How do we make the Volt cheaper?

Two quick notes on things that happened this week. The first represents the present; the second (hopefully) the future.

Chevy Volt pricing:

Its $41,000. No surprise there. There is a tax rebate that gets this down to $33,500. The leasing option seems cheaper, but seems limited to 12,000 miles a year. I drive 18,000 a year and I rent (which means no charging at home for me). I will not be in line for one anytime soon.

The Nissan Leaf is $33,000 before rebates and $25,500 after. This seems so much more manageable, but its only a 100 miles range. You win some, you lose some. What we need is a cheaper battery.

Which leads me to…

A discussion of the future of the battery:

Those who follow this blog know that most of us at LBNL work as part of a large program called the Batteries For Advanced Transportation Technologies. The Program is funded by the US DOE and has researchers from all over North America. It’s the top battery people from Universities, National Labs, and companies. The team reads like the who’s who of the battery world. The goal of the Program is to perform the research needed to discover and make the next-generation batteries.

This week on Tuesday, all of us met for a day at LBNL to discuss the future of batteries. We discussed ways to make higher energy, lower-cost materials, methods to make the battery last longer, and the challenges with moving to new batteries that promise significantly higher energy density compared to today’s batteries. Below is a photograph that we took at lunch.

I will try to tag the picture at some point.

Venkat

If you build it, will they come?

Many of you have probably come across the piece by Andy Grove titled “How to Make an American Job Before It's Too Late” that was published in Bloomberg. In the article, the former president of Intel argues that losing low-end commodity jobs from the US is a long-term problem. He uses batteries as an example.

In the battery space, all manufacturing of lithium-ion batteries happens in China, Korea, and Japan. Since the mid 90’s when it was becoming clear that lithium-ion was going to be a dominant force in the rechargeable battery market, several US companies have tried to enter the market by setting up plants in the US. None made it big. Some went under; others went back to their core business; still others survived (and continue to do so) on small government projects.

An article written by Ralph Brodd examines this issue in detail. The article is a bit dated, but is interesting reading. Ralph concludes that there are many complicated factors that come into play. Some of these involve the difficulty in penetrating OEM markets (that were all in Japan) for US companies and the fact that lower profit margins were sustainable in East Asia. Interesting he also notes that labor costs are not as significant in this “outsourcing” trend as some claim. I suppose if you automate you can depend on robots not to ask for a minimal wage irrespective of the geography!

Long story short, by the turn of the century, the battery community had accepted the fact that there was no real Li-ion manufacturing in the US. However, most of the community also believed that innovation in batteries happens in the US, and manufacturing (read “low end jobs”) was dominated by Asia.

There are very good reasons to believe that. The materials that power your laptop and cell phone batteries were discovered in the US. Some of the materials that may end up powering your plug-in hybrids and your electric cars were discovered in the US. Ergo... the US leads in the “high value” innovation; Asia does all the “low end” manufacturing.

Andy Grove had come to LBNL last Fall and during a discussion on battery research, he asked what the rest of the world was doing. I answered (echoing the popular belief) to the effect that Asia (read China, but also Korea and Japan) leads manufacturing and the US leads innovation. He cautioned that this was exactly what the semiconductor folks thought, but in time, they started to realize that Asia was starting to do more than just low-end stuff. And he cautioned that the realization might come too late.

What he was talking about was already happening in batteries; it’s just that I was not paying attention. Japan was always a powerhouse in battery R&D (with the Korean’s not far behind), but the last few years are showing that the Chinese are doing just fine, thank you. The number of papers coming from China is increasing and there is a lot more research activity than even a decade ago.

In effect, it is possible to outsource not just “low-end” jobs, but even “high value” R&D. Certainly the last decade has shown that industries ranging from software to pharma are outsourcing their research to China and India.

One could argue that quantity does not imply quality, and impact of papers from the US tends to high compared to most of the world, especially the developing world. But I would argue that as each year goes by, you can expect to see the quality and the impact improve. With money comes equipment, personnel to hire, ability to travel to conferences, and the ability to collaborate with the best and the brightest the world over. And despite the recession, China has continued to grow. If you are looking for money, China is the place to be.

If the manufacturing is in Asia, the talent is in Asia, and the funding is in Asia one can logically assume that future breakthroughs will happen in Asia.

The question then becomes: How does the US get back on the driver seat?

The US DOE decided that one way to do that was to bootstrap the development of a battery industry in the US by providing stimulus money to build factories. A few different companies got funded as part of this effort. These companies will be ramping up manufacturing of vehicle batteries in the coming years and slowly but steadily, the US will ramp up battery manufacturing for next-gen cars. Over the last week, the government issued a report on the impact of all this funding and their expectation of battery performance and cost over the next 5 years. The report, predictably, paints a rather optimistic future.

However, there a couple of problems to worry about. For one, the batteries that are being made have to be sold (Sounds obvious, but I think its worth reminding ourselves of this). For this to happen, there has to be a market for plug-in and electric cars. And as we pointed out these cars will be expensive because of the battery cost. Mass manufacturing will decrease the cost, but for mass manufacturing you need someone to buy these batteries and so you have a chicken and egg problem. And even the decreased cost will still make these cars expensive.

Moreover, most (if not all) of these companies are essentially using the money to build a building, and buying equipment from China, Japan, and Korea to make batteries pretty much exactly as they have been made in Asia except that they are doing it on US soil. Even the chemistry for the anode, cathode, and electrolyte that are being used for are not really unique.

Its not clear is there will be any unique intellectual property that will come out of this. Maybe in time, IP will come, but in the short term there will be little that is different from the batteries made in Asia. These will be expensive batteries with no clear technology advantage over the Asian rivals, but made in the US of A.

But the funding will create jobs, reduce battery costs, allow us to start the process of innovation and IP generation, and provide a pathway for the wonderful research in the Universities and National Labs to reach the marketplace. In the long run, all this can only help.

But in the short run, it is not clear which markets these companies will sell their batteries to and how they will stay in business long enough for all these benefits to occur. I believe that a vibrant PHEV or EV marketplace is key, but it’s not clear how one should enable this. None of the solutions are easy (e.g., a gas tax). But does appear that without incentives, it will hard to jumpstart an electric economy. We may be forced to make these hard choices.

This would be the “If you build it, they will come” route.

Instead of going this route, one could try to do something radically different; generate IP; use this IP to manufacture in the US, and leapfrog Asia. Leapfrogging in batteries is not easy (I suppose by its very definition leapfrogging is not easy!) and as I have noted, Moore’s law is like Murphy’s law for battery folks (we cringe at the mention of both). But one can imagine a new material or a new way of assembling a battery coming along that makes the existing methods obsolete and makes the US the leader in manufacturing as well as research.

There are a few governmental programs that are aiming to do just that. And certainly the whole of Sand Hill Road (which would be the street in Menlo Park that houses many of the Venture Capital firms in the SF Bay Area) is looking to see if they can find the next big startup with the winning idea. Only time will tell if the numerous startups and projects that are attempting to do something radical will end up being truly disruptive. And as I mentioned in my post on David vs. Goliath (or Tesla vs. Toyota), succeeding in the battery space can be hard.

In the meantime, all of you can do your part to keep the battery economy moving. Pay the $40K or $100K (depending on your affordability) and buy a Chevy Volt or a Tesla Roadster. This may mean selling your home, but, as the last few years has taught us, home ownership is overrated anyway.

Venkat

Have Solar Panel. Need Batteries.

I'm on vacation in the east coast of the US for the week and the sun has been relentless. I can only hope to have clouds and maybe a shower or two to cool things down.

But mention clouds and the solar photovoltaic folks start to go berserk. Apparently solar panels have a hard time being of any use when there is no sun! An hour of clouds and your power generation tanks. Two days of rain can make dependance on renewable electricity seem like a return to the dark ages.

Enter batteries. Why not store the electricity during the times we generate it and use it in the night/when there are clouds etc? Sounds like a great idea, but the problem is... you guessed it... those batteries!

Anyway, long story short there are some batteries (different from vehicle batteries) that have the hope of being very useful for these sort of renewable storage applications. We are talking about MWh of storage (the M is for mega, so... big). There are a lot of batteries that are needed for this application, but the cost of these batteries is a problem and so is the lifetime. A third problem is that the energy efficiency of these batteries is not that great (maybe 50-70%). When someone tells you that the energy efficiency is 50% it means that you use twice the energy to charge the battery than you get on discharge. So 50% of your solar panels are a waste (great for the solar panel maker. Bad for the customer).

ARPA-E, the new kid on the DOE block, came up with a solicitation looking for ideas to fix these problems. This week, they announced a bunch of awards for some interesting new technologies that promise to solve these problems. One of the awards went to your faithfully (that would be me) along with two of my colleagues from LBNL- Vince Battaglia and Adam Weber. For the project we assembled a team consisting of Robert Bosch, DuPont, and 3M. We also had Proton Energy has a partner to help with some designs. Its an amazing team that beings together knowledge of electrochemistry, catalysts, membranes, and balance of plants to work on a battery called a "flow battery".

I will try to expand on what we proposed in the near future. If we (and any of the others funded) are successful, then we can get a step closer to having a more efficient grid. Click here for the list of awardees.

Till now, my blog has concentrated on vehicle batteries. I think its time I expanded into grid electricity. This is another big problem and something that needs attention.

In the meantime, for all your solar enthusiasts that complain about your batteries. Hold on... hold on. Give us a few years and we hope to have something for you.

Venkat

A 200 mile EV or a 13 mile PHEV? You choose.

The big news of the week (after Brazil loss in the World Cup and the iPhone 4 antenna issues, I suppose) is the IPO of Tesla . With a IPO price set at $17 per share, Tesla saw its shares increase to $30 at some point. On Friday, it was back down to $19.2 a share, but I think we can all conclude that this was a successful IPO. The company got some much-needed cash and the early investors cashed out. The 1st week run reminds me of another greentech "success" story- A123 Systems.

A lot has been said by various analysts on the problems with Tesla (e.g., They have not yet made money and have no chance of making money for the next 3 years), but I think the IPO shows that its possible for a small company to compete with existing players. The same can be said for A123.

Just because a company has a successful IPO does not mean that it is really successful. Tesla has a lot of problems to deal with, chief among them the fact that their cars are a tad bit expensive. Similarly, A123 continues to bleed cash and competition is increasing. Its not clear when one should consider a startup to be successful. Is it when they start becoming profitable, or is it enough if the investors, founders, and early employees make money?

Anyone who has worked at a startup knows that its a roller-coaster ride. Its not the proverbial "two steps forward, one step back". Its more like "ten steps forward, nine steps back". Everything seems magnified. A million things have to come together to be successful. Often times one has to change direction (remember that A123 was not a LiFePO4 company when they began) and this can be hard to do. Suffice to say, start-ups are not for the faint of heart. For all the guys who went through this ride, getting to an IPO will probably be considered an amazing success (well... I suppose 6 months from IPO would be a more accurate date because that is when you can sell).

For the rest, being profitable may be the criteria for success. Obviously this is no easy task. A lot has been said about the ability of a Tesla to take on, say, a Toyota (or a Tata, depending on the market) or a A123 to take on, say, a Sanyo (or a BYD). All these are valid questions and make for interesting speculation. But I think the approach taken by Tesla and that by Toyota exemplify the differences between a start-up versus a traditional giant.

We all know Tesla's approach well. They want to commercialize a pure EV with a 200 mile range. They buy laptop batteries with energy approaching 180 Wh/kg and make battery packs with energy approaching 150 Wh/kg with a total energy of 56 kWh for the pack. Assuming that their car design gets them ~250 Wh for every mile*, they are pretty much using all the energy of the battery with very little guard-banding (meaning, they use close to 90-100% of the battery capacity).

Contrast this with the news that Toyota is coming out with a Prius PHEV using a Li-ion battery. Total driving range on the battery-13 miles! Toyota argues that most commutes are less than 10 miles, but a look at the battery specs is revealing.

It appears that the Toyota battery pack is ~330 pounds and has a energy of 5.2 kWh which means that the gravimetric energy of the pack is ~35 Wh/kg! I can only assume that this is useable energy (meaning the battery will have more energy but only 35 Wh/kg is used)

Granted that Toyota would want a battery that lasts 7-10 years and so unlike Tesla, they probably are using a battery that has a lower energy than 150 Wh/kg for the pack. But one would have to think that they are atleast using something that should be greater than 100 Wh/kg. Which means that Toyota is really only using 35% of the total battery capacity (at best). Talk about guard banding!

Just so we are all on the same page, you can get 35 Wh/kg from a Ni-MH battery. One is left wondering why Toyota would want to use a Li-ion battery with such a low State Of Charge (SOC) range of operation. One can only speculate, but it would logical to think that this is one way to get the life to be better. They will operate at a lower voltage and not allow the SOC to swing too much (remember the battery rules: don't charge them too high, don't swing them too wide...).

Moreover, if the battery is only charged to a partial SOC, then if there is a safety incident (leading to, what is referred to in the industry, as a spontaneous disassembly. For the normal person, this could be called an explosion) then the lower state of charge helps decrease the impact of the incident.

All this makes sense, but what is telling is that Toyota is being very very safe in their move to a Li-ion from a Ni-MH cell (by starting with a battery that is comparable). One wonders if this is more a PR move to tell the world that Toyota is moving to the latest and greatest battery, rather than using these batteries to actually get more performance.

Compare this to Tesla which is buying laptop Li-ion batteries (which are typically the highest energy density battery you can get your hands on) and trying to squeeze as much from them as possible. One is going for incremental, the other revolutionary, one prefers an appliance-like vehicle, the other a "sexy" ride, one could be considered boring, while the other could be considered a bit brash. No prizes for guessing which one is which.

Its easy to see Toyota's point of view. All you have to do is open the newspaper (I use "open" to mean clicking on a web link) to see their recent trouble with, this time, the Lexus brand. Toyota is got to be thinking that the last thing they need is a battery-related issue. Better to be safe and boring than sexy and sorry, I suppose. They cannot afford another recall.

This difference between a startup and an established player probably resonates across all areas, not just batteries. Remember Amazon in the late 90's taking on the big box retailers, or any of the open source softwares (Firefox or Linux) taking on Microsoft.

The only difference: If you screw up your internet software all that happens if your browser crashes or worse, you are infected with a virus. If you screw up your car, things can be a little bit dicey!

Time (next 3-5 years) will tell if these newer kids on the block will succeed in being profitable. Personally, I'm keeping my fingers crossed.

Venkat

Disclaimer: I don't own shares in Tesla, A123, or Toyota (as far as I know. My retirement plan is a complete mystery to me). As a matter of fact I make it a policy of not investing in greentech. My instincts tells me that they are a good buy, but I have a policy of doing the opposite of my instincts so...

* The previous version read "250 miles for each Wh". Its actually 250 Wh for each mile.

In batteries, 2+2=1. Actually more like 1/2. Well... maybe a bit less.

This is a blog post I've wanted to write for a decade. The reason I haven't (other than the obvious problem that a decade ago, I did not know what a blog was!), is because its a tough post to write. But, folks tell me that I have a gift for explaining things (I use the world "folks" is a generic sense to indicate a number greater than 0), so I shall try.

Everyone wants to make a better battery. What they mean when they say "better" is a battery that has more energy. This is what many (not all) battery researchers are trying to do, and this is what every user wants. If you read my post titled "A Moore's law for batteries? Maybe not", you will know that the game is to find new materials that make up the anode and cathode of a battery.

The idea here is to find a new material that has more capacity than the existing material and/or find one that operates at a higher voltage. Capacity is a measure of the amount of charge (electrons) you can get per gram. More is obviously better. Capacity times the voltage is energy; for real-world applications what matters is the energy. Typical numbers for capacity for lithium-ion batteries would be 140 mAh/g for the cathode and 330 mAh/g for the anode. The typical voltage of a lithium-ion battery is 3.7 V.

A lot of research in lithium-ion batteries is focussed on increasing the capacity. There is also an active area of interest in increasing the voltage to above 3.7 V. Increasing the voltage is going to be hard (very hard), so increasing the capacity appears to be the way batteries will improve, atleast in the short-term.

Simple enough.

Those of you who are paying attention have probably noticed that for every gram of material, you only have ~1/2 the capacity in the cathode compared to the anode. If you want to make a battery with a capacity of, say 330 mAh, then you have to take 1 gram of the anode, but you need 2.35 g of the cathode (330/140). What this means is that you have a total weight of 3.35 g to get a capacity of 330 mAh. So the capacity of your battery is actually 98 mAh/g (330/3.35). So you started with a anode at 330 mAh/g, a cathode at 140 mAh/g and you get 98 mAh/g for the battery. A 2 mAh/g cathode with a 2 mAh/g anode give you a 1 mAh/g battery. 2+2 is actually only 1. Certainly not 4. Not even 2! Welcome to batteries.

If you have a new anode with say 10 times the capacity (so 3300 mAh/g) you can do the same math and you will get a cell capacity of 134 mAh/g (for a battery of capacity 3300 mAh the weight is 24.5 g). You go to all this effort to make something 10 times better and you get to use your iPhone for an extra 30% talk time. A bit disappointing! On the other hand, if you had an cathode that was, say, twice as good, at 280 mAh/g (with an anode at 330 mAh/g), then your cell capacity goes up to 151 mAh/g. Much better. 50% better. This is why most researchers want to find a better cathode. Its more bang for the buck.

All this is pretty simple. All battery folks know this. 2+2=1. End of story.

Or is it? There is another small factor that even battery researchers sometimes miss. This factor is the dead weight in a battery.

If you really want to use the anode and cathode, you need some extra real estate. Things like separators to keep the electrodes apart, current collectors to collect the current, and packaging to make sure you contain it in a neat little package. All these add weight and volume. It doesn't matter if you have 10 times the capacity in a new anode, you still have to carry this dead weight.

This is a lot like a gasoline-powered car. Only the gasoline has any useful energy in the car. But to use the gasoline, you need a tank, an engine, the wheels, the drivetrain.... you get the point.

Obviously, if you can make the weight of the rest of car as light as you can (no seats?), it helps you get more from your tank of gas. Similarly, if you can minimize the amount of unwanted weight, it helps a lot in the battery. What this means is that you try to increase the ratio of the active materials (the anode and cathode) to that of the inactive material (the separators, current collectors etc).

But there is a catch. Turns out that you can't increase the amount of the active material willy-nilly. It has to do with losses in a battery. If you put extra active material in, you have to add a bit of the inactive with it. And increasing the amount of active materials involves making the anode and cathode thicker and there is a limit to how thick these can be made before losses become prohibitive. One needs to account for these factors.

*Geek meter on*

Remember the example above where we calculated 98 mAh/g using a battery of capacity 330 mAh with a weight of 3.35 g? If you do the math on the extra weight for the inactive material, you have to add an extra ~3.35 g. You can do the math to convince yourself of this number or you can trust me. I would suggest doing the latter. So you actually only get a capacity of 49 mAh/g (1/2 of 98)! 2+2=1/2!

For you battery geeks, you can verify these numbers by calculating the theoretical energy of the battery using the 98 mAh/g and multiplying by 3.7 V to get 360 Wh/kg (the theoretical capacity of a graphite/LiCoO2 cell). You can calculate the practical capacity by multiple 49 mAh/g by 3.7 V to get ~180 Wh/kg (A typical value for a 18650 cell using cobalt oxide). Well well well... the math works, does it not?

Here is the rub. Remember the example where we had an anode that has 10x the capacity. We had a cell capacity of 134 mAh/g. If you do the calculation for the extra weight and recalculate the capacity you get only 55 mAh/g.

You have to think about this a little bit, but it turns out that if you have more capacity you will need less of the anode, so now the inactive weight becomes a larger fraction of the total weight of the battery. You could have compensated for this by taking the same weight of the anode and just talking a lot more cathode, but like I was saying, this is impossible because it increases the losses in the battery to a point where it would be useless.

So we have an anode with 10x the capacity and we gain 12% in cell capacity (and don't get me started on the voltage! That is for another post).

If you don't believe me, do the math. If you don't know how to do the math; I guess you have to believe me! It would be embarrassing if someone spots an error; but then again I'm assuming that no one has actually made it this far.

If you do the same math on the battery where instead of the anode being better, the cathode is twice the capacity, where we calculated a cell capacity of 151 mAh/g without the inactive weight you will calculate a cell capacity of 68 mAh/g with the inactive material. So you made a cathode of twice the capacity and your cell capacity actually went up by 38% (remember we calculated this to be 50% better before).

Turns out that even if you make a battery with 3300 mAh/g for the anode (in a sense, this is close to the best Li-ion anode we know of) and a cathode of 280 mAh/g (the best Li-ion cathode we know of) we get a cell capacity of 110 mAh/g. 2.2x the present-day battery. But this assumes the voltage of the two are the same. In reality the materials that have this capacity have a lower voltage, which means that the energy is not really that high. Turns out that this best base scenario battery is better by maybe a factor of 1.8 to 1.9. Meaning, this battery will approach 340 Wh/kg.

*Geek meter off*

As a matter of fact, everything else being equal (i.e., amount of inactive material), the best Li-ion battery we can dream of making in the future, based on what we know as of late June 2010, will have a energy density of ~340 Wh/kg. If you want something better, you pretty much have to work on the inactive material. All these are for cell-level numbers. If you go to a battery pack, things get even worse, but that is for another post. If someone tells you that they can make a battery where the energy is greater than this, you better dig.

Most people, including battery researchers, don't think about this extra weight. Its actually a very important factor in a battery. There is such a great focus on new materials that folks forget that reality may be as good as your simple math leads you to believe. In addition to new materials, we have to think about ways to decrease the inactive materials in a battery. There is far too little research on this and a lot to be gained from doing something about it.

So next time you hear about a new material with more capacity, ask not how much more theoretical capacity you can get, instead ask how much practical energy you actually get. Remember that you can't just divide theory by 2 to get practical; it could be less (a lot less). And don't forget the voltage. Its also critical.

To help you, here is a link to a excel spreadsheet that has a battery simulator specifically for a lithium-ion battery. I hope the mac version of excel is compatible with a PC. The sheet that has the calculations is protected. Contact me to unprotect. Let me know if you catch errors. The simulator makes a LOT of assumptions. If you want them all relaxed, contact me.

Venkat

You say potato, I say...battery?

Saw something interesting in the news on a potato battery. Its a Zn-Cu battery with the two rods inserted into a potato. Why is this new? The authors say that they boiled the potato and were able to get less resistance and more power! I swear I'm not making this up.

Check out http://jrse.aip.org/jrsebh/v2/i3/p033103_s1 for the abstract. They say its cheaper than a AA battery and can be used to power a low-power LED light. I have not dug into the numbers to see if the cost claims are right. It would seem that with the low power that one gets from each cell you will need a lot of potatoes; the authors say they need 5.

My dad is visiting us from India and is sitting across from me. He tells me that 5 potatoes in India costs Rupees 15 (~30 cents). He tells me that a AA battery is either a bit cheaper or comparable! And I still need to buy some zinc and copper (and a pot to boil the potatoes, and spend some money heating it)

I get the impression that this is sort of a cute press release of something we already know and I wonder if it solves anything. I have to boil the potato and so need energy; I gain a means of making electricity, but I lose food to do that. And we really need someone from countries in the developing world to tell us if the cost numbers are what my dad tells me they are in India.

Anyway... could not resist.

Venkat

Made in Afghanistan

Many of you have probably heard the criticism against lithium batteries in that we are now dependent on a single resource for our energy storage needs. The trouble being that we substitute from one imported reserve for our transportation needs to another. And lithium is abundant in Bolivia and China (on the Tibetan plateau)- Two countries where US influence is weak. Now comes a report in the New York Times that the US has found vast reserves on lithium in Afghanistan. See http://www.nytimes.com/2010/06/14/world/asia/14minerals.html?hp

They also found copper, cobalt, etc., but its the lithium part that is intriguing to me. Apparently the reports coming out are that there is "potential for lithium deposits as large of those of Bolivia".

Now, in the short-term (i.e., a few lithium-based batteries in cars) there is no reason for any concern or interest in this story. There is more lithium than we need. If (and this is a big if), there is a significant conversion of the automotive fleet to batteries, lithium-based ones make the most sense. In this scenario, we can get lithium limited. But we are not talking about just running out of the metal (which could happen if we convert all our cars), its more the question of: can we mine the metal at the rate we will consume it. Obviously, just because we find deposits, this does not mean we can exploit it.

We shall have to wait and see what this means to the USGS estimates of lithium reserves. And I wonder if proximity of resources will play into which countries will take a lead in battery manufacturing. In the mean time, I'm sure all you conspiracy theorists will have a field day speculating on the cause for the war in Afghanistan.

Venkat

Tesota or maybe Toyola?

Logged onto New York Times and was amazed to see that there is a tie up between Toyota and Tesla.

See link

They plan to produce the sedan EV in the NUMMI plant in Fremont, CA. NUMMI is close to where I live and I'm happy to see something happening to this shuttered plant.

Its good news for Tesla and for Toyota. Hopefully, this will be a fruitful relationship.

I've visited Tesla and sat on the passenger seat of their roadster (I suppose they did not trust me with a $100,000 car). It's an amazing ride. Its easy to fall in love with the car and the concept (the price tag notwithstanding). Despite Toyota's recent troubles, I've always thought they are very good at what they do.

Lets hope that this move will get us closer to an EV I can afford (and trust me, if I can afford it, so can you).

Venkat

John Newman wins the Acheson Award

Professor John Newman has been selected to receive the Acheson Award of The Electrochemical Society. This prestigious award will be given to Professor Newman at the next meeting of the Society, to be held in Las Vegas during the week of October 10-15, 2010. Professor Newman’s greatest contribution to the “objects, purposes or activities of The Electrochemical Society” (i.e., the definition of the Acheson Award, as spelled out below)” has been his seminal approach to the analysis and design of electrochemical systems. Starting in the 1960s and continuing to this day, John has not only clarified the physicochemical laws that govern the behavior of electrochemical systems, he has also demonstrated how to use these laws to correctly formulate and solve problems associated with batteries, fuel cells, electrolyzers, and related technologies. His sophisticated approach to mathematically analyze complex electrochemical problems has been universally accepted by the academic and industrial communities, to the extent that it is now commonly referred to as “The Newman Method.”

John is a Professor of Chemical Engineering at the University of California Berkeley campus, a Faculty Senior Scientist and Principal Investigator in the Environmental Energy Technologies Division of the Lawrence Berkeley National Laboratory, and Director of the Department of Energy’s Batteries for Advanced Transportation Technologies Program. He is the author or co-author of more than 390 technical publications, numerous plenary and invited lectures, and the book Electrochemical Systems, which is now in its 3rd edition and is used throughout the world as a monograph and graduate text in electrochemical engineering. Professor Newman has mentored many graduate students, as well as post-doctoral fellows and visiting scientists. Additional details about Professor Newman and his research group can be found at http://www.cchem.berkeley.edu/jsngrp/

The Edward Goodrich Acheson Award of The Electrochemical Society (http://www.electrochem.org/awards/ecs/ecs_awards.htm) was established in 1928 for distinguished contributions to the advancement of any of the objects, purposes or activities of The Electrochemical Society, and it is awarded not more frequently than biennially. It includes a gold medal, a wall plaque, and a prize of $10,000. It is named for Edward Acheson, a U.S. inventor best known for the invention of the highly effective abrasive material Carborundum. Acheson also helped develop the incandescent lamp.

Beside the Acheson Award, John has received 9 other awards from the Electrochemical Society. He also was recognized as a Highly Cited Author, as identified by Thomson ISI; during 2002 he was an Onsager Professor at the Norwegian University of Science and Technology in Trondheim; and in 1999 he was elected to the National Academy of Engineering.

The Acheson is arguably the most prestigious award that an electrochemical scientist could hope to attain, short of a Nobel Prize or a National Medal of Science. The late Professor Charles W. Tobias (in 1972) is among those who have received the Acheson Award, and he the only other member of the Berkeley electrochemical community to be so recognized.

LBNL everywhere...?

ARPA-E announced the results for their latest round of solicitations that they issued a few months ago on transformational energy projects. One of the areas was batteries for vehicles. 10 projects were identified to receive the award (Here is the list). 3 of these (that I can talk about) have an LBNL connection. Its a proud day for what I consider the top battery program in the country. Turns out that the number 3 is not the full story, but I can't talk about any other connections that may (or may not) exist. Welcome to the world of startup's and confidentiality and stealth.

That's the quick summary. Here are the details. ARPA-E stands for Advanced Research Projects Agency-Energy, is the DARPA (Defense Advanced....) of DOE. I guess no one liked EARPA! Their mission is to (I copy and paste here):

- Enhance U.S. economic security by identifying technologies with the potential to substantially reduce energy imports from foreign sources; cut energy-related greenhouse gas emissions; and improve efficiency across the energy spectrum.

- Ensure the U.S. remains a technological and economic leader in developing and deploying advanced energy technologies.

This is the official spiel. In reality, ARPA-E is the agency that is supposed to help identify the next transformative idea related to energy technology. Think, the next transistor, or the next light bulb, but related to energy. You get the picture. These bullets above also do not convey the level of buzz this new agency has generated in the battery community. We have been energized. Getting ARPA-E funding is now considered to be a big deal. A very big deal. There are huge bragging rights for the winners, and those who are finalists.

No officially numbers have been released, but my sources (is that an euphemism for "I pulled it out of you-know-where"?) tell me that 350 concept papers came in the battery area. Of these 70 were down selected for submitting a full proposal. Of these 70, 10 were funded (ARPA-E folks: Please feel free to correct this). Less than 3% of ideas are funded! Now you know why being one of the 75 is a big deal and being one of the 10 is an even bigger deal. So you can see why its a proud day for LBNL when we have 3 funded proposals that we are involved with.

LBNL was involved in 6 submissions in the concept paper stage. All 6 were selected for submitting a full proposal. 2 of these 6 were selected to receive an award. The first of these is a project on a lithium sulfur (Li-S) battery that was led by Sion Power. Li-S is a chemistry that promised very high energy density, but has a lot of problems that hinder it from being commercialized. Sion is in the forefront of developing this technology. They will be working with John Newman, who is, for those of you who don't know, the father of electrochemical engineering (For those who track these things- I consider Charles Tobias to be the grandfather of electrochemical engineering). He wrote the book on the subject, literally. If you don't believe me, check this link. John Newman will be helping Sion with modeling their system. Systems like Li-S, if commercialized, can solve the problem of range for EVs and can help us adopt this technology.

The second is one from Applied Materials. They want to develop a manufacturing process that will lead to low-cost batteries that have high energy. Cost, as I have pointed out again and again, is one of the show-stoppers that prevent large scale adoption of EVs and PHEVs. Addressing this issue is critical. Applied will be working with Gao Liu and Vince Battaglia- both experts in making battery electrodes and cells.

These are the two where LBNL appears in the list. But there is one more that is hidden (that I can talk about). This is Polyplus, which got funded to develop Li-air batteries. Polyplus is a LBNL spinoff started by Steve Visco and Lutgard De Jonghe . Some of the underlying work that led to the formation of Polyplus was conducted under, what is now, the BATT Program. Li-air is the Holy Grail of batteries- a system that has 10x the energy density of today's batteries on a mass basis. Polyplus is pretty much the top company in this area. If they succeed, we can make a big dent on the range issue with EVs.

Three very different projects; but they all promise to change the world if they succeed. The fact that the reviewers have picked so many of the projects that LBNL was involved with is a testimony to the cutting edge research that happens here. Congrats to all the winners. And did I mention that this is not all. There may (or may not) be other connections. Stay tuned.

In a future post, I will delve a bit more into these technologies and provide my thoughts on what the critical challenges are and what (I think) their approach will be.

Venkat

Lithium-lithium everywhere...

Over the last 15 years the whole battery community has slowly starting looking at one single system: the lithium battery. I remember going to an Electrochemical Society meeting in 1996 to present a paper on Ni-MH batteries. My talk was scheduled for Monday AM (read prime time). By 1997, I was down to Wednesday, and by 1999, I was talking Friday PM with 3 people in the room (yours faithfully, the presenter before me, and the one after me. Even the session chair was missing!). If one was looking to read the signs, this was it.

This week I was talking to someone who was interested in electrochemical capacitors (more on this later) and he asked if all the research was only on lithium batteries or do we do anything else? I had to admit that there was very little that goes on other than lithium. Since that conversation, I've been thinking about the effectiveness of having all our eggs in the lithium basket and wondering if this is a good thing.

First off, I should note that when it comes to batteries, lithium has a lot more energy per weight or volume compared to the other batteries we have been looking at in the past. Its got 4-5 times the energy per mass as a lead-acid battery and 2-3 times that for a Ni-MH battery. There is still a lot more that can be done with this chemistry and so there is a reason for us to obsess about this. When it comes to batteries for a plug-in or an electric car, we need all the energy we can get and working on lithium does make a lot of sense.

But does this mean that there are no advances that can be made in other energy-storage technologies? And even if we do make advances in these other areas, does it really have any impact in the world? Let's look at the second question first.

Remember that we have argued that batteries for plug-in and EVs are going to very expensive and that they may not last very long either. Its far from given that we will indeed be driving in these battery-powered cars. We may not be cost competitive with gasoline for a while, and we may end up seeing that these cars as a niche market. Maybe hydrogen will take off as a carrier and batteries as a primary energy source will not be the future. The future is far from clear, but it is possible that we may end up finding out that hybrid vehicles (like your out-of-control Prius) may be the most common vehicle on the road for a decade. But even your Prius is not as popular as it could be because its expensive.

But when it comes to hybrids, its not energy that is critical, but the power. Many batteries, including the lead-acid and the Ni-MH batteries have the power capability to satisfy the requirements for a hybrid. The cheapest battery we know of is the lead-acid battery. So if we can get the power with a lead-acid battery and if its the cheapest battery we know of, why don't we use this for hybrids?

Remember the post on battery rules where we asked you to "keep you lead-acid charged"? You may also remember that this was important because if the lead-acid is ever discharged, it sulfates and causes capacity loss. In a hybrid, the battery is always sitting partially discharged. This is important because if you hit the brakes, you need to be able to accept the juice in your battery. Hybrid batteries operate around 50% state of charge because of this. Try using a lead-acid at a partially discharged state and you will have a dead battery long before the new car smell fades.

But something strange happened to the lead-acid battery when the rest of us were obsessing over the lithium battery. The companies working on this started using activated carbon in their negative plates. Lo and behold!, these companies started seeing much better cycling with this new concept. Some companies are doing variations of this by replacing the negative electrode with activated carbon so that its a hybrid between a battery and a capacitor. Companies doing this are promising all the cycle life you need at 1/4 the cost of the Li-ion for hybrids! The catch: they don't yet know if the batteries will last 10 years. So they can get the cycle life, but its not clear they can get the calendar life.

But that is not the point I want to make. What amazes me is that someone can take a 150 year old technology and show that they can make it better by solving a particular problem that stops it from being used for an application. I'll take a bet that 90% of the researchers in the field of batteries don't know of this advancement (all right, that may be a bit of an overstatement, but you get the point). I had worked on a mathematical model for a lead-acid battery a few years ago where I had included some features in the model that make it easy to address this advance. A person in the lead-acid industry had sent me a mail when these findings started coming out asking if I was doing anything to address these new findings. I had to (sadly) tell him that although this was interesting, I had no way of doing anything because all my funding is in the area of lithium batteries.

But what if we find out that the new lead-acid batteries do have a calendar life issue. Should we leave it to companies to figure this out by themselves, or should battery researchers be helping with this effort to see if we can find a solution? It seems to me that the answer has to be the latter, but I fear that this will not be the case. The chemistry is considered too "un-sexy" (for want of a better word). Try presenting a paper on this at the Electrochemical Society meeting and you will asked to present on a Saturday morning (after the conference has ended!). To be fair there has recently been government support for these technologies for trying to commercialize them; but I don't see anything happening at the research stage.

The story of the lead-acid is far from unique. The few (very few) folks who continue to work on the Ni-MH system talk about the use of carbon fiber instead of nickel plaques to decrease the weight and cost of the battery and increase its specific energy. The person working on capacitors was telling me that he had ideas for increasing the energy by the factor of 2 (which, as it turns out, could be huge for a hybrid). There are companies working on Ni-Zn batteries that think they can do something better than Li-ion in some applications. But look at research in the US on batteries and there is pretty much zero effort in these areas. None of these ideas may pan out, but the question remains: should battery researchers be looking at these issues along with companies or should we all focus on one system (the lithium system)?

Part of the problem is the amount of funding that is available for battery research. If there was unlimited funding available, all these problems will be looked at. But with funding being tight, one needs to focus on a few problems and not spread one-selves too thin. Another problem is the community. As in any other area, there is a bit of jumping on the bandwagon that happens. Its tough being the only guy doing something, especially when no one cares for what you do.

At LBNL I wear two hats: one as a researcher looking at mathematically modeling batteries and another as the technical manager of the Batteries or Advanced Transportation Technologies (BATT) program. In my latter role, I have a hand at picking the kind of systems we work on. And I know exactly why we have picked to focus on the lithium battery exclusively. But the advances in these less "sexy" fields makes we wonder if this strategy is right. Weigh in with your views.

Venkat

Nano for batteries: the challenge of volumetric density

In my previous post I discussed some of the pros and cons of using our skills making materials in various nanoarchitectures in Li-ion battery technology, mainly related to the increase in surface area and shortening of diffusion paths. Today I will concentrate in other aspects: volume and density.

Most probably, you have heard how silicon-based electrodes can boost the storage of Li-ion batteries. And you may have even noticed that a lot of the releases announcing breakthroughs in this area have the word nano in them (here's a very recent example). Indeed, one of the most serious problems of silicon electrodes is that they expand and contract enormously upon cycling because they can uptake so much lithium (hence the boost in storage capacity). In brief, what happens with big particles is that they crack into much smaller ones due to these expansion/contraction cycles (think of freeze/thaw cycles in the winter) and lose contact with the electrode additives and the electrolyte, cripling the electrode life. So starting small (i.e., nano) bypasses this issue. With less volume in a particle, it is less likely to break in several domains.

Usually, electrodes composed of nanoparticles of silicon cycle better than those composed of bigger particles... provided that we are good at building the electrode structure so that all these new particles are well connected to the current collectors (and, subsequently, the battery leads) through the electrode additives. However, issues arise when using this strategy. Guess what one of the problems is? Yes, our friends the side reactions; silicon reacts outside the voltage of stability of the electrolyte. A second problem, related to the increase in surface, is that silicon nanoparticles are much more reactive with air than micron-size particles, bringing up the need for additional safety controls during handling. In fact, some people have even proposed primary silicon/air batteries.

It is quite likely that silicon will have to be used in nanometric form to make it a viable electrode with very high capacity. But be careful with overstating the numbers. A typical strategy to keep a good electrical contact is to use more conductive additives (carbon, basically) because there are more particles to connect to each other and the current collector. Increasing the amount of polymeric binder is another strategy that is commonly used to keep the particles together. And more carbon and/or binder means less silicon, which means that we are reducing the total capacity of the electrode. Yes, in terms of the silicon only, the capacity is unchanged, but we have to count everything when building the battery! Pay attention to what companies that announce silicon-based batteries show as capacity gains and you'll see they are more modest than would be expected theoretically.

In addition, nanoparticles have a very annoying tendency to form aggregates that is very difficult to control. These aggregates form rather disorderly and, therefore, leave a lot of dead space within, which can be helpful for electrolyte wetting but also be unnecessarily high. Finally, a lot of the strategies to alleviate volume expansions in silicon electrodes rely on placing the particles far from each other, so that they don't crush against each other upon expansion. Obviously, this also helps with the aggregation, but now we have even more inactive space between particles!

The result of all these approaches is always the same: the density (mass per unit of volume) of the electrode is lowered considerably with respect to an electrode made using more traditional methods with bigger particles. In general, it is very difficult to achieve bulk packing densities of materials using nanostructured electrodes, which may, after all, be something we have to live with, in some instances, if we want them to work.

Unfortunately, lower packing density also means lower total volumetric energy density of the electrode/battery. And volumetric energy density is no laughing matter when thinking of batteries for electric vehicles. There is very limited volume available for the battery (especially in a hybrid). Using certain nanostructures as electrodes can lead to very long life, but very modest volumetric densities, so that you still need a bigger battery to power your car. When volume is factored in, the gains of using nanoparticles are systematically much more modest or even totally offset. This is a problem that is still unsolved. Scientists are getting better at synthesizing nanoparticles and we are starting to be able to control aggregation and assembly, so there are possibilities that are being explored. Now, the methods associated may imply an increase in cost of manufacturing. But I'll leave this for another day.

More reading materials for those interested in the science of silicon electrodes:

Larcher et al., Recent findings and prospects in the field of pure metals as negative electrodes for Li-ion batteries, Journal of Materials Chemistry 17, 3759 - 3772 (2007)

What can nano do for batteries?

First and foremost, I must express my gratitude to Venkat for his introduction and for encouraging me to participate in this new blog-adventure. Now that he cannot hear us, I will tell you that I learned quite a few things myself with his posts. It is a pleasure for me to offer a different perspective to his and I hope you will find it informative. Since he has already introduced me, I’ll move on to the fun stuff.

Nanotechnology is certainly one of the fields of research that has witnessed greatest progress in the last decade (although the concept itself is not all that new; Michael Faraday can be considered one of the first nanoscientists!). When it comes to functional materials, among other things, nanoscience offers the promise of enhanced catalytic properties, controllable band gaps that can have an impact on the efficiency of a solar cell and novel medical diagnostics and treatment tools (not to mention that most of suntan lotions contain nanoparticles nowadays!).

It is easy to wonder whether nanotechnology would also be a helpful tool toward better batteries. There are a few arguments in favor of using nanoparticles in a battery, particularly as part of the electrodes. We will just concentrate on a couple of them for now (and leave the rest for another day if I am still considered a guest after today!). Although the discussion relies on the Li-ion technology for examples, the ideas are pretty much applicable to many battery technologies.

One of the first incentives one can think of is the shorter distances for ions and electrons to travel through. Broadly speaking, think of it as you having to cross your living room as opposed to a football field. The second one has to with the surface area. Let’s imagine that the square in the picture below is made of 1 um edges:

divide each edge ten times and you now have 100 squares with edges of 100 nm:

All those new lines you see are new surfaces (if you want to entertain yourself, expand the exercise to a 3D cube and reduce it to particles of 10 nm). In a battery, all of this surface could ideally be exposed to the electrolyte, which is the media through which ions transfer from electrode to electrode (the key to battery operation).

Now we have (lithium) ions that can access the active material much more extensively (more surface) and have shorter distances to travel through the solid (remember the living room). Diffusion in the solid is typically, but not always, slower than in the liquid, so, in theory, the result is a lower resistance to ion transport and, therefore, better utilization of the material (i.e., higher stored charge/energy) and, potentially, higher rates of charge and discharge (i.e., shorter charging times and higher power).

There are many reports available that show that samples composed of nanoparticles, all things equal, can lead to better performance than (what we call) bulk counterparts. In materials with poor ion conduction, this effect has had an important impact. The now world famous lithium iron phosphate owes some of its glamour to the chemists that were able to nanostructure it. The same happens with an anode material that is getting a lot of exposure as of late: lithium titanate.

So in a sense, nanotechnology has an important role in the field of (Li-ion) batteries, and, in fact, there are many R&D projects that concentrate on exploiting the advantages of nanotechnology to developing advanced materials, including some in our very own Batteries for Advanced Transportation Technologies program (go through our recent scientific reports to see what's up) at the Department of Energy. So, it is settled! Nanotechnology is the way to go to make batteries with five times more energy density!

Hmmm... not so quick... Apart from the fact that geometrically increasing the energy density is much trickier than it seems (we’ll also leave this for another day), there is a key subtlety in the case of lithium iron phosphate and lithium titanate that makes the whole trick work: they are both active within the voltage window of stability of the components of the liquid electrolyte. Venkat has already told you that bad things happen when we fall outside this window. Unfortunately, one of the ways of increasing the energy density is precisely by increasing the voltage (remember, energy = voltage x charge). Graphite electrodes, for instance, ubiquitous as they may be, react outside that window.

If we start using materials that are only slightly outside the thermodynamic window of the electrolyte, the undesired reactions may happen at a rate that is slow enough for us to live with. But, hey, remember that increased surface area of nanoparticles? Yeah, it is increased for every component of the electrolyte, not just the ions. The immediate consequence of reducing the particle size of our electrode materials is that side reactions tend to be exacerbated. And those side reactions produce insoluble products that deposit, just our luck, precisely on the surface of the particles, covering them and producing layers that are resistive to the diffusion of ions. Automatically, the advantage of using nanoparticles is lost. And things can be so bad that we may be better off using slightly less active electrodes!

In conclusion, you can choose to have a lithium iron phosphate/lithium titanate battery that operates extremely well and has a long life thanks to the use of nanoparticles... but what if I told that such battery only has a voltage output of around 2 V (yeah, those lead-acid batteries don't look so bad anymore)? And if I mentioned that, in addition, the lithium titanate has about half the storage capacity of graphite, so the energy density of this great battery is lower than that in your cellphone Li-ion cells? If we are to increase the energy density of current batteries to make them more application friendly, we have to come up with inventive ways of using materials operating at high and low voltages; preferably, not in the form of nanoparticles… unless we find a way of stopping those annoying side reactions without killing the ion transport at the same time.

There are other issues that make nano only a partial answer (sorry, no Moore's law for batteries) to the performance barriers of batteries, among which are higher associated manufacturing or processing costs and lower packing densities. But this is for another post (or two!). If you are left wanting more, you can get even more knitty-gritty details by reading some scientific literature (if you have access to it, of course), which will also offer additional shades of grey to the arguments developed here:

Aricò et al., Nanostructured materials for advanced energy conversion and storage devices, Nature Materials 4, 366 - 377 (2005)

Bruce et al., Nanomaterials for Rechargeable Lithium Batteries, Angewandte Chemie International Edition 47, 2930 – 2946 (2008)