Researchers Develop Novel High-Performance Polymer Tin Sulfur Lithium Ion Battery
12 March 2010
Researchers at the Università degli Studi di Roma La Sapienza have developed a novel polymer tin sulfur lithium-ion battery that takes advantage of the high theoretical specific energy and energy density of the lithium-sulfur battery chemistry (2,500 Wh kg-1 and 2,800 Wh L-1 respectively, earlier post), while avoiding the shortcomings that have hindered commercialization of this type chemistry.
Rather than taking the more conventional approach of using a sulfur cathode and a lithium metal anode, Jusef Hassoun and Bruno Scrosati have developed a lithium-metal-free battery, using a carbon lithium sulfide composite as the cathode and a tin carbon composite anode. In a paper published online 28 February in the journal Angewandte Chemie International Edition, they report demonstrating a specific energy of the cell on the order of 1,100 Wh kg-1.
Lithium-sulfur cells are based on the electrochemical reaction:
16Li + S8 8Li2S
While Li-ion batteries use a process called intercalation to store lithium ions by inserting the ions between molecules in the electrode, lithium-sulfur batteries rely on a multi-step redox reaction with sulfur that results in a number of stable intermediate sulfide ions. This storage process, in theory, reduces limitations of electrode structure—thus enabling higher capacity in similar volumes.
In the conventional approach, at the negative electrode lithium is dissolved into solution on discharge and plated out on charge. The solubility of the intermediate sulfide ions depends on the solvent used in the electrolyte, and the voltage vs. discharge capacity profile of the cell thus depends on the solvents used.
The practical development of the lithium–sulfur battery has been hindered to date by a series of shortcomings. A major hurdle is the high solubility in the organic electrolyte of the polysulfides Li2Sx (1≤x≤8) that form as intermediates during both charge and discharge processes. This high solubility results in a loss of active mass, which is reflected in a low utilization of the sulfur cathode and in a severe capacity decay upon cycling. The dissolved polysulfide anions, by migration through the electrolyte, may reach the lithium metal anode, where they react to form insoluble products on its surface; this process also negatively impacts the battery operation.
...The key challenge is then to totally renew the chemistry of this battery such as to achieve an advanced configuration that can consistently provide high capacity, a long cycle life, and safe operation. Herein, we report an example of a lithium metal- free new battery version and demonstrate that, to a large extent, it can effectively meet these targets. In contrast to most of the Li–S batteries proposed to date, which are fabricated in the “charged” state, that is, using a carbon–sulfur composite cathode that necessarily requires a lithium metal counter electrode (anode) to assure the 16Li+S8→8Li2S discharge process, we propose to fabricate the battery in the “discharged” state by using a carbon lithium sulfide composite as the cathode.
—Hassoun and Scrosati
Hassoun and Scrosati also replaced the common liquid organic solutions with a gel-type polymer membrane. Since the lithium ions necessary to drive the electrochemical process are provided by the Li2S/C cathode, any material capable of accepting and releasing lithium ions can be chosen as anode to replace lithium metal, they said. They chose a tin/carbon nanocomposite, Sn/C 1:1 in weight. The specific capacity of the improved Sn/C electrode matches that of the Li2S/C electrode, and Sn/C has high chemical stability.
The electrochemical process is basically the conversion of lithium sulfide into sulfur with the release of lithium ions: 2.2Li2S/C→2.2S+C+4.4Li++4.4e-. The lithium ions travel through the electrolyte to reach the anode where they form an alloy with the tin metal: 4.4Li++Sn/C+ 4.4e-→Li4.4Sn+C. The total process is the reversible reaction of the lithium–tin alloy with elemental sulfur to form tin metal and lithium sulfide.
...The reported results show that this innovation is effective in controlling most of the issues that have, to date, prevented practical exploitation of the lithium–sulfur electrochemical system and give rise to a novel tin–lithium sulfide battery that provides a specific energy on the order of 1100 Wh kg-1, a value not previously achieved for a lithium metal-free battery.
—Hassoun and Scrosati
The team notes that “the road to a practical lithium–sulfur battery is still long”; optimization of the electrode morphology and cell structure are needed to further improve the cycle life and the rate capability.
Resources
Jusef Hassoun and Bruno Scrosati (2010) A High-Performance Polymer Tin Sulfur Lithium Ion Battery. Angew. Chem. Int. Ed. 49, 1 – 5 doi: 10.1002/anie.200907324
J. Hassoun, A. Fernicola, M.A. Navarra and B. Scrosati (2010) Advanced lithium-ion batteries based on a nanostructured Sn-C anode and an electrochemically stable LiTFSi-Py24TFSI ionic liquid electrolyte J Power Sources 195, 574 - 579 doi: 10.1016/j.jpowsour.2009.07.046
1,100 Wh/kg should please some people on here!
That would mean a 300 mile range EV battery pack would weigh just 54 kg.
If we can sort out the cycle life issues, it's goodbye petroleum....
Posted by: clett | 12 March 2010 at 04:03 AM
With only the range of 30 miles on electricity needed for most daily automobile uses, the plug-in-hybrid electric car has long been possible even with lead batteries. The only issue is to get a series hybrid cheap enough to compete by having it designed and built for efficient use and low cost rather than super high performance and high cost like the TESLA.
This new battery is not needed. The future high capacity will remain an illusion, and in any case will be less than hydrocarbon fuels. The high temperature sodium sulphur battery and the ZEBRA battery already have enough capacity for long range electric travel at very low costs. A modified Prius with an electric motor that can run at motorway speeds and carries as many ZEBRA cells as its design will allow would be a perfect long range Plug-In-Hybrid car. No new lithium battery would improve its performance significantly as ultimately the hydrocarbon fuel is the long distance energy source. The higher energy density of lithium is much diluted by the carbon and sulphur and other materials needed for batteries. Lead batteries are cheaper now on a cycle basis and Firefly, EFFPOWER, CSIRO and others are making them even more so.
Higher capacity batteries are not the answer that will make the plug-in-hybrid car sell. First the cars must be cheaper and then they must always be hybrid in contrast to the TESLA and the TH!NK and others to eliminate any worry at all about charging on long trips. Hybrid also means that smaller cheaper batteries can be used.
Whilst electronic conversion and induction motors may be more efficient in electric locomotives that are used all day, plain direct current electric motors with brushes may be cheaper in the long run, even, for automobiles. It is well known how to make speed controls with and for DC electric motors and generators.
A series hydraulic hybrid is the cheapest way to make a hybrid if the plug in feature does not appeal to you. The Prius was a big misstep for Toyota if it does not move on to plug in vehicles. ..HG..
Posted by: Henry Gibson | 12 March 2010 at 05:16 AM
Perhaps "This new battery is not needed.", but a new battery is needed.
Posted by: kelly | 12 March 2010 at 05:53 AM
I like the response about how "this battery is not needed" like back in the 80's: "What the hell would we ever need more then 64k bytes?" True we can start penetrating the market with EVs todays, but these batteries (or batteries of this kind of performance) is going to allow EVs to dominate the market.
Posted by: Ben | 12 March 2010 at 06:48 AM
Yes, or IBM's famous statement, "the world will never need more than 2 computers" ;)
Posted by: clett | 12 March 2010 at 07:13 AM
Henry: You keep lauding the ZEBRA battery. You do understand that it must be kept at a temperature of over 300F -all the time-, to provide any power right? If allowed to cool, it will freeze into a solid mass that will take hours to re-heat. We use our cars on average 55 minutes a day, yet this battery will require energy input to keep it at operating temperature 24 hours/day, 365 days/year.
What a waste.
Some Li chemistries may need to be kept warm when the ambient temperature is below 30F (though others work at -40F), but that'll waste far less energy than any molten salt battery.
Posted by: Nat Pearre | 12 March 2010 at 07:46 AM
@Henry,
If the Chevy Volt battery cost $1K instead of $10K+, the PHEV would be much more marketable, yes? Better power and energy density batteries will ultimately lead to lighter, cheaper batteries in all formats...so PHEV and BEV benefit.
My $0.02 is that when a BEV power source provides 400+ miles of range for less than $5K, it will kick PHEV's scrawny little rear bumper all over the place. Pure BEV has too many other advantages.
Posted by: HealthyBreeze | 12 March 2010 at 09:29 AM
Regardless of what batteries are out there, we need cheaper ones. Even lead acid aren't cheap enough. Having a lithium battery that doesn't require refined lithium metal is a good step in that direction since most easily accessible lithium exists as salts. Other issues with lead acid is the limited life cycle. Zebra batteries operates at 250 °C (482 °F) so decent insulation is required so as not to require a lot of additional energy to keep them active. I drive a Ford Ranger EV that has 1500 lbs of batteries to get me about 40 miles of travel. I wouldn't mind at all replacing that with 100 lbs of a better battery. That alone would probably get me another 50% in distance.
Posted by: Eletruk | 12 March 2010 at 11:43 AM
BEVs (and most PHEVs) do required higher performance (1000+ Wh/Kg) lower cost (as low as $100/Kwh) before they can favorably replace most ICE vehicles.
I have no doubt that technologies will be developed to produce such high performance batteries by 2020 or shortly thereafter. Many will be surprised to see what is coming next. Very large scale automated mass production facilities and worldwide competition will bring price down by 20%+/year soon.
Higher performance/lower cost solar panels + much lower cost batteries will make it possible to equip many residences with their own e-power source by 2020. Coupled with short and long range BEVs, that would negate the construction of more large centralized power plants.
The 2020-2030 decade will be very interesting with many coal fired power plants closing down.
Posted by: HarveyD | 12 March 2010 at 02:24 PM
Assuming that cycleability can be solved, such a chemistry would a allow for a PHEV30's battery to weigh 5.4lbs! (moved the zero on you, Clett ;)
Two PML wheel hub motors (50lbs each) and a small genset (100lbs) and your whole drivetrain weighs.... 205.4lbs. That's pretty damn good.
Posted by: GreenPlease | 12 March 2010 at 04:30 PM
@HarveyD
2020-2030? I think 2015-2020 will be very interesting.
Posted by: JMartin | 12 March 2010 at 06:53 PM
Key words:
The team notes that “the road to a practical lithium–sulfur battery is still long”
Posted by: Darius | 13 March 2010 at 03:22 AM
JMartin:
Historically, major changes in e-power generation and distribution took 2+ decades to implement.
Resistance to change and our acquired (non-culture) growing use of the cheapest power sources, vehicles, cheapest junk food and housing is difficult to change very quickly.
Chasing the cheapest sources of junk food have made many of us walking fat blobs with diabetes, multiple heart conditions, blocked arteries, cancers and a growing multitude of impossible to treat or cure diseases. What we're saving with cheap junk food will be spent (2x to 3x) on the extra health care required. Look at what happened to the relative Food vs Health Care cost over the last 60 years. We're now spending twice as much on health care as on food and we are twice as sick. It used to be the opposite 60 years ago.
Industrial junk food and multiple pollution are taking their toll on most living creatures. Another century of this unchecked acquired desire for the cheapest at all times may become a great danger for USA. If health care cost triples again, from current 18% to 57% of GDP by 2060/2070, not many may be able to afford a private car.
What is even worst is that those negative values are being spread across the world, making many young children fat and sick.
What an example we have given.
Posted by: HarveyD | 13 March 2010 at 01:12 PM
Harvey, you don't really think our comsumption of junk food is JUST from it being cheap, do you? It's planned that way so the drug companies can make more money; Bill Maher
Posted by: ai_vin | 13 March 2010 at 03:41 PM
ai-win:
Yes, lowest price and lowest quality are very closely related with regards to food products.
Low quality industrial and junk food, reduced food cost from 30+% to less than 10% of family net income in the last 60 years. A 46-day, hormone fed chicken, raised in darkness, weights 4.5+ lbs instead of less than 2.5 lbs 30 years ago. It is very cheap meat but is it as good as grain fed chicken that would take 76+ days to reach the equivalent weight?
The price to pay for that choice is that we are looking more and more like (hormonized) fat blobs on two legs and suffering from many associated diseases. Health care (partial in USA)cost is going in the opposite direction. Cheaper industrial food gets, fatter and sicker we get. No wonder that so many do not want national health care coverage. Unless we start eating better food in appropriate (lesser) quantity to reduce to healthy weight, there may not be enough public funds to treat everybody by 2030/2050.
Sooner or latter, industrial food will have to be better regulated. Will interested lobbies allow it? So many people are involved making junk-industrial food and treating the after effects that it will be difficult to change the trend.
Posted by: HarveyD | 13 March 2010 at 04:42 PM
Harvey
I didn't know you were so frustrated by the belly fat around. But sadly you are right, and EV won't change that fact, being from Europe but living in US I am amazed that american accept themselves being fatter an fatter, obesity problem keeps going up and show no sign of abating, 50% of the black female population is technically "obese" that is staggering. It seems that is easier for people to accept themselves than to change their bad life style even if it makes them sick and unattractive, I can't get it. But clearly the growing cost of health care will just sink the country if nothing is done soon.
Posted by: Treehugger | 14 March 2010 at 05:40 PM
Harvey
I didn't know you were so frustrated by the belly fat around. But sadly you are right, and EV won't change that fact, being from Europe but living in US I am amazed that american accept themselves being fatter an fatter, obesity problem keeps going up and show no sign of abating, 50% of the black female population is technically "obese" that is staggering. It seems that is easier for people to accept themselves than to change their bad life style even if it makes them sick and unattractive, I can't get it. But clearly the growing cost of health care will just sink the country if nothing is done soon.
Posted by: Treehugger | 14 March 2010 at 05:40 PM
Tree...:
When the majority is convinced that cheapness (lowest cost) is was makes a product attractive or more desirable than others, you have created a problem.
When the majority is convinced that lowest cost and bigness (largest size at least larger than the neighbour's) are the two qualities to look for in most products, you have created a nation where excessive corpulence and 3+ tonne gas guzzlers become the accepted norm and even the ideal goal to achieve.
For 350+ lbs driver, speeding on the highway in a 4+ tonne Hummer I or 4.5 tonne International Pick Up on 20-inch wheels becomes the fulfillment of a lifetime dream and a declaration of prosperity, wealth, liberty and power.
A growing new culture with 50+% participation in many areas.
Posted by: HarveyD | 15 March 2010 at 06:20 AM
There are high costs to low prices.
Posted by: ai_vin | 15 March 2010 at 11:23 AM
Well put, there are many costs that the consumer does not have to pay, but we all do. Maybe those costs should be included in the price.
Posted by: SJC | 15 March 2010 at 12:05 PM