Feb
5
The Battery Explosion Is Coming, Part Two
February 5, 2010 | 2 Comments
The cover story at Nikkei Electronics Asia titled ‘Winning in the Gigantic New EV Market’ examines over 16 web pages the positioning of industry in lithium ion battery production. Its a long piece so I’ll condense it down, but by all means if you’re interested in a world view seen from the Japanese point of view, with still much more than half the world’s market share, the full story is very worthwhile.
Part two begins with new materials that can boost capacity. The Japanese to their credit are already finalizing plans for large capacity lithium ion batteries. The plans are going a pace even though the Japanese are not satisfied with performance. World wide competition beware, all the factory and investment is getting answered with lower cost capacity with such confidence that plans are going ahead even as designs are racing to catch up. As we saw yesterday, it’s a market on a steep growth line, a major market answer is going to be capacity.
At the same time many of the automakers realize that lithium ion is still not good enough for long distance EV use. More energy density, power density, cost and safety improvements are going to be needed. Current technology simply occupies too much volume and expense for automaker’s comfort. The Japanese answer is new materials for the cathode, anode and the electrolytic solution.
Around the world research is focused on the post lithium ion technology with solid-state batteries, Li-metal batteries, Li-S batteries or Li-air batteries, as the current examples, all with commercial roll-out planned before 2030.
Current batteries composed as cathode and anode materials, electrolyte, separators, and other parts, and their characteristics as batteries must be carefully balanced. Sometimes a choice of a high-performance cathode material and combining it with a high-performance anode material does not result in a high-performance battery. For example the electrode materials and the electrolyte may not work well with each other, or it may simply be difficult to get commercial scale with the technology for the new materials.
Lithium Ion Battery New Material Flow Chart. Click image for more info.
The covers story says, “There is not a very wide range of commercial choice for cathode and anode material, electrolyte, etc., for use in consumer electronics. That’s exactly why the development of a new and promising combination of materials could represent enormous business opportunity.”
Development will likely be guided by three key factors, higher energy density, better safety and lower materials costs. The ‘devil’ is in the cathode.
The Japanese believe that there aren’t any new materials for cathodes unless sulfur, air or something undiscovered turns up. That list poses a range of unresolved problems needing time to work out. The short-term answer is to build more voltage into the cathode for more output.
On the anode side alternatives to graphite exist but expand and contract too much in the charge discharge cycle forcing physical breakdown and a short lifespan. The key research effort is to match the cathode higher voltage potential for more capacity and safer battery. The electrolytes will also have to improve; higher voltage will require better heat resistance.
Lithium ion is currently stuck at 3 volts. Research has identified cathodes that can get to 5 volts, a major improvement. Energy density is the product of specific capacitance and voltage, so a higher voltage means more battery capacity.
The olivine materials are interesting with elements P and O tightly bonded, and oxygen is not released even at high temperature so tempering the ‘thermal runaways’ and making batteries safer. The U.S. A123 Systems, Inc., the Massachusetts Institute of Technology, and others have found a way to make practical Li-ion rechargeable batteries for use in high-output applications by using smaller LiFePO4 particles and sheathing them in carbon. The fine particles with carbon sheathing make possible use of the material, formerly suffering from low electrical conductivity in the cathode.
Lithium Ion Cathode Carbon Sheaths. Click image for more info.
Wholly solid materials are gathering development momentum. One is a 5V cathode layered material, a layered and spinel anode material, and a solid solution material of Li2MnO3-LiMO2. Layered designs might surpass a theoretical ceiling of 275 mAh per gram. Research is also pointing to fluoride phosphate olivine (Li2MPO4F), silicate (Li2MSiO4) and other materials offering high specific capacitances exceeding 300mAh/g, better than a 50%increase from today’s on sale technology.
At the anode Si (silicon) has a theoretical capacity ten times that of graphite with a dreadful corresponding change in volume of 400%, larger physical size requirements and a very short cycle lifespan, but that 10-fold increase is a serious invitation for research. Ideas are in trial with Si materials expected in battery anodes in a year or two.
The single battery safety risk in a cell phone is much lower than a tightly packed set in a notebook PC or vehicle. Thus safety is a much higher priority for pack service. The graphite role is significant. Japan’s Toshiba Corp. has developed a new material attracting attention in the industry: lithium titanium oxide, or LTO (Li4Ti5O12). Japan’s Sanyo Electric Co., Ltd. is developing an anode material with a theoretical volumetric capacitance double that of LTO, with an electrical potential on a par with that of lithium.
The Sanyo prototype coin-type battery made with a LiCoO2 cathode and a MoO2 anode achieved a capacity of 2.9mAh, 1.3 times the level of the same design with an LTO anode. Both paths offer significant improvements.
The other candidates, air, solid state and metal are heavily funded with considerable management power. IBM has organized a lithium air research effort. Toyota is going basic with fundamental themes such as interface reactions between particles, and between electrodes and electrolytes, with the goal of developing new Li-ion rechargeable battery materials, all solid-state batteries, Li-air batteries, and more. By last December 1st Toyota presented nine papers on basic research at the 50th Battery Symposium in Japan.
Toyota appears to be especially interested in all solid-state batteries. An ideal all solid-state battery, says theory, would achieve a Li diffusion speed higher than that possible with a liquid electrolyte, making higher output possible. It would also be safer than organic electrolytes, which combust at high temperatures, and because there is no contained liquid, it seems likely that the exterior casing could be simplified. But reaction products form at the interface between the solid electrolyte and the electrode, degrading battery performance. It’s a major problem covered in detail in the Nikkei cover story. But Toyota is undeterred.
Air batteries have been around a while, going briefly commercial in the 1980s. Self-ignition removed them from the market. It’s known now that dendrites formed on the anode, puncturing the separator causing shorts that sparked and ignited the batteries. Two paths are in mind for researchers, solid electrolytes would eliminate the possibility of internal shorts. Research is expected to solve the problem. Preventing them from forming is more attractive and research is underway. The prevention path is further behind, while offering more promise.
All of these points are addressed in greater detail at the Nikkei Electronics cover story site. It’s a worthwhile read, the translation is pretty good, and I puzzled less than on some topics trying to figure out what was really meant.
Lithium, a light happily reactive metal has a future in energy storage. The drive to lower prices, market share, and quality improvements come from human nature. The spark of $150 oil has repercussions.
On the other hand . . . We haven’t heard from EEStor in a while. When we do, we might find that the lithium ion business will answer with even more research, faster adoption of new technology and raw animal competition. Electron storage is changing fast and it’s going to get cheaper faster than anyone thought.
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Amazing! Not clear for me, how offen you updating your newenergyandfuel.com.
Socco
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