High Power Density Li-Ion Batteries with Good Low Temperature Performance

Hybrid electric vehicles (HEVs) require economical, safe, rechargable Li-ion batteries that have high power, long cycle life, and good low-temperature performance. The DOE performance targets for HEV rechargeable batteries include a discharge power of 25kW for 18 seconds, a cost of $20/kW, and an operating temperature window of -30 to +52 C. Currently available Li-ion batteries suffer a significant degradation in performance at temperatures lower than -10 C, and do not meet the other requirements either. This project will improve the low-temperature performance of Li-ion batteries by utilizing safe and nanostructured electrode materials in conjunction with a liquid electrolyte that has high ionic conductivity at low temperatures. In addition, the new Li-ion configuration will overcome the lithium plating problem found in conventional Li-ion batteries at low temperatures. In Phase I, nanocomposite cathodes with small-primary-particle size and high electronic conductivity will be synthesized by a newly-developed low-cost process. The electrohemical properties of the nanocomposite cathodes will be evaluated in Li test cells containing a low temperature electrolyte. Li-ion cells, containing a nanocomposite cathode and either a carbon-based or a nanostructured anode, will be fabricated and tested. Commercial Applications and Other Benefits as described by the awardee: Rechargeable Li-based batteries are ubiquitous in the commercial marketplace, both in the consumer and industrial sectors. However, most of the applications to date have been for relatively small portable devices, such as cellular phones, laptop batteries, and camcorders. According to one estimate, the wholesale market for batteries (new and replacement combined) is $12 billion, and electrode materials are a major component of the market. The technology described above should address the unfulfilled need for low cost, large-sized, and safe Li-ion batteries for hybrid electric vehicle and other applications.