Composite Conducting Polymer Cathodes For High Energy Density Lithium-Ion Batteries

Future NASA planetary exploration missions require secondary (rechargeable) batteries that can operate at extreme temperatures (-60oC to 60oC) yet deliver high specific energies (> 180 W·hr/kg) and long cycle life (>2,000 cycles). Functional organic materials are a promising technology for use as the cathode in Li-Ion batteries due to their high specific energy density. It is also expected that the use of polymeric cathodes instead of lithium metal oxides will make Li-Ion batteries thinner, lighter and less environmentally hazardous. This Phase I proposal is based on demonstrating the feasibility of fully packaged Li-Ion batteries that have a superior specific energy (>200 W·hr/kg) through the use of novel polymeric cathodes (composite conducting polymer/disulfide materials) when coupled with room temperature ionic liquid (RTIL) electrolyte. Compared to traditional organic electrolyte systems (e.g. (e.g. lithium salts dissolved in alkyl carbonates), RTIL electrolytes have favorable electrochemical windows (> 5 V) and high ionic conductivity over a wide range of temperatures from –60?C to 250?C and are known to prolong the lifetime of conducting polymer electrochemical devices. Besides these highly desirable characteristics for use in these novel Li-ion batteries, RTILs have inherent safety characteristics by virtue of their thermal stability, non-flammability, non-volatility and low heat of reaction with active materials.