A major factor impacting development of Liion batteries for vehicles is the effect of elevated temperature ( & gt;50C) on battery life. Calendar and cycle life degrade at elevated temperatures due to degradation processes involving the interaction of the salt, solvents, and electrodes. Safety is undermined by use of high vapor pressure and low flash point volatile carbonate solvents. Overall, development of Li-ion batteries for vehicles, including enabling of high voltage cathode materials, requires new solvents and salts with electrochemical and thermal stability and safety characteristics that are beyond the capabilities of current state-of-the-art commercial electrolytes. In this proposal, a new non- carbonate Liion battery electrolyte will be developed by combining advanced generation organosilicon solvents with a lithium imide chemistry system. The organosilicon solvents are thermally and electrochemically stable with vapor pressures significantly lower than linear carbonates commonly used in Li-ion batteries. The use of high stability imide salts is enabled by a new current collector technology that solves the aluminum corrosion issue. By integrating an organosilicon solvent with lithium imide salts into an electrolyte, improved wide temperature range performance, enhanced safety, and the potential to integrate these advantages into higher energy Li-ion systems (i.e., higher voltage cathode, higher capacity anode) will be achieved. In Phase 1, we will focus on optimizing a new electrolyte for use in high energy density cells at elevated temperatures ( & gt;55C). Electrolytes will be characterized for electrochemical performance and thermal and electrochemical stability. Their interaction and safety profile with high energy density cathode and anode materials will be evaluated. Commercial Applications and Other
Benefits: Success of this program will lead to lower cost and better performing Li-ion batteries for electric vehicles to support commercialization. Overall system cost will improve due to increased energy density and simplification of thermal management systems. Abuse tolerance of the system will increase as the new electrolytes will have lower vapor pressure and better stability at high temperature.
