Improved Safety in Large Format Lithium-Ion Cells and Batteries

In recent years a new separator, developed under SOCOM funding, proved to prevent failure during overcharge by limiting the cell voltage and shunting the current. Tests have been done on 4.7Ah cells charged at C/2 and have been demonstrated to successfully continue to cycle after 300% overcharge. This separator also provides thermal shutdown at 90 - 110„aC and is structurally stable to 180„aC. It is proposed to combine this latest development of a new separator with other design-in technologies to produce intrinsically safe, large format cells. These cells will be designed to provide thermal management and will contain the safest of high energy cathode materials in order to still provide 175 - 200 Wh/kg at the cell level. These large cells will be tested and revised as necessary to provide and demonstrate intrinsic safety. A battery will then be designed using these cells and incorporating thermal management systems thus providing a large battery for submersibles with significantly improved safety against catastrophic events.