Novel polymer coating for chemically absorbing CO2 for safe Li-ion battery.

Gas evolution in Li-ion batteries remains a barrier for the implementation of high voltage materials in a pouch cell format; the inflation of the pouch cell is a safety issue that can cause battery failure. In particular, for manganese-based materials employed for fabricating cathodes, the dissolution of Mn2+ in the electrolyte can accelerate cell degradation, and subsequently gas evolution, of which carbon dioxide (CO2) is a major component. We report on the utilization of a mixture of polymers that can chemically absorb the CO2, including the coating of aluminum foils, which serve as trapping sheets, introduced into two Ah pouch cells-based on a LiMnFePO4 (cathode) and a Li4Ti5O12 (anode). The pouch cells with trapping sheets experienced only an 8.0 vol% inflation (2.7 mmol CO2 per gram of polymers) as opposed to the 40 vol% inflation for the reference sample. Moreover, the cells were cycled for 570 cycles at 1 C and 45 °C before reaching 80% of their retention capacity.