New polymer lithium secondary batteries based onOMOCER electrolytes-inorganic-organic polymers

摘要

Based on new plasticized inorganic-organic polymer electrolytes [M. Popall, M. Andrei, J. Kappel, J. Kron, K.Olma. B. Olsowski, ‘ORMOCERs as Inorganic-organic Electrolytes for New Solid State Lithium Batteries andSupercapacitors’, Electrochim. Acta 43 (1998) 1155] new flexible foil-batteries in ‘coffee bag arrangement wereassembled and tested. The electrolyte works as separator and binder for the cathodes. Self-diffusion NMR studies onthe system (EC/PC/L~+N(SO2CF3)~/ORMOCERa) resulted in cationic transport numbers (r) of 0.42 for the EC/PC/salt system and 0.35 for the ternary electrolyte, typical for polymer electrolytes. Cycling tests (more than 900cycles) proved that the unplasticized electrolyte can act as binder in composite cathodes of lithium secondary batteries[21. Charge/discharge cycles of complete batteries like (Cu;active carbon/ORMOCER~/LiCoO2/Al) with an ORMO- CER~ as separator electrolyte were measured. The voltage drop of these batteries is very similar to cells with standard liquid electrolytes and the efficiency is close to 100%. Cycling the batteries with a current density of 0.25 mA cm2 between the voltage limits of 3.1 and 4.1 V results in a charge/discharge capacity (referring to the cathode mass) of 100 mAh g ?! at the beginning and after a slight decrease in a stabilised capacity of 75 mAh g ?? after 15 cycles. These promising results could be optimised by using highly purified components.