LiBOB-based gel electrolyte Li-ion battery for high temperature operation

Abstract

In this work, we evaluated the chemical compatibility of 1.0m (molality) lithium bis(oxalate)borate (LiBOB) 1:1 (w/w) propylene carbonate (PC)/ethylene carbonate (EC) liquid electrolyte with lithium metal and spinel LiMn 2O 4 cathode using storage and cycling tests at high temperatures. Impedance analyses show that LiBOB and lithium are very compatible due to the formation of a stable passivation layer on the surface of lithium. Cycling tests of Li/Cu and Li/LiMn 2O 4 cells, respectively, show that lithium can be plated and stripped in LiBOB-based electrolyte with more than 80% cycling efficiency, and that this electrolyte can support LiMn 2O 4 cycling reversibly up to 60 °C without visible capacity loss. Using LiBOB-based liquid electrolyte and porous Kynar ® membrane, microporous gel electrolyte (MGE) Li-ion cells were assembled and evaluated. Results show that the MGE cell presents an improved cycling performance compared with a liquid cell, especially at elevated temperatures. It is confirmed that the LiBOB-based gel electrolyte Li-ion batteries can be operated at 60 °C with good capacity retention.