Dual Type-Gel Polymer Electrolyte for Lithium Metal Battery with Excellent Cyclability and High-Voltage Stability

Abstract

Lithium metal batteries (LMBs) are promising rechargeable battery systems due to high theoretical capacity of lithium metal anode and its high energy density. However, liquid electrolytes have high reactivity to lithium metal anode and it follows lithium dendrite growth during charge and discharge cycles. Finally, LMBs have lower cycling stability and fire/explosion incidents due to a short circuit. Herein, we synthesize a dual type-gel polymer electrolyte (GPE) consists of catholyte and anolyte. A catholyte is the semi-interpenetrating polymer network (IPN) structure through in-situ thermal curing with high ionic conductivity and oxidative stability. An anolyte is an organic and inorganic hybrid electrolyte based on poly(ethylene oxide) (PEO). It could not only prevent direct contact between lithium metal anode and liquid electrolyte but also suppressed lithium dendrite growth. We applied this dual type-GPE to LiCoO2 (LCO) cathode and lithium metal anode and its cycling performance was tested from 3.0 V to upper limit charging voltage, 4.48 V at 0.5 C rate. The cell exhibited excellent cycling stability with a capacity retention of 86.1% after 500 cycles, proposing that dual-type GPE is suitable electrolyte for high-voltage lithium metal batteries.