UV-induced semi-interpenetrating polymer electrolyte membrane for elevated-temperature all-solid-state lithium-ion batteries

Abstract Design and synthesis of electrochemical stable polymer electrolyte membranes with rational ionic conductivity is essential for elevated-temperature all-solid-state lithium ion batteries. Herein, we report that poly(ethylene oxide)-based semi-interpenetrating polymer electrolyte membrane synthesized through photo-crosslinking strategy shows promising electrochemical stability and great mechanical strength compared with membrane without crosslinked structures. The ionic conductivity of the designed membrane electrolytes can be also controlled through controlling the crosslinking density and the highest ionic conductivity is even slightly higher than that of pure PEO-based membrane electrolyte. The formed semi-interpenetrating polymer electrolyte membrane containing 20 wt% of crosslinking agent has the ionic conductivity of 1.59 × 10 −4 Scm −1 and is electrochemically stable under potential of 4.2 V at 65 °C. The thus-assembled lithium ion battery using lithium iron phosphate as cathode and lithium metal as anode exhibits a first discharging capacity of 148 mAhg −1 at 0.1 C under 65 °C and the discharge capacity remains 145 mAhg −1 after 40 charge-discharge cycles.