Flyash/polymer composite electrolyte with internal binding interaction enables highly-stable extrinsic-interfaces of all-solid-state lithium batteries

Satisfactory electrochemical stability of extrinsic-interfaces between electrodes and electrolyte is the prerequisite for the safe and durable applications of all-solid-state Lithium batteries (ALBs). Unfortunately, the oxidative decomposition of anions from Li-salt at the extrinsic-interfaces of cathode side leads to the electrochemical instability during charge process. Here, a novel composite polymer electrolyte (CPE) containing flyash-treated (FA) submicro/micron particles and poly(ethylene oxide) (PEO) matrix is reported. After the addition of FA filler, Li + transference number increases from 0.21 to 0.37 and electrochemical stability window reaches 5.2 V. FA as filler can efficiently immobilize (trifluoromethanesulfonyl) imide (TFSI – ) anions and mitigate their irreversible oxidative decomposition at the extrinsic-interface of cathode||CPE due to the internal binding interaction between TFSI – anions and FA particles. ALBs using CPE with FA can not only provide stable extrinsic-interfaces for uniform Li deposition, but also tolerate strong electrochemical polarization with excellent cycling performance.