Could Capacitive Behavior be Triggered in Inorganic Electrolyte‐Based All‐Solid‐State Batteries?

Abstract

AbstractRecent studies in all‐solid‐state batteries (ASSBs) based on inorganic solid electrolytes (ISEs) have improved the energy density to a higher level. However, its commercialization is still delayed by many intrinsic limitations, among which the fast‐charging capability is not mentioned enough. Despite few elaborately selected electrolytes coupled with electrodes that can deliver an extremely high rate, the rate improvement strategy is still lacking. Here, a novel and effective strategy of introducing liquid metal is demonstrated to trigger the capacitive behavior in the ASSBs for the first time. Two paramount criteria of inducing capacitive behavior in ASSBs are proposed, and both of them are accomplished by utilizing liquid metal Ga. As a result, the capacitive behavior contribution to total charge storage reaches 73% at 1 mV s−1. Benefitted from the improved kinetics, both an excellent rate of performance (81% specific capacity retained at 5 C) and a good cyclability (0.02% decay per cycle during 800 cycles at 1 C) are delivered. The universality of the liquid metal induced capacitive behavior in ASSBs is further verified in multiple active materials. This work provides a fundamental understanding of the origin of the capacitive behavior and opens a new route for fast‐charging ASSBs.