Synergistic Optimization Strategy Involving Sandwich-like MnO2@rGO and Laponite-Modified PAM for High-Performance Zinc-Ion Batteries and Zinc Dendrite Suppression.

Abstract

Optimization of the cathode structure and exploration of a novel electrolyte system are important approaches for achieving high-performance zinc-ion batteries (ZIBs) and zinc dendrite suppression. Herein, a quasi-solid-state ZIB combining a sandwich-like MnO2@rGO cathode, a laponite (Lap)-modified polyacrylamide (PAM) hydrogel electrolyte, and an electrodeposited zinc anode is designed and constructed by a synergistic optimization strategy. The MnO2 composite prepared through the intercalation of rGO shows developed mesopores, providing accessible ion transport channels and exhibiting a high electrical conductivity. Thanks to the high dispersion of Lap nanoplates in the hydrogel and good charge-averaging effect, the Zn//PAM-5%Lap//Zn symmetrical battery exhibits a consistent low-voltage polarization of less than 60 mV within 2000 h without a short-circuit phenomenon or any over-potential rise, indicating a stable zinc peeling/plating process. The optimized quasi-solid-state ZIB delivers a high reversible capacity of 291 mA h g-1 at a current density of 0.2 A g-1 due to the synergistic effect of each component of ZIB. Even at a high rate of 2 A g-1, it still maintains a high reversible capacity of 97 mA h g-1 after 2000 cycles, indicating its excellent electrochemical performance. Furthermore, the assembled flexible battery performs excellently in terms of damage and bending resistance.