Construction of dynamic electrostatic shielding layer toward stable interface chemistry of Zn anode

Abstract

Dendrite proliferation and parasitic side reaction seriously deteriorate the electrochemical reversibility of zinc metal anode (ZMAs), thus impeding the commercial application of rechargeable aqueous zinc-ion batteries. Herein, a novel strategy, which enables more stable interface chemistry of ZMAs, is proposed based on the construction of a dynamic electrostatic shielding layer. Specially, the trace amount of Al³⁺ cations added into the ZnSO₄ base-line electrolyte will preferentially adsorb onto the surface of Zn electrode and further establish a dynamic electrostatic shielding layer, which can effectively homogenize the Zn²⁺ cations and electric field. Consequently, the Zn nucleation energy was reduced and the Zn²⁺ deposition kinetic process was boosted. As a result, a long cycle life exceeding 3500 hours was observed on the ZMA deployed in symmetric Zn||Zn cell (1 mA cm^-2 and 0.5 mAh cm^-2) with the ZnSO₄/Al³⁺ hybrid electrolyte, along with an average Coulombic efficiency of 99.8% in Zn||Cu cell (2 mA cm^-2 and 1 mAh cm^-2). Furthermore, the assembled full Zn||MnO₂/CNT pouch cell with the ZnSO₄/Al³⁺ hybrid electrolyte acquires a maximal specific capacity of 274.5 mAh g^-1 and a high retention of 75% after 2000 cycles. This work offers a novel pathway for stabilizing the interface chemistry of ZMAs, thus inhibiting Zn dendrite growth for enhanced electrochemical reversibility.