Aqueous Acidic Pectin-Based Solution as Electrolyte and Pretreatment Solution for Zinc Ion Battery Anodes

Abstract

While considerable progress has been achieved in aqueous mildly acidic Zn-ion batteries (AZIBs), the development of metallic Zn anodes remains challenging due to dendritic growth and side reactions on the Zn surface in mildly acidic aqueous environments. Herein, we utilize pectin in two ways: firstly, as an additive for the acidic ZnSO₄ electrolyte with pectin (referred to as ZSP); and secondly, as a component in the pretreatment solution for Zn electrode. The ZSP electrolyte can prevent the formation of inactive Zn₄(OH)₆(SO₄) ⋅ 5H₂O byproduct on Zn electrode and enable stable cycling under challenging conditions at 10 mA h cm⁻². Interestingly, the immersion of the Zn foil in the acidic pectin solution resulted in the uniform removal of the bumpy oxides/carbonates layer on the Zn metal surface. The cells with treated Zn electrode in pectin solution exhibited lower overpotentials and effectively inhibited cell failure. Our findings indicate that utilizing an organic-based acidic ZnSO₄ electrolyte shows promise as both an effective electrolyte and a pretreatment solution for the development of stable and cheap aqueous AZIB electrolytes.