Effect of Preconditioning on Cycling Performance of Aqueous Zn-Ion Batteries

Abstract

This study provides valuable insights into the optimization of a zinc ion battery with higher mass loadings and lower current rate. While other academic papers aim to provide fundamental insights and highly engineered approaches, this paper aims to provide a commercially relevant study that improves the performance of a full system that can be applied at scale. We demonstrate that fast C-rate preconditioning effectively improve performance of Zn–MnO2 full cells when used in synergy with an aqueous electrolyte with 1 vol% acetonitrile additive and optimized ZnSO4 and MnSO4 salt concentrations. Three cycles of preconditioning protocols using C/3 rate and 1C rate led to a remarkable specific discharge capacity of over 550 mAh g⁻¹ for low loading cathodes of ~2 mg/cm2 after 25 cycles at C/10 rate. Discharge capacity ~350 mAh g⁻¹ and high coulombic efficiency of 99% can be maintained even after increasing electrode loadings to commercially relevant levels of ~6 mg/cm2. These results demonstrate that preconditioning could activate internal restructuring of electrolytic M MnO2 cathode during fast-rate cycling and can lead to the creation of more efficient pathways for both electrons and ions, improving the overall conductivity and Zn2+ transport. It highlights electrochemical preconditioning as a simple yet powerful strategy to achieve high specific discharge capacities in commercial aqueous zinc-ion batteries.