A New Approach in Surface Modification of Manganese Based Cathode Materials for Enhanced Performance in Zinc Aqueous Batteries

Abstract

With the growing demand for sustainable and environmentally friendly energy storage solutions, zinc-aqueous batteries have emerged as promising alternatives to conventional lithium-ion batteries. Among the various cathode materials studied for zinc-aqueous batteries, manganese dioxide (MnO2) has garnered significant attention due to its high theoretical capacity, abundance, and non-toxic nature. However, the intrinsic limitations of MnO2, including low electrical conductivity and sluggish kinetics, have hindered its practical application. To address the aforementioned limitations, we present a new approach in surface modification of KxMnO2 cathode with improved electrochemical performance for zinc-aqueous batteries.In this study, the KxMnO2 cathode material’s surface has been fluorinated, that enhances capacity retention of the material and effectively improves the overall electrochemical performance. Structural and morphological characterizations of the surface modified KxMnO2 were performed using operando X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), X-ray Absorption Near Edge Spectroscopy (XANES) and thermogravimetric analysis (TGA). Furthermore, X-ray photoelectron spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) confirmed the successful fluorination of the material surface.Electrochemical tests, including cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS), were conducted to evaluate the performance of the surface fluorinated KxMnO2 cathode in comparison to pristine KxMnO2. The results demonstrated a remarkable improvement in the specific capacity, rate capability, and cycling stability of the modified cathode. The improvement of electrochemical performance can be attributed to the effect of the fluorine element, which alleviates the structural degradation of KxMnO2 during cycling. The improved electrochemical performance of the KxMnO2 cathode paves the way for the development of high-performance, cost-effective, and environmentally friendly zinc-aqueous batteries.