Nanoarchitectonics of interstitial oxygen and Jahn-Teller distortion to enhance electrochemical performance of CuMnO2: symmetric coin-cell

Abstract

In this work, influence of interstitial oxygen and Jahn-Teller distortion of Mn ions, tuned by varying alkali concentration during hydrothermal reaction, on the charge storage capacity of monoclinic CuMnO₂ nanoplate electrodes has been investigated, followed by tuning them to improve the capacitance. CuMnO₂ nanoplates, prepared at optimum pH, exhibits high specific capacity ∼ 120 F.g^− 1 at 2 mVs^− 1 scan rate using environment friendly electrolyte Na₂SO₄. Symmetric coin-cell, prepared with CuMnO₂ nanoplates, exhibits specific capacitance ∼ 86.5 Fg^− 1 at 2 mVs^− 1 scan rate (∼ 71.2 Fg^− 1 at 0.35 A/g), energy density ∼ 14.2 Wh/kg and power density ∼ 333.3 W/kg which make it a promising candidate for supercapacitor applications. It has been found that the charge transfer mechanism across electrode – electrolyte interface is governed by Marcus’s mechanism, wherein Jahn-Teller distortion plays most predominant role. Our theoretical analysis on the basis of density functional theory, provides better insight about the influence of interstitial oxygen on storage capacity. Herein, we have identified that interstitial oxygen tunes electron density on Mn³⁺ sites which in consequence facilitates specific capacitance. Our studies clearly reveal that CuMnO₂ may be a potential, biocompatible pseudocapacitive energy storage material.