New Insights into the Ion/Electron Transfer Mechanisms of LiMn2O4-Based Membrane Electrodes at Different Electron Fluxes

Abstract

Electrochemical Li extraction technology is a highly promising approach for Li extraction from salt lakes. To enhance its practical application, it is crucial to elucidate the ion/electron transfer mechanism under diverse process conditions particularly different electron fluxes. Different migration intermediate states demonstrate the distinct ion migration mechanisms inside the LiMn₂O₄ lattice at different electron fluxes. Furthermore, direct observation of the distribution of Li⁺ in LiMn₂O₄-based membrane at different layered locations using Laser-induced Breakdown Spectroscopy (LIBS) reveals that the rate-limiting step is determined by the variety of electron flux. The desorption rate is limited by electron-transfer resistance at low electron fluxes whereas the ion-transfer resistance is the rate-limiting at high electron fluxes. These novel insights into the ion/electron transfer mechanisms and rate-limiting steps at different electron fluxes on the molecular and microscopic scales are imperative for the improvement of electroactive ion exchange materials (EIXMs) and practical applications of the electrochemical Li extraction technology.