Mitigating Electrode Polarization through Electrolyte Concentration Optimization

Abstract

High-loading electrodes are crucial for attaining elevated high energy density in the industrial applications of lithium-ion batteries. However, a rise in electrode loading correlates with an elevation in electrode tortuosity. The elevated tortuosity of the transport pathway may result in a discrepancy between ion transport and electrode reaction, leading to excessive or incomplete reactions of localized particles, creating concentration gradient phenomena, and ultimately causing capacity loss. Research on high-loading electrodes mostly concentrates on the regulation of electrode structure and material modification, while investigations into electrolyte concentration predominantly emphasize solvation structures; however, the correlation between electrolyte concentration and high-loading electrodes has been inadequately explored. This study examines the effect of electrolyte concentration on the electrochemical performance of high-loading LiNi₀.₈₃Mn₀.₁₂Co₀.₀₅O₂ (NMC83) electrode. Utilizing pore network modeling (PNM), high-resolution techniques, and pore equivalent diameters (EqD) analysis to compare ion transport pathways and abilities under different electrolyte concentrations. It was observed that a concentration of 1.5 M in the conventional electrolyte can establish a more efficient percolation channel and provide sufficient lithium ions to achieve a balance between ion transport and electrode reaction, thereby alleviating the inherent concentration polarization of high-loading electrodes.