Synergy-electrode based on micron-sized LiNi0.5Mn0.3Co0.2O2/LiFePO4 particles with bimodal size distribution

Abstract

We investigated the electrochemical behavior of binary blend cathodes made by mixing micro-spheres of LiNi_0.5Mn_0.3Co_0.2O₂ and smaller micro-platelets of LiFePO₄ in different proportions (10–40 wt%). Results show that the discharge profiles of the blended electrodes at 0.1C are predictable through a model based on the weighted averages of specific differential capacities of pristine electrodes. However, at high C-rates (>1C), the blended electrode contains 20 wt% LiFePO₄ (coined as the synergy-electrode) shows significantly higher discharge capacity and better capacity retention (observed up to the 100th cycle) than other electrodes. The synergy is rationalized using cyclic voltammetry and electrochemical impedance spectroscopy, indicating the facilitation of the charge-discharge reactions, reduction of both the bulk and the charge-transfer resistances, and higher Li diffusion coefficients observed for the synergy-electrode.