Stabilization of Li[NixMnyCo1-x-y]O2 structure using a mixture of Super-P and vapor-grown carbon fiber as conducting additives

Abstract

Li[NiMnCo]O (NCM) has attracted considerable attention as a cathode material because of its excellent electrochemical performance; however, practical application of NCM is challenging owing to side reactions in the electrolyte and structural changes. In this study, we manufactured NCM electrodes with mixtures of Super-P and vapor-grown carbon fiber (VGCF) as conductive additives at different ratios (Super-P/VGCF=2/8 (S2V8), 5/5 (S5V5), and 8/2 (S8V2)) and investigated the effect of the ratio of the conductive additives on NCM electrode performance. Simply changing the ratio of the conductive additives without modifying the NCM active materials substantially altered the electrochemical performance. Using a Super-P/VGCF mixture at an appropriate ratio (5/5, w/w) forms a conductive network throughout the NCM active materials, improving the electrical conductivity and enabling uniform activation across the range of NCM particles. Consequently, for S5V5, the anisotropic volume changes of the NCM primary particles became uniform, resulting in structural stability of the secondary NCM particles during charging and discharging.