H2SO4 etches the surface of Super-P conductive agent: Improving the comprehensive performance of LiNi0.5Co0.2Mn0.3O2 lithium-ion batteries

In order to solve the problems of insufficient adsorption electrolyte capacity and small specific surface area caused by the smooth surface and few pores of Super P spherical conductive particles, this work uses concentrated sulfuric acid (H2SO4) for surface etching of Super P conductive particles to explore the influence of different etching time on the micromorphology of SP conductive agent and the behaviors of LiNi0.5Co0.2Mn0.3O2 (NCM-523) batteries. After etched by concentrated H2SO4, the surface of SP conductive agent changes from "capillary" structure to fluffy "plush" structure, effectively improving the conductivity specific surface area of the conductive agent particles. Compared with the pristne SP-0H conductive agent, the batteries using 1.5% of concentrated H2SO4 etched SP-1H, SP-2H and SP-20H conductive agent have smaller EIS impedance value, larger area of CV curves, and smaller potential difference of the redox peaks. As a result, the initial charging/ discharging capacities of SP-1H, SP-2H and SP-20H conductive batteries were 178.7/183.0, 187.6/183.9, 178.9/180.8 mAh/g with corresponding ICE of 102.4%, 98.0% and 101.1% respectively, which were much higher than the pristine SP-0H conductive battery (182.0/173.7 mAh/g with ICE of 95.4%). In addition, the SP1H, SP-2H and SP-20H batteries also show significantly improved cycle performance and rate cycle capabilities, showing more superior comprehensive behaviors, which can provide a new modification insights for the exploration of new conductive agent in NCM-523 of high-performance lithium ion batteries.