Improved lithium-ion battery cathode rate performance via carbon black functionalization

Abstract

Carbon black (CB) creates essential electron transport pathways in lithium-ion battery (LiB) cathodes. Here, we show that by modifying the surface of CB via mild hydrogen peroxide or nitric acid treatment, the rate performance of a LiB cathode can be increased up to 350% at 0.75 C-rate charging. We demonstrate that this improvement is predominately due to the presence of introduced carbonyl groups on the surface of the CB which increases the surface redox reaction of the nickel manganese cobalt oxide (NMC) cathode active material. As a result, there is both a decrease in the overpotential (∼37% during 0.25 C-rate charging) and electrochemical impedance. A mechanism is proposed which describes how the cathode performance is influenced by electrostatic interactions between the CB surface and solvated lithium ions. An improved rate effect was demonstrated across various cathode active materials, clearly highlighting the versatility of this simple approach.