Reactive plasma oxygen-modified and nitrogen-doped soft carbon as a potential anode material for lithium-ion batteries using a tornado-type atmospheric pressure plasma jet

Abstract

In this study, a tornado-type atmospheric pressure plasma jet (APPJ) system was used to modify soft carbon (SC) as an anode material for lithium-ion batteries (LIBs). We used both argon plasma–derived reactive oxygen species and reactive nitrogen species to activate SC electrodes in an ambient environment using in-situ hydrophilic surface modification and nitrogen-doping technology. After the APPJ modification, the contact angle of the electrode was substantially reduced from 113° to less than 10° because of the formation of oxygen-containing functional groups on the SC surface. The hydrophilic nature of the plasma-modified electrode facilitated the penetration of liquid electrolyte. In addition, during the APPJ process, nitrogen atoms were simultaneously doped into the SC to increase its conductivity, reversible capacity, and rate capability. According to electrochemical measurements, the SC-40 electrode (40 cycles of plasma treatment) exhibited a reversible charge and discharge capacity of 293 and 259 mAh/g, respectively, with a Coulombic efficiency of 88.63 % at 0.1C. At 10 C, the reversible capacity of the SC-40 electrode achieved 111 mAh/g, which was 252% greater than that of the pristine SC electrode (approximately 44 mAh/g). Plasma-induced surface hydrophilicity and nitrogen-incorporated soft carbon as an anode material for LIBs using a tornado-type APPJ technique represents a unique and promising technique.