Synthesis of Highly Dispersible Functionalized Carbon Nanotubes as Conductive Material through a Facile Drying Process for High-Power Lithium-ion Batteries.

Herein, surface-functionalized carbon nanotubes (CNTs) were successfully synthesized by dry ball milling that facilitates industrial application. The optimal conditions were determined by analyzing the physicochemical characteristics of CNTs, including the content of the carboxyl group (-COOH) induced on the surface of CNTs by co-existing dry ice based on the ball milling time. Among them, 30 s ball milling (CNTs-30s) showed a high dispersibility in N-methyl-2-pyrrolidone (NMP) while retaining most carboxyl groups and maintaining the intrinsic high conductivity. In the evaluation of rate capability and 5 C/5 C cyclability applied to the Li1+x (Ni1-y-z Coy Mnz )1-x O2 with 60 % Ni (NCM622) cathode, CNTs-30s showed excellent performance based on a well-formed conductive network. Regarding improved dispersion properties and electrochemical performance, the optimal surface functionalization conditions, dispersibility, and electrode properties according to the processing time were analyzed; based on these, the correlation with electrochemical performance was confirmed.