Sodium Carboxymethyl Cellulose as an Effective Modifier for Boosting the Electrochemical Performance of Commercial TiO2

Abstract

The poor electrochemical performance stunts the utilization of commercial TiO2 (c‐TiO2) as the negative material of Li‐ion batteries (LIBs). Herein, sodium carboxymethyl cellulose (CMC) with carboxyl groups and Na+ is used as a carbon source to fabricate carbon‐coated c‐TiO2 (TiO2/C) with excellent electrochemical performance. The good viscosity of CMC in water allows it to cover the TiO2 particles under magnetic stirring, and the intense adsorbability of the carboxyl groups with TiO2 promotes the interaction, resulting in the formation of a uniform and thin carbon coating on the surface of TiO2 particles and Na+‐doping in c‐TiO2 during sintering at 750 °C. The Na+ doping brings about some oxygen vacancies (OVs) and Ti3+ to favor the electronic conductivity of c‐TiO2, together with carbon coating. Meanwhile, the OVs and lattice distortion induced by Na+‐doping can promote Li+ diffusion in TiO2. TiO2/C with an initial mass fraction of 16 wt% CMC shows superior electrochemical performance and cycling stability, retaining a specific capacity of 163.4 mAh g−1, even undergoing 1200 cycles at 500 mA g−1. The outstanding performance is attributed to the alleviated polarization, resulting from the simultaneously enhanced electronic and ionic conductivities.