Polyacrylonitrile Block Copolymers for the Preparation of a Thin Carbon Coating Around TiO2 Nanorods for Advanced Lithium-Ion Batteries

Herein, a new method for the realization of a thin and homogenous carbonaceous particle coating, made by carbonizing RAFT polymerization derived block copolymers anchored on anatase TiO2 nanorods, is presented. These block copolymers consist of a short anchor block (based on dopamine) and a long, easily graphitizable block of polyacrylonitrile. The grafting of such block copolymers to TiO2 nanorods creates a polymer shell, which can be visualized by atomic force microscopy (AFM). Thermal treatment at 700 °C converts the polyacrylonitrile block to partially graphitic structures (as determined by Raman spectroscopy), establishing a thin carbon coating (as determined by transmission electron microscopy, TEM, analysis). The carbon‐coated TiO2 nanorods show improved electrochemical performance in terms of achievable specific capacity and, particularly, long‐term cycling stability by reducing the average capacity fading per cycle from 0.252 mAh g–1 to only 0.075 mAh g–1. A thin and homogeneous carbon coating of anatase TiO2 nanorods is described involving a new approach using block copolymers synthesized by RAFT polymerization. Grafting of these polymers onto the TiO2 nanoparticle surfaces followed by pyrolysis results in carbon‐coated particles, which are utilized as an electrode material in a lithium‐ion half‐cell configuration that shows a substantially enhanced electrochemical performance.