Anchoring Nitrogen-Doped TiO₂Nanocrystals on Nitrogen-Doped 3D Graphene Frameworks for Enhanced Lithium Storage

An advanced architecture design of nitrogen-doped TiO₂anchored on nitrogen-doped 3D graphene framework composites (denoted as N-TiO₂/N-3D GFs) have been fabricated by a facile template process and further NH₃treatment. The 3D graphene framework allows the electrolyte to penetrate into the inverse opal structure, and possesses high electronic conductivity. The close contact between the N-TiO₂and the graphene suppresses the growth and aggregation of TiO₂nanoparticles during heating process, leading to decreased Li⁺diffusion length. The N-doping in both TiO₂and the graphene matrix could improve the electronic conductivity on the TiO₂particle surface and between adjacent particles. As expected, when used as an anode for Li-ion batteries (LIBs), the N-TiO₂/N-3D GFs composite delivers an excellent reversible capacity of 165 mA h g⁻¹after 200 cycles at 100 mA g⁻¹and an outstanding rate capability of 114 mA h g⁻¹after 1000 cycles at 1 Ag⁻¹. With rational design, this strategy could be extended to other electrode materials that may hold great promise for the development of high energy storage systems.