Anchoring Nitrogen-Doped TiO₂ Nanocrystals on Nitrogen-Doped 3D Graphene Frameworks for Enhanced Lithium Storage

An advanced architecture design of nitrogen-doped TiO₂ anchored on nitrogen-doped 3D graphene framework composites (denoted as N-TiO₂ /N-3D GFs) have been fabricated by a facile template process and further NH₃ treatment. 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-TiO₂ and the graphene suppresses the growth and aggregation of TiO₂ nanoparticles during heating process, leading to decreased Li⁺ diffusion length. The N-doping in both TiO₂ and the graphene matrix could improve the electronic conductivity on the TiO₂ particle 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^-1 after 200 cycles at 100 mA g^-1 and an outstanding rate capability of 114 mA h g^-1 after 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.