Graphite foam as carbon-based footprint for in-situ fabrication of Ti³⁺-doped titanium niobium oxide (Ti₂Nb₁₀O₂₉) nanocrystal for high-rate performance lithium-ion batteries

The induction of cation dopant into the lattice structure of anode materials is a feasible and effective method to modulate the electronic structure and induce different active sites for Li⁺ storage. However, it is a challenge to create the cation dopant into the structure of the transition metal oxides anode of the lithium-ion batteries (LIBs). In this work, we propose an in-situ source template thermal reduction of graphite foam (GF) and annealing process for the first time to successfully induce Ti³⁺ into the titanium niobium oxide (Ti₂Nb₁₀O₂₉, TNO) nanocrystal structure denoted as TNO@GF for high-energy/power lithium storage. The induction of Ti³⁺ could not only prompt the more active sites for Li⁺ ion storage but also modulate the electronic interaction between the active sites and the intercalated Li⁺ ion, leading to the favorable Li⁺ ions intercalation and minimizing the Li⁺-ion diffusion barriers in the open channel of the ReO_3-type structure unit. Due to the combined effect of nanocrystal structure and Ti³⁺, TNO@GF yields a higher reversible discharge capacity of 328 mAh g⁻¹ at 0.1C, a higher rate capability of 296.3 mAh g⁻¹; and keeps 207.88 mAh g⁻¹ at a high rate of 35 C and shows good cycling stability (217.73 mAh g⁻¹ at the rate of 10 C) with the capacity retention of 83.20 % after 500 cycles. These findings provide insights into cation engineering and its influence on the functional nanomaterials' physicochemical properties, which are not achievable in the perfect crystal for advanced energy storage applications.