Engineering of Cerium Modified TiNb₂O₇ Nanoparticles For Low-Temperature Lithium-Ion Battery

Although TiNb₂O₇ (TNO) with comparable operating potential and ideal theoretical capacity is considered to be the most ideal replacement for negative Li₄Ti₅O₁₂ (LTO), the low ionic and electronic conductivity still limit its practical application as satisfactory anode for lithium-ion batteries (LIBs) with high-power density. Herein, TNO nanoparticles modified by Cerium (Ce) with outstanding electrochemical performance are synthesized. The successful introduction of Ce³⁺ in the lattice leads to increased interplanar spacing, refined grain size, more oxygen vacancy, and a smaller lithium diffusion barrier, which are conducive to improve conductivity of both Li⁺ and electrons. As a result, the modified TNO reaches high reversible capacity of 256.0 mA h g^-1 at 100 mA g^-1 after 100 cycles, and 183.0 mA h g^-1 even under 3200 mA g^-1. In particular, when the temperature drops to -20 °C, the cell undergoing 1500 cycles at a high current density of 500 mA g^-1 can still reach 89.7 mA h g^-1, corresponding to a capacity decay rate per cycle of only 0.033%. This work provides a new way to improve the electrochemical properties of alternative anodes for LIBs at extreme temperature.