Design of regenerated TiNb₂O₇ with engineered local polarization effect for fast-charging applications prepared by...

TiNb₂O₇ (TNO) is regarded as a highly promising anode material for high-rate and fast-charging lithium-ion energy storage applications. This study presents a recycling strategy for synthesizing next-generation fast-charging TiNb₂O₇ anode materials from waste selective catalytic reduction (SCR) catalysts. By employing sodium roasting followed by leaching, vanadium and tungsten were efficiently recovered with leaching rates of 92.30 % and 95.16 %, respectively. This process yielded a regenerated TiO₂ carrier (R-TiO₂) containing trace amounts of aluminum impurities. Environmental and economic evaluations verified the environmental benignity and economic viability of this process, highlighting its scalability for industrial application. On this basis, a novel regenerated TiNb₂O₇ (R-TNO) anode material was synthesized using R-TiO₂, demonstrating significantly enhanced fast-charging performance compared to conventional TNO. Electrochemical tests reveal that R-TNO delivers a discharge capacity of 340.4 mAh·g^-1 after 100 cycles at 0.5 C and 181.6 mAh·g^-1 after 500 cycles at 10 C, representing an 81.05 % improvement over pristine TNO. XPS analysis identifies an unusual binding energy shift, suggesting that Al doping induces a local polarization effect, which redistributes charge density across Nb-O bonds thereby underpinning the performance enhancement. DFT calculations corroborate this mechanism: reduced density of states and band gap confirmed improved intrinsic electronic conductivity. Differential charge density and Bader charge analyses quantitatively demonstrated the polarization effect, while optimization of the Nb-O bonding environment and lower lithium-ion diffusion energy barriers accounted for accelerated Li⁺ transport kinetics. This study provides critical insights into both circular-economy approaches to carbon neutrality and the development of high-performance fast-charging anodes, thereby connecting resource recovery and next-generation energy storage technologies.