Biopolymer-assisted Synthesis of P-doped TiO₂ Nanoparticles for High-performance Lithium-ion Batteries: A Comprehensive Study

TiO₂ material has gained significant attention for large-scale energy storage due to its abundant, low-cost, and environmentally friendly properties, as well as the availability of various nanostructures. Phosphorus doping has been established as an effective technique for improving electronic conductivity and managing the slow ionic diffusion kinetics of TiO₂. In this study, non-doped and phosphorus doped TiO₂ materials were synthesized using sodium alginate biopolymer as chelating agent. The prepared materials were evaluated as anode materials for lithium-ion batteries (LIBs). The electrodes exhibit remarkable electrochemical performance, including a high reversible capacity of 235 mAh g⁻¹ at 0.1 C and excellent first coulombic efficiency of 99 %. An integrated approach, combining operando XRD and ex-situ XAS, comprehensively investigates the relationship between phosphorus doping, material structure, and electrochemical performance, reinforced by analytical tools and first principles calculations. Furthermore, a full cell was designed using 2 %P-doped TiO₂ anode and LiFePO₄ cathode. The output voltage was about 1.6 V with high initial specific capacity of 148 mAh g⁻¹, high rate-capability of 120 mAh g⁻¹ at 1 C, and high-capacity retention of 96 % after 1000 cycles at 1 C.