Effect of Si Doping and Active Carbon Surface Modifications on the Electrical and Structure Performance of Li 4 Ti 5 O 12 Anode Material for Lithium-Ion Batteries

Abstract Li 4 Ti 5 O 12 , as a spinel lithium-ion batteries anode material , exhibits stable cycling and is less prone to lithium dendrites and solid electrolyte interphase (SEI) films. However, its theoretical capacity and conductivity are low within the electrochemical window of 1.0-2.5 V. In this study, active carbon coated and Silicon-doped Li 4 Ti 5 O 12 crystals were used, and an electrochemical window of 0.01-3.0 V was applied during cycling to enhance the material’s capacity and conductivity. The investigation revealed that the capacity of bare Li 4 Ti 5 O 12 samples and those with single silicon doping or carbon coating exhibited rapid decay during high-rate long cycling. By contrast, the capacity of composite LSiAC samples (comprising 87 wt% Li 4 Ti 5 O 12 +3 wt% AC+10 wt% Si) after 1000 cycles at a 5C rate reached 196.56 mAh/g, with a great capacity retention rate (89.37%). This improvement can be attributed to two factors. Firstly, the active carbon coating enhances material conductivity and simultaneously acts as a barrier isolating Li 4 Ti 5 O 12 from the electrolyte LiPF 6 , thereby preventing structural degradation. Secondly, Si doping between Li 4 Ti 5 O 12 crystals leads to an appropriate amount of Si expansion during cycling, effectively increasing the crystal plane spacing and facilitating lithium-ion migration. The proposed modification process is both simple and environmentally friendly, making it suitable for industrial-scale production. This approach holds promise in bolstering the competitiveness of spinel Li 4 Ti 5 O 12 as an anode material in the lithium-ion battery market.