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

Abstract Li4Ti5O12, 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 Li4Ti5O12 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 Li4Ti5O12 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% Li4Ti5O12+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 Li4Ti5O12 from the electrolyte LiPF6, thereby preventing structural degradation. Secondly, Si doping between Li4Ti5O12 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 Li4Ti5O12 as an anode material in the lithium-ion battery market.