Effect of Si Doping and Active Carbon Surface Modifications on the Structure and Electrical Performance of Li4Ti5O12 Anode Material for Lithium-Ion Batteries.

Autor: Kuang, Huan, Xiao, Li, Lai, Yuan, Shen, Li, Zhou, Anni, Wu, Juan, Zhu, Yirong
Zdroj: Ionics; Mar2024, Vol. 30 Issue 3, p1307-1317, 11p
Abstrakt: The spinel lithium-ion battery anode material Li4Ti5O12 (LTO) exhibits stable cycling and is less prone to lithium dendrite and solid electrolyte interphase (SEI) films. However, its theoretical capacity and conductivity are low within the electrochemical window of 1.0–3.0 V. In this study, we utilized active carbon (AC) coated and micron Silicon (Si) doped Li4Ti5O12, applying an extended electrochemical window of 0.01–3.0 V during cycling to enhance the material's electrochemical performance. Our investigation revealed that bare LTO sample as well as those with single Silicon doping or active carbon coating experienced rapid decay during high-rate long cycling tests. Conversely, the Silicon-carbon composite LSiAC sample (87 wt% Li4Ti5O12 + 3 wt% AC + 10 wt% Si) demonstrated a capacity of 349.19 mAh g−1 (98.28%) at a 1C rate after 200 cycles, and achieved a capacity of 196.56 mAh g−1 (89.37%) after 1000 cycles at a 5C rate,; in comparison, bare LTO exhibited capacities of only 230.98 mAh g−1 (1C-89.71%)and 145.63 mAh g−1 (5C-82.48%). This improvement can be attributed to three factors: first, the active carbon enhances material conductivity while the active carbon coating and SEI films simultaneously as a barrier isolating Li4Ti5O12 from the electrolyte LiPF6, thereby preventing structural degradation; second, micron Si doping into Li4Ti5O12 crystals introduces additional capacity and leads to an appropriate amount of expansion during cycling, effectively increasing crystal plane spacing and facilitating Li+ migration. Final, the multi-layer core–shell structure consisting of Li4Ti5O12, active carbon coating, and SEI films acts as the buffer successfully limits the Si-Li15Si4 phase transition volume expansion. The proposed modification process is straightforward 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. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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