关键词: 锂离子电池, 低温充电, 合金负极, 倍率性能

Abstract:

The performance of lithium-ion batteries (LIBs) is severely degraded at low temperatures, hindering further development and applications. The commercial graphite anode used in LIBs exhibits slow lithium-ion diffusion and a low lithiation potential, which can lead to lithium plating and consequently poor low-temperature charging capability. In contrast, tin-based anodes show high capacities and moderate lithiation potentials, thus resulting in superior low-temperature performance. This study presents a facile approach to prepare SnSb-Li₄Ti₅O₁₂ composites through a simple ball-milling method. A fine balance between high capacity and cycling stability was achieved with a 30% LTO composite, which displays excellent high-rate lithium storage capability and cycling stability at room and low temperatures. Specifically, after 300 cycles at 30 ℃, the composite material delivers a specific capacity of 536 mAh/g, with a capacity retention rate close to 90%. Even at a high rate of 20 A/g (34C), the specific capacity remains at around 280 mAh/g, approximately 50% of that at 0.2 A/g. When cycling 100 times at -30 ℃ and a current density of 0.2 A/g, a reversible specific capacity of about 413 mAh/g was obtained (74% of room temperature capacity). Moreover, at -30 ℃ and a rate of 1.0 A/g, a moderate lithiation potential is maintained, and the capacity can reach 61% of the value at room temperature. The results suggest that the phase structure of SnSb remains intact during cycling, which ensures the cycling stability and high-rate capacity. This work demonstrates the possibility of low-temperature applications of SnSb-LTO composite anode materials and provides a basis for the development of fast charging LIBs at low-temperature.

Key words: lithium-ion battery, low-temperature, alloy anode, rate capability