SnSb-Li_(4)Ti_(5)O_(12)复合负极材料低温高倍率储锂特性研究

High-rate lithium storage performance of SnSb-Li_(4)Ti_(5)O_(12) composite anode for Li-ion batteries at low-temperature

低温环境下,锂离子电池的性能明显下降,严重限制了其在寒冷地区的应用推广。尤其是,商业化的石墨负极材料锂离子扩散较慢且嵌锂电位低,易出现析锂风险而使锂离子电池的低温充电能力差。相比之下,Sn基负极材料具有较高的储锂容量和适中的嵌锂电位,具有良好的低温应用前景。本文通过球磨方法,将Sn Sb与Li_(4)Ti_(5)O_(12)(LTO)进行复合,制备出了系列Sn Sb-Li_(4)Ti_(5)O_(12)复合负极材料。实验结果表明,当LTO含量为30%时,复合负极材料能兼顾高容量,同时具备良好的常、低温循环稳定性和高倍率储锂能力。在30℃下,以0.2 A/g循环300次后比容量为536 m Ah/g,容量保持率接近90%;即使在20 A/g (34C)的高倍率下比容量仍有280 m Ah/g。并且在-30℃下,以0.2 A/g循环100次后稳定容量为413 m Ah/g,1.0 A/g倍率下能保持适中嵌锂电位,嵌锂容量也可达其常温容量的61%。研究结果表明,LTO复合后Sn Sb的物相结构能够在循环过程中保持完整,保证了其低温条件下高倍率脱锂过程的循环稳定性。这项工作展现了Sn Sb-Li_(4)Ti_(5)O_(12)复合负极材料的低温应用潜力,为构建具有低温快速充电能力的锂离子电池提供材料基础。

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-Li_(4)Ti_(5)O_(12) 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.