Preparation Of Tin Based Anode Materials By Ball Milling And Their Low Temperature Performances For LIBs

In order to solve the problems of the cycle performance deterioration and the sharp reduction of capacity at low temperature of tin based anode materials caused by the obvious volume effect in the process of charge and discharge,the structure optimization design of tin based composites was carried out.A series of Sn/EG based composites,including Sn/EG,Sn/CNT/EG and Sn/PANI/EG,were prepared by ball milling using nanometer tin powder and expanded graphite(EG)as the main raw materials.The morphology and electrochemical properties of the three electrode materials were tested by various characterization methods.The main research results of this paper are as follows:(1)Sn/EG composites were prepared by ball milling using nanometer tin powder and expanded graphite(EG)as raw materials.The experiments show that the solvent used,the content of tin and the ball-milling time all affect the electrochemical properties of the composites.Sn/EG composite electrode prepared with the best performance as anode material for lithium ion batteries can maintain 735.1 m Ah/g after 120 cycles at a current density of 100 m A/g.As the current density is set at 100,700,and 1A/g,the corresponding reversible capacities are 532.3,275.6,and 223.9 m Ah/g.The specifc capacities are measured to be 635.9,394.1,and 70.9 m Ah/g at the temperature of 25 ℃,0 ℃,and-20 ℃,respectively.(2)A series of Sn/CNT/EG composites with high Sn content were prepared by adding CNT into Sn/EG system.We explored the effects of the tin content and ball-milling time on the electrochemical performance of electrode,and Sn/CNT/EG composite electrode with the best performance delivers a long cycle life of 541.3 m Ah/g after 290 cycles at 100 m A/g and a higher lowtemperature capacity of 641,483.7,and 210.7 m Ah/g at 25 ℃,0 ℃,and 20 ℃,which is obviously higher than that of Sn/EG capacity at the same temperature.(3)Sn/PANI/EG composite was prepared by using polyaniline as coating material.The Sn/PANI/EG composite with the best performance shows ultrahigh cycle capacity and superior rate performance.Sn/PANI/EG shows a high reversible specific capacity of 970.8 m Ah/g at 100 m A/g after 210 cycles and excellent rate capability of 429.9 m Ah/g at 1 A/g.The low temperature performance of C-Sn/PANI/EG prepared by carbonization of Sn/PANI/EG is significantly improved.The reversible capacities of C-Sn/PANI/EG at 25℃,0℃,and-20℃ are 748,565.3,and 263.9 m Ah/g,respectively,which are higher than those at the same temperature of Sn/PANI/EG.