石墨孔结构对锂离子电池倍率性能的影响

Effect of graphite pore structure on rate capability of Li-ion battery

讨论负极材料特征对锂离子电池倍率性能的影响。对比4种人造石墨样品的结构、形貌等特征及倍率性能,发现孔结构状况特别是纳米级孔的分布,对倍率性能的影响较大,即电池的倍率性能与石墨纳米级孔的数量正相关。原因可能是:负极材料孔洞越多,提供的Li+迁移通道越多,可提高颗粒内Li+扩散的能力;孔洞越多的石墨材料,制成极片后的孔隙越丰富,极片的渗液能力较强,可缩短Li+传输路径。孔结构最丰富样品的孔体积为0.0052 cm 3/g,循环性能最好。制备的电池以5.0 C充电、1.0 C放电(2.00~3.65 V),循环寿命为233次,约是孔体积为0.0029 cm 3/g样品的1.75倍。

The influence of the characteristics of anode material on the rate capability of Li-ion battery was discussed.The characteristics of structure,morphology and rate capability of four kinds of artificial graphite samples were compared.It was found that the pore structure,especially the distribution of nanoscale pores had a greater impact on the rate capability.The rate capability of battery was positively related to the number of nanoscale pores.The reason might be:the more holes in the cathode material,the more Li+migration channels provided,which could improve the ability of Li+diffusion in the particles;the more holes in the graphite material,the more abundant nanoscale pores in prepared plates,the liquid seepage in the plates was relatively strong,which could shorten Li+transport distance.The sample with the most abundant pore structure had a total pore volume of 0.0052 cm 3/g and showed the best cycle performance.When charged at 5.0 C and discharged at 1.0 C(2.00-3.65 V),the service life of prepared battery was 233 times,which was about 1.75 times of which prepared by the sample with a pore volume of 0.0029 cm 3/g.