一维氮化钒纳米线在锂硫电池中的研究

Study on One-Dimensional Vanadium Nitride Nanowires in Lithium Sulfur Batteries

锂硫电池以其高理论比容量、高能量密度、储量丰富等优点得到了人们的广泛关注,但锂硫电池充放电过程中存在的多硫化锂严重的穿梭效应等缺陷制约着其进一步发展。为了能有效抑制穿梭效应、改善锂硫电池性能,采用水热法制备了一种结晶良好、元素分布均匀的一维氮化钒纳米线,将其作为隔膜修饰材料后,电解液间的浸润性得到了改善,离子传输性能得到了提升;同时,修饰层的形成有效地覆盖了初始隔膜较大的孔洞,从而有效抑制了多硫化锂的穿梭效应,电池的倍率性能和循环性能得到了提升。0.1C下的初始放电容量可达1055 mAh·g^(-1),0.5C、1C、2C、5C下的放电容量也能分别维持在862m Ah·g^(-1)、803m Ah·g^(-1)、736m Ah·g^(-1)和651m Ah·g^(-1),1C循环后的容量能维持在641 mAh·g^(-1)。当正极硫负载量为3 mg·cm-2时,3C循环后的容量也能维持在645 m Ah·g^(-1)。

Lithium sulfur(Li-S)battery has attracted extensive attention for its advantages of high theoretical specific capacity,high energy density and abundant reserves,but its further development is restricted by the serious shuttle effect of lithium polysulfide(LPS)in the charging and discharging process.In order to effectively inhibit the shuttle effect and improve the performance of Li-S batteries,a one-dimensional vanadium nitride nanowire with good crystallization and uniform distribution of elements has been prepared by hydrothermal method.When the vanadium nitride nanowires were used as separator modification material,the infiltrative property between the electrolyte and the electrolyte can be improved,and the ion transport performance can be improved.Meanwhile,the formation of the modification layer can effectively cover the large holes of blank separator,thus effectively inhibiting the shuttle effect of LPS,and improving the ratio performance and cycle performance of the battery:The initial discharge capacity of 1055mAh·g^(-1) at 0.1C can be obtained,and the discharge capacity of 862mAh·g^(-1),803mAh·g^(-1),736mAh·g^(-1) and 651mAh·g^(-1) can be maintained at 0.5C,1C,2C and 5C,respectively.The cycle capacity of 641mAh·g^(-1) at 1C can be maintained,and when the positive sulfur loading reaches to 3mg·cm-2,the cycle capacity of 645mAh·g^(-1) can also be maintained at 3C.