摘要
锂硫电池的理论比容量高达1675 mAh·g~(-1),理论能量密度是传统锂离子电池的3-5倍,面对移动交通、大规模储能等领域等对高比容量化学电源日益增长的需求,有着良好的应用前景~([1])。然而锂硫电池放电过程中存在多硫化物的"穿梭效应",这是导致锂硫电池循环性能不佳的最主要因素。传统的硫碳复合材料并无法有效解决多硫化物的"穿梭效应"。我们通过以PVP为软模板的方法合成了一种氧化钴的纳米片状材料,将氧化钴与硫进一步复合后得到了S/Co_3O_4复合材料。作为锂硫电池的正极材料表现出较好的电化学性能,这种良好的电化学性能表现,源自于氧化钴在电池反应过程中对多硫化物中间体有很好的吸附作用,从而在一定程度上抑制了穿梭效应,使电池性能得到了提升。该复合材料在0.5 C的电流密度下,首圈可逆容量为1037mAh·g~(-1),经过140圈循环充放电后依然保持有698 mAh·g~(-1)的可逆容量;而且在较大的1C的电流密度下,经过300圈的长循环充放电,可逆容量仍然可以达到600 mAh·g~(-1)以上。
Lithium-sulfur batteries have attracted increasing attention because of their high theoretical capacity.Using sulfur/metal oxides composites as the cathode materials has been demonstrated as an effective strategy to reduce the "shuttle effect" and improve the cycle stability as well.In this work,cobaltosic oxide nanosheets are prepared to improve both capability and cycling stability of lithium-sulfur batteries.In the resulting S/Co_3O_4 composites,cathodes with sulfur loading of 70 wt%could retain a high capacity 698 m Ah/g after 140 cycles at a rate of 0.5C and above 600 m Ah/g after 300 cycles at a high charge/discharge rate of 1C.
引文
[1]Yin Y.X.;Xin S.;Guo Y.G.;et al.,Angew.Chem.Int.Ed.,2013,52(50):13186.
