Abstract:

Lithium-sulfur batteries have a higher theoretical energy density and are considered to be one of the most promising next-generation high-energy-density energy storage devices. However, the commercialization of lithium-sulfur batteries is seriously hindered by capacity decay and poor cyclic life caused by polysulfide shuttle. Manganese dioxide nanosheets were prepared by redox method using graphene oxide nanosheets as template. TEM, XRD, FTIR, SEM, AFM were used to characterize the microstructure and morphology of the manganese dioxide nanosheets and the modified separator. The electrochemical properties of the manganese dioxide modified separator were tested by using constant current charge and discharge, cyclic voltammetry and electrochemical impedance method. The results show that the manganese dioxide nanosheets can cover the micropores on separator surface of polypropylene uniformly, thus effectively inhibiting the shuttle of polysulfide through physical barrier and catalysis, and improving the specific capacity and cycle stability of lithium-sulfur battery.

Key words: nanomaterials, membranes, catalysis, lithium-sulfur batteries, manganese dioxide nanosheets, inhibition of shuttle effect, cyclic stability

摘要：

锂硫电池具有较高的理论能量密度，被认为是最有发展潜力的下一代高能量密度储能器件之一。然而多硫化物穿过隔膜形成的穿梭效应导致电池容量衰减过快、使用寿命降低，严重阻碍了锂硫电池商业化。以层状氧化石墨烯为模板，采用氧化还原法合成了二氧化锰纳米片，通过低压抽滤获得二氧化锰改性隔膜。利用TEM、XRD、FTIR、SEM、AFM等对该二氧化锰纳米片及改性隔膜的微观结构、形貌等进行表征；采用恒电流充放电、循环伏安法、电化学阻抗法对二氧化锰改性隔膜电化学性能进行测试。研究结果表明，二氧化锰纳米片能均匀覆盖聚丙烯隔膜表面的微孔，通过物理阻隔和催化作用，有效抑制了多硫化物的穿梭，提高了锂硫电池的比容量和循环稳定性。

关键词: 纳米材料, 膜, 催化作用, 锂硫电池, 二氧化锰纳米片, 抑制穿梭效应, 循环稳定性