摘要
锂硫电池具有高的能量密度,被认为具有前景的下一代动力能源存储体系。然而仍有一些重要的问题制约着锂硫电池的实际应用,如活性物质的低利用率和容量的快速衰减。通过多离子调控的方法一步制备多孔三维氮硫双掺杂的石墨烯,不仅可以提高纳米碳材料对多硫化合物的亲和力,而且改变组装方式,形成的三维网络结构更有利的孔结构的形成、适应充放电过程中硫的体积变化和对多硫化锂的吸附限制作用。制备的复合硫正极材料电池展示了极好的倍率性能,如在5C的放电倍率下,电池的比容量可达613 mA h g~(-1),在2C的放电倍率下,1500次循环后可逆容量仍有462 mA h g~(-1),每次循环的容量衰减率低至0.028%。在0.2C充放电倍率下,当提高电池的活性物质的面积载量至6.3 mg cm~(-2)时,电池的面积容量可达5.1 mAh cm~(-2)。在目前报道的双掺杂碳-硫正极材料中,我们报道的电池性能是处在前列。
Lithium/sulfur battery is a promising next-generation energy storage system owing to its high theoretical energy density,and low active material utilization and rapid capacity fading remain to be solved.We report a facile one-pot method to prepare porous 3D N,S-codoped graphene with multi-ion mixture modulations.The modulation can not only improve the surface affinity to polysulfides,but also alter their assembling manner and render pore morphology.The cell also has an excellent rate performance and stability,showing 613 mA h g~(-1) at 5C and maintaining 462 mA h g~(-1) after 1500 cycles at 2C with capacity fading as low as 0.028%per cycle.Moreover,a high areal capacity of 5.1 mA h cm~(-2) at 0.2C is achieved at an areal sulfur loading of 6.3 mg cm~(-2),which are the best values reported so far for dual-doped sulfur cathodes.
引文
[1]Wang,J.;Cheng,S.;Li,W.;Lin,H.;Zhang,Y.J.Power Sources 2016(321),193
[2]Li,H.;Yang,X.;Zhang,Y.,Nano Energy,2015(12),468
