用于镁硫电池的原位生长NiS的泡沫镍正极集流体

In⁃situ Growth NiS/nickel Foam as Cathode Current Collector of Magnesium-sulfur Batteries

采用原位生长NiS的泡沫镍NiS@Ni(NNF)和铜箔分别作为硫@微孔碳(S@MC)正极材料的集流体,0.4 mol/L(PhMgCl)_(2)-AlCl_(3)+1.0 mol/L LiCl“二代镁锂混合”作为电解液,测试了镁硫电池恒电流和不同倍率下的充放电性能,分析了2种不同的集流体在涂覆相同正极材料下对镁硫电池性能影响的原因.研究发现,采用铜箔集流体的镁硫电池循环后正极极片上观察到明显的裂缝,镁负极表面有分布不均匀的附着物,硫含量略高.采用NNF为集流体时,由于泡沫镍具有缓冲硫正极体积变化的孔道结构,正极极片能基本保持原本的形貌;特别是在NNF上原位生长的NiS可电催化加速多硫化物中间体的转化,减少多硫化物的生成并减缓其穿梭,不干扰镁负极上发生的电化学反应,使镁负极极片表面更为均匀,明显改善了镁硫电池的循环稳定性和倍率性能.

Nickel foam in situ grown NiS and Cu foil were respectively used as the cathode current collectors of magnesium-sulfur(Mg-S)batteries with S@MC cathode and(PhMgCl)_(2)-AlCl_(3)+LiCl/THF hybrid electrolyte.The constant-current discharge-charge cycling and rate performances of the Mg-S batteries were compared and the reason of different performance was analyzed.When using copper foil collector,the cracks were observed on the cathode and obvious uneven distribution with slightly higher sulfur content on magnesium anode.In the case of NNF,the morphology of the cathode can be basically maintained because the pore structure of nickel foam buffers the volume changes of sulfur active material.Importantly,NiS in situ growing on NNF can accelerate the conversion of polysulfide intermediates,reduce the formation of polysulfides and suppress the shuttle,and hardly interfere the electrochemical reaction on the magnesium anode,resulting in more uniform magne⁃sium surface.As a result,the Mg-S battery with NNF cathode current collector exhibits significantly im⁃proved cycle stability and rate performance.