Ni/SiO2/Graphene-modified separator as a multifunctional polysulfide barrier for advanced lithium-sulfur batteries

Lithium-sulfur batteries with high energy density and low cost are widely recognized as one of the most promising next generation energy storage devices. However, their practical applications are hampered by the notorious polysulfide shuttle effect, which leads to a series of problems including the loss of active materials and poor cycling efficiency. We herein develop a Ni nanoparticles embedded in silica (Ni/SiO2) nanosheet spheres, which are mixed with graphene, and then coated on the separator as a highly effective lithium polysulfides (LiPSs) blocking layer. The Ni/SiO2/Graphene-modified separator is able to anchor LiPSs through affinity towards LiPSs by silica and Ni atoms, and enable rapid conversion between LiPSs and Li2S2/Li2S by abundant Ni catalytic sites. The mesoporous hollow structure of the Ni/SiO2 nanosheet spheres also facilitates Li+ diffusion. As a result, Li–S batteries with the Ni/SiO2/Graphene-modified separator achieve a stable cycling performance (specific capacity of 922 mAh g−1 after 100 cycles, with the cyclic decay rate of 0.28%), coulombic efficiency of approximately 100%, and a high rate capability (782 mAh g−1 at 2 C). Our work provides an effective strategy to build a multifunctional separator for highly stable Li–S batteries.