Morphology Control of Li2S Deposition via Geometrical Effect of Cobalt-Edged Nickel Alloy to Improve Performance of Lithium–Sulfur Batteries

Rechargeable lithium–sulfur batteries operate based on the interconversion between sulfur and Li₂S. Due to its insoluble and insulated nature, Li₂S deposition is kinetically sluggish, which has an important effect on  performance of lithium–sulfur batteries. In this work, cobalt-edged  nickel alloy is designed and used as host material of sulfur cathodes to  manipulate the behavior and morphology of Li₂S deposition. It is found that Co and Ni have different catalytic kinetic characteristics for Li₂S deposition reactions, and the difference in nucleation and growth rates of Li₂S and geometrical effect of Co-edged Ni alloy can cause a well-spaced  morphology to prevent premature surface passivation, thereby improving  sulfur utilization and rate capability of the cathodes. As a result, the thick sulfur cathode using cobalt-edged nickel as host material with a sulfur loading of 4.0 mg cm⁻² shows an initial capacity of 1229.3 mA h g⁻¹ at electrolyte/sulfur ratio of 8 µL mg⁻¹, as well as high capacity retention of 92.2% at 0.2 C during 100 cycles.  These results provide an alternative perspective not only for  developing new mixed host materials for lithium–sulfur batteries, and also for further understanding the existing works using composite host materials.