Metallic NiSe₂ nanoarrays towards ultralong life and fast Li₂S oxidation kinetics of Li-S batteries

The complex solid-liquid-solid phase transition in Li-S batteries, the serious shuttle effect of soluble polysulfides, sluggish polysulfide conversion kinetics and the low conductive nature of Li₂S cause a high decomposition barrier, inevitably limiting the development of advanced Li-S batteries. In addition, the severe sedimentation problem of nonconductive Li₂S during the charging process would inevitably hamper the subsequent reaction kinetics of Li-S batteries, especially at high sulfur loading. Herein, this paper, for the first time, reports the construction of a highly conductive sulfur host material (C@NiSe₂) by simulating the decomposition process of Li₂S on the surface of anchor materials, which confirmed that NiSe₂ is more suitable for the Li₂S oxidation process. In addition, the strong binding strength of NiSe₂ with Li₂S is better for the decomposition of Li₂S during the charge process. Therefore, when C@NiSe₂ is used as the electrode material, the batteries exhibited an initial capacity of 1250 mA h g^-1 with a quite low cycle decay of 0.089% per cycle with a sulfur loading of 5 mg cm^-2 at 0.2C. At a high current density of 5C, the battery showed an ultralow cycle decay of 0.019% during 2000 cycles. In addition, with an ultrahigh sulfur loading of 12.0 mg cm^-2, the C@NiSe₂/S electrode could still deliver a significant areal capacity of 9.96 mA h cm^-2, which is good for realizing practical applications of Li-S batteries.