Octopus-Inspired Design of Apical NiS2 Nanoparticles Supported on Hierarchical Carbon Composites as an Efficient Host for Lithium Sulfur Batteries with High Sulfur Loading.

Developing high-performance Li-S batteries with high sulfur loading is highly desirable for practical application and remains a major challenge. To achieve this goal, the following requirements for designing carbon/metal compound composites need to be met: (i) the carbon materials need to exhibit suitable specific surface area, void structure, and electrical conductivity; (ii) the weight content of the metal compounds should be low; and (iii) the metal compounds need to show a strong adsorption and efficient electrocatalytic function for LiPSs. In this study, inspired by the body structure of an octopus, a new carbon/NiS2 hierarchical composite is reported, in which the apical NiS2 nanoparticles (0D) on a 1D carbon nanotubes (CNTs) are supported on a three-dimensional carbon (3DC) framework (3DC-CNTs-NiS2). The 3DC-CNTs-NiS2 composite has a high specific surface area (271 m2 g-1), good electrical conductivity, and low NiS2 content (9.2 wt %), and the apical NiS2 nanoparticles are capable of adsorption and electrocatalysis toward LiPSs, demonstrated by both electrochemical characterization and theoretical calculation. When used as a cathode host of the Li-S battery, it exhibits an ultra-stable cycling performance with a fade rate of 0.043% per cycle over 1000 cycles; even with a high S loading (6.5 mg cm-2 with 90 wt % of S), the soft package battery delivers a high area capacity of 5.0 mAh cm-2 under the E/S ratio of 5 µLE mg-1s. This work provides a new approach to design and fabricate multi-functional S hosts with high S loading.