Three-Dimensionally Hierarchical Ni/Ni₃S₂/S Cathode for Lithium-Sulfur Battery

Lithium-sulfur (Li-S) batteries have attracted interest as a promising energy-storage technology due to their overwhelming advantages such as high energy density and low cost. However, their commercial success is impeded by deterioration of sulfur utilization, significant capacity fade, and poor cycle life, which are principally originated from the severe shuttle effect in relation to the dissolution and migration of lithium polysulfides. Herein, we proposed an effective and facile strategy to anchor the polysulfides and improve sulfur loading by constructing a three-dimensionally hierarchical Ni/Ni₃S₂/S cathode. This self-supported hybrid architecture is sequentially fabricated by the partial sulfurization of Ni foam by a mild hydrothermal process, followed by physical loading of elemental sulfur. The incorporation of Ni₃S₂, with high electronic conductivity and strong polysulfide adsorption capability, can not only empower the cathode to alleviate the shuttle effect, but also afford a favorable electrochemical environment with lower interfacial resistance, which could facilitate the redox kinetics of the anchored polysulfides. Consequently, the obtained Ni/Ni₃S₂/S cathode with a sulfur loading of ∼4.0 mg/cm² demonstrated excellent electrochemical characteristics. For example, at high current density of 4 mA/cm², this thick cathode demonstrated a discharge capacity of 441 mAh/g at the 150th cycle.