リチウム硫黄電池におけるポリサルファイドの分離触媒-析出モードを可能にするアンチペロブスカイト型樹枝状構造

Catalytic conversion of the sulfur reduction reaction is regarded as a crucial approach to accelerate the conversion kinetics and inhibit the shuttle effect of soluble lithium polysulfide (LiPS) intermediate products in a high-capacity lithium-sulfur (Li-S) battery system. Exploiting advanced catalysts and designing their microstructure to achieve efficient and durable Li-S batteries is still a challenge. Herein, a composite catalyst Cu_0.145In_0.855Ni₃N/Cu_0.61Ni_0.39@C (CINN) with a separate catalysis-deposition site distribution in the dendrite microstructure is synthesized from layered double hydroxide by a simple g-C₃N₄ vapor modulation method. The LiPS conversion reaction proceeds in a step-by-step manner, with LiPSs adsorbed and catalyzed through Cu_0.145In_0.855Ni₃N antiperovskite domains at the carbon-dendrite tips, which then diffuse and deposit around the Cu_0.61Ni_0.39 alloy particles embedded in the substrate carbon. This dendritic microstructure maximizes the spatial utilization and durability of catalytic sites. This rational spatial distribution of different functional domains creates a polysulfide nucleation process consisting of top catalysis, diffusion, and substrate deposition. The partial substitution of In atoms by Cu in antiperovskite intensifies the electron-loss ability of In, which can break the Li-S and S-S bonding of long-chain polysulfides, catalyzing the rate-determining step (e.g., Li₂S₄ to Li₂S₂) of the LiPS conversion reaction. Benefiting from the above-mentioned advantages of the CINN catalyst, the nucleation polarization of the Li-S battery is reduced from 34 to 9 mV, and the activation energy of LiPS conversion into Li₂S decreases by 48.8 kJ mol^-1. The CINN-modified Li-S batteries exhibit a high discharge capacity (∼1300 mAh g^-1), outstanding rate performance (500 mAh g^-1 at 8 C), and great durability (641 mAh g^-1 at 1 C after 400 cycles).