Anti-Perovskite-Tip Dendritic Structure to Enable Separate Catalysis-Deposition Mode for Polysulfides in Li-S Batteries.
basic_science · Level V
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- Also identified by DOI 10.1021/acsnano.5c14687.
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Abstract
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<sub>0.145</sub>In<sub>0.855</sub>Ni<sub>3</sub>N/Cu<sub>0.61</sub>Ni<sub>0.39</sub>@C (CINN) with a separate catalysis-deposition site distribution in the dendrite microstructure is synthesized from layered double hydroxide by a simple g-C<sub>3</sub>N<sub>4</sub> vapor modulation method. The LiPS conversion reaction proceeds in a step-by-step manner, with LiPSs adsorbed and catalyzed through Cu<sub>0.145</sub>In<sub>0.855</sub>Ni<sub>3</sub>N antiperovskite domains at the carbon-dendrite tips, which then diffuse and deposit around the Cu<sub>0.61</sub>Ni<sub>0.39</sub> 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., Li<sub>2</sub>S<sub>4</sub> to Li<sub>2</sub>S<sub>2</sub>) 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 Li<sub>2</sub>S decreases by 48.8 kJ mol<sup>-1</sup>. The CINN-modified Li-S batteries exhibit a high discharge capacity (∼1300 mAh g<sup>-1</sup>), outstanding rate performance (500 mAh g<sup>-1</sup> at 8 C), and great durability (641 mAh g<sup>-1</sup> at 1 C after 400 cycles).