Alveoli‐Inspired Carbon Cathodes with Interconnected Porous Structure and Asymmetric Coordinated Vanadium Sites for Superior Li−S Batteries

Abstract

Accelerating sulfur conversion catalysis to alleviate the shuttle effect has become a novel paradigm for effective Li‐S batteries. Although nitrogen‐coordinated metal single‐atom (M‐N4) catalysts have been investigated, further optimizing its utilization rate and catalytic activities is urgently needed for practical applications. Inspired by the natural alveoli tissue with interconnected structure and well‐distributed enzyme catalytic sites on the wall for the simultaneously fast diffusion and in‐situ catalytic conversion of substrates, here, we proposed the controllable synthesis of bioinspired carbon cathode with interconnected porous structure and asymmetric coordinated V‐S1N3 sites for efficient and stable Li‐S batteries. The enzyme‐mimetic V‐S1N3 shows asymmetric electronic distribution and high tunability, therefore enhancing in‐situ polysulfide conversion activities. Experimental and theoretical results reveal that the high charge asymmetry degree and large atom radius of S in V‐S1N3 result in sloping adsorption for polysulfide, thereby exhibiting low thermodynamic energy barriers and long‐range stability (0.076% decay over 600 cycles).

Silica Hard Template Extracted from Semicoke Residue Toward the Hierarchical Porous Carbon Skeleton for Lithium–Sulfur Batteries

“…In order to mitigate the infamous “shuttle effect” and the highly insulating nature of S, a variety of cathode host materials have been proposed to increase the electrical conductivity of the cathode material, block S, and slow down the diffusion of polysulfides, including metallic compounds, − conductive polymers, , metal organic frameworks (MOFs) and covalent organic frameworks (COFs), − and different types of carbon. − Among them, porous carbon has fast electron transport and a high sulfur trapping ability due to its outstanding electrical conductivity, large pore size, high specific surface area, and adjustable pore size distribution . In addition, the ultrahigh specific surface area of porous carbon can facilitate surface reactions or interactions such as adsorption and catalysis, while reducing the volume expansion of the sulfur cathode. , However, the nonpolar nature of carbon materials leads to poor binding of carbon materials to lithium polysulfides (LiPSs), resulting in rapid capacity decay during late cycling. , Therefore, highly polar carbon materials with adsorption and electrocatalytic effects have been extensively explored, and it has been shown that carbon materials doped with heteroatoms have better electrochemical properties because heteroatom (O, N, P, and S) doping can effectively increase the polarity of carbon, thus improving the adsorption behavior of LiPSs.…”