Atomic-Level Modulation of Imine and Cobalt Enables a Homogeneous Co5.47N Catalyst for High-Performance Lithium-Sulfur Batteries

Abstract

Electrocatalyst presents a promising strategy for enhancing sulfur utilization and cycling stability in lithium-sulfur (Li-S) batteries, especially under demanding operational conditions. However, conventional catalytic strategies demonstrate undesirable effects in high-loading lithium-sulfur batteries, primarily attributed to the absence of efficient catalyst dispersion strategy. In this work, it successfully anchored a diverse range of Co-containing catalysts uniformly onto the COF-derived carbon through the unique chelation between cobalt atoms and imine groups. This strategy greatly enhances catalytic efficiency and also prevents the formation of “dead” catalysts, maximizing catalyst utilization. Experimental measurements and simulations reveal that the Co_5.47N nanocrystal integrated with COF-derived carbon (Co_5.47N@NC) demonstrates remarkable catalytic efficiency in accelerating polysulfide conversion, primarily owing to the significant modulation of the d-band center of cobalt atoms within the Co_5.47N@NC. Remarkably, the Li-S battery with Co_5.47N@NC achieves a specific capacity of 1288 mAh g⁻¹ at 0.3 C and maintains 92% capacity retention over 200 cycles. The Co_5.47N@NC system with a sulfur loading of 5.7 mg cm⁻² and an E/S ratio of 4.0 µL mg⁻¹, still sustains a specific capacity of 1314 mAh g⁻¹. Consequently, a 1.0 Ah-level pouch cell delivers an energy density of 411 Wh kg⁻¹ and maintains stable cycling.