A Multifunctional CuP2/Carbon Catalyst: An Effective Adsorption Catalysis Solution for High-Performance Lithium–Sulfur Batteries

Abstract

Lithium-sulfur （Li–S） batteries are promising next-generation energy storage systems owing to their high theoretical energy density and low cost. However, their practical application is severely hindered by the polysulfide shuttle effect and sluggish sulfur redox kinetics. Herein, a multifunctional CuP2/carbon （CuP2/C） catalyst was developed as an adsorption and catalytic conversion platform to simultaneously regulate polysulfide migration and accelerate sulfur conversion reactions. CuP2/C was synthesized via a thermal reaction method, incorporated into a conductive carbon matrix, and deposited onto a commercial polypropylene separator through a scalable spray- coating process. The CuP2/C-coated separator exhibited strong chemical affinity toward lithium polysulfides and effectively accelerated sulfur redox kinetics. Benefiting from the synergistic effects of polysulfide adsorption and electrocatalytic conversion, the modified Li–S cell delivered an initial discharge capacity of 1012 mAh g-1 at 0.2 C and significantly reduced polarization compared with the pristine separator. Moreover, the cell retained 387 mAh g-1 after 400 cycles at 1 C with nearly 100% coulombic efficiency. Under practical conditions with a sulfur loading of 3.0 mg cm-2 and an electrolyte-to-sulfur ratio of 5 μL mg-1, a stable areal capacity of 2.2 mAh cm-2 was achieved. These results demonstrate that the CuP2/C adsorption and catalysis conversion system provides an effective strategy for suppressing polysulfide shuttling and improving the long-term performance of Li–S batteries.