Integrating polysulfide adsorption and electrocatalysis on a mineral-based separator for high-rate and long-life Li–S batteries

Abstract

Lithium–sulfur (Li–S) batteries are regarded as promising next-generation energy storage systems due to their high theoretical specific capacity and energy density. However, their practical application is hindered by the polysulfide shuttle effect, which leads to rapid capacity decay and poor cycling stability. In this work, we design and synthesize a novel composite separator coating, ESrp@CoP, by in situ growth of highly catalytic cobalt phosphide (CoP) nanoparticles on acid-etched serpentine (ESrp), a naturally abundant layered silicate mineral. The ESrp substrate provides a hierarchical porous structure and abundant polar sites (Si–O⁻/Si–OH) for strong physical confinement and chemical adsorption of lithium polysulfides (LiPSs), while the CoP nanoparticles significantly enhance the electrocatalytic conversion kinetics of LiPSs. Systematic physicochemical and electrochemical characterizations confirm the successful construction of the composite and its multifunctional synergy in LiPS management. As a result, Li–S batteries employing the ESrp@CoP-modified separator exhibit remarkable electrochemical performance: high specific capacity (995.7 mAh g⁻¹ at 0.2 C), excellent rate capability, and outstanding long-term cycling stability (78.6% capacity retention after 200 cycles). Even under high sulfur loading (3.9 mg cm⁻²), the battery maintains stable performance. This work demonstrates a cost-effective and efficient mineral-based strategy for suppressing the shuttle effect and advancing the development of high-performance Li–S batteries.