A rice husk-derived SiOx/C composite for effective lithium-sulfur battery separator modification

Abstract

Lithium–sulfur (Li–S) batteries offer several advantages including high specific capacity, high energy density, cost-effectiveness, and non-toxicity. However, challenges such as the shuttle effect and low electrical conductivity hinder the reversibility during cycling. Herein, we introduce a sustainable rice husk-derived SiO_x/porous carbon composite (S-MRH) for separator modification in high-performance Li–S batteries. The S-MRH composite, synthesized via a salt-assisted method without toxic chemicals, features amorphous polar SiO_x and porous carbon working synergistically. SiO_x promotes a catalytic effect that suppresses polysulfide dissolution, while porous carbon provides an open conductive network. An S-MRH-coated polypropylene (S-MRH/PP) separator exhibited a high specific capacity of 1507.7 mA h g⁻¹ at 0.1C, which is attributed to improved sulfur utilization. Compared to different separators, the S-MRH/PP separator demonstrated a superior rate performance of 766.5 mA h g⁻¹ at 3C. Even under high sulfur loading and lean electrolyte conditions, S-MRH/PP exhibited good cycling stability with high capacities. This study highlights the potential of biomass-derived materials in Li–S batteries and offers insights into SiO_x/C synthesis applicable to various energy storage systems.