From Waste to Power: Gas–Solid Coupling-Modified Rubber Carbon Anodes with 87% Coulombic Efficiency for Sodium-Ion Batteries

Rubber, an organic polymer, is notoriously difficult to degrade. The large quantities of waste rubber decommissioned annually pose significant ecological and environmental challenges. This study proposes a novel strategy to transform waste rubber into high-performance carbon anode materials for sodium-ion batteries (SIBs) through gas–solid intersection modification with ethanol-assisted heat treatment. This innovative approach optimizes the microstructure of rubber-derived carbon, effectively reducing the surface sulfur content and forming more pseudographite microcrystalline structures. As a result, the initial Coulombic efficiency of the anode material is significantly improved from ∼78% to ∼87%, and the rate performance is enhanced, maintaining a reversible specific capacity of 157 mAh g–1 after 300 cycles at a high current density of 12 C. This work not only provides a new pathway for the high-value-added recycling of waste rubber but also contributes to the development of advanced carbon anode materials for SIBs, offering dual benefits for environmental sustainability and energy storage applications.