Preparation of Green and High-Performance Industrial Polymer Waste-Derived Hard Carbon Electrodes for Sodium-Ion Battery

Polymer-based hard carbon is a potential anode material for sodium-ion batteries (SIBs) due to their structural controllability and electrochemical characteristics. Despite these advantages, its high cost hinders widespread adoption. This study synthesized a polymer-derived hard carbon material from industrial polymer waste through a facile method. The results show that the interlayer spacing of the prepared material (∼0.37 nm) is significantly larger than graphite, which facilitates sodium-ion intercalation/deintercalation during the charge/discharge cycles. Furthermore, the material’s design, distinguished by a well-developed surface area (i.e., 5.014 m2 g–1), facilitates better electrolyte diffusion and improved ion accessibility, hence enhancing electrochemical performance. The influence of the temperature (900–1500 °C) on the microstructure is examined, revealing that elevated heat treatment temperatures result in enhanced graphitization and superior cycle stability. Among various temperatures, hard carbon synthesized at 1300 °C has superior electrochemical performance as anode material for SIB, with a maximum stable reversible specific capacity of 350 mAh g–1 at 0.1C (1C = 300 mA g–1). This material has an initial Coulombic efficiency (ICE) of around 80% and maintains a high-capacity retention of 98% after 100 cycles at a rate of 0.1C. The findings underscore the viability of polymer-derived hard carbon as an advantageous anode material for SIBs, offering a sustainable and high-performance alternative for extensive energy storage applications.