Sponge-like porous sustainable hard carbon as an efficient anode for sodium-ion batteries

Abstract

Renewable, cost-effective, eco-friendly, and abundant biodegradable waste has emerged as a promising resource for developing hard carbon (HC) anode materials for rechargeable sodium-ion batteries (SIBs). This study focuses on synthesizing HC anode materials from mango leaves using hydrothermal carbonization process, and thereafter pyrolysis at 900 °C and 1000 °C. The synthesized HC shows the spongelike morphology along with large specific surface area (88.3 m² g−1). The resulting materials pyrolyzed at 900 °C and 1000 °C, designated as Mango (Mangifera indica) Leaves Hard Carbon (MLHC-900) and (MLHC-1000) respectively, deliver impressive discharge capacities per unit mass of approximately 241 mAh g−1 and 215 mAh g−1 at a current density of 10 mA g−1, respectively. After 1200 cycles at a current density 1000 mA g−1, the MLHC-900 demonstrated superior capacity retention compared to MLHC-1000. These results signify the potential of using biodegradable waste utilizing hydrothermal carbonization to fabricate efficient HC anodes for SIBs. © 2025 Elsevier Ltd