Optimally Carbonized Mangrove Wood-Derived Hard Carbon with a Soft Carbon Coating for High-Performance Sodium-Ion Battery Anodes

초록

Sodium-ion batteries (SIBs) are emerging as promising alternatives to lithium-ion batteries owing to the abundance of sodium resources and the limited supply of lithium raw materials. However, the development of high-performance anode materials remains a critical challenge owing to the relatively low initial coulombic efficiencies (ICEs) and limited reversible capacities of conventional carbon-based anodes. Herein, hard carbon (HC) from mangrove wood was synthesized via controlled carbonization, and its electrochemical performance was systematically investigated. HC prepared by carbonization at 1200 degrees C (MWHC-1200) exhibited the best performance, delivering a high reversible capacity of 266.6 mAh g-1 and an ICE of 75%. Pitch-derived soft carbon coatings (containing 5, 10, or 15 wt% pitch) were applied to HC synthesized at the optimal carbonization temperature to further enhance Na+-storage performance. Notably, the composite containing 10 wt% pitch (PC-10) exhibited the best electrochemical performance, delivering a high reversible capacity of 291.5 mAh g-1, an ICE of 82%, a capacity retention of 90.4% after 200 cycles, and an excellent rate capability. These improvements were associated with the suppression of irreversible reactions and improvement in interfacial stability. This study offers a simple yet effective approach for improving the electrochemical properties of biomass-derived HC and provides insights into the design of practical SIB anodes.

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