Integrated Soft-Hard Carbon Derived from Hawthorn Seeds as a High Performance Anode for Sodium Storage

Biomass-derived hard carbon has emerged as a highly promising anode material for sodium-ion batteries (SIBs), owing to its exceptional sodium storage capacity, cost-effectiveness, and sustainable sourcing advantages. However, its widespread commercialization faces significant challenges, including unsatisfactory carbon yield and inadequate rate capability. To address these limitations, this study presents a facile approach to synthesize high-performance soft-hard carbon composites through the strategic combination of pitch and hawthorn seeds. Our research demonstrates that the presence of highly graphitized soft carbon effectively mitigates the inherent drawbacks of hard carbon material. Specifically, the optimized composite with a hawthorn seed-to-pitch mass ratio of 100:10 exhibits superior electrochemical performance compared to pure hawthorn seed-derived hard carbon prepared under identical conditions. The incorporation of pitch-derived soft carbon enhanced the carbon yield from 45.8% to 51.5%. The composite anode delivers a high capacity of 295.9 mAh g-1 (at 20 mA g-1), an outstanding cycling stability (retaining 75.0% capacity retention after 1000 cycles at 500 mA g-1), and significantly enhanced rate capability. Through these studies, we attempted to establish fundamental structure-property relationships and provide valuable guidance for their commercial implementation in SIB systems.