Hybrid catalyst-assisted synthesis of multifunctional carbon derived from Camellia shell for high-performance sodium-ion batteries and sodium-ion hybrid capacitors

Biomass-derived carbon as energy storage materials have gradually attracted widespread attention due to their low cost, sustainability, and inherent structural advantages. Herein, hard carbon (H-1200) and porous carbon (PC-800) for sodium-ion batteries (SIBs), sodium-ion capacitors (SICs) half cells and sodium-ion hybrid capacitors (SIHCs) have been synthesized from the same biomass precursor of Camellia shells through different treatments. H-1200 synthesized by directly high-temperature carbonization possesses a rational graphitic layer structure and plentiful heteroatoms. When applied as anode for SIBs, it exhibits a reversible capacity of 365.5 mAh g^–1 at 25 mA g^–1 and capacity retention 89.0% after 400 cycles at 200 mA g^–1. Additionally, PC-800 prepared by catalytic carbonization of K₂C₂O₄/CaC₂O₄ hybrid catalyst has a sophisticated porous structure and a high surface area of 2186.9 m² g^–1. When employed as a cathode for SICs, it delivers a maximum capacity 104.2 mAh g^–1 at 100 mA g^–1 and 35.0 mAh g^–1 at 5 A g^–1. Furthermore, the all carbon assembled SIHC (H-1200||PC-800) using H-1200 as anode and PC-800 as cathode, features a broad output voltage range (0.01 ~ 4.1 V), high energy density of 161.5 Wh kg^–1, power density of 12896.1 W kg^–1, and superior capacity retention of 90.32% after 10000 cycles at 10 A g^–1. This research result provide a new horizon for constructing low-cost and large-scale production of biomass derived carbon for energy storage materials.