Boron and nitrogen co-doped sodium alginate-based porous carbons for durable and fast Zn-ion hybrid capacitors

In recent years, zinc-ion hybrid capacitors (ZIHCs) have attracted increasing attention due to their environmental friendliness and excellent electrochemical properties. However, their performance is mainly limited by the electrochemical performance of the cathode, so it is necessary to develop an advanced cathode material. N, B co-doped sodium alginate-based porous carbon (NBSPC) was prepared by one-step co-carbonization using sodium alginate as the matrix and NH₄B₅O₈ as the N and B source. This N, B co-doping strategy improves the pore structure of the carbon materials and increases the number of surface functional groups, greatly improving the capacitive behavior of the raw materials and thus improving their electrochemical performance. When used as the cathode in ZIHCs, the NBSPC had an excellent rate performance (85.4 mAh g⁻¹ even at ultra-high current density of 40 A g⁻¹) and good cycling stability (15 000 cycles at 20 A g⁻¹ with a capacity retention rate of 94.5%).