Biomass derivatives self-assembled into multiple heteroatoms doped carbon sphere for aqueous Zn-ion hybrid capacitors

Zinc ion hybrid capacitors (ZHCs) as a new type of energy storage device, possess high power density, low cost, and safety. However, the unsatisfactory energy density of ZHCs caused by low output voltage and small specific capacitance restricts its practical application. Herein, a novel multiple heteroatoms doping carbon sphere is achieved from the mixture precursors of glucosamine hydrochloride and sodium lignosulfonate via chemical activation strategy. High specific surface area, rich O/N/S-containing functional groups, and good electric conductivity endow the resultant carbon sphere with a superior specific capacity of 233 mAh g−1 at 1 A g−1 and outstanding capacity retention of 83 mAh g−1 at 50 A g−1. Remarkably, as-assembled ZHC exhibits a conspicuous energy density of 209.7 Wh kg−1 at 900 W kg−1, and its energy density still maintains 74.7 Wh kg−1 at 45,000 W kg−1. Furthermore, after 10,000 cycles, the resultant carbon sphere achieves 100% capacitance retention. This work offers a feasible strategy for carbon cathode materials with enhancing energy density and rate capability, and concurrently reasonable cycling stability.