Rational-design heteroatom-doped cathode and ion modulation layer modified Zn anode for ultrafast zinc-ion hybrid capacitors with simultaneous high power and energy densities

Aqueous zinc-ion hybrid capacitors (ZICs) have attracted significant attention due to their high safety and environmental friendliness. However, the imbalanced kinetics between electrodes and the poor compatibility between cathodes and electrolytes have severely restricted the development of ZICs. Herein, a phase transfer strategy driven by electrostatic interaction is used to enable the facile coating of phosphatidylcholine on MOF in an oil-in-water emulsion for the fabrication of N, P, O tri-doped carbon nanocage cathodes. DFT calculations reveal that the most stable adsorption sites for Zn atoms on carbon matrix are P–O sites and N vacancy, which dominate in cathodes. Moreover, the Zn anode is modified by an ion modulation layer to efficiently regulate the Zn-ion diffusion and plating behavior for balancing kinetics between electrodes, as confirmed by the dual-field and electroplating simulations. As expected, the ZICs deliver an outstanding rate capability of 310 F g⁻¹ at 0.5 A g⁻¹ and 175 F g⁻¹ at 200 A g⁻¹, a high energy density of 43 Wh kg⁻¹ at the record high power density of 137.9 kW kg⁻¹. This work provides novel strategies for designing reasonable heteroatom-doped cathodes and balancing kinetics between electrodes to construct ZICs with both high energy and power densities.