Zinc-Ion Hybrid Capacitor Energy Storage Technologies

Zinc-ion hybrid capacitors represent a versatile class of aqueous energy storage devices that bridge the gap between high-power supercapacitors and high-energy zinc-ion batteries. By combining rapid ion adsorption at a high-surface-area cathode with reversible zinc plating and stripping at the anode, these systems deliver both elevated power density and substantial energy capacity within a safe, non-flammable electrolyte. Core components include a zinc metal negative electrode, a porous carbon or pseudocapacitive positive electrode, a compatible aqueous electrolyte (often zinc sulfate based) and a separator tailored to mitigate dendrite formation and self-discharge. The dual-storage mechanism relies on electric double-layer capacitance at the cathode surface and Faradaic redox reactions at heteroatom-doped interfaces, enabling fast charge–discharge cycles alongside long-term stability. Recent advances have focused on tuning carbon microstructure, introducing multi-scale porosity, incorporating redox-active oxide or polymer phases, and optimising electrolyte formulations to expand the voltage window and suppress side reactions. Challenges remain in enhancing energy density without sacrificing cycle life, understanding self-discharge phenomena, and developing flexible or micro-scale formats for wearable and integrated applications. The global abundance of zinc, combined with the benign nature of aqueous electrolytes, renders these devices highly attractive for grid buffering, load levelling and portable power systems.

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Zinc-Ion Hybrid Capacitor Energy Storage Technologies publication trend

The graph below shows the total number of articles in zinc-ion hybrid capacitor energy storage technologies across all publications each year (not limited to Nature Index journals).

Technical terms

Zinc-ion hybrid capacitor (ZHC): A device that combines battery-type zinc plating/stripping at the anode with capacitor-type ion adsorption at the cathode in an aqueous electrolyte.

Electric double-layer capacitance (EDLC): Charge storage mechanism arising from the electrostatic accumulation of ions at the interface between electrode and electrolyte without Faradaic reactions.

Pseudocapacitance: Faradaic charge storage involving fast, reversible redox reactions at or near the electrode surface, contributing to capacitive behaviour.

Faradaic redox process: Electron transfer reactions in which ions undergo oxidation or reduction, storing energy through chemical transformations.

Heteroatom doping: Introduction of elements such as nitrogen, boron or oxygen into a carbon matrix to create active sites that enhance ion adsorption, conductivity and redox activity.

Zinc plating/stripping: Reversible deposition and dissolution of metallic zinc at the anode during charge and discharge, forming the basis of the device’s energy storage cycle.

References

1. Status and Opportunities of Zinc Ion Hybrid Capacitors: Focus on Carbon Materials, Current Collectors, and Separators. Nano-Micro Letters (2023).
2. Template‐oriented synthesis of boron/nitrogen‐rich carbon nanoflake superstructure for high‐performance Zn‐ion hybrid capacitors. Carbon Energy (2025).
3. Recent progress in flexible Zn‐ion hybrid supercapacitors: Fundamentals, fabrication designs, and applications. Carbon Energy (2022).