Research progress on carbon-based zinc-ion capacitors

Zinc-ion capacitors (ZICs), which consist of a capacitor-type electrode and a battery-type electrode, not only possess the high power density of supercapacitors and the high energy density of batteries, but also have other advantages such as abundant resources, high safety and environmental friendliness. However, they still face problems such as insufficient specific capacitance, a short cycling life, and narrow operating voltage and temperature ranges, which are hindering their practical use. We provide a comprehensive overview of the fundamental theory of carbon- based ZICs and summarize recent research progress from three perspectives: the carbon cathode, electrolyte and zinc anode. The influence of the structure and surface chemical properties of the carbon materials on the capacitive performance of ZICs is considered together with theoretical guidance for advancing their development and practical use.