Probing Electrode–Electrolyte Synergy and Bottleneck Breakthrough of Zinc-Ion Capacitors from Two Key Configurations

In response to the demanding requirements of next-generation energy storage systems for high-energy density, high-power density, and ultra-long-cycle life, the academic community has continued to focus on coupled devices that combine battery-level energy and capacitor-level power characteristics. Zinc-ion capacitors (ZICs) have become the most promising strategic candidate system for energy storage technology due to their high-energy/power characteristics, excellent intrinsic safety, and significant cost advantages. In this review, the latest research progress of ZICs is reviewed from the perspective of system. Firstly, ZICs are divided into zinc metal anode//capacitive cathode ZICs (ZC-ZICs) and capacitive anode//battery-type cathode ZICs (CB-ZICs) according to the device configuration, and the energy storage mechanisms are analyzed in depth. At the same time, focusing on the two configurations of ZC-ZICs and CB-ZICs and their electrolyte systems, problem-oriented the key puzzles and corresponding solutions are sorted out one by one. Finally, based on the above discussion, this review proposes forward-looking suggestions for material modifications of ZICs, including pulse voltage activation, application of high-entropy materials, and the development of stable and multi-functional electrolytes, aiming to provide scientific guidance for the practical application of high-performance ZICs and promote the in-depth development of high-performance ZICs research.