Multifunctional zinc-ion capacitors for energy storage

Zinc-ion capacitors are promising energy storage systems due to their high theoretical capacity, environmental friendliness, and cost effectiveness. Recently, to broaden application scenarios, multifunctional zinc-ion capacitors have been designed and attracted increasing interest. Therefore, development of advanced electrodes, electrolytes, and integrated devices have been witnessed to improve electrochemical performance and meet the practical requirements. In this Review, recent advancements in multifunctional zinc-ion capacitors is presented. First, the device types and working principles are introduced, followed by a systematic illustration of the latest achievements in multifunctional zinc-ion capacitors, including deformable, micro, self-chargeable, and electrochromic zinc-ion capacitors, as well as zinc-ion capacitor-sensor integrated systems. Finally, the current challenges, future development directions, and prospects of multifunctional zinc-ion capacitors are proposed. This review aims at stimulating the development of more types of multifunctional zinc-ion capacitors and provide deeper insights into future directions for constructing high-performance zinc-ion capacitors. Zinc-ion capacitors offer high capacity, eco-friendliness, and low cost, and recent designs with improved electrodes, electrolytes, and devices enhance their performance. Here, the authors outline recent progress in multifunctional zinc-ion capacitors, summarize key device types and advances, and highlight current challenges and future development directions.