Progress and challenges of zinc ion capacitors: From basic principles to performance optimization strategies
Xuexue Pan, Zhazira Supiyeva, Zhuanpei Wang, Qamar Abbas
Abstract
Faced with the growing demand for efficient and sustainable energy storage, zinc ion capacitors (ZICs) are gradually emerging due to their low cost, high safety, and environmental compatibility. This article provides a comprehensive overview of the theoretical framework, structural innovation, scientific challenges, and optimization strategies of ZICs. Firstly, the concept of ZICs is described, then their classification and charge storage mechanism are presented, delving into the principles and performance indicators of charge matching, such as energy and power density, and cycle-life. Further, characteristics of hybrid ZICs that integrate the advantages of batteries and capacitors are highlighted. The material section details the electrode category, including carbon-based, pseudocapacitor and battery-type materials, supplemented with consideration of separator, multi-electrolyte system (water-based, organic, gel, solid) and redox enhanced electrolytes. In the scientific challenge section, we discuss core issues such as low specific capacity, unclear energy storage mechanism, low mass load, mismatched carrier pore size, inhibition of zinc dendrite growth, electrolyte optimization, and research and development of positive electrode materials. This part is also supplemented with discussion on interface stability, structural and surface chemical modulation, cycle life decay mechanism, and safety considerations. Interface engineering and optimization strategies focus on enhancing the stability of electrode/electrolyte interfaces, suppressing zinc dendrite paths, improving the performance of positive electrode pseudocapacitors, and constructing SEI films. Structural design and performance improvement focus on nanostructures (one-dimensional, two-dimensional, and three-dimensional), optimizing porous materials, designing flexible micro ZICs, and innovating functionalized separators and current collectors. Finally, the future research directions have been summarized, with assertions that deepening research and innovation will promote ZICs to enter a new era of sustainable high energy density device applications.