Advanced carbon-based materials for Na, K, and Zn ion hybrid capacitors

Developing electrochemical energy storage devices with high energy and power densities, long cycling life, as well as low cost is of great significance. Hybrid metal-ion capacitors (MICs), commonly consisting of high energy battery-type anodes and high power capacitor-type cathodes, have become a trade-off between batteries and supercapacitors. Tremendous efforts have been devoted to searching for high-performance electrode materials due to poor rate capability of anodes, low capacity of cathodes, and interior sluggish kinetic match. Carbon materials with large surface area, good electrical conductivity and stability have been considered to be ideal candidates for electrodes of MICs. In this review, the advanced carbon materials directly as cathodes and anodes of MICs are systematically summarized. Then, the key structural/chemical factors including the structure engineering, porous characteristics, and heteroatom incorporation for improving electrochemical performance of carbon materials are highlighted. Additionally, the challenges and opportunities for future research on carbon materials in MICs are also proposed.