An asymmetric supercapacitor is a device in which the two electrodes store charge by different mechanisms, one capacitive and one faradaic, so that their potential windows add rather than overlap. Pairing them widens the cell voltage beyond the stability limit that a symmetrical device would be restricted to, and hence raises the energy density, which scales with the square of that voltage [1]. Metal-organic frameworks and their calcination products have been examined as faradaic partners, and a device built from an unmodified cobalt zeolitic imidazolate framework delivers both high energy and power [2]. Prototype cells assembled from a nickel-cobalt oxide and a carbon negative electrode show how far the laboratory figures can be pushed [3]. Pairing an iron oxide negative electrode with an iron phosphide positive one is another route to the same voltage gain [4], and combining a perovskite-type molybdate with reduced graphene oxide extends the range of chemistries examined [5]. Cycle life at the widest voltage remains the quantity that limits what the wider window is worth.
- hybrid capacitor
- potential window
- energy density
- faradaic electrode
- carbon negative electrode
- power density
- charge balance
Supercapacitor Materials and Fabrication·Electronic, Optical and Magnetic Materials·Materials Science·Physical Sciences
References
- Qian, Y.; Zhang, J.; Jin, J.; Yang, S.; Li, G. Flexible Solid-State Asymmetric Supercapacitor with High Energy Density and Ultralong Lifetime Based on Hierarchical 3D Electrode Design. ACS Applied Energy Materials 2022, 5, 5830-5840. [CrossRef]
- Kaushik, S.; Chand, P.; Sharma, S. High-performance pristine ZIF-67 asymmetric supercapacitor device with excellent energy and power density for energy storage application. Electrochimica Acta 2024, 497, 144565. [CrossRef]
- Shwetha, K.; Manjunatha, C.; Sudha Kamath, M.; Rastogi, C.K.; Chaudhary, V.; Maurya, G.; Athreya, Y.; Shivaraj, B.; Khosla, A. Fabrication of super-high energy density asymmetric supercapacitor prototype device employing NiCo2S4@f-MWCNT nanocomposite. Journal of Energy Storage 2023, 72, 108657. [CrossRef]
- Qi, S.; Zhang, C.; Sun, M.; Wu, X. Design of high energy density asymmetric supercapacitor using Fe₃O₄/graphene and FeP₄/graphene electrodes. Diamond and Related Materials 2025, 154, 112258. [CrossRef]
- Kumar, A.; Kumar, K.Y.; Hamzad, S.; Prasanna, B.; Raghu, M. Fabrication of La-CoMoO4@RGO composite for asymmetric supercapacitor device applications. Next Energy 2026, 13, 100788. [CrossRef]