Recent advancements and future challenges of perovskite-based supercapacitors

Abstract

Perovskite materials have attracted increasing interest as advanced electrode materials for the next generation of supercapacitors, providing an elegant solution to the limitations of traditional materials, including carbonaceous materials, transition metal oxides, and conducting polymers, often identified to have low energy density, lack of electrical conductivity, and inhibited cycling stability. The revolutionary potential of perovskite-based supercapacitors as a result of their unique ABX₃ crystal structure allows for considerable compositional flexibility and tunable electrochemical properties. Perovskites store energy by stable, synergistic mechanisms such as electric double-layer capacitance (EDLC) and pseudocapacitance, driven by oxygen vacancies, high ionic conductivity, and reversible redox reactions. Advances in synthesis modalities including sol–gel, hydrothermal, co-precipitation, and mechanochemical methods have already yielded substantial improvements to phase purity, porosity, and scalability, improving electrochemical performance to the extent that it can be used in practical applications. Perovskite integration and combination with renewable energy systems such as hybrid photovoltaic-supercapacitors illustrate the compatibility and potential of perovskites to stimulate the development of sustainable energy storage technologies. However, drawbacks such as the toxicity of halide perovskites and complexity of synthesis routes, as well as aqueous long-term stability continue to present challenges and further research is required to investigate lead-free alternatives, cheaper synthesis routes, and protective coatings. This review brings together advances over the last five years in oxide, halide, and fluoride perovskites, including overarching themes in defect engineering, carbon-based composites, and new lead-free alternatives. Further, it will summarize the performance characteristics, and then contrast these materials with established electrode families such as MXenes, MOFs and advanced carbons. A differentiating theme of this review is in its inclusion of a future-focused section that identifies unresolved issues associated with toxicity, cycling stability, and scalable synthesis and recommends potential solutions including protective coatings, green synthesis, and device encapsulation. To provide context for new material development and device integration, a conceptual roadmap is provided to indicate the movements needed to realize laboratory demonstrations of supercapacitor devices.