Photo-rechargeable batteries and supercapacitors: Critical roles of carbon-based functional materials

As a clean and renewable energy source, solar energy is a competitive alternative to replace conventional fossil fuels. Nevertheless, its serious fluctuating nature usually leads to a poor alignment with the actual energy demand. To solve this problem, the direct solar-to-electrochemical energy conversion and storage have been regarded as a feasible strategy. In this context, the development of high-performance integrated devices based on solar energy conversion parts (i.e., solar cells or photoelectrodes) and electrochemical energy storage units (i.e., rechargeable batteries or supercapacitors [SCs]) has become increasingly necessary and urgent, in which carbon and carbon-based functional materials play a fundamental role in determining their energy conversion/storage performances. Herein, we summarize the latest progress on these integrated devices for solar electricity energy conversion and storage, with special emphasis on the critical role of carbon-based functional materials. First, principles of integrated devices are introduced, especially roles of carbon-based materials in these hybrid energy devices. Then, two major types of important integrated devices, including photovoltaic and photoelectrochemical-rechargeable batteries or SCs, are discussed in detail. Finally, key challenges and opportunities in the future development are also discussed. By this review, we hope to pave an avenue toward the development of stable and efficient devices for solar energy conversion and storage.