Naphthalenediimide-Based Metal Organic Framework Materials for Photoassisted Lithium-Ion Batteries

Photoassisted lithium-ion batteries provide an effective solution to improve the capacity and round-trip efficiency of batteries by utilizing solar energy. However, there is still a big challenge to develop key photoelectrochemical energy storage materials for simultaneous light harvesting and energy storage. Here, we presented a redox-active metal–organic framework (MOF) material with Ni2+ and naphthalenediimide salicylic acid ligand (NDISA) as photoactive electrodes. The designed Ni-NDISA material exhibited reversible electrochemical redox activity on the naphthalenediimide unit and showed efficient photoinduced metal–ligand charge transfer to realize solar-to-electrochemical energy conversion and storage. With the Ni-NDISA as a bifunctional cathode, a photoassisted lithium-ion battery delivered an extra 13.1% of round-trip efficiency and improved specific capacity (82.0 mA h g–1 under dark to 200.0 mA h g–1 under 1 sun illumination). This work presents an optional way to design photoelectrochemical energy storage materials and opens up opportunities for solar to electrochemical energy storage devices.