Naphthalenediimide-Based\nMetal Organic Framework Materials\nfor Photoassisted Lithium-Ion Batteries

Abstract

Photoassisted lithium-ion batteries provide an effective\nsolution\nto improve the capacity and round-trip efficiency of batteries by\nutilizing solar energy. However, there is still a big challenge to\ndevelop key photoelectrochemical energy storage materials for simultaneous\nlight harvesting and energy storage. Here, we presented a redox-active\nmetal–organic framework (MOF) material with Ni²⁺ and naphthalenediimide salicylic acid ligand (NDISA) as photoactive\nelectrodes. The designed Ni-NDISA material exhibited reversible electrochemical\nredox activity on the naphthalenediimide unit and showed efficient\nphotoinduced metal–ligand charge transfer to realize solar-to-electrochemical\nenergy conversion and storage. With the Ni-NDISA as a bifunctional\ncathode, a photoassisted lithium-ion battery delivered an extra 13.1%\nof round-trip efficiency and improved specific capacity (82.0 mA h\ng^–1 under dark to 200.0 mA h g^–1 under 1 sun illumination). This work presents an optional way to\ndesign photoelectrochemical energy storage materials and opens up\nopportunities for solar to electrochemical energy storage devices.