Lignin-based materials for electrochemical energy storage devices

Lignin is the most abundant aromatic polymer in nature, which is rich in a large number of benzene ring structures and active functional groups. The molecular structure of lignin has unique designability and controllability, and is a class of functional materials with great application prospects in energy storage and conversion. Here, this review firstly focuses on the concept, classification, and physicochemical property of lignin. Then, the application research of lignin in the field of electrochemical storage materials and devices are summarized, such as lignin-carbon materials and lignin-carbon composites in supercapacitors and secondary batteries. Finally, this review points out the bottlenecks that need to be solved urgently and the prospects for future research priorities.