Research Progress of Lignin Molecules in Electrochemical Energy Storage Devices

The development of advanced electrochemical energy storage devices is a key strategic measure to safeguard national energy security and achieve the goals of "carbon peaking and carbon neutrality". Electrochemical energy storage devices realize energy storage and release through the mutual conversion between chemical energy and electrical energy, with their core components including electrodes, electrolytes, and separators. As a by-product of the papermaking industry, lignin has become an ideal raw material for energy storage devices due to its unique aromatic skeleton, modifiable redox-active sites, and biomass sustainability. This paper first reviews the structural characteristics and electrochemical properties of lignin, as well as the intrinsic reasons for its application in various energy storage devices based on these properties. Subsequently, it summarizes the latest research progress of lignin molecules in energy storage devices such as supercapacitors, zinc-ion batteries, lithium-ion batteries, and flow batteries, covering the three key components of electrodes, separators, and electrolytes. Finally, the prominent advantages of lignin in the field of electrochemical energy storage devices are summarized, and the current technical challenges are pointed out, aiming to provide theoretical reference and practical guidance for subsequent related R&D work.