Promising sustainable technology for energy storage devices: Natural protein-derived active materials

Electrochemical energy storage devices (EESDs) are critical technologies in modern economy, covering numerous fields such as portable electronics, electric vehicles, etc. The expanding market of EESDs demands for extra requirements such as safety, environmental friendliness and low cost, in addition to increasingly enhanced electrochemical properties. Natural proteins are abundant, versatile bio-macromolecules involving tremendous amount of amino acids/functional groups/heteroatoms, which greatly benefit sustainable technologies for advancing performances of EESDs. Recent years, significant research on utilizing natural proteins including plant/animal proteins to fabricate active materials for enhancing performance of EESDs has been well reported. Therefore, it is important to comprehensively summarize the progress and achievements, analyze the advan-tages/challenges, and predict the prospective for future protein-based strategies toward high-performance EESDs, which are the contents of this review. The protein-derived active materials include activated carbons, silicon, sulfur, metal alloys, transitional metal compounds, and nonprecious metal catalysts. The resulting EESDs are associated with Li-/Na-/K-ion batteries, metal-air batteries, and redox flow batteries, as well as super-capacitors. The contributions of proteins to stabilizing/protecting electrodes, and thus enhancing performance of EESDs are specifically emphasized. Furthermore, studies on genetical engineering of proteins for directing self-assembly of active material nanoparticles are introduced.