An Amino Acid-Enabled Separator for Effective Stabilization of Li Anodes.

Fundamentally suppressing Li dendrite growth is known to be critical for realizing the potential high energy density for Li-metal batteries (LMBs). Inspired by the ionic transport function of proteins, we previously discovered that utilizing natural proteins was able to stabilize the Li anode but have not demonstrated how a specific amino acid of the protein enabled the function. In this study, we decorate the separator with Leucine ( Leu ) amino acid assisted by poly(acrylic acid) (PAA) for effectively stabilizing the Li-metal anode, so as to dramatically improve the cycling performance of LMBs. The decorated separator improves electrolyte wettability and effectively suppresses Li dendrite growth. As a result, the amino acid-enabled separator prolongs the cycle life of the symmetrical Li|Li cells, exhibits higher Coulombic efficiency in the Li|Cu cells, and improves the cycling performance in LMBs with the LiFePO 4 cathode. This work is an initial study on applying a specific amino acid of proteins to enhance the performance of batteries, providing a new strategy on guiding Li + deposition, and laying an important foundation for functional separator design of high-energy-density batteries.