Effects of Anions and Protein Structures on Protein‐Based Solid Electrolytes

Abstract Low ionic conductivity is one of the main hurdles for the practical application of advanced all‐solid‐state lithium‐ion batteries. Protein‐based solid electrolytes are recently proposed and can potentially provide both high ionic conductivity and high mechanical properties due to the decoupled ion transport mechanism. In this work, the effects of lithium salts and protein structures on the performance of protein‐based electrolytes through both ab initio density functional theory calculations and experiments are systematically investigated. The results show that the anions can be strongly locked by the charged amino acids, thus providing intermediate hopping sites for lithium‐ion, reducing energy barrier for lithium‐ion transport, and then enhancing the ionic conductivity. These calculations also demonstrate that need to be locked at appropriate positions by properly controlling the protein structures in order to provide bridging effects and facilitate lithium‐ion transport. The findings are consistent with the experimental observations and can provide guidance for design and optimization of protein‐based solid electrolytes.