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Decoupling the ion motion and segmental relaxation is significant for developing advanced solid polymer electrolytes with high ionic conductivity and high mechanical properties. Our previous work proposed a decoupled ion transport in a novel protein-based solid electrolyte. Herein, we investigate the detailed ion interaction/transport mechanisms through first-principles density functional theory (DFT) calculations in a vacuum space. Specifically, we study the important roles of charged amino acids from proteins. Our results show that the charged amino acids (i.e., Arg and Lys) can strongly lock anions (ClO4−). When locked at a proper position (determined from the molecular structure of amino acids), the anions can provide additional hopping sites and facilitate Li+ transport. The findings are supported from our experiments of two protein solid electrolytes, in which the soy protein (with plenty of charged amino acids) electrolyte shows much higher ionic conductivity and lower activation energy in comparison to the zein (lack of charged amino acids) electrolyte.
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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.
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- Award ID(s):
- 1929236
- PAR ID:
- 10421278
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials Technologies
- Volume:
- 8
- Issue:
- 11
- ISSN:
- 2365-709X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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