Suffering from critical instability of lithium (Li) anode, the most commercial electrolytes, carbonate-ester electrolytes, have been restrictedly used in high-energy Li metal batteries (LMBs) despite of their broad implementation in lithium-ion batteries. Here, abundant, natural corn protein, zein, is exploited as a novel additive to stabilize Li anode and effectively prolong the cycling life of LMBs based on carbonate-ester electrolyte. It is
discovered that the denatured zein is involved in the formation of solid electrolyte interphase (SEI), guides Li+ deposition and repairs the cracked SEI. In specific, the zein-rich SEI benefits the anion immobilization, enabling uniform Li+ deposition to diminish dendrite growth; the preferential zein-Li reaction effectively repairs the cracked SEI, protecting Li from parasite reactions. The resulting symmetrical Li cell exhibits a prolonged cycling life to over 350 h from <200 h for pristine cell at 1 mA cm 2 with a capacity of 1 mAh cm^ 2. Paired with LiFePO4 cathode, zein additive markedly improves the electrochemical performance including a higher capacity of 130.1 mAh g^ 1 and a higher capacity retention of ~ 80 % after 200 cycles at 1 C. This study demonstrates a natural
protein to be an effective additive for the most commercial electrolytes for advancing performance of LMBs.
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Protein-modified SEI formation and evolution in Li metal batteries
Despite numerous reported lithium metal batteries (LMBs) with excellent cycling performance achieved in labs, transferring the high performing LMBs from lab-scale to industrial-production remains challenging. Therefore, via imitating the stand-still process in battery production, a conventional but important procedure, to investigate the formation and evolution of a solid electrolyte interface (SEI) is particularly important for LMBs. Our previous studies indicate that zein (corn protein)-modified carbonate-ester electrolyte (the most commercialized) effectively improves the performance of LMBs through guiding Li- ions and repairing cracked SEI. Herein, we investigate the formation and evolution of the protein-modified SEIs on Li anodes by imitating the stand-still temperature and duration. A simulation study on the protein denaturation in the electrolyte under different temperatures demonstrates a highly unfolded configuration at elevated temperatures. The experiments show that this heat-treated-zein (H-zein) modified SEI forms quickly and becomes stable after a stand-still process of less than 100 min. Moreover, the H-zein SEI exhibits excellent wetting behavior with the electrolyte due to the highly unfolded protein structures with more functional groups exposed. The Li|Li cell with the H-zein SEI achieves prolonged cycling performance (>360 h vs. 260 h of the cell with the untreated-zein (U-zein) modified SEI). The LiFePO4|Li cell with the H-zein SEI shows much stable long-term cycling performance of capacity retention (70% vs. 42% of the cell with U-zein SEI) after 200 cycles. This study confirms that the appropriately treated protein is able to effectively improve the performance of LMBs, and will inspire future studies for the production process of LMBs toward their commercialization.
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- Award ID(s):
- 1929236
- NSF-PAR ID:
- 10349902
- Date Published:
- Journal Name:
- Journal of Energy Chemistry
- Volume:
- 73
- ISSN:
- 2095-4956
- Page Range / eLocation ID:
- 248–258
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1016/j.jechem.2022.06.017
