The practical applications for aqueous Zn ion batteries (ZIBs) are promising yet still impeded by the severe side reactions on Zn metal. Here, a lysozyme protective layer (LPL) is prepared on Zn metal surface by a simple and facile self-adsorption strategy. The LPL exhibits extremely strong adhesion on Zn metal to provide stable interface during long-term cycling. In addition, the self-adsorption strategy triggered by the hydrophobicity-induced aggregation effect endows the protective layer with a gap-free and compacted morphology which can reject free water for effective side reaction inhibition performance. More importantly, the lysozyme conformation is transformed from α-helix to β-sheet structure before layer formation, thus abundant functional groups are exposed to interact with Zn2+ for electrical double layer (EDL) modification, desolvation energy decrease, and ion diffusion kinetics acceleration. Consequently, the LPL renders the symmetrical Zn battery with ultra-long cycling performance for more than 1200 h under high Zn depth of discharge (DOD) for 77.7%, and the Zn/Zn0.25V2O5 pouch cell with low N/P ratio of 2.1 at high Zn utilization of 48% for over 300 cycles. This study proposes a facile and low-cost method for constructing a stable protective layer of Zn metal for high Zn utilization aqueous devices.
Keywords: aqueous Zn batteries; conformational transition; high Zn utilization; lysozyme protective layer; side reaction inhibition.
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