Polysaccharide-driven hydrogen bond engineering enabling cryoprotective aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) suffer from poor electrolyte/anode interfacial stability and severe performance degradation under low-temperature conditions. To address these issues, this study proposes natural okra polysaccharides (OPs) as an electrolyte additive for interfacial engineering. OPs, rich in polar functional groups, preferentially adsorb onto the Zn/electrolyte interface via strong dipole interactions, forming a robust protective layer. This layer promotes uniform Zn deposition, suppresses side reactions and corrosion, and enhances the hydrogen-bond network of the electrolyte, thereby reducing interfacial water activity and lowering the freezing point. As a result, the low-temperature stability and electrochemical reversibility of AZIBs are significantly improved. Zn||Zn symmetric cells incorporating OPs exhibit exceptional cycling stability, maintaining reversible zinc plating/stripping for over 5000 h at 2 mA cm−2 and 1 mAh cm−2 and sustaining stable operation at −10 °C for 1600 h under 1 mA cm−2 and 0.5 mAh cm−2, as well as for 300 h under 10 mA cm−2 and 10 mAh cm−2. Furthermore, full cells employing V2O5 cathodes retain 83 % of their capacity after 1000 cycles, confirming the practical applicability of OPs as a functional electrolyte additive. This work demonstrates the significant potential of OPs to overcome key limitations of AZIBs, particularly for low-temperature operation, offering a sustainable and cost-effective strategy for next-generation energy storage.