Highly reversible and stable Zn metal anode under wide temperature conditions enabled by modulating electrolyte chemistry

Aqueous Zn metal batteries (ZMBs) are promising for next-generation energy storage. However, the grievous Zn dendrite growth at low temperatures and severe parasitic reactions of Zn metal anode at high temperatures greatly restrict the development of wide-temperature aqueous ZMBs. Herein, the above problems faced by Zn metal anode are solved by introducing a multi-hydroxyl polymer (polyethylene glycol, PEG) cosolvent, and thus high cyclic stability of aqueous ZMBs under wide temperatures (-20 to 80 °C) is achieved. At subzero temperatures, PEG adsorbed on the Zn surface induces uniform deposition of Zn2+, which inhibits dendrite growth. Meanwhile, the interaction between PEG and water molecules diminishes the activity of free water by perturbing hydrogen bonds, which suppresses the parasitic reactions of Zn anode at elevated temperatures. As a result, Zn||Zn symmetric cells achieve an ultralong-term cycling life of over 1000 h at 0.2 mA cm−2 at −20 °C or at 1 mA cm−2 at 20 °C, and exhibit an ultrahigh cumulative cycling capacity (CCC) of over 1500 mAh cm−2 at 60 °C, which is superior to the previously reported ZMBs. Moreover, the Zn||[email protected]2O5 full batteries also exhibit excellent electrochemical performance from −20 °C to 80 °C, suggesting great potential for practical applications.