Flexible energy storage devices are at the forefront of next‐generation power supplies, one of the most important components of which is the gel electrolyte. However, shortcomings exist, more or less, for all the currently developed hydrogel electrolytes. Herein, a facile and cost‐effective method is developed to construct an all‐round hydrogel electrolyte by using cotton as the raw material, tetraethyl orthosilicate as the crosslinker, and glycerol as the antifreezing agent. The obtained hydrogel electrolyte has high ionic conductivity, excellent mechanical properties (e.g., high tensile strength and elasticity), ultralow freezing point, good self‐healing ability, high adhesion, and good heat‐resistance ability. Remarkably, this hydrogel electrolyte can provide a record‐breaking high ionic conductivity of 19.4 mS cm−1 at −40 °C compared with previously reported aqueous electrolytes for zinc‐ion batteries. In addition, this hydrogel electrolyte can significantly inhibit zinc dendritic growth and parasitic side reactions from −40 to 60 °C. With this hydrogel electrolyte, a flexible quasi‐solid‐state Zn–MnO2 battery is assembled, which shows remarkable energy densities from −40 to 60 °C. The battery also exhibits outstanding cycling durability and has high endurance under various harsh conditions. This work opens new opportunities for the development of hydrogel electrolytes.

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An anti-freezing gel electrolyte with an ultralow freezing point below −60 °C is developed for assembling high-performance flexible aqueous Zn–MnO2 batteries.

The quasi-solid-state zinc-ion hybrid supercapacitor based on borax-crosslinked polyvinyl alcohol/nanocellulose hydrogel electrolyte displays not only great electrochemical performances but also high flexibility and self-healing ability.

The addition of small concentrations (2 wt % or less) of ultrahigh molecular weight isotactic polypropylene (M L ~ 3500 kg/mol) to a matrix of lower molecular weight chains (M S ~ 186 kg/mol, e.g. M L /M S ~ 20) substantially decreases the critical stress for inducing a highly oriented skin under flow-induced crystallization conditions-significantly more than for blends of M L /M S ~ 5 (Seki et al.)-and promotes the formation of point precursors and oriented "sausage-like" structures not observed for M L /M S ~ 5. These differences correlate with the onset of long chain stretching during shear: the ratio of long chains' Rouse time to short chains' disengagement time indicates that 3500 kg/mol chains can easily stretch if tethered onto a point nuclei and even when untethered. Adding 3500 kg/mol chains has strong effects that saturate beyond the overlap concentration, suggesting that an uninterrupted supply of long chains greatly accelerates formation of threads. A conceptual model is proposed that distinguishes between a critical stress for shish initiation and that for propagation.