Rechargeable aqueous batteries are an up-and-coming system for potential large-scale energy storage due to their high safety and low cost. However, the freeze of aqueous electrolyte limits the low-temperature operation of such batteries. Here, we report the breakage of original hydrogen-bond network in ZnCl₂ solution by modulating electrolyte structure, and thus suppressing the freeze of water and depressing the solid-liquid transition temperature of the aqueous electrolyte from 0 to –114 °C. This ZnCl₂-based low-temperature electrolyte renders polyaniline||Zn batteries available to operate in an ultra-wide temperature range from –90 to +60 °C, which covers the earth surface temperature in record. Such polyaniline||Zn batteries are robust at –70 °C (84.9 mA h g⁻¹) and stable during over 2000 cycles with ~100% capacity retention. This work significantly provides an effective strategy to propel low-temperature aqueous batteries via tuning the electrolyte structure and widens the application range of temperature adaptation of aqueous batteries.

Covalent organic frameworks with designable periodic skeletons and ordered nanopores have attracted increasing attention as promising cathode materials for rechargeable batteries. However, the reported cathodes are plagued by limited capacity and unsatisfying rate performance. Here we report a honeycomb-like nitrogen-rich covalent organic framework with multiple carbonyls. The sodium storage ability of pyrazines and carbonyls and the up-to twelve sodium-ion redox chemistry mechanism for each repetitive unit have been demonstrated by in/ex-situ Fourier transform infrared spectra and density functional theory calculations. The insoluble electrode exhibits a remarkably high specific capacity of 452.0 mAh g⁻¹, excellent cycling stability (~96% capacity retention after 1000 cycles) and high rate performance (134.3 mAh g⁻¹ at 10.0 A g⁻¹). Furthermore, a pouch-type battery is assembled, displaying the gravimetric and volumetric energy density of 101.1 Wh kg⁻¹_cell and 78.5 Wh L⁻¹_cell, respectively, indicating potentially practical applications of conjugated polymers in rechargeable batteries.

High-performance sodium storage at low temperature is urgent with the increasingly stringent demand for energy storage systems. However, the aggravated capacity loss is induced by the sluggish interfacial kinetics, which originates from the interfacial Na ⁺ desolvation. Herein, all-fluorinated anions with ultrahigh electron donicity, trifluoroacetate (TFA ⁻ ), are introduced into the diglyme (G2)-based electrolyte for the anion-reinforced solvates in a wide temperature range. The unique solvation structure with TFA ⁻ anions and decreased G2 molecules occupying the inner sheath accelerates desolvation of Na ⁺ to exhibit decreased desolvation energy from 4.16 to 3.49 kJ mol ⁻¹ and 24.74 to 16.55 kJ mol ⁻¹ beyond and below −20 °C, respectively, compared with that in 1.0 M NaPF ₆ -G2. These enable the cell of Na||Na ₃ V ₂ (PO ₄ ) ₃ to deliver 60.2% of its room-temperature capacity and high capacity retention of 99.2% after 100 cycles at −40 °C. This work highlights regulation of solvation chemistry for highly stable sodium-ion batteries at low temperature.