Rechargeable aqueous zinc-ion batteries (ZIBs) have been considered as a promising candidate for the large-scale energy storage device owing to their low cost and high safety. However, the practical application of aqueous ZIBs at low temperature environment is hindered by the freezing aqueous electrolytes, which leads to a sharp drop in ionic conductivity, and thereby a rapid deterioration of battery performance. Herein, a chaotropic salt electrolyte based on low concentration aqueous Zn(ClO 4 ) 2 with superior ionic conductivity under low temperature (4.23 mS/cm at −50°C) is reported. The anti-freezing methodology introduced here is completely different from conventional freeze-resistant design of using “water-in-salt” electrolyte, cosolvents, or anti-freezing agent additives strategy. Experimental analysis and molecular dynamics simulations reveal that the as-prepared Zn(ClO 4 ) 2 electrolyte possesses faster ionic migration compared with other commonly used Zn-based salts (i.e., Zn(CF 3 SO 3 ) 2 and ZnSO 4 ) electrolyte. It is found that Zn(ClO 4 ) 2 electrolyte can suppress the ice crystal construction by forming more hydrogen bonds between solute ClO 4 − and solvent H 2 O molecules, thus leading to a superior anti-freezing property. The fabricated ZIBs using this aqueous electrolyte exhibits a dramatically enhanced specific capacity, remarkable rate capability, and great cycling stability over a wide temperature range, from −50 to 25°C. The aqueous ZIBs also exhibit an outstanding energy density of 238.4 Wh/kg without compromising the power density (7.9 kW/kg) under −20°C. Moreover, the assembled aqueous ZIBs can also cycle stably over 1000 cycles at an ultra-low −50°C. The high-safety and cost-effective chaotropic salt electrolyte presented here is a promising strategy for low temperature energy storage application.
Although wearable sensors based on polymer hydrogels have great progress, achieving biocompatibility, long-term stability, and being used in harsh environments for polymer hydrogels remains a significant challenge. In this work, a new simple tactic is proposed to prepare biocompatible zwitterionic polymer hydrogels (PDM) by copolymerization of dopamine acrylamide (DAA) and 2-methacryloyloxyethyl phosphorylcholine (MPC). The synergistic effects of the Hofmeister and electrostatic interaction effect based on a series of inorganic salts on PDM hydrogels are studied. The PD3M7/4 M Zn(ClO 4 ) 2 hydrogel presents a high ionic conductivity of 13.58 S m −1 at 25 °C. The re-prepared hydrogel demonstrates outstanding anti-freezing properties, even at −45 °C, the hydrogel exhibits transparency and flexibility, and the ionic conductivity is up to 1.81 S m −1 . Moreover, the hydrogel has excellent adhesive strength (34.7 kPa), and anti-dehydration (94.4 % after 30 days). The freeze-dried PD3M7/4 M Zn(ClO 4 ) 2 gel can recover up to 89.5 % of the original water content after 96 h at 20 % RH and 25 °C. Importantly, the wearable strain sensor based on PD3M7/4 M Zn(ClO 4 ) 2 hydrogel shows high sensitivity (7.43 kPa −1 at 25 °C and 4.83 kPa −1 at −45 °C), ultra-low detection limit (30 Pa), outstanding cycle stability (10000 cycles), and quickly responds to human movement detection at 25 °C and −45 °C. This work provides an effective strategy to prepare the hydrogel which will be more appropriate to apply in wearable sensors and biological tissue engineering.
危险品化学品经营许可证（带存储）