Flexible Zinc–Air Battery with High Energy Efficiency and Freezing Tolerance Enabled by DMSO‐Based Organohydrogel Electrolyte

Abstract

With the emergence of various flexible electronics, the flexible zinc–air battery (ZAB) is considered a promising energy source with low cost, high energy density, and safety. However, gel electrolytes that improve the freezing tolerance and energy efficiency of ZABs are rarely explored. Herein, an organohydrogel electrolyte (OHE) is fabricated by soaking poly(2‐acrylamido‐2‐methylpropanesulfonic acid)/polyacrylamide (PAMPS/PAAm) double‐network hydrogel in aqueous KOH electrolyte with dimethyl sulfoxide (DMSO) additive. The prepared OHE exhibits high mechanical strength and excellent ionic conductivity. In addition, the introduction of DMSO effectively improves freezing tolerance and electrochemical performance especially in energy efficiency of ZABs due to that DMSO can break the hydrogen bonds between water molecules and alter the path of the conventional oxygen evolution reaction in ZAB simultaneously. Compared with the control hydrogel electrolyte, the optimized OHE enables flexible ZABs to not only exhibit an exceptionally low charge voltage of 1.63 V, high energy efficiency of 74.2%, and long cycling life of 177 cycles, but also to operate with an excellent specific capacity of 562 mAh g−1 and energy density of 523.4 Wh kg−1 at −40 °C. Moreover, the obtained flexible ZABs keep a stable output under deformations and extreme low temperature, manifesting a great potential for functional wearable devices.

Regulation of Released Alkali from Gel Polymer Electrolyte in Quasi‐Solid State Zn–Air Battery

“…NMR spectrum shows no peak of D 2 O, validating that the concentration gradient cannot cause diffusion of D 2 O back to the GPE (Figure S12, Supporting Information).Furthermore, the hydrophilic inner HPβCD can bond strongly with the H 2 O molecules to move the to the right-hand side, mitigating the loss of soluble Zn(OH)4 …”

“…During the charging process, the shape change of Zn anode occurs caused by inhomogeneous and insufficient deposition of reduced Zn because of the loss of Zn(OH) 4 2− . [22] Meanwhile, the preferential deposition of the unreduced Zn(OH) 4 2− at the raised points of Zn surface facilitates the dendrites growth. [23] Noteworthily, the adverse impact…”

“…More importantly, the strong hydrophilicity can reduce the water activity and move the reaction of Zn(OH) ZnO H O 2OH 2− and facilitating the homogeneous deposition of ZnO inside microspheres. [26][27][28] Therefore, sufficient Zn(OH) 4 2− and ZnO result in a uniform deposition of Zn and suppression of the Zn dendrites growth during charging process. Eventually, the regulation of the released alkali and suppression of Zn dendrites growth enable assembled QSZAB a long cyclic life.…”

Low-temperature resistant gel polymer electrolytes for zinc–air batteries

“…7d). Li et al 86 also added DMSO to construct DN poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS)/PAM, which exhibited high mechanical strength and good ionic conductivity. Moreover, the introduction of DMSO could change the path of the OER in ZABs and reduce the charge voltage to improve the energy efficiency.…”

Assessment of the Feasibility of Zn–Air Batteries with Alkaline Electrolytes Working at Sub-Zero Temperatures

“…Jiang et al reported an organohydrogel electrolyte with excellent mechanical flexibility and high ionic conductivity, which was composed of a dimethyl sulfoxide-added double-network hydrogel soaked with an aqueous KOH electrolyte. A Zn–air battery with this electrolyte exhibited a superior energy density of 523.4 W h kg –1 and a discharge capacity of 562 mA h g –1 at −40 °C . Although the reported hydrogel electrolyte-based Zn–air batteries with organic additives can operate at low temperatures, the water retention, low conductivity, high cost, and other safety risks of the gel electrolyte, such as the flammability and high toxicity of organic additives, remain to be addressed. , Consequently, alkaline aqueous-based electrolytes are still dominating the research at this stage, especially at high concentrations, as the high concentrations of ions reduce the proportion and inhibit the formation of hydrogen bonds .…”