Multifunctional gel electrolytes for high-performance zinc metal batteries

Zinc metal batteries (ZMBs) are considered to be promising energy storage devices in the field of large-scale energy storage due to the advantages of high energy density, good safety and environmental friendliness. However, the commercialization of ZMBs has been hampered because of the problems caused by aqueous electrolytes, such as hydrogen evolution reaction, electrolyte leakage, and water evaporation. Gel polymer electrolytes (GPEs) have attracted extensive attention due to the features of high security and low water content. However, the disadvantages of poor ion transport rate, easily freezing at low temperature and low mechanical strength are not conducive to the rapid development and practical application of ZMBs. The rational design and fabrication of multifunctional polymer-based frameworks are considered to be effective strategy to obtain high-performance GPEs. In this review, the recent advancements of GPEs with various polymers are generalized. The strategies for the improvement of ionic conductivity, low temperature resistance and mechanical strength of these GPEs, such as adding inorganic fillers, building double cross-linked networks and introducing functional groups, are summarized. The effects of the GPEs on the self-healable ability, inhibiting dendrite growth, and cycling stability of the ZMBs are also discussed. Finally, the key problems and development prospects of GPEs are proposed, which will provide possibility for the further development of GPEs.