Enhancing the performance and safety of quasi-solid-state zinc ion batteries through advanced electrolyte and material design

Zinc-ion batteries (ZIBs) have emerged as the most competitive alternative to lithium-ion batteries, owing to their high safety profile, superior theoretical specific capacity, low electrochemical potential, and cost-effectiveness. However, ZIBs employing zinc metal as the anode tend to develop dendritic zinc structures during cycling, which, if allowed to overgrow, may puncture the separator and lead to short-circuiting. Quasi-solid-state electrolytes (QSSEs) demonstrate the capacity to efficaciously impede the proliferation of zinc dendrites; nevertheless, the intrinsic diminution in ionic conductivity inherent to QSSEs severely impedes the advancement of quasi-solid-state ZIBs (QSSZIBs). Herein, a sulfonated MOF-modified QSSE was prepared via a freeze-thaw method, thereby imparting its surface with finely distributed, uniform pores. This refinement results in more gradual and orderly dendritic growth, consequently significantly augmenting its long-term cycling performance. The sulfonated MOF not only provides a pathway for zinc ion transport but also improves ionic conductivity and cationic migration (with nearly a fivefold increase in ionic conductivity compared to non-sulfonated MOF-modified QSSEs). Subsequently, an anode material composed of polyaniline/carbon cloth was prepared through an in situ polymerization process, and these components were assembled to create practical ZIBs alongside the QSSE. Under a discharge rate of 5 A g-1, the initial specific capacity reached 98.1 mA h g-1, and after 5000 cycles, the capacity retention remained impressively high at 88.4%. This endeavor has, to a certain extent, addressed the prevalent issue of elevated resistance in QSSZIBs and the associated reduced specific capacity under high current density conditions, fostering the further progression of QSSZIB technology.