Designing bionic ion pumps in the electrolyte for stable Zn metal anodes

Zn metal anodes with dendrite growth that driven by heterogeneous ion distribution, limit their application in high-energy-density batteries. Here, we pioneer liquid metal-organic framework (MOF) as a built-in bionic ion pump into the electrolyte, unlike conventional solid MOF, to stabilize Zn metal anodes. The inherent pores of liquid MOF of UiO-66 and the strong electrostatic interactions between the oxygen-containing atoms and Zn²⁺ can effectively promote the homogenization and pumping of Zn²⁺, thus achieving the uniform bulk ion distribution. Meanwhile, the exposed metal sites and the anchoring effect of -CH₂ on OTf⁻ further strengthen ion regulation effect. Consequently, Zn dendrites are effectively suppressed, and the V₂O₅||Zn pouch cell exhibits a capacity retention of 80.1 % and low gassing behavior after 600 cycles at 1 A g⁻¹ compared to the control group (56.6 %). Remarkably, the liquid UiO-66 also demonstrates universal applicability in Li and Na metal anodes, where the capacity retention of the LiFePO₄||Li cell improves from 57.8 % to 92.8 % after 150 cycles, and the Na₃V₂(PO₄)₃||Na cell shows an increase from 82.7 % to 94.1 % after 5600 cycles.