Difunctional MOF for dendrite-free all-solid-state lithium metal batteries by synergistic effect of hydrogen bond and electrostatic interaction

The interphase formed between solid polymer electrolyte (SPE) and highly reductive lithium metal largely de-termines the overall performance of the battery. Although various types of nanoparticles have been continuously employed as fillers to achieve a stable interphase for long cycling performance, the irregular growth of lithium dendrites cannot be completely suppressed due to uneven lithium deposition. Herein, a new type of zwitter-ion modified metal-organic framework (NH3+center dot SO3-@ZIFs) is prepared as a modifier for PEO-LiTFSI. Due to the unique ionic structure of NH3+center dot SO3--@ZIFs, the formed electrostatic interaction could inhibit the movement of TFSI-, enhance the ion migration number. More importantly, TOF-SIMS effectively confirms the formation of Li+ -conductive LiF-rich SEI due to the catalytic effect of NH3+center dot SO3-@ZIFs, which could homogenize the lithium flux, inhibit the growth of Li dendrite. Results show that the PEO-NH3+center dot SO3- @ZIFs exhibits high ion migration number (tLi+ = 0.78). The Li/Li symmetric cells equipped NH3+center dot SO3-@ZIFs SPE can be stably operated for more than 4600 h at 60 C-? while the full cell with LiFePO4 cathode also enables long-term stability over 1200 cycles with capacity stabilizing at around 103 mAh g(-1), demonstrating the great potential of this kind of SPEs for preparing high-performance LMBs.