Anionic metal-organic framework modified separator boosting efficient Li-ion transport

Low lithium ion (Li + ) mobility and thermal stability of polyolefin separator are crucial obstacles that limit the utilization of Li metal electrodes in the age of rapid acceleration toward high-energy-density rechargeable batteries. Herein, we report anionic metal-organic frameworks (MOFs) modified separator to overcome the barriers. By grafting –SO 3 − group onto the Universitetet i Oslo (UIO) structure, the anionic MOFs nanoparticles are synthesized (noted as UIO-SOLi). The UIO-SOLi is adhered on the surface of Celgard 2400 via polyacrylic acid (PAA) to fabricate the modified separator (UIOSOL@PP). The MOFs coating optimizes the wettability and thermal stability of the pristine separator. Negatively charged moieties –SO 3 − within the pore surface electrostatically repel anions while facilitate the transport of Li + , thus achieving a high Li + transference number ( t Li + ) of 0.82. The effective Li + transport relieves the concentration polarization, regulates the Li + flow and realizes the uniform deposition of lithium. By implementing the UIOSOL@PP separator, the LiFePO 4 |Li cells deliver superior rate performance and cycling lifespan that renders a high discharge capacity retention of 155 mAh g −1 over 600 cycles at 1C. These results indicate that anionic MOFs modified separator is a promising strategy to modulate Li + flow and assist with efficient long-term operation of lithium metal batteries.