Environment-Friendly Li-Rich Molecular Sieve Composite Separator with Abundant Lewis Base Sites for Enhancing the Lithium-Ion Transport Property

Lithium dendrites and the volume expansion effect limit the practical application of lithium metal batteries (LMBs), and they have become urgent problems that need to be solved. Herein, we design a kind of lithiated molecular sieve (LMS) ceramic particles through the ionic replacement reaction as a functional separator coating for inhibiting lithium dendrites. This LMS@HT-PE composite separator is prepared via a water-based slurry and exhibits an improved ionic conductivity (0.569 mS cm–1) and a higher lithium-ion transference number (0.52). Furthermore, the Li//Li symmetrical cell with the LMS@HT-PE composite separator can retain a lower overpotential and stably operate for over 500 h. A dendrite-free lithium deposition morphology is realized on the surface of the lithium metal anode with a uniform Li-ion flux and excellent interface stability. Meanwhile, an enhanced coulombic efficiency (more than 80%) and reduced nucleation overpotential are achieved in Li//Cu half-cells. In addition, the LiCoO2/Li cell with the composite separator exhibits a stable cycle for more than 200 cycles and the average capacity decay rate is only 0.11% per cycle. During the rate performance test, the cell with the LMS@HT-PE composite separator still displays high discharge capacity even at 5C. Hence, this functional composite separator strategy is expected to boost the electrochemical performance of LMBs and be widely used in this field.