Dendrite-Free Lithium Anodes with a Metal Organic Framework-Derived Cake-like TiO₂ Coating on the Separator

Lithium metal, with a high theoretical capacity of 3860 mAh/g and a low electrochemical potential of −3.040 V, is an attractive anode material. However, its application has been hampered by irregular lithium dendrite growth and low coulombic efficiency. To solve these problems, a facile air calcination strategy was used to prepare cake-like TiO₂ nanoparticles with rich pores, which were further coated on one side of the commercial Celgard separator. The nanoscale mesoporous channels on the surface of TiO₂ particles can effectively block the growth of lithium dendrites, leading to dense and uniform Li deposition with a high coulombic efficiency. Compared with the blank cell (50 cycles of normal operation), the Li||Cu cell with modified separator can run 100 cycles at 2 mA/cm² with an average coulombic efficiency of 97.3 %. These results herald a new approach to dendrite-free lithium anodes by nanostructured ceramic coating on the separator.