Regulated Li Electrodeposition Behavior through Mesoporous Silica Thin Film in Anode-Free Lithium Metal Batteries

Lithium metal anode material suffers from the formation of a dendritic structure and manufacturing difficulties in Li metal batteries. Although anode-free lithium metal batteries (AFLMBs) have received broad interest due to their high energy density and easy fabrication, controlling the morphology of electrodeposited Li is challenging. In this work, we report on the use of mesoporous silica thin films (MSTFs) with perpendicular nanochannel (pore size ∼6 nm) stacking on a stainless steel (SS) substrate as the MSTF⊥SS for advancing AFLMBs. The MSTF⊥SS substrate with inorganic structures improves the stability of the Li plating/stripping process in Li-MSTF⊥SS cells at a current density of 2 mA cm–2 and capacity of 2 mAh cm–2. A LiFePO4 cathode (mass loading: ∼12 mg cm–2) paired with the MSTF⊥SS electrode delivered an initial discharge capacity of 154 mA h g–1, which is ∼20% higher than that of the bare SS electrode at a C rate of 0.1C. Grazing-incidence wide-angle X-ray scattering results suggest that MSTF regulates the Li electrodeposition process with individual microcrystals and leads to the formation of Li(110). Also, the electrodeposited Li film with a uniform surface is obtained on the MSTF⊥SS substrate. The designed porous MSTF with high stability, ultrasmall pore size, and lithiophilic properties enhances the performance of AFLMBs with the LiFePO4 cathode during 100 cycles.