Near-Theoretical-Density Zinc Plating Enabled by an Ordered Janus Interphase for High-Energy Zinc Pouch Cells.

Achieving ultradense zinc plating at the theoretical limit is crucial for high-energy aqueous zinc metal batteries (AZMBs), but is hindered by severe interfacial instabilities such as dendrite growth and hydrogen evolution. Here we construct a nanometer-thin, vertically stratified organic-inorganic Janus bilayer (CF-LaF3) by ion layer epitaxy to pre-engineer the zinc anode interface. A hydrophobic perfluoroalkyl top layer accelerates Zn2+ desolvation, blocks active water and suppresses parasitic reactions, while a crystalline LaF3 bottom layer with high modulus, zincophilicity and continuous ionic channels homogenizes Zn2+ flux and helps mechanically suppress dendritic growth. This complementary interphase delivers dendrite-free zinc deposition at 5 mAh cm-2 with an ultradense thickness of 8.60 μm, approaching the theoretical limit (8.54 μm). Ah-level Zn||I2 pouch cells achieve 109 Wh L-1 energy density on a full-cell basis. This pre-engineered Janus interphase offers a general and scalable route to practical high-energy AZMBs.