Small Grain ZnO/SnO₂Heterostructures with Built-In Electric Fields for Stable Lithium Metal Anodes

Through an integrated electric field at the SnO₂–ZnO (SZO) interfaces, we provide a 3D SZO heterostructured host that permits dendrite-free lithium metal anodes. This host efficiently redistributes Li⁺flux across a carbon paper framework by taking advantage of the work function mismatch between the two oxides. This allows lithium to deposit uniformly and without dendrites even at high current densities. Prolonged galvanostatic testing under extreme conditions, including 5 mA cm^–2, confirmed that the SZO host significantly enhances cycle stability when compared to single-oxide layers or bare carbon. According to thorough mechanism studies, space-charge zones created at the SZO heterojunctions control Li⁺nucleation and growth by (i) reducing the effective nucleation barrier, (ii) stabilizing the electric double-layer, and (iii) reducing local Li⁺depletion. Partial electron transfer from SnO₂to ZnO is confirmed by X-ray photoelectron spectroscopy, which increases the composite work function and increases its lithiophilicity. The flat, planar Li deposits seen in the ex situ examination can be explained by the combined action of internal electric fields and electron-deficient locations. The current study emphasizes heterostructure engineering as a reliable method for dendrite suppression, providing a viable approach to producing safe, high-performing lithium metal anodes that are appropriate for next-generation rechargeable batteries.