Atomic Layer Deposition of Nanoscale MoO_3–x@ZnO Heterostructures for Kinetically Regulating Lithium Storage Behaviors

Metal oxides are considered among the most promising anode materials for next-generation lithium-ion batteries (LIBs) owing to their high theoretical capacities. Nevertheless, their practical application is hindered by intrinsic drawbacks, such as limited active sites, low electrical conductivity, and drastic volume variation during cycling. Rational construction of heterostructures offers a powerful strategy to overcome these limitations, but precise control at the nanoscale and a fundamental understanding of how heterostructures influence lithium storage behavior remain elusive. Herein, we report the atomic layer deposition (ALD)-enabled synthesis of two distinct MoO_3-x@ZnO heterostructures with controllable oxygen vacancies and tunable ZnO crystallinity. The underlying mechanism between the lithium storage behavior and the varied structures has been well revealed. A transition from amorphous ZnO (MoO_3-x@a-ZnO) to crystalline ZnO with a preferred (100) orientation (MoO_3-x@c-ZnO) leads to a shift in the dominant lithium storage mechanism─from pseudocapacitive behavior to diffusion-controlled processes. As a result, MoO_3-x@a-ZnO delivers a high specific capacity of 1016 mA h/g but suffers from rapid capacity fading, whereas MoO_3-x@c-ZnO exhibits delayed activation and gradually reaches 1035 mA h/g after prolonged cycling. This study provides critical insights into the structure–property relationships of oxide-based heterostructures and offers valuable guidance for the rational design of advanced metal oxide anodes for LIBs.