Unraveling Synergistic Dual-Element Doping Mechanisms in Solid-State Synthesis via Atomic Layer Deposition-Enabled...

Introducing dopants via high-temperature solid-state synthesis is a widely employed strategy to enhance the electronic and mechanical properties of inorganic materials. However, the intrinsic distribution and incorporation mechanisms of dopants are often obscured by localized side reactions arising from the inhomogeneous mixing inherent to conventional methods. Here, we present a model system based on sequentially coating the oxides of target dopant elements onto substrate surfaces using atomic layer deposition (ALD), enabling precise investigations of intrinsic doping behaviors and dopant-dopant interactions. This ALD-based methodology ensures uniform and controlled reactions between dopants and substrates, effectively eliminating undesired side products. By sequentially depositing Al₂O₃ and WO₃ onto a Ni_0.9Co_0.05Mn_0.05(OH)₂ precursor followed by calcination with LiOH·H₂O, we reveal a unique synergistic effect between Al and W: whereas W alone tends to segregate at the particle surface, the presence of Al facilitates its lattice incorporation. Notably, lattice-incorporated W significantly enhances rate capability and high-voltage cycling stability, attributed to robust W-O bonding within the host lattice. This ALD-based model system provides a versatile and broadly applicable platform for elucidating fundamental doping mechanisms in solid-state synthesis, offering critical insights into complex multidopant interactions.