Lattice pinning in MoO₃ via coherent interface with stabilized Li⁺ intercalation.

Abstract

Large lattice expansion/contraction with Li⁺ intercalation/deintercalation of electrode active materials results in severe structural degradation to electrodes and can negatively impact the cycle life of solid-state lithium-based batteries. In case of the layered orthorhombic MoO₃ (α-MoO₃), its large lattice variation along the b axis during Li⁺ insertion/extraction induces irreversible phase transition and structural degradation, leading to undesirable cycle life. Herein, we propose a lattice pinning strategy to construct a coherent interface between α-MoO₃ and η-Mo₄O₁₁ with epitaxial intergrowth structure. Owing to the minimal lattice change of η-Mo₄O₁₁ during Li⁺ insertion/extraction, η-Mo₄O₁₁ domains serve as pin centers that can effectively suppress the lattice expansion of α-MoO₃, evidenced by the noticeably decreased lattice expansion from about 16% to 2% along the b direction. The designed α-MoO₃/η-Mo₄O₁₁ intergrown heterostructure enables robust structural stability during cycling (about 81% capacity retention after 3000 cycles at a specific current of 2 A g^-1 and 298 ± 2 K) by harnessing the merits of epitaxial stabilization and the pinning effect. Finally, benefiting from the stable positive electrode-solid electrolyte interface, a highly durable and flexible all-solid-state thin-film lithium microbattery is further demonstrated. This work advances the fundamental understanding of the unstable structure evolution for α-MoO₃, and may offer a rational strategy to develop highly stable electrode materials for advanced batteries.