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 MoO 3 (α-MoO 3 ), 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-MoO 3 and η-Mo 4 O 11 with epitaxial intergrowth structure. Owing to the minimal lattice change of η-Mo 4 O 11 during Li + insertion/extraction, η-Mo 4 O 11 domains serve as pin centers that can effectively suppress the lattice expansion of α-MoO 3 , evidenced by the noticeably decreased lattice expansion from about 16% to 2% along the b direction. The designed α-MoO 3 /η-Mo 4 O 11 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-MoO 3 , and may offer a rational strategy to develop highly stable electrode materials for advanced batteries.