Interface-Mediated Jahn–Teller Effect in a Structure-Reinforced LiMnO 2 Cathode

Lithium manganese-rich oxides are promising cobalt-free cathodes, but their viability is plagued by cooperative Jahn–Teller (CJT) distortions of Mn3+ ions. Conventional strategies only partially mitigate this instability without addressing its electronic origin. Herein, we demonstrate a paradigm of interfacial orbital ordering to suppress CJT distortions at its root. We construct a spinel-layered LiMnO2 heterostructure with noncollinear JT ordering (SLNC-LMO) and benchmark it against a collinear analog. Atomic-resolution imaging confirms the near-orthogonal arrangement of MnO6 octahedra across the interfaces. Combined with density functional theory calculations, we reveal that this noncollinear ordering introduces orbital geometric frustration, which drastically reduces the eg orbital splitting energy to 0.24 eV from 1.12 eV of the collinear structure. This near restoration of orbital degeneracy suppresses long-range distortion propagation and enhances interfacial cohesion. Consequently, the SLNC-LMO cathode delivers exceptional cycling stability, retaining 100% of its capacity after 500 cycles, far outperforming the collinear counterpart. This work establishes interfacial orbital engineering as a general design principle for stabilizing manganese-rich and other Jahn–Teller-active electrode materials.