Interface-Mediated Jahn-Teller Effect in a Structure-Reinforced LiMnO₂ Cathode

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Lithium manganese-rich oxides are promising cobalt-free cathode materials.
• Cooperative Jahn-Teller (CJT) distortions of Mn³⁺ ions limit their electrochemical performance.
• Current mitigation strategies do not fully address the electronic origins of instability.

Purpose of the Study:

• To introduce a novel interfacial orbital ordering paradigm to suppress CJT distortions at their root.
• To design and characterize a spinel-layered LiMnO₂ heterostructure with noncollinear Jahn-Teller (JT) ordering (SLNC-LMO).
• To demonstrate the effectiveness of this strategy in enhancing cathode stability and performance.

Main Methods:

• Construction of a spinel-layered LiMnO₂ heterostructure with noncollinear JT ordering.
• Atomic-resolution imaging to analyze octahedral arrangements.
• Density functional theory (DFT) calculations to investigate electronic structure and orbital interactions.
• Electrochemical cycling tests to evaluate performance.

Main Results:

• Atomic-resolution imaging confirmed near-orthogonal MnO₆ octahedra in the SLNC-LMO heterostructure.
• DFT calculations revealed orbital geometric frustration in SLNC-LMO, reducing e_g orbital splitting energy to 0.24 eV (vs. 1.12 eV for collinear analog).
• The SLNC-LMO cathode exhibited exceptional cycling stability, retaining 100% capacity after 500 cycles.

Conclusions:

• Interfacial orbital ordering effectively suppresses CJT distortions by inducing orbital geometric frustration.
• The SLNC-LMO heterostructure demonstrates superior electrochemical stability compared to collinear analogs.
• This work establishes interfacial orbital engineering as a viable design principle for stabilizing Jahn-Teller-active electrode materials.