Creating partial disorder in spinel-type cathodes for enhanced kinetics and cycling stability

The Mn-based spinel-type cathode material LiMn 2 O 4 (LMO) attracts widespread attention due to its low cost, eco-friendly characteristics, ease of synthesis, and stable chemical properties. However, its intrinsic two-phase reaction leads to relatively lower practical capacity and poor cycling stability, restricting its application. This study introduces partial disorder into LMO through high-energy ball milling, synthesizing the fluorinated and lithium-rich material Li 1.5 Mn 1.73 O 3.8 F 0.2 (LMOF). Structural characterization, including X-ray diffraction, neutron diffraction, transmission electron microscopy, and X-ray absorption spectroscopy, reveals cation disorder compared with ordered LMO. The voltage profiles indicate a solid-solution reaction in partially disordered LMOF, replacing the conventional sluggish two-phase transition in fully ordered LMO. The suppressed phase transitions contribute to improved cycling stability and rate capability. Apparent lithium-ion diffusivity is enhanced by approximately two to three orders of magnitude, with the difference also reflecting particle-size-related surface-area effects, while impedance is reduced. Electrochemical evaluation shows a high initial capacity of 337.53 mAh g -1 and capacity retention of 86.54% after 100 cycles. This work shows that tuning cation disorder offers a promising strategy to optimize spinel-type cathodes for sustainable, high-performance lithium-ion batteries.