Fluorine-Rich Oxyfluoride Spinel-like Li _1.25 Ni _0.625 Mn _1.125 O ₃ F Utilizing Redox-Active Ni and Mn for High Capacity and Improved Cyclability

High Resolution Image Download MS PowerPoint Slide Extending the accessible capacity and cyclability is of central interest for cathode materials for Li-ion batteries. Here, we report the successful synthesis of a new spinel-like Li 1.25 Ni 0.625 Mn 1.125 O 3 F ( Fd 3 m ) oxyfluoride with significant cation disorder characterized by combined refinement of X-ray and neutron diffraction data. Li 1.25 Ni 0.625 Mn 1.125 O 3 F utilizes redox reactions of both Ni and Mn, accessing capacities of 225 (i.e., 1.46 Li + capacity) and 285 mAh g –1 (i.e., 1.85 Li + capacity) at 25 and 40 °C, respectively, through intercalation of additional Li + into the lattice. Moreover, compared to lithium transition metal disordered rocksalt or spinel-like oxyfluorides previously reported, Li 1.25 Ni 0.625 Mn 1.125 O 3 F shows significantly improved cycling stability. Ex situ compositional, structural, and spectroscopic analyses of samples at different states of charge/discharge confirm a single-phase intercalation reaction and high structural integrity over cycling.