Lawrence Berkeley National Laboratory

Developing high-capacity, long-life cathodes is critical to overcome the energy limitations of current Li-ion batteries. Here, we report a Li-excess cation-disordered rocksalt (DRX) cathode, Li₁.₁₆₇Mn₀.₇Ti₀.₁₃₃O₁.₈F₀.₂ (M₀.₇F₀.₂), which demonstrates excellent electrochemical performance. This cathode delivers a capacity approaching 250 mAh g^-1 and maintains 200 mAh g^-1 over 200 cycles with an average discharge voltage of 3.1 V at 2 V cutoff. The formation of a spinel-like phase during cycling enables fast charging, achieving over 240 mAh g^-1 at 2C for 100 cycles. Combined X-ray absorption spectroscopy and transmission electron microscopy reveal reversible electrochemical redox processes and stable Mn local structures during 2 V discharge. These results highlight the potential of DRX cathodes for next-generation Li-ion batteries and provide insights into strategies to overcome kinetic limitations and optimize the cathode-electrolyte interface.