Quenching-induced lattice modifications endowing Li-rich layered cathodes with ultralow voltage decay and long life†

While bringing high capacity, oxygen redox in Li-rich layered oxides has also led to severe voltage decay, hindering their practical applications. To break through this bottleneck, we herein propose a general and versatile strategy, brine quenching, to address this issue. Combining with multiple-scale characterizations, theory calculation and electrochemical performance, the underlying mechanism of voltage decay suppression by brine quenching is distinctly revealed. The quenching process can generate local bulk-compatible distortion, which can adjust the whole lattice oxygen framework to mitigate the disorder, and modulate the intrinsic redox properties of the material. The resulting LLO will maintain the ordered structure after long-term cycling, thus mitigating the voltage decay. Additionally, a robust surface can be established through the ion exchange to restrict oxygen release. Therefore, lattice oxygens both in the bulk and surface are stabilized. Benefiting from the synergistic effect, the 1.6 Ah full cell based on the magnesium–nitrate-solution-quenched sample exhibits over 80% retention after 2159 cycles and an ultra-long lifespan of 3200 cycles with a negligible voltage decay rate of 0.091 mV per cycle. This research provides a potential direction for designing next-generation cathode materials that combine long-life and ultralow voltage decay.