Stabilizing LiNi0.8Co0.1Mn0.1O2 cathodes with a mixed ionic-electronic conducting Li0.34La0.55MnO3- multifunctional coating formed via in-situ conversion of surface Li residual

In this work, we for the first time utilize the harmful surface Li residual on NCM811 to in-situ form a mixed Li+/electron conducting Li0.34La0.55MnO3-x (LLMO) coating. The formation of the (electro)chemically stable LLMO coating not only achieves effective surface cleaning, but also stabilizes the cathode surface against electrolyte attack, alleviating structure degradation and intergranular cracking. Equally importantly, the mixed conducting LLMO layer affords considerably high Li+ and electronic conductivities (2.35×10-5 S/cm and 1.86×10-3 S/cm respectively), accelerating the charge-transfer process at the interface. The in-situ LLMO-coated NCM811 exhibits notable improvements in both rate and cycling performance, featuring a capacity retention rate of 82.51% over 100 cycles at 1 C in stark contrast to 48.26% of the pristine NCM811. When combined with a dendrite-suppressed Li@Pb@carbon cloth composite Li metal anode in a full battery, a high capacity retention rate of 86.96% over 200 cycles at 1 C and a N/P ratio of 37.7 is achieved, significantly outperforming that with NCM811 (42.24%, 40.2). This study provides a novel and comprehensive solution to stabilize nickel-rich layered cathode materials for high-energy-density Li-metal batteries.