High Energy Density Single-Crystal NMC/Li₆PS₅Cl Cathodes for All-Solid-State Lithium-Metal Batteries

To match the high capacity of metallic anodes, all-solid-state batteries require high energy density, long-lasting composite cathodes such as Ni-Mn-Co (NMC)-based lithium oxides mixed with a solid-state electrolyte (SSE). However in practice, cathode capacity typically fades due to NMC cracking and increasing NMC/SSE interface debonding because of NMC pulverization, which is only partially mitigated by the application of a high cell pressure during cycling. Using smart processing protocols, we report a single-crystal particulate LiNi_0.83Mn_0.06Co_0.11O₂ and Li₆PS₅Cl SSE composite cathode with outstanding discharge capacity of 210 mA h g^-1 at 30 °C. A first cycle coulombic efficiency of >85, and >99% thereafter, was achieved despite a 5.5% volume change during cycling. A near-practical discharge capacity at a high areal capacity of 8.7 mA h cm^-2 was obtained using an asymmetric anode/cathode cycling pressure of only 2.5 MPa/0.2 MPa.