LATP-coated LiNi0.8Co0.1Mn0.1O2 cathode with compatible interface with ultrathin PVDF-reinforced PEO-LLZTO electrolyte for stable solid-state lithium batteries

LiNi0.8Co0.1Mn0.1O2 (NCM811) is considered as a promising cathode for high-energy-density solid-sate Li metal battery for its high theoretical capacity. However, the high oxidizability and structural instability during charge limit its practical applications. In this work, 1% (in mass) of nanosized Li1.3Al0.3Ti1.7(PO4)3 (LATP) was coated on NCM811 to enhance its electrochemical stability with a ceramic/polymer composite electrolyte. A robust, ultrathin (11 μm) composite electrolyte film was prepared by combining poly(vinylidene fluoride) (PVDF) with polyethylene oxide (PEO)-Li6.5La3Zr1.5Ta0.5O12 (LLZTO). An in-situ polymerization process was used to enhance the interface between the PVDF/PEO-LLZTO (PPL) composite electrolyte and the LATP-coated NCM811 (LATP-NCM811). Coin-type Li|LATP-NCM811 cell with the PPL electrolyte exhibits stable cycling with an 81% capacity retention after 100 cycles at 0.5 C. Pouch-type cell was also fabricated, which can be stably cycled for 70 cycles at 0.5 C/1.0 C (80% retention), and withstand abuse tests of bending, cutting and nail penetration. This work provides an applicable method to fabricate solid-state Li metal batteries with high performance.