A Quasi-Solid-State Polymer Lithium–Metal Battery with Minimal Excess Lithium, Ultrathin Separator, and High-Mass Loading NMC811 Cathode

Solid-state batteries with lithium metal anodes are considered the next major technology leap with respect to today’s lithium-ion batteries, as they promise a significant increase in energy density. Expectations for solid-state batteries from the automotive and aviation sectors are high, but their implementation in industrial production remains challenging. Here, we report a solid-state lithium–metal battery enabled by a polymer electrolyte consisting of a poly(DMADAFSI) cationic polymer and LiFSI in Pyr₁₃FSI as plasticizer. The polymer electrolyte is infiltrated and solidified in the pores of a commercial LiNi_0.8Mn_0.1Co_0.1O₂ (NMC811) cathode with up to 2.8 mAh cm^–2 nominal areal capacity and in the pores of a 25 μm thin commercial polypropylene separator. Cathode and separator are finally laminated into a cell in combination with a commercial 20 μm thin lithium metal anode. Our demonstration of a solid-state polymer battery cycling at full nominal capacity employing exclusively commercially available components available at industrial scale represents a critical step forward toward the commercialization of a competitive all-solid-state battery technology.