Integrated cathode/electrolyte with low resistance enables untra-long cycle-lifetime in solid-state lithium-metal batteries

All-solid-state lithium metal batteries (LMBs) are widely recognized as one of the most promising next-generation energy storage technologies. However, their commercialization is still hampered by insufficient interfacial contact between the solid electrolyte and the cathode, along with low ionic conductivity in these solid components. In this work, a highly efficient “solid-polymer-solid” Li + transport channel was constructed based on a Diels–Alder (DA) crosslinked polyurethane (PU) incorporated with lithium bis(trifluoromethyl sulfonyl)imide (PUDAL). This polymer system was applied simultaneously as both the cathode binder and the solid electrolyte. The interfacial resistance between the solid electrolyte and the cathode is significantly reduced through the construction of an integrated interfacial structure. An intimate contact at the molecular level is generated by the DA bonds, which enhances the compatibility and stability of the cathode-electrolyte interface and facilitates continuous Li + transport pathways. The utilization of DA bonds for cross-linking solid polymer electrolytes enables the preparation of solid-state electrolytes with enhanced electrochemical and mechanical properties. These improved characteristics contribute to more uniform lithium metal deposition and effective suppression of lithium dendrite growth. The Li symmetric cells employing PUDAL exhibited stable cycling for over 1500 hours (0.1 mA cm -2 ) at both 60 °C and 30 °C. Furthermore, the integrated LFP-PUDAL |PUDAL| Li full cells demonstrated remarkable long-term charge/discharge stability and high capacity retention under the same temperature conditions.