In-built intermolecular hydrogen bonds enabling stable interfacial chemistry for all-solid-state Li metal batteries

The guest–host chemistry in polymer electrolytes plays a crucial role for all-solid-state Li metal batteries, where the stable operation of such batteries heavily relies on high ion conductivity, strong mechanical properties, and stable interfaces of the electrolyte. While traditional ceramic fillers can boost ion conductivity, they fail to improve interfacial stability. In this study, we introduce intermolecular hydrogen bonding into a polyethylene oxide (PEO)-based polymer electrolyte through the incorporation of metal organic framework (MOF) and lithium nitrate additives. The hydrogen on the PEO chain is found to be tightly interacted with the oxygen nodes of UiO-66 MOF and nitrate anions, creating a cross-linked framework that reduces the crystallinity of the PEO and enhances the integrity of composite. This interaction induces a beneficial Li₃N and LiF-rich solid electrolyte interphase, ensuring 2000 h of stable lithium metal operation without short-circuits. The strong polysulfide adsorption enables compatibility with high-capacity sulfur cathodes, resulting in solid-state Li-S batteries that can achieve a high capacity of 913.8 mAh·g⁻¹ and exhibit stable cycling performance. This work demonstrates the deep understanding of guest–host chemistry in polymer electrolytes and their potential in developing energy-dense solid-state Li metal batteries.