ZnO/carbon framework derived from metal-organic frameworks as a stable host for lithium metal anodes

Lithium metal is the ideal anode for the next generation of high-energy-density batteries. Nevertheless, dendrite growth, side reactions and infinite relative volume change have prevented it from practical applications. Here, we demonstrate a promising metallic lithium anode design by infusing molten lithium into a ZnO/carbon framework, which is obtained by pyrolysis of a typical metal-organic framework (MOF) ZIF-8. The ZnO/carbon scaffold is not only stable against highly reactive molten lithium, but also very lithiophilic via abundant carbonyl and nitrogen-containing surface groups and zinc oxide sites, which are in-situ generated from the ZIF-8. The molten lithium can be drawn into the composite, affording a nano-structured lithium electrode. Importantly, the ZnO/carbon scaffold enables uniform lithium stripping/plating by successfully confining lithium within the composite, resulting in minimum volume change and effective dendrite suppression. The porous electrode reduces the effective current density; thus, flat voltage profiles and stable cycling of more than 200 cycles is achieved even at a high current density of 10 mA cm−2. The advantages of the porous, stable MOF-derived ZnO/carbon electrode provide important insights into the design principles of lithium metal anodes.