Ambiently fostering solid electrolyte interphase for low-temperature lithium metal batteries

Despite being a leading candidate to meet stringent energy targets, lithium (Li) metal batteries (LMBs) face severe challenges at low temperatures such as dramatic increase in impedance, capacity loss and dendrite growth. Unambiguously fingerprinting rate-limited factors of low-temperature LMBs would encourage targeted approaches to promote performances. Herein, the charge transfer impedance across solid electrolyte interphase (SEI) is identified to restrict battery operation under low temperature, and we propose a facile approach on the basis of ambiently fostering SEI (af-SEI) to facilitate charge transfer. The concept of af-SEI stems from kinetic benefits and structural merits to construct SEI at ambient temperature over low temperature developed SEI that is temporally consuming to achieve steady state and that is structurally defective to incur dendrite growth. The af-SEI allows ionically conductive and morphologically uniform layer on the anode surface, which exhibits a lower resistance and induces an even deposition of Li in the subsequent low temperature battery operation. Armed with af-SEI, the LMBs deliver the improved rate performance and prolonged cycle life when subjected to low temperature cycling. This work unveils the underlying causes that limit low temperature LMB performances, and enlightens the facile test protocols to build up favorable SEI, beyond scope of material and morphology design.