Long cycle life and dendrite-free lithium morphology in anode-free lithium pouch cells enabled by a dual-salt liquid electrolyte

Cells with lithium-metal anodes are viewed as the most viable future technology, with higher energy density than existing lithium-ion batteries. Many researchers believe that for lithium-metal cells, the typical liquid electrolyte used in lithium-ion batteries must be replaced with a solid-state electrolyte to maintain the flat, dendrite-free lithium morphologies necessary for long-term stable cycling. Here, we show that anode-free lithium-metal pouch cells with a dual-salt LiDFOB/LiBF4 liquid electrolyte have 80% capacity remaining after 90 charge–discharge cycles, which is the longest life demonstrated to date for cells with zero excess lithium. The liquid electrolyte enables smooth dendrite-free lithium morphology comprised of densely packed columns even after 50 charge–discharge cycles. NMR measurements reveal that the electrolyte salts responsible for the excellent lithium morphology are slowly consumed during cycling. Extensive efforts have recently been geared towards developing all-solid-state batteries largely because of their potential to enable high-energy-density Li anodes. Here, the authors report a high-performance lithium pouch cell with no excess lithium, enabled by just a dual-salt liquid electrolyte.