Effect of the Electrolyte on the Cycling Efficiency of Lithium-Limited Cells and their Morphology Studied Through in Situ Optical Imaging

Capacity retention of anode-free cells, in which the cathode’s lithium was the sole lithium source, was studied. These cells fail by depletion of their limited amount of cycling lithium, unlike cells with lithium foil anodes in which the buildup of an insulating, dead lithium layer on the anodes causes failure. The electrolyte dependence of the deposition morphologies was also studied optically in a symmetrical cell built with lithium electrodes. After passage of 28 mAh cm–2, dendrite-free deposits were observed in a concentrated LiNO3 electrolyte. SEI characterization revealed that this LiNO3 concentrated electrolyte formed a Li2O enriched and organic polymer depleted interphase.