Discovering new chemistry and materials to enable rechargeable batteries with higher capacity and energy density is of paramount importance. While Li (or Na) metal is the ultimate choice of a battery anode, its low efficiency is still yet to be overcome. Many strategies have been developed to improve the reversibility and cycle life of these metal electrodes. However, almost all the results are limited to shallow cycling conditions (e.g. 1 mAh cm-2) and thus inefficient utilization (&lt;1%). We analyze the cycling and failing behaviors of alkaline metal electrodes, and explore new strategies for stabilization. We use a slow-release electrolyte additive and its decomposition to form a Li ion conductor-containing protective layer which renders reversible, dendrite-free, and highly-dense Li metal deposition. As a result, we successfully. achieve Li metal electrodes that can be deeply cycled at unprecedentedly high capacities of 10 and 20 mAh cm-2 with average Coulombic efficiency &gt; 98% in a commercial LiPF6/carbonate electrolyte. We for the first time introduce a bi-functional electrolyte additive to stabilize Na metal electrodes, where one component decomposes to render a desirable solid electrolyte interphase layer while the other suppresses dendritic deposition. With the cooperation of both components, we have realized Na metal electrodes that can be deeply cycled at the capacity of 10 mAh cm−2 for hundreds of hours.

Cycling, failing, and protection of alkaline metal electrodes for high energy rechargeable batteries

256th National Meeting (2018)

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