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- Mohammadi, Abdolkhaled, et al.
(författare)
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Measuring the Nucleation Overpotential in Lithium Metal Batteries : Never Forget the Counter Electrode!
- 2022
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 169:7
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Tidskriftsartikel (refereegranskat)abstract
- The nucleation overpotential has been used by many researchers as an indicator of the energy required to form the Li nuclei during plating. Typically, a two-electrode system is used to measure the nucleation overpotential; this method, however, fails to show the contribution of working and counter electrodes separately. In this study, we have used a three-electrode configuration (three-dimensional nickel foam as working electrode, lithium foil as both reference and counter electrode) to deconvolute the potential associated with each electrode during the galvanostatic Li electrodeposition to obtain a clear picture of nucleation overpotential. The results indicate that, in such a system, the main source of overpotential is the sudden drop in the potential of the counter electrode, which can be attributed to the extraction of Li from the surface of lithium metal. Moreover, unlike the first half-cycle, the nuclear overpotential is dominated by the working electrode in the second half-discharge cycle, which should account for a true nucleation overpotential of the system. This finding may aid in clarifying the origins of the experimental polarization and preventing researchers from misinterpreting it in terms of nucleation overpotential.
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| 2. |
- Mohammadi, Abdolkhaled, et al.
(författare)
-
Towards understanding the nucleation and growth mechanism of Li dendrites on zinc oxide-coated nickel electrodes
- 2022
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 10:34, s. 17593-17602
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Tidskriftsartikel (refereegranskat)abstract
- While lithium metal is considered an ideal anode for the next generation of high-energy-density batteries, some major issues such as huge volume change and continuous dendrite formation during lithium plating have hindered its practical applications. Zinc oxide (ZnO) modification of surfaces has shown great potential for inducing a homogeneous Li plating to attain dendrite-free lithium metal anodes. Although considerable improvements in electrochemical performance have been achieved, the detailed mechanism of the evolution of Li nucleation and growth morphology remains elusive. Here, we combine experimental and theoretical calculations to study the Li deposition behaviour during and after the initial nucleation on a thin and uniform layer of ZnO-coated 3D nickel foam. Upon lithiation of the ZnO layer, Li2O and LiZn are formed through a conversion reaction; this composite layer provides specific properties ensuring a homogeneous Li plating. The results showed that dendrite growth not only leads to the formation of cracks on the surface but also provokes the breakoff of some parts of the converted layers from the bulk surface. In addition, no new nucleation occurs upon continued Li deposition, with Li plating mainly taking place on the initial nuclei underneath the protective layer. As a result, large granular Li particles grow at the site of the initial Li nucleation centre, leading to the improvement of electrochemical performances. A deeper understanding of the mechanism of Li nucleation and growth and the morphology of the formed dendrites can help with the development of lithium metal batteries.
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