Metal batteries can theoretically provide high energy density and low cost energy storage but electroplating on the metal electrode surfaces during charging can lead to dendrite growth that reduces cycle life and can lead to internal short circuits. Previous research shows that forced advection through porous lithium metal electrodes can eliminate dendrite growth. In this paper, we study the effect of electrolyte flow through perforated metal anodes on dendrite growth and energy density.  The diameter and spacing of the perforations and the electrode thickness are varied and simulated using a 2D COMSOL Multiphysics model. The electrolyte flow velocities are sufficiently low for creeping flow assumptions to be valid. The 2D COMSOL Multiphysics model shows the evolving lithium metal electrode surface with time. The flowing electrolyte carries lithium ions into the slot (2D model of the pore), thus leading to plating within the slot. The concentration of ions within the slot increases with time. At any given instance, the concentration in the slot is higher for higher electrolyte flow rates. Increasing the flow rate also reduces the charging overpotential. Initially, plating occurs both inside the slot and on the lithium metal electrode surface facing the counter-electrode. The plating current density is maximum at the top of the slot, because electric field lines and concentration gradient lines tend to concentrate at the tip separating the slot from the flat part of the electrode. With increasing time, the amount of plating occurring inside the slot increases. Eventually, almost all plating is inside the slot eliminating the risk of dendrite growth. However, if the slot width is too small, it can lead to eventual slot closure and flow blockage. Higher the electrolyte velocity, lower the amount of time required for entire plating to take place within the slot. Larger slot separation and thicker electrodes reduce the local plating current density and dendrite growth, due to higher surface area available for plating. However, it also increases the mass of the lithium metal electrode and thus reduces the energy density. Hence, this is an optimization problem. Increasing the slot width leads to higher plating current densities on part of the electrode directly facing the counter electrode. This may lead to higher dendrite growth rate in a direction normal to the counter electrode and thus increase the probability of short circuits. Small slot widths lead to the slot being plugged due to electroplating inside the hole. Thus, there is an optimum slot width that should be used. We perform multiple COMSOL simulations and present these optimization problems as Pareto curves.


Dendrite Suppression and Energy Density in Metal Batteries With Electrolyte Flow Through Perforated Electrodes

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Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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