Flowing Electrolyte Metal Batteries

Flowing electrolyte metal batteries (FEMBs) are a new class of energy storage devices with metal anodes and flowing electrolytes. In this presentation, electrochemical models predict that flowing electrolyte can accelerate diffusion-limited transport, reducing impedance, increasing stability, and improving coulombic efficiency and cycle life. Electrolyte flow toward the metal electrode reduces and, for flow velocities above a critical speed, changes the sign of the electrolyte impedance, allowing faster charging without exceeding voltage limits. The critical flow rate is very slow (~μm/s) and directly proportional to the charging current density. Concentration of diffusion flux at dendrite tips is responsible for accelerated dendrite growth in metal batteries, so introduction of creeping electrolyte flow normal to electrodes levels ion concentration and eliminates dendrites above the critical speed. Creeping normal flow also significantly reduces solid electrolyte interphase (SEI) growth rate [1]. Creeping Poiseuille and Couette flows that are parallel to the electrodes have no impact on impedance or SEI layer growth, but do reduce dendrite growth, albeit much less effectively than normal flow [2]. Both creeping normal and parallel flows eliminate/reduce dendrite growth, so introducing electrolyte flow, in general, is a promising method to control dendrite growth. As dead Li formation is tied to dendrite growth, and as creeping normal flow eliminates dendrites and reduces SEI layer growth [3], creeping normal flows significantly improve coulombic efficiencies, and cycle life. The low flow rates indicate potential for practical applications. [1] Parekh, Mihir N., Christopher D. Rahn, and Lynden A. Archer. "Controlling dendrite growth in lithium metal batteries through forced advection." Journal of Power Sources 452 (2020): 227760. [2] Parekh, Mihir N., and Christopher D. Rahn. "Reducing Dendrite Growth in Lithium Metal Batteries by Creeping Poiseuille and Couette Flows." Journal of the Electrochemical Society (2020). [3] Parekh, Mihir N., and Christopher D. Rahn. “Solid electrolyte interphase growth on lithium metal electrodes with normal electrolyte flow.’’ Journal of the Electrochemical Society (Submitted). Figure 1