A Single‐Flow Battery with Multiphase Flow

Abstract

Widespread adoption of redox flow batteries (RFBs) for renewable energy storage is inhibited by a relatively high cost of storage. This is due largely to typical RFBs requiring two flows, two external tanks, and expensive ion‐exchange membranes. Here, we propose a potentially inexpensive Zn‐Br2 RFB which is membraneless and requires only a single flow. The flow is an emulsion consisting of a continuous, Br2‐poor aqueous phase and a dispersed, Br2‐rich polybromide phase, pumped through the channel separating anode and cathode. With our prototype cell, we explore the effect of polybromide‐phase volume fraction and Br2 concentration on cell performance and plating efficiencies. We demonstrate high discharge currents of up to 270 mA/cm2, plating efficiencies up to 88 %, and dendriteless plating up to the highest Zn loading investigated of 250 mAh/cm2. We provide mechanistic insights into cell behavior and elucidate paths towards unlocking ultra‐low‐cost single‐flow RFBs with multiphase flow.

SOC (STATE of CHARGE) THREE-CELL LEAD DYNAMIC BATTERY MODEL

“…7,8 An electrochemical reaction occurs when the electrolyte flowing from the tank interacts. 9 There are two types of dynamic batteries, 10 a single electrolytic dynamic batteries 11,12 and dual electrolytic dynamic batteries. 13 a single electrolyte dynamic battery is accommodated in a reservoir which is circulated to the battery cell unit such as a lead acid dynamic battery.…”

Properties of Bromine Fused Salts Based on Quaternary Ammonium Molecules and Their Relevance for Use in a Hydrogen Bromine Redox Flow Battery

“…An additional advantage is that fused salt drops adhering to the electrode surface lead to higher discharge current densities, since Br 2 is released from the fused salt into the aqueous phase directly at the electrode surface [12] . Amit et al [33] . apply emulsions of aqueous electrolyte and the fused salt in a membrane‐less Zn/Br 2 ‐RFB.…”

“…apply emulsions of aqueous electrolyte and the fused salt in a membrane‐less Zn/Br 2 ‐RFB. In their work they show that increasing the volume fraction of the fused salt phase from 1 to 5 vol % in the emulsion, significantly increased both the discharge current densities and the ohmic resistance of the cell [33] . If not managed correctly, the accumulation of fused salt droplets on the graphite electrode surfaces [34] can lead to the complete coverage of the electrode surface which results in a decrease of the current densities of the cell [12] .…”

Modelling the fluid mechanics in single-flow batteries with an adjacent channel for improved reactant transport

“…In an effort to reduce battery capital costs, a fast-emerging sub-class is the single-flow RFBs. Such systems operate with only a single electrolyte flow, enabling a significant system simplification and cost reduction, as they require only a single tank, flow loop and are membraneless (Amit, Naar, Gloukhovski, Ola, & Suss, 2021; Cheng et al, 2013; Xie, Liu, Lu, Zhang, & Li, 2019). Various types of batteries have been utilized in the single-flow cell architecture, such as batteries with two metal reactants (e.g.…”

“…zinc–nickel) (Cheng et al, 2007; Xiao et al, 2016; Yao, Zhao, Sun, Zhao, & Cheng, 2019), cells with a single multiphase flow (e.g. zinc–bromine) (Amit et al, 2021; Ronen, Gat, Bazant, & Suss, 2021) and cells with one metal electrode and a separator (e.g. lithium–sulphur or zinc–bromine) (Lai, Zhang, Li, Zhang, & Cheng, 2013; Yang, Zheng, & Cui, 2013).…”