Use of Carbon Additives towards Rechargeable Zinc Slurry Air Flow Batteries

Abstract

The performance of redox flow batteries is notably influenced by the electrolyte, especially in slurry-based flow batteries, as it serves as both an ionic conductive electrolyte and a flowing electrode. In this study, carbon additives were introduced to achieve a rechargeable zinc slurry flow battery by minimizing the zinc plating on the bipolar plate that occurs during charging. When no carbon additive was present in the zinc slurry, the discharge current density was 24 mA∙cm−2 at 0.6 V, while the use of carbon additives increased it to up to 38 mA∙cm−2. The maximum power density was also increased from 16 mW∙cm−2 to 23 mW∙cm−2. Moreover, the amount of zinc plated on the bipolar plate during charging decreased with increasing carbon content in the slurry. Rheological investigation revealed that the elastic modulus and yield stress are directly proportional to the carbon content in the slurry, which is beneficial for redox flow battery applications, but comes at the expense of an increase in viscosity (two-fold increase at 100 s−1). These results show how the use of conductive additives can enhance the energy density of slurry-based flow batteries.

Highly conductive colloidal carbon based suspension for flow-assisted electrochemical systems

“…Extensive research is undertaken for the management of energy with new technologies that exploit renewable sources ( Aneke and Wang, 2016 ; Akinyele and Rayudu, 2014 ; Chakrabarti et al., 2020 ). In the last decade, carbon black dispersions have been used as active material in different flow-assisted electrochemical energy storage systems (FAESs) ( Skyllas-Kazacos et al., 2011 ; Skyllas Kazacos et al., 1986 ; Weber et al., 2011 ; Liu et al., 2020 ; Choi et al., 2020 ). In these systems, the carbon black dispersions serve as flowable electrodes in semi-solid flow batteries dispersed in an electrolyte solution ( Duduta et al., 2011 ) or as active materials in the electrochemical flow capacitor ( Presser et al., 2012 ) or in the flow capacitive deionization of water ( Hatzell et al., 2014 ; Rommerskirchen et al., 2020 ).…”

Redox Flow Batteries: Materials, Design and Prospects

“…Furthermore, the charge storage capacity of the solid particles can be restrained in the tanks and ca. 80% of this capacity can be reached depending on the compatibility established between the redox electrolyte and redox solid [279]. Furthermore, it is also possible to combine the slurry redox flow battery with other configurations, e.g., slurry-air [280].…”

“…80% of this capacity can be reached depending on the compatibility established between the redox electrolyte and redox solid [278]. Furthermore, it is also possible to combine the slurry redox flow battery with other configurations, e.g., slurry-air [279]. However, every approach until now severely undermines the electrolyte flow due to high viscosity, increasing the pressure drop and ultimately decreasing the round-trip efficiency.…”

Pristine and Modified Porous Membranes for Zinc Slurry–Air Flow Battery

“…In other words, the Zn slurry (Zn particles suspended in alkaline electrolytes) is used as both the anode electrode and electrolyte [ 20 , 21 ]. In these batteries, unlike conventional Zn–air batteries, the volume of tank or the amount/concentration of Zn particles in the slurry, rather than the size of the porous Zn electrode used in the system, determine the capacity of the battery [ 22 , 23 ]. Moreover, such Zn slurry-based configuration is believed to minimize formation of dendrites and surface passivation since the negative electrode acts only as a current collector [ 9 , 23 , 24 , 25 ], thus enhance battery performance.…”