Adroit Market Research - Industry Insights

One of the major aim behind the development of vanadium redox flow batteries (VRFBs) is the upgrading density of cell power. Presently, a large number of VRFBs manufacturers operating in market are using graphite felt electrodes in moderately lesser density that results in a big cell ohmic resistance & limits maximum power density. Previously, top performing VRFBs were using carbon paper electrodes along with great active zone compression pressures identical to the fuel cells. This Paper enables in analyzing the usage of felt electrodes at alike compression pressures and how will that help in guiding electrode as well as optimization of cell in a significant energy storage technology.

One of the major aim behind the development of vanadium redox flow batteries (VRFBs) is the upgrading density of cell power. Presently, a large number of VRFBs manufacturers operating in market are using graphite felt electrodes in moderately lesser density that results in a big cell ohmic resistance & limits maximum power density. Previously, top performing VRFBs were using carbon paper electrodes along with great active zone compression pressures identical to the fuel cells. This Paper enables in analyzing the usage of felt electrodes at alike compression pressures and how will that help in guiding electrode as well as optimization of cell in a significant energy storage technology.

Single cells are accumulated with compression pressures of around 0.2 to 7.5 bar and then are tried in a VRFB- based system. The maximum cell compression pressure joint with a reedy Nafion membrane, accomplished a highest power density of around 669 mW cm−2 at the flow rate of about 3.2 mL min to 1 per cm2 of dynamic zone that is almost more than double of the past finest performance as of a felt vanadium redox flow batteries. Thus, with the help of the study it was clear that felt electrodes might compete with the paper electrodes as far as performance is concerned while in same compression pressures.

The augmenting growth of renewable sporadic power supplies such as solar, wind and tidal that requires an associated progression of energy storage systems. Presently lithium-ion batteries are ruling the applications of electrochemical energy storage owing to the cost efficiency, higher energy density as well as consistency. Nevertheless, redox flow batteries (RFBs) has been comprehended as a striking substitute of lithium-ion, regardless of the fact that they are costlier. This is because RFBs have got extended lifespans, lesser risk of catching fire and are ecofriendly since they can be reused. Moreover, capacity as well as power are entirely broken down in a flow battery with the power determined by dimensions of the stack & capability determined by the volume as well as concentration of electrolyte. So, redox flow batteries provides a versatile approach to energy storage that is proficient in both long as well as short interval applications, along with their market impact which is anticipated to speedily increase in upcoming years.

In addition, vanadium redox flow battery (VRFB) is when compared with a number of flow battery chemistries available in the market, turned out to be best especially for the commercialized owing to its extended lifespan and recycling easiness. Certainly, China has got the world’s biggest vanadium redox flow battery. Although VRFBs are very much successful, their system cost is a key concern and is required to be reconsidered for the technology to be competitive. A key approach for the cost reduction of VRFB can be improving the density and performance of cell power. While comparing VRFBs to polymer electrolyte fuel cells (PEFCs) with similar cell structural design, VRFBs have very poor performance. For instance, conventional polymer electrolyte fuel cells can effortlessly accomplish existing densities of around 1.5 A cm−2 while most of the VRFBs installed nowadays function at existing densities of around 0.2 A cm−2 or less.

Though a comparing these directly wouldn’t be fair direct comparison as VRFBs generally function at a greater efficiencies than of PEFCs, but comparatively poor performance of VRFB cells than PEFCs necessities considerably longer cells for the particular power. For instance, a conventional stack of approx. 5 kW VRFB that is alike magnitude to that of the 114 kW fuel cell stack in Toyota Mirai. Several scientists have evaluated the cost effecting factors related with the VRFBs and concluded that the stack gives approximately 30–32% of entire system cost. Therefore, if the performance similar to the fuel cells could be attained, the magnitude of VRFB stacks might decrease from any direction of magnitude, surprisingly impacting the system cost.

In addition, electrode material plays a major role in determining the flow battery cell’s performance. Besides, graphite felt is amongst the most preferred electrode material for VRFBs since it has higher conductivity, promising absorptivity, electrochemical constancy and huge surface area.

In one of the initial investigations over VRFBs, Kazacos & Skyllas–Kazacos realized a highest power density of around 85 mW cm−2 by graphite felt electrodes. Ever since, a number of scientists have enhanced the performance thru kinematic effects, altering graphite felt electrodes in order to upsurge their reactivity as well as lessening the potential allied associated with propelling the electrochemical reactions.

Furthermore, some of the studies corrected the cell performance by presenting even more satisfactory mass transport of electrolyte via felt electrodes. Furthermore, substantial gains in the performance has been accomplished by decreasing the ohmic resistance of the cell, by rising the compression of felt electrode as well as lessening the contact resistance inside the cell.

One of the utmost power densities documented through felt electrodes was found by Chen et al., who accomplished approx. 311 mW cm−2 with a GFA5 felt electrode by a compression of around 33%. That performance were marginally enhanced by Zhao & associates, who attained a utmost power density of around 350 mW cm−2 with a VRFB using GFA5 electrodes at higher temperature. On the other hand, the compression of the electrodes were not documented.