Low‐Carbon‐Content Composite Bipolar Plates: A Novel Design and Its Performance in Vanadium Redox Flow Batteries

Abstract

Bipolar plates possessing both high electrical conductivity and mechanical strength has been urgently required for redox flow batteries and fuel cells. Contrary to the conventional method of increasing carbon content to maximize the bipolar plate's electrical conductivity, a novel low-carbon-content design based on the bridging effect of graphene is developed. The microstructure, electrical conductivity, flexural strength, vanadium permeability, corrosion current density and its perform-ance in vanadium redox flow battery single cell have been investigated. The low-carbon-content bipolar plates present both high electrical conductivity and flexural strength. Low area specific resistance of 3.3 mΩ cm 2 is reached at 18.7 wt.% carbon content, and flexural strength of 48.1 MPa can be obtained after being reinforced by carbon fibers. The voltage efficiency and energy efficiency of the single cell reach as high as 88.6% and 85.7%, respectively, at 100 mA cm À 2 .Keywords: bridging effect · composite bipolar plates · high performance · low-carbon-content · vanadium redox flow battery.

Redox Flow Batteries: Materials, Design and Prospects

“…83% of EE at 40 mA cm −2 was reported and the battery was cycled for 100 cycles at the same current density without substantial degradation. A new low-carbon-content design based on the bridging effect of graphene for bipolar plates published by Liao and colleagues [89] achieved ca. 83% EE at 140 mA cm −2 .…”

Fluoropolymer impregnated graphite foil as a bipolar plates of vanadium flow battery

“…3 Indeed, a combination of a carbon-based conductive filler and inert polymer as binder results in good electrical conductivity, compactness, and soft mechanical processing. Graphite and its modified types, including expanded graphite, 7 synthetic anisotropic graphite, 8 mineral graphite, 9,10 compressed expanded graphite, 11,12 graphite and graphene mixture, 13 graphite foil, 14 carbon in different forms, such as carbon nanotubes, 8 carbon fabric, 15,16 carbon and carbon fibers mixture, 17 are used in the capacity of carbon-containing raw material. Thermoplastics polymers (polyvinylidene fluoride, 18 polypropylene, 9,19,20 etc.)…”

Promising Material Based on Paraffin‐Impregnated Graphite Foil with Increased Electrochemical Stability for Bipolar Plates of Vanadium Redox Flow Battery

“…Mineral, [5,6] synthetic, [7] and expanded [8][9][10][11] graphite as well as carbon black and carbon fibers [7,[12][13][14][15][16][17] can be used as a carbon-containing material. Variety of thermosetting (such as epoxy, [9,10,18] and phenolic [8] resins), and thermoplastic (such as polyvinylidene fluoride (PVDF), [19] polytetrafluoroethylene (PTFE), [11] polypropylene (PP), [5,[20][21][22] and polyethylene (PE) [17,15] ) inert polymers can be used as a filler for composite BPs. Such BP production methods as compression and injection molding are usually used, but many other methods (layers molding, soft-layer method, impregnation with molding, plate extrusion, etc.)…”