![]() reported on the rheological and electrical properties of two kinds of carbon blacks, namely ketjen black (KB) and super C45, in organic medium. This network should sufficiently sustain as high amount of electroactive (electrically insulating) materials as possible for enhanced energy capacity but still has considerable flowability. ![]() A fundamental requirement for these cells is the formation of percolated network of electronically conductive CB particles. 12 which highlighted the importance of replacing the nonaqueous cells by alternative aqueous-based cells, offering scalable low-cost storage. ![]() Thereafter, the focus of research was devoted to nonaqueous-based cells 9–11 until the pioneer study by Li et al. 8 introduced a novel approach for energy storage system the so-called semi-solid redox flow cell (SSFC) in which the electrode suspension is typically composed of electroactive materials and electronic conductive nanoparticles suspended in nonaqueous medium. 4 Of course, the surface chemistry of CBs, dispersing medium and dissolved salt (type and concentration) might influence the rheological and electrical behavior of CB suspensions. 4 It has been reported that the particle size of CBs impacts on the their rheological behavior where large particles (with relatively small specific surface area) form weaker percolated network consisting of less dense agglomerates with numerous branches and hence lower rheological parameters and electrical conductivity. 4,7 This behavior is a consequence of formation of percolated network composed of branches (paths) of aggregated CB resulting in 3D network. 6 Above a critical concentration, the so-called percolating threshold, a three-dimensional network is formed across the CB dispersion showing abrupt increase of the rheological parameters (viscosity, shear modulus) and electrical conductivity of dispersion. 4 The specific surface area and surface chemistry of CBs play pivotal role in determine the strength of binding forces 5 which determines the microstructure and hence the flow behavior of CB suspensions. 3 The van der Waals attraction forces drive the aggregates to binding into larger loosely agglomerates (10–100 μm). 1,2Ĭarbon black is initially formed from semi-spherical primary particles of nanometric (few hundred nm) size, which are fused to form aggregates (few μm size scale) in dispersions. Among various kinds of carbon nanomaterials, filamentous (one-dimensional) carbon nanofibers (CNFs) and carbon nanotubes (CNTs), platelet-like (two-dimensional) graphite and graphene, and most commonly semi-spherical (three-dimensional) carbon black (CB) have a unique place in many applications including printing inks, paints and importantly the formulations of electrodes for energy storage systems (batteries and supercapacitors). Introduction Carbon black (CB) is an important member of a large family of carbon nanomaterials that are allotropes of carbon and characterized by their exceptional chemical stability electrical and mechanical properties derive from their large diversity of structures that extend from the sp 2-hybridization of carbon atoms to the crystalline structure (varied degree of graphitization). This finding suggests hybrid dispersions as a promising precursor in the formulation of electrode suspensions for aqueous semi-solid redox flow cells. This hybrid dispersion is dominated by a cooperatively supporting network, which is wired by the flexible filamentous nanofibers so that it is able to recover the conductivity loss under flow conditions due to flow-induced breaking up of the conductive pathways of CB and presumably sustain a higher load of active materials. At this percolating threshold, replacing a trace amount of CB with equivalent carbon nanofibers (CNFs) produces hybrid dispersions with higher electrical conductivity and comparable rheological behavior to pure CB dispersions. In spite of its small particle size (30 nm), this type of CB forms a three-dimensional open network which is rheologically and electrically percolated at a relatively high threshold (2.0 wt%) with enhanced rheological and electrical properties. The aqueous dispersions of a special type of carbon black (CB) in 1 M lithium bis(trifluoromethanesulfonimide) electrolyte is mainly controlled by the affinity of the aqueous electrolyte towards the CB particles rather than the particle size.
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