Fig. 1

The schematic of preparation of PPy/C-PDA coating[20]"

Fig. 2

Preparation schematic diagram of PPy-Ti4O7 coating[21]"

Fig. 3

(a) Fabrication procedures of thin flexible BPs; (b) Cyclic performances of small flow cells with BPs with different PTFE contents[23]"

Table 1

Comparison of extrusion molding and compression molding processes[28-29]"

Fig. 4

Schematic of the major and minor conductive fillers and the fabrication process of the carbon-based polymer composite bipolar plates [32]"

Fig. 5

(a) Schematic diagram of microstructure of the BPs and (b) voltage ef?ciency; (c) Coulombic ef?ciency (d) Energy ef?ciency at various current densities[33]"

Fig. 6

“Soft layer method” for exposing carbon fibers on composite bipolar plates[35]"

Fig. 7

Schematic of PVDF-carbon felt composite bipolar plate fabrication[37]"

Fig. 8

(a) Schematic diagram of the composite BP modified with C–CNF and (b) discharge capacity retention and (c) EE of the cells with different BPs in cycling test[38]"

Fig. 9

(a) Fabrication of the PANI-embedded carbon composite bipolar plate; (b) SEM images of the cross-section of the fabricated specimens[39]"

Fig. 10

(a) The fabrication process of the laminated bipolar plate and (b) schematic diagram of electrically conductive pathways of the bipolar plates[40]"

Table 2

Brief description of carbon/polymer composite materials as BP for the VFB reported in the literature"

Fig. 11

Conventional flow channel designs: (a) parallel (b) serpentine (c) interdigitated[15]"

Fig. 12

The reduced molar concentration of V2+ with increased channel size[45]"

Fig. 13

Schematic of flow channels engraved on graphite bipolar pate of the type (a) single serpentine, (b) interdigitated, (c) multiple serpentine and (d) interdigitated with pins in the inlet flow channels[46]"

Fig. 14

(a) Sketch of the novel electrode-bipolar plate assembly and (b) typical charge/discharge curves of the single cell with conventional electrode-bipolar plate setup and novel electrode-bipolar plate assembly[47]"

Table 3

Comparison of three conventional bipolar plates and electrode-bipolar plate integrated structures[29, 50-51]"

Fig. 13

Schematics of the fabrication of IS_G: (a) plasma treatment of the GF; (b) formation of the glucose layer; (c) compression molding and (d) removal of glucose[49]"