High energy density redox flow device
Redox flow devices are described in which at least one of the positive electrode or negative electrode-active materials is a semi-solid or is a condensed ion-storing electroactive material, and in which at least one of the electrode-active materials is transported to and from an assembly at which the electrochemical reaction occurs, producing electrical energy. The electronic conductivity of the semi-solid is increased by the addition of conductive particles to suspensions and/or via the surface modification of the solid in semi-solids (e.g., by coating the solid with a more electron conductive coating material to increase the power of the device). High energy density and high power redox flow devices are disclosed. The redox flow devices described herein can also include one or more inventive design features. In addition, inventive chemistries for use in redox flow devices are also described.
1. An energy storage device, comprising:
a positive electrode current collector, a negative electrode current collector, and an ion-permeable membrane separating the positive current collector and the negative current collector;
a positive electrode disposed between the positive electrode current collector and the ion-permeable membrane; the positive electrode current collector and the ion-permeable membrane defining a positive electroactive zone accommodating the positive electrode; and
a negative electrode disposed between the negative electrode current collector and the ion-permeable membrane; the negative electrode current collector and the ion-permeable membrane defining a negative electroactive zone accommodating the negative electrode;
wherein at least one of the positive electrode and the negative electrode includes a semi-solid or condensed liquid ion-storing redox composition, the semi-solid or condensed liquid ion-storing redox composition including a conductive additive selected from metal carbides, metal nitrides, carbon black, graphitic carbon powder, carbon fibers, carbon microfibers, vapor-grown carbon fibers (VGCF), fullerenes, carbon nanotubes (CNTs), multiwall carbon nanotubes (MWNTs), single wall carbon nanotubes (SWNTs), graphene sheets, and materials comprising fullerenic fragments that are not predominantly a closed shell or tube of the graphene sheet, and mixtures thereof, and
wherein the semi-solid or condensed liquid ion-storing redox composition is capable of taking up or releasing ions, remains substantially insoluble during operation of the cell, and has a thickness of about 250 μm to about 800 μm.
2. The energy storage device of claim 1 , wherein the semi-solid or condensed liquid ion-storing redox composition forms a continuously electronically conductive network percolative pathway to the negative current collector and/or the positive current collector.
3. The energy storage device of claim 1 , wherein the positive electrode and the negative electrode include a semi-solid or condensed liquid ion-storing redox composition.
4. The energy storage device of claim 1 , wherein one of the positive electrode and the negative electrode includes a semi-solid or condensed liquid ion-storing redox composition and the other electrode is a solid electrode.
5. The energy storage device of claim 1 , wherein the ion storage compound stores at least one of Li, Na or H.
6. The energy storage device of claim 1 , wherein the conductive additive forms a percolative conductive continuously electronically conductive network in the semi-solid or condensed liquid ion-storing redox composition.
7. The energy storage device of claim 1 , wherein the semi-solid or condensed liquid ion-storing redox composition is free of added binder.
8. An energy storage device, comprising:
a positive electrode current collector, a negative electrode current collector, and an ion-permeable membrane separating the positive current collector and the negative current collector;
a positive electrode disposed between the positive electrode current collector and the ion-permeable membrane; the positive electrode current collector and the ion-permeable membrane defining a positive electroactive zone accommodating the positive electrode; and
a negative electrode disposed between the negative electrode current collector and the ion-permeable membrane; the negative electrode current collector and the ion-permeable membrane defining a negative electroactive zone accommodating the negative electrode;
wherein at least one of the positive electrode and the negative electrode includes a semi-solid or condensed liquid ion-storing redox composition, the semi-solid or condensed liquid ion-storing redox composition including a conductive additive,
wherein the volume percentage of the ion-storing solid phase is between 5% and 70%, and the volume percentage of the total solids including the conductive additive is between 10% and 75%, and
wherein the semi-solid or condensed liquid ion-storing redox composition is capable of taking up or releasing ions, remains substantially insoluble during operation of the cell, and has a thickness of about 250 μm to about 800 μm.
9. The energy storage device of claim 8 , wherein the semi-solid or condensed liquid ion-storing redox composition forms a continuously electronically conductive network percolative pathway to the negative current collector and/or the positive current collector.
10. The energy storage device of claim 8 , wherein the positive electrode and the negative electrode include a semi-solid or condensed liquid ion-storing redox composition.
11. The energy storage device of claim 8 , wherein one of the positive electrode and the negative electrode includes a semi-solid or condensed liquid ion-storing redox composition and the other electrode is a solid electrode.
12. The energy storage device of claim 8 , wherein the ion storage compound stores at least one of Li, Na or H.
13. The energy storage device of claim 8 , wherein the conductive additive forms a percolative conductive continuously electronically conductive network in the semi-solid or condensed liquid ion-storing redox composition.
14. The energy storage device of claim 8 , wherein the semi-solid or condensed liquid ion-storing redox composition is free of added binder.