High energy density redox flow device

1. An electrochemical cell comprising:

an anode;

a cathode; and

an ion-permeable membrane disposed between the anode and the cathode;

wherein at least one of the anode and the cathode includes an electrode composition comprising ion storage compound particles capable of taking up or releasing ions, and 0.5% to 10% by volume of electronically conductive particles disposed in a liquid electrolyte, the ion storage compound particles having a polydisperse size distribution and a particle packing fraction of at least 50 vol %.

2. The electrochemical cell of claim 1 , wherein the electronically conductive particles form a percolating network in the electrode composition.

3. The electrochemical cell of claim 1 , wherein the electrode composition is a semi-solid composition.

4. The electrochemical cell of claim 1 , wherein the liquid electrolyte is a non-aqueous liquid electrolyte.

5. The electrochemical cell of claim 1 , wherein the particle packing fraction is at least 70 vol %.

6. The electrochemical cell of claim 1 , wherein the ion storage compound particles have a polydisperse size distribution in which the finest particles present in at least 5 vol % of the total volume, is at least a factor of 5 smaller than the largest particles present in at least 5 vol % of the total volume.

7. The electrochemical cell of claim 1 , wherein the electronically conductive particles comprise a conductive inorganic compound selected from the group consisting of metals, metal carbides, metal nitrides, metal oxides, and allotropes of carbon including carbon black, graphitic carbon, carbon fibers, carbon microfibers, vapor-grown carbon fibers (VGCF), fullerenic carbons including “buckyballs”, carbon nanotubes (CNTs), multiwall carbon nanotubes (MWNTs), single wall carbon nanotubes (SWNTs), graphene sheets or aggregates of graphene sheets, and materials comprising fullerenic fragments and mixtures thereof.

8. The electrochemical cell of claim 1 , wherein the volume percentage of the ion storage compound is between 5% and 70%.

9. The electrochemical cell of claim 1 , wherein the electrode composition comprises 0.5% to 5% by volume of the electronically conductive particles.

10. An electrochemical cell comprising:

an anode;

a cathode; and

an ion-permeable membrane disposed between the anode and the cathode;

wherein at least one of the anode and the cathode includes a semi-solid electrode composition comprising ion storage compound particles capable of taking up or releasing ions, and 0.5% to 10% by volume of electronically conductive particles disposed in a liquid electrolyte, the ion storage compound particles having a polydisperse size distribution and a particle packing fraction of at least 50 vol %.

11. The electrochemical cell of claim 10 , wherein the particle packing fraction is at least 70 vol %.

12. The electrochemical cell of claim 10 , wherein the ion storage compound particles have a polydisperse size distribution in which the finest particles present in at least 5 vol % of the total volume, is at least a factor of 5 smaller than the largest particles present in at least 5 vol % of the total volume.

13. The electrochemical cell of claim 10 , wherein the volume percentage of the ion storage compound is between 5% and 70%.

14. The electrochemical cell of claim 10 , wherein the electronically conductive particles form a percolating network in the electrode composition.

15. The electrochemical cell of claim 10 , wherein the electronically conductive particles comprise a conductive inorganic compound selected from the group consisting of metals, metal carbides, metal nitrides, metal oxides, and allotropes of carbon including carbon black, graphitic carbon, carbon fibers, carbon microfibers, vapor-grown carbon fibers (VGCF), fullerenic carbons including “buckyballs”, carbon nanotubes (CNTs), multiwall carbon nanotubes (MWNTs), single wall carbon nanotubes (SWNTs), graphene sheets or aggregates of graphene sheets, and materials comprising fullerenic fragments and mixtures thereof.

16. An electrochemical cell comprising:

an anode;

a cathode; and

an ion-permeable membrane disposed between the anode and the cathode;

wherein at least one of the anode and the cathode includes an electrode composition comprising a suspension of ion storage compound particles capable of taking up or releasing ions, and 0.5% to 10% by volume of electronically conductive particles disposed in a liquid electrolyte, the ion storage compound particles having a polydisperse size distribution and a particle packing fraction of at least 50 vol %.

17. The electrochemical cell of claim 16 , wherein the ion storage compound particles have a particle packing fraction of at least 70 vol %.

18. The electrochemical cell of claim 16 , wherein the electrode composition comprises a semi-solid composition.

19. The electrochemical cell of claim 16 , wherein the liquid electrolyte is a non-aqueous liquid electrolyte.

20. The electrochemical cell of claim 16 , wherein the electronically conductive particles form a percolating network in the electrode composition.

21. The electrochemical cell of claim 16 , wherein the electronically conductive particles comprise a conductive inorganic compound selected from the group consisting of metals, metal carbides, metal nitrides, metal oxides, and allotropes of carbon including carbon black, graphitic carbon, carbon fibers, carbon microfibers, vapor-grown carbon fibers (VGCF), fullerenic carbons including “buckyballs”, carbon nanotubes (CNTs), multiwall carbon nanotubes (MWNTs), single wall carbon nanotubes (SWNTs), graphene sheets or aggregates of graphene sheets, and materials comprising fullerenic fragments and mixtures thereof.

22. The electrochemical cell of claim 16 , wherein the ion storage compound particles have a polydisperse size distribution in which the finest particles present in at least 5 vol % of the total volume, is at least a factor of 5 smaller than the largest particles present in at least 5 vol % of the total volume.