High energy density redox flow device
Redox flow devices are described including a positive electrode current collector, a negative electrode current collector, and an ion-permeable membrane separating said positive and negative current collectors, positioned and arranged to define a positive electroactive zone and a negative electroactive zone; wherein at least one of said positive and negative electroactive zone comprises a flowable semi-solid composition comprising ion storage compound particles capable of taking up or releasing said ions during operation of the cell, and 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.
1. An energy storage system 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 composition comprising ion storage compound particles capable of taking up or releasing said ions during operation of the cell, and
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.
2. The energy storage system of claim 1 , wherein the finest particles present in at least 5 vol % of the total volume, is at least a factor of 7 smaller than the largest particles present in at least 5 vol % of the total volume.
3. The energy storage system of claim 1 , wherein the finest particles present in at least 5 vol % of the total volume, is at least a factor of 10 smaller than the largest particles present in at least 5 vol % of the total volume.
4. The energy storage system of claim 1 , wherein the ion storage compound particles have a bidisperse size distribution in which the two maxima differ in size by at least a factor of 5.
5. The energy storage system of claim 4 , the particle size of the maxima for the larger particles is at least 1 micrometer.
6. The energy storage system of claim 1 , wherein the particles have morphology that is at least equiaxed.
7. The energy storage system of claim 1 , wherein the particle packing fraction is at least 50 vol %.
8. The energy storage system of claim 1 , wherein the particle packing fraction is at least 55 vol %.
9. The energy storage system of claim 1 , wherein the particle packing fraction is at least 60 vol %.
10. The energy storage system of claim 1 , wherein the particle packing fraction is at least, at least 70 vol %.
11. The energy storage system of claim 1 , further comprising a redox mediator.
12. The energy storage system of claim 11 , wherein the redox mediator is soluble in the semi-solid composition and comprises multiple oxidation states.
13. The energy storage system of claim 11 , wherein the redox mediator comprises a redox metal ion selected from iron, vanadium, chromium and zinc and mixtures thereof.
14. The energy storage system of claim 1 , wherein the semi-solid composition further comprises an electronically conductive material.
15. The energy storage system of claim 14 , wherein the electronically conductive material comprises a conductive inorganic compound.
16. The energy storage system of claim 14 , wherein the electronically conductive material forms a percolative conductive pathway.
17. The energy storage system of claim 14 , wherein the electronically conductive material comprises an electronically conductive polymer.
18. The energy storage system of claim 14 , wherein the electronically conductive material coats the ion storage compound particles.
19. The energy storage system of claim 1 , wherein the one or both of the positive and negative current collector is coated with an electronically conductive material.
20. The energy storage system of claim 1 , further comprising:
at least one tank external to the energy storage system for delivering the semi-solid composition into the electroactive zone.
21. The energy storage system of claim 1 ,
wherein one of said positive and negative electroactive zone comprises a semi-solid composition comprising ion storage compound particles capable of taking up or releasing said ions during operation of the cell; and
wherein one of said positive and negative electroactive zone comprises an aqueous redox solution capable of taking up or releasing said ions during operation of the cell and an electronically conductive material.
22. The energy storage system of claim 21 , wherein the electronically conductive material forms a percolative conductive pathway.
23. A system comprising:
(a) an energy storage system 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 composition comprising ion storage compound particles capable of taking up or releasing said ions during operation of the cell, and
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; and
(b) at least one container external to the energy storage system for delivering the semi-solid composition into the electroactive zone.
24. An electrochemical cell, comprising:
a semi-solid electrode including a suspension of ion storage compound particles in a non-aqueous liquid electrolyte, the ion storage compound particles capable of taking up or releasing said ions during operation of the cell, and
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.
25. The electrochemical cell of claim 24 , wherein the ion storage compound particles in the semi-solid electrode is at least 10% by mass.
26. The electrochemical cell of claim 25 , wherein the ion storage compound particles in the semi-solid electrode is at least 25% by mass.
27. The electrochemical cell of claim 24 , wherein the volume percentage of the ion storage compound particles is between 5% and 70%.
28. The electrochemical cell of claim 24 , wherein the finest particles present in at least 5 vol % of the total volume, is at least a factor of 7 smaller than the largest particles present in at least 5 vol % of the total volume.
29. The electrochemical cell of claim 24 , wherein the finest particles present in at least 5 vol % of the total volume, is at least a factor of 10 smaller than the largest particles present in at least 5 vol % of the total volume.
30. The electrochemical cell of claim 24 , wherein the ion storage compound particles have a bidisperse size distribution in which the two maxima differ in size by at least a factor of 5.
31. The electrochemical cell of claim 24 , wherein the semi-solid electrode further comprises an electronically conductive material.
32. The electrochemical cell of claim 31 , wherein the electronically conductive material forms a percolative conductive pathway.
33. The electrochemical cell of claim 24 , wherein the volume percentage of the ion storage compound particles is between 5% and 70%, and the volume percentage of the total solids including the electronically conductive material is between 10% and 75%.