Apparatuses and processes for forming a semi-solid electrode having high active solids loading and electrochemical cells including the same
Embodiments described herein relate generally to apparatuses and processes for forming semi-solid electrodes having high active solids loading by removing excess electrolyte. In some embodiments, the semi-solid electrode material can be formed by mixing an active material and, optionally, a conductive material in a liquid electrolyte to form a suspension. In some embodiments, the semi-solid electrode material can be disposed onto a current collector to form an intermediate electrode. In some embodiments, the semi-solid electrode material can have a first composition in which the ratio of electrolyte to active material is between about 10:1 and about 1:1. In some embodiments, a method for converting the semi-solid electrode material from the first composition into the second composition includes removing a portion of the electrolyte from the semi-solid electrode material. In some embodiments, the method includes mechanically compressing the intermediate electrode to remove the portion of electrolyte from the semi-solid electrode material.
1. A method of forming a densified semi-solid electrode, the method comprising:
mixing an active material and a conductive material with a liquid electrolyte to form a semi-solid electrode material;
disposing the semi-solid electrode material onto a current collector;
disposing a semi-permeable membrane onto an exposed surface of the semi-solid electrode material; and
compressing the semi-solid electrode material between the current collector and the semi-permeable membrane to extract a portion of the liquid electrolyte and form the densified semi-solid electrode,
wherein the densified semi-solid electrode includes between about 60% and about 85% by volume of an active material.
2. The method of claim 1 , wherein the semi-permeable membrane is configured to absorb the portion of the liquid electrolyte extracted during compressing.
3. The method of claim 1 , further comprising:
disposing an absorptive material onto an exposed surface of the semi-permeable membrane, the absorptive material configured to absorb the portion of the liquid electrolyte extracted during compressing.
4. The method of claim 1 , wherein mechanically compressing the semi-solid electrode material includes compressing the semi-solid material between a die and a base.
5. The method of claim 1 , wherein the compressed semi-solid electrode material includes greater than about 70 wt % of the active material.
6. The method of claim 1 , wherein the semi-solid electrode material after mixing has a first composition in which the liquid electrolyte is between about 50 wt % and about 80 wt % of the semi-solid electrode material, and
wherein the semi-solid electrode material after compressing has a second composition in which the liquid electrolyte is between about 10 wt % and about 45 wt % of the semi-solid electrode material.
7. The method of claim 1 , wherein the semi-solid electrode material after mixing has a first ratio of liquid electrolyte to active material of between about 10:1 and about 1:1; and
wherein the semi-solid electrode material after compressing has a second ratio of liquid electrolyte to active material of between about 5:1 and about 1:3.
8. The method of claim 1 , wherein the semi-solid electrode material after mixing has a first active material molarity of between about 5M and about 15M; and
wherein the semi-solid electrode material after compressing has a second active material molarity of between about 16M and about 24M.
9. The method of claim 1 , wherein the semi-solid electrode material after mixing has a first energy density of between about 3 mAh/g and about 5 mAh/g; and
wherein the semi-solid electrode material after compressing has a second energy density of between about 6 mAh/g and about 14 mAh/g.
10. The method of claim 1 , wherein the conductive material includes conductive particles.
11. The method of claim 1 , wherein the densified semi-solid electrode is a first electrode and the current collector is a first current collector, further comprising:
removing the semi-permeable membrane from the first electrode;
placing a second electrode on a second current collector;
placing a separator on the second electrode, such that a first surface of the separator contacts the second electrode and a second surface of the separator is exposed, the second surface opposite the first surface;
placing droplets of electrolyte on the second surface of the separator; and
placing the first electrode on the separator to form an electrochemical cell.
12. A method, comprising:
mixing an active material and a conductive material with a liquid electrolyte to form a semi-solid electrode material having a first volume;
interposing the semi-solid electrode material between a current collector and a semi-permeable membrane; and
applying a compressive force to the semi-solid electrode material via a roller such that the semi-solid electrode material has a second volume less than the first volume.
13. The method of claim 12 , further comprising:
exposing the semi-solid electrode material to an absorptive material, such that a portion of the liquid electrolyte migrates from the semi-solid electrode material to the absorptive material.
14. The method of claim 13 , wherein the absorptive material is conveyed by one or more rollers.
15. The method of claim 14 , wherein a flat portion of the absorptive material is in contact with the semi-solid electrode material.
16. The method of claim 12 , wherein the second volume is between about 50% and about 95% of the first volume.
17. The method of claim 16 , wherein the second volume is between about 50% and about 80% of the first volume.
18. The method of claim 16 , wherein the second volume is between about 70% and about 95% of the first volume.
19. A method, comprising:
mixing an active material and a conductive material with a liquid electrolyte to form a semi-solid electrode material having a first thickness;
interposing the semi-solid electrode material between a current collector and a semi-permeable membrane; and
applying a compressive force to the semi-solid electrode material via a roller such that the semi-solid electrode material has a second thickness less than the first thickness.
20. The method of claim 19 , wherein the first thickness is between about 100 μm and about 2,000 μm.
21. The method of claim 19 , wherein the second thickness is between about 5 μm and about 50 μm.
22. The method of claim 19 , wherein mechanically compressing is accomplished by mechanically compressing the semi-solid electrode material between a base and a die of a mechanical press.
23. A method, comprising:
mixing an active material and a conductive material with a liquid electrolyte to form a first semi-solid electrode material having a first composition comprising between about 50 wt % and about 80 wt % of the liquid electrolyte;
interposing the first semi-solid electrode material between a current collector and a semi-permeable membrane; and
mechanically compressing the first semi-solid electrode material to form a second semi-solid electrode material having a second composition comprising between about 10 wt % and about 45 wt % of the liquid electrolyte.
24. A method, comprising:
mixing an active material and a conductive material with a liquid electrolyte to form a first semi-solid electrode material having a first density;
interposing the first semi-solid electrode material between a current collector and a semi-permeable membrane; and
mechanically compressing the first semi-solid electrode material to form a second semi-solid electrode material having a second density greater than the first density, the second semi-solid electrode material including between about 60% and about 85% by volume of the active material.
25. The method of claim 24 , wherein the first density is less than about 2 g/cm 3 .
26. The method of claim 25 , wherein the second density is between about 2.1 g/cm 3 and about 4 g/cm 3 .
27. The method of claim 26 , wherein an energy density of the second semi-solid electrode material is greater than about 7 mAh/g.
28. The method of claim 27 , wherein the energy density of the second semi-solid electrode material is greater than about 8 mAh/g.
29. The method of claim 28 , wherein the energy density of the second semi-solid electrode material is greater than about 9 mAh/g.
30. The method of claim 29 , wherein the energy density of the second semi-solid electrode material is greater than about 10 mAh/g.