DRY ELECTRODE MANUFACTURE BY TEMPERATURE ACTIVATION METHOD
A method of manufacturing a free-standing electrode film includes preparing a mixture including an electrode active material, a conductive material, and a binder, heating the mixture to 70° C. or higher, subjecting the mixture to a shear force, and, after the mixture has been subjected to the shear force, pressing the mixture into a free-standing film. The method may further include adding a solvent to the mixture. A resulting free-standing electrode film may include an amount of binder less than 4% by weight.
This application relates to and claims the benefit of U.S. Provisional Application No. 62/857,144, filed Jun. 4, 2019 and entitled “DRY ELECTRODE MANUFACTURE BY TEMPERATURE ACTIVATION METHOD,” the entire disclosure of which is hereby incorporated by reference.
STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENTNot Applicable
BACKGROUND 1. Technical FieldThe present disclosure relates generally to manufacturing electrodes for energy storage devices such as batteries and, more particularly, to the manufacture of a free-standing electrode film by a dry process.
2. Related ArtAs demand for inexpensive energy storage devices increases, various methods have been proposed for manufacturing electrodes. Among these, there exist so-called “dry” processes by which a free-standing electrode film may be manufactured while avoiding the expense and drying time associated with the solvents and aqueous solutions that are typically used in slurry coating and extrusion processes. In order to produce higher quality electrodes by such a dry process that may result in energy storage devices having higher energy density, the amount of binder mixed with the active material should be minimized within a range that still allows for an electrode film to be reliably produced without excessive breakage. To this end, the binder may be activated to improve its adhesion strength by the addition of a highly vaporizable solvent as described in the present inventor's own U.S. Pat. No. 10,069,131, entitled “Electrode for Energy Storage Devices and Method of Making Same,” the entirety of the disclosure of which is wholly incorporated by reference herein. However, further reduction in the amount of binder needed is desirable, especially in the case of producing electrodes for batteries, where maximizing the active material loading is essential to maximizing the energy density of the battery.
BRIEF SUMMARYThe present disclosure contemplates various methods for overcoming the drawbacks accompanying the related art. One aspect of the embodiments of the present disclosure is a method of manufacturing a free-standing electrode film. The method may include preparing a mixture including an electrode active material, a conductive material, and a binder, heating the mixture to 70° C. or higher, after said heating, subjecting the mixture to a shear force, and, after the mixture has been subjected to the shear force, pressing the mixture into a free-standing film.
The method may further include adding a solvent to the mixture before the mixture is subjected to the shear force. Adding the solvent to the mixture may be performed after the heating.
The method may further include adding a solvent to the mixture while the mixture is being subjected to the shear force.
Subjecting the mixture to the shear force may include mixing the mixture in a high shear mixer, such as a kitchen or industrial blender (e.g. a Waring® blender), a cyclomixer, a jet mill, a bead mill, a planetary mixer, a paddle mixer, etc.
The pressing may include applying a roller press to the mixture.
The solvent may have a boiling point of less than 130° C. or less than 100° C. The solvent may include one or more chemicals selected from the group consisting of: a hydrocarbon, an acetate ester, an alcohol, a glycol, ethanol, methanol, isopropanol, acetone, diethyl carbonate, and dimethyl carbonate.
Another aspect of the embodiments of the present disclosure is a method of manufacturing a free-standing electrode film. The method may include preparing a mixture including an electrode active material, a conductive material, and a binder, adding a solvent to the mixture, after the solvent has been added to the mixture, subjecting the mixture to a shear force, after the mixture has been subjected to the shear force, heating the mixture to 70° C. or higher, and, after heating, pressing the mixture into a free-standing film.
Subjecting the mixture to a shear force may include mixing the mixture in a high shear mixer, such as a kitchen or industrial blender (e.g. a Waring® blender), a cyclomixer, a jet mill, a bead mill, a planetary mixer, a paddle mixer, etc.
The pressing may include applying a roller press to the mixture.
The solvent may have a boiling point of less than 130° C. or less than 100° C. The solvent may include one or more chemicals selected from the group consisting of: a hydrocarbon, an acetate ester, an alcohol, a glycol, ethanol, methanol, isopropanol, acetone, diethyl carbonate, and dimethyl carbonate.
Another aspect of the embodiments of the present disclosure is a method of manufacturing an electrode. The method may include performing any of the above methods of manufacturing a free-standing electrode film and laminating the resulting free-standing film on a current collector.
Another aspect of the embodiments of the present disclosure is a free-standing electrode film including an electrode active material, a conductive material, and one or more binders, the one or more binders totaling around 4% by weight of the free-standing electrode film, and in some cases less than 4%.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
The above and other features and advantages of the various embodiments disclosed herein will be better understood with respect to the following description and drawings, in which like numbers refer to like parts throughout, and in which:
The present disclosure encompasses various embodiments of methods for manufacturing a free-standing electrode film or an electrode produced therefrom. The detailed description set forth below in connection with the appended drawings is intended as a description of several currently contemplated embodiments, and is not intended to represent the only form in which the disclosed invention may be developed or utilized. The description sets forth the functions and features in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions may be accomplished by different embodiments that are also intended to be encompassed within the scope of the present disclosure. It is further understood that the use of relational terms such as first and second and the like are used solely to distinguish one from another entity without necessarily requiring or implying any actual such relationship or order between such entities.
The operational flow of
The operational flow of
With the binder having been activated by one or both of the activation steps 120, 130, the operational flow of
After the mixture has been subjected to the shear force, the operational flow of
As noted above, the solvent activation step 130 may be completely omitted, with the binder still being adequately activated by the temperature activation step 120. In such case, step 140 of subjecting the mixture to a shear force (e.g. using a blender of jet mill) may follow the temperature activation step 120. In the case of a “dual activation” process including both the temperature activation step 120 and the solvent activation step 130, the shear force of step 140 may be applied after the binder has been activated by one or both of the activation steps 120, 130 as noted above. For example, steps 120, 130, and 140 may be performed one after the other in the order shown in
The experimental results described in relation to
As can be understood from the above Table 1 and
According to the disclosed methods, a free-standing electrode film can be produced comprising an electrode active material, a conductive material, and one or more binders totaling less than 4% by weight of the free-standing electrode film. Such a free-standing electrode film with reduced quantity of binder can be laminated to a current collector to produce an electrode for use in batteries, ultracapacitors, lithium ion capacitors (LIC), fuel cells, and other energy storage devices having higher energy density and lower manufacturing costs.
The above description is given by way of example, and not limitation. Given the above disclosure, one skilled in the art could devise variations that are within the scope and spirit of the invention disclosed herein. Further, the various features of the embodiments disclosed herein can be used alone, or in varying combinations with each other and are not intended to be limited to the specific combination described herein. Thus, the scope of the claims is not to be limited by the illustrated embodiments.
Claims
1-20. (canceled)
21. A free-standing electrode film comprising:
- an electrode active material; and
- one or more binders totaling less than 4 percent by weight of the free-standing electrode film, the electrode active material having an exposed surface that is unblocked by the one or more binders.
22. The free-standing electrode film of claim 21, wherein the one or more binders comprise polytetrafluoroethylene (PTFE).
23. The free-standing electrode film of claim 21, wherein the one or more binders total 3.5 percent by weight of the free-standing electrode film.
24. The free-standing electrode film of claim 21, wherein the electrode active material is in an amount 82-99 percent by weight of the free-standing electrode film.
25. The free-standing electrode film of claim 21, wherein the electrode active material comprises one or more materials selected from the group consisting of activated carbon, graphite, hard carbon, and metal oxide.
26. The free-standing electrode film of claim 21, further comprising a conductive material.
27. The free-standing electrode film of claim 26, wherein the conductive material is in an amount less than 10 percent by weight of the free-standing electrode film.
28. The free-standing electrode film of claim 27, wherein the conductive material is 3.5 percent by weight of the free-standing electrode film.
29. The free-standing electrode film of claim 21, further comprising solvent in an amount less than 3 percent by weight of the free-standing electrode film.
30. The free-standing electrode film of claim 29, wherein the solvent has a boiling point of less than 130° C.
31. The free-standing electrode film of claim 29, wherein the solvent includes one or more chemicals selected from the group consisting of a hydrocarbon, an acetate ester, an alcohol, a glycol, ethanol, methanol, isopropanol, acetone, diethyl carbonate, and dimethyl carbonate.
32. An electrode for use in an energy storage device, the electrode comprising:
- a current collector; and
- an electrode film laminated on the current collector, the electrode film comprising an electrode active material and one or more binders totaling less than 4 percent by weight of the electrode film, the electrode active material having an exposed surface that is unblocked by the one or more binders.
33. The electrode of claim 32, wherein the one or more binders comprise polytetrafluoroethylene (PTFE).
34. The electrode of claim 32, wherein the one or more binders total 3.5 percent by weight of the electrode film.
35. The electrode of claim 32, wherein the electrode active material is in an amount 82-99 percent by weight of the electrode film.
36. The electrode of claim 32, wherein the electrode active material comprises one or more materials selected from the group consisting of activated carbon, graphite, hard carbon, and metal oxide.
37. The electrode of claim 32, wherein the electrode film further comprises a conductive material.
38. The electrode of claim 37, wherein the conductive material is in an amount less than 10 percent by weight of the electrode film.
39. The electrode of claim 38, wherein the conductive material is 3.5 percent by weight of the electrode film.
40. The electrode of claim 32, wherein the electrode film further comprises solvent in an amount less than 3 percent by weight of the electrode film.
Type: Application
Filed: Feb 16, 2023
Publication Date: Jun 22, 2023
Inventors: Linda Zhong (Sacramento, CA), Kathleen Qiu (Sacramento, CA), Martin Zea (Sacramento, CA), Erika Shaw (Sacramento, CA)
Application Number: 18/110,627