DESC:FORM 2

THE PATENTS ACT, 1970

(39 of 1970)

&

THE PATENT RULES, 2003

COMPLETE SPECIFICATION

[See Section 10 and Rule 13]

TITLE:

“A METHOD FOR MANUFACTURING SEMI-SOLID ELECTRODE”

APPLICANT:

E-TRNL ENERGY PRIVATE LIMITED
a company incorporated under Indian Companies Act, 2013,
having address at
Plot No. 08, SY No. 75, Sadaramangala lndustrial Area,
M.D. Pura White Field, Mahadevapura, Bengaluru,
Bengaluru Urban, Pin Code – 560048, Karnataka, India

PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the invention and the manner in which it is to be performed:
FIELD OF THE INVENTION
The present invention relates to the field of electrode fabrication. More particularly, the present invention relates to a method of manufacturing a homogeneous, semi-solid material for electrode fabrication.

BACKGROUND OF THE INVENTION
Energy storage cells refer to devices that store and release electrical energy. Energy storage devices are made up of electrodes, electrolyte and separator. Electrodes are the positive and the negative terminals where the chemical or electrical reactions take place. Electrolyte is a substance that allows ions to move between the positive and the negative electrodes. Separator is a component that keeps the positive and negative electrodes physically apart while allowing the flow of ions to prevent short circuits. The electrodes are porous layers coated on metal foils that act as substrates as well as current collectors. Both the electrodes consist of an active material, conductive additives and a binder. The active material is a substance that undergoes a reversible electrochemical reaction during the process of generating electrical energy. The conductive additives are materials added to enhance the electrical conductivity of another substance by forming a percolation network that allows flow of current through the electrode. The binder holds the electrode materials together and provide mechanical strength.
For the cells to work at their optimal performance, the electrode component needs to be evenly spread and possess consistent properties. In order to achieve the uniform distribution of electrode components, the slurry mixing mechanism is generally utilized. The slurry mixing mechanism involves the steps of adding conductive additives and active materials in the binder that dissolves in a suitable solvent. The slurry is then applied to the metal foil using tape-casting method, followed by a drying process to evaporate the solvent. These electrodes are henceforth referred to as slurry coated electrodes. However, the slurry mixing mechanism requires significant amount of solvents that are ecologically and biologically harmful. Along with that, the slurry mixing mechanism takes a significant amount of heat to evaporate the solvent and dry the electrodes that results into high energy cost. Also, the drying process requires large drying chambers that increases the capital investment on machinery and equipment which requires large floor space for manufacturing. The evaporated solvent been environmentally harmful, needs to be capture and recovered, hence adding to the energy and monetary cost. The slurry mixing and casting process also require dehumidification, which also drives up the financial and energy cost of the product along with the carbon footprint.
US10446826B2 discloses a method for making a lithium ionic energy storage element, the method includes the steps of: (a) mixing a lithium ion donor, a positive electrode frame active substance and a binder with a predetermined weight ratio to form a mixture, and adding the mixture into a dispersant to form a positive electrode active substance, wherein the lithium ion donor includes lithium peroxide, lithium oxide or a combination thereof; (b) coating the positive electrode active substance on an aluminum foil to form a film, and baking the film to form a positive electrode; and (c) forming a lithium ionic energy storage element by assembling the positive electrode, a negative electrode having a negative electrode active substance and a porous separate strip interposed between the positive electrode and the negative electrode, and filling an electrolyte into the porous separate strip. However, the method involves multiple steps that increases manufacturing costs and complexity. In addition, achieving uniform coating on aluminum affects the overall stability and performance of the electrode.
US4105815A discloses a thin flat Leclanche cells and batteries comprising cathodes in the form of slurries of manganese dioxide and carbon in an electrolyte solution containing from 23 to 30 percent of water based on the weight of the slurry. The anodes are of conventional dry patch construction, or take the form of slurries of zinc powder in an electrolyte solution containing from 25 to 40 percent of water based on the weight of the anode slurry. However, the thin flat Leclanche cells and batteries take a significant amount of heat to evaporate the solvent and dry the electrodes that results into high energy cost.
Therefore, due to above mentioned drawbacks, there is a requirement of a method for manufacturing the semi-solid electrodes by uniformly mixing the electrode components.

OBJECT OF THE INVENTION
The main object of the present invention is to provide a method for manufacturing semi-solid electrode that requires less energy consumption in comparison to conventional method for slurry coated electrode.
Yet another object of the present invention is to provide a method for manufacturing semi-solid electrode that required minimal machinery and equipment which minimizes the capital investment as well as the floor spacing for manufacturing.
Yet another object of the present invention is to provide a method for manufacturing semi-solid electrode that takes less time in mixing the electrode components.
Still another objective of the present invention is to provide a method for manufacturing semi-solid electrode that uniformly mix the electrode components.

SUMMARY OF THE INVENTION
The present invention relates to a method for manufacturing semi-solid electrode by mixing electrode components with homogeneous properties that are used in energy storage devices.
In an embodiment, the present invention provides a method for manufacturing semi-solid electrode comprising the steps of: (a) mixing of at least one active material, at least one binding agent and a plurality of conductive components via a dry mixing technique to obtain a dry mixed powder; (b) adding a solvent to the dry mixed powder obtained in step (a) to achieve a semi-solid electrode structure; and (c) roll-pressing the semi-solid electrode structure obtained in step (b) multiple times to achieve better homogeneity.
The above objects and advantages of the present invention will become apparent from the hereinafter set forth brief description of the drawings, detailed description of the invention, and claims appended herewith.

BRIEF DESCRIPTION OF THE DRAWINGS
An understanding of the method for manufacturing semi-solid electrode thereof of the present invention may be obtained by reference to the following drawing:
Figure 1 is a flow diagram of a conventional method of manufacturing slurry electrode.
Figure 2 is a flow diagram of a conventional method of making dry mix electrode.
Figure 3 is a block diagram of a method for manufacturing semi-solid electrode according to an embodiment of the present invention.
Figure 4 is a flow diagram of a method for manufacturing semi-solid electrode according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION
The present invention will now be described hereinafter with reference to the accompanying drawings in which a preferred embodiment of the invention is shown. This invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiment set forth herein. Rather, the embodiment is provided so that this disclosure will be thorough, and will fully convey the scope of the invention to those skilled in the art.
Many aspects of the invention can be better understood with references made to the drawings below. The components in the drawings are not necessarily drawn to scale. Instead, emphasis is placed upon clearly illustrating the components of the present invention. Moreover, like reference numerals designate corresponding parts through the several views in the drawings. Before explaining at least one embodiment of the invention, it is to be understood that the embodiments of the invention are not limited in their application to the details of construction and to the arrangement of the components set forth in the following description or illustrated in the drawings. The embodiments of the invention are capable of being practiced and carried out in various ways. In addition, the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
The present invention relates to a method for manufacturing semi-solid electrode that are used in energy storage devices to enhance the efficiency and performance of the electrodes.
In an embodiment, the present invention provides method for manufacturing semi-solid electrode comprising the steps of: (a) mixing of at least one active material, at least one binding agents and a plurality of conductive components via a dry mixing technique to obtain a dry mixed powder; (b) adding a solvent to the dry mixed powder obtained in step (a) to achieve a semi-solid electrode structure; and (c) roll-pressing the semi-solid electrode structure obtained in step (b) multiple times to achieve better homogeneity. The solvent in the step (b) is preferably aqueous or non-aqueous. The semi-solid electrode is preferably in the form of a clay or a dough.
Figure 1 is a flow diagram of a conventional method of manufacturing slurry coated electrode. The conventional method (100) of manufacturing slurry coated electrode including the steps of (a) dissolving a binding substance (i.e. binder powder (3) in a suitable solvent to obtain a binder solution (8); (b) adding a conductive additive (2) and an active material (1) to the binder solution (8); (c) mixing the conductive additive (2) and an active material (1) and the binder solution to create a homogeneous slurry (6); (d) applying the homogeneous slurry (6) onto a metal foil through a coating machine to achieve a uniform coating; (e) drying the coated electrode (7) to remove solvents from the slurry to leave a solid layer of the active material (1), the conductive additive and the binding substance on the metal foil.
However, in the conventional method, the homogeneous slurry (6) mixing requires significant amount of solvents, which are often ecologically and biologically harmful. Also, it takes a significant amount of heat to evaporate the solvent and dry the electrodes, thus increasing the energy cost and the carbon footprint of the process. The drying process requires large drying chambers thus increasing the capital investment on machinery and equipment. Moreover, the large size of the machinery and equipment also results in large floor space required for manufacturing. Depending on the solvents, the homogeneous slurry (6) mixing and casting process also require dehumidification, which also drives up the financial and energy cost of the product along with its carbon footprint.
Figure 2 is a flow diagram of another conventional method of making dry mix electrode. The another conventional method (200) comprises the steps of a) adding a pre-defined amount of active material (1), conductive material (2) (which may also be referred as conductive agents) and a binder agent (3) in a container to obtain a first mixture, b) mixing the first mixture to obtain a dry mixture. The binding substance deform under shear stress until the binding substance form fibers that holds the other electrode components together. The dry mix is then extruded in form of thin layers and pressed onto metal foils that act as current collectors. The electrodes referred to as dry electrodes. However, the method of dry mixing powders till the point of shredding the polymeric binders to fibers takes a lot of energy. Along with that, the dry mixing of powders takes a long time to achieve the fibrous nature of binding substance. The uniformity and quality control on electrode dimensions is difficult to achieve in the dry electrode method.
Figure 3 is a block diagram of a method (300) for manufacturing semi-solid electrode according to an embodiment of the present invention. The method (300) comprises the following steps.
At step (a), the method comprises mixing of at least one active material (1), at least one binding agent (2) and a plurality of conductive components (3) via a dry mixing technique to obtain a dry mixed powder (4). The active material (1) is in powder form and is selected based on an energy storage device. The active material (1) in range from 85% to 95%, the conductive component (3) in range from 0.1% to 10% and the binding agent (2) from 0.1% to 7%. The dry mixing technique includes a combination of planetary, centrifugal motion and three-dimensional tumbling motion.
Also, the binding agent (2) holds the active material (1) and conductive components (3) together by forming a network and adhere to the current collector to increase electrical conductivity within the semi-solid electrode (5). The conductive components (3) form a percolation network to flow current through the semi-solid electrode (5). The plurality of conducive material include carbon blacks, carbon nanotubes, graphite, graphene, carbon fibers.
Further, the method includes an addition of a solvent to the dry mixed powder (4) to swell the binding agent (2) for obtaining the semi-solid electrode (5) structure. The binding agent (2) include carboxymethyl cellulose, polyvinylpyrrolidone, polymethyl methacrylate, polyethylene oxide, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylic acid, styrene-butadiene rubber.
At step (b), the method comprises adding a solvent to the dry mixed powder (4) obtained in step (a) to achieve a semi-solid electrode (5) structure. The solvent is an aqueous solvent or a non-aqueous solvent. The solvent is composed of water and carbon dispersed in a water based suspension and a dispersant that stabilizes the water based suspension. Further, the solvent is added according to the industry standard or as per the requirement, which may be known to a person skilled in the art.
At step (c), the method comprises roll-pressing the semi-solid electrode (5) structure obtained in step (b) multiple times to achieve better homogeneity, thereby obtaining the semi-solid electrode (5).
The method provides a reduction in energy consumption in range from 30% to 50%.
Figure 4 is a flow diagram of a method (300) for manufacturing semi-solid electrode according to an embodiment of the present invention. In other words, Figure 4 in another representation of the method (300) provided by the present invention. The method (300) for manufacturing semi-solid electrode solves the problem by reducing solvent requirement and hereby decreasing energy consumption during solvent drying.
In addition, the method (300) for manufacturing semi-solid electrode has higher thickness of electrode as compared to the slurry mixing method. The method (300) for manufacturing semi-solid electrode comprises of at least one active material (1), at least one binding agents (2) and a plurality of conductive components (3). The active materials (1), the set of binding agents (2) and the plurality of conductive components (3) are mixed via a dry mixing technique to obtain a dry mixed powder (4). The binding agents (2) are preferably polymers. A suitable solvent is added to the dry mixed powder (4) that acts as a medium to swell the binding agents (2). The active materials (1), the swollen binding agents (2) and the conductive components (3) are mechanically mixed in order to achieve a semi-solid electrode (5) structure. Thereafter, mechanically mixing the above mixture, with the binders in swollen state, reduces the energy consumption required for homogeneous mixing.
The semi-solid electrode (5) structure is roll-pressed with multiple passes to achieve better homogeneity. The plurality of conductive components (3) are preferably anisotropic in nature. The plurality of conductive components (3) include but not limited to carbon blacks, carbon nanotubes, flake graphite, graphene and carbon fibers. The binding agents (2) include but not limited to carboxymethyl cellulose, polyvinylpyrrolidone, polymethyl methacrylate, polyethylene oxide, polyvinylidene fluoride, polytetrafluoroethylene, and polyacrylic acid and styrene-butadiene rubber. The solvent is preferably aqueous, non-aqueous or mixture of aqueous and non-aqueous. The semi-solid electrode (5) structure is roll-pressed with multiple passes to achieve better homogeneity.

EXAMPLE 1
Preferred Implementation of the Present Invention
The present invention provides the method (300) for manufacturing semi-solid electrode that is cost-effective and that takes less energy and time in battery manufacturing.
The method (300) for manufacturing semi-solid electrode comprises steps of mixing of at least one active material (1), at least one binding agent (2) and a plurality of conductive components (3) via a dry mixing technique to obtain a dry mixed powder (4). In an implementation, the semi-solid electrode (5) have 85% to 98% active material (1), 10% to 0.1% conductive carbon (i.e. conductive component), and 7% to 0.1% binder content (i.e. binding agent).
Further in dry mixing technique, the powders (active material (1), conductive component (3), and binding agent (2)) are added sequentially to a container, with mixing steps between each addition. The homogenous mixing of these powders is ensured either by using a combination of planetary and centrifugal motion to create a powerful mixing effect or by using a three-dimensional tumbling motion to mix powders homogeneously. The dry mixing technique ensures thorough mixing without causing particle degradation or segregation is utilized for the dry mixing technique.
Further, the method comprises adding a solvent to the dry mixed powder (4) obtained in step (a) to achieve the structure of semi-solid electrode (5) e. Thereafter, roll-pressing the semi-solid electrode (5) obtained in step (b) multiple times to achieve better homogeneity, thereby obtaining the semi-solid electrode (5).
The solvent is composed of water, carbon dispersed in a water-based suspension, and a dispersant stabilizing the suspension. The carbon content can range between 0.01 to 1 wt. %.
Also, the present invention eliminates the use of metallic current collectors. The electrode is made with a metallic current collector, or may be even be a free-standing film. The binding agent (2) give adhesion to the metallic current collector or even provide enough adhesive force to form a free-standing film.
In other words, adding the binding agent (2) does not contribute to any increase in electronic conductivity. The binding agent (2) forms a network upon adding a solvent that creates the adhesive force between the active materials (1) and the conductive additives. The binding agent (2) creates the network between the active materials (1) and the conductive additives, thereby providing contact between both in an extensive range. This enhances the electronic motion from and to the active material (1).
Also, the present invention reduces (up to 50%) the amount of solvent required for manufacturing semi-solid electrode (5) and achieves 50% reduction in the energy consumption for solvent drying. Moreover the present invention reduces the preparation time of electrode, equipment and floor spacing required for manufacturing.
Therefore, the present invention provides a method for manufacturing semi-solid electrode with homogeneous properties that takes less time and energy, as less number of steps are carried out in the present invention, in manufacturing of electrode in order to provide more efficient and high-performance energy storage devices.
Many modifications and other embodiments of the invention set forth herein will readily occur to one skilled in the art to which the invention pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
The foregoing description of embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principle of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated.
,CLAIMS:CLAIMS

We claim:
1. A method (300) for manufacturing semi-solid electrode comprising steps of:
a) mixing of at least one active material (1), at least one binding agent (2) and a plurality of conductive components (3) via a dry mixing technique to obtain a dry mixed powder (4);
b) adding a solvent to the dry mixed powder (4) obtained in step (a) to achieve a semi-solid electrode (5) structure; and
c) roll-pressing the semi-solid electrode (5) structure obtained in step (b) multiple times to achieve homogeneity, thereby obtaining the semi-solid electrode (5).
2. The method (300) for manufacturing semi-solid electrode as claimed in claim 1, wherein said active material (1) is in powder form and is selected based on an energy storage device.
3. The method (300) for manufacturing semi-solid electrode as claimed in claim 1, wherein said binding agent (2) holds the active material (1) and conductive components (3) together by forming a network and adhere to the current collector to increase electrical conductivity within the semi-solid electrode (5).
4. The method (300) for manufacturing semi-solid electrode as claimed in claim 1, wherein said conductive components (3) form a percolation network to flow current through the semi-solid electrode (5).
5. The method (300) for manufacturing semi-solid electrode as claimed in claim 1, wherein said method include an addition of a solvent to the dry mixed powder (4) to swell the binding agent (2) for obtaining the semi-solid electrode (5) structure.
6. The method (300) for manufacturing semi-solid electrode as claimed in claim 5, wherein said solvent is an aqueous solvent or a non-aqueous solvent.
7. The method (300) for manufacturing semi-solid electrode as claimed in claim 5, wherein said solvent is composed of water and carbon dispersed in a water based suspension and a dispersant that stabilizes the water based suspension.
8. The method (300) for manufacturing semi-solid electrode as claimed in claim 1, wherein said plurality of conducive material include carbon blacks, carbon nanotubes, graphite, graphene, carbon fibers.
9. The method (300) for manufacturing semi-solid electrode as claimed in claim 1, wherein said binding agent (2) include carboxymethyl cellulose, polyvinylpyrrolidone, Polymethyl methacrylate, polyethylene oxide, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylic acid, styrene-butadiene rubber.
10. The method (300) for manufacturing semi-solid electrode as claimed in claim 1, wherein said semi-solid electrode (5) include the active material (1) in range from 85% to 95%, the conductive component (3) in range from 0.1% to 10% and the binding agent (2) from 0.1% to 7%.
11. The method (300) for manufacturing semi-solid electrode as claimed in claim 1, wherein said dry mixing technique includes a combination of planetary, centrifugal motion and three-dimensional tumbling motion.
12. The method (300) for manufacturing semi-solid electrode as claimed in claim 1, wherein said method provides a reduction in energy consumption in range from 30% to 50%.