JPH10172541A - Electrode paste applying device and relating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mix an electrode paste with a polymerization initiator without generation of excess mechanical energy and/or heat by mixing the electrode paste effectively delivered from a means which holds the electrode paste so as to be capable of delivering with the polymerization initiator, and preventing the polymerization of the electrode paste by effectively linking with the mixing means before applying to a substrate. SOLUTION: An electrode paste supporting means 22 forces the electrode paste to deliver with a pressure piston like member. Electrode paste 40 and a polymerization initiator 45 are effectively mixed with a mixing means 26 before the mixture is applied to the upper surface 50 of a substrate 44. An electrode paste applying device 10 applies the mixture to the metal foil substrate 44 immediately after the electrode paste 40 and the polymerization initiator are mixed. Before the electrode paste is delivered from the electrode paste putting and/or mixing means 26, the polymerization initiator 45 is put in a polymerization initiator holding means 24. The electrode paste 40 and the polymerization initiator 45 are at first put in supporting/holding means respectively, then delivered to the mixing means 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION

1. Field of the Invention The present invention relates to an electrode paste application apparatus and related methods for the fabrication of thermoset electrodes, such as cathodes, for use in electrolytic cells, particularly rechargeable electrolytic cells.

2. Prior Art Electrolytic cells, such as rechargeable lithium batteries, having an electrode / cathode composed of a metal foil current collector and an electrode / cathode paste are known in the art. In fact, the cathode paste for such an application can be made from a variety of materials using common techniques.

[0003] In particular, typical components of such cathode pastes (metal foil current collector materials) based on known desirable percentages of the total component weight include cathode active materials, carbon black, graphite, plasticizers and acrylics. Will contain system monomers. To actually produce the cathode paste, the cathode active material, carbon black, graphite and at least some plasticizer are mixed together. The actual mixing operation typically lasts from 3 hours to 3 days, depending on the particular mixing / milling technique used and the particular degree of grinding required.

After the mixing / milling process is completed, the acrylic monomer is gently mixed with the paste using what is commonly known as a double-armed closed mixer. However, because polymerization inhibitors are generally added to acrylic monomers by the manufacturer (to prevent accidental polymerization during transport, storage, handling, etc.)
Before mixing with the paste, the monomers must be reprocessed to remove such inhibitors. Therefore, in order to prepare the cathode paste using monomers that do not contain polymerization inhibitors, the paste is very susceptible to premature gelling / polymerization when subjected to excessive heat or mechanical energy. Would.

[0005] Once the cathode paste is completely manufactured, it is ready for application to the current collector material. Since it is desirable that polymerization of the cathode paste is started immediately after the cathode paste is applied on the surface of the current collector, the polymerization initiator is applied after or immediately before the application of the cathode paste to the current collector material. Mix into the paste. The prior art also discloses the use of such polymerization initiators, but unfortunately consistent mixtures,
Secondly, uniform polymerization is difficult, if not impossible, to achieve. It is further known that other problems arise when mixing the polymerization initiator and the cathode paste before applying the cathode paste to the current collector material. In fact, such prior art mixing generally results in an excessive transfer of mechanical energy and / or heat to the mixture, which unfortunately thereby leads to premature polymerization and, for example, gelling in the mixing equipment, which results in very high processing equipment. Frequent damage occurs.

Accordingly, it is an object of the present invention to provide an electrode paste application apparatus and related method wherein the electrode paste is mixed with a polymerization initiator before applying the electrode paste to the substrate / current collector material. It is also an object of the present invention that it does not generate excessive mechanical energy and / or heat, and consequently excessively transfers such mechanical energy and / or heat to the components to be mixed. It is an object of the present invention to provide an electrode paste applying apparatus and a related method for mixing an electrode paste and a polymerization initiator without using the same.

It is still another object of the present invention to provide an electrode paste application apparatus and related method in which polymerization of the electrode paste does not occur after discharge from the mixing apparatus and until the electrode paste is applied to the substrate / collector material. It is to provide. It is another object of the present invention that electrodes for use in electrolytic cells (eg, rechargeable lithium batteries) can be completely fabricated using in-line manufacturing methods, and furthermore that such electrolytic cells require It is an object of the present invention to provide an electrode paste applying apparatus and related method, which may further include an additional in-line apparatus for continuously manufacturing and completely assembling all members. These and other objects of the present invention will become apparent in light of the present specification, claims and drawings.

[0008]

SUMMARY OF THE INVENTION The present invention relates to an apparatus for applying an electrode paste on a substrate for use in an electrolytic cell. The apparatus includes means for supporting the electrode paste in a releasable manner and means for holding the polymerization initiator in a releasable manner. Means for mixing a predetermined amount of the electrode paste and the polymerization initiator is also included. The mixing means functions to mix a predetermined amount of the electrode paste and the polymerization initiator and discharge the mixture onto the substrate.
In addition, it includes a means effectively interlocking with the mixing means to prevent polymerization of the electrode paste before applying the mixed polymerization initiator and electrode paste on the substrate. In a preferred embodiment, the means for preventing polymerization is intended to include a static or stationary mixer.

In a preferred aspect of the present invention, the apparatus further comprises means for adjusting the desired amounts of the electrode paste and the polymerization initiator released from the mixing means onto the substrate.
The control means can also be used to control the release of the desired amount of electrode paste and polymerization initiator into the mixing means. Furthermore, means for curing the electrode paste after it has been applied on the substrate, for example (furnace) are also contemplated. Curing occurs in an at least two-step process. For example, it is desirable to only partially cure the electrode paste after it has been applied to the substrate, and then to cure it more completely at a later stage. Indeed, in one preferred embodiment of the present invention, the electrolyte is mixed with the electrolyte polymerization initiator in a manner similar to that discussed for the electrode paste and polymerization initiator. Such multi-step curing of the electrode paste is desirable because the electrolyte generally adheres relatively well to the soft or partially cured electrode paste.
Therefore, even after the electrolyte is applied, the electrode paste can continue to harden.

[0010] In a preferred embodiment, the present invention provides a method, such as a coating film, to prevent the applied electrode paste from being excessively exposed to oxygen after the electrode paste has been applied to the substrate and before subjecting it to curing means. Means for applying a protective cover are further contemplated. The present invention further contemplates means for removing volatiles that may be present in the electrode paste prior to polymerization, as well as means for removing water in the electrode paste by using a dehydrating agent.

According to the present invention, a) the electrode paste is inserted into the supporting member, b) the polymerization initiator is inserted into the holding chamber, and c) a predetermined amount of the electrode paste and the polymerization initiator are respectively supplied to the supporting member and the holding chamber. And into the mixing chamber, d) mixing a predetermined amount of the electrode paste and the polymerization initiator in the mixing chamber, e)
Discharging the mixed electrode paste and polymerization initiator from the mixing chamber and applying it on the substrate; and f) initiating polymerization of the electrode paste after the electrode paste is released from the mixing chamber and applied to the substrate. Includes a method for applying the electrode paste to the substrate.

In a preferred embodiment of the present invention, the method further comprises the step of adjusting the amount of the mixed electrode paste and polymerization initiator released onto the substrate. The method also includes, after the step of applying the electrode paste on the substrate, curing the electrode paste, for example, by inserting the substrate with the electrode paste into a furnace. In such a preferred embodiment, the method includes, after the step of applying the electrode paste to the substrate and prior to the step of curing the electrode paste, providing a protective cover that serves to prevent the electrode paste from being excessively exposed to oxygen. The method further includes applying to the substrate. The method includes removing volatiles in the electrode paste after applying the electrode paste to the substrate, and removing water that may be present in the electrode paste or the polymerization initiator using a dehydrating agent. It is also intended to include. The method uses a multi-step curing process and is directed toward the overall fabrication of rechargeable lithium batteries in an in-line method for applying the substrate with the electrode paste to another substrate, such as an electrolyte and a lithium anode. It may be possible to continue.

[0013]

DETAILED DESCRIPTION OF THE INVENTION While the invention is susceptible to various embodiments, two specific embodiments are shown in the drawings and described in detail herein. It should be understood, however, that this disclosure is an exemplification of the principles of the invention and is not intended to limit the invention to the described embodiments. FIG. 1 shows an electrode paste applying apparatus 10 including an electrode paste support means 22, a polymerization initiator holding means 24, a mixing means 26, a control means 28-30, a curing means 32, a substrate protection cover means 34 and a volatile substance removing means 36. Have been. The polymerization initiator holding means 24, including any commercially available container that supports and allows the release of a liquid or gas, may include the polymerization initiator 45 and / or the polymerization initiator and at least one other component, such as several. And a commercially available solvent, a polymerization accelerator, a polymerization modifier, a dehydrating agent, a highly reactive polyfunctional cross-linking monomer, and the like. If chemically incompatible, such components can be applied sequentially. Polymerization initiators are also commercially available,
Used to initiate polymerization of electrode paste 40. Some examples of polymerization initiators that can be used include peroxides such as t-butyl peroctoate and benzoyl peroxide, and azo compounds such as azobisisobutyronitrile.

An electrode paste support means 22 having a cylindrical device for forcing a predetermined amount of electrode paste from the support means 22 with a pressure piston-like member is shown. However, other common holding and dispensing mechanisms could be used if desired. The electrode paste 40 and the polymerization initiator 45 (along with the other desired components identified above) are effectively mixed using the mixing means 26 before the mixture is applied to the upper surface 50 of the substrate 44. . As described below, the substrate ("current collector") may include, for example, a metal foil or mesh, upon which the electrode paste is applied and then the electrodes 60 are assembled, for example, for use in a rechargeable lithium battery. Will be included.

The mixing means 26 may cause undesirable premature polymerization initiation of the electrode paste due to heat.
May include any suitable mixing device that does not cause excessive heat and / or excessive conversion of energy (from the mixing device) to heat (in the mixture). It is also desirable that the mixing means operate so as not to cause undesirable air / bubble formation in the mixture. In addition, as identified below, the electrode paste itself (even before mixing with the polymerization initiator) is, from the beginning, an acrylic unit that has been chemically treated to remove an otherwise effective polymerization inhibitor. It is first produced using a monomer. As a result, the electrode paste supporting means 2
The electrode paste inserted in 2 easily gels very quickly when it receives excessive heat or mechanical energy, and thus further requires the above-mentioned mixing means. Mixing devices that exhibit acceptable properties for use in the present invention are commonly known as stationary or stationary mixers and are available from Cole-Palmer Instruments Company of Niles, Ill. And of Keminiar, Inc. of North and Bar, Mass. Commercially available from such companies.

In operation, the electrode paste application device 1
0 immediately after mixing the electrode paste, for example electrode paste 40, with the polymerization initiator, the metal foil substrate 44 (for actual use in the electrolyte cell after completion of the claimed and described method). Produces a thermosetting electrode 60)
It is configured to be applied to. Substrate / current collector material 4
Although 4 is shown in roll form, experts in the art could conceive of other means for supplying such materials, especially dispensing pre-cut sheets. Will be easily understood.

The electrode paste 40, which has been premixed to the desired consistency (fineness of pulverization), is inserted into the electrode paste support means 22 until it is effectively released into the mixing means 26. To keep. A variety of electrode pastes can be used for application on the substrate / current collector 44, but typical components of such electrode pastes are as follows:

Prior to insertion of the electrode paste and / or release from the mixing means 26, the polymerization initiator 45 is inserted into the polymerization initiator holding means 24. As described above, the polymerization initiator holding means may include other desired components. For example, since it is important that the electrode paste does not substantially contain water, it is desirable to add a dehydrating agent to the polymerization initiator before mixing with the electrode paste. An example of a dehydrating agent that can be used is dimethoxypropane, but it is contemplated that polymerization initiator 45 or other common dehydrating agents that do not affect the chemical composition of the electrode paste may be used as well.

In particular, the use of dimethoxypropane as a dehydrating agent (in a preferred embodiment) is: 1) reacting with water that may be present in the electrode paste to remove volatilization means 36 (described below); This is desirable because it produces readily volatile methanol and acetone when exposed to water and can be used as a solvent / diluent for 2) polymerization initiators. In fact, when the polymerization initiator is a solid material such as benzoyl peroxide or azobisisobutyronitrile, the use of such a solvent is typically required. Other than using such additives in the polymerization initiator prior to mixing with the electrode paste, other such components may be added to the mixing means 26 (rather than added directly into the polymerization holding means 24). It is also conceivable to add directly by a separate injection / dispensing system.

Although not shown, it is conceivable that the apparatus 10 includes a plurality of polymerization initiator holding means and, consequently, a plurality of various polymerization initiators. Indeed, it may be desirable to use two different types of polymerization initiators that mix with the electrode paste and result in a two-step curing / polymerization process after applying the mixed electrode paste onto a substrate. For example, it is known that electrolytes adhere better to soft (ie, partially cured) electrode pastes than to hard (ie, substantially cured) electrode pastes.
Thus, the present invention uses various types of polymerization initiators to partially cure the electrode paste (promote the bond between the electrolyte and the electrode paste) before the desired electrolyte is applied thereon, And it is intended that the second phase of the curing process then follows after the electrolyte has been applied. of course,
The first stage of such a curing process results in various mechanisms and processes that may be imposed during the continuous fabrication of the electrode / substrate as well as the finished electrolytic cell to the applied electrode paste. It will be appreciated that this results in a cured electrode paste that is at least sufficiently resistant to mechanical stress.

Although the use of a multi-stage polymerization initiator has been described as consisting of a separate polymerization initiator and a separate means for retaining the polymerization initiator, the homopolymerization initiator can be used to effect controlled curing and to provide a soft electrolyte (partial). It is also conceivable to configure it so that it is applied to an electrode paste that has been (cured). It is also conceivable that such multi-stage cured electrode pastes are exposed in a controlled manner to various curing catalysts.

Electrode paste 40 and polymerization initiator 45
(And other desired components) are inserted into their respective support / holding means, and then a predetermined amount of them is discharged into the mixing means 26. As shown in FIG. 1, such predetermined amounts are adjusted by adjusting means 28 and 29, which are, in a preferred embodiment, conventional gear metering pumps, but are various to be discharged into the mixing means. Other types of common regulators suitable for use with the present chemistry may be used. Further, the actual ratio of the polymerization initiator 45 to the electrode paste 40 depends on their specific chemical composition and the like, but the polymerization initiator used is generally 0.1% of the total weight of the specific electrode paste used. It will range from 05% to 2.0%. The actual mixing of the polymerization initiator and the electrode paste begins immediately after the controlled release of them into the mixing means 26. Also, as described above, the mixing means 26 thoroughly mixes the polymerization initiator and the electrode paste together without receiving unacceptable levels of heat and mechanical energy that might otherwise be applied from the mixing device. Must be configured as follows.

Immediately after effectively mixing the electrode paste and the polymerization initiator, a controlled amount of the mixture is then applied (in conjunction with the control means 30) to the top surface 50 of the substrate / collector material 44.
Release and apply. The release and application of the mixture onto the substrate should be performed as part of a continuous process (ie,
Wherein the movement of the substrate material is coordinated with the continuous release of the mixture from the mixing means), the predetermined amount of the mixture being released and applied to the substrate in a tuned time increment, or such release of the mixture It is also conceivable that the application takes place at a sensing position of the substrate as the substrate travels during the process. Of course, other convenient delivery and material application methods are also contemplated, as long as the desired amount of the mixture is applied on the predetermined portion and on the substrate at the predetermined thickness.

After effectively applying the mixture onto the substrate / collector material 44, polymerization of the applied electrode paste occurs. In practice, due to the mixing means, in particular the anti-polymerization means associated with the mixing means, combined with the mixing of the polymerization initiator and the electrode paste just before application on the substrate / collector material 44, the mixture is Polymerization does not actually begin until it is released from the mixing means and it is applied to the substrate. Thus, premature gelling / polymerization that would otherwise cause damage to the processing equipment and produce degraded, chemically destroyed electrodes is avoided.

As the polymerization of the electrode paste on substrate 44 occurs, the coated / treated substrate is then subjected to volatile removal means 36. Volatiles, such as methanol and acetone, are vaporized and removed from the electrode paste by volatile removal means, which may include a common heat source such as a heat gun or other type of heat flow. It is also conceivable to overlay the substrate protection cover means 34 on the applied electrode paste after the removal of the volatile substances. The applied electrode paste is substantially prevented from being excessively exposed to oxygen by using a protective cover means, which may for example comprise a plastic film or a metal foil (shown in roll form in FIG. 1). . Of course, if the coating is applied under inert atmosphere conditions, such as a nitrogen atmosphere,
There would be no need for a protective cover.

After the protective cover means has been effectively placed on the applied electrode paste, the coated substrate is then subjected to curing means 32. The curing means acts to promote the polymerization of the electrode paste and may include a heat source such as a furnace. As the coated substrate exits the curing means, the thermally cured electrode is effectively fabricated. The finished electrode is then optionally used as an electrode in an electrolytic cell. It is also conceivable to actually make and assemble other components for such cells, such as the electrolyte and the anode, in combination with the resulting electrode as part of an in-line process, where the resulting electrode is cured. Means 32
, Together with other integrated components for such in-line production of a substantially completed electrolytic cell, especially a rechargeable lithium battery.

In particular, an additional in-line process is shown in FIG. 2 where the substrate with the applied electrode paste is heading towards the fabrication of the electrolytic cell. Since the components and processes previously described for the application of the electrode paste in FIG. 1 are also used in the continuous in-line process of FIG. 2, the same reference numbers are used where appropriate. Therefore, the substrate 44
In addition to the steps and components described above for applying the electrode paste 40 to the upper surface 50 of the device 10, the device 10 further comprises an electrolyte support means 62, an electrolyte polymerization initiator holding means 64, and a combination means 66 (which is preferably in , An electrolyte 70, an electrolyte polymerization initiator 75, a heat source 76 and a treated lithium anode 80. Those skilled in the art will appreciate that other types of treated, untreated substrates, including lithium anodes but including other types of alkali metal anodes, are contemplated for use with the present invention.

In operation, after the substrate 44 has been effectively coated with the electrode paste 40 (preferably the electrode paste is mixed with a polymerization initiator capable of a two-step cure) and the electrode paste is somewhat While soft (partially cured), the coated substrate is then further coated with an electrolyte. As was done with the electrode paste 40, predetermined amounts of the electrolyte 70 and the electrolyte polymerization initiator 75 are released from the electrolyte support means 62 and the electrolyte polymerization initiator holding means 64 into the combination means 76, respectively. A combination means, which may include a static mixer, mixes the electrolyte and the polymerization initiator so that the electrolyte is released from the combination means and polymerization does not occur until it is applied onto the electrode paste on the substrate.

Once the electrolyte has been effectively applied onto the electrode paste, the electrolyte is then exposed to another source of energy, such as a heat source 76, a furnace or ultraviolet light. The heat source accelerates the curing of the electrolyte and also functions to accelerate the curing of the electrode paste if necessary (for example, if a multi-step curing method is used for the electrode paste). Note that a multi-stage curing method is also contemplated for use with electrolytes.

After application of the electrolyte, the coated substrate can be effectively coated with a treated lithium anode, for example for the overall fabrication of an electrolytic cell. The foregoing description and drawings are merely illustrative of the invention and are merely illustrative, and those skilled in the art can make modifications and alterations from these disclosures without departing from the scope of the invention. It is not limited thereto except that the range is limited.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of the apparatus, and

FIG. 2 is a schematic diagram of another embodiment of the present apparatus.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Arthur A. Masco USA Massachusetts 01760 Natick Tamarack Road 20

Claims (22)

[Claims] 1. Apparatus for applying an electrode paste on a substrate used in an electrolytic cell, comprising: means for supporting the electrode paste in a releasable manner; holding the polymerization initiator in a releasable manner. Means for mixing predetermined amounts of electrode paste and polymerization initiator effectively released from the electrode paste support means and the polymerization initiator holding means, respectively, for actual release and application onto the substrate, and mixing An apparatus comprising means for effectively coordinating with the mixing means to prevent polymerization of the electrode paste before applying the polymerization initiator and the electrode paste on a substrate. 2. The apparatus according to claim 1, wherein the polymerization preventing means is a static mixer. 3. The apparatus of claim 1, further comprising means for adjusting a desired amount of electrode paste and polymerization initiator released from the mixing means onto the substrate. 4. The apparatus of claim 1, further comprising means for applying the electrode paste to the substrate and thereafter curing the substrate. 5. The apparatus according to claim 4, wherein the curing means has a source of thermal energy. 6. Means for supporting the electrolyte in a releasable manner; Means for holding the electrolyte polymerization initiator in a releasable manner; Where the electrolyte is effectively released from the electrolyte supporting means and the electrolyte polymerization initiator holding means, respectively. Means for combining a fixed amount of electrolyte and polymerization initiator for release and application onto the electrode paste applied on the substrate, and releasing and applying the combined electrolyte and electrolyte polymerization initiator to the electrode paste on the substrate 2. The apparatus of claim 1, further comprising means for preventing polymerization of the electrolyte in effective association with said combining means. 7. The apparatus according to claim 6, wherein the electrolyte polymerization preventing means is a static mixer. 8. The apparatus according to claim 6, further comprising means for applying the electrolyte to the electrode paste on the substrate and thereafter curing it. 9. A means for curing the electrode paste in at least two separate steps, wherein the first step of curing is performed before the electrolyte is applied to the electrode paste on the substrate, so that the partially cured electrode paste is cured. 7. The apparatus of claim 6, wherein the means for producing a paste and at least the second stage of curing further comprises electrode paste curing means occurring after an electrolyte is applied to the partially cured electrode paste. 10. The method of claim 1, further comprising: after applying the electrode paste on the substrate, applying a protective cover on the substrate to prevent the applied electrode paste from being excessively exposed to oxygen. Item 10. The apparatus according to Item 1. 11. The apparatus of claim 1, further comprising means for removing any volatiles that may be present in the electrode paste prior to polymerization. 12. The apparatus according to claim 1, further comprising means for removing water in the electrode paste using a dehydrating agent prior to applying the electrode paste on the substrate. 13. The apparatus of claim 1, further comprising means for adjusting the desired amounts of electrode paste and polymerization initiator released from the electrode paste support means and the polymerization holding means into the mixing means, respectively. 14. A method for applying an electrode paste to a substrate, the method comprising: inserting the electrode paste into a support member; inserting the polymerization initiator into a holding chamber; Releasing the polymerization initiator from the support member and the holding chamber into the mixing chamber, respectively;-mixing a predetermined amount of the electrode paste and the polymerization initiator in the mixing chamber;-mixing the mixed electrode paste and the polymerization initiator from the mixing chamber. Discharging and applying on the substrate; and-initiating polymerization of the electrode paste after the electrode paste is released from the mixing chamber and applied to the substrate. 15. The method of claim 14, further comprising adjusting the amounts of the mixed electrode paste and the polymerization initiator released on the substrate. 16. The method of claim 14, further comprising, after applying the electrode paste on the substrate, curing the electrode paste. 17. After the step of applying the electrode paste on the substrate and before the step of curing the electrode paste, a protective cover is provided which serves to prevent the electrode paste from being excessively exposed to oxygen. 17. The method of claim 16, further comprising applying to. 18. The method of claim 14, further comprising removing volatiles in the electrode paste after applying the electrode paste on the substrate. 19. The method of claim 14, further comprising the step of removing water that may be present in the electrode paste or the polymerization initiator using a dehydrating agent. 20. inserting the electrolyte into the support member; inserting the electrolyte polymerization initiator into the holding chamber; and applying a predetermined amount of the electrolyte and the electrolyte polymerization initiator to the electrolyte support member and the electrolyte polymerization initiator, respectively. Releasing from the holding chamber into the mixing chamber;-mixing a predetermined amount of electrolyte and electrolyte polymerization initiator in the mixing chamber;-releasing the mixed electrolyte and electrolyte polymerization initiator from the mixing chamber and applying them on the substrate. 15. The method of claim 14, further comprising: applying on the applied electrode paste; and initiating polymerization of the electrolyte after the electrolyte is released from the mixing chamber and applied on the electrode paste on the substrate. 21. Means for curing the electrode paste in at least two separate steps, wherein the first step of curing is performed before the step of applying the electrode paste on the substrate to remove the partially cured electrode paste. 21. The method of claim 20, wherein the resulting and at least a second step of curing further comprises electrode paste curing means occurring after applying an electrolyte to the partially cured electrode paste. 22. The method of claim 20, further comprising the step of curing the electrolyte after applying the electrolyte onto the electrode paste on the substrate.