JP2021166182A - System and method for manufacturing electrode with separator - Google Patents

Abstract

To provide a method for manufacturing a battery cell including an electrode and a separator capable of improving safety and reducing the cost without adversely affecting the environment.SOLUTION: A method includes the steps of: providing an electrode; sending the electrode toward a coating region; and coating a mixture of a non-conductive ceramic based separator material and a binder on the electrode in the coating region by a dry non-solvent coating method to form a separator layer.SELECTED DRAWING: Figure 7

Description

[Cross-reference of related applications]
This application is a non-provisional application of U.S. Provisional Patent Application No. 61/647773 filed on May 16, 2012 and claims its priority on September 14, 2012. It is a partial continuation of the filed US Patent Application No. 13/6171162, which claims its priority, and these disclosures are incorporated herein by reference in their entirety.

Government Rights in Invention The United States Government has paid licenses in this invention and, in limited circumstances, SP4701-09-D-0049 CLIN 0002 and given to patent holders by the Defense Logistics Agency. It reserves the right to demand that others be licensed under reasonable conditions as defined by the provisions of HQ0147-140-C-8307.

[Technical field]
Embodiments of the present invention generally relate to dry solvent-free methods and devices for producing electrodes, and more specifically to methods and devices for forming separator layers on electrodes.

Power supplies such as batteries, capacitors and fuel cells typically include positive and negative electrodes. The manufacturing method differs depending on the chemical properties of the power supply. Many methods, such as those used in the Li-ion industry, involve using a solvent to mix the active material, conductive material and binder in a wet slurry, and to apply to a substrate. This application may be by doctor blade, roll transfer coating, slot die or extrusion.

The cast electrodes are then dried in a drying oven, but the solvent is recaptured to prevent the fume from escaping into the environment, or the solvent is used as an auxiliary fuel in the dryer. This process is time consuming and expensive. Drying furnaces are usually very large, long, expensive and space consuming. Solvents are usually flammable, difficult to remove from their chemical structure, adversely affect the environment, and costly to handle properly, both environmentally and from a safety standpoint. If solvent recovery is required, the solvent must be captured, concentrated, purified and prepared for reuse or disposal.

Some known methods of power supply manufacturing are separated from the solvent slurry on one electrode, but still use solvent-based methods on the other electrode. The non-solvent method usually involves press-fitting or extruding a mixture of active material, conductive material and binder into the electrode and then attaching it to a substrate or current collector. Therefore, today's manufacturing techniques limit throughput and the cost of such electrodes can be excessive.

Electrodes made by solvent casting and subsequent extraction typically exhibit good adhesion to current collectors when the dried electrodes are mechanically coined. The action of solvent casting and subsequent extraction leaves the binder and electrode structure open as well as the sponge structure. By the imprint operation, the electrode structure is crushed leaving a porosity of 30 to 50%. When infiltrated with an electrolyte, this crushed sponge-like structure is relaxed and generally exhibits an aspect called electrode swelling. PVDF-Polyvinylidene fluoride, a typical anode binder known as polyvinylidene difluoride, is a highly non-reactive, pure thermoplastic fluoropolymer produced by the polymerization of vinylidene difluoride (vinylidene fluoride). (Fluororesin). It is one of the few known binders that does not easily react at the lithium potential of the anode and is therefore typically suitable as a binder in Li-ion batteries.

Some manufacturers are trying to develop a method of using polytetrafluoroethylene (PTFE) to fibrillate the binder to produce a self-supporting membrane. Next, the self-supporting film carrying this active material is pressed against the current collector to prepare an electrode. Since PTFE is not stable at the lithium ion anodic potential, its use is limited to the use of cathode binders. Other manufacturers have attempted to fabricate lithium electrode structures using aqueous binders. Those manufacturers struggle to completely dry the electrodes to prevent moisture from reacting with the lithium salt and adversely affecting the performance of the resulting battery.

Thus, a preferred method of manufacturing a Li-ion battery typically meets many required performance requirements for at least one electrode (by exhibiting sufficient adhesion to the substrate). Includes solvent-based methods that meet the required and stringent life requirements. However, due to the costs associated with handling, regenerating, and final disposal of these environmentally harmful solvents, the cost of producing Li ions and other solvent-based electrodes can be excessive.

Battery manufacturing also includes providing a battery separator on the electrodes of the battery, which is placed between the anode and cathode of the battery and holds the two electrodes apart to prevent electrical short circuits. At the same time, it also allows the transport of ionic charge carriers needed to close the circuit while the current flows through the electrochemical cell. It has been recognized that existing battery separator manufacturing and application methods have many drawbacks. That is, a battery with a small cell area and many electrodes stacked on it causes problems with alignment and stacking during assembly, as well as short circuit problems, which reduces the overall battery yield. Tabbing and placement of separators on individual electrodes presents challenges in battery manufacturing, and techniques such as heat staking the separators at the ends of the electrodes are useful, but overall alignment and It does not completely address the short-circuit issue.

In a typical battery separator manufacturing and application method, the battery separator is formed by mixing the separator material with pore forming oil, followed by blowing, casting, and extraction / calendaring to leave the separator as a microporous material. Formed as independent sheets / layers. A polyolefin base material is used as the ceramic separator, and ceramic particles are added to the base material to obtain a high polymer (15 to 35%) supported ceramic separator. The separator material must be stored on a roll and then slit / size cut to produce a separator for a particular cell and battery type, followed by the slitting during the actual manufacture of the cell / battery. / Align the cut separator and apply to the cell / battery.

Therefore, it is desirable to provide solvent-free methods and devices for manufacturing electrodes. It is also desirable to provide a method for providing the separator directly on the electrode to eliminate the additional slitting, size cutting and alignment steps associated with the preparation and application of the separator.

(nothing special)

The present invention is directed to methods and devices for manufacturing electrodes, and more specifically, methods and devices for forming ceramic separators for electrodes.

According to one aspect of the present invention, the method of applying a dry solvent-free ceramic separator to the electrode is a step of providing the electrode to the coating area via a feed mechanism and a dry dispersion coating to the electrode with a binder and non-bonding agent. A step of applying a separator layer made of a conductive separator material, wherein the binder comprises at least one of a thermoplastic material and a thermosetting material, including a step of applying the separator layer.

According to another aspect of the present invention, the method of manufacturing a battery cell including an electrode and a separator is a dry method in order to form a separator layer, a step of providing the electrode, a step of feeding the electrode toward the coating region, and a step of forming the separator layer. It comprises a step of coating a mixture of a non-conductive ceramic separator material and a binder on an electrode in a coated area by a solvent-free coating method.

According to yet another aspect of the present invention, the battery cell comprises an electrode and a separator layer adhered to the electrode, wherein the separator layer is at least one of a thermoplastic material and a thermosetting material. The binder of the separator layer contains a binder containing one and a non-conductive ceramic-based separator material, and the binder in the separator layer is in the range of 2 to 30% by weight.

Various other features and advantages will become apparent from the detailed description and drawings below.

The drawings show preferred embodiments currently contemplated for carrying out the present invention.

It is a figure which shows the component of the system for forming an electrode active material on an electrode substrate by one Embodiment of this invention. It is a figure which shows the step for applying the base layer to the electrode substrate, and applying the electrode layer of one or a plurality of active material layers to the base layer according to the embodiment of the invention. It is a figure which shows the base layer which electrode was formed on it using one Embodiment of this invention. It is a figure which shows the component of the system for forming the electrode active material on both sides (both sides) of the electrode substrate by one Embodiment of this invention. It is a figure which shows the base layer which electrode was formed on both sides (both sides) of the electrode substrate using the embodiment of this invention. It is a figure which shows the component of the separator system for coating a separator layer on an electrode which is integrated with the system of FIG. 1 according to one Embodiment of this invention. It is a figure which shows the dry solvent-free method for providing the battery separator on an electrode by one Embodiment of this invention. It is a figure which shows the electrochemical cell obtained by combining the anode-separator structure and the cathode-separator structure by one Embodiment of this invention.

According to an embodiment of the present invention, electrodes for energy storage (storage) devices such as lithium ion batteries are manufactured using solvent-free methods and devices, and separator layers are attached to the electrodes by a dry dispersion method. It is provided for.

FIG. 1 shows a system 100 for manufacturing an electrode by depositing a binder and an electrode active material on one side of a substrate 102 (also known as a current collector in a finished electrode). In one example, the substrate 102 can include copper as an anode current collector or aluminum as a cathode current collector. In another example, the anode current collector is, for example, a composite material containing steel. As another example, the substrate 102 can also include, but is not limited to, nickel-plated steel, fibrous carbon composites, tin dioxide (SnO ₂ ), eg, punched solid sheets or expanded composites (ie, ie). , Allows open expansion of the substrate to reduce weight or allow higher mechanical or material filling). However, the present invention is not limited to this, and as is known in the art, even if an electrode having another (s) of other active materials is formed using any substrate or current collector. good. Active materials or mixtures of active materials include lithium titanate oxide (LTO), cobalt oxide, nickel oxide, manganese oxide, nickel cobalt manganese oxide, iron phosphate, iron oxide, carbon and silicon. Not limited.

The substrate 102 is supplied via a feed mechanism or roller system 104 having a feed mandrel 106 guided by (two) guide mandrel 108 that provides the material for the substrate 102 and rotates in the opposite direction. In the embodiment of the present invention, the substrate 102 may be a single electrode sheet or a continuous feed thereof. The substrate 102 is fed through a first coating region 110 and a second coating region 112, during which a mixture containing a binder, an active material, and a conductive material is coated or sprayed onto the substrate 102. NS. Heat is applied to perform bonding and formation of the electrode material within and / or after passing through the coating areas 110, 112, as described further below. The substrate passes through a second set of guide mandrel 114 that guides the substrate to which the electrode active material is bound towards the collection mandrel 116. According to the present invention, the set 114 of the second guide mandrel is a space or space maintained during operation in order to compress the substrate 102 with electrodes on it to the final desired consistent thickness. It can be designed with a gap.

The first coating region 110 includes a spraying mechanism (such as a spray gun or other known device that produces a spray) configured to spray a first layer or base layer of the material mixture onto the substrate 102. A device 118 for applying the first layer to the substrate 102 is included. Generally, the first coating area 110 is described as having a spray mechanism or spray gun for coating the material onto the substrate and is illustrated as "spray 120", but for coating the material, It is contemplated that any mechanism can be used, including, for example, painting, brushing, powder coating, the use of fluidized beds, the doctor blade method, and wiping with a waste cloth. In fact, in this coating area and all subsequent coating areas described, a spray gun or other known spraying device may be used to coat the first and subsequent layers on the substrate 102, or described above. As such, it is contemplated that any mechanism may be used to apply the material, and that the term "spray" may be applied to any mechanism or means used to apply the liquid to the surface. Has been done.

According to the present invention, the device or spray mechanism 118 emits the spray 120 at about 2-20 psi. According to the present invention, the spray 120 contains a mixture of binder, conductive carbon, and electrode active material. The binder comprises a thermoplastic or thermosetting material according to one embodiment, which, in one embodiment, comprises polyvinylidene fluoride in the range of 6-85% by weight of the total material in the spray 120. Polyvinylidene fluoride) (PVDF). However, the present invention is not limited thereto, and for example, a low level of about 1% or a high binder level of about 100% may be used. Furthermore, the present invention is not limited to PVDF, and includes any binder known in the art according to an embodiment of the present invention, including the above-mentioned thermoplastic and thermosetting materials. May be. As is known in the art, thermoplastic resins are polymers that soften above a certain temperature and return to a solid when cooled. In contrast, and as is also known in the art, thermosetting materials form irreversible chemical bonds during the curing process and decompose upon melting (not reformed during cooling). According to embodiments of the present invention, the binder may be, for example, PVDF or any derivative thereof, or PTFE or any derivative thereof. According to another embodiment of the invention, the binder may contain an ultra-high molecular weight polyethylene material in order to add structural integrity to the binder. Conductive carbon may be included to create or enhance electrical contact between the particles in the electrode, as is known in the art.

Spray 120 may also contain generally 4-8% conductive carbon to include graphite such as TIMREX® KS6 (TIMREX is a registered trademark of Timcal SA located in Switzerland). According to the present invention, increased amounts of conductive carbon up to 17% and above, and up to, for example 40%, may be used). The remaining% of the spray 120 is an electrode active material including, but not limited to, LTO, cobalt oxide, nickel oxide, manganese oxide, nickel cobalt manganese oxide, iron phosphate, iron oxide, carbon and silicon. As an example, the spray 120 contains 13% by weight of binder and 8% conductive carbon, with the remaining amount of spray 120 being 79% active material.

According to the present invention, the spray 120 deposited on the substrate 102 within the first coating region 110 is heated to initiate bonding of the first layer mixture to the substrate 102. In one embodiment, the heater 122 is positioned facing device 118 to raise the temperature of the substrate from about 100 ° F (about 37.8 ° C) to 500 ° F (about 260 ° C), and in one embodiment 300 ° F. Sufficient power is supplied to the heater 122 to raise it within the range up to (about 148.9 ° C.). However, in another embodiment, the heater 124 is positioned to heat the surface of the substrate 102 opposite to the surface of the substrate 102 to which the spray 120 is applied. Also in this embodiment, the heater 124 raises the substrate temperature from about 100 ° F (about 37.8 ° C) to 500 ° F (about 260 ° C), and in one embodiment 300 ° F (about 148.9 ° C). Power is supplied to raise the temperature within the range of up to. Further, in one embodiment, heat may be applied to the base layer via the heater 126 after passing through the first coating region 110 until at least the first layer reaches a plastic state, and then the first layer. May be cooled before applying the electrode material of the subsequent layer. Therefore, according to the present invention, the first layer or base layer of the electrode material is applied to the substrate 102, and the bonding to the substrate 102 is started via the heaters 122 and 124 of one or both. The base layer binder may also be melted throughout using the heater 126 in order to melt the base layer and form it uniformly on the substrate 102. Heaters 122, 124 and 126 may be heated by any number of known mechanisms. For example, heaters 122-126 may include infrared (IR) heaters, convection heaters, conduction heaters, radiant heaters (eg, outside the IR spectrum) or induction heaters.

The heaters 122/124 and 126 generally serve different purposes. For example, the heater 122/124 changes the binder material in contact with the substrate 102 into a plastic state (but without heating to the point where the binder easily melts and flows) and adheres to the substrate 102. As such, it provides heat directed to the substrate 102. On the other hand, the heater 126, as a whole, is directed to heat most of the sprayed material that forms the base layer. According to the present invention, heat can be supplied to any surface of the substrate 102 in this way, and the heaters 122 and 124 depending on factors such as the amount of binder in the spray 120, the apparatus 118. Can be provided at different positions with respect to. Thus, different types of heaters can be used to perform different desired types of heating. For example, the heater 122 and / or the heater 124 may be an induction heater that mainly heats the substrate 102, and the heater 126 may be an IR heater, a convection heater, or a radiant heater. In another example, one or all heaters (122 and / or 124, and 126) are IR heaters. In fact, according to the present invention, any combination of heaters can be used, depending on the desired type of heating to be performed (relationship between the substrate and the coating material layer).

As is known in the art, it is generally desirable to maximize the amount of active material in the electrode. Therefore, it is also desirable to minimize the amount of binder used in the spray 120, which provides sufficient binding in the base layer sprayed onto the substrate 102 in the first coating region 110. There is a restriction by the guideline. The bonding of the first layer of the spray material 120 is influenced not only by the type of heater, the temperature obtained, etc., but also by the amount of binder, conductive carbon, and active material present in the spray 120. As is known in the art, the particle size may be positively selected based on the type of electrode formed, even in the range of nanometer-sized low particles to hundreds of microns and above. good. The particle size may be varied over the entire depth of the electrode. Thus, the particle size of the active material affects not only the amount of active material that can be deposited on the base layer, but also the amount of binder and the amount of heat applied to initiate the binding of the base layer.

According to the present invention, the apparatus 118 may include a spray gun to which an electrostatic charge is applied in order to guide and accelerate the particles in the spray 120 toward the substrate 102. A known spray mechanism typically applies to the nozzle 128 of the spray gun 118 such that the particles emitted from the nozzle 128 are charged to form an electrostatic voltage difference between the nozzle 128 and the substrate 102. Includes static charges applied in close proximity. According to one embodiment, the electrostatic voltage applied to the nozzle 128 is 25 kV, but the present invention is not limited to this, and according to the present invention, the spray 120 is uniformly applied to the substrate 102. As such, any voltage above or below 25 kV, such as 100 kV, may be applied. The voltage difference may be increased by grounding the area of the substrate 102 to which the spray 120 is directed. Since the substrate 102 constantly passes through the first coating region 110, it may be inconvenient to directly ground the substrate 102. Therefore, according to the present invention, the support structure 130 through which the substrate 102 passes may be provided. The support structure 130 is fixed and in electrical contact with the substrate 102, so grounding of the substrate 102 can be performed by providing a ground wire 132 connected to the support structure 130. According to one embodiment, a plurality of ground wires may be included (represented by a second ground wire 134) in order to ground the substrate 102 closer to the location where the spray 120 hits and more uniformly. However, according to the present invention, a large number may be included).

The system 100 includes a second coating area 112 that deposits the second layer on the substrate 102. The second coating region 112 is a device 136 (as described above, spray gun) that discharges the spray 138 toward the substrate 102 and drops or hits it onto the first layer coated in the first coating region 110. And other known devices that produce sprays, etc.). Adhesion from one electrode layer to the next electrode layer tends to be easier to achieve than adhesion of the first base layer to the substrate 102, so spray 138 for the second electrode layer and any subsequent electrode layer. Usually contains less binder. Therefore, according to one embodiment of the present invention, the spray 138 contains 80 to 90% by weight of active material (LTO, cobalt oxide, nickel oxide, manganese oxide, nickel cobalt manganese oxide, iron phosphate, iron oxide). , But not limited to, carbon and silicon, 4-8% by weight of conductive carbon, and residual binder (PVDF in one embodiment). However, the present invention is not limited to this, and for example, the binder level in the second electrode layer (and any subsequent layer) is also as low as about 1% or as high as 100%. You can also do it. In fact, according to the present invention, the first layer and the second and subsequent layers applied to the first layer may contain active materials and binders of arbitrary composition and ratio.

According to the present invention, one or both heaters 140 that provide heat to the substrate 102 may be included. However, since the substrate 102 has already been coated with the base layer in the first coating region 110, the heater 140 may not be needed because it provides a heat insulating barrier in which the base layer should also be formed. Also, the coupling from one electrode layer to the next may be more effective, and the heat from the heater 142 may be sufficient to bring the subsequent electrode material from the spray 138 into a plastic state. For some reason, the heater 140 may not be included.

The heater 140 (if used) and the heater 142 may supply heat by any number of known methods, including, for example, IR heaters, convection heaters, radiant heaters or induction heaters. Further, the device 136 may also include a spraying mechanism having a nozzle 144 to which an electrostatic charge such as 25 kV can be applied. The coating area 112 may include a support 146 and one or more ground wires 148 to enhance the deposition of spray 138 on the previously coated base layer.

According to the present invention, the system 100 includes a computer 150 including a computer-readable storage medium containing a computer program including instructions for executing control commands via the controller 152. In this way, the controller 152 can be made to control the operation of the spray station, heater and roller mechanism as described in accordance with the operations known in the art.

The operation of system 100 in FIG. 1 can be summarized as a series of steps in block diagram 200 as shown in FIG. Starting from step 202, the substrate material is supplied 204, in step 206 a first layer or base layer of binder, conductive carbon and active material is applied onto the substrate. Heat is applied to the non-spray side of the substrate in step 208 and may include a heater directly opposite the spray position in step 206 and / or heat to the non-spray side of the substrate as described above. , May be added after passing through the area or zone where the base layer is applied to the substrate. The spray side may then be heated in step 210, after which a first layer is formed on the substrate. In step 212, a second layer of binder, conductive carbon and active material is sprayed onto the first layer. As mentioned above, the non-spray side may be heated by a heater located directly opposite or immediately after the second spray region, as represented by the heater 140 in FIG. 1 (step 214). Heat may also be applied to the spray side (216) to bring the second layer binder into a plastic state. As suggested, the subsequent layer may be applied to the electrode layer by repeating the process described above. That is, with reference to FIG. 1, additional spray stations, such as a second coating area 112, may be included in system 100 approximately indefinitely to add additional layers. Therefore, if an additional layer is sought in step 218 (220), block diagram 200 shows a return (222) so that subsequent layers can be added. In other words, the return (222) does not represent the physical return of the part through the second coating area 112, and the system 100 has a large number of spray stations in its design to obtain the desired final thickness. It shows that it can include.

As also suggested, each subsequent spray station may contain different amounts of a spray mixture of binder, conductive carbon and active material, depending on the desired final electrode design. As is known in the art, in one example, the smallest active material particles are located closest to the substrate and the largest active material particles are located near the outer surface of the electrode within the electrode depth. It may be desirable to have a gradient. Conversely, it may be desirable to have larger particles near the substrate and smaller particles near the outer surface of the electrode. Alternatively, it may be desirable to have a uniform active material particle size throughout the electrode. Such designs are generally understood in the art and may all be formed according to embodiments of the present invention. That is, the thickness of each layer, as well as the particle size within each layer, is selected and controlled as subsequent layers are added during electrode formation so that the desired active material particle size gradient is achieved within the electrode. May be done.

There may be several advantages to being able to deposit amorphous layers with different material sizes or with different active materials in the electrodes. In one example, a solvent with a given binder by layering a larger particle size closer to the current collector and gradually layering smaller particle sizes as the electrode thickness construction moves away from the current collector. Allows for higher power and higher energy densities and cycle life compared to electrodes constructed from single, bimodal, or trimodal particle size distributions processed by the casting method. sell. The described process will also allow the binder and conductive additives to be varied as needed to optimize electrode performance for a given application. As a result, the electrode active material matrix is changed from an amorphous layer to a more or less discrete layer having excellent interfacial conductivity.

The ability to stratify without creating interfacial resistance is a major improvement over conventional solvent-based techniques and other known methods. The stratification method described in the present invention is of a type in which the interfacial resistance is not as clear as one of ordinary skill in the art would expect. In fact, the resistance or impedance is lower than expected, demonstrating that the disclosed method is superior to the solvent-based method of applying the active material to the current collector, which is a significant improvement for the art.

Next, referring to FIG. 3, the electrode 300 includes a substrate 302 corresponding to the substrate 102 of FIG. The electrode 300 may include one or more layers of the active material mixture within the binder 304 and may include a particle thickness gradient over its thickness 306, as described above. The electrode 300 is also controlled by selectively applying an appropriate number of layers and compressing the substrate and layers as the final product passes through the guide mandrel 114, as shown in FIG. It may have an overall thickness of 308. Therefore, according to the present invention, a final one-sided electrode with a thickness of 0.0005 inches (about 0.00127 cm) to 0.015 inches (about 0.0381 cm) or more can be produced. In fact, in principle, there is no limit to how thin or thick the electrodes can be. In terms of thinness, a layer as thin as a single active material size may be obtained. When it comes to thickness, the limits are based solely on the number of application stations, and perhaps on the more basic limits associated with electrochemical performance.

The principles described above in connection with FIGS. 1 and 2 can also be applied to the manufacture of bilateral electrodes. That is, the substrate can be passed through a system in which sprays are applied to both sides of the substrate and subsequent layers to deposit the active material on both sides of the substrate. Next, referring to FIG. 4, in the bilateral coating system 400, the substrate 102 can be passed through a first bilateral coating station 402 to spray the first layer on both sides of the substrate 102. The system 400 includes a heater 404 and a second spray station 406 exemplifying a station that can be used in conjunction with an additional heater 408 corresponding to each spray station 406. In other words, as in the case of the system 100 of FIG. 1, the system 400 may include a plurality of spray stations to form a plurality of subsequent layers in the construction of the bilateral electrodes. System 400 includes a heater 410 on one or both sides of the substrate that preheats the substrate to enhance the heating of the substrate prior to spraying the base layer on both sides, thereby enhancing the adhesion of the base layer to the substrate 102. It may be. The spray mechanism 412 may or may not include an electrostatic charge and may also include one or more corresponding ground wires 414. According to the present invention, the heater 410 and the spray station 412 may be staggered and offset from each other, or one heater 410 faces one spray station 412 and the other heater 410 faces the other spray. It may be positioned to face the station 412. Similarly, the second spray station 406 may or may not be electrostatically controlled and includes a spray mechanism 416 that is grounded to the substrate by a ground wire (not shown in spray station 406).

In this way, a bilateral electrode 500 having a substrate 102 and a first active material layer 502 and a second active material layer 504 formed on the substrate can be formed (see FIG. 5). As in the one-sided embodiment, the particle size gradient and overall thickness can be controlled using a compression mandrel 418 with the appropriate particle size within each spray station. Therefore, according to the present invention, a final bilateral electrode with a thickness of 0.0010 inch (about 0.00254 cm) to 0.030 inch (about 0.0762 cm) or more can be produced.

According to one embodiment, the metal belt 154 may be added to a covering system such as the system 100 of FIG. The metal belt can extend the length of the system through which the substrate is passed. That is, instead of using the individual support structures 130 and 146, a single belt may be provided to enhance ground contact within the spray area (s) as the substrate moves. .. This can be particularly interesting when low conductive materials such as thin metals, composite structures, coarse substrates, foam substrates, or non-woven substrates are used. Also, if a small production lot of electrodes is desired, with the steel belt in place, the machine is inverted to increase the thickness of the electrode active material in order to improve the final electrochemical performance. Alternatively, perhaps different active materials can be stratified. Another advantage of using a belt machine is that by using this method to create free-standing membranes of active material, these membranes require less strong bonding to the substrate or current collector in product design. It will be possible to make it usable for other purposes that are not. Belt machines will also allow faster switching of electrode types.

The double coating is by applying the active material to both sides at once (ie, FIG. 4), or by rotating the web or turning it over and repeating the one-sided coating (ie, with the back surface of the substrate 102 coated). It can be achieved by repeating the coating zone or re-passing the coating zone, whether vertical or horizontal (performing through the embodiment of FIG. 1 again). That is, although FIGS. 1 and 4 exemplify the substrate 102 that passes orthogonally to the gravitational field of the earth, according to the present invention, the substrate may be passed collinearly with the gravitational field. .. In other words, the coating system may drive the substrate vertically according to embodiments of the present invention. Other ways to do the same are to build a longer machine with more stations, or wrap and rewind the web passing in the same direction, or put the web on the machine to save space. Will bring it back. Therefore, the lithium ion electrode is manufactured without solvent and its performance is as good as the electrode conventionally made using the solvent method. The electrode can be manufactured with any known active material at any thickness and density.

Also, the electrode density is adjustable / controllable. Solvent cast electrodes usually include coining to obtain or improve performance. According to the present invention, both the imprinted electrode and the non-imprinted electrode are manufactured from this process without any apparent difference in performance. Solvent casting systems typically target an open structure of 30-40% after imprinting, with porosity returning to the 50% range by cycling and relaxation with polymer solvation. However, the process illustrated herein produces a porosity of 15% to 50% with or without secondary imprinting. Therefore, the overall cycle life is improved without solvation by imprinting and adding electrolyte. In addition, the amount of binder in the internal structure of the active material is reduced compared to solvent casting systems. In solvent casting systems, polymer binders often enter the internal structure of the active material. However, in the described process, the majority of the binder is maintained outside the active material, resulting in higher utilization of the active material compared to solvent casting systems.

In solvent cast lines, a solvent, usually N-methyl-2-pyrrolidone (NMP) or methylethylketone (MEK) or other known solvent, is usually added to the active material and then does not cause cracking or peeling of the cast electrode. Removed at speed. This typically includes a large drying oven and solvent recovery system. In some cases, solvents are used as part of the fuel to heat the furnace. Either way, the solvent must be removed, creating the need for over 200 feet (about 60.96 meters) of lengthy drying ovens and other chemical processing equipment. Removing the solvent in the casting process also reduces the possibility of contaminating the electrolyte and cells if adequate airing time is not available.

Finally, the process illustrated herein does not alter the chemistry of existing batteries. The same binders, active materials and conductive additives as in conventional solvent systems are used and no other components are added. That is, the performance of the electrodes with respect to resistance, power and attenuation is comparable to the batteries formed in solvent systems.

The processes exemplified herein are not limited to ultrathin electrodes. Electrodes with a thickness range of 0.0005 inches (about 0.00127 cm) to 0.015 inches (0.0381 cm) (one-sided electrode, about twice this thickness for two-sided electrodes) and more Is possible and is limited to some extent only by the number of stratified stations. Furthermore, this process is not limited to battery electrodes and may be extended to the production of similar separator layers, allowing full cells to be produced on one line, approaching just-in-time delivery capabilities.

According to one embodiment of the present invention, there is provided a method of forming a separator layer on an electrode utilizing the same process, binder, temperature, and operating conditions used in the solvent-free electrode coating process described above. NS. In this method, a ceramic separator is attached / formed to / on the surface of the electrode so that the ceramic separator can be bent with the electrode and rolled or cut in the same way as a typical electrode. Eliminate the need to use / manufacture different / different polyolefin separators. This method can be used with both rechargeable lithium cells or primary cells and can be placed on either or both electrodes, i.e. on the anode and / or cathode.

Next, with reference to FIG. 6, a system 600 and associated method for manufacturing and applying a battery separator on an electrode according to one embodiment is shown. In FIG. 6, the separator system 600 is integrated with a system for manufacturing electrodes (ie, system 100 in FIG. 1) by depositing a binder and an electrode active material on one side of the substrate or current collector. It should be understood that the separator system 600 can also be provided as a stand-alone system separate from the system 100, although it is shown as being. Therefore, a solvent cast electrode or a spray electrode can be subsequently provided to the system 600 for coating / forming a separator on it.

The separator system 600 provides a feed mechanism (shown in FIG. 6 as a roller / mandrel 114) that provides a completed electrode (eg, solvent cast electrode or spray electrode) in the coating area 604 of the system to which the separator layer is applied. include. The coating area is provided with a device 606 for applying a separator layer to the manufactured electrodes, which is a spray mechanism (spray gun) configured to spray a layer of material mixture 608 onto the electrodes. And other known devices that produce sprays, etc.). Generally, the device 606 is described as a spray mechanism or spray gun for applying a material onto the electrodes and is illustrated as "spray 608", but any dry dispersion coating mechanism that applies a separator layer to the electrodes. It is intended that the technique can be used. Such dry dispersion techniques used to apply the separator material may include, for example, brushing, powder coating, use of fluidized beds, doctor blade method, wiping with a waste cloth.

According to an exemplary embodiment, the device or spray mechanism 606 releases the spray 608 at about 2-20 psi. Spray 608 is a ceramic separator spray mixture composed of a binder and a non-conductive ceramic separator material. According to one embodiment of the invention, the binder may consist exclusively of a thermoplastic or thermosetting material, which in an exemplary embodiment is polyvinylidene fluoride (polyvinylidene fluoride) (polyvinylidene fluoride). PVDF) or any derivative thereof, but it is also envisioned that it could be PTFE or any derivative thereof instead. According to another embodiment of the invention, the binder is a thermoplastic or thermosetting material (such as PVDF) along with a polyolefin filler material (such as polyethylene or polypropylene) to add structural integrity to the binder. ) May be included. PVDF may range from 2 to 30% by weight of the total material in the spray 608, but the exact percentages are the surface area and pore size of the separator material and the properties of the binder as it melts or softens (ie, ie. It should be understood that it depends (partially) on (whether it also contains fillers). As is known in the art, thermoplastic resins are polymers that soften above a certain temperature and return to a solid when cooled. In contrast, and as is also known in the art, thermosetting materials form irreversible chemical bonds during the curing process and decompose upon melting (not reformed during cooling).

The ceramic separator material of the spray mixture comprises one or more ceramic powders, including one or more of alumina, magnesium oxide (MgO), aluminum oxide, tin oxide or other ceramics, and the ceramic (s). The particle size of the powder is in the range of 1 to 25 μm. It is acknowledged that other insulating ceramic materials can be used as an alternative to the above materials. As an example, a silicon dioxide (SiO ₂ ) -based material may be used, but SiO ₂ has been certified to be unstable when in contact with the negative electrode material, especially at high temperatures.

In one embodiment, the spray 608 is applied not only to the top and / or bottom (bottom surface) of the electrode, but also to the edges of the electrode. When applying the ceramic-polymer separator mixture to the edge of the electrode, the device or spray mechanism 606 overcoats the electrode to prevent a short circuit around the edge of the electrode pair and borders the edge of the electrode. It is controlled to provide a spray 608 to form. The separator overlap is typically less than 0.039 inches (about 1 mm), but the overlapping edges may be up to 0.125 inches (about 3.2 mm).

According to the present invention, the electrodes are heated to initiate bonding of the ceramic-polymer separator mixture to the electrodes. In one embodiment, the heater 610 is positioned facing the device 606 and, based on the polymer binder utilized, the heater 610 has sufficient power to raise the temperature of the electrodes to about 150 ° C to 300 ° C. Be supplied. However, in another embodiment, the heater 612 is positioned to heat the surface of the electrode opposite to the surface of the electrode to which the spray 608 is applied. Thus, according to the present invention, a layer of separator material is applied to the electrodes and coupling to the electrodes is initiated via one or both heaters 610, 612. Heaters 610, 612 can apply heat via any number of known mechanisms, including infrared (IR) heaters, convection heaters, conduction heaters, radiant heaters (eg, outside the IR spectrum) or induction heaters. The heater 610 (and optionally the heater 612) heats the binder to a certain temperature (ie, 150 ° C. to 300 ° C.) so that the polymer in the binder softens but is not heated to the point where the polymer easily flows. It works to work like that. This is because it is recognized that if the polymer flows too easily, it will enter the particle pores of the separator material and lose its adhesive strength and adhesive strength.

A separator layer is formed by applying a ceramic-polymer separator mixture onto the electrodes via spray 608 (or another suitable coating means) and performing the associated heating. As shown in FIG. 6, the separator system 600 is also designed to have a space or gap maintained during operation to provide a gapped calendar process in the separator layer after depositing and heating the spray. Includes a set of mandrel or roller 614 that has been calendered to ensure a smooth, uniform finish and thickness of the separator layer. Thus, the mandrel 614 compresses and calendars the substrate layer to the final desired consistent thickness, density, porosity and tortuosity. According to an exemplary embodiment, the target thickness of the separator layer is within the ceramic particle size, and the separator layer is ideally as thin as possible to reduce its impedance. A thickness of less than 25 μm can be achieved based on the thickness corresponding to the grain size thickness of a single particle of the ceramic separator material utilized. The specific tortuosity and porosity of the separator layer is controlled by the precise setting of spraying and subsequent calendaring.

As shown in FIG. 6, a controller 152 that controls the operation of the spray station 606, the heaters 610, 612, and the roller mechanism 614 is provided, as is known in the art and described according to the above operations. .. The controller 152 is shown as being common to both the system 100 and the separator system 600, but uses a separate controller (different from the controller associated with the system 100) to operate the separator system 600. It is understood that it can also be done.

Next, with reference to FIG. 7, a dry solvent-free method 700 for applying the battery separator onto the electrodes according to one embodiment is shown. In step 702, the electrodes are first provided and fed towards the separator coating area. Such electrodes are manufactured as solvent cast electrodes or spray electrodes (as described in detail above). In step 704, the surface of the electrode is heated by any of several known methods, including, for example, infrared (IR) heating, convection heating, conduction heating, radiant heating (eg, outside the IR spectrum) or induction heating. ..

When the electrode surface is heated, in step 706, the ceramic separator mixture is applied to the electrode by a dry solvent-free coating method, and the mixture is applied so as to cover the surface of the electrode. The ceramic separator mixture is composed of a binder and a non-conductive ceramic separator material, which are described herein as "mixtures" applied together in a single application. However, it is recognized that the ceramic binder and the ceramic separator material can also be applied by separate coatings at the same time. According to one embodiment of the invention, the binder may consist exclusively of a thermoplastic or thermosetting material, which in an exemplary embodiment is polyvinylidene fluoride (polyvinylidene fluoride) (polyvinylidene fluoride). PVDF) or any derivative thereof. According to another embodiment of the invention, the binder may be polyethylene (PE), polypropylene (PP), or fibers thereof to add structural integrity to the binder, a polyolefin filler. The material may include a thermoplastic material or a thermosetting material (such as PVDF). PVDF may range from 2 to 30% by weight of the total material in the separator mixture, but the exact percentages are the surface area and pore size of the ceramic separator material and the properties of the binder as it melts or softens (ie). It should be understood that it depends (partially) on (whether it also contains fillers).

Ceramic Separator Material of Separator Mixtures comprises one or more ceramic powders, including one or more of alumina, magnesium oxide, aluminum oxide, tin oxide or other ceramics, granules of (s) ceramic powders. The diameter is in the range of 1 to 25 μm. It is understood that other insulating ceramic materials can be used as an alternative to the above materials. According to an exemplary embodiment of the invention, the ceramic material may depend on whether the electrode to which the ceramic separator mixture is applied is a cathode or an anode. As an example, when the electrode is a cathode, the ceramic separator material may be magnesium oxide, and when the electrode is an anode, the ceramic separator material may be aluminum oxide.

In embodiments where the binder consists exclusively of PVDF (or another thermoplastic or thermosetting material), the separator mixture consists of 3% -20% PVDF and 97% -80% ceramic separator material. If the binder consists of PVDF (or another thermoplastic or thermosetting material) and filler material, the separator mixture will be 3% -15% PVDF, 5% -40% filler material (polypropylene or Polyethylene) and 45% -92% ceramic separator material.

Regarding the dry solvent-free application of the ceramic separator mixture to the electrode performed in step 706, the separator mixture is applied not only to the upper surface and / or the bottom surface of the electrode, but also to the edge of the electrode. It may be done. When the ceramic separator mixture is applied to the edges of the electrodes, the application is a spray that overcoats the electrodes to form a boundary at the edges of the electrodes to prevent short circuits around the edges of the electrode pairs. Controlled to provide.

Further referring to FIG. 7, when the dry solvent-free application of the ceramic separator mixture to the electrodes is completed, a gap-based calendering is performed in step 708 to obtain the finally desired ceramic separator. Compressed and calendered to consistent thickness, density, porosity and flexibility. The structure thus obtained provides a ceramic separator that can be bent with the electrode on the surface of the electrode, and subsequent steps of rolling and / or cutting the separator electrode obtained in step 710 , It is easy because it is similar to rolling and / or cutting a typical electrode. In addition, any optional rolling and / or cutting is obtained in step 712 to form an electrochemical cell in which both cracks and short circuits due to separator misalignment can be minimized / removed. The separator / electrode structure to be rolled up can be bonded (ie, the anode and cathode can be bonded). The electrochemical cell 800 obtained from such a junction is shown in FIG. 8, in which the anode structure 802 containing the copper current collector 804, the anode active material 806, and the ceramic separator 808 is an aluminum current collector 812, a cathode. It can be seen that it is bonded to the cathode structure 810 containing the active material 814 and the ceramic separator 816.

Advantageously, applying the ceramic-polymer separator mixture to the electrodes by the method described above provides a battery separator that exhibits improved performance over existing battery separators. The ceramic-polymer separator mixture contains a smaller amount of binder (ie, 2-30% by weight) than conventional commercially available battery separators, which means that the smaller the amount of binder, the higher the heat rise during a thermal runaway event. It is advantageous for the battery industry because it is less likely. That is, reducing the amount of polymer binder in the separator suppresses the initiation of thermal runaway by reducing the immediate energy available to initiate electrolyte decomposition, which causes the ceramic separator structure to collapse and short circuit. Is further reduced. When heated, the polymer binder is drawn into the pores of the separator material (such as MgO) and isolated from its involvement in thermal runaway reactions. Therefore, the battery separators (and methods of forming them) of the present invention reduce the likelihood of heat rise during thermal runaway events, making such events less likely, or at least for maximum catastrophic energy release. It sufficiently slows the heat rise so that it does not reach, minimizes the amount of energy the battery system needs to dissipate, and significantly improves the overall safety of the battery.

A further advantage of applying the ceramic-polymer separator mixture to the electrodes by the method described above is that such application reduces the cost of the electrode pair when assembling the battery and facilitates handling. That is, unlike the individual separators, which are slippery and require a constant tension for proper winding, the ceramic separator applied by the method described above remains attached to the electrode. As a result, alignment is performed during operations such as manufacturing jelly rolls for tubular cells and cell stacking when manufacturing square cells and pouch-shaped cells, regardless of whether they are flat-wound or utilize individual electrode components. Web control in case becomes easier.

The technical contribution of the disclosed methods and devices is to provide computer mounting methods and devices for applying battery separators to electrodes, more specifically to manufacture ceramic separators or lithium ceramic separators. For methods and devices for application to lithium electrochemical cells in ionic (Li-ion) batteries.

Those skilled in the art will appreciate that embodiments of the present invention can be interfaced with and controlled by a computer-readable storage medium containing a computer program. A computer-readable storage medium includes a plurality of components, such as one or more of electronic components, hardware components, and / or computer software components. These components generally contain instructions such as software, firmware and / or assembly language for executing one or more parts of one or more embodiments or embodiments of a sequence. Computer readable storage media may be included. These computer-readable storage media are generally non-temporary and / or tangible. Examples of such computer-readable storage media include recordable data storage media for computers and / or storage devices. The computer-readable storage medium can be, for example, one or more of magnetic, electrical, optical, biological, and / or atomic data storage media. Further, such media may take the form of, for example, floppy disks (flexible disks), magnetic tapes, CD-ROMs, DVD-ROMs, hard disk drives, and / or electronic memories. Other forms of non-temporary and / or tangible computer-readable storage media not described may be used with embodiments of the present invention.

Several such components can be combined or split in embodiments of the system. In addition, such components are a set of computer instructions and / or a set of computers written in or implemented in one of several programming languages, as will be understood by those skilled in the art. It may include instructions. In addition, when executed by one or more computers using other forms of computer-readable media, such as a carrier wave, one or more computers of one or more embodiments or embodiments of the sequence. Alternatively, a computer data signal representing an instruction sequence that executes a plurality of parts may be embodied.

According to one embodiment of the present invention, the method of applying a dry solvent-free ceramic separator to the electrode includes a step of providing the electrode in the coating region via a feed mechanism and a dry dispersion coating to the electrode with a binder and non-conductive material. A step of applying a separator layer made of a sex separator material, wherein the binder comprises at least one of a thermoplastic material and a thermosetting material, including a step of applying the separator layer.

According to another embodiment of the present invention, the method of manufacturing a battery cell including an electrode and a separator is such that a step of providing the electrode, a step of sending the electrode toward the coating region, and a separator layer are formed. It comprises a step of coating a mixture of a non-conductive ceramic separator material and a binder on an electrode in a coated area by a dry solvent-free coating method.

According to yet another embodiment of the present invention, the battery cell is an electrode and a separator layer adhered to the electrode, the separator layer having at least one of a thermoplastic material and a thermosetting material. The binder includes a binder and a non-conductive ceramic separator material, and the binder of the separator layer includes a separator layer in the range of 2 to 30% by weight.

The present specification, by way of example, discloses the invention, including the best forms, and includes the person skilled in the art making and using any device or system to perform any incorporated method. Therefore, the present invention can be carried out. The patentable scope of the present invention is defined by the claims, which may include other examples conceived by those skilled in the art. Such other examples include structural elements that do not differ substantially from the wording of the claims, or include equal structural elements that do not substantially differ from the wording of the claims. Is intended to be included in the claims.

102 Substrate 104 Feed mechanism or roller system 110, 112 First and second coating areas 300 Electrode 302 Substrate 304 Binder
500 Double-sided electrode 502 First active material layer 504 Second active material layer 604 Coating area 606 Equipment for applying a separator layer to the electrodes 800 Electrochemical cell 802 Anode structure 804 (Copper) Current collector 806 Anode active material 808 Ceramic Separator 810 Cathode Structure 812 (Aluminum) Current Collector 814 Cathode Active Material 816 Ceramic Separator

Claims (21)

It is a method of applying a dry solvent-free ceramic separator to the electrode, and the method is
With the step of providing the electrode to the coating area via the feed mechanism,
A step of applying a separator layer composed of a binder and a non-conductive separator material to the electrode by dry dispersion coating, wherein the binder is at least one of a thermoplastic material and a thermosetting material. Including, steps and
A method characterized by being equipped with. The step of heating the electrode and
A step of calendering the separator layer with a gap to form a separator layer having the desired uniform thickness, density, porosity and tortuosity.
The method according to claim 1, further comprising. The method according to claim 2, wherein the separator layer is applied and calendared so as to form a separator layer having a thickness of less than 35 μm. The method according to claim 1, wherein the binder of the separator layer is in the range of 2 to 30% by weight. The method of claim 1, wherein the binder is composed of polyvinylidene fluoride (PVDF). The method of claim 5, wherein the separator layer comprises 3% to 20% PVDF and 97% to 80% non-conductive separator material. The method of claim 5, wherein the binder further comprises a filler comprising one of polypropylene and polyethylene. The method of claim 7, wherein the separator layer comprises 3% to 15% PVDF, 5% to 40% polypropylene or polyethylene, and 45% to 92% non-conductive separator material. The method of claim 1, wherein the non-conductive separator material comprises at least one of alumina, magnesium oxide, aluminum oxide, or tin oxide. When the electrode is a cathode, the non-conductive separator material contains magnesium oxide and
When the electrode is an anode, the non-conductive separator material comprises aluminum oxide.
The method according to claim 7. The method according to claim 1, wherein the dry dispersion coating includes powder coating coating. A method of manufacturing a battery cell including an electrode and a separator.
With the steps to provide the electrodes,
The step of sending the electrode toward the coating area and
In order to form a separator layer, a step of coating a mixture of a non-conductive ceramic separator material and a binder on the electrode in the coating region by a dry solvent-free coating method, and a step of coating the electrode.
A method characterized by being equipped with. 12. The method of claim 12, wherein the step of coating the mixture on a substrate comprises powder coating the mixture of the separator material and the binder on the electrodes. The method of claim 12, wherein the binder comprises polyvinylidene fluoride (PVDF). 14. The method of claim 14, further comprising a filler comprising one of polypropylene and polyethylene. 12. The method of claim 12, wherein the ceramic separator material comprises at least one of alumina, magnesium oxide, aluminum oxide, or tin oxide. A step of heating at least one of the electrode and the separator layer in order to bond the separator layer to the electrode.
A step of calendering the separator layer with a gap to form a separator layer having the desired uniform thickness, density, porosity and tortuosity.
12. The method of claim 12. 17. The method of claim 17, wherein the separator layer is coated and calendared to form a separator layer having a thickness of less than 35 μm. The method according to claim 12, wherein the binder of the separator layer is in the range of 2 to 30% by weight. With electrodes
A battery cell provided with a separator layer adhered to the electrode.
The separator layer
A binder containing at least one of a thermoplastic material and a thermosetting material,
Non-conductive ceramic separator material and
Including
A battery cell in which the binder of the separator layer is in the range of 2 to 30% by weight. The battery cell according to claim 20, wherein the separator layer has a thickness of less than 35 μm.

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