Method of manufacturing a battery electrode assembly

Abstract

Methods of making battery electrode assemblies and methods of making batteries are described herein. The method of manufacturing a battery electrode assembly includes providing a continuous electrode workpiece and electrochemically forming a solid electrolyte interface layer on the continuous electrode workpiece. The method further includes segmenting the continuous electrode workpiece into a plurality of battery electrodes, and stacking or winding the plurality of battery electrodes and the plurality of separators.

Description

Technical Field

[0001] Embodiments of this disclosure relate to methods for manufacturing battery electrode assemblies and methods for manufacturing batteries. Background Technology

[0002] Industrial lithium-ion battery cell production typically involves steps such as slurry mixing, electrode separation, electrode stacking, cell assembly (encapsulation), electrolyte filling, cell formation, and offline testing. During cell formation and offline testing, most of the lithium ions extracted from the cathode material are consumed on the electrode surface to form a solid electrolyte interface (SEI). Current research focuses on constructing a stable and uniform SEI layer to prevent chemical decomposition throughout the battery cell's lifespan and to suppress continuous, excessive, and harmful electrolyte decomposition reactions.

[0003] However, current methods for forming SEI on electrode surfaces are time-consuming, energy-intensive, and require significant factory space / area, resulting in high costs. Furthermore, in traditional battery manufacturing, because the entire battery cell is completely sealed and assembled before the SEI formation step, direct quality control during SEI formation is impossible. SEI formation can lead to the generation of unwanted gas compositions, which either remain in the prismatic or cylindrical battery cell casing or accumulate in parallel auxiliary gas bag cavities that must be removed before final sealing of the main gas bag.

[0004] There is a persistent need for improved battery manufacturing methods. Methods are required that allow for the continuous fabrication of battery electrodes, while simultaneously reducing manufacturing costs, particularly by decreasing the energy, time, and space required to produce the electrodes. In particular, methods for forming the SEI (Sediment Injection) in a controlled and direct manner are needed. Summary of the Invention

[0005] Based on the foregoing, a method for manufacturing a battery electrode assembly according to independent claim 1 and a method for manufacturing a battery according to claim 16 are provided. Other aspects, advantages, and features will be apparent from the dependent claims, the specification, and the drawings. According to one aspect of this disclosure, a method is provided for assembling a battery electrode assembly, particularly for a lithium-ion battery. The method includes: a) providing a continuous electrode assembly; and b) electrochemically forming a solid electrolyte interface (SEI) layer on the continuous electrode assembly. Step b) includes conveying the continuous electrode assembly in a first electrochemical bath. Step b) further includes conveying the continuous electrode assembly in a second electrochemical bath. The method also includes steps c) dividing the continuous electrode assembly into a plurality of battery electrodes; and d) stacking or winding the plurality of battery electrodes and a plurality of separators. The first electrochemical bath is preferably an electrochemical battery cell in a charging mode, while the second electrochemical bath is preferably an electrochemical battery cell in a discharging mode.

[0006] The electrode workpiece can also be referred to as an electrode assembly or electrode material. The electrode workpiece can be considered as a semi-finished assembly that can be used to form the battery electrode in step c).

[0007] The term "continuous" electrode workpiece can be understood as an electrode workpiece that extends substantially along at least one dimension (e.g., along length). In other dimensions, the electrode workpiece may not extend substantially. Therefore, the electrode workpiece can be flat and / or in the form of strips or bands. The length of a continuous electrode workpiece can range from several meters, for example, between 1 meter and several hundred meters. A continuous electrode workpiece can be coated on one or both sides and can have a thickness ranging from sub-millimeter to millimeter. For example, the width of the electrode can be between 0.5 m and 3 m.

[0008] The method disclosed herein allows for the continuous execution of at least steps a) and b), but preferably all steps until the electrode workpiece is segmented according to step c). The method disclosed herein allows for continuous production without interruption of the flow production while the continuous electrode workpiece is being processed or otherwise treated. SEI formation according to step b) is performed by continuously conveying the continuous electrode workpiece through first and second electrochemical baths. It should be understood that processing steps such as drying SEI formation step b) may only affect a specific portion of the continuous electrode workpiece at a given point in time, i.e., the portion subjected to processing at that point in time.

[0009] The method disclosed herein allows for the continuous fabrication of battery electrodes, thereby reducing the time, energy, and factory volume / area required compared to existing methods. Electrode assemblies and batteries can be produced faster and at a lower cost compared to existing technologies.

[0010] Furthermore, the method described herein allows for the continuous and controlled direct formation of an SEI layer on the electrode surface before the electrode assemblies are fabricated by stacking or winding and before the battery cells are assembled. The method described herein does not require, and preferably does not include, further SEI layer formation during conventional battery cell formation and / or at the end of the battery cell production line. Therefore, the formation of unwanted gases after the battery electrode assemblies are arranged in the battery cell housing can be reduced or even completely avoided. The “early” SEI formation described herein can skip the time-consuming and costly formation steps at the end of battery cell manufacturing. Forming the SEI layer before sealing the battery housing allows for monitoring and quality control of the SEI layer formed in step b).

[0011] Transporting or moving the electrode workpiece through a first electrochemical bath (preferably an electrochemical battery cell in charging or SEI formation mode) may cause physical and / or chemical interactions between the lithium species contained in the first electrochemical bath and the electrode workpiece. Lithium ions from the first electrode bath can be introduced into the pores of the electrode workpiece, thereby forming a lithiated electrode workpiece. Furthermore, the redox reaction facilitated by the first electrochemical bath of the electrochemical battery cell may lead to the formation of a solid electrolyte interface (SEI) on the surface of the (coated) electrode workpiece. For example, this solid electrolyte interface may include a lithium organic composition.

[0012] However, the first electrochemical bath may cause the electrode workpiece to become fully charged, which is difficult to handle during manufacturing due to safety concerns. If the electrode workpiece is used directly after passing through the first electrochemical bath, there is a risk of short circuits during electrode stacking / winding and battery cell assembly, potentially leading to fires and explosions. Transporting or moving the electrode workpiece through a second electrochemical bath (preferably an electrochemical battery cell in discharge mode) advantageously allows for a significant or complete discharge of the continuous electrode workpiece, ensuring safe handling. Simultaneously, the second electrochemical bath may cause "delithiation" of the electrode workpiece. When the electrode workpiece is immersed in the first electrochemical battery cell, most or all of the lithium ions that may have permeated into the bulk material or coating of the electrode workpiece return to the second electrochemical bath, thus discharging the electrode workpiece and allowing for a significant recovery of lithium consumed in the first electrochemical bath. Advantageously, the SEI layer formed in the first electrochemical bath is likely quite stable and therefore not substantially affected in the second electrochemical bath.

[0013] The methods disclosed herein may not produce pre-lithiated electrode materials and / or require a separate pre-lithiation step. Constructing an SEI layer on the electrode workpiece before forming the electrode assembly ensures that lithium ions are not irreversibly consumed when the battery is put into service, as the formation of the SEI layer is largely or completely completed in the early stages. The SEI layer formed on the electrode surface extends cell life due to its lower aging rate.

[0014] A first electrochemical bath may be filled with a first composition comprising an electrolyte and / or an SEI-forming additive. The electrolyte may include a lithium salt and an organic component or organic solvent. Illustratively, the electrolyte may include a 1 mol / L LiPF6 salt in a solvent of a mixture of ethylene carbonate and diethyl carbonate (volume ratio 1:1). The SEI-forming additive may be an organic component or organic solvent. For example, the SEI-forming additive may be fluoroethylene carbonate (FEC) and / or vinylene carbonate (VC). The first composition allows for efficient, rapid, durable, uniform, and thickness- and integrity-controlled SEI formation. The electrolyte may include one or more components selected from the group consisting of ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, propylene carbonate, fluoroethylene carbonate, propylene carbonate, and combinations thereof. For example, electrolytes and electrolyte additives for the first composition are described in “Areview on electrolyte additives for lithium-ion batteries” published by Zhang Shengshui in November 2006 (Power Supply Journal, Vol. 162, No. 2, pp. 1379-1394).

[0015] The first and second electrochemical baths may each include multiple rollers (e.g., transport rollers) for conveying or moving the electrode workpiece through the multiple electrochemical baths.

[0016] The first and second electrochemical baths may also each include a plurality of second rollers. The plurality of second rollers are provided to remove or lift the downstream portion of the continuous electrode workpiece from the electrochemical bath, and / or to extract or extrude the (first, second) composition from the downstream portion of the continuous electrode workpiece. The plurality of second rollers may have a tensioning function.

[0017] The first and second electrochemical baths may include a counter electrode and a separator placed between the continuous electrode workpiece and the counter electrode. The counter electrode may be selected from the group consisting of pure lithium electrodes, lithium titanate (LTO) electrodes, and lithium iron phosphate (LFP) electrodes. Preferably, the counter electrode is a lithium titanate electrode. The electrode workpiece may be coated on both sides. In one embodiment, the first and / or second electrochemical bath may include two counter electrodes and two separators. A separator and a counter electrode may be provided on each side of the electrode workpiece. The separator and / or counter electrode may be continuous. The separator may be continuous, and the electrochemical bath may include a plurality of spaced-apart discontinuous counter electrodes. Having a plurality of spaced-apart discontinuous counter electrodes simplifies production while simulating a continuous electrochemical cell cell capable of operating in a continuous feed mode.

[0018] The second electrochemical bath may be filled with a second composition. The second composition may be the same as the first composition, but preferably different. The second composition may not include SEI-forming additives. The second composition may include an electrolyte. The electrolyte may be the same as the electrolyte used in the first composition. This electrolyte may include lithium salts and organic components or organic solvents. Illustratively, the electrolyte may include a 1 mol / L LiPF6 salt in a solvent of a mixture of ethylene carbonate and diethyl carbonate (volume ratio 1:1). In addition to the advantages mentioned above, the second electrochemical bath and the second composition can also serve as an electrolyte and cleaning solution. This allows the rinsing away of harmful or detrimental components or decomposition products that may form in the first electrochemical bath and may adhere to or adsorb onto the surface of the electrode workpiece. Electrolytes and electrolyte additives for the first and second compositions are described in “A review of one electrolyte additives for lithium-ion batteries” published by Zhang Shengshui in November 2006 (Power Supply Journal, Vol. 162, No. 2, pp. 1379-1394).

[0019] Furthermore, the method may include conveying or moving the electrode workpiece through two or more electrochemical baths, or conveying or moving the electrode workpiece through the first and second electrochemical baths multiple times. This ensures the formation of a sufficiently thick and uniform SEI layer.

[0020] For example, the method may include conveying a continuous electrode workpiece in a third electrochemical bath. The third electrochemical bath may be an electrochemical battery cell in a charging mode. The third electrochemical bath may be filled with a third composition comprising an electrolyte and an SEI forming agent. Preferably, the third composition differs from the first composition. The method may further include subsequently conveying the continuous electrode workpiece in a fourth electrochemical bath. The fourth electrochemical bath may be an electrochemical battery cell in a discharging mode.

[0021] Additionally or alternatively, the method may include conveying or moving the electrode workpiece through a cleaning bath or a plurality of wetted rollers. These rollers may be soaked in a cleaning agent. The cleaning bath or the plurality of wetted rollers may allow the rinsing away of harmful or detrimental components or decomposition products that may have formed in the first or second electrochemical bath and may have adhered to or adsorbed onto the surface of the electrode workpiece. This step may be performed after conveying the electrode workpiece through the first electrochemical bath, preferably after conveying the electrode workpiece through the second electrochemical bath.

[0022] The method may further include establishing electrical connections with the counter electrode of the first electrochemical bath and the continuous electrode workpiece. An SEI layer can be formed on the continuous electrode workpiece by supplying voltage to the electrode workpiece and the first electrochemical bath (particularly the counter electrode of the first electrochemical bath). The electrical connection with the electrode workpiece can be established in the uncoated portion of the electrode workpiece.

[0023] The method may further include establishing an electrical connection with the counter electrode and the continuous electrode workpiece of the second electrochemical bath. This allows the continuous electrode workpiece to be at least partially discharged. The electrical connection can be established in the uncoated portion of the electrode workpiece.

[0024] Step b) may further include feeding the discharge energy generated in the second electrochemical bath back to the first electrochemical bath. Advantageously, the discharge energy from the second electrochemical bath can be recovered. This discharge energy can be fed back to perform electrochemical treatment in the first electrochemical bath. Additionally, a power supply network can be provided to supply additional energy for performing electrochemical treatment in the first electrochemical bath. Advantageously, step b) can be performed with relatively limited energy consumption.

[0025] According to an embodiment, the method further includes exchanging or interchangeably using the counter electrodes(s) of a first electrochemical bath and the counter electrodes(s) of a second electrochemical bath. The counter electrodes(s) in the first electrochemical bath may initially be lithium-rich, and the lithium in these counter electrodes(s) can gradually dissolve into the solution. On the other hand, the counter electrodes(s) in the second electrochemical cell may initially be lithium-poor, and lithium can gradually accumulate on these counter electrodes(s). Benefitingly, lithium can be recovered by exchanging the counter electrodes, thereby limiting lithium consumption. In another embodiment, the first and second electrochemical baths comprise the same composition. Instead of exchanging or interchangeably using the counter electrodes, the first electrochemical bath and the second electrochemical bath(s) can be exchanged.

[0026] After the counter electrode has reached a predetermined operating time, or alternatively, when the ratio of lithium extracted from the counter electrode in the first bath electrode to lithium accumulated in the counter electrode in the second bath electrode exceeds a predetermined value, the following operations may be performed: exchanging the counter electrodes of the first electrochemical bath and the second electrochemical bath with each other; and / or exchanging the first and second electrochemical baths with each other.

[0027] According to another embodiment, the counter electrode is a continuous counter electrode. A continuous counter electrode may include a plurality of conductive portions spaced apart along its length direction (movement direction). A continuous counter electrode may include a plurality of insulating portions spaced apart between each pair of adjacent conductive portions.

[0028] The method may include repeatedly feeding a continuous counter electrode from a first electrochemical bath to a second electrochemical bath. Optionally, the method may include repeatedly feeding a counter electrode from a second electrochemical bath to a first electrochemical bath. The method may include means for providing and feeding the continuous counter electrode. This means may be configured to, particularly directly or at a later point in time, remove the continuous counter electrode from the first (second) electrochemical bath and immerse the continuous counter electrode in the second (first) electrochemical bath. The means may include multiple rollers for feeding the counter electrode from the second electrochemical bath to the first electrochemical bath. Advantageously, lithium consumption can be limited by repeatedly consuming and accumulating lithium on the continuous counter electrode.

[0029] According to another embodiment, the plurality of first and / or second electrochemical baths include solvated lithium. In this embodiment, the solvated lithium in the plurality of electrochemical baths can serve as a counter electrode. A diaphragm can be provided, which can serve as an isolation layer. The diaphragm can be configured to allow lithium ions to pass through but prevent the passage of electrolyte or solvent. In this embodiment, the solvated lithium can be pumped from the second electrochemical bath to the first electrochemical bath. Advantageously, lithium consumption can be limited by repeatedly replenishing the lithium consumed in the first electrochemical bath from the second electrochemical bath (in which lithium accumulates).

[0030] Method step b) can be performed in a controlled environment. For example, method step b) can be performed in a drying chamber used for battery assembly, preferably wherein the drying chamber has low humidity and / or is explosion-proof.

[0031] According to an embodiment, the method includes: e) using one or more sensors to record a signal associated with an SEI layer formed on an electrode portion of a continuous electrode workpiece; using a controller to analyze the signal to determine quality control parameters associated with the quality of the SEI layer formed on the electrode portion; and determining quality conditions based on a comparison between the quality control parameters and predetermined threshold parameters.

[0032] Typically, quality control according to step e) allows for the evaluation of the SEI formed on a specific portion (electrode portion) of the continuous electrode workpiece. Step e) can be performed during and / or after step b). Step e) can be performed at several time points, which allows for monitoring of the progress of the SEI layer formed on the electrode portion of the continuous electrode workpiece. For example, signals can be recorded using sensors after the electrode portion is removed from the first electrochemical bath or during removal. Additionally or alternatively, signals can also be recorded using sensors before the electrode portion is immersed in the first electrochemical bath and / or after removal from the second electrochemical bath. The formation of the SEI layer can occur entirely or primarily while the electrode workpiece is in an electrochemical cell cell (such as the first electrochemical bath) in a charging mode.

[0033] The method disclosed herein includes forming an SEI layer before sealing the battery casing, which allows for direct monitoring or inspection of the SEI layer formed in step b). In prior art methods, the quality of the formed SEI layer can only be inspected indirectly by determining the decrease in usable capacity after the battery is fully assembled and put into use. The method disclosed herein allows for investigation of the SEI layer formed on the electrode portions even before the battery assembly is manufactured. Therefore, the method disclosed herein allows for the use of only portions of a continuous electrode workpiece that include a satisfactory SEI layer, thereby reducing waste during the manufacturing process.

[0034] Any type of signal that allows for the assessment of SEI layer quality can be recorded. This signal can be obtained by examining the surface of the electrode portion of a continuous electrode workpiece, or inferred from other parameters associated with SEI formation. For example, SEI formation may affect the first composition in the first electrochemical bath by reducing the lithium ion concentration in the first composition, or by the appearance of decomposition products formed through interaction with the (coated) electrode workpiece.

[0035] In one embodiment, recording signals using one or more sensors includes recording images of the surface of the electrode portion using an image sensor. Forming an SEI layer on the electrode portion may alter the visual appearance of the electrode workpiece. SEI formation can be verified based on images recorded by a camera. For example, the color of the electrode workpiece may change during SEI formation. The method may also include analyzing the images to determine quality control parameters associated with the visual appearance (preferably color) of the electrode portion's surface. For example, a control system including a processing circuitry system can be used to evaluate the color of the electrode portion's surface. This quality control parameter may correspond to parameters in a color space.

[0036] Alternatively or additionally, the signal may be selected from the group consisting of: electrochemical impedance signal, lithium ion concentration signal in the first composition, lithium concentration signal associated with the surface of the electrode portion, and combinations thereof.

[0037] This method may include evaluating the quality of the formed SEI layer using at least two different methods. For example, the method may include: recording an image of the surface of the electrode portion using an image sensor; and analyzing the image to determine quality control parameters associated with the appearance (preferably color) of the surface of the electrode portion. Additionally, the method may include recording a second signal using a second sensor, the second signal being selected from the group consisting of: an electrochemical impedance signal, a lithium ion concentration signal in the first composition, a lithium concentration signal associated with the surface of the electrode portion, and combinations thereof. The method may also include using a controller to analyze the second signal to determine a second quality control parameter associated with the quality of the SEI layer formed on the electrode portion.

[0038] The predetermined threshold parameter can be a value that indicates whether the quality of the formed SEI is sufficient for further use in steps c) and d). The quality control parameter determined by the controller can be compared with the predetermined threshold parameter to determine whether the quality condition is met.

[0039] Preferably, the quality control according to step e) is performed automatically. The quality control according to step e) can be performed during or, optionally, in real time after step b) and / or multiple times. For example, visual inspections can be performed multiple times during step b), and / or electrochemical impedance signals can be measured multiple times during step b). The method may also include outputting quality conditions and / or quality control parameters. For example, the method may also include displaying the quality conditions and / or quality control parameters on a screen. Additionally or alternatively, the method may issue an alarm if the quality conditions are not met. The method may include transmitting the quality conditions and / or quality control parameters to an external device.

[0040] In one embodiment, if the quality condition is met, step e) includes further proceeding to step c).

[0041] If the quality condition is not met, the method may include repeating step b). Step b) may be repeated until the quality condition is met, or may be repeated a maximum of a predetermined number of times.

[0042] Alternatively, if the quality conditions are not met, the method may include marking or labeling the electrode portions so that they are not used in step c). For example, after the segmentation in step c), electrode portions that do not meet the quality conditions may be picked out and not used to form the electrode assembly in step d).

[0043] If the quality conditions are not met, the method may include conveying a continuous electrode workpiece in a third electrochemical bath. The third electrochemical bath may be an electrochemical cell in a charging mode. The third electrochemical bath may be filled with a third composition comprising an electrolyte and an SEI forming agent. Preferably, the third composition differs from the first composition. The method may further include subsequently conveying the continuous electrode workpiece in a fourth electrochemical bath.

[0044] The electrode workpiece provided in step a) is preferably an electrode workpiece for a lithium-ion electrode assembly or a lithium-ion battery. This electrode workpiece may correspond to an anode workpiece for forming an anode or a cathode workpiece for forming a cathode. Preferably, the electrode workpiece corresponds to an anode workpiece for forming an anode, and more preferably, it corresponds to an anode workpiece for forming a graphite anode.

[0045] The method for manufacturing battery electrode assemblies disclosed herein can be used to form multiple anodes and cathodes. Steps a) to c) of the method disclosed herein can be performed individually for each of the continuous anode and continuous cathode workpieces.

[0046] The method may include:

[0047] a) Provide continuous cathode workpieces and continuous anode workpieces;

[0048] b) Electrochemically forming a solid electrolyte interface (SEI) layer on a continuous cathode workpiece and electrochemically forming a solid electrolyte interface (SEI) layer on a continuous anode workpiece;

[0049] c) Divide the continuous cathode workpiece into multiple battery cathodes; and divide the continuous anode workpiece into multiple battery anodes.

[0050] Steps a) through c) can be performed according to any of the embodiments described herein. The continuous cathode workpiece and the continuous anode workpiece can be transported in the same first and second electrochemical baths, or they can be transported in different and separate first and second electrochemical baths (first, second, third and fourth electrochemical baths).

[0051] The method may also include step d): stacking or winding multiple battery anodes, multiple separators, and multiple battery cathodes.

[0052] Step a) of providing a continuous electrode workpiece may include one or more sub-steps as described in more detail below.

[0053] Step a) may include sub-step a1): providing a blank continuous electrode workpiece. If the continuous electrode workpiece is a continuous cathode workpiece, the blank continuous cathode workpiece may be formed of aluminum (Al). If the continuous electrode workpiece is a continuous anode workpiece, the blank continuous anode workpiece may be formed of copper (Cu).

[0054] Step a) may include sub-step a2): producing a slurry. Sub-step a2) may be performed before, during, or after sub-step a1). The slurry may include an active component for forming an anode or cathode. If the continuous electrode workpiece is a continuous cathode workpiece, the active component may be LiCoO2. If the continuous electrode workpiece is a continuous anode workpiece, the active component may preferably be graphite. The slurry may also include one or more of conductive additives (e.g., carbon black), polymer binders (e.g., PVDF), and solvents (e.g., NMP, water), preferably all of them.

[0055] Step a) may include sub-step a3): coating a blank continuous electrode workpiece with a slurry. The continuous electrode workpiece may be coated on one or both sides, and / or its thickness may be in the sub-millimeter to millimeter range.

[0056] In one embodiment, the method includes: after step b), repeating at least steps a3) and b), but optionally also including one or more other steps disclosed herein. Repeating the above steps can accelerate the formation of the overall SEI and is particularly beneficial for high-energy electrodes.

[0057] The method may further include step f): heating the continuous electrode workpiece. Heating step f) can be considered a first or initial drying step to reduce the water content of the continuous electrode workpiece and, in particular, to cure the coating. Preferably, step f) is performed before SEI formation step b). Alternatively, step f) can be considered part of step a), corresponding to sub-step a4). Preferably, step f) is performed after step a), particularly after sub-step a3). For example, the method may include a coating line for performing sub-step a3), and the furnace may be equipped with this coating line. Alternatively, heating step f) can be performed by means of infrared radiation or hot air purging. Heating or drying step f) allows for a reduction in residual moisture content in the electrode workpiece, which would otherwise react with other components (such as lithium components) used in step b) and result in the loss of lithium components. Therefore, step f) promotes SEI formation in step b).

[0058] The method may further include step g): rolling a continuous electrode workpiece. Preferably, step g) may be performed before step b) and / or after steps a) and f). Alternatively, step g) may be considered as part of step a), corresponding to sub-step a5). Sub-step a5) may be performed after sub-step a4).

[0059] The method may further include step h) drying the continuous electrode workpiece. Step h) may be a second drying step. The second drying step may be performed after step f) and before step b). The second drying step may be performed after step g). In one example, the second drying step is based on vacuum drying.

[0060] The method may further include step i) coating the continuous electrode workpiece with an electrolyte. Step i) may be performed after step b) and before step d). Step i) may be performed before or after step c). Step i) may include temperature-controlled electrolyte fixation of the coating on the electrode workpiece, for example, by freezing or partial freezing.

[0061] In some embodiments, step c) may also be referred to as slitting the continuous electrode workpiece into multiple battery electrodes. In step c), the continuous (and dried) electrode workpiece may be slit such that the resulting electrodes are appropriately sized for direct use in the preparation of the electrode assembly in step d).

[0062] Step d) includes forming a battery electrode assembly. The battery electrode assembly can be used directly to form a battery without requiring further processing steps. Step d) may include forming a battery electrode stack by stacking multiple electrodes and multiple separators. The battery electrode stack may include several cathodes and anodes. As further described above, the method may be performed to form multiple cathodes or multiple anodes, or it may be performed to form multiple cathodes and multiple anodes.

[0063] According to another aspect of this disclosure, a method for manufacturing a battery electrode assembly, particularly for lithium-ion batteries, is provided. The method includes: a) providing a continuous electrode workpiece; b) forming a solid electrolyte interface (SEI) layer on the continuous electrode workpiece; wherein step b) includes at least one selected from the group consisting of electrochemical, chemical, and mechanically forming the solid electrolyte interface (SEI) layer. The method further includes: e) recording a signal associated with the SEI layer formed on an electrode portion of the continuous electrode workpiece using one or more sensors; and analyzing the signal using a controller to determine quality control parameters associated with the quality of the SEI layer formed on the electrode portion; and determining quality conditions based on a comparison between the quality control parameters and predetermined threshold parameters. The method further includes: c) dividing the continuous electrode workpiece into a plurality of battery electrodes; and d) stacking or winding the plurality of battery electrodes and a plurality of separators.

[0064] Each of steps a) through e) can be performed according to any aspect or embodiment described herein. Similarly, a method according to this aspect may include any optional steps described above with respect to the foregoing aspects of this disclosure (such as each of steps f) through i).

[0065] According to another aspect of this disclosure, a method for manufacturing a battery, particularly a lithium-ion battery, is provided. The method includes A) manufacturing a battery electrode assembly according to any embodiment of the present disclosure; and B) arranging the battery electrode assembly in a battery cell housing.

[0066] The method may further include step C) filling the battery cell housing with a liquid mixture comprising a battery electrolyte solvent. The battery electrolyte solvent may be selected from the group consisting of ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, propylene carbonate, fluoroethylene carbonate, propylene carbonate, and combinations thereof. Step C) may be performed after step B). The liquid mixture may also include other electrolyte co-solvents and / or salts (e.g., LiPF6).

[0067] The method may also include completing the battery cell formation, such as sealing the battery cell housing and establishing all electrical connections.

[0068] This method may also include performing offline tests.

[0069] The method described herein allows for the controlled, direct formation of an SEI layer on the surface of the electrodes in a continuous manner, prior to the production of electrode assemblies via stacking or winding and before the battery cells are assembled. The method described herein does not require, and preferably does not include, further formation of the SEI layer during battery cell formation and / or off-line testing. Therefore, the formation of unwanted gases after the battery electrode assemblies are arranged in the battery cell housing can be reduced or even completely avoided.

[0070] Other features and advantages will be recognized by those skilled in the art after reading the following detailed description and reviewing the accompanying drawings. Attached Figure Description

[0071] The components in the accompanying drawings are not necessarily drawn to scale, but rather the emphasis is on illustrating the principles of the invention. Furthermore, in the drawings, the same reference numerals designate corresponding parts. The drawings relate to embodiments of this disclosure and are described below:

[0072] Figure 1 A schematic diagram of a first electrochemical bath according to an embodiment described herein is shown;

[0073] Figure 2 A schematic diagram of a second electrochemical bath according to an embodiment described herein is shown;

[0074] Figure 3 A schematic diagram of a first electrochemical bath and a second electrochemical bath according to embodiments described herein is shown;

[0075] Figure 4 A schematic diagram of a first electrochemical bath and a second electrochemical bath according to another embodiment described herein is shown;

[0076] Figure 5 A schematic diagram of a first electrochemical bath and a second electrochemical bath according to embodiments described herein is shown;

[0077] Figure 6 A schematic diagram of a first electrochemical bath and a second electrochemical bath according to another embodiment described herein is shown;

[0078] Figure 7 A schematic diagram of a series of counter electrodes according to an embodiment described herein is shown. Detailed Implementation

[0079] Reference will now be made to various embodiments, one or more examples of which are illustrated in each of the accompanying drawings. Each example is provided by way of explanation and is not intended to be limiting. For example, features illustrated or described as part of one embodiment may be used in or in combination with any other embodiment to produce yet another embodiment. This disclosure is intended to include such modifications and variations.

[0080] In the following description of the accompanying drawings, the same reference numerals refer to the same or similar components. Generally, differences are described only with respect to individual embodiments. Unless otherwise stated, the description of a part or aspect in one embodiment may also be applied to the corresponding part or aspect in another embodiment.

[0081] Example reference Figure 1 The first electrochemical bath 110 is described. The first electrochemical bath 110 includes a housing that defines a bath containing a first composition.

[0082] The first electrochemical bath 110 also includes a plurality of first rollers 101A-101I for conveying or moving the continuous electrode workpiece 130 through the first electrochemical bath 110. The plurality of first rollers 101A-101I can be arranged in the first electrochemical bath 110 such that the electrode workpiece 130 is moved in an approximately sinusoidal manner.

[0083] The first electrochemical bath 110 also includes a plurality of second rollers 103A-103B. The plurality of second rollers 103A-103B may be provided to remove or lift the downstream portion of the continuous electrode workpiece 130 from the first electrochemical bath 110, and / or extract or extrude the first composition and other components in the composition (such as excess lithium ions, decomposition products, etc.) from the downstream portion of the continuous electrode workpiece 130.

[0084] The first electrochemical bath 110 also includes a plurality of (non-continuous) counter electrodes 132 spaced apart from each other. The counter electrodes 132 are placed on both sides of the continuous electrode workpiece 130.

[0085] The first electrochemical bath 110 also includes two continuous diaphragms ( Figure 1 (Not visible in the image), one of the diaphragms is placed between the continuous electrode workpiece 130 and the counter electrode 132. However, the diaphragm can also be discontinuous.

[0086] The first electrochemical bath 110 may also include a sensor 170 for recording signals associated with the SEI layer formed on the electrode portion of the continuous electrode workpiece. The sensor 170 allows for evaluation of the quality of the formed SEI layer. Figure 1In the illustrated embodiment, sensor 170 is a camera used to record images of the electrode portion. Color changes can indicate whether the SEI layer has been sufficiently formed.

[0087] Example reference Figure 2 The description includes a second electrochemical bath 120 according to an embodiment. The second electrochemical bath 120 includes a housing that defines a bath containing a second composition.

[0088] The second electrochemical bath 120 also includes a plurality of first rollers 102A-102I for conveying or moving the continuous electrode workpiece 130 through the second electrochemical bath 120. The plurality of first rollers 102A-102I can be arranged in the second electrochemical bath 120 such that the electrode workpiece 130 is moved in an approximately sinusoidal manner.

[0089] The second electrochemical bath 120 also includes a plurality of second rollers 104A-104B. The plurality of second rollers 104A-104B may be provided to remove or lift the downstream portion of the continuous electrode workpiece 130 from the second electrochemical bath 120, and / or extract or extrude the first composition and other components in the composition (such as excess lithium ions, decomposition products, etc.) from the downstream portion of the continuous electrode workpiece 130.

[0090] The second electrochemical bath 120 also includes a plurality of (discontinuous) counter electrodes 133 spaced apart from each other. The counter electrodes 133 are placed on both sides of the continuous electrode workpiece 130.

[0091] The second electrochemical bath 120 also includes two continuous diaphragms ( Figure 2 (Not visible in the middle), one of the diaphragms is placed between the continuous electrode workpiece 130 and the counter electrode 133.

[0092] Example reference Figure 3 The document describes first and second electrochemical baths 110 and 120 according to an embodiment. An electrical connection is provided to connect the second electrochemical bath 120 to the first electrochemical bath 110. The second electrochemical bath is an electrochemical battery cell in a discharge mode, while the first electrochemical bath 110 is an electrochemical battery cell in a charging mode. Discharge energy generated from the second electrochemical bath 120 is fed back to the first electrochemical bath 110 to perform electrochemical processing in the first electrochemical bath 110. Additionally, a power supply network 160 is provided to supply additional energy for the electrochemical processing performed in the first electrochemical bath 110.

[0093] Figure 4An example embodiment is illustrated by switching counter electrodes 132 and 133 back and forth between first and second electrochemical baths 110 and 120. The initially lithium-rich counter electrode 132 in the first electrochemical bath 110 gradually becomes lithium-depleted over time, while the initially lithium-depleted counter electrode 133 in the second electrochemical bath 120 gradually becomes lithium-rich over time. Therefore, the method disclosed herein may include exchanging or swapping counter electrodes back and forth between the first and second electrochemical baths 110 and 120. This swapping can be performed many times, such as hundreds or even thousands of times.

[0094] Figure 5 An example embodiment using continuous counter electrodes 232 is illustrated. Continuous electrode workpieces 130 are conveyed through a first electrochemical bath 110 by rollers 101A-101C, and then further conveyed through a second electrochemical bath 120 by rollers 102A-102C. The method includes means 140 for providing and conveying continuous counter electrodes 232. Means 140 is rotatable about a central axis. The means may also include a pair or more pairs of rollers 141, 142, which allow conveying continuous counter electrodes 232 and / or winding and unwinding of the counter electrodes 232. The counter electrodes 232 can be used in the first electrochemical bath 110 and then directly reused in the second electrochemical bath 120. Alternatively, the counter electrodes can be wound up after use in the first electrochemical bath 110 and used in the second electrochemical bath 120 at a later time. In this embodiment, several continuous counter electrodes 232 can be used.

[0095] Figure 6 Another exemplary embodiment using a continuous counter electrode 232 is illustrated. A continuous electrode workpiece 130 is conveyed through a first electrochemical bath 110 by rollers 101A-101C, and then further conveyed through a second electrochemical bath 120 by rollers 102A-102C. In this embodiment, preferably only one continuous counter electrode 232 is used. The method includes conveying the continuous counter electrode 232 from the first electrochemical bath 110 to the second electrochemical bath 120, and then further conveying the continuous counter electrode 232 from the second electrochemical bath 120 back to the first electrochemical bath 110. The method may include multiple rollers (not shown) for conveying the counter electrode 232.

[0096] Figure 7 An exemplary embodiment of the continuous counter electrode 332 is illustrated. Figure 7 It depicts the section along line AA. Figure 6 A portion of the counter electrode. A series of counter electrodes 332 may include a plurality of conductive portions 333 spaced apart along the length of the series of counter electrodes 332. A series of counter electrodes 332 may include a plurality of insulating portions 334 between each pair of adjacent conductive portions 333.

[0097] Although the above description pertains to embodiments, other and more embodiments may be conceived without departing from the basic scope defined by the following claims.

[0099] Figure Labels

[0100] 101A-101I Multiple First Rollers

[0101] 102A-102C Multiple First Rollers

[0102] Multiple second rollers, 103A and 103B

[0103] Multiple second rollers, 104A and 104B

[0104] 110 First Electrochemical Bath

[0105] 120 Second Electrochemical Bath

[0106] 130 Continuous Electrode Workpiece

[0107] 131 Diaphragm

[0108] Electrode pairs 132, 133, 232, and 332

[0109] 140 devices

[0110] 141 First roller for counter electrode

[0111] 142 Second roller for counter electrode

[0112] 160 power supply network

[0113] 161 Electrical Connections

[0114] 170 sensor

[0115] 333 Conductive Part

[0116] 334 Insulation Part

Claims

1. A method for manufacturing a battery electrode assembly, particularly a battery electrode assembly for a lithium-ion battery, the method comprising: a) Provide a continuous electrode workpiece (130); b) An electrochemically formed solid electrolyte interface (SEI) layer is formed on the continuous electrode workpiece (130); Step b) includes conveying the continuous electrode workpiece (130) in a first electrochemical bath (110), which is preferably an electrochemical battery cell in a charging mode; and step b) further includes conveying the continuous electrode workpiece (130) in a second electrochemical bath (120), which is preferably an electrochemical battery cell in a discharging mode. c) Dividing the continuous electrode workpiece (130) into a plurality of battery electrodes; and d) Stack or wind the plurality of battery electrodes and the plurality of separators.

2. The method according to claim 1, wherein the first electrochemical bath (110) is filled with a first composition comprising an electrolyte and an SEI forming additive.

3. The method according to any one of the preceding claims, wherein the first electrochemical bath (110) comprises a counter electrode (132) and a diaphragm (131) disposed between the continuous electrode workpiece (130) and the counter electrode (132); and particularly, wherein step b) further comprises supplying a voltage to the counter electrode (132) and the continuous electrode workpiece (130) to form an SEI layer on the continuous electrode workpiece (130).

4. The method according to any one of the preceding claims, wherein the second electrochemical bath (120) comprises a counter electrode (133) and a diaphragm (131) placed between the continuous electrode workpiece (130) and the counter electrode (133); and particularly, wherein step b) further comprises establishing an electrical connection with the counter electrode (133) and the continuous electrode workpiece (130) of the second electrochemical bath (120) to at least partially discharge the continuous electrode workpiece.

5. The method according to any one of the preceding claims further includes exchanging the counter electrode (232) of the first electrochemical bath (110) and the counter electrode (233) of the second electrochemical bath (120) with each other.

6. The method according to any one of claims 1 to 4, wherein step b) further comprises repeatedly conveying the counter electrode (132) from the first electrochemical bath (110) to the second electrochemical bath (120), and optionally repeatedly conveying the counter electrode (132) from the second electrochemical bath (120) to the first electrochemical bath (110).

7. The method according to any one of the preceding claims, wherein step b) further includes feeding the discharge energy generated by the second electrochemical bath (120) to the first electrochemical bath (110).

8. The method according to any one of the preceding claims further includes the step of: e) Using one or more sensors to record signals associated with the SEI layer formed on the electrode portion of the continuous electrode workpiece (130); using a controller to analyze the signals to determine quality control parameters associated with the quality of the SEI layer formed on the electrode portion; and determining quality conditions based on a comparison between the quality control parameters and predetermined threshold parameters. Step e) is performed during and / or after step b) and before step d).

9. The method of claim 8, wherein if the quality condition is met, the method further includes step c); otherwise: i) Repeat step b); or ii) Mark the electrode portion as not for use in step c).

10. The method of claim 8 or 9, wherein recording the signal using one or more sensors includes recording an image of the surface of the electrode portion using an image sensor (160); and The image is analyzed to determine quality control parameters associated with the visual appearance of the surface of the electrode portion, preferably color.

11. The method according to any one of claims 8 to 10, wherein the signal may be selected from the group consisting of: an electrochemical impedance signal, a lithium ion concentration signal in the first composition, a lithium concentration signal associated with the surface of the electrode portion, and combinations thereof.

12. The method according to any one of the preceding claims further includes the step of: f) Heating (514) the continuous electrode workpiece (130); Step f) is executed after step a), and preferably before step b).

13. The method according to any one of the preceding claims further includes the following step: g) Rolling (515) Continuous electrode workpiece (130); Step g) is executed before step b), and preferably after step f).

14. The method according to any one of the preceding claims further includes the step of: h) Drying the continuous electrode workpiece (130) by conveying a stream of the hydrophilic drying composition through the continuous electrode workpiece (130), wherein the hydrophilic drying composition preferably comprises a battery electrolyte solvent; Step h) is executed before step b), and preferably after step f).

15. The method according to any one of the preceding claims, wherein step b) further comprises: The downstream portion of the continuous electrode workpiece (130) is removed from one of the electrochemical baths (110, 120), and the composition is extracted from the continuous electrode workpiece (130) by means of multiple rollers (103A, 103B).

16. A method of manufacturing a battery, particularly a lithium-ion battery, the method comprising the steps of: A) To manufacture the battery electrode assembly according to any one of the preceding claims; B) Arrange the battery electrode stack in the battery cell housing.

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