Method of manufacturing a battery electrode assembly

Abstract

A method of manufacturing a battery electrode assembly and a method for manufacturing a battery are described herein. The method of manufacturing the battery electrode assembly includes providing a continuous electrode workpiece and electrochemically forming a solid electrolyte interphase layer on the continuous electrode workpiece. The method further includes partitioning the continuous electrode workpiece into a plurality of battery electrodes, and stacking or winding the plurality of battery electrodes and a plurality of separators.

Description

METHOD OF MANUFACTURING A BATTERY ELECTRODEASSEMBLYTECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to a method of manufacturing a battery electrode assembly and a method for manufacturing a battery.BACKGROUND

[0002] Industrial lithium ion battery cell production usually includes the steps of slurry mixing, electrode separation, electrode stacking, cell assembly (packaging), electrolyte filling, cell formation and end of line tests. In the steps of cell formation and end of line tests, a substantial portion of lithium ions extracted from the cathode material is consumed to form a solid electrolyte interface (SEI) on the surface of the electrodes. Current research is directed to build a stable and uniform solid electrolyte interphase layer to protect electrodes from chemical decomposition and ongoing excessive and detrimental electrolyte decomposition during the entire lifetime of the battery cell.

[0003] However, the current methods for forming the SEI on the surface of the electrodes are time, energy and factory volume / area consuming and therefore expensive. In addition, SEI formation quality control is not feasible in a direct manner as the entire cell is fully closed and finished before the SEI formation step takes place in conventional battery manufacturing. SEI formation can result in unwanted gas specifies emerging, which then eitherremain in the cell hull in case of a prismatic or cylindrical cell hull or are collected in a parallel pouch volume, which then has to be cut away before finalising the main pouch.

[0004] There is a continuous demand for improved battery manufacturing methods. There is a need for methods which allow for manufacturing battery electrodes in a continuous manner while reducing costs of manufacture, in particular by reducing the required energy, the required time as well the required space for manufacturing battery electrodes. In particular, there is a need for methods of forming a SEI in a controllable and direct manner.SUMMARY

[0005] In light of the above, a method of manufacturing a battery electrode assembly according to independent claim 1 and a method for manufacturing a battery according to claim 16 is provided. Further aspects, advantages, and features are apparent from the dependent claims, the description, and the accompanying drawings.

[0006] According to an aspect of the present disclosure, a method of manufacturing a battery electrode assembly, in particular for a lithium-ion battery, is provided. The method includes a) providing a continuous electrode workpiece and b) electrochemically forming a solid electrolyte interphase (SEI) layer on the continuous electrode workpiece. Step b) includes conveying the continuous electrode workpiece in a first electrochemical bath. Step b) further includes conveying the continuous electrode workpiece in a second electrochemical bath. The method further includes c) partitioning 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. The first electrochemical bath is preferably an electrochemical cell in a charge mode, while the second electrochemical bath is preferably an electrochemical cell in a discharge mode.

[0007] The electrode workpiece may also be referred to as electrode component or electrode material. The electrode workpiece may be regarded as a semi-finished component, which can be used to form the battery electrode in step c).

[0008] The term “continuous” electrode workpiece may be understood such that the electrode workpiece extends substantially along at least one dimension (e.g. along a length). In other dimensions, the electrode workpiece may not be substantially extended. The electrode workpiece may therefore be flat and / or have the form of a strip or band. A length of the continuous electrode workpiece may be in the range of meters, for example between 1 m and several 100 m. The continuous electrode workpiece may be single- or double-side coated and have a thickness in the sub-millimetre to millimetre range. A width of the electrode may be, for example, between 0.5 m and 3 m.

[0009] The methods disclosed herein allow for carrying out at least steps a) and b), but preferably all steps until partitioning of the electrode workpiece according to step c), in a continuous manner. The methods disclosed herein may allow for a flow production without interruption with the continuous electrode workpiece being in motion while being processed or otherwise treated. The SEI formation according to step b) is carried out by continuously conveying the continuous electrode workpiece through the first and second electrochemical baths. It is to be understood that the processing steps, such as the SEI formation step b), may only affect a particular portion of the continuous electrode workpiece at a given point in time, i.e. the portion that is subjected to processing at that point in time.

[0010] The method disclosed herein allows for manufacturing battery electrodes in a continuous manner, thereby reducing the time, energy and factory volume / area consumed compared to prior art approaches. Electrode assemblies and batteries may be produced faster and at lower costs compared to prior art methods.

[0011] Furthermore, the methods described herein allow for controlled and direct formation of a SEI layer on the surface of the electrodes in a continuous manner before the electrode assembly is produced by stacking or winding and before the battery cell is assembled. The methods described herein do not require, and preferably may not include, further formation of a SEI layer during classical cell formation and / or at the end of cell manufacturing line. Therefore, unwanted gas formation after arranging the battery electrode assembly in the cell housing can be reduced or even completely avoided. The “early” SEI formation described herein allows to skip time consuming and cost intensive formation steps at the end of cell manufacturing. Forming the SEI layer before closing off the battery housing allows for monitoring and quality control of the SEI layer formed in step b).

[0012] Conveying or moving the electrode workpiece through the first electrochemical bath, which is preferably an electrochemical cell in charging or SEI formatting mode, may result in lithium species contained in the first electrochemical bath physically and / or chemically interacting with the electrode workpiece. Lithium ions from the first electrode bath may be introduced into pores of the electrode workpiece resulting in a lithiated electrode workpiece. Furthermore, redox reactions facilitated by the first electrochemical bath being an electrochemical cell may result in the formation of a solid electrolyte interphase formed on the surface of the (coated) electrode workpiece. For example, the solid electrolyte interphase may include lithium-organic compositions.

[0013] However, the first electrochemical bath may result in a fully charged electrode workpiece which is difficult to handle during manufacturing processes due to safety issues. In case of using the electrode workpiece directly after the first electrochemical bath, there is a risk of short circuit and consequent fire and explosions in the electrode stacking / winding processes and cell assembly process. Conveying or moving the electrode workpiece through the second electrochemical bath, which is preferably anelectrochemical cell in discharge mode, advantageously largely or fully discharges the continuous electrode workpiece, thereby ensuring that the electrode workpiece is safe to handle. Concurrently, the second electrochemical bath may result in “delithiation” of the electrode workpiece. The lithium ions which may penetrate the bulk material of the electrode workpiece or its coating while being immersed in the first electrochemical cell, may largely or fully return back into the second electrochemical bath, which discharges the electrode workpiece while allowing to largely recover the lithium consumed in the first electrochemical bath. Advantageously, the SEI layer formed in the first electrochemical bath may be rather stable, and therefore may not be substantially affected in the second electrochemical bath.

[0014] The methods disclosed herein may not result in a prelithiated electrode material and / or do not require a separate prelithiation step. Building up the SEI layer on the electrode workpiece already before producing the electrode assembly may ensure that lithium ions may not be irreversibly consumed when taking the battery into operation, because SEI layer formation is largely or fully completed at an earlier stage. The SEI layer formed on the electrode surface results in an enhanced cell lifetime due to less ageing.

[0015] The first electrochemical bath may be filled with a first composition including an electrolyte and / or a SEI formation additive. The electrolyte may include a lithium salt and an organic component or an organic solvent. Illustratively, the electrolyte may include 1 mol / L LiPF6salt in ethylene carbonate and diethyl carbonate (1 : 1 by volume). The SEI formation additive may be an organic component or an organic solvent. For example, the SEI formation additive may be fluoroethylene carbonate (FEC) and / or vinylene carbonate (VC). The first composition may allow for efficient, fast, durable, homogeneous and thickness and integrity controlled SEI formation. The electrolyte may include one or more components selected from the groupconsisting 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 useful for the first composition are described in Zhang, Shengshui “A review on electrolyte additives for lithium-ion batteries” November 2006, Journal of Power Sources, Vol. 162, No. 2, p. 1379-1394.

[0016] The first and / or the second electrochemical bath(s) may each include a plurality of rollers, e.g. handling rolls, for conveying or moving the electrode workpiece through the electrochemical bath(s).

[0017] The first and / or the second electrochemical bath(s) may each further include a second plurality of rollers. The second plurality of rollers may be provided to remove or lift out a downstream portion of the continuous electrode workpiece from the electrochemical bath and / or extract or squeeze out the (first, second) composition from the downstream portion of the continuous electrode workpiece. The second plurality of rollers may have a tensioning functionality.

[0018] The first and / or the second electrochemical bath(s) may include a counter electrode, and a separator disposed between the continuous electrode workpiece and the counter electrode. The counter electrode may be selected from the group consisting of a pure lithium electrode, a lithium titanate oxide (LTO) electrode, and a lithium iron phosphate (LFP) electrode. Preferably, the counter electrode is a lithium titanate oxide electrode. The electrode workpiece may be coated on two sides. In one embodiment, the first and / or the second electrochemical bath(s) may include two counter electrodes, and two separators. One separator and one counter electrode may be provided on each side of the electrode workpiece. The separator and / or the counter electrode may be continuous. The separator may be continuous, and the electrochemical bath may include a plurality of spaced apart non-continuous counter electrodes. Having several spaced apart non-continuous counterelectrodes may simplify production while mimicking a continuous electrochemical cell capable to be operated in continuous throughput mode.

[0019] The second electrochemical bath may be filled with a second composition. The second composition may be the same as the first composition, but preferably is different. The second composition may not include a SEI formation additive. The second composition may include an electrolyte. The electrolyte may be the same as the electrolyte used in the first composition. The electrolyte may include a lithium salt and an organic component or an organic solvent. Illustratively, the electrolyte may include 1 mol / L LiPF6salt in ethylene carbonate and diethyl carbonate (1 : 1 by volume). In addition to the aforementioned advantages, the second electrochemical bath and second composition can act as an electrolyte and washing solution. This allows for rinsing out detrimental or disadvantageous parts or decomposition products which may be formed in the first electrochemical bath and may be attached or adsorbed to a surface of the electrode workpiece. Electrolytes and electrolyte additive useful for the first and second composition are described in Zhang, Shengshui “A review on electrolyte additives for lithium-ion batteries” November 2006, Journal of Power Sources, Vol. 162, No. 2, p. 1379-1394.

[0020] Furthermore, the method may include conveying or moving the electrode workpiece through more than two electrochemical baths or conveying or moving the electrode workpiece through the first and second electrochemical baths several times. This may ensure that a sufficiently thick and homogenous SEI layer is formed.

[0021] For example, the method may include conveying the continuous electrode workpiece in a third electrochemical bath. The third electrochemical bath may be an electrochemical cell in a charge mode. The third electrochemical bath may be filled with a third composition, the third composition including an electrolyte and a SEI formation agent. The thirdcomposition is preferably different 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 cell in discharge mode.

[0022] Additionally, or alternatively the method may include conveying or moving the electrode workpiece through a cleaning bath or a plurality of soaked rollers. The rollers may be soaked with a cleaning agent. The cleaning bath or the plurality of soaked rollers may allow for rinsing out detrimental or disadvantageous parts or decomposition products which may be formed in the first or second electrochemical bath and may be attached or adsorbed to a surface of the electrode workpiece. This step may be carried out after conveying the electrode workpiece through the first electrochemical bath and preferably after conveying the electrode workpiece through the second electrochemical bath.

[0023] The method may further include establishing electrical connections to the counter electrode and the continuous electrode workpiece of the first electrochemical bath. The SEI layer may be formed on the continuous electrode workpiece by supplying a voltage to the electrode workpiece and the first electrochemical bath, in particular the counter electrode of the first electrochemical bath. The electrical connections to the electrode workpiece may be established in a non-coated section of the electrode workpiece.

[0024] The method may further include establishing electrical connections to the counter electrode and the continuous electrode workpiece of the second electrochemical bath. The continuous electrode workpiece may thereby be at least partially discharged. The electrical connections may be established in a non-coated section of the electrode workpiece.

[0025] Step b) may further include feeding a discharge energy generated by the second electrochemical bath to the first electrochemical bath. Beneficially, the discharge energy from the second electrochemical bath maybe recovered. The discharge energy may be fed back to perform electrochemical processing in the first electrochemical bath. A grid may be provided in addition to supply additional energy for performing electrochemical processing in the first electrochemical bath. Step b) may advantageously be carried out with rather limited energy consumption.

[0026] According to an embodiment, the method further includes exchanging or swapping the counter electrode(s) of the first electrochemical bath and the counter electrode of the second electrochemical bath with each other. The counter electrode(s) in the first electrochemical bath may initially be lithium-rich and lithium of the counter electrode(s) may gradually dissolve into solution. On the other hand, the counter electrode(s) of the second electrochemical cell may be lithium-poor initially and lithium may gradually build up on the counter electrode(s). Beneficially, the lithium can be recovered by exchanging the counter electrodes, thereby limiting consumption of lithium. In another embodiment, the first and second electrochemical baths include the same composition. Instead of exchanging the counter electrodes, the first and second electrochemical bath may be exchanged or swapped.

[0027] Exchanging the counter electrode of the first electrochemical bath and the counter electrode of the second electrochemical bath with each other and / or exchanging the first and second electrochemical baths with each other may be carried out after a predetermined operating time of the counter electrodes or alternatively, after a ratio of lithium extracted from the counter electrode in first bath electrode to lithium built up in the counter electrode of the second bath electrode exceeds a predetermined value.

[0028] According to another embodiment, the counter electrode is a continuous counter electrode. The continuous counter electrode may include a plurality of conductive portions spaced apart along the length (the direction of movement) of the continuous counter electrode. The continuous counterelectrode may include a plurality of isolating portions spaced in between each adjacent pair of conductive portions.

[0029] The method may include repeatedly conveying the continuous counter electrode from the first electrochemical bath to the second electrochemical bath. Optionally, the method may include repeatedly conveying the counter electrode from the second electrochemical bath to the first electrochemical bath. The method may include an apparatus for providing and conveying the continuous counter electrode. The apparatus may be configured to remove the continuous counter electrode from the first (second) electrochemical bath and immerse the continuous counter electrode into the second (first) electrochemical bath, in particular directly or at a later point in time. The apparatus may include a plurality of rollers for conveying the counter electrode from the second electrochemical bath to the first electrochemical bath. Advantageously, lithium consumption can be limited by repeatedly consuming and building up lithium on the continuous counter electrode.

[0030] According to another embodiment, the first and / or second electrochemical bath(s) include lithium solvated in a solvent. In this embodiment, the electrochemical bath(s) the solvated lithium may act as a counter electrode. A separator may be provided which may act as a diaphragm. The separator may be configured to enable lithium ions to pass therethrough, but not the electrolyte or solvent. In this embodiment, the lithium solvated in the solvent may be pumped from the second electrochemical bath to the first electrochemical bath. Advantageously, lithium consumption can be limited by repeatedly replenishing lithium consumed in the first electrochemical bath from the second electrochemical bath in which it is build up.

[0031] Method step b) may be carried out in a controlled environment. For example, method step b) may be carried out within a dry room for batteryassembly, preferably wherein the dry room has a low humidity and / or is explosion-proof.

[0032] According to an embodiment, the method includes e) Recording, with one or more sensors, a signal associated with the SEI layer formed on an electrode portion of the continuous electrode workpiece; analysing, with a controller, the signal to determine a quality control parameter associated with a quality of the SEI layer formed on the electrode portion; and determining a quality condition based on a comparison between the quality control parameter and a predetermined threshold parameter.

[0033] Typically, the quality control according to step e) allows for evaluating the SEI formed on a particular portion (electrode portion) of the continuous electrode workpiece. Step e) may be carried out during and / or after step b). Step e) may be carried out at several points in time, which may allow to monitor a progress of the SEI layer being formed on the electrode portion of the continuous electrode workpiece. For example, a signal may be recorded with the sensor after or while the electrode portion is removed from the first electrochemical bath. Additionally, or alternatively, a signal may be recorded with the sensor before the electrode portion is immersed in the first electrochemical bath and / or after removal from the second electrochemical bath. Formation of the SEI layer may occur entirely or mainly while the electrode workpiece is in an electrochemical cell in charge mode, such as the first electrochemical bath.

[0034] The methods disclosed herein include SEI layer formation before closing off the battery housing, which allows for monitoring or checking the SEI layer formed in step b) in a direct manner. In prior art methods, the quality of the SEI layer formed can only be checked indirectly once the battery is fully assembled and taken into operation by means of determining the decrease in usable capacity. Methods disclosed herein allow for investigating the SEI layer formed on the electrode portion even before a battery assemblyis produced. Thus, methods disclosed herein allow for reducing scrap during production by only using portions of the continuous electrode workpiece which include a satisfactory SEI layer.

[0035] Any type of signal may be recorded which allows for evaluating the quality of the SEI layer. The signal may be derived by investigating the surface of the electrode portion of the continuous electrode workpiece, or may be inferred from other parameters associated with SEI formation. SEI formation may influence the first composition in the first electrochemical bath, for example by reducing the Li ion concentration in the first composition or by the appearance of decomposition products formed by the interaction with the (coated) electrode workpiece.

[0036] In one embodiment recording, with the one or more sensors, the signal includes recording, with an image sensor, an image of a surface of the electrode portion. Formation of an SEI layer on the electrode portion may alter the visual appearance of the electrode workpiece. SEI formation may be verified based on recording an image with a camera. For example, the colour of the electrode workpiece may change during SEI formation. The method may further include analysing the image to determine the quality control parameter associated with a visual appearance, preferably a colour, of the surface of the electrode portion. For example, a control system including processing circuitry may be used to evaluate a colour of the surface of the electrode portion. The quality control parameter may correspond to the parameters of a colour space.

[0037] Additionally, or alternatively, 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.

[0038] The method may include evaluating the quality of the SEI layer formed with at least two different approaches. For example, the method mayinclude recording, with an image sensor, an image of a surface of the electrode portion and analysing the image to determine the quality control parameter associated with a visual appearance, preferably a colour, of the surface of the electrode portion. Additionally, the method may include recording, with a second sensor, a second signal 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 further include analysing, with the controller, the second signal to determine a second quality control parameter associated with the quality of the SEI layer formed on the electrode portion.

[0039] The predetermined threshold parameter may be a value which indicates that the quality of the SEI formed is sufficient for further use in steps c) and d). The quality control parameter determined by the controller and the predetermined threshold parameter may be compared to determine whether a quality condition is met.

[0040] The quality control according to step e) is preferably carried out automatically. The quality control according to step e) may be carried out in real-time and / or several times during and optionally after step b). For example, a visual inspection may be carried out several times during step b) and / or an electrochemical impedance signal may be measured several times during step b). The method may further include outputting the quality condition and / or the quality control parameter. For example, the method may further include displaying the quality condition and / or the quality control parameter on a screen. Additionally, or alternatively, the method may output an alert if the quality condition is not met. The method may include transmitting the quality condition and / or the quality control parameter to an external device.

[0041] In one embodiment, step e) includes further proceeding with step c) if the quality condition is fulfilled.

[0042] If the quality condition is not fulfilled, the method may include repeating step b). Step b) may be repeated until the quality condition is fulfilled or may be repeated at most a predetermined number of times.

[0043] Alternatively, if the quality condition is not fulfilled, the method may include marking or labelling the electrode portion as not for use in step c). For example, after partitioning in step c), the electrode portion not fulfilling the quality condition may be sorted out and not used for forming the electrode assembly in step d).

[0044] If the quality condition is not fulfilled, the method may include conveying the continuous electrode workpiece in a third electrochemical bath. The third electrochemical bath may be an electrochemical cell in charge mode. The third electrochemical bath may be filled with a third composition, the third composition including an electrolyte and a SEI formation agent. The third composition is preferably different from the first composition. The method may further include subsequently conveying the continuous electrode workpiece in a fourth electrochemical bath.

[0045] The electrode workpiece provided in step a) is preferably an electrode workpiece for a lithium ion electrode assembly or a lithium ion battery. The electrode workpiece may correspond to an anode workpiece for forming an anode or to a cathode workpiece for forming a cathode. Preferably, the electrode workpiece corresponds to an anode workpiece for forming an anode, and more preferably a graphite anode.

[0046] The method of manufacturing the battery electrode assembly disclosed herein may be used to form a plurality of anodes and cathodes. Steps a) to c) of the method disclosed herein may be carried out separately for each of the continuous anode workpiece and a continuous cathode workpiece.

[0047] The method may include: a) Providing a continuous cathode workpiece and providing a continuous anode workpiece; b) Electrochemically forming a solid electrolyte interphase (SEI) layer on the continuous cathode workpiece, and electrochemically forming a solid electrolyte interphase (SEI) layer on the continuous anode workpiece; c) partitioning the continuous cathode workpiece into a plurality of battery cathodes; and partitioning the continuous anode workpiece into a plurality of battery anodes.Steps a) to c) may be carried out according to any embodiment described herein. The continuous cathode workpiece and the continuous anode workpiece may be conveyed in the same first and second electrochemical baths or alternatively may be conveyed in different and separate first and second electrochemical baths (first, second, third and fourth electrochemical baths).

[0048] The method may further include step d) stacking or winding the plurality of battery anodes, a plurality of separators, and the plurality of battery cathodes.

[0049] Step a) providing a continuous electrode workpiece may include one or more sub-steps as described in more detail below.

[0050] Step a) may include a sub-step al) Providing a blank continuous electrode workpiece. In case the continuous electrode workpiece is a continuous cathode workpiece, the blank continuous cathode workpiece may be formed of aluminum (Al). In case the continuous electrode workpiece is a continuous anode workpiece, the blank continuous anode workpiece may be formed of copper (Cu).

[0051] Step a) may include a sub-step a2) Manufacturing a slurry. Substep a2) may be carried out before, during or after sub-step al). The slurry may include an active component for forming the anode or cathode. In case the continuous electrode workpiece is a continuous cathode workpiece, the active component may be LiCoO2. In case the continuous electrode workpiece is a continuous anode workpiece, the active component may preferably be graphite. The slurry may further include one or more, preferably all, of a conductive additive (e.g. carbon black), a polymeric binder (e.g. PVDF), and a solvent (e.g. NMP, water).

[0052] Step a) may include a sub-step a3) Coating the blank continuous electrode workpiece with the slurry. The continuous electrode workpiece may be single or double side coated and / or have a thickness in the sub-millimetre to millimetre range.

[0053] In one embodiment, the method includes, after step b), repeating at least steps a3) and step b), but optionally also one or more of the other steps disclosed herein. Repeating the steps may speedup overall SEI formation and may be particularly beneficial for high energy electrodes.

[0054] The method may further include a step f) Heating the continuous electrode workpiece. Heating step f) may be regarded as a first or initial drying step, to reduce a water content of the continuous electrode workpiece and in particular to cure the coating. Step f) is preferably carried out before SEI formation step b). Step f) may alternatively be regarded as part of step a), corresponding to a sub-step a4). Step f) is preferably carried out after step a), and in particular after sub-step a3). For example, the method may include a coating line for carrying out sub-step a3), and a furnace may be equipped with the coating line. Alternatively, the heating step f) may be carried out by means of infrared radiation or hot air blowing. Heating or drying step f) allows to reduce the residual water content in the electrode workpiece, which may otherwise react with other components used in step b), such as a lithiumcomponent, and cause loss of the lithium component. Thus, step f) facilitates SEI formation in step b).

[0055] The method may further include a step g) calendaring the continuous electrode workpiece. Step g) may be preferably carried out before step b) and / or after steps a) and f). Step g) may alternatively be regarded as part of step a), corresponding to a sub-step a5). Sub-step a5) may be carried out after sub-step a4).

[0056] The method may further step h) drying the continuous electrode workpiece. Step h) may be a second drying step. The second drying step may be carried out after step f), and before step b). The second drying step may be carried out after step g). In one example, the second drying step is based on vacuum drying.

[0057] The method may further include step i) coating the continuous electrode workpiece with an electrolyte. Step i) may be carried out after step b) and before step d). Step i) may be carried out before or after step c). Step i) may include temperature-controlled electrolyte fixation of the coating on the electrode workpiece, e.g. by freeze or partial freeze fixation.

[0058] Step c) may also be referred to as slitting the continuous electrode workpiece into a plurality of battery electrodes in some embodiments. In step c), the continuous (and dried) electrode workpiece may be partitioned such that the resulting electrodes are appropriately dimensioned to be directly used for preparing the electrode assembly in step d).

[0059] Step d) includes forming the battery electrode assembly. The battery electrode assembly may be directly used for forming a battery without the need to carry out further processing steps for the battery electrode assembly. Step d) may include forming a battery electrode stack by stacking the plurality of electrodes and a plurality of separators. The battery electrode stack may include several cathodes and anodes. As described further above, the methodmay be carried out to form a plurality of cathodes or a plurality of anodes, or may be carried out form both a plurality of cathodes and a plurality of anodes.

[0060] According to another aspect of the present disclosure, a method of manufacturing a battery electrode assembly, in particular for a lithium-ion battery, is provided. The method includes a) providing a continuous electrode workpiece and b) forming a solid electrolyte interphase (SEI) layer on the continuous electrode workpiece; wherein step b) includes at least one selected from the group of electrochemically, chemically and mechanically forming the solid electrolyte interphase (SEI) layer. The method further includes e) recording, with one or more sensors, a signal associated with the SEI layer formed on an electrode portion of the continuous electrode workpiece; and analysing, with a controller, the signal to determine a quality control parameter associated with a quality of the SEI layer formed on the electrode portion; and determining a quality condition based on a comparison between the quality control parameter and a predetermined threshold parameter. The method further includes c) partitioning 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.

[0061] Each of steps a) to e) may be carried out according to any aspect or embodiment described herein. Likewise, the method according to this aspect may include any of the optional steps (such as any of steps f) to i)) described above for the previous aspect of the present disclosure.

[0062] According to another aspect of the present disclosure, a method for manufacturing a battery, in particular a lithium-ion battery, is provided. The method includes A) Manufacturing the battery electrode assembly according to any embodiment disclosed herein; and B) Arranging the battery electrode assembly in a cell housing.

[0063] The method may further include step C) Filling the cell housing with a liquid mixture including a battery electrolyte solvent. The battery electrolytesolvent 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 carried out after step B). The liquid mixture may further include other electrolyte co-solvents and / or a salt (e.g. LiPF6).

[0064] The method may further include finalising cell formation, such as closing off the battery cell housing and setting up all electrical connections.

[0065] The method may further include carrying out end of line tests.

[0066] The methods described herein allow for controlled and direct formation of an SEI layer on the surface of the electrodes in a continuous manner before the electrode assembly is produced by stacking or winding and before the battery cell is assembled. The methods described herein do not require, and preferably may not include, further formation of a SEI layer during cell formation and / or end of line tests. Therefore, unwanted gas formation after arranging the battery electrode assembly in the cell housing can be reduced or even completely avoided.

[0067] Those skilled in the art will recognise additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0068] The components in the Figures are not necessarily to scale, instead emphasis being placed upon illustrating the principles of the invention. Moreover, in the Figures, like reference signs designate corresponding parts. The accompanying drawings relate to embodiments of the disclosure and are described in the following:Fig. 1 shows a schematic view of a first electrochemical bath accordingto embodiments described herein;Fig. 2 shows a schematic view of a second electrochemical bath according to embodiments described herein;Fig. 3 shows a schematic view of a first and a second electrochemical bath according to embodiments described herein;Fig. 4 shows a schematic view of a first and a second electrochemical bath according to another embodiment described herein;Fig. 5 shows a schematic view of a first and a second electrochemical bath according to embodiments described herein;Fig. 6 shows a schematic view of a first and a second electrochemical bath according to another embodiment described herein;Fig. 7 shows a schematic view of a continuous counter electrode according to embodiments described herein.DETAILED DESCRIPTION OF EMBODIMENTS

[0069] Reference will now be made in detail to the various embodiments, one or more examples of which are illustrated in each figure. Each example is provided by way of explanation and is not meant as a limitation. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with any other embodiment to yield yet a further embodiment. It is intended that the present disclosure includes such modifications and variations.

[0070] Within the following description of the drawings, the same reference numbers refer to the same or to similar components. Generally, only the differences with respect to the individual embodiments are described. Unlessspecified otherwise, the description of a part or aspect in one embodiment can apply to a corresponding part or aspect in another embodiment as well.

[0071] With exemplary reference to Fig. 1, a first electrochemical bath 110 is described. The first electrochemical bath 110 includes a housing defining a bath containing a first composition.

[0072] The first electrochemical bath 110 further includes a first plurality of rollers 101 A- 1011 for conveying or moving a continuous electrode workpiece 130 through the first electrochemical bath 110. The first plurality of rollers 101A-101I may be arranged in the first electrochemical bath 110 such that the electrode workpiece 130 is moved in an approximately sinusoidal manner.

[0073] The first electrochemical bath 110 further includes a second plurality of rollers 103A-103B. The second plurality of rollers 103A-103B may be provided to remove or lift out a downstream portion of the continuous electrode workpiece 130 from the first electrochemical bath 110 and / or extract or squeeze out the first composition as well as other components in the composition, such as excess lithium ions, decomposition products and the like, from the downstream portion of the continuous electrode workpiece 130.

[0074] The first electrochemical bath 110 further includes a plurality of (non-continuous) counter electrodes 132 which are spaced apart from each other. A counter electrode 132 is disposed on either side of the continuous electrode workpiece 130.

[0075] The first electrochemical bath 110 further includes two continuous separators (not visible in Figure 1), with one separator being disposed between the continuous electrode workpiece 130 and a counter electrode 132. However, the separator may also be non-continuous.

[0076] The first electrochemical bath 110 may further include a sensor 170, for recording a signal associated with the SEI layer formed on an electrode portion of the continuous electrode workpiece. The sensor 170 may allow to evaluate the quality of the SEI layer formed. In the embodiment illustrated in Figure 1, the sensor 170 is a camera for recording an image of the electrode portion. A colour change may indicate whether a SEI layer has been sufficiently formed.

[0077] With exemplary reference to Fig. 2, a second electrochemical bath 120 according to an embodiment is described. The second electrochemical bath 120 includes a housing defining a bath containing a second composition.

[0078] The second electrochemical bath 120 further includes a first plurality of rollers 102A-102I for conveying or moving the continuous electrode workpiece 130 through the second electrochemical bath 120. The first plurality of rollers 102A-102I may be arranged in the second electrochemical bath 120 such that the electrode workpiece 130 is moved in an approximately sinusoidal manner.

[0079] The second electrochemical bath 120 further includes a second plurality of rollers 104A-104B. The second plurality of rollers 104A-104B may be provided to remove or lift out a downstream portion of the continuous electrode workpiece 130 from the second electrochemical bath 120 and / or extract or squeeze out the first composition as well as other components in the composition, such as excess lithium ions, decomposition products and the like, from the downstream portion of the continuous electrode workpiece 130.

[0080] The second electrochemical bath 120 further includes a plurality of (non-continuous) counter electrodes 133 which are spaced apart from each other. A counter electrode 133 is disposed on either side of the continuous electrode workpiece 130.

[0081] The second electrochemical bath 120 further includes two continuous separators (not visible in Figure 2), with one separator being disposed between the continuous electrode workpiece 130 and a counter electrode 133.

[0082] With exemplary reference to Fig. 3, a first and a second electrochemical bath 110, 120 according to an embodiment is described. An electrical connection is provided connecting the second electrochemical bath 120 with the first electrochemical bath 110. The second electrochemical bath is an electrochemical cell in discharge mode, while the first electrochemical bath 110 is an electrochemical cell in charge mode. The 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 grid 160 is provided to supply additional energy for performing electrochemical processing in the first electrochemical bath 110.

[0083] Figure 4 illustrates an example embodiment of switching counter electrodes 132, 133 back and forth between the first and second electrochemical baths 110, 120. An initially lithium rich counter electrode 132 of first electrochemical bath 110 may become increasingly lithium poor with time, whereas an initially lithium poor counter electrode 133 of second electrochemical bath 120 may become increasingly lithium rich with time. The methods disclosed herein may therefore include exchanging or swapping the counter electrodes back and forth between the first and second electrochemical baths 110, 120. The swapping may be carried out many times, such as hundreds or even thousands of times.

[0084] Figure 5 illustrates an example embodiment of using a continuous counter electrode 232. The continuous electrode workpiece 130 is conveyed through the first electrochemical bath 110 with rollers 101A-101C and further conveyed through second electrochemical bath 120 with rollers 102A-102C.The method includes an apparatus 140 for providing and conveying the continuous counter electrode 232. The apparatus 140 may rotate around a central axis. The apparatus may further include one or more pairs of rollers 141, 142 which allow for conveying the continuous counter electrode 232 and / or the winding up and unwinding the counter electrode 232. The counter electrode 232 may be used in the first electrochemical bath 110 and subsequently directly used again in the second electrochemical bath 120. Alternatively, the counter electrode may be wound up after use in the first electrochemical bath 110 and can be used at a later point in time for the second electrochemical bath 120. In this embodiment, several continuous counter electrodes 232 may be used.

[0085] Figure 6 illustrates another exemplary embodiment of using a continuous counter electrode 232. The continuous electrode workpiece 130 is conveyed through the first electrochemical bath 110 with rollers 101A-101C and further conveyed through second electrochemical bath 120 with 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 subsequently further conveying the continuous counter electrode 232 from the second electrochemical bath 120 to the first electrochemical bath 110. The method may include a plurality of rollers (not shown) for conveying the counter electrode 232.

[0086] Figure 7 illustrates an exemplary embodiment of a continuous counter electrode 332. Figure 7 depicts a portion of the counter electrode of Figure 6 taken along lines A-A. The continuous counter electrode 332 may include a plurality of conductive portions 333 spaced apart along the length of the continuous counter electrode 332. The continuous counter electrode 332 may include a plurality of isolating portions 334 spaced in between each adjacent pair of conductive portions 333.

[0087] While the foregoing is directed to embodiments, other and further embodiments may be devised without departing from the basic scope, and the scope is determined by the claims that follow.REFERENCE NUMERALS101A-101I first plurality of rollers102A-102C first plurality of rollers103A, 103B second plurality of rollers104 A, 104B second plurality of rollers110 first electrochemical bath120 second electrochemical bath130 continuous electrode workpiece131 separator132, 133, 232, 332 counter electrode140 apparatus141 first roller for counter electrode142 second roller for counter electrode160 grid161 electrical connection170 sensor333 conductive portion334 isolating portion

Claims

CLAIMS1. Method of manufacturing a battery electrode assembly, in particular for a lithium-ion battery, the method comprising: a) Providing a continuous electrode workpiece (130); b) Electrochemically forming a solid electrolyte interphase (SEI) layer on the continuous electrode workpiece (130); wherein step b) includes conveying the continuous electrode workpiece (130) in a first electrochemical bath (110), the first electrochemical bath (110) preferably being an electrochemical cell in a charge mode; and wherein step b) further includes conveying the continuous electrode workpiece (130) in a second electrochemical bath (120), the second electrochemical bath (120) preferably being an electrochemical cell in a discharge mode; c) Partitioning the continuous electrode workpiece (130) into a plurality of battery electrodes; and d) Stacking or winding the plurality of battery electrodes and a plurality of separators.

2. The method of claim 1, wherein the first electrochemical bath (110) is filled with a first composition including an electrolyte and a SEI formation additive.

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

4. The method of any one of the preceding claims, wherein the second electrochemical bath (120) includes a counter electrode (133), and a separator (131) disposed between the continuous electrode workpiece (130) and the counter electrode (133); and in particular wherein step b) further includes establishing electrical connections to 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 of any one of the preceding claims, further comprising 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 of any one of claims 1-4, wherein step b) further includes 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 of any one of the preceding claims, wherein step b) further includes feeding a discharge energy generated by the second electrochemical bath (120) to the first electrochemical bath (110).

8. The method of any preceding claim, further comprising the step: e) Recording, with one or more sensors, a signal associated with the SEI layer formed on an electrode portion of the continuous electrode workpiece (130); analysing, with a controller, the signal to determine a quality control parameter associated with a quality of the SEI layer formed on the electrode portion; and determining a quality condition based on a comparison between the quality control parameter and a predetermined threshold parameter, wherein step e) is carried out during and / or after step b) and before step d).

9. The method of claim 8, wherein, if the quality condition is fulfilled, the method includes further proceeding with step c); else i) repeating step b); or ii) marking the electrode portion not for use in step c).

10. The method of claim 8 or 9, wherein recording, with the one or more sensors, the signal includes recording, with an image sensor (160), an image of a surface of the electrode portion; andAnalysing the image to determine the quality control parameter associated with a visual appearance, preferably a colour, of the surface of the electrode portion.

11. The method of 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 of any preceding claim, further comprising the step: f) Heating (514) the continuous electrode workpiece (130); wherein step f) is carried out after step a) and preferably before step b).

13. The method of any preceding claim, further comprising the step: g) Calendaring (515) the continuous electrode workpiece (130); wherein step g) is carried out before step b), and preferably after step f).

14. The method of any preceding claim, further comprising the step: h) Drying (420) the continuous electrode workpiece (130) by conveying a flow of a hydrophilic drying composition past the continuous electrode workpiece (130), the hydrophilic drying composition preferably including a battery electrolyte solvent; wherein step h) is carried out before step b), and preferably after step f).

15. The method of any preceding claim, wherein step b) further includes removing a downstream portion of the continuous electrode workpiece (130) from one of the electrochemical baths (110, 120) and extracting the composition out of the continuous electrode workpiece (130) by means of a plurality of rollers (103A, 103B).

16. Method for manufacturing a battery, in particular a lithium-ion battery, including the following steps:A) Manufacturing the battery electrode assembly according to any preceding claim; B) Arranging the battery electrode stack in a cell housing.

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