Method for producing an electrochemical single cell, and electrochemical single cell
Patent Information
- Application Number
- EP2023708730
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-02-28
- Filing Date
- 2023-02-27
- Publication Date
- 2025-01-08
AI Technical Summary
Existing methods for producing electrochemical cells either underutilize space in cell housings or compromise production speed, with traditional jelly roll methods being fast but inefficient in space usage and cell stacking methods being slower.
A method involving the production of an electrode strand by alternating electrode sheets and a separator, which is then wound onto a flat core to form a flat coil, allowing for efficient space utilization and high production speed, with optional trimming and deformation of the separator to further optimize space use.
This method enables the highest possible space utilization in cell housings while maintaining rapid production, reducing the risk of electrode coating damage and facilitating electrolyte penetration, thus combining efficient space use with high production speed.
Smart Images
Figure 1.1
Abstract
Description
[0001] Method for producing an electrochemical single cell and electrochemical
[0002] single cell
[0003] The invention relates to a method for producing an electrochemical single cell and an electrochemical single cell with a flat winding in a cell housing.
[0004] In cell casings for prismatic hard-case battery cells, a cell winding in the form of a jelly roll is typically used. The anode, cathode, and separator are wound onto a core. This process is very fast compared to stacking processes, but results in a suboptimal utilization of the available space within the cell casing. Using a cell stack makes better use of the space but results in a lower production speed due to the stacking of individual electrode sheets, sometimes combined with Z-folding of the separator.
[0005] DE 102007 017 024 B3 discloses a method for producing a battery cell in a wound construction, in particular a cell of a lithium-ion battery or nickel-metal hydride battery, with an electrode coil made of an electrode strip wound around a longitudinal axis of the cell, thus having the special feature that the electrode coil is applied to the winding core by winding the electrode strip around a dimensionally stable winding core extending in the direction of the longitudinal axis and then the electrode coil is formed into a different cross-sectional shape by means of a molding press which presses the electrode coil from the outside in a radial direction oriented transversely to the longitudinal axis.
[0006] One object of the invention is to provide a method for producing a single electrochemical cell that combines the highest possible space utilization with a favorable production speed. A further object is to create a single electrochemical cell with a flat winding in a cell housing, in particular a prismatic cell housing, that has the highest possible space utilization.
[0007] The above-mentioned objects are solved by the features of the independent claims.
[0008] Advantageous embodiments and advantages of the invention emerge from the further claims, the description and the drawing.
[0009] According to one aspect of the invention, a method for producing an electrochemical single cell is proposed, at least comprising: producing a first electrode layer from a strip-shaped separator, on which a first electrode sheet and a second electrode sheet are arranged alternately in a longitudinal direction, in particular by lamination, wherein the first electrode sheets and the second electrode sheets are arranged spaced from one another along an extension of the separator; producing a second electrode layer from a strip-shaped separator, on which a second electrode sheet and a first electrode sheet are arranged alternately, in particular by lamination, wherein the second electrode sheets and the first electrode sheets are arranged spaced from one another along the extension of the separator;Joining the two electrode layers in a vertical direction, in particular by lamination, to form an electrode strand, such that a first electrode sheet is arranged opposite a second electrode sheet separated by the separator; Winding the electrode strand onto a flat winding core to form a flat coil; Mounting the flat coil in a cell housing, in particular in a rigid cell housing having a prismatic design, in particular which is produced by deep drawing or cold extrusion.
[0010] According to the proposed method, for example, an electrode strand consisting of electrode layers of first and second electrode sheets, for example an anode and a cathode, and a continuous separator strip is first produced by lamination. The electrode strand comprises at least two electrode layers which are arranged such that a first electrode sheet lies opposite a second electrode sheet, separated by the separator. The electrode strand can advantageously be manufactured sequentially, i.e. first the production of one electrode layer, then the production of the other electrode layer, and then the lamination process in which both electrode layers are laminated together. Alternatively, however, it is also possible for both electrode layers to be manufactured in a single pass. For this purpose, the separator strips can be unwound simultaneously and then two opposing electrodes can be inserted.The entire electrode string is then laminated in a single process. This process is advantageous because the lamination takes place simultaneously—i.e., separator plus anode sheet plus separator plus cathode sheet. This can save time during production, but places greater demands on the tolerances of the individual electrode sheets and separator strips.
[0011] The electrode strand is then wound onto a flat winding core. While this also creates a rounded outer surface, it is significantly flatter, as the separator's thickness is typically smaller than that of an electrode. This allows the electrode assembly to be larger than with a conventional electrode coil, allowing the speed advantage of winding to be utilized.
[0012] A further advantage is that, especially for sensitive electrodes, bending is eliminated compared to a conventional circular winding. This means that the process proposed here also reduces the risk of chipping of the electrode coating.
[0013] This makes it possible to quickly manufacture single cells using solid-state technologies, which are usually difficult or impossible to manufacture by winding the electrodes.
[0014] The separator overhang that occurs on the flat coil in the longer extension of the flat coil can be minimized, for example, by laser cutting or hot pressing.
[0015] This advantageously combines the high production speed of an electrode coil with the efficient use of space in a cell stack. Additional costs due to separator overhang or waste are virtually negligible. The cell cup can be manufactured using conventional manufacturing processes such as deep drawing or cold extrusion. However, other manufacturing processes can also be used to produce the cell cup.
[0016] According to an advantageous embodiment of the method, the first electrode sheet can be trimmed such that the first electrode sheet has a lateral projection relative to the second electrode sheet, which is located opposite it in the vertical direction. Particularly in Li-ion cells, the anode is preferably designed to be larger in area than the cathode.
[0017] According to an advantageous embodiment of the method, the first and second electrode sheets can be arranged along the length of the separator such that the distance between a first electrode sheet and a second electrode sheet increases progressively with increasing length in the longitudinal direction of the separator. In this way, the first and second electrode sheets can be positioned one above the other even as the winding diameter increases.
[0018] According to an advantageous embodiment of the method, prior to mounting the flat coil in the cell housing, regions of the separator along a longer extension of the flat coil can be separated, in particular by laser trimming, such that the open ends of the separator have a lateral overhang relative to the first and second electrode sheets. This advantageously further improves the utilization of installation space in the cell housing. The trimming essentially creates an electrode stack with advantageous utilization of installation space. The separation also facilitates the penetration of the electrolyte when filling the cell. This allows the electrolyte to wet the electrodes and the separator more quickly.
[0019] According to an advantageous embodiment of the method, prior to mounting the flat coil in the cell housing, regions of the separator can be flattened along a longer extension of the flat coil. In particular, the flattened regions can be produced by hot-pressing the flat coil along its longer extension. The utilization of installation space in the cell housing can also be advantageously further improved by pressing the flat coil along the longer extension of the flat coil.
[0020] According to an advantageous embodiment of the method, before mounting the flat coil in the cell housing, the first electrode sheets of the first and second electrode layers can be electrically contacted with one another, and the second electrode sheets of the first and second electrode layers can be electrically contacted with one another. In this way, the electrodes of the electrochemical cell can be advantageously interconnected. For example, all first electrode sheets can be connected in parallel, and all second electrode sheets can be connected in parallel.
[0021] According to a further aspect of the invention, a single electrochemical cell with a flat winding in a cell housing, in particular a prismatic cell housing, is proposed, manufactured using such a method, wherein an electrode strand comprising a first and a second electrode layer is wound onto a flat winding core, with first electrode sheets and second electrode sheets arranged alternately in a vertical direction and spaced from one another by a separator. The two electrode layers of the electrode strand are arranged one on top of the other in such a way that a first electrode sheet is arranged opposite a second electrode sheet, separated by the separator.
[0022] The proposed electrochemical single cell comprises a flat winding of an electrode strand in the cell housing, in which first and second electrode sheets, separated by a separator, are located opposite each other.
[0023] The electrode strand is wound onto a flat winding core. While this also creates a rounded outer surface, it is significantly flatter, as the separator's thickness is typically smaller than that of an electrode. This allows the electrode assembly to be larger than with a conventional electrode coil, and the speed advantage of winding can be utilized in the production of the individual cell.
[0024] A further advantage is that, especially for sensitive electrodes, bending is eliminated compared to conventional circular winding. This means that the process proposed here also reduces the risk of chipping of the electrode coating. This allows for rapid production of single cells using solid-state technologies, which are usually difficult or impossible to manufacture by winding the electrodes.
[0025] The separator overhang that occurs on the flat coil in the longer extension of the flat coil can be minimized, for example, by laser cutting or hot pressing.
[0026] This advantageously combines the high production speed of an electrode coil with the efficient use of space in a cell stack. Additional costs due to separator overhang and waste are virtually negligible.
[0027] According to an advantageous embodiment of the single electrochemical cell, the flat coil can have open ends of the separator along its longer extension, which have a lateral overhang relative to the first and second electrode sheets. This advantageously further improves the utilization of space in the cell housing. The trimming essentially creates an electrode stack with advantageous space utilization. The separation also facilitates the penetration of the electrolyte when filling the cell. This allows the electrolyte to wet the electrodes and the separator more quickly.
[0028] According to an advantageous embodiment of the single electrochemical cell, the flat coil can have flat-formed regions of the separator along its longer extension. In particular, the flat-formed regions can be produced by hot-pressing the flat coil along its longer extension. The use of space in the cell housing can also be advantageously further improved by hot-pressing the flat coil along its longer extension.
[0029] According to an advantageous embodiment of the individual electrochemical cell, in the first and second electrode layers, the first electrode sheets can be electrically contacted with one another, and the second electrode sheets can be electrically contacted with one another. In this way, the electrodes of the electrochemical cell can be advantageously interconnected. For example, all of the first electrode sheets can be connected in parallel, and all of the second electrode sheets can be connected in parallel. Further advantages will emerge from the following description of the drawings. An exemplary embodiment of the invention is shown in the drawings. The drawings, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently also consider the features individually and combine them into useful further combinations.
[0030] Showing:
[0031] Fig. 1 is a longitudinal section through a laminated electrode strand according to an embodiment of the invention;
[0032] Fig. 2 shows a longitudinal section through a flat coil made of a laminated electrode strand according to an embodiment of the invention;
[0033] Fig. 3 shows a longitudinal section through a trimmed flat coil before assembly in a cell housing according to an embodiment of the invention; and
[0034] Fig. 4 shows a longitudinal section through a pressed flat coil before assembly in a cell housing according to a further embodiment of the invention.
[0035] In the figures, identical or similar components are numbered with the same reference numerals. The figures show only examples and are not to be understood as limiting.
[0036] Figure 1 shows a longitudinal section through a laminated electrode strand 20 according to an embodiment of the invention.
[0037] According to the proposed method for producing a single electrochemical cell 100, a first electrode layer 16 is produced from a strip-shaped separator 14, on which a first electrode sheet 10 and a second electrode sheet 12 are arranged alternately in a longitudinal direction 54, in particular by lamination. The first electrode sheets 10 and the second electrode sheets 12 are arranged spaced apart from one another along an extension 26 of the separator 14. The first electrode sheet 10 can, for example, be an anode, in which case the second electrode sheet 12 is the corresponding cathode.
[0038] A second electrode layer 18 is then produced in a similar manner, with only the order of the first and second electrode sheets 10, 12 being reversed. The two electrode layers 16, 18 are then joined together in a vertical direction 56 to form an electrode strand 20, in particular by lamination, so that a first electrode sheet 10 is arranged opposite a second electrode sheet 12, separated by the separator 14. The first electrode sheet 10, for example, the anode, projects beyond the opposite second electrode sheet 12, for example, the cathode.
[0039] The electrode strand 20 is wound onto a flat winding core 22 to form a flat winding 28. The winding direction 50 is indicated by an arrow in Figure 1.
[0040] The first and second electrode sheets 10, 12 can advantageously be arranged along the extension 26 of the separator 14 such that a distance 24 between a first electrode sheet 10 and a second electrode sheet 12 increases successively with increasing length in the longitudinal direction 54 of the separator 14. In this way, the first and second electrode sheets 10, 12 lie one above the other on the flat coil, even as the coil diameter increases.
[0041] Figure 2 shows a longitudinal section through a flat coil 28 made of a laminated electrode strand 20 according to an embodiment of the invention before assembly in the assembly direction 52 into a cell housing 40, which is indicated schematically in section.
[0042] The flat coil 28 is intended, in particular, for installation in a rigid cell housing 40 having a prismatic design. The cell housing 40 can be manufactured, for example, by deep drawing or cold extrusion, or by other manufacturing processes.
[0043] As can be seen in the longitudinal sections in Figure 1 and Figure 2, the first electrode sheet 10 can be trimmed such that the first electrode sheet 10 has a lateral overhang relative to the second electrode sheet 12 opposite it in the vertical direction 56.
[0044] Before mounting the flat coil 28 in the cell housing 40, the first electrode sheets 10 of the first and second electrode layers 16, 18 are electrically contacted with one another and the second electrode sheets 12 of the first and second electrode layers 16, 18 are electrically contacted with one another, so that the electrode string is connected as intended for installation in the cell housing 40 and for contacting connection poles (not shown) of the individual cell 100.
[0045] Figure 3 shows a longitudinal section through a trimmed flat coil 28 before assembly into a cell housing 40 according to an embodiment of the invention.
[0046] Before mounting the flat coil 28 into the cell housing 40, regions 36 of the separator 14 are separated along a longer extension 30 of the flat coil 28 (visible in Figure 2), in particular by laser trimming, such that open ends 32 of the separator 14 have a lateral projection relative to the first and second electrode sheets 10, 12. Lasers 42 with the corresponding laser beam 44 for the trimming are shown schematically. This advantageously increases the utilization of installation space in the cell housing 40 and practically corresponds to a conventional cell stack.
[0047] Figure 4 shows a longitudinal section through a pressed flat coil 28 before assembly into a cell housing 40 according to a further embodiment of the invention.
[0048] Before the flat coil 28 is mounted in the cell housing 40, regions 34 of the separator 14 are deformed flat along a longer extension 30 of the flat coil 28. This can be achieved, in particular, by hot-pressing the flat coil 28 along its longer extension 30. Punches 46, which exert forces 48 on the regions 34 of the flat coil 28 from both sides along the longer extension 30 of the flat coil 28, are shown schematically in Figure 4. The hot-pressing essentially compresses and laminates the protrusions of the separator 14, thus reducing the installation space for the protrusions of the separator 14.
[0049] The longer extension 30 of the flat coil 28 can thus be significantly shortened. This advantageously increases the utilization of space in the cell housing 40 and is practically equivalent to a conventional cell stack.
[0050] According to the proposed method, an electrochemical single cell 100 with a flat winding 28 in a cell housing 40, in particular a prismatic cell housing 40, is advantageously produced.
[0051] In the single cell 100, an electrode strand 20 consisting of a first and a second electrode layer 16, 18 is wound onto a flat winding core 22, with first electrode sheets 10 and second electrode sheets 12 arranged alternately in the vertical direction 56 and spaced apart from one another by a separator 14. The two electrode layers 16, 18 of the electrode strand 20 are arranged one above the other in such a way that a first electrode sheet 10 is arranged opposite a second electrode sheet 12, separated by the separator 14.
[0052] The flat coil 28 can have, in its longer extension 30, open ends 32 of the separator 14, as shown in Figure 3, which have a lateral projection relative to the first and second electrode sheets 10, 12.
[0053] Furthermore, the flat coil 28 can have flat-deformed regions 34 of the separator 14 along its longer extension 30, as shown in Figure 4. In particular, the flat-deformed regions 34 can be produced by hot-pressing the flat coil 28 along its longer extension 30.
[0054] Advantageously, in the first and second electrode layers 16, 18, the first electrode sheets 10 are electrically connected to one another, and the second electrode sheets 12 are electrically connected to one another. For example, all first electrode sheets can be connected in parallel, and all second electrode sheets can be connected in parallel.
[0055] List of reference symbols
[0056] 10 first electrode sheet
[0057] 12 second electrode sheet
[0058] 14 Separator
[0059] 16 first electrode layer
[0060] 18 second electrode layer
[0061] 20 electrode strands
[0062] 22 winding core
[0063] 24 Distance between electrode blades
[0064] 26 Extension
[0065] 28 flat wraps
[0066] 30 longer extension
[0067] 32 open ending
[0068] 34 flat deformed area
[0069] 36 Area
[0070] 40 cell casings
[0071] 42 lasers
[0072] 44 laser beam
[0073] 46 stamps
[0074] 48 Force
[0075] 50 Winding direction
[0076] 52 Mounting direction
[0077] 54 Longitudinal direction
[0078] 56 Vertical direction
[0079] 100 single cells
Claims
Patent claims: Method for manufacturing a single electrochemical cell (100), comprising at least Producing a first electrode layer (16) from a ribbon-shaped separator (14) on which a first electrode sheet (10) and a second electrode sheet (12) are arranged alternately in a longitudinal direction (54), in particular by lamination, wherein the first electrode sheets (10) and the second electrode sheets (12) are arranged spaced apart from each other along an extension (26) of the separator (14); Producing a second electrode layer (18) from a ribbon-shaped separator (14) on which a second electrode sheet (12) and a first electrode sheet (10) are alternately arranged, in particular by lamination, wherein the second electrode sheets (12) and the first electrode sheets (10) are spaced apart from each other along the extent (26) of the separator (14); Joining the two electrode layers (16, 18) in a vertical direction (56) to each other, in particular by lamination, to form an electrode strand (20), such that a first electrode sheet (10) and a second electrode sheet (12) are arranged opposite each other, separated by the separator (14); Winding the electrode strand (20) onto a flat winding core (22) to form a flat winding (28); Mounting the flat winding (28) in a cell housing (40), in particular in a rigid cell housing (40) which has a prismatic design, in particular which is manufactured by deep drawing or cold extrusion. Method according to claim 1, wherein the first electrode sheet (10) is trimmed such that the first electrode sheet (10) has a lateral projection relative to the a second electrode sheet (12) opposite it in the vertical direction (56). A method according to claim 1 or 2, wherein the first and second electrode sheets (10, 12) are arranged along the extension (26) of the separator (14) such that the distance (24) between a first electrode sheet (10) and a second electrode sheet (12) increases successively with increasing length in the longitudinal direction (54) of the separator (14). A method according to one of the preceding claims, wherein, prior to mounting the flat coil (28) in the cell housing (40), areas (36) of the separator (14) in a longer extension (30) of the flat coil (28) are cut off, in particular by laser trimming, such that open ends (32) of the separator (14) have a lateral projection relative to the first and second electrode sheets (10, 12).A method according to any one of claims 1 to 3, wherein, prior to mounting the flat coil (28) in the cell housing (40), areas (34) of the separator (14) are flattened in a longer extension (30) of the flat coil (28), in particular the flattened areas (34) are produced by hot pressing the flat coil (28) along its longer extension (30). A method according to any one of the preceding claims, wherein, prior to mounting the flat coil (28) in the cell housing (40), the first electrode sheets (10) of the first and second electrode layers (16, 18) are electrically contacted with each other and the second electrode sheets (12) of the first and second electrode layers (16, 18) are electrically contacted with each other.Electrochemical single cell (100) with a flat winding (28) in a cell housing (40), in particular a prismatic cell housing (40), manufactured by a method according to one of claims 1 to 6, wherein an electrode strand (20) consisting of a first and a second electrode layer (16, 18) is wound onto a flat winding core (22), with first electrode sheets (10) and second electrode sheets alternating in a vertical direction (56). Electrode sheets (12) spaced apart from one another by a separator (14), wherein the two electrode layers (16, 18) of the electrode strand (20) are arranged such that a first electrode sheet (10) and a second electrode sheet (12) are arranged opposite each other, separated by the separator (14). Electrochemical single cell according to claim 7, wherein the flat coil (28) has open ends (32) of the separator (14) in its longer extension (30), which have a lateral projection towards the first and second electrode sheets (10, 12). Electrochemical single cell according to claim 7, wherein the flat coil (28) has flat deformed areas (34) of the separator (14) in its longer extension (30), in particular wherein the flat deformed areas (34) are produced by hot pressing the flat coil (28) along its longer extension (30).Electrochemical single cell according to one of claims 7 to 9, wherein in the first and second electrode layer (16, 18) the first electrode sheets (10) are electrically contacted together and the second electrode sheets (12) are electrically contacted together.