Method for clamping an electrode assembly into a housing of a battery cell, battery cell, computer program and computer-readable storage medium

Abstract

Proposed is a method for clamping an electrode assembly (20) into a housing (10) of a battery cell, in which method the electrode assembly (20) is arranged in the housing (10) of the battery cell. The electrode assembly (20) comprises a first contact foil (21), a first electrode layer (22), a solid electrolyte (23) and a second contact foil (25), wherein the solid electrolyte (23) has a first and a second side. The first contact foil (21) is arranged on the first side and the second contact foil (25) is arranged on the second side of the solid electrolyte (23). The first electrode layer (22) is arranged between the solid electrolyte (23) and the first contact foil (21). The electrode assembly (20) is designed to deposit ions from the first electrode layer (22) onto the second contact foil (25), by application of a first voltage to the contact foils (21, 25) for charging the electrode assembly (20), such that a second electrode layer (24) is formed between the second contact foil (25) and the solid electrolyte (23). The electrode assembly (20) is designed to transfer ions from the second electrode layer (24) into the first electrode layer (22) by application of a second voltage to the contact foils (21, 25) for discharging the electrode assembly (20). Furthermore, in the method, the electrode assembly (20) is charged, and the second electrode layer (24) is formed as a result of the charging. Furthermore, a cut-off voltage is set at which the second electrode layer (24) is at least partially maintained between the second contact foil (25) and the solid electrolyte (23) in order to set a minimum pressure in the battery cell.

Description

[0001] Description

[0002] Method for clamping an electrode arrangement into a housing of a battery cell, battery cell, computer program and computer-readable storage medium

[0003] The invention relates to a method for clamping an electrode arrangement into a housing of a battery cell. The invention further relates to a battery cell for carrying out the method for clamping an electrode arrangement into a housing of a battery cell. The invention further relates to a computer program for clamping an electrode arrangement into a housing of a battery cell. The invention further relates to a computer-readable storage medium on which the computer program is stored.

[0004] Conventional batteries with a liquid, organic electrolyte are commonly used as traction batteries for vehicles. Lithium batteries containing a solid electrolyte offer an advantage over lithium batteries with conventional liquid, organic electrolytes because the electrolyte is non-flammable. Compared to conventional organic electrolytes, solid electrolytes exhibit significantly improved safety characteristics because they are not only non-flammable but also reduce lithium dendrite growth. Furthermore, due to the selectivity of the charge carriers and the high stability of solid electrolytes, both the cycle stability and the calendar life of the battery cell are generally improved.However, batteries with a solid electrolyte are problematic in that, compared to conventional batteries, the electrode layers and the solid electrolyte must be clamped within the battery cell with a high pressure of, for example, 100 bar in order to ensure stable and efficient operation of the battery cell.

[0005] One object underlying the invention is to provide a method for clamping an electrode arrangement into a battery cell housing, as well as a corresponding battery cell, computer program, and computer-readable storage medium. This object is achieved by the subject matter of the independent patent claims.

[0006] Advantageous embodiments are characterized in the subclaims.

[0007] According to a first aspect, the invention relates to a method for clamping an electrode arrangement into a housing of a battery cell.

[0008] The electrode arrangement here and below is, for example, an electrode arrangement of a rechargeable battery, in particular a solid-state battery. The electrode arrangement is thus, for example, a single rechargeable storage element for electrical energy. A battery cell comprises, in particular, the electrode arrangement installed in a battery housing.

[0009] The electrode assembly is arranged in the housing of the battery cell. The electrode assembly comprises a first contact foil, a first electrode layer, a solid electrolyte, and a second contact foil, wherein the solid electrolyte has a first and a second side. The first contact foil is arranged on the first side of the solid electrolyte, and the second contact foil is arranged on the second side of the solid electrolyte. The first electrode layer is arranged between the solid electrolyte and the first contact foil.

[0010] By applying a first voltage to the first and second contact foils to charge the electrode arrangement, the electrode arrangement is designed to deposit ions from the first electrode layer onto the second contact foil, thereby forming a second electrode layer between the second contact foil and the solid electrolyte. For example, this is an electrode arrangement of a lithium metal battery cell or an anode-free lithium battery cell.

[0011] Furthermore, the electrode arrangement is configured to incorporate ions from the second electrode layer into the first electrode layer by applying a second voltage to the first and second contact foils to discharge the electrode arrangement. According to at least one embodiment, the method involves charging the electrode arrangement, and forming the second electrode layer as a result of the charging.

[0012] For example, the electrode arrangement is arranged in the housing of the battery cell, wherein a hollow space exists between the electrode arrangement and the housing. The formation of the second electrode layer by charging the electrode arrangement increases the volume of the electrode arrangement. For example, the volume of the electrode arrangement is continuously increased with increasing charge level until the housing of the battery cell is completely filled with the electrode arrangement. The housing of the battery cell serves as a limit for any further increase in volume. Because any increase in volume upon further charging of the battery cell is limited by the housing, mechanical forces originating from the forming second electrode layer are transferred to the electrode arrangement and the housing of the battery cell, thereby increasing the pressure in the housing of the battery cell.Thus, the mechanical forces exerted by the forming second electrode layer and transferred to the electrode assembly and the battery cell housing depend on the battery cell's charge level. The battery cell's charge level represents the battery cell's cell voltage. In other words, the transferred mechanical forces, and thus the pressure within the housing, depend on the battery cell's cell voltage.

[0013] When the battery cell is discharged, the described process is reversed. The second electrode layer of the electrode assembly is degraded during discharge, reducing the volume of the second electrode layer and thus the volume of the electrode assembly and the mechanical forces transmitted by the second electrode layer, thereby reducing the pressure in the battery cell housing.

[0014] According to at least one embodiment, a final discharge voltage is set at which the second electrode layer remains at least partially between the second contact foil and the solid electrolyte, in order to establish a minimum pressure in the battery cell. For example, the partially remaining second electrode layer has a predetermined thickness.

[0015] By setting the cut-off voltage, the battery cell's discharge is terminated when the cut-off voltage is reached. For example, reaching a cut-off voltage is considered a discharged state of the battery cell. Advantageously, the second electrode layer, which is arranged at least partially between the second contact foil and the solid electrolyte, is thus not completely degraded and, even in the discharged state, exerts pressure on the electrode arrangement and the battery cell housing due to the transmitted mechanical forces.

[0016] For example, when the final discharge voltage is reached, the second electrode layer exerts a minimum pressure of 50 bar, 80 bar or 100 bar on the electrode arrangement and the housing of the battery cell in order to clamp the electrode arrangement in the housing of the battery cell.

[0017] Advantageously, the process allows for more efficient use of available installation space, as no additional devices, such as springs for bracing the electrode arrangement, are required. This increases the energy density within the available installation space, for example.

[0018] According to at least one embodiment, the final discharge voltage is determined as a function of an expected pressure in the housing of the battery cell.

[0019] The relationship between the final discharge voltage and the pressure within the battery cell casing ensures that sufficient pressure is maintained to clamp the electrode assembly within the battery cell casing. This ensures efficient operation of the battery cell.

[0020] For example, the relationship between the final discharge voltage and the pressure in the housing of the battery cell can be used to adjust the final discharge voltage if, for example, any requirements for the pressure to clamp the electrode arrangement change due to aging effects of the electrode arrangement.

[0021] According to at least one embodiment, the pressure in the housing of the battery cell depends on a cell chemistry of the electrode materials of the electrode arrangement and / or the volume between the electrode arrangement and the housing of the battery cell and / or a lithium content of the first electrode material.

[0022] Depending on the cell chemistry of the electrode materials of the electrode assembly, the optimal pressure for the operation of the battery cell can vary, which in turn causes the electrode assembly to be clamped with a higher or lower pressure in the housing of the battery cell.

[0023] For example, the pressure in the housing of the battery cell depends on a mass loading and / or a capacity loading of the electrode arrangement.

[0024] Alternatively or additionally, the pressure in the battery cell may depend on the size of the cavity between the electrode assembly and the battery cell housing. Alternatively or additionally, the pressure in the battery cell housing depends on the lithium content of the first electrode material, since the thickness of the formed electrode layer increases the more lithium is deposited from the first electrode material onto the first contact foil or the already formed electrode layer.

[0025] According to at least one embodiment, the electrode arrangement is mechanically coupled to the housing of the battery cell.

[0026] Through the mechanical coupling of the electrode arrangement with the housing of the battery cell, the mechanical forces, starting from the second electrode layer, are transferred to the housing of the battery cell.

[0027] According to at least one embodiment, the housing of the battery cell is designed as a cylindrical cell (round cell). A cylindrical battery cell format has known advantages, such as high energy density. Conventional solid-state battery cells have typically been used in pouch cell format, as clamping devices are used to apply the required pressure to clamp the electrode assembly in the battery cell housing. Due to the design of a round cell, a device for clamping the electrode assembly does not appear to be efficient.

[0028] By straining the electrode array through a change in volume and increasing the pressure through the mechanical forces of the forming second electrode layer, strain devices are no longer necessary, allowing the use of the cylindrical cell format.

[0029] The invention is further characterized by a battery cell with which the method for clamping an electrode arrangement into a housing of a battery cell can be carried out.

[0030] The invention is further characterized by a computer program for clamping an electrode arrangement into a housing of a battery cell, comprising instructions which, when the computer program is executed by a computer, cause the computer to carry out the method for clamping an electrode arrangement into a housing of a battery cell.

[0031] The invention is further characterized by a computer-readable storage medium on which the computer program is stored.

[0032] The computer-readable storage medium comprises, in particular, a medium readable by a data processing device on which program code is stored.

[0033] Embodiments of the invention are explained in more detail below with reference to the schematic drawings. Figure 1 shows a flowchart of a program for clamping an electrode arrangement into a battery cell housing.

[0034] Figure 2 shows a first embodiment of an electrode arrangement in a housing of a battery cell,

[0035] Figure 3 shows a second embodiment of an electrode arrangement in a housing of a battery cell,

[0036] Figure 4 shows a third embodiment of an electrode arrangement in a housing of a battery cell,

[0037] Elements of the same design or function are marked with the same reference symbols throughout the figures.

[0038] Figure 1 shows a flowchart of a program for clamping an electrode arrangement into a housing of a battery cell.

[0039] A device 50 is designed to process the program. For this purpose, the device 50 has in particular a computing unit, a program and

[0040] Data memory, as well as, for example, one or more communication interfaces. The program and data memory and / or the computing unit and / or the communication interfaces can be implemented in a single unit and / or distributed across multiple units.

[0041] The device 50 can also be referred to as a device for clamping an electrode arrangement into a housing of a battery cell.

[0042] For this purpose, the program is stored in particular on the program and data memory of the device 50.

[0043] The program is started in step S1, where variables can be initialized if necessary. In step S3, the electrode array 20 is loaded.

[0044] For example, the electrode arrangement 20 is a lithium metal electrode arrangement.

[0045] For example, the electrode assembly 20 is charged as soon as a first voltage is applied to the first and second contact foils 21, 25. For example, during charging, the electrode assembly 20 deposits lithium ions from the first electrode layer 21 onto the second contact foil 25, so that a second electrode layer 24, a lithium metal electrode layer, is formed between the second contact foil 25 and the solid electrolyte 23.

[0046] During a discharge, a second voltage is also applied to the first and second contact foils 21, 25, the polarity of the second voltage being different from the first voltage. By discharging the electrode arrangement 20, lithium ions are deposited from the second electrode layer 24 into the first electrode layer 21. The second electrode layer 24 is thereby degraded.

[0047] For example, the electrode arrangement 20 is fully charged over an entire capacity range.

[0048] In a step S5, a final discharge voltage is set.

[0049] By setting the final discharge voltage, it is ensured that the electrode arrangement 20 is not discharged below the final discharge voltage.

[0050] The final discharge voltage is set, for example, depending on the pressure in the battery cell housing 10 and / or the aging state of the battery cell. The discharge voltage, for example, is linearly related to the pressure in the battery housing 10. For example, the pressure in the housing 10 increases when the final discharge voltage is increased.

[0051] For example, the end-of-discharge voltage is set to prevent the second electrode layer 24 from being completely degraded during discharge. For example, with advanced aging of the battery cell, the available capacity decreases, whereupon the end-of-discharge voltage is reduced as the battery cell ages, depending on the aging state of the battery cell, in order to extract additional lithium from the second electrode layer 24 to counteract the aging of the battery cell and the reduction in the available capacity.

[0052] In an optional step S7, the electrode arrangement 20 is discharged.

[0053] The electrode assembly 20 is discharged, for example, to the specified end-of-discharge voltage. For example, the entire available capacity of the electrode assembly 20 is not utilized. For example, 10% of the available capacity remains in the second electrode layer 24 to prevent the second electrode layer 24 from being completely depleted. For example, the end-of-discharge voltage thus serves as a discharge limiter to maintain the pressure within the battery cell in such a way as to clamp the electrode assembly within the battery cell housing.

[0054] In step S9 the program is terminated and can be restarted if necessary.

[0055] Figure 2 shows a first embodiment of an electrode arrangement 20 in a housing of a battery cell.

[0056] According to Figure 2, an electrode arrangement 20 comprising a first contact foil 21, a first electrode layer 22, a solid electrolyte 23 and a second contact foil 25 is shown, which is arranged in a housing 10 of a battery cell.

[0057] A cavity exists between the first contact foil 21 and the housing 10 because the electrode assembly 20 is inserted into the housing 10 of the battery cell, but is not yet clamped in the housing 10 of the battery cell. Figure 3 shows a second exemplary embodiment of an electrode assembly 20 in a housing 10 of a battery cell. Figure 3 shows a fully charged state of the electrode assembly 20. In addition to the components of the electrode assembly 20 shown in Figure 2, Figure 3 shows the second electrode layer 24, which is formed by charging the electrode assembly 20.

[0058] Figure 3 also illustrates that the cavity is filled by increasing the volume of the electrode arrangement 20.

[0059] Figure 4 shows a third embodiment of an electrode assembly 20 in a housing 10 of a battery cell. Figure 4 shows the electrode assembly 20 after a discharge process up to the specified end-of-discharge voltage. The second electrode layer 24 is shown with a reduced thickness compared to the fully charged state of Figure 3.

[0060] List of reference symbols

[0061] S1-S9 steps

[0062] 10 housings

[0063] 20 Electrode arrangement

[0064] 21 first contact foil

[0065] 22 first electrode layer

[0066] 23 Solid electrolyte

[0067] 24 second electrode layer

[0068] 25 second contact foil

[0069] 50 device

Claims

Patent claims 1 . Method for clamping an electrode arrangement (20) into a housing (10) of a battery cell, wherein - the electrode arrangement (20) is arranged in the housing (10), - the electrode arrangement (20) comprises a first contact foil (21), a first electrode layer (22), a solid electrolyte (23) and a second contact foil (25), wherein the solid electrolyte (23) has a first and a second side, the first contact foil (21) is arranged on the first side and the second contact foil (25) is arranged on the second side of the solid electrolyte (23), and the first electrode layer (22) is arranged between the solid electrolyte (23) and the first contact foil (21), - the electrode arrangement (20) is designed to deposit ions from the first electrode layer (22) onto the second contact foil (25) by applying a first voltage to the first and second contact foils (21, 25) for charging the electrode arrangement (20), so that a second electrode layer (24) is formed between the second contact foil (25) and the solid electrolyte (23), - the electrode arrangement (20) is designed to store ions from the second electrode layer (24) into the first electrode layer (22) by applying a second voltage to the first and second contact foils (21, 25) for discharging the electrode arrangement (20), and in the method - the electrode arrangement (20) is charged and the second electrode layer (24) is formed by the charging, - a final discharge voltage is set at which the second electrode layer (24) remains at least partially between the second contact foil (25) and the solid electrolyte (23) in order to set a minimum pressure in the battery cell.

2. Method according to claim 1, wherein the final discharge voltage is set as a function of an expected pressure in the housing (10) of the battery.

3. The method according to claim 1 and 2, wherein the pressure in the housing (10) of the battery cell is dependent on a cell chemistry of the electrode materials of the electrode arrangement (20) and / or the volume between the electrode arrangement (20) and the housing (10) of the battery cell and / or a lithium content of the first electrode material.

4. Method according to one of the preceding claims, wherein the electrode arrangement (20) is mechanically coupled to the housing (10) of the battery cell.

5. Method according to one of the preceding claims, wherein the housing (10) of the battery cell is designed as a round cell.

6. Battery cell with which the method according to claim 1 is carried out.

7. Vehicle in which the battery cell according to claim 6 is arranged.

8. A computer program for clamping an electrode arrangement (20) into a housing (10) of a battery cell, comprising instructions which, when the computer program is executed by a computer, cause the computer to carry out the method according to one of claims 1 to 5.

9. A computer-readable storage medium on which the computer program according to claim 8 is stored.

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