Process condition derivation method for manufacturing curved battery

Abstract

A process condition derivation method for manufacturing a curved battery according to an embodiment of the present invention comprises: a first step for identifying a target value for the curvature of the bottom surface of a battery; a second step for selecting main factors for manufacturing the battery having the curvature; and a third step for verifying the main factors, selected in the second step, by a certain design of experiments method.

Description

Method for deriving process conditions for manufacturing curved batteries

[0001] The present invention relates to a method for deriving process conditions for manufacturing a curved battery, and more particularly, to a method for deriving actual process conditions for manufacturing a curved battery having a specific curvature on the outer side of a widthwise left-right portion or a lengthwise top-bottom portion.

[0002]

[0003] With the recent increase in technological development and demand for mobile devices, the demand for secondary batteries as an energy source is rapidly increasing.

[0004] In terms of battery shape, there is a high demand for square secondary batteries and pouch-type secondary batteries that can be applied to electronic devices such as mobile phones due to their thin thickness.

[0005] As electronic devices are becoming increasingly smaller and thinner in line with consumer tastes, the shape of batteries is also being required to be smaller and thinner to minimize unnecessary space waste.

[0006] Therefore, it is necessary to implement the shape of the battery in various ways according to the shape of the device and at the same time efficiently utilize the internal space of the device.

[0007] In particular, recently, the design of the device itself has become a very important factor in consumers' product selection, so various types of designs are being designed, moving away from the conventional flat design that took productivity into consideration.

[0008] For example, recently, devices such as cell phones and laptops are being designed with curved surfaces for ergonomic design.

[0009] In this way, many designs with curved surfaces on the outer surface have been developed and put into practical use, but most of the secondary batteries that have been commercialized are flat, resulting in unnecessary waste of space.

[0010] In addition, because of these curves, it is difficult to stably mount the secondary battery, and the battery may be damaged by movement due to external impact.

[0011] Specifically, as the wearable functions of various IT devices gained attention, curved designs that took the shape of the human face into account began to appear in smartphones, and accordingly, curved batteries that met the design requests of mobile phone customers became necessary.

[0012] Previously, only flat-shaped batteries were available, so manufacturing technology to create these curved shapes was needed.

[0013] Pouch-type batteries have an exterior made of pouch material, so they can be deformed according to force, and by utilizing this characteristic, the battery shape can be implemented in a curved shape.

[0014] However, although the manufacturing of such curved batteries has been actively researched recently, it has not been known whether there are any safety issues even if a curved battery is manufactured.

[0015] Accordingly, there is an urgent need for technology to manufacture pouch-type batteries with an appropriate curved shape by deriving various factors within a range that does not affect the safety of pouch-type batteries.

[0016]

[0017] The present invention is intended to solve the conventional problems as described above, and provides a method for deriving process conditions for manufacturing a curved battery to derive various factors within a range that does not affect the safety of the battery when manufacturing a curved battery having a specific curvature on the outer side of the widthwise left and right portions or the lengthwise top and bottom portions.

[0018]

[0019] In order to achieve the above objectives, a method for deriving process conditions for manufacturing a curved battery according to an embodiment of the present invention includes a first step of confirming a target value of the curvature of the bottom surface of the battery; a second step of selecting key factors for manufacturing a battery having the above curvature; and a third step of verifying the key factors selected in the second step using a predetermined experimental design method.

[0020] In the first step, the location at which the curvature is measured on the bottom surface of the battery can be selected as the left and right portions in the width direction or the upper and lower portions in the length direction.

[0021] The above key factors may be the curvature value of the pressing jig, the pressure and temperature during pressing, and the pressing time.

[0022] It is desirable that the pressure, temperature, and time during the above pressing be set within 80% of the pressure, temperature, and time used when manufacturing a battery.

[0023] It is preferable that the curvature value of the above pressing jig be selected to be smaller than the target value of the curvature of the bottom surface of the battery.

[0024] In the third step, after manufacturing a battery for three different levels of the four conditions of the main factors to be verified, namely the curvature value of the pressing jig, the pressure and temperature during pressing, and the pressing time, the curvature can be measured at each location on the bottom of the battery selected in the first step.

[0025] By utilizing statistical techniques, the effective ranking can be selected among the four conditions of the curvature value of the pressing jig, the pressure and temperature during pressing, and the pressing time, and the condition value that produces the result value closest to the target curvature value can be collected.

[0026] After manufacturing the batteries for three different levels with four conditions: the curvature value of the pressing jig, the pressure and temperature during pressing, and the pressing time, the curvature of each battery can be measured for the first time after storing them at room temperature for 3 to 4 hours.

[0027] It is desirable to design a tray having a curvature corresponding to the curvature of the battery measured for the first time.

[0028] After manufacturing a battery under four conditions: the curvature value of the pressing jig, the pressure and temperature during pressing, the pressing time, and three levels with different values, it is possible to check whether there is a spring back phenomenon in which the curvature returns to its original state, and if so, to what extent.

[0029] After manufacturing the above battery, it is possible to check whether the condition for the least amount of spring back generation during a predetermined standing time is met and whether the amount generated is within the target curvature value.

[0030] After the batteries packaged in the above trays arrive at the final customer, the curvature of the batteries can be measured to find the conditions that minimize springback phenomenon, and then final verification can be performed.

[0031] After manufacturing a battery for three different levels with four conditions: the curvature value of the pressing jig, the pressure and temperature during pressing, and the pressing time, the performance, environmental reliability, and safety of the battery can be verified.

[0032]

[0033] According to the method for deriving process conditions for manufacturing a curved battery according to the present invention, when manufacturing a curved battery having a specific curvature on the outer side of the widthwise left and right portions or the lengthwise upper and lower portions, by deriving various factors within a range that does not affect the safety of the battery, the time required to set conditions for manufacturing a curved battery shape can be reduced, and there is an effect of preventing competitors from accessing the market.

[0034]

[0035] Figure 1 is a perspective view of a pouch-type battery.

[0036] Figure 2 is a schematic drawing showing the side of a curved battery.

[0037] Figure 3 is a drawing showing parts for measuring curvature in a curved battery, indicated as (1) to (4).

[0038] Figure 4 is a flowchart showing a method for deriving process conditions for manufacturing a curved battery according to the present invention step by step.

[0039]

[0040] The advantages and features of the present invention, and the methods for achieving them, will become clearer with reference to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms. These embodiments are provided only to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Accordingly, in some embodiments, well-known process steps, well-known device structures, and well-known techniques are not specifically described to avoid ambiguity in the interpretation of the present invention. Like reference numerals refer to like elements throughout the specification.

[0041] In order to clearly represent multiple layers and regions in the drawings, the thickness may be enlarged. Similar parts are designated by the same drawing reference numerals throughout the specification. When an element such as a layer, film, region, or plate is said to be "over" another element, this includes not only the case where it is "directly over" that element but also the case where there are other elements in between. Conversely, when an element is said to be "directly over" another element, this means that there are no other elements in between. Furthermore, when an element such as a layer, film, region, or plate is said to be "under" another element, this includes not only the case where it is "directly under" that element but also the case where there are other elements in between. Conversely, when an element is said to be "directly under" another element, this means that there are no other elements in between.

[0042] Before explaining a method for deriving process conditions for manufacturing a curved battery according to an embodiment of the present invention, a flat battery cell is described.

[0043] Figure 1 is a drawing illustrating an example of a pouch-type battery cell, and is a drawing illustrating a flat pouch-type battery cell.

[0044] A pouch-type battery cell (100) may include an electrode assembly and a cell case (115) that accommodates the electrode assembly.

[0045] The cell case (115) of the pouch-type battery cell (100) is for accommodating the electrode assembly and may be a pouch-type cell case (115).

[0046] The cell case (115) includes a lower case and an upper case covering the lower case, and the upper and lower cases can be formed as one piece.

[0047] Additionally, as shown in Fig. 1, the connecting portion of the upper and lower cases can be formed into a structure in which they are bent and folded.

[0048] And, as shown, the upper case can completely cover the lower case and a sealing portion (114) can be formed at the periphery.

[0049] Both the upper and lower cases can be made of a laminate structure including an inner covering layer, a metal layer, and an outer covering layer.

[0050] The inner covering layer is located on the inside of the cell case (115) based on the metal layer, and since it comes into direct contact with the electrode assembly, it must have insulation and electrolytic resistance. In addition, in order to seal it from the outside, the sealing area where the inner layers are thermally bonded must have excellent thermal bonding strength.

[0051] The metal layer is located between the inner and outer covering layers and serves as a barrier layer that prevents moisture or various gases from penetrating into the battery from the outside. A preferred material for the metal layer in contact with the inner covering layer is a lightweight aluminum (Al) thin film with excellent formability.

[0052] The outer covering layer is located on the outside of the cell case (115) based on the metal layer, and this outer covering layer can use a heat-resistant polymer with excellent tensile strength, moisture permeability, and air permeability to protect the electrode assembly while ensuring heat resistance and chemical resistance. For example, nylon or polyethylene terephthalate can be used.

[0053] A receiving groove (116) can be formed in each of the upper and lower cases, and an electrode assembly can be accommodated in the receiving groove (116) of the upper and lower cases.

[0054] The electrode assembly housed in the cell case (115) may be one of a group consisting of a jelly-roll type electrode assembly having a structure in which a separator is interposed between long sheet-shaped positive and negative electrodes and then rolled up, a stack type electrode assembly having unit cells having a structure in which rectangular positive and negative electrodes are stacked with a separator interposed between them, a stack-folding type electrode assembly in which the unit cells are rolled up by a long separator film, and a lamination-stack type electrode assembly in which the unit cells are stacked with a separator interposed between them and attached to each other.

[0055] Additionally, the electrode assembly may include two electrode tabs and two electrode leads (111, 112) each connected to the electrode tabs by a weld.

[0056] One of the two electrode leads (111, 112) may be a positive lead connected to the positive tab, and the other electrode lead (111, 112) may be a negative lead connected to the negative tab.

[0057] A lead film (113) may be attached to each of the electrode leads (111, 112).

[0058] The lead film (113) coupled to the electrode leads (111, 112) is positioned between the electrode leads (111, 112) and the cell case (115) to prevent a short circuit from occurring between the electrode leads (111, 112) and the cell case (115) and to improve the sealing force, thereby preventing leakage of the electrolyte, etc.

[0059] The two electrode leads (111, 112) are shown as being arranged on each side of the electrode assembly, but may be arranged on only one side of the electrode assembly depending on the arrangement of the electrode tabs.

[0060]

[0061] Next, a preferred embodiment of a method for deriving process conditions for manufacturing a curved battery according to the present invention will be described in detail based on the attached drawings.

[0062] In one embodiment of the present invention, a pouch-type curved battery is described as an example.

[0063] However, the present invention is not limited to pouch-type curved batteries and can be applied to other types of curved batteries.

[0064] Additionally, the pouch-type curved battery can be used for smartphones and other devices that use secondary batteries.

[0065]

[0066] Fig. 2 is a schematic drawing showing the side of a curved battery, and Fig. 3 is a drawing showing parts for measuring curvature in a curved battery, indicated as (1) to (4).

[0067] A curved battery (200) is a battery that is bent in a curved shape and can be applied to various IT devices that require a curved design, such as curved smartphones, smart watches, and smart glasses.

[0068] The curved battery (200) can be manufactured by pressing the above-described flat pouch-shaped battery cell (100) with a compression jig at a predetermined temperature and pressure.

[0069] Accordingly, after manufacturing a flat pouch-shaped battery cell (100), a curved battery (200) having a predetermined curvature can be manufactured.

[0070] The curved battery (200) illustrated in FIG. 2 is exemplary, and the central portion is formed flat (FLAT AREA), and may be formed to have a predetermined curvature (R) from the end of the flat portion of the central portion to the edge and to slope downward.

[0071] The present invention relates to a method for deriving process conditions for manufacturing a curved battery having a specific curvature, and a location for measuring the curvature on the bottom surface of the battery can be selected as a left-right portion in the width direction or an up-down portion in the length direction as shown in FIG. 3.

[0072]

[0073] Figure 4 is a flowchart showing a method for deriving process conditions for manufacturing a curved battery according to the present invention step by step.

[0074] A method for deriving process conditions for manufacturing a curved battery according to the present invention may include a first step (S1) of confirming a target value of the curvature of the bottom surface of the battery, a second step (S2) of selecting key factors for manufacturing a battery having such curvature, and a third step (S3) of verifying the key factors selected in the second step (S2) using a predetermined experimental design method.

[0075] The method for deriving process conditions for manufacturing such curved batteries is explained as follows.

[0076]

[0077] [Check target curvature (R) value - S1]

[0078] 1. Receive customer specifications for target curvature values ​​and establish production target levels (center value + tolerance)

[0079] 2. Since it is not possible to measure the entire battery area, select the actual location to measure.

[0080] - Selected as a place that can represent the entire battery curvature status

[0081] - You can also distribute equally left and right / up and down.

[0082] - Discuss the ‘inspection method’ with the customer.

[0083]

[0084] [Key Factor Selection-S2]

[0085] Establishing a certain level of manufacturing conditions to create the corresponding curvature

[0086] 1. You can refer to the manufacturing method of battery cells.

[0087] - There is a pressing process using pressure / temperature / time during battery cell manufacturing.

[0088] - Do not exceed the pressure / temperature / time required for manufacturing battery cells. For example, do not exceed the pressure / temperature / time required for manufacturing flat pouch-type batteries (100) (considering a safety margin, do not exceed 80% of the battery cell manufacturing conditions (battery cells before the curving process)).

[0089] 2. It is manufactured to a specific curvature, and is selected to be smaller than the target curvature (R) value because it is more likely to spring back than the curvature value at the time of pressing.

[0090] 3. Accordingly, a total of four conditions are selected as manufacturing conditions.

[0091] - Compression equipment curvature value (curvature value of equipment jig), compression pressure, compression temperature, compression time

[0092]

[0093] [Key Factor Verification-S3]

[0094] 1. Equipment manufacturing

[0095] It is important to build equipment to manufacture actual curved batteries, and the equipment should be built with appropriate size, convenience, and stability features in mind, taking into account the production plan.

[0096] (1) The pressing equipment (jig) uses insulated metal (therefore, it can withstand pressure).

[0097] (2) In the process of installing the battery, a space is created to avoid pressing parts other than the battery body.

[0098] (3) Since it is dangerous to press while a person's hand is present, various safety sensors are installed.

[0099] (4) It is important to press the battery after placing it in the ‘center’, so use a spring, etc. when making the placement / position guide part.

[0100] (5) Since equipment heated to high temperatures is used, it is possible to check the basic heating time / surrounding safety conditions, etc.

[0101] Through the equipment manufactured in this way, a battery is directly manufactured for the four conditions to be verified (curvature value of the pressing jig, pressure and temperature during pressing, pressing time) / three levels (different values), and then the data is inspected / analyzed for each ‘inspection location’ planned in the first stage, which is the stage of establishing the target curvature (R) value.

[0102]

[0103] 2. Fabrication and first measurement of a curved battery with actual curvature.

[0104] We use statistical techniques to select the effective rank of each condition and collect the condition values ​​that produce the result value closest to the target curvature value.

[0105] (1) There is no need to specify the experimental design method, and each method can be used if it is deemed effective.

[0106] (2) It is divided into 3 levels by condition (see Table 1 below).

[0107] - As a result, a total of 4 conditions / 3 levels of experimental design (design of experiments, DOE) are conducted.

[0108] (3) After manufacturing the battery, the initial inspection should be conducted after the temperature has returned to room temperature (approximately 3-4 hours when stored at room temperature).

[0109]

[0110] Among experimental design methods, the Taguchi method is an experimental method that allows one to inexpensively and quickly find the optimal conditions for experimental factors and levels in product design.

[0111] This is a method that complements the advantages and disadvantages of the full-combination method and the one-time single-stage method among experimental methods. It creates an orthogonal array to determine the level of each factor and then finds the optimal conditions with the minimum number of experiments.

[0112]

[0113] [Table 1] Orthogonal array table using Taguchi's experimental design (example)

[0114]

[0115]

[0116] Table 1 above is an example of an orthogonal array table using the Taguchi experimental design method, in which the three factors, radius of curvature, pressure, and temperature, are each arranged at three levels.

[0117] That is, the radius of curvature is 20 mm, 24 mm, 28 mm, and the pressure is 500 kg. f , 600 kg f , 700 kg f , and the temperature was selected as 40 ℃60 ℃℃.

[0118] In the present invention, in addition to the three factors in Table 1, it is preferable to proceed with three levels of four factors, with the compression time being 3 seconds, 5 seconds, and 7 seconds.

[0119]

[0120] 3. Tray design (selecting the tray curvature based on the initial measurement) - S4

[0121] A tray design corresponding to the shape of a curved battery manufactured in a shape with a curvature is required.

[0122] (1) The curvature value of the tray is not the same as the final target curvature value.

[0123] (2) Since the battery is packaged in a tray immediately after production, the tray must be manufactured with at least the initial measured value of the battery curvature. This is because if the target curvature (R) value is adjusted, it will be forcibly straightened due to the sprang-back phenomenon.

[0124]

[0125] 4. Springback Verification (Natural Leaving) - S5

[0126] After the battery is manufactured, check whether or not there is a spring back phenomenon, in which the curvature returns to its original state after a certain period of time, and if so, to what extent.

[0127] (1) When conducting a design of experiments (DOE) to select key factors, the battery must be left for a certain period of time after manufacturing, and it must be confirmed that the conditions for the least amount of spring back during the leaving time are met and that the amount of spring back is within the customer's target curvature value.

[0128] (2) The storage time must be confirmed as the time / date from the manufacturing line to the final arrival and use at the customer site.

[0129]

[0130] 5. Springback Comprehensive Verification (Confirmation of the curvature value after the battery product packed in the tray arrives at the end customer) -S6

[0131] We have checked the change in curvature value considering the various situations above, but ultimately, we must see the actual status after the logistics movement to the customer.

[0132] After finding the optimal conditions confirmed through the first design of experiments (DOE) and the conditions with the least secondary springback phenomenon, a final comprehensive verification is conducted once more within those conditions.

[0133]

[0134] [Performance / Safety Verification - S6]

[0135] After forming the curvature according to the manufacturing conditions for forming the curvature, it must be verified that there are no abnormalities in the final performance / environmental reliability / safety of the battery.

[0136] The above 'Key Factor Verification' is a process of reviewing the physical shape, and it is necessary to verify that there are no abnormalities in the battery's unique performance / environmental reliability / safety (capacity, short-circuit safety, etc.).

[0137] Performance / safety verification can cover all of a battery's fundamental performance, reliability, and safety criteria, or select only those items deemed potentially impactful (customer-required items + optional extras).

[0138] For example,

[0139] Performance: Capacity of battery pack, various function tests (electrical function), etc., simple appearance, pouch wrinkles, etc.

[0140] Environmental reliability: high temperature and high humidity environments, drop environments, thermal shock environments, etc.

[0141] Safety: tearing / leakage, electrode detachment, electrode slip, pouch wrinkles, separator change, pouch damage, sealing damage, overcharging, hot box, etc.

[0142]

[0143] [Final Completion - Condition Priority and Optimal Condition Table Creation - S6]

[0144] Based on the above sequence (which can be applied in combination depending on the situation), the optimal conditions are found and prioritized into 2-3.

[0145] It is important to prioritize options, as there may clearly be cases where the target curvature value is not satisfied under certain conditions during actual mass production.

[0146] If possible, all data verified through the Design of Experiments (DOE) method should be recorded and transferred as manufacturing know-how so that it can be used to modify conditions when troubleshooting occurs.

[0147]

[0148] The present invention described above is not limited to the above-described embodiments and the attached drawings, and it will be apparent to a person skilled in the art to which the present invention pertains that various substitutions, modifications, and changes are possible within a scope that does not depart from the technical spirit of the present invention.

Claims

1. The first step is to check the target value of the curvature of the bottom of the battery; A second step of selecting key factors for manufacturing a battery having the above curvature; and A third step of verifying the key factors selected in the second step using a predetermined experimental design method; Method for deriving process conditions for manufacturing curved batteries.

2. In claim 1, In the above first step, the location for measuring the curvature on the bottom surface of the battery is selected as the left and right part in the width direction or the upper and lower part in the length direction. Method for deriving process conditions for manufacturing curved batteries.

3. In claim 1, The above main factors are characterized by the curvature value of the pressing jig, the pressure and temperature during pressing, and the pressing time. Method for deriving process conditions for manufacturing curved batteries.

4. In claim 3, The above compression pressure and temperature, and compression time are set to within 80% of the pressure, temperature, and time used when manufacturing batteries. Method for deriving process conditions for manufacturing curved batteries.

5. In claim 3, The curvature value of the above pressing jig is selected to be smaller than the target value of the curvature of the bottom surface of the battery. Method for deriving process conditions for manufacturing curved batteries.

6. In claim 3, The third step above is, After manufacturing the battery for the four conditions of the above main factors to be verified, which are the curvature value of the pressing jig, the pressure and temperature during pressing, the pressing time, and three levels with different values, the curvature is measured at each location on the bottom of the battery selected in the first step. Method for deriving process conditions for manufacturing curved batteries.

7. In claim 6, Using statistical techniques, the effective ranking is selected among the four conditions of the curvature value of the pressing jig, the pressure and temperature during pressing, and the pressing time, and the condition value that produces the result value closest to the target value of the curvature is collected. Method for deriving process conditions for manufacturing curved batteries.

8. In claim 6, After manufacturing the batteries for four conditions, namely the curvature value of the pressing jig, the pressure and temperature during pressing, the pressing time, and three levels with different values, the curvature of each battery was measured for the first time after storing them at room temperature for 3 to 4 hours. Method for deriving process conditions for manufacturing curved batteries.

9. In claim 8, Designing a tray having a curvature corresponding to the curvature of the first measured battery. Method for deriving process conditions for manufacturing curved batteries.

10. In claim 9, After manufacturing the battery for four conditions, which are the curvature value of the pressing jig, the pressure and temperature during pressing, the pressing time, and three different levels, we checked whether there was a spring back phenomenon in which the curvature returned to its original state, and if so, to what extent. Method for deriving process conditions for manufacturing curved batteries.

11. In claim 10, After manufacturing the above battery, the condition of the least amount of spring back generation during a predetermined standing time and whether the amount of generation is within the curvature target value are checked. Method for deriving process conditions for manufacturing curved batteries.

12. In claim 11, After the batteries packed in the above trays arrive at the final customer, the curvature of the batteries is measured to find the condition with the least springback phenomenon, and then the final verification is performed. Method for deriving process conditions for manufacturing curved batteries.

13. In claim 8, After manufacturing the battery for four conditions, namely the curvature value of the pressing jig, the pressure and temperature during pressing, the pressing time, and three levels with different values, the performance, environmental reliability, and safety of the battery are verified. Method for deriving process conditions for manufacturing curved batteries.

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