Method for deriving process conditions for manufacturing curved batteries

Abstract

A method for deriving process conditions for manufacturing a curved battery according to one 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 curvature, and a third step of verifying the key factors selected in the second step using a predetermined experimental design.

Description

[Technical Field]

[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 outside of the left and right portions in the width direction or the top and bottom portions in the length direction. [Background technology]

[0002] In recent years, with technological development and increasing demand for mobile devices, the demand for secondary batteries as an energy source has increased dramatically.

[0003] Typically, there is a high demand for prismatic and pouch-type secondary batteries, which have a thin shape and are applicable to electronic devices such as mobile phones.

[0004] As consumer preferences lead to electronic devices becoming smaller and thinner, there is a demand for smaller and thinner batteries to minimize unnecessary space consumption.

[0005] Therefore, it is necessary to realize various battery shapes according to the shape of the device and to efficiently utilize the internal space of the device.

[0006] In particular, recently, device design itself has become a very important factor in consumers' product selection, and various designs have been developed, moving away from the conventional flat design that takes productivity into consideration.

[0007] For example, recently, devices such as mobile phones and notebook PCs are designed to have predetermined curved surfaces for ergonomic reasons.

[0008] Although many designs with curved outer surfaces have been developed and put into practical use, most of the commercially available secondary batteries have a flat shape, which results in unnecessary space waste.

[0009] Furthermore, due to the curved surface, it is difficult to mount the secondary battery securely, and external impact can cause the battery to move loosely, which can result in damage to the battery.

[0010] Specifically, as wearable functions of various IT devices have become popular, curved designs that take into account the shape of the human face have begun to appear on smartphones, creating a need for curved batteries that meet the design requirements of mobile phone customers.

[0011] Conventionally, only flat batteries were available, so manufacturing technology to create such curved shapes is required.

[0012] Since the outer shape of a pouch-type battery is made of a pouch material, it can be deformed by force, and this characteristic can be used to realize a curved shape for the battery.

[0013] However, although active research has been conducted recently into the manufacture of such curved batteries, it was unclear whether there would be any safety issues if curved batteries were manufactured.

[0014] Therefore, there is an urgent need for a technology to manufacture a pouch-type battery with an appropriate curved shape by deriving various factors within a range that does not affect the safety of the pouch-type battery. Summary of the Invention [Problem to be solved by the invention]

[0015] The present invention is intended to solve the above-mentioned conventional problems, and aims to provide a method for deriving process conditions for manufacturing a curved battery, which derives 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 outside of the left and right parts in the width direction or the top and bottom parts in the length direction. [Means for solving the problem]

[0016] To achieve the above-mentioned objectives, a method for deriving process conditions for manufacturing a curved battery according to one 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 curvature, and a third step of verifying the key factors selected in the second step using a predetermined experimental design.

[0017] In the first step, the positions at the bottom surface of the battery where the curvature should be measured may be selected from the left and right portions in the width direction or the top and bottom portions in the length direction.

[0018] The main factors may be the curvature value of the crimping jig, the pressure and temperature during crimping, and the crimping time.

[0019] The pressure, temperature and time during the crimping are preferably set to within 80% of the pressure, temperature and time used in manufacturing a battery.

[0020] The curvature value of the crimping jig is preferably selected to be smaller than the target curvature value of the bottom surface of the battery.

[0021] In the third step, batteries are manufactured for three levels having different values ​​for the four conditions of the main factors to be verified, namely, the curvature value of the crimping jig, the pressure and temperature during crimping, and the crimping time, and then the curvature can be measured at each position on the bottom of the battery selected in the first step where the curvature should be measured.

[0022] Statistical techniques can be used to select the effective rankings among four conditions: the curvature value of the crimping jig, the pressure and temperature during crimping, and the crimping time, and collect the condition values ​​that produce the result value closest to the target curvature value.

[0023] After manufacturing batteries under four conditions, namely the curvature value of the crimping jig, the pressure and temperature during crimping, and the crimping time, and three levels with different values, the curvature of each battery can be measured for the first time after storing them at room temperature for 3 to 4 hours.

[0024] Thus, it is preferable to design a tray with a curvature that corresponds to the initially measured curvature of the battery.

[0025] After manufacturing batteries under four different conditions, namely the curvature value of the crimping jig, the pressure and temperature during crimping, and three levels with different values ​​for the crimping time, it was possible to check whether there was a spring back phenomenon in which the curvature returns to its original state, and if so, to what extent.

[0026] After the battery is manufactured, it may be confirmed under what conditions the least amount of springback occurs during a predetermined time of storage, and whether the amount of springback occurs is within the target curvature value.

[0027] After the tray-packed batteries arrive at the final customer, the curvature of the batteries can be measured to find the conditions that cause the least springback phenomenon, and then final verification can be performed.

[0028] After manufacturing batteries under three different levels of four conditions, namely, the curvature value of the crimping jig, the pressure and temperature during crimping, and the crimping time, the performance, environmental reliability, and safety of the batteries can be verified. [Effects of the Invention]

[0029] 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 outside of the left and right parts in the width direction or the top and bottom parts in the length direction, various factors can be derived within a range that does not affect the safety of the battery, thereby reducing the time required to set conditions for manufacturing the curved battery shape and preventing competitors from approaching the market. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1 is a perspective view of a pouch-type battery. [Figure 2] FIG. 2 is a diagram schematically illustrating a side view of a curved battery. [Figure 3] This is a diagram showing the parts 1 to 4 used to measure curvature in a curved battery. [Figure 4] 1 is a flowchart illustrating a method for deriving process conditions for manufacturing a curved battery according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] The advantages and features of the present invention and methods for achieving them will become more apparent from the following detailed description of the embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and may be embodied in various different forms. These embodiments are provided solely to complete the disclosure of the present invention and to fully convey the scope of the invention to those skilled in the art. The present invention is defined only by the claims. Therefore, in some embodiments, well-known process steps, well-known device structures, and well-known techniques are not specifically described to avoid obscuring the present invention. The same reference numerals refer to the same elements throughout the specification.

[0032] In the drawings, thicknesses may be exaggerated to clearly show the various layers and regions. Similar parts are designated by the same reference numerals throughout the specification. When a layer, film, region, plate, or other part is said to be "on" another part, this includes not only the case where it is "directly on" the other part, but also the case where there are other parts between them. Conversely, when a part is said to be "directly on" another part, it means that there are no other parts between them. Furthermore, when a part is said to be "under" another part, this includes not only the case where it is "directly under" the other part, but also the case where there are other parts between them. Conversely, when a part is said to be "directly under" the other part, it means that there are no other parts between them.

[0033] Before describing a method for deriving process conditions for manufacturing a curved battery according to an embodiment of the present invention, a flat battery cell will be described.

[0034] FIG. 1 is a diagram showing an example of a pouch-type battery cell, and is a diagram showing a flat pouch-type battery cell.

[0035] The pouch-type battery cell 100 can include an electrode assembly and a cell case 115 that houses the electrode assembly.

[0036] The cell case 115 of the pouch-type battery cell 100 is for housing the electrode assembly and may be a pouch-type cell case 115.

[0037] The cell case 115 includes a lower case and an upper case that covers the lower case, and the upper and lower cases can be integrated.

[0038] Also, as shown in FIG. 1, the connecting portion of the upper and lower cases may be folded to form a folding structure.

[0039] As shown, the upper case completely covers the lower case, and a sealing portion 114 may be formed around the periphery.

[0040] Both the upper and lower cases can be laminate structures including an inner cladding layer, a metal layer, and an outer cladding layer.

[0041] The inner coating layer is located inside the cell casing 115 relative to the metal layer and is in direct contact with the electrode assembly, so it must have insulating and electrolytic resistance. In addition, to seal against the outside, the sealing properties, i.e., the sealing areas where the inner layers are thermally bonded together, must have excellent thermal adhesion strength.

[0042] The metal layer is located between the inner coating layer and the outer coating layer and serves as a barrier layer that prevents moisture and various gases from penetrating into the battery from the outside. A suitable material for the metal layer in contact with the inner coating layer is a thin film of aluminum (Al), which is lightweight yet has excellent formability.

[0043] The outer coating layer is located outside the cell casing 115 based on the metal layer. This outer coating layer can be made of a heat-resistant polymer with excellent tensile strength, moisture-proofing, and air-proofing properties to protect the electrode assembly while ensuring heat resistance and fire resistance. For example, nylon or polyethylene terephthalate can be used.

[0044] The upper and lower cases each have a receiving groove 116 formed therein, and the electrode assembly can be received in the receiving groove 116 of the upper and lower cases.

[0045] The electrode assembly accommodated in the cell case 115 may be one selected from the group consisting of a jelly-roll type electrode assembly having a structure in which a separator is interposed between a long sheet-shaped negative electrode and a positive electrode and then wound up; a stack type electrode assembly consisting of unit cells having a structure in which rectangular positive and negative electrodes are stacked with a separator between them; a stack-folding type electrode assembly in which unit cells are wound up with a long separator film; and a lamination-stack type electrode assembly in which unit cells are stacked with a separator between them and attached to each other.

[0046] The electrode assembly may also include two electrode tabs and two electrode leads 111 and 112 connected to the electrode tabs via welding.

[0047] One of the two electrode leads 111, 112 may be a positive electrode lead connected to a positive electrode tab, and the other electrode lead 111, 112 may be a negative electrode lead connected to a negative electrode tab.

[0048] A lead film 113 may be attached to each of the electrode leads 111 and 112. The lead film 113 connected to the electrode leads 111 and 112 is located between the electrode leads 111 and 112 and the cell case 115, and prevents short circuits from occurring between the electrode leads 111 and 112 and the cell case 115, and improves sealing strength to prevent leakage of electrolyte.

[0049] Although the two electrode leads 111, 112 are shown as being located on opposite sides of the electrode assembly, they may be located on only one side of the electrode assembly depending on the placement of the electrode tabs.

[0050] Next, a preferred embodiment of the method for deriving process conditions for manufacturing a curved battery according to the present invention will be described in detail with reference to the accompanying drawings.

[0051] In one embodiment of the present invention, a pouch-type curved battery will be described as an example.

[0052] However, the present invention is not limited to the pouch-type curved battery, but can also be applied to other types of curved batteries.

[0053] In addition, the pouch-type curved battery can be used for smartphones and other devices that use secondary batteries.

[0054] FIG. 2 is a diagram showing a schematic side view of a curved battery, and FIG. 3 is a diagram showing the parts of the curved battery for measuring curvature, numbered 1 to 4.

[0055] The curved battery 200 is a battery that is curved, and can be applied to various IT devices that require a curved design, such as not only curved smartphones but also smart watches and smart glasses.

[0056] The curved battery 200 can be manufactured by pressing the flat pouch-type battery cell 100 described above in a crimping jig at a predetermined temperature and pressure.

[0057] Therefore, after manufacturing the flat pouch-type battery cell 100, the curved battery 200 having a predetermined curvature can be manufactured.

[0058] The curved battery 200 shown in FIG. 2 is an example, and the central portion is formed flat (FLAT AREA), and the central portion may be formed obliquely downward with a predetermined curvature (R) from the end of the flat portion to the edge.

[0059] The present invention relates to a method for deriving process conditions for manufacturing a curved battery with a specific curvature. The position for measuring the curvature on the bottom surface of the battery can be selected from the left and right parts in the width direction or the top and bottom parts in the length direction, as shown in FIG.

[0060] FIG. 4 is a flowchart showing a step-by-step method for deriving process conditions for manufacturing a curved battery according to the present invention.

[0061] The 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 for 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.

[0062] A method for deriving process conditions for manufacturing such a curved battery will be described below.

[0063] [Confirming the target curvature (R) value - S1] 1. Acceptance of customer specifications for target curvature value and establishment of production target level (center value + tolerance) 2. It is not possible to measure the entire area of ​​the battery, so select the actual location to be measured.

[0064] -Selected part that can represent the entire curvature of the battery -You can also distribute it equally left and right / up and down.

[0065] - Discuss with the customer the "inspection method".

[0066] [Selection of key factors - S2] Establishment of manufacturing conditions at a predetermined level to create the curvature 1. You can refer to the manufacturing method of battery cells.

[0067] -When manufacturing battery cells, there is a pressing process that involves pressure, temperature, and time.

[0068] -The pressure / temperature / time during battery cell manufacturing should not be exceeded. For example, when manufacturing the flat pouch-type battery 100, the pressure / temperature / time can be prevented from being exceeded (within 80% of the manufacturing conditions of the battery cell (battery cell before the carving process) in consideration of a safety margin).

[0069] 2. Since a specific curvature is manufactured, there is a high possibility of spring back from the curvature value at the time of crimping, so it is selected to be smaller than the target curvature (R) value.

[0070] 3. Therefore, a total of four conditions are selected as manufacturing conditions.

[0071] -Crimping equipment curvature value (curvature value of equipment jig), pressure during crimping, temperature during crimping, crimping time [Verification of main factors - S3] 1.Equipment production The production of equipment for actually manufacturing curved batteries is important, and the equipment is manufactured taking into consideration the appropriate size, convenience, and stability functions in consideration of the production plan.

[0072] (1) The crimping equipment (jig) uses insulated metal (so it can withstand pressure). (2) During the battery seating process, an escape space is formed to prevent parts other than the battery body from being pressed.

[0073] (3) Since it is dangerous if the machine is pressed while there is someone inside, various safety sensors will be installed.

[0074] (4) It is important to seat the battery in the exact center before pressing, so use a spring or similar when manufacturing the seating / position guide part.

[0075] (5) Since high-temperature equipment is used, the basic heating time / surrounding safety conditions, etc. should be confirmed.

[0076] Using the equipment thus manufactured, batteries are directly manufactured for the four conditions to be verified (curvature value of the crimping jig, pressure and temperature during crimping, and crimping time) / three levels (different values), and then the data is inspected / analyzed according to the 'inspection position' planned in the first stage, which is the stage of establishing the target curvature (R) value.

[0077] 2. Manufacture and initial measurement of a curved battery with actual curvature Statistical techniques are used to sort out the effective ranking of each condition and collect the condition values ​​that produce the result value closest to the target curvature value.

[0078] (1) The experimental design method does not need to be specific in nature, and techniques that are deemed effective for each experiment should be utilized.

[0079] (2) Divide into three levels based on conditions (see Table 1 below).

[0080] -As a result, a total of four conditions / three levels of experimental design (DOE) will be carried out.

[0081] (3) After the battery is manufactured, the first test is performed after the minimum "temperature" has returned to room temperature (approximately 3 to 4 hours after storage at room temperature). In experimental design, the Taguchi method is an experimental method for quickly and cheaply finding optimal conditions for experimental factors and levels in product design.

[0082] This experimental method complements the advantages and disadvantages of the full factorial experiment and the one-at-a-time experiment. After creating an orthogonal array to determine the level of each factor, it searches for the optimal conditions with the minimum number of experiments. [Table 1]

[0083] Table 1 above is an example of an orthogonal array according to Taguchi experimental design, in which three factors, namely, radius of curvature, pressure, and temperature, are each arranged at three levels.

[0084] That is, the radius of curvature is set to 20mm, 24mm, and 28mm, and the pressure is set to 500kg. f , 600kg f , 700kg f The temperature was set to 40°C, 60°C, and ℃.

[0085] In the present invention, in addition to the three factors in Table 1, it is preferable to set the compression time to 3 seconds, 5 seconds, and 7 seconds, and carry out the process at three levels for four factors.

[0086] 3. Tray design (selection of tray curvature based on initial measurement values) - S4 It is necessary to design a tray that corresponds to the shape of the curved battery manufactured in a curvature shape.

[0087] (1) The curvature value of the tray is not the same as the final target curvature value.

[0088] (2) Since the battery is packaged in the tray immediately after manufacturing, the tray must be manufactured to the minimum battery curvature value first measured. If the battery curvature (R) is adjusted to the target value, it will be forced to expand due to the springback phenomenon.

[0089] 4. Verification of springback (natural leaving) - S5 After the battery is manufactured, we check whether there is a springback phenomenon, in which the curvature returns to its original shape over a certain period of time, and if so, what level it is.

[0090] (1) When conducting a design of experiments (DOE) to select key factors, it is necessary to leave the battery for a specific period of time after manufacturing and confirm the conditions under which the amount of spring back occurs the least during that time and whether that amount of spring back occurs within the customer's target curvature value.

[0091] (2) The storage time must be confirmed as the number of hours / days from the production line to the time of final arrival and use at the customer's company.

[0092] 5. Comprehensive springback verification (verification of curvature value after battery products packaged in trays arrive at the end customer) - S6 Although we have examined the change in curvature value taking into account the various circumstances, we must ultimately look at the state after the actual logistics movement of the customer company.

[0093] After finding the optimum conditions confirmed by the first DOE and the conditions with the least secondary springback phenomenon, the final comprehensive verification is carried out again within those conditions.

[0094] [Performance / Safety Verification - S6] After forming the curvature according to the manufacturing conditions for forming the curvature, it must be verified whether there are any abnormalities in the final performance / environmental reliability / safety of the battery.

[0095] The "Factor Verification" is a process of examining the physical shape, and it is necessary to verify whether there are any abnormalities in the battery's inherent performance, environmental reliability, and safety (capacity, short circuit safety, etc.).

[0096] Performance / safety verification can be performed by selecting all items of the basic performance / reliability / safety of the battery or only some items that are deemed to have an impact (items generally required by the customer + additional items added by the customer). for example, Performance: Battery pack capacity, various functional tests (electrical function), pouch wrinkles in simple appearance, etc. Environmental reliability: High temperature and humidity, drop environment, thermal shock environment, etc. Safety: Tearing / leakage, electrode detachment, electrode slippage, pouch wrinkles, separator changes, pouch damage, sealing damage, overcharging, hot box, etc.

[0097] [Final completion - Condition priority and creation of optimal condition table - S6] The optimum conditions found through the above series of procedures (which may be applied in combination depending on the situation) are divided into two or three types and the order of priority is determined.

[0098] During actual mass production, it is certainly possible that the target curvature value may not be met under certain conditions, so it is important to determine the order of options.

[0099] Whenever possible, all data verified using design of experiments (DOE) will be recorded and transmitted as manufacturing know-how so that it can be used to correct conditions when troubleshooting occurs.

[0100] The present invention described above is not limited to the above-described embodiments and accompanying drawings, and it will be apparent to those skilled in the art that various substitutions, modifications and changes can be made without departing from the technical spirit of the present invention.

Claims

1. The first step is to confirm the target value of the curvature of the battery bottom. A second step of selecting key factors for manufacturing a battery having the curvature; A method for deriving process conditions for manufacturing a curved battery, comprising: a third step of verifying the main factors selected in the second step using a predetermined experimental design method.

2. 2. The method of claim 1, wherein in the first step, the left and right portions in the width direction or the top and bottom portions in the length direction are selected as the positions on the bottom surface of the battery where the curvature should be measured.

3. 2. The method of claim 1, wherein the main factors are a curvature value of a crimping jig, a pressure and temperature during crimping, and a crimping time.

4. 4. The method of claim 3, wherein the pressure, temperature, and time during crimping are set to within 80% of the pressure, temperature, and time required for manufacturing a battery.

5. 4. The method of claim 3, wherein the curvature value of the crimping jig is selected to be smaller than the target curvature value of the bottom surface of the battery.

6. 4. The method of claim 3, wherein the third step comprises manufacturing batteries for three levels having different values ​​of the four conditions of the main factors to be verified, namely, a curvature value of a crimping jig, a pressure and temperature during crimping, and a crimping time, and then measuring the curvature at each position on the bottom surface of the battery selected in the first step where the curvature is to be measured.

7. 7. The method for deriving process conditions for manufacturing a curved battery according to claim 6, wherein a statistical technique is used to select an effective ranking from four conditions, namely, the curvature value of the crimping jig, the pressure and temperature during crimping, and the crimping time, and the condition values ​​that produce a result value closest to the target curvature value are collected.

8. 7. The method for deriving process conditions for manufacturing a curved battery according to claim 6, wherein batteries are manufactured under three different conditions, namely, the curvature value of the crimping jig, the pressure and temperature during crimping, and the crimping time, and then the curvature of each battery is measured after storing the batteries at room temperature for three to four hours.

9. 9. The method of claim 8, further comprising the step of designing a tray having a curvature corresponding to the initially measured curvature of the battery.

10. 10. The method of claim 9, wherein after manufacturing batteries for three levels having different values ​​for four conditions, namely, a curvature value of a crimping jig, pressure and temperature during crimping, and crimping time, it is confirmed whether or not a springback phenomenon occurs, in which the curvature is restored, and if so, to what extent.

11. 11. The method of claim 10, further comprising: determining a condition under which the amount of springback generated is the smallest during a predetermined time period after the battery is manufactured, and whether the amount of springback generated is within a target value of the curvature.

12. 12. The method of claim 11, further comprising: measuring the curvature of the battery after the tray-packed battery arrives at the final customer; searching for a condition that minimizes springback; and then performing final verification.

13. 9. The method of claim 8, wherein batteries are manufactured for three levels having different values ​​for four conditions, namely, a curvature value of a crimping jig, a pressure and temperature during crimping, and a crimping time, and then the performance, environmental reliability, and safety of the batteries are verified.

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