WO2021002701A1 - 저전류 검사를 활용한 웨팅 정도 판별 방법 - Google Patents
저전류 검사를 활용한 웨팅 정도 판별 방법 Download PDFInfo
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- WO2021002701A1 WO2021002701A1 PCT/KR2020/008661 KR2020008661W WO2021002701A1 WO 2021002701 A1 WO2021002701 A1 WO 2021002701A1 KR 2020008661 W KR2020008661 W KR 2020008661W WO 2021002701 A1 WO2021002701 A1 WO 2021002701A1
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- charging
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- aging
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/04—Processes of manufacture in general
- H01M4/0438—Processes of manufacture in general by electrochemical processing
- H01M4/044—Activating, forming or electrochemical attack of the supporting material
- H01M4/0445—Forming after manufacture of the electrode, e.g. first charge, cycling
- H01M4/0447—Forming after manufacture of the electrode, e.g. first charge, cycling of complete cells or cells stacks
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N13/00—Investigating surface or boundary effects, e.g. wetting power; Investigating diffusion effects; Analysing materials by determining surface, boundary, or diffusion effects
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/44—Methods for charging or discharging
- H01M10/446—Initial charging measures
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Definitions
- the present invention relates to a method of determining the degree of wetting of a lithium ion battery cell, and more particularly, to a method of determining the degree of wetting without disassembling the assembled battery cell.
- This application is an application for claiming priority for Korean Patent Application No. 10-2019-0079604 filed on July 2, 2019, and all contents disclosed in the specification and drawings of the application are incorporated herein by reference.
- Lithium-ion batteries capable of repetitive charging and discharging are gaining popularity as an alternative to fossil energy.
- Lithium-ion batteries have been used primarily in traditional handheld devices such as cell phones, video cameras and power tools.
- electric vehicles EV, HEV, PHEV
- ESS large-capacity power storage devices
- UPS uninterruptible power supply systems
- Lithium-ion batteries are manufactured including one or more battery cells having a positive electrode, a negative electrode, a separator, and an electrolyte as basic elements.
- charging and discharging are performed while repeating a process in which lithium ions are intercalated and deintercalated from lithium metal oxide of the positive electrode into graphite of the negative electrode.
- the assembly of the battery cell is performed by alternately overlapping the porous positive electrode and the negative electrode, and a separator, and inserting the battery into a case and injecting an electrolyte.
- the electrolyte permeates between the anode, the cathode, and the separator by a capillary force and soaks into each of the interiors and interfaces, which is referred to as wetting or impregnation.
- the electrolyte solution of the electrode active material is not sufficiently wetted.
- the electrolyte is hydrophilic, the affinity for the hydrophobic electrode active material components is not high, and when the volume of the electrode active material layer is increased, the movement path of the electrolyte is lengthened accordingly, so penetration of the electrolyte is not easy. It is difficult to achieve a sufficient degree of wetting. If the electrolyte does not sufficiently penetrate into the electrode, for example, the movement of ions is slowed so that the electrode reaction cannot be performed smoothly, and as a result, the efficiency of the battery cell decreases.
- the battery cells are assembled in a discharged state, they can function only after the battery cells are assembled and then activated by primary charging.
- the primary charging is called a formation process or an activation process.
- Typical conventional inspection methods include a PC solvent impregnation method, an impregnation area observation method, a negative electrode charge state analysis method, an air scanner analysis method, and an electrochemical impedance spectroscopy (EIS) analysis method.
- the PC solvent impregnation method is to observe the degree of absorption using linear carbonate in the electrolyte solvent
- the impregnation area observation method is to observe or measure the impregnated area by immersing in the electrolyte solution in units of bi- or mono-battery cells.
- the negative charge state analysis method is to observe by peeling the active material layer from the current collector after being fully charged or charged over a certain SOC.
- the air scanner analysis method is an image analysis method according to the degree of ultrasonic transmission
- the EIS analysis method is based on the principle of measuring diffusion and interface resistance.
- the problem to be solved by the present invention is to provide a time-saving and quantitative method for determining the degree of wetting without decomposition of the battery cell.
- the present invention proposes a method for determining the degree of wetting using a low current test.
- the method for determining the degree of wetting according to the present invention includes a) charging the electrode assembly and the electrolyte solution in a case, and then charging the pre-aged reference battery cell at a low current of 0.01 C-rate or less while charging the recorded charging profile as a reference.
- charging may be performed with a constant current until a cut-off voltage is reached.
- the charging profile is a graph of a change in voltage of a battery cell over a charging time.
- the comparative analysis of c) may be determined based on a time to reach the cut-off voltage or a difference in slope of the charging profile.
- the cut-off voltage is 2.0V or less.
- the step of recording the measured charging profile while charging with a low current of 0.01 C-rate or less may form part of a formation process, which is an initial charging step for the battery cell.
- the other battery cells are assembled in the same manner as the reference battery cells and pre-aging is performed in the same manner, and b) and c) are performed on all battery cells in the mass production line for total inspection.
- the reference battery cells and other battery cells are assembled on the same line, and the reference battery cells and other battery cells are charged together in the same charging/discharging device to record the charging profile.
- the other battery cell is assembled in the same manner as the reference battery cell and pre-aging is performed under different conditions, thereby obtaining a specification of determining the degree of wetting according to the pre-aging condition.
- the pre-aging may be 2 hours or more and 48 hours or less.
- the degree of wetting of a battery cell constituting a lithium ion battery can be quantitatively evaluated and specified.
- the measurement conditions are not difficult and can be performed within a manufacturing process including an existing formation process. Therefore, it is time-saving.
- the determination method according to the present invention it is possible to quickly and easily check the degree of wetting of the battery cell, and by reflecting the confirmed degree of wetting to the lithium ion battery production process, the injection amount of the electrolyte can be optimized, and defects can be reduced.
- battery cells with poor wetting can be filtered out in advance, they can be made into good battery cells after sufficient wetting. Accordingly, it is possible to prevent the assembled battery cells from being discarded unfairly and improve productivity.
- FIG. 1 is a flow chart of a method for determining a degree of wetting according to an embodiment of the present invention.
- 2 is a graph comparing charging profiles of different battery cells.
- FIG 3 is a graph of a change in voltage of a battery cell over a charging time according to pre-aging conditions in another embodiment of the present invention.
- 4 is a photograph of an electrode wetting region after 2, 4, 12, and 24 hours for each pre-aging condition.
- FIG. 5 shows dQ/dV values, which are the reciprocal of the slope (dV/dQ) of the graph of FIG. 3, with respect to the battery cell voltage.
- the lithium ion battery is a generic term for a battery in which lithium ions act as operating ions during charging and discharging to cause an electrochemical reaction at the positive and negative electrodes.
- a lithium-ion battery includes an assembly of a single battery cell, including a single battery cell including a positive electrode/separator/cathode electrode assembly and an electrolyte in one case, a module in which a plurality of assemblies are connected in series and/or in parallel, and a plurality of modules. It should be construed to include packs connected in series and/or in parallel, battery systems in which multiple packs are connected in series and/or in parallel, and the like.
- the electrode assembly and the electrolyte are housed in a case and sealed to complete the battery cell assembly (step S10).
- an electrode assembly including an anode, a cathode, and a separator interposed therebetween is manufactured.
- the manufacturing of the electrode assembly includes applying an electrode slurry including an active material and a binder to an electrode current collector to prepare a positive electrode and a negative electrode, respectively, and then interposing a separator between the positive electrode and the negative electrode.
- the step of manufacturing such an electrode assembly is not particularly limited and may be performed according to a known method.
- the electrode assembly is not particularly limited as long as it includes a positive electrode, a negative electrode, and a separator, and may include, for example, a jelly-roll type, a stack type, or a stack/folding type structure.
- the negative electrode in the electrode assembly may include a carbon-based negative active material.
- the carbon-based negative active material may be artificial graphite or natural graphite.
- the electrolyte may include an organic solvent and a lithium salt.
- the organic solvent may minimize decomposition due to oxidation reactions during the charging and discharging process of the battery, and there is no limitation as long as it can exhibit the desired properties, and may be, for example, a cyclic carbonate, a linear carbonate, an ester, an ether, or a ketone. . These may be used alone, or two or more may be used in combination.
- a carbonate-based organic solvent may be preferably used, and examples of the cyclic carbonate include ethylene carbonate (EC), propylene carbonate (PC) and butylene carbonate (BC), and the linear carbonate includes dimethyl carbonate.
- DMC diethyl carbonate
- DPC dipropyl carbonate
- EMC ethylmethyl carbonate
- MPC methylpropyl carbonate
- EPC ethylpropyl carbonate
- the lithium salt is LiPF 6 , LiAsF 6 , LiCF 3 SO 3 , LiN(CF 3 SO 2 ) 2 , LiBF 4 , LiBF 6 , LiSbF 6 , LiN(C 2 F5SO 2 ) 2 , LiAlO 4 , LiAlCl 4 , LiSO 3 Lithium salts commonly used in electrolytes of lithium secondary batteries such as CF 3 and LiClO 4 may be used without limitation, and these may be used alone, or two or more may be used in combination.
- the case may preferably be a pouch made of an aluminum laminate sheet.
- step S20 pre-aging is performed on the previously assembled battery cells.
- Pre-aging means taking a certain amount of time for aging so that the electrolyte is wetted.
- the pre-aging may be 2 hours or more and 48 hours or less.
- the injected electrolyte flows into the battery cell over time, and the required electrolyte is charged inside the battery cell, and is impregnated into an electrode, for example, an active material layer.
- Pre-aging can be carried out at room temperature and pressure.
- the battery cells which have been assembled after the electrolyte solution and then subjected to pre-aging, are charged with a low current, and the charging profile is recorded (step S30).
- step S40 By quantitatively evaluating all of the mass-produced battery cells based on the difference level of the charging profile result, battery cells that deviate from the mass-produced level can be selected as battery cells with poor wetting.
- a battery cell serving as a reference for comparative analysis is referred to as a reference battery cell
- a charging profile of the reference battery cell is referred to as a reference charging profile.
- the charging profile of another battery cell compared to this is called a measured charging profile.
- a reference charging profile may be obtained in advance, and steps S10, 20, and 30 may be performed only for the battery cells to be mass-produced, and then step S40 may be performed.
- the reference battery cells and other battery cells are assembled on the same line, and the reference battery cells and other battery cells are charged in the same charging/discharging device at the same time. After recording the charging profiles, they may be compared and analyzed with each other. That is, if the above-described example is viewed as a case of performing S40 after performing a sub-process consisting of steps S10, 20, and 30 several times, the example described here sequentially performs steps S10, 20, 30, and 40 for a plurality of battery cells. It is to proceed. It will be appreciated by those skilled in the art that various other sequence changes and combinations are possible.
- the low current level in step S30 is characterized by a fine current of 0.01 C-rate or less.
- C is the battery cell capacity of the charging unit (often expressed as Q) A ⁇ h
- the current in amperes is selected as a fraction (or multiplier) of C.
- 1 C-rate refers to the charge/discharge speed at which the capacity of a fully charged battery cell is pulled out or filled within one hour, and also refers to the current density at that time.
- step S30 a constant current (CC) is charged with this low current until a cut-off voltage is reached. It only needs to be less than 0.01 C-rate, but if the charging current is too small, it takes a long time to reach the cut-off voltage, leading to an increase in the manufacturing time of the entire mass production line, so an appropriate charging current between 0 and 0.01 C-rate. Make a decision.
- CC constant current
- the cut-off voltage of step S30 is also characterized by a level of 2.0V or less. If the cut-off voltage is too low, it may become difficult to distinguish between charging profiles. If the cut-off voltage is too high, it takes a long time to reach the cut-off voltage, which increases the manufacturing time of the entire mass production line. Therefore, the cut-off voltage should be properly set between 0 and 2.0V.
- the primary charging of the battery cells impregnated through pre-aging is charged only to a low voltage of 2.0V or less as proposed in the present invention with a very small current of 0.01 C-rate or less as suggested in the present invention.
- a cell having a different charging profile result from the reference cell is different from each other. It can be determined by the arrival time to the cut-off voltage (t 1 , t 2 ) or the difference in slope of the charging profile.
- the slope may be an average voltage slope up to the cut-off voltage arrival time (t 1 , t 2 ), or may be a slope corresponding to a tangent line at a specific time.
- the results can be collected to quantitatively evaluate the degree of wetting and can be specified. Whether or not the electrolyte is sufficiently impregnated, it is possible to determine to what extent it is impregnated, and the reason for the occurrence of such an unimpregnated portion and the difference in degree can be estimated. Based on these observations and the reasons, it is possible to incorporate improvements into the production process.
- the arrival time to the cut-off voltage is slower than the average arrival time obtained for several battery cells or the arrival time of the reference battery cell, e.g. 5% or more or 10% or more, if it is slower, wetting failure It can be determined that it is a battery cell.
- the slope of the charging profile is less than a predetermined value, such as 5% or more or 10% or more, compared to the average slope obtained for several battery cells or the slope of the reference battery cell, it may be determined that the battery cell is a bad wetting.
- the preset value which is the criterion for determination, may be appropriately changed.
- the present invention is characterized in that the degree of wetting is determined using low current charging, but also the step of recording the measured charging profile while charging with a low current of 0.01 C-rate or less (step S30) is performed for the battery cell. It is also characterized in that it allows it to form part of the formation process, which is the initial charging stage. Conventional analysis methods were performed before or after the formation process. In contrast, the method of the present invention may constitute a part of the formation process.
- the formation process includes charging a constant current (CC) with a low current of 0.01 C-rate or less until the cut-off voltage is reached (that is, charging with a low current to determine the degree of wetting in the present invention) and As a full-fledged formation, a current of about 0.1 C-rate may be constantly maintained for about 3 hours for a long time to generate a solid electrolyte interface (SEI) film. Since conventional formation proceeds at about 0.1 C-rate, in the present specification, 0.01 C-rate is referred to as a low current in the sense of a low current.
- CC constant current
- SEI solid electrolyte interface
- a constant current (CC) is charged with a low current of 0.01 C-rate or less until the cut-off voltage is reached, and a C-rate constant current (CC) higher than the low current is applied to the SEI film. It may include generating nuclei and then growing the nuclei by maintaining a relatively low C-rate constant current (CC) thereafter.
- the C-rate at the end of charging can be smaller than the C-rate at the beginning of charging.
- the initial charging step includes a step of charging at 1 C-rate to 2 C-rate, and at the end of charging at 0.1 C-rate to 0.3 C-rate.
- the charging time at a high C-rate at the initial stage of charging may be very short, such as about 1 minute, preferably about 30 seconds.
- the charging time at a low C-rate can be about 2 hours or longer, and can be relatively long compared to the high C-rate application section.
- the time to maintain the low C-rate current can be adjusted according to the target SOC% at this stage. It may be partially charged to more than 10% and less than 50% of the battery capacity, or fully charged to 100% of the battery capacity.
- a constant current (CC) but at the end of the formation process, a constant voltage (CV) charge may be performed to terminate the charging.
- the CV charging voltage may be 3.9V to 4.5V, but is not limited thereto.
- the CC section as charging proceeds, the voltage of the battery cell increases. When the voltage of the battery cell reaches a preset voltage value (for example, 4.2V), it shifts to the CV section to continue charging. In the CV period, charging is performed while maintaining the preset voltage value (4.2V).
- the current is reduced while maintaining the voltage value (4.2V), and when the current value reaches a preset value (for example, for a battery with a capacity of 2000mAh, 2000 times 1/20 multiplied by 100mA), it is fully charged. You can judge and stop charging.
- a large overcurrent (e.g., 1 C-rate) is instantaneously applied at the beginning of the SEI film generation process to generate a large number of nuclei momentarily, and then a lower current (e.g. 0.1 C-rate) is applied as an example in which a uniform SEI film is grown, but is not intended to limit the present invention.
- the step of charging a constant current with a low current of 0.01 C-rate or less to perform the discrimination method according to the present invention, which is performed relatively early is also considered as a preparatory step before applying a high C-rate current.
- I can. It can be prepared for electrode or system stabilization before the SEI film is created. That is, while configuring a part of the formation process, the method of determining the degree of wetting can be performed without having to have a separate measurement step.
- the determination method of the present invention can be performed within a manufacturing process including an existing formation process without requiring difficult measurement conditions.
- step S40 the remaining formation process is performed only on the battery cells determined to have good wetting. Accordingly, when the primary charging is completed, normal manufacturing steps in the order of aging, discharging, and degassing are performed, and performance tests are performed, so that only good products can be shipped.
- lithium-ion batteries and other batteries in the past require aging, a aging process that gives a time margin for the electrolyte to enter the empty space of the electrode to form a stable electrolyte channel.
- the aging period can be set longer in consideration of the diffusion coefficient of metal foreign substances that may exist.
- high-temperature aging is performed at a temperature of about 65°C, the aging period may be shortened through film stabilization and uniformity.
- the discharge current and time of the discharge condition can be determined according to the SOC state of the lithium ion battery. It may be partially discharged or fully discharged at more than 10% and less than 50% of the battery capacity. Through this discharging step, it is possible to select the capacity of the battery, and to prevent the current density non-uniformity due to the non-uniform distribution of the battery active material. Preferably, after the aging is over, the voltage (OCV), resistance (IR), etc. of the battery are checked for defects, and 40 to 50% of the total capacity of the fully charged battery is discharged to be shipped in a semi-charged state. In the case of discharge, it can be by constant current discharge.
- degassing is performed to remove such gas. It is performed by creating a reduced pressure state in a cut state such as reopening a case such as a sealed pouch or cutting a part of the case, and when the gas discharge is completed, the cut case is sealed again.
- the battery cell determined to be wetting defect in the determination step (step S40) is only a case in which wetting is delayed, it is not a defect in the battery cell structure, but only the expression performance is delayed in time.Therefore, further wetting should be performed to perform the remaining formation process. I can. If such a battery cell cannot be filtered out and the formation is completed and performance is checked with other battery cells, it is highly likely to be identified as defective in the performance test, and the defect will be discarded soon, so the effort and cost of assembling the battery cells will be lost. There is a problem that it becomes. In the present invention, it is possible to prevent the assembled battery cells from being discarded unfairly because the battery cells with poor wetting can be made into good quality battery cells after sufficient wetting without filtering out and discarding them in advance.
- the discrimination method of the present invention may be more immediately understood with reference to experimental examples described below, and is provided for illustration and is not intended to be limiting.
- the discrimination method of the present invention was applied to a cylindrical battery cell of 2,500mAh @ 0.2C-rate. After injecting the electrolyte, after wetting for each pre-aging period, 0.005 C-rate constant current (CC) was charged and cut-off at 1.5V. (Calculating 0.005 C-rate for 2500mAh, charging current is 12.5mA)
- the pre-aging period ranged from 2 to 48 hours per battery cell.
- FIG. 3 is a graph of a change in voltage of a battery cell over a charging time, and Table 1 summarizes the time at which the cut-off voltage of 1.5V is reached for each pre-aging period, that is, for each wetting time.
- the left Y axis represents voltage and the right Y axis represents current.
- the upper graph is a current graph, and the lower graph is a voltage graph.
- the longer the pre-aging that is, the longer the time for wetting
- the time to reach the cut-off voltage of 1.5 V when charging with a current of 0.005 C-rate gradually decreases.
- pre-aging for 2 hours it took 8.1 minutes to reach 1.5 V
- pre-aging for 48 hours it took 5.7 minutes. This is a result that fits well with the prediction that the longer the time for wetting is, the better wetting will be and the shorter the time to reach the cut-off voltage will be as wetting is better.
- FIG. 4 is a photograph of an electrode wetting region after 2, 4, 12, and 24 hours for each pre-aging condition.
- the longer the pre-aging ie, the longer the time for wetting
- the less the area of the non-impregnated membrane by the electrolyte gradually decreases.
- the wetting area is the same and cannot be distinguished.
- FIG. 3 in the low-current charging profile, a difference in the time to reach the cut-off voltage occurs after 24, 36, and 48 hours, and in the present invention, the difference in wetting that is indistinguishable with the naked eye can be found from the comparison of the charging profile Suggests that you can. Based on these results, pre-aging for each battery cell model until after 24 hours will be applied after technically determining whether wetting is necessary.
- the X-axis of the graph is the time axis of application of the constant current, so it means the charging capacity Q, and the Y-axis of the graph is the corresponding voltage (V) value.
- V voltage
- FIG. 5 shows dQ/dV values, which are the reciprocal of the slope (dV/dQ) of the graph of FIG. 3, with respect to the battery cell voltage. As seen from the eye, the difference is clearer in FIG. 5 than in FIG. 3, so it is easy to grasp.
- the battery cell has a capacitor structure because it is wetted in the electrolyte, and the initial very small C-rate current And up to the very low voltage range, charges accumulate on the positive/cathode surfaces rather than material transfer between the positive and negative electrodes due to lithium ion oxidation and reduction reactions, and the capacitance component is the main region.
- the charges on the positive and negative electrodes It can be interpreted that the accumulating speed is faster the better wetting is, so that the voltage rise occurs rapidly.
- the actual mass production method is as follows. In actual mass production, the determination of the degree of wetting per wetting time is not applied. This is because the wetting time is the same according to the product specifications. Accordingly, when some of the battery cells have poor wetting, the defective battery cells may be selected according to the aforementioned exemplary embodiment. For example, if the battery cell lamination after stacking the separator on the electrode is excessive due to corona, or if the vacuum wetting process is used to facilitate wetting after infusion, there may be a problem in the process, so it is possible to select battery cells that are not well wetted. It can be. If the battery cell is not a defect due to the structure of the battery cell, but a battery cell in which the expression performance is delayed in time, there is no problem of lowering productivity because it is not necessary to discard it.
- the method according to the present invention can also be used to determine the injection amount of the electrolyte. For example, by assembling several battery cells by varying the amount of electrolyte injected, pre-aging under the same conditions, and then applying the evaluation method according to the present invention, the specification of determining the degree of wetting according to the amount of electrolyte injected can be obtained.
- the electrolyte acts as a medium to facilitate the movement of electrons. Therefore, when designing a lithium ion battery, it is necessary to calculate and inject the total amount of the electrolyte so that the electrolytic rack can be properly wetted, and a considerable amount of time is required to ensure sufficient wetting, resulting in a decrease in productivity. In this situation, if the degree of wetting of the electrolyte solution can be checked in advance, the required amount of the electrolyte solution can be known, and thus productivity may be increased.
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Abstract
Description
Claims (10)
- a) 전극 조립체와 전해액을 케이스에 수납하여 조립한 후 프리에이징을 실시한 기준 배터리 셀에 대해 0.01 C-rate 이하의 저전류로 충전하면서 기록한 충전 프로파일을 기준 충전 프로파일로서 획득하는 단계;b) 전극 조립체와 전해액을 케이스에 수납하여 조립한 후 프리에이징을 실시한 다른 배터리 셀에 대해 상기 기준 배터리 셀과 동일하게 0.01 C-rate 이하의 저전류로 충전하면서 측정 충전 프로파일을 기록하는 단계; 및c) 상기 기준 충전 프로파일과 상기 측정 충전 프로파일을 비교 분석하여 상기 기준 배터리 셀 대비 상기 다른 배터리 셀의 웨팅 정도를 판별하는 단계를 포함하는 것을 특징으로 하는 웨팅 정도 판별 방법.
- 제1항에 있어서, 상기 a)와 b)의 충전 프로파일을 기록하는 단계에서 충전은 컷-오프(cut-off) 전압에 이를 때까지 정전류(constant current)로 충전하는 것을 특징으로 하는 웨팅 정도 판별 방법.
- 제1항에 있어서, 상기 충전 프로파일은 충전 시간 경과에 따른 배터리 셀 전압 변화 그래프인 것을 특징으로 하는 웨팅 정도 판별 방법.
- 제3항에 있어서, 상기 c)의 비교 분석은 컷-오프 전압까지의 도달 시간 또는 상기 충전 프로파일의 기울기 차이로 판별하는 것을 특징으로 하는 웨팅 정도 판별 방법.
- 제2항에 있어서, 상기 컷-오프 전압은 2.0V 이하인 것을 특징으로 하는 웨팅 정도 판별 방법.
- 제1항에 있어서, 상기 0.01 C-rate 이하의 저전류로 충전하면서 측정 충전 프로파일을 기록하는 단계는 상기 배터리 셀에 대한 최초 충전 단계인 포메이션 공정의 일부를 이루는 것을 특징으로 하는 웨팅 정도 판별 방법.
- 제1항에 있어서, 상기 다른 배터리 셀은 상기 기준 배터리 셀과 동일하게 조립하고 동일하게 프리에이징을 실시하며, 상기 b)와 c)는 전수 검사를 위해 양산 라인의 모든 배터리 셀에 대해 실시하는 것을 특징으로 하는 웨팅 정도 판별 방법.
- 제1항에 있어서, 상기 기준 배터리 셀과 다른 배터리 셀을 동일한 라인에서 조립하고, 상기 기준 배터리 셀과 다른 배터리 셀을 동일한 충방전 장치에서 한꺼번에 충전하여 상기 충전 프로파일을 기록하는 것을 특징으로 하는 웨팅 정도 판별 방법.
- 제1항에 있어서, 상기 다른 배터리 셀은 상기 기준 배터리 셀과 동일하게 조립하고 다른 조건에서 프리에이징을 실시함으로써 프리에이징 조건에 따른 웨팅 정도 판별의 스펙을 얻는 것을 특징으로 하는 웨팅 정도 판별 방법.
- 제9항에 있어서, 상기 프리에이징은 2 시간 이상 48 시간 이하인 것을 특징으로 하는 웨팅 정도 판별 방법.
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US17/623,510 US20220359856A1 (en) | 2019-07-02 | 2020-07-02 | Method for determining degree of wetting by using low current test |
ES20835187T ES2965818T3 (es) | 2019-07-02 | 2020-07-02 | Método para determinar el grado de humectación mediante una prueba de baja corriente |
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PL20835187.4T PL3993134T3 (pl) | 2019-07-02 | 2020-07-02 | Sposób określania stopnia zwilżania za pomocą testu niskoprądowego |
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CN114072952B (zh) | 2023-12-19 |
HUE064166T2 (hu) | 2024-02-28 |
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US20220359856A1 (en) | 2022-11-10 |
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