A lithium battery cell charging and discharging tray, an aging device and an aging method

Abstract

The present invention relates to the technical field of lithium-ion batteries, and in particular to a charging and discharging tray for battery cells, an aging device and a method for aging battery cells. Among them, the tray includes an insulating base component for accommodating each battery cell and a conductive component for realizing the parallel connection of one type-A battery cell and each type-B battery cell in sequence. It is applicable to aging one type-A battery cell and several type-B battery cells simultaneously, and the potential of the type-A battery cell is higher than that of each type-B battery cell. The tray of the present invention adopts a design in which the base component and the conductive component are separated, so that after the low-potential battery cells are aged, the high-potential battery cells are also aged, and the lifespan of the high-potential battery cells is not affected. Therefore, it can also be shipped after selecting defective products by self-discharge, which is beneficial to the improvement of manufacturing efficiency. Compared with the method of fixing the high-potential battery cells to charge the low-potential battery cells, it avoids the high-potential battery cells from being damaged due to cyclic aging, which is beneficial to the reduction of manufacturing costs. Moreover, the tray of the present invention is very simple, which is beneficial to the reduction of the cost of the battery cell aging device.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and particularly to a charging and discharging tray for battery cells, an aging device and an aging method. Background Art

[0002] Self-discharge sorting is the ultimate goal of the battery cell aging process. Battery cell self-discharge can be divided into physical self-discharge and chemical self-discharge according to different reaction types. Considering the impact of self-discharge on battery cells, self-discharge can also be divided into two types: self-discharge whose lost capacity can be reversibly compensated and self-discharge with permanent capacity loss.

[0003] Generally speaking, the energy loss caused by physical self-discharge is recoverable, while the energy loss caused by chemical self-discharge is basically irreversible. The self-discharge of battery cells comes from two aspects: (1) self-discharge caused by the chemical system itself; this part is mainly caused by side reactions inside the battery cells, specifically including changes in the surface film layers of the positive and negative electrode materials; potential changes caused by the thermodynamic instability of the electrodes; dissolution and precipitation of metal foreign impurities; (2) self-discharge of the battery cells caused by micro-short circuits inside the battery cells due to the separator between the positive and negative electrodes.

[0004] Existing aging methods have a long test time, low test accuracy, and low operation efficiency in selecting unqualified products. Summary of the Invention

[0005] Other features and advantages of the present invention will be described in the following specification, and will be partially obvious from the specification, or understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures specifically pointed out in the specification, claims, and other specification drawings.

[0006] The objective of the present invention is to provide a charging and discharging tray for battery cells, an aging device and an aging method in view of the above problems.

[0007] In a first aspect, the present invention provides a charging and discharging tray for battery cells, which is suitable for aging one type-A battery cell and several type-B battery cells simultaneously. The potential of the type-A battery cell is higher than that of each type-B battery cell. The tray includes an insulating base component for accommodating the type-A battery cell and the type-B battery cells, and a conductive component for sequentially connecting the type-A battery cell and each type-B battery cell in parallel; the base component and the conductive component are separated.

[0008] In some embodiments, the base component is a bottom plate, and side walls are formed by the bottom plate extending upward along the perimeter of the bottom surface. The purpose of setting the side walls is to prevent the battery cells from falling during handling.

[0009] In some embodiments, a gripping portion is formed by local indentation on two opposite side walls; or a gripping portion is formed by extending in opposite directions on the surfaces parallel to the bottom surface of the base plate at the tops of two opposite side walls. The purpose of setting the gripping portion is to facilitate the handling of the base component during the aging operation.

[0010] In some embodiments, the tray further includes a plurality of insulating separation components for separating each battery cell. The purpose of setting the separation components is to prevent the battery cells from colliding and causing a fire and a safety accident.

[0011] In some embodiments, the separation components are a plurality of mutually separated baffles. The separation of the separation components (not connected to the base component) can improve the versatility of the battery cell charging and discharging tray.

[0012] In some embodiments, the baffles are arranged in parallel on the base component. When the spacing distance between the baffles matches the size of the battery cell, it can avoid poor contact between each probe and the positive / negative electrode posts of the corresponding battery cell due to shaking during handling.

[0013] In some embodiments, the tray further includes a fastening component for surrounding each battery cell to integrally fasten each battery cell. The purpose of setting the fastening component is to avoid poor contact between each probe and the positive / negative electrode posts of the corresponding battery cell due to shaking during handling.

[0014] In some embodiments, the fastening component is a flexible belt-shaped hoop, and an openable and closable connection part is arranged at the opening of the hoop.

[0015] In some embodiments, the conductive component includes a first conductive component for sequentially connecting the positive electrode posts of the type A battery cell and each type B battery cell, and a second conductive component for sequentially connecting the negative electrode posts of the type A battery cell and each type B battery cell in the same order.

[0016] In some embodiments, the first conductive component includes a first metal strip and X probes spaced on its lower surface; the second conductive component includes a second metal strip and Y probes spaced on its lower surface; both X and Y are natural numbers greater than or equal to 2.

[0017] In some embodiments, the spacing distance between the probes arranged on the first metal strip is equal to the spacing distance between the probes arranged on the second metal strip.

[0018] In some embodiments, a plurality of grooves with internal threads are spaced on the lower surfaces of the first metal strip and the second metal strip respectively, and external threads for realizing threaded connection with the grooves are arranged at the upper ends of each probe.

[0019] In some embodiments, the number of grooves with internal threads spaced on the lower surface of the first metal strip is greater than X; the number of grooves with internal threads spaced on the lower surface of the second metal strip is greater than Y. The purpose of this improvement is to make the cell charging and discharging tray applicable to aging cells of different sizes.

[0020] In some embodiments, X and Y are equal.

[0021] In some embodiments, the first conductive component includes a first flexible main conducting wire and X flexible branch conducting wires. One end of each of the X flexible branch conducting wires is connected to the first flexible main conducting wire at intervals, and the other end of each of the X flexible branch conducting wires is connected to a conductive clip; the second conductive component includes a second flexible main conducting wire and Y flexible branch conducting wires. One end of each of the Y flexible branch conducting wires is connected to the second flexible main conducting wire at intervals, and the other end of each of the Y flexible branch conducting wires is connected to a conductive clip; both X and Y are natural numbers greater than or equal to 2.

[0022] In a second aspect, the present invention provides a cell aging device, including a tray, and the tray is the cell charging and discharging tray in the above embodiments.

[0023] In a third aspect, the present invention further provides a cell aging method, which uses the cell aging device in the above embodiments for aging, and includes the following steps:

[0024] Step 1, connect the positive electrode columns of at least one type A cell (5) in the first state and at least one type B cell (6) in the second state in sequence through the first conductive component (21), and connect the negative electrode columns in sequence through the second conductive component (22). The potential of the type A cell (5) is higher than the potential of each type B cell (6);

[0025] Step 2, leave the connected cells standing for a first duration t1 at a first set temperature T1;

[0026] Step 3, cool the cells at a second set temperature T2, where T1 > T2;

[0027] Step 4, test the open-circuit voltage OCV1 of each cell;

[0028] Step 5, leave the cells standing for a second duration t2 at the second set temperature;

[0029] Step 6, test the open-circuit voltage OCV2 of each cell;

[0030] Step 7, judge whether each cell is qualified according to the open-circuit voltage OCV1 and the open-circuit voltage OCV2 according to the set rules.

[0031] In the technical solution of the embodiment of the present invention, the type-A battery cells are used to charge each type-B battery cell. Therefore, the potential of the type-A battery cells needs to be higher than that of each type-B battery cell. Battery cells with a maximum working voltage ≥ 4.05V are called high-potential system battery cells, which can be used as the type-A battery cells of the present invention. Generally, they are battery cells of the NCM system, and can also be battery cells of systems such as lithium cobaltate, ternary, and high nickel. The type-A battery cells need to be charged to SOC ≥ 70% before they can maintain their potential ≥ 3.85V.

[0032] In some embodiments, the first state is that the state of charge ≥ 70% and the potential is maintained ≥ 3.85V.

[0033] In some embodiments, the second state is full charge and lithium supplementation.

[0034] In some embodiments, the maximum working voltage of each type-A battery cell (5) is ≥ 4.05V.

[0035] In some embodiments, the type-A battery cell (5) is a battery cell of the NCM system, lithium cobaltate, ternary system or high nickel system.

[0036] In some embodiments, each type-B battery cell (6) is a battery cell of the LFP system.

[0037] In some embodiments, the first set temperature T1 is 25 - 80°C or 35 - 80°C.

[0038] In some embodiments, the second set temperature T2 is room temperature.

[0039] In some embodiments, the first duration t1 is 0 - 7 days or 0 - 5 days.

[0040] In some embodiments, the second duration t2 is 12 hours - 30 days.

[0041] In some embodiments, the setting rule is to calculate the voltage drop per unit time of each battery cell according to the formula K = (OCV2 - OCV1) / t2, and then convert the voltage drop per unit time into the K-value specification according to the monthly self-discharge requirement. Battery cells with a voltage drop greater than the K-value specification are determined to be unqualified, and battery cells with a voltage drop less than or equal to the K-value specification are determined to be qualified.

[0042] In some embodiments, before step one, the type-A battery cells (5) and each type-B battery cell (6) are sequentially placed on the base component (1), or the type-A battery cells (5) and various battery cells (6) are sequentially arranged and then integrally fastened by surrounding each battery cell with the fastening component (4).

[0043] In some embodiments, the base component (1) and the fastening component (4) have insulating properties.

[0044] In some embodiments, before step one, a step of placing a separating member (3) between each battery cell is added.

[0045] In some embodiments, before or after step three, the first conductive member (21) and the second conductive member (22) are removed.

[0046] By adopting the above technical solutions, the beneficial effects of the present invention are as follows:

[0047] (1) The separation design of the base member and the conductive member of the battery cell charging and discharging tray enables the high-potential battery cells to complete aging after the low-potential battery cells have aged, without affecting the lifespan of the high-potential battery cells. Thus, it is also possible to ship the products after selecting defective products due to self-discharge, which is beneficial to improving the manufacturing efficiency.

[0048] (2) Compared with the method of fixing the high-potential battery cells to charge the low-potential battery cells, it avoids the high-potential battery cells from being damaged due to cyclic aging, which is beneficial to reducing the manufacturing cost.

[0049] (3) The structure of the battery cell charging and discharging tray of the present invention is simple, which is beneficial to reducing the cost of the battery cell aging device.

[0050] (4) When the battery cells are aging, if the potential of the battery cells is low and the voltage is unstable, it will not be possible to effectively achieve the purpose of high-temperature and high-potential chemical self-discharge and accelerating metal precipitation. Therefore, the above method connects the high-potential battery cells in parallel with the low-potential battery cells, so that the high-potential battery cells continuously charge the low-potential battery cells, thereby raising the potential of the low-potential battery cells and stabilizing the voltage, enabling the effective achievement of the purpose of high-temperature and high-potential chemical self-discharge and accelerating metal precipitation.

[0051] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure.

[0052] Undoubtedly, such objects of the present invention and other objects will become more apparent after the detailed description of the preferred embodiments described in the following with multiple drawings and illustrations.

[0053] To make the above and other objects, features, and advantages of the present invention more obvious and understandable, one or several preferred embodiments are hereinafter specifically exemplified and described in detail in conjunction with the accompanying drawings as follows. Description of the Drawings

[0054] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention.

[0055] In the drawings, the same components are denoted by the same reference numerals, and the drawings are schematic and not necessarily drawn to actual scale.

[0056] To more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only one or several embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on such drawings.

[0057] Figure 1 It is a schematic structural diagram of a charging and discharging tray for an electric core of the present invention;

[0058] Figure 2 It is another schematic structural diagram of a charging and discharging tray for an electric core of the present invention;

[0059] Figure 3 It is a partial schematic structural diagram of a charging and discharging tray for an electric core of the present invention;

[0060] Figure 4 It is a flowchart of a method for aging an electric core of the present invention.

[0061] Main reference numeral description:

[0062] 1 Base component;

[0063] 11 Bottom plate; 12 Side wall; 13 Gripping part;

[0064] 2 Conductive component;

[0065] 21 First conductive component; 211 First metal strip;

[0066] 22 Second conductive component; 221 Second metal strip;

[0067] 23 Probe;

[0068] 3 Separation component;

[0069] 31 Baffle;

[0070] 4 Fastening component;

[0071] 41 Hoop; 411 Openable connection part;

[0072] 5 Class A electric core;

[0073] 6 Class B electric core. Detailed implementation manners

[0074] The following will describe in detail the embodiments of the technical solutions of the present invention with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and therefore are only examples and cannot be used to limit the protection scope of the present invention.

[0075] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs; the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention; the terms "comprising" and "having" and any variations thereof in the specification and claims of the present invention and the above drawings are intended to cover non-exclusive inclusion.

[0076] In the description of the embodiments of the present invention, the technical terms "first", "second", etc. are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present invention, the meaning of "a plurality of" is more than two, unless otherwise specifically defined.

[0077] Reference to "an embodiment" herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present invention. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0078] In the description of the embodiments of the present invention, the term "and / or" is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0079] In the description of the embodiments of the present invention, the term "a plurality of" refers to more than two (including two). Similarly, "a plurality of groups" refers to more than two groups (including two groups), and "a plurality of pieces" refers to more than two pieces (including two pieces).

[0080] In the description of the embodiments of the present invention, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present invention and simplifying the description, and does not indicate or imply that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present invention.

[0081] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific situations.

[0082] After the battery cells in a lithium-ion battery are assembled, filled with electrolyte, and undergo the first charge and discharge formation, they need to be aged. The main purposes of aging are as follows:

[0083] 1. Placing the battery cells at a high temperature or normal temperature for a period of time can ensure that the electrolyte can fully infiltrate the electrode sheets, which is beneficial to the stability of the battery cell performance;

[0084] 2. After the battery cells go through the pre-formation process, a certain amount of solid electrolyte interphase (SEI) will be formed on the graphite negative electrode inside the battery cells. However, this film structure is tight and has small pores. Aging the battery cells at a high temperature will help the SEI structure to reorganize and form a loose and porous film;

[0085] 3. After formation, the voltage of the battery cells is in an unstable stage. After the active substances in the positive and negative electrode materials are aged, it can promote the acceleration of some side effects, such as gas generation, electrolyte decomposition, precipitation of metal impurities, etc., so that the electrochemical performance of the lithium battery cells can quickly reach stability;

[0086] 4. Eliminate unqualified battery cells with serious self-discharge, which is convenient for screening battery cells with high consistency.

[0087] Among them, screening for internal micro-shorted battery cells by the aging process is a main purpose. During the storage process of the battery cells, the open-circuit voltage will decrease, but the amplitude will not be very large. If the open-circuit voltage drops too fast or the amplitude is too large, it belongs to an abnormal phenomenon.

[0088] Self-discharge sorting is the ultimate goal of the battery cell aging process. Battery cell self-discharge can be divided into physical self-discharge and chemical self-discharge according to different reaction types. Considering the impact of self-discharge on the battery cells, self-discharge can also be divided into two types: self-discharge whose lost capacity can be reversibly compensated and self-discharge with permanent capacity loss.

[0089] Generally speaking, the energy loss caused by physical self-discharge is recoverable, while the energy loss caused by chemical self-discharge is basically irreversible. The self-discharge of the battery cells comes from two aspects:

[0090] (1) Self-discharge caused by the chemical system itself; this part is mainly caused by side reactions inside the battery cell, specifically including changes in the surface film layers of the positive and negative electrode materials, potential changes caused by the thermodynamic instability of the electrodes, and the dissolution and precipitation of metal foreign impurities.

[0091] (2) Micro-short circuit inside the battery cell caused by the separator between the positive and negative electrodes, resulting in self-discharge of the battery cell.

[0092] When a lithium-ion battery cell ages, the change in the K value is exactly the process of the formation and stabilization of the SEI film on the surface of the electrode material. If the voltage drop is too large, it indicates that there is a micro-short circuit inside, and thus the battery cell can be determined as a non-conforming product. The K value is a physical quantity used to describe the self-discharge rate of the battery cell, and its calculation method is the open-circuit voltage difference between two tests divided by the time interval Δt between the two voltage tests. The formula is: K = (OCV2 - OCV1) / Δt.

[0093] Existing test methods charge the battery to different states of charge (State of Charge, abbreviated as SOC) of 15 - 35%, 50 - 55%, and 90 - 100% at different charging rates, then test the open-circuit battery cell, and let it stand at room temperature for 1 - 15 days as a test cycle. The open-circuit voltage is tested multiple times (1 - 10 times), and the voltage drop is calculated using ΔV = OCVn - OCVn-1 (OCVn is the open-circuit voltage of the nth test, and OCVn-1 is the open-circuit voltage of the (n - 1)th test). Finally, the battery cells are grouped according to self-discharge using ΔV.

[0094] Although existing test methods can be used for self-discharge test and sorting of lithium iron phosphate lithium-ion batteries, for low-potential battery cells, such as those of the LFP system, this method has the following defects:

[0095] 1. The potential of the battery cells of the LFP system is low, at 3.65V, which is not conducive to the precipitation of metal impurities. And since the entire test process is carried out at room temperature, a long test time is required, affecting the working efficiency of selecting non-conforming products by self-discharge.

[0096] 2. The low potential of the battery cells will also result in a small amount of de-chemical self-discharge. The tested self-discharge mainly includes chemical self-discharge, so the accuracy is low, affecting the working effect of selecting non-conforming products by self-discharge.

[0097] Therefore, for the self-discharge sorting of low-potential battery cells, the present invention starts from the aging process for optimization. During the aging stage, a high-potential battery cell continuously charges several low-potential battery cells, so as to enable the low-potential battery cells to achieve the purpose of accelerating de-chemical self-discharge and metal precipitation at high temperature and high potential.

[0098] The inventive concept of the battery cell charge and discharge tray provided by the present invention comes from the aging method of the battery cell.

[0099] Refer toFigures 1 - 3 , Figure 1 is a schematic structural view of a charging and discharging tray for an electric core according to the present invention; Figure 2 is another schematic structural view of a charging and discharging tray for an electric core according to the present invention; Figure 3 is a partial schematic structural view of a charging and discharging tray for an electric core according to the present invention.

[0100] In some embodiments of the present invention, the present invention provides a charging and discharging tray for an electric core, which is suitable for aging an A-type electric core 5 and a plurality of B-type electric cores 6 simultaneously. The potential of the A-type electric core 5 is higher than that of each B-type electric core 6. The tray includes: a base member 1 and a conductive member 2, and the base member 1 is separated from the conductive member 2. Among them, the base member is insulating and is used to accommodate the A-type electric core 5 and the B-type electric cores 6, and the conductive member 2 is used to realize the sequential parallel connection of the A-type electric core 5 and each B-type electric core 6.

[0101] Referring to Figure 1 , Figure 1 is a schematic structural view of a charging and discharging tray for an electric core according to the present invention.

[0102] In some embodiments of the present invention, the electric cores to be aged include an A-type electric core 5 and four B-type electric cores 6 arranged together in sequence. The outer shape of each electric core is a cuboid with the same size. One positive electrode post and one negative electrode post are provided on the upper surface of each electric core. The A-type electric core 5 is, for example, an NCM system electric core, which has been charged to a certain SOC, such as ≥ 70%, and the B-type electric core 6 is, for example, an LFP system electric core, which has been fully charged.

[0103] In some embodiments of the present invention, the charging and discharging tray for an electric core includes a base member 1 and a conductive member 2, and the base member 1 is separated from the conductive member 2.

[0104] The base member 1 is a bottom plate 11, on the upper surface of which the above-mentioned A-type electric core 5 and four B-type electric cores 6 are accommodated. In order to avoid short circuit caused by the base member 1 accidentally contacting the conductive member 2, the base member 1 is preferably made of insulating material. In order to match the size after the electric cores are arranged together, in some embodiments of the present invention, the shape of the bottom plate 11 is set to be square. In order to prevent the electric cores from falling during handling, in some embodiments of the present invention, the bottom plate 11 extends upward along the four sides of the bottom surface to form side walls 12.

[0105] The conductive member 2 includes a first conductive member 21 and a second conductive member 22. The first conductive member 21 is the first conductive member 21 that sequentially connects the positive electrode posts of the above-mentioned A-type electric core 5 and four B-type electric cores 6; the second conductive member 22 is the second conductive member 22 that sequentially connects the negative electrode posts of the above-mentioned A-type electric core 5 and four B-type electric cores 6 in the same order, thereby realizing the sequential parallel connection of the above-mentioned A-type electric core 5 and four B-type electric cores 6.

[0106] Among them, the first conductive component 21 includes a first metal strip 211 and a plurality of probes 23 arranged on the lower surface of the first metal strip 211; one end of each probe 23 is fixed on the positive electrode post of the corresponding battery cell, and the other end is fixed on the lower surface of the first metal strip 211. The second conductive component 22 includes a second metal strip 221 and a plurality of probes 23 arranged on the lower surface of the second metal strip 221; one end of each probe 23 is fixed on the negative electrode post of the corresponding battery cell, and the other end is fixed on the lower surface of the second metal strip 221. The number of probes 23 arranged under the two metal strips is the same, and the requirements for the material of each probe 23 are relatively low, and it can be used for charging and discharging.

[0107] In some embodiments of the present invention, the usage method of the battery cell charging and discharging tray (i.e., the method of aging the battery cell using the battery cell charging and discharging tray disclosed in some embodiments of the present invention) is as follows:

[0108] (1) Place the positive electrode posts and negative electrode posts of the type A battery cells 5 and each type B battery cell 6 upward into the base component 1, where each type B battery cell 6 is together, and the type A battery cell 5 is located on one side, specifically, it can be on the left or right side;

[0109] (2) Fix each probe 23 of the first metal strip 211 on the positive electrode posts of each battery cell, and one probe 23 is fixed on each positive electrode post;

[0110] (3) Fix each probe 23 of the second metal strip 221 on the negative electrode posts of each battery cell, and one probe 23 is fixed on each negative electrode post, so that the type A battery cell 5 and each type B battery cell 6 are connected in parallel in sequence;

[0111] (4) Move the base component 1 to a high-temperature aging chamber, stand still for 0 to 7 days, and perform aging at a temperature controlled at 25 to 80 °C. After the standing time is completed, place it in a normal-temperature standing chamber;

[0112] (5) After cooling, remove the first metal strip 211 and the second metal strip 221, and test the open-circuit voltage OCV1 of each battery cell;

[0113] (6) Stand still at normal temperature for 12 hours to 30 days, and then test the open-circuit voltage OCV2 of each battery cell;

[0114] (7) According to the calculation formula of the self-discharge of the battery cell K = (OCV2 - OCV1) / the time of standing at normal temperature, by comparing with the customer's requirements, select the battery cells whose self-discharge does not meet the requirements.

[0115] It should be noted that in the steps of testing the open-circuit voltage OCV1, testing the open-circuit voltage OCV2, and comparing with the customer's requirements to select the battery cells whose self-discharge does not meet the requirements, the type A battery cell 5 is used as the working object in all these links, which is one of the differences from the existing method of aging the fixed high-potential battery cells.

[0116] In some embodiments of the present invention, the base component 1 and the conductive component 2 are designed separately, so that after the Class A battery cells 5 with high potential are aged after the Class B battery cells 6 with low potential are aged, the aging of the Class A battery cells 5 is also completed, without affecting the lifespan of the Class A battery cells 5. The Class A battery cells 5 can also be shipped after picking out defective products by self-discharge, effectively saving the aging cost. Compared with the method of charging the low-potential battery cells with the fixed high-potential battery cells, it avoids the damage of the high-potential battery cells due to cyclic aging, thereby reducing the manufacturing cost. Moreover, the battery cell charging and discharging tray of the present invention is very simple, further reducing the aging cost.

[0117] Refer to Figure 2 , Figure 2 which is another structural schematic diagram of a battery cell charging and discharging tray of the present invention.

[0118] In some embodiments of the present invention, in order to facilitate the handling of the base component 1 during the aging operation, in some embodiments provided by the present invention, a gripping portion 13 is further provided on the base component 1. For example: the gripping portion 13 can be formed by local depression on two opposite side walls 12; or the gripping portion 13 can be formed by extending in opposite directions along a surface parallel to the bottom surface of the bottom plate 11 at the top of two opposite side walls 12. Both of these methods can be realized by an integrated molding processing method after designing the corresponding molds, and the implementation is very simple.

[0119] Refer to Figure 3 , Figure 3 which is a partial structural schematic diagram of a battery cell charging and discharging tray of the present invention.

[0120] During the aging process, in order to prevent the battery cells from colliding and causing a fire and resulting in a safety accident, in some embodiments provided by the present invention, an insulating separation component 3 is inserted between the battery cells. The insulating separation component 3 can be a separate baffle 31, and the number of baffles 31 is the same as the number of Class B battery cells 6. Each insulating separation component 3 can also be arranged in parallel on the base component 1, and the arrangement method on the base component 1 can be an integrated molding method. Its advantages are: on the one hand, the insulation separation of each battery cell is realized, and on the other hand, when the spacing distance between the baffles 31 matches the size of the battery cells, it can also avoid the poor contact between each probe 23 and the positive / negative electrode posts of the corresponding battery cells due to shaking during handling. However, after integrated molding, the battery cell charging and discharging tray has poor versatility due to requirements for the size of the battery cells.

[0121] Refer to Figure 3 , Figure 3 which is a partial structural schematic diagram of a battery cell charging and discharging tray of the present invention.

[0122] In order to solve the problem of poor contact between each probe 23 and the positive / negative electrode posts of the corresponding battery cells due to shaking during the handling process mentioned above, in some embodiments provided by the present invention, a fastening member 4 is further added. After surrounding each battery cell, the fastening member 4 can achieve the integral fastening of each battery cell. The fastening member 4 can be a flexible strip-shaped hoop 41, and an openable and closable connecting portion 411 is provided at the opening of the hoop 41. The using method of the hoop 41 is as follows: after the positive and negative electrode posts of the type-A battery cells 5 and each type-B battery cell 6 are placed upward into the base member 1, the hoop 41 in the open state is surrounded around each battery cell, and then the openable and closable connecting portion 411 of the hoop 41 is fastened. After the battery cells are cooled at room temperature, the openable and closable connecting portion 411 of the hoop 41 is opened, and then the hoop 41 can be removed.

[0123] In some embodiments of the present invention, each probe 23 can be arranged on the lower surface of the metal strip in an integrally formed manner; alternatively, a plurality of grooves with internal threads can be provided on the lower surface of each metal strip, and external threads can be provided at the upper ends of each probe 23, so that each probe 23 is threadedly connected to the corresponding metal strip. The first way of arranging the probe 23 can reduce the processing cost, but it will cause the battery cell charge and discharge tray to have poor versatility due to the requirements for the size of the battery cell; the second way of arranging the probe 23 is more complex in processing, and the spacing of each probe 23 may need to be adjusted during each aging, affecting the operation efficiency. However, when the number of grooves on the lower surface of each metal strip is greater than the number of probes 23 on the metal strip, the battery cell charge and discharge tray can be made applicable to aging battery cells of different sizes.

[0124] In order to achieve the versatility of the battery cell charge and discharge tray, the conductive member 2 can also use flexible conductive wires to replace the metal strips disclosed in this embodiment. Specifically, the first conductive member 21 includes a first flexible main conductive wire and X flexible branch conductive wires. One end of each of the X flexible branch conductive wires is connected to the first flexible main conductive wire at intervals, and the other end of each of the X flexible branch conductive wires is connected to a conductive clip; the second conductive member 22 includes a second flexible main conductive wire and Y flexible branch conductive wires. One end of each of the Y flexible branch conductive wires is connected to the second flexible main conductive wire at intervals, and the other end of each of the Y flexible branch conductive wires is connected to a conductive clip; both X and Y are natural numbers greater than or equal to 2. The disadvantage of this solution is that the installation and disassembly of each conductive clip and the positive / negative electrode posts need to be completed one by one, affecting the operation efficiency. When the above-mentioned metal strip solution is adopted, the conductive member 2 is a rigid member, and the installation and disassembly of each conductive clip and the positive / negative electrode posts only need to be operated once to complete, which can greatly improve the operation efficiency.

[0125] In some embodiments of the present invention, the beneficial effects achieved by the battery cell charge and discharge tray are as follows:

[0126] (1) The base component and the conductive component of the battery cell charging and discharging tray are designed to be separated. After the low-potential battery cells are aged, the high-potential battery cells are also aged, and the lifespan of the high-potential battery cells is not affected. Therefore, defective products can be shipped after self-discharge screening, which is beneficial to improving manufacturing efficiency.

[0127] (2) Compared with the method of fixing the high-potential battery cells to charge the low-potential battery cells, it avoids the high-potential battery cells from being damaged due to cyclic aging, which is beneficial to reducing manufacturing costs.

[0128] (3) The structure of the battery cell charging and discharging tray of the present invention is simple, which is beneficial to reducing the cost of the battery cell aging device.

[0129] In some embodiments of the present invention, the beneficial effects achieved by the battery cell aging device using the battery cell charging and discharging tray in any of the above embodiments are as follows:

[0130] (1) The high-potential battery cells and the low-potential battery cells are connected in parallel, so that the high-potential battery cells continuously charge the low-potential battery cells, thus solving the problem that when the battery cells are aged, if the potential of the battery cells is low and the voltage is unstable, the purpose of effectively performing high-temperature and high-potential chemical self-discharge and accelerating metal precipitation cannot be achieved.

[0131] (2) During aging, the potential of the low-potential battery cells is raised and the voltage is stable, so that the purpose of effectively performing high-temperature and high-potential chemical self-discharge and accelerating metal precipitation can be achieved.

[0132] (3) After the low-potential battery cells are aged, the high-potential battery cells are also aged. Defective products can be shipped after self-discharge screening without affecting the lifespan of the battery cells, effectively saving the cost of the equipment.

[0133] (4) Compared with the method of fixing the high-potential battery cells to charge the low-potential battery cells, at this time, the high-potential battery cells are in a high-temperature state for a long time and are easily damaged, while the high-potential battery cells of the present invention can be shipped, thus reducing the manufacturing cost.

[0134] Refer to Figure 4 , Figure 4 which is a flowchart of a battery cell aging method of the present invention.

[0135] In some embodiments of the present invention, the present invention provides a battery cell aging device, including a tray, and the tray is the battery cell charging and discharging tray in any of the above embodiments.

[0136] In some embodiments of the present invention, the present invention further provides a battery cell aging method, using the battery cell aging device in any of the above embodiments for aging, including the following steps:

[0137] Step 101: Connect the positive electrode columns of at least one Class-A battery cell 5 in the first state and at least one Class-B battery cell 6 in the second state in sequence through a first conductive component 21, and connect the negative electrode columns in sequence through a second conductive component 22. The potential of the Class-A battery cell 5 is higher than that of each Class-B battery cell 6.

[0138] Step 102: Let the connected battery cells stand for a first duration t1 at a first set temperature T1.

[0139] Step 103: Cool the battery cells at a second set temperature T2, where T1 > T2.

[0140] Step 104: Test the open-circuit voltage OCV1 of each battery cell.

[0141] Step 105: Let it stand for a second duration t2 at the second set temperature.

[0142] Step 106: Test the open-circuit voltage OCV2 of each battery cell.

[0143] Step 107: Judge whether each battery cell is qualified according to the open-circuit voltage OCV1 and the open-circuit voltage OCV2 according to the set rules.

[0144] In the technical solution of the embodiment of the present invention, through Step 101, the Class-A battery cells 5 and each Class-B battery cell 6 can be connected in parallel in sequence, and the potential of the Class-A battery cells 5 needs to be higher than that of each Class-B battery cell 6, so as to achieve the purpose of continuously charging each Class-B battery cell 6 through the Class-A battery cells 5 during the aging process.

[0145] In the technical solution of the embodiment of the present invention, in order to facilitate the picking and placing of the connected battery cells during the aging process, before connecting the battery cells, the Class-A battery cells 5 and each Class-B battery cell 6 can be placed on the base component 1 in sequence, or after arranging the Class-A battery cells 5 and each Class-B battery cell 6 in sequence, the fastening component 4 can be used to surround the battery cells to achieve integral fastening. The base component 1 or the fastening component 4 is generally made of an insulating material to avoid accidental contact with the first conductive component 21 or the second conductive component 21, which may cause a short circuit of the battery cells. In addition, the battery cells can be isolated from each other by a baffle 31 to prevent the battery cells from colliding and causing a fire, resulting in a safety accident.

[0146] In the technical solution of the embodiment of the present invention, each Class-B battery cell 6 is generally a lithium iron phosphate (LFP) system battery cell. The battery cells of this system are cathode lithium supplement materials, so they also have the ability of high potential, but the content is small and the retention rate of high potential is low. Therefore, continuous charging is required to maintain the high potential. In order to avoid insufficient energy for the Class-A battery cells 5 to charge each Class-B battery cell 6 during the aging process, each Class-B battery cell 6 can be charged to a full charge state before aging.

[0147] In the technical solution of the embodiment of the present invention, the type-A battery cells are used to charge each type-B battery cell. Therefore, the potential of the type-A battery cells needs to be higher than that of each type-B battery cell. A battery cell with a maximum working voltage ≥ 4.05V is called a high-potential system battery cell, which can be used as the type-A battery cell in some embodiments of the present invention. Generally, it is a battery cell of the NCM system, and can also be a battery cell of systems such as lithium cobaltate, ternary, and high nickel. The type-A battery cells need to be charged to SOC ≥ 70% before they can maintain their potential ≥ 3.85V.

[0148] It should be noted that the voltage of the NCM system battery cell for measuring the K value process is ≥ 3.85V, while the stable potential of the LFP system battery cell is 3.4 - 3.5V. Therefore, during the process of measuring the K value, the LFP system needs to always maintain a fully charged state.

[0149] Each type-B battery cell 6 is generally a battery cell of the LFP system. The battery cell of this system is a cathode lithium supplement material, so it also has the ability of high potential, but the content is small and the retention rate of high potential is low. Therefore, continuous charging is required to maintain high potential. In order to avoid insufficient energy for each type-A battery cell 5 to charge each type-B battery cell 6 during the aging process, each type-B battery cell 6 can be charged to a fully charged state before aging.

[0150] Considering from the perspectives of aging cost, efficiency, and effect, the specific process parameters are selected as the first set temperature T1 is 25 - 80°C or 35 - 80°C, the second set temperature T2 is room temperature, the first duration t1 is 0 - 7 days or 0 - 5 days, and the second duration t2 is 12 hours - 30 days.

[0151] The rule for selecting defective products in the above method can be designed according to the needs of customers. Preferably, the voltage drop per unit time of each battery cell is calculated according to the formula K = (OCV2 - OCV1) / t2, and then the voltage drop per unit time is converted into the K value specification according to the monthly self-discharge requirement. The battery cells with a voltage drop greater than the K value specification are judged as unqualified, and the battery cells with a voltage drop less than or equal to the K value specification are judged as qualified. For customers with high requirements for quality control, the rule can also be tightened for selection, such as increasing the K value specification by a certain proportion.

[0152] In some embodiments of the present invention, the first state is the state of charge ≥ 70% and the maintained potential ≥ 3.85V.

[0153] In some embodiments of the present invention, the second state is fully charged with lithium supplementation.

[0154] In some embodiments of the present invention, the maximum working voltage of each type-A battery cell 5 is ≥ 4.05V.

[0155] In some embodiments of the present invention, the type-A battery cell 5 is a battery cell of the NCM system, lithium cobaltate, ternary system, or high nickel system.

[0156] In some embodiments of the present invention, each type-B battery cell 6 is a battery cell of the LFP system.

[0157] In some embodiments of the present invention, the first set temperature T1 is 25 - 80 °C or 35 - 80 °C.

[0158] In some embodiments of the present invention, the second set temperature T2 is room temperature.

[0159] In some embodiments of the present invention, the first duration t1 is 0 - 7 days or 0 - 5 days.

[0160] In some embodiments of the present invention, the second duration t2 is 12 hours - 30 days.

[0161] In some embodiments of the present invention, the setting rule is to calculate the voltage drop per unit time of each battery cell according to the formula K = (OCV2 - OCV1) / t2, and then convert the voltage drop per unit time to the K-value specification according to the monthly self-discharge requirement. The battery cells with a voltage drop greater than the K-value specification are determined to be unqualified, and the battery cells with a voltage drop less than or equal to the K-value specification are determined to be qualified.

[0162] In some embodiments of the present invention, before step 101, the type-A battery cells 5 and each type-B battery cell 6 are sequentially placed on the base member 1, or the type-A battery cells 5 and various battery cells 6 are sequentially arranged and then integrally fastened by surrounding each battery cell with the fastening member 4.

[0163] In some embodiments of the present invention, the base member 1 and the fastening member 4 have insulating properties.

[0164] In some embodiments of the present invention, before step 101, a step of placing the separation member 3 between each battery cell is added.

[0165] In some embodiments of the present invention, before or after step 103, the first conductive member 21 and the second conductive member 22 are removed.

[0166] In some embodiments of the present invention, the beneficial effects achieved by using the above battery cell aging method are as follows:

[0167] When the battery cells are aging, if the potential of the battery cells is low and the voltage is unstable, the purpose of effectively performing high-temperature and high-potential chemical self-discharge and accelerating metal precipitation cannot be achieved. Therefore, the above battery cell aging method connects the high-potential battery cells in parallel with the low-potential battery cells, so that the high-potential battery cells continuously charge the low-potential battery cells, thereby raising the potential of the low-potential battery cells and stabilizing the voltage, so as to effectively achieve the purpose of high-temperature and high-potential chemical self-discharge and accelerating metal precipitation.

[0168] It should be understood that the embodiments disclosed in the present invention are not limited to the specific processing steps or materials disclosed herein, but should extend to equivalent alternatives of such features understood by those of ordinary skill in the relevant art. It should also be understood that the terms used herein are for the purpose of describing particular embodiments only and do not imply limitation.

[0169] As used herein, the term "embodiment" means that a particular feature or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, the phrase "an embodiment" or "embodiments" that appear throughout the specification are not necessarily all referring to the same embodiment.

[0170] In addition, the described features or characteristics may be combined in any other suitable manner into one or more embodiments. In the above description, some specific details, such as thickness, quantity, etc., are provided to provide a comprehensive understanding of the embodiments of the present invention. However, those skilled in the relevant art will understand that the present invention can be implemented without one or more of the above specific details or can also be implemented using other methods, components, materials, etc.

Claims

1. A method for aging an electric cell, characterized in that, It includes the following steps: Step 1: Connect the positive electrode columns of at least one type-A battery cell (5) in the first state and at least one type-B battery cell (6) in the second state in sequence through a first conductive component (21), and connect the negative electrode columns in sequence through a second conductive component (22). The potential of the type-A battery cell (5) is higher than that of each type-B battery cell (6). Step 2: Let the connected battery cells stand for a first duration t1 at a first set temperature T1. Step 3: Cool the battery cells at a second set temperature T2, where T1 > T2. Step 4: Test the open-circuit voltage OCV1 of each battery cell. Step 5: Let the battery cells stand for a second duration t2 at the second set temperature. Step 6: Test the open-circuit voltage OCV2 of each battery cell. Step 7: Judge whether each battery cell is qualified according to the set rules based on the voltage OCV1 and the voltage OCV2.

2. The method for aging an electric cell according to claim 1, wherein The first state is that the state of charge ≥ 70% and the maintained potential ≥ 3.85V, and the second state is full charge and lithium supplementation.

3. The method for aging an electric cell according to claim 1, wherein The maximum working voltage of each type-A battery cell (5) ≥ 4.05V.

4. The method for aging an electric cell according to claim 1, wherein The first set temperature T1 is 35 - 80°C, and the second set temperature T2 is room temperature.

5. The method for aging an electric cell according to claim 1, characterized in that, The first duration t1 is 0 - 7 days or 0 - 5 days, and the second duration t2 is 12 hours - 30 days.

6. The method for aging an electric cell according to claim 1, wherein The set rules are as follows: Calculate the voltage drop per unit time of each battery cell according to the formula K = (OCV2 - OCV1) / t2, and then calculate the voltage drop per unit time as the K value specification according to the monthly self-discharge requirement. The battery cells with a voltage drop greater than the K value specification are judged as unqualified, and the battery cells with a voltage drop less than or equal to the K value specification are judged as qualified.

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