Accelerated test method for battery, battery and electric device

Abstract

The invention provides an accelerated test method for a battery, the battery and a power utilization device, and belongs to the technical field of batteries. An acceleration test method for a battery including a plurality of battery cells includes: calibrating an acceleration standard potential and a state of charge reference value for an acceleration test based on a single battery cell of the plurality of battery cells; acquiring a battery based on the battery for testing, wherein the battery for testing comprises a pressure sensing device; and performing an acceleration test on the test battery based on the acceleration standard potential and the charge state reference value.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and in particular to an accelerated test method for a battery, a battery, and an electrical device using the same. Background Art

[0002] Energy conservation and emission reduction are the keys to the sustainable development of the automotive industry. Electric vehicles have become an important part of the sustainable development of the automotive industry due to their advantages of energy conservation and environmental protection. For electric vehicles, battery technology is an important factor related to their development.

[0003] The performance of a battery can be evaluated by an accelerated test method. The accelerated test method can achieve the same life attenuation of the battery with a significant reduction in the number of cycles, thereby quickly realizing the evaluation of the battery performance. Since the battery has a corresponding mechanical structure, it is also important to consider the impact of the expansion force generated by the battery on the battery mechanical structure in the accelerated test method. Summary of the Invention

[0004] The present application aims to solve at least one of the technical problems existing in the background art. To this end, an object of the present application is to provide an accelerated test method that can comprehensively consider the impact of the expansion force generated by the battery on the battery mechanical structure in the accelerated test method, thereby improving the authenticity of the evaluation result obtained by the accelerated test method.

[0005] An embodiment of the first aspect of the present application provides an accelerated test method for a battery. The battery includes a plurality of battery cells, including: calibrating an acceleration standard potential and a state of charge (SOC) reference value for the accelerated test based on a single battery cell among the plurality of battery cells; obtaining a test battery based on the battery, the test battery including a pressure sensing device; and performing an accelerated test on the test battery based on the acceleration standard potential and the SOC reference value.

[0006] In the technical solution of the embodiment of the present application, by calibrating the SOC reference value for the accelerated test based on a single battery cell and performing the accelerated test based on the SOC reference value, it is possible to simulate the impact effect of the expansion force generated by the battery on the battery mechanical structure by using the SOC reference value during the accelerated test. At the same time, the accelerated test method of the present application is implemented by using a test battery including a pressure sensing device, which enables obtaining data related to the expansion force of the battery during the entire accelerated test for evaluation. Therefore, the accelerated test method according to the embodiment of the present application can comprehensively consider the impact of the expansion force generated by the battery on the battery mechanical structure, thereby improving the authenticity of the evaluation result obtained by the accelerated test method.

[0007] In some embodiments, calibrating an acceleration standard potential for an accelerated test based on a single battery cell among a plurality of battery cells includes: sequentially performing a charging operation and a discharging operation on the single battery cell, wherein, during the discharging operation, discharging data of the single battery cell is collected, and the discharging data includes the full-cell potential and the discharging capacity collected at a predetermined time interval; and determining the acceleration standard potential based on the discharging data. In this way, the characteristics reflecting the electrical performance degradation of the single battery cell can be obtained by acquiring the corresponding discharging data through the charge-discharge process of the single battery cell, thereby determining the discharging potential to be used in the accelerated test. Since this process can involve only a single charge-discharge process, the acceleration standard potential can be calibrated quickly and accurately.

[0008] In some embodiments, determining the acceleration standard potential based on the discharging data includes: obtaining a first curve graph of the differential potential varying with the full-cell potential, wherein the differential potential is obtained by calculating the ratio of the difference in the full-cell potential at two adjacent moments with a predetermined time interval to the difference in the discharging capacity; and determining the full-cell potential corresponding to the disappearance of the peak value of the differential potential in the first curve graph as the acceleration standard potential. In this way, the discharging characteristics of the single battery cell can be characterized by means of the relationship between the differential potential and the full-cell potential, and further the characteristics reflecting its electrical performance degradation can be reflected. Accordingly, the discharging potential required to degrade the electrical performance of the single battery cell to a predetermined degree, that is, the acceleration standard potential, can be found from such discharging characteristics. Since the discharging data of the full-cell potential and the discharging capacity are easy to collect, the process for calibrating the acceleration standard potential is easy to implement, and further it is convenient to implement the overall accelerated test method.

[0009] In some embodiments, calibrating an SOC reference value for an accelerated test based on a single battery cell among a plurality of battery cells includes: obtaining a second curve graph of the swelling force of the single battery cell varying with the SOC during the charging operation and the discharging operation; and determining the SOC corresponding to the first peak value of the swelling force in the second curve graph as the SOC reference value. In this way, the SOC value required for simulating the impact effect of the swelling force generated by the battery or the battery cell on the battery mechanical structure during the accelerated test process can be quickly obtained by means of a single charge-discharge operation of the single battery cell.

[0010] In some embodiments, an accelerated test is performed on a test battery based on an accelerated standard potential and an SOC reference value, including: performing a charging operation and a discharging operation on the test battery in sequence, where the charging duration of the charging operation is determined based on the SOC reference value, and the discharging potential of the discharging operation is determined based on the accelerated standard potential. In this way, during the accelerated test, the simulation of the impact effect of the swelling force can be introduced through the pre-determined SOC reference value during the charging operation, and the accelerated test effect can be achieved through the pre-determined accelerated standard potential during the discharging process. Thus, it is convenient to perform the accelerated test while taking into account the impact effect of the swelling force.

[0011] In some embodiments, the charging duration of the charging operation is the product of the unit hour and the SOC reference value. In this way, the simulation of the impact effect of the swelling force can be introduced during the charging operation by calculating the product of the unit hour and the SOC reference value, thus facilitating the performance of the accelerated test while taking into account the impact effect of the swelling force.

[0012] In some embodiments, obtaining a test battery based on a battery includes: replacing at least one battery cell located at a predetermined position among a plurality of battery cells with a pressure sensing device, where the pressure sensing device includes a pressure sensor and support members on both sides of the pressure sensor. In this way, a test battery for the accelerated test can be made by replacing the battery cell with the pressure sensing device, so that the swelling force data can be monitored during the accelerated test of the test battery.

[0013] In some embodiments, obtaining a test battery based on a battery further includes: electrically connecting the remaining battery cells among the plurality of battery cells except for at least one battery cell located at a predetermined position. In this way, the remaining battery cells can be processed by electrical connection in the test battery, so as to make a test battery that can monitor the swelling force data during the accelerated test.

[0014] In some embodiments, the electrical connection includes series connection, and the discharging operation includes at least two discharging stages, and the discharging potential in each discharging stage is the product of a predetermined discharging cut-off voltage and the number of the remaining series-connected battery cells. In this way, the accelerated test mechanism can be realized by using different at least two discharging stages, and the method of connecting the remaining battery cells in series is easy to implement, so it provides convenience for the overall accelerated test.

[0015] In some embodiments, the predetermined discharging cut-off voltage in the last discharging stage of the at least two discharging stages is the accelerated standard potential. By setting the discharging cut-off voltage to the accelerated standard potential for over-discharging in the last discharging stage, it is convenient to realize the accelerated test mechanism.

[0016] In some embodiments, the accelerated test method further includes: respectively obtaining a third curve graph of the swelling force of the battery under test varying with the state of health (SOH) during the accelerated test process and the normal test process, the third curve graph including a first sub-curve corresponding to the accelerated test and a second sub-curve corresponding to the normal test; and determining whether the result of the accelerated test is credible based on the comparison between the first sub-curve and the second sub-curve. In this way, it is possible to measure whether the result of the accelerated test is credible according to the change of the swelling force with the SOH. Thus, on the one hand, the accelerated test can be realized while taking into account the swelling force, and on the other hand, it is convenient to obtain the swelling force data for evaluation, thereby facilitating the evaluation of the authenticity of the overall accelerated test.

[0017] In some embodiments, determining whether the result of the accelerated test is credible based on the comparison between the first sub-curve and the second sub-curve includes: respectively performing linear fitting on the first sub-curve and the second sub-curve to obtain a first fitting slope and a second fitting slope; determining the deviation between the first fitting slope and the second fitting slope; determining whether the deviation satisfies a predetermined condition; and in response to determining that the deviation satisfies the predetermined condition, determining that the result of the accelerated test is credible. By performing linear fitting, the slope values for comparing the two sub-curves can be indirectly obtained, and then the difference between the two sub-curves can be judged by means of the slope, thereby determining whether the result of the accelerated test is credible.

[0018] An embodiment of the second aspect of the present application provides a battery that performs an accelerated test according to the method of the above embodiment.

[0019] An embodiment of the third aspect of the present application provides an electrical device, which includes the battery in the above embodiment, and the battery is used to provide electrical energy.

[0020] The above description is only an overview of the technical solution of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present application more obvious and understandable, the specific embodiments of the present application are specifically exemplified below. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In the drawings, unless otherwise specified, the same reference numerals throughout the several views denote the same or similar components or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed according to the present application and should not be regarded as limiting the scope of the present application.

[0022] Figure 1 is a schematic exploded view of a battery according to some embodiments of the present application;

[0023] Figure 2Flow chart of the accelerated test method for a battery according to some embodiments of the present application;

[0024] Figure 3 Flow chart of the process for calibrating the accelerated standard potential according to some embodiments of the present application;

[0025] Figure 4 Schematic diagram of the first curve graph showing the change of differential potential with the full cell potential according to some embodiments of the present application;

[0026] Figure 5 Schematic diagram of the device for collecting the swelling force data of a single battery cell according to some embodiments of the present application;

[0027] Figure 6 Schematic diagram of the second curve graph showing the change of the swelling force of a single battery cell with the SOC according to some embodiments of the present application;

[0028] Figure 7 Schematic diagram of the test battery according to some embodiments of the present application;

[0029] Figure 8 Flow chart of the process for determining whether the result of the accelerated test is credible according to some embodiments of the present application;

[0030] Figure 9 Schematic diagram of the third curve graph showing the change of the swelling force of the test battery with the SOH during the accelerated test and the normal test according to some embodiments of the present application.

[0031] Explanation of reference numerals:

[0032] Battery 100, battery cell 20, box body 10, first part 11, second part 12;

[0033] Swelling force acquisition device 500, battery cell 510, first fixing member 520, second fixing member 524, pressure sensor 522, fastening member 526;

[0034] Test battery 700, side plate 701, end plate 702, battery cell 720, pressure sensing device 710, pressure sensor 710a, support member 710b, conductive bus bar 730. Detailed description of the specific implementation

[0035] Hereinafter, embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, so they are only examples and cannot be used to limit the protection scope of the present application.

[0036] 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 application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above description of the drawings are intended to cover non-exclusive inclusion.

[0037] In the description of the embodiments of this application, technical terms such as "first" and "second" 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 this application, the meaning of "a plurality" is more than two, unless otherwise specifically and clearly defined.

[0038] Referring to "embodiments" herein means that specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of this application. The phrase appearing in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0039] In the description of the embodiments of this application, the term "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. Additionally, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0040] In the description of the embodiments of this application, the term "a plurality" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0041] In the description of the embodiments of this application, 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, and is only for the convenience of describing the embodiments of this application and simplifying the description, rather than indicating or implying 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 to the embodiments of this application.

[0042] In the description of the embodiments of the present application, unless otherwise clearly specified or limited, technical terms such as "installation", "connection", "attachment", and "fixation" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral one; it may also be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may 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 application can be understood according to specific circumstances.

[0043] At present, from the perspective of the development of the market situation, the application of power batteries is becoming more and more extensive. Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in multiple fields such as military equipment and aerospace. With the continuous expansion of the application fields of power batteries, the market demand is also continuously increasing.

[0044] For safety considerations, both the electrical performance and mechanical performance of the battery need to be accurately evaluated. In particular, during the entire life cycle of the battery, since the battery will experience a certain degree of expansion and contraction during each charge and discharge process and the expansion force will gradually increase, it may cause the mechanical structure of the battery (such as end plates, side plates, tabs, welds, etc.) to withstand thousands of impacts.

[0045] Traditional evaluation schemes may include normal testing methods, that is, normally cycling the battery to age it to the end of work (EOW) or end of life (EOL) state. However, although this normal testing method can evaluate the reliability of the battery's mechanical structure, the required evaluation cycle is relatively long, often taking more than one and a half years, or even two years.

[0046] The industry has also proposed using an accelerated testing method to quickly evaluate the battery performance. The accelerated testing method can achieve the same life attenuation of the battery with a significant reduction in the number of cycles. However, the significant reduction in the number of cycles may also greatly reduce the impact of the expansion force generated by the battery on the battery's mechanical structure (for example, the impact experienced during 2000 charge and discharge processes in the normal testing method is only about 400 times in the accelerated testing method). As a result, the evaluation results obtained through this accelerated testing method are somewhat distorted compared to the evaluation results obtained through the normal testing method, greatly reducing the authenticity of the evaluation results.

[0047] In order to comprehensively consider the impact of the swelling force generated by the battery on the mechanical structure of the battery in the accelerated test method, so as to improve the authenticity of the evaluation results obtained by the accelerated test method, the present application proposes an accelerated test method. In this method, the state of charge (SOC) reference value for the accelerated test is calibrated based on a single battery cell, and the accelerated test is carried out based on this SOC reference value, so that the impact effect of the swelling force generated by the battery on the mechanical structure of the battery can be simulated by using this SOC reference value during the accelerated test. At the same time, the accelerated test method of the present application is realized by means of a test battery including a pressure sensing device, which enables data related to the swelling force of the battery to be obtained during the entire accelerated test process for evaluation.

[0048] The battery disclosed in the embodiments of the present application can be used, but is not limited to, power-consuming devices such as vehicles, ships or aircraft. A power supply system of the power-consuming device can be composed of the battery disclosed in the present application.

[0049] The embodiments of the present application provide a power-consuming device using a battery as a power source. The power-consuming device can be, but is not limited to, a mobile phone, a tablet computer, a laptop computer, an electric toy, an electric tool, a battery car, an electric vehicle, a ship, a spacecraft, etc. Among them, the electric toy can include a fixed or mobile electric toy, for example, a game console, an electric vehicle toy, an electric ship toy, an electric aircraft toy, etc., and the spacecraft can include an airplane, a rocket, a space shuttle, a spaceship, etc.

[0050] Please refer to Figure 1 , Figure 1 which is a schematic exploded view of the battery provided in some embodiments of the present application. The battery 100 includes a box body 10 and battery cells 20, and the battery cells 20 are accommodated in the box body 10. Among them, the box body 10 is used to provide an accommodation space for the battery cells 20, and the box body 10 can adopt various structures. In some embodiments, the box body 10 can include a first part 11 and a second part 12, the first part 11 and the second part 12 are covered with each other, and the first part 11 and the second part 12 jointly define an accommodation space for accommodating the battery cells 20. The second part 12 can be a hollow structure with one end open, and the first part 11 can be a plate-like structure. The first part 11 covers the open side of the second part 12 so that the first part 11 and the second part 12 jointly define an accommodation space; the first part 11 and the second part 12 can also both be hollow structures with one side open, and the open side of the first part 11 covers the open side of the second part 12. Of course, the box body 10 formed by the first part 11 and the second part 12 can be of various shapes, such as a cylinder, a cuboid, etc.

[0051] In the battery 100, there may be multiple battery cells 20. The multiple battery cells 20 can be connected in series, in parallel, or in a combined series-parallel connection. A combined series-parallel connection means that there are both series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 can be directly connected in series, in parallel, or in a combined series-parallel connection and then the whole formed by the multiple battery cells 20 is accommodated in the box 10. Of course, the battery 100 can also be that multiple battery cells 20 are first connected in series, in parallel, or in a combined series-parallel connection to form a battery module, and then multiple battery modules are connected in series, in parallel, or in a combined series-parallel connection to form a whole and are accommodated in the box 10. The battery 100 can also include other structures. For example, the battery 100 can also include a busbar component for realizing the electrical connection among the multiple battery cells 20.

[0052] Among them, each battery cell 20 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 can be in a cylindrical shape, a flat shape, a cuboid shape, or other shapes, etc.

[0053] An embodiment of the present application provides an accelerated test method for a battery including multiple battery cells. Figure 2 It is a flowchart of the accelerated test method for some embodiments of the present application. As Figure 2 shown, the accelerated test method includes steps S202, S204, and S206. In step S202, based on a single battery cell among the multiple battery cells, an accelerated standard potential and a state of charge (SOC) reference value for the accelerated test are calibrated. In step S204, a test battery for the battery is obtained, and the test battery includes a pressure sensing device. In step S206, based on the accelerated standard potential and the SOC reference value, an accelerated test is performed on the test battery.

[0054] In some embodiments, the battery and the battery cell can be, for example, Figure 1 the battery 100 and the battery cell 20 as shown. The battery 100 includes multiple battery cells 20. An accelerated standard potential and an SOC reference value for performing an accelerated test on the battery can be calibrated based on any one of the multiple battery cells 20.

[0055] In some embodiments, the accelerated standard potential can refer to the discharge potential required to be applied during the accelerated test to simulate the situation where the life or electrical performance of the battery or the battery cell drops to a predetermined level. The SOC reference value can refer to the SOC value required to be referenced during the accelerated test to simulate the impact effect of the swelling force generated by the battery or the battery cell on the mechanical structure of the battery.

[0056] In some embodiments, the test battery can be made by adding a pressure sensing device to the battery. The pressure sensing device is used to monitor in real time the swelling force generated by the battery cells in the battery during the accelerated test.

[0057] In some embodiments, the accelerated test may have a predetermined cut-off condition, such as reaching a predetermined number of cycles or the battery capacity dropping to a predetermined value.

[0058] In some embodiments, the execution order of step S202 and step S204 can be changed. For example, step S202 can be executed first, and then step S204; alternatively, step S204 can be executed first, and then step S202. Alternatively, step S202 and step S204 can be executed in parallel.

[0059] In the embodiments of the present application, by calibrating the SOC reference value for the accelerated test based on a single battery cell and performing the accelerated test based on the SOC reference value, it is possible to simulate the impact effect of the expansion force generated by the battery on the mechanical structure of the battery by virtue of the use of the SOC reference value during the accelerated test. At the same time, the accelerated test method of the present application is implemented by means of a test battery including a pressure sensing device, which enables data related to the expansion force of the battery to be obtained throughout the accelerated test for evaluation. Therefore, the accelerated test method according to the embodiments of the present application can comprehensively consider the impact of the expansion force generated by the battery on the mechanical structure of the battery, thereby improving the authenticity of the evaluation results obtained by the accelerated test method.

[0060] According to some embodiments of the present application, as Figure 2 shown in step S202, calibrating the acceleration standard potential can correspond to the process of calibrating the acceleration standard potential as Figure 3 shown. Figure 3 is a flowchart of the process of calibrating the acceleration standard potential for some embodiments of the present application. As Figure 3 shown, the process of calibrating the acceleration standard potential may include steps S302 and S304. In step S302, a charging operation and a discharging operation can be sequentially performed on a single battery cell. During the discharging operation, the discharging data of the single battery cell is collected, and the discharging data includes the full-cell potential and the discharging capacity collected at a predetermined time interval. In step S304, based on the discharging data, the acceleration standard potential can be determined.

[0061] In some embodiments, a single battery cell can be charged at a constant current to reach a predetermined charging capacity. It is also possible to further perform a constant-voltage charging on the basis of the constant-current charging so that the single battery cell reaches a fully charged state from the above-mentioned predetermined charging capacity.

[0062] In some embodiments, a single battery cell can be discharged at a constant current. The constant-current discharging may include a stage for realizing over-discharging, and in this case, the discharging data of the single battery cell can be collected during the over-discharging process.

[0063] In some embodiments, the full cell potential may refer to the difference between the positive electrode potential and the negative electrode potential of a single battery cell. When the full cell potential is acquired at a certain time point during the discharge process, the corresponding discharge capacity at this time point can be obtained based on the battery capacity of the single battery cell.

[0064] In some embodiments, the predetermined time interval may include a fixed time interval or a variable time interval.

[0065] In some embodiments, the discharge data can be processed to characterize the discharge characteristics of a single battery cell, and the discharge characteristics can reflect the characteristics of the degradation of the electrical performance of the single battery cell. Thus, according to the discharge characteristics, the discharge potential required to degrade the electrical performance of the single battery cell to a predetermined level, i.e., the accelerated standard potential, can be determined.

[0066] In the embodiments of the present application, the corresponding discharge data can be obtained by means of the charge-discharge process of a single battery cell to obtain the characteristics reflecting the life or the degradation of the electrical performance of the single battery cell, and thus the discharge potential to be used in the accelerated test can be determined. Since this process can only involve a single charge-discharge process, the accelerated standard potential can be calibrated quickly and accurately.

[0067] According to some embodiments of the present application, as Figure 3 shown, step S304 may include: obtaining a first curve graph of the differential potential varying with the full cell potential, wherein the differential potential is obtained by calculating the ratio of the difference between the full cell potentials at two adjacent moments with a predetermined time interval to the difference between the discharge capacities; and determining the full cell potential corresponding to the disappearance of the peak of the differential potential in the first curve graph as the accelerated standard potential.

[0068] In some embodiments, please refer to Figure 4 , Figure 4 is a schematic diagram of a first curve graph 400 of the differential potential varying with the full cell potential according to some embodiments of the present application. In the first curve graph 400, the vertical coordinate may represent the differential voltage, and the horizontal coordinate may represent the full cell potential. As Figure 4 shown, a first peak is formed at about 1.9V of the full cell potential in the first curve graph 400. This first peak gradually decreases as the full cell potential decreases, and a second peak is formed at about 1.3V of the full cell potential. This second peak continues to decrease as the full cell potential decreases, and a plateau is formed at about 1.0V of the full cell potential, and thus the peak disappears. Therefore, the full cell potential corresponding to the disappearance of the peak of the differential potential at 410 in the first curve graph 400 can be determined as the accelerated standard potential, as Figure 4 shown as 1.0V.

[0069] In some embodiments, the differential potential can be calculated by the following formula 1:

[0070] diff t2 =(V t2 -V t1 ) / (Q t2 -Q t1 ) (Formula 1)

[0071] wherein, t1 and t2 can represent two adjacent moments with a predetermined time interval (for example, 1 second), for example, t2 is after t1; diff t2 can represent the differential potential at the moment of t2; V t2 , Q t2 can represent the full cell potential and discharge capacity at the moment of t2, and V t1 , Q t1 can represent the full cell potential and discharge capacity at the moment of t1.

[0072] In the embodiments of the present application, the discharge characteristics of a single battery cell can be characterized by means of the relationship between the differential potential and the full cell potential, so as to reflect the characteristics of its electrical performance degradation. Accordingly, the discharge potential required to reduce the electrical performance of the single battery cell to a predetermined level, that is, the accelerated standard potential, can be found from such discharge characteristics. Since the discharge data of the full cell potential and discharge capacity are easy to collect, the process for calibrating the accelerated standard potential is easy to implement, and thus it is convenient to implement the overall accelerated test method.

[0073] According to some embodiments of the present application, calibrating the SOC reference value in step S202 as shown in Figure 2 may include: obtaining a second curve graph of the expansion force of a single battery cell changing with the SOC during the charging operation and the discharging operation; and determining the SOC corresponding to the first peak value of the expansion force in the second curve graph as the SOC reference value.

[0074] In some embodiments, please refer to Figure 5 , Figure 5 which is a schematic diagram of an expansion force acquisition device 500 for acquiring the expansion force data of a single battery cell according to some embodiments of the present application. As shown in Figure 5As shown, the device 500 may include: a first fixing member 520 for fixing the battery cell 510, which may be disposed on both sides of the battery cell 510 to clamp the battery cell 510; a pressure sensor 522, which may be disposed on either side of the battery cell 510 and abutted against the fixing member 520 on that side; a second fixing member 524 for fixing the pressure sensor 522, and the second fixing member 524 and the first fixing member 520 may be respectively disposed on both sides of the pressure sensor 522 to clamp the pressure sensor 522; and a fastening member 526 for fastening the first fixing member 520 and the second fixing member 524 together. In an example, the battery cell 510 may be a hard-shell battery cell taken out from a battery. The first fixing member 520 and the second fixing member 524 may include stainless steel plates or other material plates, etc. The fastening member 526 may include bolts, screws, etc. After the device 500 is installed, due to the clamping force, a certain initial pressure (e.g., 1000 kgf) may be applied to the battery cell 510, and the pressure sensor 522 may sense the initial pressure.

[0075] In some embodiments, please refer to Figure 6 , Figure 6 is a schematic diagram of a second curve graph 600 showing the change of the expansion force of a single battery cell with respect to the SOC according to some embodiments of the present application. In the second curve graph 600, the vertical coordinate may represent the expansion force, and the horizontal coordinate may represent the SOC. For ease of observation, the second curve graph 600 shows the change of the expansion force with respect to the SOC during both the charging operation and the discharging operation, that is, the change of the expansion force during a single charge-discharge operation. In order to simulate the impact effect of the expansion force on the mechanical structure, as Figure 6 shown, the SOC corresponding to the first peak value 610 of the expansion force in the second curve graph 600 may be determined as the SOC reference value, that is, as Figure 6 shown, 30% (which may be denoted as S x = 30%).

[0076] In the embodiments of the present application, the SOC value required for reference to simulate the impact effect of the expansion force generated by the battery or the battery cell on the battery mechanical structure during the accelerated test process can be quickly obtained by means of a single charge-discharge operation of a single battery cell.

[0077] According to some embodiments of the present application, as Figure 2 shown, the step S206 may include: sequentially performing a charging operation and a discharging operation on the test battery, wherein the charging duration of the charging operation is determined based on the SOC reference value, and the discharging potential of the discharging operation is determined based on the accelerated standard potential.

[0078] In some embodiments, in order to comprehensively consider the impact of the swelling force during the accelerated test, a SOC reference value determined based on the change of the swelling force of a single battery cell with the SOC can be introduced during the charging operation to simulate the impact effect of the swelling force. To this end, the charging duration of the charging operation can be determined based on this SOC reference value.

[0079] In some embodiments, since the accelerated standard potential itself is the discharge potential required to reduce the electrical performance of a battery or a battery cell to a predetermined level during the accelerated test, the discharge potential of the discharge operation can be determined based on this accelerated standard potential.

[0080] In some embodiments, the test battery can be subjected to multiple cycles of a charging operation and a discharging operation (for example, reaching a predetermined number of cycles or the battery capacity dropping to a predetermined value).

[0081] In the embodiments of the present application, during the accelerated test, the simulation of the impact effect of the swelling force can be introduced through a predetermined SOC reference value during the charging operation, and the accelerated test effect can be achieved through a predetermined accelerated standard potential during the discharging process. Thus, it is convenient to perform the accelerated test while comprehensively considering the impact effect of the swelling force.

[0082] According to some embodiments of the present application, the charging duration of the charging operation can be the product of the unit hour and the SOC reference value.

[0083] In some embodiments, taking Figure 6 the SOC reference value shown as 30% as an example, the charging duration of the charging operation can be determined as 1h * 30% = 0.3h, that is, 0.3 hours.

[0084] In the embodiments of the present application, the simulation of the impact effect of the swelling force can be introduced during the charging operation by means of calculating the product of the unit hour and the SOC reference value. Thus, it is convenient to perform the accelerated test while comprehensively considering the impact effect of the swelling force.

[0085] According to some embodiments of the present application, as Figure 2 shown, step S204 may include: replacing at least one battery cell at a predetermined position among a plurality of battery cells with a pressure sensing device, where the pressure sensing device includes a pressure sensor and support members on both sides of the pressure sensor.

[0086] In some embodiments, please refer to Figure 7 , Figure 7 which is a schematic diagram of the test battery 700 according to some embodiments of the present application. For the convenience of description, Figure 7The side plate 701 and the end plate 702 of the test battery 700 are schematically shown. In order to monitor the expansion force data during the accelerated test, a pressure sensing device 710 can be placed in the battery to fabricate the test battery 700. As Figure 7 shown, the battery cell at the central position among the multiple battery cells 720 can be replaced with the pressure sensing device 710. The pressure sensing device 710 can include a pressure sensor 710a and support members 710b on both sides of the pressure sensor 710a. The support members 710b can include stainless steel plates or other material plates, etc. In order to support the pressure sensor 710a to facilitate the accurate sensing of the expansion force by the pressure sensor 710a, the size (e.g., thickness) of the support members 710b can be adjusted so that the overall size (e.g., thickness) of the pressure sensor 710a and the support members 710b is equivalent to that of the replaced battery cell. That is, the support members 710b can play a filling role. It can be understood that replacing the battery cell at the central position can simulate a situation where the impact forces of the expansion forces on both sides of the battery are consistent, but the battery cell at a non - central position can also be replaced with the pressure sensing device 700. In addition, two or more battery cells can be replaced. For example, when there are two battery cells at the central position, these two battery cells can be replaced with the pressure sensing device 710 together.

[0087] In the embodiments of the present application, a test battery for accelerated testing can be fabricated by replacing the battery cells with pressure sensing devices, so that the expansion force data can be monitored during the accelerated test of the test battery.

[0088] According to some embodiments of the present application, as Figure 2 shown, step S204 can include: electrically connecting the remaining battery cells among the multiple battery cells except for at least one battery cell at a predetermined position.

[0089] In some embodiments, please continue to refer to Figure 7 , the remaining battery cells ( Figure 7 8 are schematically shown in) among the multiple battery cells 720 except for the battery cells at the central position can be electrically connected, for example, in series. For this purpose, the positive and negative electrodes of adjacent two battery cells can be connected together using a conductive bus bar 730, for example, by welding. At the same time, for the battery cells at the ends, the positive output terminal and the negative output terminal can be led out using the conductive bus bar 730.

[0090] In the embodiments of the present application, the remaining battery cells can be processed by electrical connection in the test battery, so as to fabricate a test battery capable of monitoring the expansion force data during the accelerated test.

[0091] According to some embodiments of the present application, the electrical connection may include a series connection, and the discharging operation may include at least two discharging stages, and the discharging potential in each discharging stage is the product of the predetermined discharging cut-off voltage and the number of the remaining battery cells connected in series.

[0092] In some embodiments, the discharging cut-off voltage in the first discharging stage may be a well-known lower limit voltage, such as 2.5V. Taking Figure 7 the example shown in which there are 8 remaining battery cells, the discharging potential in the first discharging stage may be 2.5V * 8 = 20V.

[0093] In some embodiments, each discharging stage may have a successively decreasing discharging cut-off voltage.

[0094] In some embodiments, the discharging operation may be performed on the test battery for multiple cycles (for example, reaching a predetermined number of cycles or the battery capacity dropping to a predetermined value).

[0095] In the embodiments of the present application, different at least two discharging stages can be used to implement an accelerated test mechanism, and the method of connecting the remaining battery cells in series is easy to implement, thus providing convenience for the overall accelerated test.

[0096] According to some embodiments of the present application, the predetermined discharging cut-off voltage in the last discharging stage among the at least two discharging stages is the accelerated standard potential.

[0097] In some embodiments, the last discharging stage can be used for over-discharging. Taking Figure 4 the accelerated standard potential shown in the example as 1.0V, the predetermined discharging cut-off voltage in the last discharging stage can be 1.0V. Correspondingly, taking Figure 7 the example shown in which there are 8 remaining battery cells, the discharging potential in the last discharging stage may be 1.0V * 8 = 8V.

[0098] In the embodiments of the present application, by setting the discharging cut-off voltage to the accelerated standard potential through over-discharging in the last discharging stage, it is convenient to implement the accelerated test mechanism.

[0099] According to some embodiments of the present application, the accelerated test method may further include a process for determining whether the result of the accelerated test is credible. Figure 8 is a flowchart of the process for determining whether the result of the accelerated test is credible in some embodiments of the present application. As Figure 8As shown, the accelerated test method may further include steps S802 and S804. In step S802, a third curve graph showing the change in the swelling force of the test battery during the accelerated test and the normal test with respect to the state of health (SOH) is obtained respectively. The third curve graph includes a first sub-curve corresponding to the accelerated test and a second sub-curve corresponding to the normal test. In step S804, based on the comparison between the first sub-curve and the second sub-curve, it is determined whether the result of the accelerated test is credible.

[0100] In some embodiments, relative to the accelerated test process, as described above, the normal test process may refer to normally cycling the battery to age the battery to the EOW or end-of-life state. Since the evaluation period required for the normal test process is often long, in practice, a part of the range of SOH change (for example, the range from 100% to 80% decrease) can be used for comparison with the result of the accelerated test.

[0101] In some embodiments, please refer to Figure 9 , Figure 9 is a schematic diagram of a third curve graph showing the change in the swelling force of the test battery during the accelerated test and the normal test with respect to SOH in some embodiments of the present application. As Figure 9 shown, in the third curve graph, the vertical coordinate may represent the swelling force, and the horizontal coordinate may represent the SOH. The third curve graph includes a first sub-curve 910 showing the change in the swelling force with respect to SOH during the accelerated test process, and a second sub-curve 920 showing the change in the swelling force with respect to SOH during the normal test process. Thus, it can be determined whether the result of the accelerated test is credible based on the comparison between the first sub-curve 910 and the second sub-curve 920.

[0102] In the embodiments of the present application, it is possible to measure whether the result of the accelerated test is credible based on the change in the swelling force with respect to SOH. Thus, on the one hand, the accelerated test can be realized while taking into account the swelling force, and on the other hand, it is convenient to obtain the swelling force data for evaluation, thereby facilitating the evaluation of the authenticity of the overall accelerated test.

[0103] According to some embodiments of the present application, step S804 as Figure 8 shown may include: respectively performing linear fitting on the first sub-curve and the second sub-curve to obtain a first fitting slope and a second fitting slope; determining the deviation between the first fitting slope and the second fitting slope; determining whether the deviation satisfies a predetermined condition; and in response to determining that the deviation satisfies the predetermined condition, determining that the result of the accelerated test is credible.

[0104] In some embodiments, as Figure 9 shown, an interval with SOH of 80% - 95% can be selected for linear fitting to make the fitting result more accurate. Figure 9The figure schematically shows the straight lines obtained by linearly fitting the first sub-curve 910 and the second sub-curve 920 respectively.

[0105] In some embodiments, the deviation of the accelerated test result can be calculated by the following formula:

[0106]

[0107] where α can represent the deviation of the accelerated test result; K1 can represent the second fitting slope corresponding to the normal test, and K2 can represent the first fitting slope corresponding to the accelerated test. In other words, the expression in Formula 2 above can represent the authenticity between the first fitting slope and the second fitting slope, such that the sum of the authenticity and the deviation is 1.

[0108] In some embodiments, when the authenticity is greater than or equal to 95% (i.e., when the deviation is less than or equal to 5%), the result of the accelerated test can be considered credible.

[0109] In the embodiments of the present application, by performing linear fitting, the slope value for comparing the two sub-curves can be indirectly obtained, and then the difference between the two sub-curves can be judged by means of the slope, thereby determining whether the result of the accelerated test is credible.

[0110] The embodiments of the present application provide a battery, and the battery is subjected to an accelerated test according to the method described above.

[0111] In some embodiments, the battery can be the battery 100 as Figure 1 shown. The battery can be used as a power source in an electrical device, and the electrical device can be but not limited to mobile phones, tablets, laptop computers, electric toys, electric tools, battery cars, electric vehicles, ships, spacecraft, etc. Among them, the electric toy can include fixed or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys, and electric aircraft toys, etc., and the spacecraft can include airplanes, rockets, space shuttles, and spaceships, etc.

[0112] In the embodiments of the present application, since the battery can be tested by an accelerated test method with higher authenticity, the battery performance can be quickly evaluated within a shorter evaluation period. At the same time, since the accelerated test method takes into account the impact of the expansion force generated by the battery on the mechanical structure of the battery, the evaluation result can accurately reflect the electrical performance and mechanical performance of the battery.

[0113] The embodiments of the present application provide an electrical device, including the battery described above, and the battery is used to provide electrical energy.

[0114] In some embodiments, the electrical device may be, but is not limited to, a mobile phone, a tablet computer, a laptop computer, an electric toy, an electric tool, a battery car, an electric vehicle, a ship, a spacecraft, and the like. Among them, the electric toy may include a stationary or mobile electric toy, for example, a game console, an electric vehicle toy, an electric ship toy, an electric airplane toy, and the like, and the spacecraft may include an airplane, a rocket, a space shuttle, a spaceship, and the like.

[0115] In the embodiments of the present application, since the electrical device uses a battery that can be evaluated via an acceleration test method with higher authenticity, the safety can be further guaranteed.

[0116] The embodiments of the present application are further described in detail below.

[0117] In the process of calibrating the acceleration standard potential by sequentially performing a charging operation and a discharging operation on a single battery cell, the following process may be adopted: 1) Let the single battery cell stand still for 5 minutes; 2) Perform constant current charging (CC) on the single battery cell at a charging rate of 1.0 times (1.0C) until a known upper limit voltage (for example, 3.6V); 3) Perform constant voltage charging (CV) at the known upper limit voltage (for example, 3.6V) until the charging current drops to 0.05 times the charging rate (0.05C); 4) Let the single battery cell stand still for 5 minutes; 5) Perform constant current discharging (DC) on the single battery cell at a discharging rate of 1.0 times (1.0C) until a known lower limit voltage (for example, 2.5V); 6) Perform constant current discharging (DC) on the single battery cell at a discharging rate of 0.05 times (0.05C) until 0.5V.

[0118] In the process of performing an acceleration test on the test battery based on the acceleration standard potential and the SOC reference value, the following process may be adopted: 1) Let the test battery stand still for 10 minutes; 2) Perform constant current charging (CC) on the test battery at a charging rate of 1.0 times (1.0C) of a single battery cell in the test battery, and the charging duration is x hours, where x = 1h*S x , S xrepresent the SOC reference value as described above; 3) Let the test battery stand still for 10 minutes; 4) Perform constant current discharge (DC) on the test battery at a discharge rate of 1.0 times that of a single battery cell in the test battery (1.0C), and the discharge cut-off voltage is 2.5V*y, where y represents the number of battery cells connected in series in the test battery. 5) Let the test battery stand still for 5 minutes; 6) Perform constant current discharge (DC) on the test battery at a discharge rate of 0.05 times that of a single battery cell in the test battery (0.05C), and the discharge cut-off voltage is V0*y, where V0 represents the acceleration standard potential as described above, and y represents the number of battery cells connected in series in the test battery. 7) Let the test battery stand still for 5 minutes; 8) Repeat steps 2 to 7, for example, 3000 to 7000 cycles or until the battery capacity drops to 60%.

[0119] When the SOH drops from 100% to 80%, the accelerated test method according to the embodiment of the present application can take 45 days, saving about 80% of the evaluation period compared with the 280 days of the normal test method, and the authenticity can reach more than 95%.

[0120] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be covered by the scope of the claims and the description of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. An accelerated test method for a battery, the battery comprising a plurality of battery cells, characterized in that, Including: Based on a single battery cell among the multiple battery cells, calibrating an acceleration standard potential and a state of charge (SOC) reference value for the acceleration test; Obtaining a test battery based on the battery, the test battery including a pressure sensing device; And Based on the acceleration standard potential and the SOC reference value, performing the acceleration test on the test battery.

2. The method according to claim 1, wherein The calibrating the acceleration standard potential for the acceleration test based on a single battery cell among the multiple battery cells includes: Performing a charging operation and a discharging operation on the single battery cell in sequence, wherein, during the discharging operation, discharging data of the single battery cell is collected, the discharging data including a full cell potential and a discharging capacity collected at a predetermined time interval; and Based on the discharging data, determining the acceleration standard potential.

3. The method according to claim 2, wherein The determining the acceleration standard potential based on the discharging data includes: Obtaining a first curve graph of the differential potential varying with the full cell potential, wherein the differential potential is obtained by calculating the ratio of the difference in the full cell potential and the difference in the discharging capacity at two adjacent moments with the predetermined time interval; and Determining the full cell potential corresponding to the disappearance of the peak value of the differential potential in the first curve graph as the acceleration standard potential.

4. The method according to claim 2 or 3, characterized in that, The calibrating the SOC reference value for the acceleration test based on a single battery cell among the multiple battery cells includes: Obtaining a second curve graph of the swelling force of the single battery cell varying with the SOC during the charging operation and the discharging operation; and Determining the SOC corresponding to the first peak value of the swelling force in the second curve graph as the SOC reference value.

5. The method according to any one of claims 1 to 4, characterized in that The performing the acceleration test on the test battery based on the acceleration standard potential and the SOC reference value includes: Performing a charging operation and a discharging operation on the test battery in sequence, wherein the charging duration of the charging operation is determined based on the SOC reference value, and the discharging potential of the discharging operation is determined based on the acceleration standard potential.

6. The method according to claim 5, characterized in that The charging duration of the charging operation is the product of the unit hour and the SOC reference value.

7. The method according to claim 5 or 6, characterized in that The obtaining the test battery based on the battery includes: Replacing at least one battery cell at a predetermined position among the multiple battery cells with the pressure sensing device, wherein the pressure sensing device includes a pressure sensor and support members on both sides of the pressure sensor.

8. The method according to claim 7, wherein The obtaining the test battery based on the battery further includes: Electrically connecting the remaining battery cells among the multiple battery cells except the at least one battery cell at the predetermined position.

9. The method according to claim 8, wherein The electrical connection includes series connection, and the discharging operation includes at least two discharging stages, and the discharging potential in each discharging stage is the product of a predetermined discharging cut-off voltage and the number of the remaining battery cells connected in series.

10. The method according to claim 9, wherein The predetermined discharging cut-off voltage in the last discharging stage of the at least two discharging stages is the acceleration standard potential.

11. The method according to any one of claims 1 to 10, characterized in that, The method further includes: Obtain a third curve graph of the swelling force of the test battery varying with the state of health (SOH) during the accelerated test process and the normal test process respectively, where the third curve graph includes a first sub-curve corresponding to the accelerated test and a second sub-curve corresponding to the normal test; and Based on the comparison between the first sub-curve and the second sub-curve, determine whether the result of the accelerated test is credible.

12. The method according to claim 11, wherein The determining whether the result of the accelerated test is credible based on the comparison between the first sub-curve and the second sub-curve includes: Perform linear fitting on the first sub-curve and the second sub-curve respectively to obtain a first fitting slope and a second fitting slope; Determine the deviation between the first fitting slope and the second fitting slope; Determine whether the deviation meets a predetermined condition; and In response to determining that the deviation meets the predetermined condition, determine that the result of the accelerated test is credible.

13. A battery, characterized in that, The battery is subjected to an accelerated test according to the method of any one of claims 1 to 12.

14. An electrical device, characterized in that, Comprises a battery according to claim 13, the battery being used to provide electrical energy.

Images