Battery negative electrode stability estimation method and battery system using the same

Abstract

To provide a battery negative electrode stability estimation method and a battery system using the same that can determine only the deterioration of the negative electrode separately from the deterioration of a positive electrode, and can grasp the deterioration state of the negative electrode, including the effect of increased resistance of the negative electrode, using charge / discharge voltage data.SOLUTION: A negative electrode stability estimation method includes the steps of receiving first charging data for at least one cell from a voltage sensor, receiving second charging data for at least one cell from the voltage sensor, and estimating negative electrode stability for the at least one cell on the basis of the first charging data and the second charging data, and the first charging data and the second charging data may have different charging rates (C-rates).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for estimating the negative electrode stability of a battery and a battery system using the same, and more particularly to a method for estimating the negative electrode stability of a battery based on battery charging data and a battery system using the same. [Background technology]

[0002] Unlike primary batteries, which cannot be recharged, secondary batteries are batteries that can be charged and discharged. Low-capacity secondary batteries are used in small portable electronic devices such as smartphones, feature phones, laptop computers, digital cameras, and camcorders, while high-capacity secondary batteries are widely used as motor drive power sources and power storage batteries in hybrid vehicles, electric vehicles, and the like. Such secondary batteries include an electrode assembly consisting of a positive electrode and a negative electrode, a case that houses the electrode assembly, and electrode terminals connected to the electrode assembly.

[0003] With the demand for higher energy and faster charging speeds for batteries, including secondary batteries, safety issues are becoming increasingly important. In particular, deterioration due to lithium metal deposition at the negative electrode of a battery is the primary cause of fire and is related to the deterioration state of the negative electrode. Understanding the deterioration state of the negative electrode in a battery is important for optimal battery performance and battery reuse.

[0004] It is extremely important to non-destructively diagnose the internal state of a battery in order to understand the deterioration state of the negative electrode. While charge / discharge voltage data can be used to diagnose the internal state of a battery, it is difficult to determine the deterioration of the negative electrode alone, separate it from the deterioration of the positive electrode. Furthermore, it is difficult to understand the deterioration state of the negative electrode, including the effect of the increase in the resistance of the negative electrode, as well as the decrease in capacity of the negative electrode, using charge / discharge voltage data.

[0005] The foregoing information disclosed in this Background of the Invention section is intended solely to enhance understanding of the background of the present invention and may therefore include information that does not constitute prior art. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Korean Patent Publication No. 10-2022-0021730 Summary of the Invention [Problem to be solved by the invention]

[0007] The present disclosure provides a method for estimating the negative electrode stability of a battery to solve the above problem, and a battery system using the same.

[0008] However, the technical problems that the present invention aims to solve are not limited to the problems mentioned above, and problems not mentioned or other problems should be clearly understood by those skilled in the art from the description of the invention described below. [Means for solving the problem]

[0009] According to one embodiment of the present disclosure for solving the technical problem, a method for estimating negative electrode stability includes the steps of receiving first charging data for at least one cell from a voltage sensor, receiving second charging data for at least one cell from the voltage sensor, and estimating negative electrode stability for the at least one cell based on the first charging data and the second charging data, wherein the first charging data and the second charging data may have different charging rates (C-rates).

[0010] According to one embodiment of the present disclosure, the first charging data may include first charging voltage data according to a charge capacity obtained by charging the at least one cell at a first charging rate, and the second charging data may include second charging voltage data according to a charge capacity obtained by charging the at least one cell at a second charging rate.

[0011] According to one embodiment of the present disclosure, the first charging data and the second charging data can be generated by charging at least one cell when the State of Charge (SoC) of the at least one cell is below an SoC threshold.

[0012] According to one embodiment of the present disclosure, the first charging rate may be slower than the second charging rate, and the second charging rate may be less than or equal to a predetermined threshold.

[0013] According to an embodiment of the present disclosure, the method may further include calculating first differential voltage data for the first charging voltage data, and calculating second differential voltage data for the second charging voltage data.

[0014] According to one embodiment of the present disclosure, the first differential voltage data may include a peak charge capacity of 1_1 and a peak charge capacity of 1_2, the second differential voltage data may include a second peak charge capacity, the peak charge capacity of 1_1 may be included in a first charge region, and the peak charge capacity of 1_2 and the second peak charge capacity may be included in a second charge region.

[0015] According to one embodiment of the present disclosure, the step of estimating the negative electrode stability for at least one cell may include the step of estimating the negative electrode stability based on the first peak charge capacity, the first peak charge capacity, and the second peak charge capacity.

[0016] According to one embodiment of the present disclosure, the step of estimating the negative electrode stability for at least one cell may include a step of calculating a peak change amount based on the first_2 peak charge capacity and the second peak charge capacity, and a step of estimating the negative electrode stability based on the peak change amount, the first_1 peak charge capacity, and the first_2 peak charge capacity.

[0017] According to one embodiment of the present disclosure, the at least one cell is a lithium secondary battery, and the peak change amount may be related to the degree of lithium deposition in a negative electrode included in the at least one cell.

[0018] According to one embodiment of the present disclosure, the method may further include receiving third charging data associated with an early stage of battery life (BoL: Beginning of Life) of the at least one cell, and the step of estimating negative electrode stability for the at least one cell may include estimating negative electrode stability for the at least one cell based on the first charging data to the third charging data.

[0019] According to one embodiment of the present disclosure, the step of estimating negative electrode stability for at least one cell based on the first to third charging data may include the steps of calculating a negative electrode health for at least one cell based on the first charging data and the second charging data, calculating a reference negative electrode health associated with the BoL of the at least one cell based on the third charging data, and estimating the negative electrode stability based on the negative electrode health and the reference negative electrode health.

[0020] According to one embodiment of the present disclosure, the first charging data includes first charging voltage data according to a charging capacity obtained by charging at least one cell at a first charging rate, the second charging data includes second charging voltage data according to a charging capacity obtained by charging at least one cell at a second charging rate, and the third charging data includes third charging voltage data according to a charging capacity obtained by charging at least one cell associated with a BoL, and the method includes the steps of calculating first differential voltage data for the first charging voltage data and calculating second differential voltage data for the second charging voltage data. The method may further include a step of calculating differential voltage data and a step of calculating third differential voltage data for the third charging voltage data, wherein the first differential voltage data includes the peak charging capacity of 1_1 and the peak charging capacity of 1_2, the second differential voltage data includes the second peak charging capacity, and the third differential voltage data includes the peak charging capacity of 3_1 and the peak charging capacity of 3_2, and the peak charging capacity of 1_1 and the peak charging capacity of 3_1 may be included in the first charging region, and the peak charging capacity of 1_2, the second peak charging capacity and the peak charging capacity of 3_2 may be included in the second charging region.

[0021] According to one embodiment of the present disclosure, the step of estimating the negative electrode stability for at least one cell based on the first charging data to the third charging data may include the step of estimating the negative electrode stability for at least one cell based on the first_1 peak charging capacity to the third_2 peak charging capacity.

[0022] According to one embodiment of the present disclosure, charging of at least one cell is performed until the at least one cell is fully charged, the first charging data includes a fully charged state charge capacity associated with the first charging data, and the step of estimating negative electrode stability for the at least one cell based on the first to third charging data may include a step of estimating negative electrode stability for the at least one cell based on the fully charged state charge capacity associated with the first charging data and the first_1 peak charge capacities to the third_2 peak charge capacities.

[0023] According to one embodiment of the present disclosure, negative electrode stability may be related to a decrease in negative electrode capacity and an increase in negative electrode resistance.

[0024] According to an embodiment of the present disclosure, the method may further include adjusting an upper limit of the charge rate of at least one cell based on the estimated negative electrode stability.

[0025] According to one embodiment of the present disclosure, adjusting the upper limit of the charge rate of the at least one cell may include decreasing the upper limit of the charge rate in response to determining that the negative electrode stability is less than a stability threshold.

[0026] According to one embodiment of the present disclosure, a battery includes a voltage sensor that measures a voltage according to a charge capacity of at least one cell, and a control unit that receives charge data generated by the voltage sensor and estimates a negative electrode stability for the at least one cell based on the charge data, wherein the charge data includes first charge data for the at least one cell and second charge data for the at least one cell, and the first charge data and the second charge data may have different charge rates.

[0027] According to one embodiment of the present disclosure, the charging data further includes third charging data associated with the BoL of at least one cell, and the control unit calculates a negative electrode health level for at least one cell based on the first charging data and the second charging data, calculates a reference negative electrode health level associated with the BoL of the at least one cell based on the third charging data, and estimates negative electrode stability based on the negative electrode health level and the reference negative electrode health level.

[0028] According to an embodiment of the present disclosure, the control unit can adjust the upper limit of the charge rate of at least one cell based on the estimated negative electrode stability. [Effects of the Invention]

[0029] According to various embodiments of the present disclosure, the adjusted charging rate can reduce the risk of lithium deposition in the battery cell, and can also reduce the rate of deterioration of the negative electrode caused by repeated charging and discharging of the battery cell, thereby reducing the rate of reduction in the lifespan of the battery cell.

[0030] According to various embodiments of the present disclosure, negative electrode stability can be a criterion for determining not only the degree of a decrease in negative electrode capacity but also the degree of an increase in negative electrode resistance. Because deterioration of a negative electrode plate induces a decrease in negative electrode capacity and an increase in negative electrode resistance, negative electrode stability can effectively indicate the degree of deterioration of a negative electrode plate.

[0031] According to various embodiments of the present disclosure, it may be easy to use the negative electrode stability estimation method according to the present disclosure in that the state of the negative electrode can be determined using data related to a full cell that is being charged.

[0032] According to various embodiments of the present disclosure, the negative electrode stability estimation method can be applied to battery cells regardless of the material of the positive electrode, and therefore, the negative electrode stability estimation method can be highly versatile for secondary batteries.

[0033] However, the effects obtained by the present invention are not limited to the effects described above, and other technical effects not mentioned herein should be clearly understood by those skilled in the art from the description of the invention described below. [Brief explanation of the drawings]

[0034] The following drawings and the like attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention to be given later, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be analyzed by being limited to the matters depicted in such drawings. [Figure 1] 1 is a schematic diagram showing a battery system according to an embodiment of the present invention; [Figure 2] FIG. 2 is a block diagram showing an internal configuration of a control unit according to an embodiment of the present disclosure. [Figure 3]FIG. 10 shows example charging voltage data for a negative electrode half-cell according to one embodiment of the present disclosure. [Figure 4] FIG. 10 illustrates example differential voltage data for a negative electrode half-cell according to one embodiment of the present disclosure. [Figure 5] 1 is a graph showing an example of the relationship between peak charge capacity and the length of the precipitation danger zone for a negative electrode half-cell according to one embodiment of the present disclosure. [Figure 6] 10 is a graph showing an example of differential voltage data for a full cell according to one embodiment of the present disclosure. [Figure 7] 10 is a graph showing an example of differential voltage data for a full cell according to one embodiment of the present disclosure. [Figure 8] 10 is a graph showing an example of differential voltage data for a full cell according to another embodiment of the present disclosure. [Figure 9] 10 is a graph showing example differential voltage data of a full cell according to still another embodiment of the present disclosure. [Figure 10] 1 is a flowchart illustrating an example of a negative electrode stability estimation method according to an embodiment of the present disclosure. [Figure 11] 10 is a flowchart illustrating an example of steps for estimating negative electrode stability for at least one cell according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0035] Preferred embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. First, the terms and phrases used in this specification and claims should not be interpreted in a limited manner based on their ordinary and dictionary meanings, but should be interpreted in a manner consistent with the technical concept of the present invention, based on the principle that the inventor may appropriately define the concepts of terms in order to best describe his or her invention. Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely preferred embodiments of the present invention and do not represent the entire technical concept of the present invention, and that various equivalents and modifications may exist as of the time of filing this application.

[0036] Furthermore, as used herein, "comprise," "comprising," "include," and "including" specify the presence of a stated shape, number, step, operation, member, element, and / or group, but do not exclude the presence or addition of one or more other shapes, numbers, operations, members, elements, and / or groups. Furthermore, when describing an embodiment of the present invention, "may" and "may be" can include "one or more embodiments of the present invention."

[0037] In order to facilitate understanding of the invention, the accompanying drawings may not be drawn to scale, and the dimensions of some components may be exaggerated. In addition, the same reference numerals are used to refer to the same components in different embodiments.

[0038] A statement that two comparison objects are "identical" means that they are "substantially identical." Therefore, being substantially identical can include cases where there is a deviation that is considered low in the art, for example, a deviation of 5% or less. Furthermore, a statement that a certain parameter is uniform in a given region can mean that the parameter is uniform on average.

[0039] Although terms such as "first" and "second" are used to describe various components, it is understood that these components are not limited by these terms. These terms are merely used to distinguish one component from another, and unless otherwise specified, a first component can be a second component.

[0040] Throughout the specification, unless specifically stated to the contrary, each element may be singular or plural.

[0041] The phrase "above (or below)" a component or "above (or below)" a component means that the component is not only placed in contact with the upper surface (or lower surface) of the component, but also means that other components may be interposed between the component and the component placed above (or below) the component.

[0042] Furthermore, when a component is described as being "coupled," "coupled," or "connected" to another component, it should be understood that the components may be directly coupled or connected to each other, but that other components may be "intervening" between the components, or that each component may be "coupled," "coupled," or "connected" via other components.

[0043] Furthermore, when a part is said to be electrically coupled to another part, this includes not only a direct connection but also a connection via another element therebetween.

[0044] Throughout the specification, "A and / or B" means A, B, or A and B, unless expressly stated to the contrary. That is, "and / or" includes all or any combination of the listed items. "C through D" means at least C and at most D, unless expressly stated to the contrary.

[0045] FIG. 1 is a schematic diagram illustrating a battery system 120 according to one embodiment of the present invention. A battery cell 110 (hereinafter referred to as a "cell") can be charged via a charging device 130. For example, the cell 110 can be disposed within an electronic device and charged via a charging device included in the electronic device or via an external charging device. Referring to FIG. 1, the cell 110 is shown connected only to the charging device 130 and the battery system 120, but this is not limiting. For example, the cell 110 may be electrically connected to an external component. The cell 110 may supply power to the external component while charging, or may supply power to the external component after charging is completed. As another example, the cell 110 may be electrically connected to another external component after being separated from the battery system 120 and the charging device 130.

[0046] The charging device 130 can charge the cell 110 at different charging rates (C-rates). Here, the charging rate can be a value obtained by dividing the magnitude of the battery's charging current by the rated capacity of the battery. For example, the charging device 130 can charge the cell 110 at a first charging rate. As another example, the charging device 130 can charge the cell 110 at a second charging rate that is different from the first charging rate. For example, the first charging rate is slower than the second charging rate.

[0047] In one embodiment, the second charge rate may be less than or equal to a predetermined threshold, where the threshold may be less than or equal to 0.33 C, where C is a unit of charge rate, meaning a charge rate that takes a certain amount of time (e.g., 10 hours) to fully charge the cell.

[0048] The battery system 120 may include a voltage sensor 122 and a controller 124. When the cell 110 is charged via the charging device 130, the voltage sensor 122 may generate charging data for the cell 110. The generated charging data may be transferred to the controller 124.

[0049] The control unit 124 may receive charging data generated from the voltage sensor 122. The charging data may include charging voltage data according to the charging capacity obtained by charging the cell 110. The control unit 124 may calculate differential voltage data based on the charging voltage data. The control unit 124 may calculate a peak charging capacity based on the differential voltage data. In one embodiment, the charging data may include differential voltage data, which may include a peak charging capacity. However, in the following description, the control unit 124 calculates the differential voltage data based on the charging voltage data included in the charging data and calculates the peak charging capacity based on the differential voltage data, but this is not limited thereto. For example, at least one processor included in the battery system 120 may calculate the differential voltage data and calculate the peak charging capacity.

[0050] In one embodiment, the charge data is obtained by charging the cell 110 to a fully charged state. The charge data may include a fully charged state charge capacity of the cell 110 obtained by charging the cell 110 to a fully charged state. Additionally, the charge data may be obtained by charging the cell 110 below a State of Charge (SoC) threshold. For example, the SoC threshold may be a value between 0% and 40%. For example, the SoC threshold may be 25%. However, the SoC threshold is not limited thereto, and an appropriate value may be used as a default value to ensure sufficient charge data.

[0051] In one embodiment, the cell 110 may be a battery cell corresponding to the middle of life (MoL). The cell 110 may be a battery whose lifespan has been reduced by repeated charging and discharging. For example, the state of health (SoH) of the cell 110 may be approximately 99% or less. However, without being limited thereto, the cell 110 may be a cell immediately after manufacture that has been charged and discharged one or more times.

[0052] In another embodiment, the cell 110 may be a battery cell that is in the beginning of life (BoL). The cell 110 may be a battery immediately after manufacture. For example, the State of Health (SoH) of the cell 110 may be approximately 100%. In still another embodiment, the cell 110 may be a battery whose voltage is first measured by the voltage sensor 122. That is, the cell 110 may be in a state before the life of the cell is reduced by the charging device 130.

[0053] In one embodiment, the first charging data may include first charging voltage data according to a charge capacity obtained by charging the cell 110 corresponding to the MoL at a first charging rate, the second charging data may include second charging voltage data according to a charge capacity obtained by charging the cell 110 corresponding to the MoL at a second charging rate, and the third charging data may include third charging voltage data according to a charge capacity obtained by charging the cell 110 corresponding to the BoL.

[0054] In one embodiment, the control unit 124 may calculate the negative electrode health state based on the peak charge capacity. The control unit 124 may also calculate a reference negative electrode health state based on the peak charge capacity associated with the BoL. The control unit 124 may estimate the negative electrode stability of the cell 110 based on the negative electrode health state and the reference negative electrode health state.

[0055] The charging device 130 and the control unit 124 can communicate with each other. The control unit 124 can also adjust the charging rate of the charging device 130. In one embodiment, the control unit 124 can adjust the upper limit of the charging rate of the cell 110 based on the negative electrode stability. For example, the control unit 124 can reduce the upper limit of the charging rate of the cell 110 charged by the charging device 130 in response to determining that the negative electrode stability is below the stability threshold.

[0056] 1, one cell 110 is shown, but the present invention is not limited thereto. For example, a plurality of cells may be charged by the charging device 130, and charging data may be generated by the voltage sensor 122. In one embodiment, the plurality of cells may be battery cells corresponding to the BoL. In another embodiment, the plurality of cells may be battery cells corresponding to the MoL that have been charged and discharged one or more times in the BoL state.

[0057] The lifespan of the cell 110 decreases as the cell is repeatedly charged and discharged. Specifically, the negative electrode included in the cell 110 may deteriorate due to repeated charging and discharging. The more the negative electrode of the cell deteriorates, the greater the risk of lithium precipitation. Furthermore, the faster the cell is charged, the greater the risk of lithium precipitation. This will be described in detail with reference to FIGS. 3 to 5.

[0058] As described above, the negative electrode stability estimation method according to the present disclosure estimates the negative electrode stability of the cell 110 and compares the negative electrode stability with a predetermined threshold value, thereby adjusting the charge rate of the cell 110. The adjusted charge rate can reduce the risk of lithium deposition in the cell 110. It can also reduce the rate of deterioration of the negative electrode that occurs due to repeated charging and discharging of the cell 110, thereby reducing the rate at which the lifespan of the cell 110 decreases.

[0059] 2 is a block diagram showing an internal configuration of a control unit 200 according to an embodiment of the present disclosure. The control unit 200 may include a charge data receiving unit 210, a negative electrode health degree calculating unit 220, a reference negative electrode health degree calculating unit 230, a negative electrode stability estimating unit 240, and a charging rate adjusting unit 250. For example, the control unit 200 may be the control unit 124 included in the battery system 120 of FIG. 1.

[0060] The charging data receiving unit 210 can receive charging data from a voltage sensor (e.g., voltage sensor 122 in FIG. 1). For example, the charging data receiving unit 210 can receive first charging data associated with a first charging rate and second charging data associated with a second charging rate from the voltage sensor. Additionally, the charging data receiving unit 210 can receive third charging data associated with the BoL of at least one cell (e.g., cell 110 in FIG. 1).

[0061] In one embodiment, the first charging data may include first charging voltage data according to a charge capacity obtained by charging at least one cell at a first charging rate, the second charging data may include second charging voltage data according to a charge capacity obtained by charging at least one cell at a second charging rate, and the third charging data may include third charging voltage data according to a charge capacity obtained by charging at least one cell corresponding to the BoL.

[0062] In one embodiment, the negative electrode health degree calculation unit 220 can calculate differential voltage data for the charging voltage data included in the charging data. Specifically, the negative electrode health degree calculation unit 220 can calculate the differential voltage data for the charging voltage data by differentiating the charging voltage data. For example, the negative electrode health degree calculation unit 220 can calculate first differential voltage data for the first charging voltage data and second differential voltage data for the second charging voltage data.

[0063] The negative electrode health degree calculation unit 220 can calculate the peak charge capacity based on the differential voltage data. For example, the negative electrode health degree calculation unit 220 can calculate the first_1 peak charge capacity and the first_2 peak charge capacity based on the first differential voltage data. The peak charge capacity will be described in detail with reference to Figs. 3 to 7.

[0064] In one embodiment, the negative electrode health calculator 220 may calculate the negative electrode health of at least one cell based on the first charge data and the second charge data. For example, the negative electrode health may be calculated based on a peak charge capacity associated with the first charge data and a peak charge capacity associated with the second charge data. The process of calculating the negative electrode health based on the peak charge capacity will be described in detail with reference to FIGS. 6 and 7.

[0065] In one embodiment, similar to the negative electrode health degree calculation unit 220, the reference negative electrode health degree calculation unit 230 can calculate third differential voltage data for third charge data related to the BoL of at least one cell. The reference negative electrode health degree calculation unit 230 can also calculate a third_1 peak charge capacity and a third_2 peak charge capacity based on the third differential voltage data. The reference negative electrode health degree calculation unit 230 can also calculate a reference negative electrode health degree based on the third_1 peak charge capacity and the third_2 peak charge capacity.

[0066] In one embodiment, a voltage sensor (e.g., voltage sensor 122 of FIG. 1) obtains a fully charged state charge capacity by charging at least one cell until it reaches a fully charged state. The charging data includes the fully charged state charge capacity, and the charging data receiving unit 210 can receive the charging data including the fully charged state charge capacity. The negative electrode health calculation unit 220 can calculate the negative electrode health for at least one cell based on the fully charged state charge capacity of the at least one cell corresponding to the MoL and the peak capacity associated with the MoL of the at least one cell. Similarly, the reference negative electrode health calculation unit 230 can calculate the negative electrode health for at least one cell based on the fully charged state charge capacity of the at least one cell corresponding to the BoL and the peak capacity associated with the BoL of the at least one cell.

[0067] In one embodiment, the negative electrode stability estimation unit 240 can estimate the negative electrode stability based on the negative electrode health degree and the reference negative electrode health degree. Specifically, the negative electrode stability estimation unit 240 can estimate the negative electrode stability by comparing the negative electrode health degree with the reference negative electrode health degree. For example, the negative electrode stability may be a value obtained by dividing the negative electrode health degree by the reference negative electrode health degree. A specific process for calculating the negative electrode stability will be described in detail with reference to FIGS. 6 and 7.

[0068] In one embodiment, the charge rate adjustment unit 250 can adjust the charge rate of the charging device that charges at least one cell based on the negative electrode stability. For example, the charge rate adjustment unit 250 can determine whether the estimated negative electrode stability is less than a stability threshold. The charge rate adjustment unit 250 can reduce the upper limit of the charge rate of the charging device in response to determining that the estimated negative electrode stability is less than the stability threshold. For example, the stability threshold can be approximately 80%. If the estimated negative electrode stability is less than 80%, the charge rate adjustment unit 250 can reduce the upper limit of the charge rate (or the charge rate) so that the negative electrode stability is 80% or greater.

[0069] In one embodiment, the control unit 200 may include a memory and a processor. The memory may include any non-transitory computer-readable recording medium. According to one embodiment, the memory may include a permanent mass storage device such as a random access memory (RAM), a read only memory (ROM), a disk drive, a solid state drive (SSD), or a flash memory. As another example, a permanent mass storage device such as a ROM, an SSD, a flash memory, or a disk drive may be included in the control unit 200 as a separate permanent storage device. In addition, the memory may store an operating system and at least one program code (e.g., code for estimating anode stability, etc., installed and operated in the control unit 200).

[0070] The processor can be configured to process computer program instructions by performing basic arithmetic, logic, and input / output operations. The instructions can be provided to a charging device (e.g., charging device 130 in FIG. 1 ), an external device, or another external system via a memory or a communication module. For example, the processor can calculate differential voltage data based on the charging voltage data. The processor can calculate peak charge capacity based on the differential voltage data. The processor can estimate negative electrode stability based on the charging data.

[0071] Additionally, the control unit 200 may further include a communication module. The communication module may provide a configuration or function for communication with the charging device, and may provide a configuration or function for the control unit 200 to communicate with an external device, an external system, etc. For example, control signals, instructions, data, etc. provided under the control of the processor of the control unit 200 may be transferred to the charging device, the external device, and / or the external system via the communication module and the communication module of the charging device, the external device, and / or the external system.

[0072] FIG. 3 is a diagram illustrating an example of charging voltage data for a negative electrode half-cell according to an embodiment of the present disclosure. Here, the negative electrode half-cell may be a coin half-cell including graphite as the negative electrode. The maximum charging capacity of the negative electrode half-cell may be 2.4 Ah. The negative electrode half-cell before generating the charging voltage data may be a half-cell corresponding to BoL. For example, the negative electrode half-cell may have undergone an activation process including two charging and discharging cycles at a charging rate of 0.05 C. Here, the negative electrode half-cell refers to a battery cell including only a negative electrode, without a positive electrode.

[0073] The graph shown in FIG. 3 is an example of charging voltage data according to the charge capacity obtained by charging a negative half-cell. Specifically, multiple charging voltage data 310-330 are obtained by varying the charging rate. For example, the first charging voltage data 310 may be charging voltage data according to the charge capacity obtained by charging the negative half-cell at a charging rate of 0.1 C. The second charging voltage data 320 may be charging voltage data according to the charge capacity obtained by charging the negative half-cell at a charging rate of 0.1 C to 1 C. Here, the second charging voltage may be higher than the first charging voltage. The third charging voltage data 330 may be charging voltage data according to the charge capacity obtained by charging at a charging rate of 1 C. Referring to FIG. 3, the charging rate associated with the charging voltage data may increase in the direction of A.

[0074] The negative half cell can be charged up to a predetermined voltage, not below 0V. Referring to Figure 3, it can be seen that it is charged to a predetermined voltage. The negative electrode included in the full cell can be charged below 0V, but may not be charged to 0V due to the characteristics of the half cell. Here, a full cell refers to a single battery cell including a positive electrode and a negative electrode.

[0075] The fully charged state charge capacity of the first charging voltage data 310 can be the same as or closest to the maximum charge capacity of the negative electrode half-cell. For example, the fully charged state charge capacity of the first charging voltage data 310 can be approximately 2.4 Ah. The fully charged state charge capacities of the second charging voltage data 320 and the third charging voltage data 330 can be smaller than the fully charged state charge capacity of the first charging voltage data 310.

[0076] In this case, the greater the difference between the fully charged state charge capacity of the nth charging voltage data (where n is a natural number greater than or equal to 2) and the fully charged state charge capacity of the first charging voltage data 310, the greater the risk of lithium precipitation in the negative electrode of a cell charged at a charging rate associated with the nth charging voltage data. For example, the difference (D2) between the fully charged state charge capacity of the third charging voltage data and the fully charged state charge capacity of the first charging voltage data may be greater than the difference (D1) between the fully charged state charge capacity of the second charging voltage data and the fully charged state charge capacity of the first charging voltage data. In this case, the cell charged at the charging rate associated with the third charging voltage data may be at a greater risk of lithium precipitation than a cell charged at a charging rate associated with the second charging voltage data. Here, the difference between the fully charged state charge capacity of the nth charging voltage data and the fully charged state charge capacity of the first charging voltage data 310 may be referred to as the length of the precipitation risk zone.

[0077] 4 is a diagram illustrating an example of differential voltage data of a negative electrode half-cell according to one embodiment of the present disclosure. Specifically, FIG. 4 may illustrate differential voltage data for the plurality of charging voltage data 310 to 330 shown in FIG.

[0078] 4, the charge rate associated with the differential voltage data may be faster in the direction A. For example, the charge rate of the negative half-cell corresponding to the first differential voltage data 410 is slower than the charge rate of the negative half-cell corresponding to the second differential voltage data 420. For example, the charge rate of the negative half-cell corresponding to the first differential voltage data 410 may be 0.1 C. Also, the charge rate of the negative half-cell corresponding to the second differential voltage data 420 may be 1 C.

[0079] Each of the plurality of differential voltage data may include a plurality of peaks. For example, the Tth differential voltage data included in the plurality of differential voltage data may include a T_1 peak and a T_2 peak (for example, T is a natural number equal to or greater than 1). In this case, the T_1 peak may include a T_1 peak charge capacity corresponding to the T_1 peak. The T_2 peak may include a T_2 peak charge capacity corresponding to the T_2 peak.

[0080] In FIG. 4 , when the charge capacity is less than 0.5 Ah, a peak may be formed for each of the plurality of differential voltage data. As shown in FIG. 4 , a downwardly convex portion of the graph corresponds to the peak. However, this is not limited thereto, and when the differential voltage data is expressed as an absolute value, an upwardly convex portion of the graph may correspond to the peak. The plurality of peaks may be associated with the T_1 peak for each of the plurality of differential voltage data. In FIG. 4 , when the charge capacity is between 1.0 Ah and 1.5 Ah, a peak may be formed for each of the plurality of differential voltage data. The plurality of peaks may be associated with the T_2 peak for each of the plurality of differential voltage data.

[0081] In one embodiment, the peak charge capacity at T_1 may be included in the first charge range. The peak charge capacity at T_2 may be included in the second charge range. The first charge range may be determined to include a charge capacity where the SoC of the cell being measured is 25%. For example, the first charge range may be a range where the SoC of the cell being measured is 15% to 35%. The second charge range may be determined to include a charge capacity where the SoC of the cell being measured is 50%. For example, the second charge range may be a range where the SoC of the cell being measured is 40% to 60%.

[0082] In one embodiment, when multiple peaks are formed in one charge range for one differential voltage data, the peak corresponding to the peak charge capacity closest to the reference value for that charge range can be selected. For example, the reference value for a first charge range can be 25% of the cell being measured. The reference value for a second charge range can be 50% of the cell being measured.

[0083] As shown in FIG. 4 , the first differential voltage data 410 may include a 1_1 peak (not shown) and a 1_2 peak 412. The 1_2 peak 412 may include a 1_2 peak charge capacity. The second differential voltage data 420 may include a 2_1 peak (not shown) and a 2_2 peak 422. The 2_2 peak 422 may include a 2_2 peak charge capacity. For example, the charge rate corresponding to the first differential voltage data 410 is slower than the charge rate corresponding to the second differential voltage data 420. In this case, the 1_2 peak charge capacity is greater than the 2_2 peak charge capacity. As such, as the charge rate increases, the T_2 peak shown in the differential voltage data may shift to the left. Here, the peak change amount refers to the value obtained by subtracting the n_2 peak charge capacity (where n is a natural number greater than or equal to 2) from the 1_2 peak charge capacity.

[0084] The phenomenon of the T_2 peak shifting as the charging rate increases may occur in MoL batteries. In contrast, the phenomenon of the T_2 peak shifting as the charging rate increases may not occur in BoL batteries. Alternatively, the degree of the T_2 peak shifting in BoL batteries may be relatively smaller than the degree of the shifting in MoL batteries. Therefore, the phenomenon of the T_2 peak shifting in BoL batteries is negligible.

[0085] 5 is a graph showing an example of the relationship between the peak charge capacity and the length of the precipitation risk zone for a negative electrode half-cell according to one embodiment of the present disclosure. The Y axis of FIG. 5 may represent the length of the precipitation risk zone versus the charge voltage data for the negative electrode half-cell described with reference to FIG. 3. The X axis of FIG. 5 may represent the T_2 peak charge capacity versus the differential voltage data for the negative electrode half-cell described with reference to FIG. 4.

[0086] The first data 510 may be related to the first charging voltage data 310 of Figure 3 and also related to the first differential voltage data 410 of Figure 4. That is, the first differential voltage data 410 of Figure 4 may be differentiated with respect to the first charging voltage data 310 of Figure 3. The length of the precipitation danger zone included in the first data 510 may be approximately 0 Ah, and the peak charge capacity included in the first data 510 may be approximately 1.2 Ah.

[0087] The second data 520 may be related to the second charging voltage data 320 of Figure 3 and also related to the second differential voltage data 420 of Figure 4. That is, the second differential voltage data 420 of Figure 4 may be differentiated with respect to the second charging voltage data 320 of Figure 3. The length of the precipitation danger zone included in the second data 520 may be approximately 0.73 Ah, and the peak charge capacity included in the second data 520 may be approximately 1.05 Ah.

[0088] 5 may be correlated with the charging speed. For example, the charging speed of each of the plurality of data increases in the direction A. For example, the charging speed corresponding to the first data 510 is slower than the charging speed corresponding to the second data 520.

[0089] As shown in FIG. 5, as the charge rate increases, the peak charge capacity may decrease. As the peak charge capacity decreases, the length of the precipitation risk period may increase. In other words, the greater the peak change amount described with reference to FIG. 4, the greater the risk of lithium precipitation. Furthermore, as the charge rate increases, the risk of lithium precipitation may increase. Therefore, it may be necessary to adjust the charge rate of the cell to prevent lithium precipitation.

[0090] 6 and 7 are graphs showing example differential voltage data of a full cell according to an embodiment of the present disclosure. The graphs of FIGS. 6 and 7 show the differential voltage data as absolute values.

[0091] A full cell may be a battery cell including a positive electrode and a negative electrode. The positive electrode of the full cell includes NCA with 88% Ni, and the negative electrode of the full cell may include graphite and silicon. In Figures 6 and 7, MoL refers to the state after 60 charge-discharge cycles, in which the battery is charged at a charge rate of 3 C and discharged at a discharge rate of 0.5 C, immediately after manufacture. The maximum capacity of the full cell may be approximately 3 Ah.

[0092] The first charging voltage data may include a charge capacity obtained by charging a full cell corresponding to the MoL at a first charge rate (e.g., 0.05 C). The first differential voltage data 610 may be obtained by differentiating the first charging voltage data. The first charging voltage data may include a fully charged state charge capacity 616 of the full cell corresponding to the MoL.

[0093] The second charging voltage data may include a charge capacity obtained by charging a full cell corresponding to the MoL at a second charging rate (e.g., 0.2 C). The second differential voltage data 620 may be obtained by differentiating the second charging voltage data.

[0094] The third charging voltage data may include a charge capacity obtained by charging a full cell corresponding to the BoL at a first charge rate (e.g., 0.05C). The third differential voltage data 630 may be obtained by differentiating the third charging voltage data. The third charging voltage data may include a state-of-full charge capacity 636.

[0095] The fourth charging voltage data may include a charge capacity obtained by charging a full cell corresponding to the BoL at a second charging rate (e.g., 0.2 C). The fourth differential voltage data 640 may be obtained by differentiating the fourth charging voltage data.

[0096] The first differential voltage data 610 may include a 1_1 peak and a 1_2 peak. The first differential voltage data 610 may include a 1_1 peak charge capacity 612 for the 1_1 peak and a 1_2 peak charge capacity 614 for the 1_2 peak.

[0097] The second differential voltage data 620 may include a 2_1 peak and a 2_2 peak. The second differential voltage data 620 may include a 2_1 peak charge capacity relative to the 2_1 peak and a 2_2 peak charge capacity 622 relative to the 2_2 peak.

[0098] The 1_1 peak and the 2_1 peak may be included in the first charge region. For example, the first charge region may be when the SoC of the cell being measured is between 20% and 30%. The 1_2 peak and the 2_2 peak may be included in the second charge region. For example, the second charge region may be when the SoC of the cell being measured is between 45% and 55%.

[0099] The negative electrode health degree can be related to the full cell corresponding to the MoL. The negative electrode health degree can be calculated based on the first_1 peak charge capacity 612, the first_2 peak charge capacity 614, the second_2 peak charge capacity 622, and the fully charged state charge capacity 616 of the full cell corresponding to the MoL. Specifically, the negative electrode health degree can be calculated using the following equation 1.

[0100]

number

[0101] In the above formula (1), X1 may be a value obtained by subtracting the peak charge capacity 612 of the first_1 from the peak charge capacity 614 of the first_2. Y1 may be a value obtained by subtracting the peak charge capacity 612 of the first_1 from the fully charged state charge capacity 616 of the full cell corresponding to the MoL. ΔX may be a value obtained by subtracting the peak charge capacity of the second_2 from the peak charge capacity of the first_2 as the peak change amount. α may be a first proportionality constant that varies depending on the difference between the first charge rate and the second charge rate. β may be a second proportionality constant that varies depending on the material of the negative electrode. For example, if the negative electrode contains graphite, β may be approximately 3.

[0102] In the negative electrode health index, (βX1-Y1) can be related to the increase in the resistance of the negative electrode. In the negative electrode health index, αΔX can be related to the decrease in the capacity of the negative electrode. The decrease in capacity of the negative electrode is related to the degree of lithium deposition, so αΔX can be related to the degree of lithium deposition. In other words, the smaller the calculated negative electrode health index, the greater the increase in the resistance of the negative electrode of the cell. Also, the smaller the calculated negative electrode health index, the greater the decrease in the capacity of the negative electrode of the cell.

[0103] The third differential voltage data 630 may include a 3_1 peak and a 3_2 peak. The third differential voltage data 630 may include a 3_1 peak charge capacity 632 relative to the 3_1 peak and a 3_2 peak charge capacity 634 relative to the 3_2 peak.

[0104] The fourth differential voltage data 640 may include a 4_1 peak and a 4_2 peak. The fourth differential voltage data 640 may include a 4_1 peak charge capacity relative to the 4_1 peak and a 4_2 peak charge capacity relative to the 4_2 peak.

[0105] The 3_1 peak and the 4_1 peak may be included in the first charge region. The 3_2 peak and the 4_2 peak may be included in the second charge region. The 3_1 peak charge capacity may be the same as or similar to the 4_1 peak charge capacity. Similarly, the 3_2 peak charge capacity may be the same as or similar to the 4_2 peak charge capacity. That is, a full cell that falls into the BoL state does not experience any peak shift and / or peak change because no deterioration of the negative electrode occurs. Alternatively, even if deterioration of the negative electrode occurs in a full cell that falls into the BoL state, the peak shift and / or peak change may be very small. Therefore, the peak shift and / or peak change for a full cell that falls into the BoL state may be negligible.

[0106] The reference negative electrode health level may be associated with a full cell corresponding to BoL. The reference negative electrode health level may be calculated based on the 3_1 peak charge capacity 632, the 3_2 peak charge capacity 634, and the fully charged state charge capacity 636 of the full cell corresponding to BoL. Specifically, the reference negative electrode health level may be calculated using the following equation 2.

[0107]

number

[0108] In the above formula 2, X2 may be a value obtained by subtracting the peak charge capacity 632 of the 3_1 from the peak charge capacity 634 of the 3_2. Y2 may be a value obtained by subtracting the peak charge capacity 632 of the 3_1 from the fully charged state charge capacity 636 of the full cell corresponding to BoL.

[0109] The negative electrode stability can be calculated based on the negative electrode health degree and the reference negative electrode health degree. Specifically, the negative electrode stability can be calculated by comparing the negative electrode health degree and the reference negative electrode health degree. For example, the negative electrode stability (%) can be calculated as follows: negative electrode health degree / reference negative electrode health degree×100. That is, the negative electrode stability can be calculated using the following formula 3.

[0110]

number

[0111] The negative electrode stability may be a value calculated by comparing a reference negative electrode health level associated with a battery cell corresponding to the BoL with a negative electrode health level associated with a battery cell corresponding to the MoL. The negative electrode stability may indicate both the degree of increase in negative electrode resistance and the degree of decrease in negative electrode capacity of the battery cell being estimated (e.g., a battery cell corresponding to the MoL). That is, the higher the negative electrode stability, the more stable the battery cell having the corresponding negative electrode stability may be estimated to be.

[0112] As described above, negative electrode stability can be used as a criterion for determining not only the degree of negative electrode capacity reduction but also the degree of negative electrode resistance increase. Since deterioration of a negative electrode plate induces a negative electrode capacity reduction and an increase in negative electrode resistance, negative electrode stability can effectively indicate the degree of deterioration of the negative electrode plate. Furthermore, since the state of the negative electrode can be determined using data related to a full cell during charging, it may be easy to use the negative electrode stability estimation method according to the present disclosure.

[0113] 8 is a graph showing an example of differential voltage data for a full cell according to another embodiment of the present disclosure. The full cell according to this embodiment is similar to the full cell described with reference to FIG. 7 except that it contains LFP as the positive electrode. The maximum capacity of the full cell may vary depending on the material.

[0114] The first charging voltage data may include a charge capacity obtained by charging a full cell corresponding to the MoL at a first charging rate (e.g., 0.05C). The first differential voltage data 810 may be obtained by differentiating the first charging voltage data. The second charging voltage data may include a charge capacity obtained by charging a full cell corresponding to the MoL at a second charging rate (e.g., 0.33C). The second differential voltage data 820 may be obtained by differentiating the second charging voltage data.

[0115] The first differential voltage data 810 may include a first peak. The first differential voltage data 810 may include a first peak charge capacity 812 relative to the first peak. The second differential voltage data 820 may include a second peak. The second differential voltage data 820 may include a second peak charge capacity 822 relative to the second peak. Here, the first peak and the second peak may be included in a charge region (e.g., when the SoC of the cell being measured is between 45% and 55%).

[0116] 8, the faster the charging rate, the smaller the peak charging capacity. Specifically, the first peak charging capacity 812 may be greater than the second peak charging capacity 822. That is, a peak change (ΔX) occurs depending on the charging rate, and the faster the charging rate, the more the peak shifts.

[0117] 9 is a graph showing an example of differential voltage data for a full cell according to another embodiment of the present disclosure. The full cell according to this embodiment is similar to the full cell described with reference to FIG. 7 except that it contains NCM622 as the positive electrode. The maximum capacity of the full cell may vary depending on the material.

[0118] The first charging voltage data may include a charge capacity obtained by charging a full cell corresponding to the MoL at a first charging rate (e.g., 0.05C). The first differential voltage data 910 may be obtained by differentiating the first charging voltage data. The second charging voltage data may include a charge capacity obtained by charging a full cell corresponding to the MoL at a second charging rate (e.g., 0.33C). The second differential voltage data 920 may be obtained by differentiating the second charging voltage data.

[0119] The first differential voltage data 910 may include a first peak. The first differential voltage data 910 may include a first peak charge capacity 912 relative to the first peak. The second differential voltage data 920 may include a second peak. The second differential voltage data 920 may include a second peak charge capacity 922 relative to the second peak. Here, the first peak and the second peak may be included in a charge region (e.g., when the SoC of the cell being measured is between 45% and 55%).

[0120] 9, the faster the charging rate, the smaller the peak charging capacity. Specifically, the first peak charging capacity 912 may be greater than the second peak charging capacity 922. That is, a peak change (ΔX) occurs depending on the charging rate, and the faster the charging rate, the more the peak shifts.

[0121] 8 and 9, a peak change amount may exist even if the material of the positive electrode is changed. The negative electrode stability estimation method according to the present disclosure can be applied to battery cells regardless of the material of the positive electrode. Therefore, the negative electrode stability estimation method according to the present disclosure can be highly versatile for secondary batteries.

[0122] 10 is a flowchart illustrating an example of a method S1000 for estimating negative electrode stability according to an embodiment of the present disclosure. The method S1000 for estimating negative electrode stability can be performed by a battery system. Here, the battery system can include a voltage sensor and a controller. The controller can include at least one processor. The voltage sensor can measure a voltage according to the charge capacity of at least one cell.

[0123] First, the negative electrode stability estimation method S1000 starts by receiving first charge data for at least one cell from a voltage sensor (S1010).

[0124] In one embodiment, the controller may receive second charging data for the at least one cell from the voltage sensor (S1020), where the first charging data and the second charging data may be generated by charging the at least one cell in a state where the State of Charge (SoC) of the at least one cell is less than an SoC threshold.

[0125] In one embodiment, the first charging data can include first charging voltage data according to a charge capacity obtained by charging the at least one cell at a first charging rate, and the second charging data can include second charging voltage data according to a charge capacity obtained by charging the at least one cell at a second charging rate.

[0126] In one embodiment, the controller may estimate negative electrode stability for at least one cell based on the first charging data and the second charging data. Here, the negative electrode stability may be related to a decrease in negative electrode capacity and an increase in negative electrode resistance. For example, the first charging data and the second charging data may have different charging rates (C-rates). The first charging rate may be slower than the second charging rate, and the second charging rate may be equal to or lower than a predetermined threshold.

[0127] In one embodiment, the control unit can calculate first differential voltage data for the first charging voltage data, and can calculate second differential voltage data for the second charging voltage data.

[0128] In one embodiment, the first differential voltage data includes a peak charge capacity of 1_1 and a peak charge capacity of 1_2, the second differential voltage data includes a second peak charge capacity, the peak charge capacity of 1_1 is included in a first charge region, and the peak charge capacity of 1_2 and the second peak charge capacity are included in a second charge region.

[0129] In one embodiment, the control unit can estimate the negative electrode stability based on the first peak charge capacity, the first peak charge capacity, and the second peak charge capacity. For example, the control unit can calculate the peak change amount based on the first peak charge capacity and the second peak charge capacity. Furthermore, the control unit can estimate the negative electrode stability based on the peak change amount, the first peak charge capacity, and the first peak charge capacity.

[0130] In one embodiment, the at least one cell is a lithium secondary battery, and the peak change amount can be related to the degree of lithium deposition in a negative electrode included in the at least one cell.

[0131] In one embodiment, the controller may receive third charging data associated with a beginning of life (BoL) of at least one cell (S1030).

[0132] In one embodiment, the control unit can estimate the negative electrode stability for at least one cell based on the first to third charging data (S1040).

[0133] In one embodiment, the control unit may adjust an upper limit of a charge rate of at least one cell based on the estimated negative electrode stability (S1050). Specifically, the control unit may reduce the upper limit of the charge rate in response to determining that the negative electrode stability is less than a stability threshold.

[0134] FIG. 11 is a flowchart illustrating an example of step S1040 for estimating negative electrode stability for at least one cell according to one embodiment of the present disclosure. Step S1040 begins by calculating differential voltage data based on charging voltage data (S1110). In one embodiment, the first charging data may include first charging voltage data according to a charge capacity obtained by charging at least one cell at a first charging rate, the second charging data may include second charging voltage data according to a charge capacity obtained by charging at least one cell at a second charging rate, and the third charging data may include third charging voltage data according to a charge capacity obtained by charging at least one cell associated with a BoL. The controller may also calculate first differential voltage data for the first charging voltage data, second differential voltage data for the second charging voltage data, and third differential voltage data for the third charging voltage data.

[0135] In one embodiment, the control unit can calculate peak charge capacities included in the differential voltage data (S1120). For example, the first differential voltage data can include a peak charge capacity of 1_1 and a peak charge capacity of 1_2, the second differential voltage data can include a second peak charge capacity, and the third differential voltage data can include a peak charge capacity of 3_1 and a peak charge capacity of 3_2, where the peak charge capacity of 1_1 and the peak charge capacity of 3_1 are included in a first charge region, and the peak charge capacity of 1_2, the second peak charge capacity, and the peak charge capacity of 3_2 are included in a second charge region. The control unit can calculate the peak charge capacities of 1_1 to 3_2.

[0136] In one embodiment, the control unit may calculate a negative electrode health state for at least one cell based on the first charging data and the second charging data (S1130).

[0137] In one embodiment, the control unit may calculate a reference negative electrode health state associated with the BoL of at least one cell based on the third charging data (S1140).

[0138] In one embodiment, the control unit can estimate the negative electrode stability based on the negative electrode health degree and the reference negative electrode health degree (S1150). For example, the control unit can estimate the negative electrode stability for at least one cell based on the first to third peak charge capacities.

[0139] Additionally, the first charging data may include a state-of-full charge capacity associated with the first charging data. The controller may estimate a negative electrode stability for at least one cell based on the state-of-full charge capacity and the first to third peak charge capacities associated with the first charging data.

[0140] 10 and 11 and the above description are merely examples, and the scope of the present disclosure is not limited to the flowcharts shown in Figures 10 and 11 and the above description. For example, one or more steps in the flowcharts and the above description may be added / modified / deleted, the order of one or more steps may be changed, or one or more steps may be performed simultaneously.

[0141] Although the present invention has been described above using limited examples and drawings, it is not limited thereto, and it goes without saying that various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims. [Explanation of symbols]

[0142] 110 battery cells 120 Battery System 122 Voltage Sensor 124 Control Unit 130 Charging device

Claims

1. A method for estimating negative pole stability, performed by at least one processor, comprising: receiving first charge data for at least one cell from a voltage sensor; receiving second charge data for the at least one cell from the voltage sensor; and estimating a negative electrode stability for the at least one cell based on the first charging data and the second charging data; The first charging data and the second charging data have different charging rates (C-rates).

2. the first charging data includes first charging voltage data according to a charge capacity obtained by charging the at least one cell at a first charging rate; 2. The method of claim 1, wherein the second charging data includes second charging voltage data according to a charge capacity obtained by charging the at least one cell at a second charging rate.

3. 2. The negative electrode stability estimation method according to claim 1, wherein the first charge data and the second charge data are generated by charging the at least one cell in a state where a State of Charge (SoC) of the at least one cell is less than an SoC threshold.

4. The method for estimating negative electrode stability according to claim 2 , wherein the first charging rate is slower than the second charging rate, and the second charging rate is equal to or lower than a predetermined threshold value.

5. calculating first differential voltage data for the first charging voltage data; The method for estimating negative electrode stability according to claim 2 , further comprising: calculating second differential voltage data with respect to the second charging voltage data.

6. the first differential voltage data includes a first peak charge capacity and a first peak charge capacity; the second differential voltage data includes a second peak charge capacity; the first peak charge capacity is included in a first charge region; The method for estimating negative electrode stability according to claim 5 , wherein the first_2nd peak charge capacity and the second peak charge capacity are included in a second charge region.

7. 7. The negative electrode stability estimation method according to claim 6, wherein the step of estimating the negative electrode stability for the at least one cell includes a step of estimating the negative electrode stability based on the first peak charge capacity, the first peak charge capacity, and the second peak charge capacity.

8. The step of estimating negative electrode stability for the at least one cell includes: calculating a peak change amount based on the first_2 peak charge capacity and the second peak charge capacity; and estimating the negative electrode stability based on the peak change amount, the first_1 peak charge capacity, and the first_2 peak charge capacity.

9. the at least one cell is a lithium secondary battery; The method of claim 8 , wherein the peak change is associated with a degree of lithium deposition in the negative electrode included in the at least one cell.

10. receiving third charging data associated with a beginning of life (BoL) of the at least one cell; 2. The negative electrode stability estimation method according to claim 1, wherein the step of estimating negative electrode stability for the at least one cell includes a step of estimating negative electrode stability for the at least one cell based on the first charge data to the third charge data.

11. The step of estimating negative electrode stability for the at least one cell based on the first charging data to the third charging data includes: calculating a negative electrode health state for the at least one cell based on the first charging data and the second charging data; calculating a reference negative electrode health state associated with BoL of the at least one cell based on the third charging data; The negative electrode stability estimation method according to claim 10 , further comprising: a step of estimating the negative electrode stability based on the negative electrode health degree and the reference negative electrode health degree.

12. the first charging data includes first charging voltage data according to a charge capacity obtained by charging the at least one cell at a first charging rate; the second charging data includes second charging voltage data according to a charge capacity obtained by charging the at least one cell at a second charging rate; the third charging data includes third charging voltage data according to a charge capacity obtained by charging at least one cell associated with the BoL; The method comprises: calculating first differential voltage data for the first charging voltage data; calculating second differential voltage data for the second charging voltage data; calculating third differential voltage data with respect to the third charging voltage data; the first differential voltage data includes a first peak charge capacity and a first peak charge capacity; the second differential voltage data includes a second peak charge capacity; the third differential voltage data includes a 3_1 peak charge capacity and a 3_2 peak charge capacity; the first_1 peak charge capacity and the third_1 peak charge capacity are included in a first charge region; The method for estimating negative electrode stability according to claim 10 , wherein the first_2 peak charge capacity, the second peak charge capacity, and the third_2 peak charge capacity are included in a second charge region.

13. 13. The negative electrode stability estimation method according to claim 12, wherein the step of estimating negative electrode stability for the at least one cell based on the first charge data to the third charge data includes the step of estimating negative electrode stability for the at least one cell based on the first_1 peak charge capacities to the third_2 peak charge capacities.

14. Charging the at least one cell is performed until the at least one cell is fully charged; the first charging data includes a state-of-charge charge capacity associated with the first charging data; 13. The method of claim 12, wherein estimating the negative electrode stability for the at least one cell based on the first through third charge data comprises estimating the negative electrode stability for the at least one cell based on a fully charged state charge capacity associated with the first charge data and the first through third peak charge capacities.

15. The method for estimating negative electrode stability according to claim 1 , wherein the negative electrode stability is associated with a decrease in capacity of the negative electrode and an increase in resistance of the negative electrode.

16. The method for estimating negative electrode stability according to claim 1 , further comprising the step of adjusting an upper limit of a charge rate of the at least one cell based on the estimated negative electrode stability.

17. 17. The method for estimating negative electrode stability according to claim 16, wherein adjusting the upper limit of the charge rate of the at least one cell includes decreasing the upper limit of the charge rate in response to determining that the negative electrode stability is less than a stability threshold.

18. a voltage sensor for measuring a voltage according to the charge capacity of at least one cell; a control unit that receives charging data generated by the voltage sensor and estimates negative electrode stability for the at least one cell based on the charging data; the charging data includes first charging data for the at least one cell and second charging data for the at least one cell; The first charging data and the second charging data have different charging rates.

19. the charge data further includes third charge data associated with a BoL of the at least one cell; the control unit calculates a negative electrode health degree for the at least one cell based on the first charging data and the second charging data; calculating a reference negative electrode health state associated with BoL of the at least one cell based on the third charging data; The battery system according to claim 18 , wherein the negative electrode stability is estimated based on the negative electrode health degree and the reference negative electrode health degree.

20. The battery system according to claim 18 , wherein the control unit adjusts an upper limit of a charging rate of the at least one cell based on the estimated negative electrode stability.

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