Resistance increase rate diagnosis device and operation method thereof

Abstract

A resistance increase rate diagnosis device according to an embodiment disclosed in the present document may comprise: a determination unit for determining a reference voltage range on the basis of a discharge profile of a unit cell; an identification unit for identifying a capacity retention rate of the unit cell, which has undergone a designated number of charge and discharge cycles, in the reference voltage range; and a diagnosis unit for diagnosing a resistance increase rate of the unit cell on the basis of the identified capacity retention rate.

Description

Resistance increase rate diagnostic device and its operating method

[0001] Cross-citation with related application(s)

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0093380, filed July 18, 2023, the entire contents of which are incorporated herein by reference.

[0003] The embodiments disclosed in this document relate to a resistance increase rate diagnostic device and an operating method thereof.

[0004] Recently, research and development on secondary batteries has been actively conducted. Here, secondary batteries are rechargeable and include both conventional Ni / Cd and Ni / MH batteries, as well as recent lithium-ion batteries. Among secondary batteries, lithium-ion batteries have the advantage of having a much higher energy density than conventional Ni / Cd and Ni / MH batteries. Furthermore, lithium-ion batteries can be manufactured in a compact and lightweight form, making them suitable for use as power sources for mobile devices. Recently, their use has expanded to include power sources for electric vehicles, attracting attention as a next-generation energy storage medium.

[0005] In general, a secondary battery has a structure in which an electrode assembly is sealed together with an electrolyte within an outer material and two electrode terminals with different polarities are exposed to the outside. The electrode assembly includes a plurality of unit cells, and the unit cells have a structure in which a porous separator is interposed between at least a positive electrode plate and a negative electrode plate. Here, the unit cell may be configured as a mono cell in which a positive electrode and a negative electrode are respectively positioned on the outermost sides, a bi-cell in which electrodes with the same polarity are positioned on the outermost sides, or a half cell in which a positive electrode or a negative electrode is positioned between separators on the outermost sides.

[0006] Meanwhile, the importance of technology for management systems for more efficient use and management of secondary batteries is increasing. In particular, management systems must be able to accurately predict the degradation of secondary batteries to appropriately adjust their charge / discharge output and capacity utilization strategies.

[0007] Secondary batteries degrade in that their maximum capacity does not remain at the initial design capacity, but rather decreases with each charge / discharge cycle. Based on this characteristic, resistance growth rate and capacity retention rate are used as parameters to predict secondary battery degradation. For example, the resistance growth rate is calculated based on the capacity retention rate of a secondary battery. Since resistance growth rate is directly related to the degree of degradation, the degree of degradation can be predicted based on the calculated resistance growth rate.

[0008] In general, as the charge / discharge cycle progresses, the capacity retention rate behavior and resistance increase rate behavior of the cathode material are similar, so the resistance increase rate of a unit cell including the cathode material can be predicted from the capacity retention rate behavior.

[0009] However, in the case of high-manganese cathode materials with the highest manganese (Mn) content, as the charge / discharge cycle progresses, the capacity decreases due to an increase in resistance, and the capacity increases due to the activation of the manganese oxidation / reduction reaction. Therefore, there was a problem that the capacity retention behavior over the entire voltage range did not match the resistance increase behavior of the unit cell. Therefore, in the case of a unit cell containing a high-manganese cathode material, it is necessary to determine a voltage range in which the capacity retention behavior and the resistance increase behavior of the unit cell match.

[0010] Embodiments disclosed in this document can provide a resistance increase rate diagnostic device and an operating method thereof capable of diagnosing the resistance increase rate based on the capacity retention rate in a reference voltage range where the capacity retention rate behavior and the resistance increase rate behavior of a unit cell including a high-manganese cathode material are matched.

[0011] The technical problems of the embodiments disclosed in this document are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the descriptions below.

[0012] A resistance increase rate diagnosis device according to an embodiment disclosed in this document may include a determination unit that determines a reference voltage range based on a discharge profile of a unit cell, an identification unit that identifies a capacity retention rate in the reference voltage range of the unit cell that has undergone a specified number of charge / discharge cycles, and a diagnosis unit that diagnoses the resistance increase rate of the unit cell based on the identified capacity retention rate.

[0013] In a resistance increase rate diagnostic device according to an embodiment disclosed in this document, the determination unit can determine a reference voltage based on a slope of the discharge profile, and determine the reference voltage range based on the reference voltage.

[0014] In a resistance increase rate diagnostic device according to an embodiment disclosed in this document, the determination unit can determine a voltage at an inflection point of the discharge profile as the reference voltage.

[0015] In the resistance increase rate diagnostic device according to one embodiment disclosed in this document, the determination unit can determine a voltage range equal to or greater than the reference voltage and equal to or less than the upper limit voltage of the charge / discharge cycle as the reference voltage range.

[0016] In a resistance increase rate diagnostic device according to an embodiment disclosed in this document, the identification unit can identify the capacity maintenance rate based on the capacity change amount in the reference voltage range of the unit cell that has undergone the specified number of charge / discharge cycles.

[0017] In the resistance increase rate diagnostic device according to one embodiment disclosed in this document, the unit cell may include a high-manganese anode having the highest manganese (Mn) content among the constituent components. Such a high-manganese anode may be, for example, an anode including a lithium metal oxide as a cathode active material, in which at least 50 mol% of the total metal excluding lithium is manganese (Mn).

[0018] A resistance increase rate diagnosis method according to an embodiment disclosed in this document may include an operation of determining a reference voltage range based on a discharge profile of a unit cell, an operation of identifying a capacity retention rate in the reference voltage range of the unit cell that has undergone a specified number of charge / discharge cycles, and an operation of diagnosing the resistance increase rate of the unit cell based on the identified capacity retention rate.

[0019] In a resistance increase rate diagnosis method according to an embodiment disclosed in this document, the operation of determining the reference voltage range may include an operation of determining the reference voltage based on a slope of the discharge profile, and an operation of determining the reference voltage range based on the reference voltage.

[0020] In a resistance increase rate diagnosis method according to an embodiment disclosed in this document, the operation of determining the reference voltage may include an operation of determining a voltage at an inflection point of the discharge profile as the reference voltage.

[0021] In a resistance increase rate diagnosis method according to an embodiment disclosed in this document, the operation of determining the reference voltage range may include an operation of determining a voltage range equal to or greater than the reference voltage and equal to or less than the upper limit voltage of the charge / discharge cycle as the reference voltage range.

[0022] In a resistance increase rate diagnosis method according to an embodiment disclosed in this document, the operation of identifying the capacity maintenance rate may include an operation of identifying the capacity maintenance rate based on a capacity change amount in the reference voltage range of the unit cell that has undergone the specified number of charge / discharge cycles.

[0023] In a method for diagnosing a resistance increase rate according to an embodiment disclosed in this document, the unit cell may include a high-manganese anode having the highest manganese (Mn) content among the constituent components.

[0024] According to the embodiments disclosed in this document, the resistance increase rate of a unit cell including a high-manganese cathode material can be accurately diagnosed based on the capacity retention rate of the unit cell.

[0025] The effects of the method for activating a secondary battery according to the disclosure of this document are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art according to the disclosure of this document.

[0026] In addition, various effects may be provided, either directly or indirectly, through this document.

[0027] Figure 1 is a graph showing the results of measuring the capacity retention rate and resistance increase rate in the entire voltage range corresponding to each charge / discharge cycle while performing charge / discharge cycles in different voltage ranges for the unit cell to be measured.

[0028] FIG. 2 is a block diagram of a resistance increase rate diagnostic device according to one embodiment.

[0029] FIG. 3 is a diagram illustrating an example of a resistance increase rate diagnostic device according to one embodiment of the present invention determining a reference voltage range based on a discharge profile of a unit cell.

[0030] Figure 4 is a diagram showing the results of measuring capacity changes in voltage ranges other than the reference voltage range while performing charge / discharge cycles in different voltage ranges for the unit cell to be measured.

[0031] Figure 5 is a diagram showing the results of measuring the change in capacity in the reference voltage range while performing charge / discharge cycles in different voltage ranges for the unit cell to be measured.

[0032] Figure 6 is a flowchart of the operation of a resistance increase rate diagnosis device according to one embodiment.

[0033] Hereinafter, various embodiments of the present invention will be described with reference to the attached drawings. However, this is not intended to limit the present invention to specific embodiments, and it should be understood that the present invention encompasses various modifications, equivalents, and / or alternatives of the embodiments.

[0034] The various embodiments and terms used in this document are not intended to limit the technical features described in this document to specific embodiments, but should be understood to encompass various modifications, equivalents, or alternatives of the embodiments. In connection with the description of the drawings, similar reference numerals may be used to refer to similar or related components. The singular form of a noun corresponding to an item may include one or more of the items, unless the context clearly indicates otherwise.

[0035] In this document, the phrases "A or B", "at least one of A and B", "at least one of A or B", "A, B, or C", "at least one of A, B, and C", and "at least one of A, B, or C" can each include any one of the items listed together in that phrase, or all possible combinations thereof. Terms such as "first", "second", "first", "second", "A", "B", "(a)", or "(b)" may be used merely to distinguish the corresponding element from other corresponding elements, and do not limit the corresponding elements in any other respect (e.g., importance or order) unless specifically stated otherwise.

[0036] In this document, whenever a component (e.g., a first component) is referred to as being “connected,” “coupled,” or “connected,” with or without the terms “functionally” or “communicatively,” or “coupled” or “connected,” it means that the component can be connected to the other component directly (e.g., wired), wirelessly, or via a third component.

[0037] According to one embodiment, the method according to the various embodiments disclosed in the present document may be provided as included in a computer program product. The computer program product may be traded as a product between a seller and a buyer. The computer program product may be distributed in the form of a machine-readable storage medium (e.g., compact disc read-only memory (CD-ROM)), or may be distributed online (e.g., downloaded or uploaded) through an application store or directly between two user devices. In the case of online distribution, at least a portion of the computer program product may be temporarily stored or temporarily generated in a machine-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or an intermediary server.

[0038] According to various embodiments, each component (e.g., a module or a program) of the above-described components may include one or more entities, and some of the entities may be separated and placed in other components. According to various embodiments, one or more components or operations of the aforementioned components may be omitted, or one or more other components or operations may be added. Alternatively or additionally, a plurality of components (e.g., a module or a program) may be integrated into a single component. In such a case, the integrated component may perform one or more functions of each of the plurality of components identically or similarly to those performed by the corresponding component among the plurality of components prior to the integration. According to various embodiments, the operations performed by a module, program, or other component may be executed sequentially, in parallel, iteratively, or heuristically, or one or more of the operations may be executed in a different order, omitted, or one or more other operations may be added.

[0039] Figure 1 is a graph showing the results of measuring the capacity retention rate and resistance increase rate in the entire voltage range corresponding to each charge / discharge cycle while performing charge / discharge cycles in different voltage ranges for the unit cell to be measured.

[0040] Referring to FIG. 1, a graph (100) showing a resistance increase rate according to a discharge capacity retention rate of the same unit cell after a specified number of different charge / discharge cycles can be confirmed. Here, the unit cell may include a high-manganese cathode having the highest manganese (Mn) content among the constituent components. The high-manganese cathode may be a cathode including a lithium metal oxide as a cathode active material, in which more than 50 mol% of the total metal excluding lithium is manganese (Mn), and the lithium metal oxide may be, for example, a lithium manganese-rich oxide represented by Chemical Formula 1:

[0041] [Chemical Formula 1]

[0042] Li a [Ni b Co c Mn d M e ]O2

[0043] In the above chemical formula 1, 1.00 <a, 0≤b≤0.5, 0≤c≤0.10, 0.5≤d≤1.00, 0≤e≤0.20이고, M은 Al, B, Co, W, Mg, V, Ti, Zn, Ga, In, Ru, Nb, Sn, Sr 및 Zr로 이루어진 군에서 선택된 적어도 하나 이상임.

[0044] According to one embodiment, the different charge / discharge cycles may include cycles in which charge / discharge occurs within different voltage ranges (e.g., 2 V to 4.25 V, 3 V to 4.3 V, or 2 V to 4.35 V). Hereinafter, the three charge / discharge cycles of the graph (100) may be referred to as a first charge / discharge cycle (e.g., a charge / discharge cycle in a voltage range of 2 V to 4.25 V), a second charge / discharge cycle (e.g., a charge / discharge cycle in a voltage range of 3 V to 4.3 V), and a third charge / discharge cycle (e.g., a charge / discharge cycle in a voltage range of 2 V to 4.35 V).

[0045] Referring to graph (100), it can be confirmed that, in the case of a unit cell that has undergone the first charge / discharge cycle or the third charge / discharge cycle, the capacity retention rate behavior and the resistance increase rate behavior have a linear relationship. Specifically, in the case of a unit cell that has undergone the first charge / discharge cycle or the third charge / discharge cycle, it can be confirmed that, as the capacity retention rate decreases, the resistance increase rate increases.

[0046] On the other hand, for unit cells that have undergone a second charge / discharge cycle, it can be confirmed that the capacity retention rate behavior and the resistance increase rate behavior have a nonlinear relationship. Specifically, for unit cells that have undergone a second charge / discharge cycle, it can be confirmed that the decrease or increase in the capacity retention rate and the decrease or increase in the resistance increase rate do not correspond one-to-one.

[0047] A typical NCM (nickel-cobalt-manganese) cathode material tends to show a matching behavior between the capacity retention rate and the resistance increase rate as the charge / discharge cycle progresses. However, in the case of a high-manganese cathode material, for example, the lithium manganese-rich oxide of the above chemical formula 1, the resistance increase rate tendency according to the capacity retention rate is different from that of a typical NCM cathode material, as shown in graph (100). This can be predicted because the lithium manganese-rich oxide has two crystal phases, a rock salt phase and a layered phase, mixed together, and thus the crystal phase that is mainly activated differs depending on the progress stage and voltage of the charge / discharge cycle.

[0048] Accordingly, it may be difficult to predict the degradation of high-manganese cathode materials based on the rate of resistance increase over the entire voltage range of charge-discharge cycles.

[0049] FIG. 2 is a block diagram of a resistance increase rate diagnostic device according to one embodiment.

[0050] According to one embodiment, the resistance increase rate diagnostic device (200) may include a communication circuit (210), a sensor (220), a memory (230), and / or a processor (240). According to an embodiment, the resistance increase rate diagnostic device (200) illustrated in FIG. 2 may further include at least one component (e.g., a display, an input device, or an output device) other than the components illustrated in FIG. 2.

[0051] According to one embodiment, the resistance increase rate diagnostic device (200) can receive values ​​related to the state of a unit cell through a communication circuit (210) and / or a sensor (220). For example, the unit cell can be a unit cell including a high-manganese cathode having the highest manganese content among the components. According to one embodiment, the values ​​related to the state can include a discharge profile indicating a voltage according to a discharge capacity of the unit cell during discharge and / or a capacity change amount (or capacity retention rate) of the unit cell after a charge / discharge cycle.

[0052] According to one embodiment, the communication circuit (210) can establish a wired communication channel and / or a wireless communication channel between the resistance increase rate diagnostic device (200) and an external electronic device and / or an external server, and transmit and receive data with the external electronic device and / or the external server through the established communication channel. According to one embodiment, the communication circuit (210) can receive values ​​related to the state of a unit cell from the external electronic device and / or the external server.

[0053] According to one embodiment, the sensor (220) can measure values ​​related to the state of a unit cell.

[0054] According to one embodiment, in the resistance increase rate diagnosis device (200), one of the communication circuit (210) or the sensor (220) may be omitted. For example, if the sensor (220) is omitted, the resistance increase rate diagnosis device (200) can receive values ​​related to the state of the unit cell from an external electronic device and / or an external server only through the communication circuit (210). As another example, if the communication circuit (210) is omitted, the resistance increase rate diagnosis device (200) can measure values ​​related to the state of the unit cell only through the sensor (220).

[0055] According to one embodiment, the memory (230) may include volatile memory and / or non-volatile memory.

[0056] In one embodiment, the memory (230) may store data used by at least one component (e.g., a processor (240)) of the resistance increase rate diagnostic device (200). For example, the data may include software (or instructions related thereto), input data, or output data. In one embodiment, the instructions, when executed by the processor (240), may cause the resistance increase rate diagnostic device (200) to perform operations defined by the instructions.

[0057] In one embodiment, the memory (230) may include one or more software (e.g., an acquisition unit (231), a determination unit (233), an identification unit (235), and / or a diagnosis unit (237)).

[0058] In one embodiment, the processor (240) may include a central processing unit, an application processor, a graphics processing unit, a neural processing unit (NPU), an image signal processor, a sensor hub processor, or a communication processor.

[0059] In one embodiment, the processor (240) may execute software (e.g., acquisition unit (231), determination unit (233), identification unit (235), and / or diagnosis unit (237)) to control at least one other component (e.g., hardware or software component) of the resistance increase rate diagnostic device (200) connected to the processor (240) and perform various data processing or calculations.

[0060] Hereinafter, with reference to FIGS. 3, 4, and 5, a method for a resistance increase rate diagnosis device (200) to diagnose an abnormality of a unit cell through an acquisition unit (231), a determination unit (233), an identification unit (235), and / or a diagnosis unit (237) will be described.

[0061] FIG. 3 is a diagram illustrating an example of a resistance increase rate diagnosis device according to an embodiment of the present invention determining a reference voltage range based on a discharge profile of a unit cell. FIG. 4 is a diagram showing the results of measuring capacity changes in a voltage range outside the reference voltage range while performing charge / discharge cycles in different voltage ranges on a unit cell to be measured. FIG. 5 is a diagram showing the results of measuring capacity changes in a reference voltage range while performing charge / discharge cycles in different voltage ranges on a unit cell to be measured.

[0062] Referring to FIG. 3, a graph (300) showing a first discharge profile indicating a voltage according to a discharge capacity during discharge of a first unit cell and a second discharge profile indicating a voltage according to a discharge capacity during discharge of a second unit cell can be confirmed. Here, the first unit cell is a unit cell including a high-manganese cathode material that has not undergone a charge / discharge cycle, and the second unit cell may be a unit cell of the same type as the first unit cell that has undergone a specified number of charge / discharge cycles (e.g., 25 times).

[0063] According to one embodiment, the acquisition unit (231) can acquire the first discharge profile. According to one embodiment, the acquisition unit (231) can acquire the first discharge profile from an external electronic device and / or an external server connected through a wired and / or wireless network using a communication circuit (210). According to another embodiment, the acquisition unit (231) can also acquire the first discharge profile by measuring the discharge capacity and voltage during the discharge of the first unit cell through a sensor (220).

[0064] According to one embodiment, the decision unit (233) can determine the reference voltage range based on the first discharge profile of the first unit cell.

[0065] In one embodiment, the decision unit (233) may determine the reference voltage based on the slope of the first discharge profile. In one embodiment, the decision unit (233) may determine the voltage (e.g., 3.5 V) at the inflection point (P) of the first discharge profile as the reference voltage. In a specific example, the inflection point (P) may be defined as a point at which the mainly activated crystal phase changes, or the type of oxidation / reduction reaction that mainly expresses the capacity during charge / discharge and / or the target element changes due to the characteristics of the high-manganese cathode material, for example, the lithium manganese rich oxide of Chemical Formula 1.

[0066] In the graph (300), it can be confirmed that the discharge capacity at the inflection point (P) of the first discharge profile is higher in the first discharge profile than in the second discharge profile. This is because, in a voltage range higher than the voltage of the inflection point (P) (e.g., 3.5 V), the oxidation-reduction reaction of nickel (Ni) and oxygen (O) in the high-manganese cathode material included in the unit cell during charge and discharge, for example, the cathode active material of the lithium manganese-rich oxide of the chemical formula 1, is dominant, thereby decreasing the capacity of the unit cell.

[0067] On the other hand, in the graph (300), it can be confirmed that the discharge capacity at the part where the discharge ends (e.g., the part where the discharge capacity is about 105 mAh) is higher in the second discharge profile than in the first discharge profile. This is because, in the range below the voltage of the inflection point (P), the oxidation-reduction reaction of manganese (Mn) and oxygen (O) in the high-manganese cathode material included in the unit cell during charge and discharge, for example, the cathode active material of the lithium manganese-rich oxide of the chemical formula 1, is dominant, thereby increasing the capacity of the unit cell.

[0068] Thus, for unit cells containing high-manganese cathode materials, there is a characteristic in which the dominant reaction changes based on the inflection point of the discharge profile. That is, the dominant reaction may be the same in the voltage range above the inflection point or in the voltage range below the inflection point.

[0069] According to one embodiment, the decision unit (233) may determine a reference voltage range based on a reference voltage. For example, the decision unit (233) may determine a voltage range equal to or greater than the reference voltage and equal to or less than an upper limit voltage as the reference voltage range. Here, the upper limit voltage may refer to the upper limit voltage of a charge / discharge cycle to be performed on the first unit cell.

[0070] Hereinafter, with reference to FIGS. 4 and 5, the reason why the decision unit (233) determines the voltage range above the reference voltage and below the upper limit voltage as the reference voltage range can be explained.

[0071] Referring to FIG. 4, a graph (400) showing the resistance increase rate according to the capacity retention rate in a voltage range from a reference voltage to a lower limit voltage for the same unit cell after a specified number of different charge / discharge cycles has been confirmed. Here, the lower limit voltage may refer to the lower limit voltage of the charge / discharge cycle to be performed on the first unit cell.

[0072] Referring to graph (400), it can be confirmed that, for a unit cell that has undergone a second charge / discharge cycle, the capacity retention rate behavior and the resistance increase rate behavior have a linear relationship. Specifically, for a unit cell that has undergone a second charge / discharge cycle, it can be confirmed that, as the capacity retention rate decreases, the resistance increase rate increases.

[0073] On the other hand, for unit cells that have undergone the first or third charge / discharge cycle, it can be confirmed that the capacity retention rate behavior and the resistance increase rate behavior have a nonlinear relationship. Specifically, for unit cells that have undergone the first or third charge / discharge cycle, it can be confirmed that the decrease or increase in the capacity retention rate and the decrease or increase in the resistance increase rate do not correspond one-to-one.

[0074] That is, since the capacity retention rate behavior and the resistance increase rate behavior do not have a nearly linear relationship in all charge / discharge cycles, if the decision unit (233) determines the reference voltage range to be a voltage range higher than or equal to the lower limit voltage below the reference voltage, it may be difficult for the diagnosis unit (237) to diagnose the resistance increase rate based on the capacity retention rate.

[0075] Referring to FIG. 5, a graph (500) showing the resistance increase rate according to the capacity retention rate in the voltage range from the reference voltage to the upper limit voltage of the same unit cell that has undergone a specified number of different charge / discharge cycles can be confirmed.

[0076] Referring to graph (500), it can be confirmed that the capacity retention rate behavior and the resistance increase rate behavior have a linear relationship in the case of a unit cell that has undergone the first charge / discharge cycle, the second charge / discharge cycle, or the third charge / discharge cycle.

[0077] That is, since the capacity retention rate behavior and the resistance increase rate behavior have a nearly linear relationship in all charge / discharge cycles, when the decision unit (233) determines the reference voltage range as a voltage range from the reference voltage to the upper limit voltage, the diagnosis unit (237) can diagnose the resistance increase rate based on the capacity retention rate.

[0078] Accordingly, the decision unit (233) can determine only the voltage range that is higher than the reference voltage and lower than the upper limit voltage as the reference voltage range, rather than the voltage range that is higher than the lower limit voltage and lower than the reference voltage.

[0079] According to one embodiment, the identification unit (235) can identify the capacity retention rate of a unit cell that has undergone a specified number of charge / discharge cycles within a reference voltage range. According to one embodiment, the identification unit (235) can identify the capacity change amount of a unit cell that has undergone a specified number of charge / discharge cycles within a reference voltage range. The identification unit (235) can identify the capacity retention rate based on the capacity change amount.

[0080] According to one embodiment, the acquisition unit (231) can acquire the capacity change amount in the reference voltage range of a unit cell that has undergone a specified number of charge / discharge cycles. According to one embodiment, the acquisition unit (231) can acquire the capacity change amount from an external electronic device and / or an external server connected through a wired and / or wireless network using a communication circuit (210). According to another embodiment, the acquisition unit (231) can also measure the capacity change amount in the reference voltage range of a unit cell that has undergone a specified number of charge / discharge cycles through a sensor (220).

[0081] According to one embodiment, the identification unit (235) can identify the capacity retention rate in the reference voltage range of a unit cell that has undergone a specified number of charge / discharge cycles based on the capacity change amount.

[0082] According to one embodiment, the diagnostic unit (237) can diagnose the resistance increase rate of the unit cell based on the capacity retention rate identified by the identification unit (235). According to one embodiment, the diagnostic unit (237) can diagnose the resistance increase rate of the unit cell based on the degree of decrease in the capacity retention rate.

[0083] Fig. 6 is a flowchart illustrating the operation of a resistance increase rate diagnostic device according to one embodiment. Fig. 6 can be explained using the configuration of Fig. 2 (e.g., resistance increase rate diagnostic device (200)).

[0084] The embodiment illustrated in FIG. 6 is only one embodiment, and the order of steps according to various embodiments of the present invention may be different from that illustrated in FIG. 6, and some of the steps illustrated in FIG. 6 may be omitted, the order between steps may be changed, or steps may be merged.

[0085] In operation 605, the resistance increase rate diagnostic device (200) can determine a reference voltage range based on the discharge profile of the unit cell.

[0086] According to one embodiment, the resistance increase rate diagnosis device (200) can determine the reference voltage based on the slope of the discharge profile of the unit cell. The resistance increase rate diagnosis device (200) can determine the reference voltage range based on the reference voltage. For example, the resistance increase rate diagnosis device (200) can determine the voltage range higher than the reference voltage and lower than the upper limit voltage as the reference voltage range. Here, the upper limit voltage may mean the upper limit voltage of the charge / discharge cycle to be performed on the unit cell.

[0087] According to one embodiment, the resistance increase rate diagnostic device (200) can determine the voltage at the inflection point of the discharge profile as the reference voltage.

[0088] In operation 610, the resistance increase rate diagnostic device (200) can identify the capacity retention rate in the reference voltage range of the unit cell.

[0089] According to one embodiment, the resistance increase rate diagnostic device (200) can identify the capacity retention rate of a unit cell that has undergone a specified number of charge / discharge cycles within a reference voltage range. According to one embodiment, the resistance increase rate diagnostic device (200) can identify the capacity change amount of a unit cell that has undergone a specified number of charge / discharge cycles within a reference voltage range. The resistance increase rate diagnostic device (200) can identify the capacity retention rate based on the capacity change amount.

[0090] In operation 615, the resistance increase rate diagnostic device (200) can diagnose the resistance increase rate of the unit cell.

[0091] According to one embodiment, the resistance increase rate diagnosis device (200) can diagnose the resistance increase rate of the unit cell based on the capacity retention rate identified in operation 610. According to one embodiment, the resistance increase rate diagnosis device (200) can diagnose the resistance increase rate of the unit cell based on the degree of decrease in the capacity retention rate.

[0092] The terms "include," "comprise," or "have" used herein, unless otherwise specifically stated, imply that the corresponding component may be included, and therefore should be interpreted to include other components rather than to exclude other components. All terms, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which the embodiments disclosed in this document pertain, unless otherwise defined. Commonly used terms, such as terms defined in a dictionary, should be interpreted to be consistent with the contextual meaning of the relevant technology, and shall not be interpreted in an idealized or overly formal sense, unless explicitly defined in this document.

Claims

1. A decision unit that determines a reference voltage range based on the discharge profile of a unit cell; An identification unit for identifying the capacity retention rate of the unit cell in the reference voltage range after a specified number of charge / discharge cycles; and A resistance increase rate diagnostic device, comprising a diagnostic unit that diagnoses a resistance increase rate of the unit cell based on the identified capacity retention rate.

2. In claim 1, The above decision-making body, Determine the reference voltage based on the slope of the above discharge profile, A resistance increase rate diagnostic device that determines the reference voltage range based on the reference voltage.

3. In claim 2, The above-mentioned determination unit is a resistance increase rate diagnostic device that determines the voltage at the inflection point of the discharge profile as the reference voltage.

4. In claim 2, The above determination unit is a resistance increase rate diagnostic device that determines a voltage range equal to or greater than the reference voltage and equal to or less than the upper limit voltage of the charge / discharge cycle as the reference voltage range.

5. In claim 1, The above identification part is, A resistance increase rate diagnostic device that identifies the capacity maintenance rate based on the capacity change amount in the reference voltage range of the unit cell that has undergone the specified number of charge and discharge cycles.

6. In claim 1, The above unit cell is a resistance change producing device including a positive electrode including a lithium metal oxide in which more than 50 mol% of the total metal excluding lithium is manganese (Mn).

7. An operation to determine a reference voltage range based on the discharge profile of a unit cell; An operation of identifying a capacity retention rate in the reference voltage range of the unit cell that has undergone a specified number of charge / discharge cycles; and A resistance increase rate diagnosis method, comprising an operation of diagnosing a resistance increase rate of the unit cell based on the identified capacity retention rate.

8. In claim 7, The operation of determining the above reference voltage range is: An operation for determining a reference voltage based on the slope of the above discharge profile, and A resistance increase rate diagnosis method, comprising an operation of determining the reference voltage range based on the reference voltage.

9. In claim 8, A method for diagnosing a resistance increase rate, wherein the operation of determining the reference voltage includes an operation of determining a voltage at an inflection point of the discharge profile as the reference voltage.

10. In claim 8, A method for diagnosing a resistance increase rate, wherein the operation of determining the reference voltage range includes an operation of determining a voltage range equal to or greater than the reference voltage and equal to or less than the upper limit voltage of the charge / discharge cycle as the reference voltage range.

11. In claim 7, The operation of identifying the above capacity retention rate is: A resistance increase rate diagnosis method, comprising an operation of identifying the capacity maintenance rate based on the capacity change amount in the reference voltage range of the unit cell that has undergone the specified number of charge and discharge cycles.

12. In claim 7, A method for diagnosing a resistance increase rate, wherein the above unit cell includes a positive electrode including a lithium metal oxide in which more than 50 mol% of the total metal excluding lithium is manganese (Mn).

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