Apparatus and method for diagnosing battery

Abstract

The apparatus for diagnosing a battery according to the present disclosure includes: a capacity calculation unit configured to calculate a positive electrode capacity value and a negative electrode capacity value of the battery, respectively, for each predetermined number of charge and discharge cycles; a degradation rate calculation unit configured to calculate a positive electrode degradation rate and a negative electrode degradation rate of the battery, respectively, based on the positive electrode capacity value and the negative electrode capacity value calculated by the capacity calculation unit; and a diagnosis unit configured to diagnose a state of the battery by referring to a comparison result of comparing the positive electrode degradation rate and the negative electrode degradation rate.

Description

Technical Field

[0001] This application is based upon and claims the benefit of priority from Korean Patent Application No. 10-2023-0136849 filed on October 13, 2023, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

[0002] The present disclosure relates to an apparatus and method for diagnosing a battery, and more particularly, to an apparatus and method for diagnosing a state of a battery capable of repeated charge and discharge. Background Art

[0003] Recently, the demand for portable electronic products such as laptop computers, digital cameras, and mobile phones has increased dramatically, and electric vehicles, energy storage systems, robots, satellites, etc. have also been vigorously developed. Therefore, high-performance batteries that allow repeated charging and discharging are being actively researched.

[0004] Types of rechargeable batteries include lithium batteries using lithium ions, such as lithium ion batteries or lithium ion polymer batteries, as well as nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries. Among these, lithium batteries have advantages such as a relatively long life cycle, very low self-discharge rate, and high energy density, as they have almost no memory effect compared to batteries using nickel, and therefore their application range is gradually expanding.

[0005] At the same time, the positive and negative electrodes of such batteries gradually degrade as the number of charge and discharge cycles increases, resulting in a decrease in capacity. In this case, the positive and negative electrodes may degrade at different rates. The difference in degradation rates between the positive and negative electrodes may lead to rapid performance degradation of the battery, shortened life cycle, or damage to the separator.

[0006] For example, in the case of lithium batteries, if the degradation rate of the negative electrode is faster than that of the positive electrode, causing the negative electrode capacity to drop below that of the positive electrode, the lithium ions in the positive electrode are converted to lithium metal through a side reaction with the electrolyte and deposited on the surface of the negative electrode, causing lithium plating. This lithium plating further reduces the capacity of the negative electrode, shortening the battery life, and may damage the separator between the positive and negative electrodes, leading to battery failure or thermal runaway.

[0007] Therefore, there is a need for a battery diagnostic technology that can accurately determine the point in time when changes in charging and discharging conditions need to be applied to a battery by monitoring the battery degradation rate of each electrode.

[0008] However, as disclosed in Japanese Patent Laid-Open Publication No. 2009-252381, since the prior art determines the degradation state of a battery cell by cell by cell through differential voltage analysis, there is a problem in that the degradation rate of each electrode of the battery cannot be confirmed, and therefore, the time point at which changes in charging and discharging conditions need to be applied to the battery cannot be accurately determined. Summary of the Invention

[0009] Technical issues

[0010] The technical challenge that the present disclosure attempts to solve is to provide an apparatus and method for diagnosing a battery, which can prevent the performance degradation and shortened life cycle of the battery by monitoring the degradation rate of the battery for each electrode.

[0011] Another technical challenge that the present disclosure attempts to solve is to provide an apparatus and method for diagnosing a battery, which can extend the life of the battery while ensuring the safety of the battery.

[0012] Another technical challenge that the present disclosure attempts to solve is to provide a battery pack and a vehicle including the apparatus for diagnosing a battery according to the present disclosure.

[0013] Technical Solutions

[0014] A device for diagnosing a battery according to one aspect of the present disclosure diagnoses the state of a battery that can be repeatedly charged and discharged, and the device includes: a capacity calculation unit configured to calculate a positive electrode capacity value and a negative electrode capacity value of the battery, respectively, for each predetermined number of charge and discharge cycles; a degradation rate calculation unit configured to calculate a positive electrode degradation rate and a negative electrode degradation rate of the battery, respectively, based on the positive electrode capacity value and the negative electrode capacity value calculated by the capacity calculation unit; and a diagnosis unit configured to diagnose the state of the battery by referring to a comparison result of the positive electrode degradation rate and the negative electrode degradation rate.

[0015] In one embodiment, the capacity calculation unit may be configured to generate a battery curve representing a corresponding relationship between the capacity and voltage of the battery that changes while the battery is charging or discharging, before calculating the positive electrode capacity value and the negative electrode capacity value, and may be configured to calculate the positive electrode capacity value and the negative electrode capacity value, respectively, based on the battery curve.

[0016] In one embodiment, the capacity calculation unit may be configured to generate a first differential curve representing a corresponding relationship between a differential capacity obtained by differentiating the capacity of the battery relative to the voltage of the battery and the voltage of the battery based on the battery curve, and calculate the positive electrode capacity value using the first differential curve.

[0017] In one embodiment, the capacity calculation unit may be configured to select a partial section from the entire section of the first differential curve, calculate an area between a voltage axis representing the voltage of the first differential curve and the partial section, and calculate the positive electrode capacity value based on the calculated area.

[0018] In one embodiment, the capacity calculation unit may be configured to generate a second differential curve representing a corresponding relationship between a differential voltage obtained by differentiating the voltage of the battery relative to the capacity of the battery and the capacity of the battery based on the battery curve, and calculate the negative electrode capacity value using the second differential curve.

[0019] In one embodiment, the capacity calculation unit may be configured to select two peaks from among the peaks appearing in the second differential curve according to a predetermined selection criterion, calculate a capacity difference between the two peaks, and calculate the negative electrode capacity value based on the calculated capacity difference.

[0020] In one embodiment, the degradation rate calculation unit may be configured to calculate the positive electrode degradation rate and the negative electrode degradation rate based on the positive electrode capacity reduction amount and the negative electrode capacity reduction amount of the battery generated at each charge and discharge cycle of the battery.

[0021] In one embodiment, the apparatus may further include an NP ratio calculation unit for calculating the NP ratio of the battery by using the positive electrode capacity value and the negative electrode capacity value of the battery calculated at a diagnostic point of the battery, and the diagnostic unit may be configured to determine the state of the battery by further referring to a comparison result of the NP ratio with a predetermined reference NP ratio.

[0022] In one embodiment, the diagnosis unit may be configured to diagnose the battery state as a normal state that does not require a change in the charging or discharging conditions of the battery when the NP ratio is not less than a reference NP ratio and the negative electrode degradation rate is not faster than the positive electrode degradation rate.

[0023] In one embodiment, the diagnostic unit can be configured to diagnose the state of the battery as a first abnormal state that requires a change in the charging condition or discharging condition of the battery when the NP ratio is not less than the reference NP ratio but the negative electrode degradation rate is faster than the positive electrode degradation rate.

[0024] In one embodiment, the diagnosis unit may be configured to diagnose the state of the battery as a second abnormal state requiring suspension of use of the battery when the NP ratio is less than a reference NP ratio.

[0025] In one embodiment, the diagnostic unit may be configured to, when the negative electrode degradation rate is faster than the positive electrode degradation rate, diagnose the state of the battery as an abnormal state, which requires a change in the charging condition or discharging condition of the battery or cessation of use, and the device may further include a charging and discharging adjustment unit configured to change the charging condition or discharging condition of the battery or stop charging and discharging the battery when the state of the battery is diagnosed as an abnormal state.

[0026] A battery pack according to another aspect of the present disclosure may include the apparatus for diagnosing a battery as described above.

[0027] A vehicle according to another aspect of the present disclosure may include the apparatus for diagnosing a battery as described above.

[0028] According to another aspect of the present disclosure, a method for diagnosing a battery diagnoses a state of a battery capable of repeated charge and discharge by using a processor, and the method includes: calculating, by the processor, a positive electrode capacity value and a negative electrode capacity value of the battery for each predetermined number of charge and discharge cycles, respectively; a degradation rate calculation step, which calculates the positive electrode degradation rate and the negative electrode degradation rate of the battery based on the positive electrode capacity value and the negative electrode capacity value calculated by the processor; and diagnosing the state of the battery by referring to a comparison result of the positive electrode degradation rate and the negative electrode degradation rate by the processor.

[0029] Beneficial effects

[0030] According to the device for diagnosing a battery disclosed herein, the positive electrode capacity value and the negative electrode capacity value of the battery are calculated for each predetermined number of charge and discharge cycles, and the positive electrode degradation rate and the negative electrode degradation rate of the battery are calculated based on the calculated positive electrode capacity value and the calculated negative electrode capacity value, so that the degradation rate of the battery can be monitored for each electrode, and the time point when the charging and discharging conditions of the battery need to be changed can be accurately determined by referring to the degradation rate of each electrode.

[0031] Furthermore, in one embodiment, the device for diagnosing a battery diagnoses the state of the battery by referring to a comparison result of the degradation rate of the positive electrode of the battery and the degradation rate of the negative electrode, thereby facilitating the charge and discharge management of the battery which may lead to rapid performance degradation, shortened life cycle or damage to the diaphragm when a difference in degradation rate occurs between the positive electrode and the negative electrode, and ensuring the safety of the battery.

[0032] Furthermore, in one embodiment, the apparatus for diagnosing a battery diagnoses the state of the battery based on the NP ratio and the degradation rate of each electrode, thereby determining a point in time for a change in charging conditions or discharging conditions applied to the battery, thereby improving the safety of the battery and extending the life of the battery.

[0033] In addition, those skilled in the art will be able to clearly understand from the following description that various embodiments of the present disclosure can solve various technical problems not mentioned above. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a block diagram of an apparatus for diagnosing a battery according to an embodiment of the present disclosure.

[0035] Figure 2 A battery graph showing the relationship between battery capacity and voltage.

[0036] Figures 3 to 5 1 is a first differential graph showing a corresponding relationship between the voltage and the differential capacity of the battery in different charge and discharge cycles.

[0037] Figures 6 to 8 2 is a graph showing a second differential curve indicating a corresponding relationship between the capacity of the battery and the differential voltage in different charge and discharge cycles.

[0038] Figure 9 is a graph showing a first curve indicating a capacity decrease trend of each electrode of a battery under constant charge and discharge conditions.

[0039] Figure 10 is a graph showing a second curve representing a capacity decrease trend for each electrode of a battery under changing charge and discharge conditions according to an embodiment of the present disclosure.

[0040] Figure 11 is a flowchart illustrating a method for diagnosing a battery according to an embodiment of the present disclosure.

[0041] Figure 12 is a diagram illustrating a battery pack according to an embodiment of the present disclosure.

[0042] Figure 13 is a diagram illustrating a vehicle according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0043] Hereinafter, in order to clarify the solution corresponding to the technical challenge of the present disclosure, the embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. However, when explaining the present disclosure, if the description of the related known technology obscures the key points of the present disclosure, its description may be omitted.

[0044] In addition, the terms used in this specification are defined in consideration of the functions in the present disclosure, and these terms may vary depending on the intention or custom of designers, manufacturers, etc. Therefore, the definitions of the terms described below should be based on the contents throughout this specification.

[0045] Figure 1 is a block diagram illustrating an apparatus 100 for diagnosing a battery according to an embodiment of the present disclosure.

[0046] like Figure 1 As shown, the apparatus 100 for diagnosing a battery according to an embodiment of the present disclosure is an apparatus configured to diagnose a state of a battery capable of repeated charge and discharge, and includes a capacity calculation unit 110 , a degradation rate calculation unit 120 , and a diagnosis unit 130 .

[0047] The battery to be diagnosed (hereinafter referred to as the "target battery") in the device 100 for diagnosing a battery according to the present disclosure may be a battery cell corresponding to a basic unit of charge and discharge, a battery module in which a plurality of battery cells are connected in series and / or in parallel, or a battery pack in which a plurality of battery cells or a plurality of battery modules are connected in series and / or in parallel.

[0048] The capacity calculation unit 110 is configured to calculate a positive electrode capacity value and a negative electrode capacity value for each predetermined number of charge and discharge cycles of the target battery, the positive electrode capacity value and the negative electrode capacity value respectively representing the current capacity of the positive electrode and the negative electrode of the target battery. As described again below, the capacity calculation unit 110 may be configured to generate a battery curve representing a correspondence or correlation between the capacity and voltage of the target battery that changes while the target battery is charged or discharged before calculating the positive electrode capacity value and the negative electrode capacity value of the target battery, and to calculate the positive electrode capacity value and the negative electrode capacity value of the target battery based on the battery curve.

[0049] The degradation rate calculation unit 120 is configured to calculate the positive electrode degradation rate and the negative electrode degradation rate of the target battery, respectively, based on the positive electrode capacity value and the negative electrode capacity value calculated by the capacity calculation unit 110. For example, the degradation rate calculation unit 120 can calculate the positive electrode degradation rate and the negative electrode degradation rate based on the amount of decrease in the positive electrode capacity and the amount of decrease in the negative electrode capacity of the target battery generated during each charge and discharge cycle of the target battery.

[0050] The diagnostic unit 130 is configured to diagnose the state of the target battery by comparing the positive electrode degradation rate with the negative electrode degradation rate. For example, if the negative electrode degradation rate is faster than the positive electrode degradation rate, the diagnostic unit 130 may diagnose the state of the target battery as an abnormal state requiring a change in charging or discharging conditions of the target battery or cessation of use.

[0051] In an embodiment, the apparatus 100 for diagnosing a battery according to the present disclosure may further include an NP ratio calculation unit 122. The NP ratio calculation unit 122 may be configured to calculate the NP ratio of the target battery corresponding to the diagnostic point by using the positive electrode capacity value and the negative electrode capacity value of the target battery calculated at the diagnostic point of the target battery. In this case, the NP ratio of the target battery may be calculated according to Formula 1.

[0052] [Formula 1]

[0053] Rt=(Cn / Cp)×100[%]

[0054] In Formula 1, Rt is the NP ratio of the target battery, Cn is the negative electrode capacity of the target battery, and Cp is the positive electrode capacity of the target battery.

[0055] In this case, the diagnosis unit 130 may be configured to determine the state of the target battery by further comparing the reference NP ratio with a predetermined reference NP ratio.

[0056] In one embodiment, the reference NP ratio may be an NP ratio obtained by adding or subtracting a predetermined margin value from the NP ratio of the target battery calculated at the target battery's BOL (Beginning of Life) point. In this case, the margin value may be determined within a range of 0 to 10 percentage points. In another embodiment, the reference NP ratio may be a NP ratio predetermined based on the composition and amount of the positive and negative active materials of the target battery.

[0057] For example, if the NP ratio of the target battery corresponding to the diagnostic point is not less than the reference NP ratio and the negative electrode degradation rate of the target battery is not faster than the positive electrode degradation rate, the diagnostic unit 130 can diagnose the state of the target battery as a normal state that does not require a change in the charge state or discharge state of the target battery.

[0058] On the contrary, if the NP ratio of the target battery corresponding to the diagnostic point is not less than the reference NP ratio, but the negative electrode degradation rate of the target battery is faster than the positive electrode degradation rate, the diagnostic unit 130 can diagnose the state of the target battery as a first abnormal state, which requires a change in the charging condition or the discharging condition of the target battery.

[0059] In particular, if the NP ratio of the target battery corresponding to the diagnostic point becomes smaller than the reference NP ratio because the negative electrode degradation rate of the target battery becomes faster than the positive electrode degradation rate before the diagnostic point, the diagnostic unit 130 may diagnose the state of the target battery as a second abnormal state requiring suspension of use of the battery.

[0060] In one embodiment, the apparatus 100 for diagnosing a battery according to the present disclosure may further include a charge and discharge adjustment unit 140. The charge and discharge adjustment unit 140 may be configured to change the charge condition or discharge condition of the target battery, or stop charging and discharging the target battery, when the state of the target battery is diagnosed as an abnormal state.

[0061] That is, when the state of the target battery is diagnosed as the first abnormal state, the charge and discharge adjustment unit 140 can prevent rapid degradation of the target battery by changing the charging or discharging conditions of the target battery. In one embodiment, the charge and discharge adjustment unit 140 can be configured to control the charger or discharger to reduce the current rate of charging or discharging the target battery, or to reduce the full charge voltage of the target battery. In another embodiment, the charge and discharge adjustment unit 140 can be configured to control a cooling device, such as a radiator, to reduce the temperature of the target battery.

[0062] The capacity calculation unit 110, degradation rate calculation unit 120, and diagnosis unit 130 of the battery diagnostic apparatus 100 described above can be implemented by a processor and a program executed by the processor. Furthermore, when the battery diagnostic apparatus 100 further includes the NP ratio calculation unit 122 and the charge and discharge adjustment unit 140 described above, the NP ratio calculation unit 122 and the charge and discharge adjustment unit 140 can also be implemented by a processor and a program executed by the processor. The capacity calculation unit 110, degradation rate calculation unit 120, diagnosis unit 130, NP ratio calculation unit 122, and charge and discharge adjustment unit 140 can be implemented by a single processor or by two or more processors interacting with each other.

[0063] In one embodiment, the apparatus 100 for diagnosing a battery according to the present disclosure may be configured to interact with various sensors, such as a voltage sensor 14 a for sensing the voltage of the battery, a current sensor 14 b for sensing the charge / discharge current of the battery, and a temperature sensor 14 c for sensing the temperature of the battery.

[0064] In addition, the apparatus 100 for diagnosing a battery according to the present disclosure may be configured to interact with a memory 16 capable of storing programs or data required for battery diagnosis. In this case, the memory 16 may include one or more of various storage media such as RAM, ROM, EEPROM, flash memory, registers, etc.

[0065] In another embodiment, the apparatus for diagnosing a battery according to the present disclosure may be configured to include one or more of the voltage sensor 14 a , the current sensor 14 b , the temperature sensor 14 c , and the memory 16 described above.

[0066] Figure 2 Schematic diagram showing a battery curve BP indicating the correspondence relationship between battery capacity and voltage.

[0067] like Figure 2As illustrated, the apparatus 100 for diagnosing a battery according to an embodiment of the present disclosure may generate a battery curve BP representing a correspondence or correlation between the capacity and voltage of a target battery that changes while the target battery is charged or discharged, before calculating the positive electrode capacity value and the negative electrode capacity value of the target battery.

[0068] To this end, the capacity calculation unit 110 can interact with a voltage sensor 14a for sensing the voltage of the target battery and a current sensor 14b for sensing the charge and discharge current of the target battery. Specifically, while the target battery is being charged or discharged, the capacity calculation unit 110 can measure the voltage of the target battery using the voltage sensor 14a and sense the charge or discharge current of the target battery using the current sensor 14b. The unit then calculates the capacity of the target battery by applying a current integration method to the sensed current values. Consequently, the capacity calculation unit 110 can generate a battery curve BP corresponding to the corresponding relationship between the capacity and voltage of the target battery.

[0069] exist Figure 2 In the 1990s, % is used as the unit of capacity (Q), but Ah, which is the product of current and time, can also be used as the unit of capacity (Q).

[0070] In addition, the capacity calculation unit 110 may calculate the positive electrode capacity value and the negative electrode capacity value of the target battery based on the generated battery curve BP.

[0071] In one embodiment, the capacity calculation unit 110 may use a predetermined simulation program to obtain the positive electrode curve PP and the negative electrode curve NP of the target battery from the battery curve BP of the target battery. For example, the capacity calculation unit 110 may obtain the positive electrode curve PP and the negative electrode curve NP using a simulation program that combines various types of positive electrode curves and negative electrode curves to select positive electrode curves and negative electrode curves that are identical to or most similar to the battery curve BP.

[0072] In this case, the capacity calculation unit 110 may calculate the positive electrode capacity value and the negative electrode capacity value of the target battery at the diagnosis point based on the obtained positive electrode curve PP and negative electrode curve NP.

[0073] In another embodiment, the capacity calculation unit 110 may calculate the positive electrode capacity value and the negative electrode capacity value of the target battery based on a differential curve obtained by differentiating the battery curve BP with respect to voltage or capacity.

[0074] For example, the capacity calculation unit 110 may be configured to generate a first differential curve representing a correspondence or correlation between a differential capacity obtained by differentiating the capacity of the target battery relative to the voltage of the target battery and the voltage of the target battery based on the battery curve BP, and calculate the positive electrode capacity value of the target battery using the first differential curve.

[0075] In addition, the capacity calculation unit 110 can be configured to generate a second differential curve representing a correspondence or correlation between a differential voltage obtained by differentiating the voltage of the target battery relative to the capacity of the target battery and the capacity of the target battery based on the battery curve BP, and calculate the negative electrode capacity value of the target battery using the second differential curve.

[0076] Figures 3 to 5 1 is a graph showing a first differential curve indicating the corresponding relationship between the voltage and the differential capacity of the battery in different charge and discharge cycles.

[0077] Figure 3 A first differential curve (Q'1) corresponding to the BOL (Beginning of Life) period of the target battery is shown.

[0078] like Figure 3 As illustrated, the capacity calculation unit 110 can generate a first differential curve (Q'1) indicating a corresponding relationship between a differential capacity obtained by differentiating the capacity of the target battery with respect to the voltage of the target battery and the voltage of the target battery based on the battery curve BP generated during the BOL (Beginning of Life) period of the target battery, and calculate the positive electrode capacity value of the target battery using the first differential curve (Q'1).

[0079] For example, the capacity calculation unit 110 may select a partial segment from the entire segment of the first differential curve (Q'1), calculate the area between the voltage axis (horizontal axis) representing the voltage of the first differential curve (Q'1) and the partial segment, and calculate the positive electrode capacity value of the target battery based on the calculated area.

[0080] To this end, the capacity calculation unit 110 may select peak points Pa1 to Pa5 having a slope (instantaneous rate of change) of 0 in the first differential curve (Q'1), and divide the first differential curve (Q'1) into a plurality of segments Sa1 to Sa5 corresponding to the peak points Pa1 to Pa5, respectively. At this time, the capacity calculation unit 110 may divide the first differential curve (Q'1) into a plurality of segments Sa1 to Sa5 based on valley points adjacent to the peak points Pa1 to Pa5.

[0081] Next, the capacity calculation unit 110 may select a segment with high correlation with the positive electrode capacity and low correlation with the negative electrode capacity from among the multiple segments Sa1 to Sa5. For example, the capacity calculation unit 110 may select the fifth segment Sa5 corresponding to the high voltage segment from among the multiple segments Sa1 to Sa5.

[0082] The capacity calculation unit 110 then calculates the area between the voltage axis (horizontal axis) and the fifth segment Sa5, and calculates the positive electrode capacity value of the target battery based on the calculated area. In this case, the capacity calculation unit 110 can regard the positive electrode capacity value corresponding to the area of the fifth segment Sa5 calculated during the BOL period as being the same as the reference positive electrode capacity value determined during the design of the target battery.

[0083] Figure 4 A first differential curve (Q'2) corresponding to the 200th charge and discharge cycle of the target battery is shown.

[0084] like Figure 4 As shown, the capacity calculation unit 110 can generate a first differential curve (Q'2) representing the correspondence relationship between the differential capacity obtained by differentiating the capacity of the target battery relative to the voltage of the target battery and the voltage of the target battery based on the battery curve BP generated in the 200th charge and discharge cycle of the target battery. Since the battery gradually deteriorates as charge and discharge are repeated, the first differential curve (Q'2) corresponding to the 200th charge and discharge cycle becomes different from the first differential curve (Q'1) corresponding to the BOL period.

[0085] Then, the capacity calculation unit 110 may select a partial segment from the entire segment of the first differential curve (Q'2), calculate the area between the voltage axis (horizontal axis) representing the voltage of the first differential curve (Q'2) and the partial segment, and calculate the positive electrode capacity value of the target battery based on the calculated area.

[0086] To this end, the capacity calculation unit 110 may select peak points Pb1 to Pb5 in the first differential curve (Q'2) where the slope (instantaneous rate of change) is zero, and divide the first differential curve (Q'2) into a plurality of segments Sb1 to Sb5 corresponding to the peak points Pb1 to Pb5, respectively. In this case, the capacity calculation unit 110 may divide the first differential curve (Q'2) into a plurality of segments Sb1 to Sb5 based on valley points adjacent to the peak points Pb1 to Pb5.

[0087] Then, as described above, the capacity calculation unit 110 may select the fifth section Sb5 corresponding to the high voltage section among the plurality of sections Sb1 to Sb5 .

[0088] The capacity calculation unit 110 then calculates the area between the voltage axis (horizontal axis) and the fifth segment Sb5 and, based on this calculated area, calculates the target battery's positive electrode capacity value. In this case, the capacity calculation unit 110 can calculate the target battery's positive electrode capacity value by comparing the area of the fifth segment Sa5 calculated during the BOL period with the area of the fifth segment Sb5 calculated during the 200th charge and discharge cycle. For example, the target battery's positive electrode capacity value corresponding to the 200th charge and discharge cycle can be calculated according to Formula 2.

[0089] [Formula 2]

[0090] A BOL :A 200 =Cp R :Cp 200

[0091] In formula 2, A BOL is the area of the fifth segment Sa5 calculated during the BOL period, A 200 is the area of the fifth segment Sb5 calculated at the 200th charge and discharge cycle, Cp R is the reference capacity value of the positive electrode, and Cp 200 is the positive electrode capacity value corresponding to the 200th charge and discharge cycle.

[0092] Figure 5 is the first differential curve (Q'3) corresponding to the 300th charge and discharge cycle of the target battery.

[0093] like Figure 5 As shown, the capacity calculation unit 110 can generate a first differential curve (Q'3) representing the corresponding relationship between the differential capacity obtained by differentiating the capacity of the target battery relative to the voltage of the target battery and the voltage of the target battery based on the battery curve BP generated in the 300th charge and discharge cycle of the target battery. Since the battery gradually deteriorates as charging and discharging are repeated, the first differential curve (Q'3) corresponding to the 300th charge and discharge cycle is different from not only the first differential curve (Q'1) corresponding to the BOL period, but also the first differential curve (Q'2) corresponding to the 200th charge and discharge cycle.

[0094] Next, the capacity calculation unit 110 may select a partial segment from the entire segment of the first differential curve (Q'3), calculate the area between the voltage axis (horizontal axis) representing the voltage of the first differential curve (Q'3) and the partial segment, and calculate the positive electrode capacity value of the target battery based on the calculated area.

[0095] To this end, the capacity calculation unit 110 may select peak points Pc1 to Pc5 having a slope (instantaneous rate of change) of 0 in the first differential curve (Q'3), and divide the first differential curve (Q'3) into a plurality of segments Sc1 to Sc5 corresponding to the peak points Pc1 to Pc5, respectively. At this time, the capacity calculation unit 110 may divide the first differential curve (Q'3) into a plurality of segments Sc1 to Sc5 based on valley points adjacent to the peak points Pc1 to Pc5.

[0096] Then, as described above, the capacity calculation unit 110 may select the fifth section Sc5 corresponding to the high voltage section among the plurality of sections Sc1 to Sc5 .

[0097] The capacity calculation unit 110 then calculates the area between the voltage axis (horizontal axis) and the fifth segment Sc5, and based on this calculated area, calculates the target battery's positive electrode capacity value. In this case, the capacity calculation unit 110 can calculate the target battery's positive electrode capacity value by comparing the area of the fifth segment Sa5 calculated during the BOL period with the area of the fifth segment Sc5 calculated during the 300th charge and discharge cycle. For example, the positive electrode capacity value corresponding to the 300th charge and discharge cycle of the target battery can be calculated according to Formula 3.

[0098] [Formula 3]

[0099] A BOL :A 300 =Cp R :Cp 300

[0100] In formula 3, A BOL is the area of the fifth segment Sa5 calculated during the BOL period, A 300 is the area of the fifth segment Sc5 calculated at the 300th charge and discharge cycle, Cp R is the reference capacity value of the positive electrode, and Cp 300 is the positive electrode capacity value corresponding to the 300th charge and discharge cycle.

[0101] Figures 6 to 8 is a graph showing a second differential curve indicating the corresponding relationship between the capacity and the differential voltage of the battery in different charge and discharge cycles.

[0102] Figure 6 A second differential curve (V'1) corresponding to the BOL (Beginning of Life) period of the target battery is shown.

[0103] like Figure 6As illustrated, the capacity calculation unit 110 can generate a second differential curve (V'1) indicating a correspondence relationship between a differential voltage obtained by differentiating the voltage of the target battery with respect to the capacity of the target battery and the capacity of the target battery based on the battery curve BP generated during the BOL (Beginning of Life) period of the target battery, and calculate the negative electrode capacity value of the target battery using the second differential curve (V'1).

[0104] For example, the capacity calculation unit 110 may select two peaks from among the peaks Pd1 to Pd5 appearing in the second differential curve (V'1) according to a predetermined selection criterion, calculate the capacity difference between the two peaks, and calculate the negative electrode capacity value based on the calculated capacity difference.

[0105] To this end, the capacity calculation unit 110 may select peaks Pd1 to Pd5 in the second differential curve (V'1) having a slope (instantaneous rate of change) of zero, and select two peaks from these peaks Pd1 to Pd5 that have a high correlation with the negative electrode capacity and a low correlation with the positive electrode capacity. For example, the capacity calculation unit 110 may select the first peak Pd1 and the third peak Pd3 located in the low-capacity section from the peaks Pd1 to Pd5 of the second differential curve (V'1).

[0106] The capacity calculation unit 110 can then calculate the capacity difference (ΔQ1) between the first peak Pd1 and the third peak Pd3, and calculate the capacity value of the negative electrode of the target battery based on the calculated capacity difference (ΔQ1). In this case, the capacity calculation unit 110 can treat the capacity value of the negative electrode corresponding to the calculated capacity difference (ΔQ1) at the BOL time as the same as the reference capacity value of the negative electrode determined during the design of the target battery.

[0107] Figure 7 A second differential curve (V'2) corresponding to the 200th charge and discharge cycle of the target battery is shown.

[0108] like Figure 7 As shown, the capacity calculation unit 110 can generate a second differential curve (V'2) representing the corresponding relationship between the differential voltage obtained by differentiating the voltage of the target battery relative to the capacity of the target battery and the capacity of the target battery based on the battery curve BP generated in the 200th charge and discharge cycle of the target battery. Since the battery gradually deteriorates as charge and discharge are repeated, the second differential curve (V'2) corresponding to the 200th charge and discharge cycle becomes different from the second differential curve (V'1) corresponding to the BOL period.

[0109] Then, the capacity calculation unit 110 may select two peaks from the peaks Pe1 to Pe5 appearing in the second differential curve (V'2) according to a predetermined selection criterion, calculate the capacity difference between the two peaks, and calculate the negative electrode capacity value of the target battery based on the calculated capacity difference.

[0110] To this end, the capacity calculation unit 110 can select peaks Pe1 to Pe5 whose slope (instantaneous change rate) is 0 in the second differential curve (V'2), and as described above, select the first peak Pe1 and the third peak Pe3 located in the low capacity segment from these peaks Pe1 to Pe5.

[0111] The capacity calculation unit 110 then calculates the capacity difference (ΔQ2) between the first peak Pe1 and the third peak Pe3 and, based on the calculated capacity difference (ΔQ2), calculates the negative electrode capacity value of the target battery. In this case, the capacity calculation unit 110 can calculate the negative electrode capacity value of the target battery by comparing the capacity difference (ΔQ1) calculated during the BOL period with the capacity difference (ΔQ2) calculated during the 200th charge and discharge cycle. For example, the negative electrode capacity value corresponding to the 200th charge and discharge cycle of the target battery can be calculated according to Formula 4.

[0112] [Formula 4]

[0113] ΔQ1:ΔQ2=Cn R :Cn 200

[0114] In Formula 4, ΔQ1 is the capacity difference between the first peak Pd1 and the third peak Pd3 of the second differential curve (V'1) corresponding to the BOL period, ΔQ2 is the capacity difference between the first peak Pe1 and the third peak Pe3 of the second differential curve (V'2) corresponding to the 200th charge and discharge cycle, and Cn R is the reference capacity value of the negative electrode, and Cn 200 is the negative electrode capacity value corresponding to the 200th charge and discharge cycle.

[0115] Figure 8 A second differential curve (V'3) corresponding to the 300th charge and discharge cycle of the target battery is shown.

[0116] like Figure 8As shown, the capacity calculation unit 110 can generate a second differential curve (V'3) representing the corresponding relationship between the differential voltage obtained by differentiating the voltage of the target battery relative to the capacity of the target battery and the capacity of the target battery based on the battery curve BP generated in the 300th charge and discharge cycle of the target battery. Since the battery gradually deteriorates as charging and discharging are repeated, the second differential curve (V'3) corresponding to the 300th charge and discharge cycle is different from the second differential curve (V'1) corresponding to the BOL period and the second differential curve (V'2) corresponding to the 200th charge and discharge cycle.

[0117] Then, the capacity calculation unit 110 may select two peaks from the peaks Pf1 to Pf5 appearing in the second differential curve (V'3) according to a predetermined selection criterion, calculate the capacity difference between the two peaks, and calculate the negative electrode capacity value of the target battery based on the calculated capacity difference.

[0118] To this end, the capacity calculation unit 110 can select peaks Pf1 to Pf5 whose slope (instantaneous rate of change) is 0 in the second differential curve (V'3), and as described above, select the first peak Pf1 and the third peak Pf3 located in the low capacity segment among these peaks Pf1 to Pf5.

[0119] The capacity calculation unit 110 can then calculate the capacity difference (ΔQ3) between the first peak Pf1 and the third peak Pf3 and calculate the target battery's negative electrode capacity value based on the calculated capacity difference (ΔQ3). In this case, the capacity calculation unit 110 can calculate the target battery's negative electrode capacity value by comparing the capacity difference (ΔQ1) calculated during the BOL period with the capacity difference (ΔQ3) calculated at the 300th charge and discharge cycle. For example, the target battery's negative electrode capacity value corresponding to the 300th charge and discharge cycle can be calculated according to Formula 5.

[0120] [Formula 5]

[0121] ΔQ1:ΔQ3 = NC R :NC 300

[0122] In Formula 4, ΔQ1 is the capacity difference between the first peak Pd1 and the third peak Pd3 of the second differential curve (V'1) corresponding to the BOL period, ΔQ3 is the capacity difference between the first peak Pf1 and the third peak Pf3 of the second differential curve (V'3) corresponding to the 300th charge and discharge cycle, and Cn R is the reference capacity value of the negative electrode, Cn 300 It is the negative electrode capacity value corresponding to the 300th charge and discharge cycle.

[0123] Figure 9is a graph showing a first curve indicating a capacity decrease trend of each electrode of a battery under constant charge and discharge conditions.

[0124] like Figure 9 As shown, as the charge and discharge cycles increase, the positive and negative electrodes of the battery deteriorate and the available capacity gradually decreases.

[0125] Even if the negative electrode degradation rate becomes faster than the positive electrode degradation rate after the N2 cycle, if the existing battery charge and discharge conditions remain constant, the negative electrode degradation rate will continue to accelerate due to side reactions occurring in the battery. Therefore, the period (ΔN1) from the point (N2) when the negative electrode degradation rate becomes faster than the positive electrode degradation rate to the battery's EOL (end of life) point (Na) at which use of the battery must be discontinued becomes shorter.

[0126] Therefore, the device for diagnosing a battery according to an embodiment of the present disclosure can monitor the degradation rate of the battery for each electrode, detect the time point (N2) when the negative electrode degradation rate becomes faster than the positive electrode degradation rate, and relax the charging and discharging conditions of the battery from the detected time point (N2), thereby ensuring the safety of the battery and extending the life of the battery.

[0127] Figure 10 is a graph of a second curve showing a capacity decrease trend for each electrode of a battery under varying charge and discharge conditions according to the present disclosure.

[0128] like Figure 10 As illustrated, the device for diagnosing a battery according to an embodiment of the present disclosure can monitor the degradation rate of the battery for each electrode, detect the time point (N2) when the degradation rate of the negative electrode becomes faster than the degradation rate of the positive electrode, and relax the charging and discharging conditions of the battery from the detected time point (N2), thereby slowing down the degradation rate of the battery, especially the degradation rate of the negative electrode.

[0129] Therefore, according to the present disclosure, the period (ΔN2) from the time point (N2) at which the negative electrode degradation rate becomes faster than the positive electrode degradation rate to the battery EOL point (Nb) at which use of the battery must be discontinued becomes longer.

[0130] Figure 11 is a flowchart of a method for diagnosing a battery according to an embodiment of the present disclosure.

[0131] The method for diagnosing a battery according to the present disclosure is a method for diagnosing the condition of a battery capable of repeated charge and discharge using a processor. The battery to be diagnosed by the method for diagnosing a battery according to the present disclosure (hereinafter referred to as a "target battery") may be a battery cell corresponding to a basic unit of charge and discharge, a battery module in which multiple battery cells are connected in series and / or in parallel, or a battery pack in which multiple battery cells or multiple battery modules are connected in series and / or in parallel.

[0132] According to an embodiment of the present disclosure, the processor calculates a positive electrode capacity value and a negative electrode capacity value respectively representing current capacities of the positive electrode and the negative electrode of the target battery for each predetermined number of charge and discharge cycles of the target battery.

[0133] Next, the processor calculates the positive electrode degradation rate and the negative electrode degradation rate of the target battery based on the calculated positive electrode capacity value and negative electrode capacity value.

[0134] The processor then diagnoses the target battery's condition by comparing the calculated positive electrode degradation rate with the calculated negative electrode degradation rate. If the comparison confirms that the negative electrode degradation rate is faster than the positive electrode degradation rate, the processor may diagnose the target battery's condition as abnormal, requiring a change in charging or discharging conditions or cessation of use of the target battery.

[0135] For example, Figure 11 As illustrated, the processor may calculate a positive electrode capacity value (Cp) and a negative electrode capacity value (Cn) respectively representing the current capacities of the positive electrode and the negative electrode of the target battery for each predetermined number of charge and discharge cycles of the target battery ( S10 ).

[0136] To this end, before calculating the positive electrode capacity value (Cp) and the negative electrode capacity value (Cn) of the target battery, the processor may generate a battery curve representing a corresponding relationship between the capacity and voltage of the target battery that changes while the target battery is charged or discharged, and calculate the positive electrode capacity value and the negative electrode capacity value of the target battery based on the battery curve.

[0137] In this case, the processor can use Figure 2 The predetermined simulation program described herein obtains the positive and negative electrode curves of the target battery from the target battery's battery curve. Specifically, the processor can obtain the positive and negative electrode curves of the target battery through the simulation program. The simulation program selects the positive and negative electrode curves that are identical or most similar to the target battery curve by combining various types of positive and negative electrode curves. The processor can then calculate the positive and negative electrode capacity values of the target battery at a diagnostic point based on the obtained positive and negative electrode curves.

[0138] In another embodiment, the processor may further calculate the positive electrode capacity value and the negative electrode capacity value of the target battery based on a differential curve obtained by differentiating the battery curve of the target battery with respect to voltage or capacity, such as with respect to Figures 3 to 8 described.

[0139] Then, before calculating the positive electrode degradation rate and the negative electrode degradation rate of the target battery, the processor may calculate the NP ratio (Rt) of the target battery corresponding to the diagnostic point using the positive electrode capacity value and the negative electrode capacity value of the target battery calculated at the diagnostic point of the target battery, and compare the calculated NP ratio (Rt) with the reference NP ratio (Ro) to preliminarily diagnose the state of the target battery (S20).

[0140] At this time, the NP ratio (Rt) of the target battery can be calculated according to Formula 1. In addition, the reference NP ratio (Ro) can be an NP ratio obtained by adding or subtracting a predetermined margin value from the NP ratio of the target battery calculated at the target battery BOL time, or an NP ratio predetermined based on the composition and amount of the positive and negative active materials of the target battery.

[0141] As a result of comparing the NP ratio (Rt) of the target battery with the reference NP ratio (Ro), if the NP ratio (Rt) of the target battery is not less than the reference NP ratio (Ro) (S30), the processor may calculate the positive electrode degradation rate and the negative electrode degradation rate of the target battery based on the positive electrode capacity value and the negative electrode capacity value calculated up to the diagnosis point (S40). For example, the processor may calculate the positive electrode degradation rate (Sp) and the negative electrode degradation rate (Sn) of the target battery based on the positive electrode capacity reduction and the negative electrode capacity reduction of the target battery generated at each charge and discharge cycle of the target battery.

[0142] Next, the processor may diagnose the state of the target battery by comparing the positive electrode degradation rate (Sp) and the negative electrode degradation rate (Sn) of the target battery ( S50 ).

[0143] For example, if the negative electrode degradation rate (Sn) is not faster than the positive electrode degradation rate (Sp), the processor may diagnose the target battery's state as a normal state that does not require a change in the target battery's charging or discharging conditions. In this case, the processor may maintain the target battery's charging and discharging conditions (S60).

[0144] On the other hand, if the negative electrode degradation rate (Sn) is faster than the positive electrode degradation rate (Sp), the processor may diagnose the target battery's condition as a first abnormal condition that requires a change in the target battery's charging or discharging conditions. In this case, the processor may alleviate the burden on the target battery by changing the target battery's charging or discharging conditions (S70).

[0145] That is, if the NP ratio (Rt) of the target battery is not less than the reference NP ratio (Ro), and the negative electrode degradation rate (Sn) of the target battery is not faster than the positive electrode degradation rate (Sp), the processor can diagnose the state of the target battery as a normal state that does not require a change in the charging condition or the discharging condition of the target battery.

[0146] On the other hand, if the NP ratio (Rt) of the target battery is not less than the reference NP ratio (Ro), but the negative electrode degradation rate (Sn) of the target battery is faster than the positive electrode degradation rate (Sp), the processor may diagnose the state of the target battery as a first abnormal state that requires a change in the charging condition or the discharging condition of the target battery.

[0147] For example, if the state of the target battery is diagnosed as the first abnormal state, the processor can control the charger or discharger to reduce the current rate of charging or discharging the target battery, or reduce the full charge voltage of the target battery. In addition, the processor can control a cooling device such as a radiator to reduce the temperature of the target battery.

[0148] Then, the processor waits until the next diagnosis time, and when the next diagnosis time arrives, the processor may repeat the above-described process ( S10 to S70 ) ( S80 ).

[0149] Meanwhile, in step S30, if the NP ratio (Rt) of the target battery is less than the reference NP ratio (Ro) as a result of comparing the NP ratio (Rt) of the target battery with the reference NP ratio (Ro) (S30), the processor may diagnose the state of the target battery as a second abnormal state that requires suspension of battery use. In this case, the processor may stop charging and discharging the target battery (S90).

[0150] Figure 12 is a schematic diagram of a battery pack 10 according to an embodiment of the present disclosure.

[0151] like Figure 12 As shown, the battery pack 10 includes a battery 12 capable of repeated charge and discharge and an apparatus 100 for diagnosing a battery according to the present disclosure. In an embodiment, the battery pack 10 may further optionally include a measurement unit 14, a charge and discharge unit 18a, and a cooling unit 18b.

[0152] The measuring unit 14 may be configured to measure the voltage and / or current of the battery 12. To this end, the measuring unit 14 may include a voltage sensor 14a and a current sensor 14b, such as Figure 1The measuring unit 14 can measure the voltage of the battery 12 via the first and second sensing lines SL1 and SL2. In addition, the measuring unit 14 can measure the current of the battery B via the third sensing line SL3 connected to the current measurement circuit A. The current measurement circuit A may include a shunt resistor.

[0153] In one embodiment, the measuring unit 14 may be configured to further measure the temperature of the battery 12. To this end, the measuring unit 14 may also include a Figure 1 The temperature sensor 14c is described.

[0154] The apparatus 100 for diagnosing a battery according to an embodiment of the present disclosure may use the voltage information and current information of the battery 12 obtained from the measuring unit 14 to generate a battery diagnostic result such as a voltage signal relative to the battery 12. Figure 2 The battery curve described.

[0155] The charging and discharging unit 18a may be configured to charge and / or discharge the battery 12. To this end, the charging and discharging unit 18a may include a charger for charging the battery 12, a discharger for discharging the battery 12, at least one switch for electrically connecting the battery 12 to the terminals T1 and T2 of the battery pack 10, and the like.

[0156] The apparatus 100 for diagnosing a battery according to an embodiment of the present disclosure may control the charging and discharging unit 18 a to set charging and discharging conditions of the battery 12 or change the set charging and discharging conditions.

[0157] The cooling unit 18b may be configured to cool the battery 12. To this end, the cooling unit 18b may include a radiator that absorbs heat from the battery 12 and releases the heat to the outside.

[0158] The apparatus 100 for diagnosing a battery according to an embodiment of the present disclosure may control the temperature of the battery 12 by controlling the cooling unit 18 b.

[0159] Figure 13 is a diagram illustrating a vehicle according to an embodiment of the present disclosure.

[0160] like Figure 13 As shown, a vehicle 2 may include a battery pack 10 that provides electrical energy required for operation of the vehicle and an apparatus 100 for diagnosing a battery according to the present disclosure.

[0161] In this case, the apparatus for diagnosing a battery 100 may be configured to interact with an ECU (Electronic Control Unit) that controls operations of the vehicle 2 or a BMS (Battery Management System) of the battery pack 10 .

[0162] For reference, the apparatus 100 for diagnosing a battery according to the present disclosure may be applied to various electric devices or electric systems other than vehicles, as well as to ESS (Energy Storage System).

[0163] As described above, the device for diagnosing a battery according to the present disclosure calculates the positive electrode capacity value and the negative electrode capacity value of the battery for each predetermined number of charge and discharge cycles, and calculates the positive electrode degradation rate and the negative electrode degradation rate of the battery based on the calculated positive electrode capacity value and the calculated negative electrode capacity value, so that the degradation rate of the battery can be monitored for each electrode, and the time point when the charging and discharging conditions of the battery need to be changed can be accurately determined by referring to the degradation rate of each electrode.

[0164] Furthermore, in one embodiment, the device for diagnosing a battery diagnoses the state of the battery by referring to a comparison result of the degradation rate of the positive electrode of the battery and the degradation rate of the negative electrode, thereby helping to manage the charge and discharge of the battery which may lead to rapid performance degradation, shortened life cycle or damage to the diaphragm when a difference in degradation rate occurs between the positive electrode and the negative electrode, and ensuring the safety of the battery.

[0165] Furthermore, in one embodiment, the apparatus for diagnosing a battery diagnoses the state of the battery based on the NP ratio and the degradation rate of each electrode, thereby determining a point in time for a change in charging conditions or discharging conditions applied to the battery, thereby improving the safety of the battery and extending the life of the battery.

[0166] Furthermore, embodiments according to the present disclosure can solve various technical problems other than those mentioned in this specification in the corresponding technical field and related technical fields.

[0167] The present disclosure has been described with reference to specific embodiments. However, it will be clearly understood by those skilled in the art that various modified embodiments can be implemented within the technical scope of the present disclosure. Therefore, the embodiments disclosed above should be considered from an illustrative rather than a restrictive perspective. In other words, the true technical scope of the present disclosure is indicated by the claims, and all differences within the scope of equivalence thereto should be interpreted as being included in the present disclosure.

[0168] [Explanation of Reference Signs]

[0169] 2: Vehicle

[0170] 10: Battery pack

[0171] 100: Device for diagnosing batteries

[0172] 110: Capacity calculation unit

[0173] 120: Degradation rate calculation unit

[0174] 122: NP ratio calculation unit

[0175] 130: Diagnostic Unit

[0176] 140: Charge and discharge regulation unit

Claims

1. A device for diagnosing a battery, the device for diagnosing a battery state being capable of repeated charge and discharge, the device for diagnosing a battery comprising: a capacity calculation unit, configured to calculate a positive electrode capacity value and a negative electrode capacity value of the battery for each predetermined number of charge and discharge cycles; a degradation rate calculation unit configured to calculate a positive electrode degradation rate and a negative electrode degradation rate of the battery, respectively, based on the positive electrode capacity value and the negative electrode capacity value calculated by the capacity calculation unit; as well as A diagnosis unit is configured to diagnose a state of the battery by referring to a comparison result of the positive electrode degradation rate and the negative electrode degradation rate.

2. The device for diagnosing a battery according to claim 1, in, The capacity calculation unit is configured to generate a battery curve indicating a corresponding relationship between the capacity and voltage of the battery that changes while the battery is charged or discharged, before calculating the positive electrode capacity value and the negative electrode capacity value, and calculate the positive electrode capacity value and the negative electrode capacity value, respectively, based on the battery curve.

3. The device for diagnosing a battery according to claim 2, in, The capacity calculation unit is configured to generate a first differential curve indicating a correspondence relationship between a differential capacity obtained by differentiating the capacity of the battery with respect to the voltage of the battery and the voltage of the battery based on the battery curve, and is configured to calculate the positive electrode capacity value using the first differential curve.

4. The device for diagnosing a battery according to claim 3, in, The capacity calculation unit is configured to select a partial section from the entire section of the first differential curve, calculate an area between a voltage axis representing the voltage of the first differential curve and the partial section, and calculate the positive electrode capacity value based on the calculated area.

5. The device for diagnosing a battery according to claim 2, in, The capacity calculation unit is configured to generate a second differential curve indicating a correspondence relationship between a differential voltage obtained by differentiating the voltage of the battery with respect to the capacity of the battery and the capacity of the battery based on the battery curve, and calculate the negative electrode capacity value using the second differential curve.

6. The device for diagnosing a battery according to claim 5, in, The capacity calculation unit is configured to select two peaks from among peaks appearing in the second differential curve according to a predetermined selection criterion, calculate a capacity difference between the two peaks, and calculate the negative electrode capacity value based on the calculated capacity difference.

7. The device for diagnosing a battery according to claim 1, in, The degradation rate calculation unit is configured to calculate the positive electrode degradation rate and the negative electrode degradation rate based on a positive electrode capacity decrease amount and a negative electrode capacity decrease amount of the battery generated at each charge and discharge cycle of the battery.

8. The device for diagnosing a battery according to claim 1, further comprising: an NP ratio calculation unit for calculating the NP ratio of the battery by using the positive electrode capacity value and the negative electrode capacity value of the battery calculated at a diagnosis point of the battery, The diagnosis unit is configured to determine the state of the battery by further referring to a comparison result of the NP ratio with a predetermined reference NP ratio.

9. The device for diagnosing a battery according to claim 8, in, The diagnosis unit is configured to, when the NP ratio is not less than the reference NP ratio and the negative electrode degradation rate is not faster than the positive electrode degradation rate, diagnose the state of the battery as a normal state that does not require a change in a charging condition or a discharging condition of the battery.

10. The device for diagnosing a battery according to claim 8, in, The diagnosis unit is configured to, when the NP ratio is not less than the reference NP ratio but the negative electrode degradation rate is faster than the positive electrode degradation rate, diagnose the state of the battery as a first abnormal state requiring a change in charging conditions or discharging conditions of the battery.

11. The device for diagnosing a battery according to claim 8, in, The diagnosis unit is configured to diagnose the state of the battery as a second abnormal state requiring suspension of use of the battery when the NP ratio is less than the reference NP ratio.

12. The device for diagnosing a battery according to claim 1, in, The diagnosis unit is configured to, when the negative electrode degradation rate is faster than the positive electrode degradation rate, diagnose the state of the battery as an abnormal state requiring a change in charging or discharging conditions of the battery or requiring suspension of use, and Wherein, the device for diagnosing a battery further includes a charging and discharging adjustment unit, which is configured to change the charging condition or the discharging condition of the battery or stop charging and discharging the battery when the state of the battery is diagnosed as an abnormal state.

13. A battery pack comprising the device for diagnosing a battery according to any one of claims 1 to 12.

14. A vehicle comprising the device for diagnosing a battery according to any one of claims 1 to 12.

15. A method for diagnosing a battery, the method diagnosing a state of a battery capable of repeated charge and discharge by using a processor, the method comprising: The processor calculates the positive electrode capacity value and the negative electrode capacity value of the battery for each predetermined number of charge and discharge cycles; a degradation rate calculation step of calculating a positive electrode degradation rate and a negative electrode degradation rate of the battery based on the positive electrode capacity value and the negative electrode capacity value calculated by the processor; and The state of the battery is diagnosed by referring to a comparison result of the positive electrode degradation rate and the negative electrode degradation rate by the processor.

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