Battery diagnostic device and method

Abstract

According to an embodiment of the present invention, a battery diagnostic device includes: a profile acquisition unit configured to acquire a capacity profile for a constant current charge capacity and a constant voltage charge capacity measured during a battery charging process; and a control unit configured to calculate a capacity change rate between the constant current charge capacity and the constant voltage charge capacity from the capacity profile, compare the calculated capacity change rate with a predetermined reference value, and diagnose a state of the battery based on the comparison result.

Description

[Technical Field]

[0001] This application claims priority based on Korean Patent Application No. 10-2022-0119803, filed on September 22, 2022, the entire contents of which are incorporated herein by reference in their entirety in the specification and drawings of that application.

[0002] The present invention relates to a battery diagnostic device and method, and more particularly to a battery diagnostic device and method capable of diagnosing the state of a battery. [Background technology]

[0003] In recent years, as demand for portable electronic products such as laptops, video cameras, and mobile phones has grown rapidly and the development of electric vehicles, energy storage batteries, robots, and artificial satellites has gained momentum, active research has been conducted into high-performance batteries that can be repeatedly charged and discharged.

[0004] Currently commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Among these, lithium batteries are attracting attention due to their advantages of being able to be freely charged and discharged since they have almost no memory effect compared to nickel-based batteries, as well as their extremely low self-discharge rate and high energy density.

[0005] Although much research has been conducted into increasing the capacity and density of such batteries, improving their lifespan and safety is also important. To improve battery safety, a technology that can accurately diagnose the current state of the battery is required.

[0006] For example, it is necessary to prevent lithium deposition (lithium plating) on the surface of the negative electrode. Lithium deposition on the surface of the negative electrode can cause side reactions with the electrolyte and alter the kinetic balance of the battery, resulting in battery degradation. Furthermore, lithium metal deposition on the surface of the negative electrode can cause an internal short circuit in the battery, posing a risk of fire and explosion due to the internal short circuit. Therefore, there is a need for a technology that can detect whether lithium metal has been deposited on the surface of the negative electrode. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made to solve the above problems, and an object of the present invention is to provide a battery diagnostic device and method that can quickly diagnose the current state of a battery.

[0008] Other objects and advantages of the present invention will become apparent from the following description and the embodiments of the present invention, and can be realized by the means and combinations thereof set forth in the claims. [Means for solving the problem]

[0009] According to one aspect of the present invention, a battery diagnostic device includes: a profile acquisition unit configured to acquire a capacity profile for a constant current charge capacity and a constant voltage charge capacity measured during a battery charging process; and a control unit configured to calculate a capacity change rate between the constant current charge capacity and the constant voltage charge capacity from the capacity profile, compare the calculated capacity change rate with a predetermined reference value, and diagnose a state of the battery based on the comparison result.

[0010] The control unit may be configured to diagnose the state of the battery as a usable lithium loss state, a normal state, or a positive electrode capacity degradation state based on the comparison result.

[0011] The control unit may be configured to diagnose the state of the battery as a usable lithium loss state if the capacity change rate is less than the reference value.

[0012] The control unit may be configured to diagnose the state of the battery as normal if the capacity change rate is equal to the reference value.

[0013] The control unit may be configured to diagnose the state of the battery as a positive electrode capacity degradation state if the capacity change rate exceeds the reference value.

[0014] The control unit may be configured to divide the capacity profile into one or more capacity sections according to a magnitude relationship between the capacity change rate and the reference value, and diagnose the state of the battery for each of the divided capacity sections.

[0015] The control unit may be configured to calculate the capacity change rate for each of a plurality of constant current charging capacities included in the capacity profile, determine a target capacity from the plurality of constant current charging capacities at which a corresponding capacity change rate is equal to the reference value, and divide the capacity ranges based on the determined target capacity.

[0016] The control unit may be configured to diagnose the battery as being unsuitable for use when the battery is sequentially diagnosed as being in the positive electrode capacity depletion state, the available lithium loss state, and the positive electrode capacity depletion state.

[0017] The control unit may be configured to change a pre-set usage condition for the battery to correspond to a state of the battery.

[0018] The control unit may be configured to change at least one of an upper limit of a charging C rate and a rest period preset for the battery when the state of the battery is diagnosed as the available lithium loss state.

[0019] The control unit may be configured to change at least one of an upper limit voltage and a maximum allowable temperature preset for the battery when the state of the battery is diagnosed as the positive electrode capacity degraded state.

[0020] The capacity profile may be a profile configured to accumulate and store a correspondence between a constant current charge capacity and a constant voltage charge capacity measured for each charge cycle of the battery.

[0021] A battery pack according to another aspect of the present invention includes the battery diagnostic device according to an aspect of the present invention.

[0022] An electric vehicle according to yet another aspect of the present invention includes the battery diagnostic device according to an aspect of the present invention.

[0023] An energy storage device according to yet another aspect of the present invention includes a battery diagnostic device according to an aspect of the present invention.

[0024] According to another aspect of the present invention, a battery diagnosis method includes: a capacity profile acquisition step of acquiring a capacity profile for a constant current charge capacity and a constant voltage charge capacity measured during a battery charging process; a capacity change rate calculation step of calculating a capacity change rate between the constant current charge capacity and the constant voltage charge capacity from the capacity profile; a comparison step of comparing the calculated capacity change rate with a predetermined reference value; and a status diagnosis step of diagnosing a status of the battery based on a comparison result. [Effects of the Invention]

[0025] A battery diagnostic device according to an aspect of the present invention can quickly and specifically diagnose the state of a battery according to the degree of change between a constant current charging capacity and a constant voltage charging capacity.

[0026] The effects of the present invention are not limited to the effects described above, and other effects of the present invention not mentioned will be clearly understood by those skilled in the art from the description of the claims.

[0027] The following drawings attached to this specification, together with the detailed description of the invention described below, serve to further understand the technical concept of the present invention, and the present invention should not be interpreted as being limited to only the matters described in the drawings. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a diagram illustrating a battery diagnostic device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a diagram illustrating a first capacitance profile according to an embodiment of the present invention. [Figure 3] FIG. 4 is a diagram illustrating a comparison between a first capacity curve of a first capacity profile according to an embodiment of the present invention and a reference line. [Figure 4] 4 is a diagram illustrating a state of positive electrode capacity deterioration of a battery according to an embodiment of the present invention. FIG. [Figure 5] 1 is a diagram illustrating a loss state of available lithium in a battery according to an embodiment of the present invention. [Figure 6] FIG. 4 is a diagram illustrating a second capacitance profile according to an embodiment of the present invention. [Figure 7] FIG. 10 is a diagram illustrating a comparison between a second capacity curve of a second capacity profile according to an embodiment of the present invention and a reference line. [Figure 8] 10 is a diagram schematically illustrating an exemplary configuration of a battery pack according to another embodiment of the present invention. [Figure 9] FIG. 10 is a schematic diagram of an electric vehicle according to yet another embodiment of the present invention. [Figure 10] FIG. 10 is a diagram illustrating an ESS (Energy Storage System) according to yet another embodiment of the present invention. [Figure 11] 10 is a diagram illustrating a battery diagnostic method according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] The terms and words used in this specification and claims should not be interpreted limited to their ordinary and dictionary meanings, but should be interpreted in a meaning and concept that corresponds to the technical idea of the present invention, in accordance with the principle that the inventor himself can appropriately define the concept of the term in order to explain the invention in the best way.

[0030] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent the entire technical idea of the present invention, and that there may be various equivalents and modifications that can be substituted for them at the time of this application.

[0031] Furthermore, in the description of the present invention, if it is determined that a detailed description of related known structures or functions may obscure the gist of the present invention, the detailed description will be omitted.

[0032] Terms including ordinal numbers such as "first," "second," etc. are used to distinguish one of various components from other components, and do not limit the components.

[0033] Throughout this specification, when a part is said to "comprise" a certain element, this does not mean that it excludes other elements, but that it may further include other elements, unless otherwise specified.

[0034] Furthermore, throughout this specification, when a part is referred to as being "connected" to another part, this includes not only a "direct connection" but also an "indirect connection" via other elements.

[0035] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0036] FIG. 1 is a diagram illustrating a battery diagnostic device 100 according to an embodiment of the present invention.

[0037] Referring to FIG. 1, a battery diagnostic device 100 includes a profile acquisition unit 110, a control unit 120, and a recording unit .

[0038] Here, a battery refers to a physically separable, independent cell having a negative terminal and a positive terminal. For example, a lithium ion battery or a lithium polymer battery may be considered a battery. A battery may also refer to a battery module in which multiple cells are connected in series and / or parallel. Hereinafter, for convenience of explanation, a battery will be described as meaning a single independent cell.

[0039] The profile acquisition unit 110 may be configured to acquire a capacity profile for the constant current charging capacity and the constant voltage charging capacity measured during the charging process of the battery.

[0040] For example, the profile acquisition unit 110 can receive the capacity profile from the outside using a communication module provided therein.

[0041] As another example, the profile acquisition unit 110 may be connected to the recording unit 130 so as to perform wired and / or wireless communication with the recording unit 130. The profile acquisition unit 110 may access the recording unit 130 and acquire the capacity profile stored in the recording unit 130.

[0042] Specifically, the capacity profile may be a profile configured to accumulate and store the correspondence between the constant current charge capacity and the constant voltage charge capacity measured for each charge cycle of the battery. Here, the constant current charge capacity refers to the charge capacity when the battery is charged at a constant current (CC), and the constant voltage charge capacity refers to the charge capacity when the battery is charged at a constant voltage (CV).

[0043] Generally, in the battery charging process, a battery is charged at a constant current until the voltage reaches a preset cutoff voltage. During the constant current charging process, the charging current remains constant and the battery voltage increases in proportion to the current. Once the battery voltage reaches the cutoff voltage, the battery is charged at a constant voltage. During the constant voltage charging process, the battery voltage remains constant and the charging current gradually decreases. Once the charging current reaches the preset cutoff current, the battery charging is terminated.

[0044] For example, if a total of 100 charging cycles are performed, the capacity profile may include a correspondence between constant current charging capacity and constant voltage charging capacity for the 100 cycles.

[0045] FIG. 2 is a diagram illustrating a first capacitance profile P1 according to an embodiment of the present invention.

[0046] Specifically, the first capacity profile P1 is a profile that indicates the correspondence relationship between the constant current charge capacity and the constant voltage charge capacity of the first battery. The first capacity profile P1 is a profile normalized based on the initial constant current charge capacity and the initial constant voltage charge capacity. The normalized constant current charge capacity of the current battery may be 0.8, and the normalized constant voltage charge capacity may be approximately 1.28.

[0047] The control unit 120 may be configured to calculate the rate of change in capacity between the constant current charging capacity and the constant voltage charging capacity from the capacity profile.

[0048] Specifically, the control unit 120 can calculate the rate of change of the constant voltage charging capacity relative to the constant current charging capacity as the capacity change rate.

[0049] For example, the rate of change of capacity can be the instantaneous rate of change or the average rate of change of constant voltage charging capacity relative to constant current charging capacity.

[0050] In one embodiment, the control unit 120 may calculate an instantaneous rate of change between the constant current charging capacity and the constant voltage charging capacity most recently included in the capacity profile. Specifically, the control unit 120 may obtain a capacity curve corresponding to the capacity profile through curve fitting. The control unit 120 may also calculate an instantaneous rate of change at a desired constant current charging capacity based on a relational equation of the capacity curve.

[0051] FIG. 3 is a diagram showing a comparison between a first capacity curve QC1 of a first capacity profile P1 and a reference line RR according to an embodiment of the present invention.

[0052] 3, the first capacity curve QC1 may be a capacity curve obtained from the first capacity profile P1 using a curve fitting algorithm. The first capacity curve QC1 may indicate the correspondence relationship between the constant-current charge capacity and the constant-voltage charge capacity in the constant-current charge capacity range of 0.8 to 1.0.

[0053] The control unit 120 may be configured to compare the calculated capacitance change rate with a preset reference value.

[0054] Preferably, the control unit 120 may compare the absolute value of the calculated capacity change rate with a preset reference value. That is, the capacity change rate calculated by the control unit 120 may be 0 or a positive real value. For convenience of explanation, it should be noted that in the following, the comparison of the capacity change rate with the reference value refers to the comparison of the absolute value of the capacity change rate with the reference value.

[0055] In the embodiment of FIG. 3, the reference line RR is assumed to be a straight line whose absolute value of slope is set as a reference value. For example, the reference value may be preset to 1. Alternatively, the reference line RR may be a straight line whose slope is -1. That is, the absolute value of the slope of the reference line RR and the reference value may be 1.

[0056] Specifically, the control unit 120 can compare the calculated rate of change in capacitance with a reference value.

[0057] 3, the average rate of change and the instantaneous rate of change of the first capacity curve QC1 may be smaller than the slope of the reference line RR, and the control unit 120 may determine that the reference value is smaller than the rate of change of the capacity of the first capacity curve QC1 (specifically, the absolute value of the rate of change of the capacity).

[0058] The control unit 120 may be configured to diagnose the state of the battery based on the comparison result.

[0059] Specifically, the control unit 120 may be configured to diagnose the battery state as a usable lithium loss state, a normal state, or a positive electrode capacity degradation state based on the comparison result. That is, the control unit 120 may diagnose the battery state as a usable lithium loss state, a normal state, or a positive electrode capacity degradation state based on the result of determining whether the reference value and the capacity change rate are larger or smaller.

[0060] For example, if the capacity change rate is less than a reference value, the control unit 120 may diagnose the battery state as a usable lithium loss state. As another example, if the capacity change rate is equal to a reference value, the control unit 120 may diagnose the battery state as a normal state. As yet another example, if the capacity change rate exceeds the reference value, the control unit 120 may diagnose the battery state as a positive electrode capacity degradation state.

[0061] For example, in the embodiment of FIG. 3, the capacity change rate of the first capacity profile P1 exceeds the reference value, so the control unit 120 may diagnose the state of the first battery as a positive electrode capacity degradation state.

[0062] FIG. 4 is a diagram for explaining the state of positive electrode capacity deterioration of the battery according to one embodiment of the present invention.

[0063] Referring to FIG. 4, when the positive electrode capacity of the battery deteriorates, the constant voltage charge capacity (CV capacity) may increase from CVQi to CVQf. Also, the constant current charge capacity (CC capacity) may decrease. That is, as the positive electrode capacity deteriorates, the rate of change of the constant voltage charge capacity relative to the constant current charge capacity may change rapidly. Therefore, if the rate of change of the capacity in the capacity profile exceeds a reference value, the control unit 120 may diagnose the battery state as a state of deteriorated positive electrode capacity.

[0064] FIG. 5 is a diagram illustrating a state in which available lithium is lost in a battery according to an embodiment of the present invention.

[0065] 5, when available lithium is lost from the battery, the constant voltage charging capacity (CV capacity) remains unchanged. The constant current charging capacity (CC capacity) may decrease by the amount of available lithium lost. That is, as more available lithium is lost, the rate of change in the constant voltage charging capacity relative to the constant current charging capacity may change more slowly. Therefore, if the rate of change in capacity in the capacity profile is less than a reference value, the control unit 120 may diagnose the battery state as a state in which available lithium has been lost.

[0066] The battery diagnostic device 100 according to an embodiment of the present invention can quickly and specifically diagnose the state of a battery according to the degree of change between the constant current charging capacity and the constant voltage charging capacity.

[0067] The battery diagnostic device 100 can diagnose the battery condition by considering only the correspondence between the constant current charging capacity and the constant voltage charging capacity without being affected by the charging C rate (Current rate). Therefore, the battery diagnostic device 100 can quickly diagnose the battery condition in a situation where there are no constraints such as low-rate charging (e.g., 0.05 C charging) or data comparison at the same C rate.

[0068] Meanwhile, the control unit 120 included in the battery diagnostic device 100 may selectively include a processor, an ASIC (Application-Specific Integrated Circuit), other chipsets, logic circuits, registers, a communication modem, a data processing device, etc., known in the art, to execute various control logics performed in the present invention. Furthermore, when the control logic is embodied as software, the control unit 120 may be embodied as a collection of program modules. In this case, the program modules may be stored in a memory and executed by the control unit 120. The memory may be provided inside or outside the control unit 120 and may be connected to the control unit 120 by various well-known means.

[0069] The battery diagnostic device 100 may further include a recording unit 130. The recording unit 130 may store data and programs necessary for each component of the battery diagnostic device 100 to operate and function, or data generated during the operation and function. The recording unit 130 may be any known information recording means capable of recording, erasing, updating, and reading data. For example, the information recording means may include RAM, flash memory, ROM, EEPROM, registers, etc. The recording unit 130 may also store program code defining processes executable by the control unit 120.

[0070] The control unit 120 may be configured to divide the capacity profile into one or more capacity sections according to the magnitude relationship between the capacity change rate and a reference value.

[0071] FIG. 6 is a diagram schematically illustrating a second capacitance profile P2 according to an embodiment of the present invention.

[0072] Specifically, the second capacity profile P2 is a profile that indicates the correspondence relationship between the constant current charge capacity and the constant voltage charge capacity of the second battery. The second capacity profile P2 is a profile normalized based on the initial constant current charge capacity and the initial constant voltage charge capacity. The normalized constant current charge capacity of the current battery may be Q0, and the normalized constant voltage charge capacity may be approximately 1.3.

[0073] FIG. 7 is a diagram illustrating a comparison between the second capacity curve QC2 of the second capacity profile P2 and the reference line RR according to an embodiment of the present invention.

[0074] 7, the second capacity curve QC2 may be a capacity curve obtained from the second capacity profile P2 using a curve fitting algorithm. The second capacity curve QC2 may indicate the correspondence relationship between the constant current charge capacity and the constant voltage charge capacity in the constant current charge capacity section Q0 to Q3.

[0075] Specifically, the control unit 120 may be configured to calculate a capacity change rate for each of a plurality of constant current charging capacities included in the capacity profile, and may determine a target capacity from the plurality of constant current charging capacities, the corresponding capacity change rate of which is equal to a reference value.

[0076] 7, the reference line RR having the slope of the reference value may intersect with the second capacity curve QC2 at points Q1 and Q2. That is, at points where the constant current charging capacity is Q1 and Q2, the capacity change rate of the second capacity curve QC2 may be equal to the reference value. Therefore, the controller 120 may determine Q1 and Q2 as the target capacity.

[0077] The control unit 120 may be configured to divide the capacity zones based on the determined target capacity.

[0078] For example, in the embodiment of FIG. 7, the control unit 120 may divide Q0 to Q1 into a first capacity section RQ1, Q1 to Q2 into a second capacity section RQ2, and Q2 to Q3 into a third capacity section RQ3.

[0079] The control unit 120 may be configured to diagnose the battery state for each of the divided capacity ranges.

[0080] Specifically, the control unit 120 may diagnose the battery state for each divided capacity range. The control unit 120 may diagnose not only the current state of the battery but also the past state of the battery based on the capacity profile. That is, the control unit 120 may determine the battery state change pattern by diagnosing the battery state for each capacity range.

[0081] 7, the capacity change rate in the first capacity section RQ1 may exceed the reference value, and the control unit 120 may diagnose the battery state in the first capacity section RQ1 as a positive electrode capacity degradation state.

[0082] Then, the capacity change rate in the second capacity range RQ2 may be less than the reference value, and the control unit 120 may diagnose the battery state in the second capacity range RQ2 as a usable lithium loss state.

[0083] Finally, the capacity change rate in the third capacity range RQ3 may exceed the reference value. Therefore, the control unit 120 may diagnose the battery state in the third capacity range RQ3 as a positive electrode capacity degradation state. That is, the control unit 120 may diagnose the current state of the battery as a capacity degradation state.

[0084] The battery diagnostic device 100 according to an embodiment of the present invention can determine the state change pattern of the battery life cycle by specifically diagnosing the state of the battery for each capacity range. In particular, the battery diagnostic device 100 can identify the time point at which the state of the battery changes, which is advantageous in that it can more efficiently collect related information that affects the change in the state of the battery.

[0085] Meanwhile, the control unit 120 may be configured to diagnose the battery state as unsuitable for use when the battery state is sequentially diagnosed as a positive electrode capacity depletion state, a usable lithium loss state, and a positive electrode capacity depletion state.

[0086] Specifically, when the battery state changes sequentially from a positive electrode capacity depletion state to a usable lithium loss state to a positive electrode capacity depletion state, the control unit 120 may diagnose the battery state as being unsuitable for use (End of Life (EOL) state). Generally, an unsuitable state refers to a state in which the battery's State of Health (SOH) is less than 70%, and may be a state in which the battery should be discarded. Continuing to use a battery in an unsuitable state may result in unexpected accidents such as explosions and fires.

[0087] Therefore, when the battery state change shows a certain pattern, the battery diagnostic device 100 diagnoses the battery state as being unsuitable for use, thereby preventing unexpected accidents in advance.

[0088] The control unit 120 may be configured to change the pre-set usage conditions for the battery to correspond to the state of the battery.

[0089] When the battery state is diagnosed as a state of available lithium loss, the control unit 120 may change at least one of the upper limit of the charge C rate and the rest period preset for the battery.

[0090] In one embodiment, the control unit 120 may reduce a preset upper limit of the charge C rate to prevent or delay lithium plating, which is the deposition of lithium metal on the negative electrode of the battery. For example, the control unit 120 may prevent high-rate charging of the battery by reducing the upper limit of the charge C rate of the battery.

[0091] In one embodiment, the control unit 120 may increase a rest time set for the battery, that is, by increasing the rest time during which the battery is maintained in an unloaded state after charging or discharging of the battery is completed, the electrical balance state of the battery can be maintained for a longer period of time.

[0092] When the battery state is diagnosed as a positive electrode capacity degradation state, the control unit 120 can change at least one of the upper limit voltage and the maximum allowable temperature preset for the battery.

[0093] In one embodiment, the control unit 120 may reduce the upper voltage limit and / or the maximum allowable temperature set for the battery to prevent or delay capacity degradation of the positive electrode.

[0094] The battery diagnostic device 100 according to an embodiment of the present invention can prevent rapid deterioration of the battery by appropriately changing the use conditions according to the diagnosed state of the battery.

[0095] In particular, the battery diagnostic device 100 can identify the time when the battery state changes, and can quickly change the usage conditions to best suit the current state of the battery. Therefore, the battery diagnostic device 100 can increase the expected lifespan of the battery.

[0096] The battery diagnostic device 100 according to the present invention may be applied to a battery management system (BMS). That is, the BMS according to the present invention may include the above-described battery diagnostic device 100. In this configuration, at least some of the components of the battery diagnostic device 100 may be implemented by complementing or adding functions of components included in a conventional BMS. For example, the profile acquisition unit 110, the control unit 120, and the recording unit 130 of the battery diagnostic device 100 may be implemented as components of the BMS.

[0097] The battery diagnostic device 100 according to the present invention may be provided in a battery pack. That is, the battery pack according to the present invention may include the above-described battery diagnostic device 100 and one or more battery cells. The battery pack may further include electrical components (e.g., a relay, a fuse, etc.) and a case.

[0098] FIG. 8 is a diagram schematically illustrating an exemplary configuration of a battery pack 10 according to another embodiment of the present invention.

[0099] The positive terminal of the battery 11 may be connected to the positive terminal P+ of the battery pack 10, and the negative terminal of the battery 11 may be connected to the negative terminal P- of the battery pack 10.

[0100] The measurement unit 12 may be connected to a first sensing line SL1, a second sensing line SL2, and a third sensing line SL3. Specifically, the measurement unit 12 may be connected to a positive terminal of the battery 11 via the first sensing line SL1 and to a negative terminal of the battery 11 via the second sensing line SL2. The measurement unit 12 may measure the voltage of the battery 11 based on the voltages measured on the first sensing line SL1 and the second sensing line SL2.

[0101] The measuring unit 12 may also be connected to a current measuring unit A through a third sensing line SL3. For example, the current measuring unit A may be an ammeter or a shunt resistor capable of measuring the charging current and discharging current of the battery 11. The measuring unit 12 may measure the charging current of the battery 11 through the third sensing line SL3 to calculate the charging capacity. The measuring unit 12 may also measure the discharging current of the battery 11 through the third sensing line SL3 to calculate the discharging capacity.

[0102] An external device (not shown) may be connected to the positive terminal P+ and the negative terminal P− of the battery pack 10. For example, the external device may be a charging / discharging device, or may be a motor of an electric vehicle that receives power from the battery 11. While the charging / discharging device is connected to the battery pack 10 and the battery 11 is being charged, the measuring unit 12 may measure the constant current charging capacity and the constant voltage charging capacity of the battery 11.

[0103] FIG. 9 is a schematic diagram of an electric vehicle 900 according to yet another embodiment of the present invention.

[0104] 9, a battery pack 910 according to an embodiment of the present invention may be mounted on a vehicle 900 such as an electric vehicle (EV) or a hybrid vehicle (HV). The battery pack 910 may drive the vehicle 900 by supplying power to a motor through an inverter provided in the vehicle 900.

[0105] The electric vehicle 900 may also include a battery diagnostic device 100. For example, the battery diagnostic device 100 may be provided in a battery pack 910 to diagnose the condition of the battery pack 910 and / or each battery cell included in the battery pack 910.

[0106] FIG. 10 is a diagram schematically illustrating an ESS (Energy Storage System) according to yet another embodiment of the present invention.

[0107] 10, the ESS includes a plurality of rack cases 1010 and a plurality of battery modules 1020. The plurality of battery modules 1020 may be configured to be housed in the rack case 1010 in a vertically arranged form.

[0108] Each of the plurality of battery modules 1020 may be provided with a battery diagnostic device 100. The battery diagnostic device 100 may diagnose the state of the corresponding battery module 1020 and / or the battery cells included in the battery module 1020.

[0109] FIG. 11 is a diagram illustrating a battery diagnostic method according to yet another embodiment of the present invention.

[0110] Preferably, each step of the battery diagnostic method may be performed by the battery diagnostic device 100. Hereinafter, for convenience of explanation, the contents overlapping with the above explanation will be omitted or briefly explained.

[0111] Referring to FIG. 11, the battery diagnostic method includes a capacity profile obtaining step S100, a capacity change rate calculating step S200, a comparison step S300, and a state diagnosis step S400.

[0112] The capacity profile acquiring step S100 is a step of acquiring a capacity profile for a constant current charge capacity and a constant voltage charge capacity measured during the charging process of the battery, and may be performed by the profile acquiring unit 110.

[0113] For example, the profile acquisition unit 110 can acquire the capacity profile from an external source or from the recording unit 130 .

[0114] The capacity change rate calculation step S200 is a step of calculating a capacity change rate between a constant current charging capacity and a constant voltage charging capacity from the capacity profile, and can be performed by the control unit 120.

[0115] For example, the control unit 120 can calculate the capacity change rate by calculating the ratio of the constant voltage charging capacity to the constant current charging capacity.

[0116] The comparing step S300 is a step of comparing the calculated capacitance change rate with a preset reference value, and can be performed by the control unit 120.

[0117] For example, the control unit 120 can make a determination by comparing the calculated rate of change in capacitance with a preset reference value.

[0118] The state diagnosis step S400 is a step of diagnosing the state of the battery based on the comparison result, and may be performed by the control unit 120.

[0119] For example, if the capacity change rate is less than a reference value, the control unit 120 may diagnose the battery state as a usable lithium loss state. As another example, if the capacity change rate is equal to a reference value, the control unit 120 may diagnose the battery state as a normal state. As yet another example, if the capacity change rate exceeds the reference value, the control unit 120 may diagnose the battery state as a positive electrode capacity degradation state.

[0120] Meanwhile, the control unit 120 can divide the capacity profile into a plurality of capacity sections and specifically diagnose the battery state in each capacity section. Furthermore, when the battery state changes show a certain pattern (when the positive electrode capacity degradation state, available lithium loss state, and positive electrode capacity degradation state are diagnosed sequentially), the control unit 120 can diagnose the battery state as unsuitable for use.

[0121] The above-described embodiments of the present invention may be realized not only by an apparatus and a method, but also by a program that realizes functions corresponding to the configuration of the embodiments of the present invention or a recording medium on which the program is recorded, and such realization can be easily realized by a person skilled in the art from the description of the above-described embodiments.

[0122] As described above, the present invention has been described using limited embodiments and drawings, but the present invention is not limited thereto, and it goes without saying that various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims.

[0123] Furthermore, the present invention described above can be variously replaced, modified, and changed by a person having ordinary knowledge in the technical field to which the present invention belongs, within the scope that does not deviate from the technical concept of the present invention, and is not limited to the above-described embodiments and the accompanying drawings, but can be configured by selectively combining all or part of each embodiment to enable various modifications. [Explanation of symbols]

[0124] 10: Battery pack 11: Battery 12: Measuring part 100: Battery diagnostic device 110: Profile acquisition unit 120: Control unit 130: Recording section 900: Electric vehicle 910: Battery pack 1000:ESS 1010: Battery rack 1020: Battery module

Claims

1. a profile acquisition unit configured to acquire a capacity profile for a constant current charging capacity and a constant voltage charging capacity measured during a charging process of the battery; a control unit configured to calculate a capacity change rate between the constant current charging capacity and the constant voltage charging capacity from the capacity profile, compare the calculated capacity change rate with a preset reference value, and diagnose a state of the battery based on a comparison result.

2. The control unit The battery diagnostic device according to claim 1 , configured to diagnose the state of the battery as a usable lithium loss state, a normal state, or a positive electrode capacity degradation state based on the comparison result.

3. The control unit If the capacity change rate is less than the reference value, the battery is diagnosed as being in a usable lithium loss state; If the capacity change rate is equal to the reference value, the battery is diagnosed as being in a normal state; The battery diagnostic device according to claim 2 , wherein the battery is diagnosed as being in a positive electrode capacity deterioration state if the capacity change rate exceeds the reference value.

4. The control unit 3. The battery diagnostic device according to claim 2, wherein the capacity profile is divided into one or more capacity sections according to a magnitude relationship between the capacity change rate and the reference value, and the battery state is diagnosed for each divided capacity section.

5. The control unit 5. The battery diagnostic device of claim 4, wherein the device is configured to calculate the capacity change rate for each of a plurality of constant current charging capacities included in the capacity profile, determine a target capacity from the plurality of constant current charging capacities at which a corresponding capacity change rate is equal to the reference value, and divide the capacity ranges based on the determined target capacity.

6. The control unit 5. The battery diagnostic device according to claim 4, wherein the battery is diagnosed as being unsuitable for use when the battery is sequentially diagnosed as being in the positive electrode capacity degraded state, the available lithium loss state, and the positive electrode capacity degraded state.

7. The control unit 3. The battery diagnostic device according to claim 2, wherein the device is configured to change a usage condition preset for the battery so as to correspond to the state of the battery.

8. The control unit When the battery state is diagnosed as the available lithium loss state, changing at least one of an upper limit of the charge C rate and a rest period preset for the battery; 8. The battery diagnostic device according to claim 7, wherein the device is configured to change at least one of an upper limit voltage and a maximum allowable temperature preset for the battery when the state of the battery is diagnosed as the positive electrode capacity degradation state.

9. The capacity profile may be:

2. The battery diagnostic device according to claim 1, wherein the profile is configured to accumulate and store a correspondence between a constant current charge capacity and a constant voltage charge capacity measured for each charge cycle of the battery.

10. A battery pack comprising the battery diagnostic device according to any one of claims 1 to 9.

11. a capacity profile acquiring step of acquiring a capacity profile for a constant current charge capacity and a constant voltage charge capacity measured during a charging process of the battery; a capacity change rate calculation step of calculating a capacity change rate between the constant current charging capacity and the constant voltage charging capacity from the capacity profile; a comparison step of comparing the calculated capacitance change rate with a preset reference value; and diagnosing the state of the battery based on the comparison result.

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