Battery diagnostic equipment, battery diagnostic system, battery pack and battery diagnostic method

Abstract

A battery diagnostic device according to one embodiment of the present invention includes: a measuring unit, which is used to measure the discharge capacity and temperature of a battery; an ohmic resistance determining unit, which is used to determine the ohmic resistance of the battery based on an impedance curve generated relative to the battery; and a control unit, which calculates a capacity change rate by comparing the discharge capacity of the battery measured by the measuring unit with a reference capacity, calculates a resistance change rate by comparing the ohmic resistance determined by the ohmic resistance determining unit with a reference resistance, determines an amount of internal gas generation of the battery by comparing the calculated resistance change rate with a standard resistance change rate, and determines a cause of internal gas generation of the battery by comparing the calculated capacity change rate with a standard capacity change rate.

Description

Technical Field

[0001] This application claims the benefit of Korean Patent Application No. 10-2020-0131451 filed in Korea on October 12, 2020, the disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to a battery diagnosis apparatus and method, and more particularly, to a battery diagnosis apparatus and method capable of diagnosing an internal gas generation level and a cause of the internal gas generation of a battery. Background Art

[0003] Recently, the demand for portable electronic products such as notebook computers, video cameras, and portable phones has increased dramatically, and electric vehicles, energy storage batteries, robots, satellites, etc. have also been vigorously developed. Therefore, high-performance batteries that allow repeated charge and discharge are being actively studied.

[0004] Currently commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium batteries, etc. Among them, lithium batteries have attracted much attention because they have almost no memory effect compared to nickel-based batteries, have a very low self-discharge rate, and have a high energy density.

[0005] As the battery degrades, various side reactions occur with the generation of internal gas. If the side reactions continue and the amount of internal gas exceeds the allowable value, the joints of the battery will open and the battery will reach the EOL (End of Life) state.

[0006] Therefore, in order to diagnose the state of the battery, it is necessary to measure the amount of internal gas. However, in the prior art, it is difficult to measure the amount of internal gas of the battery in a non-destructive manner. Summary of the invention

[0007] Technical issues

[0008] The present disclosure aims to solve the problems of the prior art, and thus the present disclosure aims to provide a battery diagnosis device and method for diagnosing the internal gas generation level and the internal gas generation cause of a battery in a non-destructive manner based on an impedance curve of the battery.

[0009] These and other purposes and advantages of the present disclosure can be understood from the following detailed description, and will become more apparent from the exemplary embodiments of the present disclosure. In addition, it will be easily understood that the purposes and advantages of the present disclosure can be achieved by the means shown in the appended claims and their combinations.

[0010] Technical Solution

[0011] A battery diagnostic device according to one aspect of the present disclosure may include: a measuring unit configured to measure a discharge capacity and a temperature of a battery; an ohmic resistance determining unit configured to determine the ohmic resistance of the battery based on an impedance curve generated for the battery; and a control unit configured to calculate a capacity change rate by comparing the discharge capacity of the battery measured by the measuring unit with a reference capacity, calculate a resistance change rate by comparing the ohmic resistance determined by the ohmic resistance determining unit with a reference resistance, judge a level of internal gas generation of the battery by comparing the magnitude of the calculated resistance change rate with the magnitude of a standard resistance change rate, and judge a cause of internal gas generation of the battery by comparing the magnitude of the calculated capacity change rate with the magnitude of a standard capacity change rate.

[0012] The ohmic resistance determination unit may be configured to determine the ohmic resistance based on the impedance curve generated for the battery when the temperature of the battery measured by the measurement unit is equal to or greater than a standard temperature during a predetermined period.

[0013] The battery may be configured to be maintained at the standard temperature or higher during the predetermined period, and then be fully charged at a first time point, and then be fully discharged at a second time point.

[0014] The measuring unit may be configured to measure a discharge capacity of the battery when the battery is fully charged at the first time point until it is fully discharged at the second time point.

[0015] The control unit may be configured to judge that an internal gas of the battery is generated in an amount equal to or greater than a standard amount when the calculated resistance change rate is equal to or greater than the standard resistance change rate.

[0016] The control unit may be configured to judge that the internal gas of the battery is generated in a smaller amount than the standard amount when the calculated resistance change rate is smaller than the standard resistance change rate.

[0017] The control unit may be configured to, when the calculated capacity change rate is equal to or greater than the standard capacity change rate, determine that the internal gas generation cause is a side reaction of the negative electrode of the battery.

[0018] The control unit may be configured to, when the calculated capacity change rate is less than the standard capacity change rate, determine that the internal gas generation cause is other than a side reaction of the negative electrode.

[0019] The control unit may be configured to diagnose a state of the battery based on the internal gas generation level and the internal gas generation cause.

[0020] The control unit may be configured to diagnose the state of the battery as a normal state when it is determined that the internal gas less than the standard amount is generated.

[0021] When it is determined that the internal gas equal to or greater than the standard amount is generated due to the other cause, the control unit may be configured to diagnose the state of the battery as a first warning state and reduce an upper limit temperature of the battery.

[0022] When it is determined that an amount of internal gas equal to or greater than the standard amount is generated due to a side reaction of the negative electrode, the control unit may be configured to diagnose the battery state as a second warning state and reduce at least one of an upper limit temperature and an upper limit C rate of the battery.

[0023] A battery diagnostic system according to another aspect of the present disclosure may include: a battery diagnostic device according to one aspect of the present disclosure; and an EIS unit, which is configured to output an alternating current to the battery, generate an impedance curve representing the impedance of the battery as a correspondence between a real part and an imaginary part based on the output result of the alternating current, and output the generated impedance curve to the battery diagnostic device.

[0024] The battery diagnosis system according to another aspect of the present disclosure may further include: a heating unit configured to increase the temperature of the battery so that the temperature of the battery becomes equal to or greater than a standard temperature; and a charge and discharge unit configured to charge and discharge the battery.

[0025] A battery pack according to still another aspect of the present disclosure may include the battery diagnosis device according to one aspect of the present disclosure.

[0026] A battery diagnosis method according to another aspect of the present disclosure may include: a temperature measuring step for measuring the temperature of a battery; an ohmic resistance determining step for determining the ohmic resistance of the battery based on an impedance curve generated for the battery; a discharge capacity measuring step for measuring the discharge capacity of the battery; a capacity change rate calculating step for calculating the capacity change rate by comparing the discharge capacity of the battery measured in the measuring step with a reference capacity; a resistance change rate calculating step for calculating the resistance change rate by comparing the ohmic resistance determined in the ohmic resistance determining step with a reference resistance; an internal gas generation level judging step for judging the internal gas generation level of the battery by comparing the calculated resistance change rate with the standard resistance change rate; and an internal gas generation cause judging step for judging the cause of internal gas generation of the battery by comparing the calculated capacity change rate with the standard capacity change rate.

[0027] Beneficial effects

[0028] According to one aspect of the present disclosure, the internal gas generation level and the internal gas generation cause of a battery may be diagnosed in a non-destructive manner.

[0029] The effects of the present disclosure are not limited to the above-mentioned effects, and other unmentioned effects will be clearly understood by those skilled in the art from the description of the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the foregoing disclosure, are used to provide a further understanding of the technical features of the present disclosure. Therefore, the present disclosure is not to be construed as being limited to the drawings.

[0031] Figure 1 is a diagram schematically showing a battery diagnosis apparatus according to one embodiment of the present disclosure.

[0032] Figure 2 is a diagram schematically showing an impedance curve according to one embodiment of the present disclosure.

[0033] Figure 3 is a graph showing one example of a capacity change rate calculated by a battery diagnosis apparatus according to one embodiment of the present disclosure.

[0034] Figure 4 is a graph showing one example of a resistance change rate calculated by a battery diagnosis apparatus according to one embodiment of the present disclosure.

[0035] Figure 5 is a diagram schematically showing a state of a battery diagnosed by a battery diagnosis apparatus according to one embodiment of the present disclosure.

[0036] Figure 6 is a diagram schematically showing a battery diagnosis system according to another embodiment of the present disclosure.

[0037] Figure 7 is a diagram showing an exemplary configuration of a battery pack including a battery diagnostic device according to one embodiment of the present disclosure.

[0038] Figure 8 is a diagram illustrating a battery diagnosis method according to still another embodiment of the present disclosure. DETAILED DESCRIPTION

[0039] It should be understood that the terms used in the specification and the appended claims should not be construed as limited to the general and dictionary meanings, but should be interpreted according to the meanings and concepts corresponding to the technical aspects of the present disclosure based on the principle of allowing the inventor to appropriately define the terms to obtain the best interpretation.

[0040] Therefore, the description presented herein is only a preferred embodiment for illustrative purposes and is not intended to limit the scope of the disclosure, and it should be understood that other equivalents and modifications may be made to the disclosure without departing from the scope of the disclosure.

[0041] Furthermore, in the description of the present disclosure, when it is deemed that a detailed description of related known elements or functions may obscure the key subject matter of the present disclosure, such detailed description is omitted herein.

[0042] Terms including ordinal numbers such as “first,” “second,” and the like may be used to distinguish one element from another of various elements, but are not intended to limit the elements by the terms.

[0043] Throughout the specification, when a portion is referred to as “comprising” or “including” any element, it means that the portion may further include other elements, without excluding other elements, unless specifically stated otherwise.

[0044] In addition, terms such as “control unit” described in this specification refer to a unit that processes at least one function or operation, which can be implemented by hardware, software, or a combination of hardware and software.

[0045] Furthermore, throughout the specification, when a part is referred to as being “connected to” another part, it is not limited to the case where they are “directly connected” but also includes the case where they are “indirectly connected” with another element interposed therebetween.

[0046] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0047] Figure 1 is a diagram schematically showing a battery diagnosis apparatus 100 according to one embodiment of the present disclosure.

[0048] refer to Figure 1 , a battery diagnosis apparatus 100 according to one embodiment of the present disclosure may include a measuring unit 110 , an ohmic resistance determining unit 120 , and a control unit 130 .

[0049] The measuring unit 110 may be configured to measure a discharge capacity and a temperature of the battery.

[0050] Here, a battery refers to a single independent battery that has a negative terminal and a positive terminal and is physically separable. For example, a pouch-type lithium polymer battery can be considered a battery. In addition, a battery can be a battery module in which one or more batteries are connected in series and / or in parallel. However, hereinafter, for ease of explanation, a battery will be described as referring to an independent battery.

[0051] For example, the measuring unit 110 may measure the discharge capacity of the battery within a predetermined time by measuring the discharge current of the battery.

[0052] In addition, the measuring unit 110 may be connected to the battery to measure the current temperature of the battery.

[0053] The ohmic resistance determination unit 120 may be configured to determine the ohmic resistance of the battery based on an impedance curve generated for the battery.

[0054] Figure 2 is a diagram schematically showing an impedance curve according to one embodiment of the present disclosure.

[0055] refer to Figure 2 , when X is set to the real part (Zre) and Y is set to the imaginary part (-Zim), the impedance curve can be expressed as an XY plane graph. Figure 2 In the embodiment of the present invention, the ohmic resistance (Ro) of the battery may be the starting resistance value of the impedance curve. Specifically, in the impedance curve, when the value of the imaginary part (-Zim) is 0, the resistance value of the real part (Zre) may be the ohmic resistance (Ro) of the battery. Since the ohmic resistance (Ro) is a well-known factor, it should be noted that the description of the ohmic resistance (Ro) will be omitted.

[0056] For example, the impedance curve of the battery may be generated outside the battery diagnostic apparatus 100. In addition, the ohmic resistance determination unit 120 may directly receive the externally generated impedance curve of the battery, or may acquire the impedance curve by accessing a memory storing the battery impedance curve.

[0057] Then, the ohmic resistance determination unit 120 may determine a starting resistance value according to the received impedance curve, and determine the determined starting resistance value as the ohmic resistance of the battery.

[0058] The control unit 130 may be configured to calculate a capacity change rate by comparing the discharge capacity of the battery measured by the measurement unit 110 with a reference capacity.

[0059] Here, the reference capacity may be the discharge capacity of the battery until the battery in the BOL (beginning of life) state changes from a fully charged state to a fully discharged battery. For example, the reference capacity may be the discharge capacity of the battery measured when the battery in the BOL state is discharged from 100% SOC (state of charge) to 0% SOC.

[0060] Specifically, the control unit 130 can calculate the capacity change rate of the battery by calculating the ratio of the difference between the reference capacity and the measured battery discharge capacity to the reference capacity. For example, the control unit 130 can calculate the capacity change rate of the battery by the calculation formula "(reference capacity-measured battery discharge capacity)÷reference capacity×100".

[0061] Figure 3 is a graph showing one example of a capacity change rate calculated by the battery diagnosis apparatus 100 according to one embodiment of the present disclosure.

[0062] For example, in Figure 3 In the embodiment of the present invention, the control unit 130 may calculate the capacity change rate of the first battery B1 to the fifth battery B5. Here, a reference capacity may be preset for each of the first battery B1 to the fifth battery B5. That is, a first reference capacity of the first battery B1 and a second reference capacity of the second battery B2 may be preset. In addition, a third reference capacity of the third battery B3 and a fourth reference capacity of the fourth battery B4 may be preset. In addition, a fifth reference capacity of the fifth battery B5 may be preset.

[0063] That is, the control unit 130 does not calculate the capacity change rate of the first battery B1 to the fifth battery B5 by using one preset reference capacity, but can calculate the capacity change rate of each of the first battery B1 to the fifth battery B5 by calculating the difference between the corresponding reference capacity and the measured battery discharge capacity. Therefore, the degree of degradation of each battery can be reflected in the capacity change rate of the battery calculated by the control unit 130.

[0064] For example, in Figure 3 In the embodiment of the present invention, the capacity change rate of the first battery B1 may be 3.17%, and the capacity change rate of the second battery B2 may be 2.5%. In addition, the capacity change rate of the third battery B3 may be 2.83%, and the capacity change rate of the fourth battery B4 may be 3.67%. In addition, the capacity change rate of the fifth battery B5 may be 6.33%.

[0065] The control unit 130 may be configured to calculate the resistance change rate by comparing the ohmic resistance determined by the ohmic resistance determination unit 120 with a reference resistance.

[0066] Here, the reference resistance may be a resistance value measured in advance for a battery in a BOL state. More preferably, the reference resistance may be an ohmic resistance value measured when the SOC (State of Charge) of the battery in the BOL state is 100%.

[0067] Specifically, the control unit 130 can calculate the resistance change rate of the battery by calculating the ratio of the difference between the reference resistance and the measured battery ohmic resistance to the reference resistance. For example, the control unit 130 can calculate the resistance change rate of the battery by calculating the formula "(measured battery ohmic resistance-reference resistance)÷reference resistance×100".

[0068] Figure 4is a graph showing one example of a resistance change rate calculated by the battery diagnosis apparatus 100 according to one embodiment of the present disclosure.

[0069] For example, in Figure 4 In an embodiment, the control unit 130 may calculate the resistance change rate of the first battery B1 to the fifth battery B5. As with the reference capacity, a reference resistance may also be preset for each of the first battery B1 to the fifth battery B5. That is, a first reference resistance of the first battery B1 and a second reference resistance of the second battery B2 may be preset. In addition, a third reference resistance of the third battery B3 and a fourth reference resistance of the fourth battery B4 may be preset. In addition, a fifth reference resistance of the fifth battery B5 may be preset. In addition, the control unit 130 may calculate the resistance change rate of each of the first battery B1 to the fifth battery B5 based on the corresponding reference resistance and the ohmic resistance of the battery.

[0070] For example, in Figure 4 In an embodiment of the present invention, the resistance change rate of the first battery B1 may be 16.4%, and the resistance change rate of the second battery B2 may be 17.1%. In addition, the resistance change rate of the third battery B3 may be 16.1%, and the resistance change rate of the fourth battery B4 may be 24.2%. In addition, the resistance change rate of the fifth battery B5 may be 25.2%.

[0071] The control unit 130 may be configured to determine the internal gas generation level of the battery by comparing the magnitude of the calculated resistance change rate and a standard resistance change rate.

[0072] Specifically, the control unit 130 may be configured to determine that the battery has generated an amount of internal gas equal to or greater than a standard amount when the calculated resistance change rate is equal to or greater than a standard resistance change rate. In addition, the control unit 130 may be configured to determine that the battery has generated an amount of internal gas less than a standard amount when the calculated resistance change rate is less than the standard resistance change rate. Here, the case where the battery generates an amount of internal gas less than a standard amount may include a case where the battery generates an amount of internal gas less than a standard amount and a case where no internal gas is generated.

[0073] For example, in Figure 4 In the embodiment of the present invention, it is assumed that the preset standard resistance change rate is 20%. Since the resistance change rate of the first battery B1 to the third battery B3 is less than the standard resistance change rate, the control unit 130 can judge that the first battery B1 to the third battery B3 generate less than the standard amount of internal gas. In addition, since the resistance change rate of the fourth battery B4 and the fifth battery B5 is greater than the standard resistance change rate, the control unit 130 can judge that the fourth battery B4 and the fifth battery B5 generate more than the standard amount of internal gas.

[0074] The control unit 130 may be configured to determine the cause of internal gas generation of the battery by comparing the calculated capacity change rate with a standard capacity change rate.

[0075] Specifically, the control unit 130 may be configured to, when the calculated capacity change rate is greater than or equal to the standard capacity change rate, determine that the cause of the internal gas generation is a side reaction of the negative electrode of the battery. More preferably, the control unit 130 may be configured to, when the calculated capacity change rate is greater than or equal to the standard capacity change rate, determine that the cause of the internal gas generation is a side reaction of the negative electrode of the battery and the electrolyte.

[0076] In addition, the control unit 130 may be configured to determine that the internal gas generation cause is other than the side reaction of the negative electrode when the calculated capacity change rate is less than the standard capacity change rate. For example, the other cause may include the side reaction of the positive electrode of the battery.

[0077] For example, in Figure 3 In the embodiment of the present invention, it is assumed that the preset standard capacity change rate is 5%. Since the capacity change rate of the first battery B1 to the fourth battery B4 is less than the standard capacity change rate, the control unit 130 can determine that the internal gas of the first battery B1 to the fourth battery B4 is caused by other reasons. In addition, since the capacity change rate of the fifth battery B5 is greater than the standard capacity change rate, the control unit 130 can determine that the internal gas of the fifth battery B5 is generated by the side reaction of the negative electrode of the corresponding battery.

[0078] That is, the battery diagnostic device 100 according to one embodiment of the present disclosure can determine whether the battery generates an internal gas equal to or greater than a standard amount, and can determine whether the internal gas of the battery is generated due to any side reaction. In particular, the battery diagnostic device 100 has the advantage of diagnosing in a non-destructive manner whether the internal gas of the battery is generated due to a side reaction of the negative electrode of the battery.

[0079] For example, when diagnosing the state of one or more batteries collected for reuse, the battery diagnostic device 100 according to one embodiment of the present disclosure can be used. The battery diagnostic device 100 can diagnose the internal gas generation level and the internal gas generation cause of each of the one or more batteries in a non-destructive manner. Therefore, according to one embodiment of the present disclosure, because the internal gas generation level and the internal gas generation cause of the battery can be quickly and easily diagnosed based on the ohmic resistance and discharge capacity of the battery, it is possible to quickly and accurately determine whether the collected battery is reusable.

[0080] Meanwhile, the control unit 130 provided to the battery diagnostic device 100 may optionally include a processor, an application specific integrated circuit (ASIC), another chipset, a logic circuit, a register, a communication modem, and a data processing device, etc., known in the art, to execute various control logics performed in the present disclosure. In addition, when the control logic is implemented in software, the control unit 130 may be implemented as a set of program modules. In this case, the program modules may be stored in a memory and executed by the control unit 130. The memory may be provided inside or outside the control unit 130, and may be connected to the control unit 130 by various well-known means.

[0081] In addition, reference Figure 1 The battery diagnostic device 100 may further include a storage unit 140. The storage unit 140 may store data or programs required for the operation and function of each component of the battery diagnostic device 100, data generated in the process of performing the operation or function, etc. The type of the storage unit 140 is not particularly limited as long as it is a known information storage means that can record, erase, update and read data. As an embodiment, the information storage means may include RAM, flash memory, ROM, EEPROM, registers, etc. In addition, the storage unit 140 may store program codes, in which processes that can be executed by the control unit 130 are defined.

[0082] For example, the storage unit 140 may store a reference capacity and a reference resistance of each battery. In addition, the storage unit 140 may store an impedance curve of the battery. In this case, the ohmic resistance determination unit 120 may access the storage unit 140 to obtain the impedance curve of the battery.

[0083] Preferably, the ohmic resistance determination unit 120 may be configured to determine the ohmic resistance based on an impedance curve generated for the battery when the temperature of the battery measured by the measurement unit 110 is equal to or greater than a standard temperature during a predetermined period.

[0084] Here, the predetermined period may be a minimum period during which the temperature of the battery must be maintained at a standard temperature or higher so that a change in the ohmic resistance of the battery can be related to the generation of the internal gas of the battery. That is, if the temperature of the battery is maintained at the standard temperature or higher only during too short a period, the generated battery internal gas may not have an obvious relationship with the change in the ohmic resistance of the battery. Therefore, in the present disclosure, by maintaining the temperature of the battery at the standard temperature or higher during the predetermined period, it is possible to make a judgment by associating the change in the ohmic resistance of the battery with the level of internal gas generation of the battery.

[0085] For example, the standard temperature may be set to any one of 40° C. to 60° C. Preferably, the standard temperature may be set to 40° C. Furthermore, the predetermined period may be set to any one of 3 days to 8 days. Preferably, the predetermined period may be set to 3 days.

[0086] As a specific embodiment, assuming that the standard temperature is set to 40° C. and the predetermined period is set to 3 days, when the battery temperature measured by the measuring unit 110 is maintained at 40° C. or higher for 3 days, the ohmic resistance determining unit 120 can determine the ohmic resistance of the corresponding battery by acquiring the impedance curve of the corresponding battery.

[0087] Generally speaking, as the SOC and temperature of the battery increase, the internal gas generation amount of the battery increases. That is, in order to diagnose the internal gas generation amount and the internal gas generation cause to determine whether the battery can be reused, the battery diagnosis device 100 according to one embodiment of the present disclosure can diagnose the battery maintained at a standard temperature or higher during a predetermined period of time.

[0088] In addition, preferably, the battery can be initially fully charged to a SOC 100% state. In addition, the fully charged battery can be maintained at a standard temperature or higher for a predetermined period of time. That is, during the predetermined period of time, the fully charged battery can be gradually discharged naturally, but the temperature of the battery can be configured to be maintained at a standard temperature or higher.

[0089] In addition, like the ohmic resistance determining unit 120, the measuring unit 110 can also measure the discharge capacity only for the battery whose temperature is maintained at the standard temperature or higher for a predetermined period of time, and the control unit 130 can diagnose the internal gas generation level and the cause of the internal gas generation only for the corresponding battery.

[0090] Here, after the battery is maintained at a standard temperature or higher for a predetermined period of time, the battery may be fully charged again at a first time point, and may be configured to be fully discharged at a second time point after the battery is fully charged at the first time point. Preferably, the measuring unit 110 may be configured to measure the discharge capacity of the battery when the battery is fully charged at the first time point until it is fully discharged at the second time point.

[0091] For example, as in the previous embodiment, after the battery temperature is maintained at 40° C. or higher for 3 days, the battery can be fully charged to SOC 100% at a first time point. In addition, at a second time point later than the first time point, the battery can be fully discharged to SOC 0%. The measuring unit 110 can measure the discharge capacity of the battery from the first time point to the second time point. In addition, the control unit 130 can calculate the capacity change rate of the battery based on the discharge capacity measured by the measuring unit 110. That is, the control unit 130 can calculate the loss rate of the irreversible capacity of the battery.

[0092] That is, only when a fully charged battery is maintained at a standard temperature or higher for a predetermined period of time to create a test environment in which internal gas of the battery may be generated, the battery diagnostic apparatus 100 will determine whether internal gas of the battery is generated, and if so, due to what reasons the internal gas of the battery is generated.

[0093] Hereinafter, one embodiment in which the battery diagnosis apparatus 100 diagnoses a battery state according to an internal gas generation level and an internal gas generation cause of a diagnosed battery will be described in detail.

[0094] The control unit 130 may be configured to diagnose the state of the battery based on the internal gas generation level and the internal gas generation cause.

[0095] Hereinafter, for the convenience of explanation, the state of the battery that can be judged by the control unit 130 is divided into a normal state, a first warning state, and a second warning state. However, the state of the battery that can be judged by the control unit 130 can be further subdivided according to the internal gas generation level of the battery and the cause of the internal gas generation. For example, the control unit 130 can specifically subdivide and diagnose the internal gas generation level of the battery by comparing the calculated resistance change rate of the battery with the standard resistance range divided into multiple sections. In addition, the control unit 130 can compare the calculated capacity change rate of the battery with the standard capacity range divided into multiple capacity sections to further subdivide and diagnose the cause of the internal gas generation of the battery. In addition, it should be noted that the state of the battery can be specifically diagnosed in more aspects by subdividing and diagnosing the internal gas generation level and the cause of the internal gas generation.

[0096] Figure 5 is a diagram schematically showing a state of a battery diagnosed by the battery diagnosis apparatus 100 according to one embodiment of the present disclosure.

[0097] refer to Figure 5 , the control unit 130 may be configured to diagnose the battery state as a normal state when it is determined that the internal gas is generated in an amount less than a standard amount.

[0098] That is, even if a fully charged battery is at a standard temperature or higher for a predetermined period of time, if less than a standard amount of internal gas is generated, the control unit 130 can diagnose the battery state as a normal state. In addition, the control unit 130 can classify the battery as a reusable battery.

[0099] In addition, reference Figure 5When it is determined that the internal gas equal to or greater than the standard amount is generated due to other reasons, the control unit 130 may be configured to diagnose the state of the battery as the first warning state. In addition, the control unit 130 may classify the battery as a reusable battery.

[0100] Thereafter, the control unit 130 may be configured to lower the upper limit temperature of the battery to reduce the amount of internal gas generation of the battery diagnosed as the first warning state. That is, the battery diagnosed as the first warning state may be set to lower the allowable upper limit temperature by the control unit 130. That is, when the battery diagnosed as the first warning state is reused, the allowable upper limit temperature of the battery may be limited to the temperature set by the control unit 130.

[0101] In addition, reference Figure 5 The control unit 130 may be configured to diagnose the battery state as the second warning state when it is determined that the internal gas equal to or greater than the standard amount is generated by the side reaction of the negative electrode. In addition, the control unit 130 may classify the battery as a reusable battery.

[0102] Thereafter, the control unit 130 may be configured to reduce at least one of the upper limit temperature and the upper limit C rate of the battery to reduce the amount of internal gas generated by the battery diagnosed as the second warning state. That is, the battery diagnosed as the second warning state may be set by the control unit 130 so as to reduce at least one of the allowable upper limit temperature and the allowable upper limit C rate. Preferably, the control unit 130 may simultaneously reduce the upper limit temperature and the upper limit C rate of the battery so as to effectively reduce the amount of internal gas generated by the battery diagnosed as the second warning state. That is, when the battery diagnosed as the second warning state is reused, at least one of the allowable upper limit temperature and the upper limit C rate of the corresponding battery may be limited to the value set by the control unit 130.

[0103] Specifically, the control unit 130 may diagnose the state of the battery having an internal gas generation level equal to or greater than a standard amount as a warning state, and lower the upper limit temperature and / or the upper limit C rate to reduce the internal gas generation amount.

[0104] In summary, the control unit 130 can classify the battery diagnosed as a normal state, a first warning state, or a second warning state as a reusable battery. In addition, the control unit 130 can reduce the amount of internal gas generated when the battery is reused by appropriately restricting the operation of the battery diagnosed as the first warning state or the second warning state.

[0105] Therefore, the battery diagnostic device 100 according to one embodiment of the present disclosure can diagnose the state of the battery by focusing on whether the battery is reusable based on the internal gas generation level of the battery and the internal gas generation cause. In addition, in order to reduce the generation of internal gas during reuse, the operation of each battery can be limited based on the diagnosed state. Therefore, the battery diagnostic device 100 has the advantage that it can not only determine whether the battery is reusable, but also set appropriate control conditions so that the battery can be used for a longer period of time.

[0106] Figure 6 is a diagram schematically showing a battery diagnosis system 10 according to another embodiment of the present disclosure.

[0107] refer to Figure 5 , the battery diagnosis system 10 may include an EIS unit 200 and a battery diagnosis apparatus 100 according to one embodiment of the present disclosure.

[0108] The EIS unit 200 may be configured to output an alternating current to the battery, and generate an impedance curve representing the impedance of the battery as a corresponding relationship between a real part (Zre) and an imaginary part (-Zim) according to the output result of the alternating current.

[0109] Specifically, the EIS unit 200 may be configured to perform EIS (electrochemical impedance spectroscopy). Therefore, the EIS unit 200 may apply a small alternating current to the battery to measure the impedance of the battery and generate an impedance curve representing the impedance as a correspondence between a real part (Zre) and an imaginary part (-Zim).

[0110] For example, when the temperature of the battery is equal to or higher than the standard temperature, the battery impedance measured by the EIS unit 200 may be inaccurate due to the influence of temperature. Therefore, the EIS unit 200 may measure the impedance of the battery when the temperature of the battery becomes close to the room temperature.

[0111] The EIS unit 200 may be configured to output the generated impedance curve to the battery diagnostic apparatus 100 .

[0112] For example, the EIS unit 200 may transmit the generated impedance curve to the ohmic resistance determination unit 120 of the battery diagnostic apparatus 100 .

[0113] As another embodiment, the EIS unit 200 may transmit the generated impedance curve to the storage unit 140 of the battery diagnosis apparatus 100. In this case, the ohmic resistance determination unit 120 may access the storage unit 140 to acquire the impedance curve generated by the EIS unit 200.

[0114] In addition, refer to Figure 6 , the battery diagnosis system 10 may further include a heating unit 300 and a charge and discharge unit 400 .

[0115] The heating unit 300 may be configured to increase the temperature of the battery so that the temperature of the battery is equal to or higher than the standard temperature. That is, the heating unit 300 may increase and maintain the temperature of the battery so that the temperature of the battery may be maintained at the standard temperature or higher for a predetermined period of time.

[0116] The charge and discharge unit 400 may be configured to be connected to a battery so as to charge or discharge the battery.

[0117] For example, the battery may be fully charged by the charge and discharge unit 400 at an initial time point. In addition, the temperature of the battery may be maintained at a standard temperature or higher by the heating unit 300 within a predetermined period of time. The charge and discharge unit 400 may fully charge the battery again at the first time point after the predetermined period of time. That is, the SOC of the battery at the first time point may be 100%. In addition, at a second time point later than the first time point, the charge and discharge unit 400 may fully discharge the battery. That is, the SOC of the battery at the second time point may be 0%. The measuring unit 110 may measure the discharge capacity of the battery from the first time point to the second time point. In addition, the control unit 130 may diagnose the level of internal gas generation, the cause of internal gas generation, and the state of the battery.

[0118] Therefore, the battery diagnosis system 10 has an advantage of diagnosing whether a battery is reusable by satisfying the test conditions that may generate the internal gas of the battery.

[0119] On the other hand, in preparation for determining that the battery internal gas is generated in an amount equal to or greater than the standard amount, and the cause of the internal gas generation is diagnosed as a cause other than the side reaction of the negative electrode, the battery diagnostic device 100 may perform additional diagnosis to specifically determine the cause of the internal gas generation of the battery. That is, in preparation for determining that the state of the battery is the first warning state, the battery diagnostic device 100 may perform additional diagnosis to specifically diagnose the cause of the internal gas generation of the battery.

[0120] The measuring unit 110 may be configured to further measure the voltage of the battery. Preferably, the measuring unit 110 may measure the voltage of the battery maintained at a standard temperature or higher for a predetermined period of time. More preferably, the measuring unit 110 may measure the OCV (open circuit voltage) of the battery.

[0121] The control unit 130 may be configured to calculate the voltage variation amount by comparing the battery voltage measured by the measurement unit 110 with a reference voltage.

[0122] Here, the reference voltage may be a voltage value pre-measured for a battery in a BOL state. More preferably, the reference voltage may be an OCV value measured when the SOC of the battery in the BOL state is 100%.

[0123] Specifically, the control unit 130 can calculate the voltage variation of the battery by calculating the difference between the reference voltage and the measured voltage of the battery. For example, the control unit 130 can calculate the voltage variation of the battery by calculating the formula "reference voltage - measured voltage of the battery".

[0124] In addition, if the calculated voltage variation is greater than or equal to the standard voltage variation, the control unit 130 may be configured to determine that the internal gas generation of the battery is caused by a side reaction of the positive electrode.

[0125] Furthermore, the control unit 130 may be configured to diagnose the battery state as a third warning state when determining that the battery internal gas equal to or greater than the standard amount is generated due to the side reaction of the positive electrode. Furthermore, the control unit 130 may classify the battery as a reusable battery.

[0126] Thereafter, the control unit 130 may be configured to reduce at least one of the upper limit temperature and the upper limit SOC of the battery to reduce the amount of internal gas generation of the battery diagnosed as the third warning state. That is, the battery diagnosed as the third warning state may be set by the control unit 130 to reduce at least one of the allowable upper limit temperature and the upper limit SOC. That is, when the battery diagnosed as the third warning state is reused, the allowable upper limit temperature and / or the upper limit SOC of the battery may be limited to the value set by the control unit 130.

[0127] The battery diagnostic device 100 according to the present disclosure may be applied to a BMS (battery management system). That is, the BMS according to the present disclosure may include the above-mentioned battery diagnostic device 100. In this configuration, at least some components of the battery diagnostic device 100 may be implemented by supplementing or increasing configuration functions included in a conventional BMS.

[0128] In addition, the battery diagnostic device 100 according to the present disclosure may be provided to a battery pack. That is, the battery pack according to the present disclosure may include the above-mentioned battery diagnostic device 100 and at least one battery. In addition, the battery pack may further include electrical devices (relays, fuses, etc.) and a housing.

[0129] Figure 7 is a diagram schematically showing an exemplary configuration of a battery pack 1 according to another embodiment of the present disclosure. Figure 7 , the battery pack 1 may include a battery diagnosis device 100 , an EIS unit 200 , a heating unit 300 , and a charge and discharge unit 400 . That is, the battery pack 1 may include a battery diagnosis system 10 .

[0130] For example, in Figure 7In an embodiment of the present invention, the battery diagnostic apparatus 100 may be connected to the first to fourth sensing lines SL1 to SL4. Preferably, the first to fourth sensing lines SL1 to SL4 may be connected to the measuring unit 110 of the battery diagnostic apparatus 100.

[0131] The measuring unit 110 may measure the temperature of the battery B via the first sensing line SL1 .

[0132] In addition, the measuring unit 110 can measure the positive discharge capacity of the battery B via the second sensing line SL2, and measure the negative discharge capacity of the battery B via the third sensing line SL3. In addition, the measuring unit 110 can measure the discharge capacity of the battery B by calculating the difference between the measured positive discharge capacity and negative discharge capacity of the battery B.

[0133] In addition, the measuring unit 110 may be connected to the current measuring element A via the fourth sensing line SL4. Here, the current measuring element A may be a current system or a shunt resistor. Therefore, the measuring unit 110 may measure the current of the battery B via the fourth sensing line SL4. Figure 7 An embodiment is shown, in which, as a preferred embodiment, the current measuring element A is arranged between the negative electrode of the battery B and the negative terminal P- of the battery pack 1, but the current measuring element A can also be arranged between the positive electrode of the battery B and the positive terminal P+ of the battery pack 1.

[0134] One end of the EIS unit 200 may be connected between the positive terminal P+ of the battery pack 1 and the positive electrode of the battery B, and the other end may be connected between the negative terminal P- of the battery pack 1 and the negative electrode of the battery B. In addition, the EIS unit 200 may measure the impedance of the battery B after outputting a tiny alternating current. Thereafter, the EIS unit 200 may generate an impedance curve of the battery B and transmit it to the battery diagnostic device 100.

[0135] One end of the heating unit 300 may be connected to the positive electrode of the battery B, and the other end may be connected to the negative electrode of the battery B. In addition, the operation of the heating unit 300 is controlled by the battery diagnostic apparatus 100 (particularly the control unit 130), and when the heating unit 300 operates, the temperature of the battery B may increase.

[0136] One end of the charge and discharge unit 400 may be connected to the positive terminal P+ of the battery pack 1, and the other end may be connected to the negative terminal P- of the battery pack 1. In another embodiment, similar to the heating unit 300, one end of the charge and discharge unit 400 may be directly connected to the positive electrode of the battery B, and the other end may be directly connected to the negative electrode of the battery B. The operation of the charge and discharge unit 400 may be controlled by the battery diagnostic device 100 (particularly the control unit 130), and when the charge and discharge unit 400 operates, the battery B may be charged or discharged.

[0137] For example, the battery B may be fully charged by the charge and discharge unit 400. In addition, the temperature of the battery B may be maintained at a standard temperature or higher for a predetermined period of time by means of the heating unit 300. Thereafter, the internal gas generation level, the internal gas generation cause, and the state of the battery B may be diagnosed by the battery diagnostic apparatus 100.

[0138] Figure 8 is a diagram illustrating a battery diagnosis method according to still another embodiment of the present disclosure.

[0139] Here, each step of the battery diagnosis method may be performed by the battery diagnosis apparatus 100. Hereinafter, for the convenience of explanation, contents overlapping with the previously described contents will be briefly described or omitted.

[0140] refer to Figure 8 According to one embodiment of the present disclosure, a battery diagnosis method may include a temperature measuring step (S100), an ohmic resistance determining step (S200), a discharge capacity measuring step (S300), a capacity change rate calculating step (S400), a resistance change rate calculating step (S500), an internal gas generation level judging step (S600), and an internal gas generation cause judging step (S700).

[0141] The temperature measuring step ( S100 ) is a step of measuring the battery temperature and may be performed by the measuring unit 110 .

[0142] For example, refer to Figure 1 and Figure 7 , the measuring unit 110 may be connected to the battery via the first sensing line SL1. In addition, the measuring unit 110 may measure the temperature of the battery via the first sensing line SL1.

[0143] The ohmic resistance determining step ( S200 ) is a step of determining the ohmic resistance of the battery based on the impedance curve generated for the battery, and may be performed by the ohmic resistance determining unit 120 .

[0144] For example, the ohmic resistance determination unit 120 may directly receive an impedance curve generated for the battery from the outside, or may access the storage unit 140 to obtain the impedance curve stored in the storage unit 140. In addition, the ohmic resistance determination unit 120 may determine the ohmic resistance of the battery according to the impedance curve.

[0145] Preferably, the ohmic resistance determination unit 120 may determine the ohmic resistance only for the battery whose battery temperature measured by the measurement unit 110 is equal to or greater than the standard temperature and this state is maintained for a predetermined period of time.

[0146] The discharge capacity measurement step ( S300 ) is a step of measuring the discharge capacity of the battery, and may be performed by the measurement unit 110 .

[0147] Preferably, the battery whose temperature is maintained at the standard temperature or higher during the predetermined period can be fully charged again after the predetermined period. Thereafter, the fully charged battery can be fully discharged. The measuring unit 110 can measure the discharge capacity of the battery when the fully charged battery is fully discharged.

[0148] For example, refer to Figure 1 and Figure 7 , the measuring unit 110 may be connected to the current measuring element A via the fourth sensing line SL4. In addition, the measuring unit 110 may measure the discharge capacity of the battery by means of the current measuring element A.

[0149] The capacity change rate calculation step ( S400 ) is a step of calculating the capacity change rate by comparing the discharge capacity of the battery measured in the discharge capacity measurement step ( S300 ) with a reference capacity, and may be performed by the control unit 130 .

[0150] For example, the control unit 130 may calculate the capacity change rate of the battery by a calculation formula of “(reference capacity−measured discharge capacity of the battery)÷reference capacity×100”.

[0151] The resistance change rate calculation step ( S500 ) is a step of calculating the resistance change rate by comparing the ohmic resistance determined in the ohmic resistance determination step ( S200 ) with a reference resistance, and may be performed by the control unit 130 .

[0152] For example, the control unit 130 may calculate the resistance change rate of the battery by a calculation formula of “(determined ohmic resistance−reference resistance)÷reference resistance×100”.

[0153] The internal gas generation level judging step ( S600 ) is a step of judging the internal gas generation level of the battery by comparing the calculated resistance change rate with the standard resistance change rate, and may be performed by the control unit 130 .

[0154] For example, if the calculated resistance change rate is greater than or equal to the standard resistance change rate, the control unit 130 can determine that the internal gas of the battery equal to or greater than the standard amount is generated. Conversely, if the calculated resistance change rate is less than the standard resistance change rate, the control unit 130 can determine that the internal gas of the battery less than the standard amount is generated.

[0155] The internal gas generation cause determination step ( S700 ) is a step of determining the internal gas generation cause of the battery by comparing the calculated capacity change rate with the standard capacity change rate, and may be performed by the control unit 130 .

[0156] For example, if the calculated capacity change rate is greater than or equal to the standard capacity change rate, the control unit 130 may determine that the internal gas of the battery is generated due to the side reaction of the negative electrode of the battery. Conversely, if the calculated capacity change rate is less than the standard capacity change rate, the control unit 130 may determine that the internal gas of the battery is caused by other reasons other than the side reaction of the negative electrode of the battery.

[0157] In addition, although Figure 8 Although not shown, the battery diagnosis method may further include a battery state diagnosis step after the internal gas generation cause determination step (S700).

[0158] The battery state diagnosis step is a step of diagnosing the state of the battery based on the internal gas generation level and the internal gas generation cause, and may be performed by the control unit 130 .

[0159] refer to Figure 5 , the control unit 130 may diagnose the state of the battery as a normal state, a first warning state, or a second warning state based on the internal gas generation level and the internal gas generation cause.

[0160] For example, the control unit 130 may classify a battery diagnosed as a normal state, a first warning state, or a second warning state as a reusable battery. In addition, the control unit 130 may reduce the amount of internal gas generated by the battery when the battery is reused by appropriately restricting the operation of the battery diagnosed as the first warning state or the second warning state.

[0161] Furthermore, after the battery state diagnosis step, only when the battery is judged to be in the first warning state, an additional diagnosis step may be performed to more specifically confirm the cause of internal gas generation of the battery.

[0162] The additional diagnosis step is a step of diagnosing whether the cause of the gas generation inside the battery is a side reaction of the positive electrode, and can be performed by the control unit 130 .

[0163] The embodiments of the present disclosure described above cannot be implemented only by devices and methods, but can also be implemented by a program that implements functions corresponding to the configuration of the embodiments of the present disclosure or a recording medium that records the program. The program or recording medium can be easily implemented by a person of ordinary skill in the art based on the description of the embodiments described above.

[0164] The present disclosure has been described in detail. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the present disclosure, are given by way of illustration only, as various changes and modifications within the scope of the present disclosure will become apparent to those skilled in the art based on the detailed description.

[0165] In addition, those skilled in the art may make many substitutions, modifications and changes to the present disclosure described above without departing from the technical aspects of the present disclosure, and the present disclosure is not limited to the above-mentioned embodiments and drawings, and each embodiment may be selectively combined in part or in whole to achieve various variations.

[0166] (reference numerals)

[0167] 1: Battery Pack

[0168] 10: Battery diagnostic system

[0169] 100: Battery diagnostic equipment

[0170] 110: Measurement unit

[0171] 120: Ohm resistance determination unit

[0172] 130: Control unit

[0173] 140: Storage unit

[0174] 200: EIS unit

[0175] 300: Heating unit

[0176] 400: Charge and discharge unit

Claims

1. A battery diagnostic device, comprising: a measuring unit configured to measure a discharge capacity and a temperature of a battery; an ohmic resistance determination unit configured to determine the ohmic resistance of the battery based on an impedance curve generated for the battery; as well as a control unit configured to calculate a capacity change rate by comparing the discharge capacity of the battery measured by the measuring unit with a reference capacity, calculate a resistance change rate by comparing the ohmic resistance determined by the ohmic resistance determining unit with a reference resistance, judge the internal gas generation level of the battery by comparing the magnitude of the calculated resistance change rate with the magnitude of a standard resistance change rate, and judge the cause of the internal gas generation of the battery by comparing the magnitude of the calculated capacity change rate with the magnitude of the standard capacity change rate.

2. The battery diagnostic device according to claim 1, in, The ohmic resistance determination unit is configured to determine the ohmic resistance based on the impedance curve generated for the battery when the temperature of the battery measured by the measurement unit is equal to or greater than a standard temperature during a predetermined period, the predetermined period being a minimum period during which the temperature of the battery must be maintained at the standard temperature or higher so that a change in the ohmic resistance of the battery is related to generation of internal gas of the battery.

3. The battery diagnostic device according to claim 2, in, The battery is configured to be maintained at the standard temperature or higher during the predetermined period, then fully charged at a first time point, and then fully discharged at a second time point, and The measuring unit is configured to measure a discharge capacity of the battery from being fully charged at the first time point to being fully discharged at the second time point.

4. The battery diagnostic device according to claim 1, in, The control unit is configured to, when the calculated resistance change rate is equal to or greater than the standard resistance change rate, determine that the battery generates an internal gas equal to or greater than a standard amount, and The control unit is configured to determine that the battery has generated an amount of internal gas less than the standard amount when the calculated resistance change rate is less than the standard resistance change rate.

5. The battery diagnostic device according to claim 4, in, The control unit is configured to, when the calculated capacity change rate is equal to or greater than the standard capacity change rate, determine that the internal gas generation cause is a side reaction of the negative electrode of the battery, and The control unit is configured to determine that the internal gas generation cause is other than a side reaction of the negative electrode when the calculated capacity change rate is less than the standard capacity change rate.

6. The battery diagnostic device according to claim 5, in, The control unit is configured to diagnose a state of the battery based on the internal gas generation level and the internal gas generation cause.

7. The battery diagnostic device according to claim 6, in, The control unit is configured to diagnose the state of the battery as a normal state when it is determined that the internal gas less than the standard amount is generated.

8. The battery diagnostic device according to claim 6, in, When it is determined that the internal gas equal to or greater than the standard amount is generated due to the other cause, the control unit is configured to diagnose the state of the battery as a first warning state and reduce an upper limit temperature of the battery.

9. The battery diagnostic device according to claim 6, in, When it is determined that an amount of internal gas equal to or greater than the standard amount is generated due to a side reaction of the negative electrode, the control unit is configured to diagnose the state of the battery as a second warning state and reduce at least one of an upper limit temperature and an upper limit C rate of the battery.

10. A battery diagnostic system, comprising: The battery diagnostic device according to any one of claims 1 to 9; as well as The EIS unit is configured to output an alternating current to the battery, generate an impedance curve representing the impedance of the battery as a correspondence between a real part and an imaginary part according to the output result of the alternating current, and output the generated impedance curve to the battery diagnostic device.

11. The battery diagnosis system according to claim 10, further comprising: a heating unit configured to increase the temperature of the battery so that the temperature of the battery becomes equal to or greater than a standard temperature; as well as A charge and discharge unit is configured to charge and discharge the battery.

12. The battery diagnosis system according to claim 11, in, The heating unit is configured to maintain the temperature of the battery at the standard temperature or higher for a predetermined period of time, wherein the predetermined period of time is a minimum period of time during which the temperature of the battery must be maintained at the standard temperature or higher so that a change in the ohmic resistance of the battery is related to the generation of internal gas of the battery.

13. The battery diagnosis system according to claim 12, in, The charge and discharge unit is configured to fully charge the battery at a first time point after the predetermined period of time has elapsed, and then fully discharge the battery at a second time point later than the first time point.

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

15. A battery diagnosis method, the battery diagnosis method comprising: A temperature measuring step for measuring the temperature of the battery; an ohmic resistance determining step for determining the ohmic resistance of the battery based on an impedance curve generated for the battery; A discharge capacity measuring step, which is used to measure the discharge capacity of the battery; a capacity change rate calculation step for calculating a capacity change rate by comparing the discharge capacity of the battery measured in the measuring step with a reference capacity; a resistance change rate calculation step for calculating the resistance change rate by comparing the ohmic resistance determined in the ohmic resistance determination step with a reference resistance; an internal gas generation level judging step for judging the internal gas generation level of the battery by comparing the magnitude of the calculated resistance change rate with the magnitude of a standard resistance change rate; and The step of judging the cause of internal gas generation is used to judge the cause of internal gas generation of the battery by comparing the calculated capacity change rate with the standard capacity change rate.

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