Battery capacity recovery device and battery capacity recovery method

Abstract

A battery capacity recovery device and a battery capacity recovery method are provided. The battery capacity recovery device includes a sensing unit configured to measure a voltage and a current of a battery, and a control unit configured to determine an electrical state of the battery based on time series data of the voltage and the current of the battery. The control unit is configured to sequentially execute a first capacity recovery routine and a second capacity recovery routine when execution of a capacity recovery process is determined according to the electrical state of the battery. The first capacity recovery routine is a process of discharging the battery until the SOC of the battery drops to a reference SOC. The second capacity recovery routine is a process of resting the battery for a reference time or more from the completion of the first capacity recovery routine.

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for restoring at least a portion of the diminished capacity of a rechargeable battery.

[0002] This application claims priority to Korean Patent Application No. 10-2022-0139218 filed on October 26, 2022 and Korean Patent Application No. 10-2023-0113145 filed on August 28, 2023, the entire contents of which are incorporated herein by reference in their entirety in the specification and drawings. [Background technology]

[0003] In recent years, as the 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 progressed in earnest, research into high-performance batteries that can be repeatedly charged and discharged is being actively conducted.

[0004] Currently commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Among them, 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] Among various types of rechargeable batteries, lithium-sulfur batteries have been attracting attention in recent years. Lithium-sulfur batteries contain a sulfur-based material with a sulfur-sulfur bond (SS bond) as a positive electrode active material and lithium metal as a negative electrode active material. Sulfur, the main material of the positive electrode active material, has the advantages of being abundant in resources around the world, non-toxic, and having a low atomic weight.

[0006] In addition, the application areas of various types of rechargeable batteries are expanding to electric vehicles (EVs) and energy storage systems (ESSs), and lithium-sulfur batteries are advantageous in achieving a high energy storage density (~2,600Wh / kg) relative to weight compared to lithium-ion batteries.

[0007] In general, rechargeable batteries, including lithium-sulfur batteries, gradually deteriorate as they are repeatedly charged and discharged. Specifically, the full charged capacity (FCC) of the battery gradually decreases as the charge and discharge cycles are repeated. That is, the amount of energy available when a degraded battery is fully charged (i.e., the dischargeable capacity) is relatively lower than the amount of energy available when a new battery is fully charged.

[0008] Such a decrease in dischargeable capacity reduces the usage time and driving distance of a load such as an electronic device or an electric vehicle, and therefore there is a need to develop a technology that can restore the decreased dischargeable capacity of a deteriorated battery. Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been devised to solve the above problems, and aims to provide a battery capacity recovery device and method that performs a capacity recovery process to recover at least a portion of the full charge capacity that has been reduced due to deterioration, depending on the electrical state of the battery.

[0010] Other objects and advantages of the present invention can be understood from the following description and will become more apparent from the embodiments of the present invention. Also, the objects and advantages of the present invention can be realized by the means and combinations thereof as set forth in the claims. [Means for solving the problem]

[0011] A battery capacity recovery device according to an aspect of the present invention includes a sensing unit configured to measure a voltage and a current of a battery, and a control unit configured to determine an electrical state of the battery based on time series data of the voltage and the current of the battery. The control unit is configured to determine whether to execute a capacity recovery process including a first capacity recovery routine and a second capacity recovery routine according to the electrical state of the battery. When it is determined to execute the capacity recovery process, the control unit is configured to sequentially execute the first capacity recovery routine and the second capacity recovery routine. The first capacity recovery routine is a process of discharging the battery until the SOC (State of Charge) of the battery drops to a reference SOC. The second capacity recovery routine is a process of resting the battery for a reference time or more from the completion of the first capacity recovery routine.

[0012] At least one of the reference SOC and the reference time may be predetermined.

[0013] The reference SOC may be 0% or more and less than 20%. The reference time may be 10 hours or more.

[0014] The control unit may be configured to determine at least one of a reference constant current, the reference SOC, and the reference time associated with the first capacity recovery routine based on a full charge capacity of the battery.

[0015] The control unit may be configured to determine the reference constant current from first relationship data in which a predetermined positive correspondence relationship between the full charge capacity and the reference constant current is defined.

[0016] The control unit may be configured to determine the reference SOC from second relationship data in which a predetermined positive correspondence relationship between the full charge capacity and the reference SOC is defined.

[0017] The control unit may be configured to determine the reference time from third relationship data in which a predetermined negative correspondence relationship between the full charge capacity and the reference time is defined.

[0018] The control unit may be configured to execute the capacity recovery process under the condition that an increase in the cumulative discharge capacity of the battery since the completion of the previous capacity recovery process is equal to or greater than a reference capacity and that the battery is in a resting state.

[0019] The controller may be configured to determine the reference capacity based on a full charge capacity of the battery.

[0020] The control unit may be configured to execute the capacity recovery process under the condition that the decrease in the full charge capacity of the battery since the completion of the previous capacity recovery process is equal to or greater than a critical capacity and that the battery is in a hibernation state.

[0021] The battery may include lithium metal as an active anode material and sulfur as an active cathode material.

[0022] A battery pack according to another aspect of the present invention includes the battery capacity recovery device.

[0023] An electric vehicle according to yet another aspect of the present invention includes the battery pack.

[0024] A battery control method according to another aspect of the present invention includes the steps of: determining an electrical state of the battery based on time-series data of the voltage and current of the battery; determining whether to execute a capacity recovery process including a first capacity recovery routine and a second capacity recovery routine according to the electrical state of the battery; performing the first capacity recovery routine when it is determined to execute the capacity recovery process; and performing the second capacity recovery routine in response to completion of the first capacity recovery routine. The first capacity recovery routine is a step of discharging the battery until the SOC of the battery drops to a reference SOC. The second capacity recovery routine is a step of resting the battery for a reference time or more from the completion of the first capacity recovery routine. Effect of the Invention

[0025] According to one aspect of the present invention, a capacity recovery process for a battery can be performed to recover at least a portion of the full charge capacity of the battery that has been reduced due to various causes such as repeated charging and discharging from a new state, etc. In particular, the capacity recovery process can be effectively applied to lithium-sulfur batteries.

[0026] Additionally, according to one aspect of the present invention, the service life of a battery can be extended by preemptively performing a capacity recovery process before the end of the battery's service life.

[0027] In addition, according to one aspect of the present invention, after determining whether or not a capacity recovery process needs to be performed based on the electrical condition of the battery, the capacity recovery process is performed only when necessary, thereby eliminating the side effect of the battery deteriorating more quickly due to excessive execution of the capacity recovery process.

[0028] In addition, according to one aspect of the present invention, by adjusting at least one control parameter (such as a reference constant current described below) related to the capacity recovery process in accordance with the electrical state of the battery, it is possible to minimize the accelerated deterioration caused by the discharge process of the capacity recovery process, thereby slowing down the rate of deterioration of the battery.

[0029] 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.

[0030] The following drawings attached to this specification, together with the detailed description of the invention described below, serve to further understand the technical ideas of the present invention, and the present invention should not be interpreted as being limited only to the matters described in the drawings. [Brief description of the drawings]

[0031] [Figure 1] 1 is a diagram illustrating a schematic configuration of a battery capacity recovery device according to an embodiment of the present invention; [Diagram 2] 1 is a flow chart illustrating a battery capacity recovery method according to a first embodiment of the present invention; [Diagram 3] 4 is a graph to explain the difference in battery life characteristics depending on whether or not a capacity recovery process according to an embodiment of the present invention is applied; [Figure 4] FIG. 5 is a flow chart illustrating a battery capacity recovery method according to a second embodiment of the present invention. [Diagram 5] FIG. 5 is a flow chart illustrating a battery capacity recovery method according to a third embodiment of the present invention. [Figure 6] FIG. 10 is a flow chart illustrating a battery capacity recovery method according to a fourth embodiment of the present invention. [Figure 7] 1 is a diagram showing an example of the exterior of an electric vehicle according to an embodiment of the present invention; [Figure 8] FIG. 8 is a diagram illustrating a schematic configuration of the electric vehicle illustrated in FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, the terms and words used in the present specification and claims should not be interpreted as being limited to their ordinary and dictionary meanings, but should be interpreted as having meanings and concepts corresponding to the technical ideas of the present invention, in accordance with the principle that the inventor himself can appropriately define the concepts of terms in order to best describe the invention.

[0033] Therefore, it should be understood that the embodiment described in this specification and the configurations shown in the drawings are merely the most preferred embodiment 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 therefor at the time of this application.

[0034] Terms including ordinal numbers such as first, second, etc. are used to distinguish one of various components from other components, and are not intended to limit the components.

[0035] Throughout the specification, when a part "includes" a certain component, this does not mean to exclude other components, but means that other components may be further included, unless otherwise specified. Furthermore, terms such as "controller" described in the specification refer to a unit that processes at least one function or operation, and may be embodied in hardware, software, or a combination of hardware and software.

[0036] 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" through other elements.

[0037] FIG. 1 is a diagram illustrating a schematic configuration of a battery capacity recovery device according to an embodiment of the present invention.

[0038] Referring to FIG. 1, a battery capacity recovery device 100 includes a sensing unit 110, a control unit 120, and a recording unit .

[0039] 1, the sensing unit 110 and the control unit 120 are illustrated as separate components, but this is merely an example, and in various embodiments, two or more components may be integrated together to operate. Also, in the following description, at least some of the functions described as being realized by a certain component may also be realized by other components.

[0040] Here, the battery means a single independent cell that has a negative terminal and a positive terminal and can be physically separated.

[0041] As an example, the battery may be a lithium ion battery or a lithium polymer battery. Here, the battery may have various structures depending on the type of positive electrode active material. For example, the battery may be formed with at least one of a layered structure, a spinel structure, and an olivine structure. The battery may be a battery to which a positive electrode active material having a layered structure is applied. For example, the battery may be a battery to which an NCM-based positive electrode active material is applied. As another example, the battery may be a battery to which a positive electrode active material having an olivine structure is applied. For example, the battery may be a battery to which an LFP-based positive electrode active material is applied.

[0042] Preferably, the battery may include lithium metal as the negative electrode active material and sulfur as the positive electrode active material.

[0043] Herein, the battery may refer to a battery module in which a plurality of cells are connected in series and / or parallel, but for the sake of convenience, the battery will be described below as referring to a single independent cell.

[0044] The sensing unit 110 may be configured to detect at least one battery parameter (e.g., voltage, current) indicative of the electrical condition of the battery, which may include various characteristics indicative of the battery's usage, physical condition, chemical condition, etc.

[0045] The control unit 120 may be operatively coupled to other components of the battery capacity recovery device 100 , such as the sensing unit 110 and the recording unit 130 , and may control various operations of the battery capacity recovery device 100 .

[0046] The control unit 120 may execute one or more instructions to perform various operations of the battery capacity recovery device 100. The control unit 120 may selectively include a processor, an application-specific integrated circuit (ASIC), 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 logics are 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 the recording unit 130 and executed by the control unit 120.

[0047] The controller 120 may perform a capacity recovery process for the battery depending on the electrical condition of the battery. The controller 120 may be configured to perform a capacity recovery process that can recover at least a portion of the capacity loss of a degraded battery depending on the electrical condition of the battery.

[0048] As an example of a capacity recovery process that can be executed by the control unit 120, a first charging operation for charging the battery to a first reference SOC, a discharging operation for discharging the battery below the reference SOC after the first charging operation, a hibernation operation for maintaining the battery in a hibernation state for a hibernation time equal to or greater than a reference time after the discharging operation, and a second charging operation for recharging the battery to a third reference SOC after the hibernation operation may be sequentially performed.

[0049] The recording unit 130 may store data and programs necessary for each component of the battery capacity recovery device 100 to operate and function, or data generated in the process of performing the operation and function. The recording unit 130 may be provided inside or outside the control unit 120 and may be connected to the control unit 120 by various known means. The recording unit 130 may store at least one program, application, data, or instruction executed by the control unit 120. There is no particular limit to the type of the recording unit 130 as long as it is a known information recording means known to be capable of recording, erasing, updating, and reading data. The recording unit 130 may be implemented in at least one form of a flash memory, a hard disk, a solid state disk (SSD), a solid disk drive (SDD), a multimedia micro card, a random access memory (RAM), a static RAM (SRAM), a read only memory (ROM), an electrically erasable programmable ROM (EEPROM), and a programmable ROM (PROM), but the present invention is not limited to such a specific form of the recording unit 130. In addition, the recording unit 130 may store program code in which processes executable by the control unit 120 are defined.

[0050] In addition, the recording unit 130 may store information regarding a preset reference capacity and / or a preset reference number of cycles to determine whether to perform the capacity restoration process, which will be described in detail in the following embodiments.

[0051] 2 is a flow chart showing a battery capacity recovery method according to a first embodiment of the present invention, which can be performed by the battery capacity recovery device 100 shown in FIG.

[0052] 2, the capacity recovery process of the battery may include a first charging operation (S210), a discharging operation (S220), a resting operation (S230), and a second charging operation (S240). The discharging operation (S220) and the resting operation (S230) may correspond to required routines of the capacity recovery process, and the first charging operation (S210) and the second charging operation (S240) may correspond to optional routines that can be omitted in the capacity recovery process. The discharging operation (S220) and the resting operation (S230) may be referred to as a first capacity recovery routine and a second capacity recovery routine, respectively.

[0053] In step S210, the control unit 120 may drive the charger (see FIG. 8) to charge the battery until the SOC of the battery rises to a first reference SOC. Here, the first reference SOC may be a value that is determined in advance and stored in the recording unit 130, etc. If the SOC of the battery is already equal to or higher than the first reference SOC, step S210 may not be performed.

[0054] Specifically, the control unit 120 may be operably coupled to a charger and a discharger provided outside the battery capacity recovery device 100. Alternatively, the control unit 120 may be configured to open and close a charging switch of the battery pack. The control unit 120 may then charge the battery by controlling the charger and / or the charging switch. The charger may be configured to supply charging power to the battery constantly during operation or upon request of the control unit 120.

[0055] In step S220, the control unit 120 may drive the discharge device to discharge the battery until the SOC of the battery drops to a second reference SOC. Here, the second reference SOC may be a value that is predetermined and stored in the recording unit 130 or the like. In particular, the second reference SOC may be set to a value significantly lower than the first reference SOC for the first charging operation (step S210). For example, the second reference SOC may be 70% or more lower than the first reference SOC.

[0056] The control unit 120 may control a discharge switch of the discharge device and / or the battery pack to discharge the battery. The discharge device may be configured to receive discharge power from the battery at all times during operation or upon request of the control unit 120.

[0057] The control unit 120 may determine the full charge capacity of the battery based on the SOC change amount and the discharge capacity of the battery in step S220.

[0058] In step S230, the control unit 120 may stop both the charger and the discharge device (eg, the inverter 30 in FIG. 8) to allow the battery to rest for a reference time or longer.

[0059] Specifically, the control unit 120 may interrupt both charging and discharging of the battery for a reference time or more from the completion point of step S220 to maintain the battery in a hibernation state. To this end, the control unit 120 may control a charge switch or a discharge switch of a charger or a battery pack.

[0060] In step S240, the control unit 120 may drive the charger to recharge the battery so that the SOC of the battery increases to a third reference SOC. Here, the third reference SOC may be a value that is predetermined and stored in the recording unit 130, etc. For example, the third reference SOC may be set to 90%.

[0061] The battery capacity recovery method shown in FIG. 2 has the technical effect of slowing down the deterioration rate of the battery. In particular, a battery gradually deteriorates due to repeated charging and discharging, and battery deterioration means a decrease in dischargeable capacity (full charge capacity). According to this embodiment, the capacity recovery process can restore the battery capacity to a certain level or higher. Therefore, the deterioration rate due to battery use can be effectively slowed down. This can have the effect of extending the life of the battery and the device in which the battery is installed, such as an electric vehicle or an energy storage system (ESS).

[0062] When the battery is a lithium-sulfur battery, the effect of capacity recovery by applying the method shown in Figure 2 is even more excellent. In the case of a lithium-sulfur battery, when the battery is charged to a first reference SOC, then discharged below the second reference SOC described above, and then subjected to a rest period of at least a reference time, the ratio of sulfur-containing species (e.g., Li2S, S, polysulfides, etc.) to each other naturally and appropriately redistributes within and on the positive and negative electrodes.

[0063] Specifically, when the above-mentioned capacity recovery process is performed on a battery, the ratio of sulfur-containing species, such as sulfur (S), polysulfides, and lithium sulfide (Li2S), contained in the electrodes and electrolyte of a deteriorated battery may be redistributed by spontaneous chemical reactions. In the process of redistribution of the ratio of sulfur-containing species, sulfur-containing species that have become irreversible and cannot be expressed due to deterioration of the battery may be changed to a reversible state again. The sulfur-containing species that have been changed to a reversible state again in this way can provide usable energy in subsequent charge and discharge cycles. The battery capacity recovery device 100 can obtain additional dischargeable capacity that was previously unavailable for a deteriorated battery.

[0064] At least one of the first reference SOC and the third reference SOC may be set to 100%. That is, the control unit 120 may be configured to fully charge the battery until the SOC of the battery reaches 100% as the first charging operation (step S210). Also, the control unit 120 may be configured to charge the battery until the SOC of the battery reaches 100% from the second reference SOC as the second charging operation (step S240). In particular, the control unit 120 may fully charge the battery in both the first charging operation and the second charging operation. In this case, the second charging operation may be a re-full charging process following the first charging operation as a full charging process.

[0065] In particular, when a battery is recharged to a SOC of 100% after a rest period of a reference time or more, not only is capacity recovery due to the rest period, but additional capacity recovery due to the recharge process occurs, and this capacity recovery effect can be sustained in charge / discharge cycles after the method shown in Fig. 2 is completed. That is, the full charge capacity recovered by the capacity recovery process is not only recovered once at the corresponding charge or discharge stage, but is sustained in charge / discharge cycles after the capacity recovery process is performed. Therefore, a battery to which the capacity recovery process is applied can store a relatively larger amount of usable energy than before the capacity recovery process is performed.

[0066] The second reference SOC related to the discharging operation (S220) may be a value that is predetermined to be within a range of SOC 20% or less.

[0067] As an example, the second reference SOC for the discharging operation (S220) may be set to 20%. In this case, the control unit 120 may discharge the battery until the SOC of the battery drops to the second reference SOC. If the SOC of the battery reaches 20% during the discharging operation (S220), the control unit 120 may end the discharging operation and perform the hibernation operation (S230).

[0068] As another example, the second reference SOC for the discharging operation (S220) may be set to 0%. In this case, when the battery SOC reaches a fully discharged state where the battery SOC is 0%, the control unit 120 may end the discharging operation and execute the hibernation operation (S230).

[0069] In the pause operation (S230), the reference time is the minimum time during which both charging and discharging of the battery are maintained in a suspended state, and may be stored in advance in the recording unit 130 or the like. In particular, the pause time may be set to be 1 hour or longer. Preferably, the pause time may be set to be 10 hours or longer. Furthermore, the pause time may be set to be 20 hours or longer. According to the present embodiment, by providing a sufficiently long pause period, it is possible to appropriately redistribute the ratio between sulfur-containing chemical species.

[0070] The operation of the control unit 120 to execute the capacity recovery process according to the electrical state of the battery will now be described in more detail with reference to the drawings.

[0071] The control unit 120 may monitor the usage history of the battery based on the time series of each battery parameter collected from the sensing unit 110. The usage history of the battery may include the number of charge / discharge cycles and / or the accumulated discharge capacity.

[0072] Meanwhile, battery deterioration is usually caused by an increase in at least one of the number of charge / discharge cycles and the cumulative discharge capacity of the battery. Therefore, the number of charge / discharge cycles or the cumulative discharge capacity of the battery may be used as an index representing the deterioration state of the battery. In this manner, the control unit 120 may monitor the electric state of the battery in real time based on a time series of at least one type of battery parameter collected from the sensing unit 110, and perform a capacity recovery process according to the monitored electric state. Hereinafter, the control unit 120 performing the above-mentioned capacity recovery process based on the usage history of the battery will be described in detail.

[0073] Specifically, the control unit 120 may determine the cumulative discharge capacity of the battery for any period based on time series data of at least one battery parameter collected from the sensing unit 110. As an example, the sensing unit 110 may include a current sensor. The control unit 120 may periodically collect a current signal indicating a current detected by the sensing unit 110 and record the time series data of the current as a battery parameter in the recording unit 130. In addition, the control unit 120 may be configured to determine the cumulative discharge capacity for any period from the time series data of the current.

[0074] For example, the sensing unit 110 outputs a current signal indicating the current detected during a predetermined time or a predetermined number of charge / discharge cycles (or a predetermined interval) to the control unit 120, and the control unit 120 can recognize the cumulative discharge capacity by integrating the current value indicated by the current signal.

[0075] In a beginning of life (BOL) state where the battery can be considered as new, the degree of deterioration of the battery is small, so the control unit 120 does not need to execute a capacity recovery process on the battery. In addition, frequent application of the capacity recovery process is not preferable because the capacity recovery process may cause deterioration of the battery. Therefore, the control unit 120 can apply the capacity recovery process at an optimal time point and improve the capacity recovery effect of the capacity recovery process by determining in advance whether or not to apply the capacity recovery process to the battery based on the accumulated discharge capacity from a specific point in the past. For example, the control unit 120 can determine the accumulated discharge capacity of the battery from the completion point of the previous capacity recovery process to the current time point, and estimate the degree of deterioration of the battery during the same period based on the accumulated discharge capacity.

[0076] Specifically, the control unit 120 may compare the total number of charge / discharge cycles of the battery with a plurality of cycle sections and determine which of the plurality of cycle sections the current total number of charge / discharge cycles belongs to. For reference, the number of charge / discharge cycles of the battery may increase by 1 each time the total accumulated discharge capacity from the time of delivery of the battery increases by the design capacity of the battery. The control unit 120 may calculate the accumulated discharge capacity of the battery in each cycle section.

[0077] The control unit 120 may calculate the cumulative discharge capacity of the battery for each cycle section. For example, when the total number of charge / discharge cycles of the battery belongs to the first cycle section of the multiple cycle sections, the control unit 120 may determine the cumulative discharge capacity of the battery in the first cycle section. Assuming that x is the number of cycle sections and y is a natural number less than x, the size of the (y+1)th cycle section may be equal to or smaller than the size of the yth cycle section. For example, the first cycle section may be a section in which the total number of charge / discharge cycles is 0 to 100, and the second cycle section may be a section in which the total number of charge / discharge cycles is 101 to 190.

[0078] The electrical condition of the battery at a particular time may include a total accumulated discharge capacity from the time the battery was delivered to the particular time. The controller 120 may be configured to execute a capacity recovery process each time the electrical condition of the battery meets a predetermined set of conditions.

[0079] Even after the capacity recovery process is performed once on the battery, the capacity of the battery may deteriorate again as the battery is used. Therefore, the control unit 120 may conditionally execute the capacity recovery process based on at least one of the set of conditions including: (i) an increase in the total accumulated discharge capacity is equal to or greater than a reference capacity; and (ii) an increase in the accumulated discharge capacity since the completion of the previous capacity recovery process is equal to or greater than a reference capacity. Through the repeatedly executed capacity recovery process, the control unit 120 may recover the available energy of the battery.

[0080] The reference capacity may be predetermined to be equal to a value obtained by multiplying the design capacity by a predetermined reference multiple. The design capacity may be a fully charged capacity of the battery at the time of leaving the warehouse, and may be a predetermined value. The reference capacity may be determined, for example, within a range of 1 to 200 times the design capacity. Preferably, the reference capacity may be predetermined to be 5 to 70 times the design capacity. More preferably, the reference capacity may be predetermined to be 10 to 20 times the design capacity. According to this embodiment, the reference capacity is set equal to a predetermined multiple of the design capacity, so that the deterioration state of the battery can be more easily estimated. Therefore, the control unit 120 can easily determine whether or not to execute the above-mentioned capacity recovery process depending on whether the electrical state of the battery satisfies the set of conditions.

[0081] Alternatively, the control unit 120 may set a reference capacity to be compared with the cumulative discharge capacity from the completion time of the previous capacity recovery process to the current time for re-execution of the capacity recovery process. The control unit 120 may optimize the timing of re-execution of the capacity recovery process according to the total cumulative discharge capacity corresponding to the electrical state of the battery.

[0082] Specifically, the control unit 120 may set the reference capacity, which is a reference for whether or not to perform the capacity recovery process, to a relatively large value as the electrical state of the battery is closer to the BOL state, and may set the reference capacity related to the capacity recovery process to be subsequently performed to a relatively small value. For example, the control unit 120 may be configured to perform a first capacity recovery process and a second capacity recovery process on the battery. The control unit 120 may set the first reference capacity for determining whether or not to perform the first capacity recovery process and the second reference capacity for determining whether or not to perform the second capacity recovery process to be different.

[0083] The control unit 120 may set the reference capacity for determining whether to execute the capacity recovery process to at least two or more different values ​​depending on the number of times of the capacity recovery process. For example, the control unit 120 may set the reference capacity for determining whether to execute the first capacity recovery process for the battery after delivery to a value corresponding to 66 times the design capacity of the battery. In this case, since the reference capacity is 14.52 Ah when the design capacity of the battery is 0.22 Ah, the control unit 120 may determine that the first capacity recovery process needs to be executed in response to the total cumulative discharge capacity of the battery from the time of delivery being 14.52 Ah or more. The reference capacity related to the second capacity recovery process may be 14 times the design capacity, which is less than the reference capacity related to the first capacity recovery process. In this case, the control unit 120 may determine that the second capacity recovery process needs to be executed in response to the cumulative discharge capacity from the time of completion of the first capacity recovery process being 3.08 Ah, which is 14 times the design capacity. If w is a natural number equal to or greater than 1 indicating the number of times of the capacity recovery process, the reference capacity associated with the wth capacity recovery process may be predetermined to be equal to or less than the reference capacity associated with the (w-1)th capacity recovery process.

[0084] The control unit 120 may compare the cumulative discharge capacity from the completion of the (w-1)th capacity recovery process with a reference capacity associated with the wth capacity recovery process. The control unit 120 may determine that the wth capacity recovery process needs to be performed if the cumulative discharge capacity from the completion of the (w-1)th capacity recovery process is equal to or greater than the reference capacity associated with the wth capacity recovery process. In a state in which the wth capacity recovery process needs to be performed, the control unit 120 may start the wth capacity recovery process in response to the electrical state of the battery being switched from a charging state or a discharging state to a resting state.

[0085] FIG. 3 is a graph to be referred to in order to explain the difference in the life characteristics of a battery depending on whether or not the capacity restoration process according to an embodiment of the present invention is applied.

[0086] In the graph of FIG. 3, the x-axis indicates the number of charge / discharge cycles of the battery, and the y-axis indicates the full charge capacity, which is expressed in Ampere hours (Ah). The charge / discharge cycle includes a charging process of charging the battery from 1.8V to 2.5V at a constant current of 0.3C, and a discharging process of discharging the battery from 2.5V to 1.8V at a constant current of 2.0C. A predetermined rest time may be provided between the discharging process of the preceding charge / discharge cycle and the charging process of the following charge / discharge cycle. The full charge capacity related to a specific charge / discharge cycle may be an average of one or two of the charge capacity due to the charge process and the discharge capacity due to the discharge process of the corresponding charge / discharge cycle.

[0087] Each of the multiple cycle sections (section 1 to section 4) exemplarily shown in FIG. 3 has a predetermined size. Section 1 is a section in which the number of charge / discharge cycles is 87 or less, and has a size of 87. Section 2 is a section in which the number of charge / discharge cycles is 88 to 107, and has a size of 20. Section 3 is a section in which the number of charge / discharge cycles is 108 to 127, and has a size of 20. Section 4 is a section in which the number of charge / discharge cycles is 128 to 147, and has a size of 20.

[0088] The control unit 120 may calculate the cumulative discharge capacity in each of the multiple cycle sections and determine whether the cumulative discharge capacity in a specific cycle section is equal to or greater than a reference capacity associated with the specific cycle section. Since the control unit 120 calculates the cumulative discharge capacity for each cycle section, when the capacity recovery process is completed in the specific cycle section, the control unit 120 may initialize the cumulative discharge capacity in the specific cycle section to 0 Ah.

[0089] Specifically, when the execution of the capacity recovery process is completed in the preceding cycle section of the two adjacent cycle sections, the control unit 120 may initialize the accumulated discharge capacity and calculate the accumulated discharge capacity from the initialization point. For example, the control unit 120 executes the first capacity recovery process when the total number of charge / discharge cycles of the battery reaches the upper limit cycle number of section 1 (number of charge / discharge cycles=87). Thereafter, the control unit 120 may monitor whether the accumulated discharge capacity from the time when the total number of charge / discharge cycles of the battery is equal to the lower limit cycle number of section 2 (number of charge / discharge cycles=88) reaches the reference capacity of 3.08 Ah. The control unit 120 may execute the second capacity recovery process under the condition that the accumulated discharge capacity is equal to or greater than the reference capacity of 3.08 Ah and that the total number of charge / discharge cycles has reached the upper limit cycle number of section 2 (number of charge / discharge cycles=107). The control unit 120 may monitor whether the accumulated discharge capacity from the time when the total number of charge / discharge cycles of the battery is equal to the lower limit cycle number of section 3 (number of charge / discharge cycles=108) reaches the reference capacity of 3.08 Ah. The control unit 120 may execute a third capacity recovery process under the condition that the cumulative discharge capacity is equal to or greater than the reference capacity of 3.08 Ah and the total number of charge / discharge cycles has reached the upper limit number of cycles in section 3 (number of charge / discharge cycles=127). Thereafter, the control unit 120 may monitor whether the cumulative discharge capacity from the point in time when the total number of charge / discharge cycles of the battery is equal to the lower limit number of cycles in section 4 (number of charge / discharge cycles=128) has reached the reference capacity of 3.08 Ah. The control unit 120 may execute a fourth capacity recovery process under the condition that the cumulative discharge capacity is equal to or greater than the reference capacity of 3.08 Ah and the total number of charge / discharge cycles has reached the upper limit number of cycles in section 4 (number of charge / discharge cycles=147).

[0090] In this way, the control unit 120 can initialize the cumulative discharge capacity every time the capacity recovery process is performed, and accurately recognize the time when the next capacity recovery process is to be performed. Hereinafter, the control unit 120 will be described for performing the above-mentioned capacity recovery process based on the number of charge / discharge cycles of the battery.

[0091] The control unit 120 may recognize the total number of charge / discharge cycles of the battery based on the total accumulated discharge capacity since the time of leaving the warehouse. As an example, the sensing unit 110 may recognize the number of charge / discharge cycles (or charge / discharge cycles) of the battery, where one charge and one discharge of the battery is one cycle. The control unit 120 may recognize whether the total number of charge / discharge cycles or an increase in the total number of charge / discharge cycles from a specific time point has reached a predetermined reference number of cycles. In response to the total number of charge / discharge cycles or an increase in the total number of charge / discharge cycles from a specific time point being equal to or greater than the predetermined reference number of cycles, the control unit 120 may determine that a capacity recovery process needs to be applied to the battery.

[0092] The control unit 120 may determine that the capacity recovery process needs to be performed when the total number of charge / discharge cycles of the battery reaches a predetermined reference number. The control unit 120 may determine that the capacity recovery process needs to be performed when the increase in the total number of charge / discharge cycles from the time point when the previous capacity recovery process is completed reaches a predetermined reference number. That is, the capacity recovery process may be repeatedly applied at different times depending on the changing electrical conditions throughout the life of the battery.

[0093] The control unit 120 may determine that the battery needs to be restored to its capacity if the total number of charge / discharge cycles of the battery reaches a reference cycle number in a preset reference cycle list. The reference cycle list may be a data table in which different reference cycle numbers (e.g., 100, 120, 140, 160, 170) are recorded.

[0094] The control unit 120 may adaptively control the timing of executing the capacity recovery process according to the electrical state of the battery. That is, the closer the electrical state of the battery is to the BOL state, the less the degree of deterioration. The control unit 120 may determine the time to re-execute the capacity recovery process according to the total number of charge / discharge cycles of the battery.

[0095] Specifically, as the battery deteriorates from the BOL state, the control unit 120 may shorten the time interval between capacity recovery processes (i.e., the time difference between the completion of the previous capacity recovery process and the start of a new capacity recovery process) by reducing the reference cycle number used to determine the need to execute a capacity recovery process.

[0096] The control unit 120 may set at least two different reference cycle numbers to repeatedly execute the capacity recovery process according to the deterioration state of the battery. For example, the control unit 120 may execute a first capacity recovery process when the total number of charge / discharge cycles of the battery reaches 87 (the upper limit number of cycles of section 1), and then execute a new capacity recovery process every time the total number of charge / discharge cycles increases by 20.

[0097] The control unit 120 may be configured to change the execution cycle of the capacity recovery process. Specifically, the deterioration rate of the battery gradually increases with use. For example, the degree of deterioration of the battery at the same number of charge / discharge cycles is greater when the battery is in a Middle of Life (MOL) state than when it is in a BOL state, and is greater when the battery is in an End of Life (EOL) state than when it is in an MOL state. Therefore, the control unit 120 may set the execution cycle of the capacity recovery process to be gradually shorter as the battery deteriorates.

[0098] For example, the control unit 120 may perform an initial capacity recovery process when the total number of charge / discharge cycles is equal to 87, and may re-perform the capacity recovery process every time the total number of charge / discharge cycles increases by 20 until the total number of times the capacity recovery process has been performed reaches a first critical number (e.g., 10). Thereafter, the control unit 120 may re-perform the capacity recovery process every time the total number of charge / discharge cycles increases by 10 until the total number of times the capacity recovery process has been performed reaches a second critical number (e.g., 30). According to this embodiment, the re-perform cycle of the capacity recovery process may be shortened as the deterioration of the battery accelerates, thereby maximizing the capacity recovery effect of the battery.

[0099] Hereinafter, in order to more clearly explain the effect of the charge / discharge control of a battery according to an embodiment of the present invention, examples and comparative examples will be described. However, the examples according to the present invention may be modified in various ways, and the scope of the present invention should not be construed as being limited to the following examples. The examples of the present invention are provided to more completely explain the present invention to those skilled in the art.

[0100] Referring to FIG. 3, a graph showing the relationship between the full charge capacity and the number of charge / discharge cycles of the battery according to Example 1 of the present invention and a graph showing the relationship between the full charge capacity and the number of charge / discharge cycles of the battery according to Comparative Example 1 can be seen.

[0101] [Comparative Example 1] The battery was repeatedly subjected to a charge-discharge cycle in which (1) a charge process, (2) a discharge process, and (3) a rest process were sequentially performed, as defined below.

[0102] 1) Charging process: Charge at a constant current of 0.3C until the battery voltage rises from 1.8V to 2.5V (or SOC 0% to 100%). 2) Discharge process: Discharge at a constant current of 2.0C until the battery voltage drops from 2.5V to 1.8V (or SOC100% to 0%). 3) Rest period: Stop charging and discharging for 1 minute

[0103] [Example 1] A battery of the same type and specifications as in Comparative Example 1 was prepared, and the same charge / discharge cycle as in Comparative Example 1 was repeated. Comparative Example 1 differs in that the capacity recovery process was performed a total of four times in which the first rest process according to 3-1) was replaced with the second rest process according to 3-2), on the condition that the total number of charge / discharge cycles reached 87, 107, 127, and 147, respectively.

[0104] 1) Charging process: Charge at a constant current of 0.3C until the battery voltage rises from 1.8V to 2.5V (or SOC 0% to 100%). 2) Discharge process: Discharge at a constant current of 2.0C until the battery voltage drops from 2.5V to 1.8V (or SOC100% to 0%). 3-1) First resting step: Stop charging and discharging for 1 minute 3-2) Second resting period: Stop charging and discharging for 20 hours

[0105] That is, in Example 1, the first capacity recovery process is the 88th charge / discharge cycle, the second capacity recovery process is the 108th charge / discharge cycle, the third capacity recovery process is the 128th charge / discharge cycle, and the fourth capacity recovery process is the 148th charge / discharge cycle.

[0106] The total of four charge-discharge cycles as the capacity recovery process applied to the battery according to Example 1 differ from that of Comparative Example 1 in that it includes 1) a charging process, 2) a discharging process, and 3-2) a second resting process.

[0107] 3, in section 1 where the capacity recovery process is not performed, the change in full charge capacity in Example 1 is substantially equal to the change in full charge capacity in Comparative Example 1.

[0108] On the other hand, the capacity of the battery according to Example 1 is recovered by the first capacity recovery process corresponding to the lower limit cycle number 88 of Section 2, so that the full charge capacity of the battery according to Example 1 is much larger than the full charge capacity of the battery according to Comparative Example 1 over the entire range of Section 2.

[0109] Similarly, the second capacity recovery process corresponding to the lower limit cycle number 108 of section 3 partially recovers the battery capacity that decreased in section 2, so that the full charge capacity of the battery according to Example 1 is much greater than that of the battery according to Comparative Example 1 over the entire range of section 3. It can also be seen that in sections 3 and 4, respectively, the full charge capacity of the battery according to Example 1 is maintained greater than that of the battery according to Comparative Example 1, as a capacity recovery effect of the third capacity recovery process and the fourth capacity recovery process. In other words, the battery capacity recovery device 100 according to the present invention repeatedly executes the capacity recovery process for the battery at appropriate intervals, thereby improving the life characteristics of the battery.

[0110] Hereinafter, the capacity recovery effect by performing a total of four capacity recovery processes will be specifically described with reference to Tables 1 and 2.

[0111] Table 1 shows the increase rate of full charge capacity before and after the application of a total of four capacity recovery processes to the battery according to Example 1. The increase rate of full charge capacity may also be referred to as the "capacity recovery rate." For example, if the full charge capacity increases from A to B through the capacity recovery process, the recovered capacity is "BA" and the capacity recovery rate is "(BA) / A x 100%."

[0112] [Table 1]

[0113] According to Table 1, as a result of performing the first capacity recovery process at 88 charge / discharge cycles, the capacity recovery was about 3.76% compared to the full charge capacity at 87 charge / discharge cycles. In addition, the full charge capacity immediately after performing the second capacity recovery process at 108 charge / discharge cycles was increased by about 3.16% compared to the full charge capacity at 107 charge / discharge cycles. In addition, the full charge capacity immediately after performing the third capacity recovery process at 128 charge / discharge cycles was increased by about 2.81% compared to the full charge capacity at 127 charge / discharge cycles. In addition, the full charge capacity immediately after performing the fourth capacity recovery process at 148 charge / discharge cycles was increased by about 1.95% compared to the full charge capacity at 147 charge / discharge cycles. According to the experimental results of Example 1, it can be confirmed that the capacity of the battery was partially recovered and the dischargeable capacity was increased each time the capacity recovery process was performed.

[0114] In addition, the increased usable capacity is not only effective for the corresponding charge / discharge cycle, but can also be maintained in subsequent charge / discharge cycles, which can be seen from the results of measuring the full charge capacity of the battery according to Comparative Example 1 and the battery according to Example 1 as the charge / discharge cycle progresses.

[0115] Table 2 shows a comparison of the life characteristics of the battery according to Example 1 and the life characteristics of the battery according to Comparative Example 1.

[0116] [Table 2]

[0117] In Table 2, the numerical value of each cell indicates the full charge capacity. Referring to Table 2, according to Example 1, it is confirmed that the full charge capacity in the 87th charge / discharge cycle before the first capacity recovery process is applied is 0.154 Ah, and the average full charge capacity in section 2 (88th charge / discharge cycle to 107th charge / discharge cycle) is 0.155 Ah. Also, according to Example 1, it is confirmed that the full charge capacity in the 107th charge / discharge cycle before the second capacity recovery process is applied is 0.151 Ah, and the average full charge capacity in section 3 (108th charge / discharge cycle to 127th charge / discharge cycle) is 0.152 Ah. Also, according to Example 1, it is confirmed that the full charge capacity in the 127th charge / discharge cycle before the third capacity recovery process is applied is 0.150 Ah, and the average full charge capacity in section 4 (128th charge / discharge cycle to 147th charge / discharge cycle) is 0.151 Ah.

[0118] In contrast, in Comparative Example 1, in which the capacity recovery process was not applied even once, a continuous decrease in full charge capacity was observed as the charge / discharge cycle was repeated, to 0.153 Ah (full charge capacity at the 87th charge / discharge cycle), 0.150 Ah (average full charge capacity in section 2), 0.148 Ah (full charge capacity at the 107th charge / discharge cycle), 0.146 Ah (average full charge capacity in section 3), 0.145 Ah (full charge capacity at the 127th charge / discharge cycle), and 0.144 Ah (average full charge capacity in section 4).

[0119] It can be seen that the full charge capacity of the battery according to Example 1 is greater than the full charge capacity of the battery according to Comparative Example 1 based on the same charge / discharge cycle and the same cycle period.

[0120] In addition, considering that the average full charge capacity during a charge / discharge cycle (during a specific period) in a specific cycle section is greater than the average full charge capacity of the battery according to Comparative Example 1, the capacity recovery effect of the capacity recovery process is not temporary but continues for a long period of time, which can be confirmed from the graph in Figure 3. Therefore, it is also possible to provide the effect of slowing down the deterioration rate of the battery by the amount of capacity recovery.

[0121] 4 is a flow chart illustrating a battery capacity recovery method according to a second embodiment of the present invention, which may be performed by the battery capacity recovery device 100 shown in FIG.

[0122] Referring to FIG. 4, in step S400, the control unit 120 determines the electrical state of the battery.

[0123] In step S410, the control unit 120 determines whether to perform a capacity recovery process on the battery according to the electrical state of the battery. If the value of step S410 is "yes", the process proceeds to step S420. If the value of step S410 is "no", the method of Fig. 4 ends. Different from the method of Fig. 2, the capacity recovery process according to the method of Fig. 4 includes a first capacity recovery routine and a second capacity recovery routine.

[0124] Specifically, the control unit 120 may determine whether the electrical condition of the battery satisfies all the conditions of a predetermined set of conditions, and if so, may decide to perform a capacity recovery process on the battery.

[0125] The set of conditions used in step S410 includes at least one condition selected from the following list of conditions: <Condition list> (i) The cumulative discharge capacity since the completion of the previous capacity recovery process is equal to or greater than the reference capacity. (ii) The decrease in full charge capacity from the time of the completion of the previous capacity recovery process is equal to or greater than a critical capacity (e.g., 1% of the design capacity). (iii) The battery is at rest (unloaded).

[0126] In step S420, the control unit 120 performs a first capacity recovery routine. The first capacity recovery routine may be a process of discharging the battery until the SOC of the battery drops to a reference SOC. The control unit 120 may transmit a discharge command to a discharge device to discharge the battery at a reference constant current having a predetermined current rate (e.g., 2.0 C). The inverter 30 provided in the electric vehicle 1 may be used as the discharge device.

[0127] During the execution of step S420, the control unit 120 may periodically or non-periodically monitor the SOC of the battery to determine whether the first capacity recovery routine is completed. In the battery capacity recovery method according to the second embodiment, the reference SOC may be determined in advance. For example, the reference SOC may be a fixed value within a range of 0% to 20%.

[0128] In step S430, the control unit 120 performs a second capacity recovery routine. The second capacity recovery routine may be a process of resting the battery for a reference time or more from the completion of the first capacity recovery routine. The control unit 120 may control a relay provided in the battery pack to an off state or transmit a drive stop command to the discharge device so that the battery is maintained in an unloaded state.

[0129] In the battery capacity recovery method according to the second embodiment, the reference time may be predetermined. For example, the reference time may be a fixed value of 10 hours or more.

[0130] Fig. 5 is a flow chart showing a battery capacity recovery method according to a third embodiment of the present invention. The method of Fig. 5 can be performed by the battery capacity recovery device 100 shown in Fig. 1. In describing the method of Fig. 5, it should be made clear in advance that a description of contents common to the method of Fig. 4 may be omitted.

[0131] Referring to FIG. 5, in step S500, the control unit 120 determines the electrical state of the battery.

[0132] In step S510, the control unit 120 determines whether to perform a capacity recovery process on the battery according to the electrical state of the battery. If the value of step S510 is "yes", the process proceeds to step S515. If the value of step S510 is "no", the method of Fig. 5 ends. Similar to the capacity recovery process according to the method of Fig. 4, the capacity recovery process according to the method of Fig. 5 includes a first capacity recovery routine and a second capacity recovery routine.

[0133] In step S515, the control unit 120 determines at least one of a reference constant current, a reference SOC, and a reference time associated with the capacity recovery process. That is, in contrast to step S420 of the method according to Fig. 4, at least one of the reference constant current, the reference SOC, and the reference time may be a variable control parameter adaptively changed by the control unit 120 according to the electric state of the battery, etc. When only one or two of the control parameters of the reference constant current, the reference SOC, and the reference time are determined in step S515, the remaining control parameters may be set to predetermined values.

[0134] At least one of the first relationship data, the second relationship data, and the third relationship data may be stored in the recording unit 130. Each of the first relationship data, the second relationship data, and the third relationship data may be recorded in the recording unit 130 in the form of a lookup table or a multi-order function.

[0135] The first relationship data is used to determine the reference constant current, and may define a predetermined positive correspondence relationship between the full charge capacity and the reference constant current. According to the first relationship data, the reference constant current decreases as the full charge capacity decreases. The control unit may input the current full charge capacity of the battery as an index into the first relationship data, thereby determining the reference constant current as an operating condition of the first capacity recovery routine to be executed soon.

[0136] The second relationship data is used to determine the reference SOC, and may define a predetermined positive relationship between the full charge capacity and the reference SOC. According to the second relationship data, the reference SOC decreases as the full charge capacity decreases. The control unit may input the current full charge capacity of the battery as an index into the second relationship data, thereby determining the reference SOC as a termination condition for the first capacity recovery routine to be executed soon.

[0137] The third relationship data is used to determine the reference time, and may define a predetermined negative correspondence relationship between the full charge capacity and the reference time. According to the third relationship data, the reference time increases as the full charge capacity decreases. The control unit may input the current full charge capacity of the battery as an index into the third relationship data, thereby determining the reference time as a minimum duration of the second capacity recovery routine to be executed soon.

[0138] In step S520, the control unit 120 performs a first capacity recovery routine. The first capacity recovery routine may be a process of discharging the battery at the reference constant current determined in step S515 until the SOC of the battery drops to the reference SOC determined in step S515.

[0139] In step S530, the control unit 120 performs a second capacity recovery routine, which may be a process of resting the battery for a reference time period determined in step S515 or longer from the completion of the first capacity recovery routine.

[0140] Fig. 6 is a flow chart showing a battery capacity recovery method according to a fourth embodiment of the present invention. The method of Fig. 6 can be performed by the battery capacity recovery device 100 shown in Fig. 1. In describing the method of Fig. 6, it should be made clear in advance that a description of contents common to the method of Fig. 4 or Fig. 5 may be omitted.

[0141] Referring to FIG. 6, in step S600, the control unit 120 determines the electrical state of the battery.

[0142] In step S610, the control unit 120 determines whether to perform a capacity recovery process on the battery according to the electrical state of the battery. If the value of step S610 is "yes", the process proceeds to step S620. If the value of step S610 is "no", the method of Fig. 6 ends. Unlike the capacity recovery process according to the methods of Fig. 2 and Fig. 5, the capacity recovery process according to the method of Fig. 6 further includes a calibration charging routine following the second capacity recovery routine.

[0143] In step S620, the control unit 120 performs a first capacity recovery routine, which may be a process of discharging the battery at a reference constant current until the SOC of the battery drops to a reference SOC.

[0144] In step S630, the control unit 120 performs a second capacity recovery routine, which may be a process of resting the battery for a reference time or more from the completion of the first capacity recovery routine.

[0145] In step S640, the control unit 120 performs a calibration charging routine. The calibration charging routine may be started on the condition that the rest time of the battery due to the second capacity recovery routine is equal to or greater than a reference time. The calibration charging routine may be a process of charging the battery until the SOC of the battery reaches a verification SOC. The verification SOC is greater than the reference SOC and may be predetermined within a range of, for example, 80% to 100%.

[0146] In step S650, the control unit 120 determines a recovery capacity by the capacity recovery process based on the integrated amount of charging current and the amount of SOC change (e.g., the difference between the verification SOC and the reference SOC) during the execution period of the calibration charging routine. Specifically, the control unit 120 may determine a current full charge capacity equal to a value obtained by dividing the integrated amount of charging current by the amount of SOC change, and then determine a recovery capacity equal to a value obtained by subtracting the full charge capacity at the start of the method of FIG. 6 from the current full charge capacity.

[0147] In step S660, the control unit 120 calibrates any one of the reference constant current, the reference SOC, and the reference time based on the recovery capacity.

[0148] The recording unit 130 may store at least one of the first calibration data, the second calibration data, and the third calibration data. Each of the first calibration data, the second calibration data, and the third calibration data may be recorded in the recording unit 130 in the form of a look-up table or a multi-order function.

[0149] The first calibration data is used to calibrate the reference constant current, and may define a predetermined positive correspondence between the recovery capacity and a calibration amount for the reference constant current. Therefore, the reference constant current is calibrated to be larger as the recovery capacity is larger.

[0150] The second calibration data is used to calibrate the reference SOC, and may define a predetermined positive correspondence between the recovery capacity and a calibration amount for the reference SOC, so that the reference SOC is calibrated to be larger as the recovery capacity is larger.

[0151] The third calibration data is used to calibrate the reference time, and may define a predetermined negative correspondence between the recovery capacity and the calibration amount for the reference time. Therefore, the larger the recovery capacity, the shorter the reference time is calibrated.

[0152] Any one of the reference constant current, the reference SOC, and the reference time calibrated in step S660 is used when the capacity recovery process is subsequently re-executed.

[0153] FIG. 7 is a diagram showing an example of the appearance of an electric vehicle according to an embodiment of the present invention, and FIG. 8 is a diagram showing a schematic configuration of the electric vehicle shown in FIG.

[0154] 7 and 8, an electric vehicle 1 includes a vehicle controller 2, a battery pack 10, a relay 20, an inverter 30, and an electric motor 40. Charging and discharging terminals P+, P- of the battery pack 10 may be electrically coupled to a charger 3 via a charging cable or the like. The charger 3 may be included in the electric vehicle 1 or may be provided in a charging station.

[0155] The vehicle controller 2 (e.g., an electronic control unit (ECU)) is configured to transmit a key-on signal to the battery management system 50 in response to an engine start button (not shown) provided on the electric vehicle 1 being switched to an on (ON) position by a user. The vehicle controller 2 is configured to transmit a key-off signal to the battery management system 50 in response to an engine start button being switched to an off (OFF) position by a user. The charger 3 communicates with the vehicle controller 2 and can supply constant current or constant voltage charging power through the charging and discharging terminals P+, P- of the battery pack 10.

[0156] The battery pack 10 includes a battery B and a battery management system 50.

[0157] The type of battery B is not particularly limited as long as it includes an electrochemical element that can be repeatedly charged and discharged, such as a lithium ion cell, etc. Battery B is a target for the capacity recovery process according to the embodiment described above with reference to Figs.

[0158] The relay 20 is electrically connected in series to the battery B through a power path connecting the battery B and the inverter 30. FIG. 8 illustrates an example in which the relay 20 is connected between the positive terminal of the battery B and the charge / discharge terminal P+. The relay 20 is controlled to be turned on and off in response to a switching signal from the battery management system 50. The relay 20 may be a mechanical contactor that is turned on and off by the magnetic force of a coil, or a semiconductor switch such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). While the relay 20 is turned off or the inverter 30 and the charger 3 are stopped, the battery B is maintained in a resting state.

[0159] An inverter 30 is provided to convert direct current from battery B to alternating current in response to commands from the battery management system 50 or vehicle controller 2 .

[0160] The electric motor 40 is driven by AC power from the inverter 30. As the electric motor 40, for example, a three-phase AC motor 40 may be used.

[0161] The battery management system 50 includes a sensing unit 110, a control unit 120, and a recording unit 130. The battery management system 50 may further include a communication circuit 150. The battery management system 50 may be used as the battery capacity recovery device 100 shown in FIG.

[0162] The sensing unit 110 may include a voltage detection unit 111 and a current detection unit 113 .

[0163] The voltage detection unit 111 is connected to the positive and negative terminals of battery B and is configured to detect the terminal voltage, which is the voltage applied across both ends of battery B, and output a voltage signal SV indicating the detected terminal voltage to the control unit 120.

[0164] The current detection unit 113 is connected in series to the battery B through a current path between the battery B and the inverter 30. The current detection unit 113 is configured to detect a charge / discharge current, which is a current flowing through the battery B, and output a current signal SI indicating the detected charge / discharge current to the control unit 120. The current detection unit 113 may be implemented using one or a combination of two or more of known current detection elements, such as a shunt resistor, a Hall effect element, etc.

[0165] The communication circuit 150 is configured to support wired or wireless communication between the control unit 120 and the vehicle controller 2. The wired communication may be, for example, a controller area network (CAN) communication, and the wireless communication may be, for example, ZigBee (registered trademark) or Bluetooth (registered trademark) communication. Of course, the type of communication protocol is not particularly limited as long as it supports wired or wireless communication between the control unit 120 and the vehicle controller 2. The communication circuit 150 may include an output device (for example, a display, a speaker) that provides information received from the control unit 120 and / or the vehicle controller 2 in a form that can be recognized by a user.

[0166] The control unit 120 is operably coupled to the relay 20, the voltage detection unit 111, the current detection unit 113, and the communication circuit 150. The two components being operably coupled means that the two components are directly or indirectly connected to each other so as to be able to transmit and receive signals in one or both directions.

[0167] The control unit 120 may collect a voltage signal SV from the voltage detection unit 111 and a current signal SI from the current detection unit 113. The control unit 120 may convert and record each analog signal collected from the sensing unit 110 into a digital value using an analog-to-digital converter (ADC) provided inside.

[0168] The control unit 120 is also referred to as a "control circuit" or a "battery controller" and may be embodied in hardware using at least one of ASICs (application specific integrated circuits), DSPs (digital signal processors), DSPDs (digital signal processing devices), PLDs (programmable logic devices), FPGAs (field programmable gate arrays), microprocessors, and other electrical units for performing functions.

[0169] The recording unit 130 may include at least one of the following recording media: a flash memory, a hard disk, a solid state disk (SSD), a solid disk drive (SDD), a multimedia micro card, a random access memory (RAM), a static RAM (SRAM), a read only memory (ROM), an electrically erasable programmable ROM (EEPROM), and a programmable ROM (PROM). The recording unit 130 may record data and programs required for the arithmetic operation by the control unit 120. The recording unit 130 may record data indicating the result of the arithmetic operation by the control unit 120. In FIG. 8, the recording unit 130 is physically independent from the control unit 120, but may be incorporated within the control unit 120.

[0170] The control unit 120 may turn on the relay 20 in response to a key-on signal. The control unit 120 may turn off the relay 20 in response to a key-off signal. The key-off signal indicates a switch from the cycle mode to the pause mode. Alternatively, the on / off control of the relay 20 may be handled by the vehicle controller 2 instead of the control unit 120.

[0171] The above-described embodiments of the present invention may be embodied not only by an apparatus and a method, but also through 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 implementation would be easily embodied by a person skilled in the art from the description of the above-described embodiments.

[0172] As described above, the present invention has been described using limited embodiments and drawings. However, 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 belongs within the technical spirit of the present invention and the equivalent scope of the claims.

[0173] Furthermore, the present invention described above is susceptible to various substitutions, modifications and alterations by those having ordinary knowledge in the technical field to which the present invention pertains, within the scope not departing from the technical spirit of the present invention, and is not limited to the above-described embodiments and the accompanying drawings, but may be configured by selectively combining all or part of each embodiment for various modifications.

Claims

1. a sensing unit configured to measure a voltage and a current of the battery; a control unit configured to determine an electrical state of the battery based on time series data of the voltage and current of the battery, The control unit is Determine whether to execute a capacity recovery process including a first capacity recovery routine and a second capacity recovery routine according to an electrical state of the battery; configured to sequentially execute the first capacity recovery routine and the second capacity recovery routine when it is determined to execute the capacity recovery process; The first capacity recovery routine is a process of discharging the battery until the SOC of the battery decreases to a reference SOC, The second capacity recovery routine is a process of restoring the battery for a reference time or more from a point in time when the first capacity recovery routine is completed.

2. 2. The battery capacity recovery device according to claim 1, wherein at least one of the reference SOC and the reference time is predetermined.

3. The reference SOC is equal to or greater than 0% and less than 20%, The battery capacity recovery device according to claim 2 , wherein the reference time is 10 hours or more.

4. The control unit is 2. The battery capacity recovery device according to claim 1, configured to determine at least one of a reference constant current, the reference SOC, and the reference time associated with the first capacity recovery routine based on a full charge capacity of the battery.

5. The control unit is 5. The battery capacity recovery device according to claim 4, wherein the reference constant current is determined from first relationship data in which a predetermined positive correspondence relationship between the full charge capacity and the reference constant current is defined.

6. The control unit is 5. The battery capacity recovery device according to claim 4, further comprising: second relationship data that defines a predetermined positive correspondence relationship between the full charge capacity and the reference SOC, and determines the reference SOC from second relationship data that defines a predetermined positive correspondence relationship between the full charge capacity and the reference SOC.

7. The control unit is 5. The battery capacity recovery device according to claim 4, further comprising: a third relationship data in which a predetermined negative correspondence relationship between the full charge capacity and the reference time is defined, and the reference time is determined from the third relationship data.

8. The control unit is 2. The battery capacity recovery device according to claim 1, configured to execute the capacity recovery process under the conditions that an increase in the cumulative discharge capacity of the battery since the completion of the previous capacity recovery process is equal to or greater than a reference capacity and that the battery is in a resting state.

9. The control unit is The battery capacity recovery device according to claim 8 , configured to determine the reference capacity based on a full charge capacity of the battery.

10. The control unit is 2. The battery capacity recovery device according to claim 1, configured to execute the capacity recovery process under the conditions that a decrease in the full charge capacity of the battery since the completion of the previous capacity recovery process is equal to or greater than a critical capacity and that the battery is in a resting state.

11. The battery comprises:

10. The battery capacity recovery device of claim 1, comprising lithium metal as an anode active material and sulfur as a cathode active material.

12. A battery pack comprising the battery capacity recovery device according to any one of claims 1 to 11.

13. 13. An electric vehicle comprising the battery pack of claim 12.

14. determining an electrical state of the battery based on time series data of the voltage and current of the battery; determining whether to execute a capacity recovery process including a first capacity recovery routine and a second capacity recovery routine according to an electrical state of the battery; performing the first capacity recovery routine when it is determined that the capacity recovery process should be performed; and performing the second capacity restoration routine in response to completion of the first capacity restoration routine; The first capacity recovery routine is a process of discharging the battery until the SOC of the battery decreases to a reference SOC, The second capacity recovery routine is a step of restoring the battery for a reference time or more from a point in time when the first capacity recovery routine is completed.

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