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 recovering at least a part of a reduced capacity of a rechargeable battery.

[0002] This application claims priority based on 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, and all the contents disclosed in the specifications and drawings of the applications are incorporated herein.

Background Art

[0003] In recent years, as the demand for portable electronic products such as notebook computers, video cameras, mobile phones, etc. has rapidly grown, and the development of electric vehicles, energy storage batteries, robots, artificial satellites, etc. has become full-fledged, research on high-performance rechargeable batteries that can be repeatedly charged and discharged has been actively conducted.

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

[0005] Among various forms of rechargeable batteries, lithium-sulfur batteries have attracted attention in recent years. A lithium-sulfur battery includes a sulfur-based substance having an S-S bond (sulfur-sulfur bond) as a positive electrode active material and lithium metal as a negative electrode active material. Sulfur, which is the main material of the positive electrode active material, has the advantages of being abundant in resources worldwide, non-toxic, and having a low weight per atom.

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

[0007] Generally, rechargeable batteries, including lithium-sulfur batteries, gradually degrade with repeated charging and discharging cycles. Specifically, the battery's full charge capacity (FCC) gradually decreases with each charge-discharge cycle. In other words, the amount of energy available when a degraded battery is fully charged (i.e., the dischargeable capacity) is relatively less than the amount of energy available when a new battery is fully charged.

[0008] Such a decrease in discharge capacity reduces the operating time and driving range of loads such as electronic devices or electric vehicles. Therefore, there is a need to develop technologies that can restore the reduced discharge capacity of degraded batteries. [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The present invention was devised to solve the above-mentioned 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 decreased due to degradation, 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 be more clearly evident from the embodiments of the present invention. Furthermore, the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims. [Means for solving the problem]

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

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

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

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

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

[0018] The control unit may be configured to execute the capacity recovery process on the condition that the 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 dormant state.

[0019] The control unit may be configured to determine the reference capacity based on the fully charged capacity of the battery.

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

[0021] The battery may contain lithium metal as the negative electrode active material and sulfur as the positive electrode active 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] According to another aspect of the present invention, a battery control method includes: 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; when it is determined to execute the capacity recovery process, performing the first capacity recovery routine; and performing the second capacity recovery routine in response to completion of the first capacity recovery routine. The first capacity recovery routine is a process of discharging the battery until the state of charge (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 time of the first capacity recovery routine.

Advantages of the Invention

[0025] According to one aspect of the present invention, by executing a capacity recovery process for a battery, at least a part of the fully charged capacity of the battery that has decreased due to various causes such as repeated charging and discharging from a new state can be recovered. In particular, the capacity recovery process can be effectively applied to lithium-sulfur batteries.

[0026] Also, according to one aspect of the present invention, by preemptively executing a capacity recovery process before the service life of the battery ends, the service life of the battery can be extended.

[0027] Also, according to one aspect of the present invention, after determining whether it is necessary to execute a capacity recovery process according to the electrical state of the battery, and executing the capacity recovery process only when necessary, it is possible to eliminate the side effect that the battery deteriorates faster due to excessive execution of the capacity recovery process.

[0028] Also, according to one aspect of the present invention, by adjusting at least one control parameter (such as a reference constant current described later) related to the capacity recovery process according to the electrical state of the battery, it is possible to minimize the acceleration of deterioration caused by the discharge process of the capacity recovery process, and as a result, slow down the deterioration rate 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 serve to further understand the technical idea of the present invention together with the detailed description of the invention described later, and the present invention should not be construed as being limited only to the matters described in the drawings.

Brief Explanation of Drawings

[0031] [Figure 1] It is a diagram schematically showing the configuration of a battery capacity recovery device according to an embodiment of the present invention. [Figure 2] It is a flowchart schematically showing a battery capacity recovery method according to the first embodiment of the present invention. [Figure 3] It is a graph referred to for explaining the difference in the life characteristics of a battery according to the application of a capacity recovery process according to an embodiment of the present invention. [Figure 4] It is a flowchart schematically showing a battery capacity recovery method according to the second embodiment of the present invention. [Figure 5] It is a flowchart schematically showing a battery capacity recovery method according to the third embodiment of the present invention. [Figure 6] It is a flowchart schematically showing a battery capacity recovery method according to the fourth embodiment of the present invention. [Figure 7] It is a diagram exemplarily showing the appearance of an electric vehicle according to an embodiment of the present invention. [Figure 8] It is a diagram schematically showing the configuration of the electric vehicle shown in FIG. 7.

Modes for Carrying Out the Invention

[0032] Preferred embodiments of the present invention will now be described in detail with reference to the attached drawings. Prior to this, terms and words used in this specification and in the claims should not be interpreted in a manner limited to their ordinary and dictionary meanings, but rather in a manner corresponding to the technical idea 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, the embodiments described herein and the configurations shown in the drawings represent only one of the most preferred embodiments of the present invention and do not represent the entire technical concept of the present invention. It should be understood that there are various equivalents and modifications that can be substituted for these at the time of this application.

[0034] Terms that include ordinal numbers, such as "1st," "2nd," etc., are used to distinguish one of several components from others, and these terms do not limit the components themselves.

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

[0036] Furthermore, when a part of the specification is described as being "connected" to another part, this includes not only "direct connections" but also "indirect connections" mediated by other elements.

[0037] Figure 1 is a schematic diagram showing the configuration of a battery capacity recovery device according to one embodiment of the present invention.

[0038] Referring to Figure 1, the battery capacity recovery device 100 includes a sensing unit 110, a control unit 120, and a recording unit 130.

[0039] In Figure 1, the sensing unit 110 and the control unit 120 are shown as distinct components, but this is merely illustrative, and in various embodiments, two or more components may be integrated and operate as one. Furthermore, 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, a battery refers to a single, independent cell that has a negative terminal and a positive terminal and is physically separable.

[0041] As an example, a lithium-ion battery or a lithium polymer battery may be used as the battery. Here, the battery can have a variety of structures depending on the type of positive electrode active material. For example, the battery may be formed with at least one of the following structures: 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 an olivine-based positive electrode active material 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 contain lithium metal as the negative electrode active material and sulfur as the positive electrode active material.

[0043] Here, "battery" can sometimes refer to a battery module in which multiple cells are connected in series and / or parallel. For the sake of explanation, in the following, "battery" will be used to refer to a single, independent cell.

[0044] The sensing unit 110 may be configured to detect at least one battery parameter (e.g., voltage, current) that indicates the electrical state of the battery. The electrical state of the battery may include a variety of characteristics that indicate, for example, the battery's usage state, physical state, chemical state, etc.

[0045] The control unit 120 is operably coupled with other components of the battery capacity recovery device 100, such as the sensing unit 110 and the recording unit 130, and can control various operations of the battery capacity recovery device 100.

[0046] The control unit 120 can perform various operations of the battery capacity recovery device 100 by executing one or more instructions. To execute the various control logics performed in this invention, the control unit 120 may selectively include a processor, ASIC (Application-Specific Integrated Circuit), other chipsets, logic circuits, registers, communication modems, data processing devices, etc., as known in the industry. Furthermore, when the control logic is implemented as software, the control unit 120 may be implemented as a collection of program modules. In this case, the program modules are stored in the recording unit 130 and can be executed by the control unit 120.

[0047] The control unit 120 may perform a capacity recovery process for the battery depending on the battery's electrical state. The control unit 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 battery's electrical state.

[0048] As an example of a capacity recovery process that can be executed by the control unit 120, the following can be performed sequentially: a first charging operation to charge the battery to a first reference SOC; a discharge operation to discharge the battery to below the reference SOC after the first charging operation; a rest operation to maintain the battery in a rest state for a rest period of a reference time or longer after the discharge operation; and a second charging operation to recharge the battery to a third reference SOC after the rest operation.

[0049] The recording unit 130 may store data or programs necessary for each component of the battery capacity recovery device 100 to operate and function, or data generated during the process of operation and functioning. The recording unit 130 may be located inside or outside the control unit 120 and may be connected to the control unit 120 by a variety of known means. The recording unit 130 may store at least one program, application, data, or instruction executed by the control unit 120. The recording unit 130 is not particularly limited in type, 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 can be implemented in at least one form from among flash® memory, hard disk, SSD (Solid State Disk), SDD (Solid Disk Drive), multimedia microcard, RAM (Random Access Memory), SRAM (Static RAM), ROM (Read Only Memory), EEPROM (Electrically Erasable Programmable ROM), and PROM (Programmable ROM), but the present invention is not limited to such specific forms of the recording unit 130. Furthermore, the recording unit 130 can store program code in which the process executable by the control unit 120 is defined.

[0050] Furthermore, the recording unit 130 can store information regarding a preset reference capacity and / or a preset reference number of cycles in order to determine whether or not to execute the capacity recovery process. Further details will be explained through the embodiments described later.

[0051] Figure 2 is a schematic flowchart illustrating a battery capacity recovery method according to a first embodiment of the present invention. The method in Figure 2 can be performed by the battery capacity recovery device 100 shown in Figure 1.

[0052] Referring to Figure 2, the battery capacity recovery process may include a first charge operation (S210), a discharge operation (S220), a pause operation (S230), and a second charge operation (S240). The discharge operation (S220) and the pause operation (S230) are essential routines of the capacity recovery process, while the first charge operation (S210) and the second charge operation (S240) may be optional routines that can be omitted from the capacity recovery process. The discharge operation (S220) and the pause operation (S230) may be referred to as the first capacity recovery routine and the second capacity recovery routine, respectively.

[0053] In step S210, the control unit 120 may drive the charger (see Figure 8) to charge the battery until the battery's State of Charge (SOC) rises to a first reference SOC. Here, the first reference SOC may be a predetermined value stored in the recording unit 130 or the like. If the battery's SOC is already equal to or greater than the first reference SOC, step S210 does not need to be performed.

[0054] Specifically, the control unit 120 may be operably coupled to a charger and discharge device located outside the battery capacity recovery device 100. Alternatively, the control unit 120 may be configured to open and close the charging switch of the battery pack. The control unit 120 can 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 at all times during operation or when requested by the control unit 120.

[0055] In step S220, the control unit 120 may drive the discharge device to discharge the battery until the battery's State of Charge (SOC) drops to a second reference SOC. Here, the second reference SOC may be a predetermined value 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 smaller than the first reference SOC.

[0056] The control unit 120 can discharge the battery by controlling the discharge switch of the discharge device and / or battery pack. The discharge device may be configured to receive discharge power from the battery at all times during operation or when requested by the control unit 120.

[0057] The control unit 120 can determine the full charge capacity of the battery based on the change in the battery's state of charge (SOC) and discharge capacity in step S220.

[0058] In step S230, the control unit 120 can stop both the charger and the discharge device (for example, the inverter 30 in Figure 8) to allow the battery to remain dormant for a period longer than the reference time.

[0059] Specifically, the control unit 120 can maintain the battery in a dormant state by shutting off both charging and discharging of the battery for a reference time or longer from the completion of step S220. To this end, the control unit 120 can control the charger or the charging or discharging switch of the battery pack.

[0060] In step S240, the control unit 120 may drive the charger to recharge the battery so that the battery's State of Charge (SOC) rises to a third reference SOC. Here, the third reference SOC may be a predetermined value stored in the recording unit 130 or the like. For example, the third reference SOC may be set to 90%.

[0061] The battery capacity recovery method shown in Figure 2 has the technical effect of reducing the rate of battery degradation. In particular, batteries gradually degrade with repeated charging and discharging, and battery degradation means a decrease in the 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 rate of degradation due to battery use can be effectively reduced. This has the effect of extending the lifespan of the battery and the device in which it is installed, such as electric vehicles and energy storage systems (ESS).

[0062] If the battery is a lithium-sulfur battery, the capacity recovery effect by applying the method shown in Figure 2 is even better. In the case of a lithium-sulfur battery, after the battery is charged to the first reference SOC, it is discharged to below the second reference SOC as described above, and then undergoes a rest period of a reference time or longer, at which point the ratio of sulfur-containing chemical species (e.g., Li2S, S, polysulfide, etc.) is naturally and appropriately redistributed inside and on the surface of the positive and negative electrodes.

[0063] Specifically, when the above-described capacity recovery process is performed on a battery, the ratio of sulfur-containing chemical species such as sulfur (S), polysulfides, and lithium sulfide (Li2S) contained in the electrodes and electrolyte of a degraded battery can be redistributed through spontaneous chemical reactions. In the process of redistributing the ratio of sulfur-containing chemical species, sulfur-containing chemical species that were irreversibly rendered unexpressed due to battery degradation can be transformed back into a reversible state. These sulfur-containing chemical species, once transformed back into a reversible state, can provide usable energy in subsequent charge-discharge cycles. The battery capacity recovery device 100 can acquire additional dischargeable capacity that was previously unavailable from a degraded battery.

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

[0065] In particular, when a battery is recharged to a state of charge (SOC) of 100% after a rest period longer than the standard time, not only is capacity recovered due to the rest period, but additional capacity recovery occurs due to the recharging process, and this capacity recovery effect is sustainable even in charge-discharge cycles after the method shown in Figure 2 is completed. In other words, the full charge capacity recovered by the capacity recovery process is not recovered only once during the relevant charge or discharge stage, but is sustained even in charge-discharge cycles after the capacity recovery process has been performed. Therefore, a battery to which the capacity recovery process has been applied can store a relatively larger amount of available energy than before the capacity recovery process was performed.

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

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

[0068] As another example, the second reference SOC for the discharge operation (S220) may be set to 0%. In this case, the control unit 120 may terminate the discharge operation and perform a pause operation (S230) once the battery reaches a full discharge state where the SOC is 0%.

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

[0070] Referring to the drawings, the operation of the control unit 120 in which it performs a capacity recovery process according to the electrical state of the battery will be explained in more detail.

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

[0072] On the other hand, battery degradation is usually caused by an increase in at least one of the number of charge-discharge cycles and the cumulative discharge capacity. Therefore, the number of charge-discharge cycles or the cumulative discharge capacity can be used as indicators of the battery's degradation state. Thus, the control unit 120 can monitor the battery's electrical state in real time based on the time series of at least one type of battery parameter collected from the sensing unit 110, and execute a capacity recovery process according to the monitored electrical state. The following describes in detail how the control unit 120 executes the above-described capacity recovery process based on the battery's usage history.

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

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

[0075] In the BOL (Beginning of Life) state, which can be considered equivalent to a new battery, the degree of battery degradation is minimal, so the control unit 120 does not need to perform a capacity recovery process on the battery. Furthermore, frequent application of the capacity recovery process is undesirable because it may degrade the battery. Therefore, the control unit 120 can determine in advance whether or not to apply the capacity recovery process to the battery based on the cumulative discharge capacity from a specific point in the past, thereby enabling the application of the capacity recovery process at the optimal time and improving the capacity recovery effect of the capacity recovery process. For example, the control unit 120 can determine the cumulative discharge capacity of the battery from the completion of the last capacity recovery process to the present time, and estimate the degree of battery degradation during that period based on the cumulative discharge capacity.

[0076] Specifically, the control unit 120 can compare the total number of charge-discharge cycles of the battery with multiple cycle intervals to determine which of the multiple cycle intervals 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 cumulative discharge capacity from the time the battery was shipped increases by the battery's design capacity. The control unit 120 can calculate the cumulative discharge capacity of the battery in each cycle interval.

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

[0078] The electrical state of the battery at a specific point in time may include the total cumulative discharge capacity from the time the battery was taken out of storage until that specific point in time. The control unit 120 may be configured to execute a capacity recovery process whenever the electrical state of the battery satisfies a predetermined set of conditions.

[0079] Even after a capacity recovery process has been performed on the battery once, the battery's capacity may degrade again with continued use. Therefore, the control unit 120 may conditionally execute a capacity recovery process based on a set of conditions including at least one of the following: (i) the increase in total cumulative discharge capacity is equal to or greater than a reference capacity, and (ii) the increase in cumulative discharge capacity since the completion of the previous capacity recovery process is equal to or greater than a reference capacity. Through repeatedly executed capacity recovery processes, the control unit 120 can recover the battery's available energy.

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

[0081] Alternatively, the control unit 120 may set a reference capacity to compare with the cumulative discharge capacity from the time of completion of the previous completed capacity recovery process to the present time, in order to re-execute 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 serves as the basis for determining whether to execute a capacity recovery process, to a relatively larger value as the battery's electrical state approaches the BOL (Battery Overload) state, and set the reference capacity related to subsequent capacity recovery processes to a relatively smaller value. For example, the control unit 120 may be configured to execute 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 to execute the first capacity recovery process and the second reference capacity for determining whether to execute the second capacity recovery process to be different.

[0083] The control unit 120 can set the reference capacity for determining whether to perform the capacity recovery process to at least two different values ​​depending on the number of times the capacity recovery process is performed. For example, the control unit 120 can set the reference capacity for determining whether to perform the first capacity recovery process on a battery after it has been delivered to a value corresponding to 66 times the battery's design capacity. In this case, if the battery's design capacity is 0.22 Ah, the reference capacity is 14.52 Ah, so the control unit 120 can determine that the first capacity recovery process is necessary in response to the total cumulative discharge capacity of the battery since it was delivered 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 can determine that the second capacity recovery process is necessary in response to the cumulative discharge capacity since the completion of the first capacity recovery process being 3.08 Ah or more, which is 14 times the design capacity. If w is a natural number greater than or equal to 2 that indicates the iteration of the capacity recovery process, then the reference capacity associated with the w-th capacity recovery process can be predetermined to be less than or equal to 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) capacity recovery process with a reference capacity associated with the w capacity recovery process. If the cumulative discharge capacity from the completion of the (w-1) capacity recovery process is equal to or greater than the reference capacity associated with the w capacity recovery process, the control unit 120 may determine that the w capacity recovery process needs to be executed. In the state where the w capacity recovery process needs to be executed, the control unit 120 may start the w capacity recovery process in response to the battery's electrical state switching from a charged or discharged state to a dormant state.

[0085] Figure 3 is a graph referenced to illustrate the differences in battery life characteristics depending on the application of the capacity recovery process according to one embodiment of the present invention.

[0086] In the graph in Figure 3, the x-axis represents the number of battery charge-discharge cycles, and the y-axis represents the full charge capacity, with the unit of full charge capacity being Ah (Ampere hour). A charge-discharge cycle includes a charging process in which the battery is charged from 1.8V to 2.5V with a constant current of 0.3C, and a discharging process in which the battery is discharged from 2.5V to 1.8V with a constant current of 2.0C. A predetermined rest period may be provided between the discharge process of a preceding charge-discharge cycle and the charging process of a subsequent charge-discharge cycle. The full charge capacity associated with a particular charge-discharge cycle may be the average of one or both of the charging capacity and the discharging capacity during the charging and discharging processes of that charge-discharge cycle.

[0087] The multiple cycle intervals (intervals 1 to 4) shown exemplarily in Figure 3 each have a predetermined size. Interval 1 is the interval with 87 or fewer charge / discharge cycles, and its size is 87. Interval 2 is the interval with 88 to 107 charge / discharge cycles, and its size is 20. Interval 3 is the interval with 108 to 127 charge / discharge cycles, and its size is 20. Interval 4 is the interval with 128 to 147 charge / discharge cycles, and its size is 20.

[0088] The control unit 120 can calculate the cumulative discharge capacity in each of the multiple cycle intervals and determine whether the cumulative discharge capacity in a particular cycle interval is equal to or greater than the reference capacity associated with that particular cycle interval. Since the control unit 120 calculates the cumulative discharge capacity for each cycle interval, once the capacity recovery process is completed in a particular cycle interval, the control unit 120 can initialize the cumulative discharge capacity in that particular cycle interval to 0 Ah.

[0089] Specifically, the control unit 120 can initialize the cumulative discharge capacity and calculate the cumulative discharge capacity from the initialization point once the capacity recovery process is completed in the preceding cycle interval of two adjacent cycle intervals. 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 of the number of cycles in interval 1 (number of charge-discharge cycles = 87). Subsequently, the control unit 120 can 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 of the number of cycles in interval 2 (number of charge-discharge cycles = 88) reaches the reference capacity of 3.08 Ah. The control unit 120 can execute a second capacity recovery process, provided 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 of the number of cycles in interval 2 (number of charge-discharge cycles = 107). The control unit 120 can 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 of the number of cycles in interval 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, provided 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 reaches the upper limit of the number of cycles in section 3 (number of charge-discharge cycles = 127). Subsequently, 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 of the number of cycles in section 4 (number of charge-discharge cycles = 128) reaches the reference capacity of 3.08 Ah. The control unit 120 may execute a fourth capacity recovery process, provided 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 reaches the upper limit of the 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 each time the capacity recovery process is executed, and accurately recognize when the next capacity recovery process will be executed. The following describes how the control unit 120 executes the above-described capacity recovery process based on the number of charge-discharge cycles of the battery.

[0091] The control unit 120 can recognize the total number of charge-discharge cycles of the battery based on the total cumulative discharge capacity from the time of shipment. For example, the sensing unit 110 can recognize the number of charge-discharge cycles (or charge-discharge cycles) of a battery, where one charge and one discharge constitute one cycle. The control unit 120 can recognize whether the total number of charge-discharge cycles or the increase in the total number of charge-discharge cycles from a specific point in time has reached a predetermined reference number of cycles. In response to the fact that the total number of charge-discharge cycles or the increase in the total number of charge-discharge cycles from a specific point in time is equal to or greater than the predetermined reference number of cycles, the control unit 120 can determine that a capacity recovery process for the battery needs to be applied.

[0092] The control unit 120 may determine that a capacity recovery process is necessary when the total number of charge-discharge cycles of the battery reaches a predetermined reference number of cycles. The control unit 120 may also determine that a capacity recovery process is necessary when the increase in the total number of charge-discharge cycles since the completion of the previous capacity recovery process reaches a predetermined reference number of cycles. In other words, the capacity recovery process may be applied repeatedly with time lags in accordance with the changing electrical state of the battery throughout its entire lifespan.

[0093] The control unit 120 may determine that battery capacity recovery is necessary when 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 can adaptively control the timing of the capacity recovery process depending on the electrical state of the battery. That is, the closer the battery's electrical state is to the BOL state, the less the degradation. The control unit 120 can determine when to re-execute the capacity recovery process depending on the total number of charge-discharge cycles of the battery.

[0095] Specifically, the control unit 120 can 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 the new capacity recovery process) by reducing the reference cycle count used to determine the necessity of executing a capacity recovery process as the battery degrades from the BOL state.

[0096] The control unit 120 can set at least two different reference cycle counts so that it can repeatedly execute the capacity recovery process according to the battery's degradation status. For example, after executing the first capacity recovery process when the total number of charge / discharge cycles of the battery reaches 87 (the upper limit of the number of cycles in section 1), the control unit 120 can 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 degradation rate gradually increases with battery use. For example, the degree of battery degradation for the same number of charge-discharge cycles is greater when the battery is in the MOL (Middle of Life) state than when it is in the BOL (Body of Life) state, and even greater when it is in the EOL (End of Life) state than when it is in the MOL state. Therefore, the control unit 120 may set the execution cycle of the capacity recovery process to gradually become shorter as the battery degrades.

[0098] For example, the control unit 120 may execute the first capacity recovery process when the total number of charge-discharge cycles is equal to 87, and may re-execute the capacity recovery process every time the total number of charge-discharge cycles increases by 20 until the total number of executions of the capacity recovery process reaches a first critical number (e.g., 10). Thereafter, the control unit 120 may re-execute the capacity recovery process every time the total number of charge-discharge cycles increases by 10 until the total number of executions of the capacity recovery process reaches a second critical number (e.g., 30). According to such an embodiment, the capacity recovery effect of the battery can be maximized by shortening the re-execution cycle of the capacity recovery process as the battery degradation accelerates.

[0099] The following describes the effects of battery charge and discharge control according to embodiments of the present invention in more detail, using examples and comparative examples. However, embodiments of the present invention can be modified in various forms, and the scope of the present invention should not be construed as being limited to the embodiments described later. Embodiments of the present invention are provided to those skilled in the art to more fully explain the present invention.

[0100] Referring to Figure 3, you can see a graph showing the relationship between the full charge capacity and the number of charge / discharge cycles of a 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 a battery according to Comparative Example 1.

[0101] [Comparative Example 1] The battery was subjected to repeated charge-discharge cycles in which the following processes were sequentially performed: (1) charging, (2) discharging, and (3) resting.

[0102] 1) Charging process: Charge the battery at a constant current of 0.3C until the battery voltage rises from 1.8V to 2.5V (or from 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 from SOC 100% to 0%). 3) Pause process: Charging and discharging are stopped for 1 minute.

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

[0104] 1) Charging process: Charge the battery at a constant current of 0.3C until the battery voltage rises from 1.8V to 2.5V (or from 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 from SOC 100% to 0%). 3-1) First pause process: Charging and discharging are suspended for 1 minute. 3-2) Second pause process: Charging and discharging are suspended for 20 hours.

[0105] In other words, 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 charge-discharge cycle, which serves as a total of four capacity recovery processes applied to the battery in Example 1, differs from Comparative Example 1 in that it includes 1) a charging process, 2) a discharging process, and 3-2) a second resting process.

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

[0108] On the other hand, the first capacity recovery process corresponding to the lower limit of 88 cycles in section 2 restores the capacity of the battery according to Example 1, resulting in the fully charged capacity of the battery according to Example 1 being far greater than the fully charged capacity of the battery according to Comparative Example 1 across the entire range of section 2.

[0109] Similarly, the second capacity recovery process corresponding to the lower limit of 108 cycles in section 3 partially recovers the battery capacity that decreased in section 2, resulting in the fully charged capacity of the battery according to Example 1 being significantly larger than the fully charged capacity of the battery according to Comparative Example 1 across the entire range of section 3. In both section 3 and section 4, it can be confirmed that the fully charged capacity of the battery according to Example 1 is maintained at a greater level than that of the battery according to Comparative Example 1, as a result of the capacity recovery effect of the third and fourth capacity recovery processes. In other words, the battery capacity recovery device 100 according to the present invention can improve the battery's lifespan characteristics by repeatedly executing the capacity recovery process on the battery at appropriate intervals.

[0110] The capacity recovery effect of the four capacity recovery processes will be explained in detail below with reference to Tables 1 and 2.

[0111] Table 1 shows the percentage increase in full charge capacity before and after applying a total of four capacity recovery processes to the battery according to Example 1. The percentage increase in full charge capacity can also be called the "capacity recovery rate". For example, if the full charge capacity increases from A to B by the capacity recovery process, the recovered capacity is "BA", and the capacity recovery rate is "(BA) / A × 100%".

[0112] [Table 1]

[0113] According to Table 1, the first capacity recovery process performed at 88 charge / discharge cycles resulted in a capacity recovery of approximately 3.76% compared to the full charge capacity at 87 charge / discharge cycles. Furthermore, the full charge capacity immediately after the second capacity recovery process performed at 108 charge / discharge cycles increased by approximately 3.16% compared to the full charge capacity at 107 charge / discharge cycles. Additionally, the full charge capacity immediately after the third capacity recovery process performed at 128 charge / discharge cycles increased by approximately 2.81% compared to the full charge capacity at 127 charge / discharge cycles. Finally, the full charge capacity immediately after the fourth capacity recovery process performed at 148 charge / discharge cycles increased by approximately 1.95% compared to the full charge capacity at 147 charge / discharge cycles. The experimental results of Example 1 confirm that the battery capacity is partially recovered and the dischargeable capacity increases each time a capacity recovery process is performed.

[0114] Furthermore, the increased usable capacity is not only effective for the current charge-discharge cycle, but can be maintained in subsequent charge-discharge cycles. This can be seen from the results of measuring the full charge capacity of the battery in Comparative Example 1 and the battery in Example 1 as the charge-discharge cycle progresses.

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

[0116] [Table 2]

[0117] In Table 2, the values ​​for each cell represent the full charge capacity. Referring to Table 2, according to Example 1, the full charge capacity in the 87th charge / discharge cycle, before the application of the first capacity recovery process, 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, the full charge capacity in the 107th charge / discharge cycle, before the application of the second capacity recovery process, 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. Furthermore, according to Example 1, the full charge capacity in the 127th charge / discharge cycle, before the application of the third capacity recovery process, 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, where the capacity recovery process was never applied, only a sustained decrease in the full charge capacity was observed as the charge-discharge cycles were repeated: 0.153Ah (full charge capacity after 87 charge-discharge cycles), 0.150Ah (average full charge capacity in section 2), 0.148Ah (full charge capacity after 107 charge-discharge cycles), 0.146Ah (average full charge capacity in section 3), 0.145Ah (full charge capacity after 127 charge-discharge cycles), and 0.144Ah (average full charge capacity in section 4).

[0119] Based on the same charge-discharge cycle and the same cycle interval, 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.

[0120] Furthermore, considering that the average full charge capacity during the charge-discharge cycle in a specific cycle section (within a predetermined section) is greater than the average full charge capacity of the battery in Comparative Example 1, the capacity recovery effect of the capacity recovery process is not temporary but lasts for a long period of time, as can be confirmed through the graph in Figure 3. Therefore, it is also possible to provide the effect of reducing the battery degradation rate by the amount of capacity recovery.

[0121] Figure 4 is a schematic flowchart illustrating a battery capacity recovery method according to a second embodiment of the present invention. The method in Figure 4 can be performed by the battery capacity recovery device 100 shown in Figure 1.

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

[0123] In step S410, the control unit 120 decides whether to perform a capacity recovery process on the battery according to the battery's electrical state. If the value in step S410 is "yes", the process proceeds to step S420. If the value in step S410 is "no", the method in Figure 4 terminates. Unlike the method in Figure 2, the capacity recovery process in the method in Figure 4 includes a first capacity recovery routine and a second capacity recovery routine.

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

[0125] The set of conditions used in step S410 includes at least one condition selected from the following list of conditions. <List of conditions> (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 since the completion of the previous capacity recovery process is greater than or equal to the critical capacity (e.g., 1% of the design capacity). (iii) The battery is in a dormant state (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 battery's State of Charge (SOC) drops to a reference SOC. The control unit 120 may transmit a discharge command to the discharge device to discharge the battery with a reference constant current having a predetermined current rate (e.g., 2.0C). The discharge device may be an inverter 30 provided in the electric vehicle 1.

[0127] During the execution of step S420, the control unit 120 can confirm the completion of the first capacity recovery routine by periodically or aperiodically monitoring the battery's SOC. In the battery capacity recovery method according to the second embodiment, the reference SOC can be predetermined. For example, the reference SOC may be a fixed value within the range of 0% or more and less than 20%.

[0128] In step S430, the control unit 120 performs a second capacity recovery routine. The second capacity recovery routine may be a process that puts the battery into a paused state for a reference time or longer from the time the first capacity recovery routine is completed. The control unit 120 may control the relays provided in the battery pack to the 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 can be predetermined. For example, the reference time may be a fixed value of 10 hours or more.

[0130] Figure 5 is a schematic flowchart illustrating a battery capacity recovery method according to a third embodiment of the present invention. The method in Figure 5 can be performed using the battery capacity recovery device 100 shown in Figure 1. It should be noted in advance that explanations of the method in Figure 5 may be omitted if they are common to the method in Figure 4.

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

[0132] In step S510, the control unit 120 decides whether to perform a capacity recovery process on the battery according to the battery's electrical state. If the value in step S510 is "yes", the process proceeds to step S515. If the value in step S510 is "no", the method in Figure 5 terminates. Similar to the capacity recovery process in Figure 4, the capacity recovery process in Figure 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 the reference constant current, reference SOC, and reference time related to the capacity recovery process. That is, in contrast to step S420 of the method shown in Figure 4, at least one of the reference constant current, reference SOC, and reference time may be a variable control parameter that is adaptively changed by the control unit 120 depending on the electrical state of the battery, etc. If only one or two of the control parameters of the reference constant current, reference SOC, and reference time are determined in step S515, the remaining control parameters may be set to predetermined values.

[0134] The recording unit 130 may store at least one of the first relational data, the second relational data, and the third relational data. The first relational data, the second relational data, and the third relational data may each be recorded in the recording unit 130 in the form of a lookup table or a polynomial function.

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

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

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

[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 a reference constant current determined in step S515 until the battery's SOC drops to the reference SOC determined in step S515.

[0139] In step S530, the control unit 120 performs a second capacity recovery routine. The second capacity recovery routine may be a process that puts the battery into a paused state for a period of time longer than the reference time determined in step S515, starting from the completion of the first capacity recovery routine.

[0140] Figure 6 is a schematic flowchart illustrating a battery capacity recovery method according to a fourth embodiment of the present invention. The method in Figure 6 can be performed using the battery capacity recovery device 100 shown in Figure 1. It should be noted in advance that explanations of the method in Figure 6 may be omitted if they are common to the methods in Figure 4 or Figure 5.

[0141] Referring to Figure 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 battery's electrical state. If the value in step S610 is "yes", the process proceeds to step S620. If the value in step S610 is "no", the method in Figure 6 terminates. Unlike the capacity recovery processes in Figures 2 and 5, the capacity recovery process in Figure 6 further includes a calibration charging routine that follows the second capacity recovery routine.

[0143] In step S620, the control unit 120 performs a first capacity recovery routine. The first capacity recovery routine may be a process of discharging the battery with a reference constant current until the battery's state of charge (SOC) drops to a reference SOC.

[0144] In step S630, the control unit 120 performs a second capacity recovery routine. The second capacity recovery routine may be a process that puts the battery into a paused state for a reference time or longer, starting 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 battery rest time due to the second capacity recovery routine is equal to or greater than the reference time. The calibration charging routine may be a process of charging the battery until the battery's SOC reaches the verification SOC. The verification SOC is greater than the reference SOC and can be predetermined, for example, in the range of 80% to 100%.

[0146] In step S650, the control unit 120 determines the recovery capacity by the capacity recovery process based on the cumulative amount of charging current over the execution period of the calibration charging routine and the change in SOC (for example, the difference between the verification SOC and the reference SOC). Specifically, the control unit 120 may first determine the current full charge capacity by dividing the cumulative amount of charging current by the change in SOC, and then determine the recovery capacity by subtracting the full charge capacity at the start of the method in Figure 6 from the current full charge capacity.

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

[0148] The recording unit 130 may store at least one of the first calibration data, the second calibration data, and the third calibration data. The first calibration data, the second calibration data, and the third calibration data may each be recorded in the recording unit 130 in the form of a lookup table or a polynomial 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 the calibration amount relative to the reference constant current. Therefore, the larger the recovery capacity, the larger the reference constant current will be calibrated.

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

[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 relative to the reference time. Therefore, the larger the recovery capacity, the shorter the reference time will be calibrated.

[0152] One of the reference constant current, reference SOC, and reference time calibrated through step S660 will be used if the capacity recovery process is subsequently re-executed.

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

[0154] Referring to Figures 7 and 8, the electric vehicle 1 includes a vehicle controller 2, a battery pack 10, a relay 20, an inverter 30, and an electric motor 40. The charge and discharge terminals P+ and P- of the battery pack 10 can 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 provided at a charging station.

[0155] The vehicle controller 2 (for example, an electronic control unit (ECU)) is configured to transmit a key-on signal to the battery management system 50 in response to the user switching the engine start button (not shown) on the electric vehicle 1 to the ON position. The vehicle controller 2 is also configured to transmit a key-off signal to the battery management system 50 in response to the user switching the engine start button to the OFF position. The charger 3 can communicate with the vehicle controller 2 to supply constant current or constant voltage charging power through the charge / discharge terminals P+ and P- of the battery pack 10.

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

[0157] Battery B is not limited in type, as long as it includes an electrochemical element that can be repeatedly charged and discharged, such as a lithium-ion cell. Battery B is subject to the capacity recovery process according to the embodiments described above, with reference to Figures 1 to 6.

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

[0159] The inverter 30 is provided to convert the DC current from the battery B into AC current in response to a command from the battery management system 50 or the vehicle controller 2.

[0160] The electric motor 40 is driven using AC power from the inverter 30. For example, a three-phase AC motor 40 can be used as the electric motor 40.

[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 can be used as the battery capacity recovery device 100 shown in Figure 1.

[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 to 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 with the battery B through a current path between the battery B and the inverter 30. The current detection unit 113 is configured to detect the charge / discharge current, which is the current flowing through the battery B, and to output a current signal SI indicating the detected charge / discharge current to the control unit 120. The current detection unit 113 can be implemented as one or more combinations of known current detection elements, such as a shunt resistor or a Hall effect element.

[0165] The communication circuit 150 is configured to support wired or wireless communication between the control unit 120 and the vehicle controller 2. Wired communication may be, for example, CAN (controller area network) communication, and wireless communication may be, for example, ZigBee® or Bluetooth® 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 (e.g., a display, a speaker) that provides information received from the control unit 120 and / or the vehicle controller 2 in a form that is recognizable to the 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 operably coupled nature of the two components means that they are directly or indirectly connected in such a way that signals can be transmitted and received in one or both directions.

[0167] The control unit 120 can 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 can convert and record the analog signals collected from the sensing unit 110 into digital values ​​using an internally provided analog-to-digital converter (ADC).

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

[0169] The recording unit 130 may include at least one form of recording medium, such as flash® memory, hard disk, SSD (Solid State Disk), SDD (Solid Disk Drive), multimedia microcard, RAM (Random Access Memory), SRAM (Static RAM), ROM (Read Only Memory), EEPROM (Electrically Erasable Programmable ROM), or PROM (Programmable ROM). The recording unit 130 may record data and programs necessary for calculation operations performed by the control unit 120. The recording unit 130 may also record data indicating the results of calculation operations performed by the control unit 120. In Figure 8, the recording unit 130 is physically independent of the control unit 120, but it may be incorporated into 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 cycle mode to idle mode. Alternatively, the vehicle controller 2 may be responsible for controlling the on / off state of the relay 20 instead of the control unit 120.

[0171] The embodiments of the present invention described above are not limited to apparatus and methods, but can also be embodied through a program that implements the functions corresponding to the configuration of the embodiments of the present invention, or through a recording medium on which such a program is recorded. Such embodiments will be easily realized by those skilled in the art from the description of the embodiments described above.

[0172] As described above, the present invention has been explained with limited embodiments and drawings, but the present invention is not limited thereto, and it goes without saying that various modifications and variations are possible within the equivalent scope of the technical concept and claims of the present invention by persons with ordinary skill in the art to which the present invention pertains.

[0173] Furthermore, the present invention described above can be substituted, modified, and altered in various ways by a person with ordinary skill in the art to which the present invention belongs, without departing from the technical spirit of the invention, and is not limited by the embodiments described above and the accompanying drawings. For diverse modifications, all or part of each embodiment may be selectively combined to form the present invention.

Claims

1. A sensing unit configured to measure the voltage and current of the battery, Includes a control unit configured to determine the electrical state of the battery based on time-series data of the battery's voltage and current, respectively. The control unit, Depending on the electrical state of the battery, it is determined whether to execute a capacity recovery process including a first capacity recovery routine and a second capacity recovery routine. When it is decided to execute the capacity recovery process, the system is configured to execute the first capacity recovery routine and the second capacity recovery routine in sequence. The first capacity recovery routine is a process of discharging the battery using a reference constant current until the battery's SOC drops to a reference SOC. The second capacity recovery routine is a process of putting the battery into a hiatus for a reference time or longer from the time the first capacity recovery routine is completed. The control unit, A battery capacity recovery device that determines the reference constant current from first relational data in which a predetermined positive correspondence relationship between the full charge capacity of the battery and the reference constant current is defined.

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 aforementioned standard SOC is 0% or more 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, The battery capacity recovery device according to claim 1, configured to determine at least one of the reference SOC and the reference time based on the full charge capacity.

5. The control unit, The battery capacity recovery device according to claim 4, configured to determine the reference SOC from second relational data in which a predetermined positive correspondence relationship between the full charge capacity and the reference SOC is defined.

6. The control unit, The battery capacity recovery device according to claim 4, configured to determine the reference time from third relational data in which a predetermined negative correspondence relationship between the full charge capacity and the reference time is defined.

7. The control unit, The battery capacity recovery device according to claim 1, configured to execute the capacity recovery process on the condition that the 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 dormant state.

8. The control unit, The battery capacity recovery device according to claim 7, configured to determine the reference capacity based on the fully charged capacity of the battery.

9. The control unit, The battery capacity recovery device according to claim 1, configured to execute the capacity recovery process on the condition that the decrease in the battery's full charge capacity since the completion of the previous capacity recovery process is greater than or equal to the critical capacity, and that the battery is in a dormant state.

10. The aforementioned battery is The battery capacity recovery device according to claim 1, comprising lithium metal as a negative electrode active material and sulfur as a positive electrode active material.

11. A battery pack comprising a battery capacity recovery device according to any one of claims 1 to 10.

12. An electric vehicle comprising the battery pack described in claim 11.

13. A step of determining the electrical state of the battery based on time-series data of the battery's voltage and current, Depending on the electrical state of the battery, a step is to determine whether to execute a capacity recovery process including a first capacity recovery routine and a second capacity recovery routine, When it is decided to execute the capacity recovery process, the steps include: performing the first capacity recovery routine; The step includes performing the second capacity recovery routine in response to the completion of the first capacity recovery routine, The first capacity recovery routine is a process of discharging the battery using a reference constant current until the battery's SOC drops to a reference SOC. The second capacity recovery routine is a process of putting the battery into a hiatus for a reference time or longer from the time the first capacity recovery routine is completed. A battery capacity recovery method in which the reference constant current is determined from first relational data in which a predetermined positive correspondence relationship is defined between the full charge capacity of the battery and the reference constant current.

14. The battery capacity recovery device according to any one of claims 1 to 10, wherein the control unit sets the execution cycle of the capacity recovery process to be shorter as the battery deteriorates.

Images