Charging method and charging system

Abstract

To enable the precipitation of lithium metal to be accurately suppressed in charging a lithium-ion battery.SOLUTION: A charging method includes: determining a first and a second threshold at which lithium metal precipitates to lithium-ion battery electrodes, with regard to the charge current of the lithium-ion battery (S11); and controlling the charge current of the lithium-ion battery using a difference between the first and the second thresholds and the second threshold (S12-S16). The first threshold indicates a current boundary value at which precipitation of the lithium metal becomes likely to occur when the charge current of the lithium-ion battery exceeds the first threshold. The second threshold represents a smaller value than the first threshold and indicates a current boundary value at which precipitation of the lithium metal becomes likely to occur when the charge current of the lithium-ion battery exceeds continuously the second threshold.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a charging method and a charging system. [Background technology]

[0002] Japanese Patent Laid-Open Publication No. 2012-016263 (Patent Document 1) discloses a technique for setting a Li deposition start voltage (the voltage at which lithium metal deposition starts inside the cell) according to a first charging current or first charging power of the cell, and switching the first charging current or first charging power to a smaller second charging current or second charging power when the terminal voltage of the cell reaches the Li deposition start voltage. The Li deposition start voltage is set lower as the first charging current or first charging power is higher. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-016263 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology described in Patent Document 1 reduces the charging current only after the cell terminal voltage reaches the Li deposition onset voltage, which may not be sufficient to prevent lithium metal deposition. In particular, when the performance of a charger is low, the charger's charge current control response to changes in the target charging current value is likely to be slow. Charging control using such a charger is likely to cause lithium metal deposition due to the delayed reduction in charging current.

[0005] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to make it easier to appropriately suppress the deposition of lithium metal during charging of a lithium-ion battery. [Means for solving the problem]

[0006] A charging method according to one embodiment of the present disclosure includes determining a first threshold and a second threshold for the charging current of the lithium ion battery at which lithium metal deposition occurs on electrodes of the lithium ion battery, and controlling the charging current of the lithium ion battery using the difference between the first and second thresholds and the second threshold. The first threshold indicates a current boundary value at which lithium metal deposition is likely to occur when the charging current of the lithium ion battery exceeds the first threshold. The second threshold is a value smaller than the first threshold and indicates a current boundary value at which lithium metal deposition is likely to occur when the charging current of the lithium ion battery continuously exceeds the second threshold. [Effects of the Invention]

[0007] According to the present disclosure, it becomes easier to appropriately suppress the deposition of lithium metal during charging of a lithium ion battery. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a charging system according to an embodiment of the present disclosure. [Figure 2] 3 is a flowchart illustrating a charging method according to an embodiment of the present disclosure. [Figure 3] 3 is a time chart showing an example of operation according to the charging method shown in FIG. 2. [Figure 4] FIG. 2 is a diagram showing a modification of the charging system shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present disclosure will be described in detail with reference to the accompanying drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and their description will not be repeated.

[0010] FIG. 1 is a diagram illustrating a charging system according to an embodiment of the present disclosure. Referring to FIG. 1, the charging system according to this embodiment includes a vehicle 100 and an EVSE 300. The EVSE 300 receives a supply of power from a power grid PG. EVSE stands for Electric Vehicle Supply Equipment. The power grid PG is a power network constructed by power transmission and distribution equipment. A plurality of power plants (not shown) are connected to the power grid PG. The power grid PG receives a supply of power from these power plants. In this embodiment, the power grid PG supplies AC power.

[0011] The EVSE 300 incorporates a power supply circuit 310 and includes a charging cable 320. The power supply circuit 310 is electrically connected to the power grid PG. The charging cable 320 has a connector 320a (plug) at its tip and includes a communication line and a power line inside. A single electric wire may serve as both a communication line and a power line. The power supply circuit 310 converts the power supplied from the power grid PG into power suitable for supplying power to the vehicle 100 and outputs the converted power to the charging cable 320. The EVSE 300 outputs AC power from the connector 320a.

[0012] The vehicle 100 includes an inlet 60 to which a connector 320a can be attached / detached. When the connector 320a of the charging cable 320 connected to the main body of the EVSE 300 is connected to the inlet 60 of the parked vehicle 100, the vehicle 100 is electrically connected to the power grid PG via the EVSE 300 (hereinafter also referred to as a "plugged-in state"). On the other hand, for example, when the vehicle 100 is traveling, the vehicle 100 is not electrically connected to either the EVSE 300 or the power grid PG (hereinafter also referred to as a "plugged-out state").

[0013] Vehicle 100 further includes battery 11, SMR (System Main Relay) 12, MG (Motor Generator) 20, PCU (Power Control Unit) 22, and ECU (Electronic Control Unit) 150. ECU 150 includes processor 151, RAM (Random Access Memory) 152, and storage device 153. Storage device 153 is configured to be able to save stored information. Storage device 153 stores programs as well as information used by the programs (e.g., maps, formulas, and various parameters). In this embodiment, processor 151 executes the programs stored in storage device 153, thereby performing various controls in ECU 150 (e.g., charging control of battery 11). However, these processes may be performed only by hardware (electronic circuits) without using software. ECU 150 according to this embodiment corresponds to an example of a "control device" according to the present disclosure.

[0014] Vehicle 100 is configured to be able to run using electric power stored in battery 11. Vehicle 100 is, for example, an electric vehicle (BEV) that does not have an engine (internal combustion engine). However, the vehicle is not limited to this, and may be a PHEV (plug-in hybrid vehicle) that has an internal combustion engine, or another type of electrically powered vehicle (xEV).

[0015] In this embodiment, the battery 11 is a battery pack. The battery pack is made up of a plurality of secondary batteries (generally also called "cells") electrically connected to one another. Each cell making up the battery pack is a lithium-ion secondary battery.

[0016] The cell includes a positive electrode, a negative electrode, an electrolyte (e.g., a nonaqueous electrolyte), and a separator. For example, a wound body in which electrodes and separators are alternately arranged is formed by stacking sheet-like positive electrodes, negative electrodes, and separators and winding the resulting laminate. In such a wound body, a separator is interposed between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive electrode current collector (e.g., aluminum foil) and a positive electrode active material layer. Examples of the positive electrode active material include lithium ion-containing transition metal oxides (NCM-based, LFP, LMFP, etc.). In this embodiment, an NCM-based (nickel-cobalt-manganese ternary system) is used as the positive electrode active material. The negative electrode sheet includes a negative electrode current collector (e.g., copper foil) and a negative electrode active material layer. Examples of the negative electrode active material include carbon-based materials, silicon-containing carbon-based materials, silicon, lithium titanate (LTO), and niobium titanium oxide (NTO). In this embodiment, a carbon-based material (e.g., graphite) is used as the negative electrode active material. The negative electrode is a carbon-based electrode. The active material layers of the positive electrode and negative electrode are formed, for example, by coating a composite containing the active material on the surface of a current collector. In this embodiment, the positive electrode and negative electrode have a monopolar structure. However, this is not limiting, and the positive electrode and negative electrode may have a bipolar structure.

[0017] The above-described wound body (laminate) is sealed in a battery case together with an electrolyte. The positive electrode current collector is electrically connected to a positive electrode terminal. The negative electrode current collector is electrically connected to a negative electrode terminal. A battery 11 (battery assembly) is formed by connecting a plurality of cells having such a configuration in series, for example, as shown in FIG. 1. However, the connection of the cells in the battery assembly is not limited to series and may include parallel connection.

[0018] The battery 11 is provided with a BMS (Battery Management System) 11a that monitors the state of the battery 11. The BMS 11a includes various sensors that detect the state of the battery 11 (for example, voltage, current, and temperature) and a monitoring IC (Integrated Circuit) to which detection signals from the various sensors are input. In this embodiment, a voltage sensor and a temperature sensor are provided for each cell that constitutes the battery 11 (battery pack). However, this is not limiting, and each of the voltage sensor and the temperature sensor may be provided for each of a plurality of cells, or only one may be provided for one battery pack.

[0019] The monitoring IC generates a signal indicating the state of the battery 11 (hereinafter also referred to as a "BMS signal") using the detection signals from the various sensors, and outputs the generated BMS signal to the ECU 150. Based on the BMS signal, the ECU 150 acquires, for example, the temperature, current, voltage, SOC (State of Charge), and SOH (State of Health) of the battery 11. The monitoring IC may have a function of equalizing cell voltages.

[0020] Vehicle 100 further includes a charger 61 and a charging relay 62. Charger 61 and charging relay 62 are located between inlet 60 and battery 11. Each of charger 61 and charging relay 62 is controlled by ECU 150. In this embodiment, a charging line including inlet 60, charger 61, and charging relay 62 is connected between SMR 12 and PCU 22. However, this is not limiting, and a charging line may also be connected between battery 11 and SMR 12.

[0021] The charger 61 charges the battery 11 using power input to the inlet 60 from outside the vehicle. The charger 61 includes a power conversion circuit (e.g., an inverter) and is configured to be able to adjust the charging current. The power conversion circuit performs DC (direct current) / AC (alternating current) conversion. The charging relay 62 switches between connection and disconnection of the electrical path from the inlet 60 to the battery 11. The vehicle 100 further includes a detector 61a that monitors the state of the charger 61. The detector 61a includes various sensors (e.g., a current sensor and a voltage sensor) that detect the state of the charger 61, and outputs the detection results to the ECU 150.

[0022] When the vehicle 100 is plugged in, external charging (i.e., charging of the battery 11 with power from outside the vehicle) becomes possible. Power for external charging is supplied to the inlet 60 from, for example, the power grid PG via a charging cable 320 of the EVSE 300. The charger 61 converts the AC power received by the inlet 60 into DC power suitable for charging the battery 11, and outputs the DC power to the battery 11. When external charging is being performed, the charging relay 62 is closed (connected), and when external charging is not being performed, the charging relay 62 is opened (disconnected).

[0023] The MG 20 is, for example, a three-phase AC motor generator. The MG 20 functions as a traction motor for the vehicle 100. The MG 20 is driven by the PCU 22 to rotate the drive wheels of the vehicle 100. The MG 20 also performs regenerative power generation and outputs the generated power to the battery 11. The vehicle 100 further includes a motor sensor 21 that monitors the state of the MG 20. The motor sensor 21 includes various sensors (for example, a current sensor, a voltage sensor, and a temperature sensor) that detect the state of the MG 20, and outputs the detection results to the ECU 150. The number of traction motors included in the vehicle 100 is arbitrary, and may be one, two, three, or more. The traction motors may be in-wheel motors.

[0024] The PCU 22 drives the MG 20 using power supplied from the battery 11. The SMR 12 switches between connection and disconnection of an electric path from the battery 11 to the PCU 22. The PCU 22 includes, for example, an inverter and a converter. The SMR 12 and the PCU 22 are each controlled by the ECU 150. The SMR 12 is closed (connected) when the vehicle 100 is running. The SMR 12 is also closed when power is exchanged between the battery 11 and the inlet 60 (and ultimately, the outside of the vehicle).

[0025] Lithium-ion secondary batteries discharge and charge through chemical reactions (battery reactions) at the interfaces between the negative electrode active material, the positive electrode active material, and the electrolyte. + ) and electrons (e - ) occurs at the interface of the positive electrode active material, while at the interface of the negative electrode active material, lithium ions (Li + ) and electrons (e - During discharge, the reverse reaction occurs: the release / absorption of lithium ions takes place between the positive electrode sheet and the negative electrode sheet via the separator, thereby charging and discharging the lithium-ion secondary battery.

[0026] During charging of a lithium-ion secondary battery, absorption and diffusion at the negative electrode may not keep up with the supply of lithium ions, resulting in the deposition of lithium metal on the negative electrode surface. Excessive deposition of lithium metal may cause a short circuit between the positive and negative electrodes. Therefore, in controlling the charging of a lithium-ion secondary battery, it is desirable to suppress lithium metal deposition (hereinafter also referred to as "Li deposition") so that excessive lithium metal does not deposit on the electrode surface (especially the negative electrode surface) of the lithium-ion secondary battery. For example, Li deposition can be suppressed by reducing the charging current. However, reducing the charging current lengthens the charging time (the time until charging is completed). Therefore, in this embodiment, the charging current is controlled based on the current boundary value at which Li deposition is likely to occur. This control can prevent the charging current from being reduced more than necessary, thereby preventing the charging time from being extended.

[0027] Specifically, ECU 150 controls the charging current using a first threshold and a second threshold by executing a series of processes shown in Fig. 2, which will be described below. The first threshold indicates a current boundary value at which Li deposition is likely to occur when the charging current of battery 11 exceeds the first threshold. The second threshold is a value smaller than the first threshold and indicates a current boundary value at which Li deposition is likely to occur when the charging current of battery 11 continuously exceeds the second threshold. ECU 150 may obtain the charging current of battery 11 using at least one of the detection result by the current sensor of BMS 11a and the detection result by the current sensor of detector 61a.

[0028] Fig. 2 is a flowchart showing a charging method according to this embodiment. The processing shown in this flowchart is executed by ECU 150. The processing flow shown in Fig. 2 is started, for example, when an external charging start condition is met for vehicle 100. The external charging start condition may be met when vehicle 100 is in a plugged-in state. Furthermore, for vehicle 100 for which timer charging has been scheduled in ECU 150, the external charging start condition may be met when the timer charging start time arrives in the plugged-in state.

[0029] Referring to FIG. 2, in S11, ECU 150 determines the first threshold value and the second threshold value. The first threshold defines a range of charging current at which Li deposition may occur in the battery 11. That is, if the charging current of the battery 11 exceeds the first threshold even momentarily, the possibility of Li deposition occurring increases. Such a first threshold is likely to vary depending on the state of the battery 11. The ECU 150 variably sets the first threshold using, for example, a first map. The first map is, for example, experimentally determined and stored in the storage device 153. The ECU 150 may set the first threshold based on the voltage and temperature of the battery 11. For example, the first map outputs the first threshold when the voltage and temperature of the battery 11 are input. A representative value (e.g., an average value, a median value, or a maximum value) of data determined for each of the multiple cells constituting the battery 11 (battery pack) may be used as the value (voltage and temperature) of the battery 11. Instead of the first map, a trained model obtained by machine learning using AI (artificial intelligence) may be employed.

[0030] The second threshold defines a range of charging current within which Li deposition in the battery 11 is always suppressed. That is, Li deposition does not occur during charging of the battery 11 unless the charging current of the battery 11 exceeds the second threshold. However, if the current load continues and the final charging current (saturated charging current) exceeds the second threshold, the possibility of Li deposition occurring increases. The second threshold varies little with changes in the state of the battery 11. For this reason, the second threshold may be a fixed value. For example, an experimentally determined fixed value (second threshold) may be stored in the storage device 153. Alternatively, the ECU 150 may variably set the second threshold using, for example, a second map. The ECU 150 may decrease the second threshold as the thickness of the SEI (Solid Electrolyte Interphase) coating of the negative electrode increases. For example, the second map outputs the second threshold when the thickness of the SEI coating formed on the surface of the negative electrode is input. The second map may be determined, for example, experimentally and stored in the storage device 153.

[0031] In S12, ECU 150 determines whether the difference between the first threshold and the second threshold is equal to or greater than a predetermined reference value (hereinafter referred to as "Th"). ECU 150 obtains the difference between the first threshold and the second threshold (hereinafter referred to as "difference X") by subtracting the second threshold from the first threshold. If difference X is smaller than Th (NO in S12), ECU 150 determines a predetermined value (hereinafter referred to as "Mx") as a charging margin in S13. Mx is a fixed value. In this case, the charging margin is determined uniformly. Mx is set, for example, taking into account performance variations of chargers 61, so that the charging current during charging of battery 11 does not exceed the second threshold even if the performance of charger 61 is low. If difference X is equal to or greater than Th (YES in S12), ECU 150 determines a charging margin according to difference X within a range smaller than Mx in S14. Specifically, ECU 150 variably sets the charging margin so that the larger the difference X, the smaller the charging margin.

[0032] The greater the difference (difference X) between the first threshold and the second threshold, the less likely lithium metal deposition tends to occur. When difference X is smaller than Th, it is considered that lithium metal deposition is more likely to occur. For this reason, in S13, Mx is determined as the charge margin. On the other hand, when difference X is larger than Th, it is considered that lithium metal deposition is less likely to occur. For this reason, in S14, the charge margin is made smaller than Mx, thereby increasing the charge current of battery 11. Furthermore, in S14, the greater the difference X, the smaller the charge margin is made, and the more unlikely lithium metal deposition becomes, so the charge current is increased.

[0033] After the charging margin is determined in S13 or S14, the ECU 150 determines a charging command value in S15 based on the determined charging margin and a second threshold value. The charging command value indicates a target charging current value. The ECU 150 determines the target charging current value so that the charging current of the battery 11 is lower than the second threshold value by the charging margin. The ECU 150 obtains the target charging current value by subtracting the charging margin from the second threshold value.

[0034] By setting the charge margin as described above, it becomes easier to more reliably suppress lithium metal deposition even when charging control of the lithium ion battery is performed using a low-performance charger. Furthermore, by determining the charge margin using the difference between the first threshold and the second threshold, charging control of the lithium ion battery is performed so that the charging current of the lithium ion battery does not exceed the second threshold, and when it is determined based on the difference that lithium metal deposition is unlikely to occur, the charging current of the lithium ion battery can be increased.

[0035] In the following S16, ECU 150 transmits the charge command value determined in S15 to charger 61. Upon receiving the charge command value, charger 61 controls the charge current of battery 11 so that the charge current of battery 11 approaches the target charge current value indicated by the charge command value. In this way, external charging of battery 11 is performed.

[0036] In the next step S17, the ECU 150 determines whether a charging end condition is met. The charging end condition is met, for example, when the amount of stored power in the battery 11 reaches a target value. The target value may be set automatically by the ECU 150 or the EVSE 300, or may be set by the user. The amount of stored power may be expressed as SOC. The target value may be a value indicating full charge. The charging end condition can be changed as appropriate. For example, the charging end condition may be met when a predetermined time has elapsed since the start of external charging. The charging end condition may also be met in response to a user instruction to stop charging.

[0037] If the charging end condition is not met (NO in S17), the process returns to the first step (S11). This allows external charging to continue. On the other hand, if the charging end condition is met (YES in S17), the process flow ends. This ends external charging.

[0038] FIG. 3 is a time chart showing an example of operation according to the charging method shown in FIG. 2. In FIG. 3, lines L1, L2, and L3 respectively indicate the transitions of the first threshold, the second threshold, and the target charging current value (charging command value) in the charging method shown in FIG. 2. In the example shown in FIG. 3, the second threshold is constant. In the charging method shown in FIG. 2, the ECU 150 variably controls the charging current of the battery 11 from the start of charging of the battery 11 until the difference X (=first threshold−second threshold) falls below Th. In the example shown in FIG. 3, the difference X falls below Th at timing t1. After the difference X falls below Th, the ECU 150 maintains the charging current of the battery 11 at the target charging current value (=second threshold−Mx) determined based on the second threshold.

[0039] As shown in FIG. 3, in a lithium-ion battery, the difference between the first threshold and the second threshold is large immediately after the start of charging, and this difference tends to decrease over time and eventually converge to a constant value. The charging method shown in FIG. 2 variably controls the charging current of the lithium-ion battery during the period immediately after the start of charging when the difference between the first threshold and the second threshold is large. Because lithium metal is unlikely to deposit during this period, variably controlling the charging current of the lithium-ion battery using a charger with low responsiveness can suppress lithium metal deposition even if the charging current of the lithium-ion battery does not sufficiently track the target value. Furthermore, the charging method shown in FIG. 2 maintains the charging current of the lithium-ion battery at a target value determined based on the second threshold during the period when the difference between the first threshold and the second threshold is small. Therefore, even a charger with low responsiveness can easily cause the charging current of the lithium-ion battery to track (maintain) the target value.

[0040] As described above, the charging method according to this embodiment includes the processes shown in Fig. 2. This charging method includes determining first and second thresholds for the charging current of a lithium ion battery (battery 11) at which lithium metal precipitates on the electrodes of the lithium ion battery (S11), and controlling the charging current of the lithium ion battery using the difference between the first and second thresholds and the second threshold (S12 to S16). ECU 150 (control device) executes the charging method for battery 11 (lithium ion battery).

[0041] The charging method according to this embodiment will be described below in comparison with comparative examples. As a first comparative example, it is possible to control the charging current of the lithium-ion battery based on the first threshold value, regardless of the difference between the first threshold value and the second threshold value. However, with this charging method, depending on the responsiveness of the charger, it may be impossible to make the charging current of the lithium-ion battery follow the first threshold value, which changes from moment to moment. Furthermore, as shown by line L4 in FIG. 3, as a second comparative example, it is possible to maintain the charging current of the lithium-ion battery at a target charging current value (= second threshold value - Mx) determined based on the second threshold value, regardless of the difference between the first threshold value and the second threshold value. However, with this charging method, the charging current of the lithium-ion battery will always be small, resulting in a long charging time (the time until charging is completed).

[0042] In the charging method according to this embodiment, the second threshold is used to control the charging current of the lithium-ion battery. By controlling the charging current of the lithium-ion battery so that it does not exceed the second threshold, lithium metal deposition can be easily suppressed. Because the second threshold varies little over time, even a charger with low responsiveness can make the charging current of the lithium-ion battery follow the second threshold. Furthermore, in lithium-ion batteries, the greater the difference between the first and second thresholds, the less likely lithium metal deposition tends to occur. Therefore, in the charging method described above, this difference is also used to control the charging current of the lithium-ion battery. This charging method controls the charging of the lithium-ion battery so that the charging current of the lithium-ion battery does not exceed the second threshold. If it is determined based on the difference that lithium metal deposition is unlikely to occur, the charging current of the lithium-ion battery is increased, thereby shortening the charging time. Even if the performance of the charger 61 installed in the vehicle 100 is low, the ECU 150 can accurately suppress lithium metal deposition when charging the battery 11. In addition, ECU 150 (control device) may be configured to select a charging method from options including the charging method shown in Figure 2, the charging method according to the first comparative example, and the charging method according to the second comparative example, and to execute the selected charging method.

[0043] In the above embodiment, charging control of the lithium ion battery is performed using a charger 61 mounted on the vehicle 100. However, this is not limited to this, and charging control of the lithium ion battery may be performed using a charger mounted on the EVSE. Figure 4 is a diagram showing a modification of the charging system shown in Figure 1.

[0044] Referring to FIG. 4, the EVSE 300A incorporates a charger 331, a detector 331a, and a control device 332. The charger 331 includes a power conversion circuit (e.g., an inverter) and is configured to be able to adjust the charging current. The detector 331a includes various sensors (e.g., a current sensor and a voltage sensor) that detect the state of the charger 331 and outputs the detection results to the control device 332. When the connector 320a of the EVSE 300A is connected to the inlet 60A of the vehicle 100A, the vehicle 100A enters a plugged-in state. In the plugged-in state of the vehicle 100A, the ECU 150A performs external charging of the battery 11 while communicating with the control device 332 via the charging cable 320. During external charging, the charger 331 converts AC power supplied from the power grid PG into DC power and outputs the DC power to the connector 320a. That is, the EVSE 300A outputs DC power. The DC power output from the EVSE 300A to the vehicle 100A is input to the inlet 60A and is used to charge the battery 11.

[0045] ECU 150A performs external charging of battery 11 using the charging method shown in Fig. 2. In S16, ECU 150A transmits the charge command value determined in S15 to control device 332. Having received the charge command value, control device 332 controls charger 331 so that the charge current of battery 11 approaches the target charge current value indicated by the charge command value. In this way, external charging of battery 11 is performed. Control device 332 may obtain the charge current using the detection result by the current sensor of detector 331a.

[0046] The processing flow shown in Fig. 2 can be modified as appropriate. For example, the order of processing may be changed or unnecessary steps may be omitted depending on the purpose. Furthermore, the content of any of the processing steps may be changed. For example, in the processing flow shown in Fig. 2, when the difference X matches Th, the processing proceeds to S14, but the processing may be modified so that it proceeds to S13.

[0047] The configuration of the vehicle is not limited to the configuration described above (see FIG. 1). For example, the vehicle may be configured to be capable of wireless charging. A vehicle performing wireless charging may be considered to be in a state equivalent to the "plugged-in state" described above when the alignment between the power transmission unit (e.g., a power transmission coil) on the power supply equipment side and the power receiving unit (e.g., a power receiving coil) on the vehicle side is completed.

[0048] The lithium-ion battery may be installed in a resource other than an automobile. The resource may be a moving body other than an automobile (railroad vehicle, ship, airplane, drone, walking robot, robot cleaner, etc.). The resource may be an electrical appliance (lighting device, air conditioner, cooking appliance, television, refrigerator, washing machine, etc.). The lithium-ion battery to be charged may be a stationary lithium-ion battery used in a building (house, factory, etc.) or outdoors.

[0049] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0050] 11 Battery, 11a BMS, 60,60A Inlet, 61 Charger, 61a Detector, 100,100A Vehicle, 150,150A ECU, 300,300A EVSE, 331 Charger, 331a Detector, 332 Control Unit.

Claims

1. determining a first threshold value and a second threshold value for a charging current of the lithium ion battery at which lithium metal deposits on an electrode of the lithium ion battery; controlling a charging current of the lithium ion battery using the second threshold and a difference between the first threshold and the second threshold; Including, the first threshold indicates a current boundary value at which precipitation of the lithium metal is likely to occur when the charging current of the lithium ion battery exceeds the first threshold, The second threshold is a value smaller than the first threshold and indicates a current boundary value at which precipitation of the lithium metal is likely to occur when the charging current of the lithium ion battery continuously exceeds the second threshold.

2. Controlling the charging current comprises: determining a charge margin using the difference between the first threshold and the second threshold; determining a target charging current value such that the charging current of the lithium ion battery is lower than the second threshold by the charging margin; controlling the charging current of the lithium ion battery so as to approach the target charging current value; The charging method of claim 1 , comprising:

3. Controlling the charging current comprises: determining whether the difference between the first threshold value and the second threshold value is greater than a reference value; When the difference between the first threshold value and the second threshold value is smaller than the reference value, determining a predetermined value as the charging margin; determining the charging margin so that the charging margin is smaller than the predetermined value when the difference between the first threshold value and the second threshold value is larger than the reference value, and so that the charging margin becomes smaller as the difference between the first threshold value and the second threshold value increases; The charging method of claim 2 , comprising:

4. Controlling the charging current comprises: variably controlling a charging current of the lithium ion battery from the start of charging of the lithium ion battery until the difference between the first threshold value and the second threshold value falls below a predetermined value; After the difference falls below the predetermined value, maintaining the charging current of the lithium ion battery at the target charging current value determined based on the second threshold value; The charging method of claim 1 , comprising:

5. A charging system comprising a lithium ion battery and a control device that executes the charging method according to any one of claims 1 to 4 with respect to the lithium ion battery.

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