Electricity storage device and control method

Abstract

The invention provides a power storage device and a control method, wherein safety is ensured, and a long cruising distance can be maintained even if an electric vehicle is used for a long period of time through improvement of cycle characteristics and the like. A control method for controlling a power storage device provided with a lithium metal battery, in which the lithium metal battery is controlled so as to be charged at a rate of 0.2 C or less and discharged at a rate of 1.0 C to 2.0 C (inclusive).

Description

Technical Field

[0001] The present invention relates to a power storage device and a control method. Background Art

[0002] In recent years, in order to ensure that more people can obtain energy that is suitable, reliable, sustainable, and advanced, research and development related to secondary batteries that contribute to energy efficiency is being carried out. Patent document 1 describes an invention related to charge and discharge management for the purpose of suppressing battery deterioration using a secondary battery in a mobile body. The use of high-capacity-density secondary batteries is effective in improving the cruising range of a mobile body. Patent document 2 discloses a method for controlling an electric vehicle using a secondary battery. Patent document 2 discloses a metal lithium battery using metal lithium in the negative electrode as a high-capacity-density battery as a secondary battery that can be used.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2023-120237

[0004] Patent Document 2: Japanese Patent Application Laid-Open No. 2023-38288 Summary of the Invention

[0005] Ensuring safety and maintaining a high driving range even during long-term use of electric vehicles are key challenges in secondary battery technology. In lithium metal batteries (LMBs), a layer of inactive lithium metal forms on the surface of the metallic lithium used as the negative electrode during charging and discharging. The formation of this layer of inactive lithium metal reduces battery capacity and deteriorates cycle characteristics. The formation of this layer in lithium metal batteries also increases the thickness of the battery cells.

[0006] The present invention aims to solve the above-mentioned problems by ensuring safety and maintaining a high cruising range even in long-term use of electric vehicles by improving cycle characteristics, etc., and further contributing to energy efficiency.

[0007] In order to solve the above-mentioned problems and achieve the object, the present invention adopts the following means.

[0008] (1) A control method according to one embodiment of the present invention controls a power storage device including a lithium metal battery, wherein the lithium metal battery is controlled to be charged at a rate of 0.2 C or less and discharged at a rate of 1.0 C or more and 2.0 C or less.

[0009] (2): In addition to the above-mentioned solution (1), the lithium metal battery may be charged after being discharged according to the charging resistance.

[0010] (3): Based on the above-mentioned scheme (1), the power storage device may also include a first battery which is a lithium metal battery and a second battery which is a secondary battery other than a lithium metal battery, and when discharging from the power storage device, power is supplied from the second battery to the first battery.

[0011] (4): In the embodiment of (3) above, the power supply from the second battery to the first battery may be performed at a rate of 0.2C or less.

[0012] (5): Based on the above scheme (1), the power storage device may also include a first battery which is a lithium metal battery and a third battery which is a secondary battery other than a lithium metal battery, and when charging the power storage device, the first battery is charged at a rate of less than 0.2C, and the third battery is charged at a rate exceeding 0.2C.

[0013] (6): Based on the above-mentioned scheme (1), the power storage device may also include a first battery which is a lithium metal battery and a second battery and a third battery which are secondary batteries other than lithium metal batteries, the second battery having a higher capacity density than the third battery, and the third battery having a higher output density than the second battery. When charging the power storage device, the charging rate of the first battery is less than 0.2C, the charging rate of the second battery is a rate exceeding 0.2C, and the charging rate of the third battery is higher than the charging rate of the second battery. When discharging from the power storage device, power is supplied from the second battery to the first battery.

[0014] (7): In the above-mentioned aspect (5) or (6), the power storage device may be mounted on an electric vehicle and supply regenerative electric power to the third battery.

[0015] (8) An electric storage device according to one aspect of the present invention includes a plurality of battery blocks including an LMB block composed of a plurality of lithium metal battery cells, and each battery block is detachably configured.

[0016] (9): In the above-mentioned aspect (8), the power storage device may include a plurality of LMB blocks.

[0017] (10): In the above aspect (8), the power storage device may include a second battery block composed of secondary battery cells other than lithium metal.

[0018] (11): In addition to the above-mentioned aspect (10), the LMB block and the second battery block may be configured to be electrically connectable.

[0019] According to the above aspect (1), the rate of formation of a lithium inactive material layer on the negative electrode lithium metal is reduced during charge and discharge of the lithium metal battery, thereby ensuring safety and improving the cycle characteristics of the power storage device.

[0020] According to the above scheme (2), the lithium inactive material that is easily formed in the form of dendrites on the negative electrode during charging is removed from the negative electrode by discharge before charging to flatten it, thereby suppressing the local thick formation of lithium inactive material on the negative electrode during charging, and improving the cycle characteristics.

[0021] According to the schemes (3) to (5) above, a lithium metal battery that exhibits a high capacity although its charging rate is limited from the viewpoint of suppressing the formation of lithium inactive matter is charged at a charging rate that can suppress the growth of lithium inactive matter, and the SOC of batteries other than the lithium metal battery that is charged at a higher charging rate is adjusted in such a way that becomes lower during charging, thereby increasing the SOC of the entire storage device over a long period of time, improving the cycle characteristics, and improving the charging time and charging frequency.

[0022] According to the scheme (6) above, during charging, priority is given to charging batteries that can increase the charging rate. In addition, the difference between the discharge rate and the charging rate of lithium metal batteries that deviate from the charging rate and the discharge rate that can be appropriately used can be compensated, thereby improving the cycle characteristics and increasing the SOC of the entire storage device, which can improve the charging time and charging frequency.

[0023] According to the above-mentioned aspect (7), the regenerative electric power is supplied to the battery having a higher battery capacity, thereby making it possible to increase the SOC of the entire power storage device over a long period of time.

[0024] According to the above configurations (8) and (9), even if the cycle characteristics of the lithium metal batteries in the plurality of battery blocks deteriorate due to long-term use, a high cruising range can be maintained by replacing the batteries.

[0025] According to the above schemes (10) and (11), during charging and discharging, the lithium metal battery having a charging rate and a discharging rate for maintaining high cycle characteristics is charged and discharged at an appropriate rate, and the second battery can be charged and discharged at a rate higher than that of the lithium metal battery, which can improve the overall SOC of the storage device over a long period of time. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a block diagram schematically showing the configuration of an electric vehicle equipped with a power storage device according to one embodiment of the present invention.

[0027] Figure 2 It is used to illustrate the Figure 1 A circuit diagram of a method for controlling charging of a power storage device.

[0028] Figure 3 It is used to illustrate the Figure 1 A circuit diagram of a method for controlling discharge of a power storage device.

[0029] Figure 4 It means Figure 1 A block diagram of a control method for discharging in a power storage device.

[0030] Figure 5 It is used to illustrate the Figure 2 A circuit diagram of a method for controlling charging of a power storage device according to a modified example of FIG.

[0031] Figure 6 It is used to illustrate the Figure 2 A circuit diagram of a method for controlling discharge of a power storage device according to a modified example of FIG.

[0032] Figure 7 It is used to illustrate the Figure 2 A circuit diagram of a method for controlling charging of a power storage device according to another modified example.

[0033] Figure 8 It is used to illustrate the Figure 2 A circuit diagram of a method for controlling discharge of a power storage device according to another modified example.

[0034] Figure 9 This is a graph showing the capacity retention rate of the recycled metal battery under the respective charge and discharge conditions of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0035] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0036] Figure 1 This is a block diagram schematically showing the configuration of an electric vehicle equipped with a power storage device according to one embodiment of the present invention. Figure 1 The thick solid lines in the figure represent mechanical connections, the double-pointed lines represent power wiring, and the thin solid lines represent control signals. Figure 1 The illustrated single-motor (1MOT) electric vehicle includes a motor generator (MG) 11, a PDU (Power Drive Unit) 13, and a power storage device 100 according to one embodiment. Components of the electric vehicle will be described below.

[0037] The power storage device 100 includes a battery block including lithium metal batteries. Figure 1 In the example shown, an electric vehicle equipped with a power storage device 100 including battery blocks B1 to B3 composed of lithium metal battery cells is described. Figure 1In the description, the power storage device 100 is described as having three battery blocks. However, as long as the device has multiple battery blocks composed of lithium metal battery cells, the number of battery blocks is not limited. For example, the power storage device may have four or more battery blocks.

[0038] The motor generator 11 is driven by electric power supplied from the power storage device 100 to generate power for driving the electric vehicle. The torque generated by the motor generator 11 is transmitted to the drive wheels W via a gearbox GB, which includes a variable speed or fixed speed, and a differential gear D. When the electric vehicle is decelerating, the motor generator 11 operates as a generator, outputting braking force for the electric vehicle. The regenerative power generated by the motor generator 11 operating as a generator is stored in a battery included in the power storage device 100.

[0039] The PDU 13 converts a DC voltage into an AC voltage and supplies a three-phase current to the motor generator 11. The PDU 13 converts an AC voltage input during a regenerative operation of the motor generator 11 into a DC voltage.

[0040] The power storage device 100 is as follows Figure 1 As shown, the power storage device 100 includes multiple battery blocks B1-B3, a VCU (Voltage Control Unit) 101, voltage sensors 103p, 103e, and 103a, current sensors 105p, 105e, and 105a, a vehicle speed sensor 108, a switch unit 111, an ECU (Electronic Control Unit) 109, and an APS (Accelerator Position Sensor, not shown). Each battery block B1-B3 is detachably mounted on the power storage device 100. Each battery block B1-B3 includes multiple battery cells.

[0041] Battery blocks B1-B3, for example, are composed of multiple lithium metal battery cells. Lithium metal battery cells use either or both lithium metal and a lithium alloy in the negative electrode. The lithium alloy can be an alloy of lithium, any element selected from the group consisting of magnesium, aluminum, and indium, and unavoidable impurities, with the lithium content in the alloy being 90% or greater and less than 100%. The unavoidable impurity content in the aluminum alloy is 0.05% by mass or less.

[0042] The plurality of battery blocks B1 to B3 are preferably electrically connected to one another. By electrically connecting the plurality of battery blocks B1 to B3 to one another, the battery blocks B1 to B3 can supply power to one another during discharge, such as while the electric vehicle is traveling.

[0043] The VCU 101 boosts the output voltage of battery blocks B1-B3 while maintaining it in DC form. During deceleration of the electric vehicle, the VCU 101 steps down the voltage of the power generated by the motor generator 11 and converted to DC. Furthermore, the VCU 101 steps down the output voltage of battery blocks B1-B3 while maintaining it in DC form. The power stepped down by the VCU 101 is then used to charge battery blocks B1-B3, for example. The voltage and current levels of the DC power output by the VCU 101 are controlled by the ECU 109.

[0044] Voltage sensor 103a detects voltage Va of battery block B1. A signal indicating voltage Va detected by voltage sensor 103a is sent to ECU 109. Voltage sensor 103e detects voltage Ve of battery block B2. A signal indicating voltage Ve detected by voltage sensor 103e is sent to ECU 109. Voltage sensor 103p detects voltage Vp of battery block B3. A signal indicating voltage Vp detected by voltage sensor 103p is sent to ECU 109.

[0045] When each battery block B1-B3 is in the open state, the voltages Va, Ve, and Vp are open-circuit voltages (OCV). The voltages Va, Ve, and Vp detected by the voltage sensor 103a, 103e, and 103p, acquired by the ECU 109, have a predetermined relationship with each of the battery blocks B1, B2, and B3. A map is acquired in advance. Based on this map, the ECU 109 can derive the state of charge (SOC) of each battery block B1-B3 from the acquired voltages Va, Ve, and Vp.

[0046] Current sensor 105a detects the input / output current Ia of battery block B1. Signals indicating the input / output current Ia detected by current sensor 105a are transmitted to ECU 109. Current sensor 105e detects the input / output current Ie of battery block B2. Signals indicating the input / output current Ie detected by current sensor 105e are transmitted to ECU 109. Current sensor 105p detects the input / output current Ip of battery block B3. Signals indicating the input / output current Ip detected by current sensor 105p are transmitted to ECU 109.

[0047] The vehicle speed sensor 108 detects the running speed (vehicle speed) VP of the electric vehicle. A signal indicating the vehicle speed VP detected by the vehicle speed sensor 108 is sent to the ECU 109 .

[0048] The switch unit 111 includes a contactor MCa that opens and closes the current path from the battery block B1 to the PDU 13 or VCU 101, a contactor MCe that opens and closes the current path from the battery block B2 to the VCU 101, and a contactor MCp that opens and closes the current path from the battery block B3 to the VCU 101. Each of the contactors MCa, MCe, and MCp is opened and closed under the control of the ECU 109.

[0049] The ECU 109 controls the PDU 13 and VCU 101 and opens and closes the switch unit 111. The ECU 109 determines the electric vehicle's driving state based on the vehicle speed VP indicated by the signal from the vehicle speed sensor 108. If the electric vehicle is not driving, the ECU 109 controls the PDU 13 so that all switching elements in the PDU 13 are turned off, and controls the VCU 101 so that all switching elements in the VCU 101 are turned off. This control results in an open circuit state for each circuit.

[0050] Figure 2 It is used to illustrate the Figure 1 This circuit diagram illustrates a method for controlling the charging of the power storage device 100. The diagram shows an extracted portion of the power storage device 100, including the ECU 109 and battery blocks B1 to B3. The power storage device 100 includes a plurality of battery blocks B1 to B3. The plurality of battery blocks B1 to B3 included in the power storage device 100 are connected in parallel. Battery blocks B1 to B3 are LMB blocks composed of lithium metal battery cells 30.

[0051] exist Figure 2 For ease of explanation, arrows indicate the power supplied from the power source to each battery block B1-B3. When connected to an external power source E, such as a power station, the ECU 109 controls charging of battery blocks B1-B3 so that the charging rate is 0.2C or less. This charging rate control is achieved, for example, by the ECU 109 calculating the current required for each block and commanding a total current value to the external power source E. The ECU 109 then distributes the current input from the external power source E to each block according to the calculated value.

[0052] Before charging, it is preferable to pre-discharge battery blocks B1-B3. The discharge rate is preferably 1.0C or higher. By rapidly discharging the lithium metal battery before charging, lithium inactive materials, which tend to form as dendrites on the negative electrode during charging, can be removed from the negative electrode during discharge, flattening the surface and preventing thick localized buildup of lithium inactive materials on the negative electrode during charging. For rapid discharge, the number of battery blocks is selected, with the discharge being performed under the constraint that the discharge rate for each LMB block is between 1.0C and 2.0C, by opening and closing contactors connected in series with battery blocks B1-B3.

[0053] The discharge before charging of the lithium metal battery is implemented, for example, based on the charging resistance of the lithium metal battery. It is believed that when the charging resistance is high, the layer of the precipitated inactive lithium metal becomes thicker, and the lithium inactive material formed in a dendritic shape is more likely to cause a short circuit than when the charging resistance is low. Therefore, it is preferred to discharge before charging. Thus, it is preferred that, during charging, as an identification process, the charging resistance is measured, and whether to perform rapid discharge is identified based on the charging resistance of the lithium metal battery.

[0054] ECU109 controls the constant current for each battery block for a time Δt to confirm the charge and discharge capacity C of the battery block. When it is determined that the charge and discharge capacity C is below the specified value, the battery block can be removed and a new battery block can be installed, which can be displayed on the instrument panel.

[0055] During this process, the charge / discharge capacity C can be calculated using ΔAh / ΔSOC. ΔAh is the product of the constant current Ic and the time Δt. ΔSOC is the difference between SOC(t+Δt) and SOC(t). SOC(t) is the SOC of the battery block immediately before constant current control charging / discharging. SOC(t+Δt) is the SOC of the battery block immediately after constant current control charging / discharging. In other words, the charge / discharge capacity C is expressed by the following equation.

[0056] C=ΔAh / ΔSOC=〔(Ic×Δt) / {SOC(t+Δt)-SOC(t)}

[0057] Figure 3 It is used to illustrate the Figure 1 1 is a circuit diagram of a method for controlling the power storage device 100 during discharge, and a portion of the power storage device 100 including the ECU 109 and the battery blocks B1 to B3 is extracted and shown. Figure 4 It means Figure 1 A block diagram of a control method for discharging in a power storage device.

[0058] During discharge, the ECU 109 first obtains the voltage Va of the battery block B1 detected by the voltage sensor 103 a , the voltage Ve of the battery block B2 detected by the voltage sensor 103 e , and the voltage Vp of the battery block B3 detected by the voltage sensor 103 p (step S1 ).

[0059] Next, the accelerator opening is measured using the APS, and the output corresponding to the load is calculated (step S2 ).

[0060] Next, based on the voltage measured in step S1 and the output calculated in step S2 , the current value flowing through each battery pack when the combination of battery packs to be used is adjusted is calculated (step S3 ).

[0061] Next, based on the calculation result in step S3 , the combination of battery blocks B1 to B3 and the current value to flow current are determined so that the current value of the lithium metal battery blocks B1 to B3 becomes 0 or a discharge rate of 1.0 to 2.0 C (step S4 ).

[0062] Next, the switch unit 111 is controlled to open and close contactors MCa, MCe, and Mcp in accordance with the combination of battery blocks through which current is to flow, as determined in step S4. Current output commands are issued to each battery block B1-B3 (step S5). The output current is voltage-controlled by the VCU 101 and then supplied to the motor generator 11 via the PDU 13.

[0063] Figure 5 It is used to illustrate the Figure 2 A circuit diagram of a method for controlling charging of a power storage device according to a modified example, Figure 6 It is used to illustrate the Figure 2 A circuit diagram of a method for controlling discharge of a power storage device according to a modified example of FIG. Figure 5 as well as Figure 6 In FIG, a portion of the power storage device is extracted and shown. Figure 5 as well as Figure 6 The power storage device of which a part of the circuit is shown in FIG has a battery block B4 composed of battery cells 40 other than lithium metal batteries in addition to the battery blocks B1 and B3 composed of lithium metal battery cells. Figures 1-3 The power storage device 100 shown is different. Other structures can be made the same. Figure 5 、 6 In the illustrated power storage device as well, the SOC of each of the battery blocks B1 , B2 , and B4 can be derived in the same manner as in power storage device 100 .

[0064] Battery block B4 includes multiple power storage cells, such as lithium-ion secondary batteries or nickel-metal hydride batteries, whose negative electrodes are not made of lithium metal. In this embodiment, battery block B4 is also referred to as a second battery or a third battery. Battery block B4 is not limited to secondary batteries such as the aforementioned lithium-ion batteries and nickel-metal hydride batteries. For example, capacitors (condensers, capacitors) can be used, although their storage capacity is small but they can charge and discharge large amounts of electricity in a short period of time. A battery block is also referred to as a battery module.

[0065] Lithium-ion secondary batteries are categorized into, for example, high-output and high-capacity lithium-ion secondary batteries. High-output lithium-ion secondary batteries have a high output density but a relatively low capacity density. High-capacity lithium-ion secondary batteries, on the other hand, have a high capacity density but a relatively low output density.

[0066] High-output lithium-ion batteries and high-capacity lithium-ion batteries have different characteristics. High-output lithium-ion secondary batteries are lithium-ion secondary batteries, and compared with high-capacity lithium-ion batteries, their energy weight density is lower, but their output weight density is higher. High-capacity lithium-ion secondary batteries are lithium-ion secondary batteries, and compared with high-output lithium-ion secondary batteries, their output weight density is lower, but their energy weight density is higher. Thus, high-capacity lithium-ion secondary batteries are relatively superior in terms of energy weight density, while high-output lithium-ion secondary batteries are relatively superior in terms of output weight density. Energy weight density refers to the amount of electricity per unit weight (Wh / kg), and output weight density refers to the amount of electricity per unit weight (W / kg). Examples of high-output lithium-ion secondary batteries include lithium-ion secondary batteries using graphite, hard carbon, or lithium titanate (LTO: Lithium Titanium Oxide) in the negative electrode.

[0067] The control of the power storage device in the modified example can also be performed in the same manner as the above-described charge and discharge control.

[0068] The charging and discharging rates can also be adjusted to account for the different characteristics of battery block B4 from those of battery blocks B1 to B3. For example, even when lithium-ion secondary batteries, particularly high-power lithium-ion secondary batteries, are charged at a rate exceeding 0.2C, no degradation in cycle characteristics is observed.

[0069] As described above, since the power storage device includes battery blocks having different characteristics, the ECU 109 performs power distribution control using the VCU 101 so as to effectively utilize the characteristics of the battery blocks B1 , B3 , and B4 having different characteristics.

[0070] For example, during charging, battery block B4 is prioritized. Specifically, battery blocks B1 and B3 are charged at a rate of 0.2C or less, while battery block B4 is charged at a rate exceeding 0.2C. More preferably, battery block B4 is charged at a rate exceeding 1.0C. This power distribution control improves the overall storage capacity (SOC: State of Charge) of the power storage device, even with a relatively short charging time.

[0071] The regenerative power generated by the motor generator 11 is preferentially input to the battery block B4. Preferably, the power is input only to the battery block B4, or the power input to the battery blocks B1 and B3 is input at a rate of 0.2C or less and the remaining power is input to the battery block B4.

[0072] During discharge, ECU 109 can control VCU 101 so that the discharge rate of battery blocks B1 and B3 becomes 1.0C or higher and 2.0C or lower by the same control method as the above embodiment, and the discharge rate of battery block B4 becomes higher than that of battery blocks B1 and B3.

[0073] Furthermore, when the battery block B4 is composed of a lithium-ion secondary battery cell, it is preferred that the battery blocks B1, B3, and B4 are electrically connected and controlled so that power is supplied from the battery block B4 to one or both of the battery blocks B1 and B3 at a rate of 0.2C or less. The ECU is capable of supplying power from the battery block B4 to one or both of the battery blocks B1 and B3 by means of a boost circuit. The power supply from the above-mentioned battery block B4 to the battery blocks B1 and B3 is performed when the SOC of the battery block B4 is above a specified value and the SOC of the battery blocks B1 and B3 is below 50%, and is not performed when this condition is not met. The specified value of the SOC of the battery block B4 can be set to, for example, 30% or more, and is preferably set to 50%.

[0074] By supplying power from the battery block B4 to the battery blocks B1 and B3 composed of the lithium metal battery cells 30 at a rate of 0.2C or less, the lithium metal battery cells can be charged within a range where degradation of cycle characteristics is minimal.

[0075] By reducing the SOC of battery block B4 without changing the overall SOC of the power storage device, battery block B4 can be charged preferentially using external power at charging stations, enabling more charging in a shorter period of time. This results in a higher overall SOC of the power storage device over the long term, improving cycle characteristics and reducing charging time and frequency. While a battery block composed of lithium metal battery cells requires approximately five hours of charging at a rate of 0.2C or less, this control method shortens charging time and ensures high commercial quality.

[0076] Figure 7 It is used to illustrate the Figure 2 A circuit diagram of a method for controlling charging of a power storage device according to another modified example. Figure 8 It is used to illustrate the Figure 2 A circuit diagram of a method for controlling discharge of a power storage device according to another modified example. Figure 7 as well as Figure 8In the example shown, battery block B4 is composed of high-power lithium-ion secondary battery cells 40, and battery block B5 is composed of high-capacity lithium-ion secondary battery cells 50. In this embodiment, either high-power or high-capacity lithium-ion batteries can be used as the second and third batteries, but it is preferable to use battery block B5 composed of high-capacity lithium-ion secondary battery cells 50 as the second battery, and it is preferable to use battery block B4 composed of high-power lithium-ion secondary battery cells 40 as the third battery.

[0077] exist Figure 7 as well as Figure 8 The power storage device, a portion of which is shown in FIG, can also be charged and discharged using the same control method as in the above embodiment. Power distribution control using the VCU 101 is performed in a manner that effectively utilizes the characteristics of the battery blocks B1, B3 and the battery blocks B4, B5, each of which has different characteristics.

[0078] During charging, ECU 109 controls the battery blocks B4 and B5 to supply power preferentially over battery blocks B1 and B3. ECU 109 controls the battery blocks B1 and B3 to be charged at a rate of 0.2C or less, and controls the battery blocks B4 and B5 to be charged at a rate exceeding 0.2C.

[0079] During discharge, the ECU 109 can control the VCU 101 so that the discharge rate of battery blocks B1 and B3 is between 1.0C and 2.0C, and the discharge rate of battery blocks B4 and B5 is higher than that of battery blocks B1 and B3, using the same control method as the above-mentioned embodiment. The ECU 109 controls the VCU so that the discharge rate of battery block B4 is higher than that of battery block B5. Here, preferably, battery blocks B1, B3, B4, and B5 are electrically connected, and control is performed so that power is supplied from battery block B4 to one or both of battery blocks B1 and B3 at a rate of 0.2C or less. Similarly, control is performed so that power is supplied from battery block B5 to one or both of battery blocks B1 and B3 at a rate of 0.2C or less. Preferably, power is also supplied from battery block B5, which is composed of high-capacity lithium-ion secondary battery cells 50, to battery block B4, which is composed of high-output lithium-ion secondary battery cells 40. The power supply from battery block B4 to battery blocks B1 and B3 is enabled when the SOC of battery block B4 is above a specified value and the SOC of battery blocks B1 and B3 is below 50%. It is not enabled if these conditions are not met. This specified value can be set to, for example, 30%, and is preferably set to 50%. Similarly, the power supply from battery block B5 to battery blocks B1 and B3 is enabled when the SOC of battery block B5 is above a specified value and is not enabled if it is below the specified value. This specified value can be set to, for example, 30%, and is preferably set to 50%.

[0080] By supplying power between battery blocks within the power storage device within a specified rate range, the SOC of the battery blocks within the power storage device can be balanced to an appropriate value, resulting in a reduction in charging frequency, a shortened charging time, and a longer life of the lithium metal battery.

[0081] exist Figure 7 as well as Figure 8 In the storage device showing a portion of the circuit diagram, regenerative power is preferentially input to battery block B4. Preferably, it is input only to battery block B4, or only to battery block B4 and battery block B5, or the input to battery blocks B1 and B3 is input at a rate of less than 0.2C, the input to battery block B5 is input at a rate of less than 0.5C, and the remaining power is input to battery block B4.

[0082] While the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. Various changes or improvements can be applied to the above embodiments. Such changes or improvements are also included in the technical scope of the present invention.

[0083] [Example]

[0084] Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to the following examples.

[0085] A lithium metal battery cell with a negative electrode composed of lithium metal was produced using an electrolyte containing a lithium salt containing fluorine.

[0086] [Example 1]

[0087] As Example 1, the capacitance of the lithium metal battery was measured when the battery was repeatedly charged and discharged at a rate of 0.2C and a rate of 1.0C at 25°C, with one cycle consisting of charging at a rate of 0.2C and discharging at a rate of 1.0C. The capacity retention rate of the lithium metal battery was calculated over five cycles, with the capacitance after one cycle being considered 100%.

[0088] [Comparative Example 1]

[0089] The capacity retention rate of the lithium metal battery per five cycles was calculated in the same manner as in Example 1, except that the charge rate was changed to 0.33 C and the discharge rate was changed to 0.33 C.

[0090] Figure 9 This is a graph showing the capacity retention rate of the recycled metal battery under the respective charge and discharge conditions of Example 1 and Comparative Example 1.

[0091] like Figure 9 As shown, it was confirmed that when charging and discharging were performed at a charge rate of 0.2C or less and a discharge rate of 1.0C or more and 2.0C or less, superior cycle characteristics were exhibited compared to when charging and discharging were performed at a charge rate exceeding 0.2C and a discharge rate less than 1.0C. Based on these results, it was confirmed that by controlling the battery block composed of lithium metal battery cells to charge at a rate of 0.2C or less and discharge at a rate of 1.0C or more and 2.0C or less, the battery life was significantly extended, thereby increasing the cruising range.

Claims

1. A control method for controlling a power storage device including a lithium metal battery, wherein: The lithium metal battery is controlled to be charged at a rate of 0.2C or less and discharged at a rate of 1.0C or more and 2.0C or less.

2. The control method according to claim 1, wherein: The lithium metal battery is charged after being discharged according to the charging resistance.

3. The control method according to claim 1, wherein: The power storage device includes a first battery which is a lithium metal battery and a second battery which is a secondary battery other than a lithium metal battery. During discharge from the power storage device, electric power is supplied from the second battery to the first battery.

4. The control method according to claim 3, wherein: The power is supplied from the second battery to the first battery at a rate of 0.2C or less.

5. The control method according to claim 1, wherein: The power storage device includes a first battery which is a lithium metal battery and a third battery which is a secondary battery other than a lithium metal battery. When charging the power storage device, the first battery is charged at a rate of 0.2C or less, and the third battery is charged at a rate exceeding 0.2C.

6. The control method according to claim 1, wherein: The power storage device includes a first battery which is a lithium metal battery, and a second battery and a third battery which are secondary batteries other than lithium metal batteries. The second battery has a higher capacity density than the third battery. The third battery has a higher output density than the second battery. When charging the power storage device, the charging rate of the first battery is 0.2C or less, the charging rate of the second battery is a rate exceeding 0.2C, and the charging rate of the third battery is higher than the charging rate of the second battery. During discharge from the power storage device, electric power is supplied from the second battery to the first battery.

7. The control method according to claim 5 or 6, wherein: The power storage device is mounted on an electric vehicle and supplies regenerative electric power to the third battery.

8. An electric storage device, wherein: The power storage device includes a plurality of battery blocks, wherein the plurality of battery blocks include an LMB block composed of a plurality of lithium metal battery cells. Each battery block is configured to be attachable and detachable.

9. The power storage device according to claim 8, wherein The power storage device includes a plurality of the LMB blocks.

10. The power storage device according to claim 8, wherein The power storage device includes a second battery block composed of secondary battery cells other than lithium metal.

11. The power storage device according to claim 10, wherein The LMB block and the second battery block are configured to be electrically connectable.

Images