JP5521989B2 - Battery system, vehicle equipped with battery system, and method for heating secondary battery - Google Patents

Description

  The present invention relates to a battery system including a secondary battery, charging means for charging the secondary battery, and charging control means for controlling charging of the secondary battery by the charging means. The present invention also relates to a vehicle equipped with the battery system. The present invention also relates to a method for heating the secondary battery.

  It is known that the output characteristics of a secondary battery such as a lithium ion secondary battery greatly deteriorates under a low temperature environment such as −30 to −10 ° C., for example. For this reason, a vehicle equipped with a battery system such as an electric vehicle or a plug-in hybrid vehicle equipped with a secondary battery may not be able to exhibit sufficient running performance under a low temperature environment in winter, particularly at the start or immediately after that. .

  For example, Patent Documents 1 to 3 listed below propose to separately provide a heating device or the like outside or inside the secondary battery and heat the secondary battery using the heating device or the like. Specifically, in Patent Document 1, a secondary battery temperature adjusting device including a ventilation fan that ventilates air to the secondary battery, an air heating means that warms the air, and the like is provided outside the secondary battery, It is disclosed that when the temperature of the secondary battery is low, the air is heated by the air heating means and the secondary battery is heated by this air (refer to the claims of Patent Document 1). .

In Patent Document 2, a substance that can be kept in a supercooled state that maintains a liquid state even when the temperature is below the freezing point is arranged around the secondary battery, and this substance undergoes a phase transition from a supercooled liquid to a solid. It is disclosed that the secondary battery is heated by using the latent heat of solidification.
In Patent Document 3, a container containing a substance that can be supercooled is placed inside a secondary battery, and the solidification latent heat when this substance undergoes a phase transition from a supercooled liquid to a solid is utilized. It is disclosed that the secondary battery is heated from the inside of the secondary battery.

  On the other hand, secondary batteries in which a redox shuttle agent is added to an electrolytic solution are also known (see Patent Documents 4 to 6). In these, the redox shuttle agent is added for the purpose of preventing overcharge. That is, an oxidation-reduction reaction is caused in the redox shuttle agent at the time of overcharge, and the battery energy input in the overcharge state is chemically consumed and converted into heat energy. Since this heat is released to the outside of the battery, overcharge of the secondary battery can be prevented.

JP 2007-323810 A JP 2005-141929 A JP 2008-198390 A JP 2000-277147 A Japanese Patent Laid-Open No. 9-17447 JP 2000-156243 A

However, as in Patent Documents 1 and 2, if a heating device or the like is separately provided outside the secondary battery, a part of the thermal energy for heating the secondary battery is part of the equipment outside the battery or the exterior material of the battery. Therefore, the battery heating efficiency is poor. In addition, since a heating device or the like is separately provided, the battery system is increased in size and costs are increased. Further, as in Patent Document 3, even when a heating device or the like is separately provided inside the secondary battery, the secondary battery itself and the battery system increase in size and increase the cost.
In addition, the secondary battery which added the redox shuttle agent to the electrolyte solution of patent documents 4-6 is not used for the battery heating at the time of low temperature.

  This invention is made | formed in view of this present condition, Comprising: It aims at providing the battery system vehicle which mounts this battery system and the battery system which can heat a secondary battery easily and efficiently. Moreover, it aims at providing the heating method of a secondary battery which can heat a secondary battery easily and efficiently.

  In one embodiment of the present invention for solving the above-described problems, a secondary battery including an electrolytic solution to which a redox shuttle agent is added, a charging unit that charges the secondary battery, and charging of the secondary battery by the charging unit Charge control means for controlling the battery, wherein the charge control means uses the charging means to change the battery voltage Va of the secondary battery to a normal use upper limit voltage Vb that is a battery voltage at full charge. And a value equal to or higher than the oxidation-reduction voltage Vc (where Vc> Vb), which is a battery voltage at which the redox shuttle agent causes an oxidation-reduction reaction, causes heat generation associated with the oxidation-reduction reaction. A battery system having direct heating means for directly heating the secondary battery.

  The charging control means of this battery system maintains the battery voltage Va of the secondary battery at a value exceeding the normal use upper limit voltage Vb and not less than the oxidation-reduction voltage Vc (Va ≧ Vc> Vb). There is a direct heating means for directly generating heat in the redox shuttle agent due to the oxidation-reduction reaction, and thus directly heating the electrolytic solution and thus the secondary battery. For this reason, a secondary battery can be heated easily and efficiently.

Note that the “redox shuttle agent” is a substance that can be added to the electrolyte, and at an oxidation-reduction voltage Vc exceeding the normal use upper limit voltage Vb, an oxidation reaction occurs at the positive electrode and a reduction reaction occurs at the negative electrode, resulting in an overcharged state It is a substance having the characteristic that the electric energy input to the secondary battery can be converted into thermal energy. As the “redox shuttle agent”, only one kind of substance can be used, or a plurality of kinds of substances can be mixed and used.
As the “redox shuttle agent”, for example, an aromatic compound, a radical compound, a heterocyclic complex, a metallocene complex, a Ce compound and the like having the above-described properties can be used. A redox shuttle agent composed of an aromatic compound, a radical compound, a metallocene complex, and a Ce compound can be used for a secondary battery having a normal use upper limit voltage Vb of about 4.0 to 4.5 V because of its redox voltage Vc. It is particularly preferable to use the redox shuttle agent composed of a ring complex for a secondary battery having a normal use upper limit voltage Vb of about 3.0V.

  Examples of the redox shuttle agent comprising an aromatic compound include 1,4-dimethoxy-2-fluorobenzene, 1,3-dimethoxy-5-chlorobenzene, 3,5-dimethoxy-1-fluorobenzene, and 1,2-dimethoxy. Examples include -4-fluorobenzene 1,2-dimethoxy-4-bromobenzene, 1,3-dimethoxy-4-bromobenzene, 2,5-dimethoxy-1-bromobenzene, and the like.

  Examples of the redox shuttle agent composed of a radical compound include tris (4-fluorophenyl) amine, tris (4-trifluoromethylphenyl) amine, tris (2,4,6-trifluorophenyl) amine, tris ( 4-methyl-2,3,5,6-tetrafluorophenyl) amine, tris (2,3,5,6-tetrafluorophenyl) amine, tris (2,3,4,5,6-pentafluorophenyl) Amines, tris (4-trifluoromethyl-2,3,5,6-tetrafluorophenyl) amine, tris (2,6-difluoro-4-bromophenyl) amine, tris (2,4,6-tribromophenyl) ) Triphenylamine compounds such as amine and tris (2,4,6-trichlorophenyl) amine.

  In addition, as a redox shuttle agent comprising a heterocyclic complex, TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy, free radical), 4-hydroxy-TEMPO, 4-amino-TEMPO, 4-cyano- TEMPO, 4-carboxy-TEMPO, 4- (2-bromoacetamide) -TEMPO, 4- (2-iodoacetamide) -TEMPO, 3-hydroxy-TEMPO, 3-amino-TEMPO, 3-cyano-TEMPO, 3- (2 N-oxyl compounds such as -bromoacetamide) -TEMPO, 3- (2-iodoacetamide) -TEMPO, proxyl, β-hydroxy-proxyl, β- (2-bromoacetamide) -proxyl, β- (2-iodoacetamide) -proxyl Is mentioned.

Moreover, as a redox shuttle agent consisting of a metallocene complex, Fe (5-Cl-1,10-phenanthroline) ₃ X ₂ , Ru (phenanthroline) ₃ X ₂ (wherein “X” in the formula represents an anionic molecule) ) And the like.
Examples of the redox shuttle agent made of Ce compound include cerium salts such as Ce (NH ₄ ) ₂ (NO ₃ ) ₅ .

  Furthermore, in the battery system described above, the battery system further includes a temperature detection unit that detects a battery temperature Ta of the secondary battery, and the charge control unit is configured such that when the battery temperature Ta is lower than a first predetermined temperature Tb, The battery system may further include a temperature management unit that causes the direct heating unit to heat the secondary battery until the battery temperature Ta reaches a second predetermined temperature Tc (where Tc ≧ Tb).

  In this battery system, when the battery temperature Ta of the secondary battery becomes lower than the first predetermined temperature Tb, the battery temperature Ta of the secondary battery is set to the second predetermined temperature Tc by the temperature detection means and the temperature management means. The temperature can be raised automatically.

  Furthermore, the battery system further includes a driven device that is driven using electric energy stored in the secondary battery, and the charge control means is configured such that the battery temperature Ta is equal to the first predetermined temperature Tb. A timing adjustment for adjusting the timing of starting the heating of the secondary battery by the direct heating means based on the scheduled driving start time Ha for starting the driving of the driven device and the battery temperature Ta, The battery system may further include means.

This battery system further includes a driven device, and the charging control unit further includes a timing adjustment unit, so that the timing for starting the heating of the secondary battery can be appropriately adjusted based on the scheduled drive start time Ha and the battery temperature Ta. .
As the “heating start timing”, for example, other than the timing at which the battery temperature Ta at the drive start scheduled time Ha is exactly the second predetermined temperature Tc by heating by the direct heating means (for example, 45 minutes before the drive start scheduled time Ha) A timing when the battery temperature Ta becomes the second predetermined temperature Tc slightly before the scheduled drive start time Ha (for example, 5 minutes before) is given. As described above, if the battery temperature Ta is set to the second predetermined temperature Tc at or slightly before the scheduled drive start time Ha, the temperature of the secondary battery is increased to a period when it is not necessary to warm the secondary battery. Since it is not necessary to let it go, useless energy consumption can be suppressed.

  In addition, it is preferable to include a heat retaining unit that keeps the battery temperature Ta at the second predetermined temperature Tc until the driven device actually starts driving after the scheduled driving start time Ha.

  Furthermore, in the battery system according to any one of the above, the charge control unit includes a pattern in which the secondary battery is fully charged immediately before the secondary battery is heated by the direct heating unit. The battery system may further include a full charging unit immediately before charging the battery.

  Some secondary batteries, such as lithium ion secondary batteries, tend to deteriorate when left in a fully charged state. In contrast, in this battery system, the secondary battery can be charged by the immediately preceding full charging means so that the secondary battery is fully charged immediately before heating the secondary battery. Accordingly, it is possible to suppress the deterioration of the secondary battery due to the long period of the fully charged state.

  Another aspect is a battery system-equipped vehicle equipped with any of the battery systems described above.

Since the battery system described above can easily and efficiently heat the secondary battery, it is possible to improve the power consumption of a vehicle equipped with the battery system.
Examples of the “battery system-equipped vehicle” include an electric vehicle, a plug-in hybrid vehicle, a hybrid railway vehicle, a forklift, an electric wheelchair, an electrically assisted bicycle, and an electric scooter.

  In this battery system-equipped vehicle, a motor that drives and runs the battery system-equipped vehicle corresponds to the aforementioned driven device. Further, corresponding to the above-mentioned charging means is an external power supply charging device for charging the secondary battery with electric energy from an external power supply outside the vehicle equipped with the battery system.

  Further, another aspect is a method of heating a secondary battery having an electrolyte solution to which a redox shuttle agent is added, wherein the battery voltage Va of the secondary battery is a battery voltage at full charge. By maintaining a value that exceeds a certain normal use upper limit voltage Vb and at least a redox voltage Vc (where Vc> Vb), which is a battery voltage at which the redox shuttle agent undergoes a redox reaction, The secondary battery heating method includes a direct heating step in which the secondary battery is directly heated by causing the accompanying heat generation.

  In this secondary battery heating method, the battery voltage Va of the secondary battery exceeds the normal use upper limit voltage Vb and is maintained at a value equal to or higher than the oxidation-reduction voltage Vc (Va ≧ Vc> Vb). The heat generated by the oxidation-reduction reaction is caused to heat the electrolytic solution and thus the secondary battery directly. For this reason, a secondary battery can be heated easily and efficiently.

  Furthermore, in the heating method of the secondary battery, the battery temperature Ta when detecting the battery temperature Ta of the secondary battery, and when the battery temperature Ta is lower than the first predetermined temperature Tb. It is preferable that the secondary battery heating method further includes a temperature management step of heating the secondary battery in the direct heating step until the temperature reaches a second predetermined temperature Tc (where Tc ≧ Tb).

  In this secondary battery heating method, the battery temperature Ta of the secondary battery is detected, and when the battery temperature Ta is lower than the first predetermined temperature Tb, the battery temperature Ta becomes the second predetermined temperature Tc. The next battery is heated. Therefore, when the battery temperature Ta becomes lower than the first predetermined temperature Tb, the battery temperature Ta can be automatically raised to the second predetermined temperature Tc.

  Furthermore, in the heating method for the secondary battery described above, when the battery temperature Ta is lower than the first predetermined temperature Tb, the driven device is driven using the electrical energy stored in the secondary battery. The secondary battery heating method further comprising a timing adjustment step of adjusting the timing of starting the heating of the secondary battery by the direct heating step based on the scheduled drive start time Ha for starting the driving of the battery and the battery temperature Ta And good.

  In this secondary battery heating method, the timing of the secondary battery heating start can be appropriately adjusted by the timing adjustment step based on the scheduled drive start time Ha and the battery temperature Ta.

  Furthermore, in the method for heating a secondary battery according to any one of the above, a full charge step immediately before charging the secondary battery in a pattern in which the secondary battery is fully charged immediately before performing the direct heating step. It is good to set it as the heating method of the secondary battery further equipped with these.

  Some secondary batteries, such as lithium ion secondary batteries, tend to deteriorate when left in a fully charged state. On the other hand, in this heating method of the secondary battery, the secondary battery is charged so that the secondary battery is fully charged immediately before performing the direct heating step. Degradation of the secondary battery can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram illustrating an outline of a plug-in hybrid vehicle equipped with a battery system according to a first embodiment. 1 is a longitudinal sectional view of a lithium ion secondary battery according to Embodiment 1. FIG. FIG. 3 is a perspective view showing a wound electrode body according to the first embodiment. 6 is a graph showing a relationship between an input electric quantity and a battery voltage Va for Example 1 and Comparative Example 1. It is a graph which shows the relationship between heating time and battery temperature Ta about Example 2 and Comparative Example 2. FIG. It is a graph which shows a battery output and battery temperature Ta about Example 3 and Comparative Examples 3-5. 4 is a flowchart illustrating charge control by the battery system according to the first embodiment. 4 is a flowchart illustrating charging / heating processing in the charging control by the battery system according to the first embodiment. 10 is a flowchart illustrating charge control by the battery system according to the second embodiment. 6 is a flowchart illustrating heat treatment in charge control by the battery system according to the second embodiment.

(Embodiment 1)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a plug-in hybrid vehicle (battery system-equipped vehicle) 300 equipped with the battery system 200 according to the first embodiment. The plug-in hybrid vehicle 300 includes an engine 320, a front motor 330 and a rear motor 340 (driven device), and a battery system 200 mounted on a vehicle body 310.

  Among these, the battery system 200 includes an assembled battery 210, an ECU 220, an inverter 230, an AC-DC converter (charging means) 240, a cable 250 for connecting them, and a cable with a plug used for connection to an external power source XV. 260. Among these, the assembled battery 210 includes a plurality of lithium ion secondary batteries (secondary batteries) 100, 100,... And a temperature sensor (temperature detection means) 190 that detects the battery temperature Ta of the lithium ion secondary battery 100. Have.

  In the first embodiment, the battery system 200 can charge the assembled battery 210 (lithium ion secondary battery 100) from the external power source XV, and the electric energy stored in the assembled battery 210 (lithium ion secondary battery 100). Can be used to drive the front motor 330 and the rear motor 340. The ECU 220 corresponds to “charging control means” that controls charging of the lithium ion secondary battery 100 by the AC-DC converter 240.

Next, the lithium ion secondary battery 100 constituting the assembled battery 210 will be described. The lithium ion secondary battery 100 has a battery capacity estimated from the theoretical capacity of the positive electrode plate 121 of 14 Ah, and a normal use upper limit voltage Vb that is a battery voltage at full charge (SOC 100%) is 4.1 V.
The lithium ion secondary battery 100 is a rectangular battery, and includes a rectangular battery case 110, a wound electrode body 120 accommodated in the battery case 110, and a positive electrode terminal member 150 supported by the battery case 110. And the negative electrode terminal member 160 and the like (see FIGS. 2 and 3). In addition, an electrolytic solution 117 is injected into the battery case 110.

  Among these, the electrolyte solution 117 is a solution to which a redox shuttle agent is added. Specifically, ethylene carbonate and ethylmethyl carbonate are mixed at a ratio (volume ratio) of 1: 1, and LiPF6 is dissolved to 1 M in an electrolytic solution, and 1,2-di ( Methoxy) -4- (fluorinated) benzene is dissolved so as to be 0.01M. The redox shuttle agent has a redox voltage Vc of 4.2V.

Further, the wound electrode body 120 is obtained by winding a belt-like positive electrode plate 121 and a belt-like negative electrode plate 131 on each other with a breathable belt-like separator 141 around the axis AX, and compressing them flatly. It is.
Among these, the positive electrode plate 121 has a current collector plate 122 made of a strip-shaped aluminum foil as a core material. On both main surfaces of the current collector plate 122, a positive electrode active material layer is provided in a band shape in the longitudinal direction on a part extending in the longitudinal direction and extending in the longitudinal direction. This positive electrode active material layer is comprised from the positive electrode active material, the conductive support agent, and the binder. In the first embodiment, LiFePO _{4 is} used as the positive electrode active material, acetylene black (AB) is used as the conductive auxiliary agent, and polyvinylidene fluoride (PVDF) is used as the binder.

Moreover, the negative electrode plate 131 has the current collection plate 132 which consists of strip | belt-shaped copper foil as a core material. On both main surfaces of the current collector plate 132, a negative electrode active material layer is provided in a strip shape in the longitudinal direction on a part extending in the longitudinal direction and extending in the longitudinal direction. The negative electrode active material layer is composed of a negative electrode active material, a binder, and a thickener. In the first embodiment, a natural graphite-based carbon material is used as the negative electrode active material, a styrene-butadiene copolymer (SBR) is used as the binder, and carboxymethyl cellulose (CMC) is used as the thickener.
The separator 141 is a porous film made of resin, specifically, polypropylene (PP) and polyethylene (PE), and has a strip shape.

  Here, various test results performed on the lithium ion secondary battery 100 will be described. First, as Example 1, the lithium ion secondary battery 100 was charged, and the relationship between the input electric quantity and the battery voltage (inter-terminal voltage) Va was examined. In addition, as Comparative Example 1, a lithium ion secondary battery is prepared in the same manner as in Embodiment 1 except that no redox shuttle agent is added to the electrolytic solution. The relationship with Va was investigated. The result is shown in FIG.

From the graph of FIG. 4, when the lithium ion secondary battery according to Comparative Example 1 is charged and exceeds the fully charged battery voltage Va = Vb (4.1 V), the battery voltage is increased with respect to the increase in the amount of input electricity. Va rises rapidly.
On the other hand, in the lithium ion secondary battery 100 according to the first embodiment, the input electric quantity and the battery voltage Va exceed the fully charged battery voltage Va = Vb and further reaches the battery voltage Va = Vc (4.2 V). This relationship is the same as that of the lithium ion secondary battery according to Comparative Example 1. However, when the battery voltage Va = Vc is reached, the battery voltage Va no longer increases with the increase of the input electric quantity, and the battery voltage Va maintains this value Vc. This voltage value Vc is an oxidation-reduction voltage at which an oxidation-reduction reaction occurs in the redox shuttle agent in the electrolytic solution 117. The redox shuttle agent converts electric energy input in an overcharged state into heat energy by causing an oxidation reaction at the positive electrode plate 121 and a reduction reaction at the negative electrode plate 131 at the oxidation-reduction voltage Vc. This heat is released outside the battery through the battery case 110 and the like.

Next, as Example 2, the lithium ion secondary battery 100 according to Embodiment 1 was directly heated, and the relationship between the heating time and the battery temperature Ta was examined. Specifically, the lithium ion secondary battery 100 is fully charged in a constant temperature bath at 25 ° C. by a constant current-constant voltage method (upper limit voltage 4.1 V, current value (1/80) C is a charge termination condition). Charged until Thereafter, the fully charged lithium ion secondary battery 100 was placed in a constant temperature bath at -20 ° C.
Thereafter, the lithium ion secondary battery 100 was energized with a constant current of 1 C to generate heat associated with the redox shuttle agent oxidation-reduction reaction, and the lithium ion secondary battery 100 was directly heated from the inside. In Example 2, it took 20 minutes for the battery temperature Ta to change from -20 ° C to 25 ° C.

On the other hand, as Comparative Example 2, 30 ml of liquid (specifically, water) and a heater (180 W nichrome wire) capable of heating the container are accommodated in the container, and the lithium ion 2 according to Comparative Example 1 is contained in this liquid. What dipped the next battery was prepared. The lithium ion secondary battery 100 was fully charged in advance as described above at an ambient temperature of 25 ° C., and the temperature of the liquid in the container and the lithium ion secondary battery 100 was −20 ° C.
Thereafter, the lithium ion secondary battery 100 was indirectly heated by energizing the heater so that the power consumption was the same as that of the lithium ion secondary battery 100 according to Example 1 and heating the liquid. In Comparative Example 2, it took 35 minutes for the battery temperature Ta to change from -20 ° C to 25 ° C. The result is shown in FIG.

As can be seen from the graph of FIG. 5, in both the lithium ion secondary battery 100 according to Example 2 and the lithium ion secondary battery according to Comparative Example 2, the battery temperature Ta increases linearly as the heating time elapses. . However, the speed of the rise in Example 2 is faster than that in Comparative Example 2. That is, the lithium ion secondary battery 100 according to Example 2 took 20 minutes to reach 25 ° C., whereas the lithium ion secondary battery according to Comparative Example 2 reached 25 ° C. It took 35 minutes.
Therefore, rather than separately installing a heating device outside the lithium ion secondary battery and thereby heating the lithium ion secondary battery (Comparative Example 2), the lithium ion secondary battery 100 is directly heated from the inside. It can be seen that (Example 2) can be heated more efficiently.

Next, as Example 3, as in Example 2, the lithium ion secondary battery 100 according to Embodiment 1 was fully charged, and was heated to −20 ° C., and then heated for 20 minutes. The output was measured. The battery output was measured when 1 minute passed after the heating was completed.
The battery output was calculated as follows. That is, the lithium ion secondary battery 100 was discharged at 1 C for 30 seconds by a constant current method. The battery voltage (open voltage) before discharge was V0, the battery voltage 20 seconds after the start of discharge was V1, and (V1-V0) / I was the internal resistance R of the lithium ion secondary battery 100. Further, (V2 × V2) / R is obtained from the lower limit voltage V2 of the system (V2 = 3.0 V in this embodiment), and further divided by the weight of the positive electrode active material, and this value is obtained as the battery output (W / g). It was.

In addition, as Comparative Example 3, a lithium ion secondary battery according to Comparative Example 1 described above (a redox shuttle agent is not included in the electrolytic solution) is prepared, fully charged, and set to −20 ° C., and then as in Example 3. The battery temperature Ta was measured “without energization” for proper heating, and the battery output was further measured.
In addition, as Comparative Example 4, a lithium ion secondary battery according to Comparative Example 1 described above (a redox shuttle agent is not included in the electrolytic solution) is prepared, fully charged, and set to −20 ° C. The battery temperature Ta and the battery output were measured in the same manner as “energized”.
Further, as Comparative Example 5, the lithium ion secondary battery 100 (including the redox shuttle agent in the electrolytic solution) according to Example 3 described above was prepared, fully charged, and set to −20 ° C., and then as in Example 3. The battery temperature Ta and the battery output were measured “without energization” for proper heating.
The result is shown in FIG. The battery output is based on Comparative Example 3 (reference value “1”), and Examples 3, Comparative Examples 4 and 5 are shown as relative values with respect to Comparative Example 3.

  From FIG. 6, in Comparative Examples 3 and 5, the battery temperature Ta did not change from the environmental temperature (−20 ° C.) after the above test, and the battery output was the reference value “1”. In Comparative Example 4, the battery temperature Ta slightly increased from the environmental temperature (−20 ° C.) (battery temperature Ta = −15 ° C.), and the battery output also increased slightly compared to Comparative Example 3 (battery output). = 1.3). In contrast, in Example 3, the battery temperature Ta significantly increased from the environmental temperature (−20 ° C.) (battery temperature Ta = 25 ° C.), and the battery output also increased significantly (battery output = 5.0). did.

  From this, unless energization for heating is performed separately after full charge (Comparative Examples 3 and 5), regardless of whether or not a redox shuttle agent is added to the electrolyte, there is no change in the battery temperature Ta, Therefore, it can be seen that the battery output does not increase. In addition, even when energization (overcharge) is performed for heating after full charge, the battery temperature Ta is slightly increased in the lithium ion secondary battery in which the redox shuttle agent is not added to the electrolyte (Comparative Example 4). It can also be seen that the battery output increases only slightly. On the other hand, if the lithium-ion secondary battery 100 in which the redox shuttle agent is added to the electrolytic solution is energized for heating after full charge (Example 3), the battery temperature Ta increases significantly, and the battery output is increased. It can also be seen that it can be significantly increased.

  Next, charging control of the assembled battery 210 (lithium ion secondary battery 100) by the battery system 200 in the plug-in hybrid vehicle 300 described above will be described. In this plug-in hybrid vehicle 300, for example, the output of the assembled battery 210 (lithium ion secondary battery 100) is greatly reduced under a low temperature environment of −30 to −10 ° C., for example, there is a possibility that sufficient running performance cannot be exhibited. . In order to solve this problem, in the plug-in hybrid vehicle 300, the battery system 200 performs the charge control shown in the flowcharts of FIGS. 7 and 8 so that the lithium ion secondary battery 100 (the assembled battery 210) is in a low temperature state. Heat.

The user connects the plug-in hybrid vehicle 300 to the external power source XV, and inputs a scheduled operation start time (estimated drive start time) Ha at which the operation of the plug-in hybrid vehicle 300 is started. This scheduled operation start time Ha is stored in the ECU 220.
First, in step S1, it is determined whether or not a scheduled operation start time (estimated drive start time) Ha is set. If YES, that is, if the scheduled operation start time Ha is set, the process proceeds to step S2. On the other hand, if NO, that is, if the scheduled operation start time Ha is not set, the process proceeds to the charging process in step S10.

In step S2, the state of charge (SOC) of the lithium ion secondary battery 100 is detected. In the first embodiment, the battery voltage Va of the lithium ion secondary battery 100 is measured, and the state of charge is detected from this value.
Next, it progresses to step S3 and the battery temperature Ta of the lithium ion secondary battery 100 is measured with the temperature sensor 190. FIG. This step S3 corresponds to the aforementioned “temperature detection step”.

  Next, in step S4, it is determined whether or not the battery temperature Ta obtained in step S3 is lower than a first predetermined temperature Tb (5 ° C. in the first embodiment). If YES, that is, if the battery temperature Ta is lower than the first predetermined temperature Tb, the process proceeds to step S5. This is a case where the lithium ion secondary battery 100 is in a low temperature state and requires heating. On the other hand, if NO, that is, if the battery temperature Ta is equal to or higher than the first predetermined temperature Tb, the process proceeds to step S8. This is a case where the lithium ion secondary battery 100 does not need to be heated.

  In step S5, the estimated operation start time Ha set by the user, the state of charge obtained in step S2, and the temperature difference ΔT between the second predetermined temperature Tc described later and the battery temperature Ta obtained in step S3 are set. Based on this, a charging / heating start time Hb, which is a time for starting a charging / heating process described later, is determined. Specifically, the charging time Ja required to fully charge the lithium ion secondary battery 100 from the charged state is obtained, and the lithium ion secondary battery 100 is moved from the temperature difference ΔT to the second predetermined temperature Tc. The heating time Jb necessary for heating is obtained. Then, the charging time Ja from the scheduled operation start time Ha so that the lithium ion secondary battery 100 is in a warmed state at the scheduled operation start time Ha (so that the battery temperature Ta becomes the second predetermined temperature Tc). And the heating time Jb is subtracted to obtain the charging / heating start time Hb.

  Next, the process proceeds to step S6, and it is determined whether or not the current time is the charging / heating start time Hb. If YES, that is, if the charging / heating start time Hb is reached, the process proceeds to step S7 to perform the charging / heating process. On the other hand, if NO, that is, if charging / heating start time Hb has not yet been reached, the system waits until charging / heating start time Hb. Steps S5 and S6 correspond to the “timing adjustment step” described above, and ECU 220 executing steps S5 and S6 corresponds to the “timing adjustment unit” described above.

Next, the process proceeds to step S7, and the charging / heating processing subroutine shown in FIG. 8 is performed. In this subroutine, the lithium ion secondary battery 100 is also heated following the charging of the lithium ion secondary battery 100. This is because the battery temperature Ta is too low (battery temperature Ta <first predetermined temperature Tb).
First, in step S71, charging of the lithium ion secondary battery 100 is started. In the first embodiment, charging is performed at 0.5 to 2 C (0.5 C in the first embodiment) by a constant current method.

Next, it progresses to step S72 and the battery voltage Va of the lithium ion secondary battery 100 is measured. Thereafter, in step S73, it is determined whether or not the battery voltage Va obtained in step S72 is equal to or higher than the oxidation-reduction voltage Vc. If YES, that is, if the battery voltage Va is greater than or equal to the redox voltage Vc, the process proceeds to step S74. On the other hand, if NO, that is, if the battery voltage Va is smaller than the oxidation-reduction voltage Vc, the process returns to step S72 and charging is continued.
If it progresses to step S74, charge of the lithium ion secondary battery 100 will be complete | finished. At this time, the lithium ion secondary battery 100 has passed the fully charged state and is slightly overcharged. Steps S71 to S74 correspond to the aforementioned “immediate full charge step”, and the ECU 220 executing these steps S71 to S74 corresponds to the “immediate full charge unit” described above.

  Next, heating of the lithium ion secondary battery 100 is started in step S75. That is, the battery voltage Va exceeds the normal use upper limit voltage Vb at the time of full charge and is maintained at a value equal to or higher than the redox shuttle agent's oxidation-reduction voltage Vc, thereby causing an oxidation-reduction reaction of the redox shuttle agent. Heat generation is caused to directly heat the electrolytic solution 117, and thus the lithium ion secondary battery 100. Specifically, the lithium ion secondary battery 100 is directly heated from the inside by energizing 0.1 to 0.2 C (0.1 C in the first embodiment) by a constant current method. This step S75 corresponds to the above-mentioned “direct heating step”, and the ECU 220 executing this step S75 corresponds to the above-mentioned “direct heating means”.

Next, it progresses to step S76 and battery temperature Ta is measured. This step S76 also corresponds to the above-described temperature detection step.
Thereafter, in step S77, it is determined whether or not the battery temperature Ta obtained in step S76 is equal to or higher than a second predetermined temperature Tc (where Tc ≧ Tb, 5 ° C. in the first embodiment). If YES, that is, if the battery temperature Ta is equal to or higher than the second predetermined temperature Tc, the process proceeds to step S78. On the other hand, if NO, that is, if the battery temperature Ta is lower than the second predetermined temperature Tc, the process proceeds to step S79.

In step S78, the energization of the lithium ion secondary battery 100 and the heating thereby are terminated. The above-described step S4, step S77, and step S78 correspond to the “temperature management step”. The ECU 220 executing steps S3, S4, S76 to S78 corresponds to the above-mentioned “temperature management means”.
Thereafter, the process returns to the main routine of FIG. At this end time, the time is exactly the scheduled operation start time Ha or a time before and after it, and the lithium ion secondary battery 100 is fully charged and raised to the second predetermined temperature Tc. Yes. Therefore, the output of the assembled battery 210 (lithium ion secondary battery 100) can be sufficiently obtained from the scheduled operation start time Ha when the user starts the operation of the plug-in hybrid vehicle 300, and sufficient running performance can be exhibited.

  On the other hand, when proceeding to step S79, the battery voltage Va is measured. Thereafter, in step S80, it is determined whether or not the battery voltage Va obtained in step S79 is equal to or higher than the heating upper limit voltage Vd that is the upper limit voltage during battery heating. If YES, that is, if the battery voltage Va is equal to or higher than the heating upper limit voltage Vd, the process proceeds to step S78 and the heating is terminated. Thereby, it can prevent that the battery voltage Va is heated in the abnormally raised state. Thereafter, the process returns to the main routine of FIG. On the other hand, if NO, that is, if the battery voltage Va is smaller than the heating upper limit voltage Vd, the process returns to step S76 and the heating of the lithium ion secondary battery 100 is continued.

  Next, if NO is determined in step S4 of the main routine of FIG. 7 and the process proceeds to step S8, based on the scheduled operation start time Ha set by the user and the state of charge obtained in step S2. Then, a charging start time Hc that is a time for starting a charging process described later is determined. Specifically, the above-described charging time Ja necessary for charging the lithium ion secondary battery 100 to a fully charged state is obtained from the charged state, and the lithium ion secondary battery 100 becomes fully charged at the scheduled operation start time Ha. As described above, the charging time Ja is subtracted from the scheduled operation start time Ha to obtain the charging start time Hc.

  Next, it progresses to step S9 and it is judged whether the present time became charge start time Hc. If YES, that is, if the charging start time Hc is reached, the process proceeds to step S10, where the charging process is performed. On the other hand, if NO, that is, if the charging start time Hc has not yet been reached, the system waits until the charging start time Hc is reached.

  In step S10, only the lithium ion secondary battery 100 is charged and not heated. This is because the battery temperature Ta is not so low as to require heating (battery temperature Ta ≧ first predetermined temperature Tb). Specifically, the lithium ion secondary battery 100 is charged until it is fully charged by a constant current-constant voltage method (upper limit voltage 4.1 V, current value (1/80) C is a charge termination condition). When this charging is completed, the time is the scheduled operation start time Ha.

  As described above, in the battery system 200 according to the first embodiment, the battery voltage Va of the lithium ion secondary battery 100 exceeds the normal use upper limit voltage Vb and is oxidized by the AC-DC converter 240 controlled by the ECU 220. Energization is performed to maintain a value equal to or higher than the reduction voltage Vc (Va ≧ Vc> Vb). As a result, heat is generated due to the redox shuttle agent redox reaction, and the lithium ion secondary battery 100 is directly heated from the inside. For this reason, there is no need to separately provide a heating device or the like for heating the battery outside or inside the battery as described in the prior art, so that the battery system 200 can be reduced in size and made inexpensive.

  In addition, when a heating device or the like is provided outside the battery, a part of the heat energy at the time of heating is used for raising the temperature of the battery case 110 of the lithium ion secondary battery 100 or the equipment outside the battery. ineffective. On the other hand, in the battery system 200, the lithium ion secondary battery 100 can be directly heated from the inside thereof, so that energy for heating can be reduced. Thus, in this battery system 200, the lithium ion secondary battery 100 can be heated easily and efficiently.

  Further, in this battery system 200, the battery temperature Ta of the lithium ion secondary battery 100 is detected, and when the battery temperature Ta is lower than the first predetermined temperature Tb, the battery temperature Ta becomes the second predetermined temperature Tc. The lithium ion secondary battery 100 is heated. Therefore, when the battery temperature Ta becomes lower than the first predetermined temperature Tb, the battery temperature Ta can be automatically raised to the second predetermined temperature Tc.

  Further, in this battery system 200, when the battery temperature Ta is lower than the first predetermined temperature Tb, the scheduled operation start time Ha and the battery temperature Ta become the second predetermined temperature Tc at the scheduled operation start time Ha, and Based on the battery temperature Ta, the heating start timing of the lithium ion secondary battery 100 is adjusted. Accordingly, the battery temperature Ta at the scheduled operation start time Ha can be set to the second predetermined temperature Tc or a temperature close thereto. Further, since it is not necessary to heat the lithium ion secondary battery 100 until a period during which the lithium ion secondary battery 100 does not need to be warmed, useless energy can be saved.

  Further, although the lithium ion secondary battery 100 is likely to deteriorate when left in a fully charged state, in this battery system 200, the lithium ion secondary battery 100 is fully charged immediately before the lithium ion secondary battery 100 is heated. Thus, the lithium ion secondary battery 100 can be charged. Therefore, it is possible to suppress the deterioration of the lithium ion secondary battery 100 due to the long period of the fully charged state.

  Moreover, by installing such a battery system 200, the power consumption of the plug-in hybrid vehicle 300 can be improved. Moreover, the plug-in hybrid vehicle 300 can reduce the space for mounting the battery system 200, and can reduce the vehicle cost.

(Embodiment 2)
Next, a second embodiment will be described. The battery system 202 according to the second embodiment and the plug-in hybrid vehicle 302 equipped with the battery system 202 are charged at the scheduled operation start time Ha when the lithium ion secondary battery 100 is charged to the full charge immediately after the charge control is started. This is different from the battery system 200 and the plug-in hybrid vehicle 300 according to the first embodiment that start charging based on the above.

The charge control of the second embodiment will be described with reference to the flowcharts of FIGS. When the user connects the plug-in hybrid vehicle 300 to the external power source XV and inputs the scheduled operation start time Ha, the scheduled operation start time Ha is stored in the ECU 220 as in the first embodiment.
First, in step S21, a charging process is performed. This charging process is the same as the charging procedure (step S10) of the first embodiment (see FIG. 7). When this step S21 is completed, the lithium ion secondary battery 100 is in a fully charged state.

  Next, it progresses to step S22 and it is judged whether the driving | operation scheduled start time Ha is set. If YES, that is, if the scheduled operation start time Ha is set, the process proceeds to step S23. On the other hand, if NO, that is, if the scheduled operation start time Ha is not set, this charging control is terminated.

Next, it progresses to step S23 and the battery temperature Ta is measured by the temperature sensor 190. FIG. This step S23 corresponds to the aforementioned “temperature detection step”.
Thereafter, in step S24, it is determined whether or not the battery temperature Ta obtained in step S23 is lower than a first predetermined temperature Tb (5 ° C. in the second embodiment). If YES, that is, if the battery temperature Ta is lower than the first predetermined temperature Tb, the process proceeds to step S25. This is a case where the lithium ion secondary battery 100 is in a low temperature state and requires heating. On the other hand, when the battery temperature Ta is equal to or higher than the first predetermined temperature Tb, the charging control is terminated. This is because there is no need to heat the lithium ion secondary battery 100.

  Next, when proceeding to step S25, the heat treatment start time described later is started based on the scheduled operation start time Ha and the temperature difference ΔT between the second predetermined temperature Tc described later and the battery temperature Ta obtained in step S23. The heating start time Hd is determined. Specifically, the heating time Jb required to heat the lithium ion secondary battery 100 to the second predetermined temperature Tc is obtained from the temperature difference ΔT. Then, the heating time Jb is subtracted from the scheduled operation start time Ha so that the battery temperature Ta becomes the second predetermined temperature Tc at the scheduled operation start time Ha to obtain a heating start time Hd.

  Next, it progresses to step S26 and it is judged whether the present time became the heating start time Hd. Here, if YES, that is, if the heating start time Hd is reached, the process proceeds to step S27 and a heating process is performed. On the other hand, if NO, that is, if the heating start time Hd is not yet reached, the process waits until the heating start time Hd is reached. Steps S25 and S26 correspond to the “timing adjustment step” described above, and the ECU 222 executing steps S25 and S26 corresponds to the “timing adjustment unit” described above.

When the processing proceeds to step S27, the processing proceeds to a heating processing subroutine shown in FIG.
First, in step S271, heating of the lithium ion secondary battery 100 is started. This heating is the same as the heating in the first embodiment (step S75) (see FIGS. 7 and 8). That is, the battery voltage Va exceeds the normal use upper limit voltage Vb at the time of full charge and is maintained at a value equal to or higher than the redox shuttle agent's oxidation-reduction voltage Vc, thereby causing an oxidation-reduction reaction of the redox shuttle agent. Heat generation is caused to directly heat the electrolytic solution 117, and thus the lithium ion secondary battery 100. Specifically, the lithium ion secondary battery 100 is directly heated from the inside by energizing 0.1 to 0.2 C (0.1 C in the second embodiment) by a constant current method. The step S271 corresponds to the above-described “direct heating step”, and the ECU 222 executing the step S271 corresponds to the above-mentioned “direct heating unit”.

Next, it progresses to step S272 and battery temperature Ta is measured. This step S272 also corresponds to the aforementioned “temperature detection step”.
Thereafter, in step S273, it is determined whether or not the battery temperature Ta obtained in step S272 is equal to or higher than a second predetermined temperature Tc (5 ° C. in the second embodiment). If YES, that is, if the battery temperature Ta is equal to or higher than the second predetermined temperature Tc, the process proceeds to step S274. On the other hand, if NO, that is, if the battery temperature Ta is lower than the second predetermined temperature Tc, the process proceeds to step S275.

In step S274, the energization and heating by the lithium ion secondary battery 100 are terminated. The above-described step S24, step S273, and step S274 correspond to the above-described “temperature management step”. The ECU 222 executing steps S23, S24, S272 to S274 corresponds to the above-mentioned “temperature management means”.
Thereafter, the process returns to the main routine of FIG. At this end time, as in the first embodiment, the time is exactly the scheduled operation start time Ha or a time before and after it, and the lithium ion secondary battery 100 is fully charged and the second The temperature is raised to a predetermined temperature Tc. Therefore, the output of the assembled battery 210 (lithium ion secondary battery 100) can be sufficiently obtained from the scheduled operation start time Ha when the user starts the operation of the plug-in hybrid vehicle 300, and sufficient running performance can be exhibited.

  On the other hand, in step S275, the battery voltage Va is measured. Thereafter, in step S276, it is determined whether or not the battery voltage Va obtained in step S275 is equal to or higher than the heating upper limit voltage Vd. If YES, that is, if the battery voltage Va is equal to or higher than the heating upper limit voltage Vd, the process proceeds to step S274 and the heating is terminated. Thereafter, the process returns to the main routine of FIG. On the other hand, if NO, that is, if the battery voltage Va is smaller than the heating upper limit voltage Vd, the process returns to step S272 and the heating of the battery of the lithium ion secondary battery 100 is continued.

  As described above, the battery system 202 according to the second embodiment is also oxidized by the AC-DC converter 240 controlled by the ECU 222 so that the battery voltage Va of the lithium ion secondary battery 100 exceeds the normal use upper limit voltage Vb. Energization is performed to maintain a value equal to or higher than the reduction voltage Vc (Va ≧ Vc> Vb). As a result, heat is generated due to the redox shuttle agent redox reaction, and the lithium ion secondary battery 100 is directly heated. For this reason, since it is not necessary to separately provide a heating device or the like for heating the battery outside or inside the battery, the battery system 202 can be reduced in size and made inexpensive. Moreover, since this battery system 202 can also heat the lithium ion secondary battery 100 directly from the inside, it can be heated easily and efficiently.

  In addition, when the battery temperature Ta is lower than the first predetermined temperature Tb, the battery system 202 also has the scheduled operation start time Ha and the battery temperature so that the battery temperature Ta becomes the second predetermined temperature Tc at the scheduled operation start time Ha. Based on Ta, the heating start timing of the lithium ion secondary battery 100 is adjusted. Accordingly, the battery temperature Ta at the scheduled operation start time Ha can be set to the second predetermined temperature Tc or a temperature close thereto. Further, since it is not necessary to heat the lithium ion secondary battery 100 until a period during which the lithium ion secondary battery 100 does not need to be warmed, useless energy can be saved. In addition, the same parts as those of the first embodiment have the same effects as those of the first embodiment.

In the above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to the above-described first and second embodiments, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof. Yes.
For example, in the first and second embodiments, charging and heating are performed so that the battery temperature Ta at the scheduled operation start time Ha becomes the second predetermined temperature Tc in Step S5 (Embodiment 1) or Step S25 (Embodiment 2). Although the start time Hb (Embodiment 1) or the heating start time Hd (Embodiment 2) is determined, the heating start timing can be adjusted as appropriate. For example, in step S5 or step S25, the charging / heating start time Hb or the heating start time Hd is set so that the battery temperature Ta becomes the second predetermined temperature Tc slightly before the scheduled operation start time Ha (for example, 5 minutes before). May be determined.

In the first and second embodiments, when the battery temperature Ta is heated to the second predetermined temperature Tc, the heating is finished at that time, but after that, until the user actually starts operation, Continuously or intermittently, the lithium ion secondary battery 100 may be energized and heated directly to keep the battery temperature Ta at the second predetermined temperature Tc.
Further, according to the user's instruction, the lithium ion secondary battery 100 in a fully charged state is energized for direct heating, or the lithium ion secondary battery 100 is fully charged and then directly heated. You may make it perform electricity supply for.

  In the first and second embodiments, the charging / heating start time Hb (first embodiment) or the heating start time Hd (second embodiment) is determined in step S5 (first embodiment) or step S25 (second embodiment). After that, you will not change them. However, the charging / heating start time Hb (Embodiment 1) and the heating start time Hd (Embodiment 2) may be set repeatedly in order to adapt to subsequent changes in the battery temperature Ta accompanying changes in the outside air temperature. .

  In Embodiments 1 and 2, energization for battery heating in Step S7 (Embodiment 1) or Step S27 (Embodiment 2) is performed with a constant current. However, the present invention is not limited to this. For example, in accordance with the battery temperature Ta at that time and the time until the scheduled operation start time Ha, the current value is increased in the middle so that the battery temperature Ta becomes exactly the second predetermined temperature Tc at the scheduled operation start time Ha. It may be decreased.

100 Lithium ion secondary battery (secondary battery)
117 Electrolyte 190 Temperature sensor (temperature detection means)
200 battery system 210 assembled battery 220, 222 ECU (charge / discharge control means)
240 AC-DC converter (charging means)
300,302 Plug-in hybrid automobile (vehicle with battery system)
330 Front motor (driven device)
340 Rear motor (driven device)
Ha scheduled drive start time (scheduled start time)
Ta battery temperature Tb first predetermined temperature Tc second predetermined temperature ΔT temperature difference Va battery voltage Vb normal use upper limit voltage Vc oxidation reduction voltage XV external power source

Claims (9)

A secondary battery having an electrolyte solution to which a redox shuttle agent is added;
Charging means for charging the secondary battery;
Charge control means for controlling charging of the secondary battery by the charging means, and a battery system comprising:
The charge control means includes
A redox voltage that is a battery voltage at which the battery voltage Va of the secondary battery exceeds a normal use upper limit voltage Vb that is a battery voltage at the time of full charge and a redox shuttle reaction occurs in the redox shuttle by the charging means. A battery system comprising a direct heating means for directly heating the secondary battery by causing heat generation associated with the oxidation-reduction reaction by maintaining the value at Vc or higher. The battery system according to claim 1,
A temperature detecting means for detecting a battery temperature Ta of the secondary battery;
The charge control means includes
When the battery temperature Ta is lower than the first predetermined temperature Tb, the secondary battery is heated by the direct heating means until the battery temperature Ta reaches the second predetermined temperature Tc (where Tc ≧ Tb). A battery system further comprising a temperature management means. The battery system according to claim 2,
Further comprising a driven device that is driven using electrical energy stored in the secondary battery;
The charge control means includes
When the battery temperature Ta is lower than the first predetermined temperature Tb, the secondary heating by the direct heating means based on the scheduled drive start time Ha for starting the drive of the driven device and the battery temperature Ta. A battery system further comprising timing adjusting means for adjusting a timing of starting heating of the battery. It is a battery system as described in any one of Claims 1-3,
The charge control means includes
The battery system further comprising a full charge unit immediately before charging the secondary battery in a pattern in which the secondary battery is fully charged immediately before the secondary battery is heated by the direct heating unit. A battery system-equipped vehicle equipped with the battery system according to any one of claims 1 to 4. A heating method of a secondary battery for heating a secondary battery having an electrolyte solution to which a redox shuttle agent is added,
The battery voltage Va of the secondary battery exceeds a normal use upper limit voltage Vb that is a battery voltage at the time of full charge, and a value equal to or higher than a redox voltage Vc that is a battery voltage at which an oxidation-reduction reaction occurs in the redox shuttle agent. A heating method of a secondary battery, comprising a direct heating step of heating the secondary battery directly by causing heat generation due to the oxidation-reduction reaction by maintaining. The method for heating a secondary battery according to claim 6,
A temperature detection step of detecting a battery temperature Ta of the secondary battery;
When the battery temperature Ta is lower than the first predetermined temperature Tb, the secondary battery is heated in the direct heating step until the battery temperature Ta reaches a second predetermined temperature Tc (where Tc ≧ Tb). And a temperature control step for heating the secondary battery. A method for heating a secondary battery according to claim 7,
When the battery temperature Ta is lower than the first predetermined temperature Tb, the drive start scheduled time Ha for starting the drive of the driven device driven using the electrical energy stored in the secondary battery, and A method for heating a secondary battery, further comprising a timing adjustment step of adjusting a timing of starting the heating of the secondary battery in the direct heating step based on a battery temperature Ta. A method for heating a secondary battery according to any one of claims 6 to 8,
A method for heating a secondary battery, further comprising a full charge step immediately before charging the secondary battery in a pattern in which the secondary battery is fully charged immediately before performing the direct heating step.

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