JP2010198759A - Battery system and vehicle - Google Patents

Abstract

A battery system capable of effectively recovering a battery capacity reduced due to lithium deposition and an automobile are provided.
A battery system includes a lithium ion secondary battery and a temperature control device that controls the temperature of the lithium ion secondary battery. The temperature control device 20 performs control to keep the temperature of the lithium ion secondary battery 100 within a range of 35 ° C. or more and 55 ° C. or less.
[Selection] Figure 2

Description

  The present invention relates to a battery system including a lithium ion secondary battery and an automobile including the battery system.

  Lithium ion secondary batteries are attracting attention as power sources for portable devices and as power sources for electric vehicles and hybrid vehicles. By the way, in a lithium ion secondary battery, for example, when charging (particularly, high rate charging) is performed in a low temperature environment, Li may be deposited on the negative electrode surface. Since most of Li deposited on the negative electrode surface cannot contribute to the charge / discharge reaction of the battery, there is a problem that the battery capacity decreases when such charging is repeated. In recent years, methods for solving this problem have been proposed (see, for example, Patent Document 1).

JP 2001-52760 A

  Patent Document 1 proposes a charging method in which a charging voltage is set according to the battery temperature at the start of charging, and constant voltage charging is performed with this charging voltage. Specifically, the charging voltage is set lower as the battery temperature at the start of charging is lower. As a result, when charging in a low temperature environment, it is possible to prevent the negative electrode potential from decreasing due to a decrease in battery temperature, so that the negative electrode potential is unlikely to decrease to the lithium deposition potential and Li deposition is prevented. Yes.

However, in the method of Patent Document 1, once Li is deposited on the negative electrode surface and the battery capacity is reduced, the reduced battery capacity cannot be recovered.
This invention is made | formed in view of this present condition, Comprising: It aims at providing the battery system which can recover the battery capacity reduced by precipitation of lithium effectively, and a motor vehicle.

  The solution is a battery system comprising a lithium ion secondary battery and a temperature control device for controlling the temperature of the lithium ion secondary battery, wherein the temperature control device is a temperature of the lithium ion secondary battery. Is a battery system that performs control for keeping the temperature within a range of 35 ° C. or higher and 55 ° C. or lower for a predetermined time.

In the battery system of the present invention, the temperature control device performs control to keep the temperature of the lithium ion secondary battery within a range of 35 ° C. or more and 55 ° C. or less for a predetermined time. By maintaining the temperature of the lithium ion secondary battery within a range of 35 ° C. or higher and 55 ° C. or lower for a predetermined time, the metal lithium deposited on the negative electrode of the lithium ion secondary battery can be efficiently returned to lithium ions. Therefore, it is possible to effectively recover the battery capacity that has decreased due to the deposition of lithium.
In this way, by using the battery by recovering the battery capacity that has decreased due to the precipitation of lithium, it is possible to suppress the deterioration of the battery and extend the battery life. Moreover, the safety | security of a battery can also be improved by reducing highly active metallic lithium.

  Furthermore, in the above battery system, the lithium ion secondary battery is mounted on the automobile as a power source for driving the automobile, and the battery system is supplied from an external power source while the automobile is stopped. The lithium ion secondary battery can be charged using electric power, and the temperature control device is configured to charge the lithium ion secondary battery using electric power supplied from the external power source. A battery system that performs control for keeping the temperature of the lithium ion secondary battery within a range of 35 ° C. or higher and 55 ° C. or lower for a predetermined time may be used.

  The battery system of the present invention is a battery system mounted on a vehicle as a power source for driving a vehicle (specifically, a hybrid vehicle or an electric vehicle), and uses lithium-ion secondary battery using power supplied from an external power source. This is a battery system having a configuration in which the secondary battery can be charged. In an automobile equipped with such a battery system, it is supplied from an external power source periodically (for example, every few days) during a predetermined time (for example, about 10 hours) while the automobile is stopped (parked in a garage or the like). There is a tendency to charge lithium ion secondary batteries using electric power. Accordingly, the temperature of the lithium ion secondary battery is kept within a range of 35 ° C. or more and 55 ° C. or less for a predetermined time during the period in which the lithium ion secondary battery is charged using electric power supplied from an external power source while the vehicle is stopped. Thus, the lithium metal deposited on the negative electrode of the lithium ion secondary battery can be periodically returned to lithium ions.

In addition, if the temperature control of the lithium ion secondary battery is performed while the automobile is running, the running performance of the automobile may be affected, but in the present invention, the temperature control of the lithium ion secondary battery is performed while the automobile is stopped. There is no such concern because it does.
The “predetermined time” for keeping the temperature of the lithium ion secondary battery within the range of 35 ° C. or higher and 55 ° C. or lower is the total period of charging the lithium ion secondary battery using the power supplied from the external power source. It is good, and it is good also as some periods.

  Furthermore, in any one of the battery systems described above, the temperature control device may be a battery system that performs control to maintain the temperature of the lithium ion secondary battery at 45 ° C. for a predetermined time.

  By maintaining the temperature of the lithium ion secondary battery at 45 ° C. for a predetermined time, the battery capacity reduced by the deposition of metallic lithium can be recovered very effectively.

  Another solution is an automobile including any one of the battery systems described above, wherein the lithium ion secondary battery is mounted as a driving power source for the automobile.

  Lithium ion secondary batteries mounted as driving power sources for automobiles (such as hybrid cars and electric cars) are charged at a high rate (large current), so they are not incorporated into the negative electrode due to the diffusion-controlled Li ions. Li ions are likely to be deposited on the negative electrode surface as metal Li. Therefore, a lithium ion secondary battery mounted on a vehicle as a driving power source is in an environment where the battery capacity is likely to be reduced as compared with a case where it is used as a power source for other electronic devices.

  If the capacity of a lithium ion secondary battery mounted on a vehicle as a driving power source decreases, the driving performance of the vehicle decreases. Furthermore, if the battery is continuously used while the battery capacity is reduced, the deterioration of the battery is promoted, and the battery reaches the end of its life at an early stage. In addition, it is not preferable in terms of safety to use a battery as a power source for driving an automobile in a state where metallic lithium is deposited.

  On the other hand, since the automobile of the present invention includes the battery system described above, the battery capacity reduced due to the deposition of metallic lithium can be effectively recovered. Thereby, the fall of the driving performance of a motor vehicle can be suppressed. Further, by using the battery by recovering the reduced battery capacity, it is possible to suppress the deterioration of the battery and extend the battery life. Moreover, by reducing highly active metallic lithium, the safety of the battery can be increased, and thus the safety of the automobile can be improved.

1 is a schematic diagram of an automobile according to Example 1. FIG. 1 is a schematic diagram of a battery system according to Example 1. FIG. It is sectional drawing of a lithium ion secondary battery. It is sectional drawing of the electrode body of a lithium ion secondary battery. It is a partial expanded sectional view of an electrode body, and is equivalent to the B section enlarged view of FIG. It is a bar graph which shows the amount of Li precipitation after each cycle test performed by varying storage temperature. 3 is a flowchart showing a flow of temperature control of the lithium ion secondary battery according to Example 1; It is the schematic of the motor vehicle concerning Example 2. FIG. 6 is a schematic diagram of a battery system according to Example 2. FIG. 6 is a flowchart showing a flow of temperature control of a lithium ion secondary battery according to Example 2;

Example 1
Next, Example 1 of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the automobile 1 according to the first embodiment includes a vehicle body 2, an engine 3, a front motor 4, a rear motor 5, a battery system 6, and a cable 7, and the engine 3, the front motor 4, and the rear motor 5. It is a hybrid car that is driven in combination. Specifically, the automobile 1 includes the battery system 6 (specifically, the assembled battery 10 of the battery system 6, see FIG. 2) as a power source for driving the front motor 4 and the rear motor 5, using known means. And the front motor 4 and the rear motor 5 are configured to be able to travel.

  Among these, the battery system 6 is attached to the vehicle body 2 of the automobile 1 and is connected to the front motor 4 and the rear motor 5 by a cable 7. As shown in FIG. 2, the battery system 6 includes an assembled battery 10 in which a plurality of lithium ion secondary batteries 100 (single cells) are electrically connected in series with each other, and a temperature control device 20. The temperature control device 20 includes a microcomputer 30, a cooling device 50 (such as a cooling fan), and a heating device 60 (such as a heater). The microcomputer 30 has a ROM, a CPU, a RAM, and the like (not shown).

  As shown in FIG. 2, the assembled battery 10 is equipped with a thermistor 40 that detects the battery temperature of the lithium ion secondary battery 100. The thermistor 40 is electrically connected to the microcomputer 30. Thereby, the microcomputer 30 can detect the battery temperature of the lithium ion secondary battery 100.

  A cooling device 50 is electrically connected to the assembled battery 10 via a switch 41. By operating the cooling device 50, the lithium ion secondary battery 100 constituting the assembled battery 10 can be cooled. Further, a heating device 60 is electrically connected to the assembled battery 10 via a switch 42. By operating the heating device 60, the lithium ion secondary battery 100 constituting the assembled battery 10 can be heated.

  The microcomputer 30 determines whether or not the battery temperature of the lithium ion secondary battery 100 detected through the thermistor 40 is 45 ° C. Further, when the microcomputer 30 determines that the battery temperature of the lithium ion secondary battery 100 is not 45 ° C., the microcomputer 30 heats or cools the lithium ion secondary battery 100 so that the temperature of the lithium ion secondary battery 100 becomes 45 ° C. Control.

  Specifically, when the microcomputer 30 determines that the battery temperature of the lithium ion secondary battery 100 is higher than 45 ° C., the microcomputer 30 performs control to cool the lithium ion secondary battery 100 by the cooling device 50. Specifically, the microcomputer 30 transmits an electrical signal that turns the switch 41 (see FIG. 2) “ON” and the switch 42 “OFF”. Thereby, since electric power is supplied from the assembled battery 10 to the cooling device 50, the cooling device 50 operates and the lithium ion secondary battery 100 constituting the assembled battery 10 can be cooled.

  Further, the microcomputer 30 detects the battery temperature of the lithium ion secondary battery 100 after starting the cooling of the lithium ion secondary battery 100. Then, it is determined whether or not the battery temperature of the lithium ion secondary battery 100 has reached 45 ° C. When it determines with the battery temperature of the lithium ion secondary battery 100 not reaching 45 degreeC, the cooling of the lithium ion secondary battery 100 by the cooling device 50 is continued.

  Thereafter, when the microcomputer 30 determines that the battery temperature of the lithium ion secondary battery 100 has reached 45 ° C., the microcomputer 30 performs control to stop cooling of the lithium ion secondary battery 100. Specifically, an electrical signal for setting the switch 41 to the “OFF” state is transmitted. Thereby, since the power supply from the assembled battery 10 to the cooling device 50 is interrupted, the cooling of the lithium ion secondary battery 100 by the cooling device 50 can be stopped.

  On the other hand, when the microcomputer 30 determines that the battery temperature of the lithium ion secondary battery 100 is lower than 45 ° C., the microcomputer 30 controls the heating device 60 to heat the lithium ion secondary battery 100. Specifically, the microcomputer 30 transmits an electrical signal that turns the switch 42 (see FIG. 2) “ON” and the switch 41 “OFF”. Thereby, since electric power is supplied from the assembled battery 10 to the heating device 60, the heating device 60 operates and the lithium ion secondary battery 100 constituting the assembled battery 10 can be heated.

  Furthermore, the microcomputer 30 detects the battery temperature of the lithium ion secondary battery 100 after starting the heating of the lithium ion secondary battery 100. Then, it is determined whether or not the battery temperature of the lithium ion secondary battery 100 has reached 45 ° C. When it determines with the battery temperature of the lithium ion secondary battery 100 not reaching 45 degreeC, the heating of the lithium ion secondary battery 100 by the heating apparatus 60 is continued.

Thereafter, when the microcomputer 30 determines that the battery temperature of the lithium ion secondary battery 100 has reached 45 ° C., the microcomputer 30 performs control to stop heating of the lithium ion secondary battery 100. Specifically, an electrical signal for turning off the switch 42 is transmitted. Thereby, since the power supply from the assembled battery 10 to the heating device 60 is interrupted, the heating of the lithium ion secondary battery 100 by the heating device 60 can be stopped.
Thus, in the first embodiment, the temperature controller 20 can maintain the battery temperature of the lithium ion secondary battery 100 within the range of 35 ° C. or higher and 55 ° C. or lower (specifically, 45 ° C.).

  As shown in FIG. 3, the lithium ion secondary battery 100 is a rectangular sealed lithium ion secondary battery including a rectangular parallelepiped battery case 110, a positive electrode terminal 120, and a negative electrode terminal 130. Among these, the battery case 110 is made of metal, and includes a rectangular housing portion 111 that forms a rectangular parallelepiped housing space, and a metal lid portion 112. An electrode body 150, a non-aqueous electrolyte 140, and the like are accommodated in the battery case 110 (rectangular accommodation part 111).

  As shown in FIGS. 4 and 5, the electrode body 150 is an oblong cross section, and is a flat wound body formed by winding a sheet-like positive electrode plate 155, a negative electrode plate 156, and a separator 157. The electrode body 150 is located at one end (right end in FIG. 3) in the axial direction (left and right in FIG. 3), and a positive winding part 155b in which only a part of the positive electrode plate 155 overlaps in a spiral shape, Located at the other end (left end in FIG. 3), only a part of the negative electrode plate 156 has a negative electrode winding part 156b that overlaps in a spiral shape. The positive electrode plate 155 is coated with a positive electrode mixture 152 including a positive electrode active material 153 at a portion other than the positive electrode winding portion 155b (see FIG. 5). Similarly, a negative electrode mixture 159 including a negative electrode active material 154 is applied to the negative electrode plate 156 at portions other than the negative electrode winding portion 156b (see FIG. 5). The positive electrode winding part 155 b is electrically connected to the positive electrode terminal 120 through the positive electrode current collecting member 122. The negative electrode winding part 156 b is electrically connected to the negative electrode terminal 130 through the negative electrode current collecting member 132.

In the lithium ion secondary battery 100, lithium nickelate is used as the positive electrode active material 153. Further, natural graphite is used as the negative electrode active material 154. Further, non-aqueous electrolyte solution 140 was prepared by dissolving lithium hexafluorophosphate (LiPF ₆ ) in a non-aqueous solvent in which EC (ethylene carbonate), DMC (dimethyl carbonate), and EMC (ethyl methyl carbonate) were mixed. A water electrolyte is used.

Next, five lithium ion secondary batteries 100 (referred to as samples 1 to 5) were prepared, and the cycle test was performed with different conditions for each sample.
Specifically, Sample 2 was charged for 10 seconds at a current value of 20 C in a temperature environment of 0 ° C., and then discharged for 10 seconds at a current value of 20 C. This charge / discharge cycle was defined as 1 cycle, and 10 cycles were performed. Then, this sample 2 was preserve | saved for 16 hours in a -15 degreeC thermostat. Eighty cycles of “charging / discharging-constant storage cycle” were performed with this charging / discharging cycle (10 cycles) and constant temperature storage (−15 ° C.) as one cycle. In other words, in sample 2, constant temperature storage (−15 ° C.) for 16 hours was provided between 10 charge / discharge cycles, and a total of 800 charge / discharge cycles were performed.
Note that 1C is a current value that can be set to 0% SOC in one hour when the lithium ion secondary battery 100 having a SOC (state of charge) 100% is discharged at a constant current.

  Moreover, about the sample 3, after performing the above-mentioned charging / discharging cycle 10 cycles, it preserve | saved for 16 hours in a 25 degreeC thermostat. Eighty charging / discharging-constant storage cycles with one cycle of this charging / discharging cycle and constant temperature storage (25 ° C.) were performed. In other words, in Sample 3, 16 hours of constant temperature storage (25 ° C.) was provided between 10 charge / discharge cycles, and a total of 800 charge / discharge cycles were performed.

  Moreover, about the sample 4, after performing the above-mentioned charging / discharging cycle 10 cycles, it preserve | saved for 16 hours in a 45 degreeC thermostat. Eighty charge / discharge-constant storage cycles were performed with this charge / discharge cycle and constant-temperature storage (45 ° C.) as one cycle. In other words, in Sample 4, 16 hours of constant temperature storage (45 ° C.) was provided between 10 charge / discharge cycles, and a total of 800 charge / discharge cycles were performed.

  Moreover, about the sample 5, after performing the above-mentioned charging / discharging cycle 10 cycles, it preserve | saved for 16 hours in a 60 degreeC thermostat. Eighty charge / discharge-constant storage cycles were performed with this charge / discharge cycle and constant-temperature storage (60 ° C.) as one cycle. In other words, in Sample 5, constant temperature storage (60 ° C.) for 16 hours was provided between 10 charge / discharge cycles, and a total of 800 charge / discharge cycles were performed.

  Moreover, about the sample 1, after performing the above-mentioned charging / discharging cycle 10 cycles, unlike the other samples, the charging / discharging cycle was performed continuously, without preserve | saving in a thermostat. In this way, a total of 800 charge / discharge cycles were performed.

  After performing the above-described cycle test on Samples 1 to 5, each sample was disassembled and the negative electrode plate 156 was taken out. Thereafter, the amount of lithium deposited on the negative electrode plate 156 was measured for each sample by ICP emission analysis. Specifically, first, a part of the negative electrode plate 156 is cut out, dissolved in aqua regia, and then diluted with water to prepare a sample solution. Next, the amount of lithium in each sample solution (that is, the weight of lithium deposited on a part of the negative electrode plate 156) was measured using an ICP emission spectrometer (ICPS-8100, manufactured by Shimadzu Corporation). Based on this measurement result, the amount of lithium deposited on the entire negative electrode plate 156 was calculated. The result is shown in FIG. In FIG. 6, the amount of Li deposited in each sample is relatively represented by the length of the bar graph based on Sample 1.

  As shown in FIG. 6, in samples 2 to 5 in which constant temperature storage (−15 ° C. to 60 ° C.) was performed every 10 charge / discharge cycles, the Li precipitation amount was smaller than in sample 1 in which constant temperature storage was not performed. It was possible to reduce. Specifically, when the amount of Li deposited in Sample 1 is A, the amount of Li deposited in Sample 2 is 0.57A. That is, sample 2 was able to reduce the amount of Li precipitation by 43% compared to sample 1. From this result, 43% (0.43 A) of Li deposited on the negative electrode plate 156 was obtained by maintaining the temperature of the lithium ion secondary battery 100 at −15 ° C. for 16 hours every 10 charge / discharge cycles. It can be said that it was able to return to lithium ion. Since it can be said that the battery capacity is reduced according to the amount of Li deposition, maintaining the temperature of the lithium ion secondary battery 100 at −15 ° C. for 16 hours recovers 43% of the battery capacity reduced by cycle charge / discharge. I can say that.

  In Sample 3, the amount of precipitated Li was 0.3A. That is, in the sample 3, compared with the sample 1, the Li precipitation amount could be reduced by 70%. From this result, by maintaining the temperature of the lithium ion secondary battery 100 at 25 ° C. for 16 hours every 10 charge / discharge cycles, 70% (0.7 A) of Li deposited on the negative electrode plate 156 was reduced to lithium. It can be said that it was able to return to ion. Therefore, it can be said that 70% of the battery capacity reduced by the cycle charge / discharge could be recovered by maintaining the temperature of the lithium ion secondary battery 100 at 25 ° C. for 16 hours.

  In sample 4, the amount of precipitated Li was 0.18A. That is, in the sample 4, compared with the sample 1, the Li precipitation amount could be reduced by 82%. From this result, 82% (0.82A) of Li deposited on the negative electrode plate 156 was obtained by maintaining the temperature of the lithium ion secondary battery 100 at 45 ° C. for 16 hours every 10 charge / discharge cycles. It can be said that it was able to return to ion. Therefore, it can be said that by maintaining the temperature of the lithium ion secondary battery 100 at 45 ° C. for 16 hours, it was possible to recover 82% of the battery capacity reduced by the cycle charge / discharge.

  In Sample 5, the amount of precipitated Li was 0.4A. That is, in Sample 5, the Li precipitation amount could be reduced by 60% compared to Sample 1. From this result, by maintaining the temperature of the lithium ion secondary battery 100 at 60 ° C. for 16 hours for every 10 charge / discharge cycles, 60% (0.6 A) of Li deposited on the negative electrode plate 156 was reduced to lithium. It can be said that it was able to return to ion. Therefore, it can be said that 60% of the battery capacity reduced by the cycle charge / discharge could be recovered by maintaining the temperature of the lithium ion secondary battery 100 at 60 ° C. for 16 hours.

  From the above results, it can be said that it is most preferable to set the storage temperature at 45 ° C. in order to effectively recover the battery capacity which has been reduced by the precipitation of lithium. Further, from the fluctuation tendency of the Li precipitation amount shown in FIG. 6 (in other words, the tendency of battery capacity recovery), the battery temperature is 35 ° C. and the battery temperature is 25 ° C. (70% recovery). It can be said that the capacity can be recovered. Furthermore, when the storage temperature is 55 ° C., the battery capacity can be recovered more than when the storage temperature is 60 ° C. (60% recovery). Therefore, if the storage temperature is in the range of 35 ° C. or higher and 55 ° C. or lower, it can be said that the battery capacity decreased due to the precipitation of lithium can be effectively recovered.

  From the above, it can be said that by maintaining the temperature of the lithium ion secondary battery 100 within a range of 35 ° C. or more and 55 ° C. or less for a predetermined time, it is possible to effectively recover the battery capacity reduced due to lithium deposition. . In particular, it can be said that by maintaining the temperature of the lithium ion secondary battery 100 at 45 ° C. for a predetermined time, the battery capacity reduced due to the precipitation of lithium can be recovered very effectively.

Next, temperature control of the lithium ion secondary battery 100 in the automobile 1 of the first embodiment will be described with reference to FIG.
First, in step S1, the microcomputer 30 detects the temperature of the lithium ion secondary battery 100 based on an output signal from the thermistor 40 (see FIG. 2). Subsequently, it progresses to step S2 and it is determined whether the battery temperature of the detected lithium ion secondary battery 100 is 45 degreeC.

In step S2, when it is determined that the battery temperature of the lithium ion secondary battery 100 is 45 ° C. (Yes), the process returns to step S1 again and the above-described processing is performed.
On the other hand, if it is determined in step S2 that the battery temperature of the lithium ion secondary battery 100 is not 45 ° C. (No), the process proceeds to step S3, where the lithium ion secondary battery 100 constituting the assembled battery 10 is cooled or Start heating.

  Specifically, when the microcomputer 30 determines that the battery temperature of the lithium ion secondary battery 100 is higher than 45 ° C., the microcomputer 30 performs control to cool the lithium ion secondary battery 100 by the cooling device 50. Specifically, the microcomputer 30 transmits an electrical signal that turns the switch 41 (see FIG. 2) “ON” and the switch 42 “OFF”. Thereby, since electric power is supplied from the assembled battery 10 to the cooling device 50, the cooling device 50 operates and the lithium ion secondary battery 100 constituting the assembled battery 10 can be cooled.

  On the contrary, when the microcomputer 30 determines that the battery temperature of the lithium ion secondary battery 100 is lower than 45 ° C., the heating device 60 controls to heat the lithium ion secondary battery 100. Specifically, the microcomputer 30 transmits an electrical signal that turns the switch 42 (see FIG. 2) “ON” and the switch 41 “OFF”. Thereby, since electric power is supplied from the assembled battery 10 to the heating device 60, the heating device 60 operates and the lithium ion secondary battery 100 constituting the assembled battery 10 can be heated.

  Next, it progresses to step S4 and the temperature of the lithium ion secondary battery 100 is detected. Then, it progresses to step S5 and it is determined whether the battery temperature of the detected lithium ion secondary battery 100 reached 45 degreeC.

  If it is determined in step S5 that the battery temperature of the lithium ion secondary battery 100 has not reached 45 ° C. (No), the process returns to step S4 again to detect the temperature of the lithium ion secondary battery 100. Thereafter, when it is determined in step S5 that the battery temperature of the lithium ion secondary battery 100 has reached 45 ° C. (Yes), the process proceeds to step S6, and the lithium ion secondary battery 100 (the assembled battery 10) Stop cooling or heating.

  Specifically, when the lithium ion secondary battery 100 is being cooled, the microcomputer 30 transmits an electrical signal that sets the switch 41 to the “OFF” state. Thereby, since the power supply from the assembled battery 10 to the cooling device 50 is interrupted, the cooling of the lithium ion secondary battery 100 by the cooling device 50 can be stopped.

  On the other hand, when the lithium ion secondary battery 100 is being heated, the microcomputer 30 transmits an electrical signal for setting the switch 42 to the “OFF” state. Thereby, since the power supply from the assembled battery 10 to the heating device 60 is interrupted, the heating of the lithium ion secondary battery 100 by the heating device 60 can be stopped.

  Next, the process proceeds to step S7, and the microcomputer 30 determines whether or not a predetermined time (for example, 8 hours) has elapsed since it was first determined that the temperature of the lithium ion secondary battery 100 was 45 ° C. If it is determined that the predetermined time has not elapsed (No), the process returns to step S1 and the above-described processing is performed. On the other hand, if it is determined that the predetermined time has elapsed (Yes), the series of processes is terminated.

  Thus, in the first embodiment, the temperature of the lithium ion secondary battery 100 can be maintained within a range of 35 ° C. to 55 ° C. (specifically 45 ° C.) for a predetermined time (for example, 8 hours). it can. Thereby, the metallic lithium deposited on the negative electrode plate 156 of the lithium ion secondary battery 100 can be efficiently returned to lithium ions. Therefore, it is possible to effectively recover the battery capacity that has decreased due to the deposition of lithium.

  In this way, by using the lithium ion secondary battery 100 (the assembled battery 10) by recovering the battery capacity that has been reduced due to the deposition of metallic lithium, the deterioration of the lithium ion secondary battery 100 is suppressed, and the battery life is shortened. Can be extended. Furthermore, it is possible to suppress a decrease in the running performance of the automobile 1. Further, by reducing highly active metallic lithium, the safety of the lithium ion secondary battery 100 can be improved, and consequently the safety of the automobile 1 can be improved.

  In addition, it is good to perform the process (temperature control of the lithium ion secondary battery 100) of the above-mentioned step S1-S7 for every predetermined period (for example, once every several days), for example. Further, the amount of Li deposited on the negative electrode plate 156 of the lithium ion secondary battery 100 is estimated, and when this estimated amount reaches a specified value, the processing of the above-described steps S1 to S7 (temperature control of the lithium ion secondary battery 100). ) May be performed.

(Example 2)
Next, Embodiment 2 of the present invention will be described with reference to the drawings.
A hybrid vehicle 11 of the second embodiment is shown in FIG. The hybrid vehicle 11 is different from the hybrid vehicle 1 of the first embodiment in the secondary battery system. Further, a power plug 8 connected to the secondary battery system is provided.
As shown in FIG. 9, the secondary battery system 16 of the second embodiment includes the assembled battery 10, the temperature control device 220, the conversion device 44, and the voltage detection device 80.

  Among these, the temperature control device 220 includes a microcomputer 230, a cooling device 50, and a heating device 60. Further, the voltage detection device 80 detects the battery voltage (inter-terminal voltage) of each lithium ion secondary battery 100 constituting the assembled battery 10.

  The converter 44 is configured by an AC / DC converter, and can convert the voltage of the commercial power supply 46 (external power supply) into a DC constant voltage having a constant voltage value. The conversion device 44 is electrically connected to the power plug 8 through a cable 71 included in the cable 7. Further, the conversion device 44 is electrically connected to the assembled battery 10 via the switch 43. The conversion device 44 is electrically connected to the cooling device 50 via the switch 41, and is electrically connected to the heating device 60 via the switch 42.

  The power plug 8 is configured to be electrically connectable to the commercial power source 46. The power plug 8 is electrically connected to the conversion device 44. Therefore, the converter 44 and the commercial power source 46 can be electrically connected through the power plug 8. In the second embodiment, the cable 71 can be pulled out of the hybrid vehicle 11 together with the power plug 8, and the power plug 8 can be connected to the commercial power supply 46 that is remote from the hybrid vehicle 11.

  For this reason, in the hybrid vehicle 11 of the second embodiment, the power plug 8 is electrically connected to the commercial power source 46 while the hybrid vehicle 11 is stopped, so that the power is supplied from the commercial power source 46. The lithium ion secondary battery 100 constituting the battery 10 can be charged (hereinafter, this charging is also referred to as plug-in charging).

  When the microcomputer 230 monitors the conversion device 44 and detects that power is supplied from the commercial power supply 46 to the conversion device 44 through the power plug 8, the microcomputer 230 turns off the switches 47 and 48 and turns on the switch 43. To do. Thereby, the lithium ion secondary battery 100 which comprises the assembled battery 10 can be charged using the electric power supplied from the commercial power supply 46. FIG. Specifically, the battery pack 10 supplies the electric power supplied from the commercial power supply 46 through the conversion device 44 while converting the voltage of the commercial power supply 46 into a DC constant voltage having a predetermined constant voltage value by the conversion device 44. Is supplied to the lithium ion secondary battery 100 constituting the.

  Further, the microcomputer 230 uses the commercial power supply 46 to charge the lithium ion secondary battery 100, and the lithium ion secondary battery 100 constituting the assembled battery 10 is based on the battery voltage detected by the voltage detection device 80. Is estimated. Then, when it is determined that the SOC has reached 100%, the charging of the assembled battery 10 is stopped. Specifically, the switch 43 is turned off and the switches 47 and 48 are turned on.

  Further, the microcomputer 230 determines whether or not the battery temperature of the lithium ion secondary battery 100 detected through the thermistor 40 during plug-in charging is 45 ° C. Further, when the microcomputer 230 determines that the battery temperature of the lithium ion secondary battery 100 is not 45 ° C., the temperature of the lithium ion secondary battery 100 is 45 ° C., similarly to the microcomputer 30 of Example 1. Control to heat or cool the lithium ion secondary battery 100 is performed.

Next, temperature control of the lithium ion secondary battery 100 in the automobile 11 of the second embodiment will be described with reference to FIG.
First, in step T1, the microcomputer 230 determines whether plug-in charging has been started. Specifically, it is determined whether or not the power plug 8 is electrically connected to the commercial power source 46. The microcomputer 230 monitors the converter 44 and detects that power is supplied from the commercial power supply 46 to the converter 44 through the power plug 8, whereby the power plug 8 is electrically connected to the commercial power supply 46. Judge that Then, the microcomputer 230 turns off the switches 47 and 48 and turns on the switch 43. Thereby, electric power can be supplied from the commercial power supply 46 to the assembled battery 10 through the converter 44, and charging of the lithium ion secondary battery 100 constituting the assembled battery 10 can be started. Therefore, the microcomputer 230 determines that plug-in charging has started when the switches 47 and 48 are turned off and the switch 43 is turned on.

If it is determined in step T1 that plug-in charging has not started (No), the microcomputer 230 repeats this process until it is determined that plug-in charging has started (Yes).
If it is determined in step T1 that plug-in charging has started (Yes), the process proceeds to step T2, and the microcomputer 230 detects the temperature of the lithium ion secondary battery 100 based on the output signal from the thermistor 40. Subsequently, it progresses to step T3 and it is determined whether the battery temperature of the detected lithium ion secondary battery 100 is 45 degreeC.

In step T3, when it is determined that the battery temperature of the lithium ion secondary battery 100 is 45 ° C. (Yes), the process returns to step T2 again and the above-described processing is performed.
On the other hand, when it is determined in step T3 that the battery temperature of the lithium ion secondary battery 100 is not 45 ° C. (No), the process proceeds to step T4, and cooling or heating of the lithium ion secondary battery 100 constituting the assembled battery 10 is performed. To start.

  Specifically, when the microcomputer 230 determines that the battery temperature of the lithium ion secondary battery 100 is higher than 45 ° C., the microcomputer 230 controls the cooling device 50 to cool the lithium ion secondary battery 100. Specifically, the microcomputer 230 transmits an electrical signal that turns the switch 41 “ON” and the switch 42 “OFF”. Thereby, since electric power is supplied to the cooling device 50 from the commercial power supply 46 through the converter 44, the cooling device 50 operates and the lithium ion secondary battery 100 constituting the assembled battery 10 can be cooled.

  Conversely, when the microcomputer 230 determines that the battery temperature of the lithium ion secondary battery 100 is lower than 45 ° C., the heating device 60 controls to heat the lithium ion secondary battery 100. Specifically, the microcomputer 230 transmits an electrical signal that turns the switch 42 “ON” and the switch 41 “OFF”. Thereby, since electric power is supplied from the commercial power supply 46 to the heating device 60 through the conversion device 44, the heating device 60 operates and the lithium ion secondary battery 100 constituting the assembled battery 10 can be heated.

  Next, it progresses to step T5 and the temperature of the lithium ion secondary battery 100 is detected. Then, it progresses to step T6 and it is determined whether the battery temperature of the detected lithium ion secondary battery 100 reached 45 degreeC.

  If it is determined in step T6 that the battery temperature of the lithium ion secondary battery 100 has not reached 45 ° C. (No), the process returns to step T5 again to detect the temperature of the lithium ion secondary battery 100. Thereafter, when it is determined in step T6 that the battery temperature of the lithium ion secondary battery 100 has reached 45 ° C. (Yes), the process proceeds to step T7, where the lithium ion secondary battery 100 (the assembled battery 10) is cooled or Stop heating.

  Specifically, when the lithium ion secondary battery 100 is being cooled, the microcomputer 230 transmits an electrical signal that sets the switch 41 to the “OFF” state. As a result, the power supply from the commercial power supply 46 to the cooling device 50 through the converter 44 is interrupted, so that the cooling of the lithium ion secondary battery 100 by the cooling device 50 can be stopped. At this time, power is not supplied from the assembled battery 10 to the cooling device 50 (see FIG. 9).

  On the other hand, when the lithium ion secondary battery 100 is heated, the microcomputer 230 transmits an electrical signal that sets the switch 42 to the “OFF” state. Thereby, since the power supply from the commercial power source 46 to the heating device 60 through the converter 44 is interrupted, the heating of the lithium ion secondary battery 100 by the heating device 60 can be stopped. At this time, power is not supplied from the assembled battery 10 to the heating device 60 (see FIG. 9).

  Next, in step T8, the microcomputer 230 determines whether plug-in charging has been completed. Specifically, the microcomputer 230 estimates the SOC of the lithium ion secondary battery 100 based on the battery voltage detected by the voltage detection device 80 during plug-in charging. Then, when it is determined that the SOC has reached 100%, the charging of the assembled battery 10 is stopped. Specifically, the switch 43 is turned off and the switches 47 and 48 are turned on. Accordingly, the microcomputer 230 determines that the plug-in charging is completed when the switch 43 is turned off and the switches 47 and 48 are turned on.

  If the microcomputer 230 determines in step T8 that the plug-in charging has not ended (No), the microcomputer 230 returns to step T2 again and performs the above-described processing. On the other hand, if it is determined that the plug-in charging has been completed (Yes), the series of processes is terminated.

  As described above, in the second embodiment, during the period of charging the lithium ion secondary battery 100 using the power supplied from the external power supply (commercial power supply 46) (that is, during plug-in charging), the lithium ion secondary is charged. The temperature of the battery 100 can be maintained within a range of 35 ° C. or higher and 55 ° C. or lower (specifically, 45 ° C.). Thereby, the metallic lithium deposited on the negative electrode plate 156 of the lithium ion secondary battery 100 can be efficiently returned to lithium ions. Therefore, it is possible to effectively recover the battery capacity that has decreased due to the deposition of lithium.

  In this way, by using the lithium ion secondary battery 100 (the assembled battery 10) by recovering the battery capacity that has been reduced due to the deposition of metallic lithium, the deterioration of the lithium ion secondary battery 100 is suppressed, and the battery life is shortened. Can be extended. Furthermore, it is possible to suppress a decrease in the running performance of the automobile 11. Further, by reducing highly active metallic lithium, the safety of the lithium ion secondary battery 100 can be improved, and consequently the safety of the automobile 11 can be improved.

  In addition, it is good to implement the process (temperature control of the lithium ion secondary battery 100) of the above-mentioned step T1-T8, for example, whenever plug-in charge is performed. Further, the amount of Li deposited on the negative electrode plate 156 of the lithium ion secondary battery 100 may be estimated, and the process may be performed during plug-in charging only when the estimated amount reaches a specified value.

  In the above, the present invention has been described with reference to the first and second embodiments. However, the present invention is not limited to the above-described embodiments, and it can be applied as appropriate without departing from the scope of the present invention. Nor.

DESCRIPTION OF SYMBOLS 1,11 Car 6,16 Battery system 10 Assembly battery 20,220 Temperature control device 30,230 Microcomputer (temperature control device)
46 Commercial power (external power)
50 Cooling device (temperature control device)
60 Heating device (temperature control device)
100 Lithium ion secondary battery

Claims (4)

A lithium ion secondary battery;
A temperature control device for controlling the temperature of the lithium ion secondary battery, and a battery system comprising:
The said temperature control apparatus is a battery system which performs control which maintains the temperature of the said lithium ion secondary battery in the range of 35 degreeC or more and 55 degrees C or less for a predetermined time. The battery system according to claim 1,
The lithium ion secondary battery is
It is mounted on the car as a power source for driving the car,
The battery system includes:
While the vehicle is stopped, the lithium ion secondary battery can be charged using electric power supplied from an external power source,
The temperature control device includes:
A battery system for controlling the temperature of the lithium ion secondary battery within a range of 35 ° C. or higher and 55 ° C. or lower for a predetermined time during the period of charging the lithium ion secondary battery using electric power supplied from the external power source. . The battery system according to claim 1 or 2,
The said temperature control apparatus is a battery system which performs control which maintains the temperature of the said lithium ion secondary battery at 45 degreeC for a predetermined time. An automobile comprising the battery system according to any one of claims 1 to 3,
An automobile in which the lithium ion secondary battery is mounted as a power source for driving the automobile.

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