JP2017224457A - Restraint system of secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the life of a secondary battery.SOLUTION: A restraint system 200 of a secondary battery is applied to a secondary battery 10 having an electrode body including a positive electrode active material layer containing positive electrode active material particles composed of a multiple oxide containing at least Ni, Co and Mn, and a battery case 12 housing the electrode body. A controller 206 includes a storage unit 206a, a calculation unit 206b and an operation unit 206c. The storage unit stores an initial value A of an activation energy of the secondary battery. The calculation unit calculates an activation energy B of the secondary battery at a certain time determined arbitrarily, on the basis of a current value acquired from a current sensor 203, and a voltage value acquired from a voltage sensor 204. When the ratio (B/A) of the initial value A of the activation energy stored in the storage unit and the activation energy B calculated in the calculation unit is higher than a predetermined threshold, the operation unit operates a pressure adjustment mechanism 202 to increase the restraint pressure.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a secondary battery restraint system.

  Japanese Patent Laying-Open No. 2011-257314 discloses a deterioration determination method for determining deterioration of a secondary battery. In the degradation determination method of the publication, the internal resistance of the secondary battery is acquired. If the internal resistance is equal to or greater than the deterioration threshold that is the threshold for determining deterioration, the process waits until a predetermined standby time elapses, and acquires the internal resistance again after the standby time elapses. Then, the internal resistance acquired for the first time is compared with the internal resistance acquired for the second time to determine whether the internal resistance has recovered. If it is determined that the internal resistance has recovered, it is determined that no degradation has occurred. When it is determined that the internal resistance has not recovered, it is determined that the increase in the internal resistance is not temporary but has deteriorated.

  Japanese Patent Application Laid-Open No. 2005-149793 proposes a method for calculating an upper limit temperature when charging and discharging a secondary battery. In this publication, the activation energy of the main side reaction that causes battery deterioration is obtained from the operating temperature of the secondary battery and the capacity decrease at that temperature, and the charge / discharge temperature when the activation energy changes is determined as the charge / discharge temperature. It has been proposed to have an upper limit temperature.

  In JP2013-131392A, when a lithium ion secondary battery is charged and discharged at a high rate, a crystal of a lithium transition metal oxide used as a positive electrode active material particle causes a rapid volume change, In addition, it is disclosed that cracks occur at the crystal interface.

JP 2011-257314 A JP 2005-149793 A JP2013-131392A

  By the way, it is desirable that the secondary battery is appropriately used so as to have a long life. Here, a system capable of extending the life of a secondary battery using positive electrode active material particles made of a composite oxide containing at least Ni, Co, and Mn is proposed.

The secondary battery restraint system proposed here includes an electrode body including a positive electrode active material layer including positive electrode active material particles made of a composite oxide containing at least Ni, Co, and Mn, and a battery containing the electrode body The present invention is applied to a secondary battery having a case. Such a secondary battery restraint system includes a secondary battery, a restraint member, a pressure adjusting mechanism, a current sensor, a voltage sensor, and a control device.
The restraining member is a member that is attached to the battery case and restrains the battery case. The pressure adjusting mechanism is a mechanism that is provided on the restraining member and adjusts the restraining pressure that acts on the battery case by the restraining member. The current sensor is a sensor that detects a current flowing through the secondary battery. The voltage sensor is a sensor that detects a voltage applied to the secondary battery.
The control device includes a storage unit, a calculation unit, and an operation unit. Here, the storage unit stores an initial value A of activation energy of the secondary battery. The calculation unit calculates an activation energy B of the secondary battery at a predetermined time arbitrarily determined based on the current value acquired from the current sensor and the voltage value acquired from the voltage sensor. When the ratio (B / A) between the activation energy initial value A stored in the storage unit and the activation energy B calculated by the calculation unit is higher than a predetermined threshold value, the operation unit is restrained. The pressure adjusting mechanism is operated so that the pressure increases.

  According to the secondary battery restraint system proposed here, the restraint pressure is increased when the ratio (B / A) of the activation energy B to the initial value A of the activation energy is greater than a predetermined threshold. Get higher. And the activation energy of a secondary battery becomes low. By suppressing the activation energy of the secondary battery to be low, the generation of cracks in the positive electrode active material particles is suppressed, and the progress of irreversible deterioration in the secondary battery is suppressed.

FIG. 1 is a schematic diagram of a configuration example of a secondary battery restraint system proposed here. FIG. 2 is a cross-sectional view schematically showing a configuration example of the secondary battery proposed here. FIG. 3 is a graph showing a slope as activation energy. FIG. 4 is a graph showing the relationship between the restraint load (restraint pressure) and the activation energy. FIG. 5 is a graph showing the relationship between the constraint load ratio and the activation energy ratio. FIG. 6 is a flowchart of the secondary battery restraint system proposed here.

  Hereinafter, an embodiment of a secondary battery restraint system proposed here will be described. The embodiments described herein are, of course, not intended to limit the present invention in particular. The invention is not limited to the forms described herein unless specifically stated.

  FIG. 1 is a schematic diagram of a configuration example of a secondary battery restraint system proposed here. FIG. 2 is a cross-sectional view schematically showing a configuration example of the secondary battery proposed here.

  In the form shown in FIG. 1, the secondary battery restraint system 200 is applied to an assembled battery 100 in which a plurality of secondary batteries 10 are combined. Here, the secondary battery 10 includes, for example, an electrode body 11 and a battery case 12 in which the electrode body 11 is accommodated, as shown in FIG. The electrode body 11 includes a positive electrode active material layer 53 including positive electrode active material particles made of a composite oxide containing at least Ni, Co, and Mn. The secondary battery 10 includes an electrode body 11 and a battery case 12. The battery case 12 includes a case main body 12a, a lid 12b, and electrode terminals 13 and 14.

  The electrode body 11 includes, for example, a positive electrode sheet 50, a negative electrode sheet 60, and separators 72 and 74. In the form shown in FIG. 2, the positive electrode sheet 50 includes a positive electrode current collector foil 51 and a positive electrode active material layer 53. The positive electrode current collector foil 51 is a belt-like sheet (for example, an aluminum foil). In the positive electrode current collector foil 51, an exposed portion 52 is set along an edge on one side in the width direction. A positive electrode active material layer 53 is formed on both surfaces of the positive electrode current collector foil 51 except for the exposed portion 52. The negative electrode sheet 60 has a negative electrode current collector foil 61 and a negative electrode active material layer 63. The negative electrode current collector foil 61 is a belt-like sheet (for example, copper foil). In the negative electrode current collector foil 61, an exposed portion 62 is set along an edge on one side in the width direction. A negative electrode active material layer 63 is formed on both surfaces of the negative electrode current collector foil 61 except for the exposed portion 62.

  The positive electrode sheet 50 and the negative electrode sheet 60 are aligned so that the length direction is aligned, and the positive electrode active material layer 53 and the negative electrode active material layer 63 are opposed to each other with the separators 72 and 74 interposed therebetween. At this time, the exposed portion 52 of the positive electrode current collector foil 51 protrudes on one side of the separators 72 and 74 in the width direction, and the exposed portion 62 of the negative electrode current collector foil 61 protrudes on the opposite side of the separators 72 and 74 in the width direction. The positive electrode sheet 50 and the negative electrode sheet 60 are stacked. The positive electrode sheet 50, the negative electrode sheet 60, and the separators 72 and 74 are wound around the winding axis WL set along the short width of the positive electrode sheet 50 in a state where they are stacked as described above. The exposed portion 52 of the positive electrode current collector foil 51 protrudes from the separators 72 and 74 on one side of the electrode body 11 along the winding axis WL. On the opposite side, the exposed portion 62 of the negative electrode current collector foil 61 protrudes from the separators 72 and 74.

  The case main body 12 a is a member that accommodates the electrode body 11. In the form shown in FIG. 2, the case main body 12a has a bottomed rectangular parallelepiped shape with one side surface opened. The lid 12b is a member that is attached to one opened side surface and closes the opening of the case body 12a. The lid 12b is welded to the opening periphery of the case body 12a. The case body 12a and the lid 12b are preferably made of a lightweight metal material having an appropriate strength, such as aluminum, aluminum alloy, steel (SUS material), or the like.

  In this embodiment, the electrode terminals 13 and 14 are provided on both sides in the longitudinal direction of the lid 12b as shown in FIG. The electrode terminals 13 and 14 include internal terminals 13 a and 14 a that extend into the battery case 12 and external terminals 13 b and 14 b that are disposed outside the battery case 12. The internal terminals 13a and 14a and the external terminals 13b and 14b are attached to the lid 12b with gaskets 13d and 14d having insulating properties interposed therebetween. The internal terminals 13a and 14a and the external terminals 13b and 14b are arranged so as to sandwich the lid 12b between the inside and outside of the lid 12b, and are fixed to the lid 12b by caulking members 13c and 14c that penetrate the lid 12b. Connected. The exposed portion 52 of the positive electrode current collector foil 51 is welded to the tip end portion 13a1 of the internal terminal 13a of the positive electrode. The exposed portion 62 of the negative electrode current collector foil 61 is welded to the tip portion 14a1 of the negative electrode internal terminal 14a.

  In the form shown in FIG. 2, the case main body 12 a is a rectangular case and has a flat rectangular receiving area. The electrode body 11 is accommodated in the case main body 12a in a flat shape along one plane including the winding axis WL. After the electrode body 11 is accommodated, a lid 12b is attached to the case body 12a. An insulating film (not shown) is interposed between the case main body 12a and the lid 12b and the electrode body 11, and the case main body 12a and the lid 12b and the wound electrode body 11 are insulated. The lid 12 b is provided with a safety valve 30 and a liquid injection hole 32, and a cap material 33 is attached to the liquid injection hole 32. The electrolytic solution 80 is injected from the injection hole 32 into the case main body 12a. The liquid injection hole 32 is closed by attaching the cap material 33 after the electrolytic solution 80 is injected.

  Here, as the electrode body, a wound electrode body 11 (so-called wound electrode body) in which the positive electrode sheet 50, the negative electrode sheet 60, and the separators 72 and 74 are overlapped and wound around the winding axis WL. ) Is illustrated. The structure of the electrode body is not limited to this. For example, a so-called laminated electrode body (also referred to as “laminated electrode body”) in which a positive electrode sheet 50 and a negative electrode sheet 60 having a predetermined shape are stacked with a separator interposed therebetween is employed. Also good. 2 illustrates a battery case 12 including a rectangular parallelepiped case body 12a made of aluminum, an aluminum alloy, steel (SUS material), or the like, and a lid 12b. The structure of the battery case 12 is not limited to this. For example, the battery case 12 may be formed of a bag-like laminate case.

Here, the positive electrode active material layer 53 includes positive electrode active material particles made of a composite oxide containing at least Ni, Co, and Mn. Examples of the composite oxide containing at least Ni, Co, and Mn include a lithium transition metal oxide containing at least Ni, Co, and Mn (hereinafter also referred to as LiNiCoMn oxide). As a suitable example of the LiNiCoMn oxide, for example, a lithium transition metal oxide having a layered structure represented by the general formula (I): Li _{1 + x} Ni _y Co _z Mn _(1-yz) M 0 _a O ₂ ; Can be mentioned. Here, M0 in the formula (I) is, for example, Al, Cr, Fe, V, Mg, Ca, Na, Ti, Zr, Nb, Mo, W, Cu, Zn, Ga, In, Sn, La, It may be one or more selected from the group consisting of Ce, B and F. A in formula (I) may be 0 <a <0.05. X, y, and z in formula (I) satisfy 0.05 ≦ x ≦ 0.2; 0.3 ≦ y <0.9; and 0.1 <z <0.4, respectively. It is preferable. For example, a LiNiCoMn oxide containing approximately the same amount of Ni, Co, and Mn can be preferably used.

  As shown in FIG. 1, the secondary battery restraint system 200 is applied to an assembled battery 100 in which a plurality of secondary batteries 10 are combined. Here, the secondary battery 10 is stacked with the wide surfaces of the rectangular parallelepiped battery case 12 facing each other. In the example illustrated in FIG. 1, the assembled battery 100 includes three secondary batteries 10, but the number of secondary batteries 10 that form the assembled battery 100 is not limited to this. The number of secondary batteries 10 (unit cells) constituting the assembled battery 100 may be, for example, 10 or more, preferably about 10 to 30, for example, 20. The plurality of secondary batteries 10 constituting the assembled battery 100 are alternately reversed in the arrangement of the positive terminal 13 and the negative terminal 14 so that the positive terminal 13 and the negative terminal 14 are adjacent to each other in the adjacent secondary battery 10. The battery case 12 is overlapped with the wide surface facing each other. Although illustration is omitted between adjacent secondary batteries 10, a spacer or a cooling plate may be interposed. Among the secondary batteries 10 constituting the assembled battery 100, adjacent secondary batteries 10 are electrically connected by a bus bar 102. The bus bar 102 connects the positive electrode terminal 13 and the negative electrode terminal 14 of the adjacent secondary battery 10, and the assembled battery 100 having a desired voltage is constructed by sequentially connecting the secondary batteries 10 in series. Yes.

  As shown in FIG. 1, a restraint system 200 that restrains the secondary battery 10 includes a restraint member 201, a pressure adjustment mechanism 202, a current sensor 203, a voltage sensor 204, a temperature sensor 205, and a control device 206. I have.

  The restraining member 201 is a member that is attached to the battery case and restrains the battery case. In this embodiment, the secondary battery 10 is composed of the assembled battery 100 as described above. The restraining member 201 is attached to the battery cases 12 of the plurality of secondary batteries 10 constituting the assembled battery 100 and restrains the battery cases 12 of the secondary batteries 10. The restraining member 201 includes, for example, end plates 201a and 201b and restraining belts 201c and 201d. The end plates 201 a and 201 b are members that are applied to the secondary battery 10 disposed at both ends of the assembled battery 100. The restraining belts 201c and 201d are members spanned between the end plates 201a and 201b at both ends.

  The pressure adjusting mechanism 202 is a mechanism provided in the restraining member 201 and adjusts the restraining pressure acting on the battery case 12 by the restraining member 201. The pressure adjusting mechanism 202 includes, for example, a ball screw mechanism 202a attached to the ends of the restraining belts 201c and 201d and the ball screw so that the attachment positions of the end plates 201a and 201b with respect to the restraining belts 201c and 201d can be operated. It can be embodied by a servo motor 202b that operates the mechanism 202a. In this case, the ball screw mechanism 202a is operated by operating the servo motor 202b, and the distance between the end plates 201a and 201b at both ends attached to the restraining belts 201c and 201d is adjusted. By adjusting the distance between the end plates 201a and 201b, the binding pressure acting on the secondary battery 10 of the assembled battery 100 in the arranged direction is adjusted. Further, when the binding pressure acts on the battery case 12 of the secondary battery 10, the binding pressure also acts on the wound electrode body 11 accommodated in the battery case 12.

  In this embodiment, the surface pressure sensors 202c1 to 202c3 are attached to the battery case 12 of the secondary battery 10. The surface pressure sensors 202c1 to 202c3 are respectively attached to the central portion of the surface where the end plate 201a hits the battery case 12 and three places on both sides. The ball screw mechanism 202a is operated based on the information on the restraint pressure acting on the battery case 12 obtained from the surface pressure sensors 202c1 to 202c3. By operating the ball screw mechanism 202a, the restraining pressure acting on the battery case 12 is adjusted. Here, the pressure adjusting mechanism 202 is described as a mechanism that adjusts the restraining pressure acting on the battery case 12 by the restraining member 201. The pressure adjusting mechanism 202 substantially functions as a mechanism for adjusting the restraining load acting on the secondary battery 10.

  In the example shown in FIG. 1, a plurality of secondary batteries 10 constituting the assembled battery 100 are connected in series. The assembled battery 100 is connected to the power control unit 120. The power control unit 120 is connected to an external device (not shown) such as a generator or a motor. The power control unit 120 is a control device that performs various controls, and includes an electrical arithmetic device such as a CPU and a storage device such as a memory. Here, with respect to the assembled battery 100, the power control unit 120 controls charging and discharging according to a predetermined program.

  The current sensor 203 is a sensor that detects a current flowing through the secondary battery 10. The voltage sensor 204 is a sensor that detects a voltage applied to the secondary battery 10. The temperature sensor 205 is attached to the secondary battery 10 and is a sensor that detects the temperature of the secondary battery 10. Here, the current sensor 203 and the voltage sensor 204 are preferably provided in electrical wirings connected to the assembled battery 100, respectively. The current sensor 203, the voltage sensor 204, and the temperature sensor 205 are electrically connected to the power control unit 120, respectively. Detection signals detected by the sensors are sent to the power control unit 120.

  The control device 206 includes a storage unit 206a, a calculation unit 206b, and an operation unit 206c. In this embodiment, a control device 206 that operates the pressure adjusting mechanism 202 is incorporated in the power control unit 120. Processing and functions executed in the control device 206 are embodied by a program stored in advance in the power control unit 120. The control device 206 that operates the pressure adjustment mechanism 202 may be embodied by a computer provided separately from the power control unit 120.

The storage unit 206 a stores an initial value A of activation energy of the secondary battery 10.
The arithmetic unit 206b calculates the activation energy B of the secondary battery 10 at a predetermined time based on the current value acquired from the current sensor 203 and the voltage value acquired from the current sensor 203.
When the operation unit 206c has a ratio (B / A) between the activation energy initial value A stored in the storage unit 206a and the activation energy B calculated by the calculation unit 206b is higher than a predetermined threshold value. In addition, the pressure adjusting mechanism 202 is operated so that the restraining pressure is increased.

Here, the initial value A of the activation energy of the secondary battery 10 is a value measured after the secondary battery 10 is manufactured and before being shipped from the factory.
A method for measuring the initial value A of the activation energy is determined in advance by a predetermined method. For example, before shipping, discharging is performed under a predetermined condition at a plurality of predetermined temperatures. Then, the voltage change ΔV before and after the discharge is obtained, and the gradient is calculated by linear approximation with the reciprocal of the temperature T (1 / T), and this gradient is used as the activation energy. Here, the temperature T is an absolute temperature.

Here, the discharge conditions are determined for each temperature, for example. The discharge condition is determined so that the discharge current flows in a pulsed manner during a period from a certain time t to a time (t + Δt). At this time, the current value is set to 1 C or less, and Δt is preferably set to 0.001 s (1 ms) or more and 0.1 s (100 ms) or less, for example. The pulse frequency f of the discharge current is f = 1 / Δt.
Here, the pulse frequency may be set to 30 Hz at 10 ° C., 300 Hz at 25 ° C., and 3000 Hz at 40 ° C., for example. In other words, when the temperature is 10 ° C., the pulse frequency f of the discharge current is 30 Hz and Δt is predetermined as 1 / f = (1/30) s. When the temperature is 25 ° C., the pulse frequency f of the discharge current is 300 Hz, and Δt is predetermined as 1 / f = (1/300) s. When the temperature is 40 ° C., the pulse frequency f of the discharge current is 3000 Hz, and Δt is predetermined as 1 / f = (1/3000) s. Thus, the temperature and the pulse frequency f are preferably determined in advance.

  In each period from time t to time (t + Δt), a discharge current is supplied in a pulse shape, and voltage change ΔV is measured before and after that. FIG. 3 is a graph showing a slope as activation energy. Here, since the initial value A of the activation energy is measured before shipment, for example, the secondary battery 10 is discharged in an environment where the temperature is controlled at 10 ° C., 25 ° C., and 40 ° C., respectively, before and after the discharge. It is preferable to measure the voltage change ΔV. The measured voltage change ΔV and the reciprocal (1 / T) of the absolute temperature (T) when the voltage change ΔV was measured in an environment where the temperature was controlled at 10 ° C., 25 ° C., and 40 ° C., respectively. On the basis, as shown in FIG. 3, the slope may be calculated as an initial value A of activation energy by linear approximation.

  The activation energy B of the secondary battery 10 at a predetermined time arbitrarily determined is a value measured after shipment, for example. Here, the discharge condition at the time of measurement is the same as the initial value A of the activation energy at the time of shipment described above, and is 0.001 s (1 ms) or more and 0.1 s (100 ms) or less in advance according to the temperature. A discharge current is made to flow in a pulsed manner for a predetermined period of Δt, and a voltage change ΔV before and after that is acquired. Furthermore, the voltage change ΔV is acquired at a plurality of different temperatures. The activation energy B is calculated based on voltage changes ΔV obtained at a plurality of different temperatures. In this case, when the activation energy B is measured at a low temperature (for example, 0 ° C. or less) after traveling for a short time (for example, within 15 minutes) and when the temperature of the secondary battery 10 is low. Good. At a high temperature (for example, 25 ° C. or higher), the activation energy B may be measured after traveling for a long time (for example, 30 minutes or longer).

  Moreover, the discharge conditions are determined for each temperature, for example. It is difficult to manage the temperature of the secondary battery 10 after shipment. In the calculation of the initial value A of the activation energy, the pulse frequency f is set for temperatures of 10 ° C., 25 ° C., and 40 ° C., and the voltage change ΔV for the temperatures of 10 ° C., 25 ° C., and 40 ° C., respectively. Has been measured. In the calculation of the activation energy B, since temperature management is difficult, the pulse frequency f is preferably set for a larger number of temperatures. At a temperature between the predetermined temperatures of the pulse frequency f, the pulse frequency f with respect to the temperature may be obtained based on the pulse frequency f determined at a temperature adjacent to the temperature. For example, at a temperature between predetermined temperatures, the pulse frequency f may be obtained by an arithmetic average value of the pulse frequency f determined at a temperature adjacent to the temperature.

  When the operation unit 206c has a ratio (B / A) between the activation energy initial value A stored in the storage unit 206a and the activation energy B calculated by the calculation unit 206b is higher than a predetermined threshold value. In addition, the pressure adjusting mechanism 202 is operated so that the restraining pressure is increased. Here, the ratio (B / A) between the initial value A and the activation energy B of the activation energy is also referred to as “activation energy ratio”.

  FIG. 4 is a graph showing the relationship between the restraint load (restraint pressure) and the activation energy. In the graph of FIG. 4, when the activation energy B is 1,1.08 and 1.15, the restraining load is increased by 50%. That is, in the graph of FIG. 5 described later, a restraint load corresponding to the restraint load ratio of 1.5 was applied. The activation energy ratio A before increasing the restraining load is represented by a left bar graph, and the activation energy ratio B after increasing the restraining load is represented by a right bar graph. According to the inventor's knowledge, as shown in FIG. 4, the activation energy decreases as the restraining load increases.

  FIG. 5 is a graph showing the relationship between the constraint load ratio and the activation energy ratio. FIG. 5 shows a graph in which, when the activation energy ratio is 1.08, the activation energy B is measured while increasing the restraining load, and the change in the activation energy ratio is observed. According to the knowledge of the present inventor, as shown in FIG. 5, the activation energy decreases as the restraining load increases. On the other hand, when the restraint load is increased to some extent, the tendency for the activation energy to decrease is slowed down. For example, as shown in FIG. 5, when the restraint load ratio exceeds 1.5, the tendency for the activation energy to decrease with increasing restraint load becomes slow.

  Further, according to the knowledge of the present inventor, when the ratio (B / A) between the initial value A of activation energy and the activation energy B (B / A) is larger than 1.08, deterioration due to cracking of the positive electrode active material particles. Is easy to proceed. For this reason, it is desirable to control the activation energy ratio so as not to be larger than 1.08.

  FIG. 6 is a flowchart of the secondary battery restraint system proposed here. In the form illustrated in the flowchart of FIG. 6, the secondary battery restraint system is applied to an assembled battery used as a power source for a vehicle driving motor mounted on a vehicle.

  In the secondary battery restraint system proposed here, the initial value A of the activation energy of the secondary battery 10 is measured at the time of shipment. And it is preliminarily stored in the storage unit 206a of the secondary battery restraint system. The secondary battery restraint system is activated when the vehicle travels. Then, it detects the state in which the vehicle is traveling (S1) and the end of the traveling of the vehicle (S2).

  After the vehicle travels, the activation energy B is calculated (S3). Next, the ratio (B / A) between the activation energy B and the initial value A of the activation energy is calculated (S4). Next, it is determined whether or not the ratio (B / A) between the activation energy B and the initial value A of the activation energy is larger than a predetermined threshold (S) (S5). When the ratio (B / A) between the activation energy B and the initial value A of the activation energy is larger than a predetermined threshold (S), the restraining pressure is increased (S6). When the ratio (B / A) between the activation energy B and the initial value A of the activation energy is equal to or less than a predetermined threshold (S), the process of increasing the restraint pressure is not performed.

  With this process, the restraint pressure increases when the ratio (B / A) of the activation energy B and the initial value A of the activation energy is larger than a predetermined threshold (S). And the activation energy of the secondary battery 10 incorporated in the assembled battery 100 becomes low. By lowering the activation energy of the secondary battery 10, it is possible to suppress the positive electrode active material particles from being cracked and to suppress the irreversible deterioration of the secondary battery 10.

  As described above, the secondary battery restraint system proposed here has been variously described. However, the embodiments and examples given here do not limit the present invention unless otherwise specified.

  For example, here, a secondary battery incorporated in an assembled battery is illustrated, but the secondary battery can also be applied in the state of a single battery. In the form illustrated in the flowchart of FIG. 6, the secondary battery restraint system is applied to an assembled battery used as a power source for a vehicle driving motor mounted on the vehicle. Unless otherwise stated, the application of the secondary battery restraint system is not limited to an assembled battery used as a power source for a vehicle driving motor mounted on a vehicle.

DESCRIPTION OF SYMBOLS 10 Secondary battery 11 Winding electrode body 12 Battery case 13 Positive electrode terminal 14 Negative electrode terminal 30 Safety valve 32 Injection hole 33 Cap material 50 Positive electrode sheet 51 Positive electrode current collection foil 52 Exposed part 53 Positive electrode active material layer 60 Negative electrode sheet 61 Negative electrode current collection Foil 62 Exposed portion 63 Negative electrode active material layer 72, 74 Separator 80 Electrolytic solution 100 Battery pack 102 Bus bar 120 Power control unit 200 Restraining system 201 Restraining members 201a, 201b End plates 201c, 201d Restraining belt 202 Pressure adjusting mechanism 202a Ball screw mechanism 202b Servo motor 202c1-202c3 Surface pressure sensor 203 Current sensor 204 Voltage sensor 205 Temperature sensor 206 Control device 206a Storage unit 206b Operation unit 206c Operation unit

Claims (1)

A secondary battery having an electrode body including a positive electrode active material layer including positive electrode active material particles made of a composite oxide containing at least Ni, Co, and Mn; and a battery case containing the electrode body;
A restraining member attached to the battery case and restraining the battery case;
A pressure adjusting mechanism that is provided on the restraining member and that regulates the restraining pressure acting on the battery case by the restraining member;
A current sensor for detecting a current flowing in the secondary battery;
A voltage sensor for detecting a voltage applied to the secondary battery;
A control device,
The controller is
A storage unit storing an initial value A of activation energy of the secondary battery;
An arithmetic unit that calculates the activation energy B of the secondary battery at a predetermined time arbitrarily determined based on the current value acquired from the current sensor and the voltage value acquired from the voltage sensor;
When the ratio (B / A) between the activation energy initial value A stored in the storage unit and the activation energy B calculated by the calculation unit is higher than a predetermined threshold, An operation unit for operating the pressure adjusting mechanism so that the restraining pressure is increased,
Secondary battery restraint system.

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