JP2003059474A - Battery pack, battery pack structure, vehicle equipped with battery pack or battery pack structure, and control method of battery pack or battery pack structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery pack capable of bringing the charge/discharge cycle life close to that of a battery pack assembled with cells containing no defects even in the charge/discharge cycle life in the case where defective cells having high internal resistance are mixed or internal resistance is increased caused by mixing of one or more cells whose capacities are early deteriorated. SOLUTION: This battery pack is equipped with a battery line in which x pieces of unit cells of a secondary battery are connected in series; a battery group in which y lines of the battery line are connected in parallel (wherein, x>=1, y>=2); a voltmeter 9 connected to the battery group in parallel and detecting the voltage of the battery group; a measured signal detecting means detecting a measured signal from the voltmeter 9; and a controller 12 connected to the voltmeter 9 and a generator 11, and the voltmeter 9 and a driving motor 10 respectively in series, and the controller 12 judges a charged state of the battery group based on the detected measured signal, and indicates charge/ discharge to the generator 11 and the driving motor 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assembled battery formed by combining a plurality of secondary battery unit cells and a control method thereof, and particularly as a battery for driving a motor of an electric vehicle or the like by combining small secondary batteries. The present invention relates to a publicly usable battery pack and a control method thereof.

[0002]

2. Description of the Related Art In recent years, carbon dioxide emission regulations have been eagerly awaited against the backdrop of increasing environmental protection movements, and in the automobile industry, electric vehicles (EV) are being replaced by vehicles using fossil fuels such as gasoline vehicles. In order to promote the introduction of hybrid vehicles (HEVs) and fuel cell vehicles (FCVs), the development of motor drive batteries that hold the key to their practical use is being eagerly pursued. A rechargeable secondary battery is used for this purpose. For applications that require high output and high energy density, such as EV, HEV, and FCV motor drives, it is practically impossible to make a single large battery, and an assembled battery composed of multiple batteries connected in series can be used. It has been common to use.

However, in this method, it is necessary to make the capacity of the unit battery extremely large, and it is necessary to provide a dedicated production line for production. Also especially large capacity is required
For EV batteries, etc., one battery is very heavy and difficult to handle.

Therefore, it is considered to connect a large number of small batteries, which are easy to handle, for EV, HEV and FCV applications. When using a high-output, high-energy-density lithium-ion secondary battery for charging and discharging as a battery pack for automobiles, use a battery pack in which multiple groups of parallel cells are connected in series, It is designed to get a voltage of 400V. Further, in order to further improve the performance, compactness, and cost reduction of the 12V and 42V batteries for automobiles, it will be promising to use consumer-use lithium ion batteries.

[0005]

However, in such an assembled battery, there is a problem that the discharge capacity and the output are remarkably reduced when the internal resistance of any one or more cells becomes high. To solve this problem, the technique disclosed in Japanese Patent Laid-Open No. 8-241705 does not include the series portion of the unit cells.
By connecting a plurality of parallel-connected sets of single cells in series, we have proposed an assembled battery that is as close as possible to the charge / discharge cycle life of an assembled battery composed of all normal products.

However, when a charge / discharge cycle is performed when cells having a high internal resistance are connected in parallel, there is a difference between a normal product and an SOC (state of charge). The result is shown in FIG. 7. This shows the difference between the SOC of the battery pack with resistance and that of the battery pack without resistance after performing 10 cycles of 1.2A discharge-charge every 6 minutes. After 120 minutes, the value of △ SOC takes a negative value. There is. That is, it can be seen that the SOC of the assembled battery with a resistor is lowered. When SOC is lowered, deterioration of the entire battery pack is promoted and output is lowered.

The present invention has been made in view of the above-mentioned problems, and its purpose is to introduce an abnormal product such as high internal resistance into a battery pack or to deteriorate one or more cells. The battery pack, battery pack structure, and battery pack that can approach the charge / discharge cycle life of the battery pack consisting of 100% normal products even if the charge / discharge cycle life is high when the internal resistance becomes high. Another object of the present invention is to provide a vehicle equipped with an assembled battery structure and a method for controlling the assembled battery or the assembled battery structure.

[0008]

In order to achieve the above object, in the invention according to claim 1, a battery array in which x secondary battery cells are connected in series, and the battery array is connected in y array in parallel. A battery group (where x ≧ 1, y ≧ 2), a voltage detection unit that is connected in parallel with the battery group and that detects the voltage of the battery group, and a measurement that detects a measurement signal from the voltage detection unit. A signal detection unit, the voltage detection unit and the power generation unit, and the voltage detection unit and the discharge unit are respectively connected in series, the state of charge of the battery group is determined by the detected measurement signal, and the power generation unit and the discharge unit. And a charging / discharging control unit for instructing charging / discharging.

As a preferable control method thereof, the capacity C (Ah) and the voltage value V at the initial discharge of the secondary battery cell to be used are
In the relationship of (V) (C> 0, V> 0), (the absolute value of the slope of the tangent line of the voltage V with respect to the capacity C) ≧ 0.55 is satisfied, and the voltage value that can be charged / discharged by 2% or more of the initial capacity is centered It is preferable to carry out charge / discharge, and as another control method, a voltage value satisfying (absolute value of average change rate of voltage value V with respect to capacity C) ≧ 0.55 and capable of being charged / discharged by 2% or more of initial capacity Charge and discharge may be performed mainly. Incidentally, the secondary battery herein includes such 12V and 42V batteries for automobiles and refers to such a chargeable and dischargeable battery.

[0010]

According to the present invention, even if the assembled battery includes a battery having a high internal resistance, or even if the deterioration of a specific battery has progressed, all the products are configured as normal products. A charge / discharge cycle life approaching that of an assembled battery can be obtained. Further, since the charge state of the assembled battery is judged from the voltage to perform charging / discharging, the load on the battery is less, heat generation is suppressed and cycle life characteristics can be improved as compared with the case of judging directly from the battery. Furthermore, this battery pack is connected and installed in series and / or parallel as a sub-module,
Furthermore, since each of the sub-modules can be attached and removed, the output etc. can be designed according to the required characteristics and specifications.
By using as a power source for an electric vehicle, a hybrid vehicle, a fuel cell vehicle, or as a 12V, 42V battery for a vehicle, a highly reliable electric vehicle, hybrid vehicle, fuel cell vehicle, or general vehicle can be provided.

[0011]

1 is a schematic view showing a sub-module structure used in this embodiment. By connecting and installing the present assembled battery as a sub-module in series and / or parallel, and further, the sub-modules can be attached and detached, the output and the like can be designed according to required characteristics and specifications.

The assembled battery of the embodiment is a battery having a high internal resistance while realizing a large output and a large capacity by connecting a plurality of secondary battery cells connected in series in parallel to each other in a battery row. Even when the content of the battery is included or when the deterioration of a specific battery has progressed, a sufficient charge / discharge cycle life can be obtained. Further, since the charge state of the assembled battery is judged from the voltage to perform charging / discharging, the load on the battery is less, heat generation is suppressed, and cycle life characteristics can be improved as compared with the case of judging directly from the battery.

FIG. 2 shows an example in which the assembled battery of the embodiment is mounted on the HEV. Particularly, it can be suitably used as an assembled battery for HEV / FCV, which requires a large capacity and a large output and is repeatedly charged and discharged, and a 12V / 42V battery for automobiles.

(Embodiment) The embodiment of the assembled battery of the present invention will be described below based on an embodiment, but the present invention is not limited to the embodiment.

FIG. 3 shows an assembled battery in which two lithium ion secondary batteries are connected in series and the groups are connected in three parallels. 1 to 6 are lithium ion secondary batteries, 7 is a positive electrode, and 8 is a negative electrode. The assembled battery may have a configuration of a combination of m series and n parallel (m ≧ 1, n ≧ 2).

In the examples, 1 to 5 are normal batteries, and 6 is a battery having double the internal resistance of the normal product. A lithium ion secondary battery was used as the battery. The positive electrode is basically LiMn ₂ O ₄
However, it may be a Li-deficient type or a Li-excess type. Further, part of Mn may be replaced with a metal element composed of at least one selected from transition metal elements other than Mn and other metal elements. Further, it may be an O-deficient type or an O-excessive type. Further, part of O may be replaced with at least one element selected from elements such as S, F and Cl.

As the negative electrode, any of the materials used in ordinary non-aqueous electrolyte secondary batteries can be used.
Lithium-based metals such as metallic lithium and lithium alloys, SnSi
A metal oxide such as O ₃ or the like, a metal nitride such as LiCoN ₂ or a carbon material can be used. In the present invention,
Carbon materials such as coke, natural graphite, artificial graphite and non-graphitizable carbon can be preferably used.

As the electrolytic solution, various lithium salts as electrolytes, which are dissolved in a non-aqueous solvent such as an organic solvent, can be used. In this case, the electrolyte is LiClO ₄ , LiAs
Known examples include F ₆ , LiPF ₆ , LiBF ₆ , LiCF ₃ SO ₃ , and Li (CF ₃ SO ₂ ) ₂ N. The organic solvent is not particularly limited, but examples thereof include carbonates, lactones, ethers, and the like, for example, ethylene carbonate, propylene carbonate, diethyl carbonate,
Dimethyl carbonate, methyl ethyl carbonate, 1,
Solvents such as 2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 1,3-dioxolane and γ-butyrolactone may be used alone or in admixture of two or more. The concentration of the electrolyte dissolved in these non-aqueous solvent or organic solvent is preferably 0.5 to 2.0 mol / liter.

Further, in the lithium secondary battery of this embodiment, it is possible to use an electrolytic medium other than the above-mentioned electrolytic solution, for example, a solid or viscous material in which the above-mentioned electrolyte is uniformly dispersed in a polymer matrix. A body or a body obtained by impregnating these with a non-aqueous solvent can also be used. In this case, as the polymer matrix, for example, polyethylene oxide, polypropylene oxide, polyacrylonitrile, polyvinylidene fluoride or the like can be used.

Further, in the lithium secondary battery of this embodiment, a separator for preventing short circuit between the positive electrode and the negative electrode can be provided. As such a separator, a porous sheet of a polymeric material such as polyethylene and cellulose, or a non-woven fabric is used.

(Embodiment 1) Embodiment 1 has the structure of the assembled battery shown in FIG. 3, in which only the battery of 6 has an internal resistance that is twice that of the other batteries. The negative electrode of the constructed battery is graphite. Charging / discharging was performed at a low current of 3 A for 6 minutes each. The center voltage for charging / discharging is the average change rate absolute value of the voltage value V with respect to the capacity C =
2000 cycles were performed at 7.2V which is 0.55. After 2000 cycles, the open-circuit voltage of the assembled battery is 7.12V, the internal resistance is 1.02 of the initial value.
The discharge capacity retention rate was 92% of the initial discharge capacity.

(Embodiment 2) In the embodiment 2, the battery pack of FIG. 3 has a structure in which only the battery 6 has an internal resistance twice as high as that of the other batteries. The negative electrode of the constructed battery is hard carbon. Charging / discharging was carried out at a low current for 3 minutes each for 3 A. The center voltage for charging / discharging is the average change rate absolute value of the voltage value V with respect to the capacity C =
2000 cycles were performed at 7.6V which is 1. After 2000 cycles,
The open-circuit voltage of the assembled battery is 7.58V, the internal resistance is 1.01 times the initial value,
The discharge capacity retention rate was 93% of the initial discharge capacity.

(Comparative Example 1) In Comparative Example 1, the assembled battery shown in FIG. 3 is composed of all normal products. The negative electrode of the constructed battery is hard carbon. Charge and discharge are low current 3A, 6 each
It was carried out for a minute. The center voltage for charging / discharging is 2000 at 7.6V, which is (average absolute change rate of voltage value V with respect to capacity C) = 1.
Went cycle. After 2000 cycles, the open circuit voltage of the battery pack is
The internal resistance was 7.6 V, 1.002 times the initial value, and the discharge capacity retention rate was 98% of the initial discharge capacity.

COMPARATIVE EXAMPLE 2 Comparative example 2 has the structure of the assembled battery shown in FIG. 3, in which only the battery No. 6 has an internal resistance that is twice that of the other batteries. The negative electrode of the constructed battery is graphite. Charging / discharging was performed at a low current of 3 A for 6 minutes each. The central voltage for charging / discharging is (absolute value of average change rate of voltage value V with respect to capacity C).
2000 cycles were performed at 7.6V = 0.5. After 2000 cycles, the open circuit voltage was 6.4 V, the internal resistance was 2.02 times the initial value, and the discharge capacity retention rate was 55% of the initial discharge capacity.

[Table 1] (Embodiment 3) Embodiment 3 has the structure of the assembled battery shown in FIG. 3, in which only the battery 6 has an internal resistance twice that of the other batteries. The negative electrode of the constructed battery is graphite. Charging / discharging was performed at a high current of 30 A for 1 minute each. The center voltage for charging / discharging is the average absolute change rate of the voltage value V with respect to the capacity C = 0.55.
2000 cycles were performed at 7.2V. After 2000 cycles, the open circuit voltage of the assembled battery was 7.09 V, the internal resistance was 1.05 times the initial value, and the discharge capacity retention rate was 90% of the initial discharge capacity.

(Embodiment 4) Embodiment 4 has a structure of the assembled battery of FIG. 3, in which only the battery 6 has an internal resistance twice as high as that of the other batteries. The negative electrode of the constructed battery is hard carbon. Charging / discharging was performed at a high current of 30 A for 1 minute each. The center voltage for charging / discharging was 2000 cycles at 7.6 V where the absolute value of the average change rate of the voltage value V with respect to the capacity C was 1. After 2000 cycles, the open-circuit voltage of the battery pack is 7.50V and the internal resistance is 1.04 of the initial value.
The discharge capacity retention rate was 91% of the initial discharge capacity.

(Comparative Example 3) In Comparative Example 3, the assembled battery shown in FIG. 3 is composed of all normal products. The negative electrode of the constructed battery is hard carbon. Charge and discharge are high current 30A, 1 each
It was carried out for a minute. The center voltage for charging / discharging is 2000 at 7.6V, which is (average absolute change rate of voltage value V with respect to capacity C) = 1.
Went cycle. After 2000 cycles, the open circuit voltage of the battery pack is
The value was 7.58V, the internal resistance was 1.01 times the initial value, and the discharge capacity retention rate was 97% of the initial discharge capacity.

(Comparative Example 4) Comparative Example 4 has the structure of the assembled battery of FIG. 3, in which only the battery No. 6 has an internal resistance that is twice that of the other batteries. The negative electrode of the constructed battery is graphite. Charging / discharging was performed at a high current of 30 A for 1 minute each. The center voltage for charging / discharging is the average change rate absolute value of the voltage value V with respect to the capacity C =
2000 cycles were performed at 7.6V which is 0.5. After 2000 cycles, the open-circuit voltage was 6.2 V, the internal resistance was 2.52 times the initial value, and the discharge capacity retention rate was 45% of the initial discharge capacity.

[Table 2] Incidentally, in Examples 1 to 4 and Comparative Examples 1 to 4, the charging / discharging cycle was carried out according to the flowchart shown in FIG. As can be seen from Tables 1 and 2, the capacity C is irrespective of the magnitude of the discharge current.
It can be seen that the charge / discharge cycle characteristics of the assembled battery of all normal products are approached by carrying out the charge / discharge cycle test at a voltage in which the absolute value of the average change rate of the voltage value V is 0.55 or more. The reason for this is that when there is a difference between the SOC of a battery with high internal resistance and the SOC of a normal battery, the voltage difference between them tends to eliminate SOC. However, outside this range, there is no voltage difference even if there is a difference in SOC, so it is considered that charging / discharging is performed with a difference in SOC and the battery pack deteriorates.

(Embodiment 5) Embodiment 5 has the structure of the assembled battery shown in FIG. 3, and the internal resistance of only the battery of 6 is twice that of the other batteries. The negative electrode of the constructed battery is graphite. Charge and discharge are low current 3A, 6 minutes each. The central voltage for charging and discharging is
2000 cycles were performed at 7.15V where the absolute value of the slope of the tangent to the voltage V with respect to the capacitance C was 0.56. After 2000 cycles, the open circuit voltage of the assembled battery was 7.12 V, the internal resistance was 1.02 times the initial value, and the discharge capacity retention rate was 91% of the initial discharge capacity.

(Embodiment 6) Embodiment 6 has the structure of the assembled battery shown in FIG. 3, and the internal resistance of only the battery 6 is twice that of the other batteries. The negative electrode of the constructed battery is hard carbon. Charge and discharge are low current 3A, 6 minutes each. The center voltage for charging / discharging was 20008 cycles at 7.58 V where the absolute value of the tangent slope of the voltage V with respect to the capacity C = 1. After 2000 cycles, the open circuit voltage of the assembled battery was 7.55 V, the internal resistance was 1.01 times the initial value, and the discharge capacity retention rate was 92% of the initial discharge capacity.

(Comparative Example 5) In Comparative Example 5, the assembled battery shown in FIG. 3 is composed of all normal products. The negative electrode of the constructed battery is hard carbon. Charge and discharge are low current 3A, 6 each
Minutes. The central voltage for charging / discharging is the voltage V with respect to the capacity C.
2000 cycles were carried out at 7.58 V where the absolute value of the slope of the tangent of = 0.99. After 2000 cycles, the open circuit voltage of the battery pack is 7.57
V, the internal resistance was 1.003 times the initial value, and the discharge capacity retention rate was 98% of the initial discharge capacity.

(Comparative Example 6) Comparative Example 6 has the structure of the assembled battery shown in FIG. 3, and the internal resistance of only the battery 6 is twice that of the other batteries. The negative electrode of the constructed battery is graphite. Charge and discharge are low current 3A, 6 minutes each. The central voltage for charging and discharging is
2000 cycles were performed at 7.61 V where the absolute value of the tangent of the voltage V with respect to the capacitance C was 0.51. After 2000 cycles, the open circuit voltage was 6.41 V, the internal resistance was 2.04 times the initial value, and the discharge capacity retention rate was 53% of the initial discharge capacity.

[Table 3] (Embodiment 7) Embodiment 7 has the structure of the assembled battery shown in FIG. 3, in which only battery No. 6 has an internal resistance double that of other batteries. The negative electrode of the constructed battery is graphite. Charge and discharge are low current 30A, 1 minute each. The central voltage for charging / discharging is 7.19V, which is the absolute value of the tangent slope of the voltage V with respect to the capacitance C = 0.55, which is 2
000 cycles were performed. After 2000 cycles, the open circuit voltage of the assembled battery was 7.1910 V, the internal resistance was 1.04 times the initial value, and the discharge capacity retention rate was 92% of the initial discharge capacity.

(Embodiment 8) Embodiment 8 has the structure of the assembled battery shown in FIG. 3, and the internal resistance of only the battery of 6 is twice that of the other batteries. The negative electrode of the constructed battery is hard carbon. Charge and discharge are low current 30A, 1 minute each. The central voltage for charging / discharging is the absolute value of the tangent slope of the voltage V with respect to the capacity C = 1.05.
2000 cycles at 7.61V. After 2000 cycles,
The open-circuit voltage of the assembled battery is 7.52V, the internal resistance is 1.02 times the initial value,
The discharge capacity retention rate was 93% of the initial discharge capacity.

(Comparative Example 7) Comparative Example 7 has the structure of the assembled battery shown in FIG. The negative electrode of the constructed battery is hard carbon. Charge and discharge are low current 30A, 1 each
Minutes. The central voltage for charging / discharging is (voltage V
2000 cycles were carried out at 7.6 V, which is the absolute value of the tangent line slope of 1. After 2000 cycles, the open-circuit voltage of the assembled battery is 7.57V,
The internal resistance was 1.03 times the initial value, and the discharge capacity retention rate was 96% of the initial discharge capacity.

(Comparative Example 8) Comparative Example 8 has the structure of the assembled battery shown in FIG. 3, and the internal resistance of only the battery of 6 is twice that of the other batteries. The negative electrode of the constructed battery is graphite. Charge and discharge are low current 30A, 1 minute each. The central voltage for charging and discharging is
2000 cycles were performed at 7.6 V where the absolute value of the tangent slope of the voltage V with respect to the capacitance C was 0.51. After 2000 cycles, the open-circuit voltage was 6.3 V, the internal resistance was 2.50 times the initial value, and the discharge capacity retention rate was 48% of the initial discharge capacity.

[Table 4] Incidentally, in Examples 5 to 8 and Comparative Examples 5 to 8, the charge and discharge cycle was carried out according to the flowchart shown in FIG. As can be seen from Tables 3 and 4, regardless of the magnitude of the discharge current, the charge / discharge cycle test was performed at a voltage where the absolute value of the tangent slope of the voltage V with respect to the capacity C was ≧ 0.55. It can be seen that the charge and discharge cycle characteristics of the assembled battery are approaching. The reason for this is that when the absolute value of the tangent slope of the voltage V with respect to the capacity C is ≧ 0.55 and there is a difference in SOC between the battery with a high internal resistance and a normal battery, the SOC is eliminated by the voltage difference between them. Head to. However, when the absolute value of the tangent slope of the voltage V with respect to the capacity C is <0.55, there is no voltage difference even if there is a difference in SOC. Therefore, it is considered that charging / discharging is performed with the difference in SOC and the assembled battery deteriorates.

FIG. 6 illustrates a control method using HEV or FCV as an example. FIG. 3 shows an assembled battery in which two groups are connected in series and three groups are connected in parallel, but a combination of m series and n parallel (m is 1 or more, n is 2 or more) is also possible. . Reference numeral 9 is a voltmeter for measuring the total voltage of the assembled battery, 10 is a driving motor, 11 is a generator, for example, an alternator or a fuel cell, and 12 is a negative electrode 8 and a controller.

When the voltage deviates from the absolute value ≧ 0.55 of the average change rate of the voltage value V with respect to the capacity C or from the absolute value ≧ 0.55 of the tangent slope of the voltage value V with respect to the capacity C, the assembled battery is Since the voltage is basically higher than the proper voltage, the controller 12 operates to discharge the assembled battery. Then, when the voltage returns to an appropriate level, charging and discharging are repeated. This makes it possible to provide a highly reliable HEV or FCV.

[0037]

As described above, by using the present invention, even if the assembled battery has a high internal resistance or a specific battery is deteriorated, all the assembled products are normal products. A charge / discharge cycle life close to that of a battery can be obtained. Further, this battery pack provides a highly reliable electric vehicle, hybrid vehicle, fuel cell vehicle, and general vehicle by being used as a power source for an electric vehicle, a hybrid vehicle, a fuel cell vehicle, or as a 12V, 42V battery for an automobile. it can.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an assembled battery structure according to an embodiment.

FIG. 2 is a schematic diagram showing a hybrid vehicle equipped with the assembled battery of the embodiment.

FIG. 3 is a schematic diagram showing an assembled battery of an example.

FIG. 4 is a flowchart showing charge / discharge control used in charge / discharge experiments of Examples 1 to 4 and Comparative examples 1 to 4.

FIG. 5 is a flowchart showing charge / discharge control used in charge / discharge experiments of Examples 5-8 and Comparative examples 5-8.

FIG. 6 is a system diagram when the assembled battery of the embodiment is applied to HEV or FCV.

FIG. 7 is a diagram showing changes in SOC difference when a charge / discharge cycle test is performed when two batteries having a difference in internal resistance are arranged in parallel.

[Explanation of symbols]

1-6 Lithium ion secondary battery 7 Positive electrode 8 Negative electrode 9 Voltmeter 10 Drive motor 11 generator 12 Controller 13 Sub-module structure 14 batteries 15 connection terminals 16 cases 17 hybrid cars 18 engine 19 batteries

Continued front page    F term (reference) 5H029 AJ05 AJ14 AK03 AL01 AL02                       AL06 AL07 AL12 AM03 AM04                       AM05 AM07 AM16 BJ23 HJ18                       HJ19                 5H030 AA09 AS08 BB00 BB10 DD01                       DD08 DD20 FF41                 5H040 AA03 AA06 AS07 AY02 AY06                       DD05 NN05                 5H115 PA08 PA11 PA15 PG04 PI16                       PO02 PO17 PU01 PU21 SE06                       TI01 TI05 TR19 TU04 TU16                       TU17 UI35

Claims (6)

[Claims] 1. A battery array in which x secondary battery cells are connected in series, and a battery group in which the battery arrays are connected in y rows (where x ≧ 1, y
≧ 2), a voltage detection unit that is connected in parallel with the battery group and that detects the voltage of the battery group, a measurement signal detection unit that detects the measurement signal from the voltage detection unit, the voltage detection unit and the power generation unit. Unit, and the voltage detection unit and the discharge unit are respectively connected in series, the state of charge of the battery group is determined by the detected measurement signal, the power generation unit, the charge and discharge control unit for instructing the discharge unit charging and discharging, An assembled battery characterized by having. 2. An assembled battery structure comprising the assembled battery according to claim 1 as a sub-module, and the sub-modules being connected in series and / or in parallel. 3. The assembled battery structure according to claim 2, wherein each of the sub-modules is removable. 4. An electric vehicle, a hybrid vehicle, or a fuel cell vehicle, wherein each vehicle is a vehicle including the assembled battery or the assembled battery structure according to any one of claims 1 to 3. A vehicle including an assembled battery or an assembled battery structure. 5. The method for controlling the assembled battery or assembled battery structure according to claim 1, wherein the secondary battery cell used has a capacity C (Ah) and a voltage at initial discharge. In the relationship of the value V (V) (C> 0, V> 0), the absolute value of the slope of the tangent line of the voltage V to the capacity C ≧ 0.55 is satisfied, and the voltage value that can be charged / discharged by 2% or more of the initial capacity is A method of controlling an assembled battery or an assembled battery structure, which is characterized in that charge and discharge are performed mainly. 6. A method for controlling an assembled battery or an assembled battery structure according to claim 1, wherein the secondary battery cell to be used has a capacity C (Ah) and a voltage at initial discharge. In the relationship of the value V (V) (C> 0, V> 0), the absolute value of the average change rate ≧ 0.55 of the voltage value V with respect to the capacity C is satisfied, and the voltage value capable of charging and discharging 2% or more of the initial capacity is A method of controlling an assembled battery or an assembled battery structure, which is characterized in that charge and discharge are performed mainly.