KR101608125B1 - Secondary battery system and control apparatus for secondary battery - Google Patents

Abstract

Disclosure of the Invention A problem to be solved by the present invention is to provide a secondary battery system which prevents lithium precipitation in the negative electrode and thereby prevents reduction in energy density.
A temperature sensor 4 for measuring the temperature of the secondary battery 2 and a secondary battery 3 for measuring the temperature of the secondary battery 2 when the temperature of the secondary battery 2 measured by the temperature sensor 4 rises And the control unit 7 controls the voltage of the secondary battery 2 to be less than the upper limit voltage. The control unit 7 controls the secondary battery 2 so that the value of the negative electrode capacity / (2), and controls the voltage of the secondary battery (2) to be less than the upper limit voltage based on the corresponding information.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a secondary battery system,

The present invention relates to a secondary battery system and a secondary battery control device, and more particularly, to a secondary battery system using a lithium ion secondary battery and a secondary battery control device charging the lithium ion secondary battery.

Recently, a lithium ion secondary battery has been used as a motor drive battery for an electric vehicle (EV) or a hybrid electric vehicle (HEV).

In the lithium ion secondary battery, there is a technique of using a ternary positive electrode active material (for example, NCM (Li [NiMnCo] O ₂ ) or NCA (Li [NiAlCo] O ₂ ) Various developments have been made to improve the characteristics.

As one of the problems of the secondary battery using the ternary positive electrode active material, metal ions may be reduced to the negative electrode and precipitated. In order to prevent metal precipitation in the negative electrode, at least one of 0.5 to 5 wt% of succinonitrile, 1 to 10 wt% of halogenated ethylene carbonate, and 1 to 5 wt% of vinylethylene carbonate as an additive is added to the electrolyte solution (Patent Document 1). According to this technique, succinonitrile is added to an electrolytic solution, and succinonitrile captures metal ions such as nickel (Ni) and manganese (Mn) dissolved in an electrolytic solution to inhibit metal precipitation in the negative electrode . In addition, it is supposed to add a sufficient amount of succinonitrile to capture the metal ion (see paragraph 0014 of patent document 1 in particular).

Japanese Patent Application Laid-Open No. 2010-15968

However, the succinonitrile added as an additive in the prior art only captures the metal ions of Ni and Mn by inhibiting dissolution of Ni and Mn into the electrolytic solution. For this reason, the prior art does not consider suppressing precipitation of lithium (Li) ions in the negative electrode. As a result, in the prior art, lithium is still deposited in the negative electrode or captured in the additive, so that the amount of lithium ions acting in the electrolyte is reduced, which may lower the energy density.

Accordingly, an object of the present invention is to provide a secondary battery system and a secondary battery control device in which lithium precipitation in a negative electrode is suppressed in a lithium ion secondary battery so that the energy density is not lowered.

As a result of intensive studies, the inventors of the present invention have found that there is a tendency that, when the temperature rises, the ternary positive electrode active material increases in charge capacity due to the occurrence of some phase transition thereon. In view of this phenomenon, in a lithium ion secondary battery which is designed using capacities of a positive electrode and a negative electrode which are normally obtained at room temperature, the AC balance (AC balance = (obtained from the negative electrode active material layer opposed to the positive electrode active material layer (The total value of the capacitance obtained from the positive electrode active material layer opposed to the negative electrode active material layer)] is collapsed, and when it becomes too small, lithium is precipitated on the negative electrode.

That is, in order to accomplish the above object, the present invention provides a secondary battery system that includes a secondary battery and charges the secondary battery. This secondary battery system includes a temperature sensor for measuring the temperature of the secondary battery and a temperature sensor for measuring the temperature of the secondary battery when the temperature of the secondary battery is measured by the temperature sensor As shown in FIG. The control unit stores corresponding information composed of the temperature of the secondary battery and the upper limit voltage for setting the value of the negative electrode capacity / positive electrode capacity to a value larger than 1. Based on the corresponding information, the voltage of the secondary battery is set to the upper limit Voltage.

In order to achieve the above object, the present invention is a secondary battery control device for charging a secondary battery. The secondary battery control device includes a secondary battery holder for setting a lithium ion secondary battery to be charged. A temperature sensor for measuring the temperature of the secondary battery set in the holder; and a temperature sensor for measuring the temperature of the secondary battery when the temperature of the secondary battery is measured by the temperature sensor. And a controller. The control unit stores corresponding information composed of the temperature of the secondary battery and the upper limit voltage for setting the value of the negative electrode capacity / positive electrode capacity to a value larger than 1. Based on the corresponding information, the voltage of the secondary battery is set to the upper limit Voltage.

According to the present invention, by setting and charging the upper limit voltage corresponding to the temperature of the secondary battery, it is possible to control the AC balance to be always constant, to prevent lithium precipitation in the negative electrode of the lithium ion secondary battery, Can be prevented.

1 is a block diagram for explaining a configuration of a secondary battery system according to the first embodiment.
2 is a flowchart showing a control procedure at the time of charging.
3 is a schematic graph showing the temperature dependency of the positive electrode capacity by the positive electrode active material other than the ternary positive electrode active material and the ternary negative electrode active material.
4 is a schematic cross-sectional view for explaining the overall structure of a lithium ion secondary battery of a lamination type in a non-bipolar manner.
5 is a schematic cross-sectional view for explaining the overall structure of a bipolar type stacked lithium ion secondary battery.
Fig. 6 is a perspective view showing the external appearance of the stacked lithium ion secondary battery shown in Fig. 4 or Fig. 5. Fig.
7 is a block diagram showing the configuration of a secondary battery control apparatus according to the second embodiment.

Hereinafter, a lithium ion secondary battery according to an embodiment to which the present invention is applied will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant explanations are omitted. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may differ from the actual ratios.

[First Embodiment]

[Secondary Battery System]

1 is a block diagram for explaining a configuration of a secondary battery system according to the first embodiment.

This secondary battery system 1 is provided with a lithium ion secondary battery (referred to as a secondary battery 2). A voltage sensor 3 for measuring the voltage between the positive and negative electrodes of the secondary battery 2, a temperature sensor 4 for measuring the temperature of the secondary battery 2, a voltage / current adjusting unit 5 for supplying charging power, A current sensor 6 for measuring a current value supplied to the secondary battery 2, and a control unit 7 for controlling voltage and current at the time of charging.

Details of each part will be described below.

The secondary battery 2 is similar to a conventional lithium ion secondary battery and is arranged such that the positive electrode including the positive electrode active material and the negative electrode including the negative electrode active material face each other with the separator interposed therebetween and the separator is filled with the electrolyte . Details of the lithium ion secondary battery will be described later.

The voltage sensor 3 measures a voltage between a positive electrode and a negative electrode of the secondary battery 2, for example, a voltmeter is preferable. The mounting position of the voltage sensor 3 is not particularly limited and may be a position at which the voltage between the positive electrode and the negative electrode can be measured in the circuit connected to the secondary battery 2. [

The temperature sensor (4) measures the temperature of the secondary battery (2). The temperature sensor 4 is attached to the outer surface of the secondary battery 2 or the like (see FIG. 6 to be described later).

The voltage / current adjustment unit 5 adjusts voltage and current based on a command from the control unit 7 to supply power from the external power source (not shown) to the secondary battery 2. For example, when the external power source is an AC power source, the voltage / current regulator 5 converts AC into DC, and then supplies voltage and current to the secondary battery 2. In addition, when the external power source is a direct current power source, for example, the direct current voltage and current from the outside are adjusted and supplied to the secondary battery 2.

The current sensor 6 is, for example, an ammeter and measures a current value of electric power supplied from the voltage / current regulator 5 to the secondary battery 2 at the time of charging. The position where the current sensor 6 is attached is not particularly limited and may be a position in the circuit for supplying electric power to the secondary battery 2 from the voltage / current regulating section 5, do.

The control unit 7 is, for example, a microchip type processor, and includes a CPU, a memory (storage device), and the like. The control unit 7 controls the voltage and current supplied to the secondary battery 2 at the time of charging according to a procedure to be described later. The memory is preferably a nonvolatile memory, and is a table of correspondence between the temperature and the upper limit voltage that defines the relationship between the temperature of the secondary battery 2 at the time of charging and the upper limit voltage in the secondary battery 2 Information).

The control procedure at the time of charging in the thus constituted secondary battery system will be described.

Fig. 2 is a flowchart showing a control procedure at the time of charging, and is a process performed by the control unit 7 unless otherwise noted.

This control at the time of charging is performed in a state where the secondary battery system 1 is connected to an external power source (not shown) with respect to the secondary battery 2, and charging power is supplied to the secondary battery 2 All. This control is exemplified by the charging by the constant current constant voltage charging method.

First, the control unit 7 acquires the current temperature of the secondary battery 2 from the temperature sensor 4 (S1).

Subsequently, the control unit 7 determines whether or not the obtained current temperature is lower than the threshold temperature (S2). If the obtained temperature is not lower than the threshold temperature (S2: " (S11). After that, the process returns to S1 to acquire the current temperature, and continues power cut from the external power source until the current temperature falls. When the temperature returns to S1, the process after S3 is continued.

Here, the critical temperature is a temperature at which the temperature of the secondary battery 2 becomes excessively high enough not to be suitable for charging. For example, in a lithium ion secondary battery, a temperature of about 60 deg. C is used as a critical temperature in most cases. This limit temperature can be appropriately set depending on the performance of the secondary battery 2 or the like. In S11, the reason why the power supply from the external power source to the voltage / current regulating unit 5 is cut off is that the limit temperature has been exceeded because there is a possibility that something is wrong. In order to reliably cut off the power supplied to the secondary battery 2 to be.

The secondary battery system 1 may be previously provided with a display device (for example, an indicator lamp or the like indicating a state of being charged, completed, or not being able to be charged) beforehand. For example, when the power from the external power source is cut off by S11, it may be displayed that the display device is not chargeable. In addition, the external power supply such as S11 is disconnected by the control unit 7, and a mechanism for interrupting the current flow by a temperature such as a separate thermal fuse or the like is attached to the wiring of the charging system of the secondary battery 2 And when the temperature reaches the limit temperature, the power from the outside may be cut off.

On the other hand, in S2, if the temperature is lower than the threshold temperature (S2: YES), the upper limit voltage corresponding to the acquired current temperature is obtained (S3) by referring to the stored temperature vs. upper limit voltage correspondence table (described later in detail). The relationship between this temperature and the upper limit voltage is a temperature and an upper limit voltage so that a predetermined AC balance (AC balance = (negative electrode capacity / positive electrode capacity)) is greater than 1. Lithium precipitation in the negative electrode can be prevented by using the relationship between the temperature and the upper limit voltage for achieving AC balance (details will be described later).

Subsequently, the control unit 7 acquires the current voltage of the secondary battery 2 from the voltage sensor 3 (S4).

Subsequently, the control unit 7 compares the obtained current voltage of the secondary battery 2 with the upper limit voltage acquired in S3 (S5). Here, if the current voltage is lower than the upper limit voltage (S5: YES), the voltage and current regulation unit 5 supplies power for charging by the predetermined constant current to the secondary battery 2 (S6). When the first S6 is reached in this control sequence, the constant current mode starts charging the secondary battery 2 from the voltage / current regulator 5 as a constant current mode. If the process proceeds to S6 during the continuation of charging, the charging in the constant current mode by the constant current supply from the voltage / current regulating unit 5 to the secondary battery 2 continues. After S6, the process returns to S1 and continues the process.

As described above, in this control procedure, since the charging is always returned to S1, the current temperature is always acquired again during charging. When the temperature rises during charging, charging by the upper limit voltage corresponding to the increased temperature .

On the other hand, in S5, if the current voltage is not lower than the upper limit voltage (S5: "NO"), the process proceeds to S7 to charge by the constant voltage mode.

In S7, the control unit 7 starts charging from the voltage / current regulating unit 5 with a constant voltage equal to the upper limit voltage extracted in S3 (S7). Therefore, after this step, the voltage of the secondary battery 2 is not higher than the upper limit voltage corresponding to the current temperature at that time.

The control unit 7 obtains the current value from the current sensor 6 in step S8 and determines whether the current value is less than the termination current in step S9. If the current value is not less than the termination current value in step S9, "), The process returns to S1 and processing continues. When the temperature of the secondary battery 2 is lowered during charging by returning to S1 and obtaining the current temperature again, the upper limit voltage at that temperature is acquired again in S3, and until the upper limit voltage is obtained Charging is performed in the constant current mode (S4, S5: YES, S6).

On the other hand, if the present current value is less than the termination current value (S9: YES) in S9, the power supply from the voltage / current regulator 5 to the secondary battery 2 is stopped Lt; / RTI >

By the above procedure, charging is performed so that the current voltage obtained in S4 is less than the upper limit voltage corresponding to the current temperature acquired in S3.

The above-described control procedure at the time of charging is based on the constant-current constant-voltage charging method. Alternatively, for example, a constant-current method may be used. In this case, if the present voltage is not lower than the upper limit voltage in S5 of the above procedure (S5: "NO"), that is, if the current voltage is higher than the upper limit voltage, do. Even in this manner, the battery can be charged so as to have a voltage lower than the upper limit voltage corresponding to the current temperature. The same applies to other charging methods, and the secondary battery 2 may be charged such that the voltage of the secondary battery 2 is lower than the upper limit voltage corresponding to the current temperature.

Next, the relationship between the temperature and the upper limit voltage of the secondary battery 2 will be described.

3 is a graph showing the temperature dependency of the positive electrode capacity by the positive electrode active material other than the ternary positive electrode active material and the ternary negative electrode (the median value is taken as room temperature (25 占 폚)).

Here, Li (Ni, Co, Al) O ₂ (indicated by a circle) and Li (Ni, Co, Mn) O ₂ (indicated by a diamond pattern) are exemplified as a ternary positive electrode active material. On the other hand, LiMn ₂ O ₄ (lithium manganese oxide) (triangular notation) is shown as a positive electrode active material other than a ternary system.

As shown in Fig. 3, in LiMn ₂ O ₄ (triangular display), there is no change in the rate of change in capacity with respect to temperature change, and it is found that there is no temperature dependency. That is, LiMn ₂ O ₄ has no temperature dependency, while the energy density is low. In such a positive electrode active material, there is not a large nonuniformity in battery characteristics in a hydrothermal state due to heat generation.

On the other hand, in the case of Li (Ni, Co, Al) O ₂ (circled) and Li (Ni, Co, Mn) O ₂ The change (increase or decrease) of the increase / decrease rate is in direct proportion. As a result, it can be seen that there is a large nonuniformity in the battery characteristics in a hydrothermal state due to heat generation during charging and discharging. The positive electrode active material having such a temperature dependency has a layered rock salt type which is a hexagonal layered structure.

As a result, in such a ternary positive electrode active material, the AC balance is broken at the positive electrode and the negative electrode if the battery is charged until the constant upper limit voltage is always ignored, ignoring the temperature.

The AC balance is strictly expressed by the following equation (1).

AC balance = (total value of capacities obtained from the negative electrode active material layer facing the positive electrode active material layer) / (total value of capacities obtained from the positive electrode active material layer facing the negative electrode active material layer) ... (One)

Here, the total value of the capacities obtained from the negative electrode active material layer facing the positive electrode active material layer is the negative electrode capacity, and the total value of the capacities obtained from the positive electrode active material layer facing the negative electrode active material layer is the positive electrode capacity. Therefore, simply speaking, the AC balance can be defined as the capacity ratio (A / C) of the anode capacity and the cathode capacity, that is, AC balance = anode capacity / cathode capacity.

Until now, the secondary battery 2 using the ternary positive electrode active material has been charged and discharged at a constant voltage (usually 4.2 V at 25 캜) regardless of the temperature, like lithium manganese oxide. However, as shown in Fig. 3, in the ternary positive electrode active material, the positive electrode capacity increases by the temperature. As a result, if this phenomenon is ignored and the battery is charged until it reaches a constant voltage regardless of the temperature, the capacity of the positive electrode side gradually increases. On the other hand, on the negative electrode side, the change of the capacity does not occur even if the temperature changes. As a result, the denominator becomes larger and the AC balance becomes less than 1 in the formula of AC balance = negative electrode capacity / positive electrode capacity. In this state, excessive lithium (Li) ions are reduced and precipitated in the negative electrode.

Therefore, in the present embodiment, the positive electrode active material having such a temperature dependency is set to an upper limit voltage according to the temperature so as to have the optimum AC balance with respect to the temperature, and the voltage of the secondary battery 2 is controlled according to the temperature (According to the control sequence described above). The optimum AC balance here is a value greater than 1, and preferably greater than 1.2. This means that by setting the AC balance to a value larger than 1, the negative electrode capacity becomes larger, thereby preventing precipitation of lithium ions in the negative electrode. In addition, preferably, the AC balance is 1.2 or more, thereby providing a margin.

The value of AC balance may be appropriately determined according to the secondary battery to be charged. If the value is larger than 1, the upper limit is not particularly limited. However, if it is too large, the negative electrode active material becomes excessively excessive with respect to the positive electrode active material, The energy density becomes low. Therefore, in consideration of efficient use of resources, it is preferable that the AC balance is less than 2.

Next, a description will be given of a method of generating a correspondence table (corresponding information) of the temperature and the upper limit voltage.

First, the constant-current constant-voltage charging is performed while keeping the temperature of the secondary battery unchanged at room temperature (for example, 25 占 폚). That is, the secondary battery 2 is charged to a predetermined upper limit voltage by a constant current, then charged to a predetermined voltage, and is charged at a time point when the current to the secondary battery 2 becomes less than a predetermined current value Lt; / RTI > As a result, the battery is fully charged at room temperature. Normally, the voltage at this time is 4.2V. Then, the charging capacity at this time is recorded (capacity is obtained from the amount of current (A) and time (h) until full charge).

Thereafter, the ambient temperature of the secondary battery 2 is variously changed, and the temperature of the secondary battery is forcibly changed (for example, the environmental temperature of the secondary battery is changed) Constant-current charging is performed until the charging capacity becomes equal to the capacity. That is, the secondary battery 2 that has been completely discharged is charged with a constant current value, and the time point at which the charge current value falls below the predetermined lower limit value is set to full charge, and the voltage of the secondary battery at that time is recorded. Then, the recorded voltage at the full charge becomes the upper limit voltage at the time of charging at that temperature, thereby making the correspondence table of the temperature vs. the upper limit voltage.

Normally, when the constitution of the battery (the composition of the positive electrode active material, the amount used, the size of the positive electrode and the negative electrode, the composition of the electrolyte, and the like) are the same, the charging capacity and the upper limit voltage become equal. Accordingly, the correspondence table of the temperature versus the upper limit voltage can be applied to the secondary battery having the same configuration afterwards, by preparing the correspondence table of the temperature versus the upper limit voltage as described above by using the reference sample. In principle, it is also possible to create a correspondence table of the temperature versus the upper limit voltage from one sample. However, since there is a slight variation in each product in practice, it is preferable to prepare the correspondence table of the temperature versus the upper limit voltage by using a plurality of samples.

The correspondence table created in this way lowers the upper limit voltage as the temperature of the secondary battery 2 rises (see Examples described later). This is because, as can be seen from Fig. 3, as the temperature rises, the positive electrode capacity increases. As described above, only the positive electrode capacity increases and the AC balance is broken. Therefore, it is possible to prevent the AC balance from being broken by controlling the upper limit voltage of the secondary battery 2 at the time of charging to be lowered as the temperature rises.

The correspondence table (temperature-to-upper-voltage correspondence information) is stored in the control unit 7 (for example, stored in the memory). The correspondence table stored in the control unit 7 is specifically a data table or the like that can handle the control procedure (program) executed by the control unit 7 (hardware CPU).

In actual operation, the correspondence table of the temperature vs. the upper limit voltage may be created at an interval of 1 占 폚, but it may be an interval of several 占 폚. For example, if it is within the range of about 3 캜, it can be accepted from the tolerance of the member and the cell design being used. Therefore, the correspondence table itself may be set at a relationship of the temperature at intervals of 3 占 폚 and the corresponding upper limit voltage. Of course, other temperature intervals may be used if the AC balance is not broken.

[Secondary Battery]

Hereinafter, a stacked lithium ion secondary battery as an example of the secondary battery 2 will be described.

(Non-bipolar lithium ion secondary battery)

4 is a schematic cross-sectional view for explaining the overall structure of a lithium ion secondary battery of a non-bipolar type and a stacked type.

In the lithium ion secondary battery 10 shown in Fig. 4, the battery casing 22 is used to enclose the power generation element 17 in a sealed manner. Here, the power generation element 17 is formed of the positive electrode plate, the electrolyte layer 13, and the negative electrode collector 14 both surfaces of which the positive electrode active material layer 12 is formed on both surfaces of the positive electrode collector 11 And a negative electrode plate on which the negative electrode active material layer 15 is formed. The positive electrode active material layer 12 of one positive electrode plate and the negative electrode active material layer 15 of one negative electrode plate adjacent to the one positive electrode plate are opposed to each other with the electrolyte layer 13 interposed therebetween, A positive electrode plate, an electrolyte layer 13, and a negative electrode plate.

Thereby, the adjacent positive electrode active material layer 12, the electrolyte layer 13 and the negative electrode active material layer 15 constitute one unit cell layer 16. Therefore, the lithium ion secondary battery 10 may have a configuration in which a plurality of unit cell layers 16 are stacked and electrically connected in parallel. The positive electrode active material layer 12 is formed on only one side of the outermost positive electrode current collector 11a located on the outermost layers of the power generating element 17. The arrangement of the positive electrode plate and the negative electrode plate may be changed. At this time, the outermost layer negative electrode current collector (not shown) is positioned on both outermost layers of the power generating element 17, and the negative electrode active material layer 15 is formed on only one side in the outermost negative electrode current collector .

The positive electrode tab 18 and the negative electrode tab 19 which are electrically connected to the respective electrode plates (the positive electrode plate and the negative electrode plate) described above are connected to the positive electrode terminal lead 20 and the negative electrode terminal lead 21, (11) and the negative electrode collector (14) by ultrasonic welding, resistance welding, or the like. The positive electrode tab 18 and the negative electrode tab 19 which are electrically connected to the positive electrode collector 11 and the negative electrode collector 14 are exposed to the outside of the battery casing 22. [

In view of the structure of such an electrode, the lithium ion secondary battery 10 is referred to as a non-bipolar lithium ion secondary battery in comparison with the structure shown in FIG. 5 to be described later.

(Bipolar lithium ion secondary battery)

5 is a schematic cross-sectional view for explaining the overall structure of a bipolar lithium ion secondary battery of another type. Here, the term bipolar is used as a term corresponding to the above-mentioned non-bipolar type.

The lithium ion secondary battery 30 shown in Fig. 5 has a structure in which a power generation element 37 in which a charging / discharging reaction is actually performed is sealed inside the battery exterior material 42. As shown in Fig. 5, the power generation element 37 of the bipolar type secondary battery 30 is formed by sandwiching the electrolyte layer 35 between the bipolar electrodes 34 composed of two or more bipolar electrodes, The positive electrode active material layer 32 and the negative electrode active material layer 33 of the negative electrode 34 are opposed to each other with the electrolyte layer 35 interposed therebetween. Here, the bipolar electrode 34 has a structure in which the positive electrode active material layer 32 is provided on one surface of the current collector 31 and the negative electrode active material layer 33 is provided on the other surface. That is, in the bipolar type secondary battery 30, the bipolar electrode 34 having the positive electrode active material layer 32 on one side of the current collector 31 and the negative electrode active material layer 33 on the other side is electrolyzed And a power generating element 37 having a structure in which a plurality of layers are stacked via a layer 35.

The adjacent positive electrode active material layer 32, the electrolyte layer 35 and the negative electrode active material layer 33 constitute one unit cell layer 36. Therefore, the bipolar type secondary battery 30 may have a structure in which the unit cell layers 36 are laminated. An insulating layer (sealing portion) 43 is disposed in the periphery of the unit cell layer 36 to prevent a liquid level due to leakage of the electrolyte from the electrolyte layer 35. The insulating layer 43 is provided to isolate the adjacent current collectors 31 from each other and to prevent a short circuit due to contact between the adjacent electrodes (the positive electrode active material layer 32 and the negative electrode active material layer 33) .

The positive electrode 34a and the negative electrode 34b located on the outermost layer of the power generation element 37 may not have a bipolar electrode structure. For example, the positive electrode active material layer 32 or the negative electrode active material layer 33 having only one side required for the current collectors 31a and 31b may be disposed. Specifically, as shown in Fig. 4, the positive electrode active material layer 32 may be formed on only one side of the outermost layer current collector 31a on the positive electrode side located on the outermost layer of the power generation element 37. [ Likewise, the negative electrode active material layer 33 may be formed on only one side of the outermost layer current collector 31b on the negative electrode side located on the outermost layer of the power generating element 37. Further, in the bipolar lithium ion secondary battery 30, the current collecting plates 38a and 39b are provided on the outer sides of the outermost positive current collector 31a and the negative electrode side outermost current collector 31b at the both upper and lower ends, . The collector plates 38a and 39b are respectively extended to be the positive electrode tab 38 and the negative electrode tab 39. [ The collector plates 38a and 39b may be bonded together via a positive terminal lead and a negative terminal lead as necessary. The positive electrode side outermost layer current collector 31a may be extended to be the positive electrode tab 38 and may be led out from the laminate sheet which is the battery exterior material 42. [ Likewise, the negative electrode side outermost layer current collector 31b may be extended to form the negative electrode tab 39, and the negative electrode tab 39 may be led out from the laminate sheet which is the battery facer material 42 as well.

Even in the bipolar lithium ion secondary battery 30, the portion of the electric power generating element 37 is pressure-sealed in the battery casing 42 and the positive electrode tab 38 and the negative electrode tab 39 are connected to the outside of the battery casing 42 It is preferable that the structure is taken out. With such a structure, it is possible to prevent the impact from the outside and deterioration of the environment during use. The basic structure of the bipolar lithium ion secondary battery 30 is a structure in which a plurality of stacked unit cells 36 are connected in series.

(Outer shape)

Fig. 6 is a perspective view showing the external appearance of the stacked lithium ion secondary battery shown in Fig. 4 or Fig. 5. Fig. This outer shape is also called a flat secondary battery.

6, the flat type lithium ion secondary battery 50 has a flat rectangular shape and has a positive electrode tab 58 and a negative electrode tab 59 for extracting electric power from both sides thereof, . The power generating element 57 is wrapped by the battery sheath 52 of the lithium ion secondary battery 50 and its periphery is thermally fused and the power generating element 57 is wound around the positive electrode tab 58 and the negative electrode tab 59 And is sealed in a state of being drawn out to the outside. Here, the power generation element 57 corresponds to the power generation elements 17 and 37 of the lithium-ion secondary battery 10 and 30 of the non-bipolar or bipolar type shown in Figs. 4 and 5, (Single cells) 16 each composed of a negative electrode layer 12, an electrolyte layer 13, and a negative electrode layer 15 are stacked.

In this embodiment, the temperature sensor 4 is attached to the surface of the external member of the stacked flat lithium ion secondary battery 50. Thus, the present temperature of the secondary battery 2 required as the secondary battery system 1 is measured.

The positive electrode tab 58 and the negative electrode tab 59 may be taken out from the same side or the positive electrode tab 58 and the negative electrode tab 59 may be taken out from the same side, Tab 59 may be divided into a plurality of portions and taken out from each side, and the present invention is not limited to the form shown in Fig.

Next, the details of each member in the secondary battery 2 of the above-described type will be described.

[Whole house]

The current collector is made of a conductive material. The material constituting the current collector is not particularly limited as far as it has conductivity, and conventionally known materials such as metal and conductive polymer can be suitably used. Concretely, at least one or more kinds selected from the group consisting of Fe, Cr, Ni, Mn, Ti, Mo, V, Nb, Al, Cu, Ag, Au, Or alloys thereof, such as stainless steel, may preferably be used. In the present embodiment, a clad material of Ni and Al, a clad material of Cu and Al, or a combination plating material of these current collector materials can also be preferably used. Alternatively, the current collector may be formed by coating Al, which is another current collector material, on the surface of the metal (excluding Al) as the current collector material. Further, in some cases, the current collector may be used to return the metal foil to two or more of the current collector materials.

The thickness of the current collector is not particularly limited, but any current collector usually has a thickness of 1 to 100 mu m, preferably 1 to 50 mu m. However, even if the above-mentioned range is exceeded, it falls within the technical scope of the present invention as far as it does not impair the function and effect of the present invention.

Further, in the non-bipolar battery of Fig. 1, in addition to the foil using the above-described material, the current collector may be composed of a mesh using an above-described material, an expanded grid (expanded metal), punched metal or the like. The mesh scale, line diameter, number of meshes and the like are not particularly limited, and conventionally known ones can be used.

Al, Ni, stainless steel (SUS) or the like can be used as the positive electrode collector 11 of the non-bipolar battery 10, but Al is preferable because it is easy to process into a thin film and is inexpensive. Examples of a method of carrying the positive electrode active material layer (positive electrode material mixture) on the positive electrode collector include a method of making a paste using a press molding method or a solvent or the like, applying the solution on a current collector, . The method of supporting the positive electrode active material layer (positive electrode mixture) on the positive electrode collector is also applicable to a method of supporting the negative electrode active material layer (negative electrode mixture) on the negative electrode collector.

[Positive electrode active material layer (positive electrode mixture)]

The positive electrode active material layer (positive electrode material mixture) is a layer formed on the current collector and including a positive electrode active material serving as a center of charge / discharge reaction. The positive electrode active material layer (positive electrode mixture) includes those containing a positive electrode active material, a conductive material (also referred to as a conductive auxiliary agent) for improving electrical conductivity, a binder, and the like. The compounding ratio of these components is not particularly limited and can be adjusted by appropriately referring to known knowledge on existing lithium ion secondary batteries.

(Positive electrode active material)

As described above, in the secondary battery 2 in the present embodiment, it is preferable to use a ternary positive electrode active material as the positive electrode active material.

Examples of the positive electrode active material include LiMn ₂ O ₄ , LiCoO ₂ , LiNiO ₂ , Li (Ni, Co, Mn) O ₂ , Li ₂ MnO ₃ , Li ₂ MnO ₃ -LiMO ₂ Transition metal complex oxides, lithium-transition metal sulfate compounds, and the like can be given as examples of the lithium-transition metal complex oxide and the lithium-transition metal complex oxide in which some of these transition metals are substituted by other elements. In some cases, two or more kinds of positive electrode active materials may be used in combination. Preferably, from the viewpoints of capacity and output characteristics, a lithium-transition metal composite oxide is used as the positive electrode active material. It goes without saying that other positive electrode active materials may be used.

Particularly, in the present embodiment, as described above, it can be suitably applied to a positive electrode active material which has temperature dependency and is accompanied with non-uniformity in battery characteristics in a hydrothermal state due to heat generation. Specifically, LiNiO ₂ , a material in which a part of Ni of LiNiO ₂ is substituted by another element such as Co or Al, LiCoO ₂ , Li (Ni, Co, Mn) O ₂ (= LiNixCoyMnzO ₂ ; x + y + z = 1), a hexagonal layered structure such as Li ₂ MnO ₃ , Li ₂ MnO ₃ -LiMO ₂ (M = Co, Ni etc.) solid solution, etc. [Highly filling layered rock salt type, rock salt type layered structure Or the like).

(Conductive material)

The conductive material (also referred to as a conductive auxiliary agent) refers to an additive compounded to improve the conductivity of the positive electrode active material layer (positive electrode material mixture). The conductive auxiliary agent is not particularly limited and conventionally known ones can be used. For example, carbon materials such as natural graphite, artificial graphite, cokes, carbon black such as acetylene black, graphite, and carbon fiber can be cited. As the conductive material, each of them may be used alone, or for example, a mixture of artificial graphite and carbon black may be used. When the conductive auxiliary agent is contained, the electronic network inside the active material layer is effectively formed, contributing to the improvement of the output characteristics of the battery.

(bookbinder)

The binder is added to the active material layer for the purpose of maintaining the electrode structure (three-dimensional network) by binding the active materials or binding the active material with the current collector or the conductive auxiliary agent.

Examples of the binder include polyvinylidene fluoride (hereinafter may be referred to as PVDF), polytetrafluoroethylene (hereinafter may be referred to as PTFE), polytetrafluoroethylene, hexafluoropropylene / vinylidene fluoride copolymer, Polyvinylidene fluoride copolymer, tetrafluoroethylene-perfluoro vinyl ether copolymer, polyvinyl acetate, polyimide and acrylic resin, epoxy resin, polyurethane resin and urea resin, and the like. Resin, and rubber-based materials such as styrene butadiene rubber (SBR). These may be used alone or in combination of two or more. In addition, these binders may be dissolved or dispersed in a solvent in which a binder is soluble or dispersible, such as N-methyl-2-pyrrolidone (hereinafter, sometimes referred to as NMP) or water.

The positive electrode active material layer (positive electrode active material composition) of the present embodiment is formed so that the proportion of the fluororesin in the positive electrode active material layer (positive electrode material mixture) is 1 to 10 mass% and the proportion of the polyolefin resin is 0.1 to 10 mass% It is preferable to use it in combination with the powder. By doing so, it is preferable that the lithium ion secondary battery is excellent in bondability to the current collector and the safety of the lithium ion secondary battery against external heating typified by the heating test can be further improved.

(Electrolyte, support salt)

Specific examples of the supporting salt (lithium salt) include inorganic acid anion salts such as LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiTaF ₆ , LiAlCl ₄ and Li ₂ B ₁₀ Cl ₁₀ ; Organic acid anion salts such as LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N and Li (C ₂ F ₅ SO ₂ ) ₂ N. These support salts may be used alone or in combination of two or more.

(Other Details of Positive Electrode Active Material)

The average particle diameter of the positive electrode active material is not particularly limited. However, if the average particle diameter is too large, the reaction surface area of the active material becomes small, or lithium ion conduction within the particle of the active material causes the lithium ion conductivity in the active material layer to be controlled. From this viewpoint, the average particle diameter of the active material is preferably 0.1 to 100 占 퐉, more preferably 1 to 50 占 퐉, and still more preferably 1 to 20 占 퐉. However, forms deviating from these ranges may also be employed. The average particle diameter of the active material is assumed to be a value measured by laser diffraction particle size distribution measurement (laser diffraction scattering method).

The content of the positive electrode active material in the positive electrode active material layer (positive electrode material mixture) is preferably 70 to 98 mass%, more preferably 80 to 98 mass%, based on the total mass of the positive electrode active material layer. When the content of the positive electrode active material is within the above range, the energy density can be increased, which is preferable.

The thickness of the positive electrode active material layer (thickness of the one surface of the current collector) is preferably 20 to 500 탆, more preferably 20 to 300 탆, and still more preferably 20 to 150 탆.

[Negative electrode active material layer]

The negative electrode active material layer in the negative electrode is a layer formed on the current collector and containing a negative electrode active material and Li particles that are central to the charging / discharging reaction. The negative electrode active material layer includes a negative electrode active material and a conductive material (also referred to as a conductive auxiliary agent), a binder, an electrolyte (a polymer matrix, an ion conductive polymer, an electrolytic solution or the like) for enhancing electrical conductivity, Electrolytic salts), and the like. The compounding ratio of these components is not particularly limited, and can be adjusted by properly referring to known knowledge of the lithium ion secondary battery.

(Negative electrode active material)

As the negative electrode active material used for the negative electrode active material layer, carbon (carbon) is preferable, and a material capable of doping and dedoping lithium is preferable. Examples of the carbon include carbon materials such as graphite carbon materials such as natural graphite, artificial graphite and expanded graphite, carbon black, activated carbon, carbon fiber, coke, soft carbon and hard carbon. In some cases, two or more negative electrode active materials may be used in combination.

However, in the case of the material or composition in which the negative electrode active material itself does not cause metal precipitation, for example, the lithium transition metal-composite oxide having a partial composition is not applicable to the present embodiment. This is because if the metal (particularly lithium) is not precipitated in the negative electrode, there is no reduction in capacity due to the precipitation.

However, the negative electrode is not limited to carbon (carbon), and the present embodiment is suitable when a substance or composition in which metal (particularly lithium) is precipitated in the negative electrode is used.

(Conductive material, binder, electrolyte, support salt)

As for the conductive material and the binder, those described in the section of the positive electrode active material layer can be similarly used. Particularly, when a negative electrode active material having no conductivity such as a material for alloying with lithium is used, the conductive material is effectively used. When a conductive metal, alloy, carbon material, or the like is used for the negative electrode active material, the conductive material may be omitted.

The average particle diameter of the negative electrode active material is not particularly limited. However, if the average particle diameter is too large, the reaction surface area of the active material may become small, or lithium ion conduction in the particles of the active material may lead to the lithium ion conduction in the active material layer. From this viewpoint, the average particle diameter of the active material is preferably 0.1 to 20 占 퐉. However, forms deviating from these ranges may also be employed. In the present application, the average particle diameter of the active material is assumed to be a value measured by a laser diffraction scattering type particle size distribution measuring apparatus.

[Electrolyte Layer]

The electrolyte (layer) comprises an electrolyte and, if necessary, an organic solvent (plasticizer) and a separator.

As the electrolyte, for example, a liquid electrolyte or a polymer electrolyte may be used.

(Liquid electrolyte)

The liquid electrolyte (electrolytic salt and organic solvent) is not particularly limited, and conventionally various electrolytic solutions can be appropriately used. For _{example, LiPF 6, LiBF 4, LiClO} 4, LiAsF 6, LiTaF 6, LiAlCl 4, Li 2 B 10 inorganic acid anion salts such as _{Cl 10, LiCF 3 SO 3,} Li (CF 3 SO 2) 2 N, Li (Electrolyte salt), which is selected from organic acid anion salts such as (C ₂ F ₅ SO ₂ ) ₂ N (also referred to as LiBETI), and is at least one kind selected from the group consisting of cyclic monomers such as propylene carbonate and ethylene carbonate Carbonates; Chain carbonates such as dimethyl carbonate, methyl ethyl carbonate and diethyl carbonate; Ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane and 1,2-dibutoxyethane; lactones such as? -butyrolactone; Nitriles such as acetonitrile; Esters such as methyl propionate; Amides such as dimethylformamide; (Organic solvent) such as an aprotic solvent in which at least one kind or a mixture of two or more kinds selected from methyl acetate and methyl formate is used can be used. However, the present invention is not limited thereto.

(Polymer electrolyte)

On the other hand, the polymer electrolyte is classified into a gel electrolyte containing an electrolytic solution and an intrinsic polymer electrolyte containing no electrolytic solution.

The gel electrolyte includes an electrolytic solution used in a conventionally known lithium ion secondary battery in a solid polymer electrolyte having ion conductivity, and also includes a polymer having an electrolyte in a skeleton of a polymer having no lithium ion conductivity. Examples of the solid polymer electrolyte having ionic conductivity include polyethylene oxide (PEO), polypropylene oxide (PPO), and known solid polymer electrolytes such as copolymers thereof. This solid polymer electrolyte having ion conductivity is used in an intrinsic (all solid) polymer electrolyte.

Examples of the polymer having no lithium ion conductivity used in the gel electrolyte include polyvinylidene fluoride (PVDF), polyvinyl chloride (PVC), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA) Can be used. However, the present invention is not limited thereto. The PAN, PMMA and the like can be used as the polymer having ion conductivity, since any one of them can enter into a class having almost no ionic conductivity. Here, as the polymer having no lithium ion conductivity used for the polymer gel electrolyte, It is.

When the electrolyte layer is composed of a liquid electrolyte or a gel electrolyte, a separator may be used for the electrolyte layer. Specific examples of the separator include polyolefin such as fluororesin, polyethylene and polypropylene, nylon (registered trademark of Mydupont), aromatic aramid, and the like having a shape of a microporous film, a nonwoven fabric, Materials. The thickness of the separator is preferably from 5 to 200 mu m as the thickness becomes thinner as long as the mechanical and chemical strength is maintained, from the viewpoint of increasing the volume energy density as a battery and decreasing the internal resistance.

The intrinsic polymer electrolyte has a structure in which a support salt (lithium salt) is dissolved in a matrix polymer which is a solid polymer electrolyte having ionic conductivity and does not contain an organic solvent as a plasticizer. Therefore, when the electrolyte layer is constituted of an intrinsic polymer electrolyte, there is no leakage of liquid from the battery, and the reliability of the battery can be improved.

In addition, various additives may be contained in the electrolyte layer (electrolytic solution).

[Insulating layer (seal part)]

The insulating layer (the sealed portion) 43 is a layer which is formed in the lithium ion secondary battery, particularly in the bipolar battery 30 shown in Fig. 2, so that adjacent current collectors in the battery are in contact with each other, In order to prevent short-circuiting caused by short-circuiting of the unit cell layer 36. The insulating layer 43 may be any insulating material having sealability against falling off of the solid electrolyte, sealing (sealability) against moisture permeation from the outside, heat resistance under battery operating temperature, and the like. For example, a urethane resin, an epoxy resin, a polyethylene resin, a polypropylene resin, a polyimide resin, a rubber and the like may be used. Among them, urethane resin and epoxy resin are preferable from the viewpoints of corrosion resistance, chemical resistance, easiness of production (film formability), economy and the like.

[Tab]

The material of the tabs (positive electrode tabs 18, 38 and negative electrode tabs 19, 39) may be aluminum, copper, nickel, stainless steel, these alloys, or the like. These are not particularly limited, and a known material conventionally used as a tap can be used.

[Exterior]

In the lithium ion secondary batteries 10 and 30, in order to prevent external impact or environmental deterioration during use, the entire power generating element in which the electrolyte holding layer is formed is divided into the battery casing 22, 42 to the battery case ). As the exterior material, a conventionally known metal pipe case can be used, and a bag-like case that can cover a power generating element using a laminated sheet including aluminum can be used. Since the laminate sheet has a high degree of freedom in its shape, it can be suitably applied to a battery using a negative electrode material having a large expansion / shrinkage in addition to being easily mounted in a narrow space.

Since the outer casing of the metal pipe case type has strength, even if the power generating element in the pipe is expanded or contracted slightly, the thickness of the cell does not change. It is also possible to obtain a tube case having a desired strength and size by examining the material of the tube, the design of the plate thickness, and the clearance between the outer tube and the power generation element.

The polymer-metal composite laminate sheet is not particularly limited, and conventionally known ones in which a metal film is disposed between the polymer films so that the entire laminated body is integrated can be used. Concretely, a laminate is formed by laminating together a heat-sealable layer (laminate innermost layer) comprising an outer protective layer (laminate outermost layer) comprising a polymer film, a metal film layer and a polymer film, have.

In particular, it is preferable to use an aluminum laminate film having a high degree of freedom in shape. Aluminum laminate refers to a laminate containing aluminum. Specific examples of the aluminum laminate film include a laminate film of a three-layer structure formed by laminating polypropylene (PP), aluminum, and nylon in this order, but the present invention is not limited thereto.

The secondary battery of the above-described type is used as the secondary battery 2 in the secondary battery system 1 already described.

[Example]

Here, an embodiment to which the present embodiment is applied will be described. A comparative example for comparing the effects of the present embodiment will be described. However, the technical scope of the present invention is not limited to the forms shown in the following embodiments.

<Examples>

(1) Production of lithium ion secondary battery

As a positive electrode active material Li [Ni Mn _{0 .3 0 .5 0 .2} Co] O _2, acetylene black 94 as polyvinylidene fluoride (PVDF) and a conductive material as a binder: and mixed in a weight ratio of 3: 3 And dispersed with N-methyl-2-pyrrolidone to prepare a positive electrode slurry. This slurry was coated on an aluminum foil having a thickness of 20 mu m and then dried and rolled to prepare a positive electrode. Styrene-butadiene rubber as a negative electrode active material, styrene-butadiene rubber as a binder, and carboxymethyl cellulose as a thickener were mixed at a weight ratio of 96: 3: 1 and dispersed in water to prepare a slurry of negative active material. This slurry was coated on a copper foil having a thickness of 10 mu m and then dried and rolled to prepare a negative electrode.

As a test battery, eight positive electrodes and seven positive electrodes were stacked on a positive electrode and a negative electrode via a separator, respectively, and these were stacked in a laminate film as a battery outer cover material. Thereafter, each of the positive electrode current collector and the negative electrode current collector was protruded from the opposing face from the separator, and a positive electrode terminal lead made of Al and a negative electrode terminal lead made of Ni were welded. Subsequently, the positive electrode terminal lead and the negative electrode terminal lead were respectively protruded from the opposite sides of the battery and sandwiched in the external laminate film, and the three sides of the periphery were heat-welded. Thereafter, the concentration of the LiPF ₆ electrolyte was dissolved to 1 M in a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of 3: 7, and then vinylene carbonate (VC), and succinonitrile were added and dissolved in an amount of 1.5 wt% and 0.5 wt%, respectively, to prepare an electrolytic solution. This electrolytic solution was poured into an enclosure sealed at three sides to seal the whole. Subsequently, initial charging and aging were performed to produce a lithium ion secondary battery.

The AC balance was set to 1.2 based on the charge / discharge capacity of the positive electrode and the negative electrode per unit area at a temperature of 25 占 폚 that had already been obtained.

(2) Measurement of charging / discharging capacity (25 ° C)

The lithium ion secondary battery produced in the above (1) was subjected to a charge-discharge test by constant-current constant-voltage charging and constant-current discharge under the following conditions.

Charging: Charging upper limit voltage: 4.2 V, Charging time: 2.5 hours, C rate: 1 C

Discharge: Lower discharge voltage: 2.5V, C rate: 1C

Ambient temperature: 25 ℃

The obtained charge capacity is A (Ah) and the discharge capacity is B (Ah).

(3) Measurement of charge / discharge capacity at each temperature

After the execution of the above (2), the temperature of the lithium ion secondary battery was variously changed, and the charging / discharging capacity was measured in the same manner as in (2). The correspondence table of the temperature-upper limit voltage (Table 1) was prepared from the charging voltage at which the charging capacity at each temperature obtained coincides with the charging capacity at 25 占 폚.

In accordance with this correspondence table, the charge / discharge was repeated by controlling the upper limit voltage at the time of charging according to the secondary battery temperature as in the embodiment. Thereafter, precipitation of lithium on the negative electrode side was not observed even when the lithium ion secondary battery was observed.

<Comparative Example>

The charge-discharge capacity of the lithium ion secondary battery obtained in (2) of Example was measured under the conditions described in (2) of Example, except that the secondary battery temperature was changed to 25 占 폚 or more .

In this comparative example, the charging capacity was monotonous with respect to the temperature rise, and when the difference from the value at 25 캜 was remarkable, precipitation of lithium was confirmed on the negative electrode side. In addition, the examples and comparative examples all contain succinonitrile. As can be seen from the comparative example, it can be seen that lithium precipitation in the negative electrode can not be suppressed by simply adding succinonitrile. On the other hand, it can be seen that lithium precipitation in the negative electrode can be prevented by controlling the upper limit voltage according to the temperature as in the embodiment.

From the results of these Examples and Comparative Examples, it was found that lithium precipitation in the negative electrode can be prevented by controlling the voltage (upper limit voltage) reached by the secondary battery upon charging according to the temperature. Therefore, by the control of the present embodiment, it is possible to prevent a reduction in the energy density due to the reduction of lithium ions in the electrolytic solution caused by the lithium precipitation in the negative electrode.

From these Examples and Comparative Examples, it can be seen that, in order to maintain the AC balance at a value larger than 1, the upper limit voltage decreases as the temperature of the secondary battery rises.

[Second Embodiment]

The second embodiment is a secondary battery control device (so-called charger) for charging a predetermined type of lithium ion secondary battery.

7 is a block diagram showing the configuration of a secondary battery control apparatus according to the second embodiment. In the drawings, members having the same configuration and functions as those of the first embodiment are denoted by the same reference numerals.

This secondary battery control apparatus 100 has a secondary battery holder 8 for setting a lithium ion secondary battery to be charged. Like the first embodiment, it includes a voltage sensor 3, a temperature sensor 4, a voltage / current regulating section 5, a current sensor 6, and a control section 7.

Here, the voltage sensor 3 measures the voltage between the positive electrode and the negative electrode of the lithium ion secondary battery set in the secondary battery holder 8. The temperature sensor 4 also measures the temperature of the lithium ion secondary battery set in the secondary battery holder 8 in the same manner. The configuration and function of each of the other members are the same as those of the first embodiment, and a description thereof will be omitted.

In the second embodiment, the upper limit voltage at the time of charging is controlled in accordance with the measured temperature with respect to the secondary battery set in the secondary battery holder 8 by the charging sequence similar to that of the first embodiment.

Here, the relationship between the temperature and the upper limit voltage is predetermined in the lithium ion secondary battery to be charged. However, as described above, the secondary battery 2 has the same relationship between the temperature and the upper limit voltage as long as the secondary battery 2 has the same configuration from the configuration (the composition and amount of the positive electrode active material, the amount of the positive electrode and the size of the negative electrode, . Therefore, if the correspondence table of the temperature and the upper limit voltage created by the secondary battery (preferably one, but preferably plural) serving as a sample is previously stored in the secondary battery control device 100, the same type of secondary battery 2 The upper limit voltage can be controlled in accordance with the temperature. In order to correspond to the plurality of types of secondary batteries 2, a correspondence table of temperature-type and upper-level voltage for each type is stored in advance in the memory in the control unit 7, The correspondence table may be switched and used in accordance with the type of Further, the correspondence table of the temperature versus the upper limit voltage may be replaced with a table in the memory in the control section 7. [

[Effect of Embodiment]

Next, the effects of the first and second embodiments described above will be described.

(1) In the first and second embodiments, the upper limit voltage of the secondary battery at the time of charging is controlled in accordance with the temperature of the secondary battery using the information of the temperature and the upper limit voltage of the secondary battery , The AC balance can be kept constant even if the temperature of the secondary battery changes. As a result, lithium precipitation in the negative electrode is prevented, and reduction in energy density accompanying precipitation of lithium can be prevented.

In the first and second embodiments, as the secondary battery, a conventional structure or a material composition can be used as it is. That is, in the present embodiment, it is not necessary to produce an additive of a new composition or an electrolytic solution to which such additive is added as in the prior art (Patent Document 1). As a result, the secondary battery which has been developed and produced so far can be used as it is, so that the cost of the secondary battery is not increased even when the secondary battery system 1 is constituted.

(2) In the first and second embodiments, since the AC balance is set to a value larger than 1, the AC balance is broken and the positive electrode capacity is excessively increased with respect to the negative electrode capacity, thereby preventing lithium from precipitating in the negative electrode .

(3) In the first and second embodiments, when the lithium ion secondary battery using the positive electrode active material having the hexagonal layered structure having the temperature dependency on the positive electrode capacity is charged, the lithium ion dissolved in the electrolyte Can be prevented from being precipitated as lithium in the negative electrode.

(4) In the first and second embodiments, as the positive electrode active material of the secondary battery, specifically, for example, a composite oxide containing lithium and nickel, a composite oxide containing lithium and manganese, And the like. It is possible to prevent precipitation of lithium ions in the negative electrode when such a positive electrode active material is used.

(5) In the second embodiment, since the secondary battery holder 8 is provided, the secondary battery is set in the secondary battery holder 8 and charged in the same manner as in the first embodiment, The lowering of the energy density of the secondary battery can be prevented.

(6) In addition, the first and second embodiments are a large-capacity power source such as an electric vehicle, a hybrid electric vehicle, a fuel cell vehicle, and a hybrid fuel cell vehicle, in which a power source for driving a vehicle for obtaining a solid energy density and a solid output density It can be suitably used for charging the secondary battery used in the auxiliary power source.

While the embodiments and the examples to which the present invention has been applied have been described above, the present invention is not limited to these embodiments and examples.

For example, as a form of the secondary battery 2, a laminate type flat lithium ion secondary battery is described as an example, but a winding type lithium ion battery and further a cylindrical shape is deformed into a rectangular shape with a flat shape And the like.

Further, although the present invention is suitable for a secondary battery that watches a ternary positive electrode active material having a hexagonal layered structure having a temperature dependency on capacity, the present invention is not necessarily limited to such a ternary positive electrode active material. For example, even in a secondary battery using a positive electrode active material having no temperature dependency such as lithium manganese oxide, the present invention is applied to strictly control the upper limit voltage corresponding to the current temperature, thereby preventing lithium precipitation in the negative electrode, Can be prevented.

In addition, it goes without saying that the present invention can be variously modified on the basis of the constitution described in the claims.

1: Secondary battery system
2: secondary battery
3: Voltage sensor
4: Temperature sensor
5: Voltage &amp;
6: Current sensor
7:
8: Secondary battery holder
10: Lithium ion secondary battery
11: positive electrode current collector
12, 32: Positive electrode active material layer
13, 35: electrolyte layer
14: anode collector whole
15, 33: Negative electrode active material layer
16, 36:
17, 37: Power generation elements
18, 38: positive electrode tab
19, 39: negative electrode tap
20: Positive terminal lead
21: Negative terminal lead
22: Battery enclosure
30: Bipolar Lithium Ion Rechargeable Battery
31: collector of bipolar lithium ion secondary battery
31a: Outermost layer current collector on the positive electrode side
31b: Outermost layer collector on the negative electrode side
34: bipolar electrode
34a: positive electrode
34b: negative electrode
38a: a collector plate on the outer side of the outermost layer collector on the positive electrode side
39a: a collector plate on the outer side of the outermost collector layer on the negative electrode side
43: insulating layer (sealing portion)
50: stacked flat lithium ion secondary battery
52: Battery exterior material (laminated film)
57: Elements of power generation
58: positive electrode tab
59: Negative electrode tab
100: secondary battery control device

Claims (6)

A secondary battery,
A temperature sensor for measuring a temperature of the secondary battery;
A voltage sensor for measuring a voltage between the positive electrode and the negative electrode of the secondary battery,
And a control unit for controlling to lower the upper limit voltage of the secondary battery at the time of charging as the temperature of the secondary battery measured by the temperature sensor rises,
The control unit stores correspondence information composed of the temperature of the secondary battery and the upper limit voltage for setting the value of the negative electrode capacity / positive electrode capacity to a value larger than 1, and the upper limit voltage obtained from the corresponding information and the voltage And the voltage of the secondary battery is compared with the voltage of the secondary battery so that the voltage of the secondary battery is controlled to be less than the upper limit voltage. The secondary battery system according to claim 1, wherein the positive electrode of the secondary battery includes a positive electrode active material having a hexagonal layered structure. The secondary battery system according to claim 1 or 2, wherein the positive electrode of the secondary battery comprises a positive electrode active material having a composite oxide containing lithium and nickel. The secondary battery system according to claim 1 or 2, wherein the positive electrode of the secondary battery comprises a positive electrode active material having a composite oxide containing lithium and manganese. The secondary battery system according to claim 1 or 2, wherein the positive electrode of the secondary battery comprises a positive electrode active material having a composite oxide containing lithium and cobalt. A secondary battery holder for setting a lithium ion secondary battery to be charged,
A temperature sensor for measuring the temperature of the secondary battery,
A voltage sensor for measuring a voltage between the positive electrode and the negative electrode of the secondary battery,
And a control unit for controlling to lower the upper limit voltage of the secondary battery at the time of charging as the temperature of the secondary battery measured by the temperature sensor rises,
The control unit stores correspondence information composed of the temperature of the secondary battery and the upper limit voltage for setting the value of the negative electrode capacity / positive electrode capacity to a value larger than 1, and the upper limit voltage obtained from the corresponding information and the voltage And controls the voltage of the secondary battery to be less than the upper limit voltage by comparing the voltages of the secondary batteries.

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