JP2003282151A - Control method for non-aqueous secondary battery module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method for a non-aqueous secondary battery module constituted by connecting a plurality of cells of non-aqueous secondary battery (cell) for early detecting unevenness of cells and the executing control determined in advance. <P>SOLUTION: In this control method for the non-aqueous secondary battery module constituted by connecting a plurality of cells of non-aqueous secondary battery (cell) provided with non-aqueous electrolyte containing a positive electrode, a negative electrode, a separator, and lithium salt, a voltage of each cell is monitored to execute the control determined in advance when a difference in voltage between the minimum voltage and the maximum voltage of the cell exceeds a set value in a state of depth of discharge of the non-aqueous secondary battery module 80% or more. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for charging / discharging a non-aqueous secondary battery, and more particularly to a method for controlling a non-aqueous secondary battery module for a power storage system.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of effective use of energy and resource saving for the purpose of resource saving and global environmental problems, a distributed power storage system for home use for electric power storage of late night electric power storage and solar power generation Power storage systems are attracting attention. For example, in Japanese Patent Laid-Open No. 6-86463,
As a system capable of supplying energy to energy consumers under optimum conditions, a total system combining electricity supplied from a power plant, gas cogeneration, a fuel cell, a storage battery, etc. has been proposed. The secondary battery used in such a power storage system has an energy capacity of 10
Unlike a small secondary battery for mobile devices of Wh or less, a large one having a large capacity is required. Therefore, in the above-described power storage system, a plurality of secondary batteries are usually stacked in series and used as an assembled battery having a voltage of, for example, 50 to 400 V. In most cases, lead batteries have been used.

On the other hand, in the field of small secondary batteries for portable equipment, nickel hydrogen batteries and lithium secondary batteries have been developed as new type batteries to meet the needs of small size and high capacity, and volume energy of 180 Wh / l or more has been developed. Batteries having a density are commercially available. Especially, the lithium-ion battery
Since it has a volume energy density of more than 350 Wh / l, and is superior in reliability such as safety and cycle characteristics to a lithium secondary battery using metallic lithium as a negative electrode, its market is dramatically increased. It has been postponed.

In response to this, even in the field of large batteries for power storage systems, lithium ion batteries are targeted as a candidate for high energy density batteries, and vigorous development is underway at the lithium battery power storage technology research association (LIBES) and the like. Has been.

The energy capacity of these large-sized lithium ion batteries is about 100 Wh to 400 Wh, and the volume energy density is 200 to 300 Wh / l, which is about the same level as small secondary batteries for portable devices. Its shape is
Diameter 50mm-70mm, Length 250mm-450mm
The cylindrical type, the flat type having a thickness of 35 mm to 50 mm, the oblong rectangular type, or the like having a thickness of 35 mm to 50 mm is typical.

However, although these large-sized lithium-ion batteries can obtain high energy density, their battery design is an extension of small batteries for portable devices, so that the diameter or thickness is more than three times that of small batteries for portable devices. The battery has a cylindrical shape, a rectangular shape, or the like. In this case, heat is likely to be accumulated inside the battery due to Joule heat generation due to internal resistance of the battery during charging / discharging, or internal heat generation of the battery due to change in entropy of the active material due to entry and exit of lithium ions. Therefore, there is a large difference between the temperature inside the battery and the temperature near the battery surface, and the internal resistance varies accordingly. As a result, variations in charge amount and voltage are likely to occur. Further, since a plurality of batteries of this type are used as an assembled battery, the easiness of heat storage also varies depending on the installation position of the batteries in the system, which causes variations among the batteries, and accurate control of the entire assembled battery is possible. It will be difficult.

In order to solve the above problem, W099 / 60
No. 652, JP 2000-251940 A, JP 200
No. 0-251941, JP-A-2000-260478, and JP-A-2000-260477 disclose flat-shaped non-aqueous electrolytes containing a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte containing a lithium salt in a battery container. A secondary battery, wherein the non-aqueous secondary battery has a flat shape with a thickness of less than 12 mm, and has an energy capacity of 30 Wh or more and a volume energy density of 180 Wh / l or more. Has been done. Due to the unique battery shape (flat shape) of the battery, in a non-aqueous secondary battery module in which a plurality of cells of these batteries are connected, the temperature variation among the individual cells in the module is small.

A large battery for a power storage system is required to have an excellent cycle life of, for example, more than 3500 cycles (several hundred cycles to 1000 cycles in the case of a small secondary battery), and naturally, a plurality of cells are connected. It is necessary to secure cycle life in the battery module. Generally, the characteristics of the unit cell are not directly reflected on the module, and in particular, the deterioration of the module characteristic due to the dispersion of the unit cell poses a problem.

When the lithium ion battery is modularized, single cell control for monitoring the voltage of the single battery is usually performed for the purpose of safety to prevent overcharge and overdischarge. Also,
When the cells with high internal resistance reach the charge regulation voltage first due to the variation of the cells, the bypass circuit controls the charging of only the cells concerned or the control to reduce the charging current is performed. Various controls have been made to bring the characteristics of a module in which a plurality of cells are connected together closer to the characteristics of a single cell. However, the accuracy of ICs that monitor single cells tends to improve year by year, but considering cost, the limit is about 25 mV, and in order to judge battery variations, at least the voltage variations of the single cells must be considered. twenty five
mV to 50 mV or more is required. At present, the battery variation is controlled by the cell voltage during charging as described above, and the lithium-ion battery having a relatively flat charging potential curve, particularly the manganese positive electrode and the lithium-ion battery using graphite for the negative electrode, When a voltage difference of 25 mV occurs, there is a considerable variation (for example, about 10% in the charged state) among the single cells. The variation between the cells is a cause of shortening the module cycle life, and it is necessary to detect and control the variation between the cells at an earlier stage.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to determine in advance a non-aqueous secondary battery module in which a plurality of non-aqueous secondary batteries (single cells) are connected, by detecting variations in the single cells at an early stage. Another object of the present invention is to provide a control method of a non-aqueous secondary battery module capable of executing such control.

[0011]

In order to achieve the above object, the present invention provides the following method for controlling a non-aqueous secondary battery module.

Item 1. In a non-aqueous secondary battery module in which a plurality of non-aqueous secondary batteries (single cells) having a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte containing a lithium salt are connected, the voltage of each single cell is monitored to A non-aqueous system characterized by executing a predetermined control when the voltage difference between the minimum voltage and the maximum voltage of a single battery exceeds a set value when the depth of discharge of the secondary battery module is 80% or more. Rechargeable battery module control method.

Item 2. The depth of discharge of the non-aqueous secondary battery module is 80% to 100%, the set value of the voltage difference between the minimum voltage and the maximum voltage of the unit cell is about 25 mV to 500 mV, and the predetermined control is for the unit cell. The control method for a non-aqueous secondary battery module according to claim 1, wherein the control is for leveling out variations in charge / discharge states.

Item 3. The thickness of the non-aqueous secondary battery is 12 m
Item 3. The method for controlling a non-aqueous secondary battery module according to Item 1 or 2, which has a flat shape of less than m and has an energy capacity of 30 Wh or more and a volume energy density of 180 Wh / l or more.

Item 4. Item 3. The method for controlling a non-aqueous secondary battery module according to Item 1 or 2, wherein the positive electrode is mainly composed of manganese oxide.

Item 5. Item 3. The method for controlling a non-aqueous secondary battery module according to Item 1 or 2, wherein the negative electrode contains a substance capable of doping and dedoping lithium.

Item 6. Item 6. The method for controlling a non-aqueous secondary battery module according to Item 5, wherein the negative electrode is mainly composed of a graphite material.

Item 7. Item 7. The method for controlling a non-aqueous secondary battery module according to any one of Items 1 to 6, wherein the front and back surfaces of the flat shape are rectangular.

Item 8. Item 8. The method for controlling a non-aqueous secondary battery module according to any one of Items 1 to 7, wherein the battery container has a plate thickness of 0.2 mm or more and 1 mm or less.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a flat non-aqueous battery (unit cell) used in the non-aqueous secondary battery module of the present invention will be described below. FIG. 1 is a plan view and a side view of a flat rectangular (notebook type) non-aqueous secondary battery for a power storage system, and FIG. 2 shows a configuration of an electrode laminate housed inside the battery shown in FIG. It is a side view shown.

As shown in FIGS. 1 and 2, the non-aqueous secondary battery includes a battery container including an upper lid 1 and a bottom container 2, and a plurality of positive electrodes 101a and negative electrodes 1 housed in the battery container.
01b and 101c, and the electrode laminated body which consists of the separator 104. In the case of the flat non-aqueous secondary battery as in the embodiment, the positive electrode 101a and the negative electrode 101b (or the negative electrodes 101c arranged on both outer sides of the laminated body) may have a separator 104, for example, as shown in FIG. The layers are alternately arranged through the layers to be laminated, but the arrangement is not particularly limited, and the number of layers and the like can be variously changed according to the required capacity and the like. The shape of the non-aqueous secondary battery shown in FIGS. 1 and 2 is, for example, 300 mm in length × 210 mm in width × 6 mm in thickness, and LiMn ₂ O ₄ is used as the positive electrode 101 a and negative electrode 1 is used as the negative electrode 1.
In the case of a lithium secondary battery using a carbon material for 01b and 101c, it can be used, for example, in a power storage system.

The positive electrode current collector 105a of each positive electrode 101a is
It is electrically connected to the positive electrode terminal 3, and similarly, each negative electrode 101
The negative electrode current collectors 105b of b and 101c are electrically connected to the negative electrode terminal 4. The positive electrode terminal 3 and the negative electrode terminal 4 are
It is attached in a state of being insulated from the battery container, that is, the upper lid 1.

The upper lid 1 and the bottom container 2 are welded together by melting the upper lid around the entire circumference at point A shown in the enlarged view of FIG. An electrolyte injection port 5 is opened in the upper lid 1,
After injecting the electrolytic solution, for example, the sealing film 6 made of an aluminum-modified polypropylene laminate film is used for sealing. The final sealing step is more preferably performed after at least one charging operation. The pressure in the battery container after the final sealing step with the sealing film 6 is preferably less than atmospheric pressure, more preferably 8.66 × 10.
⁴ Pa (650 Torr) or less, particularly preferably 7.33
It is not more than × 10 ⁴ (550 Torr). This is because when the internal pressure is equal to or higher than the atmospheric pressure, the battery tends to be larger than the designed thickness, or the thickness of the battery tends to vary greatly, and further, the internal resistance and capacity of the battery tend to vary. This pressure is determined in consideration of the separator used, the type of electrolyte, the material and thickness of the battery container, the shape of the battery, and the like.

The positive electrode active material used for the positive electrode 101a is not particularly limited as long as it is a lithium-based positive electrode material, and lithium composite cobalt oxide, lithium composite nickel oxide, lithium composite manganese oxide, or a mixture thereof. Further, a system in which one or more different metal elements are added to these composite oxides can be used, and a high-voltage, high-capacity battery can be obtained, which is preferable. Further, when importance is placed on safety, which is the most important issue in the practical application of large-sized lithium secondary batteries, manganese oxide having a high thermal decomposition temperature is preferable. This manganese oxide is LiMn ₂ O ₄
Lithium complex manganese oxide represented by, and a system in which one or more dissimilar metal elements are added to these complex oxides, and Li _{1 + x} Mn containing lithium in excess of the stoichiometric ratio.
_{2-yO 4 and the} like can be mentioned. In particular, the effect is great when the positive electrode mainly containing the manganese oxide is used.

The negative electrode active material used for the negative electrodes 101b and 101c is not particularly limited as long as it is a lithium-based negative electrode material, and it is a material capable of doping and dedoping lithium, such as safety and cycle life. This is preferable because it improves reliability. As a material capable of doping and dedoping lithium, a graphite-based material, a carbon-based material, a tin oxide-based material used as a negative electrode material of a known lithium-ion battery,
Examples thereof include metal oxides such as silicon oxides, and conductive polymers represented by polyacene organic semiconductors. In particular, when the negative electrode mainly composed of the above-mentioned graphite material is used, its effect is great.

The structure of the separator 104 is not particularly limited, but a single-layer or multi-layer separator can be used, and it is preferable to use at least one nonwoven fabric. In this case, cycle characteristics are improved. . The material of the separator 104 is not particularly limited, and examples thereof include polyolefins such as polyethylene and polypropylene, polyamide, kraft paper, glass, and cellulosic materials, and the like, depending on the heat resistance and safety design of the battery. It is decided as appropriate.

As the electrolyte of the non-aqueous secondary battery, a known non-aqueous electrolyte containing a lithium salt can be used,
It is appropriately determined depending on the use conditions such as the positive electrode material, the negative electrode material, the charging voltage, and more specifically, LiPF ₆ , LiBF ₄ , Li
Lithium salt such as ClO ₄ , propylene carbonate,
Examples thereof include ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, dimethoxyethane, γ-butyrolactone, methyl acetate, methyl formate, and those dissolved in an organic solvent such as a mixed solvent of two or more of these. The concentration of the electrolytic solution is not particularly limited, but is generally 0.5 mol / l.
Is practically 2 mol / l, and as a matter of course, it is preferable to use an electrolytic solution having a water content of 100 ppm or less. The non-aqueous electrolyte used in the present specification means a concept including a non-aqueous electrolyte solution and an organic electrolyte solution, and also a concept including a gel or solid electrolyte.

The energy capacity of the non-aqueous secondary battery constructed as described above is preferably 30 Wh or more, more preferably 50 Wh or more, and the energy density is preferably 180 Wh / l or more, more preferably 200 W.
h / l. If the energy capacity is less than 30 Wh,
Alternatively, when the volume energy density is less than 180 Wh / l, the capacity is small for use in an electricity storage system, and it is necessary to increase the number of series-parallel batteries to obtain sufficient system capacity, and a compact design is required. It is difficult to use for a power storage system because it becomes difficult.

The non-aqueous secondary battery has a flat shape,
Its thickness is less than 12 mm, more preferably less than 10 mm. The lower limit of the thickness is practically 2 mm or more in consideration of the filling rate of the electrodes and the battery size (the smaller the area, the larger the area for obtaining the same capacity). When the thickness of the battery is 12 mm or more, it becomes difficult to sufficiently dissipate the heat generated inside the battery to the outside, or the temperature difference between the inside of the battery and the surface of the battery becomes large, resulting in a difference in internal resistance. The variations in the charge amount and voltage of the battery become large. The specific thickness is appropriately determined depending on the battery capacity and the energy density, but it is preferable to design the thickness with the maximum thickness at which the expected heat dissipation characteristics can be obtained.

As the shape of the non-aqueous secondary battery, for example, the flat surface can have various shapes such as square, circular, and oval, and the square is generally rectangular. It can also be a polygon such as a triangle or a hexagon. Further, it may be formed in a tubular shape such as a thin cylinder. In the case of a cylinder, the thickness of the cylinder is the thickness here.
Further, from the viewpoint of ease of manufacturing, the flat shape of the battery has a rectangular front and back surfaces, and a notebook shape as shown in FIG. 1 is preferable.

The materials used for the upper lid 1 and the bottom container 2 which are the battery container are appropriately selected depending on the use and shape of the battery,
The material is not particularly limited, and iron, stainless steel, aluminum, etc. are common and practical. The thickness of the battery container is also appropriately determined depending on the use and shape of the battery or the material of the battery case, and is not particularly limited. Preferably, the thickness of 80% or more of the surface area of the battery (the thickness of the widest part of the battery container) is 0.2 mm or more. If the thickness is less than 0.2 mm, the strength required for battery production cannot be obtained, which is not desirable. From this viewpoint, the thickness is more preferably 0.3 mm or more. The thickness of the same portion is preferably 1 mm or less. If this thickness exceeds 1 mm, the force to press down the electrode surface becomes large, but it is not desirable because the internal volume of the battery decreases and a sufficient capacity cannot be obtained, or the weight becomes heavy. Preferably 0.
It is 7 mm or less.

As described above, the thickness of the non-aqueous secondary battery is 1
By designing it to be less than 2 mm, for example, the battery is
When the battery has a large capacity of 0 Wh or more and a high energy density of 180 Wh / l, excellent heat dissipation characteristics can be realized and a rise in battery temperature can be suppressed even during high-rate charging / discharging. Therefore, the heat storage of the battery due to internal heat generation is reduced,
As a result, thermal runaway of the battery can be suppressed, and a non-aqueous secondary battery excellent in reliability and safety can be provided.

The non-aqueous secondary battery (single battery) configured as described above is a non-aqueous battery module in which a plurality of cells are connected to each other, and is used as a household power storage system (night power storage, cogeneration, solar power generation, etc.). It can be used for a power storage system of an electric vehicle or the like.

The non-aqueous battery module according to the present invention will be described below. The non-aqueous battery module in the present invention is, for example, one in which a plurality of the flat type non-aqueous secondary battery batteries (unit cells) are connected in series, and when used in an electricity storage system, the number is generally 4 cells or more. , Up to 1
It is about 00 cells. For example, when eight cells (designed so that they can be charged / discharged at 4.2V-3.0V) are connected in series, the charging / discharging of the module is controlled at 33.6V-24V. However,
If there are variations in the unit cells, the unit cells that are charged and discharged are 4.
It may be charged above 2V and some cells may be charged below 4.2V. In a lithium-ion battery, when there is extreme cell variation such as when the voltage exceeds the specified upper limit voltage or drops below the specified lower limit voltage (for example, one cell is charged at 4.5V in the above example). Or when discharged to 2.5V), monitor each battery voltage for safety reasons,
Stop charging and discharging the module. In this case, the voltage monitoring accuracy of 25 mV is sufficient, and there is no particular problem. However, it is possible to detect the variation of the battery and suppress the variation of the single cell or to control in response to the variation (for example, when the variation occurs, level each cell, increase the charging reference voltage of the battery with large deterioration). If implemented, it is necessary to detect battery variations more accurately.

According to the control method of the present invention, a predetermined control is performed when the voltage difference between the minimum voltage and the maximum voltage of the unit cell is equal to or more than the set value in the state where the depth of discharge of the non-aqueous secondary battery module is 80% or more. To execute. That is, when the capacity of the module is 100 Ah, the voltage of the cells at the end of discharge, which is discharged by 80% or more, is compared to determine the variation of the cells.
The depth of discharge is preferably 80% to 100%, more preferably 90% to 100%. According to this control method, compared to the conventional method of controlling the voltage during charging, it is possible to detect the battery variation earlier, and it is possible to suppress the cell variation or perform control corresponding to the variation, and minimize the module deterioration due to the variation. It is possible to stop. The voltage difference between the minimum voltage and the maximum voltage of the unit cell can be appropriately selected depending on the types of the unit cell and the module, but can be set to, for example, about 25 mV to 500 mV, preferably about 50 mV to 250 mV. When the set value is low, the measurement of the potential difference and the calculation unit become complicated, which is not practical, and when the set value exceeds the upper limit, the dispersion of the unit cells is progressing, and it is preferable from the viewpoint of controlling at an appropriate time. Absent.

The predetermined control is a control for leveling the variations in the charge / discharge states of the unit cells, for example, a control for leveling the charge / discharge state by bypassing the charge / discharge current of only a specific cell, all batteries. And the like, which are connected in parallel to level the charge / discharge state. Regarding this leveling control, it is not necessary to execute it at the same time when the difference between the minimum voltage and the maximum voltage reaches the set value, and for example, after reaching the set value, it is possible to carry out the next charging or discharging. It is also possible to warn the user and execute the leveling control at a time convenient for the user.

[0037]

EXAMPLES The present invention will now be described more specifically by showing examples of the present invention.

(1) First, LiMn ₂ O ₄ as a lithium manganese composite oxide, LiNi _0.8 Co _0.2 O ₂ as a lithium nickel composite oxide and acetylene black as a conductive material were dry-mixed to obtain a mixture. Was uniformly dispersed in N-methyl-2-pyrrolidone (NMP) in which polyvinylidene fluoride (PVDF) as a binder was dissolved to prepare slurry-1. At this time, the solid content ratio (weight ratio) in the positive electrode was calculated as follows: lithium lithium manganate: lithium lithium nickel oxide:
Acetylene black: PVDF = 74: 18: 3: 5. Next, Slurry-1 was applied on both sides of an aluminum foil serving as a current collector, dried and then pressed to obtain a positive electrode.

FIG. 3A is an explanatory view of the positive electrode. In this embodiment, the coating area (W1 × W2) of the positive electrode 101a is 130
× 177 mm ² . Further, on the short side of the electrode, a current collecting portion 106a to which no electrode is applied is provided, and a hole having a diameter of 3 mm is opened in the center thereof.

(2) On the other hand, double structure graphite particles (trade name "OPCG-K", manufactured by Osaka Gas Chemicals; graphite particle core (002)
Surface spacing (d002) = less than 0.34 nm, coating layer (002) surface spacing (d002) = 0.34 nm or more), graphitized mesocarbon microbeads (MCMB, Osaka Gas Chemicals, product number "25-28""; (00
2) The interplanar spacing (d002) = less than 0.34 nm) and the conductive material acetylene black are dry-mixed, and then uniformly dispersed in NMP in which PVDF, which is the binder, is dissolved to form a slurry-
2 was prepared. The solid content ratio (weight ratio) in the negative electrode was double structure graphite particles: graphitized mesocarbon microbeads: acetylene black: PVDF = 64: 28: 2: 6. Then, slurry-2 is applied to both sides of a copper foil serving as a current collector, and after drying,
It pressed and the negative electrode was obtained. The density of the obtained negative electrode is 1.45.
It was g / cc.

FIG. 3- (b) is an explanatory view of the negative electrode. Negative electrode 1
The application area (W1 × W2) of 01b is 133 × 181.5 mm ² .
Further, on the short side of the electrode, a current collecting portion 106b to which no electrode is applied is provided, and a hole having a diameter of 3 mm is formed in the center thereof.

Further, the slurry-2 was applied to only one surface by the same method as described above to prepare a single-sided electrode. The single-sided electrode is arranged outside in the electrode laminate of item (3) described later (101c in FIG. 2).

(3) As shown in FIG. 3, 9 sheets of the positive electrode obtained in the above (1) and 10 sheets of the negative electrode obtained in the above (2) (2 sheets on one side of the inside) were used as a separator material A. (Rayon non-woven fabric, basis weight 12.6 g / m ² ) and separator material B (polyethylene microporous membrane;
Alternately laminated through a basis weight 13.3 g / m ²⁾ and the separator 104 of the combined, further, place the further separator material B on the outside of the anode 101c of the outer for insulation between the battery container, electrode stack It was created. Note that the separator 104
Was placed so that the separator material A was located on the positive electrode side and the separator material B was located on the negative electrode side.

(4) As shown in FIG. 4, SUS30 having a thickness of 0.5 mm
The thin plate made of 4 was squeezed to a depth of 5 mm to make a bottom container 2, and the upper lid 1 was also made of a thin plate made of SUS304 having a thickness of 0.5 mm. Next, the positive electrode terminal 3 made of aluminum and the negative electrode terminal 4 made of copper (head diameter 6 mm, screw part of tip M3) were attached to the upper lid 1.
The positive electrode and negative electrode terminals 3 and 4 were insulated from the upper lid 1 by a polypropylene gasket.

(5) The holes of the positive electrode current collectors 106a of the electrode laminate prepared in the above item (3) are inserted in the positive electrode terminal 3 and the holes of the negative electrode current collectors 106b are inserted in the negative electrode terminal 4, respectively. After connecting with bolts made of copper and copper, the connected electrode laminate was fixed with an insulating tape, and the corner portion A in FIG. 1 was laser-welded over the entire circumference. Next, after decompressing the inside of the battery with a vacuum pump, from a liquid injection port 5 (diameter 6 mm), 70 g of ethylene carbonate and dimethyl carbonate were mixed in a volume ratio of 30:70, and LiPF ₆ was added to a concentration of 1 mol / l. The dissolved electrolytic solution (3% additive) was injected, and the time was measured. Next, the liquid injection port 5 was once sealed under atmospheric pressure using a temporary fixing bolt, and the battery was initially charged.

(6) The rated capacity of this battery is 11.5 Ah, and the current at 10-hour rate is 1.15 A. Initial charging current
After charging up to 4.2V with 0.5A, 1A, 2A, constant current constant voltage charging with constant voltage of 4.2V for 8 hours in total, followed by 2
It was discharged to 2.5V with a constant current of A.

(7) Next, after removing the temporary fixing bolts of the battery, under reduced pressure of 4 × 10 ⁴ Pa (300 Torr), a 0.08 mm thick aluminum foil-modified polypropylene laminated film punched out to a diameter of 12 mm Sealing film 6 consisting of
Final sealing of injection port 5 by heat fusion under conditions of temperature 250-350 ° C, pressure 1-3 kg / cm ² , pressurization time 5-10 seconds, width 148 mm x height 210 mm x thickness A 6.4 mm flat notebook battery was obtained.

A battery module in which eight of the batteries were connected in series was prepared, the module was charged to 33.2 V at a current of 2 A, and discharged to 26.4 V at a constant current of 2 A was repeated. The voltage of each unit cell was monitored, and the number of cycles at which the maximum voltage and the minimum voltage difference of the unit cell were 50 mV was measured.
When the module voltage was monitored at 33.2V (depth of discharge 0%), the potential difference that was 8 mV in the first cycle was 25 mV or less in 250 cycles, but the module voltage was 26.4V.
When monitored at a discharge depth of 100%, the first cycle is 15 mV
The potential difference was 50 mV after 50 cycles, and it was possible to detect the variation early.

(8) After sensing the variation, 8 cells were connected in parallel and left for 12 hours to level the voltage variation of each unit cell. After leveling, 8 cells are connected again in series and charging / discharging is repeated 5 times. When the module voltage becomes 26.4V, the minimum and maximum voltage difference of the unit cell is 20mV, and the variation is 50
It was smaller than the cycle eye.

[0050]

According to the control method of the non-aqueous secondary battery module of the present invention, it is possible to detect the variation of the single cell at an early stage, and to suppress the variation of the single cell from an earlier stage or perform the control corresponding to the variation. As a result, it is possible to take measures against module deterioration due to battery variations at an early stage.

[Brief description of drawings]

FIG. 1 is a diagram showing a plan view and a side view of a non-aqueous secondary battery for a power storage system according to an embodiment of the present invention.

FIG. 2 is a side view showing a configuration of an electrode laminated body housed inside the battery shown in FIG.

FIG. 3 is a plan view of a positive electrode, a negative electrode, and a separator that form the laminated body shown in FIG.

FIG. 4 is a cross-sectional view showing a state in which an upper lid and a bottom container of the battery shown in FIG. 1 are separated.

[Explanation of symbols]

1 Top cover 2 bottom containers 3 Positive terminal 4 Negative electrode terminal 5 Injection port 6 sealing film 101a Positive electrode (both sides) 101b Negative electrode (both sides) 101c Negative electrode (one side) 104 separator 105a Positive electrode current collector 105b Negative electrode current collector 106a Positive electrode current collector piece 106b Negative electrode current collector piece

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroyuki Tajiri             4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Within Osaka Gas Co., Ltd. (72) Inventor Kazuya Kuriyama             4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Kansai Research Institute of Technology (72) Inventor Shiro Kato             4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Kansai Research Institute of Technology (72) Inventor Shizukuni Yada             4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Kansai Research Institute of Technology F term (reference) 5H011 AA06 BB05 CC06 DD01 KK01                 5H030 AA01 AS01 AS06 BB01 BB21                       FF41 FF44

Claims (8)

[Claims] 1. A non-aqueous secondary battery module in which a plurality of non-aqueous secondary batteries (single batteries) each including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte containing a lithium salt are connected to each other. If the voltage difference between the minimum voltage and the maximum voltage of the single cell is more than the set value when the depth of discharge of the non-aqueous secondary battery module is 80% or more,
A control method for a non-aqueous secondary battery module, which is characterized by executing a predetermined control. 2. The depth of discharge of the non-aqueous secondary battery module is 80% to 100%, the set value of the voltage difference between the minimum voltage and the maximum voltage of the unit cell is about 25 mV to 500 mV, which is predetermined. The control method for a non-aqueous secondary battery module according to claim 1, wherein the control is control for equalizing variations in charge / discharge states of the unit cells. 3. The non-aqueous secondary battery according to claim 1, wherein the non-aqueous secondary battery has a flat shape with a thickness of less than 12 mm, an energy capacity of 30 Wh or more and a volume energy density of 180 Wh / l or more. Control method for secondary battery module. 4. The method for controlling a non-aqueous secondary battery module according to claim 1, wherein the positive electrode is mainly composed of manganese oxide. 5. The method for controlling a non-aqueous secondary battery module according to claim 1, wherein the negative electrode contains a material capable of doping and dedoping lithium. 6. The method for controlling a non-aqueous secondary battery module according to claim 5, wherein the negative electrode is mainly composed of a graphite-based material. 7. The method for controlling a non-aqueous secondary battery module according to claim 1, wherein the shape of the front and back surfaces of the flat shape is rectangular. 8. The plate thickness of the battery container is 0.2 mm or more 1
The method for controlling the non-aqueous secondary battery module according to any one of claims 1 to 7, wherein the control method is less than or equal to mm.