JPH11126585A - Battery pack and electric appliance using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery pack in which decrease in the weight energy density of battery is suppressed and the cooling efficiency is enhanced. SOLUTION: A plurality of rectangular nonaqueous electrolyte secondary unit cells equipped with a positive electrode, negative electrode, electrolyte, battery vessel, and battery lid, are arranged and electrically connected in series and/or in parallel, so that they become a battery. In this battery spacers 44 made of insulative plastics or rubber are sandwiched between the side faces of the unit cells 43 to connect them/into the battery pack.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte secondary battery, and more particularly to an assembled battery using a prismatic lithium secondary battery.

[0002]

2. Description of the Related Art Non-aqueous electrolyte secondary batteries represented by lithium secondary batteries have higher energy densities than lead-acid batteries and nickel-cadmium batteries, and have recently been used in video cameras, portable telephones, notebook computers, etc. Used in portable electrical devices.

The negative electrode active material of a lithium secondary battery includes lithium metal, a carbon material capable of storing lithium ions, and the like. The positive electrode active material includes a transition metal such as cobalt, nickel or manganese and lithium. Complex oxides are used.

[0004] In particular, oxides composed of manganese and lithium include LiMn ₂ O ₄ having a spinel structure (Japanese Patent Publication No.
No. 8-34414) has attracted attention as a positive electrode material for large-sized lithium secondary batteries for power storage or electric vehicles because of its low price and abundant resources.

In such a large assembled battery, since the energy density of one battery is reduced by using the assembled battery, a packaging technology that is as compact and lightweight as possible is essential. In particular, in an assembled battery using a cylindrical lithium secondary battery, the volume energy density of the assembled battery is reduced by about 70% as compared with the case of a single battery. Therefore,
There is a demand for an optimal method for fixing the lithium secondary battery and arranging the control circuit board of the assembled battery so that the energy density of the assembled battery is as high as possible.

Further, in such an assembled battery, management of heat generated during charging and discharging of the battery is an important issue. As an example of a method of cooling an assembled battery, a method of inserting a metal beam spacer between prismatic lithium secondary batteries (Japanese Patent Laid-Open No. 8-2)
No. 12986).

[0007]

When a cylindrical battery is used as an assembled battery, the number of voids increases and the volume energy density of the assembled battery is greatly reduced. Therefore, focusing on prismatic batteries that are easier to fill than cylindrical batteries, the arrangement and fixing method of prismatic lithium secondary batteries with an increased energy density of the assembled battery, and a control circuit board for controlling the assembled battery I studied diligently about the arrangement of the.

In addition, when charging and discharging a battery pack composed of a large lithium secondary battery, it is known that increasing the current value increases the battery temperature by several tens of degrees Celsius (The 13th Interter).
national Eelectric Vehicle Symposium, p. 37, 1996). The heat generated causes the electrodes of the lithium secondary battery to deteriorate, and thus cooling during charging and discharging is important for extending the life of the battery.

When a metal material is used for the spacer, the heat transfer between the batteries is improved, but the weight energy density of the assembled battery is reduced because the metal material has a high specific gravity.

A first object of the present invention is to provide a lightweight and compact battery pack.

A second object of the present invention is to provide an assembled battery in which a decrease in weight energy density of the battery is suppressed and cooling efficiency is improved.

A third object of the present invention is to provide an electric device using the battery pack.

[0013]

Means for Solving the Problems The positions of the electrode terminals on the lid of the prismatic lithium secondary battery, the positions of the electrolyte inlet and the vent and the structure thereof are examined, and a means for securing the installation place of the control circuit board is found. Was.

Further, it is possible to provide an assembled battery in which the positive terminal and the negative terminal of the assembled battery are fixed by insulating parts, and no external container is required.

(1) Positive electrode, negative electrode, electrolyte, battery container,
In an assembled battery in which a plurality of square-shaped non-aqueous electrolyte secondary cells having a battery cover are arranged and electrically connected in series or / and in parallel, a control circuit is provided above the battery cover of the battery. The assembled battery is characterized in that the substrate is installed, and the supporting plate and the insulating parts abutting on the side surfaces of the two unit cells at both ends are integrally connected with each other.

(2) The battery lid has an electrolyte inlet, a positive electrode terminal, and a negative electrode terminal, and an end of the electrolyte inlet is lower than upper ends of the positive electrode terminal and the negative electrode terminal. In the above-mentioned assembled battery.

(3) In the battery pack, the support plate is a metal plate having a rib structure.

Further, the present inventors have repeatedly studied to achieve the above-mentioned second object, and by connecting an insulating spacer to the side surface of a prismatic lithium secondary battery to connect a plurality of batteries, We have found a means by which heat generated by batteries can be efficiently radiated from the space created between the batteries.

(4) Positive electrode, negative electrode, electrolyte, battery container,
In an assembled battery in which a plurality of square-shaped nonaqueous electrolyte secondary cells having a battery lid are arranged and electrically connected in series or / and in parallel, an insulating plastic is provided on a side surface of the cell. Alternatively, there is provided an assembled battery in which a spacer formed of rubber is sandwiched and connected.

(5) In the above battery module, a spacer is inserted between the unit cells, and an air passage formed between the spacer and a side surface of the unit cell is provided.

(6) The battery pack is housed in a container, wherein the container has a vent hole.

(7) An electric device characterized in that the above-mentioned battery pack is mounted as a power source.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The positive electrode of a prismatic lithium secondary battery
A positive electrode active material, a conductive agent, a binder, and a current collector are provided.

The cathode active material which can be used in the present invention is represented by the following chemical formula: LiCoO ₂ , LiNiO ₂ , LiMn
₂ O ₄ and the like. Since these positive electrode active materials have high electric resistance, electric conductivity is supplemented by mixing a small amount of carbonaceous powder as a conductive agent. Since both the positive electrode active material and the conductive agent are powders, a binder is mixed with the powders so that the powders are bonded to each other and simultaneously bonded to the current collector. Aluminum foil is used for the current collector.

A positive electrode slurry in which a positive electrode active material, a conductive agent, a binder, and an organic solvent are mixed is attached to a current collector by a doctor blade method, a dipping method, and the like, and then the organic solvent is dried and pressure-formed by a roll press. By doing so, a positive electrode can be manufactured.

The negative electrode of the prismatic lithium secondary battery comprises a negative electrode active material, a binder, and a current collector. The negative electrode active material used in the present invention includes aluminum, lead, silver, and the like, which are alloyed with lithium. Further, a composite material in which these metals are supported on carbon is preferable, but other materials than those described above can also be used.

Since the negative electrode active material used is a powder, a binder is mixed, and the powders are bonded to each other and simultaneously bonded to the current collector. Copper foil is used for the current collector.

A negative electrode slurry obtained by mixing a negative electrode active material, a binder, and an organic solvent is attached to a current collector by a doctor blade method, a dipping method, or the like, and then the organic solvent is dried and pressure-formed by a roll press. ,
A negative electrode can be manufactured.

FIG. 1 shows an example of the prismatic lithium secondary battery of the present invention. The battery cover 1 is made of a metal material such as stainless steel, aluminum, and nickel-plated steel. The opening of the battery can 2 made of the same material as the battery lid 1 is welded by a laser or an electron beam.

The positive electrode 3 and the negative electrode 5 are strip-shaped. The tab on the upper part of the positive electrode 3 is connected to the lower part of the positive electrode terminal 4 penetrating the insulating disk 8 and the battery lid 1. The positive terminal 4 is
It has a shape that can be fixed to the threaded terminal rod from the outside of the battery with a nut. Desirably, the material of the terminal rod is aluminum, and the material of the nut is stainless steel or aluminum.

Similarly, the negative electrode 5 has a negative electrode tab connected to a lower portion of the negative electrode terminal 6. The negative electrode terminal 6 has a shape that can be fixed to a threaded terminal rod from the outside of the battery with a nut. Desirably, the material of the terminal rod is copper, and the material of the nut is stainless steel.

The positive terminal 4 and the negative terminal 6 are both connected to the battery cover 1.
Is electrically insulated by an insulating disc. An organic polymer material such as polypropylene can be used for the insulating disc. The separator 7 is used to separate the positive electrode 3 and the negative electrode 5 and at the same time hold the electrolytic solution.

For the heat radiation of the battery, as a separator inserted between each electrode in which a strip-like positive electrode and negative electrode are alternately laminated,
Insert a polymer microporous separator such as polyethylene or polypropylene. As another method, the separator can be inserted and wound to form a flat, elliptical wound electrode group.

The electrode group produced as described above is inserted into a rectangular battery container made of aluminum, stainless steel, nickel-plated steel or the like, and the electrodes are welded to external terminals attached to the lid, and then the lid and the battery container are welded. Next, an electrolyte is injected from the liquid inlet 9 of the lid, and the liquid inlet is sealed,
The prismatic lithium secondary battery is completed.

As a typical example of the electrolytic solution usable in the present invention, there is a solution obtained by dissolving lithium hexafluorophosphate as an electrolyte in a solvent obtained by mixing dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate and the like with ethylene carbonate. . However, in the present invention, the type of the solvent and the electrolyte and the mixing ratio of the solvent are appropriately selected, and other electrolytic solutions can be used.

In order to secure a space for installing the charge / discharge control circuit board on the battery cover 1, the electrolyte injection port and the vent should not protrude from the upper surface of the battery cover 1. The electrolyte injection port 9 is connected to the battery can 2 so as not to contact the positive electrode 3 and the negative electrode 5.
And is sealed with a bolt-shaped stopper 10 and a ring-shaped packing 11.

Metals such as aluminum, stainless steel, and titanium are used as the material of the bolt-shaped stopper 10, and polymer materials such as polypropylene and polytetrafluoroethylene, and aluminum, stainless steel, titanium, and copper are used as the material of the ring-shaped packing 11. Metal can be selected.

The upper surface of the bolt-shaped stopper 10 is cut out so that it can be rotated by a screwdriver. The vent for discharging the gas accumulated inside the battery includes a gas discharge port 12, a bolt-shaped stopper 13, and a ring-shaped packing 14. The gas outlet 12 protrudes toward the inside of the battery can 2 so as not to contact the positive electrode 3 and the negative electrode 5, and is sealed with a bolt-shaped plug 13 and a ring-shaped packing 14. The material of the bolt-shaped stopper 13 is preferably a metal such as aluminum, stainless steel, and titanium.

The ring-shaped packing 14 needs to be deformable within a range of several to 20 atm in order to release the internal pressure inside the battery. Accordingly, the material is preferably a polymer such as polypropylene or polytetrafluoroethylene, viton rubber, silicone rubber, polytetrafluoroethylene rubber, or the like.

The positive terminal and the negative terminal of the battery pack of the present invention
The fixing can be performed by the following method. FIG. 2 shows an assembled battery of the present invention. A plurality of prismatic lithium secondary batteries 1
5 are arranged in a line, and the metal plates 16 are brought into contact with the battery side surfaces at both ends. This metal plate has a smooth surface in contact with the side surface of the battery, and a rib process on the opposite side.
The strength of No. 6 is increased. The ribs are preferable because the strength can be improved by increasing the number of projections, and the heat dissipation from the side of the battery can be improved.

The metal plate 16 and the insulating component 17 are bolted
To fix the prismatic lithium secondary battery 15. The insulating component 17 is desirably L-shaped.

The prismatic lithium secondary batteries are connected in series or in parallel using a cable, and charge and discharge the batteries from the positive terminal 19 and the negative terminal 20 of the assembled battery fixed to the insulating component 17. The control circuit board 22 for controlling charging and discharging is shown in FIG.
As shown in FIG. 2, the L-shaped insulating component 1 is mounted between the positive terminal 4 and the negative terminal 6 of the prismatic lithium secondary battery, as shown in FIG.
Fixed at 7.

Examples of the insulating component 17 include polytetrafluoroethylene, phenol resin, and polycarbonate.

In the structure of the above-mentioned assembled battery, an outer container is not particularly required, so that the battery can be directly cooled by outside air, and the temperature rise of the battery at the time of rapid charging or high-load discharge can be suppressed. Further, the weight energy density and the volume energy density of the battery pack can be increased.

Further, a structure in which a plurality of prismatic lithium secondary batteries are connected in a plurality of rows can be adopted. Also, the external terminals of each battery may be connected in series or in parallel, so that electric energy can be extracted from the assembled battery through a pair of positive and negative terminals, or rechargeable.

When charging and discharging a rectangular lithium secondary battery, the battery generates heat due to Joule heat and heat of chemical reaction. Therefore, if the side surfaces of the individual cells are arranged in close contact with each other, the heat radiation becomes insufficient and the battery temperature rises abnormally. As a result, the cycle life of the battery is significantly reduced, and there is a danger of ignition or explosion due to a rise in temperature.

The above problem can be solved by inserting a lightweight spacer between the prismatic lithium secondary batteries and fixing each battery via the spacer.

Examples of the spacer include plastics such as polytetrafluoroethylene, polyethylene, polypropylene, polystyrene, ABS resin, polyester, epoxy resin, phenol resin, and polycarbonate.

Further, styrene butadiene rubber, acrylonitrile butadiene rubber, butadiene rubber, isoprene rubber, silicone rubber, fluorine rubber, urethane rubber,
Acrylic rubber can also be used.

From the above materials, spacers of various shapes such as a strip shape, a cross shape, and a comb shape are produced, and the spacers are inserted between unit cells. The thicker the spacer, the better the heat dissipation, but the lower the volume energy density of the battery pack. In order to suppress the reduction rate of the volume energy density of the battery pack using the spacer to about 10%, the spacer thickness needs to be less than 10% of the battery thickness. In the present invention, the thickness of the spacer is 0.1 to 1
Desirably, it is 0 mm.

In order to fix the battery and the spacer, it is preferable to use a metal plate and tighten the batteries at both ends inward. It is also effective to provide ventilation holes in the gaps between the batteries so that outside air can flow, so that heat can be radiated from the entire side surface of the batteries.

Since the spacer of the present invention uses a material that is lighter than metal, the increase is slight with respect to the weight of the assembled battery.

[0053]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail based on embodiments.

Example 1 The positive electrode active material was electrolytic MnO
₂ and Li ₂ CO ₃ or LiNO ₃ in air at 900
LiMn with spinel crystal structure by heat treatment at ℃
₂ O ₄ powder was synthesized and used.

The above powder has an average particle size of 15 μm and a specific surface area of 1.5 m ² / g measured by a nitrogen adsorption method. X
As a result of measuring the X-ray diffraction pattern of LiMn ₂ O ₄ powder using CuKα as a radiation source, the diffraction angle 2θ value was 17, 3
Since diffraction peaks typical of spinel crystals appeared at around 6, 38, 44 and 48, it was confirmed that the positive electrode active material of this example had a spinel crystal structure.

The positive electrode was manufactured according to the procedure described below. Li
Mn ₂ O ₄ powder, natural graphite, polyvinylidene fluoride 1-
A positive electrode slurry was obtained by adding a methyl-2-pyrrolidone solution and kneading the mixture sufficiently. The mixing ratio of LiMn ₂ O ₄ , natural graphite, and polyvinylidene fluoride is 90: 6: 4 by weight.
And This slurry was applied to the surface of a positive electrode current collector made of an aluminum foil having a thickness of 20 μm by a doctor blade method. The positive electrode has a rectangular shape with a width of 150 mm and a height of 120 mm. This positive electrode was dried at 100 ° C. for 2 hours.

The negative electrode was manufactured according to the following procedure. A natural graphite powder having an average particle diameter of 5 μm and silver nitrate were dispersed in a mixed solution of alcohol and water, and formaldehyde was added dropwise to reduce silver ions, and silver fine particles were supported on the surface of the graphite powder. This powder and polyvinylidene fluoride were mixed at a weight ratio of 9: 1, 1-methyl-2-pyrrolidone was added as an organic solvent, and the mixture was sufficiently kneaded to prepare a negative electrode slurry. This slurry was applied to the surface of a negative electrode current collector made of a copper foil having a thickness of 10 μm by a doctor blade method.

The negative electrode has a rectangular shape having a width of 150 mm and a height of 120 mm. This negative electrode was dried at 100 ° C. for 2 hours.

FIGS. 1A and 1B show a sectional structure of a prismatic lithium secondary battery of this embodiment, wherein FIG. 1A is a top view and FIG. 1B is a sectional view.

The external dimensions of the battery are 150 mm high × 16 wide.
It is 0 mm x 40 mm depth. In this example, the positive electrode 3 and the negative electrode 5 inserted in the bag-shaped separator 7 were alternately laminated.

Each electrode was welded to the positive electrode terminal 4 and the negative electrode terminal 6, respectively. The terminals 4 and 6 penetrate the battery lid 1 via an insulating disk 8 made of polypropylene. The vent, which is a pressure release valve inside the battery, includes a gas discharge port 12, a bolt-shaped stopper 13, and a ring-shaped packing 14.

After the battery can 2 made of aluminum and the battery lid 1 are laser-welded, an electrolytic solution is injected from the liquid inlet 9, and the liquid inlet 9 is sealed using a bolt-shaped stopper 10 and a ring-shaped packing 11. Was sealed. In this embodiment, 1 mol / liter equivalent of lithium hexafluorophosphate (LiPF) was added to an equal volume mixed solvent of ethylene carbonate and dimethyl carbonate.
₆ ) A non-aqueous electrolyte solution was used.

With this configuration, the electrochemical energy of the battery can be extracted to the outside from the positive electrode terminal 4 and the negative electrode terminal 6, and can be stored by recharging. The average discharge voltage of this battery is 3.8 V, the rated capacity is 65.8 Ah,
250 Wh.

As shown in FIG. 2, the above-described prismatic lithium secondary batteries 15 are arranged in a row so that the side surfaces having a width of 160 mm and a height of 150 mm face each other, and eight batteries are connected in series. Was assembled.

A ribbed metal plate 16 as a support plate is brought into contact with the side surfaces of the two batteries 15 located at both ends, and an L-shaped insulating part 17 made of phenol resin and a metal plate 1 are formed.
6 was connected by bolts 18. Eight batteries 15 were fixed by using two L-shaped insulating parts 17 at the upper part and two at the lower part of the assembled battery. The L-shaped insulating component 17 may be extended to the rib pressing surface of the metal plate 16, and may be connected to the metal plate 16 by penetrating a bolt 18 from the surface of the L-shaped insulating component 17.

Further, a control circuit board 22 was installed on the upper L-shaped insulating component 17 side, and charging / discharging was controlled while measuring the voltage of each battery constituting the assembled battery. The positive terminal 19 of the assembled battery and the negative terminal 20 of the assembled battery penetrate the upper L-shaped insulating component 17 and are fixed. The assembled battery of the present embodiment has a height of 195 mm × a width of 170 mm × a depth of 360 mm, and is represented by B1.

[Comparative Example 1] In this comparative example, the liquid inlet 9 and the gas outlet 12 of the battery lid shown in FIG. In this case, the bolt plugs 10 and 1
The upper surface of the head portion of No. 3 was higher than the upper surface of the battery lid 1 by about 7 mm. Eight batteries of this specification were connected in series with the same configuration as in Example 1, and an assembled battery was assembled.

A ribbed metal plate 16 is brought into contact with the side surfaces of the two batteries 15 located at both ends, and an L-shaped insulating part 17 made of phenol resin and a metal plate 16 are bolted.
Connected. Two L-shaped insulating parts 17 are provided on the upper part of the battery pack,
Eight batteries 15 were fixed using two at the bottom. Compared with Example 1, the height of the metal plate 16 was increased by 7 mm. Therefore, the control circuit board 22 is installed under the upper surface between the positive electrode terminal 4 and the negative electrode terminal 6 and under the upper L-shaped insulating component, and the charge and discharge are performed while measuring the voltage of each battery constituting the assembled battery. Controlled.

The positive terminal 19 and the negative terminal 20 of the battery pack are
It is fixed by penetrating the upper L-shaped insulating component 17. The assembled battery of this comparative example has a height of 205 mm × a width of 170 mm × a depth of 360 mm, and is referred to as B2.

The average discharge voltages of the assembled batteries B1 and B2 were 30.4 V and the rated capacity was 65.8 Ah and 2 kWh, respectively.

However, compared to the battery pack B1, the battery pack B
Since the battery height of the battery No. 2 was increased by 7 mm, the volume energy density of the battery pack B2 was 168 Wh / l to 159 Wh / l.
Has dropped.

In the battery pack B1 of the present invention, the control circuit board 22 is housed in the empty space above the battery 15, so that the battery pack can be made compact.

Example 2 A positive electrode and a negative electrode were produced in the same manner as in Example 1. FIG. 3 shows a schematic cross-sectional view of the prismatic lithium secondary battery of this example. The external dimensions of the battery are 150 mm high × 160 mm wide × 40 mm deep. In this embodiment, the positive electrode 31 and the negative electrode 32 inserted in the polyethylene-made separator 33 processed in a bag shape are alternately laminated.

The positive electrode lead 35 and the negative electrode lead 37 welded to the upper part of each electrode are connected to the positive external terminal 40 and the negative external terminal 4.
1 respectively. The positive external terminal 40 and the negative external terminal 41 are inserted through the battery cover 36 via a packing 42 made of polypropylene. The battery cover 36 has a safety valve 38 for releasing the pressure inside the battery and an electrolyte injection port 39.
Having.

After the aluminum battery can 34 and the battery lid 36 are laser-welded, an electrolytic solution is injected from a liquid inlet 39,
The injection port 39 was sealed to seal the battery. In this embodiment,
A non-aqueous electrolyte in which lithium hexafluorophosphate (LiPF ₆ ) equivalent to 1 mol / liter was dissolved in an equal volume mixed solvent of ethylene carbonate and dimethyl carbonate was used.

With this configuration, the electrochemical energy of the battery can be extracted outside through the positive external terminal 40 and the negative external terminal 41, and can be stored by recharging. The average discharge voltage of this battery is 3.8 V and the rated capacity is 6
5.8 Ah, 250 Wh.

As shown in FIG. 4, the above-described prismatic lithium secondary batteries 43 are arranged in a row so that the side surfaces having a width of 160 mm and a height of 150 mm face each other, and eight batteries are connected in series to form an assembled battery. Was assembled. Between the batteries, a spacer 44 made of polytetrafluoroethylene having a width of 10 mm, a thickness of 1 mm and a length of 150 mm was inserted in the vertical direction of the battery as shown in the figure, and arranged between the facing surfaces of the battery. Furthermore, the stainless steel metal plate 45 attached to the side surface of the assembled battery and the front and rear was fixed with bolts, and the prismatic lithium secondary battery was tightened. The entire battery assembly was housed in a polycarbonate container 46.

The positive external terminal 40 and the negative external terminal 41 of the prismatic lithium secondary battery 43 are connected by a current cable 47 so that all the batteries are connected in series.
It was taken out to the negative electrode terminal 49.

Further, the positive external terminal 40 and the negative external terminal 41 of the battery 43 are connected to the positive voltage input cable 5 respectively.
1. Charge / discharge control panel 5 via negative voltage input cable 52
0, and the voltage of each battery was measured for charge / discharge control of the assembled battery.

The charge / discharge control panel has a function of stopping charging / discharging of the battery pack when the voltage of the battery 43 goes out of the set range.

The average discharge voltage of this assembled battery was 30.4 V,
The rated capacity is 65.8 Ah, 2 kWh. The assembled battery of this embodiment is denoted by B3. As shown in FIG. 5, ventilation holes 53 were provided in the upper and lower surfaces of a container 46 made of polycarbonate to allow the outside air to flow inside.

Comparative Example 2 A rectangular lithium secondary battery 43 having the same specifications as in Example 2
The batteries were arranged in a row so that the side surfaces of the batteries of mm × 150 mm were in contact with each other, and eight batteries 43 were connected in series to assemble a battery pack. The battery pack of this comparative example is represented by B4.

Battery B3 of Embodiment 2 and Battery B
With respect to No. 4, a thermocouple was placed in contact with one of the four batteries located at both ends at the center of the side of 150 mm in height × 40 mm in depth, and the surface temperature of the battery during discharging was measured.

The charging conditions are a current of 8 A, a charging time of 8 hours, and an end voltage of 4.2 V. The discharge current is 66, 13
The battery was discharged until the battery voltage reached 3.0 V. The test environment temperature was 20 to 25 ° C. FIG. 6 plots the maximum temperature during discharge.

The maximum temperature of the battery pack B4 of the comparative example increased as the discharge current increased, and reached 65 ° C. at the time of discharging at 200A. The maximum temperature of the battery pack B3 of the present invention is 45 ° C. or lower, and the temperature can be reduced by as much as 20 ° C. as compared with the battery pack B4.

Further, a current of 8 A, a cut-off voltage of 4.2 V, 8
Charging over time and discharging at a current of 200 A and a final voltage of 3.0 V were performed for 50 cycles, and the discharge capacity of the assembled battery was measured. The operating voltage of the battery is 3.0-4.2V.

The capacity reduction rate at the time of 50 cycles was determined by comparing with the first discharge capacity measured under the same charge and discharge conditions. The battery pack B3 of the present invention had a capacity reduction rate of 3%, and the cycle characteristics were significantly improved as compared to the capacity reduction rate of the battery pack B4 of 45%.

According to the present invention, heat from the battery can be dissipated by inserting a spacer between the rectangular lithium secondary batteries. The positive electrode active material, the negative electrode active material, the current collector, the electrolytic solution, the material of the battery can, the electrode dimensions, and the like can be arbitrarily set according to the purpose. In addition, the shape of the spacer is not limited to the strip shape shown in Example 2, but by adopting a shape that allows the outside air to flow through the gap on the side surface between the rectangular lithium batteries,
The purpose is to reduce the temperature rise of the battery.

The spacer material is also polyethylene, polystyrene, ABS resin, polyester resin, epoxy resin, phenol resin, polycarbonate, styrene butadiene rubber, acrylonitrile butadiene rubber, butadiene rubber, isoprene rubber, silicone rubber, fluorine rubber, urethane rubber, acrylic Rubber can be mentioned.

Example 3 Twenty sets of the assembled batteries B1 and B3 of Examples 1 and 2 were manufactured, and an assembled battery module 54 in which these assembled batteries were connected in series was mounted on an electric vehicle 55. FIG. 7 shows a schematic diagram of an electric vehicle.

A ventilation port 56 is provided on the front of the electric vehicle so that outside air flows from the hood into the vehicle body during traveling.
The assembled battery module 54 was installed inside the hood. When the driver operates the control device 57 with a steering wheel, the converter 58 can be operated to increase or decrease the output from the battery module 54. The electric vehicle 55 was driven by driving the motor 59 and the wheels 60 using the electric power supplied from the converter 58.

The battery pack B3 of the present invention is excellent in heat dissipation. In particular, since the battery pack B1 is directly exposed, the heat dissipation is further excellent. In addition, the capacity of the battery at the time of sudden acceleration is small, and the risk of ignition and explosion of the battery is low. The same effect can be obtained by using the battery of the present invention in a hybrid electric vehicle using a gasoline engine.

[Embodiment 4] FIG. 8 shows Embodiments 1 and 2.
It is an example of a wheelchair for medical and nursing care equipped with a power supply comprising a module of an assembled battery in which 3 to 5 assembled batteries B1 and B3 manufactured in the above are set.

[0094] The angle can be adjusted by operating the controller 62 on the wheelchair 61 for medical and nursing care while the user is in the vehicle and operating the drive units provided on the backrest seat 63 and the footrest seat 64.

Using this function, the footrest sheet 64 is lowered when the user gets on and off the vehicle, and the backrest seat 63 and the footrest seat 6 are used when the user rests.
4 can be horizontal.

[0096] A wheel 60 for movement is mounted on the wheelchair 61 for medical and nursing care, and the user can move freely by operating the controller 62.

[0097] The wheelchair 61 for medical care and care has excellent heat dissipation from the battery pack, so that a stable capacity is guaranteed even when the battery is rapidly charged. In addition, it also has the effect of suppressing the spread of fire in the assembled battery, and the product safety is high.

The battery pack system of the present invention is not limited to the electric vehicle and the wheelchair for medical care, but also includes equipment systems requiring a large power and large capacity power supply, such as a large electronic computer, a power tool, a vacuum cleaner, Game equipment with air-conditioning and virtual reality functions, electric bicycles, walking aids for medical care, mobile beds for medical care, escalators, elevators, forklifts, golf carts, emergency power supplies, road conditioners, power storage systems And the like, and the same effects as in the above embodiment can be obtained.

[0099]

According to the present invention, the assembled battery using the prismatic non-aqueous electrolyte secondary battery is compact and has excellent heat dissipation.

Further, the decrease in battery capacity during rapid acceleration is small, and the risk of ignition and explosion is low.

Therefore, it is particularly excellent as a power source for a mobile electric vehicle such as an electric vehicle. It can also be used for a hybrid electric vehicle that uses a gasoline engine.

[Brief description of the drawings]

FIG. 1 is a schematic structural view of a prismatic lithium secondary battery of the present invention.

FIG. 2 is an external view of the battery pack of Example 1.

FIG. 3 is a schematic sectional view of the prismatic lithium secondary battery of the present invention.

FIG. 4 is a perspective view of a battery pack according to a second embodiment.

FIG. 5 is an external view of a battery pack according to a second embodiment.

FIG. 6 is a graph showing the relationship between the discharge current and the battery surface temperature of the assembled batteries of Example 2 and Comparative Example 2.

FIG. 7 is a schematic diagram of an electric vehicle using the battery pack of the present invention.

FIG. 8 is a schematic view of a wheelchair for medical care using the assembled battery of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Battery lid, 2 ... Battery can, 3 ... Positive electrode, 4 ... Positive electrode terminal, 5
.. Negative electrode, 6 Negative electrode terminal, 7 Separator, 8 Insulating disk, 9 Liquid inlet, 10 Bolt plug, 11 Ring packing, 12 Gas outlet, 13 Bolt plug, 14 …
Ring-shaped packing, 15: square lithium secondary battery, 16
... Ribbed metal plate, 17 ... L-shaped insulating part, 18 ...
Bolt, 19: Positive terminal of assembled battery, 20: Negative terminal of assembled battery, 22: Control circuit board, 31: Positive electrode, 32: Negative electrode,
33: polyethylene separator, 34: battery can, 35
... Positive electrode lead, 36 ... Battery cover, 37 ... Negative electrode lead, 38
... Safety valve, 39 ... Pouring port, 40 ... Positive electrode external terminal, 41 ...
Negative electrode external terminal, 42: packing, 43: square lithium secondary battery, 44: spacer, 45: stainless steel metal plate, 46: container, 47: current cable, 48: positive terminal of the assembled battery, 49: assembled battery Negative electrode terminal, 50: charge / discharge control panel, 51: positive voltage input cable, 52: negative voltage input cable, 53: vent, 54: assembled battery module, 5
5 electric vehicle, 56 ventilation port, 57 control device, 58
... Converter, 59 ... Motor, 60 ... Wheels, 61 ... Medical care wheelchair, 62 ... Controller, 63 ... Back seat, 64 ... Leg seat.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor, Hisashi Ando 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside the Hitachi Research Laboratory, Hitachi, Ltd. No. 1-1 Inside Hitachi Research Laboratory, Hitachi, Ltd. 8-7, Shinkobe Electric Co., Ltd. (72) Inventor Takeki Ishizu 2-chome, Nihonbashi Honmachi 2-chome, Chuo-ku, Tokyo 8-7 Shinkobe Electric Co., Ltd.

Claims (7)

[Claims] 1. A plurality of rectangular non-aqueous electrolyte secondary cells each having a positive electrode, a negative electrode, an electrolytic solution, a battery container, and a battery cover are arranged, and are electrically connected in series or / and in parallel. In the assembled battery, the control circuit board is installed above the battery lid of the battery, and the support plate and the insulating parts that are in contact with the side surfaces of the two unit cells at both ends are integrally connected with each other. Battery. 2. The battery cover according to claim 1, further comprising an electrolyte inlet, a positive electrode terminal, and a negative electrode terminal, wherein an end of the electrolyte inlet is lower than upper ends of the positive electrode terminal and the negative electrode terminal. The assembled battery according to claim 1. 3. The battery pack according to claim 1, wherein the support plate is a metal plate having a rib structure. 4. A plurality of rectangular non-aqueous electrolyte secondary cells each having a positive electrode, a negative electrode, an electrolytic solution, a battery container, and a battery cover are arranged, and are electrically connected in series or / and in parallel. A battery module according to claim 1, wherein a spacer formed of insulating plastic or rubber is interposed and connected to a side surface of the unit cell. 5. The battery pack according to claim 1, wherein a spacer is inserted between the unit cells, and an air passage formed between the spacer and a side surface of the unit cell is provided. 6. The battery pack according to claim 1, wherein the battery pack is housed in a container, and the container is provided with a vent. 7. An electric device comprising the battery pack according to claim 1 as a power source.