JP2003100269A - Battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery pack having little decrease in the battery capacity by preventing peel-off of an active material layer from a current collector caused by vibration or mechanical shock. SOLUTION: In the battery pack in which a plurality of rolled single batteries are arrayed in two or more lines to form an assemblied battery, at least a partial circumferential sidewall of at least one single battery closely being in contact with a container for housing this battery pack is rolled by a porous sheetlike material having the porosity of more than 30%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery pack composed of a winding type battery such as a plurality of lithium ion secondary batteries and a rechargeable vacuum cleaner using the same.

[0002]

2. Description of the Related Art Lithium-ion secondary batteries are small and lightweight,
Since it can be repeatedly charged and discharged 300 times or more, it is used in many electronic devices such as portable personal computers and mobile phones, and its demand is increasing. In particular, the demand for nickel-cadmium secondary batteries (Ni-Cd) and nickel-hydrogen secondary batteries (Ni-MH) is increasing because they can be made smaller and lighter than the nickel-hydrogen secondary batteries (Ni-MH). Lithium-ion secondary batteries handle the positive electrode, negative electrode, separator, and electrolytic solution as the main constituent materials, and the manufacturing process is roughly divided into positive electrode coating liquid, negative electrode coating liquid preparation, coating, drying, and rolling electrode preparation. The process can be divided into four steps: a positive electrode, a negative electrode, an electrode coil production step by winding a separator, an electrode coil insertion step into an electrode case, an electrolyte solution filling step, and a sealing step.

First, in the first electrode manufacturing process, an active material is applied to a metal foil and pressure-bonded to manufacture an electrode. In the positive electrode, a positive electrode active material such as LiCoO ₂ , a carbon material conductive agent such as acetylene black or graphite, and polyvinylidene fluoride (PVDF) serving as a binder dissolved in an organic solvent such as N-methylpyrrolidone are kneaded into a paste form. Prepare a coating liquid. The prepared coating liquid is coated on both sides of an aluminum foil having a thickness of 15 to 20 μm to a uniform thickness. The coating is performed using a coating device such as a doctor blade or a die coater. Then, the electrode is passed through a dryer to remove the dispersion solvent necessary for preparing the paste. After that, the dried electrode is rolled by a roll press to increase the density of the electrode layer and make the electrode thickness a predetermined thickness. If the electrode is not densified and smoothed by roll pressing, etc., not only the amount of active material that enters a battery can of a certain volume will decrease, but also the yield in the subsequent electrode winding process will deteriorate and Good products will come out.

Carbon and graphite are used for the negative electrode as a negative electrode active material. Binders include carboxymethyl cellulose (CMC), styrene-butadiene rubber (SB
R), these are dispersed in water to prepare a paste-like coating liquid for the negative electrode. The prepared coating liquid is coated on both sides of a copper foil having a thickness of 15 to 20 μm so as to have a uniform thickness. The coating is performed by using a coating device such as a doctor blade or a die coater as in the case of producing the positive electrode material. Then, the electrode is passed through a dryer to remove the dispersion solvent necessary for preparing the paste. After that, the dried electrode is rolled by a roll press to increase the density of the electrode layer and make the electrode thickness a predetermined thickness.

In the second step, the electrode is slit into a predetermined width and then cut into a predetermined length. Then, the electrode lead tab is welded to the exposed portion of the collector metal. In the next winding step, the positive electrode and the negative electrode with tabs have a thickness of 1
It is wound around a winding core through a separator of 5 to 20 μm and fixed with tape so that the wound electrode is not unwound, and a battery coil is manufactured.

In the third step, the battery coil is inserted into the bottom of the cylindrical can made by deep drawing, and the negative electrode lead is welded to the bottom of the can at the same time. Next, a battery can is attached to the battery can to insulate the positive electrode cap and the negative electrode can. After that, the negative end of the aluminum lead tab welded to the positive electrode current collector is welded to the sealing cap. The electrolyte is injected under reduced pressure, and when a certain amount of the electrolyte is injected and the pressure is returned to atmospheric pressure, the electrolyte is allowed to penetrate to the bottom of the can. As the electrolytic solution, for example, an electrolytic solution in which 1 mol of lithium hexafluorophosphate (LiPF ₆ ) is dissolved in a mixed solvent of ethylene carbonate (EC) / methyl ethyl carbonate (EMC) or the like is used.

In the final fourth step, the positive electrode cap is crimped using a crimping machine to seal the battery. An insulating seal is attached so that the crimped negative electrode portion and the positive electrode cap are not short-circuited, and the circumference of the cylindrical can is covered with a heat shrinkable tube or the like for insulation. A predetermined number of the thus-prepared unit cells are connected to form an assembled battery, and a charge / discharge control circuit and a protection circuit are further incorporated to form a battery pack.

FIG. 5 is a sectional view showing the outline of a battery-powered vacuum cleaner driven by using this battery pack. In this vacuum cleaner, the motor 1 is driven to rotate the suction fan 2 to suck air and dust from the hose 3 together with air. The sucked air and dust pass through the suction duct 4 and enter the dust pack 5 through the entrance 5a of the dust pack 5, which is a dust collecting container, and most of the dust is collected in the dust pack 5. Submicron-sized dust that cannot be collected by the dust pack 5 is included in the air passing through the dust pack 5. This air passes through the first filter 5b that also serves as the outlet of the dust pack 5, and then passes through the intake fan 2 and partly passes through the battery pack 6 and is discharged to the outside of the intake motor 1.

It has been found that when a battery pack composed of a plurality of lithium ion secondary batteries is repeatedly used in such a cordless cleaner, the capacity of the battery pack deteriorates quickly. In other words, when the battery pack is repeatedly charged and discharged without being installed in an electronic device, the capacity is 80% or more of the initial value even after repeating the charge and discharge 300 times.
For example, when mounted on a cleaner, it was reduced to 40% to 50%. When the battery was taken out from this battery pack and the battery was disassembled and the inside was examined, it was found that the active material layer was peeled off from the current collector in many parts of the positive electrode and the negative electrode. In the positive electrode, a binder called PVDF plays a role of an adhesive, and an oxide of the active material,
For example, LiCoO ₂ particles and particles of a conductive auxiliary agent such as acetylene black or graphite are applied to an aluminum foil which is a current collector. However, since the strength of this bond is relatively weak, it is easily broken by vibration or shock. For example, it is found that the active material layer is easily peeled off from the current collector of the aluminum foil when a part of the electrode is placed in an ultrasonic cleaner and cleaned for several minutes. 30 for cleaner
Since the suction motor used at a rotation speed of about 000 rpm is used, the battery pack mounted on the cleaner is vibrated by the rotation of the motor. It is considered that this vibration is transmitted to the electrodes inside the battery and breaks the bond between the active material layer and the current collector. Also, the cleaner collides with a wall or an ornament during use, and often receives an impact at this time. Therefore, it can be said that in the battery mounted on the cleaner, the active material layer is easily peeled off from the current collector.

This problem of peeling due to vibration occurs when a battery pack is used not only in a cleaner but also in an electronic device using a rotating device such as a motor. For example, a robot vacuum cleaner,
Uninterruptible power supply (UPS: Uninterrupted P)
power source), robots, assisted bicycles, electric wheelchairs, and the like.

[0011]

When the battery pack is used by being mounted on a cleaner for mounting rotating equipment such as a motor, the active material layer of the electrode is peeled off from the current collector due to the vibration of the motor and the capacity of the battery is reduced. Has a problem that it deteriorates with the number of times of use. The present invention has been made to solve the above problems, and an object of the present invention is to provide a battery pack that prevents the active material layer from peeling off from the current collector against vibration or impact and has a small decrease in battery capacity. And

[0012]

A first aspect of the present invention is a battery pack including an assembled battery in which a plurality of winding type cells are arranged in two or more rows and integrated, and a container for accommodating the battery pack. The battery pack is characterized in that a porous sheet-like body having a porosity of 30% or more is wound around at least a part of the outer periphery of the side surface of at least one unit cell in contact with.

In the battery pack according to the first aspect of the present invention, winding the porous sheet-like body around all of the unit cells in contact with one surface of the container provides the maximum vibration damping function. preferable.

In the battery pack of the first aspect of the invention, it is preferable that the plurality of cells are arranged in a zigzag pattern in order to not only minimize the vibration of the battery pack but also improve the volume efficiency. Further, by forming a gap of 100 μm or more between the unit cells that are adjacent to each other in the longitudinal direction of the array, interference between the unit cells during vibration is suppressed to a minimum,
It is preferable for preventing the transmission of vibration.

In the battery pack of the first invention, it is preferable that the surface of the porous sheet is coated with a material having a porosity of 20% or less. Moreover, it is preferable to use polytetrafluoroethylene as the porous sheet-like material because the life of the material is extended.

In the battery pack according to the first aspect of the present invention, by inserting a support plate that supports the unit cells between rows in the longitudinal direction of the array, the inertial weight of the unit cells is increased, and the effect of suppressing resonance is obtained. Is preferable because it is exhibited. Further, it is preferable that the support plate is an aluminum plate because the resonance suppressing effect can be expected without increasing the total weight of the battery.

In the battery pack of the first aspect of the invention, it is preferable to use a lithium ion secondary battery as the unit cell because a large amount of energy can be taken out from a relatively small volume. Furthermore, it is preferable that the unit cells are integrated with one type of material selected from the group consisting of a thermoplastic resin film, plastic, and metal, because the vibration damping effect is great.

A second aspect of the present invention is a porous sheet-like body having a porosity of 30% or more on at least a part of a side surface outer peripheral portion of at least one wound-type cell in contact with a container for accommodating a battery pack. And then wind multiple cells including this cell into 2
It is a rechargeable vacuum cleaner characterized in that a battery pack, which is arranged in an array in a row or more and integrated, is housed in a housing and used.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION A battery pack according to the present invention will be described. (Unit cell) The wound type battery of the present invention means, as shown in FIG. 1, a positive electrode 4 which is a sheet-like body in which an active material layer is formed on the surface of a metal foil which is a current collector as positive and negative electrodes, and The negative electrode 6 is wound around the separator 5 and housed in the container 1 which also functions as one of the electrodes, and the electrolytic solution is injected and sealed. In the present invention, this battery is abbreviated as a unit cell. In the present invention, a lithium ion secondary battery is preferable as the unit cell because of its particularly high power generation energy density. This lithium-ion secondary battery may contain a power generating element composed of a positive electrode, a negative electrode and a separator impregnated with an electrolytic solution in a cylindrical container that also serves as a negative electrode terminal, or may have a rectangular container containing the power generating element. It doesn't matter.

(Coating Material) At least one of the plurality of unit cells constituting the battery pack of the present invention is, as shown in FIG. A body covering 22 is used. As the coating material for coating the unit cell, it is preferable to use a material having a porosity of 30% or more because the higher the porosity, the more the influence of vibration can be alleviated. Further, a sheet-like body having a porosity of 20% or less may be further laminated and wound on the surface of the porous sheet-like body having a porosity of 30% or more. Alternatively, the vibration can be further suppressed by winding a single cell in the form of a sheet in which a plurality of layers having different porosities are integrated and using materials having different porosities on the front and back surfaces. The number of layers of this porous sheet-shaped laminate may be two layers or three layers. In the case of two layers, the porosity of the material on the side in contact with the unit cell is 30% or more,
The porosity of the material to be laminated on this must be 20% or less. When the porous sheet-shaped laminate has three layers,
As the outermost surface layer, a porous sheet-like body having a porosity of 30% or more may be laminated. The material of the porous sheet-like body of the present invention is polyethylene, a material containing polypropylene as a main component, or polytetrafluoroethylene (P
The material such as TFE) is not particularly limited, but polyethylene and polypropylene are more preferable because they are deformed with time, whereas when PTFE is used, the change with time is small and the vibration absorbing capacity is less deteriorated. Further PTF
Since E is nonflammable, it is preferable for safety. When the porous sheet-shaped body laminate is formed by laminating the layers, the material may be different for each layer.

The thickness of this porous sheet-shaped body or porous sheet-shaped body laminate is preferably in the range of 100 μm to 5 mm. If the thickness is less than this range, the vibration reduction effect is not exerted. On the other hand, if the thickness is greater than this range, the vibration reduction is not improved as expected, and the volume efficiency of the battery pack is reduced, which is uneconomical. Is. In the present invention, the porous sheet may be used by adhering or adhering to the unit cell using an adhesive or a pressure-sensitive adhesive, or the porous sheet is formed into a tubular shape so as to fit the outer shape of the unit cell. As a result, it is possible to coat the unit cell without using an adhesive.
The coating material is wound around the side surface of the unit cell,
It may be formed on the entire outer peripheral portion of the side surface of the unit cell, or may be formed on a part thereof. In this case, it is preferable to form so as to cover at least 30% of the outer peripheral portion of the side surface of the unit cell.
If the coverage ratio is less than 30%, the sufficient vibration preventing function cannot be achieved. Further, when this coating is formed on a part of the outer peripheral portion of the side surface of the unit cell, it is preferable to adhere it to the central portion of the side surface of the unit cell.

(Shape of Battery Pack) In the battery pack of the present invention, a plurality of the above-mentioned unit cells are used in combination, and the arrangement thereof is a unit cell line in which the plurality of unit cells are arranged in one line.
It is preferable to combine so as to form at least two rows. Therefore, the number of unit cells that make up the battery pack is at least four. FIG. 3 shows an example of the arrangement of battery packs that can be adopted in the present invention. The array in Figure 3 is
It is configured by combining 12 unit cells. 1
As a method of arranging the two unit cells, an arrangement of 2 rows × 6 rows or an arrangement of 3 rows × 4 rows can be considered, but an arrangement of 2 rows × 6 rows is arranged in order to reduce vibration. Is preferred. Further, in the arrangement of vertical 2 rows × horizontal 6 rows, as shown in FIG. 3, three types of arrangements shown in FIG. 3 are conceivable depending on requirements such as the intervals between the unit cells. In FIG. 3, the (A) type is an array in which the cells are arranged like a grid, and the (B) type is an array in which the cells are arranged in a zigzag pattern without gaps,
The type (C) is an array in which gaps are formed between the unit cells and the cells are arranged in a zigzag pattern. The (C) type battery pack is preferable because it can reduce the vibration most and can reduce the size of the battery pack. Also, in the case of a battery array of vertical 2 rows × horizontal 6 rows, vibration is generated by covering 6 surfaces arranged horizontally rather than 2 surfaces arranged vertically with a material having a porosity of 30% or more. This is preferable because it can be further suppressed. In addition, in FIG.
Although the example in which the support plate 32 is arranged between the two is shown, of course, the support plate may be arranged without providing the support plate.

(Interval between unit cells) As shown in FIG. 3 (C),
After covering a part of the cell surface, leave 100
When the thickness is not less than μm, the effect of suppressing vibration that can suppress the resonance between the batteries is enhanced. On the other hand, if the size is too large, the size of the battery pack itself becomes large, and the volume efficiency decreases, which is not preferable. This interval is 10
A size of 0 μm or more and 5 mm is suitable.

(Support plate) By interposing the support plates between the unit cells, the vibration of the unit cells can be significantly suppressed as compared with the case where there is no support plate. The material is not particularly limited, but the larger the mass, the greater the effect of suppressing the vibration of the unit cell. However, if the mass is too large, the weight of the battery pack becomes heavy, which is not preferable. From this point of view, aluminum having a density of 2.7 g / m ³ is preferable because it can both suppress vibration and reduce the weight of the battery pack. Further, it is preferable that the shape of the support plate is wavy according to the battery arrangement of the type (C) of FIG. Regarding the plate width, two narrow support plates may be used to support the unit cells, and they may be supported above and below the battery. When the width of the plate is wide, punching holes in the plate as shown in FIG. 4 has a great effect of alleviating the vibration, and the weight can be reduced.

(Integrated structure)
Vibration can be further reduced by integrating at least one material selected from a thermoplastic resin film, plastic, and metal, so that deterioration of battery capacity when the battery pack is repeatedly used can be dramatically suppressed. Also,
The battery pack of the present invention is used as an assembled battery in which positive and negative electrodes of a single battery are electrically connected in series or in parallel with each other by a conductor. At that time, by using a metal material having high rigidity as the conductor, the cells are fixed to each other and behave in a unified manner against vibration. The vibration applied to the battery pack integrated in this way is transmitted to all the unit cells, but since at least one of the constituent unit cells is formed with the coating material to absorb the vibration, The vibration of all the unit cells fixed and integrated with this unit cell is attenuated. Therefore, of course, the number of the single cells with the coating material for absorbing the vibration is effective, but the effect of damping the vibration is better when the coating for absorbing the vibration is applied to a plurality of cells. large. In particular, it is desirable to form a vibration absorbing coating on all the cells that are in contact with the side surfaces in the longitudinal direction of the battery pack.

(Rechargeable Vacuum Cleaner) The rechargeable vacuum cleaner of the present invention will be described below. This rechargeable vacuum cleaner accommodates a battery pack in the housing of the vacuum cleaner, and is charged after use while the vacuum cleaner is being driven. The use of the battery pack of the present invention as the battery pack of this vacuum cleaner is preferable in that the life of the battery pack, that is, the decrease in the battery capacity after reuse is prevented. FIG. 5 shows a rechargeable vacuum cleaner of the present invention. FIG. 5 (B) is a side sectional view of the rechargeable vacuum cleaner of the present invention, and FIG. 5 (B) shows a cross section taken along line AA of FIG. 5 (B).
(A). In FIG. 5, reference numeral 51 denotes a battery pack of the present invention, which is a casing 54 of a vacuum cleaner.
The battery pack is housed in a battery pack housing 52 which is a container for the battery pack arranged inside. A motor 53 is arranged in contact with the battery pack housing 52, and vibration generated when the motor is driven is transmitted to the battery pack 51, causing the battery to resonate and the electrode of the battery to be peeled off. As described above, the rechargeable vacuum cleaner of the present invention solves this problem by forming a coating material on the outer peripheral surface of the unit cell that constitutes the battery pack, as described above. In the battery pack of the present invention,
As long as the unit cell having the covering material wound is in close contact with the wall surface of the battery pack housing 52, even if it is arranged in contact with the surface to which vibration of the motor is transmitted, it is arranged in contact with the opposite surface. It does not matter if it is done.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the drawings. (Example 1) Twelve 18650 size lithium ion secondary batteries having a capacity of 1.5 Ah were used, two parallels were set as one unit, and six units were connected in series.
The battery arrangement is a C type with 2 rows vertically and 6 rows horizontally. A gap of 1 mm was provided between the batteries. A battery having a porosity of 60% and a thickness of 500 μm was wrapped around the batteries around the batteries arranged in a row and arranged in a row. Six pieces were arranged laterally in two rows, and an aluminum plate having a width of 60 mm was placed between the rows.
Holes as shown in FIG. 2 were formed in the aluminum plate. This battery pack was mounted on a 160 W input cordless cleaner, and charging and discharging were repeated 300 times to measure the battery capacity.
Charging was performed by constant current constant voltage charging at 3 A to 4.15 V in 5 hours. After charging, it was installed in the cleaner and the cleaner was operated in "strong mode" until the motor stopped. The discharge current during operation was 8.2 A on average and lasted for about 22 minutes. It was found that the battery capacity after using 300 times was 1.23 Ah, which was 82% of the initial capacity.

(Comparative Example 1) As Comparative Example 1, the same 12 batteries as in Example 1 were used and the battery arrangement was set to C type. The cell was not coated at all. As a result of using this battery pack 300 times in the same manner as in Example 1, the battery capacity after 300 times of use was 48% of the initial capacity.

(Example 2) Two sets of battery packs which are the same as in Example 1 except for the coverage are prepared and used as a power source for a self-propelled robot cleaner. The battery capacity after 300 uses was 81% of the initial capacity in both sets.

(Comparative Example 2) As Comparative Example 2, two sets of the same battery packs as in Comparative Example 1 were prepared and the capacities after 300 times of use were measured. As a result, the battery capacities were 46% and 47% of the initial capacities.

(Embodiment 3) 18650 size and capacity 1.
8 units of 5 Ah lithium ion secondary batteries were used, and 2 units were connected in series with 2 units being 1 unit. The battery arrangement is a C type with 2 rows vertically and 4 rows horizontally. A PTFE sheet having a porosity of 60% and a thickness of 500 μm was wrapped around the battery in four cells arranged in a row and a gap of 1 mm was provided in the darkness of the battery. Four aluminum plates with a width of 60 mm were placed in the darkness of this row, which was arranged in two rows. Holes as shown in FIG. 4 were formed in the aluminum plate. This battery pack is mounted on a robot dog with an input of 140W to charge and discharge 300 times.
The battery capacity was measured repeatedly. Charging was performed by constant current constant voltage charging at 3 A to 4.15 V in 5 hours. The charging degree robot dog was filled and moved. The operating time of the robot dog lasted 15 to 20 minutes, depending on the movement form. It was found that the battery capacity after using 300 times was 83% of the initial capacity.

(Comparative Example 3) As Comparative Example 3, the same eight batteries as in Example 3 were used and the battery arrangement was set to C type. The cell was not coated at all. As a result of using this battery pack 300 times in the same manner as in Example 1, the battery capacity after 300 times of use was 48% of the initial capacity.

(Examples 4 to 12, Comparative Examples 4 to 6) The battery pack structure, coating material, porosity, coating material thickness, coating material layer structure, coating rate, number of coated cells as shown in Table 2,
Regarding the battery pack configured in the equipment shown in the column of equipment to be installed, which constitutes the battery pack with the intervals between the batteries and the configuration of the support plate,
Charge and discharge was repeated 300 times in the same manner as in Example 1, and 3
The battery capacity after repeated use of 00 times was measured. The results are shown in Table 2.

The constitutions and results of the above Examples 1 to 12 and Comparative Examples 1 to 6 are summarized in Table 1, Table 2 and Table 3.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

As is clear from the results of Tables 1 and 2, in the battery pack of the present invention, at least the unit cell 1
It was revealed that by winding a porous sheet around a part of the cylindrical side portion of the book, the problem of capacity decrease caused by the vibration of the unit cell was ameliorated. Further, it was revealed that when the area of the porous sheet coating was less than 30%, the effect of sufficient capacity reduction prevention was not achieved.

It has been revealed that the rechargeable vacuum cleaner using the battery pack of the present invention shows excellent results in the battery capacity retention rate.

[0040]

As described above in detail, according to the battery pack of the present invention, it is possible to prevent the active material layer from peeling off from the current collector due to vibration or impact, so that the battery capacity can be improved even after repeated use. It is possible to provide a battery pack with less decrease in battery power. In addition, a rechargeable vacuum cleaner using this has a long battery life and is highly reliable.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a wound type battery used in the present invention.

FIG. 2 is a schematic view showing a state in which a coating material is applied to an outer surface of a side portion of a unit cell of the present invention.

FIG. 3 is a schematic diagram showing an example of an arrangement of cells in the battery pack of the present invention.

FIG. 4 is a support plate used for fixing the unit cell used in the present invention.

FIG. 5 is a sectional view of the rechargeable vacuum cleaner of the present invention.

[Explanation of symbols]

1 ... Container 2 ... Insulator 3 ... Electrode group 4 ... Positive electrode 5 ... Separator 6 ... Negative electrode 7 ... Insulating paper 8 ...
..Insulation sealing plate 9 ... Positive electrode terminal 10 ... Positive electrode lead 21 ... Single cell 22 ... Coating material 31 ... Single cell 3
2 ... Support plate 41 ... Support plate 42 ... Support hole 51 ... Battery pack 52 ... Battery pack storage 53
... Motor 54 ... Casing

Continued front page    F-term (reference) 3B057 DA00                 5H029 AJ03 AK03 AL07 AL08 AM03                       AM05 BJ02 BJ14 BJ23 DJ02                       DJ07                 5H040 AA00 AS22 AT01 AY04 AY08                       CC30 NN00

Claims (11)

[Claims] 1. A battery pack in which a plurality of winding type cells are arranged in two or more rows and integrated to form an assembled battery , wherein at least one unit cell in contact with a container accommodating the battery pack. A battery pack characterized in that a porous sheet-like body having a porosity of 30% or more is wound around at least a part of the outer periphery of the side surface. 2. A said battery pack, wherein said all of the cells in contact with one surface of the container housing the battery pack, characterized by winding the porous sheet body over porosity 30% The battery pack according to Item 1. 3. A said battery pack, the battery pack according to any one of claims 1 to 3, characterized in that arranged a plurality of the unit cells in a staggered manner. 4. The battery pack according to claim 1, wherein in the battery pack, a gap of 100 μm or more is formed between the unit cells adjacent to each other in the longitudinal direction of the array. . 5. The battery pack, the porous surface of the sheet over porosity of 30% and wherein the coating the material coated, laminated porosity of 20% or less of the material on the surface of the cell The battery pack according to any one of claims 1 to 5. 6. The battery pack according to claim 1, wherein the porous sheet that covers a part of the surface of the unit cell is polytetrafluorethylene. Battery pack. 7. The battery pack, said support plate for supporting the unit cell, according to any one of claims 1 to 6, characterized in that inserted between the longitudinal direction of the single cell arrangement row Battery pack. 8. The battery pack, the support plate for supporting the unit cells, the battery pack according to claim 7, characterized in that the aluminum plate. 9. The battery pack according to claim 1, wherein the unit cell is a lithium ion secondary battery.
The battery pack according to claim 7. 10. The battery pack according to claim 1, wherein the unit cells are integrated with a material selected from a thermoplastic resin film, plastic, and metal. The battery pack described in. 11. A porous sheet-like body having a porosity of 30% or more is wound on at least a part of a side surface outer peripheral portion of at least one winding type single cell which is in contact with a container for accommodating a battery pack. A rechargeable vacuum cleaner comprising a battery pack, which is formed by arranging a plurality of cells including cells in two or more rows and integrating them in a housing.