JP3734456B2 - Battery pack and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery pack and a manufacturing method thereof.
[0002]
[Prior art]
In mobile phones, notebook computers, video cameras, other mobile information devices, electronic devices, OA devices, and the like, removable battery packs are used as portable power sources. This battery pack includes a battery cell and a hard or soft cover (packaging) that protects the battery cell.
In each of the above devices, the energy capacity of the battery itself is increasing, the continuous use time is extended, and the use area is greatly expanded. Since these devices are often used while being carried, downsizing and weight reduction of the devices have become increasingly important issues.
The weight of the battery in the weight of the equipment is very large, and each company has to reduce the weight and size of the battery pack, so that the battery cells and their protective covers that make up the battery pack have become a major issue. Yes.
In response to such demands for reducing the size and weight of the battery pack, the battery cell includes, for example, an electrolyte solution and an electrode and a cell case that accommodates them, and the cell case is a metal having a thinner thickness. There is a tendency to shift to a thin and light cell case such as a cell case made of light metal, a cell case made of light metal, a resin cell case, or a cell case made of a soft resin film.
In the situation as described above, as a conventional battery pack system, the battery cell is electrically insulated by sealing and covering the periphery of the battery cell with a heat shrinkable tube, and the battery cell is protected from external impact, so-called A tube pack method and a so-called hard pack method in which a battery cell is housed and fixed in a hard case to electrically insulate the battery cell and protect it from external impacts are known.
[0003]
[Problems to be solved by the invention]
The tube pack method using the heat shrinkable tube is suitable for reducing the size and weight of the battery pack, but on the other hand, it is difficult to obtain mechanical strength and the battery pack is dropped when the battery pack is dropped. There is a problem that the pack is damaged. For this reason, some heat-shrinkable tubes have been reinforced with resin molded products that are covered from above and bonded, but the material cost and work cost are greatly increased.
In addition, the heat shrinkable tube itself has a high cost, and has a disadvantage that heat treatment must be performed after the battery cell is covered with the heat shrinkable tube. On the other hand, in the case of the hard pack method, mechanical strength is easily obtained, but on the other hand, it is difficult to reduce the outer dimensions and reduce the weight. There is a problem that the cost becomes high, for example, a mold for pre-forming the protective case and a press machine are required.
[0004]
Therefore, the present invention eliminates the problems caused by the conventional tube pack method and hard pack method, and maintains a good mechanical strength and electrical insulation by a completely new method different from the tube pack method and hard pack method. It is another object of the present invention to provide a battery pack that can be sufficiently reduced in weight and size, and that can realize low cost, and a method for manufacturing the same.
[0005]
[Means for Solving the Problems]
As a result of repeating various experiments and researches to solve the above problems, the battery cell is not covered with a heat-shrinkable tube as in the prior art, and a protective case is not used on the surface of the bare battery cell. By directly forming the protective layer by printing the necessary resin as much as necessary, the battery pack is configured, thereby sufficiently maintaining the conventional mechanical strength and electrical insulation of the battery pack, In addition, it was learned that weight reduction, size reduction, and cost reduction could be realized, and the present invention was completed.
That is, the battery pack of the present invention is a battery pack in which the periphery of the battery cell is covered with a coating protective layer by resin printing, and the coating protective layer is composed of a plurality of layers and is made of a resin having different characteristics for each layer. The first feature is that the plurality of layers are formed.
Further, in the battery pack of the present invention, in addition to the first feature, the resin for the coating protective layer is polyethylene, polypropylene, polyethylene terephthalate, acrylic, polycarbonate, ABS, polystyrene, poly (vinylidene chloride), butyl rubber, SBR, NBR, EPDM. The second feature is that the resin is different for each layer from among the CR.
The method of manufacturing a battery pack of the present invention, a resin of different properties to the ink of dissolving with a solvent, coating the protective layer of the battery cell by printing more than once around the battery cell using the plural kinds of ink The third feature is to constitute
The method for producing a battery pack of the present invention, in addition to the third feature, the resin used in the Lee Nki include polyethylene, polypropylene, polyethylene terephthalate, acrylic, polycarbonate, ABS, polystyrene, polyvinylidene chloride Biriniden, butyl rubber, SBR , NBR, EPDM, has a fourth feature in that it consists of at least two or more of the resins of CR.
In addition to the third or fourth feature, the battery pack manufacturing method of the present invention has a fifth feature of performing printing by gravure offset printing.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be further described with reference to the drawings.
1 is an overall perspective view showing a first embodiment of the battery pack of the present invention, FIG. 2 is a sectional view of the same, FIG. 3 is a sectional view showing a second embodiment of the battery pack of the present invention, and FIG. It is sectional drawing of the principal part which shows 3rd Embodiment of the battery pack of invention.
[0007]
First, referring to FIGS. 1 and 2, the battery pack P includes a battery cell 10 and a coating protective layer 20 that covers the periphery of the battery cell 10.
The outer shape of the battery cell 10 is not particularly limited, but when the coating protective layer 20 is formed by printing, a shape suitable for the printing is preferable. For example, when the battery cell 10 is configured in a sheet shape, the periphery of the battery cell 10 can be substantially covered with the coating protective layer 20 only by printing the two front and back surfaces.
In the present embodiment, the rectangular shape is thin. In principle, printing is applied to each surface (six sides), but if the thickness is sufficiently thin, the surface of the battery cell 10 is substantially protected by coating only by printing the front and back surfaces. It is possible to cover with layer 20. The present invention includes such a case in its scope.
Of course, the shape of the battery cell 10 is not limited to the above-described flat shape, but may be any shape that can be printed on the surface, such as a cubic shape, a rectangular parallelepiped shape, a cylindrical shape, or the like. .
[0008]
The battery cell 10 includes a cell case 11, an electrolytic substance 12 filled in the cell case 11, an electrode 13, and the like. The kind of battery which the battery cell 10 comprises can be made into a lithium battery, for example. However, the type of battery is not particularly limited. Therefore, the material of the electrolytic substance 12 and the electrode 13 is not particularly limited.
The cell case 11 can be made of an aluminum alloy, a light metal having resistance to other electrolytic substances, other metals, synthetic resins, or other materials depending on the type of the electrolyte material 12 or the like. Preferably, a material is selected that is light, thin, strong, and resistant to the electrolyte being filled.
In the first embodiment of the present invention, the cell case 11 is used having a certain shape by having appropriate rigidity.
[0009]
A coating protective layer 20 is formed around the cell case 11 by printing. The coating protective layer 20 is applied to the entire surface of the cell case 11. Of course, the coating protective layer 20 is omitted for portions that should not be coated, such as portions necessary for external connection.
The coating protective layer 20 is configured by printing a resin having good electrical insulation and mechanical strength on the surface of the cell case 11.
Examples of the resin having good electrical insulation and mechanical strength include polyethylene, polypropylene, polyethylene terephthalate, acrylic, polycarbonate, ABS, polystyrene, polyvinylidene chloride, butyl rubber, SBR (styrene butadiene rubber), NBR (nitrile butadiene rubber), One kind or plural kinds of EPDM (ethylene propylene trimer) and CR (chloroprene) can be used.
Of course, the coating protective layer 20 is not limited to the above-described resin, and includes other resins (including rubber) having good electrical insulation and mechanical strength.
[0010]
The printing of the resin is performed by dissolving the resin in advance with a solvent and converting it into an ink. As the solvent, a solvent that easily dissolves the resin is selected corresponding to the resin to be used.
By printing the entire surface of the cell case 11 with an inked resin and drying the solvent, the entire surface of the battery cell 10 is protected by the coating protective layer 20 having good electrical insulation and mechanical strength due to the resin. The coating protective layer 20 can be formed by using only the minimum amount of resin used as the ink. For this reason, material cost is also very cheap compared with a heat-shrinkable tube. In addition, the thickness of the coating protective layer 20 can be adjusted during printing, and the optimum thickness can be set in consideration of the mechanical strength, weight, and the like of the coating protective layer 20.
In addition, instead of forming a protective layer using a conventional heat-shrinkable tube or hard case, the protective layer is formed by printing to form the battery pack P, so that the manufacturing process is sufficiently small and simplified. In addition, since the amount of material used is small, the manufacturing cost can be significantly reduced as compared with the conventional tube pack method and hard pack method.
[0011]
The printing of the inked resin can be performed by, for example, offset printing, screen printing, gravure printing, flexographic printing, and other printing methods. However, it can be preferably performed by gravure offset printing.
In the case of gravure offset printing, since there are many types of ink that can be used, printing can be easily performed even with ink in which a resin is dissolved. Further, since the evaporation drying type ink is used, it can be easily dried and printing can be repeated many times. Therefore, the coating protective layer 20 can be easily configured by laminating the same or different types of resins one after another. Further, there is an advantage that the thickness of the coating protective layer 20 can be adjusted accurately and easily by repeating printing.
[0012]
In the case of offset printing, the quality of printing is determined by the rubber blanket of the transfer cylinder. If the rubber hardness is high, it is difficult to sufficiently transfer the ink without deformation of the rubber. On the other hand, if it is low, the deformation of the rubber becomes large, and it is difficult to perform printing accurately. The rubber hardness is 70-20 in JIS-A, preferably 60-30. It has also been found that the surface shape of the blanket has a great influence on the surface shape of the printed matter. The surface roughness is preferably 10 μm or less in terms of 10-point average roughness, and more preferably a smooth surface of 5 μm or less.
[0013]
The solvent contained in the ink is an important factor governing printing characteristics. In particular, the boiling point of the ink greatly affects the degree of drying of the ink. If the boiling point of the ink solvent is too low, the ink dries during printing, and the viscosity of the ink increases, so that printing cannot be performed successfully. Further, if the boiling point of the ink solvent is too high, there arises a problem that it takes a very long time to dry the ink after printing.
In the present invention, UV ink (UV ink solvent) that is cured by ultraviolet irradiation or EB ink (EV ink solvent) that is cured by electron beam irradiation can be preferably used as the ink that is not affected by the drying temperature.
By quickly curing the resin-dissolved ink by ultraviolet irradiation or electron beam irradiation after printing, the same type of ink or ink with different characteristics of the resin is printed on top of each other to have different characteristics. The coating protective layer 20 can be formed.
[0014]
The thickness of the coating protective layer 20 by printing is of course changed depending on the type and combination of resins used, but can be in the range of 0.003 to 10 mm. Preferably it is set as the range of 0.05-1.0 mm.
The thickness of the coating protective layer 20 by printing is good for reducing the weight and cost of the battery pack P as the thickness is reduced. On the other hand, the mechanical strength is lowered and the electrical insulation is also lowered. become. Therefore, the thickness of the coating protective layer 20 is set to the above range in consideration of the type of resin used.
[0015]
A second embodiment of the battery pack of the present invention will be described with reference to FIG.
In this embodiment, the cell case 111 of the battery cell 10 is composed of a flexible film made of a resin film, a metal film, or the like. That is, the battery cell 10 is formed by sealing the electrolytic substance 12 and the electrode 13 in a cell case 111 made of a flexible film. Since the cell case 111 of the battery cell 10 can be configured by joining the peripheral portions of a pair of resin films by thermocompression bonding or other adhesion, etc., a hard case is used using equipment such as a mold. Unlike manufacturing, it can be prepared easily and easily at low cost.
In the present embodiment, the cell case 111 is configured in a thin and thin state, and the entire shape can be flexibly deformed. The cell case 111 is highly flexible for mounting on a device, and the weight is greatly reduced. The
Then, the coating protective layer 20 is formed by printing from above the cell case 111 enclosing the electrolytic substance 12 and the electrode 13. Since the cell case 111 has a flexible shape, it can also be used for printing.
The materials for the electrolytic substance 12 and the electrode 13 are the same as those in the first embodiment described above. Further, the material of the coating protective layer 20, the ink formation, the printing method, and the like are the same as those in the first embodiment.
By configuring the cell case 111 using a film made of resin or metal, and further forming the coating protective layer 20 by printing, the weight reduction of the battery pack P can be greatly promoted, and a mold or the like is not required. It can be expected that the manufacturing cost will be greatly reduced.
[0016]
A third embodiment of the battery pack of the present invention will be described with reference to FIG.
In this embodiment, the coating protective layer 20 formed by printing on the cell case 11 (111) of the battery cell 10 is formed from a plurality of printed layers 21, 22, and 23. For example, the first printing layer 21 is a layer printed with a resin having good insulation, the second printing layer 22 is a printing layer made of a resin having excellent mechanical strength, and the outermost printing layer 23 is suitable for character printing. It can be set as the printed layer which consists of resin.
In the drawing, the printing layer is composed of three layers, but is not limited to this, and can be composed of a plurality of layers of two or more layers.
For example, from the side in contact with the battery cell 10, a printing layer suitable for insulation, a printing layer suitable for shock absorption, a printing layer capable of color selection, and an outermost surface layer can be laminated in this order.
Furthermore, the thickness of each printing layer can also be changed and adjusted depending on the type of resin (same type or different type) used.
[0017]
In each of the above embodiments, the coating protective layer 20 is configured by printing. However, the coating protective layer 20 may be configured by means other than printing. For example, coating by immersion in a solution in which a resin is dissolved, coating by painting with a solution in which a resin is dissolved, and coating by other known coating techniques are possible.
[0018]
Example 3 parts by weight of a photopolymerization initiator (benzyldimethyl ketal) [Daiichi Kogyo Seiyaku BDK] is added to 97 parts by weight of an epoxy acrylate resin [Hitachi Kasei Hitaroid 7851] whose end of bisphenol A type epoxy resin is acrylic-modified. Thus, a UV ink was prepared. This UV ink is gravure offset printed at a film pressure of 0.003 mm on the surface of a rectangular flat lithium ion secondary battery cell, and the UV light from an 80 W / cm high pressure mercury lamp (300 to 390 nm) is 40 mJ at a conveyor speed of 25 m / min. / Cm ² to cure. As a result of conducting an insulation test of the obtained battery pack, the insulation was good.
The mechanical strength of the cured coating was measured using a specimen having a span length of 50 mm and a width of 10 mm. Result is,
Pencil hardness: H-2H
Elongation: <5%
Tensile strength: 350 kgf / cm ² (Tensile speed: 50 mm / min)
Met. From these values, it was found that the mechanical strength was sufficiently good.
[0019]
Comparative Example A polyethylene heat-shrinkable tube was covered so as to cover the entire surface of the battery cell of the rectangular plate-like lithium ion secondary battery, and it was covered with a polyethylene resin having a thickness of about 0.05 mm by performing heat treatment thereon. A battery pack was constructed. As a result, the battery pack can be downsized, but it is vulnerable to external impact, does not play a role of protection against strong impact, and allows damage to the battery cell.
During manufacturing, the necessary design for the heat-shrinkable tube is printed, both ends are bonded to the required size, processed into a cylindrical shape, covered with battery cells, and the process of shrinking the tube by applying time and heat is required. It becomes. Since these steps are required, the material cost and the manufacturing cost increase.
[0020]
【The invention's effect】
The present invention comprises the above-described configuration and action. According to the battery pack of claim 1, the battery pack is a battery pack in which the periphery of the battery cell is covered with a coating protective layer by resin printing, and the coating protective layer includes a plurality of coating protective layers. Since the plurality of layers are composed of resin having different characteristics for each layer,
Since the periphery of the battery cell is protected by the coating protective layer directly laminated with resin, the periphery of the battery cell can be reliably and densely covered with a smaller amount of resin and resin thickness.
In addition, as compared with the hard pack method, the battery cell can be protected without using a hard case or the like, and thus the weight and size can be sufficiently reduced. There is no need for molds and the effect of reducing manufacturing costs is great.
Compared to the tube pack method, the coating protective layer directly laminated on the battery cell can provide more precise electrical insulation by the resin, and the impact resistance can be reduced with less resin amount and resin thickness. Can be realized. In addition, since no resin tube or the like is used, the cost can be reduced.
In addition, since the periphery of the battery cell is to be covered with a protective coating layer by printing, the coding protective layer should be precisely adjusted from thin to thick using the printing characteristics. Can do. Further, the coating protective layer can be made denser and sufficiently adhered to the battery cell, and characteristics such as electrical insulation resistance and impact resistance can be improved accordingly.
Of course, by forming the coating protective layer by printing, it is not necessary to perform a heat treatment or an accompanying work at a high temperature as in the case of the tube pack method, and the work can be facilitated and the cost can be reduced. In addition, compared to the hard pack method, a coating protective layer adhered by printing can be formed, and the effects of weight reduction and miniaturization are great.
In addition, since the coating protective layer is composed of multiple layers,
Depending on the thickness required for the coating protective layer, the thickness of the plurality of layers can be freely and accurately adjusted.
In particular, since multiple layers are composed of resins with different characteristics for each layer,
Depending on the properties required for the coating protective layer, it is possible to easily satisfy all of the required properties as a plurality of layers with resins having different properties.
According to the battery pack described in claim 2, in addition to the effect described in claim 1, the resin for the coating protective layer is polyethylene, polypropylene, polyethylene terephthalate, acrylic, polycarbonate, ABS, polystyrene, polyvinylidene chloride. , Because it is different resin for each layer from among butyl rubber, SBR, NBR, EPDM, CR,
A coating protective layer made of a different resin suitable for the requirements can be easily configured for each layer.
According to the method of manufacturing a battery pack according to claim 3, a resin cell is obtained by dissolving resins having different characteristics with a solvent to form an ink, and printing a plurality of times around the battery cell using the plurality of types of inks. Because it is decided to constitute the coating protective layer of
By printing the inked resin around the battery cell, a dense and direct coating protective layer made of resin can be easily formed around the battery cell.
Moreover, since it is a work by printing, it does not require heat shrinking treatment with high heat and many processes attached to it, compared to a tube pack method using a heat shrink tube, and compared to a hard pack method using a hard case. Therefore, it is possible to manufacture a battery pack with a very simplified and fewer manufacturing process without requiring a plurality of assembly work steps for sealing and sealing the battery cell in the hard case. it can.
Further, since the resin is used as an ink, useless resin is eliminated, and a sufficiently light battery pack can be manufactured with the minimum amount of resin.
Of course, expensive manufacturing equipment is not required, and the manufacturing cost can be sufficiently reduced as compared with the conventional method.
In particular, resin of different characteristics is dissolved in a solvent to make an ink, and using this plurality of types of ink, it is decided to constitute a battery cell coating protective layer by printing around the battery cell multiple times,
Even when various properties are required for the coating protective layer, it is very easy to print multiple inks with various resins according to the various properties. A battery pack satisfying these various characteristics can be manufactured.
According to the battery pack manufacturing method of claim 4 , in addition to the effects of the structure of claim 3, the resin used for the ink is polyethylene, polypropylene, polyethylene terephthalate, acrylic, polycarbonate, ABS, polystyrene. Since it is made of at least two kinds of resins such as polyvinylidene chloride, butyl rubber, SBR, NBR, EPDM, and CR,
Those resins using multiple several, a battery pack having a coating protective layer can be suitably respond to the required characteristics can be easily produced.
Moreover, according to the manufacturing method of the battery pack of Claim 5 , in addition to the effect by the structure of Claim 3 or 4, by printing by gravure offset printing,
There are many types of ink that can be used, and even inks in which resin is dissolved can be printed easily. Further, since the evaporation drying type ink is used, it can be easily dried and printing can be repeated many times. Therefore, the same or different types of resins can be stacked one after another, and a battery pack provided with a plurality of coating protective layers can be manufactured easily and in a short time. Moreover, the battery pack which adjusted the thickness of the coating protective layer correctly by repeating printing can be manufactured easily.
[Brief description of the drawings]
FIG. 1 is an overall perspective view showing a battery pack according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing the first embodiment of the battery pack of the present invention.
FIG. 3 is a cross-sectional view showing a second embodiment of the battery pack of the present invention.
FIG. 4 is a cross-sectional view of a main part showing a third embodiment of a battery pack of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Battery cell 11 Cell case 12 Electrolytic substance 13 Electrode 20 Coating protective layer 21 Print layer 22 Print layer 23 Print layer 111 Cell case P Battery pack

Claims (5)

  A battery pack in which the periphery of a battery cell is covered with a coating protective layer by resin printing, wherein the coating protective layer is composed of a plurality of layers and the layers are composed of resins having different characteristics for each layer. A battery pack characterized by that.   The resin for the coating protective layer is characterized in that each layer is different from polyethylene, polypropylene, polyethylene terephthalate, acrylic, polycarbonate, ABS, polystyrene, poly (vinylidene chloride), butyl rubber, SBR, NBR, EPDM, and CR. The battery pack according to claim 1. Manufacturing a battery pack characterized in that a resin cell coating protective layer is formed by dissolving a resin having different characteristics with a solvent to form an ink, and printing a plurality of times around the battery cell using these types of inks. Method. The resin used for the ink is composed of at least two kinds of resins of polyethylene, polypropylene, polyethylene terephthalate, acrylic, polycarbonate, ABS, polystyrene, poly (vinylidene chloride), butyl rubber, SBR, NBR, EPDM, and CR. The method for producing a battery pack according to claim 3. 5. The battery pack manufacturing method according to claim 3, wherein printing is performed by gravure offset printing .

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