JP4138172B2 - Electrochemical device and manufacturing method thereof - Google Patents

Description

【００６９】
【表２】

【００７０】
図３から、本発明によって密閉性が向上した結果、充放電サイクル寿命が向上したことがわかる。また表１からも従来電池内部の電解液が大幅に蒸発していたのを改善し、本発明によってほとんど完壁な密閉状態にあることがわかる、また、表２から、本発明の適用により、作成時に電池短絡を防ぐ効果があったことが認められた。
【００７１】
［実施例Ｂ］
（キャパシタの作製）
活物質：ＬｉＣｏＯ₂、
導電助剤：アセチレンブラック、
高分子物質：ＰＶＤＦ［KynarFlex 2801（エルフ・アトケム社製）］、（ポリフッ化ビニリデンと６フッ化プロピレンとの共重合体）、
溶媒：アセトン
を重量比で、活物質：導電助剤：高分子物質：溶媒＝８：１：１：１５となるように混合して高分子溶液を調製し、これをフィルム状に成形して成形体を得た。この成形体を集電体に熱圧着し、正極とした。
【００７２】
また、活物質を黒鉛とし、活物質：導電助剤：高分子物質：溶媒＝８．５：０．５：１：１５としたほかは正極の場合と同様にして、負極を作製した。
【００７３】
高分子固体電解質としてＰＶＤＦ微多孔膜を使用した。
【００７４】
次に、正極および負極を高分子固体電解質を介して積層し、両側を導出端子を有するチタン板で挟んだ後、電解液を含浸させ、実施例１と同様に密閉した。なお、電解液には、エチレンカーボネート：ジメチルカーボネート＝１：２（体積比）である混合溶媒にＬｉＰＦ₆を１Ｍの濃度で溶解したものを用いた。
【００７５】
その他は実施例１と同様にしてキャパシタ１を得た。また、実施例２、参考例１，２、比較例１と同様にしてキャパシタ２〜４，比較キャパシタ１を作製した。
【００７６】
得られたキャパシタ１，２〜４および比較キャパシタ１をキャパシタ用の充放電操作を行った以外は実施例１と同様にして評価した。結果を図４に示す。図４から明らかなように、本発明によって密閉性が向上した結果、キャパシタにおいても充放電サイクル寿命が飛躍的に向上したことがわかる。
【００７７】
【発明の効果】
以上のように、本発明の電気化学デバイスによれば、サイクル寿命、高温保存特性、作成時の短絡不良を改善することができる。
【００７８】
また、本発明の電気化学デバイスの製造方法によれば、かかる電気化学デバイスを確実に製造することができる。
【図面の簡単な説明】
【図１】本発明の電気化学デバイスの構造を示し、（ａ）は電気化学素子を構成する電極及び導出端子を示す平面図、（ｂ）は外装袋を示す平面図、（ｃ）は電気化学素子を外装袋に封入して構成される電気化学デバイスを示す平面図である。
【図２】図１（ｃ）のＡ−Ａ線に沿った断面図である。
【図３】実施例、比較例のリチウムイオン２次電池の充放電容量の充放電回数に対する変化を示すグラフである。
【図４】実施例、参考例、比較例の電気２重層キャパシタの充放電容量の充放電回数に対
する変化を示すグラフである。
【符号の説明】
１ 電気化学デバイス
１０ 電気化学素子
１１，１２ 電極
１３，１４ 導出端子
１３ａ、１４ａ シール部
２０ 外装袋
２１ 第１シール部
２２ 第２シール部
３０ ラミネートフィルム
４０ 中間層
４１ 金属−樹脂間接着剤層
４２ 絶縁性樹脂層
４３ ポリオレフィン樹脂層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrochemical device such as a polymer lithium secondary battery and an electric double layer capacitor and a manufacturing method thereof, and more particularly to an electrochemical device having improved sealing performance at a seal portion of a lead-out terminal and a manufacturing method thereof.
[0002]
[Prior art]
In recent years, secondary batteries using a carbon material, tin oxide, silicon oxide, or the like as a negative electrode active material called a lithium ion secondary battery have been used or studied in various electronic products and electric vehicles. These lithium ion secondary batteries use a so-called electrolytic solution in which an electrolyte salt is dissolved in a liquid solvent. A battery using an electrolytic solution has an advantage that the internal resistance is low. However, there is a problem that the battery easily leaks and there is a risk of ignition. In order to solve such problems, studies on electrolytes that do not contain a solvent, that is, solid electrolytes, have been conducted for many years. For example, a gel polymer solid electrolyte composed of a polymer, an electrolyte salt, and a solvent has recently attracted attention.
[0003]
Some of these gel-like solid polymer electrolytes have a conductivity close to that of a liquid and show a value on the order of 10 ⁻³ S · cm ⁻¹ .
[0004]
A battery using a polymer solid electrolyte is unlikely to leak because it does not use a liquid electrolyte. Therefore, it is not necessary to mechanically caulk with a metal container and a polymer packing in question as in a conventional battery using a liquid electrolyte. The polymer solid electrolyte battery can prevent liquid leakage to the extent that a laminated film made of a polymer film and a metal foil is used as an outer bag (container).
[0005]
However, the adhesion between the lead-out terminal (metal foil) leading from the inside of the battery to the outside and the polymer film (thermal adhesive resin layer) on the innermost surface of the laminate film is insufficient, and the battery has a sufficient sealing property. However, there was a problem in terms of the cycle life of the battery.
[0006]
In order to improve the above-mentioned drawbacks, Japanese Patent Application Laid-Open No. 10-289698 discloses an outer bag made of a laminate sheet in which a heat-fusible resin layer is fixed to both surfaces of a metal layer, positive and negative electrodes, an electrolyte, In the thin sealed battery in which the power generation element including the battery is housed, the positive and negative electrodes are each provided with a current collecting tab made of metal, and each current collecting tab is led out of the battery from the current collecting tab leading portion of the outer bag. And the said current collection tab derivation | leading-out part is sealed by heat-sealing by interposing a heat fusion property modified resin layer between the current collection tab and the exterior bag inner surface, The thin sealing characterized by the above-mentioned A battery is disclosed.
[0007]
However, the above heat-fusible modified resin layer still has a drawback that the sealing performance is not sufficient. Analysis of the cause revealed that the modified resin layer was very weak to the lithium salt-containing organic electrolyte, but it was very difficult to make a battery so that the electrolyte did not touch the terminal seal part at the time of injection. It was difficult.
[0008]
Yet another problem is that the insulation of the terminal portion is incomplete. Simply covering the inner surface of the outer bag with a low melting point resin such as polypropylene often caused a short circuit due to the metal foil used in the bag when laminating the terminal portion.
[0009]
[Problems to be solved by the invention]
An object of the present invention is to provide an electrochemical element using a polymer solid electrolyte impregnated with an organic electrolyte containing a lithium salt, with a lead-out terminal sandwiched between the thermoadhesive resin layers of the outer bag in the outer bag (container). In the electrochemical device that is heat-bonded and sealed in, the insulation between the lead-out terminal and the outer bag is not perfect, and the adhesion between the outer bag and the lead-out terminal is insufficient. It is an object of the present invention to provide an electrochemical device that can solve the problem of being unfavorable and a method for manufacturing the same.
[0010]
[Means for Solving the Problems]
Such an object is solved by the present invention described below.
(1) An electrochemical device having an outer bag and an electrochemical element enclosed in the outer bag, wherein the outer bag is a laminate film having a metal layer and a heat-adhesive resin layer, The chemical device has a lead-out terminal that is sealed and sealed with a heat-bonded seal portion between the heat-adhesive resin layers of the outer bag, and leads out to the outside through the seal portion, A metal-resin adhesive layer having a structure sandwiched between the heat-adhesive resin layers at a seal portion and directly laminated on the lead-out terminals between the lead-out terminals and the laminate film of the seal portion An electrochemical device having an intermediate layer laminated in the order of a polyolefin resin layer, an insulating resin layer, and a polyolefin resin layer.
(2) The electrochemical device according to (1), wherein the electrochemical device has both positive and negative electrodes and a polymer solid electrolyte.
(3) The electrochemical device according to (1) or (2) , which is a lithium secondary battery.
(4) The electrochemical device according to (1) or (2) , which is an electric double layer capacitor.
[0011]
(5) An electrochemical element is housed in an exterior bag, which is a laminate film having a metal layer and a thermoadhesive resin layer, and the lead-out terminals connected to both the positive and negative electrodes of the electrochemical element are connected to the thermoadhesive resin of the exterior bag. A method of manufacturing an electrochemical device that seals by sealing between layers by thermal bonding, and a metal-resin adhesive layer from the lead-out terminal side to a portion corresponding to the seal part of the lead-out terminal, A lead-out terminal coating process in which a polyolefin resin layer, an insulating resin layer, and a polyolefin resin layer are laminated in that order and thermally bonded, and a polymer between the positive and negative electrodes of the electrochemical device after the lead-out terminal coating process is completed A liquid injection step of impregnating the membrane with an electrolytic solution to obtain a solid polymer electrolyte; and an encapsulation step of sealing the electrochemical element after the liquid injection step in the outer bag with the seal portion. Method for producing an electrochemical device, wherein the door.
(6) In the lead-out terminal covering step, a metal-resin adhesive layer is formed by applying a metal-resin adhesive to a portion corresponding to the seal portion of the lead-out terminal, and the metal-resin adhesive layer The method for producing an electrochemical device according to (5) above, wherein a polyolefin resin layer, an insulating resin layer, and a polyolefin resin layer are sequentially laminated thereon.
(7) In the lead-out terminal covering step, the metal-resin adhesive layer of the fusion sheet is thermally bonded to a portion corresponding to the seal portion of the lead-out terminal. The method for producing an electrochemical device according to the above (5) , in which an inter-resin adhesive layer, a polyolefin resin layer, an insulating resin layer, and a polyolefin resin layer are laminated in this order.
[0012]
[Action]
As a result of repeated studies, the inventor covered the modified resin layer applied on the lead terminal made of metal with a polyethylene terephthalate (PET) layer, and further covered with a polypropylene (PP) layer, and then with the outer bag. It has been found that by laminating, the resistance of the seal portion to the electrolytic solution is dramatically improved and the insulation is completely maintained.
[0013]
That is, when the inner surface of the exterior bag composed of a laminate film having a metal layer and a heat-adhesive resin layer is a heat-adhesive resin layer, and a metal-resin adhesive layer is disposed between the resin and the lead-out terminal. The adhesion between the heat-adhesive resin layer on the inner surface of the outer bag and the lead-out terminal (metal such as aluminum or nickel) is improved. However, since the metal-resin adhesive layer touches the electrolyte solution and the adhesive strength deteriorates during the electrolyte solution pouring as it is, the insulating resin layer and the polyolefin resin layer are placed on the metal-resin adhesive beforehand. By providing, it can avoid that electrolyte solution contacts a metal-resin adhesive. Since the strength at the time of fusion does not drop between the polyolefin resin layer and the heat-adhesive resin of the outer bag even if an electrolyte is present, the sealing property can be maintained. In addition, if the sealing property is good, it is possible to prevent the moisture in the atmosphere from entering, so that an electrochemical device having good cycle life and high temperature storage characteristics can be obtained. Moreover, since the metal-resin adhesive can be protected, there is an advantage that the type of the adhesive is not particularly limited. Further, by sandwiching an insulating resin layer having a high melting point, the insulating resin layer is not melted even when the terminal portion is laminated, so that the insulating property can be maintained. Further, if the insulating resin layer is provided only on the terminal portion, there is an advantage that the volume of the entire bag hardly changes.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The electrochemical device of the present invention is an electrochemical device having an outer bag and an electrochemical element enclosed in the outer bag, and the outer bag is a laminate film having a metal layer and a thermoadhesive resin layer. The electrochemical device has a lead-out terminal that is sealed by being sealed with a heat-bonded seal part between the heat-adhesive resin layers of the exterior bag, and led out to the outside through the seal part, The lead-out terminal has a structure sandwiched between the heat-adhesive resin layers at the seal portion, and is directly laminated on the lead-out terminal between the lead-out terminal and the laminate film of the seal portion. -It has an intermediate | middle layer laminated | stacked in order of the adhesive layer between resin, the insulating resin layer, and the olefin resin layer.
[0015]
Preferably, it has positive and negative electrodes and a polymer solid electrolyte, and the intermediate layer further has an olefin resin layer between the metal-resin adhesive layer and the insulating resin layer.
[0016]
Next, the electrochemical device of the present invention will be specifically described with reference to the drawings. FIG. 1 shows a schematic structure of the electrochemical device of the present invention. FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1C and shows a cross-sectional structure of the seal portion including the lead-out terminal.
[0017]
The electrochemical device 1 shown in FIG. 1 (c) includes an electrochemical device 10 shown in FIG. 1 (a) in an outer bag 20 formed in a bag shape by a first seal portion 21 shown in FIG. 1 (b). The lead-out terminals 13 and 14 of the electrochemical element 10 are housed in a state of projecting to the outside, and the open end face of the outer bag 20 is sealed by thermal fusion with the lead-out terminals 13 and 14 sandwiched therebetween to form the second seal portion 22. Formed and configured. The electrochemical device 1 has a structure in which the electrochemical element 10 is sealed in the outer bag 20 and the lead-out terminals 13 and 14 protrude from the second seal portion 22 to the outside.
[0018]
The electrochemical element 10 includes positive and negative electrodes 11 and 12 made of metal foil such as aluminum foil and copper foil, and a polymer solid electrolyte (not shown). Lead electrodes 13 and 14 are connected to the positive and negative electrodes 11 and 12, respectively, as shown in FIG. The lead terminals 13 and 14 are made of a metal foil such as aluminum, copper, nickel, and stainless steel. The lead-out terminals 13 and 14 have seal portions 13a and 14a that are regions covered by the second seal portion 22 in concept.
[0019]
The exterior bag 20 is composed of a laminate film 30 in which a polyolefin resin layer such as polypropylene or polyethylene as a heat-adhesive resin layer or a heat-resistant insulating resin layer is laminated on both surfaces of a metal layer such as aluminum. . As shown in FIG.1 (b), the exterior bag 20 forms the 1st seal | sticker part 21 by heat-adhering the heat bonding resin layers of the end surfaces of those 3 sides to the laminate film 30 of 2 sheets beforehand, It is formed in a bag shape with one side open. Alternatively, a single laminate film may be folded and the end faces of both sides may be thermally bonded to form a seal portion to form a bag.
[0020]
In the second seal portion of the electrochemical device 1 of the present invention, as shown in FIG. 2, the lead-out terminals 13 and 14 are sandwiched between laminate films 30 constituting the outer bag 20, and the lead-out terminals 13 and 14 and the outer bag The metal-resin adhesive layer 41 directly laminated on the lead-out terminals 13 and 14 and the metal-resin adhesive layer 41 are interposed between the heat-adhesive resin layers of the laminate film 30 constituting the substrate 20. The intermediate layer 40 is formed by covering and covering the insulating resin layer 42 and the olefin resin layer 43 in this order.
[0021]
Conventionally, the adhesion between the lead-out terminal constituted by such a metal foil and the heat-adhesive resin layer constituting the exterior bag has been insufficient. In the electrochemical device 1 of the present invention, the metal-resin adhesive layer 41 is directly laminated so as to cover the seal portions 13a, 14a of the lead-out terminals 13, 14, and metal (aluminum, copper, nickel, stainless steel, etc.) It maintains adhesion to polyolefin and the like, and is an indispensable material for drawing out the lead-out terminal from the laminate bag and keeping the seal.
[0022]
Examples of the metal-resin adhesive layer 41 include acid-modified polyethylene such as carboxylic acid, acid-modified polypropylene, epoxy resin, polyisocyanate, and the like. The metal-resin adhesive layer 41 is interposed between a metal and an adhesive resin such as a polyolefin resin to improve the adhesiveness thereof, and is therefore sufficient to cover the sealing portion of the lead-out terminal. The size is sufficient. The thickness of the metal-resin adhesive layer 41 is preferably about 1 to 100 μm.
[0023]
In the present invention, in order to further protect the metal-resin adhesive layer 41 from the electrolytic solution, the insulating resin layer 42 and the olefin resin layer 43 are arranged in this order from the lead-out terminal side. 41 and the outer bag 20 are interposed.
[0024]
The insulating resin layer 42 is preferably a thermosetting resin or a high melting point resin having a melting point of 180 ° C. or higher. Since the insulating resin layer does not melt when thermally bonded, the lead terminals 13 and 14 and the laminate film The insulating property between the 30 metal layers can be maintained. Therefore, the thickness of the insulating resin layer 42 is preferably about 5 to 100 μm. Examples of the high melting point resin include polyethylene terephthalate (PET: mp 190 to 265 ° C.), nylon (mp 190 to 265 ° C.), polytetrafluoroethylene (mp 327), polybutylene terephthalate (mp 225 ° C.), and polycarbonate (mp 220 to 230 ° C.). Etc. Examples of the thermosetting resin include an epoxy resin and polyurethane. Note that the resin is not limited to these resins as long as it can prevent leakage and ensure insulation.
[0025]
Since the polyolefin resin layer 43 is excellent in mutual adhesiveness with the polyolefin resin layer of the laminate film 30, it functions as a heat-adhesive resin layer. The thickness of the polyolefin resin layer 43 is preferably about 10 to 200 μm. Examples of the polyolefin include polyethylene, polypropylene, and acid-modified products thereof. Because of compatibility, when the heat-adhesive resin layer of the laminate film 30 is polyethylene, the polyolefin resin layer 43 of the intermediate layer 40 is also polyethylene, and when the heat-adhesive resin layer of the laminate film 30 is polypropylene, the intermediate layer 40 is used. The polyolefin resin layer 43 is preferably made of polypropylene from the viewpoint of adhesiveness. Furthermore, a polyolefin resin layer is preferably interposed between the metal-resin adhesive layer 41 and the insulating resin layer 42 in order to improve the adhesiveness.
[0026]
Derived by such an intermediate layer 40 composed of a metal-resin adhesive layer / insulating resin layer / polyolefin resin layer or a metal-resin adhesive layer / polyolefin resin layer / insulating resin layer / polyolefin resin layer. In the lead-out terminal covering step for covering the seal portions 13a and 14a of the terminals 13 and 14, for example, a metal-resin adhesive is applied to both sides of the seal portions 13a and 14a of the lead-out terminal, and then an insulating resin layer / polyolefin resin layer Alternatively, it is possible to employ a method in which a fusion film composed of polyolefin resin layer / insulating resin layer / polyolefin resin layer is thermally welded onto the metal-resin adhesive layer. Alternatively, a fusion film composed of a metal-resin adhesive layer / insulating resin layer / polyolefin resin layer, or a metal-resin adhesive layer / polyolefin resin layer / insulating resin layer / polyolefin resin layer is derived from the terminal. A method of heat welding to the seal portions 13a and 14a of the 13 and 14 can be employed. In the lead terminal covering step, the lead terminal may be welded or bonded to the battery or the electric double layer capacitor before electrolyte injection, or may be a single terminal. In any case, the intermediate layer 40 of the present invention needs to be attached to the lead-out terminals 13 and 14 before the electrolyte solution injection.
[0027]
The polyolefin film and the fusion film may be in a tube shape. In the case of a tube shape, a tube cut to the length of the seal portions 13a and 14a is inserted into the lead-out terminal, and is covered with the seal portions 13a and 14a and heat-sealed.
[0028]
After the lead-out terminal covering step, the battery positive electrode and the negative electrode including the lead-out terminal subjected to the above treatment and an element composed of the battery negative electrode and the polymer film are immersed in a lithium salt-containing organic electrolyte so that the electrolyte is impregnated. A liquid injection process is performed in which an electrochemical device is produced by converting the solid electrolyte into a solid electrolyte. By this step, the polymer solid electrolyte is gelled.
[0029]
Thereafter, the electrochemical device is inserted into a laminate bag made of a metal and a resin, and the opening is heat sealed and sealed to form an electrochemical device.
[0030]
The electrochemical device of the present invention can be used as the following lithium secondary battery and electric double layer capacitor.
[0031]
<Lithium secondary battery>
The structure of the lithium secondary battery of the present invention is not particularly limited, but is usually composed of a positive electrode, a negative electrode, and a polymer solid electrolyte, and is applied to a laminated battery, a cylindrical battery, and the like.
[0032]
The electrode combined with the solid electrolyte may be appropriately selected from known ones as electrodes for lithium secondary batteries, and preferably a composition of an electrode active material and a gel electrolyte and, if necessary, a conductive assistant is used. .
[0033]
The negative electrode uses a negative electrode active material such as a carbon material, lithium metal, lithium alloy or oxide material, and the positive electrode such as an oxide or carbon material capable of intercalating / deintercalating lithium ions. It is preferable to use a positive electrode active material. By using such an electrode, a lithium secondary battery having good characteristics can be obtained.
[0034]
The carbon material used as the electrode active material may be appropriately selected from, for example, mesocarbon microbeads (MCMB), natural or artificial graphite, resin-fired carbon material, carbon black, carbon fiber, and the like. These are used as powders. Of these, graphite is preferable, and the average particle size is preferably 1 to 30 μm, particularly preferably 5 to 25 μm. When the average particle size is too small, the charge / discharge cycle life is shortened and the capacity variation (individual difference) tends to increase. When the average particle diameter is too large, the variation in capacity becomes remarkably large and the average capacity becomes small. The reason why the variation in capacity occurs when the average particle size is large is thought to be because the contact between graphite and the current collector or the contact between graphites varies.
[0035]
The oxide capable of intercalating and deintercalating lithium ions is preferably a composite oxide containing lithium, and examples thereof include LiCoO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , and LiV ₂ O ₄ . The average particle diameter of these oxide powders is preferably about 1 to 40 μm.
[0036]
If necessary, a conductive additive is added to the electrode. Preferred examples of the conductive aid include metals such as graphite, carbon black, carbon fiber, nickel, aluminum, copper, and silver, and graphite and carbon black are particularly preferable.
[0037]
The electrode composition is preferably in the range of active material: conducting aid: gel electrolyte = 30 to 90: 3 to 10:10 to 70 by weight ratio in the positive electrode, and active material: conducting aid in weight ratio in the negative electrode. : Gel electrolyte = The range of 30-90: 0-10: 10-70 is preferable. The gel electrolyte is not particularly limited, and a commonly used gel electrolyte may be used. Moreover, the electrode which does not contain a gel electrolyte is also used suitably. In this case, a fluororesin, fluororubber, or the like can be used as the binder, and the amount of the binder is about 3 to 30 wt%.
[0038]
In manufacturing the electrode, first, an active material and, if necessary, a conductive additive are dispersed in a gel electrolyte solution or a binder solution to prepare a coating solution.
[0039]
And this electrode coating liquid is apply | coated to a collector. The means for applying is not particularly limited, and may be appropriately determined according to the material and shape of the current collector. In general, a metal mask printing method, an electrostatic coating method, a dip coating method, a spray coating method, a roll coating method, a doctor blade method, a gravure coating method, a screen printing method and the like are used. Then, if necessary, a rolling process is performed using a flat plate press, a calendar roll, or the like.
[0040]
The current collector may be appropriately selected from ordinary current collectors according to the shape of the device used by the battery, the method of arranging the current collector in the case, and the like. Generally, aluminum or the like is used for the positive electrode, and copper, nickel, or the like is used for the negative electrode. In addition, a metal foil, a metal mesh, etc. are normally used for a collector. The metal mesh has a smaller contact resistance with the electrode than the metal foil, but a sufficiently small contact resistance can be obtained even with the metal foil.
[0041]
Then, the solvent is evaporated to produce an electrode. The coating thickness is preferably about 50 to 400 μm.
[0042]
As the polymer film, for example, a polymer microporous film such as PEO (polyethylene oxide), PAN (polyacrylonitrile), PVDF (polyvinylidene fluoride), or the like can be used.
[0043]
Such a positive electrode, a polymer film, and a negative electrode are laminated in this order, and pressed to form a battery body.
[0044]
The electrolytic solution impregnated in the polymer membrane generally comprises an electrolyte salt and a solvent. As the electrolyte salt, for example, a lithium salt such as LiBF ₄ , LiPF ₆ , LiAsF ₆ , LiSO ₃ CF ₃ , LiClO ₄ , LiN (SO ₂ CF ₃ ) ₂ can be applied.
[0045]
The solvent of the electrolytic solution is not particularly limited as long as it has good compatibility with the above-described solid polymer electrolyte and electrolyte salt, but a polar organic solvent that does not decompose even at a high operating voltage in a lithium battery, for example, , Ethylene carbonate (abbreviation EC), propylene carbonate (abbreviation PC), butylene carbonate, dimethyl carbonate (abbreviation DMC), carbonates such as diethyl carbonate and ethyl methyl carbonate, cyclic ethers such as tetrahydrofuran (THF) and 2-methyltetrahydrofuran Cyclic ethers such as 1,3-dioxolane and 4-methyldioxolane, lactones such as γ-butyrolactone, sulfolane and the like are preferably used. 3-methylsulfolane, dimethoxyethane, diethoxyethane, ethoxymethoxyethane, ethyl diglyme and the like may be used.
[0046]
The concentration of the electrolyte salt when it is considered that the electrolytic solution is composed of the solvent and the electrolyte salt is preferably 0.3 to 5 mol / l. Usually, the highest ionic conductivity is shown around 1 mol / l.
[0047]
When a microporous polymer film is immersed in such an electrolyte solution, the polymer film absorbs the electrolyte solution and gels to form a solid polymer electrolyte.
[0048]
When the composition of the polymer solid electrolyte is represented by a copolymer / electrolytic solution, the ratio of the electrolytic solution is preferably 40 to 90 wt% from the viewpoint of the strength of the membrane and the ionic conductivity.
[0049]
<Electric double layer capacitor>
The structure of the electric double layer capacitor of the present invention is not particularly limited, but usually, a pair of polarizable electrodes are arranged via a polymer solid electrolyte, and an insulating property is provided around the polarizable electrode and the polymer solid electrolyte. A gasket is arranged. Such an electric double layer capacitor may be any of so-called coin type, paper type, laminated type and the like.
[0050]
As a polarizable electrode, activated carbon, activated carbon fiber, or the like is used as a conductive active material, and a fluororesin, fluororubber, or the like is added as a binder. And it is preferable to use what formed this mixture in the sheet-like electrode. The amount of the binder is about 5 to 15 wt%. A gel electrolyte may be used as the binder.
[0051]
The current collector used for the polarizable electrode may be a conductive rubber such as platinum or conductive butyl rubber, or may be formed by thermal spraying of a metal such as aluminum or nickel. A mesh may be attached.
[0052]
An electric double layer capacitor is combined with a polarizable electrode as described above and a solid polymer electrolyte.
[0053]
As the polymer film, for example, a polymer microporous film such as PEO (polyethylene oxide), PAN (polyacrylonitrile), PVDF (polyvinylidene fluoride), or the like can be used.
[0054]
Examples of the electrolyte salt include (C ₂ H ₅ ) ₄ NBF ₄ , (C ₂ H ₅ ) ₃ CH ₃ NBF ₄ , (C ₂ H ₅ ) ₄ PBF _{4, and the} like.
[0055]
The non-aqueous solvent used in the electrolytic solution may be various known ones, and is an electrochemically stable non-aqueous solvent such as propylene carbonate, ethylene carbonate, γ-butyrolactone, acetonitrile, dimethylformamide, 1,2-dimethoxy. Ethane, sulfolane alone or a mixed solvent is preferred.
[0056]
The concentration of the electrolyte in such a nonaqueous solvent electrolyte solution may be 0.1 to 3 mol / l.
[0057]
An insulating material such as polypropylene or butyl rubber may be used as the insulating gasket.
[0058]
【Example】
[Example A] [Example 1]
(Preparation of battery) Aluminum foil and nickel foil having a width of 4 mm, a length of 50 mm and a thickness of 0.1 mm were prepared as terminal materials. After spraying acid-modified polypropylene (Mitsui Chemicals Unistar R-200) as a metal-resin adhesive on the seal portion, a sheet of PP40 μm / PET 15 μm / PP40 μm of 5 mm in length and width is attached to the seal portion. A lead-out terminal was placed on top and bottom and heat-pressed.
[0059]
The electrode was prepared by applying a positive electrode made of LiCoO ₂ , carbon black (HS-100, manufactured by Denki Kagaku Kogyo), and PVDF (polyvinylidene fluoride) to an aluminum foil by a doctor blade method. The negative electrode was prepared by applying mesocarbon microbeads (MCMB), HS-100, and PVDF to a copper foil by the doctor blade method. A PVDF microporous membrane was used as the polymer solid electrolyte. The positive electrode and the negative electrode were cut into a width of 31 mm and a length of 41 mm. The separator was cut to a width of 33 mm and a length of 43 mm.
[0060]
The battery element was produced as follows. First, a positive electrode and a separator were laminated and laminated by hot pressing. Lamination was performed at 150 ° C. for 2 minutes at a pressure of 5 kgcm ⁻² . A negative electrode was laminated thereon and laminated in the same manner.
[0061]
The aluminum lead-out terminal of the battery body and the nickel lead-out terminal were similarly resistance-welded to the copper current collector. This battery body was immersed for 30 minutes in 330 ml of an electrolytic solution in which 1 M of LiPF ₆ was dissolved in a mixed solvent of EC (ethylene carbonate) and DMC (dimethyl carbonate) in a volume ratio of 1: 2. After removing the battery body from the electrolytic solution, the electrolytic solution adhering to the electrode surface was wiped off. The battery body absorbed the electrolyte and became a gel state. The battery body is inserted into a laminate bag (the innermost layer is PP) made of PET (12 μm) / aluminum (20 μm) / PP (40 μm), the opening is heat sealed, and a sheet-type polymer lithium ion secondary battery is manufactured. did. The melting point mp of PET was 250 ° C.
[0062]
FIG. 3 shows the relationship between the number of cycles and the discharge capacity. Table 1 shows the weight reduction rate when another battery was stored at 110 ° C. Table 1 shows the weight loss rate of five samples. In addition, the weight reduction rate was calculated | required with the following formula.
[0063]
Weight reduction rate (%) = ((battery weight after storage at 110 ° C.) − (Battery weight before storage)) / (weight of electrolyte contained in battery) × 100
Table 2 shows the number of short-circuit products that occurred when this battery was produced.
[0064]
[Example 2]
(Production of battery)
Prepare a sheet having a structure of 20 μm / PP40 μm / PET15 μm / PP40 μm without modifying acid-modified polypropylene on the aluminum foil and nickel foil of the terminal material, and acid-modified polypropylene (Mitsui Chemicals Co., Ltd., Enister R-200). The experiment was performed in the same manner as in Example 1 except that the terminal was fused.
[0065]
[Reference Example 1]
(Preparation of battery) Similar to Example 1 except that acid-modified polypropylene was sprayed on aluminum foil and nickel foil as terminal materials, and then a sheet having a structure of PET 15 μm / PP 40 μm was prepared and fused to the terminals. The experiment was conducted.
[0066]
[Reference Example 2]
(Production of battery) Acid-modified polypropylene is not sprayed on the aluminum foil and nickel foil of the terminal material, and a sheet having a structure of 20 μm / PET 15 μm / PP 40 μm of acid-modified polypropylene (Mitsui Chemicals Co., Ltd. Enister R-200) is prepared. The experiment was conducted in the same manner as in Example 1 except that this was fused to the terminal.
[0067]
[Comparative Example 1]
(Production of battery)
A sheet-type lithium ion secondary battery as in Example 1, except that acid-modified polypropylene (Enistor R-200 from Mitsui Chemicals, Inc.) was sprayed onto the terminals and the protective sheet was not fused. Was made.
[0068]
[Table 1]

[0069]
[Table 2]

[0070]
FIG. 3 shows that the charge / discharge cycle life is improved as a result of the improved sealing performance according to the present invention. Moreover, it can be seen from Table 1 that the electrolyte in the battery has been largely evaporated, and it can be seen that the present invention is almost completely sealed by the present invention. It was recognized that there was an effect of preventing a battery short circuit at the time of preparation.
[0071]
[Example B]
(Capacitor production)
Active material: LiCoO ₂ ,
Conductive aid: acetylene black,
Polymer material: PVDF [KynarFlex 2801 (manufactured by Elf Atchem)], (copolymer of polyvinylidene fluoride and hexafluoropropylene),
A polymer solution is prepared by mixing the solvent: acetone in a weight ratio such that the active material: conducting aid: polymer material: solvent = 8: 1: 1: 15, and this is formed into a film. A molded body was obtained. This molded body was thermocompression bonded to a current collector to obtain a positive electrode.
[0072]
Further, a negative electrode was produced in the same manner as in the case of the positive electrode except that graphite was used as the active material, and active material: conductive aid: polymer material: solvent = 8.5: 0.5: 1: 15.
[0073]
A PVDF microporous membrane was used as the polymer solid electrolyte.
[0074]
Next, the positive electrode and the negative electrode were laminated via a polymer solid electrolyte, and both sides were sandwiched between titanium plates having lead-out terminals, impregnated with an electrolytic solution, and sealed in the same manner as in Example 1. Note that the electrolytic solution, ethylene carbonate: dimethyl carbonate = 1: LiPF ₆ was used at a concentration of 1M in a mixed solvent of 2 (volume ratio).
[0075]
Other than that, a capacitor 1 was obtained in the same manner as in Example 1. Further, capacitors 2 to 4 and comparative capacitor 1 were fabricated in the same manner as in Example 2, Reference Examples 1 and 2, and Comparative Example 1.
[0076]
The obtained capacitors 1, 2 to 4 and comparative capacitor 1 were evaluated in the same manner as in Example 1 except that the capacitor charge / discharge operation was performed. The results are shown in FIG. As can be seen from FIG. 4, as a result of the improved sealing performance according to the present invention, the charge / discharge cycle life of the capacitor is also dramatically improved.
[0077]
【The invention's effect】
As described above, according to the electrochemical device of the present invention, it is possible to improve cycle life, high-temperature storage characteristics, and short-circuit failure during production.
[0078]
Moreover, according to the manufacturing method of the electrochemical device of this invention, this electrochemical device can be manufactured reliably.
[Brief description of the drawings]
FIG. 1 shows the structure of an electrochemical device of the present invention, wherein (a) is a plan view showing electrodes and lead-out terminals constituting the electrochemical element, (b) is a plan view showing an outer bag, and (c) is an electric diagram. It is a top view which shows the electrochemical device comprised by enclosing a chemical element in an exterior bag.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
FIG. 3 is a graph showing changes in charge / discharge capacities of lithium ion secondary batteries of examples and comparative examples with respect to the number of charge / discharge cycles.
FIG. 4 is a graph showing changes in charge / discharge capacities of electric double layer capacitors of Examples, Reference Examples, and Comparative Examples with respect to the number of charge / discharge cycles.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electrochemical device 10 Electrochemical element 11,12 Electrode 13,14 Derivation | leading-out terminal 13a, 14a Seal part 20 Outer bag 21 First seal part 22 Second seal part 30 Laminate film 40 Intermediate layer 41 Metal-resin adhesive layer 42 Insulating resin layer 43 Polyolefin resin layer

Claims (7)

An electrochemical device having an outer bag and an electrochemical element enclosed in the outer bag,
The outer bag is a laminate film having a metal layer and a heat-adhesive resin layer,
The electrochemical device has a lead-out terminal sealed and sealed with a heat-bonded seal part between the heat-adhesive resin layers of the outer bag, and led out to the outside through the seal part,
The lead-out terminal has a structure sandwiched between the thermal adhesive resin layers at the seal portion,
The metal-resin adhesive layer, the polyolefin resin layer, the insulating resin layer, and the polyolefin resin layer that are directly laminated on the lead-out terminal are laminated in this order between the lead-out terminal of the seal portion and the laminate film. Electrochemical device having an intermediate layer.   The electrochemical device according to claim 1, wherein the electrochemical device has both positive and negative electrodes and a solid polymer electrolyte. The electrochemical device according to claim 1, which is a lithium secondary battery. The electrochemical device according to claim 1, which is an electric double layer capacitor. The electrochemical element is housed in an exterior bag that is a laminate film having a metal layer and a heat-adhesive resin layer,
A lead-out terminal connected to the positive and negative electrodes of this electrochemical element is sandwiched between the heat-adhesive resin layers of the outer bag to form a seal portion by thermal bonding, and is a method for manufacturing an electrochemical device for sealing,
The portion of the lead-out terminal corresponding to the seal portion is sandwiched and thermally bonded from the lead-out terminal side by an intermediate layer in which a metal-resin adhesive layer, a polyolefin resin layer, an insulating resin layer, and a polyolefin resin layer are laminated in this order. A lead terminal covering step;
A liquid injection step of impregnating an electrolytic solution into a polymer film between the positive and negative electrodes of the electrochemical device after the lead terminal covering step to obtain a solid polymer electrolyte;
And a sealing step of sealing the electrochemical element after the liquid injection step in the outer bag with the seal portion. The lead terminal covering step includes
A metal-resin adhesive layer is formed by applying a metal-resin adhesive to a portion corresponding to the seal portion of the lead-out terminal,
The method for producing an electrochemical device according to claim 5 , wherein a polyolefin resin layer, an insulating resin layer, and a polyolefin resin layer are sequentially laminated on the metal-resin adhesive layer. The lead terminal covering step includes
The portion corresponding to the seal portion of the lead-out terminal is thermally bonded to the metal-resin adhesive layer of the fusion sheet,
6. The method of manufacturing an electrochemical device according to claim 5 , wherein the fusion sheet is laminated in the order of a metal-resin adhesive layer, a polyolefin resin layer, an insulating resin layer, and a polyolefin resin layer.

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