JP3891054B2 - Structure of electrode tab lead-out part of stacked battery - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention uses a laminate film for the exterior of a power generation element of a battery, and joins the peripheral portion thereof by thermal welding, and the tabs connected to the positive and negative plates of the power generation element are outward from the joint portion of the laminate film. The present invention relates to an electrode tab extraction portion structure of a stacked battery that is drawn out.
[0002]
[Prior art]
In recent years, air pollution caused by exhaust gas from automobiles has become a global problem, and electric cars powered by electricity and hybrid cars that run in combination with an engine and a motor are attracting attention and will be installed in these. The development of high-power batteries with high energy density and high power density occupies an important industrial position.
[0003]
Examples of such a high-power battery include a lithium ion battery. In this case, a cylindrical battery wound with a separator interposed between a positive electrode plate and a negative electrode plate, a flat positive electrode plate and a negative electrode plate, There is a laminated battery in which the separator is laminated with a separator interposed.
[0004]
In the latter stacked type battery, both sides of a flat power generation element are sandwiched between a pair of laminate films, and the periphery is joined by thermal welding to seal the electrolyte together with the power generation element. In such a laminated battery, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2000-77044, electrode tabs respectively connected to the positive electrode plate and the negative electrode plate are drawn out from the bonded portion of the laminate film. .
[0005]
At this time, in order to connect the positive electrode plate and the negative electrode plate to the respective electrode tabs, the metal foil electrode leads drawn out from the positive and negative electrode plates are directly welded to the electrode tabs. It is necessary to take out electricity by connecting a conductor such as a connection line.
[0006]
[Problems to be solved by the invention]
By the way, when the battery is used under vibration generation conditions, for example, when the battery is mounted on an electric vehicle or a hybrid car, the vehicle body vibration is directly transmitted to the electrode tab via the electric extraction conductor.
[0007]
Since the vibration transmitted to the electrode tab is input to the electrode lead formed of metal foil, there is a possibility that mechanical damage such as breakage of the electrode lead is caused inside the battery.
[0008]
Therefore, an object of the present invention is to prevent mechanical damage inside the battery by suppressing vibrations input from the outside through the electrode tab.
[0009]
[Means for Solving the Problems]
The electrode tab lead-out structure of the laminated battery according to the present invention covers both sides of a power generating element laminated with a separator interposed between a positive electrode plate and a negative electrode plate with a laminate film having a metal layer and a resin layer. The laminate film is joined to the periphery by heat welding to seal the power generating element, and the positive electrode tab and the negative electrode tab electrically connected to the positive electrode plate and the negative electrode plate through electrode leads, respectively, from junction drawer outward, in the electrode tab extraction part structure of the stacked type battery to take out electricity from the distal end portion of the positive electrode tab and negative electrode tab, wherein from the tip of the positive electrode tab and the negative electrode tab to the electrode lead the vibration absorbing portion while reaching the connecting portion is provided, the vibration absorbing portion is located at the periphery of the laminate film, lamination Phil With a positive electrode tab and negative electrode tab, it is constituted that has the positive electrode plate and a convex portion which projects toward at least one of the laminating direction of the negative electrode plate.
[0010]
【The invention's effect】
According to the electrode tab take-out portion structure of the multilayer battery of the present invention, the vibration transmitted from the tip portion to the positive electrode tab and the negative electrode tab becomes a vibration absorbing portion provided between the connection portion to the electrode lead. Therefore, vibrations can be prevented or effectively suppressed from being input to electrode leads made of low-strength materials such as metal foil, and mechanical damage such as broken electrode leads can be prevented. be able to.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described with reference to the drawings.
[0012]
1-6 has shown 1st Embodiment of the electrode tab extraction part structure of the laminated battery concerning this invention. 1 is a plan view of the battery, FIG. 2 is a cross-sectional view of the main part along the line AA in FIG. 1, FIG. 3 is an enlarged cross-sectional view along the line BB in FIG. 5 is an enlarged cross-sectional view of a portion D in FIG. 3, and FIG. 6 is an enlarged cross-sectional view of a main portion showing the function of a vibration absorbing portion provided on the electrode tab.
[0013]
In the laminated battery 10 to which the electrode tab lead-out structure of the first embodiment is applied, a flat laminated electrode 11 as a power generation element is arranged at the center of the laminated films 12 and 13 as shown in FIG. These laminated films 12 and 13 are covered so that both surfaces (front and back directions in the figure) of the laminated electrode 11 are sandwiched.
[0014]
Then, as shown in FIG. 2, the peripheral portions of the laminate films 12 and 13 are joined by thermal welding (joined portion 16), thereby sealing the electrolyte solution together with the laminated electrode 11 between the laminate films 12 and 13. Although the laminate films 12 and 13 are actually formed thin, they are exaggerated in the figure and displayed thick.
[0015]
As shown in FIG. 3, the laminated electrode 11 is formed by sequentially laminating a plurality of positive plates 11A, 11A... And negative plates 11B, 11B. Each of the positive plates 11A, 11A... Is connected to the positive electrode tab 14 via positive leads 11D, 11D... Formed of metal foil, and each of the negative plates 11B, 11B. Are connected to the negative electrode tab 15 via. The positive electrode tab 14 and the negative electrode tab 15 are drawn outward from the joint portion 16 of the laminate films 12 and 13.
[0016]
Then, bus bars (or connection wires) 17 and 18 as conductors are connected to the tip portions of the positive electrode tab 14 and the negative electrode tab 15 drawn out from the joint portion 16 by brazing or welding. Electricity is taken out from the laminated battery 10 through the bus bars 17 and 18. In the present embodiment, as will be described later, since the stacked battery 10 is configured as a secondary battery, electricity is taken in from the bus bars 17 and 18 during charging.
[0017]
Further, as shown in FIG. 4, the laminate films 12 and 13 are formed of a nylon layer α as a resin layer, an adhesive layer β, an aluminum foil layer γ as a metal layer, a resin from the outside toward the inside (joint portion 16). The layer is composed of PE (polyethylene) or PP (polypropylene) layer δ.
[0018]
As the battery 10 thus configured, for example, there is a lithium ion secondary battery. In this case, as the positive electrode active material of the positive electrode forming the positive electrode plates 11A, 11A,. Specifically, the general formula LiNi _1-x MxO ₂ (where 0.01 ≦ x ≦ 0.5, M is Fe, Co, Mn, Cu, Zn, Al, Sn, B, Ga, Cr, V, Ti, Mg And at least one of Ca and Sr.).
[0019]
The positive electrode can also contain a positive electrode active material other than the lithium nickel composite oxide. As the positive electrode active material other than the lithium nickel composite oxide, for example, a general formula LiyMn _2-z M′zO ₄ (where 0.9 ≦ y ≦ 1.2, 0.01 ≦ z ≦ 0.5, and M ′ is Fe, Co, Ni, And at least one of Cu, Zn, Al, Sn, B, Ga, Cr, V, Ti, Mg, Ca, and Sr.). In addition, the general formula LiCo _1-x MxO ₂ (where 0.01 ≦ x ≦ 0.5, M is Fe, Ni, Mn, Cu, Zn, Al, Sn, B, Ga, Cr, V, Ti, Mg, Ca , And at least one of Sr.) may be included.
[0020]
Lithium nickel composite oxide, lithium manganese composite oxide and lithium cobalt composite oxide are mixed with carbonates such as lithium, nickel, manganese, cobalt, etc., depending on the composition. It is obtained by firing in the temperature range. The starting material is not limited to carbonates, and can be synthesized in the same manner from hydroxides, oxides, nitrates, organic acid salts, and the like.
[0021]
The average particle size of the positive electrode active material such as lithium nickel composite oxide or lithium manganese composite oxide is preferably 30 μm or less.
[0022]
As the negative electrode active material forming the negative electrode plate 11B, 11B, a ... a specific surface area to use a 0.05 m ² / g or more, a range of 2m ² / g. By setting it as this range, formation of SEI (Solid Electrolyte Interface) on the negative electrode surface can be sufficiently suppressed.
[0023]
When the specific surface area of the negative electrode active material is less than 0.05 m ² / g, the place where lithium can enter and exit is too small, so that the lithium doped in the negative electrode active material during charging is sufficient from the negative electrode active material during discharge. Therefore, the charge and discharge efficiency is reduced. On the other hand, when the specific surface area of the negative electrode active material exceeds 2 m ² / g, SEI formation on the negative electrode surface cannot be controlled.
[0024]
Any material can be used as the negative electrode active material as long as the material can be doped / undoped with lithium in a range where the potential with respect to lithium is 2.0 V or less. Specifically, a non-graphitizable carbon material, an artificial material can be used. Graphite, natural graphite, pyrolytic graphite, coke such as pitch coke, needle coke and petroleum coke, graphite, glassy carbon, phenolic resin, furan resin, etc. It is possible to use carbonaceous materials such as fired bodies, carbon fibers, activated carbon, and carbon black.
[0025]
Metals capable of forming alloys with lithium and alloys thereof can also be used. Specifically, iron is doped with lithium at a relatively low potential such as iron oxide, ruthenium oxide, molybdenum oxide, tungsten oxide, and tin oxide. In addition to oxides to be dedoped, nitrides thereof, group 3B typical elements, elements such as Si and Sn, or, for example, MxSi, MxSn (where M represents one or more metal elements excluding Si or Sn. Si and Sn alloys represented by () can be used. Among these, it is particularly preferable to use Si or Si alloy.
[0026]
Further, as the electrolytic solution, in addition to a liquid one prepared by dissolving an electrolyte salt in a non-aqueous solvent, a polymer gel electrolyte in which a solution obtained by dissolving an electrolyte salt in a non-aqueous solvent is held in a polymer matrix. Also good.
[0027]
When a polymer gel electrolyte is used as the non-aqueous electrolyte, examples of the polymer material to be used include polyvinylidene fluoride and polyacrylonitrile.
[0028]
As the non-aqueous solvent, any non-aqueous solvent used so far in this type of non-aqueous electrolyte secondary battery can be used, for example, propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, diethyl carbonate. Dimethyl carbonate, γ-butyrolactone, tetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, diethyl ether, sulfolane, methyl sulfolane, acetonitrile, propionitrile and the like. In addition, these non-aqueous solvents may be used individually by 1 type, and may mix and use 2 or more types.
[0029]
In particular, the non-aqueous solvent preferably contains an unsaturated carbonate, and specifically, preferably contains vinylene carbonate, ethylene ethylidene carbonate, ethylene isopropylidene carbonate, propylidene carbonate, and the like. Among these, it is most preferable to contain vinylene carbonate. By containing unsaturated carbonate as the non-aqueous solvent, it is considered that the effect due to the properties of SEI (function of the protective film) produced in the negative electrode active material is obtained, and the overdischarge resistance is further improved.
[0030]
The unsaturated carbonate is preferably contained in the electrolyte in a proportion of 0.05% by weight or more and 5% by weight or less, and particularly preferably 0.5% by weight or more and 3% by weight or less. By setting the unsaturated carbonate content in the above range, a non-aqueous secondary battery having a high initial discharge capacity and a high energy density is obtained.
[0031]
The electrolyte salt is not particularly limited as long as it is a lithium salt exhibiting ionic conductivity.For example, LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiB (C ₆ H ₅ ) ₄ , LiCl, LiBr, CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, etc. can be used. These electrolyte salts may be used alone or in combination of two or more.
[0032]
Here, in the present embodiment, vibrations occur between the connecting portions P1, P2 of the positive electrode tab 14 and the negative electrode tab 15 to the bus bars 17, 18 to the connecting portions Q1, Q2 to the electrode leads 11D, 11E. A convex portion 20 as an absorbing portion is formed so as to protrude upward in the drawing.
[0033]
The convex portion 20 is located inside the joint portion 16 where the peripheral portions of the laminate films 12 and 13 are heat-welded, and the positive and negative tabs 14 and 15 together with the laminate films 12 and 13 are arranged upward in FIG. It has a shape that protrudes in an arch shape toward.
[0034]
That is, the laminate films 12 and 13 at the positions corresponding to the protrusions 20 are bent along the shape of the protrusions 20 in close contact with the upper and lower surfaces of the positive electrode tab 14 and the negative electrode tab 15 as shown in FIG. is doing.
[0035]
As shown in FIGS. 1 and 3, the joint portion 16 covers both the front and back surfaces of the positive electrode tab 14 and the negative electrode tab 15, and sealability between the positive electrode tab 14 and the negative electrode tab 15 and the joint portion 16 is covered. A resin sheet 19 is provided for ensuring the above.
[0036]
The resin sheet 19 is formed in a band shape with a resin material such as PE (polyethylene) or PP (polypropylene), and the resin sheet 19 is wound around the positive electrode tab 14 and the negative electrode tab 15 in advance before the joining portion 16 is thermally welded. Keep it.
[0037]
Then, after the resin sheet 19 is wound, the bonding portion 16 is heat-welded, so that the adhesion between the laminate films 12 and 13 and the peripheral portions of the positive electrode tab 14 and the negative electrode tab 15 can be secured. In the present embodiment, the resin sheet 19 is disposed on the battery outer side (bus bar 17, 18 side) than the convex portion 20.
[0038]
As shown in FIGS. 3 and 5, the convex portion 20 has a regulation surface 30 that abuts the tips of the electrode leads 11 </ b> D and 11 </ b> E by raising the battery inner side base F upward at a substantially right angle. It is as.
[0039]
In the electrode tab lead-out structure of the laminated battery 10 of this embodiment described above, when the laminated battery 10 is mounted on an electric vehicle or a hybrid car and the vehicle body vibrates, the vibration is transmitted from the bus bars 17 and 18 to the positive electrode tab 14. And transmitted to the negative electrode tab 15.
[0040]
At this time, since the positive electrode tab 14 and the negative electrode tab 15 are formed with convex portions 20 between the connection portions P1 and P2 of the bus bars 17 and 18 and the connection portions Q1 and Q2 of the electrode leads 11D and 11E, The vibration can be effectively absorbed by the convex portion 20.
[0041]
For this reason, it is possible to prevent or effectively suppress vibrations from the positive electrode tab 14 and the negative electrode tab 15 from being input to the electrode leads 11D and 11E formed of a material having a low strength such as a metal foil. Mechanical damage inside the battery such as breakage of the leads 11D and 11E can be prevented. Thereby, the fall of battery performance can be prevented and an original voltage can be maintained.
[0042]
By the way, in this embodiment, the convex part 20 as a vibration absorption part is located inside the junction part 16 which heat-welded the peripheral part of the laminate films 12 and 13, and the positive electrode tab 14 and negative electrode with the laminate films 12 and 13 The tab 15 protrudes upward. In this case, as shown in FIG. 6, the space between the convex portion 20 and the lower laminate film 13 can be used as a gas reservoir S that retains the gas generated in the laminated battery 10.
[0043]
That is, the electrolytic solution sealed together with the laminated electrode 11 in the laminate films 12 and 13 generates gas when it is decomposed, and generates a gas due to a chemical change caused by moisture entering the inside. Since the gas generated in this way has a sealed structure between the laminate films 12 and 13, there is no escape.
[0044]
For this reason, it is necessary to provide an extra space for accommodating the generated gas in the storage space for the laminated electrode 11 and the electrolytic solution, and to seal the laminate films 12 and 13 under reduced pressure conditions. However, in this case, by providing an excess space, wrinkles are easily generated in the laminated films 12 and 13 during sealing, and the sealing performance is impaired by the wrinkles, or the aluminum foil layer γ of the laminated films 12 and 13 (see FIG. 4). May break down.
[0045]
On the other hand, in this embodiment, when gas is generated inside the battery, the lower laminate film 13 that is in close contact with the positive electrode tab 14 and the negative electrode tab 15 is peeled off by this gas pressure, and the gas is supplied to each tab 14 in the convex portion 20. , 15 and the laminate film 13, and the gas reservoir S shown in FIG. 6 is formed.
[0046]
Therefore, in the present embodiment, it is not necessary to provide a surplus space for gas storage in the storage space for the laminated electrode 11 and the electrolyte solution between the laminate films 12 and 13, thereby preventing wrinkles of the laminate films 12 and 13. Thus, it is possible to eliminate problems caused by this defect.
[0047]
Further, as shown in FIG. 3, since the resin sheet 19 that secures the sealing performance of the joint portion 16 in the positive electrode tab 14 and the negative electrode tab 15 is disposed outside the battery from the convex portion 20, the resin sheet 19 is an obstacle. Thus, the gas generated inside can be guided to the gas reservoir S, and the volume of the gas reservoir S can be increased, and the long-term reliability of the stacked battery 10 can be maintained. .
[0048]
Further, since the battery inner side base F of the convex portion 20 formed on the positive electrode tab 14 and the negative electrode tab 15 is a regulation surface 30 that abuts the tips of the electrode leads 11D and 11E, the electrode leads 11D and 11E are used as the positive electrode tab. When the electrodes 14 and the negative electrode tab 15 are fixed to the negative electrode tab 15 by welding, the ends of the electrode leads 11D and 11E are simply abutted against the restriction surface 30 to easily position the electrode leads 11D and 11E with respect to the positive electrode tab 14 and the negative electrode tab 15. be able to. Thereby, the battery shape can be made uniform.
[0049]
FIGS. 7 and 8 show other embodiments of the vibration absorbing portion provided in the positive electrode tab 14 and the negative electrode tab 15, respectively, and the same components as those in the above embodiment are denoted by the same reference numerals and redundant description is omitted.
[0050]
That is, the vibration absorbing portion shown in FIG. 7 is configured by continuously forming a convex portion 20a projecting upward provided on the battery inner side and a convex portion 21 projecting downward provided on the outer side. ing. These upper convex portion 20a and lower convex portion 21 can absorb vibration at a plurality of locations, and can enhance the vibration absorbing function.
[0051]
Of course, even in this case, the gas reservoir S for introducing the gas generated inside the battery is formed in the lower portion of the convex portion 20a, and the gas reservoir S is also formed in the upper portion of the convex portion 21. Therefore, the gas retention volume can be increased.
[0052]
On the other hand, the vibration absorbing portion shown in FIG. 8 is configured by continuously forming convex portions 20b and convex portions 20c that protrude upward. Even in this case, vibration absorption can be performed at a plurality of locations, so that the vibration absorption function can be enhanced, and gas reservoir spaces S can be formed in the lower portions of the two convex portions 20b and 20c, respectively. And the gas retention volume can be increased.
[0053]
Moreover, although the convex part 20,20a, 20b, 20c shown to each said embodiment disclosed the case where it formed in the arch shape, the shape should absorb a vibration and the residence of gas is possible. For example, various shapes such as a mountain shape, a polygonal shape such as a rectangle, or an Ω-shape can be adopted. In the present embodiment, when absorbs vibrations, and has formed the convex portion 20 in order to allow the retention of gas, for the purpose only absorption of vibrations, the bus bar connecting portion as a reference example A separate vibration absorbing member such as a spring made of a conductive member (eg, Cu, Ni, Fe, etc.) may be interposed between P1 and P2 and electrode leads 11D, 11E.
[0054]
By the way, although the electrode tab extraction part structure of the multilayer battery according to the present invention has been described by taking the above embodiments as examples, it goes without saying that the present invention is not limited to these embodiments, and various embodiments can be made without departing from the gist of the present invention. Can be adopted. For example, the stacked battery 10 is not limited to a lithium ion secondary battery, and the present invention can be applied to other batteries having the same configuration.
[Brief description of the drawings]
FIG. 1 is a plan view of a battery according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of a principal part taken along line AA in FIG.
FIG. 3 is an enlarged cross-sectional view along the line BB in FIG. 1;
FIG. 4 is an enlarged cross-sectional view of a portion C in FIG.
5 is an enlarged cross-sectional view of a portion D in FIG.
FIG. 6 is an enlarged cross-sectional view of a main part showing the function of a vibration absorbing part provided in the electrode tab in one embodiment of the present invention.
FIG. 7 is a cross-sectional view of a main part showing a modification of a vibration absorbing unit in another embodiment of the present invention.
FIG. 8 is a cross-sectional view of a main part showing another modification of the vibration absorbing unit in another embodiment of the present invention.
[Explanation of symbols]
10 Stacked Battery 11 Stacked Electrode (Power Generation Element)
11A Positive electrode plate 11B Negative electrode plate 11C Separator 11D, 11E Electrode lead 12, 13 Laminate film 14 Positive electrode tab 15 Negative electrode tab 16 Joint part 17, 18 Bus bar (conductor)
19 Resin sheet 20, 20a, 20b, 20c Convex part (vibration absorbing part)
30 Regulating surface F Convex portion inside the battery base S Gas reservoir

Claims (3)

Covering both sides of the power generation element laminated with a separator interposed between the positive electrode plate and the negative electrode plate with a laminate film having a metal layer and a resin layer, and bonding the peripheral edge of the laminate film by heat welding The power generation element is sealed, and a positive electrode tab and a negative electrode tab electrically connected to the positive electrode plate and the negative electrode plate via electrode leads, respectively, are drawn out from the bonded portion of the laminate film, and the positive electrode tab and the negative electrode In the electrode tab lead-out structure of the stacked battery that takes out electricity from the tip of the tab, a vibration absorbing portion is provided between the tip of the positive electrode tab and the negative electrode tab and the connection portion to the electrode lead, and the vibration The absorbent portion is located at the peripheral edge of the laminate film, and the positive electrode tab and the negative electrode tab are disposed together with the laminate film, the positive electrode And the negative electrode plate laminate type battery electrode tabs extraction unit structure characterized by comprising a projecting portion which projects toward at least one of lamination directions. The resin sheet that secures sealing properties between the joint portion and the positive electrode tab and the negative electrode tab, which is located at the joint portion of the laminate film, is disposed outside the battery from the convex portion. 2. An electrode tab take-out structure of a laminated battery according to 1 . 3. The electrode tab take-out structure of a stacked battery according to claim 1, wherein the convex portion has a base portion on the inner side of the battery as a regulating surface that abuts the tip of the electrode lead.

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