JP2009081066A - Manufacturing method of battery and electrode with tab - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a battery capable of improving output performance and an electrode with a tab. <P>SOLUTION: The battery includes a metal can 1; electrodes 2 contained in the metal can 1, and laminated with a positive electrode 5 and a negative electrode 6 via a separator 7; a nonaqueous electrolyte impregnated in the electrodes 2; a lid 4 disposed on the opening part of the metal can 1, and provided with a positive terminal 14 and a negative terminal 15; a positive electrode tab 8 extended from the positive electrode 5, and electrically connected to the positive electrode terminal 14; and a negative electrode tab 9 extended from the negative electrode 6, and electrically connected to the negative electrode terminal 15, wherein in the positive electrode 5, one side 10 of two sides parallel to the direction L in which the positive electrode tab is extended is shorter than another side 11, wherein in the negative electrode 6, one side 12 of two sides parallel to the direction L in which the negative electrode tab is extended is shorter than another side 13, and wherein the short side 10 of the positive electrode and the short side 12 of the negative electrode are positioned on the same side face of the electrodes 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a battery and a method of manufacturing a tabbed electrode used in the battery.

  In recent years, due to rapid technological development in the electronics field, electronic devices are becoming smaller and lighter. As a result, electronic devices have become more portable and cordless, and a secondary power source serving as a driving source is also desired to be small, light, and have high power density. In response to such demands, lithium secondary batteries with high output density have been developed.

  In the technique disclosed in Patent Document 1, the uncoated portion of the positive electrode is placed outside the negative electrode and the separator on one end face of the winding electrode body for the purpose of lowering the internal resistance in order to increase the output of the battery. And projecting the uncoated part of the negative electrode to the outside of the positive electrode and the separator on the other end face, and further welding the projecting part of the uncoated part together with the conductive tab, This is a method of reducing the resistance value of the conductive foil by arranging the conductive tabs at a rate of 1 to 2 per round.

  However, this method still has two problems. One point is that when the electrode is densified by pressing to reduce the contact electrical resistance between the conductive substrate and the electrode active material by reducing the gap in the electrode, the electrode is deformed like a gutter, Since it is easy to bend, it is a point with a large position gap of a positive electrode and a negative electrode at the time of winding for producing an electrode body. This is because the conductive substrate coated with the active material slurry is stretched during the press treatment, whereas the uncoated portion is thin and thus is not stretched without pressing force. This is because the substrate is stressed. The other point is that the uncoated portion protruding from both end faces of the electrode body decreases the effective area of the positive electrode and the negative electrode, thereby reducing the capacity energy density.

  In order to improve the first problem, for example, there is a method of reducing stress on the unit length of the electrode by cutting out an uncoated portion. However, when it is cut out at random, the portion is arranged at the curvature portion of the flat electrode body, and the uncoated portion is cut or bent, and is easily brought into contact with the counter electrode to cause an internal short circuit accident.

  To improve the second problem, if you try to align the cutouts at the same position from the inner circumference to the outer circumference at all times, the pitch between the cutouts changes from the inner circumference to the outer circumference. It becomes complicated.

  Although there is a problem in taking out a large number of tabs in this way, if the battery structure has a laminated structure in which several, tens, or hundreds of electrodes are stacked, the volume capacity density, Reduction of impedance such as the number of tabs and the width of the tabs is also very easy.

  By the way, in patent document 2, the shape of a positive electrode and a negative electrode is a polygon, and has an electrode active material content layer non-formation area | region in the corner | angular part of the polygon, and the said electrode active material of each electrode The inclusion layer non-formation region is at a different corner, and each electrode portion facing this has a cutout portion with a cutout corner, thereby eliminating the convex portion for connecting the extraction electrode, and the electrochemical device It is described that the proportion of the active material-containing layer in the entire volume is increased.

On the other hand, in Patent Document 3, in the thin battery and the assembled battery, in order to reduce the bottom area (projected area) in plan view while reducing waste of resources, the side 11 on the positive electrode terminal plate 7 side of the electrode plate 4 and The length ratio with the side 12 on the negative electrode terminal plate 8 side is set according to the ratio between the resistivity of the positive electrode terminal plate 7 and the resistivity of the negative electrode terminal plate 8, and the electrode plate 4 and the side 12 are And forming a trapezoidal shape with side 11 as the bottom.
JP-A-2005-93242 JP 2003-68278 A JP 2006-127882 A

  An object of this invention is to provide the manufacturing method of the battery and the electrode with a tab which can improve output performance.

The battery according to the present invention includes a metal can,
An electrode group housed in the metal can, the positive electrode and the negative electrode being laminated via a separator;
A non-aqueous electrolyte impregnated in the electrode group;
A lid that is disposed in the opening of the metal can and includes a positive electrode terminal and a negative electrode terminal;
A positive electrode tab extending from the positive electrode and electrically connected to the positive electrode terminal;
A battery including a negative electrode tab extending from the negative electrode and electrically connected to the negative electrode terminal;
The positive electrode has two sides parallel to the direction in which the positive electrode tab extends, and one side is shorter than the other side, and the negative electrode has two parallel to the direction in which the negative electrode tab extends. One side is shorter than the other side, and the short side of the positive electrode and the short side of the negative electrode are located on the same side surface of the electrode group.

The manufacturing method of the tabbed electrode according to the present invention includes a current collector having parallel first and second sides having different lengths, an electrode layer formed on the current collector, and the current collector. A method of manufacturing a tabbed electrode comprising a tab extended from the current collector so as to be parallel to the first side and the second side of a body,
An electrode base body, which is a strip-shaped current collector in which an electrode layer is formed except for at least one long side end, and at least a part of the tab includes the long side end and the long side direction and the second side And cutting along the contour line of the tabbed electrode excluding the first side so that and are vertical,
The step is repeatedly performed by using the second side cut by the step as the first side newly cut by the step.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the battery and the electrode with a tab which can improve output performance can be provided.

(First embodiment)
The battery according to the first embodiment will be described with reference to the drawings. FIG. 1 is a schematic assembly diagram of a battery according to the first embodiment. FIG. 2 is a schematic diagram for explaining a mechanism in which a nonaqueous electrolyte is impregnated in an electrode group in the battery shown in FIG. FIG. 4 is a schematic cross-sectional view showing an electrode group used in the battery shown in FIG. 1, and FIG. 4 is a perspective view of the battery shown in FIG. 1 when viewed from the front.

  As shown in FIG. 1, for example, a battery such as a nonaqueous electrolyte battery includes a bottomed rectangular cylindrical metal can 1, an electrode group 2, a nonaqueous electrolyte (not shown) impregnated in the electrode group 2, an electrode An anti-winding tape 3 surrounding the periphery of the group 2 and a lid 4 disposed at the opening of the metal can 1 are provided.

  The electrode group 2 is accommodated in the metal can 1. As shown in FIGS. 2 and 3, the electrode group 2 includes a positive electrode 5, a negative electrode 6, and a separator 7 disposed between the positive electrode 5 and the negative electrode 6. The positive electrode 5 includes a positive electrode current collector 5a having a trapezoidal shape (for example, an isosceles trapezoid) and a positive electrode layer 5b formed on both surfaces of the positive electrode current collector 5a. A part of the inclined side of the positive electrode current collector 5 a extends in a band shape, and this functions as the positive electrode tab 8. On the other hand, the negative electrode 6 includes a trapezoidal (for example, isosceles trapezoidal) negative electrode current collector 6a and negative electrode layers 6b formed on both surfaces of the negative electrode current collector 6a. A part of the inclined side of the negative electrode current collector 6 a extends in a band shape, and this functions as the negative electrode tab 9. In two sides of the positive electrode 5 parallel to the extending direction L of the positive electrode tab 8, one side 10 is shorter than the other side 11. Also, one side 12 of the two sides of the negative electrode 6 parallel to the extending direction L of the negative electrode tab 9 is shorter than the other side 13. The electrode group 2 is produced using such a positive electrode 5 and a negative electrode 6 and a strip-shaped separator 7. As shown in FIG. 3, the strip-shaped separator 7 is folded in ninety-nine. The positive electrode 5, the negative electrode 6, the positive electrode 5, the negative electrode 6, and the positive electrode 5 are inserted in order from the top into the portion where the separators 7 are folded. In the laminate obtained by this insertion, the short side 10 of the positive electrode 5 and the short side 12 of the negative electrode 6 are located on the same side surface. Further, the positive electrode tab 8 and the negative electrode tab 9 extend from one end surface perpendicular to the side surface.

  As shown in FIGS. 1 and 4, an anti-winding tape 3 is disposed around the electrode group 2. The lid 4 is made of a rectangular metal plate, and a positive electrode terminal 14 and a negative electrode terminal 15 made of rectangular protrusions are formed on the upper surface thereof. On the lower surface of the lid 4, a positive electrode lead 16 and a negative electrode lead 17 are formed in a state of being electrically connected to the positive electrode terminal 14 and the negative electrode terminal 15, respectively. The positive electrode lead 16 and the negative electrode lead 17 protrude downward from the lower surface of the lid 4. The liquid injection port 18 is provided in the lid 4 portion located between the positive electrode terminal 14 and the negative electrode terminal 15.

  The lid 4 is fixed to the opening of the metal can 1 by welding. As shown in FIG. 1 described above, a plurality of positive electrode tabs 8 and a plurality of negative electrode tabs 9 extend from the upper end face of the electrode group 2. The plurality of positive electrode tabs 8 are welded to the positive electrode lead 16 while being bundled together by welding or the like. The negative electrode tab 9 is also welded to the negative electrode lead 17 in a bundled state by welding or the like.

  According to the battery having such a structure, it is possible to quickly impregnate the electrode group 2 with the liquid nonaqueous electrolyte injected from the liquid injection port 18 of the lid 4, so that the output performance can be improved. That is, the short side 10 of the two sides parallel to the extending direction L of the positive electrode tab 8 in the positive electrode 5 and the short side 12 of the two sides parallel to the extending direction L of the negative electrode tab 9 in the negative electrode 6 are Since the electrode group 2 is located on the same side surface, the end portions of the positive electrode 5 and the negative electrode 6 are inclined with respect to the end portion of the separator 7 on the upper and lower end surfaces of the electrode group 2 as shown in FIG. In other words, the number of free separators 7 that are not sandwiched between the positive electrode 5 and the negative electrode 6 increases. Therefore, the liquid nonaqueous electrolyte injected from the liquid injection port 18 is introduced into the electrode group 2 through the separator 7 portion as shown by the arrow in FIG. In spite of the fact that a plurality of the positive electrode tabs 8 and the negative electrode tabs 9 in which the nonaqueous electrolyte hardly permeates, the nonaqueous electrolyte can be rapidly introduced into the electrode group 2. In addition, the nonaqueous electrolyte introduced into the electrode group 2 quickly penetrates into the positive electrode 5 and the negative electrode 6 from the short side 8 of the positive electrode 5 and the short side 10 of the negative electrode 6. Therefore, since the electrode group 2 can be sufficiently impregnated with the non-aqueous electrolyte, the resistance can be lowered and a non-aqueous electrolyte battery with a high output density can be realized.

In the positive electrode 5, the ratio of the length of the short side 10 to the long side 11 is desirably 90% or more and 99% or less when the length of the long side 11 is 100%. In the negative electrode 6, the length ratio of the short side 12 to the long side 13 is such that the length of the short side 12 is 90% or more and 99% or less when the length of the long side 13 is 100%. Is preferred. By setting this range, a high output can be obtained. At this time, the difference in length between the short side 10 and the long side 11 in the positive electrode 5 (2L ₁ ) and the difference in length between the short side 12 and the long side 13 in the negative electrode 6 (2L ₂ ) are 1.5 mm or more, respectively. , 15 mm or less is preferable. Thereby, output performance can be further improved. A more preferable range is 2 mm or more and 4 mm or less.

  Hereinafter, the positive electrode, the negative electrode, the separator, the nonaqueous electrolyte, and the metal can will be described.

1) Positive electrode The positive electrode includes a positive electrode current collector and a positive electrode layer that is supported on one or both surfaces of the positive electrode current collector and includes an active material and a binder.

Examples of the positive electrode active material include various oxides and sulfides. For example, manganese dioxide (MnO ₂ ), iron oxide, copper oxide, nickel oxide, lithium manganese composite oxide (eg, Li _x Mn ₂ O ₄ or Li _x MnO ₂ ), lithium nickel composite oxide (eg, Li _x NiO ₂ ) , lithium-cobalt composite oxide (Li _x CoO _2), lithium nickel cobalt composite oxide (e.g., _{LiNi 1-y Co y O 2} ), lithium manganese cobalt composite oxides (e.g. _{LiMn y Co 1-y O 2} ), spinel type lithium-manganese-nickel composite oxide _{(Li x Mn 2-y Ni} y O 4), lithium phosphates having an olivine structure _{(Li x FePO 4, Li x} Fe 1-y Mn y PO 4, Li x CoPO 4 etc. ), iron sulfate (Fe ₂ (SO _{4) 3),} vanadium oxide (e.g. V ₂ O _5), and the like. X and y are preferably in the range of 0 to 1. In addition, conductive polymer materials such as polyaniline and polypyrrole, disulfide-based polymer materials, organic materials such as sulfur (S) and carbon fluoride, and inorganic materials are also included. More preferable positive electrode active materials for secondary batteries include lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt composite oxide, lithium nickel cobalt composite oxide, spinel type lithium manganese nickel composite oxide, lithium manganese cobalt. Examples include composite oxides and lithium iron phosphate. This is because a high battery voltage can be obtained with these active materials.

  The positive electrode layer can contain a conductive material. Examples of the conductive material include acetylene black, carbon black, and graphite. In addition, when the active material itself has high conductivity, a conductive material may be unnecessary.

  Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluorine-based rubber.

  Examples of the positive electrode current collector include aluminum or an aluminum alloy.

  The compounding ratio of the positive electrode active material, the conductive material, and the binder is preferably in the range of 80 to 95% by weight of the positive electrode active material, 3 to 18% by weight of the conductive material, and 2 to 17% by weight of the binder.

2) Negative electrode The negative electrode includes a negative electrode current collector and a negative electrode layer that is supported on one or both surfaces of the negative electrode current collector and includes an active material and a binder.

Examples of the negative electrode active material that can be used include iron sulfide, iron oxide, titanium oxide, lithium titanate, nickel oxide, cobalt oxide, tungsten oxide, molybdenum oxide, titanium sulfide, and carbonaceous material. In particular, lithium titanate has poor wettability with nonaqueous electrolytes compared to carbonaceous materials, so by applying the present invention, the excellent cycle performance of lithium titanate can be demonstrated, and output performance Can be expected to improve significantly. Among these, lithium titanate represented by the chemical formula Li _{4 + x} Ti ₅ O ₁₂ (0 ≦ x ≦ 3) and having a spinel structure is preferable.

The lithium titanate preferably has a surface area of 1 to 10 m ² / g. By setting it to 1 m ² / g or more, the effective area contributing to the electrode reaction can be increased to improve the high-current discharge performance. Moreover, since the reaction amount with electrolyte solution can be suppressed by setting it as 10 m < ² > / g or less, improvement of charging / discharging efficiency and suppression of the gas generation at the time of storage are attained.

  The negative electrode layer may contain a conductive material as necessary. A carbonaceous material is used as the conductive material. In addition, when the active material itself has high conductivity, a conductive material may be unnecessary.

  Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluorine-based rubber.

  The negative electrode current collector can be formed from, for example, aluminum, copper, nickel, an aluminum alloy, a copper alloy, a nickel alloy, or the like.

  The compounding ratio of the negative electrode active material, the conductive material and the binder is preferably in the range of 70 to 96% by weight of the negative electrode active material, 2 to 28% by weight of the conductive material, and 2 to 28% by weight of the binder. By making the amount of the conductive material 2% by weight or more, it is possible to secure current collecting and improve the large current performance. However, when the negative electrode active material has very high conductivity, a conductive material may be unnecessary. In that case, the blending ratio is preferably 2 to 29% by weight of the binder. By setting the amount of the binder to 2% by weight or more, the binding performance between the mixture layer and the current collector can be improved and the cycle performance can be improved. On the other hand, from the viewpoint of increasing the capacity, the amount of the conductive material and the binder is preferably 28% by weight or less.

  The negative electrode is produced by suspending a negative electrode active material, a conductive material, and a binder in a suitable solvent, and applying the suspension to a current collector such as an aluminum foil, drying, and pressing.

3) Separator A porous separator can be used as the separator. Examples of the porous separator include a porous film containing polyethylene, polypropylene, cellulose, or polyvinylidene fluoride (PVdF), and a synthetic resin nonwoven fabric. Among these, a porous film made of polyethylene, polypropylene, or both is preferable because it can improve the safety of the secondary battery.

4) Non-aqueous electrolyte As the non-aqueous electrolyte, a non-aqueous electrolyte prepared by dissolving an electrolyte in an organic solvent can be used. Also, a room temperature molten salt containing lithium ions can be used as the non-aqueous electrolyte.

Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluoroarsenide (LiAsF ₆ ), and trifluoro lithium methanesulfonic acid (LiCF ₃ SO _3), bis (trifluoromethylsulfonyl) imide lithium _{[LiN (CF 3 SO 2)} 2] include lithium salts such as. The electrolyte is preferably dissolved in the range of 0.5 to 2.0 mol / L with respect to the organic solvent.

  Examples of the organic solvent include cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), and vinylene carbonate (VC), dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), and diethyl carbonate (DEC). Examples include chain carbonates, cyclic ethers such as tetrahydrofuran (THF), 2-methyltetrahydrofuran (2MeTHF), chain ethers such as dimethoxyethane (DME), γ-butyrolactone (BL), acetonitrile (AN), sulfolane (SL), and the like. be able to. These organic solvents can be used alone or in the form of a mixture of two or more.

  The room temperature molten salt refers to a salt that is at least partially in a liquid state at room temperature, and the room temperature refers to a temperature range in which a power supply is assumed to normally operate. The temperature range in which the power supply is assumed to normally operate has an upper limit of about 120 ° C. and in some cases about 60 ° C., and a lower limit of about −40 ° C. and in some cases about −20 ° C.

  The room temperature molten salt is composed of a combination of a lithium salt and an organic cation.

As the lithium salt, a lithium salt having a wide potential window, which is generally used for lithium secondary batteries, is used. For example, LiBF ₄ , LiPF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ), LiN (CF ₃ SC (C ₂ F ₅ SO ₂ ) _3, etc. However, these are not limited, and these may be used alone or in combination of two or more.

  The lithium salt content is preferably 0.1 to 3.0 mol / L, and particularly preferably 1.0 to 2.0 mol / L. When the lithium salt content is 0.1 mol / L or more, the resistance of the electrolyte is reduced, and the large current / low temperature discharge performance is improved. By setting the content to 3.0 mol / L or less, the melting point of the electrolyte is lowered. Thus, it becomes possible to maintain a liquid state at room temperature.

The room temperature molten salt has, for example, a quaternary ammonium organic cation having a skeleton represented by the formula (1) or an imidazolium cation having a skeleton represented by the formula (2).

However, in the formula (2), R1, R2: C n H 2n + 1 (n = 1~6), R3: H or _{C n H 2n + 1 (n} = 1~6)
In addition, the normal temperature molten salt which has these cations may be used independently, or may be used in mixture of 2 or more types.

  Examples of the quaternary ammonium organic cation having a skeleton represented by the formula (1) include imidazolium ions such as dialkylimidazolium and trialkylimidazolium, tetraalkylammonium ions, alkylpyridinium ions, pyrazolium ions, pyrrolidinium ions, And piperidinium ions. In particular, an imidazolium cation having a skeleton represented by the formula (2) is preferable.

  Examples of the tetraalkylammonium ion include, but are not limited to, trimethylethylammonium ion, trimethylethylammonium ion, trimethylpropylammonium ion, trimethylhexylammonium ion, and tetrapentylammonium ion.

  Examples of the alkyl pyridinium ion include N-methyl pyridinium ion, N-ethyl pyridinium ion, N-propyl pyridinium ion, N-butyl pyridinium ion, 1-ethyl-2methyl pyridinium ion, 1-butyl-4-methyl. Examples thereof include, but are not limited to, pyridinium ions and 1-butyl-2,4 dimethylpyridinium ions.

  Examples of the imidazolium cation having a skeleton represented by the formula (2) include dialkylimidazolium ions such as 1,3-dimethylimidazolium ion, 1-ethyl-3-methylimidazolium ion, and 1-methyl-3-ethyl. Examples include imidazolium ion, 1-methyl-3-butylimidazolium ion, 1-butyl-3-methylimidazolium ion, and the like. Trialkylimidazolium ions include 1,2,3-trimethylimidazolium ion, 1 , 2-dimethyl-3-ethylimidazolium ion, 1,2-dimethyl-3-propylimidazolium ion, 1-butyl-2,3-dimethylimidazolium ion, and the like, but are not limited thereto. Absent.

5) Metal can The bottom of the bottom of the metal can made of aluminum, aluminum alloy, iron, stainless steel or the like can be used. The plate thickness of the metal can is preferably 0.5 mm or less, and more preferably 0.2 mm or less.

  In addition, the battery charge / discharge system according to the first embodiment can be used as a power source for a control system that drives a drive motor of an electric vehicle.

(Second Embodiment)
The second embodiment is a method of manufacturing a tabbed electrode used in the battery according to the first embodiment. This method can be applied to the positive electrode, the negative electrode, or both electrodes.

  First, a punching device used in this method will be described with reference to FIG. The punching device 21 includes a punching die 22 and a punching base 23. The punching die 22 has an outline of the electrode with tabs except for a portion corresponding to the first side (short side in the case of FIG. 5) of two parallel sides having different lengths of the electrode (current collector). A blade 24 is provided along. By the unwinding roll 25 and the winding roll 26, the hoop-shaped electrode base 27 with tabs moves along the long side direction and is conveyed onto the punching base 23. The base body 27 includes a strip-shaped current collector and an electrode layer 28 formed by removing at least one long side end portion of the strip-shaped current collector. Of the strip-shaped current collector, the long side end portion where the electrode layer 28 is not formed is referred to as an uncoated portion 29. For example, the base 27 is obtained by suspending a positive electrode active material or a negative electrode active material, a conductive material, and a binder in an appropriate solvent, and suspending the suspension on one long side end on a strip-shaped current collector. It is prepared by removing, applying, drying, and pressing. The portion where the suspension is applied becomes the electrode layer 28. In addition, what was demonstrated in 1st Embodiment can be used for a positive electrode active material, a negative electrode active material, a electrically conductive material, a binder, and a collector.

  The base body 27 is moved along the long side direction by the unwinding roll 25 and the winding roll 26 and conveyed to the punching base 23. As shown in FIG. 6A, the punching die 22 is arranged so that the portion without the blade 24 (the portion corresponding to the first side) is located upstream in the conveying direction, and the base 27 is pressed by the punching die 22. Then, since the mother body 27 is punched along the blade 24, as shown in FIG. 6B, a part of the tab includes the uncoated portion 29, and the long side direction of the mother body and the second side (FIG. 6). In this case, the contour portion excluding the first side is cut so that the long side) is perpendicular to the long side. Since the first side is shared with the short side of the mother body 27, the cutting for one electrode is completed without cutting. The uncoated portion 29 or the portion including the uncoated portion 29 cut into a rectangular shape is the positive electrode tab 8 or the negative electrode tab 9, and the electrode layer 28 formed in a trapezoidal shape is the positive electrode 5 or the negative electrode 6

  Next, when the mother body 27 is moved by one electrode along its long side direction and the mother body 27 is pressed by the punching die 22, the mother body 27 is punched along the blade 24, and therefore, as shown in FIG. Thus, a part of the tab includes the uncoated portion 29, and the contour portion excluding the first side is cut so that the long side direction of the base body 27 and the second side are perpendicular to each other. Since the first side is shared with the second side of the electrode that has already been punched (the long side in the case of FIG. 6), it is possible to cut one electrode without cutting the first side. Is completed.

  Subsequently, when the base body 27 is moved by one electrode along the long side direction and the base body 27 is pressed by the punching die 22, the contour portion excluding the first side is cut. When the mother body 27 is conveyed by the unwinding roll 25 and the take-up roll 26, the mother body 27 may be displaced in the short side direction. As shown in FIGS. 6 (d) and 6 (e), even if the portion to be punched out of the mother body 27 is displaced due to the positional deviation, a part of the second side of the already punched electrode is cut from this. Since the first side of the electrode can be used, the electrode can be cut one by one without generating an uncut portion that causes burrs. As a result, a battery with less self-discharge due to micro short circuit can be provided. Further, since it is not necessary to provide a gap between the electrodes to be cut, the material yield can be improved.

  It is desirable that the difference between the lengths of the first side and the second side of the electrode be 1.5 mm or more and 15 mm or less. If the difference in length is less than 1.5 mm, the rate of occurrence of burrs increases, which may lead to an increase in insulation failure rate or a decrease in output due to a micro short circuit. On the other hand, if the difference in length exceeds 15 mm, the material yield may be reduced. A more preferable range is 2 mm or more and 4 mm or less.

  In FIGS. 5 and 6, the first side on the upstream side in the transport direction is the short side, the second side on the downstream side is the long side, and the long side is cut. It is also possible to cut the long side with the first side as the long side and the downstream second side as the short side.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples as long as the gist of the invention is not exceeded.

Example 1
<Preparation of positive electrode>
First, lithium cobaltate (LiCoO ₂₎ powder 90 wt%, acetylene black 3 wt%, in addition to 3% by weight of graphite and polyvinylidene fluoride (PVdF) 4% by weight of N- methylpyrrolidone (NMP) mixed as a positive active material The slurry was applied to both surfaces of a strip-shaped current collector made of 15 μm aluminum foil except for one end on the long side, dried, and pressed to obtain an electrode density of 3.0 g / cm ³ . A positive electrode matrix was produced. The thickness of the positive electrode matrix was 60 μm.

  Using the punching device shown in FIG. 5 described above, a positive electrode tab having a height of 150 mm and a long side of 150 mm and a positive electrode tab having a length of 20 mm and a width of 10 mm is extended in parallel with the long side. Was cut. The difference between the long side and the short side in the positive electrode and the ratio of the long side to the short side when the length of the long side is 100% are shown in Table 1 below.

<Production of negative electrode>
Li ₄ Ti ₅ O ₁₂ as a negative electrode active material, coke having an average particle size of 1.12 μm and a specific surface area of 82 m ² / g as a conductive material, and polyvinylidene fluoride (PVdF) in a weight ratio of 90: 5: 5 In addition to the N-methylpyrrolidone (NMP) solution, the resulting slurry was applied to both sides of a strip-shaped aluminum foil having a thickness of 15 μm except for one end on the long side, then dried and pressed. Thus, a negative electrode matrix was produced. The thickness of the negative electrode was 100 μm.

  5. Using the punching device shown in FIG. 5 above, a negative electrode tab having a height of 148 mm and a long side of 148 mm and a negative electrode tab having a length of 20 mm and a width of 10 mm extending in parallel with the long side Was cut. The difference between the long side and the short side in the negative electrode and the ratio of the long side to the short side when the length of the long side was 100% were set in the same manner as in the case of the positive electrode.

  50 positive electrodes and 50 negative electrodes were prepared, respectively, and the positive electrode and the negative electrode were alternately stacked with a separator made of a polyethylene porous film having a thickness of 20 μm interposed therebetween, thereby preparing a stacked electrode group. When laminating, the positive electrode tab and the negative electrode tab extend so that the short side of the positive electrode and the short side of the negative electrode are located on the same side surface of the obtained laminate, and the end surface intersects perpendicularly with the side surface. And a negative electrode.

After placing the obtained electrode group in an aluminum metal can and attaching a lid to the opening of the metal can, injecting an electrolyte from the liquid inlet of the lid and performing initial charging, for output measurement Provided. Note that the electrolytic solution was prepared which was dissolved LiBF ₄ in 2M in organic solvent comprising a mixture of an equal volume of γ- butyrolactone and ethylene carbonate as an electrolyte.

(Examples 2 to 10)
The non-aqueous electrolyte battery was prepared in the same manner as described in Example 1 except that the difference between the long side and the short side and the positional relationship between the conveyance direction and the long side and the short side were set as shown in Table 1 below. Manufactured. In Example 4, the long side was arranged on the upstream side in the transport direction, the short side was arranged on the downstream side, and the long side was cut.

(Comparative Example 1)
The positive electrode is formed into a rectangle with a long side of 150 mm and a short side of 150 mm, and the negative electrode is formed into a rectangle with a long side of 145 mm and a short side of 145 mm. Except for the above, a nonaqueous electrolyte battery was manufactured in the same manner as described in Example 1 above.

(Comparative Example 2)
A nonaqueous electrolyte battery was manufactured in the same manner as described in Example 1 except that the positive electrode and negative electrode were formed in the same manner as in Comparative Example 1 and the punching process was performed by the method shown in FIG.

  As shown in FIG. 7A, the shape of the blade 24 provided in the punching die 22 is assumed to follow the outline of the tabbed electrode except for one side parallel to the extending direction of the tab. The punching die 22 was arranged so that the portion without the blade 24 was located upstream in the transport direction.

  When the base body 27 is moved along the long side direction by the unwinding roll 25 and the take-up roll 26, conveyed to the punching base 23, and the base body 27 is pressed by the punching die 22, as shown in FIG. The outline except for the left side was cut. Since the left side is shared with the short side of the base 27, the cutting for one electrode was completed without cutting.

  Next, when the base body 27 is moved by one electrode along the long side direction and the base body 27 is pressed by the punching die 22, the contour portion excluding the left side is cut as shown in FIG. . Since the left side is shared with the right side of the already punched electrode, the cutting for one electrode is completed without cutting the left side.

  Subsequently, when the base body 27 was moved by one electrode along its long side direction, as shown in FIGS. 7D and 7E, the base body 27 was displaced in the short side direction. As a result, the right side of the punched electrode did not coincide with the left side of the electrode to be cut, and an uncut portion remained on the left side of the electrode to be cut. The burr can cause a battery short-circuit accident.

  With respect to the battery obtained as described above, the output, insulation failure rate, and material cost loss rate were measured by the methods described below.

  The output measurement method will be described. The battery was discharged at 20A to 200A at a current of 20A for 10 seconds. The capacity at the start of discharge was 50% of the total capacity. At this time, the voltage at the 10th second was determined by interpolating or extrapolating the current value below the discharge end voltage. In this embodiment, the specified voltage is 1.5 V because lithium titanate is used as the negative electrode active material and lithium cobaltate is used as the positive electrode active material. This value is the maximum discharge current. The product of the maximum discharge current [A] and the discharge end voltage [V] is the maximum discharge output [W], and the results are shown in Table 1 below.

  Further, the insulation test was performed after the electrode group was built in the battery can and before the liquid injection. In the insulation test, a resistance value of 50 kΩ or less when a voltage of 50 V was applied was regarded as insulation failure. The insulation failure rate when the number of tests is 1000 is shown in Table 1 below.

Furthermore, the material loss rate was calculated in order to determine the amount of loss in the electrode material. The amount of material loss caused by providing a margin between the one calculated from the defect rate, the part inevitably lost in the process design {ie, the ratio of the long side to the short side (%)}, and the punched electrodes as in Comparative Example 1. It was calculated by adding together.

  As is apparent from Table 1, one side of the two sides parallel to the direction in which the tab extends is shorter than the other side, and the short sides of the positive electrode and the negative electrode are located on the same side of the electrode group. The batteries of Examples 1 to 10 obtained have higher output than Comparative Examples 1 and 2. Further, the output of the batteries of Examples 1 to 8 in which the ratio of the length of the long side to the short side is 90% or more and 99% or less, the ratio of Example 9 to which the ratio of the length exceeds 99% and the ratio of the length are Higher than Example 10 below 90%. In particular, the output of the batteries of Examples 1 to 4 in which the difference between the lengths of the long side and the short side was 2 mm or more and 4 mm or less was the highest. The reason why the output tends to decrease with the insulation failure rate is that the resistance value does not result in insulation failure, and even a non-defective product has a short circuit and self-discharge occurs.

  On the other hand, in Comparative Examples 1 and 2 using a rectangular positive electrode and negative electrode, the output performance was inferior. The mechanism of the electrolyte impregnation in the batteries of Comparative Examples 1 and 2 is shown in FIG. As shown by the arrows in FIG. 8, the nonaqueous electrolyte injected from the liquid injection port 18 penetrates from the upper end surface of the electrode group 2 or from the lower end surface of the electrode group 2 along the side surface of the electrode group 2. Therefore, the impregnation speed becomes slow. Further, in Comparative Example 1 in which the electrodes were punched one by one, the material cost loss rate was high because the gap between the electrodes was widened.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The schematic assembly drawing of the battery which concerns on 1st Embodiment. The schematic diagram for demonstrating the mechanism in which the nonaqueous electrolyte is impregnated in the electrode group in the battery shown in FIG. FIG. 2 is a schematic cross-sectional view showing an electrode group used in the battery shown in FIG. 1. The perspective view at the time of seeing the battery shown in FIG. 1 from the front. The schematic diagram which shows the punching apparatus used with the manufacturing method of the electrode with a tab which concerns on 2nd Embodiment. Process drawing which shows the manufacturing method of the electrode with a tab which concerns on 2nd Embodiment. Process drawing which shows the manufacturing method of the electrode with a tab of the comparative example 2. FIG. The schematic diagram for demonstrating the mechanism in which the nonaqueous electrolyte is impregnated in an electrode group in the battery of the comparative examples 1 and 2. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Metal can, 2 ... Electrode group, 3 ... Winding tape, 4 ... Cover, 5 ... Positive electrode, 5a ... Positive electrode collector, 5b ... Positive electrode layer, 6 ... Negative electrode, 6a ... Negative electrode collector, 6b ... Negative electrode Layer, 7 ... separator, 8 ... positive electrode tab, 9 ... negative electrode tab, 10 ... short side of positive electrode, 11 ... long side of positive electrode, 12 ... short side of negative electrode, 13 ... long side of negative electrode, 14 ... positive electrode terminal, 15 DESCRIPTION OF SYMBOLS ... Negative electrode terminal, 16 ... Positive electrode lead, 17 ... Negative electrode lead, 18 ... Injection hole, 21 ... Punching device, 22 ... Punching die, 23 ... Punching base, 24 ... Blade, 25 ... Unwinding roll, 26 ... Winding roll 27 ... Electrode matrix with tab, 28 ... Electrode layer, 29 ... Uncoated part, 30 ... Burr.

Claims (6)

Metal cans,
An electrode group housed in the metal can, the positive electrode and the negative electrode being laminated via a separator;
A non-aqueous electrolyte impregnated in the electrode group;
A lid that is disposed in the opening of the metal can and includes a positive electrode terminal and a negative electrode terminal;
A positive electrode tab extending from the positive electrode and electrically connected to the positive electrode terminal;
A battery including a negative electrode tab extending from the negative electrode and electrically connected to the negative electrode terminal;
The positive electrode has two sides parallel to the direction in which the positive electrode tab extends, and one side is shorter than the other side, and the negative electrode has two parallel to the direction in which the negative electrode tab extends. One of the sides is shorter than the other side, and the short side of the positive electrode and the short side of the negative electrode are located on the same side surface of the electrode group.   In each of the positive electrode and the negative electrode, the ratio of the length of the short side to the long side corresponds to the length of the short side of 90% to 99% when the length of the long side is 100%. The battery according to claim 1.   3. The battery according to claim 2, wherein, in each of the positive electrode and the negative electrode, a difference in length between the short side and the long side is 1.5 mm or more and 15 mm or less. A current collector having parallel first and second sides of different lengths; an electrode layer formed on the current collector; and the first side and the second side of the current collector A tabbed electrode manufacturing method comprising a tab extended from the current collector so as to be parallel to a side,
An electrode base body, which is a strip-shaped current collector in which an electrode layer is formed except for at least one long side end, and at least a part of the tab includes the long side end and the long side direction and the second side And cutting along the contour line of the tabbed electrode excluding the first side so that and are vertical,
The method of manufacturing a tabbed electrode, wherein the step is repeated with the second side cut by the step as the first side newly cut by the step.   The method of manufacturing a tabbed electrode according to claim 4, wherein the current collector has the first side shorter than the second side.   The method for producing a tabbed electrode according to claim 4 or 5, wherein a difference in length between the first side and the second side of the current collector is 1.5 mm or more and 15 mm or less. .

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