JP2006147300A - Battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery with excellent productivity maintaining a load characteristics by preventing a lowering of contact between a cathode and an anode caused by change of the size of a battery element due to consumption of lithium, maintaining a high discharging capacity even at its terminal stage of discharge in spite of its reduced thickness. <P>SOLUTION: A cathode activator layer 1a is formed only on one face of a cathode current collector 1b, and the cathode current collector is bent in folded screen shape so that the cathode activator layers face each other. An anode is arranged between the cathode activator layers facing each other through a separator. An electrode terminal is connected to the cathode and anode respectively, and the battery element is sealed under reduced pressure after the battery element is wrapped by a laminate film. Further, the activator layer is not applied on the curved part of the cathode current collector, and the activator is prevented from exfoliation and fall-off by arranging an unpainted area within a prescribed width. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flat primary battery excellent in battery characteristics and productivity.

  Currently, coin-type lithium batteries are not only used as power sources for clocks and memory backup of electronic products such as personal computers, copiers, video cameras, and game machines, but also for bending machines, gas meters, smart key systems, tire pressure monitoring. Applications such as systems, in-vehicle navigation systems, and electronic shelf labels are expected to be used as driving power supplies in a wide operating temperature range from high to low temperatures.

  However, in order to satisfy the load characteristics and discharge capacity required by devices using coin-type batteries in recent years, and the shape required for batteries (thinness is thin), a plurality of coin-type batteries are connected in parallel and used. There are many applications. Such a method of use is a sign that the load characteristics and discharge capacity of a coin-type battery with a very small electrode reaction area do not match the needs of the application.

  Usually, in order to arrange a battery in a device, welding or the like is required, which results in a very complicated manufacturing process and imposes very large restrictions on device design. In addition, when the number of batteries connected in parallel increases to three or more, a problem due to the variation in capacity between the batteries occurs. For example, a battery with a smaller discharge capacity than other batteries will continue to discharge even if the discharge ends normally, causing overdischarge, or being charged from another battery, causing gas generation or internal short circuit. It is very dangerous.

  In order to solve such a problem, a rectangular battery is used in which the space inside the battery is effectively used to improve the battery capacity.

Therefore, as shown in Patent Document 1 below, by manufacturing a battery by folding the electrode in a folding screen, a reaction area can be increased, a large current can be passed, and a battery that can be thin is obtained. It has become possible.
JP-A-6-187998

  FIG. 1 is a schematic diagram showing a configuration of a battery according to an embodiment in Patent Document 1. In FIG. In the invention of Patent Document 1, a positive electrode produced by applying a positive electrode active material 1a on an insulating substrate 3 or on a positive electrode current collector 1b provided on the insulating substrate 3, and an insulating property. A protective sheet 4 is provided on each of the negative electrode produced by applying the negative electrode active material 2a on the negative electrode current collector 2b provided on the substrate 3 having insulation or on the substrate 3 having insulation, as shown in FIG. A battery element is produced by folding the battery element, and the battery element is housed in an outer can made of a metal material or a battery case made of a resin material, thereby forming a battery.

  In a battery using metal lithium or a metal lithium alloy for the negative electrode, lithium is consumed as the discharge proceeds, and the negative electrode becomes thin. However, in the case of a coin-type lithium battery or a battery using a metal case as the exterior as in the above-mentioned Patent Document 1, the metal case cannot follow the change in the dimensions of the battery element due to the consumption of lithium. Or the contact of a positive electrode and a positive electrode case worsens. For this reason, the impedance inside a battery rises especially in the last stage of discharge, and the problem that load characteristics will fall extremely arises.

  Accordingly, an object of the present invention is to solve the above problems and to provide a battery that is thin but has load characteristics even at the end of discharge and is excellent in productivity.

  In order to solve the above-mentioned problem, a first aspect of the present invention includes a positive electrode in which an active material layer containing an active material is provided on a current collector made of a strip-shaped metal foil, and metal lithium or a metal lithium alloy. In the battery having the negative electrode and the separator, the positive electrode is a battery in which an active material layer is formed only on one surface of the current collector, and the active material layers are bent so as to face each other.

  A second aspect of the present invention is a positive electrode in which an active material layer containing an active material is provided on a current collector made of a strip-shaped metal foil, a negative electrode made of metal lithium or a metal lithium alloy, a separator, The positive electrode forms an active material layer only on one side of the current collector, is bent so that the active material layers face each other, and the active material layer uncoated portion is provided at the bent portion where the positive electrode is bent It is the battery characterized by the above-mentioned.

  According to this invention, the electrode area can be increased by arranging the electrodes effectively, and the battery having high battery characteristics can be manufactured by reducing the internal resistance of the battery. Moreover, since the active material is simply applied to one surface of the metal foil, the productivity is excellent and the cost for capital investment can be reduced.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 2 shows a configuration of a battery to which the present invention is applied. The battery is made of a laminate film, and the positive electrode terminal 12a and the negative electrode terminal 12b connected to the positive electrode and the negative electrode are led out from the laminated film bonding portion.

  A method for manufacturing a battery to which the present invention is applied will be described below.

[Positive electrode]
The positive electrode is formed by forming a positive electrode active material layer containing a positive electrode active material on one surface of a positive electrode current collector. The positive electrode current collector is made of a metal foil such as an aluminum (Al) foil, a nickel (Ni) foil, or a stainless steel (SUS) foil.

  The positive electrode active material layer includes, for example, a positive electrode active material, a conductive agent, and a binder. These are uniformly mixed to form a positive electrode mixture, and this positive electrode mixture is dispersed in a solvent to form a slurry. At this time, it adjusts so that it may have a predetermined viscosity using a thickener. Then, the slurry is uniformly applied onto the positive electrode current collector, and dried in a vacuum dryer to remove moisture in the positive electrode mixture, thereby producing a positive electrode. Here, the positive electrode active material, the conductive agent, the binder, and the solvent only have to be uniformly dispersed, and the mixing ratio is not limited.

  As the positive electrode active material, manganese dioxide or graphite fluoride can be selected for a 3V battery, and iron sulfide can be selected for a 1.5V battery. Each mass energy density is 308 mAh / g for manganese dioxide, 860 mAh / g for fluorinated graphite, 890 mAh / g for ferric sulfide, and 3860 mAh / g for lithium metal used as a counter electrode.

  As the conductive agent, for example, a carbon material such as carbon black, graphite, or acetylene black is used. As the binder, for example, polyvinylidene fluoride, styrene butadiene rubber (SBR), polyvinylidene fluoride, or the like is used. Moreover, as a solvent, ethanol etc. are used, for example.

  The positive electrode can be applied using a die coating method, a transfer printing method, a screen printing method, or the like. In view of productivity and equipment cost, it is desirable to apply the active material only to one side of the metal foil. In other words, when the active material is applied on both sides, the process of winding the electrode printed on one side after drying and winding the active material again on the back side, drying and winding is necessary to carry out with one machine. Become. Or, apply the active material on one side, apply the active material on the back side immediately after drying, and apply it in a continuous process such as drying and winding. These two are required, and the cost will be very high. For this reason, the cost required for improvement of productivity and capital investment can be significantly reduced by configuring the electrodes by single-sided printing.

  A positive electrode produced by forming a positive electrode active material layer on a positive electrode current collector has a positive electrode terminal connected to the end by spot welding or ultrasonic welding. The positive electrode terminal is preferably a metal foil, but there is no problem even if it is not a metal as long as it is electrochemically and chemically stable and can conduct electricity. Examples of the material for the positive electrode terminal include aluminum.

[Negative electrode]
As the negative electrode, metallic lithium or a metallic lithium alloy is used. Similarly to the positive electrode, the negative electrode is connected to the negative electrode terminal by spot welding or ultrasonic welding. The negative electrode terminal is desirably a metal foil, but there is no problem even if it is not a metal as long as it is electrochemically and chemically stable and can conduct electricity. Examples of the material for the negative electrode terminal include copper (Cu), nickel, stainless steel, stainless steel coated with nickel, and iron (Fe).

[Separator]
The separator is selected from one or more of resin materials whose material is glass fiber, ceramic fiber, polyphenylene sulfide, polyvinylidene fluoride, polytetrafluoroethylene, polybutylene terephthalate, polypropylene, polyethylene or the like. It is selected from microporous films and non-woven fabrics. Among these, when focusing on the viewpoint of improving the low temperature characteristics, a microporous film capable of narrowing the width between the positive and negative electrodes is desirable.

[Electrolyte]
The organic solvent of the electrolytic solution is any one or more of polycarbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, sulfolane, 3 methyl sulfolane, dimethoxyethane, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, and 1,3 dioxolane. You can choose from.

  The electrolyte salt should be selected from any one or more of lithium perchlorate, lithium hexafluorophosphate, lithium trifluoride methanesulfonate, lithium tetrafluoroborate, lithium iodide, etc. Can do.

  A battery element is manufactured using such a material. As shown in FIGS. 3 and 4, the positive electrode 21 is bent three or more times so that the surfaces of the positive electrode active material 21a formed on one surface of the positive electrode current collector 21b face each other, and the positive electrode active material 21a faces each other. A negative electrode 22 made of metallic lithium or a metallic lithium alloy foil is disposed between the surfaces via a separator 23. By directing the surface of the positive electrode active material 21a inward, the lithium negative electrode 22 is not exposed to the outside other than the end surface. Lithium is very active and easy to absorb moisture, so it is handled in low-dew point environments such as dry rooms. However, even in that environment, moisture generated by workers and the like is absorbed and a film such as lithium hydroxide is formed to deteriorate the characteristics of the battery. Therefore, the electrode element is quickly formed by the positive electrode via the separator in the manufacturing process. It is very important for handling the negative electrode to assemble and cover the surface.

[Production of battery]
The battery element produced as described above is covered with an exterior material made of a laminate film having a thickness of about 100 μm to produce a battery. The following materials can be used as the structure of the laminate film used for producing the battery.

  In FIG. 5, an example of the main structures of the laminate film 30 is shown. The metal foil indicated by reference numeral 31 is made of a multilayer film having moisture resistance and insulation sandwiched between an exterior layer 32 made of a resin film and an interior layer 33 made of a resin film (hereinafter appropriately referred to as a sealant layer). . The metal foil 31 plays the most important role of protecting the contents by preventing the ingress of moisture, oxygen and light in addition to improving the strength of the exterior material, and appropriately using stainless steel or nickel-plated iron as a material. However, aluminum (Al) is the most suitable because of its lightness, extensibility, price, and ease of processing. If necessary, an adhesive layer may be provided between the metal foil 31 and the exterior layer 32 and the sealant layer 33.

  Nylon (Ny), polyethylene terephthalate (PET), or polyethylene (PE) is used for the exterior layer 32 because of the beauty of appearance, toughness, flexibility, etc., and a plurality of types can be selected and used. .

  In addition, the sealant layer 33 is a portion that is melted by heat or ultrasonic waves and fused to each other. In addition to polyethylene (PE), unstretched polypropylene (CPP), polyethylene terephthalate (PET), nylon (Ny), low density polyethylene (LDPE), high density polyethylene (HDPE), and linear low density polyethylene (LLDPE) can be used, and a plurality of types can be selected and used.

  The most common configuration of the laminate film is: exterior layer / metal foil / sealant layer = PET / Al / PE. Moreover, not only this combination but the structure of the other general laminate film as shown below is employable. That is, exterior layer / metal film / sealant layer = Ny / Al / CPP, PET / Al / CPP, PET / Al / PET / CPP, PET / Ny / Al / CPP, PET / Ny / Al / Ny / CPP, PET / Ny / Al / Ny / PE, Ny / PE / Al / LLDPE, PET / PE / Al / PET / LDPE, or PET / Ny / Al / LDPE / CPP. In addition, as above-mentioned here, as a metal foil, it cannot be overemphasized that metals other than Al can be employ | adopted.

  As shown in FIG. 6, the battery element 41 is sandwiched between the laminate films 30 as described above, and heat welding is performed leaving one side for injecting the electrolytic solution. An electrolyte was poured into the battery, and the remaining sides were thermally welded under reduced pressure in order to remove air inside the battery as much as possible, and a battery as shown in FIG. 2 was produced.

  Since the battery element 41 is thin and thermal welding is performed under reduced pressure, there is no problem even if the laminate film 30 is used as it is. However, in order to effectively use the internal volume of the battery, the battery element 41 is molded in advance so as to have a recess, and the electrode element It is also possible to keep 41 in this recess.

  Thus, high productivity can be maintained by using a configuration in which the electrode is folded. Further, even when the discharge progresses and the consumption of lithium progresses and the negative electrode becomes thin, the laminate exterior is deformed by the pressure difference between the inside and the outside, and the contact between the positive and negative electrodes can be prevented from being lowered. Thereby, the deterioration of battery characteristics can be eliminated, and a large current can flow until the end of discharge.

  Further, by using the following method, a battery having further excellent productivity and high battery characteristics can be obtained.

  For example, battery capacity can be improved by forming a positive electrode active material thicker than before and manufacturing a battery. However, in such a case, the active material is peeled off or dropped off when the electrode is bent. Therefore, for example, when a thick electrode having a thickness of 100 μm or more is used, a strip-shaped electrode must be laminated.

  However, in the case of stacking strip-shaped electrodes, complicated processes are required to control the handling of the electrodes and the positional accuracy between the electrodes, resulting in poor productivity.

  Therefore, as shown in FIG. 7, the battery is manufactured by providing an uncoated portion 55, 56 or the like to which the active material is not applied at the bent portion to produce the battery, and thus the active surface on the current collector end face due to the displacement of the electrode. It is possible to reduce the occurrence of defects such as short-circuiting due to dropout of substances and displacement of the separator. The uncoated portion 55 is a mountain-folded uncoated portion bent with the active material layer facing outward, and the uncoated portion 56 is a valley-folded uncoated portion bent with the active material layer facing inward. .

  Since the metal foil used as the current collector of the electrode is more convenient for continuous production while maintaining tension during printing, a hard metal foil that hardly stretches is used. For this reason, even when the electrode is bent, the metal foil hardly extends.

  As shown in FIG. 8, when the electrode in which the active material layer 61 is formed on the current collector 60 is mountain-folded, the extension of the portion that contacts the outside of the active material cannot follow the bending of the metal foil. Cracking occurs (FIG. 8C). When the active material springs back from the crack, the metal foil is peeled off or dropped off. Even if there is an uncoated portion, if a sufficient uncoated width is not provided, peeling occurs for the same reason.

  Further, when the electrode is valley-folded, the active material is compressed in the shrinking direction, so that there is little possibility of dropping or peeling. However, in consideration of productivity, it is possible to clarify the bending position of the electrode by providing an uncoated portion in this portion. Accordingly, since the position does not shift even when bent, it is desirable to provide an uncoated portion. At that time, the width of the uncoated portion must be 2T or more when the thickness T of the active material is used. When the electrode is applied with the width less than this width, the metal foil is opposite to the case of mountain folding. Cannot follow the elongation, and the metal foil is cut.

  As shown in FIG. 9, when the electrode is bent, a minimum bending radius r is always formed inside the metal foil. When the thickness of the metal foil is t and the outer radius is R, R = t + r. In addition, the arc BC of the bent metal foil and the arc BC connecting the straight portions of the metal foil are connected with at least a radius r. The angle θ of the arc AB is the same as the angle of the arc BC, and the length connecting the center of the arc BC and the center of the bent portion is t + 2r. At this time, the relationship with the outer radius R of the bent portion is (t + 2r) cos θ = t + r. The length of the arc AB and the length of the arc BC are A = (t + r) θ and B = rθ, respectively.

Next, the length of the portion corresponding to L in FIG. 10 is L ² = (t + 2r) ² − (t + r) ² = 2tr + 3r ² , and the length when the ends of the arc AB and the arc BC are connected by a straight line. Since M is M ² = L ² + r ² , it can be expressed as M ² = 2tr + 4r ² .

When θ is sufficiently small, it can be approximated as M≈A + B, so that M ² = (A + B) ² . Therefore, it can be considered that θ ² = 2r ² / (t + 2r). Therefore, since length A + B = {2 (t + 2r) r} ^1/2 , the width of the uncoated portion necessary for the mountain fold portion is π (t + 2r) + 2 × {2 (t + 2r) r} ^1/2. .

  In FIG. 11, the mode of the bending part which provided the appropriate uncoated part is shown. In this way, by providing an uncoated portion having a width equal to or greater than the above width, the active material is not applied to the bent portion where the positive electrode active material becomes a fold-fold portion, and there is no fear of peeling or dropping of the active material.

  Moreover, the non-application part should just be provided at least in a mountain fold part, and it is not necessary to make it the same width even when it is a case where an unapplication part is provided in both a mountain fold part and a valley fold part.

  Furthermore, as shown in FIG. 12, since the reaction area can be increased by making the width of the positive electrode located on the outermost surface of the battery element larger than the width of the positive electrode located on the inner surface, It is desirable to make it larger than the positive electrode.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

(1) Measurement of battery characteristics [Battery preparation]
80.8% by mass of graphite fluoride as a positive electrode active material and 15.1% by mass of acetylene black as a conductive agent are uniformly mixed, dispersed in ethanol to form a slurry, and then 4.1% of acetylene black as a binder. % Mix. At this time, carboxymethylcellulose dissolved in water as a thickener was mixed and adjusted to a predetermined viscosity (200 Pas) to obtain a positive electrode mixture.

  A positive electrode active material layer 51a was formed by screen printing a positive electrode mixture on the aluminum foil having a thickness of 20 μm as the positive electrode current collector 51b. After the cathode 51 produced in this manner is dried in a vacuum atmosphere, it is bent in a W shape as shown in FIG. 12, a microporous film is disposed as the separator 53, and then the metallic lithium 52 is formed as shown in FIG. A battery element was prepared by arranging in the above. At this time, the positive electrode terminal 54a and the negative electrode terminal 54b are disposed on adjacent surfaces.

  The battery element produced as described above was sandwiched between aluminum laminate films in which the exterior layer was PET, the metal layer was Al, and the sealant layer was PE, and was thermally welded leaving one side.

  Next, an electrolytic solution is poured from the laminate film opening. The electrolytic solution is prepared by dissolving 1 mol / l of lithium tetrafluoroborate in γ-butyrolactone. After injecting the electrolyte, the opening was sealed in a vacuum degassed atmosphere to produce a battery. The produced battery is as follows.

<Example 1>
A battery having a width of 28 mm, a length of 49 mm, and a thickness of 1.8 mm and a capacity of 600 mAh was produced.

<Example 2>
A battery having a width of 15 mm, a length of 60 mm, and a thickness of 2.1 mm and a capacity of 400 mAh was produced.

  As a comparative example, a conventional coin type battery was used. The battery used as a comparative example is as follows.

<Comparative Example 1>
A coin-type battery CR2450 having a capacity of 600 mAh using manganese dioxide for the positive electrode and lithium for the negative electrode was used.

<Comparative example 2>
A coin-type battery BR2450 having a capacity of 550 mAh using graphite fluoride as the positive electrode and lithium as the negative electrode was used.

<Comparative Example 3>
A coin-type battery CR1620 having a capacity of 75 mAh using manganese dioxide for the positive electrode and lithium for the negative electrode was used.

  The specifications of the batteries of Examples 1 and 2 and Comparative Examples 1, 2, and 3 are shown in Table 1 below.

  As can be seen from Table 1, the battery manufactured according to the present invention has a very thin battery thickness compared to the coin-type battery, and the reaction area of the positive electrode can be increased by 15 times or more. Further, since the internal resistance is very small, it is possible to prevent the load characteristics from being deteriorated.

  Each battery described above is measured for a closed circuit voltage (CCV) during a 10 mA discharge in an environment of −40 ° C. Measurement is performed for each depth of discharge (DOD), and is measured 0.1 seconds after the start of discharge.

  FIG. 13 shows CCV measurement results. A graph 71 indicated by a solid line is a characteristic of Example 1, a graph 72 indicated by a broken line is a characteristic of Comparative Example 1, and a graph 73 indicated by a dotted line is a characteristic of Comparative Example 2. A battery manufactured by applying the present invention can be effectively used up to deep discharge even in a severe environment of −40 ° C., and CCV at 0% DOD is 200 to 600 mV compared to a conventional coin type battery. You can see that the

(2) Measurement of active material peeling / dropping [Battery preparation]
The battery material and manufacturing method used in this measurement are the same as those in the above-described measurement (1). However, in the measurement of peeling / dropping off of the active material, an active material non-coated portion was provided on the positive electrode by screen printing as follows.

<Example 3>
A positive electrode active material having a thickness of 0.30 mm was formed on an aluminum foil having a thickness of 20 μm. The width of the uncoated part was 0.15 mm.

<Example 4>
A positive electrode active material having a thickness of 0.30 mm was formed on an aluminum foil having a thickness of 20 μm. The width of the uncoated part was 0.90 mm.

<Example 5>
A positive electrode active material having a thickness of 0.30 mm was formed on an aluminum foil having a thickness of 20 μm. The width of the uncoated part was 1.20 mm.

<Example 6>
A positive electrode active material having a thickness of 0.50 mm was formed on an aluminum foil having a thickness of 20 μm. The width of the uncoated part was 1.20 mm.

<Comparative example 4>
A positive electrode active material having a thickness of 0.30 mm was formed on an aluminum foil having a thickness of 20 μm. The width of the uncoated part was not provided.

<Comparative Example 5>
A positive electrode active material having a thickness of 0.30 mm was formed on an aluminum foil having a thickness of 20 μm. The width of the uncoated part was 0.10 mm.

<Comparative Example 6>
A positive electrode active material having a thickness of 0.30 mm was formed on an aluminum foil having a thickness of 20 μm. The width of the uncoated part was 0.40 mm.

<Comparative Example 7>
A positive electrode active material having a thickness of 0.30 mm was formed on an aluminum foil having a thickness of 20 μm. The width of the uncoated part was 0.40 mm.

  First, using Examples 3 to 6 and Comparative Examples 4 and 5, the state of peeling / dropping when the electrode was folded in a mountain (bent so that the active material coating surface was on the outside) was measured. Table 2 below shows the measurement results. In each example and comparative example, 10 batteries are made and the number of peeled / dropped parts is measured.

  From the above results, it is possible to prevent the active material from peeling and dropping by providing an uncoated portion having a predetermined width in the mountain fold portion.

  Next, using Examples 4 to 6 and Comparative Examples 4 to 7, the state of peeling / dropping when the electrode was valley-folded (bent so that the coated surface of the active material was inside) was measured. Table 3 below shows the measurement results. In each example and comparative example, 10 batteries are made and the number of peeled / dropped parts is measured.

  From the above results, it is possible to prevent the active material from peeling and dropping by providing the uncoated portion with a width larger than twice the thickness of the active material layer applied to the valley fold.

  Thus, a battery having excellent characteristics can be produced by packaging a battery element in which electrodes are bent and laminated with a laminate film. Moreover, since it is set as the structure which apply | coats an active material only to an electrical power collector single side | surface, productivity improves. In addition, by increasing the thickness of the positive electrode active material layer and providing an appropriate active material uncoated portion, it is possible to obtain a battery with higher productivity and better performance.

  The embodiment of the present invention has been specifically described above, but the present invention is not limited to the above-described embodiment, and various modifications based on the technical idea of the present invention are possible.

  For example, the numerical values given in the above-described embodiment are merely examples, and different numerical values may be used as necessary.

  Moreover, as shown in FIG. 14, it is good also as a structure which affixes the edge parts of the laminated | stacked electrode with the tape 81, and prevents the negative electrode from jumping out.

It is sectional drawing explaining the battery structure of patent document 1. FIG. It is a schematic diagram which shows the external appearance of the battery produced by applying this invention. It is sectional drawing at the time of producing a battery element by bending an electrode. It is a schematic diagram which shows a mode when an electrode is bent. It is sectional drawing which shows the structure of the laminate film used as an exterior when producing a battery by applying this invention. It is a schematic diagram which shows a mode at the time of covering a battery element with a laminate film. It is sectional drawing at the time of providing an active material non-application part in a bending part, and producing a battery element. It is a schematic diagram which shows a mode that a crack generate | occur | produces in an active material layer when a collector is bent in a mountain fold. It is a schematic diagram which shows the mode of the bending part at the time of making a collector bent in a mountain fold. It is a schematic diagram which shows a part of bending part at the time of making a collector bent in a mountain fold. It is a schematic diagram which shows the mode of the mountain fold bending part at the time of providing the appropriate non-application part. It is sectional drawing which shows a mode when the positive electrode width of an outermost surface is taken wider than the positive electrode width of an inner surface. It is a basic diagram which shows the result of having measured the closed circuit voltage during 10 mA discharge according to the discharge depth in -40 degreeC environment. It is a schematic diagram which shows the battery structure in the case of sticking the edge parts of the laminated | stacked electrodes with a tape, and preventing the negative electrode from jumping out.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Positive electrode 1a ... Positive electrode active material 1b ... Positive electrode collector 2 ... Negative electrode 2a ... Negative electrode active material 2b ... Negative electrode collector 3 ... Insulating base | substrate 4 .... Protective sheet 11 ... Battery 12a ... Positive electrode terminal 12b ... Negative electrode terminal 21 ... Positive electrode 21a ... Positive electrode active material 21b ... Positive electrode current collector 22 ... Negative electrode 23 ... Separator 24a ... Positive electrode terminal 24b ... Negative electrode terminal 30 ... Laminate film 31 ... Metal foil 32 ... Exterior layer 33 ... Sealant layer 41 ... Battery element 51 ... Positive electrode 51a ... -Positive electrode active material layer 51b ... Positive electrode current collector 52 ... Negative electrode 53 ... Separator 54a ... Positive electrode terminal 54b ... Negative electrode terminal 55 ... Uncoated part 56 ... Uncoated part 60 ... Current collector 61 ... Active material layer 81 ... Ta The

Claims (9)

In a battery having a positive electrode provided with an active material layer containing an active material on a current collector made of a strip-shaped metal foil, a negative electrode made of metal lithium or a metal lithium alloy, and a separator,
The positive electrode has an active material layer formed only on one side of a current collector, and the active material layer is bent so as to face each other.   The outer and inner surfaces of the metal layer are covered with a laminate film sandwiched between resin layers, the electrode terminals electrically connected to the positive electrode and the negative electrode are led out from the openings of the laminate film, and the openings are heat-sealed. The battery according to claim 1, wherein the battery is sealed.   The battery according to claim 1, wherein the active material is selected from the group consisting of manganese dioxide, graphite fluoride, and iron sulfide. In a battery having a positive electrode provided with an active material layer containing an active material on a current collector made of a strip-shaped metal foil, a negative electrode made of metal lithium or a metal lithium alloy, and a separator,
The positive electrode forms an active material layer only on one side of the current collector, is bent so that the active material layers face each other, and an active material layer uncoated portion is provided at the bent portion where the positive electrode is bent A battery characterized by that.   The battery according to claim 4, wherein a thickness of the active material layer formed on the positive electrode current collector is 100 μm or more and 500 μm or less.   The battery according to claim 4, wherein the active material layer uncoated portion is provided at least in a mountain fold portion.   The width of the uncoated portion provided in the mountain fold portion is π (t + 2r) + 2 × {2 (t + 2r) r} or more, where t is the thickness of the metal foil and r is the bending radius formed inside the metal foil. The battery according to claim 4, wherein the battery is provided.   The battery according to claim 4, wherein an uncoated width of the mountain fold portion and an uncoated width of the valley fold portion are different.   The battery according to claim 4, wherein the outermost positive electrode is wider than the positive electrode disposed on the inner surface.

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