JP5011732B2 - battery - Google Patents

Description

  The present invention relates to a battery in which a battery element is accommodated in a battery can.

Conventionally, various batteries compatible with so-called dry batteries have been developed and used. As one of them, for example, as shown in Patent Document 1 below, the positive electrode is a sulfide such as iron sulfide (FeS), a transition metal oxide such as manganese dioxide (MnO ₂ ), a large _{number of} (CF _x ) _{n and the} like. Examples include a cylindrical lithium battery using carbon fluoride and a metal lithium foil as a negative electrode. Among these, the AAA lithium iron sulfide battery using iron sulfide (FeS) as the positive electrode has an average discharge voltage that is 0.2 V higher than that of the alkaline battery, and therefore simply lasts 15% in constant output discharge. In addition, since it has a winding structure in which a positive electrode and a negative electrode are stacked and wound in a spiral shape, it has good heavy load discharge characteristics. For example, when used in a digital camera, it can secure more than twice the number of alkaline batteries. be able to.

Japanese Patent No. 3060109

  However, for example, when an iron-based material such as iron sulfide, iron oxide, or iron fluoride is used for the positive electrode, the iron is easily dissolved in the electrolytic solution, and the dissolved iron precipitates in a needle shape inside the battery to cause a short circuit. The problem arises.

  Accordingly, an object of the present invention is to provide a battery in which the short-circuit inside the battery is prevented and the battery characteristics are improved in the wound battery as described above.

In order to solve the above problems, the present invention is to have a positive and negative electrodes containing iron as a positive electrode active material, one of the positive and negative electrodes were wound in such a manner that the outer peripheral side than the other A battery element having a winding structure, and a battery can that houses the battery element,
The battery can is electrically connected to either the positive electrode or the negative electrode by a lead,
The lead is provided around the battery element between the battery element and the battery can, and an insulating member is provided between the lead and the battery element.
In this battery, the lead sticking start end portion does not overlap with either the positive electrode or the negative electrode terminal portion that is not electrically connected to the battery can.

In this invention, it is configured such that the sticking start end portion of the lead electrically connected to the battery can and the terminal portion of one of the positive electrode and the negative electrode not electrically connected to the battery can do not overlap. Therefore , the electrode is pressed by the thickness of the lead, and the occurrence of a short circuit due to the deposit deposited on the lead can be suppressed.

  According to the present invention, in a battery in which a wound battery element is housed in a battery can, a short circuit inside the battery can be prevented, and a battery with improved battery characteristics can be provided.

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

  1 and 2 are schematic views showing a cross-sectional structure of a battery according to one embodiment of the present invention. This battery is a so-called cylindrical type lithium iron sulfide battery (primary battery), and a strip-shaped positive electrode 21 and a negative electrode 22 are wound around a separator 23 through a substantially hollow cylindrical battery can 11. The battery element 20 is included. The battery can 11 is made of, for example, iron plated with nickel, and has one end closed and the other end open. The battery can 11 may be made of other materials as long as it can be electrically connected. Inside the battery can 11, a pair of insulating plates 12 a and 12 b are respectively disposed perpendicular to the winding peripheral surface so as to sandwich the battery element 20.

  A battery lid 13 and a safety valve mechanism 14 and a PTC element 15 provided inside the battery lid 13 are attached to the open end of the battery can 11 by caulking through an insulating sealing gasket 16. . The battery lid 13 is made of, for example, the same material as the battery can 11. The safety valve mechanism 14 is electrically connected to the battery lid 13 via a thermal resistance element (Positive Temperature Coefficient: PTC element) 15, and the internal pressure of the battery becomes a certain level or more due to internal short circuit or external heating. In this case, the disk plate 14a is inverted to disconnect the electrical connection between the battery lid 13 and the battery element 20. When the temperature rises, the PTC element 15 limits the current by increasing the resistance value and prevents abnormal heat generation due to a large current. For example, the PTC element 15 is made of barium titanate semiconductor ceramics. The insulating sealing gasket 16 is made of, for example, an insulating material, and asphalt is applied to the surface.

  The battery element 20 has a winding structure in which a positive electrode 21 and a negative electrode 22 are laminated via a separator 23 and wound in a spiral shape so that the outer peripheral side end of the positive electrode 21 is on the outer peripheral side of the negative electrode 22. A center pin 24 is inserted in the center. A positive electrode lead 30 made of aluminum (Al) or the like is connected to the positive electrode 21 of the battery element 20, and a negative electrode lead 40 is connected to the negative electrode 22. The positive electrode lead 30 is electrically connected to the battery lid 13 by being welded to the safety valve mechanism 14, and the negative electrode lead 40 is electrically connected to the battery can 11. Further, the separator 23 is not provided on the outermost periphery of the battery element 20, and the positive electrode 21 constitutes the outermost periphery of the battery element 20.

  The negative electrode lead 40 is provided between the battery element 20 and the battery can 11 so as to go around the battery element 20. In addition, an insulating member 50 is provided between the battery element 20 configured so that the positive electrode 21 has the outermost periphery and the negative electrode lead 40 in order to prevent the positive electrode 21 and the negative electrode lead 40 from contacting each other. It has been.

  Hereinafter, the configuration of the battery element 20 accommodated in the battery can 11 will be described in detail.

[Positive electrode]
The positive electrode 21 is obtained by forming positive electrode active material layers 21b containing a positive electrode active material on both surfaces of the positive electrode current collector 21a. The positive electrode current collector 21a is made of a metal foil such as an aluminum (Al) foil, a nickel (Ni) foil, a stainless steel (SUS) foil, or a copper (Cu) foil, and copper is more preferable. Since copper has a low contact resistance, safety can be further improved, the current collecting effect can be improved, and the discharge characteristics can be enhanced.

  The positive electrode active material layer 21b includes, for example, a positive electrode active material, a conductive agent, and a binder. The positive electrode active material, the conductive agent, the binder, and the solvent only need to be uniformly dispersed, and the mixing ratio is not limited.

  Examples of the positive electrode active material mainly include iron compounds such as iron oxide, iron sulfide, and iron fluoride, and a small amount of iron or iron compound, for example, manganese (Mn), copper, cobalt (Co), nickel, and the like. The metal or metal compound to be used can be used.

  As the conductive agent, for example, a carbon material such as carbon black or graphite is used. As the binder, for example, polyvinylidene fluoride, polytetrafluoroethylene, polyvinylidene fluoride, or the like is used. Moreover, as a solvent, N-methyl-2-pyrrolidone (NMP) etc. are used, for example.

  The above-described positive electrode active material, binder, and conductive agent are uniformly mixed to form a positive electrode mixture, and this positive electrode mixture is dispersed in a solvent to form a slurry. Next, this slurry is uniformly applied to both surfaces of the positive electrode current collector by a doctor blade method or the like. Furthermore, the positive electrode active material layer is formed by drying at a high temperature and removing the solvent.

  At this time, it is preferable to provide a positive electrode active material uncoated portion at one end portion of one surface of the positive electrode 21. When assembling the battery element 20, by starting winding the other end portion that is not one end portion where the positive electrode active material uncoated portion is formed, and winding the positive electrode active material uncoated portion on the winding outer periphery side, The outer peripheral surface of the battery element outer peripheral side end of the positive electrode 21 is a positive electrode active material uncoated portion. By setting it as such a structure, contact resistance with the side wall of the battery can 11 can be reduced, and safety | security can be improved further.

  The positive electrode 21 has one positive electrode lead 30 connected to a part of the positive electrode current collector by spot welding or ultrasonic welding. The positive electrode lead 30 is preferably a metal foil or a mesh-like one, 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. As a material of the positive electrode lead 30, for example, aluminum, copper or the like can be used.

[Negative electrode]
As the negative electrode 22, a metal lithium foil can be used.

  The negative electrode lead 40 is provided so as to go around the battery element 20 later, and is preferably made of a material that does not form an alloy with lithium, such as iron, nickel, or stainless steel, and copper is particularly preferable. Since the contact resistance between the negative electrode 22 and the negative electrode lead 40 is small, the internal resistance of the battery can be further reduced, and the voltage and load characteristics can be improved. For example, when a crude copper alloy is used, a metal paired with copper is easily alloyed with lithium. Moreover, since copper can obtain high purity pure copper relatively easily, the cost is low. For these reasons, the copper used as the negative electrode lead 40 is preferably pure copper with a Cu content of 99.9% or more.

  Further, an adhesive layer 41 is preferably provided on the side surface of the battery element 20 of the negative electrode lead 40. As described above, the negative electrode lead 40 is provided between the battery element 20 and the battery can 11 so as to go around the battery element 20. For this reason, by providing the adhesive layer 41 on the side surface of the battery element 20 of the negative electrode lead 40, the position of the negative electrode lead 40 can be stabilized, and the negative electrode lead 40 is bent when the battery element 20 is accommodated in the battery can 11. , It can be prevented from cutting.

  The width of the negative electrode lead 40 is preferably shorter than the width of the negative electrode 22 by 2 mm or more. When the negative electrode lead 40 is larger than the width of the negative electrode 22, the burr generated at the cut portion of the negative electrode lead 40 comes into contact with the end portion of the positive electrode 21, and there is a possibility that the capacity is deteriorated due to the occurrence of a minute short. . For this reason, the width of the negative electrode lead 40 is configured to be shorter than the width of the negative electrode 22.

[Separator]
The separator is made of, for example, a porous film made of a polyolefin-based material such as polypropylene (PP) or polyethylene (PE), or a porous film made of an inorganic material such as a ceramic nonwoven fabric. A structure in which a porous film is laminated may be used. Among these, polyethylene and polypropylene porous films are the most effective.

  In general, the thickness of the separator is preferably 5 to 50 μm, more preferably 7 to 30 μm. If the separator is too thick, the amount of the active material filled decreases, the battery capacity decreases, and the ionic conductivity decreases and the current characteristics deteriorate. On the other hand, if the film is too thin, the mechanical strength of the film decreases.

[Electrolyte]
The separator described above is impregnated with an electrolytic solution that is a liquid electrolyte. This electrolytic solution is obtained by dissolving an electrolyte salt in a non-aqueous solvent, and generally used materials can be used.

  Examples of the non-aqueous solvent include propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, tetrahydrofuran, 2-dimethoxyethane, 1,3-dioxolane, 4-methyl-1,3-dioxolane. , Diethyl ether, sulfolane, methyl sulfolane, acetonitrile or propionitrile, anisole, acetic acid ester, entangled acid ester or propionic acid ester, etc. are preferred, and any one of these or a mixture of two or more may be used. it can.

As the electrolyte salt, one that dissolves in the non-aqueous solvent is used, and a combination of a cation and an anion is used. Alkali metals and alkaline earth metals are used as cations, and Cl ⁻ , Br ⁻ , I ⁻ , SCN ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , CF ₃ SO ₃ ^{− and the} like are used as anions. It is done. Specifically, for example, LiCl, LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiB (C ₆ H ₅ ) ₄ , LiBr, CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, N (CnF _{2n + 1} SO ₂ ) ₂ Li and the like, and any one of these or a mixture of two or more thereof is used. Among them, it is preferable to mainly use LiPF ₆ . The electrolyte salt concentration is not a problem as long as it can be dissolved in the non-aqueous solvent, but the lithium ion concentration is 0.4 mol / kg or more and 2.0 mol / kg or less with respect to the non-aqueous solvent. A range is preferable.

[Insulating material]
The insulating member 50 has a function of preventing contact between the positive electrode 21 and the negative electrode lead 40. In addition to such a function, it also has a function of preventing energization between the positive electrode 21 and the side wall of the battery can 11 electrically connected to the negative electrode 22. In the battery element 20, the positive electrode 21 constituting the outermost periphery is accommodated and disposed in the battery can 11 so as to be in electrical contact with the side wall of the battery can 11, and the width of the negative electrode lead 40 is larger than the width of the positive electrode 21. Is smaller than the positive electrode 21 and the battery can, an insulating member having a width wider than that of the positive electrode 21 and the negative electrode 22 is used.

  Moreover, it is preferable that the thickness of the insulating member 50 is 40 micrometers or more. This is because it is possible to prevent a burr generated when cutting the end of the negative electrode lead 40 from coming into contact with the positive electrode 21 that passes through the separator 23 and is opposed to the short circuit.

  Such an insulating member 50 is preferably made of, for example, a resin material. Specific examples include polypropylene, polyethylene, polyphenylene sulfide (PPS), polyimide, and copolymers of polypropylene and other polymers such as polyethylene, acrylic, and vinyl acetate.

  The insulating member 50 also has a function as a fixing member for fixing the winding terminal portion of the battery element 20, a so-called terminal tape.

[Production of battery element]
The positive electrode 21 and the negative electrode 22 as described above are alternately stacked with the two separators 23a and 23b and wound. At this time, as described above, the positive electrode 21 covers the outermost periphery of the battery element 20 so that the positive electrode active material uncoated portion becomes the outer periphery of the battery element.

  In general, the battery can is often connected to the negative electrode. For this reason, the negative electrode provided with the negative electrode active material layer on the negative electrode current collector covers the outermost periphery of the battery element, and the negative electrode current collector is exposed with the battery element outer peripheral surface side as the negative electrode active material layer uncoated portion. A structure in contact with the battery can is used. However, when the metal lithium foil is used as the negative electrode 22, if the negative electrode 22 covers the outermost periphery of the battery element 20, the battery can 11 and the negative electrode 22 cannot be brought into contact with each other with a low contact resistance. Therefore, the positive electrode 21 is configured to cover the outer periphery of the battery element, and the negative electrode lead 40 connected to the negative electrode 22 is circulated around the outer periphery of the battery element, so that the negative electrode 22 and the battery can 11 are electrically connected. To.

  At this time, as shown in FIG. 2, the winding termination portion of the positive electrode 21 does not have a portion facing the negative electrode lead 40 adjacent to the winding termination portion of the positive electrode 21 through only the separator.

  Iron contained in the positive electrode active material is dissolved in the electrolytic solution and deposited in a needle shape on the surface of the negative electrode lead 40 having the same potential as the negative electrode 22 when connected to the negative electrode 22. For this reason, as shown in FIG. 3, when the negative electrode lead 40 is provided so that the positive electrode 21 and the negative electrode lead 40 do not face each other only through the separator 23, the metal lithium is pressed by the thickness of the negative electrode lead 40, It causes a small short circuit inside the battery. Therefore, short-circuiting can be suppressed by disposing the winding terminal portion of the positive electrode 21 and the negative electrode lead 40 so that there is no portion facing only through the separator 23.

  Next, the negative electrode lead 40 provided with the adhesive layer 41 and the insulating member 50 are prepared, and the insulating member 50 and the negative electrode lead 40 are fixed by being overlapped via the adhesive layer 41. Subsequently, as shown in FIG. 4, the negative electrode lead 40 is brought into contact with the negative electrode 22 by fixing one end portion of the insulating member 50 to the separator 23 a on the inner peripheral side of the negative electrode 22 with the negative electrode lead 40 facing the battery can 11. Let Further, the remaining portion of the negative electrode lead 40 circulates around the battery element 20 and the other end portion of the negative electrode lead 40 is overlapped and fixed to one end portion, and then unnecessary portions are cut.

[Production of battery]
Subsequently, the battery element 20 in which the winding surface of the battery element 20 to which the negative electrode lead 40 and the insulating member 50 are attached is covered with the pair of insulating plates 12 and 13 and the positive electrode lead 30 is welded to the safety valve mechanism 14. The battery can 11 is housed inside. Furthermore, after injecting the electrolyte into the battery can 11 and impregnating the separator 23, the battery lid 13 at the opening end of the battery can 11, the safety valve mechanism 14 provided inside the battery lid 13, and the PTC element 15 is fixed by caulking through the gasket 16.

  In addition, it is necessary to use the positive electrode lead 30 having a certain length in the manufacturing process. This is for sealing the open end of the battery can 11 after connecting the positive electrode lead 30 to the safety valve mechanism 14 provided in the battery lid 13 in advance. The shorter the positive electrode lead 30 is, the positive electrode lead 30 and the battery lid 13 are. Connection becomes difficult. By caulking the battery lid in this way, the positive electrode lead 30 is bent and accommodated in a substantially U shape inside the battery 10.

  As described above, the battery as shown in FIG. 1 is manufactured.

  Since this battery is a primary battery, it is not charged and only discharged once. When discharging is performed, metallic lithium is eluted as lithium ions from the negative electrode 22 and is occluded by the positive electrode 21 through the electrolytic solution. Here, since the negative electrode lead 40 is provided around the battery element 20 between the battery element 20 and the battery can 11, the contact area between the negative electrode lead 40 and the battery can 11 increases during heat generation, and the internal Resistance is greatly reduced.

  Further, in this battery, since the insulating member 50 is provided between the battery element 20 and the battery can 11, the battery electrically connected to the positive electrode 21 and the negative electrode 22 constituting the outermost periphery of the battery element 20. Energization with the can 11 is prevented.

  As described above, in the embodiment of the present invention, the negative electrode lead 40 and the positive electrode 21 are configured so that the negative electrode lead 40 and the positive electrode 21 do not face each other at the winding terminal portion of the battery element. It is possible to prevent a small short circuit from occurring inside the battery.

  Further, since the negative electrode lead 40 is provided around the battery element 20 between the battery element 20 and the battery can 11, the contact area between the negative electrode lead 40 and the side wall of the battery can 11 is increased, and as a result. The internal resistance is greatly reduced, the discharge voltage is increased, and the load characteristics are improved.

  In particular, since the negative electrode lead 40 is made of copper, the internal resistance can be further reduced, the voltage can be increased, and the load characteristics can be improved.

  Moreover, since the width of the negative electrode lead 40 is shorter than the width of the negative electrode 22 by 2 mm or more, deterioration due to storage can be suppressed.

  Furthermore, since the adhesive layer 41 is provided on the surface of the negative electrode lead 40 on the battery element 20 side, the position of the negative electrode lead 40 can be stabilized, and the negative electrode lead 40 is inserted in the step of inserting the battery element 20 into the battery can 11. Can be prevented from bending or cutting, enabling stable production.

  In addition, since the insulating member 50 is provided between the negative electrode lead 40 and the battery element 20 and the thickness of the insulating member 50 is set to 40 μm or more, the burr generated when the end of the negative electrode lead 40 is cut is separated from the separator 23. It is possible to suppress a short circuit from being brought into contact with the positive electrode 21 that penetrates through and opposite to the positive electrode 21.

  Hereinafter, the present invention will be specifically described by way of examples. In the following Examples and Comparative Examples, AAA type lithium iron sulfide batteries were produced.

<Example 1>
[Production of positive electrode]
Iron sulfide powder, graphite as a conductive agent, and polyvinylidene fluoride as a binder are mixed at a solid content ratio of iron sulfide: graphite: polyvinylidene fluoride = 90: 5: 5 and used as a solvent. Dispersed in N-methyl-2-pyrrolidone to obtain a positive electrode mixture slurry. The positive electrode mixture slurry is uniformly applied to both surfaces of a positive electrode current collector made of an aluminum foil, cut into a predetermined size, and then compression-molded with a roll press machine to form an outer positive electrode active material layer and an inner positive electrode active material. A layer was formed to produce a positive electrode.

  Next, a part of the outer positive electrode active material layer is peeled off so that the inner positive electrode active material layer is longer than the outer positive electrode active material layer at one end on the winding outer peripheral side of the positive electrode, and the positive electrode active material uncoated portion Formed. Moreover, the positive electrode lead made from aluminum was attached to the positive electrode current collector of the other end part used as the winding center side of a positive electrode by welding.

[Production of battery element]
Then, the negative electrode which consists of metal lithium foil was prepared, the positive electrode and the negative electrode were laminated | stacked through the separator, and it wound so that a positive electrode might cover the outermost periphery of a battery element, and produced the battery element.

[Preparation of electrolyte]
50 parts by weight of ethylene carbonate (EC) and 50 parts by weight of propylene carbonate (PC) were mixed, and 0.7 mol / kg of LiPF ₆ was dissolved as an electrolyte salt to prepare an electrolytic solution.

[Production of battery]
After producing the battery element as described above, a negative electrode lead made of a copper foil tape provided with an adhesive layer and an insulating member having a thickness of 40 μm were prepared, and the negative electrode lead was fixed to the insulating member with an adhesive layer. After fixing the negative electrode lead to the insulating member, the negative electrode lead was brought into contact with the negative electrode by fixing the negative electrode lead to the battery can side and fixing one end of the insulating member to the separator on the inner peripheral side of the negative electrode. Subsequently, the negative electrode lead was wound around the battery element, and the other end portion was overlapped and fixed to one end portion and cut.

  At this time, in the battery element outermost peripheral part, the end position of the copper foil tape sticking start position is 5 cm away from the positive electrode winding end position, and the end position is set so that the positive electrode winding end part and the copper foil tape do not overlap. adjust. Further, the negative electrode collecting end is adjusted so as to overlap with the copper foil tape by 10 cm.

  After winding the insulating member and the negative electrode lead around the battery element, the battery element was sandwiched between a pair of insulating plates, the positive electrode lead was welded to the safety valve mechanism, and the battery element was accommodated inside the battery can. Next, the electrolytic solution was injected into the battery can and impregnated in the separator. Furthermore, a battery having the same configuration as the battery shown in FIG. 1 was produced by caulking a battery lid and a safety valve to the open end of the battery can via a gasket.

<Comparative Example 1>
A battery was fabricated in the same manner as in Example 1, except that the end of the copper foil tape was covered with 5 cm of the positive electrode terminal at the outermost periphery of the battery element.

<Comparative example 2>
A battery was fabricated in the same manner as in Example 1, except that the adhesion start end of the copper foil tape was covered 15 cm with the positive electrode termination at the outermost periphery of the battery element.

<Comparative Example 3>
At the outermost periphery of the battery element, a strip-shaped negative electrode lead made of nickel is crimped to the negative electrode end without being provided with a negative electrode lead made of copper foil tape and circulated around the outer periphery of the battery element. A battery was fabricated in the same manner as in Example 1, except that the contact was made.

  The following measurement (a), measurement (b), and measurement (c) were performed on the batteries of Example 1 and Comparative Examples 1 to 3 thus obtained.

Measurement (a) Measurement of storage retention rate For each of Example 1 and Comparative Examples 1 to 3 described above, 100 batteries were produced, and the storage retention rate was measured. For each of Example 1 and Comparative Examples 1 to 3, 50 of the 100 batteries obtained were immediately discharged at 1000 mA immediately after the production of the battery, and the initial average discharge capacity was measured. Next, the remaining 50 pieces were stored in an atmosphere of 60 ° C. for 3 months, then discharged at 1000 mA, and the average discharge capacity after storage was measured.

The storage maintenance rate was determined as follows.
Storage maintenance ratio [%] = (Average discharge capacity after storage [mAh]) / (Initial average discharge capacity [mAh]) × 100

Measurement (b) Abnormal discharge failure rate For each of Example 1 and Comparative Examples 1 to 3 described above, 100 batteries were produced, and the abnormal discharge failure rate was measured. For each of Example 1 and Comparative Examples 1 to 3, 50 of the 100 batteries obtained were immediately discharged by applying a resistance of 42Ω immediately after the battery was manufactured, and the discharge capacity was measured. Next, the remaining 50 pieces were stored in an atmosphere of 60 ° C. for 3 months, and then discharged with a resistance of 42Ω, and the discharge capacity was measured. A battery whose discharge was completed with a capacity less than 80% of the input capacity was regarded as abnormal discharge failure, and the abnormal discharge failure rate was measured.

The abnormal discharge failure rate was determined as follows.
Abnormal discharge failure rate [%] = (number of batteries with 42Ω discharge less than 80% of input capacity [pieces]) / (number of test batteries [pieces]) × 100
In this measurement, the number of test batteries is 50.

Measurement (c) Internal Resistance With respect to Example 1 and Comparative Examples 1 to 3 described above, 100 batteries were prepared and the internal resistance was measured. For each of Example 1 and Comparative Examples 1 to 3, the impedance when an alternating current of 1 kHz was passed was obtained, the internal resistance was examined, and the average internal resistance was examined.

  Table 1 below shows the measurement results of measurement (a), measurement (b), and measurement (c). In Table 1, in the batteries of Example 1 and Comparative Examples 1 and 2 in which the negative electrode lead made of the copper foil tape was circulated around the battery element outer peripheral portion, the positive electrode termination portion relative to the adhesion start end position of the copper foil tape and The position of the negative electrode collecting end portion is described as + in the direction overlapping with the copper foil tape and-as the direction not overlapping with the copper foil tape. For example, when the electrode overlaps with the copper foil tape by 5 cm, it is +5 cm, and when the copper foil tape does not overlap with the electrode end portion, it is −5 cm.

  From the above results, in a battery having a configuration in which a metal lithium foil is used as the negative electrode and the negative electrode lead is circulated around the outer periphery of the battery element, the negative electrode lead and the positive electrode are configured so as not to face each other. It can be seen that each defective rate can be maintained well.

  The cause of this is not clear, but the negative electrode lead and the positive electrode are opposed to each other, so that the metal lithium of the negative electrode is pressed by the thickness of the negative electrode lead, and a small short circuit occurs at the opposite part of the negative electrode lead and the positive electrode. It is considered that the battery was deteriorated or abnormal discharge occurred. For this reason, it is considered that the decrease in the storage maintenance rate and the occurrence of abnormal discharge can be suppressed by configuring the negative electrode lead and the positive electrode so as not to face each other.

  Further, as compared with a battery using a strip-shaped negative electrode lead, a battery having a configuration in which the negative electrode lead is circulated around the outer periphery of the battery element can reduce internal resistance.

  Although one embodiment of the present invention has been specifically described above, 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.

  In addition, the positive electrode 21 is not limited to an iron-based material, and an effect can be obtained by using the configuration of the present invention as long as it is a material that can be dissolved in an electrolytic solution, deposited, and short-circuited. Moreover, even if it is another material, a positive electrode and a negative electrode may be pressed by making it the structure which makes a negative electrode lead go around the battery element outer peripheral part, and a malfunction may arise. For this reason, even if it is other than the material which melt | dissolves in electrolyte solution and deposits inside a battery, an effect can be acquired by using the structure of this invention.

  The negative electrode 22 is not limited to a metal lithium foil, and may be a structure in which a negative electrode active material layer made of metallic lithium is provided on a negative electrode current collector made of another metal such as copper.

  Furthermore, in the above-described one embodiment and example, the case where the insulating member is directly wound around the outermost periphery of the battery element has been described. However, a separator is provided on the outermost periphery of the battery element, and an insulating member is further provided. It is good also as a structure. In such a case, the insulating member is not necessarily provided, and the vicinity of the winding terminal portion of the separator may be fixed by a fixing member, and the negative electrode lead may be rotated around the outermost separator and fixed. .

  Moreover, although the above-mentioned one Embodiment and Example demonstrated the case where the insulating member was combined with what is called a termination | terminus tape, you may provide as a member different from an insulation member and a termination | terminus tape. In this case, the termination tape does not need to go around the battery element, and may be provided only in a part near the winding termination portion of the battery element.

  In addition, the insulating member is not necessarily fixed to the separator on the inner peripheral side of the negative electrode. If the negative electrode lead 40 can contact the negative electrode 22 and the inner wall of the battery can 11, the separator 23 on the outer peripheral side of the negative electrode 22. It may be fixed to.

It is a schematic diagram which shows the cross-sectional structure of the vertical direction of the battery by one Embodiment of this invention. It is a schematic diagram which shows the cross-sectional structure of the horizontal direction of the battery by one Embodiment of this invention. It is a schematic diagram which shows the cross-sectional structure of the horizontal direction of the battery at the time of making the winding termination | terminus part of a positive electrode oppose a negative electrode lead. It is a schematic diagram which shows the winding structure of the battery element accommodated in the battery by one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Battery 11 ... Battery can 12a, 12b ... Insulation board 13 ... Battery cover 14 ... Safety valve mechanism 14a ... Disk board 15 ... PTC element 16 ... Insulation sealing gasket DESCRIPTION OF SYMBOLS 20 ... Battery element 21 ... Positive electrode 21a ... Positive electrode collector 21b ... Positive electrode active material layer 22 ... Negative electrode 23 ... Separator 24 ... Center pin 30 ... Positive electrode lead 40 ... Negative electrode lead 41 ... Adhesive layer 50 ... Insulating member

Claims (4)

Have a positive and negative electrodes containing iron as a positive electrode active material, one of the positive electrode and the negative electrode, a battery element having a wound winding structure in such a manner that the outer peripheral side than the other, the A battery can containing a battery element;
The battery can is electrically connected to either the positive electrode or the negative electrode by a lead,
The lead is provided around the battery element between the battery element and the battery can, and an insulating member is provided between the lead and the battery element.
The lead start end of the lead does not overlap with the terminal of either the positive electrode or the negative electrode that is not electrically connected to the battery can.
Batteries. The insulating member has a thickness of 40 μm or more.
The battery according to claim 1 . The above negative electrode, you occluding the inclusion or attachment or lithium ions of lithium
The battery according to 請 Motomeko 1. The lead is that consists of copper (Cu)
The battery according to 請 Motomeko 1.

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