Cylindrical lithium primary battery

Abstract

The present disclosure provides a cylindrical lithium primary battery having high reliability. The disclosed cylindrical lithium primary battery includes: an electrode group (10) in which a positive electrode (1) and a negative electrode (2) are wound with a separator (3) therebetween; a short-circuit metal sheet (21) that is electrically connected to the negative electrode (2); and a battery case that functions as a negative electrode terminal. The positive electrode (1) includes a positive electrode mixture layer (1b). The negative electrode (2) includes a lithium-containing metal sheet. The positive electrode mixture layer (1b) has a reaction suppression region (1y). The reaction suppression region (1y) has a first surface (Sp1) and a second surface (Sp2). In the separator (3), an adjacent portion (3a) adjacent to the first surface (Sp1) has a first surface (Ss1) on the first surface (Sp1) side and a second surface (Ss2) on the side opposite from the first surface (Ss1). The second surface (Ss2) is not adjacent to the lithium-containing metal sheet. At least a portion of the second surface (Sp2) is a short-circuit inducing region (1z). The short-circuit inducing region (1z) faces the short-circuit metal sheet across the separator (3).

Description

Cylindrical lithium primary battery

[0001] The present disclosure relates to cylindrical lithium primary batteries.

[0002] Lithium primary batteries are used in many electronic devices due to their high energy density and low self-discharge. Various types of lithium primary batteries have been proposed.

[0003] Claim 1 of Patent Document 1 (JP 2016-122592 A) describes, "A spiral lithium battery in which a strip-shaped electrode body, in which a negative electrode containing lithium metal or a lithium alloy as a negative electrode active material is disposed opposite a positive electrode with a separator interposed therebetween, is wound in the longitudinal direction and sealed together with a nonaqueous organic electrolyte in a bottomed cylindrical battery can that also serves as a negative electrode current collector, wherein the extension direction of the cylindrical axis of the battery can is the vertical direction, the electrode body has the vertical direction as a winding axis, and is wound with the winding start from the winding axis so that the negative electrode is disposed at the outermost periphery, and a conductor that is continuous in the longitudinal direction of the electrode body is affixed to the outer peripheral surface of the negative electrode from the end of the winding to a region that faces the inner surface of the positive electrode on the winding end side."

[0004] Claim 1 of Patent Document 2 (JP 2018-56075 A) describes an electrode assembly comprising: a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; a non-aqueous electrolyte; and a metal case accommodating the electrode assembly and the non-aqueous electrolyte; the positive electrode and the negative electrode are wound with the separator interposed therebetween to form a columnar electrode assembly in which the outermost periphery of the negative electrode is disposed outwardly of the outermost periphery of the positive electrode; the negative electrode contains metallic lithium or a lithium alloy; a copper-based metal foil is attached to the negative electrode; the copper-based metal foil extends from a portion on an outer surface or an inner surface of the negative electrode that faces a winding end end of the positive electrode or from a first position that is outer than the facing portion; the copper-based metal foil is wound around the electrode assembly from the first position one or more times; and a tab lead is electrically connected to at least one of the negative electrode and the copper-based metal foil. The lithium primary battery is characterized in that the tab lead is electrically connected to the metal case.

[0005] JP 2016-122592 A JP 2018-56075 A

[0006] Lithium primary batteries are expected to be used under harsher conditions and environments, and further improvements in reliability are required. One of the objects of the present disclosure is to provide a cylindrical lithium primary battery with high reliability.

[0007] One aspect of the present disclosure is a cylindrical lithium primary battery comprising: an electrode group in which a positive electrode and a negative electrode are wound with a separator interposed therebetween; a short-circuiting metal sheet disposed on the negative electrode and electrically connected to the negative electrode; and a battery case that houses the electrode group and functions as a negative electrode terminal; the positive electrode comprises a positive electrode current collector having a plurality of through holes, and a positive electrode mixture layer disposed on the positive electrode current collector; the negative electrode comprises a lithium-containing metal sheet, the lithium-containing metal sheet, the short-circuiting metal sheet, and the battery case are electrically connected; the short-circuiting metal sheet comprises at least one metal element M selected from the group consisting of copper, iron, titanium, nickel, and zinc; the positive electrode mixture layer has a reaction suppression region, and the reaction suppression region has a first surface Sp1 and a second surface Sp2 opposite to the first surface Sp1, and the first surface Sp1 and the second surface Sp2 are each adjacent to the separator; the portion of the separator adjacent to the first surface Sp1 has a first surface Ss1 on the first surface Sp1 side and a second surface Ss2 on the opposite side of the first surface Ss1, the second surface Ss2 is not adjacent to the lithium-containing metal sheet, at least a part of the second surface Sp2 is a short-circuit inducing region, and the short-circuit inducing region faces the short-circuiting metal sheet across the separator.

[0008] According to the present disclosure, a highly reliable cylindrical lithium primary battery can be obtained.

[0009] FIG. 1 is a partially exploded cross-sectional view schematically showing an example of a lithium primary battery of Embodiment 1. FIG. 2 is a cross-sectional view schematically showing a portion of an example of a lithium primary battery of Embodiment 1. FIG. 3 is a cross-sectional view schematically showing a portion of an example of a lithium primary battery of Embodiment 1. FIG. 4A is a top view schematically showing a portion of a lithium primary battery produced in an Example. FIG. 4B is a cross-sectional view schematically showing a portion of the lithium primary battery shown in FIG. 4A. FIG. 5A is a top view schematically showing a portion of another lithium primary battery produced in an Example. FIG. 5B is a cross-sectional view schematically showing a portion of the lithium primary battery shown in FIG. 5A. FIG. 6 is a top view schematically showing a portion of another lithium primary battery produced in an Example. FIG. 7 is a top view schematically showing a portion of another lithium primary battery produced in an Example. FIG. 8A is a top view schematically showing a portion of another lithium primary battery produced in an Example. FIG. 8B is a cross-sectional view schematically showing a portion of the lithium primary battery shown in FIG. 8A. FIG. 9 is a top view schematically showing a portion of another lithium primary battery fabricated in the Examples. FIG. 10 is a top view schematically showing a portion of another lithium primary battery fabricated in the Examples. FIG. 11 is a top view schematically showing a portion of another lithium primary battery fabricated in the Examples. FIG. 12A is a top view schematically showing a portion of a lithium primary battery fabricated as a comparative example. FIG. 12B is a cross-sectional view schematically showing a portion of the lithium primary battery shown in FIG. 12A. FIG. 13A is a top view schematically showing a portion of another lithium primary battery fabricated as a comparative example. FIG. 13B is a cross-sectional view schematically showing a portion of the lithium primary battery shown in FIG. 13A. FIG. 14A is a top view schematically showing a portion of another lithium primary battery fabricated as a comparative example. FIG. 14B is a cross-sectional view schematically showing a portion of the lithium primary battery shown in FIG. 14A. FIG. 15 is a diagram schematically showing an evaluation method used in the Examples.

[0010] Below, embodiments according to the present disclosure will be described using examples, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be exemplified, but other numerical values ​​and materials may be applied as long as the effects of the present disclosure are obtained. In this specification, the expression "numerical value A to numerical value B" includes numerical value A and numerical value B and can be read as "numerical value A or more and numerical value B or less." In the following description, when numerical values ​​for specific physical properties or conditions are exemplified as lower and upper limits, any of the exemplified lower limits and any of the exemplified upper limits can be arbitrarily combined, as long as the lower limit is not equal to or greater than the upper limit.

[0011] (Lithium Primary Battery) A cylindrical lithium primary battery according to this embodiment will be described below. The lithium primary battery according to this embodiment may be referred to as a "lithium primary battery (B)" or a "primary battery (B)" below.

[0012] The lithium primary battery (B) is a cylindrical lithium primary battery. The primary battery (B) includes an electrode assembly in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, a short-circuiting metal sheet disposed on the negative electrode and electrically connected to the negative electrode, and a battery case that houses the electrode assembly and functions as a negative electrode terminal. The positive electrode includes a positive electrode current collector having a plurality of through-holes and a positive electrode mixture layer disposed on the positive electrode current collector. The negative electrode includes a lithium-containing metal sheet. The lithium-containing metal sheet, the short-circuiting metal sheet, and the battery case are electrically connected. The short-circuiting metal sheet includes at least one metal element M selected from the group consisting of copper, iron, titanium, nickel, and zinc. The positive electrode mixture layer has a reaction suppression region. The reaction suppression region has a first surface Sp1 and a second surface Sp2 opposite the first surface Sp1. The first surface Sp1 and the second surface Sp2 are each adjacent to the separator. The portion of the separator adjacent to the first surface Sp1 has a first surface Ss1 on the first surface Sp1 side and a second surface Ss2 on the opposite side of the first surface Ss1. The second surface Ss2 is not adjacent to the lithium-containing metal sheet. At least a portion of the second surface Sp2 is a short-circuit inducing region. The short-circuit inducing region faces the short-circuiting metal sheet across the separator.

[0013] The second surface Ss2 of the separator is not adjacent to the lithium-containing metal sheet. That is, on the first surface Ss1 side of the reaction suppression region, there is no lithium-containing metal sheet that supplies lithium ions to the reaction suppression region during discharge. Therefore, the discharge reaction is suppressed in the reaction suppression region. The second surface Ss2 of the separator may be adjacent to another portion of the separator. In this specification, "surface A (or member A, or portion A) adjacent to member B (or surface B, or portion B)" means that no other member exists between surface A and member B (or that surface A and member B are positioned in the closest position in the opposing direction and overlap each other).

[0014] In one example where the lithium-containing metal sheet and the second surface Ss2 of the separator are not adjacent, the winding end of the lithium-containing metal sheet does not reach the second surface Ss2. In one example, a reaction suppression region is present in a part of the positive electrode between the innermost periphery of the positive electrode and the outermost periphery of the positive electrode, the second surface Ss2 of the separator is not adjacent to the lithium-containing metal sheet, and the second surface Ss2 of the separator is adjacent to another part of the separator. In another example where the lithium-containing metal sheet and the second surface Ss2 of the separator are not adjacent to each other, the reaction suppression region is located on the winding start side of the electrode group, the first surface Sp1 of the reaction suppression region faces the inner periphery, the second surface Ss2 of the separator faces the inner periphery, and the winding start end of the lithium-containing metal sheet does not reach the second surface Ss1 of the separator. In one example, a reaction suppression region is present in a portion of the positive electrode between the innermost periphery and the outermost periphery of the positive electrode, and the second surface Sp2 of the reaction suppression region faces the inner periphery or the outer periphery. The second surface Ss2 of the separator is not adjacent to the lithium-containing metal sheet, and the second surface Ss2 of the separator is adjacent to another portion of the separator. In these configurations, a portion of the lithium-containing metal sheet adjacent to the second surface Ss2 may be cut out. The method for forming the cutout portion of the lithium-containing metal sheet is not particularly limited, and may be formed by punching or the like. "Two members (or surfaces) are adjacent within an electrode group" means that the two members (or surfaces) are adjacent in the radial direction of the electrode group. Two adjacent members (or surfaces) within an electrode group do not necessarily need to be in contact at the adjacent portions, but typically are in contact at the adjacent portions.

[0015] The positive electrode has a reaction suppression region (reaction suppression portion) and a normal reaction region. The normal reaction region is a region where a lithium-containing metal sheet that supplies lithium ions to the normal reaction region during discharge is located at a position opposite to the surface of the normal reaction region (more specifically, at a position opposite both sides of the normal reaction region across the separator).

[0016] Assume that multiple lithium primary batteries are connected in series and used as a power source for an external device. If, for some reason, one of the multiple lithium primary batteries, battery X, becomes less capable than the other batteries, the voltage (energy) of the other batteries will force the discharge of battery X, even if the capacity of battery X is exhausted (i.e., the voltage range for normal use is exceeded). This may result in battery X entering a polarity inversion state (polarity inversion state due to overdischarge). Battery X in a polarity inversion state reacts differently from normal discharge, often resulting in a high internal resistance of battery X. Furthermore, if the internal resistance of battery X becomes higher than the resistance of the external device, resistance heat is generated by the current flowing through battery X, making battery X prone to high temperatures. After further investigation, the present inventors discovered that adopting the configuration of lithium primary battery (B) can suppress the temperature rise of a battery in a polarity inversion state. The present disclosure is based on this new finding.

[0017] When multiple batteries are connected in series, if some of the batteries become overdischarged and undergo polarity reversal, current continues to flow through the batteries in the polarity-reversed state. This can result in battery overheating and elution of the battery case. In the lithium primary battery (B), when polarity reversal occurs, it is believed that precipitation of metal element M occurs preferentially in the short-circuit-inducing region of the positive electrode, forming a low-resistance conductive path between a portion of the positive electrode and the short-circuiting metal sheet through the deposited metal (e.g., deposited copper). Therefore, it is possible to suppress the temperature rise of the battery in the polarity reversal state. Furthermore, according to the technology disclosed herein, the formation of a conductive path by the precipitation of metal element M occurs preferentially over the elution of the battery case, thereby suppressing the elution of the battery case.

[0018] In this specification, the term "two components electrically connected" refers to a configuration in which the two components are directly connected and a configuration in which the two components are connected via another conductive component. Examples of conductive portions include metals (leads, metal current collectors, deposited metals, etc.), adhesive layers formed to conduct electricity, resin films formed to conduct electricity, and positive electrode mixture layers. The adhesive layer (or resin film) formed to conduct electricity may be a known or commercially available adhesive layer (or resin film) that conducts electricity.

[0019] The short-circuiting metal sheet may be a sheet of copper, iron, titanium, nickel, or zinc, or may be a sheet of an alloy containing at least one metal element M. The proportion of one metal element M in the alloy may be 50% by mass or more, or 90% by mass or more. The short-circuiting metal sheet may be a copper sheet or a copper alloy sheet. The copper content in the copper alloy may be 50% by mass or more, or 90% by mass or more. Copper has a lower ionization tendency than other common metal elements (e.g., metal element M), so copper precipitates quickly when a copper sheet or a copper alloy sheet is used. As a result, a stable short circuit can be formed. When multiple short-circuiting metal sheets containing different metal elements M are arranged, the metal element that precipitates easily forms a short circuit, while the other metal elements ensure the conductivity of the foil, resulting in a more stable short circuit.

[0020] The lithium primary battery (B) may satisfy the following (1) and / or (2): (1) the reaction suppression region is present in the outermost periphery of the positive electrode, and (2) the short-circuiting metal sheet and the second surface Sp2 face each other across the separator over the entire circumferential direction of the second surface Sp2 (or over a wider circumferential range than the second surface Sp2).

[0021] If a reaction suppression layer is present, the balance between the positive electrode capacity and the negative electrode capacity may be disrupted, and the lithium-containing metal sheet may be prone to breaking during discharge. By satisfying condition (2), it is possible to prevent the portion of the lithium-containing metal sheet facing the second surface Sp2 from breaking during discharge.

[0022] In this specification, the outermost periphery of the positive electrode means the outermost circumferential portion of the positive electrode. Similarly, the outermost periphery of the negative electrode means the outermost circumferential portion of the negative electrode. Furthermore, the innermost periphery of the positive electrode means the innermost circumferential portion of the positive electrode. Similarly, the innermost periphery of the negative electrode means the innermost circumferential portion of the negative electrode. A separator may be disposed on the outermost periphery of the electrode group.

[0023] The area S of the short circuit induction region is 2 mm ２ Above, 4mm ２ That's all, 9mm ２ Above, 30mm ２ Above 75mm ２ Above, 250mm ２ or more, or 270 mm ２ The area S may be 1200 mm or more. ２ Below, 270mm ２ Below, 250mm ２ Below, 75mm ２ Below, 30mm ２ Below, 9mm ２ Less than or equal to 4 mm ２ The area S may be 2 to 1200 mm ２ Range: 4 to 1200 mm ２ Range: 9 to 1200 mm ２ Range: 30 to 1200 mm ２ Range: 75 to 1200 mm ２ Range: 250-1200mm ２ Range: 270-1200mm ２ In any of these ranges, the upper limit may be set to 4 mm, unless the lower limit is greater than or equal to the upper limit. ２ , 9mm ２ , 30 mm ２ , 75mm ２ , 250 mm ２, or 270 mm ２ The area S of the short circuit induction region is 4 mm ２ Above 1200mm ２ The area S may be 4 mm or less. ２ By setting the area S to 1200 mm or more, it is possible to particularly suppress the temperature rise of the battery when the polarity is inverted. ２ By setting the temperature to the following range, it is possible to suppress a decrease in discharge capacity.

[0024] The width W of the facing portion of the short-circuiting metal sheet facing the second surface Sp2 across the separator may be 3 mm or more. That is, the width W of the short-circuiting metal sheet in the short-circuit inducing region may be 3 mm or more. Here, the facing portion of the short-circuiting metal sheet has a band-like shape. The width W of the facing portion of the short-circuiting metal sheet is the length in the short direction of the facing portion having a band-like shape. By setting the width W to 3 mm or more, it is possible to suppress the lithium-containing metal sheet on the second surface Sp2 from reacting with the positive electrode near the short-circuiting metal sheet. As a result, it is possible to promote the formation of a short-circuit path when a polarity inversion state occurs.

[0025] A narrow short-circuiting metal sheet, for example, a short-circuiting metal sheet having a width equal to or less than one-third (e.g., equal to or less than one-fourth or one-fifth) the width of the lithium-containing metal sheet, may be used. In this case, the short-circuiting metal sheet may be arranged on the lithium-containing metal sheet so that the longitudinal direction of the short-circuiting metal sheet is inclined with respect to the circumferential direction of the electrode assembly. By arranging the short-circuiting metal sheet in this manner, it is possible to alleviate stress generated within the electrode assembly. Furthermore, by using a short-circuiting metal sheet having a length sufficient to wrap around the electrode assembly one or more times, it is possible to prevent the negative electrode (lithium-containing metal sheet) from being cut midway during discharge, thereby preventing the electrical path from being interrupted.

[0026] The reaction suppression region may be present on the outermost periphery of the positive electrode, the innermost periphery of the positive electrode, or the positive electrode between the innermost periphery and the outermost periphery of the positive electrode. In one example of a lithium primary battery (B), the reaction suppression region is present on the innermost periphery of the positive electrode, and the short-circuit metal sheet is present on the outer periphery of the reaction suppression region.

[0027] The lithium primary battery (B) may further include a short-circuiting metal sheet and a negative electrode lead that electrically connects the lithium-containing metal sheet to the battery case. In this case, the negative electrode lead may be laminated on the short-circuiting metal sheet and the lithium-containing metal sheet. When a part of the short-circuiting metal sheet and a part of the negative electrode lead are laminated on the lithium-containing metal sheet, they may be laminated in the order of lithium-containing metal sheet / short-circuiting metal sheet / negative electrode lead, or lithium-containing metal sheet / negative electrode lead / short-circuiting metal sheet, or short-circuiting metal sheet / lithium-containing metal sheet / negative electrode lead.

[0028] A portion of the short-circuiting metal sheet may function as a negative electrode lead, and this portion may protrude from the electrode group and be connected to the battery case.

[0029] (Short-circuiting metal sheet, lithium-containing metal sheet) The short-circuiting metal sheet may include a sheet of metal element M or a sheet of an alloy of metal element M. The lithium-containing metal sheet may include a sheet of lithium or a sheet of a lithium alloy. These sheets may be foils. For example, the short-circuiting metal sheet may be copper foil or copper alloy foil. The lithium-containing metal sheet may be lithium foil (lithium metal foil) and / or lithium alloy foil.

[0030] The short-circuiting metal sheet is electrically conductive. The content of the metal element M (e.g., copper) in the short-circuiting metal sheet may be 50 mass % or more, 90 mass % or more, or 95 mass % or more. When the short-circuiting metal sheet is made of a copper alloy, the copper alloy may be a copper alloy used as a lead material for known non-aqueous electrolyte batteries.

[0031] The thickness and size of the shorting metal sheet can be selected depending on the battery configuration. The thickness of the shorting metal sheet may be 5 μm or more, or 20 μm or more, or may be 500 μm or less, or 100 μm or less. If the shorting metal sheet is too thin, it will be easily torn, increasing the possibility that the shorting path will not be maintained in a polarity reversal state. On the other hand, if the shorting metal sheet is too thick, it will be more likely to short-circuit between the shorting metal sheet and the positive electrode under normal conditions.

[0032] The short-circuiting metal sheet may be disposed on the negative electrode across the entire width of the negative electrode, or may be disposed on only a portion of the width of the negative electrode. From the viewpoint of preventing short circuits, the end of the short-circuiting metal sheet (the end in the winding axis direction Dax) does not have to protrude from the end of the negative electrode (the end in the winding axis direction Dax). That is, the length of the short-circuiting metal sheet in the winding axis direction Dax may be equal to or less than the width of the negative electrode (the length in the winding axis direction Dax). However, if the short-circuiting metal sheet also serves as a negative electrode lead, a portion of the short-circuiting metal sheet protrudes outward beyond the end of the negative electrode.

[0033] The short-circuiting metal sheet may be welded to the lithium-containing metal sheet. The short-circuiting metal sheet may be adhered to the lithium-containing metal sheet with a conductive adhesive (conductive adhesive layer). When the short-circuiting metal sheet is adhered to the lithium-containing metal sheet with a conductive adhesive, even if a part of the lithium-containing metal sheet disappears due to discharge, it is possible to maintain the conductive path in the part where the conductive adhesive is present.

[0034] The short-circuiting metal sheet may be adhered to the lithium-containing metal sheet by an insulating adhesive (insulating adhesive layer). When the short-circuiting metal sheet is adhered to the lithium-containing metal sheet only by an insulating adhesive, the short-circuiting metal sheet may be electrically connected to the lithium-containing metal sheet via the negative electrode lead. In this case, the negative electrode lead is connected to the short-circuiting metal sheet and the lithium-containing metal sheet.

[0035] The short-circuiting metal sheet may be disposed on the inner circumferential surface of the wound negative electrode, or the short-circuiting metal sheet may be disposed on the outer circumferential surface of the wound negative electrode.

[0036] As described above, the primary battery (B) may further include a negative electrode lead. The negative electrode lead is not particularly limited, and a negative electrode lead used in a known non-aqueous electrolyte battery may be used. Examples of materials for the negative electrode lead include iron, iron alloys, nickel, stainless steel, copper, copper alloys, and clad materials thereof. The copper content of the negative electrode lead may be 50% by mass or more or less than 50% by mass. The shape and size of the negative electrode lead are selected depending on the discharge capacity of the primary battery (B), etc. A typical example of the negative electrode lead has an elongated strip shape.

[0037] In the primary battery (B), at least one selected from the group consisting of a lithium-containing metal sheet and a negative electrode lead may be electrically connected to the short-circuiting metal sheet via a conductive adhesive layer. The conductive adhesive layer is not particularly limited, and a conductive adhesive layer used in known non-aqueous electrolyte batteries may be used. The conductive adhesive layer may be formed by applying a conductive resin composition. Alternatively, the conductive adhesive layer may be a conductive tape. Examples of materials for the conductive adhesive layer include acrylic adhesives containing conductive carbon. When the metal element M elutes during a polarity reversal state, if the elution is concentrated in a portion of the short-circuiting metal sheet, the short-circuiting metal sheet may be severed at that portion, making it impossible to maintain a short-circuit path during the polarity reversal state. Even in such cases, the use of a conductive adhesive layer can prevent the short-circuit path from being severed.

[0038] Examples of components of the lithium primary battery (B) are described below, but the components of the lithium primary battery are not limited to the following examples. Components other than the essential components of the lithium primary battery (B) are not particularly limited, and known components may be used.

[0039] The lithium primary battery (B) includes an electrode group, a non-aqueous electrolyte, and an exterior housing that houses them. At least a portion of the short-circuiting metal sheet is disposed inside the electrode group. As described above, the lithium primary battery (B) may also include a negative electrode lead. The short-circuiting metal sheet, the lithium-containing metal sheet, and the negative electrode lead have been described above, and therefore, redundant description will be omitted.

[0040] The electrode assembly includes a wound positive electrode, a wound negative electrode, and a wound separator. A wound electrode assembly can be formed by winding a strip-shaped positive electrode, a strip-shaped negative electrode, and a strip-shaped separator. A separator is disposed between the positive electrode and the negative electrode. The electrode assembly is cylindrical overall.

[0041] (Positive Electrode (Positive Electrode Plate)) The positive electrode includes a positive electrode current collector and a positive electrode mixture (positive electrode mixture layer) held on the positive electrode current collector. Examples of materials for the positive electrode current collector include stainless steel, aluminum, and titanium. As described above, the positive electrode current collector has a plurality of through holes. Examples of positive electrode current collectors having a plurality of through holes include lath sheets (expanded metals), porous bodies, and punched metals. The thickness of the positive electrode current collector is not particularly limited. The thickness of the positive electrode current collector may be in the range of 100 μm to 500 μm (for example, in the range of 200 μm to 400 μm).

[0042] The positive electrode mixture layer contains a positive electrode active material and, as needed, additives (e.g., conductive material, binder). The positive electrode active material and additives are not particularly limited, and positive electrode active materials and additives used in known lithium primary batteries may be used. Examples of positive electrode active materials include graphite fluoride and manganese dioxide. Examples of conductive materials include graphite, carbon black, carbon fiber, metal fiber, and organic conductive materials. Examples of binders include fluororesins (e.g., polyvinylidene fluoride), styrene-butadiene rubber, fluororubber, and polyacrylic acid. The thickness of the positive electrode may be in the range of 200 μm to 1000 μm (e.g., 300 μm to 700 μm). Through-holes are formed in the positive electrode current collector, so the positive electrode mixture layer arranged on one side of the positive electrode current collector and the positive electrode mixture layer arranged on the other side of the positive electrode current collector are connected.

[0043] Insulating tape may be attached to both sides of the outer periphery of the positive electrode to prevent short circuits.

[0044] (Negative Electrode (Negative Electrode Plate)) As described above, the negative electrode includes a lithium-containing metal sheet (lithium-containing metal foil). The lithium content of the lithium-containing metal sheet may be 85% by mass or more, 90% by mass or more, or 95% by mass or more. The lithium-containing metal sheet may include a lithium metal foil (lithium sheet) and / or a lithium alloy foil (lithium alloy sheet). The negative electrode may be composed of only the lithium-containing metal sheet. The negative electrode may include a coating layer formed on the lithium-containing metal sheet. Examples of the coating layer include a carbon layer. The negative electrode may include a plurality of lithium-containing metal sheets and a metal foil (e.g., copper foil or copper alloy foil) connecting them.

[0045] Examples of lithium alloys used in lithium-containing metal sheets include Li-Al alloys, Li-Sn alloys, Li-Ni-Si alloys, and Li-Pb alloys. The content of metal elements other than lithium contained in the lithium alloy may be in the range of 0.05 to 15 mass %. This range is preferable in terms of ensuring discharge capacity and stabilizing internal resistance.

[0046] The thickness and size of the lithium-containing metal sheet are selected depending on the discharge capacity and size of the lithium primary battery (B). The thickness of the lithium-containing metal sheet may be in the range of 100 μm to 300 μm (for example, in the range of 150 μm to 250 μm).

[0047] (Non-aqueous electrolyte) The non-aqueous electrolyte is not particularly limited, and a non-aqueous electrolyte used in a known lithium primary battery may be used. The non-aqueous electrolyte may be a solution in which a lithium salt is dissolved in a non-aqueous solvent. Examples of the non-aqueous solvent include dimethyl ether, γ-butyl lactone, propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, and mixtures thereof.

[0048] Examples of lithium salts include LiCF ３ SO ３ , LiClO ４ , LiBF ４, LiPF ６ , LiRaSO ３ (Ra is a fluorinated alkyl group having 1 to 4 carbon atoms), LiFSO ３ , LiN(SO ２ Rb)(SO ２ Rc) (Rb and Rc each independently represent a fluorinated alkyl group having 1 to 4 carbon atoms), LiN(FSO ２ ) ２ , LiPO ２ F ２ The total concentration of the lithium salt contained in the non-aqueous electrolyte may be in the range of 0.2 to 2.0 mol / L, 0.3 to 1.5 mol / L, or 0.4 to 1.2 mol / L. The non-aqueous electrolyte may contain components other than the non-aqueous solvent and the lithium salt.

[0049] (Separator) The separator is not particularly limited, and separators used in known lithium primary batteries may be used. The separator may be a porous sheet made of an insulating material that is resistant to the internal environment of the lithium primary battery (B). Examples of the form of the separator include nonwoven fabrics and microporous membranes.

[0050] Examples of separator materials include polyolefin resins (such as polyethylene, polypropylene, and ethylene-propylene copolymers), polyphenylene sulfide, and polybutylene terephthalate. The separator thickness may be in the range of 5 μm to 100 μm (e.g., 20 μm to 50 μm). The separator thickness may be 50 μm or less (e.g., 30 μm or less) to facilitate the formation of a conductive path through the deposited metal element M. On the other hand, the separator thickness may be 20 μm or more to effectively prevent short circuits. At least a portion of the separators in the electrode group may be double-stacked. For example, the separator adjacent to the short-circuiting metal sheet may be double-stacked. By doubling up the separators, normal short circuits (which are different from short circuits intentionally generated during polarity reversal) can be suppressed. The outermost periphery of the electrode group may also be made of a separator.

[0051] In a cross section perpendicular to the central axis of the cylindrical battery case, the angle formed by the line segment connecting the center of the battery case to the outer circumferential edge of the positive electrode and the line segment connecting the central axis of the battery case to the outer circumferential edge of the negative electrode may be in the range of 120 to 240° (for example, in the range of 170 to 190°). This configuration makes it possible to reduce deviation in the diameter of the electrode group.

[0052] (Exterior Body) The exterior body is not particularly limited, and an exterior body used in a known cylindrical lithium primary battery may be used. The exterior body may include a battery case, a sealing plate, and a gasket. The battery case has a cylindrical shape with a bottom and functions as a negative electrode terminal. A metal case may be used as the battery case. Specifically, a cylindrical case with a bottom made of iron or stainless steel may be used as the battery case.

[0053] The gasket may be made of resin and / or rubber. The sealing plate functions as a positive electrode terminal. The sealing plate may include a safety valve that activates when the internal pressure of the primary battery (B) becomes high. The sealing plate may include a PTC thermistor, which is a thermal resistance element, or a thermal fuse as a safety element.

[0054] (Method for manufacturing lithium primary battery (B)) The method for manufacturing the lithium primary battery (B) is not limited. The lithium primary battery (B) may be manufactured using steps used in known manufacturing methods. The lithium primary battery (B) can be manufactured by housing predetermined components (such as an electrode group and a non-aqueous electrolyte) in an exterior body. The exterior body includes a battery case.

[0055] The negative electrode can be the same as the negative electrode described above. The positive electrode may be manufactured by the following method. First, a positive electrode mixture (or positive electrode mixture slurry) containing components of the positive electrode mixture layer is prepared. Next, the positive electrode mixture (or positive electrode mixture slurry) is applied to or filled into a positive electrode current collector, and then dried and rolled to obtain a positive electrode. A positive electrode lead is connected to the positive electrode as needed.

[0056] The electrode assembly may be formed by the following method. First, a short-circuit metal sheet is attached onto the negative electrode. Next, if necessary, a negative electrode lead is connected to the negative electrode and / or the short-circuit metal sheet. Also, if necessary, a positive electrode lead is connected to the positive electrode. Next, the positive electrode, negative electrode, and separator are wound together to form a wound electrode assembly.

[0057] Next, the formed electrode group and nonaqueous electrolyte are housed in a battery case, and the opening of the battery case is sealed with a sealing plate and a gasket. At this time, the positive electrode and the sealing plate (positive electrode terminal) are electrically connected via a predetermined member (e.g., a positive electrode lead). Also, the negative electrode and the battery case (negative electrode terminal) are electrically connected via a predetermined member (e.g., a short-circuiting metal sheet and / or a negative electrode lead). In this way, a primary battery (B) is produced.

[0058] (Lithium Primary Battery (B1)) In another aspect, the present disclosure provides a lithium primary battery (B1). The lithium primary battery (B1) is a cylindrical lithium primary battery and includes an electrode assembly in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, a short-circuiting metal sheet disposed on the negative electrode and electrically connected to the negative electrode, and a battery case that houses the electrode assembly and functions as a negative electrode terminal. The positive electrode includes a positive electrode current collector having a plurality of through-holes and a positive electrode mixture layer disposed on the positive electrode current collector. The negative electrode includes a lithium-containing metal sheet. The lithium-containing metal sheet, the short-circuiting metal sheet, and the battery case are electrically connected. The electrode assembly has a short-circuit induction part. In the short-circuit induction part, the lithium-containing metal sheet, the short-circuiting metal sheet, the separator, the positive electrode, the separator, and the separator are arranged in this order. These components may be arranged in this order from the center to the outer periphery of the electrode assembly, or from the outer periphery to the center of the electrode assembly.

[0059] The components of the lithium primary battery (B1) can be the same as those described for the lithium primary battery (B), and therefore redundant description will be omitted. The area of ​​the short circuit induction portion of the lithium primary battery (B1) corresponds to the area S of the short circuit induction region described above.

[0060] Examples of embodiments according to the present disclosure will be specifically described below with reference to the drawings. The embodiments described below can be modified based on the above description. The matters described below may also be applied to the above embodiments. In addition, in the embodiments described below, matters that are not essential for the battery according to the present disclosure may be omitted.

[0061] (Embodiment 1) A partially exploded cross-sectional view of an example of a lithium primary battery (B) is shown in Figure 1. The cylindrical lithium primary battery 100 shown in Figure 1 includes an electrode group 10, a non-aqueous electrolyte (not shown), a positive electrode lead 4, a negative electrode lead 5, an upper insulating plate 6, a lower insulating plate 7, a sealing plate 8, a battery case 9, and a gasket 11. The lithium primary battery 100 further includes a short-circuiting metal sheet (not shown) disposed within the electrode group 10.

[0062] The electrode group 10 is formed by winding a positive electrode 1, a negative electrode 2, and a separator 3. The positive electrode 1 includes a positive electrode current collector 1a and a positive electrode mixture layer held by the positive electrode current collector 1a. The electrode group 10 and the non-aqueous electrolyte are disposed in a battery case 9. The battery case 9 has a cylindrical shape with a bottom. The opening of the battery case 9 is sealed with a sealing plate 8 and a gasket 11. The sealing plate 8, the gasket 11, and the battery case 9 constitute an exterior body.

[0063] The sealing plate 8 functions as a positive electrode terminal. The positive electrode 1 and the sealing plate 8 are electrically connected by the positive electrode lead 4. The battery case 9 functions as a negative electrode terminal. The negative electrode 2 and the battery case 9 are electrically connected by the negative electrode lead 5. As described above, the negative electrode lead 5 is not essential in the primary battery (B).

[0064] An example of a portion of the lithium primary battery 100 where a short-circuit metal sheet is disposed is shown in Figures 2 and 3. Figures 2 and 3 show cross sections perpendicular to the winding axis of the electrode group 10. Note that in cross-sectional views other than Figure 3, each component may be depicted as flat to facilitate understanding. However, within the electrode group 10, each component is usually curved.

[0065] Fig. 2 shows a cross section of a portion of the electrode group 10. Referring to Fig. 2, the electrode group 10 is formed by winding a positive electrode 1, a negative electrode 2, and a separator 3. A short-circuiting metal sheet 21 is disposed on the negative electrode 2. The negative electrode 2 and the short-circuiting metal sheet 21 are connected. In Fig. 2, side A may be the center side of the electrode group 10, and side B may be the outer periphery side of the electrode group 10. Alternatively, in Fig. 2, side A may be the outer periphery side of the electrode group 10, and side B may be the center side of the electrode group 10.

[0066] The positive electrode 1 includes a positive electrode current collector 1a and a positive electrode mixture layer 1b held by the positive electrode current collector 1a. The positive electrode current collector 1a has through holes, so the positive electrode mixture layers 1b disposed on both sides of the positive electrode current collector 1a are connected. The negative electrode 2 is a lithium-containing metal sheet. The negative electrode 2 (lithium-containing metal sheet), a short-circuiting metal sheet 21, and the battery case are electrically connected.

[0067] The positive electrode mixture layer 1b has a normal reaction region 1x and a reaction suppression region 1y. In FIG. 2, the reaction suppression region 1y is hatched differently from the other portions of the positive electrode mixture layer 1b. The positive electrode mixture layer 1b may include a region that is not classified as either the normal reaction region 1x or the reaction suppression region 1y. The normal reaction region 1x is a region where a lithium-containing metal sheet (negative electrode 2) that supplies lithium ions to the normal reaction region 1x during discharge is located opposite the surface (both surfaces) of the normal reaction region 1x. In other words, both surfaces of the normal reaction region 1x face the lithium-containing metal sheet via the separator 3.

[0068] The reaction-suppression region 1y has a first surface Sp1 and a second surface Sp2 opposite the first surface Sp1. The first surface Sp1 and the second surface Sp2 are each adjacent to the separator 3. That is, no other members are disposed between the first surface Sp1 and the separator 3, or between the second surface Sp2 and the separator.

[0069] In FIG. 2 , the adjacent portion 3a of the separator 3 adjacent to the first surface Sp1 is hatched differently from the other portions of the separator 3. The adjacent portion 3a has a first surface Ss1 on the first surface Sp1 side and a second surface Ss2 on the opposite side of the first surface Ss1. The second surface Ss2 is not adjacent to the lithium-containing metal sheet (negative electrode 2). From one perspective, the reaction suppression region 1y is a region where the lithium-containing metal sheet (negative electrode 2) that supplies lithium ions to the reaction suppression region 1y during discharge is not present at a position facing the first surface Sp1. From another perspective, the lithium-containing metal sheet is not present at a position facing the first surface Sp1 across the separator 3.

[0070] At least a portion of the second surface Sp2 is a short circuit inducing region 1z. The short circuit inducing region 1z faces the short circuit metal sheet 21 across the separator 3. The separator 3 allows ions in the non-aqueous electrolyte to pass through. Therefore, no member that blocks ion permeation exists on the line connecting the short circuit inducing region 1z and the short circuit metal sheet 21.

[0071] As shown in Fig. 2, an insulating tape 40 for preventing short circuits may be attached to the outer peripheral edge of the positive electrode 1 of the lithium primary battery (B) (the same applies to other examples described below). The insulating tape 40 may be attached to the positive electrode 1 so as to cover both sides of the outer peripheral edge of the positive electrode 1. The first surface Sp1 is in contact with the separator 3. The surface to which the insulating tape 40 is attached is not included in the first surface Sp1.

[0072] Fig. 3 is a schematic cross-sectional view of an example of a lithium primary battery 100 including the structure shown in Fig. 2. Note that Fig. 3 shows only a portion of the lithium primary battery 100, and the separator is not shown. The electrode group 10 shown in Fig. 3 is an example of the electrode group 10 shown in Fig. 2 in which side A is the center side of the electrode group 10. The direction perpendicular to the plane of the paper in Fig. 3 is the winding axis direction Dax.

[0073] In the reaction suppression region 1y, at least one surface of the positive electrode 1 does not face the lithium-containing metal sheet (negative electrode 2) across the separator. Therefore, the discharge reaction is suppressed in the reaction suppression region 1y. Therefore, a large amount of unreacted positive electrode active material that has not been consumed by the discharge reaction exists in the reaction suppression region 1y.

[0074] Consider the case where a lithium primary battery 100 in which the metal element M is copper is in a polarity inversion state due to overdischarge. In this case, all or most of the negative electrode 2 electrically connected to the battery case 9 is lost due to discharge. In the polarity inversion state (overdischarge state), copper in the short-circuiting metal sheet 21 is dissolved and precipitated on the positive electrode. Here, the positive electrode active material (e.g., MnO ２ ) has the property of adsorbing ions of the metal element M. In other words, it is believed that copper ions are preferentially adsorbed to the reaction inhibition region 1y of the positive electrode 1, where a large amount of unreacted positive electrode active material remains, and are reduced and precipitated in the reaction inhibition region 1y. When the precipitated copper grows, the short-circuit inducing region 1z and the short-circuiting metal sheet 21 are electrically connected by a conductive path (precipitated copper) passing through the inside of the separator 3. As a result, the sealing plate 8 (positive electrode terminal) and the battery case 9 (negative electrode terminal) are electrically connected via the positive electrode lead 4, the positive electrode 1, the conductive path formed by the precipitated copper, and the short-circuiting metal sheet 21 (or the short-circuiting metal sheet 21 and the negative electrode lead 5).

[0075] The deposited copper forms a conductive path, which reduces the internal resistance of the lithium primary battery 100 in a polarity reversal state. By making the internal resistance of the lithium primary battery 100 smaller than the resistance of the external device, heat generation in the lithium primary battery 100 in a polarity reversal state can be suppressed. Note that similar effects can be obtained with metal elements M other than copper.

[0076] (Additional Note) The above embodiment discloses the following techniques.

[0077] (Technology 1) A cylindrical lithium primary battery comprising: an electrode group in which a positive electrode and a negative electrode are wound with a separator interposed therebetween; a short-circuiting metal sheet disposed on the negative electrode and electrically connected to the negative electrode; and a battery case that houses the electrode group and functions as a negative electrode terminal; the positive electrode comprises a positive electrode current collector having a plurality of through holes, and a positive electrode mixture layer disposed on the positive electrode current collector; the negative electrode comprises a lithium-containing metal sheet; the lithium-containing metal sheet, the short-circuiting metal sheet, and the battery case are electrically connected; the short-circuiting metal sheet comprises at least one metal element M selected from the group consisting of copper, iron, titanium, nickel, and zinc; the positive electrode mixture layer has a reaction suppression region; and the reaction suppression region has a first surface Sp1 and a second surface Sp2 opposite to the first surface Sp1; the first surface Sp1 and the second surface Sp2 are each adjacent to the separator; a cylindrical lithium primary battery in which an adjacent portion of the separator adjacent to the first surface Sp1 has a first surface Ss1 on the first surface Sp1 side and a second surface Ss2 on the opposite side of the first surface Ss1, the second surface Ss2 is not adjacent to the lithium-containing metal sheet, at least a part of the second surface Sp2 is a short-circuit inducing region, and the short-circuit inducing region faces the short-circuiting metal sheet with the separator in between.

[0078] (Technology 2) The cylindrical lithium primary battery according to Technology 1, wherein the short-circuiting metal sheet is a copper sheet or a copper alloy sheet.

[0079] (Technology 3) The cylindrical lithium primary battery according to Technology 1 or 2, wherein the reaction suppression region is present in the outermost periphery of the positive electrode, and the short-circuiting metal sheet and the second surface Sp2 face each other across the separator over the entire circumferential direction of the second surface Sp2.

[0080] (Technology 4) The area of ​​the short circuit induction region is 4 mm ２ Above 1200mm ２ The cylindrical lithium primary battery according to any one of the following techniques 1 to 3.

[0081] (Technology 5) The cylindrical lithium primary battery according to any one of Technologies 1 to 4, wherein the width of the portion of the short-circuiting metal sheet facing the second surface Sp2 across the separator is 3 mm or more.

[0082] (Technology 6) The cylindrical lithium primary battery according to any one of Technologies 1 to 5, wherein the reaction suppression region is present at the innermost periphery of the positive electrode, and the short-circuit metal sheet is present on the outer periphery of the reaction suppression region.

[0083] (Technology 7) The cylindrical lithium primary battery according to any one of Technologies 1 to 6, further comprising a negative electrode lead that electrically connects the short-circuiting metal sheet and the lithium-containing metal sheet to the battery case, and the negative electrode lead is laminated on the short-circuiting metal sheet and the lithium-containing metal sheet.

[0084] The present disclosure will be specifically described below based on examples, but the present disclosure is not limited to the following examples. In these examples, a plurality of cylindrical lithium primary batteries having different laminated portion configurations were fabricated and evaluated.

[0085] (Fabrication of Battery A1) Battery A1 (lithium primary battery) was fabricated in the following manner.

[0086] (1) Preparation of Positive Electrode: A positive electrode mixture was prepared by mixing electrolytic manganese dioxide (positive electrode active material), ketjen black (conductive material), and polytetrafluoroethylene (binder) in a predetermined ratio. The positive electrode mixture was then applied to a positive electrode current collector (thickness: 0.1 mm), dried, and rolled to a thickness of 0.5 mm. Stainless steel (SUS444) expanded metal was used for the positive electrode current collector. In this way, a positive electrode was formed, including a positive electrode current collector and a positive electrode mixture layer filled in the positive electrode current collector. The resulting positive electrode was cut to a predetermined size (width: 26 mm, length: 255 mm) to obtain a positive electrode for Battery A1. A SUS444 positive electrode lead was connected to the resulting positive electrode. Insulating tape was attached to the outer periphery of the positive electrode to prevent short circuits (the same applies to the batteries described below). Specifically, insulating tape was attached to cover both sides of the outer periphery.

[0087] (2) Preparation of Negative Electrode A negative electrode 2 was obtained by cutting a lithium metal foil (thickness: 300 μm) to a predetermined size (width: 24 mm, length: 250 mm). Copper foil (short-circuiting metal sheet 21) was crimped (connected) near the outer peripheral edge 2 e of the negative electrode 2. FIG. 4A is a schematic top view of the negative electrode with the copper foil laminated thereon. FIG. 4A shows the circumferential direction Dc and the winding axis direction Dax when the electrode group was formed (the circumferential direction Dc and the winding axis direction Dax may also be shown in the following figures). The short-circuiting metal sheet 21 had a lead portion 21 a. A portion of the lead portion 21 a protruded outside the negative electrode 2. The width of the lead portion 21 a was 5 mm. The width of the portion 21 b extending from the lead portion 21 a in the circumferential direction Dc was 2 mm. The length of the 2 mm-wide portion 21 b was 15 mm.

[0088] (3) Preparation of non-aqueous electrolyte: A non-aqueous solvent was prepared by mixing propylene carbonate (PC) and 1,2-dimethoxyethane (DME) in a volume ratio of 4:6. LiCF was added to this non-aqueous solvent to a concentration of 0.7 mol / L. ３ SO ３ A non-aqueous electrolyte was prepared by dissolving the above in water.

[0089] (4) Battery Assembly: A wound electrode group was formed by winding the positive electrode, negative electrode, and separator. The outermost periphery of the electrode group was composed of a separator (the same applies to the batteries fabricated below). A polypropylene microporous membrane (thickness: 25 μm) was used as the separator. The electrode group was formed so that the end of the negative electrode 2 was located as shown in FIG. 4A when viewed from the center of the electrode group. Specifically, the electrode group was formed so that the size of the short-circuit inducing region 1z was 2 mm (in the direction of the winding axis Dax) × 1 mm (in the circumferential direction Dc). A cross-sectional view of the vicinity of the short-circuit inducing region 1z is schematically shown in FIG. 4B. In the cross-sectional view of FIG. 4B, adjacent components are shown separated, but in an actual battery, adjacent components are in contact with each other (the same applies to the cross-sectional views below). The reaction suppression region 1y of the electrode group of Battery A1 is located at the outermost periphery of the positive electrode 1. The short-circuiting metal sheet 21 and the second surface Sp2 face each other across the separator 3 only in a part of the circumferential direction of the second surface Sp2.

[0090] Next, the electrode group and the nonaqueous electrolyte were placed in a battery case (made of iron). The opening of the battery case was then sealed using a sealing plate and a gasket. During battery assembly, the negative electrode lead was welded to the battery case, and the positive electrode lead was welded to the sealing plate. Battery A1 was thus obtained.

[0091] (Battery A2) A lithium primary battery (Battery A2) was fabricated in the same manner and under the same conditions as Battery A1, except that the material and shape of the short-circuiting metal sheet 21, the length of the positive electrode, and the position of the constituent members of the electrode group were changed. The length of the positive electrode was 241 mm. Copper foil was used for the short-circuiting metal sheet 21.

[0092] A top view of the negative electrode laminated with copper foil is shown in Figure 5A. The lead portion 21a of the short-circuiting metal sheet 21 of Battery A2 had a width of 5 mm. The portion 21b extending from the lead portion 21a in the circumferential direction Dc had a width of 2 mm. The length of the 2-mm-wide portion 21b was 30 mm.

[0093] In Battery A2, the electrode group was formed so that the size of the short-circuit inducing region 1z was 2 mm (in the winding axis direction Dax) × 1 mm (in the circumferential direction Dc). A cross-sectional view of the vicinity of the short-circuit inducing region 1z of Battery A2 is shown in FIG. 5B. The reaction suppression region 1y of the positive electrode 1 of Battery A2 was located at the outermost periphery of the positive electrode 1. The short-circuiting metal sheet 21 and the second surface Sp2 faced each other across the separator 3 over the entire circumferential direction of the second surface Sp2 of the positive electrode 1 (this also applies to Batteries A3 to A6 and A8 to A13 described below).

[0094] (Battery A3) A lithium primary battery (Battery A3) was fabricated using the same method and conditions as Battery A2, except that the size of the short circuit induction region 1z and the length of the positive electrode were changed. In Battery A3, the electrode group was formed so that the size of the short circuit induction region 1z was 2 mm (in the winding axis direction Dax) × 2 mm (in the circumferential direction Dc). The length of the positive electrode of Battery A3 was 242 mm.

[0095] (Battery A4) A lithium primary battery (Battery A4) was fabricated in the same manner and under the same conditions as those for fabricating Battery A2, except that the shape of the short-circuiting metal sheet 21, the size of the short-circuit inducing region 1z, and the length of the positive electrode were changed.

[0096] The short-circuit metal sheet 21 of Battery A4 had the same shape as the short-circuit metal sheet 21 of Battery A2, except that the width of the portion 21b was 3 mm. In Battery A4, the electrode group was formed so that the size of the short-circuit induction region 1z was 3 mm (in the winding axis direction Dax) × 10 mm (in the circumferential direction Dc). The length of the positive electrode of Battery A4 was 255 mm.

[0097] (Battery A5) A lithium primary battery (Battery A5) was fabricated in the same manner and under the same conditions as those for fabricating Battery A2, except that the shape of the short-circuiting metal sheet 21, the size of the short-circuit inducing region 1z, and the length of the positive electrode were changed, and a negative electrode lead was included.

[0098] FIG. 6 shows a top view of the negative electrode 2 on which copper foil (short-circuit metal sheet 21) is laminated. The short-circuit metal sheet 21 of Battery A5 has a strip-like shape with a width of 3 mm and a length of 25 mm. The short-circuit metal sheet 21 is arranged so that its longitudinal direction is generally parallel to the circumferential direction Dc. The negative electrode lead 5 is arranged on and connected to the negative electrode 2 and the short-circuit metal sheet 21. A nickel lead was used as the negative electrode lead 5. Note that the nickel lead was arranged in a position that was not opposite the reaction suppression region across the separator. In other words, the nickel lead does not function as a short-circuit metal sheet. This is also true for other batteries that use nickel leads, except for Battery A7.

[0099] In Battery A5, the electrode group was formed so that the size of the short-circuit inducing region 1z was 3 mm (in the winding axis direction Dax) × 10 mm (in the circumferential direction Dc). The length of the positive electrode of Battery A5 was 255 mm.

[0100] (Battery A6) A lithium primary battery (Battery A6) was fabricated in the same manner and under the same conditions as those for fabricating Battery A5, except that the shape and arrangement of the short-circuiting metal sheet 21, the size of the short-circuit inducing region 1z, and the length of the positive electrode were changed.

[0101] FIG. 7 shows a top view of a negative electrode on which copper foil (short-circuit metal sheet 21) is laminated. The short-circuit metal sheet 21 of Battery A6 has a strip shape with a width of 5 mm and a length of 70 mm. The short-circuit metal sheet 21 is arranged so that its longitudinal direction is inclined with respect to the circumferential direction Dc. The short-circuit metal sheet 21 of Battery A6 is wound around the circumferential direction Dc for one or more turns. In Battery A6, the electrode group was formed so that the size of the short-circuit inducing region 1z was 5 mm x 60 mm. The area of ​​the short-circuit inducing region 1z was 270 mm. ２ It was.

[0102] (Battery A7) In Battery A7, the reaction suppression region 1y was positioned toward the center of the wound electrode assembly. The size of Battery A7 was 230 mm. A lithium primary battery (Battery A7) was fabricated using the same method and conditions as Battery A5, except for these factors.

[0103] FIG. 8A shows a top view of a negative electrode laminated with copper foil. The short-circuiting metal sheet 21 of Battery A7 has a strip shape with a width of 5 mm and a length of 25 mm. The short-circuiting metal sheet 21 is arranged so that its longitudinal direction is generally parallel to the circumferential direction Dc. The short-circuiting metal sheet 21 is arranged near the end 2c of the negative electrode 2 toward the winding center. In Battery A7, the electrode group was formed so that the size of the short-circuit inducing region 1z was 5 mm (in the winding axis direction Dax) × 15 mm (in the circumferential direction Dc). FIG. 8B is a schematic cross-sectional view of the vicinity of the short-circuit inducing region 1z of Battery A2. The negative electrode 2 is not present in the region closer to the center than the positive electrode 1 shown in FIG. 8B. Therefore, the portion of the positive electrode 1 shown in FIG. 8B is the reaction suppression region 1y.

[0104] (Battery A8) A lithium primary battery (Battery A8) was produced in the same manner and under the same conditions as those for producing Battery A5, except that the shape of the short-circuiting metal sheet 21, the size of the short-circuit inducing region 1z, and the length of the positive electrode were changed.

[0105] FIG. 9 shows a top view of the negative electrode 2 on which copper foil (short-circuit metal sheet 21) was laminated. The length of the positive electrode 1 of Battery A8 was 280 mm. The short-circuit metal sheet 21 of Battery A8 had a strip shape with a width of 24 mm and a length of 62.5 mm. The short-circuit metal sheet 21 was arranged so that both ends of the short-circuit metal sheet 21 in the width direction coincided with both ends of the negative electrode 2 in the width direction. The short-circuit metal sheet 21 of Battery A8 was wound one or more times in the circumferential direction Dc. In Battery A8, the electrode group was formed so that the size of the short-circuit induction region 1z was 24 mm (in the winding axis direction Dax) × 50 mm (in the circumferential direction Dc). In Battery A8, the positive electrode 1 was arranged outside most of the outermost periphery of the negative electrode 2.

[0106] (Battery A9) A lithium primary battery (Battery A9) was produced in the same manner and under the same conditions as those for producing Battery A5, except that the shape of the short-circuiting metal sheet 21, the size of the short-circuit inducing region 1z, and the length of the positive electrode were changed.

[0107] FIG. 10 shows a top view of the negative electrode 2 on which copper foil (short-circuit metal sheet 21) was laminated. The length of the positive electrode 1 of Battery A9 was 290 mm. The short-circuit metal sheet 21 of Battery A9 had a strip shape with a width of 5 mm and a length of 80 mm. The short-circuit metal sheet 21 was arranged so that its longitudinal direction was approximately parallel to the circumferential direction Dc. The short-circuit metal sheet 21 of Battery A9 was wound in the circumferential direction Dc for one or more turns. In Battery A9, the electrode group was formed so that the size of the short-circuit induction region 1z was 5 mm (winding axis direction Dax) × 50 mm (circumferential direction Dc). In Battery A9, the positive electrode 1 was arranged outside the outermost periphery of the negative electrode 2.

[0108] (Battery A10) In Battery A10, a notch 2x was formed in a portion of the negative electrode 2. FIG. 11 shows a schematic top view of the negative electrode 2 on which copper foil (short-circuit metal sheet 21) was laminated. The short-circuit metal sheet 21 was arranged so that the notch 2x and a portion of the short-circuit metal sheet 21 overlapped in the radial direction of the electrode group. Specifically, the lithium-containing metal sheet / short-circuit metal sheet 21 / separator / positive electrode / separator / notch 2x were arranged so that they overlapped at the notch 2x portion. The notch 2x measured 5 mm (in the winding axis direction Dax) x 3 mm (in the circumferential direction Dc). The short-circuit metal sheet 21 was a strip of copper foil measuring 3 mm wide and 35 mm long. The positive electrode had a length of 230 mm. The short-circuit metal sheet 21 was arranged so that its longitudinal direction was approximately parallel to the circumferential direction Dc.

[0109] The portion of the positive electrode 1 facing the notch 2x across the separator serves as the reaction suppression region. For Battery A10, an electrode assembly was formed so that the short-circuit induction region 1z measured 3 mm (in the winding axis direction Dax) × 3 mm (in the circumferential direction Dc). A lithium primary battery (Battery A10) was fabricated using the same method and conditions as those for Battery A1, except for using the formed electrode assembly.

[0110] (Battery A11) A lithium primary battery (Battery A11) was fabricated in the same manner and under the same conditions as those for fabricating Battery A1, except that the material of the short-circuiting metal sheet 21 was changed to iron.

[0111] (Battery A12) A lithium primary battery (battery A12) was fabricated in the same manner and under the same conditions as those for the battery A1, except that the material of the short-circuiting metal sheet 21 was changed to nickel.

[0112] (Battery A13) A lithium primary battery (Battery A13) was fabricated in the same manner and under the same conditions as those for Battery A1, except that the material of the short-circuiting metal sheet 21 was changed to titanium.

[0113] (Battery C1) In Battery C1, the components and their arrangement were changed to form an electrode group. A top view of the negative electrode 2 in Battery C1, on which copper foil (short-circuit metal sheet 21) was laminated, is shown schematically in FIG. 12A. The copper foil used in Batteries C1 to C3 does not induce short circuits and is therefore not a short-circuit metal sheet, but for convenience, it is treated as a short-circuit metal sheet. A cross-sectional view of the vicinity of the short-circuit metal sheet 21 is shown schematically in FIG. 12B. The electrode group of Battery C1 does not have a short-circuit inducing region. A lithium primary battery (Battery C1) was fabricated using the same method and conditions as Battery A1, except that the formed electrode group was used.

[0114] (Battery C2) In Battery C2, the components and their arrangement were changed to form an electrode group. FIG. 13A shows a schematic top view of the negative electrode 2 in Battery C2, on which copper foil (short-circuit metal sheet 21) is laminated. FIG. 13B shows a schematic cross-sectional view of the vicinity of the short-circuit metal sheet 21. The electrode group of Battery C2 does not have a reaction-suppression region or a short-circuit-inducing region. A lithium primary battery (Battery C2) was fabricated using the same method and conditions as Battery A1, except that the formed electrode group was used.

[0115] (Battery C3) In Battery C3, the components and their arrangement were changed to form an electrode group. FIG. 14A is a schematic top view of the negative electrode 2 in Battery C3, on which copper foil (short-circuit metal sheet 21) is laminated. FIG. 14B is a schematic cross-sectional view of the vicinity of the short-circuit metal sheet 21. The electrode group of Battery C3 does not have a short-circuit inducing region. A lithium primary battery (Battery C3) was fabricated using the same method and conditions as Battery A1, except that the formed electrode group was used.

[0116] The fabricated batteries were evaluated as follows.

[0117] (1) Internal Resistance of Battery at the End of Discharge A resistance of 1 kΩ was connected to the battery, and the battery was discharged until the battery voltage reached 2 V. Thereafter, the internal resistance IR of the battery was measured.

[0118] (2) Measurement of maximum side temperature in overdischarge test: A battery overdischarge test was conducted under the following conditions. Specifically, the overdischarge test was conducted using the circuit shown in FIG. 15 . The battery 201 to be tested was previously discharged until the depth of discharge (DOD) reached 100%. Three lithium primary batteries 202 connected in series were used as the power source for bringing the battery 201 to be tested into an overdischarge state (polarity reversal state). The battery 201 was connected in series with the lithium primary battery 202 for discharging. An 8.2 Ω resistor was used as the external load 203.

[0119] The overdischarge test caused a rise in the temperature of the battery 201. The temperature change on the side surface of the battery 201 during the overdischarge test was monitored. Then, the maximum temperature Tmax on the side surface of the battery 201 was determined.

[0120] Table 1 shows some of the manufacturing conditions and evaluation results for each battery. In Table 1, the area S indicates the area of ​​the short-circuit inducing region. The internal resistance IR at the end of discharge is preferably low. The lower the maximum temperature Tmax, the smaller the temperature rise of the battery in an overdischarge state (polarity reversal state).

[0121]

[0122] Batteries A1 to A13 are lithium primary batteries (B) according to this embodiment. Batteries C1 to C3 are comparative examples. As shown in Table 1, the maximum temperatures Tmax of batteries A1 to A13 having a short-circuit inducing region were significantly lower than the maximum temperatures Tmax of batteries C1 to C3 of the comparative examples. ２ When the temperature was above 100°C, the maximum temperature Tmax was particularly low. The internal resistance of Battery A2 was lower than that of Battery A1. This is thought to be because Battery A2 was able to prevent the lithium metal foil from breaking at the end of discharge. By using copper as the material for the short-circuit metal sheet, the internal resistance and maximum temperature Tmax could be particularly low.

[0123] The present disclosure can be used for cylindrical lithium primary batteries.

[0124] 1: Positive electrode 1a: Positive electrode current collector 1b: Positive electrode mixture layer 1x: Normal reaction region 1y: Reaction suppression region 1z: Short-circuit inducing region 2: Negative electrode 2x: Notch 3: Separator 3a: Adjacent portion 5: Negative electrode lead 9: Battery case 10: Electrode group 21: Short-circuit metal sheet 100: Lithium primary battery

Claims

1. A cylindrical lithium primary battery comprising: an electrode group in which a positive electrode and a negative electrode are wound with a separator interposed therebetween; a short-circuiting metal sheet disposed on the negative electrode and electrically connected to the negative electrode; and a battery case that houses the electrode group and functions as a negative electrode terminal, wherein the positive electrode comprises a positive electrode current collector having a plurality of through holes and a positive electrode mixture layer disposed on the positive electrode current collector, the negative electrode comprises a lithium-containing metal sheet, wherein the lithium-containing metal sheet, the short-circuiting metal sheet, and the battery case are electrically connected, and the short-circuiting metal sheet comprises at least one metal element M selected from the group consisting of copper, iron, titanium, nickel, and zinc, the positive electrode mixture layer has a reaction suppression region, and the reaction suppression region has a first surface Sp1 and a second surface Sp2 opposite to the first surface Sp1, and the first surface Sp1 and the second surface Sp2 are each adjacent to the separator, a cylindrical lithium primary battery in which an adjacent portion of the separator adjacent to the first surface Sp1 has a first surface Ss1 on the first surface Sp1 side and a second surface Ss2 on the opposite side of the first surface Ss1, the second surface Ss2 is not adjacent to the lithium-containing metal sheet, at least a part of the second surface Sp2 is a short-circuit inducing region, and the short-circuit inducing region faces the short-circuiting metal sheet with the separator in between.

2. The cylindrical lithium primary battery according to claim 1, wherein the short-circuiting metal sheet is a copper sheet or a copper alloy sheet.

3. The cylindrical lithium primary battery according to claim 1 or 2, wherein the reaction suppression region is present at the outermost periphery of the positive electrode, and the short-circuiting metal sheet and the second surface Sp2 face each other across the separator over the entire circumferential direction of the second surface Sp2.

4. The area of ​​the short circuit induction area is 4 mm ２ Above 1200mm ２ 3. The cylindrical lithium primary battery according to claim 1, wherein:

5. The cylindrical lithium primary battery according to claim 1 or 2, wherein the width of the portion of the short-circuiting metal sheet facing the second surface Sp2 across the separator is 3 mm or more.

6. The cylindrical lithium primary battery according to claim 1 or 2, wherein the reaction suppression region is present at the innermost periphery of the positive electrode, and the short-circuiting metal sheet is present on the outer periphery of the reaction suppression region.

7. The cylindrical lithium primary battery according to claim 1 or 2, further comprising a negative electrode lead that electrically connects the short-circuiting metal sheet and the lithium-containing metal sheet to the battery case, and the negative electrode lead is laminated on the short-circuiting metal sheet and the lithium-containing metal sheet.

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