Cylindrical lithium primary battery

Abstract

A disclosed cylindrical lithium primary battery (100) includes: an electrode group (10) in which a positive electrode (1), a negative electrode (2), and a separator (3) are wound; a short-circuit metal sheet (21) disposed on the negative electrode (1); and a battery case that accommodates the electrode group (10) and functions as a negative electrode terminal. The positive electrode (1) 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 positive electrode has a current collector exposed part (1c) where a part of the positive electrode current collector is exposed. The negative electrode (2) includes a lithium-containing metal sheet. The short-circuit metal sheet (21) contains at least one metal element M selected from the group consisting of copper, iron, nickel, and zinc. At least a part of the short-circuit metal sheet (21) and at least a part of the current collector exposed part (1c) face each other across the separator (3). The short-circuit metal sheet (21) is electrically connected to the battery case not through the lithium-containing metal sheet.

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 cylindrical axis extension direction of the battery can is the vertical direction, the electrode body has the vertical direction as a winding axis, and is wound so that the negative electrode is disposed at the outermost periphery with the winding axis as the start of winding, 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 facing the inner surface of the positive electrode on the winding end side."

[0004] Claim 1 of Patent Document 2 (JP 2015-60825 A) describes "a nonaqueous electrolyte battery comprising: a positive electrode; a negative electrode current collector made of aluminum or an aluminum alloy; a negative electrode including a negative electrode active material-containing layer formed on the negative electrode current collector; a separator disposed between the positive electrode and the negative electrode; an over-discharge control member electrically connected to the negative electrode current collector and made of copper or a copper alloy; and a nonaqueous electrolyte."

[0005] Claim 1 of Patent Document 3 (JP 2018-56075 A) describes an electrode assembly including 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, wherein the positive electrode and the negative electrode are wound together with the separator interposed therebetween to form a columnar electrode assembly in which the outermost periphery of the negative electrode is disposed outside the outermost periphery of the positive electrode, and the negative electrode contains metallic lithium or a lithium alloy, and the negative electrode contains copper. the copper-based metal foil is attached to the outer surface or inner surface of the negative electrode, the copper-based metal foil extends from a portion facing the winding end end of the positive electrode or from a first position on the outer peripheral side of the facing portion, the copper-based metal foil is wound around the electrode group one or more times from the first position, a tab lead is electrically connected to at least one of the negative electrode and the copper-based metal foil, and the tab lead is electrically connected to the metal case.

[0006] JP 2016-122592 A JP 2015-60825 A JP 2018-56075 A

[0007] Lithium primary batteries may experience polarity reversal due to overdischarge during use. When polarity reversal occurs, the battery temperature may rise. If the battery temperature rises, the safety valve may activate, potentially causing non-aqueous electrolyte to leak to the outside of the battery. Therefore, there is a demand for a lithium primary battery that exhibits a small temperature rise even when polarity reversal occurs. One of the objectives of the present disclosure is to provide a cylindrical lithium primary battery that exhibits a small temperature rise even when polarity reversal occurs.

[0008] One aspect of the present disclosure relates to a cylindrical lithium primary battery including: an electrode group in which a positive electrode, a negative electrode, and a separator are wound; a short-circuiting metal sheet arranged on the negative electrode; and a battery case that houses the electrode group and functions as a negative electrode terminal, wherein the positive electrode includes a positive electrode current collector having a plurality of through holes and a positive electrode mixture layer arranged on the positive electrode current collector, the positive electrode has a current collector exposed portion where a portion of the positive electrode current collector is exposed, the negative electrode includes a lithium-containing metal sheet, the short-circuiting metal sheet includes at least one metal element M selected from the group consisting of copper, iron, nickel, and zinc, at least a portion of the short-circuiting metal sheet and at least a portion of the current collector exposed portion face each other with the separator interposed therebetween, and the short-circuiting metal sheet is electrically connected to the battery case without the lithium-containing metal sheet interposed therebetween.

[0009] Another aspect of the present disclosure relates to a cylindrical lithium primary battery including: an electrode group in which a positive electrode, a negative electrode, and a separator are wound; a short-circuiting metal sheet arranged on the negative electrode; and a battery case that houses the electrode group and functions as a negative electrode terminal, wherein the positive electrode includes a positive electrode current collector having a plurality of through holes and a positive electrode mixture layer arranged on the positive electrode current collector, the positive electrode has a current collector exposed portion where a portion of the positive electrode current collector is exposed, the negative electrode includes a lithium-containing metal sheet, the short-circuiting metal sheet includes at least one metal element M selected from the group consisting of copper, iron, nickel, and zinc, at least a portion of the short-circuiting metal sheet and at least a portion of the current collector exposed portion face each other with the separator interposed therebetween, and the short-circuiting metal sheet and the battery case are electrically connected in a state of polarity reversal due to discharge.

[0010] According to the present disclosure, a cylindrical lithium primary battery is obtained that exhibits a small temperature rise even when undergoing a polarity reversal. The novel features of the present invention are set forth in the appended claims, but the present invention, both in terms of structure and content, together with other objects and features of the present invention, will be better understood from the following detailed description taken in conjunction with the drawings.

[0011] FIG. 1 is a partially exploded cross-sectional view schematically showing an example of a lithium primary battery of Embodiment 1. FIG. 2A is a cross-sectional view schematically showing a part of an example of a lithium primary battery of Embodiment 1. FIG. 2B is a top view schematically showing a part of an example of a lithium primary battery of Embodiment 1. FIG. 2C is a cross-sectional view schematically showing a part of an example of a lithium primary battery of Embodiment 1. FIG. 2D is a top view schematically showing a part of an example of a lithium primary battery of Embodiment 1. FIG. 3 is a cross-sectional view schematically showing a part of an example of a lithium primary battery of Embodiment 1. FIG. 4A is a cross-sectional view schematically showing a part of a lithium primary battery prepared in an Example. FIG. 4B is a top view schematically showing a part of a lithium primary battery prepared in an Example. FIG. 4C is a cross-sectional view schematically showing a part of a lithium primary battery prepared in an Example. FIG. 4D is a top view schematically showing a part of a lithium primary battery prepared in an Example. FIG. 4E is a cross-sectional view schematically showing a part of a lithium primary battery prepared in an Example. Fig. 4F is a cross-sectional view schematically showing a part of a lithium primary battery fabricated in an example. Fig. 4G is a cross-sectional view schematically showing a part of a lithium primary battery fabricated in an example. Fig. 4H is a cross-sectional view schematically showing a part of a lithium primary battery fabricated in an example. Fig. 4I is a cross-sectional view schematically showing a part of a lithium primary battery fabricated in an example. Fig. 5 is a view schematically showing an evaluation method used in the examples.

[0012] 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.

[0013] The first and second cylindrical lithium primary batteries according to this embodiment will be described below. The first cylindrical lithium primary battery may be referred to below as a "lithium primary battery (B1)" or a "primary battery (B1)." The second cylindrical lithium primary battery may be referred to below as a "lithium primary battery (B2)" or a "primary battery (B2)." The first cylindrical lithium primary battery and the second cylindrical lithium primary battery may be collectively referred to as a "lithium primary battery (B)" or a "primary battery (B)." At least some embodiments of the primary battery (B1) and the primary battery (B2) overlap. At least some embodiments of the primary battery (B1) can be considered as the primary battery (B2).

[0014] (Lithium Primary Battery (B1)) The lithium primary battery (B1) (first cylindrical lithium primary battery) includes an electrode assembly in which a positive electrode, a negative electrode, and a separator are wound together, a short-circuiting metal sheet arranged on 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 arranged on the positive electrode current collector. The positive electrode has a current collector exposed portion where a portion of the positive electrode current collector is exposed. The negative electrode includes a lithium-containing metal sheet. The short-circuiting metal sheet includes at least one metal element M selected from the group consisting of copper, iron, nickel, and zinc. At least a portion of the short-circuiting metal sheet and at least a portion of the current collector exposed portion face each other with the separator sandwiched between them. The short-circuiting metal sheet is electrically connected to the battery case without a lithium-containing metal sheet interposed therebetween.

[0015] (Lithium Primary Battery (B2)) The lithium primary battery (B2) (second cylindrical lithium primary battery) includes an electrode assembly in which a positive electrode, a negative electrode, and a separator are wound, a short-circuiting metal sheet arranged on 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 arranged on the positive electrode current collector. The positive electrode has a current collector exposed portion where a portion of the positive electrode current collector is exposed. The negative electrode includes a lithium-containing metal sheet. The short-circuiting metal sheet includes at least one metal element M selected from the group consisting of copper, iron, nickel, and zinc. At least a portion of the short-circuiting metal sheet and at least a portion of the current collector exposed portion face each other with the separator sandwiched between them. In a polarity inversion state due to discharge, the short-circuiting metal sheet and the battery case are electrically connected.

[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, has a lower capacity 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., even if the voltage exceeds the normal voltage range). This can cause battery X to enter 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] As will be described later, in the lithium primary battery (B), it is believed that when a polarity inversion state occurs, a metal element M precipitates on the exposed portion of the current collector of the positive electrode, and the positive electrode and the short-circuiting metal sheet are connected by a conductive path of the precipitated metal element M. As a result, the internal resistance of the battery in a polarity inversion state can be reduced, and a temperature rise in the battery can be suppressed.

[0018] When multiple batteries are connected in series, if some of the batteries are overdischarged and undergo polarity reversal, current continues to flow through the batteries in the polarity-reversed state. As a result, the batteries may heat up or the battery case may dissolve. According to the technology of the present disclosure, heat generation in the batteries can be suppressed, as described in the examples. Furthermore, according to the technology of the present disclosure, the formation of a conductive path by precipitation of the metal element M occurs preferentially over the dissolution of the battery case, thereby suppressing the dissolution of the battery case.

[0019] Examples of batteries in a state before polarity reversal include batteries that have not yet been used and batteries that have not been over-discharged.

[0020] In this specification, "electrically connected" means connected via a conductive member. Examples of conductive members 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.

[0021] In the primary battery (B1), the short-circuiting metal sheet is electrically connected to the battery case without the lithium-containing metal sheet. In other words, in the primary battery (B1), a conductive path exists between the short-circuiting metal sheet and the battery case without the lithium-containing metal sheet. In the primary battery (B2), the short-circuiting metal sheet may also be electrically connected to the battery case without the lithium-containing metal sheet. Alternatively, in the primary battery (B2), the short-circuiting metal sheet may be electrically connected to the battery case via the lithium-containing metal sheet. For example, the short-circuiting metal sheet may be electrically connected to the battery case via a portion of the lithium-containing metal sheet that remains when the state before the polarity inversion changes to the polarity inversion state.

[0022] In the primary battery (B2) in a polarity reversal state, examples of the manner in which the short-circuiting metal sheet and the battery case are electrically connected include the following (1) to (3): (1) The short-circuiting metal sheet is electrically connected to the battery case without the lithium-containing metal sheet; (2) The short-circuiting metal sheet is electrically connected to the battery case via a portion of the lithium-containing metal foil that is not lost by normal discharge (discharge that is not overdischarge); and (3) The short-circuiting metal sheet is electrically connected to the battery case via metal (e.g., lithium metal) deposited in the polarity reversal state.

[0023] At least one of the above aspects can be achieved by arranging a short-circuiting metal sheet so that it remains electrically connected to the battery case even when at least a portion of the lithium metal-containing sheet has been lost due to normal discharge.

[0024] The primary battery (B1) may further include a negative electrode lead electrically connected to the battery case. The electrode group may have a stacked portion in which a short-circuiting metal sheet is disposed. The lithium-containing metal sheet, the short-circuiting metal sheet, and the negative electrode lead may be stacked in the stacked portion. The negative electrode lead, the lithium-containing metal sheet, and the short-circuiting metal sheet may be electrically connected.

[0025] 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 may be 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.

[0026] A primary battery (B2X), an example of the primary battery (B2), will be described. The primary battery (B2X) further includes a negative electrode lead electrically connected to the battery case. The electrode group has a stacked portion in which a short-circuiting metal sheet is disposed. In the stacked portion before the polarity inversion state, the lithium-containing metal sheet, the negative electrode lead, the adhesive layer, and the short-circuiting metal sheet are stacked in this order. In the primary battery (B2X), in the polarity inversion state, some of the lithium eluted from the lithium-containing metal sheet precipitates on the short-circuiting metal sheet of the stacked portion, and the precipitated lithium electrically connects the short-circuiting metal sheet and the negative electrode lead. In this way, in the primary battery (B2X), the precipitated lithium connects the short-circuiting metal sheet and the negative electrode lead with low resistance. Furthermore, the precipitated metal element M connects the positive electrode and the short-circuiting metal sheet with low resistance. Therefore, the internal resistance of the battery in the polarity inversion state is reduced, thereby suppressing temperature rise in the battery.

[0027] In the primary battery (B2X), the short-circuiting metal sheet and the negative electrode lead do not need to be electrically connected in the stacked portion before the polarity inversion state. In the primary battery (B2X), the short-circuiting metal sheet and the negative electrode lead are electrically connected by lithium deposited in the polarity inversion state.

[0028] The primary battery (B2X) has a configuration in which the short-circuiting metal sheet and the negative electrode lead are electrically connected by lithium deposited in a polarity inversion state. Specifically, the electrical connection is facilitated by setting the shortest distance Dmin between the short-circuiting metal sheet and the negative electrode lead to a certain value or less. The shortest distance Dmin may be 10 μm or more, 20 μm or more, or 30 μm or more, or may be 100 μm or less, 80 μm or less, 50 μm or less, or 30 μm or less.

[0029] In the primary battery (B2X), the short-circuiting metal sheet and the negative electrode lead may be bonded with a non-conductive adhesive layer. A general adhesive layer that is resistant to the environment inside the battery can be used as the non-conductive adhesive layer. Examples of adhesive layers include adhesive tape. The minimum distance Dmin can be changed by adjusting the thickness of the adhesive layer.

[0030] The stacked portion of the primary battery (B1) and the stacked portion of the primary battery (B2) may include members other than the above-mentioned members (for example, an adhesive layer).

[0031] The negative electrode lead of the primary battery (B2X) may be the negative electrode lead exemplified for the negative electrode lead of the primary battery (B1).

[0032] (Short-circuiting metal sheet, lithium-containing metal sheet) In the primary battery (B1) and the primary battery (B2), the short-circuiting metal sheet may include a sheet of metal element M or a sheet of an alloy of metal element M. The short-circuiting metal sheet may include a copper sheet or a copper alloy sheet. The lithium-containing metal sheet may include a lithium sheet or a lithium alloy sheet. 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. 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. The copper alloy may have a copper content of 50 mass% or more (the same applies to sheets of other alloys). The lithium-containing metal sheet may be lithium foil (lithium metal foil) and / or lithium alloy foil. The metal element M may be copper. That is, the short-circuiting metal sheet may be a copper-containing metal sheet.

[0033] 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% by mass or more, 90% by mass or more, or 95% by mass or more. The short-circuiting metal sheet may be a sheet consisting of one type of metal element M, or may be a sheet consisting of multiple types of metal elements M. The short-circuiting metal sheet may be an iron sheet or an iron alloy sheet. The short-circuiting metal sheet may be a nickel sheet or a nickel alloy sheet. The short-circuiting metal sheet may be a zinc sheet or a zinc alloy sheet. Copper sheets and copper alloy sheets are preferred because of their excellent electrical and thermal conductivity.

[0034] 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 500 μm or less, or 100 μm or less. If the shorting metal sheet is too thin, it becomes more likely to tear, increasing the possibility that a short-circuit path cannot be maintained in a polarity reversal state. On the other hand, if the shorting metal sheet is too thick, there is a greater possibility that the shorting metal sheet and the positive electrode will short-circuit under normal conditions. In primary batteries (B) other than the primary battery (B2X) described below, the shorting metal sheet is connected to the lithium-containing metal sheet and functions as a current collector for the negative electrode during normal use. On the other hand, the shorting metal sheet of the primary battery (B2X) described below is not connected to the lithium-containing metal sheet during normal use and does not function as a current collector for the negative electrode.

[0035] The area of ​​the short-circuit metal sheet is 20 mm ２ or more, or 50 mm ２ It may be 500 mm or more. ２ or less than 1200 mm ２ or less. The short-circuiting metal sheet may be disposed on the negative electrode across the entire width of the negative electrode in the width direction, or may be disposed on only a portion of the width of the negative electrode in the width direction. From the viewpoint of preventing short circuits, it is preferable that the end of the short-circuiting metal sheet (the end in the winding axis direction Dax) does not protrude from the end of the negative electrode (the end in the winding axis direction Dax). In other words, the length of the short-circuiting metal sheet in the winding axis direction Dax is preferably equal to or less than the width of the negative electrode (the length in the winding axis direction Dax), but the present disclosure is not limited to such a form. When the short-circuiting metal sheet also serves as a negative electrode lead, the short-circuiting metal sheet protrudes outward from the end of the negative electrode.

[0036] In the primary battery (B1) and the primary battery (B2), the area S1 where the exposed positive electrode current collector and the short-circuit metal sheet face each other with the separator sandwiched therebetween is 1.0 mm ２ More than 3.0 mm ２ More than 6.0 mm ２ or more, or 12 mm ２ It may be 100 mm or more. ２Below, 72mm ２ Below, 12mm ２ or less than 6.0 mm ２ The area S1 may be 3.0 mm or less. ２ More than 72 mm ２ The area S1 may be 3.0 mm or less. ２ By setting the area S1 to 72 mm or more, a particularly high effect can be obtained. ２ By setting the above as follows, it is possible to suppress the decrease in discharge capacity.

[0037] The current collector exposed portion has a surface where the current collector is exposed. The area S1 takes into account only the area of ​​the exposed positive electrode current collector, and does not take into account the portion of the current collector exposed portion where the positive electrode mixture is present on the surface. The area of ​​the exposed positive electrode current collector can be determined by the following method. First, an image of the surface of the positive electrode is taken. Next, the area of ​​the positive electrode current collector is determined by analyzing the image (for example, by binarization). In this way, the area of ​​the exposed positive electrode current collector can be determined.

[0038] In the primary battery (B1) and the primary battery (B2), 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.

[0039] 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.

[0040] The lithium primary battery (B) includes an electrode group, a non-aqueous electrolyte, and an exterior housing that houses them. As described above, the lithium primary battery (B) further includes a short-circuiting metal sheet disposed on the negative electrode. At least a portion of the short-circuiting metal sheet is disposed inside the electrode group. Therefore, the short-circuiting metal sheet can also be considered as part of the electrode group. As described above, the lithium primary battery (B) may include a negative electrode lead. The short-circuiting metal sheet may function as a negative electrode lead. The short-circuiting metal sheet and the negative electrode lead have been described above, so redundant description will be omitted.

[0041] 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.

[0042] (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).

[0043] The positive electrode mixture layer contains a positive electrode active material and, if necessary, additives (such as a conductive material and a 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 (such as 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). 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] (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.

[0052] 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.

[0053] (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.

[0054] 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.

[0055] The method for forming the positive electrode current collector exposed portion is not limited. The positive electrode current collector exposed portion may be formed by not applying or filling a positive electrode mixture (or positive electrode mixture slurry) to a portion of the positive electrode current collector. For example, by applying a positive electrode mixture to only one side of the positive electrode current collector, it is possible to expose the positive electrode current collector on the other side. Alternatively, the positive electrode current collector exposed portion may be formed by scraping off a portion of the formed positive electrode mixture layer.

[0056] The electrode group may be formed by the following method. First, a short-circuiting metal sheet is placed on a lithium-containing metal sheet (negative electrode). Except for the primary battery (B2X), the lithium-containing metal sheet and the short-circuiting metal sheet are electrically connected. For example, the short-circuiting metal sheet may be pressure-bonded to the lithium-containing metal sheet. Alternatively, the short-circuiting metal sheet may be bonded to the lithium-containing metal sheet using a conductive adhesive layer (e.g., conductive tape). In the case of the primary battery (B2X), the short-circuiting metal sheet may be bonded to the lithium-containing metal sheet using an insulating adhesive layer (e.g., insulating tape). If necessary, a positive electrode lead is connected to the positive electrode, and a negative electrode lead is connected to the negative electrode. Next, a wound electrode group is formed by winding the positive electrode, the negative electrode, and the separator. At this time, the positions of the positive electrode and the negative electrode are adjusted so that at least a portion of the short-circuiting metal sheet and at least a portion of the exposed portion of the current collector face each other across the separator.

[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] Hereinafter, examples of embodiments according to the present disclosure will be specifically described with reference to the drawings. The embodiments described below can be modified based on the above description. Furthermore, the matters described below may be applied to the above embodiments. Furthermore, in the embodiments described below, matters that are not essential to the invention according to the present disclosure may be omitted.

[0059] (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.

[0060] 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.

[0061] 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. Note that the negative electrode lead 5 is not essential in the primary battery (B) except for the primary battery (B2X).

[0062] 2A to 2D show examples of the structure of some of the electrode groups 10 of the lithium primary battery 100. Note that in Figs. 2A to 2D, each member is depicted as flat to facilitate understanding. However, within the electrode group 10, each member is usually curved.

[0063] The electrode group 10 shown in FIG. 2A (cross-sectional view) includes a stacked positive electrode 1, a negative electrode 2 (lithium-containing metal sheet), and a separator 3. A negative electrode lead 5 and a short-circuiting metal sheet 21 are disposed on the negative electrode 2. In FIG. 2A , side A may be the outer peripheral side (side B is the inner peripheral side), or side A may be the inner peripheral side (side B is the outer peripheral side) (the same applies to the following figures). Note that the inner peripheral side refers to the inner peripheral side (center side) of the electrode group 10. The short-circuiting metal sheet 21 is electrically connected to the battery case 9 via the negative electrode lead 5, not via the negative electrode 2 (lithium-containing metal sheet).

[0064] 2A , 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 is attached to the positive electrode 1 so as to cover both sides of the outer peripheral edge of the positive electrode 1.

[0065] The portion 2x of the negative electrode 2 that does not face the positive electrode 1 across the separator 3 may remain when the battery changes from a normal discharge state to an overdischarge state (polarity inversion state). For example, when the capacity of the negative electrode is greater than that of the positive electrode, the portion 2x is likely to remain. The portion 2x that does not face the positive electrode 1 across the separator 3 also includes a portion facing a positive electrode covered with an insulating member (e.g., a nonporous insulating layer such as insulating tape) that suppresses charge / discharge reactions. In the primary battery (B), the portion 2x may remain when the battery changes from a normal discharge state to an overdischarge state.

[0066] The positive electrode 1 includes a normal positive electrode portion 1b where the positive electrode current collector is not exposed, and a current collector exposed portion 1c where the positive electrode current collector is exposed on the surface. For ease of understanding, the current collector exposed portion 1c is illustrated as a thick portion, but the positive electrode current collector may be exposed only on the surface of the positive electrode 1. That is, the current collector exposed portion 1c may be the current collector exposed surface. In the positive electrode 1 shown in FIG. 2A , one side of the positive electrode 1 is the current collector exposed portion 1c, and the other side does not have exposed current collector. At least a portion of the short-circuiting metal sheet 21 and at least a portion of the current collector exposed portion 1c face each other with the separator 3 interposed therebetween. No insulating member that does not allow metal ions to pass through is disposed between these portions.

[0067] 2A has a laminated portion 10x in which the negative electrode lead 5 is disposed. In the laminated portion 10x, a lithium-containing metal sheet (negative electrode 2), a short-circuiting metal sheet 21, and the negative electrode lead 5 are laminated.

[0068] An example of the arrangement of the negative electrode 2, negative electrode lead 5, and short-circuiting metal sheet 21 shown in FIG. 2A is shown in FIG. 2B (top view). The winding axis direction Dax is also shown in FIG. 2B. The portion shown in FIG. 2A is a portion near the outer peripheral end 2e of the negative electrode 2. The negative electrode 2, negative electrode lead 5, and short-circuiting metal sheet 21 are electrically connected. In the example shown in FIG. 2A, the two ends 21ae of the short-circuiting metal sheet 21 do not protrude outward beyond the two ends 2ae of the negative electrode 2 (both ends in the winding axis direction Dax).

[0069] Fig. 3 is a schematic cross-sectional view of an example of a lithium primary battery 100 including the electrode group shown in Fig. 2A. 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. 2A 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.

[0070] In the following description of the first embodiment, an example in which the metal element M is copper will be described. However, similar effects can be achieved when the metal element M is an element other than copper. In the lithium primary battery 100, copper dissolves from the short-circuiting metal sheet 21 during polarity inversion, and the dissolved copper deposits on the opposing current collector exposed portion 1c. At this time, copper is likely to deposit on the exposed positive electrode current collector. As the deposited copper grows, a conductive path (a conductive path formed by the deposited copper) is formed through 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 current collector 1a of the positive electrode 1, the conductive path formed by the deposited copper, the short-circuiting metal sheet 21, and the negative electrode lead 5. When the short-circuiting metal sheet 21 functions as a negative electrode lead, the short-circuiting metal sheet 21 may be connected to the battery case 9. Because the conductive path is formed by metal, it has low resistance.

[0071] As described above, the formation of a low-resistance conductive path reduces the internal resistance of the lithium primary battery 100 in a polarity reversal state. As will be described in the examples, by making the internal resistance value of the lithium primary battery 100 smaller than the resistance value of the external device, heat generation in the lithium primary battery 100 in a polarity reversal state can be suppressed.

[0072] In the lithium primary battery (B1), the short-circuiting metal sheet is electrically connected to the battery case without the lithium-containing metal sheet. Therefore, even if the lithium-containing metal sheet disappears due to discharge, the electrical connection between the short-circuiting metal sheet and the battery case is maintained. In the lithium primary battery (B2), the short-circuiting metal sheet and the battery case are electrically connected in a polarity inversion state. Therefore, it is possible to form the above-mentioned low-resistance conductive path.

[0073] FIG. 2C shows an example of the structure of a portion of an electrode group 10 of a primary battery (B2X). FIG. 2D (top view) shows an example of the arrangement of the negative electrode 2, negative electrode lead 5, and short-circuiting metal sheet 21 shown in FIG. 2C . In the electrode group 10 shown in FIG. 2C , the short-circuiting metal sheet 21 is attached to the negative electrode 2 (lithium-containing metal sheet) and the negative electrode lead 5 by an insulating adhesive layer 42. Due to the presence of the insulating adhesive layer 42, the short-circuiting metal sheet 21 is not electrically connected to the negative electrode 2 and the negative electrode lead 5 at the time the battery is fabricated. In the example shown in FIG. 2C , the minimum distance Dmin between the negative electrode lead 5 and the short-circuiting metal sheet 21 is determined by the thickness of the insulating adhesive layer 42.

[0074] Before the polarity inversion state, the negative electrode lead 5 and the short-circuiting metal sheet 21 are not electrically connected. On the other hand, when the polarity inversion state occurs due to discharge, lithium eluted from the lithium-containing metal sheet (negative electrode 2) is deposited on the surface of the negative electrode lead 5. It is believed that the deposited lithium forms a conductive path between the negative electrode lead 5 and the short-circuiting metal sheet 21, thereby electrically connecting the negative electrode lead 5 and the short-circuiting metal sheet 21. Furthermore, as described above, it is believed that copper ions eluted from the short-circuiting metal sheet 21 are deposited on the surface of the current collector exposed portion 1c, electrically connecting the positive electrode 1 and the short-circuiting metal sheet 21. As a result, the sealing plate 8 (positive electrode terminal) and the battery case 9 (negative electrode terminal) are connected via the positive electrode lead 4, the positive electrode 1, the conductive path formed by the deposited copper, the short-circuiting metal sheet 21, the conductive path formed by the deposited lithium, and the negative electrode lead 5. As a result, heat generation from the lithium primary battery 100 in the polarity inversion state can be suppressed.

[0075] (Additional Notes) This specification discloses the following technologies: (Technology 1) A cylindrical lithium primary battery comprising: an electrode group in which a positive electrode, a negative electrode, and a separator are wound together; a short-circuiting metal sheet arranged on 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 arranged on the positive electrode current collector, the positive electrode has a current collector exposed portion where a portion of the positive electrode current collector is exposed, the negative electrode comprises a lithium-containing metal sheet, the short-circuiting metal sheet contains at least one metal element M selected from the group consisting of copper, iron, nickel, and zinc, at least a portion of the short-circuiting metal sheet and at least a portion of the current collector exposed portion face each other with the separator interposed therebetween, and the short-circuiting metal sheet is electrically connected to the battery case without the lithium-containing metal sheet interposed therebetween. (Technology 2) The cylindrical lithium primary battery according to Technology 1, further including a negative electrode lead electrically connected to the battery case, wherein the electrode group has a stacking portion in which the short-circuiting metal sheet is arranged, and the lithium-containing metal sheet, the short-circuiting metal sheet, and the negative electrode lead are stacked in the stacking portion. (Technology 3) A cylindrical lithium primary battery comprising: an electrode group in which a positive electrode, a negative electrode, and a separator are wound; a short-circuiting metal sheet arranged on 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 arranged on the positive electrode current collector, the positive electrode has a current collector exposed portion where a portion of the positive electrode current collector is exposed, the negative electrode comprises a lithium-containing metal sheet, the short-circuiting metal sheet contains at least one metal element M selected from the group consisting of copper, iron, nickel, and zinc, at least a portion of the short-circuiting metal sheet and at least a portion of the current collector exposed portion face each other with the separator interposed therebetween, and the short-circuiting metal sheet and the battery case are electrically connected in a state of polarity reversal due to discharge.(Technology 4) The cylindrical lithium primary battery according to Technology 3, further including a negative electrode lead electrically connected to the battery case, wherein the electrode group has a stacked portion in which the short-circuiting metal sheet is disposed, wherein the lithium-containing metal sheet, the negative electrode lead, an adhesive layer, and the short-circuiting metal sheet are stacked in this order in the stacked portion before the polarity reversal state, and wherein, in the polarity reversal state, a portion of lithium eluted from the lithium-containing metal sheet is deposited on the short-circuiting metal sheet in the stacked portion, and the deposited lithium electrically connects the short-circuiting metal sheet and the negative electrode lead. (Technology 5) The cylindrical lithium primary battery according to any one of Technology 1 to 4, wherein the short-circuiting metal sheet includes a sheet of the metal element M or a sheet of an alloy of the metal element M, and wherein the lithium-containing metal sheet includes a sheet of lithium or a sheet of a lithium alloy. (Technology 6) The area where the positive electrode current collector exposed in the current collector exposed portion and the short-circuiting metal sheet face each other across the separator is 3.0 mm. ２ The cylindrical lithium primary battery according to any one of the above techniques 1 to 5. (Technology 7) The area is 72 mm ２ The cylindrical lithium primary battery according to the following technique 6.

[0076] 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.

[0077] (Fabrication of Battery A1) Battery A1 (lithium primary battery) was fabricated according to the following procedure. (1) Fabrication of Positive Electrode A positive electrode mixture was obtained 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 filled into one side of a positive electrode current collector (thickness: 0.1 mm), dried, and then rolled to a thickness of 0.5 mm. A stainless steel (SUS444) expanded metal was used for the positive electrode current collector. The positive electrode mixture was filled into one side of the positive electrode current collector, leaving the other side as the current collector exposed portion (current collector exposed surface). In this way, a positive electrode having a structure similar to that of the positive electrode 1 shown in FIG. 2A was fabricated. The resulting positive electrode was cut to a predetermined size (width: 26 mm, length: 230 mm) to obtain a positive electrode for Battery A1. A SUS444 positive electrode lead was connected to the resulting positive electrode. In addition, insulating tape was attached to the outer peripheral edge of the positive electrode to prevent short circuits (the same applies to the batteries described below). Specifically, insulating tape was attached so as to cover both sides of the outer peripheral edge.

[0078] (2) Preparation of Negative Electrode A negative electrode was obtained by cutting a lithium metal foil (thickness: 170 μm) to a predetermined size (width: 24 mm, length: 250 mm). A negative electrode lead (material: nickel, width: 5 mm, length: 30 mm) was connected to the obtained negative electrode. Furthermore, a short-circuiting metal sheet (copper foil) was crimped (connected) onto the lithium metal foil and the negative electrode lead so as to cover a portion of the negative electrode lead. The width of the copper foil was 10 mm and the length was 30 mm. In this way, a structure having an arrangement similar to that shown in FIG. 2B was formed. As shown in FIG. 2B, the two ends of the short-circuiting metal sheet (ends 21 ae) do not protrude outward beyond the two ends of the lithium-containing metal sheet (ends 2 ae) (the same applies to the batteries described below).

[0079] (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 ３A non-aqueous electrolyte was prepared by dissolving the above in water.

[0080] (4) Battery Assembly A wound electrode assembly was formed by winding the positive electrode, negative electrode, and separator. A polypropylene microporous membrane (thickness: 25 μm) was used as the separator. The electrode assembly was formed to have the structure shown in FIG. 2A. The positive electrode was positioned so that the exposed current collector portion faced the inner periphery. Next, the electrode assembly and nonaqueous electrolyte were placed in a battery case (made of iron). Next, the opening of the battery case was 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.

[0081] The proportion (area) of the positive electrode current collector exposed in the current collector exposed portion was determined by the above-described method (image analysis). The proportion of the positive electrode current collector exposed in the current collector exposed portion was 6%. Then, the area S1 of the exposed positive electrode current collector facing the short-circuit metal sheet with the separator sandwiched therebetween was calculated.

[0082] (Batteries A2 and A3) Batteries A2 and A3 were fabricated in the same manner and under the same conditions as those for fabricating Battery A1, except that the area S1 was changed by changing the shape (area) of the short-circuit metal sheet.

[0083] (Battery A4) Battery A4 was fabricated using the same method and conditions as Battery A1, except that the shape (area) of the short-circuiting metal sheet was changed. In the fabrication of Battery A4, an electrode assembly was fabricated to have the structure shown in FIG. 4A . The short-circuiting metal sheet used in Battery A4 had a width of 24 mm, the same as the width of the lithium-containing metal sheet, and a length of 70 mm. In the electrode assembly of Battery A4, the short-circuiting metal sheet was wound one or more times.

[0084] (Battery A5) In the production of Battery A5, an electrode group was formed to have the structure shown in FIG. 4B . The same materials used to construct the electrode group were used as those used to produce Battery A1 (unless otherwise specified, this also applies to the electrode groups of the following batteries). As shown in FIG. 4B , insulating tape 41 was attached so as to cover the surface of the negative electrode lead 5. Battery A5 was produced using the same method and conditions as Battery A1, except for using the formed electrode group.

[0085] (Battery A6) In the fabrication of Battery A6, an electrode group was formed to have the structure shown in FIG. 4C . The arrangement of the negative electrode lead 5 and short-circuiting metal sheet 21 of Battery A6 is shown in FIG. 4D (top view). The short-circuiting metal sheet 21 was attached to the negative electrode 2 (lithium-containing metal sheet) by an insulating adhesive layer 42. The negative electrode lead 5 was connected to the negative electrode 2 and the short-circuiting metal sheet 21 by crimping. The short-circuiting metal sheet 21 was electrically connected to the negative electrode 2 via the negative electrode lead 5. Battery A6 was fabricated in the same manner and under the same conditions as Battery A1, except for using the formed electrode group.

[0086] (Battery A7) In the production of Battery A7, an electrode group was formed to have the structure shown in FIG. 4E. The short-circuiting metal sheet 21 was attached to the negative electrode 2 (lithium-containing metal sheet) by a conductive adhesive layer 43. The short-circuiting metal sheet 21 was electrically connected to the negative electrode 2 via the conductive adhesive layer 43. Battery A7 was produced by the same method and under the same conditions as those for the production of Battery A1, except that the formed electrode group was used.

[0087] (Battery A8) In the fabrication of Battery A8, an electrode group was formed to have the structure shown in FIG. 4F. In Battery A8, the short-circuiting metal sheet 21 was connected to the battery case and also functioned as a negative electrode lead. Battery A13 was fabricated using the same method and conditions as Battery A1, except that the formed electrode group was used.

[0088] (Battery A9) For Battery A9, an electrode group was formed to have the structure shown in FIG. 4G. In Battery A9, the positive electrode was arranged so that the current collector exposed portion 1c faced outward. Battery A13 was fabricated using the same method and conditions as Battery A1, except that the formed electrode group was used.

[0089] (Battery A10) Battery A10 is an example of the primary battery (B2X) described above. The electrode group 10 of Battery A10 was formed to have the structure shown in FIGS. 2C and 2D . The shortest distance Dmin between the short-circuiting metal sheet 21 and the negative electrode lead 5 was approximately 20 μm or less. Battery A10 was fabricated using the same method and conditions as Battery A1, except for using the formed electrode group.

[0090] (Batteries A11 to A13) Batteries A11 to A13 were fabricated using the same method and conditions as Battery A3, except for changing the short-circuiting metal sheet 21. Brass foil (copper:zinc = 65:35 (mass ratio)) was used for the short-circuiting metal sheet 21 of Battery A11. Iron foil was used for the short-circuiting metal sheet 21 of Battery A12. Nickel foil was used for the short-circuiting metal sheet 21 of Battery A13.

[0091] (Battery C1) In the fabrication of Battery C1, the method for fabricating the positive electrode was changed. Specifically, a positive electrode was fabricated by filling both sides with a positive electrode mixture, resulting in a positive electrode with no exposed current collector. In other words, the positive electrode of Battery C1 does not have an exposed current collector portion. Battery C1 was fabricated using the same method and conditions as Battery A1, except for using the fabricated positive electrode.

[0092] (Battery C2) In producing Battery C2, an electrode group was formed to have the structure shown in Fig. 4H. As shown in Fig. 4H, the short-circuiting metal sheet 21 of Battery C2 is electrically connected to the battery case via the lithium-containing metal sheet (negative electrode 2) and the negative electrode lead 5. Therefore, when the lithium-containing metal sheet disappears due to discharge, the electrical connection between the short-circuiting metal sheet 21 and the battery case is severed.

[0093] (Battery C3) In the fabrication of Battery C3, an electrode group was formed to have the structure shown in FIG. 4I. In the fabrication of Battery C3, insulating tape 41 was attached so as to cover the surface of the negative electrode lead 5. During battery assembly, the current collector exposed portion 1c of Battery C3 faced the negative electrode 2 across the separator 3, and did not face the short-circuiting metal sheet 21. Battery C3 was fabricated in the same manner and under the same conditions as Battery A1, except for using the formed electrode group.

[0094] (Overdischarge Test) An overdischarge test was conducted on each of the fabricated batteries under the following conditions. Specifically, the overdischarge test was conducted using the circuit shown in FIG. 5. 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 a power source to bring 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.

[0095] The temperature of the battery 201 increased due to the overdischarge test. The temperature change of the side surface of the battery 201 during the overdischarge test was monitored. Then, the maximum temperature Tmax of the side surface of the battery 201 and the time T (25°C) from the start of the test until the temperature of the side surface of the battery 201 returned to 25°C were calculated.

[0096] Table 1 shows some of the fabrication conditions and evaluation results for each battery. In Table 1, area S1 indicates the area where the exposed positive electrode current collector in the current collector exposed portion faces the short-circuiting metal sheet with the separator in between. The lower the maximum temperature Tmax, the smaller the temperature rise of the battery in the overdischarge state (polarity reversal state). The shorter the time T (25°C), the faster the rate at which the increased temperature falls.

[0097]

[0098] Batteries A1 to A13 are lithium primary batteries (B) according to the present disclosure. Batteries C1 to C3 are comparative examples. As shown in Table 1, compared to batteries C1 to C3, batteries A1 to A13 had lower maximum temperatures Tmax and shorter times T (25°C). The area S1 was 3.0 mm ２ or more (for example, 6.0 mm ２ Particularly good results were obtained by using the above.

[0099] The present disclosure is applicable to cylindrical lithium primary batteries. While the present invention has been described with reference to presently preferred embodiments, such disclosure should not be construed as limiting. Various modifications and variations will no doubt become apparent to those skilled in the art to which the present invention pertains upon reading the above disclosure. Therefore, the appended claims should be construed to cover all modifications and variations that do not depart from the true spirit and scope of the present invention.

[0100] 1: Positive electrode 1a: Positive electrode current collector 1c: Current collector exposed portion 2: Negative electrode 3: Separator 5: Negative electrode lead 9: Battery case 10: Electrode group 10x: Laminated portion 21: Short-circuit metal sheet 100: Lithium primary battery

Claims

1. A cylindrical primary lithium battery, comprising: an electrode group in which a positive electrode, a negative electrode, and a separator are wound; a short-circuiting metal sheet disposed on the negative electrode; and a battery case that houses the electrode group and functions as a negative electrode terminal, wherein 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 positive electrode has a current collector exposed portion where a part of the positive electrode current collector is exposed, the negative electrode includes a lithium-containing metal sheet, the short-circuiting metal sheet includes at least one metal element M selected from the group consisting of copper, iron, nickel, and zinc, at least a part of the short-circuiting metal sheet and at least a part of the current collector exposed portion face each other with the separator interposed therebetween, and the short-circuiting metal sheet is electrically connected to the battery case without passing through the lithium-containing metal sheet.

2. The cylindrical primary lithium battery according to claim 1, further comprising a negative electrode lead electrically connected to the battery case, wherein the electrode group has a laminated portion where the short-circuiting metal sheet is disposed, and the lithium-containing metal sheet, the short-circuiting metal sheet, and the negative electrode lead are laminated in the laminated portion.

3. A cylindrical primary lithium battery, comprising: an electrode group in which a positive electrode, a negative electrode, and a separator are wound; a short-circuiting metal sheet disposed on the negative electrode; and a battery case that houses the electrode group and functions as a negative electrode terminal, wherein 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 positive electrode has a current collector exposed portion where a part of the positive electrode current collector is exposed, the negative electrode includes a lithium-containing metal sheet, the short-circuiting metal sheet includes at least one metal element M selected from the group consisting of copper, iron, nickel, and zinc, at least a part of the short-circuiting metal sheet and at least a part of the current collector exposed portion face each other with the separator interposed therebetween, and in a polarized state due to discharge, the short-circuiting metal sheet and the battery case are electrically connected.

4. Further including a negative electrode lead electrically connected to the battery case, the electrode group having a stacked portion where the short-circuiting metal sheet is disposed, in the stacked portion in the state before reaching the inversion state, the lithium-containing metal sheet, the negative electrode lead, the adhesive layer, and the short-circuiting metal sheet are stacked in this order, in the inversion state, a part of the lithium eluted from the lithium-containing metal sheet is deposited on the short-circuiting metal sheet of the stacked portion, and the short-circuiting metal sheet and the negative electrode lead are electrically connected by the deposited lithium, the cylindrical primary lithium battery according to claim 3.

5. The short-circuiting metal sheet includes a sheet of the metal element M or a sheet of an alloy of the metal element M, the lithium-containing metal sheet includes a sheet of lithium or a sheet of a lithium alloy, the cylindrical primary lithium battery according to claim 1 or 3.

6. The area where the exposed positive current collector and the short-circuit metal sheet exposed at the current collector exposed portion face each other with the separator therebetween is 3.0 mm ２ or more. The cylindrical primary lithium battery according to claim 1 or 3.

7. The area is 72 mm ２ The cylindrical primary lithium battery according to claim 6, wherein the area is 72 mm or less.

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