Cylindrical lithium primary battery

Abstract

Disclosed is a cylindrical lithium primary battery (100) including: an electrode group (10) in which a positive electrode (1), a negative electrode (2), and a separator (3) are wound; an electrically insulating layer (22) disposed inside the electrode group (10); a short-circuiting metal sheet (21) disposed on the negative electrode (2); and a battery case (9). The positive electrode (1) includes a positive electrode mixture layer disposed on a positive electrode current collector. The negative electrode (2) includes a lithium-containing metal sheet. The short-circuiting metal sheet (21) contains at least one metal element M selected from the group consisting of copper, iron, nickel, and zinc. The lithium-containing metal sheet, the short-circuiting metal sheet (21), and the battery case (9) are electrically connected. The electrode group (10) has a layered portion (10x) in which the electrically insulating layer (22) is disposed. In the layered portion, the lithium-containing metal sheet, the short-circuiting metal sheet (21), the separator (3), the positive electrode (1), and the electrically insulating layer (22) are laminated in a prescribed order.

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 provides a cylindrical lithium primary battery comprising: an electrode group in which a positive electrode, a negative electrode, and a separator are wound; an electrical insulating layer disposed inside the electrode group; 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 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, and the short-circuiting metal sheet contains at least one metal element M selected from the group consisting of copper, iron, nickel, and zinc, the lithium-containing metal sheet, the short-circuiting metal sheet, and the battery case are electrically connected, and the electrode group has a laminated portion in which the electrical insulating layer is disposed, The present invention relates to a cylindrical lithium primary battery, wherein the lithium-containing metal sheet, the short-circuiting metal sheet, the separator, the positive electrode, the electrical insulating layer, the separator, and the lithium-containing metal sheet are stacked in this order in the stacked portion, or the lithium-containing metal sheet, the short-circuiting metal sheet, the separator, the positive electrode, the separator, the electrical insulating layer, and the lithium-containing metal sheet are stacked in this order.

[0009] Another aspect of the present disclosure is a cylindrical lithium primary battery comprising: an electrode group in which a positive electrode, a negative electrode, and a separator are wound; an electrical insulating layer disposed inside the electrode group; 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 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 short-circuiting metal sheet contains at least one metal element M selected from the group consisting of copper, iron, nickel, and zinc, the electrode group has a laminate portion in which the electrical insulating layer is disposed, The present invention relates to a cylindrical lithium primary battery, wherein, in the laminated portion before a polarity reversal state due to discharge occurs, the lithium-containing metal sheet, the short-circuiting metal sheet, the separator, the positive electrode, the electrical insulating layer, the separator, and the lithium-containing metal sheet are laminated in this order, or the lithium-containing metal sheet, the short-circuiting metal sheet, the separator, the positive electrode, the separator, the electrical insulating layer, and the lithium-containing metal sheet are laminated in this order, and in the polarity reversal state, the short-circuiting metal sheet and the battery case are electrically connected.

[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 portion of an example of a lithium primary battery of Embodiment 1. FIG. 2B is a cross-sectional view schematically showing a portion of an example of a lithium primary battery of Embodiment 1. FIG. 2C is a cross-sectional view schematically showing a portion of an example of a lithium primary battery of Embodiment 1. FIG. 2D is a top 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 prepared in an Example. FIG. 4B is a top view schematically showing a portion of a lithium primary battery prepared in an Example. FIG. 5 is a cross-sectional view schematically showing a portion of a lithium primary battery prepared in an Example. FIG. 6 is a cross-sectional view schematically showing a portion of a lithium primary battery prepared in an Example. FIG. 7 is a cross-sectional view schematically showing a portion of a lithium primary battery prepared in an Example. FIG. 8 is a cross-sectional view schematically showing a portion of a lithium primary battery prepared in an Example. Fig. 9 is a cross-sectional view schematically showing a part of a lithium primary battery fabricated in the examples. Fig. 10 is a diagram schematically showing the 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 group in which a positive electrode, a negative electrode, and a separator are wound together, an electrical insulating layer disposed inside the electrode group, 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. 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 short-circuiting metal sheet includes at least one metal element M selected from the group consisting of copper, iron, nickel, and zinc. The lithium-containing metal sheet, the short-circuiting metal sheet, and the battery case are electrically connected. The electrode group has a laminated portion in which an electrical insulating layer is disposed. In the laminated portion, a lithium-containing metal sheet, a metal sheet for short circuit, a separator, a positive electrode, an electrical insulating layer, a separator, and a lithium-containing metal sheet are laminated in this order, or a lithium-containing metal sheet, a metal sheet for short circuit, a separator, a positive electrode, a separator, an electrical insulating layer, and a lithium-containing metal sheet are laminated in this order.

[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 together, an electrical insulating layer disposed inside the electrode assembly, a short-circuiting metal sheet disposed 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 disposed on the positive electrode current collector. 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. The electrode assembly has a laminate portion in which an electrical insulating layer is disposed. In the laminated portion in a state before the polarity is reversed by discharge, the lithium-containing metal sheet, the short-circuiting metal sheet, the separator, the positive electrode, the electrical insulating layer, the separator, and the lithium-containing metal sheet are laminated in this order, or the lithium-containing metal sheet, the short-circuiting metal sheet, the separator, the positive electrode, the separator, the electrical insulating layer, and the lithium-containing metal sheet are laminated in this order. In the polarity reversal state, 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), when a polarity inversion occurs, it is thought that deposition of the metal element M occurs preferentially in a part of the positive electrode in the laminated portion, and a low-resistance conductive path is formed between the part of the positive electrode and the short-circuiting metal sheet by the deposited metal element M. Therefore, it is possible to suppress the temperature rise of the battery when a polarity inversion occurs.

[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) and the primary battery (B2), the short-circuiting metal sheet may be electrically connected to the battery case without the lithium-containing metal sheet. In other words, in the primary battery (B1) and the primary battery (B2), a conductive path may exist between the short-circuiting metal sheet and the battery case without the lithium-containing metal sheet. Alternatively, 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] Hereinafter, the electrical insulating layer disposed in the laminated portion of the primary battery (B1) and the primary battery (B2) may be referred to as the "electrical insulating layer L." The laminated portion of the primary battery (B1) and the primary battery (B2) will be described. The components constituting the laminated portion are laminated in the radial direction of the electrode group. The components constituting the laminated portion may be laminated in the above-mentioned order from the center (the central axis of winding) of the electrode group toward the outside, or from the outside of the electrode group toward the center. The laminated portion is located in a region obtained by projecting the region where the above-mentioned electrical insulating layer L is present in the radial direction of the electrode group. The laminated portion may be formed at any position in the electrode group. The above-mentioned electrical insulating layer L may be disposed at any position in the electrode group. For example, the electrical insulating layer L may be disposed closer to the outermost periphery of the electrode group than the winding axis of the electrode group in a cross section of the electrode group (a cross section perpendicular to the winding axis).

[0025] In the stacked portion of the primary battery (B1) and the primary battery (B2), it can be considered that a portion N1 of the lithium-containing metal sheet, at least a portion C1 of the short-circuiting metal sheet, a portion S1 of the separator, a portion P1 of the positive electrode, a portion S2 of the separator, and a portion N2 of the lithium-containing metal sheet are stacked in this order. An electrical insulating layer is disposed between the portion P1 of the positive electrode and the portion N2 of the lithium-containing metal sheet. An electrical insulating layer is not disposed between at least a portion C1 of the short-circuiting metal sheet and the portion P2 of the positive electrode.

[0026] The laminated portion of the primary battery (B1) and the primary battery (B2) may include components other than those described above (e.g., a negative electrode lead, an adhesive layer, etc.). However, as described above, the electrical insulating layer L is disposed between the positive electrode portion P1 and the lithium-containing metal sheet portion N2, and is not disposed between at least the short-circuiting metal sheet portion C1 and the positive electrode portion P2.

[0027] (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.

[0028] 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.

[0029] 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.

[0030] The area of ​​the short-circuit metal sheet is 10 mm ２ or more, or 20 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.

[0031] In the primary battery (B1) and the primary battery (B2), the area S1 where the short-circuiting metal sheet and the electrical insulating layer L face each other with the positive electrode and the separator sandwiched therebetween is 2.0 mm ２ More than 4.0 mm ２ That's it, and 30mm again ２ More than 200 mm ２ The area S1 may be 1500 mm or more. ２Below, 1200mm ２ Below, 500mm ２ 200m below ２ Less than or equal to 30 mm ２ The area S1 may be 4.0 mm or less. ２ By setting the area S to 1200 mm or more, the temperature rise of the battery in the polarity inversion state can be particularly suppressed. ２ By setting the area S1 to 4.0 mm or less, the decrease in discharge capacity can be suppressed. ２ That's 1200mm ２ It may be the following:

[0032] In the primary battery (B1) and the primary battery (B2), the positive electrode may have a current collector exposed portion in which a portion of the positive electrode current collector is exposed. Furthermore, at least a portion of the short-circuiting metal sheet and at least a portion of the current collector exposed portion may face each other across the separator. This configuration facilitates lithium deposition on the positive electrode current collector in a polarity reversal state, thereby reducing the resistance of the conductive path. As a result, the temperature rise of the battery in a polarity reversal state can be particularly suppressed.

[0033] The area S2 of the exposed positive electrode current collector and the short-circuit metal sheet facing each other with the separator sandwiched therebetween in the current collector exposed portion of the primary battery (B1) and the primary battery (B2) is 0.1 mm ２ Above, 0.25mm ２ or more, or 1.8 mm ２ It may be 20 mm or more. ２ Below, 10mm ２ Less than or equal to 1.8 mm ２ The area S2 may be 0.25 m or less. ２ By setting the above, it is possible to particularly suppress the temperature rise of the battery in the polarity inversion state.

[0034] The current collector exposed portion has a surface where the current collector is exposed. The area S2 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.

[0035] (Electrical Insulation Layer L) The electrical insulation layer L is a layer having electrical insulation properties. The electrical insulation layer L may include a layer (reaction suppression layer) that suppresses charge-discharge reactions in the area where the electrical insulation layer L is disposed. Specifically, the charge-discharge reactions between the positive electrode and the negative electrode facing each other across the electrical insulation layer L are suppressed. For example, the electrical insulation layer L may include a layer that does not allow metal ions to pass through. Here, "does not allow metal ions to pass through" means that metal ions in an amount that would affect the behavior of the battery are not allowed to pass through. Therefore, the phenomenon of metal ions penetrating over a long period of time is not included in the metal ion permeation. Even if porous membranes and nonwoven fabrics are made of insulating materials, they allow metal ions to pass through when impregnated with a nonaqueous electrolyte. Therefore, porous membranes and nonwoven fabrics are not included in the "electrical insulation layer L."

[0036] An example of the electrical insulation layer L includes a non-porous film formed using an insulating material. The insulating material may be an insulating resin composition. The insulating resin composition includes an insulating resin (e.g., polyethylene, polypropylene, polyimide, polyethylene terephthalate, polytetrafluoroethylene) and may further include an insulating inorganic filler (e.g., alumina particles).

[0037] In the primary battery (B1) and the primary battery (B2), the electrical insulating layer L may be an insulating tape. The insulating tape is not particularly limited, and any insulating tape used in known nonaqueous electrolyte batteries such as lithium primary batteries may be used. For example, the insulating tape may include a film of polyethylene, polypropylene, polyimide, glass cloth, or the like. Alternatively, the electrical insulating layer L may be formed by applying an insulating resin composition.

[0038] The thickness of the electrical insulating layer L may be 10 μm or more, or 50 μm or more, or may be 200 μm or less, or 500 μm or less. The electrical insulating layer L may be formed on the positive electrode, the negative electrode, or the separator.

[0039] The area of ​​the electrical insulating layer L is 10 mm ２ or more, or 100 mm ２ It may be 300 mm or more. ２ or less, or 720 mm ２ or less. The electrical insulating layer L may be disposed across the entire width of the component on which it is disposed, or may be disposed on only a portion of the component in the width direction. Alternatively, a portion of the electrical insulating layer L may protrude from the component in the direction of the winding axis Dax. In the electrode group, the length of the electrical insulating layer L in the direction of the winding axis Dax may be the same as the width of the component on which it is disposed (the length in the direction of the winding axis Dax), or may be shorter or longer than the width of the component.

[0040] The electrical insulating layer L may be formed by closing some of the pores of a porous separator, for example, by heating and melting part of the porous separator to close the pores.

[0041] The primary battery (B1) and the primary battery (B2) may further include a negative electrode lead that electrically connects the short-circuiting metal sheet and the battery case. When the primary battery (B1) and the primary battery (B2) do not include a negative electrode lead, the negative electrode and the battery case can be electrically connected using a short-circuiting metal sheet. The negative electrode lead may be directly connected to the lithium-containing metal sheet. Alternatively, the negative electrode lead may be electrically connected to the lithium-containing metal sheet via the short-circuiting metal sheet.

[0042] 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.

[0043] 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.

[0044] 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. In the primary battery (B2X), in a polarity inversion state, it is believed that a portion of the lithium eluted from the lithium-containing metal sheet is deposited on the shorting metal sheet of the stack, and the deposited lithium electrically connects the shorting metal sheet and the negative electrode lead. In this way, in the primary battery (B2X), the shorting metal sheet and the negative electrode lead are connected with low resistance due to the electrical connection provided by the deposited lithium. Furthermore, it is believed that the positive electrode and the shorting metal sheet are connected with low resistance by the deposited metal element M. Therefore, the internal resistance of the battery in a polarity inversion state is reduced, thereby suppressing the temperature rise of the battery.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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 an electrical insulating layer L disposed inside the electrode group and a short-circuiting metal sheet disposed on the negative electrode. At least a portion of the electrical insulating layer L and the short-circuiting metal sheet are disposed inside the electrode group. Therefore, the electrical insulating layer L and the short-circuiting metal sheet can also be considered 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 electrical insulating layer L, the short-circuiting metal sheet, and the negative electrode lead have been described above, so redundant description will be omitted.

[0050] 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.

[0051] (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).

[0052] 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 agents 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).

[0053] Insulating tape may be attached to both sides of the outer peripheral edge of the positive electrode to prevent short circuits. The insulating tape attached to the outer peripheral edge differs from the electrical insulating layer L arranged in the laminated portion in that it is attached to both sides of the positive electrode so as to sandwich the outer peripheral edge. Of the insulating tapes arranged to sandwich both sides of the outer peripheral edge of the positive electrode, the insulating tape arranged on one side may be longer than the insulating tape arranged on the other side. The insulating tape on only one side may be used as the electrical insulating layer L.

[0054] (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.

[0055] 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.

[0056] 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).

[0057] (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.

[0058] 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.

[0059] (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.

[0060] 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.

[0061] (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.

[0062] 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.

[0063] (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.

[0064] 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.

[0065] 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.

[0066] The electrode group may be formed by the following method. First, an electrical insulating layer L is formed on a predetermined member (positive electrode, negative electrode, or separator). Furthermore, a short-circuiting metal sheet is placed on the 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 adhered to the lithium-containing metal sheet with a conductive adhesive layer (e.g., conductive tape). In the case of the primary battery (B2X), the short-circuiting metal sheet may be adhered to the lithium-containing metal sheet with 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, the positive electrode, negative electrode, and separator are wound together to form a wound electrode group. At this time, the positions of the positive electrode, negative electrode, and separator are adjusted and wound so that the laminated portion has the above-described laminated structure.

[0067] 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.

[0068] 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.

[0069] (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 an electrical insulating layer L and a short-circuiting metal sheet (neither of which are shown) disposed within the electrode group 10.

[0070] 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.

[0071] 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) except for the primary battery (B2X).

[0072] The lithium primary battery 100 (more specifically, the electrode group 10) has the laminated portion 10x described above. Examples of the structure in the vicinity of the laminated portion are shown in FIGS. 2A to 2D. 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 typically curved.

[0073] In the laminated portion 10x shown in FIG. 2A (cross-sectional view), a portion N1 of the negative electrode 2 (lithium-containing metal sheet), at least a portion C1 of the short-circuiting metal sheet 21, a portion S1 of the separator 3, a portion P1 of the positive electrode 1, an electrical insulating layer 22 (electrical insulating layer L), a portion S2 of the separator 3, and a portion N2 of the negative electrode 2 (lithium-containing metal sheet) are stacked in this order from side A to side B. The electrical insulating layer 22 is disposed between the portion P1 of the positive electrode 1 and the portion N2 of the negative electrode 2. In FIG. 2A , side A may be the inner circumferential side (side B may be the outer circumferential side), or side A may be the outer circumferential side (side B may be the inner circumferential side) (the same applies to the following figures). Note that the inner circumferential side refers to the inner circumferential side (center side) of the electrode group 10. The negative electrode 2 (lithium-containing metal sheet), the short-circuiting metal sheet 21, and the battery case 9 are electrically connected.

[0074] As shown in FIG. 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. Therefore, the electrical insulating layer 22 may be disposed at a certain distance from the outer peripheral edge of the positive electrode 1. For example, the electrical insulating layer 22 may be disposed at a position 1 mm or more (e.g., 3 mm or more) away from the outer peripheral edge of the positive electrode 1.

[0075] 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.

[0076] Fig. 3 is a schematic cross-sectional view of an example of a lithium primary battery 100 including the laminated portion 10x 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 laminated portion 10x shown in Fig. 3 is an example of the laminated portion 10x 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.

[0077] 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 obtained when the metal element M is an element other than copper. In the portion P1 of the positive electrode of the lithium primary battery 100, the discharge reaction is suppressed by the electrical insulating layer 22. Therefore, in the portion P1 of the positive electrode, there is a large amount of unreacted positive electrode active material that has not been consumed by the discharge reaction. Consider a case in which the lithium primary battery 100 is in a polarity reversal state due to overdischarge. In this case, all or most of the negative electrode 2 electrically connected to the battery case 9 has been lost due to discharge. In a polarity reversal 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 heavy metal ions. In other words, it is thought that copper ions are preferentially adsorbed to a portion P1 of the positive electrode 1 where a large amount of unreacted positive electrode active material remains, and are reduced and precipitated in the portion P1. When the precipitated copper grows and forms a conductive path passing through the inside of the separator 3, the positive electrode 1 and the short-circuiting metal sheet 21 are electrically connected by the precipitated copper. 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, the short-circuiting metal sheet 21, and the negative electrode lead 5. Note that 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.

[0078] The deposited copper forms a conductive path, thereby reducing the internal resistance of the lithium primary battery 100 in a polarity reversal state. The presence of the electrical insulating layer 22 promotes selective deposition of copper, enabling the positive electrode 1 and the short-circuiting metal sheet 21 to be connected quickly and with low resistance. As will be described in the examples, 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.

[0079] In the laminate 10x shown in FIG. 2B , a portion N1 of the negative electrode 2 (lithium-containing metal sheet), at least a portion C1 of the short-circuiting metal sheet 21, a portion S1 of the separator 3, a portion P1 of the positive electrode 1, a portion S2 of the separator 3, an electrical insulating layer 22, and a portion N2 of the negative electrode 2 (lithium-containing metal sheet) are stacked in this order from side A to side B. Side A may be the inner circumferential side of the electrode group 10 or the outer circumferential side of the electrode group 10. The negative electrode 2 (lithium-containing metal sheet), the short-circuiting metal sheet 21, and the battery case 9 are electrically connected. In this case, as in the example shown in FIG. 2A , copper dissolved in the polarity inversion state is preferentially deposited on the surface of the portion P1 of the positive electrode 1. As a result, heat generation in the lithium primary battery 100 in the polarity inversion state can be suppressed.

[0080] FIG. 2C schematically illustrates an example of the structure of a laminated portion of a primary battery (B2X) and its vicinity. In the laminated portion 10x illustrated in FIG. 2C, a portion N1 of the negative electrode 2 (lithium-containing metal sheet), at least a portion C1 of the short-circuiting metal sheet 21, a portion S1 of the separator 3, a portion P1 of the positive electrode 1, an electrical insulating layer 22 (electrical insulating layer L), a portion S2 of the separator 3, and a portion N2 of the negative electrode 2 (lithium-containing metal sheet) are stacked in this order from side A to side B. As in FIG. 2B , the electrical insulating layer 22 may be disposed between the portion S2 of the separator 3 and the portion N2 of the negative electrode 2. Side A may be the inner circumferential side of the electrode group 10 or the outer circumferential side of the electrode group 10.

[0081] A negative electrode lead 5 is connected to the negative electrode 2. The negative electrode 2 and the battery case 9 are electrically connected via the negative electrode lead 5. A short-circuiting metal sheet 21 shown in FIG. 2C is attached to the negative electrode 2 and the negative electrode lead 5 so as to cover a portion of the negative electrode lead 5 with an insulating adhesive layer 41. An example of the arrangement of the negative electrode 2, the negative electrode lead 5, and the short-circuiting metal sheet 21 is shown in FIG. 2D (top view). Note that FIG. 2D also shows the winding axis direction Dax.

[0082] Due to the presence of the insulating adhesive layer 41, at the time of fabrication of the battery, the short-circuiting metal sheet 21 is not electrically connected to the negative electrode 2 and the negative electrode lead 5. In the example shown in Fig. 2D, the thickness of the insulating adhesive layer 41 determines the minimum distance Dmin between the negative electrode lead 5 and the short-circuiting metal sheet 21.

[0083] 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 positive electrode 1 in the laminated portion 10x, 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.

[0084] (Additional Note) This specification discloses the following techniques: (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; an electrical insulating layer disposed inside the electrode group; 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 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, and the short-circuiting metal sheet contains at least one metal element M selected from the group consisting of copper, iron, nickel, and zinc, the lithium-containing metal sheet, the short-circuiting metal sheet, and the battery case are electrically connected, and the electrode group has a laminated portion in which the electrical insulating layer is disposed, In the stacked portion, the lithium-containing metal sheet, the short-circuiting metal sheet, the separator, the positive electrode, the electrical insulating layer, the separator, and the lithium-containing metal sheet are stacked in this order, or the lithium-containing metal sheet, the short-circuiting metal sheet, the separator, the positive electrode, the separator, the electrical insulating layer, and the lithium-containing metal sheet are stacked in this order.(Technology 2) A cylindrical lithium primary battery comprising: an electrode group in which a positive electrode, a negative electrode, and a separator are wound; an electrical insulating layer disposed inside the electrode group; 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 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 short-circuiting metal sheet contains at least one metal element M selected from the group consisting of copper, iron, nickel, and zinc, and the electrode group has a laminated portion in which the electrical insulating layer is disposed, A cylindrical lithium primary battery, wherein the laminated portion before a polarity reversal state due to discharge is formed by stacking the lithium-containing metal sheet, the short-circuiting metal sheet, the separator, the positive electrode, the electrical insulating layer, the separator, and the lithium-containing metal sheet in this order, or the lithium-containing metal sheet, the short-circuiting metal sheet, the separator, the positive electrode, the separator, the electrical insulating layer, and the lithium-containing metal sheet in this order, and wherein the short-circuiting metal sheet and the battery case are electrically connected in the polarity reversal state. (Technology 3) The cylindrical lithium primary battery according to Technology 1 or 2, 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 the lithium-containing metal sheet includes a sheet of lithium or a sheet of a lithium alloy. (Technology 4) The area where the short-circuiting metal sheet and the electrical insulating layer face each other across the positive electrode and the separator is 4.0 mm. ２ That's 1200mm ２ The cylindrical lithium primary battery according to any one of Techniques 1 to 3, which is as follows: (Technology 5) The positive electrode has a current collector exposed portion where a part of the positive electrode current collector is exposed, and 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. (Technology 6) The cylindrical lithium primary battery according to any one of Techniques 1 to 4, which is as follows: (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 with the separator interposed therebetween is 0.25 mm２ The cylindrical lithium primary battery according to Technology 5, wherein the electrical insulating layer is an insulating tape. (Technology 7) The cylindrical lithium primary battery according to any one of Technology 1 to 6, wherein the electrical insulating layer is an insulating tape. (Technology 8) The cylindrical lithium primary battery according to any one of Technology 1 to 7, further comprising a negative electrode lead electrically connecting the short-circuiting metal sheet and the battery case. (Technology 9) The cylindrical lithium primary battery according to Technology 8, wherein at least one selected from the group consisting of the lithium-containing metal sheet and the negative electrode lead is electrically connected to the short-circuiting metal sheet via a conductive adhesive layer. (Technology 10) The cylindrical lithium primary battery according to any one of Technology 2 to 9, further comprising a negative electrode lead electrically connected to the battery case, wherein in the polarity inversion state, part of lithium eluted from the lithium-containing metal sheet precipitates on the short-circuiting metal sheet of the laminated portion, and the precipitated lithium electrically connects the short-circuiting metal sheet and the negative electrode lead.

[0085] 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.

[0086] (Fabrication of Battery A1) Battery A1 (lithium primary battery) was fabricated using 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 a positive electrode current collector (thickness: 0.1 mm), dried, and then rolled to a thickness of 0.5 mm. Stainless steel (SUS444) expanded metal was used for the positive electrode current collector. In this manner, a positive electrode was formed, including a positive electrode current collector and a positive electrode mixture layer filled into the positive electrode current collector. Note that for the positive electrode of Battery A1, the positive electrode mixture layer was formed so as not to expose the positive electrode current collector. The resulting positive electrode was cut to a predetermined size (width: 26 mm, length: 230 mm) to obtain the positive electrode for Battery A1. A positive electrode lead made of SUS444 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.

[0087] (2) Preparation of Negative Electrode A negative electrode was obtained by cutting lithium metal foil (thickness: 300 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 copper foil had a width of 10 mm and a length of 30 mm. A portion of the negative electrode 2 (lithium metal foil) to which the negative electrode lead 5 and the short-circuiting metal sheet 21 are connected is shown in FIG. 4A. The portion shown in FIG. 4A is a portion near the outer peripheral edge 2e of the negative electrode 2. The negative electrode 2, negative electrode lead 5, and short-circuiting metal sheet 21 are electrically connected. As shown in FIG. 4A , the two ends 21 ae of the short-circuiting metal sheet 21 do not protrude outward beyond the two ends 2 ae of the negative electrode 2 (both ends in the winding axis direction Dax) (the same applies to the batteries described below).

[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) Formation of Electrical Insulation Layer Insulating tape (electrical insulation layer L) was attached to a predetermined position on one side of the positive electrode. The insulating tape used was aramid paper with a silicone adhesive applied to one side. The insulating tape was 3 mm wide and 26 mm long. The insulating tape was attached so that its longitudinal direction was parallel to the width direction of the positive electrode. A portion of the positive electrode 1 on which the electrical insulation layer 22 (electrical insulation layer L) is disposed is shown in FIG. 4B (top view). The portion of the positive electrode 1 shown in FIG. 4B is a portion near the outer peripheral edge 1e of the positive electrode 1.

[0090] (5) 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 so that the laminated portion where the electrical insulating layer L (insulating tape) was disposed had the laminated structure shown in FIG. 2A. Next, the electrode assembly and nonaqueous electrolyte were housed 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. In this manner, Battery A1 was obtained.

[0091] Battery A1 has the structure shown in Figure 2A. In Battery A1, the area S1 where the short-circuiting metal sheet and the electrical insulating layer L face each other with the positive electrode and separator sandwiched between them is shown in Table 1. Table 1 also shows the area S2 where the exposed positive electrode current collector and the short-circuiting metal sheet face each other with the separator sandwiched between them. In Battery A1, there is no exposed portion of the positive electrode current collector facing the short-circuiting metal sheet, so area S2 is zero.

[0092] (Battery A2) In Battery A2, an electrical insulating layer L (insulating tape) was attached to the negative electrode, not to the positive electrode. An electrode group was then formed in the same manner as Battery A1. The laminated portion of the formed electrode group had the same laminated structure as the laminated portion shown in FIG. 2B. Battery A2 was fabricated in the same manner and under the same conditions as Battery A1, except that the formed electrode group was used.

[0093] (Battery A3) Battery A3 was produced in the same manner and under the same conditions as those for Battery A2, except that a polypropylene film was used instead of the insulating tape.

[0094] (Battery A4) In Battery A4, an electrode group was formed so that the laminated portion had the laminated structure shown in Figure 5. The same members as those used to fabricate Battery A1 were used to construct the electrode group. Battery A4 was fabricated using the same method and conditions as Battery A1, except for using the formed electrode group.

[0095] (Batteries A5 to A7) Batteries A5 to A7 were fabricated using the same method and conditions as Battery A1, except that the area S1 was changed. The area S1 was changed by changing the shape (area) of the electrical insulating layer L and / or the shape (area) of the short-circuiting metal sheet. The width (length in the direction of the winding axis) of the short-circuiting metal sheet of Battery A7 was 24 mm, the same as the width of the negative electrode.

[0096] (Battery A8) In Battery A8, the positive electrode was fabricated using a different method. Specifically, the positive electrode was formed so that the positive electrode current collector was exposed on one side of the positive electrode. That is, one side of the positive electrode of Battery A8 was designated as the current collector exposed portion (current collector exposed surface). The proportion (area) of the positive electrode current collector exposed in the current collector exposed portion was determined using the method described above (image analysis). The proportion of the positive electrode current collector exposed in the current collector exposed portion was 6%. The area S2 was then calculated. Battery A8 was fabricated using the same method and conditions as Battery A1, except for the use of this positive electrode. The positive electrode was positioned so that the current collector exposed surface faced the inner periphery. That is, the positive electrode was positioned so that the current collector exposed surface and the short-circuiting metal sheet faced each other across the separator.

[0097] (Battery A9) Battery A9 was fabricated using the same method and conditions as Battery A8, except that the areas S1 and S2 were changed. The areas S1 and S2 were changed by changing the shape (area) of the electrical insulating layer L and the shape (area) of the short-circuiting metal sheet. In the fabrication of the following batteries, when the area S1 and / or the area S2 was changed, the areas S1 and S2 were changed by changing the shape (area) of the electrical insulating layer L and / or the shape (area) of the short-circuiting metal sheet.

[0098] (Battery A10) Instead of crimping a short-circuiting metal sheet to the negative electrode lead and the lithium-containing metal sheet, a copper foil (short-circuiting metal sheet) having an insulating adhesive layer was attached to the lithium-containing metal sheet. The negative electrode lead was then crimped to the short-circuiting metal sheet and the lithium-containing metal sheet. A top view of a portion of the negative electrode of Battery A10 is shown in FIG. 6. The short-circuiting metal sheet 21 is electrically connected to the negative electrode 2 (lithium-containing metal sheet) via the negative electrode lead 5. Battery A10 was fabricated using the same method and conditions as Battery A8, except for the use of these components.

[0099] (Battery A11) An electrode group 10 was formed so that the laminated portion had the structure shown in FIG. 7 . The negative electrode lead 5 was attached to the lithium-containing metal sheet (negative electrode 2) by crimping. The short-circuiting metal sheet 21 was attached to the negative electrode lead 5 and the lithium-containing metal sheet (negative electrode 2) with a conductive adhesive layer 42 so as to cover a portion of the negative electrode lead 5. The short-circuiting metal sheet 21, the lithium-containing metal sheet, and the negative electrode lead 5 were electrically connected. The positive electrode used in the preparation of Battery A8 was used as the positive electrode. Battery A11 was prepared using the same method and conditions as those for the preparation of Battery A1, except that the formed electrode group was used.

[0100] (Battery A12) An electrode group 10 was formed so that the laminated portion 10x had the structure shown in FIG. 8. In the electrode group 10 of FIG. 8, a short-circuiting metal sheet was wound around one or more times. In the laminated portion of FIG. 8, insulating tape (electrical insulating layer 22) was attached to the negative electrode lead 5 and the lithium-containing metal sheet (negative electrode 2) so as to cover a portion of the negative electrode lead 5. The positive electrode used in the preparation of Battery A8 was used as the positive electrode. Battery A12 was prepared using the same method and conditions as those for the preparation of Battery A1, except that the formed electrode group was used.

[0101] (Battery A13) An electrode group 10 was formed so that the laminated portion had the structure shown in FIG. 9 . An electrical insulating layer 22 was formed on the positive electrode 1. A short-circuiting metal sheet 21 was pressure-bonded to the lithium-containing metal sheet (negative electrode 2). In Battery A13, the short-circuiting metal sheet 21 was connected to the battery case and also functioned as a negative electrode lead. The positive electrode used in the preparation of Battery A1 was used as the positive electrode. Battery A13 was prepared using the same method and conditions as Battery A1, except that the formed electrode group was used.

[0102] (Battery A14) Battery A14 is an example of the primary battery (B2X) described above. The electrode group 10 of Battery A14 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. The positive electrode used in the preparation of Battery A8 was used as the positive electrode. Battery A13 was prepared using the same method and conditions as Battery A1, except for using the formed electrode group.

[0103] (Batteries A15 to A17) Batteries A15 to A17 were fabricated using the same method and conditions as Battery A6, 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 A15. Iron foil was used for the short-circuiting metal sheet 21 of Battery A16. Nickel foil was used for the short-circuiting metal sheet 21 of Battery A17.

[0104] (Battery C1) Battery C1 was produced in the same manner and under the same conditions as those for producing battery A1, except that the electrical insulating layer L was not disposed inside the electrode group.

[0105] (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. 10 . 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.

[0106] 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.

[0107] Table 1 shows some of the fabrication conditions and evaluation results for each battery. In Table 1, area S1 indicates the area where the short-circuiting metal sheet and the electrical insulating layer L face each other with the positive electrode and separator sandwiched between them. Area S2 indicates the area where the positive electrode current collector exposed in the current collector exposed portion faces the short-circuiting metal sheet with the separator sandwiched between them. The lower the maximum temperature Tmax, the smaller the temperature rise of the battery in an overdischarge state (polarity reversal state). The shorter the time T (25°C), the faster the rate at which the increased temperature falls.

[0108]

[0109] Batteries A1 to A17 are lithium primary batteries (B) according to the present disclosure. Battery C1 is a comparative example. As shown in Table 1, compared to Battery C1, Batteries A1 to A17 had lower maximum temperatures Tmax and shorter times T (25°C). When the area S1 was 4.0 mm ２ or more (for example, 30 mm ２ Particularly good results were obtained by making the area S2 greater than zero.

[0110] 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.

[0111] 1: Positive electrode 1a: Positive electrode current collector 2: Negative electrode 3: Separator 5: Negative electrode lead 9: Battery case 10: Electrode group 10x: Laminated portion 21: Short-circuit metal sheet 22: Electrical insulating layer 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; an electrical insulating layer disposed inside the electrode group; 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 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, the lithium-containing metal sheet, the short-circuiting metal sheet, and the battery case are electrically connected, the electrode group has a laminated portion where the electrical insulating layer is disposed, and in the laminated portion, the lithium-containing metal sheet, the short-circuiting metal sheet, the separator, the positive electrode, the electrical insulating layer, the separator, and the lithium-containing metal sheet are laminated in this order, or the lithium-containing metal sheet, the short-circuiting metal sheet, the separator, the positive electrode, the separator, the electrical insulating layer, and the lithium-containing metal sheet are laminated in this order.

2. A cylindrical primary lithium battery, comprising: an electrode group in which a positive electrode, a negative electrode, and a separator are wound; an electrical insulating layer disposed inside the electrode group; 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 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, the electrode group has a laminated portion where the electrical insulating layer is disposed, and in the laminated portion in a state before reaching a pole inversion state due to discharge, the lithium-containing metal sheet, the short-circuiting metal sheet, the separator, the positive electrode, the electrical insulating layer, the separator, and the lithium-containing metal sheet are laminated in this order, or the lithium-containing metal sheet, the short-circuiting metal sheet, the separator, the positive electrode, the separator, the electrical insulating layer, and the lithium-containing metal sheet are laminated in this order, and in the pole inversion state, the short-circuiting metal sheet and the battery case are electrically connected.

3. The cylindrical primary lithium battery according to claim 1 or 2, 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 the lithium-containing metal sheet includes a sheet of lithium or a sheet of a lithium alloy.

4. The area where the short-circuit metal sheet and the electrical insulation layer face each other with the positive electrode and the separator therebetween is 4.0 mm ２ or more and 1200 mm ２ or less. The cylindrical primary lithium battery according to claim 1 or 2.

5. The cylindrical primary lithium battery according to claim 1 or 2, wherein the positive electrode has a current collector exposed portion where a part of the positive electrode current collector is exposed, and 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.

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 interposed therebetween is 0.25 mm ２ or more. The cylindrical primary lithium battery according to claim 5.

7. The cylindrical primary lithium battery according to claim 1 or 2, wherein the electrical insulating layer is an insulating tape.

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

9. The cylindrical primary lithium battery according to claim 8, wherein at least one selected from the group consisting of the lithium-containing metal sheet and the negative electrode lead and the short-circuiting metal sheet are electrically connected via a conductive adhesive layer.

10. Further including a negative electrode lead electrically connected to the battery case, in the pole-inverted state, a part of the lithium eluted from the lithium-containing metal sheet is deposited on the short-circuit metal sheet of the laminated portion, and the short-circuit metal sheet and the negative electrode lead are electrically connected by the deposited lithium. The cylindrical primary lithium battery according to claim 2.

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