Lithium primary battery and nonaqueous electrolyte for lithium primary battery

Abstract

A lithium primary battery has a positive electrode, a negative electrode, and a nonaqueous electrolyte. The positive electrode contains a positive electrode mixture containing LixMnO2 (0≤x≤0.05), and the negative electrode contains at least one of metallic lithium and a lithium alloy. The nonaqueous electrolyte contains at least one of a cyclic imide component and a pyrrole component as a first component, and contains an oxalato-phosphate complex component as a second component. The concentration of the first component in the nonaqueous electrolyte is 1 mass% or less, the concentration of the second component in the nonaqueous electrolyte is 6 mass% or less, and the mass ratio of the first component to the second component contained in the nonaqueous electrolyte is 0.02 or more and 10 or less.

Description

Technical Field

[0001] This application relates to non-aqueous electrolytes used in primary lithium batteries and primary lithium batteries using the same. Background Technology

[0002] Lithium-ion primary batteries have high energy density and low self-discharge, making them a popular power source for various electronic devices. A lithium-ion primary battery consists of a negative electrode containing metallic lithium, a positive electrode, and a non-aqueous electrolyte. In the positive electrode, fluorinated graphite, manganese dioxide, or thionyl chloride are used as active materials.

[0003] Patent document 1 proposes the use of a non-aqueous electrolyte containing additives such as phthalimide, based on the viewpoint of suppressing the increase in internal resistance of primary or secondary batteries when stored at high temperatures.

[0004] Patent Document 2 discloses an additive composition for an electrolyte used in non-aqueous storage devices, comprising a compound obtained by replacing at least one acid proton of a specific acid with a silyl group having three hydrocarbon groups. Patent Document 2 teaches that the above-mentioned additive suppresses gas generation in lithium-ion secondary batteries during use and prevents battery swelling.

[0005] As an electrolyte for electrochemical devices with high heat resistance and hydrolysis resistance, Patent Document 3 proposes an electrolyte containing LiB(C2O4)F2, etc.

[0006] Patent document 4 proposes using Li[P(C2O4)3], which is more stable than LiPF6, as a conductive salt in lithium-ion batteries.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: International Publication No. 01 / 41247 (Single Volume)

[0010] Patent Document 2: Japanese Patent Application Publication No. 2016-189327

[0011] Patent Document 3: Japanese Patent Application Publication No. 2002-110235

[0012] Patent Document 4: Japanese Patent No. 4695802 Summary of the Invention

[0013] With the increasing performance of electronic devices, high discharge performance is required for the lithium primary batteries used in their power supplies after high-temperature storage. Even when using non-aqueous electrolytes containing phthalimide in lithium primary batteries, the suppression of the increase in internal resistance during high-temperature storage is still insufficient, and the discharge performance may sometimes decrease after high-temperature storage.

[0014] The first aspect of this application relates to a lithium primary battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode comprises a positive electrode agent containing LixMnO2 (0≤x≤0.05), and the negative electrode comprises at least one of metallic lithium and a lithium alloy. The non-aqueous electrolyte comprises at least one of a cyclic imide component and a pyrrole component as a first component, and comprises an oxalate phosphate complex component as a second component. The concentration of the first component in the non-aqueous electrolyte is 1% by mass or less, the concentration of the second component in the non-aqueous electrolyte is 6% by mass or less, and the mass ratio of the first component to the second component in the non-aqueous electrolyte is 0.02 or more and 10 or less.

[0015] The second aspect of this application relates to a lithium primary battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode comprises a positive electrode compound containing LixMnO2 (0≤x≤0.05), and the negative electrode comprises at least one of metallic lithium and a lithium alloy. The non-aqueous electrolyte comprises at least one of a cyclic imide component and a pyrrole component as a first component, and comprises an oxalate phosphate complex component as a second component. The concentration of the first component in the non-aqueous electrolyte is 0.1% by mass or more and 1% by mass or less, and the concentration of the second component in the non-aqueous electrolyte is 0.1% by mass or more and 6% by mass or less.

[0016] A third aspect of this application relates to a non-aqueous electrolyte for a primary lithium battery, which is used in a primary lithium battery having a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode contains a positive electrode compound containing LixMnO2 (0≤x≤0.05), and the negative electrode contains at least one of metallic lithium and a lithium alloy. The non-aqueous electrolyte contains at least one of a cyclic imide component and a pyrrole component as a first component, and contains an oxalate phosphate complex component as a second component. The concentration of the first component in the non-aqueous electrolyte is 0.1% by mass or more and 1% by mass or less, and the concentration of the second component in the non-aqueous electrolyte is 0.1% by mass or more and 6% by mass or less.

[0017] According to this application, it is possible to suppress the increase in internal resistance of a primary lithium battery when stored at high temperatures. Attached Figure Description

[0018] Figure 1 This is a front view obtained by cross-section of a portion of the lithium primary battery described in an embodiment of this application. Detailed Implementation

[0019] A primary lithium battery comprises a positive electrode containing LixMnO2 (0≤x≤0.05), a negative electrode containing at least one of metallic lithium and lithium alloy, and a non-aqueous electrolyte. In this battery, when the non-aqueous electrolyte contains cyclic imide components, the increase in internal resistance can be suppressed to some extent during high-temperature storage compared to when the non-aqueous electrolyte does not contain cyclic imide components, but it is still insufficient, and the discharge capacity may sometimes decrease after high-temperature storage.

[0020] The lithium primary battery of this application comprises a positive electrode containing a positive electrode mixture containing LixMnO2 (0≤x≤0.05), a negative electrode containing at least one of metallic lithium and lithium alloy, and a non-aqueous electrolyte. The non-aqueous electrolyte contains at least one of a cyclic imide component and a pyrrole component as a first component, and contains an oxalate phosphate complex component as a second component. In this lithium primary battery, the non-aqueous electrolyte satisfies at least one of the following conditions (a) and (b).

[0021] (a) The concentration of the first component in the non-aqueous electrolyte is 1% by mass or less, the concentration of the second component in the non-aqueous electrolyte is 6% by mass or less, and the mass ratio of the first component to the second component in the non-aqueous electrolyte (first component / second component) is 0.02 or more and 10 or less.

[0022] (b) The concentration of the first component in the non-aqueous electrolyte is 0.1% by mass or more and 1% by mass or less, and the concentration of the second component in the non-aqueous electrolyte is 0.1% by mass or more and 6% by mass or less.

[0023] According to this application, the lithium primary battery, by possessing the aforementioned non-aqueous electrolyte, significantly suppresses the increase in internal resistance when the lithium primary battery is stored at high temperatures, and suppresses the decrease in discharge capacity after high-temperature storage, even though the non-aqueous electrolyte contains cyclic imide components. This effect in this application can be attributed to the following reasons.

[0024] When a non-aqueous electrolyte contains cyclic imides but not oxalate-phosphate complexes, the increase in internal resistance can be suppressed to some extent during storage compared to the case without either cyclic imides or oxalate-phosphate complexes. However, the discharge capacity decreases significantly after high-temperature storage. This can be attributed to the following: the cyclic imides are oxidized on the surface of the positive electrode, forming a low-conductivity lithium-ion coating derived from the cyclic imides, thus hindering lithium-ion movement at the interface between the positive electrode and the electrolyte. Furthermore, self-discharge of the positive electrode occurs due to the oxidation of the cyclic imides, resulting in a decrease in discharge capacity after storage. In particular, prolonged storage of primary lithium batteries at high temperatures promotes coating growth and self-discharge on the positive electrode, leading to a significant reduction in discharge capacity after storage.

[0025] When a non-aqueous electrolyte contains oxalate-phosphate complex but lacks cyclic imide components, it can suppress the increase in internal resistance to some extent during storage, but not sufficiently, compared to solutions lacking both oxalate-phosphate complex and cyclic imide components. Furthermore, coatings containing components derived from oxalate-phosphate complex have low thermal stability and undergo side reactions during high-temperature storage. Consequently, the discharge capacity may sometimes decrease after high-temperature storage. Additionally, a large amount of gas may be generated during storage.

[0026] In contrast, compared to cases where neither cyclic imide nor oxalate phosphate complex is present, the lithium primary battery of this application exhibits exceptionally strong suppression of internal resistance rise during high-temperature storage. In the lithium primary battery of this application, compared to cases where the non-aqueous electrolyte contains either cyclic imide or oxalate phosphate complex, the increase in internal resistance during high-temperature storage is significantly suppressed compared to expectations. Therefore, when the non-aqueous electrolyte satisfies at least one of the conditions in (a) and (b) above, a synergistic effect achieved by the cyclic imide and oxalate phosphate complex can be said to be obtained in suppressing the increase in internal resistance during high-temperature storage. The reason why the lithium primary battery of this application can exceptionally suppress the increase in internal resistance during high-temperature storage may not be immediately clear, but it can be considered as follows. It can be considered that when the cyclic imide component at the positive electrode surface decomposes to form a coating, the oxalate phosphate complex component is also involved in the decomposition reaction, forming a coating containing components derived from both the cyclic imide component and the oxalate phosphate complex component. Unlike coatings containing only components derived from the cyclic imide component, this type of coating is chemically and thermally stable. By forming this coating, side reactions caused by contact between the positive electrode and the non-aqueous electrolyte are less likely to occur during high-temperature storage, significantly suppressing the increase in internal resistance caused by side reactions and thus preventing a decrease in discharge capacity due to the increase in internal resistance. Furthermore, gas generation during storage is also suppressed. Therefore, the coating containing components derived from both the cyclic imide component and the oxalate phosphate complex component exhibits excellent lithium-ion conductivity, which is advantageous for reducing internal resistance. The coating is dense and has low electronic conductivity. Therefore, during the initial stage of battery assembly, the coating forms on the positive electrode surface, and the cyclic imide component is less prone to oxidation, thus mitigating the aggravation of positive electrode reduction. This reduces self-discharge during the storage of lithium primary batteries. Therefore, it can be concluded that by using an electrolyte containing both cyclic imide and oxalate-phosphate complex components, the increase in internal resistance during high-temperature storage can be significantly suppressed, and the decrease in discharge capacity after storage can be prevented.

[0027] When the first component is pyrrole, the same effect is obtained as when the first component is a cyclic imide. It can be considered that when the first component is pyrrole, a coating containing both pyrrole and oxalate phosphate complex components is formed. This coating is chemically and thermally stable, and has excellent lithium-ion conductivity, which can significantly suppress the increase in internal resistance during high-temperature storage.

[0028] This application also includes a non-aqueous electrolyte for use in a primary lithium battery having a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein the positive electrode comprises a positive electrode compound containing LixMnO2 (0≤x≤0.05), and the negative electrode comprises at least one of metallic lithium and a lithium alloy. Here, the non-aqueous electrolyte comprises a first component and a second component. The non-aqueous electrolyte satisfies the condition in (b) above. Furthermore, this application also includes the use of this non-aqueous electrolyte in a primary lithium battery having a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein the positive electrode comprises a positive electrode compound containing LixMnO2 (0≤x≤0.05), and the negative electrode comprises at least one of metallic lithium and a lithium alloy.

[0029] The lithium primary battery of this application will be described in more detail below.

[0030] [Lithium primary battery]

[0031] (positive electrode)

[0032] The positive electrode contains a positive electrode additive. The positive electrode additive contains a positive electrode active material. Manganese dioxide is an example of a positive electrode active material. Positive electrodes containing manganese dioxide exhibit higher voltage and excellent pulse discharge characteristics. Manganese dioxide can be in a mixed crystal state, including various crystalline states. The positive electrode may contain manganese oxides other than manganese dioxide. Examples of manganese oxides other than manganese dioxide include MnO, Mn3O4, Mn2O3, and Mn2O7. Manganese dioxide is preferably the main component of the manganese oxides contained in the positive electrode.

[0033] Lithium can be doped into a portion of the manganese dioxide contained in the positive electrode. A small amount of lithium doping ensures high capacity. Manganese dioxide and manganese dioxide doped with a small amount of lithium can be represented as LixMnO2 (0≤x≤0.05). It should be noted that the overall average composition of the manganese oxides contained in the positive electrode only needs to be LixMnO2 (0≤x≤0.05). It should also be noted that the Li ratio x only needs to be below 0.05 in the initial discharge state of the lithium primary battery. The Li ratio x typically increases as the lithium primary battery discharges. Theoretically, the oxidation number of manganese contained in manganese dioxide is tetravalent. However, by including other manganese oxides in the positive electrode or doping manganese dioxide with lithium, the oxidation number of manganese can sometimes slightly increase or decrease compared to tetravalent. Therefore, for LixMnO2, a slight increase or decrease in the average oxidation number of manganese compared to tetravalent is acceptable.

[0034] The positive electrode may contain LixMnO2, as well as other positive electrode active materials used in primary lithium batteries. Examples of other positive electrode active materials include fluorinated graphite. From the viewpoint that it is easy to achieve the effect of using a non-aqueous electrolyte that satisfies the conditions in (a) or (b) above, the proportion of LixMnO2 in the total positive electrode active material is preferably 90% by mass or more.

[0035] Electrolytic manganese dioxide is suitable as a form of manganese dioxide. Depending on the requirements, electrolytic manganese dioxide obtained by undergoing at least any of the following treatments: neutralization, cleaning, and calcination can be used.

[0036] Electrolytic manganese dioxide is typically obtained by electrolyzing an aqueous solution of manganese sulfate. Therefore, electrolytic manganese dioxide inevitably contains sulfate ions. The cathode mixture prepared using this electrolytic manganese dioxide inevitably contains sulfur atoms. The amount of sulfur atoms in the cathode mixture can be between 0.05 and 3 parts by mass per 100 parts by mass of manganese atoms. It can be considered that, with sulfur atoms in this range, in a lithium primary battery, sulfate ions react with lithium atoms to form lithium... x The unstable M generated by the embedding in MnO2 3+ An interaction occurs, which can inhibit the action of Mn 3+ Mn disproportionation 2+ The generation of Mn can be considered as follows: This can suppress the generation of Mn. 2+The process involves dissolution into the non-aqueous electrolyte and precipitation of Mn at the negative electrode. As a result, both high capacity and high reliability of the primary lithium battery can be ensured. On the other hand, in secondary lithium batteries, some sulfate ions are decomposed during charging; therefore, even if the positive electrode mixture contains sulfate in an amount of sulfur atoms within the aforementioned range, it is difficult to sufficiently ensure the aforementioned effect. The proportion of sulfur atoms in the positive electrode mixture can be adjusted by regulating the conditions of the cleaning and neutralization processes. Examples of cleaning processes include at least one of water washing and acid-based cleaning. As a neutralizing agent used in the neutralization process, inorganic bases such as ammonia or hydroxides can be used.

[0037] Adjusting the conditions during electrolytic synthesis can increase the crystallinity of manganese dioxide and decrease its specific surface area. The BET specific surface area of ​​LixMnO2 can reach 10 m². 2 / g or more and 40m 2 Below / g. With the BET specific surface area of ​​LixMnO2 in this range, a higher self-discharge suppression effect can be obtained in lithium primary batteries. Furthermore, a positive electrode additive layer can be easily formed.

[0038] The BET specific surface area of ​​LixMnO2 can be determined using well-known methods, such as a specific surface area measuring device (e.g., manufactured by MOUNTECH) and the BET method. For example, LixMnO2 separated from the positive electrode of a battery can be used as the test sample.

[0039] The central particle size of LixMnO2 can be above 10 μm and below 40 μm. When the central particle size is within this range, the effect of suppressing self-discharge in lithium primary batteries is further improved, and high current-collecting capacity in the positive electrode is easily ensured.

[0040] The median particle size of LixMnO2 is, for example, the median of the particle size distribution determined using quantitative laser diffraction-scattering (qLD) method. For example, LixMnO2 separated from the positive electrode of a battery can be used as the sample for measurement. In the measurement, for example, a SALD-7500 nano-type laser manufactured by Shimadzu Corporation is used.

[0041] In addition to containing positive electrode active materials, positive electrode binders can also be included. Positive electrode binders may also contain conductive agents.

[0042] Examples of adhesives include fluoropolymers, rubber particles, and acrylic resins.

[0043] Examples of conductive agents include conductive carbon materials. Examples of conductive carbon materials include natural graphite, artificial graphite, carbon black, and carbon fiber.

[0044] The positive electrode may further include a positive current collector for retaining the positive electrode mixture. Examples of materials that can be used as the positive current collector include stainless steel, aluminum, and titanium.

[0045] In the case of a coin-shaped battery, the positive electrode can be formed by mounting an L-shaped annular positive current collector onto the positive electrode compound granules, or the positive electrode can be formed using only the positive electrode compound granules. The positive electrode compound granules can be obtained, for example, by adding an appropriate amount of water to the positive electrode active material and additives, compressing the thus prepared wet positive electrode compound into shape, and then drying it.

[0046] In the case of a cylindrical battery, a positive electrode comprising a sheet-like positive current collector and a positive electrode binder layer held in the positive current collector can be used. The sheet-like positive current collector is preferably a porous current collector. Examples of porous current collectors include metal mesh, mesh structures, and perforated metal. The positive electrode binder layer can be obtained, for example, by coating or filling the sheet-like positive current collector with the aforementioned wetted positive electrode binder, applying pressure in the thickness direction, and then drying.

[0047] The positive electrode preferably comprises a porous current collector as described above and a positive electrode mixture filling the current collector. Preferably, a current collector comprising at least one material selected from the group consisting of SUS444, SUS430, and SUS316 is used. By using such a current collector, side reactions between the non-aqueous electrolytes in the lithium primary battery and corrosion of the current collector can be suppressed, as well as the increase in internal resistance and gas generation. In particular, when such a current collector is combined with a non-aqueous electrolyte comprising at least one of LiCF3SO3 and LiClO4, typically used in lithium primary batteries, as a lithium salt, side reactions between the current collector and the non-aqueous electrolyte can be suppressed more effectively. The thickness of the positive electrode is, for example, 300 μm or more and 900 μm or less. When using a positive electrode of this thickness, there is a tendency for reduced diffusion of the non-aqueous electrolyte in the positive electrode mixture, and the reduction of the positive electrode associated with the oxidation of the solvent or cyclic imide component (first component) is suppressed; therefore, self-discharge can be suppressed. It should be noted that in primary lithium batteries, discharge usually occurs over a long period of time at a low rate, therefore, the resistance rise is acceptable when the thickness of the positive electrode is within this range.

[0048] (negative electrode)

[0049] The negative electrode can contain metallic lithium or a lithium alloy, or both metallic lithium and lithium metal. For example, a composite containing metallic lithium and a lithium alloy can be used as the negative electrode.

[0050] Examples of lithium alloys include Li-Al alloys, Li-Sn alloys, Li-Ni-Si alloys, and Li-Pb alloys. From the viewpoint of ensuring discharge capacity and stabilizing internal resistance, the content of metal elements other than lithium in the lithium alloy is preferably set to 0.05–15% by mass.

[0051] Lithium metal, lithium alloys, or their composites are shaped into any shape and thickness according to the shape, size, standard performance, etc. of a primary lithium battery.

[0052] In the case of a coin-shaped battery, ring-shaped metallic lithium, lithium alloys, or their composites can be punched into a circular plate shape and used as the negative electrode. In the case of a cylindrical battery, sheets of metallic lithium, lithium alloys, or their composites can be used as the negative electrode. The sheets are obtained, for example, by extrusion molding. More specifically, in a cylindrical battery, foils of metallic lithium or lithium alloys having shapes having both a length direction and a width direction are used.

[0053] In the case of a cylindrical battery, a strip of adhesive tape can be adhered along its length to at least one main surface of the negative electrode. This tape comprises a resin substrate and an adhesive layer. The main surface refers to the surface opposite the positive electrode. The width of the tape can be, for example, 0.5 mm or more and 3 mm or less. This tape prevents the negative electrode foil from breaking and causing poor current collection when the lithium component of the negative electrode is consumed due to reaction at the end of discharge. Poor current collection leads to a decrease in battery capacity. However, the adhesive strength of the tape decreases due to the electrolyte during long-term storage. When using an electrolyte containing a first component and a second component, this decrease in adhesive strength can be suppressed, and foil breakage and poor current collection can be prevented more effectively.

[0054] Materials used as resin base materials include, for example, fluororesins, polyimides, polyphenylene sulfide, polyethersulfone, polyethylene, polypropylene, and other polyolefins, as well as polyethylene terephthalate. Among these, polyolefins are preferred, and polypropylene is more preferred.

[0055] The adhesive layer comprises at least one component selected from, for example, a rubber component, a silicone component, and an acrylic resin component. Specifically, as the rubber component, synthetic rubber, natural rubber, etc., can be used. Examples of synthetic rubbers include butyl rubber, butadiene rubber, styrene-butadiene rubber, isoprene rubber, chloroprene rubber, polyisobutylene, acrylonitrile-butadiene rubber, styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butadiene block copolymer, etc. As the silicone component, organic compounds having a polysiloxane structure, silicone polymers, etc., can be used. Examples of silicone polymers include peroxide-cured silicones, addition-reaction silicones, etc. As an acrylic resin component, polymers containing acrylic monomers such as acrylic acid, methacrylic acid, acrylates, and methacrylates can be used. Examples include homopolymers or copolymers of acrylic monomers such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, octyl acrylate, octyl methacrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate. It should be noted that the adhesive layer may contain crosslinking agents, plasticizers, and thickeners.

[0056] (Non-aqueous electrolyte)

[0057] The non-aqueous electrolyte comprises, for example, a first component (at least one of a cyclic imide component and a pyrrole component) and a second component (oxalate phosphate complex component), and a non-aqueous solvent in which they are dissolved. The non-aqueous electrolyte contains a lithium salt or lithium ions. At least one of the first and second components can be a lithium salt or be capable of generating lithium ions. Additionally, the non-aqueous electrolyte may contain lithium salts other than the first and second components.

[0058] (Oxalate phosphate complex components)

[0059] The oxalate-phosphate complex component only needs to have a structure capable of generating the anion shown in formula (1) below. In formula (1), * represents a connecting bond. The non-aqueous electrolyte may contain one or more of the oxalate-phosphate complex components.

[0060]

[0061] The oxalate phosphate complex can be contained in any form, either as an acid (or anion) or a salt, in the non-aqueous electrolyte. The oxalate phosphate complex only needs to generate at least an oxalate phosphate complex anion in the non-aqueous electrolyte. The oxalate phosphate complex can be a salt formed by the oxalate phosphate complex anion and a cation contained in the non-aqueous electrolyte.

[0062] In the oxalate phosphate complex, a phosphorus atom only needs to be coordinated with at least one oxalate ligand, or it can be coordinated with two or three oxalate ligands.

[0063] The oxalate phosphate complex can have a structure in which one oxalate ligand and four halogen atoms are coordinated to one phosphorus atom. The oxalate phosphate complex with this structure can generate the anion shown in formula (2).

[0064]

[0065] In equation (2), X 1 ~X 4 These are halogen atoms. Examples of halogen atoms that are coordinated to phosphorus atoms include fluorine and chlorine atoms.

[0066] In addition, the oxalate phosphate complex can have a structure in which two oxalate ligands and two halogen atoms are coordinated on one phosphorus atom. The oxalate phosphate complex with this structure can generate the anion shown in formula (3) below.

[0067]

[0068] In equation (3), X 5 and X 6 These are halogen atoms. Examples of halogen atoms that are coordinated to phosphorus atoms include fluorine and chlorine atoms.

[0069] As components of oxalate phosphate complexes, tetrafluoro(oxalate) phosphate complexes, difluorobis(oxalate) phosphate complexes, and tri(oxalate) phosphate complexes are suitable. Among them, lithium tetrafluoro(oxalate) phosphate, lithium difluorobis(oxalate) phosphate, and lithium tri(oxalate) phosphate are preferred as components of oxalate phosphate complexes.

[0070] The tetrafluoro(oxalate)phosphate complex has a structure with one oxalate ligand and four fluorine atoms coordinated to one phosphorus atom. The difluorobis(oxalate)boronic acid complex has a structure with two oxalate ligands and two fluorine atoms coordinated to one phosphorus atom. The tri(oxalate)phosphate complex has a structure with three oxalate ligands coordinated to one phosphorus atom and can generate the anion shown in formula (4).

[0071]

[0072] When the non-aqueous electrolyte meets the conditions in (a) above, the concentration of the oxalate-phosphate complex in the non-aqueous electrolyte is 6% by mass or less, specifically 5.5% by mass or less, or 5% by mass or less. If the concentration of the oxalate-phosphate complex exceeds 6% by mass, a side reaction will occur during high-temperature storage, resulting in a decrease in discharge capacity after storage. The concentration of the oxalate-phosphate complex in the non-aqueous electrolyte only needs to be above the detection limit, specifically 0.1% by mass or more, or 0.5% by mass or more. These upper and lower limits can be combined arbitrarily.

[0073] During the storage or discharge of a lithium primary battery, the oxalate-phosphate complex component is consumed within the battery by processes such as coating formation, causing changes in the concentration of the oxalate-phosphate complex component in the non-aqueous electrolyte. The concentration of the oxalate-phosphate complex component in the non-aqueous electrolyte used in battery assembly or manufacturing is preferably 0.1% by mass or more, more preferably 0.5% by mass or more. In this case, the increase in internal resistance during high-temperature storage can be significantly suppressed. It is preferable to set the concentration of the oxalate-phosphate complex component in the non-aqueous electrolyte used in battery assembly or manufacturing to 5.5% by mass or less, or 5% by mass or less. In this case, capacity reduction after high-temperature storage is easily suppressed. These lower and upper limits can be combined arbitrarily.

[0074] When the non-aqueous electrolyte meets the conditions in (b) above, the concentration of the oxalate-phosphate complex in the non-aqueous electrolyte only needs to be 0.1% by mass or more and 6% by mass or less. It can be 0.1% by mass or more and 5.5% by mass or less, or 0.5% by mass or more and 5.5% by mass or less, or 1% by mass or more and 5% by mass or less. When the concentration of the oxalate-phosphate complex is within this range, it is easy to suppress the increase in internal resistance during high-temperature storage, and the capacity reduction after high-temperature storage can be significantly suppressed.

[0075] As described above, the oxalate phosphate complex component can be contained in the non-aqueous electrolyte in the form of an acid (or anion). In this specification, the concentration or mass-based amount of the oxalate phosphate complex component in the non-aqueous electrolyte is set as the concentration of the lithium salt of the oxalate phosphate complex or a value obtained by conversion based on mass.

[0076] (Cyclic imide component)

[0077] Examples of cyclic imide components include cyclic diacylamines. A cyclic imide component only needs to possess a diacylamine ring (or, more specifically, an imide ring). The imide ring can condense with other rings (also called a second ring). Non-aqueous electrolytes may contain one or more cyclic imide components. Cyclic imide components in non-aqueous electrolytes may be contained in the form of imides, anions, or salts. When cyclic imide components are contained in the form of imides in non-aqueous electrolytes, they may be contained in the form of free NH groups or in the form of tertiary amines.

[0078] Examples of second rings include aromatic rings, saturated or unsaturated aliphatic rings, etc. The second ring may contain at least one heteroatom. Examples of heteroatoms include oxygen atoms, sulfur atoms, and nitrogen atoms.

[0079] Examples of cyclic imides constituting cyclic imides include, for example, aliphatic dicarboxylic acid imides and cyclic imides having a second ring. Examples of aliphatic dicarboxylic acid imides include succinimides. Examples of cyclic imides having a second ring include imides of aromatic or alicyclic dicarboxylic acids. Examples of aromatic or alicyclic dicarboxylic acids include dicarboxylic acids having carboxyl groups on the two adjacent atoms constituting the ring. Examples of cyclic imides having a second ring include phthalimides and hydrogenated forms of phthalimides. Examples of hydrogenated forms of phthalimides include cyclohexyl-3-ene-1,2-dicarboxamide and cyclohexane-1,2-dicarboxamide.

[0080] The imide ring can be an N-substituted imide ring with a substituent on the nitrogen atom of the imide. Examples of such substituents include hydroxyl, alkyl, alkoxy, and halogen atoms. Examples of alkyl groups include, for instance, C... 1-4 Alkyl groups can be methyl, ethyl, etc. Examples of alkoxy groups include C0. 1-4 Alkoxy groups can be methoxy, ethoxy, etc. Halogen atoms can be chlorine, fluorine, etc.

[0081] Among the cyclic imide components, phthalimide and N-substituted phthalimide are more preferred. The substituent on the nitrogen atom of the N-substituted phthalimide can be selected from substituents exemplified with respect to the N-substituted imide ring. It is further preferred to use a cyclic imide component that contains at least phthalimide.

[0082] (Pyrrole component)

[0083] The pyrrole component only needs to contain pyrrole and its derivatives and have a pyrrole ring. The non-aqueous electrolyte may contain one or more pyrrole components. In the non-aqueous electrolyte, the pyrrole component can be contained in the pyrrole state, or in the form of anions or salts. When the pyrrole component is contained in the non-aqueous electrolyte in the pyrrole state, it can be contained in the form of a free NH group or in the form of a tertiary amine.

[0084] The pyrrole ring can be an N-substituted pyrrole ring having a substituent on the nitrogen atom of the pyrrole. Such a substituent can be selected from the substituents exemplified in the above-described N-substituted imide rings.

[0085] The pyrrole ring can condense with other rings (also called second rings). Examples of second rings include aromatic rings, saturated or unsaturated aliphatic rings, etc. The second ring may contain at least one heteroatom. Examples of heteroatoms include oxygen atoms, sulfur atoms, and nitrogen atoms, etc. Examples of pyrrole components having a second ring include, for example, indole, N-substituted indole, isoindole, N-substituted isoindole, porphyrin, N-substituted porphyrin, etc. The substituent on the nitrogen atom of N-substituted indole, etc., can be selected from the substituents exemplified in the above-described N-substituted imide rings.

[0086] When the non-aqueous electrolyte meets the conditions in (a) above, the mass ratio of the first component to the second component in the non-aqueous electrolyte is 0.02 or more and 10 or less, or it can be 0.02 or more and 7 or less, or 0.02 or more and 5 or less, or 0.1 or more and 5 or less. When the mass ratio is within this range, it is easy to further form a high-quality coating with excellent lithium-ion conductivity, chemical stability, and thermal stability on the positive electrode surface. Therefore, the increase in internal resistance during high-temperature storage can be significantly suppressed.

[0087] The concentration of the first component in the non-aqueous electrolyte is 1% by mass or less, specifically 0.7% by mass or less, or 0.5% by mass or less. At this concentration range, the increase in internal resistance during high-temperature storage and the decrease in capacity after storage can be further suppressed. The concentration of the first component in the non-aqueous electrolyte only needs to be above the detection limit, specifically 0.1% by mass or more, or 0.3% by mass or more. These upper and lower limits can be combined arbitrarily.

[0088] If the concentration of the first component in the non-aqueous electrolyte exceeds 1% by mass, a coating with low lithium-ion conductivity will form on the positive electrode surface during high-temperature storage, resulting in a decrease in discharge capacity after high-temperature storage.

[0089] During battery storage or discharge, the first component is consumed within the battery by processes such as coating formation, causing changes in the concentration of the first component in the non-aqueous electrolyte. The concentration of the first component in the non-aqueous electrolyte used in battery assembly or manufacturing is preferably 0.1% by mass or more, or 0.3% by mass or more. In this case, the increase in internal resistance during high-temperature storage is easily and effectively suppressed. Furthermore, the concentration of the first component in the non-aqueous electrolyte used in battery assembly or manufacturing is preferably 1% by mass or less, or 0.7% by mass or less. In this case, capacity reduction after high-temperature storage can be significantly suppressed.

[0090] When the non-aqueous electrolyte meets the conditions in (b) above, the concentration of the first component in the non-aqueous electrolyte only needs to be 0.1% by mass or more and 1% by mass or less, or it can be 0.3% by mass or more and 1% by mass or less, or 0.3% by mass or more and 0.7% by mass or less. When the concentration of the first component is within this range, it is easy to significantly suppress the increase in internal resistance during high-temperature storage and to significantly suppress the capacity reduction after storage.

[0091] Furthermore, the mass ratio of the first component to the second component in the non-aqueous electrolyte can be 0.02 or more and 10 or less, 0.02 or more and 7 or less, 0.02 or more and 5 or less, or 0.1 or more and 5 or less. Within this mass ratio range, it is easy to effectively suppress the increase in internal resistance during high-temperature storage, and further suppress capacity reduction after storage.

[0092] The first component may be contained in the non-aqueous electrolyte in the form of a salt. In this specification, the concentration or mass-based amount of the first component in the non-aqueous electrolyte is set as the concentration of the first component having free NH groups or a value obtained by conversion based on mass-based amounts.

[0093] In the analysis of non-aqueous electrolytes (first and second components), methods such as liquid chromatography-mass spectrometry (LC / MS) can be used, or mass spectrometry (MS) and ultraviolet spectroscopy (UV) can be performed simultaneously.

[0094] (Non-aqueous solvent)

[0095] As non-aqueous solvents, examples of organic solvents commonly used in non-aqueous electrolytes for primary lithium batteries include ethers, esters, and carbonates. Other non-aqueous solvents that can be used include dimethyl ether, γ-butyrolactone, propylene carbonate, ethylene carbonate, and 1,2-dimethoxyethane. Non-aqueous electrolytes may contain one or more non-aqueous solvents.

[0096] From the viewpoint of improving the discharge characteristics of lithium primary batteries, the non-aqueous solvent preferably comprises a cyclic carbonate with a high boiling point and a chain ether with low viscosity at low temperatures. The cyclic carbonate preferably comprises at least one selected from the group consisting of propylene carbonate (PC) and ethylene carbonate (EC), with PC being particularly preferred. The chain ether preferably has a viscosity of less than 1 mPa·s at 25°C, and dimethoxyethane (DME) is particularly preferred. It should be noted that the viscosity of the non-aqueous solvent is determined using a micro-sample viscometer m-VROC manufactured by Rheosense, by measuring a shear rate of 10000 (1 / s) at 25°C.

[0097] (Lithium salt)

[0098] Non-aqueous electrolytes may contain lithium salts other than oxalate-phosphate complexes and cyclic imides. Examples of lithium salts include those used as solutes in primary lithium batteries. Examples of such lithium salts include LiCF3SO3, LiClO4, LiBF4, LiPF6, LiRaSO3 (Ra is a fluoroalkyl group with 1 to 4 carbon atoms), LiFSO3, LiN(SO2Rb)(SO2Rc) (Rb and Rc are each independently a fluoroalkyl group with 1 to 4 carbon atoms), LiN(FSO2)2, LiPO2F2, LiB(C2O4)2, and LiBF2(C2O4). Non-aqueous electrolytes may contain one or more of these lithium salts.

[0099] (other)

[0100] The concentration of lithium ions (total concentration of lithium salts) in the non-aqueous electrolyte is, for example, 0.2–2.0 mol / L, or 0.3–1.5 mol / L.

[0101] Non-aqueous electrolytes may contain additives as needed. Examples of such additives include propanesulfonate lactone and vinylene carbonate. The total concentration of such additives in the non-aqueous electrolyte is, for example, 0.003–5 mol / L.

[0102] (Separator)

[0103] Lithium-ion primary batteries typically have a separator sandwiched between the positive and negative electrodes. This separator can be a porous sheet made of an insulating material resistant to the internal environment of the lithium-ion primary battery. Specifically, examples include nonwoven fabrics made of synthetic resin, microporous membranes made of synthetic resin, or laminates thereof.

[0104] Examples of synthetic resins used in nonwoven fabrics include polypropylene, polyphenylene sulfide, and polybutylene terephthalate. Examples of synthetic resins used in microporous membranes include polyethylene, polypropylene, and polyolefin resins such as ethylene-propylene copolymer. Microporous membranes may contain inorganic particles as needed.

[0105] The thickness of the separator is, for example, 5 μm or more and 100 μm or less.

[0106] There are no particular limitations on the structure of a primary lithium battery. A primary lithium battery can be a coin-shaped battery with a stacked electrode assembly, wherein the stacked electrode assembly consists of a circular plate-shaped positive electrode and a circular plate-shaped negative electrode separated by a separator. Alternatively, it can be a cylindrical battery with a wound electrode assembly, wherein the wound electrode assembly consists of a strip-shaped positive electrode and a strip-shaped negative electrode wound into a spiral shape separated by a separator.

[0107] Figure 1 This is a front view obtained by cross-section of a portion of a cylindrical primary lithium battery according to one embodiment of this application. In the primary lithium battery 10, an electrode assembly, formed by winding a positive electrode 1 and a negative electrode 2 with a separator 3 in between, is housed together with a non-aqueous electrolyte within a battery casing 9. A sealing plate 8 is installed at the opening of the battery casing 9. A positive electrode lead 4, connected to the current collector 1a of the positive electrode 1, is connected to the sealing plate 8. A negative electrode lead 5, connected to the negative electrode 2, is connected to the casing 9. In addition, to prevent internal short circuits, an upper insulating plate 6 and a lower insulating plate 7 can be respectively arranged at the upper and lower parts of the electrode assembly.

[0108] Example

[0109] The present application will now be described in detail with reference to embodiments and comparative examples. However, the present application is not limited to the embodiments described below.

[0110] Examples 1-10 and Comparative Examples 4-6

[0111] (The production of the positive electrode)

[0112] As the positive electrode, 5 parts by mass of Ketjen black as a conductive agent, 5 parts by mass of polytetrafluoroethylene as a binder, and an appropriate amount of pure water are added to 100 parts by mass of electrolytic manganese dioxide and mixed to prepare a wet positive electrode mixture.

[0113] Next, the positive electrode filler is filled into a positive electrode current collector made of stainless steel (SUS444) mesh with a thickness of 0.1 mm to create the positive electrode precursor. The precursor is then dried and rolled using a roller press until it reaches a thickness of 0.4 mm. It is then cut into sheets 2.2 cm long and 1.5 cm wide to obtain the positive electrode. Next, SUS444 tabs are resistance-welded to the portion of the positive electrode current collector exposed by peeling off a portion of the filled positive electrode filler.

[0114] (Making the negative electrode)

[0115] The negative electrode is obtained by cutting a 300μm thick lithium foil into dimensions 4cm long and 2.5cm wide. Nickel tabs are then connected to designated locations on the negative electrode via crimping.

[0116] (Fabrication of the electrode assembly)

[0117] The electrode assembly is fabricated by winding a separator around the positive electrode and overlapping it with the negative electrode. The separator is a microporous membrane made of polypropylene with a thickness of 25 μm.

[0118] (Preparation of non-aqueous electrolytes)

[0119] PC, EC, and DME were mixed in a volume ratio of 4:2:4. LiCF3SO3 was dissolved in the resulting mixture to a concentration of 0.5 mol / L, ensuring that the first and second components shown in Tables 1 and 2 were dissolved at the concentrations indicated in Tables 1 and 2. This process was used to prepare the non-aqueous electrolyte. It should be noted that for the second component in Tables 1 and 2, LiDFOP is lithium difluorobis(oxalate)phosphate, LiTFOP is lithium tetrafluoro(oxalate)phosphate, and LiTOP is lithium tri(oxalate)phosphate.

[0120] (Assembly of a primary lithium battery)

[0121] The electrode assembly was housed in a cylindrical aluminum laminate bag, 9 cm long and 6 cm wide, with a portion of the tab leads connected to the positive and negative electrodes protruding from the bag. The opening on the tab lead side was sealed. 0.5 mL of electrolyte was injected through the opening on the opposite side of the tab leads, and the opening was sealed by vacuum heat sealing. This process was used to fabricate a test lithium primary battery. The designed capacity of the lithium primary battery was 308 mAh / g (capacity per unit mass of positive electrode active material). It should be noted that in Tables 1 and 2, A1–A10 are batteries from Examples 1–10, and B1–B6 are batteries from Comparative Examples 1–6.

[0122] It should be noted that in the lithium primary battery of the embodiment, the amount of sulfur atoms derived from sulfate in the positive electrode mixture is 0.05 parts by mass or more and 1.25 parts by mass or less per 100 parts by mass of manganese atoms in the positive electrode mixture. In the lithium primary battery of the embodiment, the central particle size of LixMnO2 contained in the positive electrode is 25 μm to 27 μm, and the BET specific surface area is 15 to 20 m². 2 / g.

[0123] Comparative Example 1

[0124] Except that the non-aqueous electrolyte does not contain the first component, the battery B1 of Comparative Example 1 was prepared in the same manner as the battery A1 of Example 1.

[0125] Comparative Example 2

[0126] Except that the non-aqueous electrolyte does not contain a second component, the battery B2 of Comparative Example 2 was prepared in the same manner as the battery A1 of Example 1.

[0127] Comparative Example 3

[0128] Except that the non-aqueous electrolyte does not contain the first and second components, the battery B3 of Comparative Example 3 was prepared in the same manner as the battery A1 of Example 1.

[0129] For batteries A1 to A4 and batteries B1 to B3, the following procedure was performed to measure the rate of increase in internal resistance after high-temperature storage.

[0130] [Evaluation 1: Rate of increase in internal resistance after high-temperature storage]

[0131] For the newly assembled battery, after discharging it to a capacity equivalent to 2.5% of the design capacity, it was stored at 60°C for 3 days, and the internal resistance R0 of the stored battery was measured. Subsequently, the battery was stored at 70°C for 1 week. For the battery stored at 70°C for 1 week, the internal resistance R1 was measured. It should be noted that the internal resistance was determined by measuring the AC resistance (ACR) using the two-terminal method at 25°C. The AC current measurement frequency was set to 1kHz.

[0132] Using R0 and R1 as described above, the rate of increase (%) of the internal resistance can be calculated according to the following formula.

[0133] Rate of increase of internal resistance = (R1 - R0) / R0 × 100

[0134] It should be noted that in Table 1, the rate of increase in internal resistance is expressed as a relative value when the rate of increase in internal resistance of battery B2 in Comparative Example 2 is set to 100. The smaller the rate of increase in internal resistance, the better the increase in internal resistance after storage can be suppressed.

[0135] For batteries A1-A3, A5-A10 and B2-B6, the capacity reduction rate after high-temperature storage was measured as follows.

[0136] [Evaluation 2: Capacity reduction rate after high-temperature storage]

[0137] The newly assembled battery was discharged to a capacity equivalent to 2.5% of its design capacity (C0) and then stored at 60°C for 3 days. The stored battery was then discharged at 25°C with a current of 4.5 mA per unit mass (g) of manganese dioxide until the battery voltage reached 2V. The discharge capacity C1 (mAh / g) at this point was calculated.

[0138] Using C0 and C1 above, the capacity reduction rate (%) is calculated according to the following formula.

[0139] Capacity reduction rate = (C0-C1) / C0×100

[0140] It should be noted that in Table 2, the capacity reduction rate is expressed as a relative value when the capacity reduction rate of battery B3 in Comparative Example 3 is set to 100. The smaller the capacity reduction rate, the better the capacity reduction after storage can be suppressed.

[0141] The evaluation results are shown in Tables 1 and 2.

[0142] [Table 1]

[0143]

[0144] [Table 2]

[0145]

[0146] Compared to batteries B1 to B3, batteries A1 to A3, which contain a first component and a second component in a non-aqueous electrolyte, exhibit a significantly lower rate of increase in internal resistance and a significantly lower rate of capacity reduction after storage. These effects in the embodiments are obtained when the non-aqueous electrolyte satisfies at least one of the conditions in (a) and (b) above (comparison of Examples 1 to 3, 5 to 10 with Comparative Examples 2 to 6).

[0147] Compared to battery B3, which uses a non-aqueous electrolyte and contains neither the first nor the second component, battery B2, which uses a non-aqueous electrolyte containing the first component but not the second component, exhibits a smaller, but not sufficient, rate of increase in internal resistance after storage, and a larger rate of capacity reduction after storage. Similarly, battery B1, which uses a non-aqueous electrolyte containing the second component but not the first component, shows less effective suppression of internal resistance after storage compared to batteries A1-4.

[0148] Industrial availability

[0149] The lithium primary battery of this application can significantly suppress the increase in internal resistance during high-temperature storage. Therefore, the lithium primary battery can be suitable for use as, for example, the main power supply for various instruments and the backup power supply for storage. However, the uses of the lithium primary battery are not limited to these.

[0150] Explanation of reference numerals in the attached figures

[0151] 1 Positive electrode

[0152] 1a Positive current collector

[0153] 2 negative electrodes

[0154] 3 partitions

[0155] 4 positive leads

[0156] 5 negative leads

[0157] 6. Upper Insulation Board

[0158] 7. Lower Insulation Board

[0159] 8 sealing boards

[0160] 9 Battery casings

[0161] 10-cell lithium primary battery

Claims

1. A lithium primary battery comprising a positive electrode, a negative electrode, and a nonaqueous electrolyte, The positive electrode comprises a positive electrode mixture containing LixMnO2, wherein, 0≤x≤0.05， the negative electrode comprising at least one of metallic lithium and a lithium alloy, the nonaqueous electrolyte comprising at least one of a cyclic imide component and a pyrrole component as a first component, and comprising an oxalato-phosphate complex component as a second component, the concentration of the first component in the nonaqueous electrolyte is 1 mass% or less, the concentration of the second component in the nonaqueous electrolyte is 6 mass% or less, the mass ratio of the first component to the second component contained in the nonaqueous electrolyte is 0.02 or more and 10 or less.

2. The lithium primary battery according to claim 1, wherein the oxalato-phosphate complex component comprises at least one selected from the group consisting of a tetrafluoro(oxalato)phosphate complex component, a difluoro bis(oxalato)phosphate complex component, and a tri(oxalato)phosphate complex component.

3. The lithium primary battery according to claim 1, wherein the cyclic imide component comprises at least one selected from the group consisting of phthalimide and N-substituted phthalimide.

4. The lithium primary battery according to claim 1, wherein the cyclic imide component comprises phthalimide.

5. The lithium primary battery according to claim 1, wherein the pyrrole component comprises indole.

6. The lithium primary battery according to claim 1, wherein the positive electrode mixture further comprises a sulfate, the amount of sulfur atom contained in the positive electrode mixture is 0.05 mass part or more and 3 mass part or less per 100 mass parts of manganese atom contained in the positive electrode mixture.

7. The lithium primary battery according to claim 1, wherein the central value of the particle diameter of LixMnO2 is 10 μm or more and 40 μm or less.

8. The lithium primary battery according to claim 1, wherein The BET specific surface area of LixMnO2 is 10 m 2 / g or more and 40 m 2 / g or less.

9. The lithium primary cell according to claim 1, wherein, the positive electrode comprises a current collector having a hole and the positive electrode mixture filled in the current collector, the current collector comprises at least one material selected from the group consisting of SUS444, SUS430, and SUS316, the thickness of the positive electrode is 300 μm or more and 900 μm or less.

10. The lithium primary battery according to claim 1, wherein the negative electrode comprises a foil of metallic lithium or a lithium alloy, and has a shape having a length direction and a width direction, and a long tape-shaped adhesive tape is attached to at least one main surface of the negative electrode along the length direction, the adhesive tape comprising a resin base material and an adhesive layer.

11. A lithium primary battery comprising a positive electrode, a negative electrode, and a nonaqueous electrolyte, The positive electrode comprises a positive electrode mixture containing LixMnO2, wherein, 0≤x≤0.05， the negative electrode comprising at least one of metallic lithium and a lithium alloy, the nonaqueous electrolyte comprising at least one of a cyclic imide component and a pyrrole component as a first component, and comprising an oxalato-phosphate complex component as a second component, the concentration of the first component in the nonaqueous electrolyte is 0.1 mass% or more and 1 mass% or less, the concentration of the second component in the nonaqueous electrolyte is 0.1 mass% or more and 6 mass% or less.

12. The lithium primary cell according to claim 11, wherein, the mass ratio of the first component to the second component contained in the nonaqueous electrolyte is 0.02 or more and 10 or less.

13. The lithium primary cell according to claim 11 or 12, wherein the oxalato-phosphate complex component comprises at least one selected from the group consisting of a tetrafluoro(oxalato)phosphate complex component, a difluoro bis(oxalato)phosphate complex component, and a tri(oxalato)phosphate complex component.

14. The lithium primary cell according to claim 11 or 12, wherein the cyclic imide component comprises at least one selected from the group consisting of phthalimide and N-substituted phthalimide.

15. The lithium primary cell according to claim 11 or 12, wherein the cyclic imide component comprises phthalimide.

16. The lithium primary cell according to claim 11 or 12, wherein the pyrrole component comprises indole.

17. The lithium primary cell according to claim 11 or 12, wherein the positive electrode mixture further comprises a sulfate, the amount of sulfur atom contained in the positive electrode mixture is 0.05 mass part or more and 3 mass part or less per 100 mass parts of manganese atom contained in the positive electrode mixture. The amount of sulfur atoms contained in the positive electrode mixture is 0.05 parts by mass or more and 3 parts by mass or less per 100 parts by mass of manganese atoms contained in the positive electrode mixture.

18. The lithium primary cell according to claim 11 or 12, wherein, The central value of the particle diameter of LixMnO2 is 10 μm or more and 40 μm or less.

19. The lithium primary cell according to claim 11 or 12, wherein, The BET specific surface area of LixMnO2 is 10 m 2 / g or more and 40 m 2 / g or less.

20. The lithium primary cell according to claim 11 or 12, wherein The positive electrode has a hole-containing current collector and the positive electrode mixture filled in the current collector, The current collector contains at least one material selected from the group consisting of SUS444, SUS430, and SUS316, The thickness of the positive electrode is 300 μm or more and 900 μm or less.

21. The lithium primary cell according to claim 11 or 12, wherein The negative electrode contains a foil of metal lithium or a lithium alloy, and has a shape having a length direction and a width direction, and a long tape-shaped adhesive tape is attached to at least one main surface of the negative electrode along the length direction, the adhesive tape having a resin base material and an adhesive layer.

22. A nonaqueous electrolyte for a lithium primary battery, which is used for a lithium primary battery provided with a positive electrode, a negative electrode and a nonaqueous electrolyte, the positive electrode comprising a positive electrode mixture containing LixMn02, wherein, 0 ≤ x ≤ 0.05, the negative electrode contains at least one of metal lithium and a lithium alloy, The nonaqueous electrolyte contains at least one of a cyclic imide component and a pyrrole component as a first component, and contains an oxalato-phosphate complex component as a second component, The concentration of the first component in the nonaqueous electrolyte is 0.1 mass% or more and 1 mass% or less, The concentration of the second component in the nonaqueous electrolyte is 0.1 mass% or more and 6 mass% or less.

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