Lithium primary battery and non-aqueous electrolyte for lithium primary battery

Abstract

This lithium primary battery comprises a positive electrode, a negative electrode and a non-aqueous electrolytic solution. The positive electrode includes a positive electrode mixture containing LixMnO2 (0≤x≤0.05), and the negative electrode includes metal lithium and / or a lithium alloy. The non-aqueous electrolytic solution includes a cyclic imide component and / or a pyrrole component as a first component, and an oxalate phosphate complex component as a second component. The concentration of the first component in the non-aqueous electrolytic solution is 1 mass% or less, the concentration of the second component in the non-aqueous electrolytic solution is 6 mass% or less, and the mass ratio of the first component included in the non-aqueous electrolytic solution to the second component is from 0.02 to 10.

Description

[Technical Field]

[0001] The present disclosure relates to a non-aqueous electrolyte solution used in a lithium primary battery, and a lithium primary battery using the same. [Background technology]

[0002] Lithium primary batteries are used as power sources for many electronic devices due to their high energy density and low self-discharge. A lithium primary battery includes a negative electrode containing metallic lithium, a positive electrode, and a nonaqueous electrolyte. The positive electrode contains an active material such as graphite fluoride, manganese dioxide, or thionyl chloride.

[0003] Patent Document 1 proposes the use of a non-aqueous electrolyte containing an additive such as phthalimide, from the viewpoint of suppressing an increase in internal resistance during high-temperature storage of a primary battery or secondary battery.

[0004] Patent Document 2 proposes an additive composition for an electrolyte solution for a non-aqueous electricity storage device, which contains as an additive a compound in which at least one acidic proton of a specific acid is substituted with a silyl group having three hydrocarbon groups. Patent Document 2 teaches that the additive suppresses gas generation during use of a lithium ion secondary battery, preventing swelling of the battery.

[0005] Patent Document 3 proposes an electrolyte containing LiB(C2O4)F2 or the like as an electrolyte for electrochemical devices that has high heat resistance and hydrolysis resistance.

[0006] Patent Document 4 proposes using Li[P(C2O4)3], which is more stable than LiPF6, as a conductive salt in a lithium ion battery. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 01 / 41247 Brochure [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-189327 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-110235 [Patent Document 4] Patent No. 4695802 specification Summary of the Invention

[0008] As electronic devices become more powerful, lithium primary batteries used as their power sources are required to have high discharge performance even after high-temperature storage. Even when a nonaqueous electrolyte containing phthalimide is used in a lithium primary battery, the suppression of an increase in internal resistance during high-temperature storage is still insufficient, and discharge performance may decrease after high-temperature storage.

[0009] A first aspect of the present disclosure relates to a lithium primary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte solution, wherein the positive electrode includes a positive electrode mixture containing LixMnO2 (0≦x≦0.05), the negative electrode includes at least one of metallic lithium and a lithium alloy, and the non-aqueous electrolyte solution includes at least one of a cyclic imide component and a pyrrole component as a first component, and an oxalate phosphate complex component as a second component, wherein the concentration of the first component in the non-aqueous electrolyte solution is 1% by mass or less, the concentration of the second component in the non-aqueous electrolyte solution is 6% by mass or less, and the mass ratio of the first component to the second component contained in the non-aqueous electrolyte solution is 0.02 or more and 10 or less.

[0010] A second aspect of the present disclosure relates to a lithium primary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte solution, wherein the positive electrode includes a positive electrode mixture containing LixMnO2 (0≦x≦0.05), the negative electrode includes at least one of metallic lithium and a lithium alloy, and the non-aqueous electrolyte solution includes at least one of a cyclic imide component and a pyrrole component as a first component, and an oxalate phosphate complex component as a second component, wherein the concentration of the first component in the non-aqueous electrolyte solution 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 solution is 0.1% by mass or more and 6% by mass or less.

[0011] A third aspect of the present disclosure relates to a non-aqueous electrolyte solution for use in a lithium primary battery including a positive electrode containing a positive electrode mixture including LixMnO2 (0≦x≦0.05), a negative electrode containing at least one of metallic lithium and a lithium alloy, and a non-aqueous electrolyte solution, wherein the non-aqueous electrolyte solution contains at least one of a cyclic imide component and a pyrrole component as a first component, and an oxalate phosphate complex component as a second component, the concentration of the first component in the non-aqueous electrolyte solution being 0.1% by mass or more and 1% by mass or less, and the concentration of the second component in the non-aqueous electrolyte solution being 0.1% by mass or more and 6% by mass or less.

[0012] According to the present disclosure, it is possible to suppress an increase in internal resistance of a lithium primary battery when stored at high temperatures. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a partially cross-sectional front view of a lithium primary battery according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] The lithium primary battery includes a positive electrode containing LixMnO2 (0≦x≦0.05), a negative electrode containing at least one of metallic lithium and a lithium alloy, and a non-aqueous electrolyte. In this battery, when the non-aqueous electrolyte contains a cyclic imide component, the increase in internal resistance during high-temperature storage is suppressed to some extent compared to when the non-aqueous electrolyte does not contain a cyclic imide component, but this is still insufficient, and the discharge capacity may decrease after high-temperature storage.

[0015] The lithium primary battery of the present disclosure includes a positive electrode containing a positive electrode mixture including LixMnO2 (0≦x≦0.05), a negative electrode containing at least one of metallic lithium and a lithium alloy, and a nonaqueous electrolyte. The nonaqueous electrolyte contains at least one of a cyclic imide component and a pyrrole component as a first component, and an oxalate phosphate complex component as a second component. In such a lithium primary battery, the nonaqueous electrolyte satisfies at least one of the following conditions (a) and (b):

[0016] (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 contained in the non-aqueous electrolyte (first component / second component) is 0.02 or more and 10 or less.

[0017] (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.

[0018] According to the present disclosure, by providing a lithium primary battery with the above-described nonaqueous electrolyte solution, an increase in internal resistance when the lithium primary battery is stored at high temperatures is significantly suppressed, and a decrease in discharge capacity after high-temperature storage is suppressed, even though the nonaqueous electrolyte solution contains a cyclic imide component. The reasons for achieving such effects in the present disclosure are believed to be as follows.

[0019] When a nonaqueous electrolyte solution contains a cyclic imide component but not an oxalate phosphate complex component, the increase in internal resistance during storage is somewhat suppressed compared to when the electrolyte solution does not contain both the cyclic imide component and the oxalate phosphate complex component. However, the discharge capacity after high-temperature storage is significantly reduced. This is thought to be due to the oxidation of the cyclic imide component on the surface of the positive electrode, forming a coating with low lithium ion conductivity derived from the cyclic imide component on the surface of the positive electrode, which inhibits the movement of lithium ions at the interface between the positive electrode and the electrolyte. Furthermore, the oxidation of the cyclic imide component promotes self-discharge of the positive electrode, resulting in a decrease in discharge capacity after storage. In particular, when a lithium primary battery is stored at high temperatures for a long period of time, the growth of the coating on the positive electrode and the self-discharge of the positive electrode are accelerated, resulting in a significant decrease in discharge capacity after storage.

[0020] When the non-aqueous electrolyte solution contains an oxalate phosphate complex component but not a cyclic imide component, the increase in internal resistance during storage is suppressed to some extent, but not sufficiently, compared to when the non-aqueous electrolyte solution does not contain both the oxalate phosphate complex component and the cyclic imide component. Furthermore, the coating containing a component derived from the oxalate phosphate complex component has low thermal stability, and side reactions occur during high-temperature storage. Therefore, the discharge capacity may decrease after high-temperature storage. Furthermore, a large amount of gas may be generated during storage.

[0021] In contrast, in the lithium primary battery of the present disclosure, the increase in internal resistance during high-temperature storage is significantly suppressed compared to when the non-aqueous electrolyte does not contain both the cyclic imide component and the oxalate phosphate complex component. In the lithium primary battery of the present disclosure, the increase in internal resistance during high-temperature storage is significantly suppressed compared to when the non-aqueous electrolyte contains either the cyclic imide component or the oxalate phosphate complex component. Therefore, when the non-aqueous electrolyte satisfies at least one of the above conditions (a) and (b), it can be said that the cyclic imide component and the oxalate phosphate complex component exert a synergistic effect in suppressing the increase in internal resistance during high-temperature storage. The reason why the increase in internal resistance during high-temperature storage in the lithium primary battery of the present disclosure is significantly suppressed is not entirely clear, but it can be considered as follows. It is believed that when the cyclic imide component decomposes on the positive electrode surface to form a coating, the oxalate phosphate complex component is also involved in the decomposition reaction, resulting in the formation of a coating containing components derived from both the cyclic imide component and the oxalate phosphate complex component. When such a coating is formed, a chemically and thermally stable coating is formed, unlike a coating formed from components derived solely from the cyclic imide component. The formation of this coating reduces side reactions due to contact between the positive electrode and the nonaqueous electrolyte during high-temperature storage, significantly suppressing increases in internal resistance caused by side reactions and reducing the decrease in discharge capacity due to increased internal resistance. Gas generation during storage is also suppressed. Furthermore, a coating containing components derived from both the cyclic imide component and the oxalate phosphate complex component has excellent lithium ion conductivity, which is advantageous for reducing internal resistance. Because this coating is dense and has low electronic conductivity, oxidation of the cyclic imide component is less likely to progress after the coating is formed on the positive electrode surface during the initial battery assembly, and the reduction of the positive electrode is slowed. This reduces self-discharge during storage of the lithium primary battery. Therefore, it is believed that using an electrolyte containing both the cyclic imide component and the oxalate phosphate complex component significantly suppresses increases in internal resistance during high-temperature storage and reduces the decrease in discharge capacity after storage.

[0022] When the first component is a pyrrole component, the same effect as when the first component is a cyclic imide component can be obtained. When the first component is a pyrrole component, a coating film containing components derived from both the pyrrole component and the oxalate phosphate complex component is formed, and the coating film is chemically and thermally stable and has excellent lithium ion conductivity, and it is thought that an increase in internal resistance during high-temperature storage is significantly suppressed.

[0023] The present disclosure also includes a nonaqueous electrolyte solution for use in a lithium primary battery comprising a positive electrode containing a positive electrode mixture including LixMnO2 (0≦x≦0.05), a negative electrode containing at least one of metallic lithium and a lithium alloy, and a nonaqueous electrolyte solution. Here, the nonaqueous electrolyte solution contains a first component and a second component. The nonaqueous electrolyte solution satisfies the above condition (b). The present disclosure also includes the use of such a nonaqueous electrolyte solution in a lithium primary battery comprising a positive electrode containing a positive electrode mixture including LixMnO2 (0≦x≦0.05), a negative electrode containing at least one of metallic lithium and a lithium alloy, and a nonaqueous electrolyte solution.

[0024] The lithium primary battery of the present disclosure will be described in more detail below.

[0025] [Lithium primary battery] (positive electrode) The positive electrode includes a positive electrode mixture. The positive electrode mixture includes a positive electrode active material. Examples of the positive electrode active material included in the positive electrode include manganese dioxide. A positive electrode including manganese dioxide exhibits a relatively high voltage and has excellent pulse discharge characteristics. The manganese dioxide may be in a mixed crystal state including a plurality of crystalline states. The positive electrode may include a manganese oxide other than manganese dioxide. Examples of manganese oxide other than manganese dioxide include MnO, Mn3O4, Mn2O3, and Mn2O7. It is preferable that the main component of the manganese oxide included in the positive electrode is manganese dioxide.

[0026] A portion of the manganese dioxide in the positive electrode may be doped with lithium. A small amount of lithium doping can ensure high capacity. Manganese dioxide and manganese dioxide doped with a small amount of lithium can be expressed as LixMnO2 (0≦x≦0.05). The average composition of the manganese oxide in the positive electrode must be LixMnO2 (0≦x≦0.05). The Li ratio x must be 0.05 or less at the initial stage of discharge of the lithium primary battery. The Li ratio x generally increases as the discharge of the lithium primary battery progresses. Theoretically, the oxidation state of manganese in manganese dioxide is tetravalent. However, the presence of other manganese oxides in the positive electrode or the doping of manganese dioxide with lithium can cause the oxidation state of manganese to fluctuate slightly from tetravalent. Therefore, in LixMnO2, the average oxidation state of manganese can vary slightly from tetravalent.

[0027] The positive electrode may contain, in addition to LixMnO2, other positive electrode active materials used in lithium primary batteries. Examples of such positive electrode active materials include graphite fluoride. From the viewpoint of easily achieving the effects of using a nonaqueous electrolyte that satisfies the above conditions (a) or (b), the proportion of LixMnO2 in the overall positive electrode active material is preferably 90 mass% or more.

[0028] As the manganese dioxide, electrolytic manganese dioxide is preferably used. If necessary, electrolytic manganese dioxide may be used that has been subjected to at least one of neutralization treatment, washing treatment, and calcination treatment.

[0029] Electrolytic manganese dioxide is generally obtained by electrolysis of an aqueous manganese sulfate solution. Therefore, sulfate ions are inevitably contained in electrolytic manganese dioxide. A positive electrode mixture prepared using such electrolytic manganese dioxide inevitably contains sulfur atoms. The amount of sulfur atoms contained in the positive electrode mixture may be 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. When the amount of sulfur atoms is within this range, in a lithium primary battery, sulfate ions and Li xUnstable MnO2 formed during lithium insertion 3+ and interact to form Mn 3+ Mn by disproportionation 2+ This is thought to suppress the generation of Mn 2+ It is believed that this suppresses the dissolution of Mn into the non-aqueous electrolyte and the precipitation of Mn at the negative electrode. As a result, high capacity and high reliability of lithium primary batteries can be ensured. On the other hand, in lithium secondary batteries, some sulfate ions are decomposed during the charging process, so even if the positive electrode mixture contains sulfate in an amount that satisfies the above-mentioned range, it is difficult to fully ensure the above-mentioned effects. The proportion of sulfur atoms contained in the positive electrode mixture can be adjusted by adjusting the conditions of the washing treatment and neutralization treatment. Examples of the washing treatment include at least one of a water washing treatment and an acid washing treatment. Examples of the neutralizing agent used in the neutralization treatment include inorganic bases such as ammonia and hydroxides.

[0030] By adjusting the conditions during electrolytic synthesis, the crystallinity of manganese dioxide can be increased and the specific surface area of ​​electrolytic manganese dioxide can be reduced. The BET specific surface area of ​​LixMnO2 is 10m 2 / g or more, 40m 2 / g or less. When the BET specific surface area of ​​LixMnO2 is in this range, a higher effect of suppressing self-discharge in a lithium primary battery can be obtained. In addition, a positive electrode mixture layer can be easily formed.

[0031] The BET specific surface area of ​​LixMnO2 may be measured by a known method, for example, by the BET method using a specific surface area measuring device (for example, manufactured by Mountec Co., Ltd.) For example, LixMnO2 separated from the positive electrode removed from a battery may be used as a measurement sample.

[0032] The median particle size of LixMnO2 may be 10 μm or more and 40 μm or less. When the median particle size is in this range, the effect of suppressing self-discharge in a lithium primary battery is further enhanced, and high current collection properties in the positive electrode are easily ensured.

[0033] The median particle size of LixMnO2 is the median of the particle size distribution determined by, for example, quantitative laser diffraction / scattering (qLD) method. For example, LixMnO2 separated from the positive electrode removed from a battery can be used as a measurement sample. For example, an SALD-7500 nano manufactured by Shimadzu Corporation is used for the measurement.

[0034] The positive electrode mixture may contain a binder in addition to the positive electrode active material. The positive electrode mixture may also contain a conductive agent.

[0035] Examples of the binder include fluororesin, rubber particles, and acrylic resin.

[0036] Examples of the conductive agent include conductive carbon materials, such as natural graphite, artificial graphite, carbon black, and carbon fiber.

[0037] The positive electrode may further include a positive electrode current collector that holds the positive electrode mixture. Examples of materials for the positive electrode current collector include stainless steel, aluminum, and titanium.

[0038] In the case of a coin-type battery, the positive electrode may be constructed by attaching a ring-shaped positive electrode current collector with an L-shaped cross section to a positive electrode mixture pellet, or by using only the positive electrode mixture pellet. The positive electrode mixture pellet can be obtained, for example, by compression-molding a wet positive electrode mixture prepared by adding an appropriate amount of water to a positive electrode active material and an additive, and then drying the resulting mixture.

[0039] In the case of a cylindrical battery, a positive electrode including a sheet-shaped positive electrode current collector and a positive electrode mixture layer supported on the positive electrode current collector can be used. The sheet-shaped positive electrode current collector is preferably a perforated current collector. Examples of perforated current collectors include expanded metal, netting, and punched metal. The positive electrode mixture layer can be obtained, for example, by applying the above-mentioned wet positive electrode mixture to the surface of the sheet-shaped positive electrode current collector or by filling the positive electrode current collector with the wet positive electrode mixture, pressing it in the thickness direction, and drying it.

[0040] The positive electrode preferably comprises a porous current collector as described above and a positive electrode mixture filled into the current collector. It is particularly preferable to use a current collector containing at least one material selected from the group consisting of SUS444, SUS430, and SUS316. The use of such a current collector can suppress side reactions with the nonaqueous electrolyte and corrosion of the current collector in a lithium primary battery, thereby suppressing increases in internal resistance and gas generation. In particular, when such a current collector is combined with a nonaqueous electrolyte containing at least one of LiCF3SO3 and LiClO4, which are typically used as lithium salts in lithium primary batteries, side reactions between the current collector and the nonaqueous electrolyte can be more effectively suppressed. The thickness of the positive electrode is, for example, 300 μm or more and 900 μm or less. Using a positive electrode with such a thickness tends to reduce the diffusibility of the nonaqueous electrolyte in the positive electrode mixture, suppressing reduction of the positive electrode due to oxidation of the solvent or cyclic imide component (first component), thereby suppressing self-discharge. In addition, in a lithium primary battery, discharge is usually carried out at a low rate over a long period of time, so an increase in resistance when the thickness of the positive electrode is within this range is acceptable.

[0041] (Negative electrode) The negative electrode may contain metallic lithium or a lithium alloy, or may contain both metallic lithium and lithium metal. For example, a composite containing metallic lithium and a lithium alloy may be used for the negative electrode.

[0042] Examples of lithium alloys include Li-Al alloys, Li-Sn alloys, Li-Ni-Si alloys, Li-Pb alloys, etc. The content of metal elements other than lithium contained in the lithium alloy is preferably 0.05 to 15 mass % from the viewpoints of ensuring discharge capacity and stabilizing internal resistance.

[0043] The metallic lithium, lithium alloy, or composite thereof is formed into any shape and thickness depending on the shape, dimensions, performance specifications, etc. of the lithium primary battery.

[0044] In the case of coin-type batteries, a hoop-shaped metallic lithium, lithium alloy, or composite thereof may be punched into a disk shape and used as the negative electrode. In the case of cylindrical batteries, a sheet of metallic lithium, lithium alloy, or composite thereof may be used as the negative electrode. The sheet may be obtained, for example, by extrusion molding. More specifically, cylindrical batteries use a foil of metallic lithium or a lithium alloy having a shape with a longitudinal direction and a transverse direction.

[0045] In the case of a cylindrical battery, a long tape comprising a resin substrate and an adhesive layer may be attached along the longitudinal direction to at least one main surface of the negative electrode. The main surface refers to the surface facing the positive electrode. The width of this tape may be, for example, 0.5 mm or more and 3 mm or less. This tape serves to prevent the negative electrode from tearing and causing current collection problems when the lithium component of the negative electrode is consumed by a reaction at the end of discharge. Poor current collection results in a decrease in battery capacity. However, the adhesive strength of the tape decreases due to the electrolyte during long-term storage. Using an electrolyte containing the first and second components can suppress this decrease in adhesive strength, more effectively preventing the negative electrode from tearing and causing current collection problems.

[0046] Examples of materials that can be used for the resin substrate include fluororesin, polyimide, polyphenylene sulfide, polyethersulfone, polyolefins such as polyethylene and polypropylene, polyethylene terephthalate, etc. Among these, polyolefins are preferred, and polypropylene is more preferred.

[0047] The adhesive layer contains, for example, at least one component selected from the group consisting of a rubber component, a silicone component, and an acrylic resin component. Specifically, the rubber component may be synthetic rubber or natural rubber. Examples of synthetic rubber include butyl rubber, butadiene rubber, styrene-butadiene rubber, isoprene rubber, neoprene, polyisobutylene, acrylonitrile-butadiene rubber, styrene-isoprene block copolymer, styrene-butadiene block copolymer, and styrene-ethylene-butadiene block copolymer. Examples of silicone components include organic compounds having a polysiloxane structure and silicone-based polymers. Examples of silicone-based polymers include peroxide-curable silicones and addition reaction silicones. The acrylic resin component can be a polymer containing an acrylic monomer such as acrylic acid, methacrylic acid, an acrylic acid ester, or a methacrylic acid ester, and examples thereof 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. The adhesive layer may contain a crosslinker, a plasticizer, and a tackifier.

[0048] (Non-aqueous electrolyte) The non-aqueous electrolyte solution contains, for example, a first component (at least one of a cyclic imide component and a pyrrole component), a second component (an oxalate phosphate complex component), and a non-aqueous solvent that dissolves them. The non-aqueous electrolyte solution contains a lithium salt or lithium ions. At least one of the first component and the second component may be a lithium salt or may be capable of generating lithium ions. The non-aqueous electrolyte solution may also contain a lithium salt other than the first component and the second component.

[0049] (Oxalate phosphate complex component) The oxalate phosphate complex component may have a structure capable of generating at least an anion represented by the following formula (1): In formula (1), * represents a bond. The non-aqueous electrolyte may contain one or more oxalate phosphate complex components.

[0050] [ka]

[0051] The oxalate phosphate complex component may be contained in the non-aqueous electrolyte in either the form of an acid (or anion) or a salt. The oxalate phosphate complex component may be any component capable of generating at least an oxalate phosphate complex anion in the non-aqueous electrolyte. The oxalate phosphate complex component may be a salt of the oxalate phosphate complex anion and a cation contained in the non-aqueous electrolyte.

[0052] In the oxalate phosphate complex component, at least one oxalate ligand may be coordinated to one phosphorus atom, but two oxalate ligands or three oxalate ligands may also be coordinated to one phosphorus atom.

[0053] The oxalate phosphate complex component may have a structure in which one phosphorus atom is coordinated with one oxalate ligand and four halogen atoms. The oxalate phosphate complex component having such a structure can generate an anion represented by the following formula (2):

[0054] [ka]

[0055] In formula (2), X 1 ~X 4 are each a halogen atom. Examples of the halogen atom coordinated to the phosphorus atom include a fluorine atom and a chlorine atom.

[0056] The oxalate phosphate complex component may have a structure in which two oxalate ligands and two halogen atoms are coordinated to one phosphorus atom. The oxalate phosphate complex component having such a structure can generate an anion represented by the following formula (3):

[0057] [ka]

[0058] In formula (3), X 5 and X 6 are each a halogen atom. Examples of the halogen atom coordinated to the phosphorus atom include a fluorine atom and a chlorine atom.

[0059] As the oxalate phosphate complex component, a tetrafluoro(oxalate) phosphate complex component, a difluorobis(oxalate) phosphate complex component, and a tris(oxalate) phosphate complex component are preferably used. Among them, as the oxalate phosphate complex component, lithium tetrafluoro(oxalate) phosphate, lithium difluorobis(oxalate) phosphate, and lithium tris(oxalate) phosphate are preferred.

[0060] The tetrafluoro(oxalate)phosphate complex component has a structure in which one oxalate ligand and four fluorine atoms are coordinated to one phosphorus atom. The difluorobis(oxalate)borate complex component has a structure in which two oxalate ligands and two fluorine atoms are coordinated to one phosphorus atom. The tris(oxalate)phosphate complex component has a structure in which three oxalate ligands are coordinated to one phosphorus atom, and can generate an anion represented by the following formula (4).

[0061] [ka]

[0062] When the non-aqueous electrolyte satisfies the above condition (a), the concentration of the oxalate phosphate complex component in the non-aqueous electrolyte is 6% by mass or less, and may be 5.5% by mass or less, or even 5% by mass or less. If the concentration of the oxalate phosphate complex component exceeds 6% by mass, side reactions will proceed during high-temperature storage, resulting in a decrease in discharge capacity after storage. The concentration of the oxalate phosphate complex component in the non-aqueous electrolyte may be at least the detection limit, and may be 0.1% by mass or more, or 0.5% by mass or more. These upper and lower limits can be combined arbitrarily.

[0063] During storage or discharge of a lithium primary battery, the oxalate phosphate complex component is consumed in the lithium primary battery for film formation and other purposes, causing the concentration of the oxalate phosphate complex component in the non-aqueous electrolyte to change. The concentration of the oxalate phosphate complex component in the non-aqueous electrolyte used in assembling or manufacturing the battery is preferably 0.1% by mass or more, and more preferably 0.5% by mass or more. In this case, an increase in internal resistance during high-temperature storage is significantly suppressed. The concentration of the oxalate phosphate complex component in the non-aqueous electrolyte used in assembling or manufacturing the battery is preferably 5.5% by mass or less or 5% by mass or less. In this case, capacity loss after high-temperature storage is likely to be suppressed. These lower and upper limits can be combined in any desired manner.

[0064] When the non-aqueous electrolyte satisfies the above condition (b), the concentration of the oxalate phosphate complex component in the non-aqueous electrolyte may be 0.1% by mass or more and 6% by mass or less, or may 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 may be 1% by mass or more and 5% by mass or less. When the concentration of the oxalate phosphate complex component is within this range, an increase in internal resistance during high-temperature storage is easily suppressed, and a decrease in capacity after high-temperature storage is significantly suppressed.

[0065] As described above, the oxalate phosphate complex component may be contained in the non-aqueous electrolyte in the form of an acid (or anion). However, in this specification, the concentration or mass amount of the oxalate phosphate complex component in the non-aqueous electrolyte is a value converted into the concentration or mass amount of the lithium salt of the oxalate phosphate complex.

[0066] (cyclic imide component) Examples of cyclic imide components include cyclic diacylamines. The cyclic imide component may have a diacylamine ring (also referred to as an imide ring). The imide ring may be condensed with another ring (also referred to as a second ring). The non-aqueous electrolyte may contain one type of cyclic imide component, or two or more types. The cyclic imide component may be contained in the non-aqueous electrolyte in the form of an imide, or in the form of an anion or a salt. When the cyclic imide component is contained in the non-aqueous electrolyte in the form of an imide, it may be contained in the form having a free NH group, or in the form of a tertiary amine.

[0067] The second ring may be an aromatic ring, a saturated or unsaturated aliphatic ring, or the like. The second ring may contain at least one heteroatom. Examples of the heteroatom include an oxygen atom, a sulfur atom, and a nitrogen atom.

[0068] Examples of cyclic imides constituting the cyclic imide component include aliphatic dicarboxylic acid imides and cyclic imides having a second ring. Examples of aliphatic dicarboxylic acid imides include succinimide. Examples of cyclic imides having a second ring include imides of aromatic or alicyclic dicarboxylic acids. Examples of aromatic dicarboxylic acids or alicyclic dicarboxylic acids include those having a carboxy group on each of two adjacent atoms constituting the ring. Examples of cyclic imides having a second ring include phthalimide and hydrogenated phthalimide. Examples of hydrogenated phthalimides include cyclohex-3-ene-1,2-dicarboximide and cyclohexane-1,2-dicarboximide.

[0069] The imide ring may be an N-substituted imide ring having a substituent on the nitrogen atom of the imide. Such a substituent may include a hydroxy group, an alkyl group, an alkoxy group, a halogen atom, etc. Examples of the alkyl group include C 1-4 Examples of the alkoxy group include alkyl groups, such as methyl groups and ethyl groups. 1-4 Examples of the halogen atom include chlorine atoms, fluorine atoms, and the like.

[0070] 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 the substituents exemplified for the N-substituted imide ring. It is more preferred to use a cyclic imide component containing at least phthalimide.

[0071] (pyrrole component) The pyrrole component includes pyrrole and its derivatives, and may have a pyrrole ring. The non-aqueous electrolyte may contain one type of pyrrole component, or two or more types. The pyrrole component may be contained in the non-aqueous electrolyte in the form of a pyrrole, or in the form of an anion or a salt. When the pyrrole component is contained in the non-aqueous electrolyte in the form of a pyrrole, it may be contained in the form of a pyrrole having a free NH group, or in the form of a tertiary amine.

[0072] The pyrrole ring may be an N-substituted pyrrole ring having a substituent on the nitrogen atom of the pyrrole, which can be selected from the substituents exemplified above for the N-substituted imido ring.

[0073] The pyrrole ring may be fused with another ring (also referred to as a second ring). Examples of the second ring include an aromatic ring, a saturated or unsaturated aliphatic ring, and the like. The second ring may contain at least one heteroatom. Examples of heteroatoms include an oxygen atom, a sulfur atom, and a nitrogen atom. Examples of pyrrole components having a second ring include indole, N-substituted indole, isoindole, N-substituted isoindole, porphyrin, and N-substituted porphyrin. The substituent on the nitrogen atom of N-substituted indole, etc., can be selected from the substituents exemplified for the N-substituted imide ring above.

[0074] When the nonaqueous electrolyte satisfies the above condition (a), the mass ratio of the first component to the second component contained in the nonaqueous electrolyte is 0.02 to 10, or alternatively, 0.02 to 7, 0.02 to 5, or 0.1 to 5. When the mass ratio is within this range, a high-quality coating having excellent lithium ion conductivity, chemical stability, and thermal stability is more easily formed on the surface of the positive electrode. Therefore, an increase in internal resistance during high-temperature storage is significantly suppressed.

[0075] The concentration of the first component in the non-aqueous electrolyte is 1% by mass or less, and may be 0.7% by mass or less, or 0.5% by mass or less. When the concentration of the first component is within this range, the increase in internal resistance during high-temperature storage and the decrease in capacity after storage are further suppressed. The concentration of the first component in the non-aqueous electrolyte may be equal to or greater than the detection limit, and may be 0.1% by mass or more, or 0.3% by mass or more. These upper and lower limits can be combined arbitrarily.

[0076] If the concentration of the first component in the non-aqueous electrolyte exceeds 1 mass %, a coating with low lithium ion conductivity is formed on the surface of the positive electrode during high-temperature storage, resulting in a decrease in discharge capacity after high-temperature storage.

[0077] During battery storage or discharge, the first component is consumed in the battery for film formation and the like, causing the concentration of the first component in the nonaqueous electrolyte to change. The concentration of the first component in the nonaqueous electrolyte used in battery assembly or manufacture is preferably 0.1% by mass or more, or 0.3% by mass or more. In this case, an increase in internal resistance during high-temperature storage is likely to be effectively suppressed. Furthermore, the concentration of the first component in the nonaqueous electrolyte used in battery assembly or manufacture is preferably 1% by mass or less, or 0.7% by mass or less. In this case, capacity loss after high-temperature storage is significantly suppressed.

[0078] When the non-aqueous electrolyte satisfies the above condition (b), the concentration of the first component in the non-aqueous electrolyte may be 0.1% by mass or more and 1% by mass or less, or may be 0.3% by mass or more and 1% by mass or less, or may be 0.3% by mass or more and 0.7% by mass or less. When the concentration of the first component is in this range, an increase in internal resistance during high-temperature storage is likely to be significantly suppressed, and a decrease in capacity after storage is significantly suppressed.

[0079] The mass ratio of the first component to the second component contained in the nonaqueous electrolyte may 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. When the mass ratio is within this range, an increase in internal resistance during high-temperature storage is likely to be effectively suppressed, and a decrease in capacity after storage is further suppressed.

[0080] The first component may be contained in the non-aqueous electrolyte in the form of a salt, provided that in this specification, the concentration or mass amount of the first component in the non-aqueous electrolyte is a value converted into the concentration or mass amount of the first component having free NH groups.

[0081] The non-aqueous electrolyte (first component and second component) can be analyzed by, for example, liquid chromatography mass spectrometry (LC / MS), and ultraviolet spectroscopy (UV) may be performed together with mass spectrometry (MS).

[0082] (non-aqueous solvent) Examples of non-aqueous solvents include organic solvents that are commonly used in non-aqueous electrolytes for lithium primary batteries. Examples of non-aqueous solvents include ethers, esters, and carbonate esters. Examples of non-aqueous solvents that can be used include dimethyl ether, γ-butyl lactone, propylene carbonate, ethylene carbonate, and 1,2-dimethoxyethane. The non-aqueous electrolyte may contain one non-aqueous solvent or two or more non-aqueous solvents.

[0083] From the viewpoint of improving the discharge characteristics of lithium primary batteries, the nonaqueous solvent preferably contains a cyclic carbonate with a high boiling point and a chain ether that has low viscosity even at low temperatures. The cyclic carbonate preferably contains 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 1 mPa·s or less at 25°C, and particularly preferably contains dimethoxyethane (DME). The viscosity of the nonaqueous solvent is measured using a Rheosens m-VROC microsample viscometer at 25°C and a shear rate of 10,000 (1 / s).

[0084] (lithium salts) The non-aqueous electrolyte may contain a lithium salt other than the oxalate phosphate complex component and the cyclic imide component. Examples of the lithium salt include lithium salts used as solutes in lithium primary batteries. Examples of such lithium salts include LiCF3SO3, LiClO4, LiBF4, LiPF6, LiRaSO3 (where Ra is a fluoroalkyl group having 1 to 4 carbon atoms), LiFSO3, LiN(SO2Rb)(SO2Rc) (where Rb and Rc are each independently a fluoroalkyl group having 1 to 4 carbon atoms), LiN(FSO2)2, LiPO2F2, LiB(C2O4)2, and LiBF2(C2O4). The non-aqueous electrolyte may contain one or more of these lithium salts.

[0085] (others) The concentration of lithium ions contained in the non-aqueous electrolyte (total concentration of lithium salts) is, for example, 0.2 to 2.0 mol / L, and may be 0.3 to 1.5 mol / L.

[0086] The non-aqueous electrolyte may contain additives as needed. Examples of such additives include propane sultone and vinylene carbonate. The total concentration of such additives contained in the non-aqueous electrolyte is, for example, 0.003 to 5 mol / L.

[0087] (separator) Lithium primary batteries typically include a separator interposed between a positive electrode and a negative electrode. The separator may be a porous sheet made of an insulating material that is resistant to the internal environment of a lithium primary battery. Specific examples of the separator include a synthetic resin nonwoven fabric, a synthetic resin microporous membrane, and a laminate thereof.

[0088] Examples of synthetic resins used for nonwoven fabrics include polypropylene, polyphenylene sulfide, and polybutylene terephthalate. Examples of synthetic resins used for microporous membranes include polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers. The microporous membrane may contain inorganic particles as needed.

[0089] The thickness of the separator is, for example, 5 μm or more and 100 μm or less.

[0090] The structure of the lithium primary battery is not particularly limited. The lithium primary battery may be a coin battery having a stacked electrode group formed by stacking a disc-shaped positive electrode and a disc-shaped negative electrode with a separator interposed therebetween. Alternatively, the lithium primary battery may be a cylindrical battery having a wound electrode group formed by spirally winding a strip-shaped positive electrode and a strip-shaped negative electrode with a separator interposed therebetween.

[0091] FIG. 1 shows a partially cross-sectional front view of a cylindrical lithium primary battery according to one embodiment of the present disclosure. In the lithium primary battery 10, an electrode group, in which a positive electrode 1 and a negative electrode 2 are wound with a separator 3 interposed therebetween, is housed in a battery case 9 together with a nonaqueous electrolyte. A sealing plate 8 is attached to the opening of the battery case 9. A positive electrode lead 4 connected to a 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 case 9. In addition, an upper insulating plate 6 and a lower insulating plate 7 are arranged at the top and bottom of the electrode group, respectively, to prevent internal short circuits.

[0092] [Example] Hereinafter, the present disclosure will be specifically described based on examples and comparative examples, but the present disclosure is not limited to the following examples.

[0093] Examples 1 to 10 and Comparative Examples 4 to 6 (Preparation of positive electrode) For the positive electrode, 100 parts by mass of electrolytic manganese dioxide was mixed with 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 to prepare a wet positive electrode mixture.

[0094] Next, the positive electrode mixture was filled into a 0.1 mm thick positive electrode current collector made of stainless steel (SUS444) expanded metal to prepare a positive electrode precursor. The positive electrode precursor was then dried, rolled to a thickness of 0.4 mm using a roll press, and cut into a sheet measuring 2.2 cm long and 1.5 cm wide to obtain a positive electrode. Next, a portion of the filled positive electrode mixture was peeled off, and a SUS444 tab lead was resistance welded to the exposed portion of the positive electrode current collector.

[0095] (Preparation of negative electrode) A negative electrode was obtained by cutting a 300 μm thick lithium foil into a size of 4 cm in length and 2.5 cm in width. A nickel tab lead was connected to a predetermined position of the negative electrode by pressure welding.

[0096] (Preparation of electrode groups) The electrode assembly was fabricated by wrapping a separator around the positive electrode and stacking it opposite the negative electrode. The separator was a 25 μm thick microporous polypropylene membrane.

[0097] (Preparation of non-aqueous electrolyte) 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, and the first and second components shown in Tables 1 and 2 were also dissolved therein to the concentrations shown in Tables 1 and 2. In this manner, a nonaqueous electrolyte was prepared. Regarding the second component in Tables 1 and 2, LiDFOP is lithium difluorobis(oxalate)phosphate, LiTFOP is lithium tetrafluoro(oxalate)phosphate, and LiTOP is lithium tris(oxalate)phosphate.

[0098] (Lithium primary battery assembly) The electrode group was placed in a cylindrical aluminum laminate bag measuring 9 cm in length and 6 cm in width so that the tab leads connected to the positive and negative electrodes were partially exposed from the bag, and the opening on the tab lead side was sealed. 0.5 mL of electrolyte was poured into the opening on the side opposite the tab lead, and the opening was sealed by vacuum heat sealing. In this way, a test lithium primary battery was produced. The design capacity of the lithium primary battery was 308 mAh / g (capacity per unit mass of positive electrode active material). In Tables 1 and 2, A1 to A10 are batteries of Examples 1 to 10, and B1 to B6 are batteries of Comparative Examples 1 to 6.

[0099] In the lithium primary batteries of the examples, the amount of sulfur atoms derived from sulfate contained in the positive electrode mixture was 0.05 parts by mass or more and 1.25 parts by mass or less per 100 parts by mass of manganese atoms contained in the positive electrode mixture. In the lithium primary batteries of the examples, the median particle diameter of LixMnO2 contained in the positive electrode was 25 μm to 27 μm, and the BET specific surface area was 15 to 20 m 2 / g.

[0100] Comparative Example 1 Battery B1 of Comparative Example 1 was fabricated in the same manner as Battery A1 of Example 1, except that the first component was not added to the non-aqueous electrolyte solution.

[0101] Comparative Example 2 Battery B2 of Comparative Example 2 was fabricated in the same manner as Battery A1 of Example 1, except that the second component was not added to the non-aqueous electrolyte solution.

[0102] Comparative Example 3 Battery B3 of Comparative Example 3 was fabricated in the same manner as Battery A1 of Example 1, except that the non-aqueous electrolyte did not contain the first component and the second component.

[0103] The rate of increase in internal resistance after high-temperature storage was measured for the batteries A1 to A4 and B1 to B3 as follows.

[0104] [Evaluation 1: Increase in internal resistance after high-temperature storage] Immediately after assembly, the battery was discharged by a capacity equivalent to 2.5% of the design capacity, then stored at 60°C for 3 days, and the internal resistance R0 of the battery after storage was measured. The battery was then stored at 70°C for 1 week. After storage at 70°C for 1 week, the internal resistance R1 of the battery was measured. The internal resistance was determined by measuring the AC resistance (ACR) using the two-terminal method in an environment of 25°C. The AC current measurement frequency was 1 kHz.

[0105] Using the above R0 and R1, the rate of increase (%) of internal resistance was calculated using the following formula.

[0106] Internal resistance increase rate = (R1-R0) / R0 x 100 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 of Comparative Example 2 is set to 100. A smaller rate of increase in internal resistance indicates that the increase in internal resistance after storage is more suppressed.

[0107] The rate of capacity decrease after high-temperature storage was measured for the batteries A1 to A3, A5 to A10 and B2 to B6 as follows.

[0108] [Evaluation 2: Capacity loss rate after high-temperature storage] Immediately after assembly, the battery was discharged for a capacity equivalent to 2.5% of the design capacity (C0), and then stored at 60°C for 3 days. After storage, the battery was discharged in an environment of 25°C at a current of 4.5 mA per unit mass (g) of manganese dioxide until the battery voltage reached 2 V. The discharge capacity C1 (mAh / g) at this time was calculated.

[0109] Using the above C0 and C1, the capacity decrease rate (%) was calculated according to the following formula.

[0110] Capacity reduction rate = (C0-C1) / C0×100 In Table 2, the capacity loss rate is expressed as a relative value when the capacity loss rate of battery B3 of Comparative Example 3 is set to 100. A smaller capacity loss rate indicates that the capacity loss after storage is more suppressed.

[0111] The evaluation results are shown in Tables 1 and 2.

[0112] [Table 1]

[0113] [Table 2]

[0114] In batteries A1 to A3, in which the nonaqueous electrolyte solution contained the first component and the second component, the rate of increase in internal resistance after storage was significantly reduced, and the rate of decrease in capacity after storage was significantly reduced, compared to batteries B1 to B3. The above-mentioned effects of the examples can be obtained when the nonaqueous electrolyte solution satisfies at least one of the above conditions (a) and (b) (compare Examples 1 to 3, 5 to 10 with Comparative Examples 2 to 6).

[0115] In battery B2, whose nonaqueous electrolyte contained the first component but not the second component, the rate of increase in internal resistance after storage was smaller but not sufficient, and the rate of capacity loss after storage was larger than in battery B3, whose nonaqueous electrolyte contained neither the first component nor the second component.Similarly, in battery B1, whose nonaqueous electrolyte contained the second component but not the first component, the suppression of internal resistance after storage was insufficient compared to batteries A1 to A4. [Industrial Applicability]

[0116] The lithium primary battery of the present disclosure can significantly suppress an increase in internal resistance during high-temperature storage. Therefore, the lithium primary battery is suitable for use, for example, as a main power source for various meters or a memory backup power source. However, the uses of the lithium primary battery are not limited to these. [Explanation of symbols]

[0117] 1 positive electrode 1a Positive electrode current collector 2 negative electrode 3 Separator 4 Positive lead 5 Negative lead 6 Upper insulating plate 7 Lower insulating plate 8 Sealing plate 9 Battery case 10. Lithium primary batteries

Claims

1. The battery comprises a positive electrode, a negative electrode, and a non-aqueous electrolyte solution, The positive electrode is LixMnO ２ (0≦x≦0.05), the negative electrode contains at least one of metallic lithium and a lithium alloy containing 0.05 to 15 mass % of metal elements other than lithium, the nonaqueous electrolyte solution includes, as a first component, at least one of a cyclic imide component and a pyrrole component, and as a second component, an oxalate phosphate complex component; The concentration of the first component in the nonaqueous electrolyte solution is 1% by mass or less, The concentration of the second component in the nonaqueous electrolyte solution is 6% by mass or less, a mass ratio of the first component to the second component contained in the nonaqueous electrolyte solution is 0.02 or more and 10 or less; The oxalate phosphate complex component comprises at least one selected from the group consisting of a tetrafluoro(oxalate) phosphate complex component, a difluorobis(oxalate) phosphate complex component, and a tris(oxalate) phosphate complex component.

2. The battery comprises a positive electrode, a negative electrode, and a non-aqueous electrolyte solution, The positive electrode is LixMnO ２ (0≦x≦0.05), the negative electrode contains at least one of metallic lithium and a lithium alloy containing 0.05 to 15 mass % of metal elements other than lithium, the nonaqueous electrolyte solution includes, as a first component, at least one of a cyclic imide component and a pyrrole component, and as a second component, an oxalate phosphate complex component; The concentration of the first component in the nonaqueous electrolyte solution is 0.1% by mass or more and 1% by mass or less, The concentration of the second component in the nonaqueous electrolyte solution is 0.1% by mass or more and 6% by mass or less, The oxalate phosphate complex component comprises at least one selected from the group consisting of a tetrafluoro(oxalate) phosphate complex component, a difluorobis(oxalate) phosphate complex component, and a tris(oxalate) phosphate complex component.

3. 3. The lithium primary battery according to claim 2, wherein a mass ratio of the first component to the second component contained in the nonaqueous electrolyte solution is 0.02 or more and 10 or less.

4. 4. 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.

5. the first component is the cyclic imide component; 3. The lithium primary battery according to claim 1, wherein the cyclic imide component comprises phthalimide.

6. the first component is the pyrrole component; The lithium primary battery according to claim 1 or 2, wherein the pyrrole component includes indole.

7. The positive electrode mixture further contains a sulfate, 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 relative to 100 parts by mass of manganese atoms contained in the positive electrode mixture. The lithium primary battery according to any one of claims 1 to 6.

8. LixMnO ２ The lithium primary battery according to any one of claims 1 to 7, wherein the median particle size is 10 µm or more and 40 µm or less.

9. LixMnO ２ The BET specific surface area of ２ / g or more, 40m ２ The lithium primary battery according to any one of claims 1 to 8, wherein the Cr content is 0.15 / g or less.

10. the positive electrode comprises a perforated current collector 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 lithium primary battery according to any one of claims 1 to 9, wherein the thickness of the positive electrode is 300 µm or more and 900 µm or less.

11. The lithium primary battery according to any one of claims 1 to 10, wherein the negative electrode includes a foil of the metallic lithium or the lithium alloy and has a shape having a longitudinal direction and a transverse direction, and a long tape including a resin base material and an adhesive layer is attached to at least one main surface of the negative electrode along the longitudinal direction.

12. LixMnO ２ (0≦x≦0.05) A non-aqueous electrolyte solution for use in a lithium primary battery, the non-aqueous electrolyte solution comprising: a positive electrode containing a positive electrode mixture containing (0≦x≦0.05); a negative electrode containing at least one of metallic lithium and a lithium alloy containing 0.05 to 15 mass % of a metal element other than lithium; and the nonaqueous electrolyte solution includes, as a first component, at least one of a cyclic imide component and a pyrrole component, and as a second component, an oxalate phosphate complex component; The concentration of the first component in the nonaqueous electrolyte solution is 0.1% by mass or more and 1% by mass or less, The concentration of the second component in the nonaqueous electrolyte solution is 0.1% by mass or more and 6% by mass or less, the oxalate phosphate complex component includes at least one selected from the group consisting of a tetrafluoro(oxalate) phosphate complex component, a difluorobis(oxalate) phosphate complex component, and a tris(oxalate) phosphate complex component.

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