Lithium primary battery

Abstract

The present disclosure provides a lithium primary battery which is capable of exhibiting high output characteristics from the initial stage of discharge to the end stage of discharge. A lithium primary battery according to the present disclosure includes a positive electrode (4), a negative electrode (5) that faces the positive electrode (4), a separator (6) that is disposed between the positive electrode (4) and the negative electrode (5), and an electrolyte solution. The positive electrode (4) includes manganese dioxide and a boron compound. The manganese dioxide includes a β-type crystal structure, and the cumulative pore volume Vp of pores having a diameter of 0.5 nm to 50 nm inclusive is 0.015 mL / g to 0.035 mL / g inclusive as determined from the pore volume distribution measured by a mercury intrusion method.

Description

Lithium primary battery

[0001] The present invention relates to a lithium primary battery, and more specifically to a lithium primary battery containing manganese dioxide having a specific structure as a positive electrode active material.

[0002] Lithium primary batteries have a high electromotive force and a high energy density, and are therefore widely used as main power sources or memory backup power sources in electronic devices such as portable devices and in-vehicle electronic devices. A lithium primary battery typically includes a positive electrode, a negative electrode facing the positive electrode, a separator disposed between the positive electrode and the negative electrode, and an electrolyte (non-aqueous electrolyte). In most lithium primary batteries, the negative electrode contains metallic lithium, and the positive electrode contains manganese dioxide as a positive electrode active material.

[0003] In recent years, as electronic devices such as those described above have become more multifunctional, lithium primary batteries used in such electronic devices are required to exhibit high output characteristics from the initial stage of discharge to the final stage of discharge.

[0004] In the following Patent Document 1, a cathode of a lithium primary battery is provided with a specific surface area of ​​15 to 40 m ２ / g manganese dioxide (positive electrode active material) and a boron compound (additive). Patent Document 1 below also describes that a lithium primary battery including such a positive electrode suppresses an increase in internal resistance even when stored for a long period of time (when stored at 80°C for 30 days), and can exhibit high output characteristics at a depth of discharge of 0% (initial stage of discharge).

[0005] Patent Document 2 below describes forming a surface layer of a boron-containing material (e.g., boron oxide) on a lithium negative electrode. Patent Document 2 below also describes that a battery including a lithium negative electrode on which such a surface layer is formed suppresses excessive passivation of the negative electrode during storage and discharge, and therefore can exhibit high output characteristics during a relatively short discharge time (30 seconds) (i.e., at the beginning of discharge) even after long-term storage (e.g., storage for 45 days at 25°C).

[0006] Patent Document 3 listed below describes a lithium primary battery in which the positive electrode contains 0.1 to 3.0 mass % of boron and the negative electrode is a lithium alloy containing 2.5 to 10 mass % of a metal other than lithium. Patent Document 3 also describes that in the lithium primary battery configured as above, elution of manganese dioxide from the positive electrode is suppressed and the discharge capacity is maintained until the end of discharge.

[0007] JP 2009-283291 A JP 59-117070 A JP 2004-327304 A

[0008] As described above, Patent Documents 1 and 2 consider how to make a lithium primary battery exhibit high output characteristics in the early stage of discharge, but it is difficult to say that they consider how to make the battery exhibit high output characteristics until the end of discharge. Also, Patent Document 3 considers how to maintain the discharge capacity until the end of discharge in a lithium primary battery, but it is difficult to say that they consider how to make the battery exhibit high output characteristics until the end of discharge. In other words, it is difficult to say that sufficient consideration has yet been given to making a lithium primary battery exhibit high output characteristics from the early stage to the end of discharge.

[0009] Therefore, an object of the present disclosure is to provide a lithium primary battery that can exhibit high output characteristics from the initial stage of discharge to the final stage of discharge.

[0010] One aspect of the present invention is a battery comprising: a positive electrode; a negative electrode facing the positive electrode; a separator disposed between the positive electrode and the negative electrode; and an electrolyte solution, wherein the positive electrode comprises manganese dioxide and a boron compound, the manganese dioxide having a β-type crystal structure, and a cumulative pore volume V of pores having a diameter of 0.5 nm or more and 50 nm or less obtained from a pore volume distribution measured by mercury intrusion porosimetry. ｐ The present invention relates to a lithium primary battery in which the capacitance is 0.015 mL / g or more and 0.035 mL / g or less.

[0011] According to the present disclosure, it is possible to provide a lithium primary battery that can exhibit high output characteristics from the initial stage of discharge to the final stage of discharge.

[0012] FIG. 1 is a longitudinal cross-sectional view of a coin-type lithium primary battery according to an embodiment of the present disclosure.

[0013] Below, embodiments of the present disclosure will be described using examples, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be exemplified, but other numerical values, materials, etc. may be applied as long as the effects of the present disclosure are obtained. Note that known components may be applied to components characteristic of the present disclosure. In this specification, when a "range from numerical value A to numerical value B" is mentioned, the range includes numerical value A and numerical value B.

[0014] In the following description, when lower and upper limits of numerical values ​​relating to specific physical properties, conditions, etc. are exemplified, any of the exemplified lower limits and any of the exemplified upper limits can be arbitrarily combined, as long as the lower limit is not equal to or greater than the upper limit. When multiple materials are exemplified, one of them can be selected and used alone, or two or more can be used in combination, unless otherwise specified.

[0015] The present disclosure encompasses any combination of two or more features arbitrarily selected from the appended claims, i.e., any combination of two or more features arbitrarily selected from the appended claims can be combined unless a technical contradiction arises.

[0016] [Lithium Primary Battery] A lithium primary battery according to an embodiment of the present disclosure includes a positive electrode, a negative electrode facing the positive electrode, a separator disposed between the positive electrode and the negative electrode, and an electrolyte. The positive electrode, negative electrode, separator, and electrolyte are typically sealed and housed in a predetermined exterior (e.g., a battery case). Hereinafter, the assembly of the positive electrode, negative electrode, separator, and electrolyte may be referred to as a power generating element. In the lithium primary battery according to an embodiment of the present disclosure, the positive electrode includes manganese dioxide and a boron compound. In the lithium primary battery according to an embodiment of the present disclosure, the manganese dioxide has a β-type crystal structure, and the cumulative pore volume V of pores having a diameter of 0.5 nm or more and 50 nm or less obtained from a pore volume distribution measured by mercury intrusion porosimetry is ｐis 0.015 mL / g or more and 0.035 mL / g or less.

[0017] (Positive Electrode) The positive electrode is formed by press-molding a positive electrode mixture into a predetermined shape. The positive electrode mixture contains manganese dioxide and a boron compound. Note that manganese dioxide is a positive electrode active material, and the boron compound is an additive for forming a protective film (intermediate film (C) and film (D) described below) on the surface of the negative electrode. When the lithium primary battery has a coin shape (or button shape), the positive electrode mixture has a pellet shape or a cylindrical (disk) shape corresponding to the coin shape. When the lithium primary battery has a coin shape, the thickness T of the positive electrode may be, for example, 400 μm or more and 2000 μm or less.

[0018] The manganese dioxide is preferably electrolytic manganese dioxide. Electrolytic manganese dioxide can usually be obtained by electrolyzing an aqueous manganese sulfate solution. The electrolytic manganese dioxide may be neutralized with an alkali, washed with water, or calcined. For example, the electrolytic manganese dioxide may be calcined in air or oxygen at 300 to 450°C for approximately 2 to 12 hours. Calcining the electrolytic manganese dioxide can volatilize water and promote crystallization. Furthermore, by controlling the calcination process, the electrolytic manganese dioxide can be made to contain a large amount of β-type crystal structure. Furthermore, by promoting crystallization, the specific surface area can be reduced. This can improve the structural stability and water-resistant reactivity of the electrolytic manganese dioxide. When uncalcined electrolytic manganese dioxide is used, the crystallinity can be increased by adjusting the conditions during electrolysis to reduce the specific surface area. Note that manganese dioxide other than electrolytic manganese dioxide can also be made to contain a large amount of β-type crystal structure by controlling the calcination process.

[0019] As described above, manganese dioxide contains a β-type crystal structure. Manganese dioxide may contain a crystal structure other than the β-type. Manganese dioxide may contain, for example, an α-type, γ-type, δ-type, ε-type, η-type, λ-type, or ramsdellite-type crystal structure. It is preferable that manganese dioxide contains 50 mass% or more (majority) of the β-type crystal structure. The crystal structure of manganese dioxide can be analyzed using a general X-ray diffractometer (e.g., MXP-3 manufactured by Mac Science). This analysis can be performed using CuKα radiation (λ = 1.5405 Å) as the radiation source, step scan as the measurement mode, scan conditions of 0.04° / second, measurement time of 3 seconds, and a measurement range of 2θ from 5° to 80°. The content of the β-type crystal structure in manganese dioxide can be determined by performing Rietveld analysis fitting based on parameters such as peak positions and peak intensities shown in the diffraction profile obtained by analysis using the X-ray diffractometer. The content of the β-type crystal structure in manganese dioxide can be adjusted, for example, by subjecting manganese dioxide to a calcination treatment, as described above. For example, the content of the β-type crystal structure in manganese dioxide can be increased by increasing the calcination temperature or lengthening the calcination time.

[0020] The boron compound is preferably a compound having at least one of a B—O bond and a B═O bond. Whether the boron compound is a compound having at least one of a B—O bond and a B═O bond can be confirmed, for example, by XPS analysis. The boron compound is preferably at least one selected from the group consisting of boric acid, boron oxide, and lithium borate, and H ３ BO ３ , B ２ O ３ , LiBO ２ , Li ２ B ４ O ７ , and Li ３ BO ３It is more preferable that the boron compound is at least one selected from the group consisting of: By using such a boron compound, it becomes easier to form a good protective film on the surface of the negative electrode.

[0021] The lithium primary battery according to the embodiment of the present disclosure preferably contains a boron compound in an amount of 0.1 parts by mass or more and 0.8 parts by mass or less, calculated as boron element, per 100 parts by mass of manganese dioxide. The content of the boron compound may be 0.2 parts by mass or more, or 0.3 parts by mass or more. The content of the boron compound may be 0.6 parts by mass or less, or 0.5 parts by mass or less. When the content of the boron compound is within the above range, a good protective film is easily formed on the surface of the negative electrode from the beginning to the end of discharge. As a result, the lithium primary battery according to the embodiment of the present disclosure can exhibit high output characteristics from the beginning to the end of discharge.

[0022] In the lithium primary battery according to the embodiment of the present disclosure, the manganese dioxide has an integrated pore volume V of pores having a diameter of 0.5 nm or more and 50 nm or less obtained from the pore volume distribution measured by mercury intrusion porosimetry. ｐ It is important that the concentration is 0.015 mL / g or more and 0.035 mL / g or less. The reason for this will be explained below.

[0023] It is believed that four reactions are occurring competitively on the surface of the negative electrode of a lithium primary battery: (1) a reaction to form a passive film (A) due to a reaction between water and the surface of the negative electrode; (2) deposition of an organic resistive component (organic film) (B) derived from the electrolyte decomposed during storage and discharge; (3) a reaction to form an intermediate film (C) due to a reaction between a boron-containing intermediate produced by contact between a boron compound and manganese dioxide and the surface of the negative electrode; and (4) a reaction to form a film (D) due to a reaction between a boron-containing product produced from the boron-containing intermediate and the surface of the negative electrode.

[0024] The boron-containing intermediate can exist in various forms and is thought to be an ionic species generated by decomposition of a boron compound by the catalytic action of manganese dioxide. The intermediate film (C) formed by reaction of the boron-containing intermediate with the negative electrode surface has lower resistance than the water-derived passivation film (A) resulting from the reaction between water and the negative electrode surface and the organic film (B) derived from the electrolyte solution, and can suppress an increase in internal resistance (IR). However, the suppression effect is not sufficient.

[0025] The boron-containing product may exist in various forms, and the results of TOF-SIMS analysis show that it is mainly Li ２ BO ２ Cation, BO ２ It is believed that Li exists in the electrolyte as an anion. ２ BO ２ The cation is LiBO ２ is a cation obtained by bonding Li ions to BO ２ The anion is LiBO ２ It is an anion obtained by desorbing Li ions from the boron-containing product. Hereinafter, the boron-containing product will also be referred to as "LBO ion."

[0026] It is believed that the film (D) formed by the reaction of LBO ions with the surface of the negative electrode can suppress an increase in internal resistance (IR) by sacrificially reacting with water. In addition, the film (D) on the surface of the negative electrode is consumed by the current during discharge and refreshed. That is, it is believed that the film (D) is repeatedly formed and removed on the surface of the negative electrode during storage and discharge of the lithium primary battery. Therefore, if the positive electrode contains a boron compound, the LBO ions necessary for repairing the film (D) are continuously supplied to a certain extent during discharge of the lithium primary battery. However, there is a concern that simply including a boron compound in the positive electrode may result in a situation where, although sufficient LBO ions can be supplied to the surface of the negative electrode at the beginning of discharge, sufficient LBO ions cannot be supplied to the surface of the negative electrode at the end of discharge. In such a case, there is a concern that the internal resistance (IR) increases at the end of discharge, resulting in a decrease in output characteristics. Therefore, in order to make a lithium primary battery exhibit high output characteristics at the end of discharge, it is necessary to be able to supply a sufficient amount of LBO ions to the surface of the negative electrode even at the end of discharge.

[0027] In the lithium primary battery according to the embodiment of the present disclosure, as described above, the positive electrode active material is a positive electrode active material having an integrated pore volume V of pores having a diameter of 0.5 nm or more and 50 nm or less, which is obtained from a pore volume distribution measured by mercury intrusion porosimetry. ｐThe present invention uses manganese dioxide having a specific surface area of ​​0.015 mL / g or more and 0.035 mL / g or less. Specifically, the present invention uses manganese dioxide as the positive electrode active material, in which pores having diameters corresponding to mesopores exist in a predetermined volume range. Therefore, the boron compound retained inside the pores having diameters corresponding to mesopores can be effectively utilized at the end of discharge. Specifically, the boron compound retained inside the pores having diameters corresponding to mesopores can be continuously supplied until the end of discharge. Furthermore, at the beginning of discharge, the boron compound adsorbed on the outer surface of the manganese dioxide and the boron compound retained inside the pores corresponding to the macropores (pores larger than 50 μm) of the manganese dioxide can be effectively utilized. This is believed to enable sufficient LBO ions to be supplied to the surface of the negative electrode from the beginning of discharge to the end of discharge. As a result, the lithium primary battery according to the embodiment of the present disclosure is believed to be able to exhibit high output characteristics from the beginning of discharge to the end of discharge. The cumulative pore volume V ｐ If the total volume of the boron compound is less than 0.015 mL / g, it is not possible to retain a sufficient amount of the boron compound in the pores having a diameter equivalent to that of the mesopores until the end of the discharge, which is undesirable. ｐ If the concentration exceeds 0.035 mL / g, the boron compound will be excessively retained in the pores corresponding to the mesopores, which is undesirable as it will be impossible to secure the boron compound required to repair the coating (D) at the initial stage of discharge.

[0028] Cumulative pore volume V ｐ is preferably 0.020 mL / g or more and 0.030 mL / g or less. ｐ When the value of is in the above-mentioned range, the boron compound held in the pores having a diameter of 0.5 nm or more and 50 nm or less in the manganese dioxide is more easily supplied to the negative electrode at the end of discharge. This makes it easier to form a better protective film on the surface of the negative electrode at the end of discharge. As a result, the lithium primary battery according to the embodiment of the present disclosure is more likely to exhibit high output characteristics from the beginning to the end of discharge.

[0029] Cumulative pore volume V ｐcan be calculated from the pore distribution data of the positive electrode active material (manganese dioxide) or the positive electrode obtained by mercury intrusion porosimetry. As explained above, the positive electrode is formed by press-molding the positive electrode mixture into a predetermined shape. Generally, when measuring the pores formed in the positive electrode by mercury intrusion porosimetry, the diameter of the pores formed in the positive electrode active material (manganese dioxide) is evaluated. The cumulative pore volume V ｐ For example, the first integrated pore volume V is calculated by integrating the pore volume from the maximum diameter to 0.5 nm using the pore distribution data of the positive electrode active material (manganese dioxide). ｐ１ and the pore volumes from the maximum diameter to 50 nm are integrated to obtain a second integrated pore volume V ｐ２ After obtaining the first cumulative pore volume V ｐ１ to the second cumulative pore volume V ｐ２ It can be calculated by subtracting the cumulative pore volume V ｐ When calculating the mass of the positive electrode active material (manganese dioxide) after drying, the mass of the positive electrode active material is used as the reference (denominator). The mass of the positive electrode active material can be calculated, for example, by subtracting the mass of the acid-insoluble residue that does not dissolve when the positive electrode is dissolved in acid from the mass of the positive electrode.

[0030] The pore size distribution of the positive electrode can be measured by mercury porosimetry, for example, by removing the positive electrode from an exterior such as a battery case, drying it, and then analyzing the dried positive electrode using a mercury porosimetry pore size distribution analyzer. For example, in the case of a positive electrode formed by pressure molding a positive electrode mixture into a pellet or cylindrical (disk) shape, a doughnut-shaped measurement sample is cut out from the positive electrode, and this measurement sample is divided into three equal parts to obtain three measurement pieces. Two of the three measurement pieces are then placed in a measurement cell in a mercury porosimetry pore size distribution analyzer for analysis.

[0031] In the pore volume distribution obtained by mercury intrusion porosimetry, the manganese dioxide preferably has a first peak having a peak top in the range of 8 nm to 12 nm and a second peak having a peak top in the range of 25 nm to 30 nm. The ratio (Ib / Ia) of the peak intensity Ib of the second peak to the peak intensity Ia of the first peak is preferably 10 or greater. That is, among the pores having diameters corresponding to mesopores, it is preferable that the pore volume of the pores having larger diameters be sufficiently higher than the pore volume of the pores having smaller diameters. This allows the pores having diameters corresponding to mesopores to more suitably retain a sufficient amount of boron compound for repairing the coating (C) until the end of discharge. As a result, the boron compound retained in the pores having diameters corresponding to mesopores can be more suitably supplied until the end of discharge. Ib / Ia may be 20 or greater or 40 or greater. Furthermore, Ib / Ia may be 100 or less or 60 or less.

[0032] The volume-based median diameter (D50) of manganese dioxide measured with a laser diffraction / scattering measuring device may be, for example, 20 μm or more and 50 μm or less, 20 μm or more and 45 μm or less, or 20 μm or more and 35 μm or less. When the median diameter of manganese dioxide is 20 μm or more, the number of contact points between manganese dioxide particles in the positive electrode mixture can be increased. When the median diameter of manganese dioxide is 50 μm or less, the pressure required when forming the positive electrode mixture can be reduced, and the packing density of the positive electrode mixture can be easily improved.

[0033] The positive electrode may further contain a binder. Examples of binders include fluororesins, rubber particles, and acrylic resins. Examples of fluororesins include polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and polyvinylidene fluoride (PVDF). Examples of rubber particles include styrene butadiene rubber (SBR) and modified acrylonitrile rubber. Examples of acrylic resins include ethylene-acrylic acid copolymers. One type of binder may be used alone, or two or more types may be used in combination.

[0034] Among the various binders described above, the positive electrode preferably contains a fluororesin, and among the fluororesins, a fibrous fluororesin is more preferably included. The fibrous fluororesin does not excessively coat the surface of the manganese dioxide. This allows the boron compound to smoothly penetrate into the pores of the manganese dioxide and smoothly escape from the pores of the manganese dioxide. Furthermore, by not excessively coating the surface of the manganese dioxide, the electrolyte can be sufficiently brought into contact with the surface of the manganese dioxide. The fibrous fluororesin may be a fluororesin that does not dissolve in N-methyl-2-pyrrolidone (NMP) and disperses as particles. The fibrous fluororesin may be a fluororesin that fibrillates due to the pressure applied to the positive electrode mixture when fabricating the positive electrode.

[0035] Examples of fibrous fluororesin include polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF). The fibrous fluororesin is preferably polytetrafluoroethylene. When the fibrous fluororesin is polytetrafluoroethylene, it is possible to further prevent the surface of the manganese dioxide from being excessively coated. This allows the boron compound to more smoothly penetrate into the pores of the manganese dioxide and to more smoothly discharge the boron compound from the pores of the manganese dioxide. In addition, the electrolyte can be brought into more sufficient contact with the surface of the manganese dioxide. Polytetrafluoroethylene is a fluororesin containing tetrafluoroethylene units (-CF ２ CF ２The polytetrafluoroethylene may have a weight average molecular weight Mw of 200,000 or more and 800,000 or less.

[0036] The positive electrode may contain 1% by mass or more and 10% by mass or less of the binder, or may contain 1% by mass or more and 5% by mass or less. When the positive electrode contains 1% by mass or more of the binder, the positive electrode capacity can be sufficiently ensured and the strength of the positive electrode can be sufficiently ensured. When the positive electrode contains 10% by mass or less of the binder, the positive electrode capacity can be sufficiently ensured and an increase in internal resistance can be sufficiently suppressed. The binder may contain 80% by mass or more, or may contain 90% by mass or more of the fibrous fluororesin. Furthermore, the binder may contain 100% by mass of the fibrous fluororesin. That is, the binder may contain only the fibrous fluororesin.

[0037] The positive electrode may contain graphite. Graphite functions as a conductive additive. By including graphite in the positive electrode, sufficient electron conduction paths are ensured within the positive electrode. As a result, sufficient output power of the lithium primary battery is ensured.

[0038] The graphite may contain expanded graphite. The expanded graphite particles have a flat shape. The expanded graphite may be one that begins to expand by inserting an agent such as sulfuric acid or an organic acid between the basal planes of the graphite to widen the spacing between the basal planes (interlayer expansion) at a temperature of about 150°C to 300°C. Expanded graphite has a large interplanar spacing in the c-axis direction perpendicular to the basal planes, making it prone to exfoliation and therefore prone to becoming flat. The interplanar spacing (d200) of the (002) plane of the expanded graphite may be, for example, 3.37 Å or more. The crystallite size Lc(002) in the c-axis direction may be, for example, 500 Å or less. The interplanar spacing (d002) and the crystallite size Lc(002) can be obtained by analyzing data obtained by powder X-ray diffraction using CuKα radiation. Expanded graphite usually contains trace amounts of sulfate ions (SO ３ －) remains.

[0039] The interplanar spacing (d002) can be calculated using the Bragg formula (λ=2d×sin θ).

[0040] λ: wavelength of CuKα ray (= 0.15418 nm) d: average interplanar spacing d002 of the (002) plane θ: half angle of 2θ at the peak position determined by the centroid method (rad) The crystallite size Lc(002) can be calculated from the half width of the X-ray diffraction peak assigned to the (002) plane using Scherrer's formula (D(nm) = 0.9 × λ / (β × cos θ)).

[0041] λ: CuKα wavelength (= 0.15418 nm) D: crystallite size β: half-width of the peak θ: 1 / 2 angle (rad) of 2θ at the peak position determined by the centroid method The positive electrode may contain 1% by mass or more and 10% by mass or less of graphite, or 1% by mass or more and 5% by mass or less. By containing 1% by mass or more of graphite in the positive electrode, the positive electrode capacity can be sufficiently ensured and the function as a conductive additive can also be sufficiently ensured. The graphite may contain 80% by mass or more of expanded graphite, or may contain 90% by mass or more. Furthermore, the graphite may contain 100% by mass of expanded graphite. That is, the graphite may contain only expanded graphite.

[0042] In the lithium primary battery according to the embodiment of the present disclosure, the area of ​​the surface of the negative electrode facing the positive electrode is S (mm ２ ), and the mass of manganese dioxide contained in the positive electrode is W (g), the ratio of S to W (S / W (mm ２ / g)) is preferably 80 or more and 300 or less. When S / W is within the above range, manganese dioxide easily retains a sufficient amount of boron compound to form and repair the coating (C) on the surface of the negative electrode. Note that an S / W ratio of more than 300 is undesirable because it becomes difficult to form a coating (C) that sufficiently covers the surface of the negative electrode. An S / W ratio of less than 80 is undesirable because an excess amount of boron compound is present compared to that required to form the coating (C), and some of the boron compound remaining on the outer surface of the manganese dioxide, etc., may inhibit the battery reaction. S / W may be 100 or more, or 130 or more. Furthermore, S / W may be 250 or less, or 170 or less.

[0043] (Negative Electrode) The negative electrode can be obtained, for example, by processing a metal sheet or metal foil into a predetermined shape. The metal sheet is formed, for example, from at least one of lithium metal and a lithium alloy. Examples of lithium alloys include lithium-aluminum alloys, lithium-tin alloys, lithium-silicon alloys, and lithium-lead alloys. When the lithium primary battery has a coin shape, the negative electrode has a disk shape corresponding to the coin shape. When the lithium primary battery has a coin shape, a foil made of at least one of lithium metal and a lithium alloy may be punched into a circle and used as the negative electrode.

[0044] (Exterior Body) When the lithium primary battery has a coin shape, the exterior body includes, for example, a case having a bottom plate and sidewalls rising from the periphery of the bottom plate, a sealing plate having a top plate and a periphery extending from the periphery of the top plate to the inside of the sidewalls of the case, and a gasket compressed and interposed between the sidewalls of the case and the periphery of the sealing plate. In the exterior body, the outer surface of the bottom plate of the case serves as a first terminal surface (e.g., a positive electrode terminal surface), and the outer surface of the top plate of the sealing plate serves as a second terminal surface (e.g., a negative electrode terminal surface). In addition, in the exterior body, the end of the sidewall of the case is bent inward. By being bent in this manner, the end of the sidewall is crimped to the periphery of the sealing plate via the gasket.

[0045] The electrolyte contains a non-aqueous solvent and a solute (salt). The solute concentration in the electrolyte is, for example, 0.3 mol / L or more and 2.0 mol / L or less. As the non-aqueous solvent, propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, etc. can be used. These may be used alone or in combination of two or more. As the solute, LiClO ４ , LiPF ６ , LiBF ４ , LiCF ３ SO ３ , LiN(CF ３ SO ２ ) ２ etc. can be used.

[0046] The separator may be made of any material that can prevent short-circuiting between the positive electrode and the negative electrode and retain the electrolyte. Examples of the separator include woven fabric, nonwoven fabric, and microporous film made of polyolefin, polyester, etc. Among these, it is preferable to use a polypropylene nonwoven fabric as the separator.

[0047] Next, a specific configuration of a coin-type lithium primary battery according to an embodiment of the present disclosure will be described with reference to the drawings. Fig. 1 is a longitudinal sectional view of a coin-type lithium primary battery according to an embodiment of the present disclosure.

[0048] The coin-type lithium primary battery 11 has an exterior body composed of a case 3, a sealing plate 8, and a gasket 7. The case 3 is a battery can having a bottom plate 3a and a side wall 3b rising from the periphery of the bottom plate 3a. In the case 3, the bottom plate 3a and the side wall 3b are connected via a bent portion 9. The case 3 is formed in a shallow cylindrical shape. The sealing plate 8 has a top plate 8a and a peripheral edge 8b extending from the periphery of the top plate 8a to the inside of the side wall 3b of the case 3. In the coin-type lithium primary battery 11, the end of the side wall 3b of the case 3 is bent inward. This bending allows the end of the side wall 3b to be crimped to the peripheral edge 8b of the sealing plate 8 via the gasket 7. This seals the gap between the case 3 and the sealing plate 8 in the coin-type lithium primary battery 11.

[0049] The exterior housing contains a power generating element. The power generating element includes a positive electrode 4, a negative electrode 5, a separator 6, and an electrolyte. In the example shown in FIG. 1 , the positive electrode 4 is disposed so as to face the bottom plate portion 3a of the case 3. Therefore, the outer surface of the bottom plate portion 3a functions as a positive electrode terminal surface. On the other hand, the negative electrode 5 is disposed so as to face the top plate portion 8a of the sealing plate 8. Therefore, the outer surface of the top plate portion 8a functions as a negative electrode terminal surface.

[0050] The structure of the lithium primary battery according to the embodiment of the present disclosure is not particularly limited. The lithium primary battery according to the embodiment of the present disclosure may be a coin-type lithium primary battery as described above, or may be a cylindrical lithium primary battery including a wound electrode group formed by spirally winding a strip-shaped positive electrode and a strip-shaped negative electrode with a separator interposed therebetween.

[0051] (Additional Note) The above description discloses the following techniques.

[0052] (Technology 1) A battery comprising: a positive electrode; a negative electrode facing the positive electrode; a separator disposed between the positive electrode and the negative electrode; and an electrolyte; wherein the positive electrode comprises manganese dioxide and a boron compound; the manganese dioxide has a β-type crystal structure; and the cumulative pore volume V of pores having a diameter of 0.5 nm or more and 50 nm or less obtained from a pore volume distribution measured by mercury intrusion porosimetry is ｐ A lithium primary battery, wherein the average capacitance is 0.015 mL / g or more and 0.035 mL / g or less.

[0053] (Technology 2) The cumulative pore volume V ｐ The lithium primary battery according to claim 1, wherein the ionic conductivity is 0.020 mL / g or more and 0.30 mL / g or less.

[0054] (Technology 3) The lithium primary battery according to Technology 1 or 2, wherein the manganese dioxide has, in the pore volume distribution, a first peak having a peak top in a range of 8 nm or more and 12 nm or less and a second peak having a peak top in a range of 25 nm or more and 30 nm or less, and a ratio (Ib / Ia) of a peak intensity Ib of the second peak to a peak intensity Ia of the first peak is 10 or more.

[0055] (Technology 4) The area of ​​the surface of the negative electrode facing the positive electrode is S (mm ２ ), and the mass of the manganese dioxide contained in the positive electrode is W (g), the ratio of S to W (S / C (mm ２ / g)) is 80 or more and 300 or less.

[0056] (Technology 5) The lithium primary battery according to any one of Technologies 1 to 4, wherein the boron compound is a compound having at least one of a B—O bond and a B═O bond.

[0057] (Technology 6) The lithium primary battery according to Technology 5, wherein the boron compound is at least one selected from the group consisting of boric acid, boron oxide, and lithium borate.

[0058] (Technology 7) The boron compound is H ２ BO ３, B ２ O ３ , LiBO ２ , Li ２ B ４ O ７ , and Li ３ BO ３ The lithium primary battery according to claim 6, wherein the lithium primary battery is at least one selected from the group consisting of:

[0059] (Technology 8) The lithium primary battery according to any one of Technologies 1 to 7, wherein the boron compound is contained in an amount of 0.1 parts by mass or more and 0.8 parts by mass or less in terms of boron element per 100 parts by mass of the manganese dioxide.

[0060] (Technology 9) The lithium primary battery according to any one of Technologies 1 to 8, wherein the positive electrode further contains a binder, and the binder contains a fibrous fluororesin.

[0061] (Technology 10) The lithium primary battery according to Technology 9, wherein the binder contains polytetrafluoroethylene as the fibrous fluororesin.

[0062] While the present invention has been described in terms of presently preferred embodiments, such disclosure should not be interpreted as limiting. Various changes and modifications will no doubt become apparent to those skilled in the art to which the present invention pertains upon reading the above disclosure. It is therefore intended that the appended claims be interpreted to cover all changes and modifications that do not depart from the true spirit and scope of the invention.

[0063] 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.

[0064] Example 1 (1) Positive Electrode A first electrolytic manganese dioxide having a β-type crystal structure (hereinafter simply referred to as first electrolytic manganese dioxide) was prepared as a positive electrode active material. The first electrolytic manganese dioxide was obtained by calcining water-containing manganese dioxide (hereinafter also referred to as hydrous manganese dioxide) in a batch-type calcination furnace. Specifically, the hydrous manganese dioxide was heated while the temperature inside the furnace was increased to 450°C under air supply, and the water was removed from the furnace (temperature-raising and heating step). Then, with the air supply stopped, the hydrous manganese dioxide from which a predetermined amount of water had been removed was calcined at 450°C for 3 hours (calcination step), thereby obtaining the first electrolytic manganese dioxide. Note that in the temperature-raising and heating step, the amount of water vapor during the calcination step was 15 g / m ３ Air was supplied so that

[0065] For the first electrolytic manganese dioxide, the cumulative pore volume V of pores having a diameter of 0.5 nm or more and 50 nm or less was calculated according to the method described above. ｐ The average molecular weight (mL / g) of the first electrolytic manganese dioxide was determined according to the method described above. Furthermore, the ratio (Ib / Ia) of the peak intensity Ib of the second peak, which has a peak top in the range of 25 nm to 30 nm, to the peak intensity Ia of the first peak, which has a peak top in the range of 8 nm to 12 nm, was determined for the first electrolytic manganese dioxide. Furthermore, according to the method described above, it was confirmed that the first electrolytic manganese dioxide had a β-type crystal structure.

[0066] First electrolytic manganese dioxide 91.62 parts by mass (2.6 g) and LiBO as a boron compound ２ A dry mixture was obtained by dry-mixing 1.38 parts by mass (0.30 parts by mass in terms of boron element) of ammonium hydroxide and 5 parts by mass of graphite as a conductive additive. Next, an aqueous dispersion containing 2 parts by mass of polytetrafluoroethylene (PTFE) was added to the obtained dry mixture, followed by wet-mixing to obtain a wet mixture. The wet mixture was then dried to obtain a positive electrode mixture. This positive electrode mixture was tableted into a cylindrical shape with a diameter of 18 mm and a thickness of 3.3 mm to produce a positive electrode. The cylindrical positive electrode pellets were dried at 250 ° C for 8 hours.

[0067] (2) Negative electrode A negative electrode was prepared by punching a lithium metal foil having a thickness of 0.9 mm into a circle having a diameter of 22 mm. The negative electrode area S was 380 mm ２ As described above, since the mass W of the first electrolytic manganese dioxide contained in the positive electrode is 2.6 g, in Example 1, S / W was 146 mm ２ / g.

[0068] (3) Electrolyte: Propylene carbonate and 1,2-dimethoxyethane were mixed in a volume ratio of 2:1 to obtain a mixed non-aqueous solvent, and then lithium perchlorate (LiClO) was added as a solute to the mixed non-aqueous solvent. ４ ) was dissolved at a concentration of 1.0 mol / L to obtain an electrolyte solution.

[0069] (4) Battery Case A battery case having a bottom plate diameter of 24 mm and a side wall height of 4.9 mm was fabricated by drawing SUS430 (thickness 250 μm) having a 3 μm thick nickel plating layer on its surface.

[0070] (5) Sealing Plate A sealing plate with a top diameter of 22 mm was fabricated by pressing SUS430 (thickness: 250 μm) having a 3 μm-thick nickel-plated layer on its surface. As shown in FIG. 1 , the sealing plate had a top plate and a peripheral edge extending from the periphery of the top plate to the inside of the side wall of the case.

[0071] (6) Assembly of a Coin-Type Lithium Primary Battery A polypropylene gasket was placed on the sealing plate. A negative electrode was attached to the inside of the top plate of the sealing plate. Next, one side of a 300 μm-thick polypropylene nonwoven fabric (separator) was placed on the negative electrode. Next, a positive electrode was placed on the other side of the polypropylene nonwoven fabric. Next, an electrolyte was injected into the sealing plate. A sealant consisting of blown asphalt and mineral oil was applied to the inside of the sides of the battery case in advance, and the battery case was then placed on the sealing plate. The end of the side wall of the case was then bent inward. This bending allowed the end of the side wall to be crimped to the peripheral edge of the sealing plate via the gasket. This resulted in the production of a coin-type lithium primary battery according to Example 1.

[0072] [Example 2] A coin-type lithium primary battery according to Example 2 was obtained in the same manner as in Example 1, except that second electrolytic manganese dioxide having a β-type crystal structure (hereinafter simply referred to as second electrolytic manganese dioxide) was used as the positive electrode active material. The second electrolytic manganese dioxide was heated in a temperature-raising heating step, and the amount of water vapor during the firing step was 5 g / m ３ The second electrolytic manganese dioxide was obtained in the same manner as the first electrolytic manganese dioxide, except that air was supplied so that the cumulative pore volume V ｐ The solubility (mL / g) of the second electrolytic manganese dioxide was determined. The ratio of the peak intensity Ib to the peak intensity Ia (Ib / Ia) was also determined. Furthermore, it was confirmed that the second electrolytic manganese dioxide had a β-type crystal structure according to the method described above.

[0073] Example 3 A coin-type lithium primary battery according to Example 3 was obtained in the same manner as in Example 1, except that third electrolytic manganese dioxide having a β-type crystal structure (hereinafter simply referred to as third electrolytic manganese dioxide) was used as the positive electrode active material. The third electrolytic manganese dioxide was heated in a temperature-raising heating step, and the amount of water vapor during the firing step was 25 g / m ３ The third electrolytic manganese dioxide was obtained in the same manner as the first electrolytic manganese dioxide, except that air was supplied so that the cumulative pore volume V ｐ The solubility (mL / g) of the electrolytic manganese dioxide was determined. The ratio of the peak intensity Ib to the peak intensity Ia (Ib / Ia) was also determined. Furthermore, it was confirmed that the third electrolytic manganese dioxide had a β-type crystal structure according to the method described above.

[0074] Example 4 A coin-type lithium primary battery according to Example 4 was obtained in the same manner as in Example 1, except that a fourth electrolytic manganese dioxide having a β-type crystal structure (hereinafter simply referred to as fourth electrolytic manganese dioxide) was used as the positive electrode active material. The fourth electrolytic manganese dioxide was heated in a temperature-raising heating step, and the amount of water vapor during the firing step was 0 g / m ３ The fourth electrolytic manganese dioxide was obtained in the same manner as the first electrolytic manganese dioxide, except that air was supplied so that the cumulative pore volume V ｐThe solubility (mL / g) of the quaternary electrolytic manganese dioxide was determined. The ratio of the peak intensity Ib to the peak intensity Ia (Ib / Ia) was also determined. Furthermore, according to the method described above, it was confirmed that the quaternary electrolytic manganese dioxide had a β-type crystal structure.

[0075] Example 5 A coin-type lithium primary battery according to Example 5 was obtained in the same manner as in Example 1, except that a fifth electrolytic manganese dioxide having a β-type crystal structure (hereinafter simply referred to as fifth electrolytic manganese dioxide) was used as the positive electrode active material. The fifth electrolytic manganese dioxide was heated in a temperature-raising heating step, and the amount of water vapor during the firing step was 35 g / m ３ The fifth electrolytic manganese dioxide was obtained in the same manner as the first electrolytic manganese dioxide, except that air was supplied so that the cumulative pore volume V ｐ The solubility (mL / g) of the 5th electrolytic manganese dioxide was determined. The ratio of the peak intensity Ib to the peak intensity Ia (Ib / Ia) was also determined. Furthermore, according to the method described above, it was confirmed that the 5th electrolytic manganese dioxide had a β-type crystal structure.

[0076] Example 6 A coin-shaped lithium primary battery according to Example 6 was obtained in the same manner as in Example 1, except that sixth electrolytic manganese dioxide having a β-type crystal structure (hereinafter simply referred to as sixth electrolytic manganese dioxide) was used as the positive electrode active material. The sixth electrolytic manganese dioxide was obtained in the same manner as the first electrolytic manganese dioxide, except that the temperature inside the furnace was set to 400°C in the temperature-raising heating step and the firing step. The cumulative pore volume V ｐ The solubility (mL / g) of the 6th electrolytic manganese dioxide was determined. The ratio of the peak intensity Ib to the peak intensity Ia (Ib / Ia) was also determined. Furthermore, according to the method described above, it was confirmed that the 6th electrolytic manganese dioxide had a β-type crystal structure.

[0077] Example 7 A coin-type lithium primary battery according to Example 7 was obtained in the same manner as in Example 1, except that the amount of first electrolytic manganese dioxide in the positive electrode was 0.9 g (91.62 parts by mass), the diameter of the positive electrode pellet was 15 mm and the thickness was 1.9 mm, a circle with a diameter of 17.8 mm was punched out of a 0.6 mm thick lithium metal foil to prepare a negative electrode, a battery case with a bottom plate diameter of 20 mm and a side wall height of 3.1 mm was used, and a sealing plate with a top plate diameter of 18 mm was used. ２ / g.

[0078] Example 8 A coin-type lithium primary battery according to Example 8 was obtained in the same manner as in Example 7, except that the amount of first electrolytic manganese dioxide in the positive electrode was 0.7 g (91.62 parts by mass), the diameter of the positive electrode pellet was 14 mm, a battery case with a bottom plate diameter of 20 mm and a side wall height of 3.1 mm was used, and a sealing plate with a top plate diameter of 18 mm was used. ２ / g.

[0079] Example 9 A coin-type lithium primary battery according to Example 9 was obtained in the same manner as in Example 1, except that the amount of first electrolytic manganese dioxide in the positive electrode was 10.0 g (91.62 parts by mass), the diameter of the positive electrode pellet was 24 mm, the thickness was 5.3 mm, a circle of 27.6 mm in diameter was punched out of a 1.7 mm thick lithium metal foil to prepare a negative electrode, a battery case having a bottom plate diameter of 36 mm and a side wall height of 7.6 mm was used, and a sealing plate having a top plate diameter of 32 mm was used. ２ / g.

[0080] Example 10 A coin-type lithium primary battery according to Example 10 was obtained in the same manner as in Example 1, except that the positive electrode contained 4.5 g of first electrolytic manganese dioxide, the positive electrode pellet had a diameter of 18 mm and a thickness of 5.3 mm, the negative electrode was prepared by punching out a 1.4 mm thick lithium metal foil into a circle with a diameter of 22 mm, and a battery case was used in which the diameter of the bottom plate was 24 mm and the height of the side wall was 7.6 mm. ２ / g.

[0081] Example 11: LiBO as a boron compound in the positive electrode ２ A coin-type lithium primary battery according to Example 11 was obtained in the same manner as in Example 1, except that the amount of the cation exchange material was changed to 0.46 parts by mass (0.10 parts by mass in terms of boron element).

[0082] Example 12: LiBO as a boron compound in the positive electrode ２ A coin-type lithium primary battery according to Example 12 was obtained in the same manner as in Example 1, except that the amount of the cation exchange material was changed to 3.68 parts by mass (0.81 parts by mass in terms of boron element).

[0083] Example 13: LiBO as a boron compound in the positive electrode ２ A coin-type lithium primary battery according to Example 13 was obtained in the same manner as in Example 1, except that the amount of the cation exchange material was changed to 5.52 parts by mass (1.21 parts by mass in terms of boron element).

[0084] Example 14: LiBO as a boron compound in the positive electrode ２ A coin-type lithium primary battery according to Example 14 was obtained in the same manner as in Example 1, except that the amount of the cation exchange material was changed to 0.23 parts by mass (0.05 parts by mass in terms of boron element).

[0085] [Example 15] B as a boron compound in the positive electrode ２ O ３ A coin-type lithium primary battery according to Example 15 was obtained in the same manner as in Example 1, except that the content of the compound was 0.96 parts by mass (0.30 parts by mass in terms of boron element).

[0086] [Example 16] H as a boron compound in the positive electrode ３ BO ３ A coin-type lithium primary battery according to Example 16 was obtained in the same manner as in Example 1, except that the content of the compound was 1.72 parts by mass (0.30 parts by mass in terms of boron element).

[0087] [Example 17] Li as a boron compound in the positive electrode ２ B ４ O ７A coin-type lithium primary battery according to Example 17 was obtained in the same manner as in Example 1, except that the content of the compound was 1.17 parts by mass (0.30 parts by mass in terms of boron element).

[0088] [Example 18] Li as a boron compound in the positive electrode ３ BO ３ A coin-type lithium primary battery according to Example 18 was obtained in the same manner as in Example 1, except that the content of the compound was 1.91 parts by mass (0.30 parts by mass in terms of boron element).

[0089] Example 19 A coin-type lithium primary battery according to Example 19 was obtained in the same manner as in Example 1, except that PVDF was used as the binder.

[0090] Example 20 A coin-type lithium primary battery according to Example 20 was obtained in the same manner as in Example 1, except that FEP was used as the binder.

[0091] Comparative Example 1 A coin-type lithium primary battery according to Comparative Example 1 was obtained in the same manner as in Example 1, except that seventh electrolytic manganese dioxide having a β-type crystal structure (hereinafter simply referred to as seventh electrolytic manganese dioxide) was used as the positive electrode active material. The seventh electrolytic manganese dioxide was heated in a temperature-raising heating step, and the amount of water vapor during the firing step was 0 g / m ３ The seventh electrolytic manganese dioxide was obtained in the same manner as the first electrolytic manganese dioxide, except that air was supplied so that the cumulative pore volume V ｐ The solubility (mL / g) of the electrolytic manganese dioxide was determined. The ratio of the peak intensity Ib to the peak intensity Ia (Ib / Ia) was also determined. Furthermore, it was confirmed that the seventh electrolytic manganese dioxide had a β-type crystal structure according to the method described above.

[0092] Comparative Example 2 A coin-type lithium primary battery according to Comparative Example 2 was obtained in the same manner as in Example 1, except that eighth electrolytic manganese dioxide having a β-type crystal structure (hereinafter simply referred to as eighth electrolytic manganese dioxide) was used as the positive electrode active material. The eighth electrolytic manganese dioxide was obtained in the same manner as the first electrolytic manganese dioxide, except that air was not supplied during the temperature-raising heating step. The cumulative pore volume V ｐ The solubility (mL / g) of the electrolytic manganese dioxide was determined. The ratio of the peak intensity Ib to the peak intensity Ia (Ib / Ia) was also determined. Furthermore, it was confirmed that the eighth electrolytic manganese dioxide had a β-type crystal structure according to the method described above.

[0093] <Evaluation> Discharge voltage (CCV) at 0% depth of discharge (DOD 0%) A pulse discharge test was carried out on the coin-type lithium batteries according to each example in an environment of 20±3° C. In the pulse discharge test, a discharge current of 2.63 mA / cm was applied every minute. ２ The batteries were discharged at 1 mA for 50 milliseconds, and the discharge voltage (CCV) of the batteries was measured. The minimum discharge voltage from the start of the pulse discharge test until one hour had elapsed was determined as the discharge voltage (CCV) at a depth of discharge of 0% (DOD 0%). The results are shown in Table 1 below as CCV0. Discharge voltage (CCV) at a depth of discharge of 60% (DOD 60%) The coin-type lithium primary batteries according to each example were discharged at 1 mA to a depth of discharge (DOD) of 60% in an environment of 20±3°C. Then, a pulse discharge test was conducted in an environment of 20±3°C. In the pulse discharge test, a current of 2.63 mA / cm was applied every minute. ２ The battery was discharged at 1000 kJ / s for 50 milliseconds, and the discharge voltage (CCV) of the battery was measured. The minimum discharge voltage from the start of the pulse discharge test until one hour had elapsed was calculated as the discharge voltage (CCV) at a depth of discharge of 60% (DOD 60%). The result is shown in Table 1 below as CCV1. The CCV maintenance rate (CCV1 / CCV0 x 100) was also calculated and shown in Table 1 below.

[0094]

[0095] From Table 1, it can be seen that the coin-type lithium primary batteries according to Examples 1 to 21 all exhibit a high CCV0 of 2.00 V or more, and also exhibit a high CCV1 of 1.80 V or more. In contrast, the coin-type lithium primary batteries according to Comparative Examples 1 and 2 all exhibit a high CCV0 of 2.00 V or more, but a low CCV1 of less than 1.80 V. From this, it can be seen that, when the positive electrode contains manganese dioxide and a boron compound, and the manganese dioxide has a β-type crystal structure and the cumulative pore volume V of pores having a diameter of 0.5 nm to 50 nm obtained from the pore volume distribution measured by mercury intrusion porosimetry is ｐ It can be seen that by using a material having the property that the capacitance is 0.015 mL / g or more and 0.035 mL / g or less, a lithium primary battery that can exhibit high output characteristics from the initial stage to the final stage of discharge can be obtained.

[0096] The lithium primary battery according to the present disclosure can be used in applications that require high output characteristics from the beginning to the end of discharge.

[0097] 3: Case 3a: Bottom plate portion, 3b: Side wall portion 4: Positive electrode 5: Negative electrode 6: Separator 7: Gasket 8: Sealing plate 8a: Top plate portion, 8b: Peripheral portion 9: Bent portion 10: Coin-type lithium primary battery

Claims

1. A primary lithium battery comprising a positive electrode, a negative electrode facing the positive electrode, a separator disposed between the positive electrode and the negative electrode, and an electrolytic solution, wherein the positive electrode contains manganese dioxide and a boron compound, the manganese dioxide contains a β-type crystal structure, and the integrated pore volume V of pores having a diameter of 0.5 nm or more and 50 nm or less obtained from the pore volume distribution measured by the mercury intrusion method ｐ is 0.015 mL / g or more and 0.035 mL / g or less.

2. The integrated pore volume V ｐ is 0.020 mL / g or more and 0.030 mL / g or less, and the primary lithium battery according to claim 1.

3. The manganese dioxide has a first peak showing a peak top in the range of 8 nm or more and 12 nm or less and a second peak showing a peak top in the range of 25 nm or more and 30 nm or less in the pore volume distribution, and the ratio (Ib / Ia) of the peak intensity Ib of the second peak to the peak intensity Ia of the first peak is 10 or more. The primary lithium battery according to claim 1 or 2.

4. When the area of the surface of the negative electrode facing the positive electrode is S (mm ２ ), and the mass of the manganese dioxide contained in the positive electrode is W (g), the ratio of S to W (S / W (mm ２ / g)) is 80 or more and 300 or less. The primary lithium battery according to claim 1 or 2.

5. The boron compound is a compound having at least one of a B—O bond and a B═O bond. The primary lithium battery according to claim 1 or 2.

6. The boron compound is at least one selected from the group consisting of boric acid, boron oxide, and lithium borate. The primary lithium battery according to claim 5.

7. The boron compound is H ３ BO ３ , B ２ O ３ , LiBO ２ , Li ２ B ４ O ７ , and at least one selected from the group consisting of Li ３ BO ３ ; the lithium primary battery according to claim 6.

8. The primary lithium battery according to claim 1 or 2, containing 0.1 part by mass or more and 0.8 part by mass or less of the boron compound in terms of boron element with respect to 100 parts by mass of the manganese dioxide.

9. The positive electrode further contains a binder, and the binder contains a fibrous fluororesin. The primary lithium battery according to claim 1 or 2.

10. The binder contains polytetrafluoroethylene as the fibrous fluororesin. The primary lithium battery according to claim 9.

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