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

Abstract

The primary lithium battery includes a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode contains a positive electrode mixture including LixMnO2 (0 ≤ x ≤ 0.05). The negative electrode includes at least one of metallic lithium and a lithium alloy. The non-aqueous electrolyte contains a cyclic imide component and a boric acid organosilyl ester component. The concentration of the cyclic imide component in the non-aqueous electrolyte is 1 mass% or less, the concentration of the boric acid organosilyl ester component in the non-aqueous electrolyte is 5.5 mass% or less, and the mass ratio of the cyclic imide component contained in the non-aqueous electrolyte to the boric acid organosilyl ester component is 0.02 or more and 10 or less.

Description

Technical Field

[0001] The present disclosure relates to a non-aqueous electrolyte used in a primary lithium battery and a primary lithium battery. Background Art

[0002] Primary lithium batteries have a high energy density and low self-discharge, and are therefore used in a large number of electronic devices. A primary lithium battery includes a negative electrode containing metallic lithium, a positive electrode, and a non-aqueous electrolyte. In the positive electrode, graphite fluoride, manganese dioxide, thionyl chloride, or the like is used as an active material.

[0003] In a primary lithium battery, if discharging occurs, the internal resistance increases and the discharge capacity sometimes decreases. From the viewpoint of suppressing such an increase in internal resistance, a method of using an additive in the electrolyte has been proposed.

[0004] For example, from the viewpoint of suppressing an increase in internal resistance of a primary battery or a secondary battery and improving the charge / discharge cycle characteristics of a secondary battery, Patent Document 1 proposes a method of using a non-aqueous electrolyte containing an additive such as phthalimide.

[0005] Patent Document 2 proposes a method of using a non-aqueous electrolyte for a non-aqueous electrolyte primary battery, the non-aqueous electrolyte containing a phosphoric acid compound or a boric acid compound having a silyl group having an alkyl group, an alkenyl group, or an aryl group or the like in the molecule at a content of 8% by mass or less.

[0006] Patent Document 3 proposes an additive composition for an electrolyte for a non-aqueous electrical storage device, which contains the following additive: a compound (A) in which at least one of the acidic protons of a protonic acid having a phosphorus atom or a boron atom is substituted with a silyl group having three hydrocarbon groups.

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: International Publication No. 01 / 41247

[0010] Patent Document 2: International Publication No. 2017 / 169684

[0011] Patent Document 3: Japanese Patent Application Laid-Open No. 2016-189327 Summary of the Invention

[0012] A primary lithium battery may sometimes be stored for a long time, and high discharge performance is also required after storage. If a non-aqueous electrolyte containing phthalimide is used for a primary lithium battery, the discharge capacity at low temperature after storing the battery sometimes decreases.

[0013] A first aspect of the present disclosure relates to a primary lithium battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte.

[0014] The foregoing positive electrode contains a positive electrode mixture containing LixMnO2 (0 ≤ x ≤ 0.05).

[0015] The foregoing negative electrode contains at least one of metallic lithium and a lithium alloy.

[0016] The foregoing non-aqueous electrolyte contains a cyclic imide component and a boric acid organic silyl ester component.

[0017] The concentration of the foregoing cyclic imide component in the foregoing non-aqueous electrolyte is 1% by mass or less.

[0018] The concentration of the foregoing boric acid organic silyl ester component in the foregoing non-aqueous electrolyte is 5.5% by mass or less.

[0019] The mass ratio of the foregoing cyclic imide component contained in the foregoing non-aqueous electrolyte to the foregoing boric acid organic silyl ester component is 0.02 or more and 10 or less.

[0020] A second aspect of the present disclosure relates to a primary lithium battery, which includes: a positive electrode, a negative electrode, and a non-aqueous electrolyte.

[0021] The foregoing positive electrode contains a positive electrode mixture containing LixMnO2 (0 ≤ x ≤ 0.05).

[0022] The foregoing negative electrode contains at least one of metallic lithium and a lithium alloy.

[0023] The foregoing non-aqueous electrolyte contains a cyclic imide component and a boric acid organic silyl ester component.

[0024] The concentration of the foregoing cyclic imide component in the foregoing non-aqueous electrolyte is 0.1% by mass or more and 1% by mass or less.

[0025] The concentration of the foregoing boric acid organic silyl ester component in the foregoing non-aqueous electrolyte is 0.1% by mass or more and 5.5% by mass or less.

[0026] A third aspect of the present disclosure relates to a non-aqueous electrolyte for a primary lithium battery, which is a non-aqueous electrolyte for a primary lithium battery, and the primary lithium battery includes: a positive electrode containing a positive electrode mixture containing LixMnO2 (0 ≤ x ≤ 0.05); a negative electrode containing at least one of metallic lithium and a lithium alloy; and a non-aqueous electrolyte.

[0027] The foregoing non-aqueous electrolyte contains a cyclic imide component and a boric acid organic silyl ester component.

[0028] The concentration of the foregoing cyclic imide component in the foregoing non-aqueous electrolyte is 0.1% by mass or more and 1% by mass or less.

[0029] The concentration of the boric acid organic silyl ester component in the aforementioned non-aqueous electrolyte is 0.1% by mass or more and 5.5% by mass or less.

[0030] It is possible to suppress a decrease in the discharge capacity at low temperatures after storing the primary lithium battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 FIG. 9 is a front view showing a cross section of a part of a primary lithium battery according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0032] It has been found that in a primary lithium battery including a positive electrode containing LixMnO2 (0 ≤ x ≤ 0.05) and a negative electrode including at least one of metallic lithium and a lithium alloy, when a non-aqueous electrolyte containing a cyclic imide component is used, the discharge capacity after storing the battery may be significantly reduced compared to the case where a non-aqueous electrolyte not containing a cyclic imide component is used. This decrease in the discharge capacity is likely to be prominent when discharging at low temperatures. The decrease in the discharge capacity is particularly prominent when the battery is stored at high temperatures and further stored at high temperatures for a long time. Recently, with the expansion of the uses of primary lithium batteries, for example, when the battery is stored for a long period (for example, a long period of 10 years or more or 20 years or more), or when discharging at low temperatures after storage, excellent discharge performance is sometimes required.

[0033] In view of the above, the primary lithium battery of the present disclosure includes: a positive electrode containing a positive electrode mixture containing LixMnO2 (0 ≤ x ≤ 0.05); a negative electrode including at least one of metallic lithium and a lithium alloy; and a non-aqueous electrolyte. The non-aqueous electrolyte contains a cyclic imide component and a boric acid organic silyl ester component. In such a primary lithium battery, the non-aqueous electrolyte satisfies at least one of the following conditions (a) and (b).

[0034] (a) The concentration of the cyclic imide component in the non-aqueous electrolyte is 1% by mass or less, the concentration of the boric acid organic silyl ester component in the non-aqueous electrolyte is 5.5% by mass or less, and the mass ratio of the cyclic imide component contained in the non-aqueous electrolyte to the boric acid organic silyl ester component is 0.02 or more and 10 or less.

[0035] (b) The concentration of the cyclic imide component in the non-aqueous electrolyte is 0.1% by mass or more and 1% by mass or less, and the concentration of the boric acid organic silyl ester component in the non-aqueous electrolyte is 0.1% by mass or more and 5.5% by mass or less.

[0036] According to the present disclosure, by providing the lithium primary battery with the above-mentioned non-aqueous electrolyte, even though the non-aqueous electrolyte contains a cyclic imide component, it is possible to suppress the decrease in discharge capacity when the lithium primary battery is discharged at low temperature after being stored. In particular, it is possible to suppress the decrease in discharge capacity when the lithium primary battery is discharged at low temperature after being stored at high temperature for a long time. In the present disclosure, it is believed that this effect is obtained based on the following reasons.

[0037] In a lithium primary battery having the above-mentioned positive electrode, the above-mentioned negative electrode and a non-aqueous electrolyte, when the non-aqueous electrolyte contains a cyclic imide component but does not contain a boric acid organic silyl ester component, the capacity after storage is greatly reduced compared to the case where both the cyclic imide component and the boric acid organic silyl ester component are not contained. It is believed that this is because the cyclic imide component is oxidized on the surface of the positive electrode, and a film with low lithium ion conductivity originating from the cyclic imide component is formed on the surface of the positive electrode, which hinders the migration of lithium ions at the interface between the positive electrode and the electrolyte. The influence of the obstruction of the migration of lithium ions is more obvious in the discharge at low temperature. In other words, at low temperatures, the migration of lithium ions at the interface between the positive electrode and the electrolyte is easy to control the speed. Therefore, the discharge capacity at low temperatures is more significantly reduced. In addition, with the oxidation of the cyclic imide component, the self-discharge of the positive electrode proceeds, so the discharge capacity after storage is reduced. In particular, when lithium primary batteries are stored at high temperatures for a long time, the growth of the coating on the positive electrode and the self-discharge of the positive electrode are promoted, so that the discharge capacity decreases significantly when the battery is discharged at low temperatures after storage.

[0038] The capacity reduction after storage was basically unchanged when the non-aqueous electrolyte contained a boric acid organosilyl ester component but did not contain a cyclic imide component, and when the non-aqueous electrolyte did not contain both a cyclic imide component and a boric acid organosilyl ester component. It is therefore believed that the boric acid organosilyl ester component alone has basically no effect on the lithium ion conductivity of the film on the positive electrode.

[0039] In contrast, in the primary lithium battery of the present disclosure, compared with the case where neither the cyclic imide component nor the boric acid organosilyl ester component is contained, a decrease in the discharge capacity at low temperature after storage can be significantly suppressed. In the primary lithium battery of the present disclosure, compared with what is expected in the case where the non-aqueous electrolyte contains either the cyclic imide component or the boric acid organosilyl ester component, a decrease in the capacity at low temperature after storage is greatly suppressed. Therefore, when the non-aqueous electrolyte satisfies at least one of the conditions (a) and (b) above, it can be said that a synergistic effect of the cyclic imide component and the boric acid organosilyl ester component is obtained in suppressing the decrease in the discharge capacity at low temperature after storage. Thus, in the primary lithium battery of the present disclosure, the factor by which the decrease in the discharge capacity at low temperature after storage is significantly suppressed is not necessarily clear, but it can be considered as follows. It is considered that when the cyclic imide component is decomposed on the surface of the positive electrode to form a coating film, the boric acid organosilyl ester component is also incorporated into the decomposition reaction to form a coating film containing components derived from both the cyclic imide component and the boric acid organosilyl ester component. When forming such a coating film, different from the case of forming a coating film formed only of components derived from the cyclic imide component, a coating film with high lithium ion conductivity is formed. Due to the effect of this coating film, a high discharge capacity can be maintained even at low temperatures where the migration of lithium ions at the interface between the positive electrode and the electrolyte is usually easily rate-limiting. In addition, the coating film containing components derived from both the cyclic imide component and the boric acid organosilyl ester component is dense and has low electron conductivity. Therefore, oxidation of the cyclic imide component becomes difficult to occur on the surface of the positive electrode at the initial stage when assembling the battery and thereafter, and the progress of reduction of the positive electrode is alleviated. Therefore, self-discharge during the storage of the primary lithium battery is reduced. Thus, it is considered that by using an electrolyte containing both the cyclic imide component and the boric acid organosilyl ester component, a decrease in the discharge capacity after storing the battery is suppressed. This effect is extremely obvious at low temperatures.

[0040] In the present disclosure, there is also provided a non-aqueous electrolyte for use in a primary lithium battery, the primary lithium battery comprising: a positive electrode containing a positive electrode mixture containing LixMnO2 (0 ≤ x ≤ 0.05); a negative electrode containing at least one of metallic lithium and a lithium alloy; and a non-aqueous electrolyte. Here, the non-aqueous electrolyte contains a cyclic imide component and a boric acid organosilyl ester component. The non-aqueous electrolyte satisfies the condition of (b) above. In addition, in the present disclosure, there is also provided the use of such a non-aqueous electrolyte in a primary lithium battery, the primary lithium battery comprising: a positive electrode containing a positive electrode mixture containing LixMnO2 (0 ≤ x ≤ 0.05); a negative electrode containing at least one of metallic lithium and a lithium alloy; and a non-aqueous electrolyte.

[0041] Hereinafter, the primary lithium battery, non-aqueous electrolyte, and manufacturing method of the primary lithium battery of the present disclosure will be described in more detail.

[0042] Primary lithium battery

[0043] (Positive electrode)

[0044] The positive electrode contains a positive electrode mixture. The positive electrode mixture contains a positive electrode active material. As the positive electrode active material contained in the positive electrode, manganese dioxide can be cited. The positive electrode containing manganese dioxide exhibits a higher voltage and excellent pulse discharge characteristics. Manganese dioxide can be in a mixed crystal state containing various crystal states. The positive electrode may also contain manganese oxides other than manganese dioxide. As manganese oxides other than manganese dioxide, MnO, Mn3O4, Mn2O3, Mn2O7, etc. can be cited. The main component of the manganese oxide contained in the positive electrode is preferably manganese dioxide.

[0045] A part of the manganese dioxide contained in the positive electrode can be doped with lithium. As long as the doping amount of lithium is small, high capacity can be ensured. Manganese dioxide doped with manganese dioxide and a small amount of lithium can be represented by LixMnO2 (0 ≤ x ≤ 0.05). It should be noted that the average composition of the entire manganese oxide contained in the positive electrode only needs to be LixMnO2 (0 ≤ x ≤ 0.05). It should be noted that the ratio x of Li only needs to be 0.05 or less in the initial state of discharge of the primary lithium battery. The ratio x of Li usually increases as the discharge of the primary lithium battery proceeds. The oxidation number of manganese contained in manganese dioxide is theoretically 4. However, since the positive electrode contains other manganese oxides or manganese dioxide is doped with lithium, the oxidation number of manganese sometimes slightly increases or decreases from 4. Therefore, in LixMnO2, the average oxidation number of manganese is allowed to have some increase or decrease from 4.

[0046] In addition to LixMnO2, the positive electrode may also contain other positive electrode active materials used in the primary lithium battery. As other positive electrode active materials, graphite fluoride, etc. can be cited. From the viewpoint of easily exerting the effects brought about by using a non-aqueous electrolyte that satisfies the above conditions (a) or (b), the proportion of LixMnO2 in the total positive electrode active material is preferably 90% by mass or more.

[0047] As manganese dioxide, electrolytic manganese dioxide is preferably used. Electrolytic manganese dioxide that has been subjected to at least any one of neutralization treatment, cleaning treatment, and firing treatment as required can also be used.

[0048] Electrolytic manganese dioxide is usually obtained by electrolysis of an aqueous manganese sulfate solution. Therefore, sulfate ions are inevitably contained in electrolytic manganese dioxide. Sulfur atoms are inevitably contained in the positive electrode mixture made using this electrolytic manganese dioxide. In a primary lithium battery, it is considered that sulfate ions interact with unstable Mn generated by the insertion of lithium into Li x MnO2, resulting in the disproportionation of Mn 3+ interact with each other, and the disproportionation of Mn 3+ caused by the disproportionation of Mn2+ generation is suppressed. Thus, it is considered that the dissolution of Mn 2+ into the non-aqueous electrolyte and the precipitation of Mn in the negative electrode are suppressed. In the primary lithium battery of the present disclosure, an electrolytic solution containing a cyclic imide component and a boric acid organosilyl ester component is used. Therefore, it is considered that if the positive electrode mixture contains sulfate ions, the sulfate ions react with the cyclic imide component and the boric acid organosilyl ester component to form a film containing sulfate ions. By using this film, the dissolution inhibition effect of Mn 2+ can be further improved.

[0049] 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 with respect to 100 parts by mass of manganese atoms contained in the positive electrode mixture. When the sulfur atoms are in this range, a higher effect can be ensured in the dissolution inhibition of Mn 2+ , and therefore, high reliability of the primary lithium battery can be ensured while ensuring high capacity. The ratio of sulfur atoms contained in the positive electrode mixture can be adjusted by adjusting the conditions of the cleaning treatment and the neutralization treatment. As the cleaning treatment, for example, at least one of a water washing treatment and a cleaning treatment using an acid can be mentioned. As the neutralizing agent used in the neutralization treatment, for example, an inorganic base such as ammonia or a hydroxide is used.

[0050] On the other hand, in a secondary lithium battery, a part of the sulfate ions is decomposed during the charging process. Therefore, even if it is assumed that the positive electrode mixture contains a sulfate salt with sulfur atoms in the above range, it is difficult to sufficiently ensure the above effects.

[0051] If the conditions during electrolytic synthesis are adjusted, the crystallinity of manganese dioxide can be improved, and the specific surface area of electrolytic manganese dioxide can be reduced. The BET specific surface area of LixMnO2 can be 20 m 2 / g or more and 50 m 2 / g or less. When the BET specific surface area of LixMnO2 is in this range, in a primary lithium battery, a voltage drop during pulse discharge can be suppressed, a higher self-discharge suppression effect can be obtained, and gas generation is suppressed. In addition, a positive electrode mixture layer can be easily formed.

[0052] The BET specific surface area of LixMnO2 can be measured by a known method. For example, it can be measured based on the BET method using a specific surface area measuring device (for example, manufactured by Mountech Co., Ltd.). For example, LixMnO2 separated from the positive electrode taken out from the battery can be used as the measurement sample.

[0053] The median value of the particle size of LixMnO2 may be 10 μm or more and 40 μm or less. When the median value of the particle size is in this range, in a primary lithium battery, the effect of suppressing self-discharge during discharge is further improved, gas generation can be suppressed, and voltage drop during pulse discharge can be suppressed.

[0054] The median value of the particle size of LixMnO2 is, for example, the median value of the particle size distribution determined by the quantitative laser diffraction / scattering method (qLD method). For example, LixMnO2 separated from the positive electrode taken out from the battery can be used as the measurement sample. For example, SALD-7500nano manufactured by Shimadzu Corporation can be used in the measurement.

[0055] The positive electrode mixture may further contain a binder in addition to the positive electrode active material. The positive electrode mixture may also contain a conductive agent.

[0056] Examples of the binder include fluororesin, rubber particles, and acrylic resin.

[0057] Examples of the conductive agent include conductive carbon materials. Examples of the conductive carbon materials include natural graphite, artificial graphite, carbon black, and carbon fiber.

[0058] The positive electrode may further contain a positive electrode current collector for holding the positive electrode mixture. Examples of the material of the positive electrode current collector include stainless steel, aluminum, and titanium.

[0059] In the case of a coin-shaped battery, a ring-shaped positive electrode current collector with an L-shaped cross-section can be installed on the positive electrode mixture pellets to form the positive electrode, or the positive electrode can be composed only of the positive electrode mixture pellets. The positive electrode mixture pellets can be obtained, for example, by adding an appropriate amount of water to the positive electrode active material and the additive to prepare a wet positive electrode mixture, and then compression molding and drying the obtained positive electrode mixture.

[0060] In the case of a cylindrical battery, a positive electrode having a sheet-like positive electrode current collector and a positive electrode mixture layer held on the positive electrode current collector can be used. As the sheet-like positive electrode current collector, a perforated current collector is preferred. Examples of the perforated current collector include a porous metal mesh, a net, and a punched metal. The positive electrode mixture layer can be obtained, for example, by coating the above-mentioned wet positive electrode mixture on the surface of the sheet-like positive electrode current collector or filling it into the positive electrode current collector, and then pressing and drying it in the thickness direction.

[0061] The positive electrode preferably includes: the above-mentioned porous current collector, and a positive electrode mixture filled into the current collector. Among them, a current collector containing at least one material selected from the group consisting of SUS444, SUS430, and SUS316 is preferably used. By using such a current collector, in the primary lithium battery, side reactions with the above-mentioned non-aqueous electrolyte and corrosion of the current collector can be suppressed, and an increase in internal resistance and gas generation can be suppressed. In particular, when combining such a current collector with a non-aqueous electrolyte containing at least one of LiCF3SO3 and LiClO4, which are typically used in primary lithium batteries as lithium salts, side reactions between the current collector and the non-aqueous electrolyte can be more effectively suppressed. The thickness of the positive electrode is, for example, 300 μm or more and 900 μm or less. When using a positive electrode with such a thickness, the diffusibility of the non-aqueous electrolyte in the positive electrode mixture tends to decrease, and the reduction of the positive electrode accompanied by the oxidation of the solvent or cyclic imide component is suppressed. Therefore, self-discharge can be suppressed. It should be noted that in a primary lithium battery, the discharge usually occurs at a low rate over a long time. Therefore, an increase in resistance when the thickness of the positive electrode is in this range can be allowed.

[0062] (Negative electrode)

[0063] 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 can be used for the negative electrode.

[0064] Examples of the lithium alloy include Li-Al alloy, Li-Sn alloy, Li-Ni-Si alloy, Li-Pb alloy, etc. From the viewpoint of ensuring discharge capacity and stabilizing internal resistance, the content of metal elements other than lithium contained in the lithium alloy is preferably set to 0.05 to 15 mass%.

[0065] Metallic lithium, a lithium alloy, or a composite thereof can be formed into any shape and thickness according to the shape, size, standard performance, etc. of the primary lithium battery.

[0066] In the case of a coin-shaped battery, a ring-shaped metallic lithium, lithium alloy, or a composite thereof can be blanked into a circular plate shape for use as the negative electrode. In the case of a cylindrical battery, a sheet of metallic lithium, lithium alloy, or a composite thereof can be used as the negative electrode. The sheet is obtained, for example, by extrusion molding. More specifically, in a cylindrical battery, a foil of metallic lithium or a lithium alloy having a shape with a length direction and a width direction is used.

[0067] In the case of a cylindrical battery, a long strip having a resin substrate and an adhesive layer can be adhered along the length 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 the strip can be set, for example, to be 0.5 mm or more and 3 mm or less. The strip has the function of preventing poor current collection due to foil breakage of the negative electrode when the lithium component of the negative electrode is consumed by reaction at the end of discharge. If poor current collection occurs, it will lead to a decrease in battery capacity. However, the adhesive force of the strip decreases due to the electrolyte during long-term storage. When using an electrolyte containing a cyclic imide component and a boric acid organosilyl ester component, the decrease in the adhesive force can be suppressed, and the occurrence of foil breakage of the negative electrode and poor current collection can be more effectively prevented.

[0068] As the material of the resin substrate, for example, fluororesin, polyimide, polyphenylene sulfide, polyethersulfone, polyolefins such as polyethylene and polypropylene, polyethylene terephthalate, etc. can be used. Among them, polyolefins are preferred, and polypropylene is more preferred.

[0069] 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, as the rubber component, synthetic rubber, natural rubber, etc. can be used. As the synthetic rubber, butyl rubber, butadiene rubber, styrene-butadiene rubber, isoprene rubber, chloroprene, polyisobutylene, acrylonitrile-butadiene rubber, styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butadiene block copolymer, etc. can be cited. As the silicone component, an organic compound having a polysiloxane structure, a silicone-based polymer, etc. can be used. As the silicone-based polymer, peroxide-curable silicone, addition-reaction-type silicone, etc. can be cited. As the acrylic resin component, a polymer containing acrylic monomers such as acrylic acid, methacrylic acid, acrylate, and methacrylate can be used, and 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, 2-ethylhexyl methacrylate, etc. can be cited. It should be noted that the adhesive layer may also contain a crosslinking agent, a plasticizer, and a tackifier.

[0070] (Non-aqueous electrolyte)

[0071] The non-aqueous electrolyte contains, for example: a cyclic imide component and a boric acid organosilyl ester component; and a non-aqueous solvent for dissolving them. The non-aqueous electrolyte contains a lithium salt or lithium ions. The cyclic imide component can be a salt such as a lithium salt, and can generate cations such as lithium ions. It should be noted that the non-aqueous electrolyte may contain a lithium salt other than the cyclic imide component.

[0072] (Cyclic imide component)

[0073] As the cyclic imide component, cyclic diacylamines can be cited, for example. The cyclic imide component only needs to have a diacylamine ring (or also referred to as an imide ring). The imide ring can be condensed with other rings (also referred to as the second ring). The non-aqueous electrolyte can contain one kind of cyclic imide component or two or more kinds. The cyclic imide component can 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 can be contained in the form having a free NH group or in the form of a tertiary amine.

[0074] As the second ring, an aromatic ring, a saturated or unsaturated aliphatic ring, etc. can be cited. At least one heteroatom can be contained in the second ring. As the heteroatom, an oxygen atom, a sulfur atom, a nitrogen atom, etc. can be cited.

[0075] As the cyclic imide constituting the cyclic imide component, aliphatic dicarboximide and cyclic imide having a second ring can be cited, for example. As the aliphatic dicarboximide, succinimide etc. can be cited, for example. As the cyclic imide having a second ring, imides of aromatic or alicyclic dicarboxylic acids etc. can be cited. As the aromatic dicarboxylic acid or alicyclic dicarboxylic acid, those having carboxyl groups on two adjacent atoms constituting the ring can be cited, for example. As the cyclic imide having a second ring, phthalimide, a hydrogenated product of phthalimide can be cited, for example. As the hydrogenated product of phthalimide, cyclohex-3-ene-1,2-dicarboxamide, cyclohexane-1,2-dicarboxamide etc. can be cited.

[0076] The imide ring can be an N-substituted imide ring having a substituent on the nitrogen atom of the imide. As such a substituent, a hydroxyl group, an alkyl group, an alkoxy group, a halogen atom etc. can be cited. As the alkyl group, an alkyl group having 1 to 4 carbon atoms can be cited, for example, and it can also be a methyl group, an ethyl group etc. As the alkoxy group, an alkoxy group having 1 to 4 carbon atoms can be cited, for example, and it can also be a methoxy group, an ethoxy group etc. As the halogen atom, a chlorine atom, a fluorine atom etc. can be cited.

[0077] Among the cyclic imide components, phthalimide, N-substituted phthalimide etc. are more preferable. As the substituent on the nitrogen atom of the N-substituted phthalimide, it can be selected from the substituents exemplified for the N-substituted imide ring. It is further preferable to use a cyclic imide component containing at least phthalimide.

[0078] When the non-aqueous electrolyte satisfies the condition of the above (a), the mass ratio of the cyclic imide component contained in the non-aqueous electrolyte to the boric acid organosilyl ester component is 0.02 or more and 10 or less, more preferably 0.02 or more and 5 or less, and may be 0.02 or more and 2 or less, 0.02 or more and 1 or less, 0.02 or more and 0.7 or less, 0.08 or more and 0.7 or less, 0.02 or more and 0.5 or less, 0.08 or more and 0.5 or less, or 0.1 or more and 0.5 or less. By setting the mass ratio within this range, the formation of the oxide coating derived only from the cyclic imide component is suppressed, and the coating containing components derived from both the cyclic imide component and the boric acid organosilyl ester component becomes further likely to form on the positive electrode surface. As a result, the lithium ion conductivity of the coating is improved, and the effect of suppressing self-discharge during storage is enhanced, so that the capacity reduction at low temperature after storage of the primary lithium battery can be significantly suppressed.

[0079] The concentration of the cyclic imide component in the non-aqueous electrolyte is 1% by mass or less, and may be 0.8% by mass or less or 0.5% by mass or less. When the concentration of the cyclic imide component is within this range, the capacity reduction at low temperature after storing the primary lithium battery can be further suppressed. The concentration of the cyclic imide component in the non-aqueous electrolyte only needs to be above the detection limit, and may be 0.1% by mass or more.

[0080] During the storage or discharge of the primary lithium battery, the cyclic imide component is consumed by film formation or the like in the primary lithium battery, and the concentration of the cyclic imide component in the non-aqueous electrolyte changes. The concentration of the cyclic imide component in the non-aqueous electrolyte used in the assembly or manufacture of the primary lithium battery is preferably 0.1% by mass or more. In this case, it becomes easier to form a film containing components derived from both the cyclic imide component and the boric acid organosilyl ester component, and the capacity reduction at low temperature after storing the primary lithium battery can be effectively suppressed. The concentration of the cyclic imide component in the non-aqueous electrolyte used in the assembly or manufacture of the primary lithium battery is preferably set to 1% by mass or less, and may also be set to 0.8% by mass or less or 0.5% by mass or less. In this case, the effect of suppressing self-discharge during the storage of the primary lithium battery is further enhanced, so that the capacity reduction at low temperature after storage can be significantly suppressed.

[0081] When the non-aqueous electrolyte satisfies the condition of the above (b), the concentration of the cyclic imide component in the non-aqueous electrolyte only needs to be 0.1% by mass or more and 1% by mass or less, and may also be 0.1% by mass or more and 0.8% by mass or less or 0.1% by mass or more and 0.5% by mass or less. When the concentration of the cyclic imide component is within this range, the capacity reduction at low temperature after storing the primary lithium battery can be significantly suppressed.

[0082] In addition, the mass ratio of the cyclic imide component contained in the non-aqueous electrolyte to the boric acid organosilyl ester component may be 0.02 or more and 10 or less, and may be 0.02 or more and 5 or less, 0.02 or more and 2 or less, 0.02 or more and 1 or less, 0.02 or more and 0.7 or less, 0.08 or more and 0.7 or less, 0.02 or more and 0.5 or less, 0.08 or more and 0.5 or less, or 0.1 or more and 0.5 or less. By setting the mass ratio within this range, it is possible to further suppress the decrease in capacity at low temperatures after storage of the primary lithium battery.

[0083] As described above, the cyclic imide component may be contained in the non-aqueous electrolyte in the form of a salt. However, in this specification, the concentration or the amount based on mass of the cyclic imide component in the non-aqueous electrolyte is set to a value converted from the concentration or the amount based on mass of the cyclic imide having a free NH group.

[0084] (Boric acid organosilyl ester component)

[0085] In this specification, the boric acid organosilyl ester component refers to a compound having an -O-Si- bond formed by silylating at least one of the three OH groups which are the ester-forming sites of boric acid B(OH)3 with an organosilyl group.

[0086] The boric acid organosilyl ester component only needs to have at least one organosilyl group, but from the viewpoint of enhancing the effect of suppressing side reactions, it preferably contains an ester having two or more organosilyl groups, and more preferably contains a triester having three organosilyl groups.

[0087] The organosilyl group may have one, two, or three organic groups. It should be noted that the organic group refers to an organic group bonded to the silicon atom in the organosilyl group. From the viewpoint of enhancing the effect of suppressing side reactions, the organosilyl group preferably has two or more organic groups, and more preferably has three organic groups. At least two of the organic groups bonded to the silicon atom may be the same or all different.

[0088] Examples of the organic group include a hydrocarbon group optionally having a substituent. The hydrocarbon group may be aliphatic, alicyclic, aromatic, or araliphatic. The aliphatic and alicyclic hydrocarbon groups may be saturated or unsaturated.

[0089] Examples of the aliphatic hydrocarbon group include an alkyl group, an alkenyl group, an alkynyl group, a diene group, etc. The aliphatic hydrocarbon group may be linear or branched, either is acceptable. The number of carbon atoms of the aliphatic hydrocarbon group is, for example, 10 or less, and may be 8 or less, or 6 or less. The lower limit of the number of carbon atoms can be determined according to the type of the aliphatic hydrocarbon group. In the case of an alkyl group, it is 1 or more, and in the case of an alkenyl group and an alkynyl group, it is 2 or more. The number of carbon atoms of the diene group is 3 or more, preferably 4 or more. Specific examples of the aliphatic hydrocarbon group include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a hexyl group, a 2-ethylhexyl group, a vinyl group, an allyl group, a propargyl group, a 1,3-butadien-1-yl group, etc.

[0090] Examples of the alicyclic hydrocarbon group include a cycloalkyl group, a cycloalkenyl group, a cycloalkanedienyl group, etc. Examples of the cycloalkyl group include a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, etc. Examples of the cycloalkenyl group include a cyclohexenyl group, a cyclooctenyl group, etc. Examples of the cycloalkanedienyl group include a cyclopentadienyl group, etc. The number of carbon atoms of the alicyclic hydrocarbon group is, for example, 4 or more and 20 or less, and may be 5 or more and 10 or less, or 5 or more and 8 or less. The alicyclic hydrocarbon group also includes a condensed ring formed by condensation of an aromatic ring such as a benzene ring and a pyridine ring.

[0091] Examples of the aromatic hydrocarbon group include an aryl group, a biphenyl group, a biaryl group, etc. Examples of the aryl group include a phenyl group, a naphthyl group, etc. Examples of the biaryl group include a monovalent group corresponding to a biarylalkane, a biarylether, a biarylsulfide, etc. The aromatic hydrocarbon group also includes a condensed ring formed by condensation of a non-aromatic hydrocarbon ring or a non-aromatic heterocyclic ring. The number of carbon atoms of the aromatic hydrocarbon group is, for example, 6 or more and 20 or less, and may be 6 or more and 16 or less, or 6 or more and 14 or less.

[0092] Examples of the araliphatic hydrocarbon group include an aralkyl group. Examples of the aralkyl group include a benzyl group, a phenethyl group, etc. The number of carbon atoms of the araliphatic hydrocarbon group is, for example, 7 or more and 20 or less, and may be 7 or more and 14 or less.

[0093] Examples of the substituent include an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, a hydroxyl group, a hydroxyalkyl group, an alkoxy group, an alkoxycarbonyl group, an acyl group, an acyloxy group, a nitrile group, an oxo group (=O), a halogen atom, etc. Examples of the aliphatic hydrocarbon group include an alkyl group, an alkenyl group, etc. Examples of the alicyclic hydrocarbon group include a cycloalkyl group, etc. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. The organic group may contain one substituent or may contain two or more substituents. When the organic group contains two or more substituents, at least two substituents may be the same or all may be different.

[0094] The non-aqueous electrolyte may contain one boric acid organosilyl ester component or may contain two or more boric acid organosilyl ester components.

[0095] Among the above organic groups, alkyl, alkenyl, and aryl are preferred. These organic groups also include those with substituents. Among them, it is more preferable to use a boric acid organosilyl ester component having an alkyl group which may optionally have a substituent, i.e., an alkylsilyl borate, as the organic group. An alkyl group having 1 to 6 carbon atoms or an alkyl group having 1 to 4 carbon atoms is more preferable as the alkyl group. As the substituent, a halogen atom is preferred, and at least one selected from a fluorine atom and a chlorine atom is more preferred.

[0096] The alkylsilyl borate may be a monoester or a diester, etc., but it is preferable to use at least a triester. In the alkylsilyl borate, the alkylsilyl moiety may be a monoalkylsilyl moiety or a dialkylsilyl moiety, but it is preferable to use at least a borate having a trialkylsilyl moiety. Among them, it is more preferable to use at least tris(trialkylsilyl) borate. When including such an alkylsilyl borate, side reactions are easily suppressed, and a decrease in the discharge capacity at low temperatures after storage can be more effectively suppressed. In each of the dialkylsilyl borate and the trialkylsilyl borate, at least two of the alkyl groups bonded to the silicon atom may be the same or all different.

[0097] When the non-aqueous electrolyte satisfies the condition of the above (a), the concentration of the boric acid organosilyl ester component in the non-aqueous electrolyte is 5.5 mass% or less, and it may be 5 mass% or less. If the concentration of the boric acid organosilyl ester component exceeds 5.5 mass%, the viscosity of the non-aqueous electrolyte increases and the internal resistance of the battery becomes high. Therefore, a decrease in the discharge capacity at low temperatures after storage becomes obvious. The concentration of the boric acid organosilyl ester component in the non-aqueous electrolyte only needs to be above the detection limit, and it may be 0.1 mass% or more, 0.5 mass% or more, 0.8 mass% or more, or 1 mass% or more. These upper limit values and lower limit values can be arbitrarily combined.

[0098] During the storage or discharge of the primary lithium battery, the boric acid organosilyl ester component is consumed by film formation, etc. inside the primary lithium battery, and the concentration of the boric acid organosilyl ester component in the non-aqueous electrolyte changes. The concentration of the boric acid organosilyl ester component in the non-aqueous electrolyte used in the assembly or manufacture of the primary lithium battery is preferably 0.1 mass% or more, and more preferably set to 0.5 mass% or more, 0.8 mass% or more, or 1 mass% or more. In this case, a decrease in capacity after storing the primary lithium battery can be significantly suppressed. The concentration of the boric acid organosilyl ester component in the non-aqueous electrolyte used in the assembly or manufacture of the primary lithium battery is preferably set to 5.5 mass% or less or 5 mass% or less. In this case, an excessive increase in the viscosity of the non-aqueous electrolyte can be suppressed, and therefore, a decrease in capacity at low temperatures after storing the primary lithium battery can be effectively suppressed. These lower limit values and upper limit values can be arbitrarily combined.

[0099] When the non-aqueous electrolyte satisfies the condition of the above (b), the concentration of the boric acid organic silyl ester component in the non-aqueous electrolyte only needs to be 0.1% by mass or more and 5.5% by mass or less, and can be 0.1% by mass or more and 5% by mass or less, 0.5% by mass or more and 5.5% by mass or less, 0.5% by mass or more and 5% by mass or less, 0.8% by mass or more and 5.5% by mass or less, 0.8% by mass or more and 5% by mass or less, 1% by mass or more and 5.5% by mass or less, or 1% by mass or more and 5% by mass or less. When the concentration of the boric acid organic silyl ester component is in this range, the capacity reduction at low temperature after the storage of the primary lithium battery can be significantly suppressed.

[0100] (Non-aqueous solvent)

[0101] As the non-aqueous solvent, organic solvents that can usually be used in the non-aqueous electrolyte of the primary lithium battery can be cited. As the non-aqueous solvent, ethers, esters, carbonates, etc. can be cited. As the non-aqueous solvent, dimethyl ether, γ-butyrolactone, propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, etc. can be used. The non-aqueous electrolyte may contain one non-aqueous solvent or may contain two or more non-aqueous solvents.

[0102] From the viewpoint of improving the discharge characteristics of the primary lithium battery, the non-aqueous solvent preferably contains: a cyclic carbonate with a high boiling point and a chain ether with a low viscosity even at low temperature. The cyclic carbonate preferably contains at least one selected from the group consisting of propylene carbonate (PC) and ethylene carbonate (EC), and PC is particularly preferred. The chain ether preferably has a viscosity of 1 mPa·s or less at 25 °C, and particularly preferably contains dimethoxyethane (DME). It should be noted that the viscosity of the non-aqueous solvent is obtained as follows: using a micro-sample viscometer m-VROC manufactured by Rheosense, and performing the measurement at a temperature of 25 °C and a shear rate of 10000 (1 / s).

[0103] (Lithium salt)

[0104] The non-aqueous electrolyte may contain a lithium salt other than the cyclic imide component. As the lithium salt, for example, lithium salts used as solutes in primary lithium batteries can be cited. As such lithium salts, for example, LiCF3SO3, LiClO4, LiBF4, LiPF6, LiR a SO3 (R a is a fluorinated alkyl group with 1 to 4 carbon atoms), LiFSO3, LiN(SO2R b )(SO2R c )(R b and R cEach independently is a fluoroalkyl group having 1 to 4 carbon atoms), LiN(FSO2)2, LiPO2F2, LiB(C2O4)2, LiBF2(C2O4). The non-aqueous electrolyte may contain one of these lithium salts or may contain two or more of them.

[0105] (Others)

[0106] The concentration of lithium ions (total concentration of lithium salts) contained in the non-aqueous electrolyte is, for example, 0.2 to 2.0 mol / L and may be 0.3 to 1.5 mol / L.

[0107] The non-aqueous electrolyte may contain an additive as needed. Examples of such an additive include propanesultone, vinylene carbonate, etc. The total concentration of such an additive contained in the non-aqueous electrolyte is, for example, 0.003 to 5 mol / L.

[0108] (Separator)

[0109] A lithium primary battery generally includes a separator interposed between a positive electrode and a negative electrode. As the separator, a porous sheet formed of an insulating material resistant to the internal environment of the lithium primary battery may be used. Specifically, examples include non-woven fabric made of synthetic resin, microporous membrane made of synthetic resin, or a laminate thereof.

[0110] Examples of the synthetic resin used in the non-woven fabric include polypropylene, polyphenylene sulfide, polybutylene terephthalate, etc. Examples of the synthetic resin used in the microporous membrane include polyolefin resins such as polyethylene, polypropylene, ethylene-propylene copolymer, etc. The microporous membrane may contain inorganic particles as needed.

[0111] The thickness of the separator is, for example, 5 μm or more and 100 μm or less.

[0112] The structure of the lithium primary battery is not particularly limited. The lithium primary battery may be a coin-shaped battery having a laminated electrode group formed by laminating a disc-shaped positive electrode and a disc-shaped negative electrode with a separator interposed therebetween. It may also 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.

[0113] Figure 1 Fig. shows a front view of a cross-section of a part of a cylindrical lithium primary battery according to an embodiment of the present disclosure. For the lithium primary battery 10, an electrode group formed by winding a positive electrode 1 and a negative electrode 2 with a separator 3 interposed therebetween is housed together with a non-aqueous electrolyte in a battery case 9. A sealing plate 8 is installed at the opening of the battery case 9. A positive electrode lead 4 connected to the current collector 1a of the positive electrode 1 is connected to the sealing plate 8. A negative electrode lead 5 connected to the negative electrode 2 is connected to the battery case 9. In addition, an upper insulating plate 6 and a lower insulating plate 7 are respectively disposed above and below the electrode group to prevent internal short circuit.

[0114] [Manufacturing Method of Primary Lithium Battery]

[0115] A primary lithium battery can be manufactured by housing a positive electrode, a negative electrode, and a non-aqueous electrolyte in a battery case. The manufacturing method of the primary lithium battery of the present disclosure at least includes the following steps: preparing a non-aqueous electrolyte containing a cyclic imide component and a boric acid organic silyl ester component and satisfying the above condition (b). In the primary lithium battery obtained by the manufacturing method having such a step, a decrease in discharge capacity at low temperature after storage can be significantly suppressed. In the manufacturing method of the primary lithium battery, except for the step of preparing the non-aqueous electrolyte, a known manufacturing method can be adopted according to the type of battery, etc.

[0116] [Examples]

[0117] 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.

[0118] <Examples 1 to 5 and Comparative Examples 1 to 7>

[0119] (1) Fabrication of Positive Electrode

[0120] To 100 parts by mass of electrolytic manganese dioxide as the positive electrode, 5 parts by mass of Ketjenblack as the conductive agent, 5 parts by mass of polytetrafluoroethylene as the binder, and an appropriate amount of pure water were added and kneaded to prepare a positive electrode mixture in a wet state.

[0121] Next, the positive electrode mixture was filled into a positive electrode current collector formed of a porous metal mesh made of stainless steel (SUS444) with a thickness of 0.1 mm to fabricate a positive electrode precursor. After that, the positive electrode precursor was dried and rolled until the thickness became 0.4 mm, and then cut into a sheet with a length of 2.2 cm and a width of 1.5 cm to obtain the positive electrode. Then, a part of the filled positive electrode mixture was peeled off, and a tab lead made of SUS444 was resistance-welded to the part where the positive electrode current collector was exposed.

[0122] (2) Fabrication of Negative Electrode

[0123] A metal lithium foil with a thickness of 300 μm was cut into a size of 4 cm in length and 2.5 cm in width to obtain the negative electrode. A tab lead made of nickel was connected to a specified part of the negative electrode by crimping.

[0124] (3) Fabrication of Electrode Assembly

[0125] A separator was wound around the positive electrode and overlapped with the negative electrode to fabricate an electrode assembly. The separator used a microporous membrane made of polypropylene with a thickness of 25 μm.

[0126] (4) Preparation of Non-aqueous Electrolyte

[0127] Mix PC, EC, and DME at a volume ratio of 4:2:4. Dissolve LiCF3SO3 in the resulting mixture to a concentration of 0.5 mol / L, and dissolve phthalimide as the cyclic imide component and tris(trimethylsilyl) borate as the boric acid organic silyl ester component at the concentrations shown in Table 1 for each component. Thus, a non-aqueous electrolyte is prepared. It should be noted that in Table 1, the cyclic imide component is denoted as the first component, and the boric acid organic silyl ester component is denoted as the second component.

[0128] (5) Assembly of the primary lithium battery

[0129] The electrode assembly is housed in a tubular aluminum laminate bag with a length of 9 cm and a width of 6 cm in such a way that a part of the tab leads connected to the positive and negative electrodes protrudes from the bag, and the opening on the tab lead side is sealed. 0.5 mL of the electrolyte is injected through the opening on the side opposite to the tab leads, and the opening is sealed by vacuum heat sealing. Thus, a test primary lithium battery is fabricated. The designed capacity of the primary lithium battery is 301 mAh / g.

[0130] It should be noted that in the primary lithium battery of the example, the amount of sulfur atoms derived from sulfate contained in the positive electrode mixture is 0.05 parts by mass or more and 1.25 parts by mass or less relative to 100 parts by mass of manganese atoms contained in the positive electrode mixture. In the primary lithium battery of the example, the median value of the particle size of LixMnO2 contained in the positive electrode is 25 μm to 27 μm, and the BET specific surface area is 38 to 42 m 2 / g.

[0131] (6) Evaluation

[0132] (6-1) Discharge capacity after storage

[0133] After discharging the just-assembled primary lithium battery at a capacity equivalent to 25% of the designed capacity (C0), it is stored at 70 °C for 80 days. Then, the stored primary lithium battery is placed in a constant temperature bath at -30 °C and discharged at a current of 4.5 mA per unit mass (g) of manganese dioxide until the battery voltage reaches 2 V, and the discharge capacity (mAh / g) at this time is obtained. The ratio (%) of the discharge capacity in each primary lithium battery when the discharge capacity in the primary lithium battery of Comparative Example 7 is set to 100% is obtained as the discharge capacity after storage (relative value). The smaller this discharge capacity (%), the more the discharge capacity at low temperature after storage decreases.

[0134] The results of the examples and comparative examples are shown in Table 1. In Table 1, E1 to E5 are Examples 1 to 5, and R1 to R7 are Comparative Examples 1 to 7.

[0135] [Table 1]

[0136]

[0137] When the non-aqueous electrolyte contains the first component and does not contain the second component, the capacity is significantly reduced compared to the case where the non-aqueous electrolyte contains neither the first component nor the second component, and the discharge capacity after storage is 85% (comparison between R1 and R7). When the non-aqueous electrolyte contains the second component and does not contain the first component, there is basically no change compared to the case where the non-aqueous electrolyte contains neither the first component nor the second component, and the discharge capacity after storage is 101% (comparison between R6 and R7). By analogy from these results: when the non-aqueous electrolyte contains both the first component and the second component, the capacity reduction rate after storage becomes 85% + 1% = 86%. However, in fact, when the non-aqueous electrolyte contains both the first component and the second component, the discharge capacity after storage becomes 136% (E1), and the capacity reduction is significantly suppressed compared to a value such as the analogized 86%. It can be said that this effect is obviously based on the synergistic effect of the first component and the second component.

[0138] In addition, when the non-aqueous electrolyte satisfies at least one of the conditions in the above (a) and (b), the above-described effects of the examples are obtained (comparison between E1 to 5 and R2 to 5).

[0139] Industrial applicability

[0140] In the primary lithium battery of the present disclosure, a reduction in the discharge capacity at low temperature after storage can be suppressed. Therefore, the primary lithium battery is suitable for use as a main power source for various meters and a memory backup power source, for example. However, the use of the primary lithium battery is not limited to these.

[0141] Explanation of reference numerals

[0142] 1 Positive electrode

[0143] 1a Positive electrode current collector

[0144] 2 Negative electrode

[0145] 3 Separator

[0146] 4 Positive electrode lead

[0147] 5 Negative electrode lead

[0148] 6 Upper insulating plate

[0149] 7 Lower insulating plate

[0150] 8 Sealing plate

[0151] 9 Battery case

[0152] 10 Primary lithium battery

Claims

1. A primary lithium battery, comprising: a positive electrode, a negative electrode, and a non-aqueous electrolyte, The positive electrode contains a positive electrode mixture containing LixMnO2, wherein, 0≤x≤0.05， The negative electrode contains at least one of metallic lithium and a lithium alloy. The non-aqueous electrolyte contains a cyclic imide component and a boric acid organosilyl ester component having an ester-forming site of boric acid B(OH)3, i.e., an -O-Si- bond formed by organosilyl esterification of at least one of the three OHs. The concentration of the cyclic imide component in the non-aqueous electrolyte is 1 mass% or less. The concentration of the boric acid organosilyl ester component in the non-aqueous electrolyte is 5.5 mass% or less. The mass ratio of the cyclic imide component contained in the non-aqueous electrolyte to the boric acid organosilyl ester component is 0.02 or more and 1 or less.

2. The primary lithium battery according to claim 1, wherein, The concentration of the cyclic imide component in the non-aqueous electrolyte is 0.1 mass% or more. The concentration of the boric acid organosilyl ester component in the non-aqueous electrolyte is 0.1 mass% or more.

3. The primary lithium battery according to claim 1 or 2, wherein, The cyclic imide component contains at least one selected from the group consisting of phthalimide and N-substituted phthalimide.

4. The primary lithium battery according to claim 1 or 2, wherein, The cyclic imide component contains at least phthalimide.

5. The primary lithium battery according to claim 1 or 2, wherein, The boric acid organosilyl ester component contains a triester having three organosilyls. Each of the organosilyls has three organic groups.

6. The primary lithium battery according to claim 5, wherein, Each of the organic groups is an alkyl group.

7. The primary lithium battery according to claim 6, wherein, The alkyl group has 1 to 4 carbon atoms.

8. The primary lithium battery according to any one of claims 1, 2, 6, and 7, wherein, The positive electrode mixture further contains a sulfate. The amount of sulfur atoms contained in the positive electrode mixture is 0.05 mass parts or more and 3 mass parts or less with respect to 100 mass parts of manganese atoms contained in the positive electrode mixture.

9. The primary lithium battery according to any one of claims 1, 2, 6, and 7, wherein, The median value of the particle size of LixMnO2 is 10 μm or more and 40 μm or less.

10. The primary lithium battery according to any one of claims 1, 2, 6, and 7, wherein, The BET specific surface area of LixMnO2 is above 20 m 2 / g and below 50 m 2 / g.

11. The primary lithium battery according to any one of claims 1, 2, 6, and 7, wherein, The positive electrode includes a porous current collector and the positive electrode mixture filled in the current collector. The current collector contains at least one material selected from the group consisting of SUS444, SUS430, and SUS316. The thickness of the positive electrode is 300 μm or more and 900 μm or less.

12. The primary lithium battery according to any one of claims 1, 2, 6, and 7, wherein, The negative electrode contains a foil of metallic lithium or a lithium alloy and has a shape having a length direction and a width direction. A long-sized tape having a resin substrate and an adhesive layer is adhered along the length direction on at least one main surface of the negative electrode.

13. A non-aqueous electrolyte for a primary lithium battery, which is a non-aqueous electrolyte for a primary lithium battery. The primary lithium battery includes: a positive electrode containing a positive electrode mixture including LixMnO2, wherein, 0 ≤ x ≤ 0.05; a negative electrode, which contains at least one of metallic lithium and a lithium alloy; and, a non-aqueous electrolyte The non-aqueous electrolyte contains a cyclic imide component and a boric acid organosilyl ester component having an ester-forming site of boric acid B(OH)3, i.e., an -O-Si- bond formed by organosilyl esterification of at least one of the three OHs. The concentration of the cyclic imide component in the non-aqueous electrolyte is 1 mass% or less. The concentration of the boric acid organosilyl ester component in the non-aqueous electrolyte is 5.5 mass% or less. The mass ratio of the cyclic imide component contained in the non-aqueous electrolyte to the boric acid organosilyl ester component is 0.02 or more and 1 or less.

14. The non-aqueous electrolyte for a primary lithium battery according to claim 13, wherein, The cyclic imide component contains at least one selected from the group consisting of phthalimide and N-substituted phthalimide.

15. The non-aqueous electrolyte for a primary lithium battery according to claim 13 or 14, wherein, The cyclic imide component contains at least phthalimide.

16. The non-aqueous electrolyte for a primary lithium battery according to claim 13 or 14, wherein, The boric acid organosilyl ester component contains a triester having three organosilyls. The organic silyls each have three organic groups.

17. The non-aqueous electrolyte for a primary lithium battery according to claim 16, wherein, The organic groups are each alkyl groups.

18. The non-aqueous electrolyte for a primary lithium battery according to claim 17, wherein, The alkyl groups have 1 to 4 carbon atoms.

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