Lithium primary battery

Abstract

This lithium primary battery is provided with a positive electrode, a negative electrode, and a non-aqueous electrolyte solution. The positive electrode contains a positive electrode mixture that contains manganese dioxide and an oxide of a metal Me. The metal Me has a valence of 2 or more, an ion radius of 0.8 or less, and an electronegativity of 1.65 or less. The amount of the oxide of the metal Me contained in the positive electrode mixture is 0.1-5 parts by mass per 100 parts by mass of the manganese dioxide contained in the positive electrode mixture. The negative electrode contains an alloy containing lithium and magnesium. The content of lithium in the alloy is greater than 88% by mass, and the content of magnesium in the alloy is 0.01-10% by mass (inclusive).

Description

Technical Field

[0001] This application relates to a primary lithium battery. Background Technology

[0002] Lithium-ion primary batteries are used as power sources for many electronic devices due to their high energy density and low self-discharge. The positive electrode of a lithium-ion primary battery uses materials such as manganese dioxide. The negative electrode uses, for example, sheet-like (foil-like) metallic lithium or lithium alloys.

[0003] Patent document 1 proposes "a lithium anode in a lithium-organic electrolyte battery in which lithium salt is dissolved in an electrolyte and spacers face each other, using a lithium body with an aluminum-magnesium alloy capping layer initially stacked on the surface of the lithium body adjacent to the spacers as the anode, and forming an aluminum-magnesium-lithium ternary alloy through diffusion, thereby increasing the surface area of ​​the anode and improving the pulse performance of the battery."

[0004] Patent document 2 proposes "a battery characterized in that it is composed of a negative electrode with a light metal as the active material, an organic electrolyte and a positive electrode with manganese dioxide as the active material, wherein the positive electrode is mixed with an oxide of an alkaline earth metal".

[0005] Patent document 3 proposes "a positive electrode for a lithium primary battery, characterized in that at least one metal oxide selected from titanium oxide, aluminum oxide, zinc oxide, chromium oxide, lithium oxide, nickel oxide, copper oxide and iron oxide is dispersed between manganese dioxide particles".

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 58-209862

[0009] Patent Document 2: Japanese Patent Application Publication No. 56-103864

[0010] Patent Document 3: Japanese Patent Application Publication No. 2003-249213 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] In lithium primary batteries, there are cases where the internal resistance increases after long-term storage, resulting in a decrease in discharge characteristics.

[0013] Methods for solving problems

[0014] One aspect of this application relates to a lithium primary battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode comprises a positive electrode compound containing manganese dioxide and an oxide of a metal Me other than manganese. The metal Me has a valence of 2 or more, an ionic radius of 0.8 Å or less, and an electronegativity of 1.65 or less. The amount of the metal Me oxide contained in the positive electrode compound is 0.1 parts by mass or more and 5 parts by mass or less relative to 100 parts by mass of the manganese dioxide contained in the positive electrode compound. The negative electrode comprises an alloy containing lithium and magnesium, wherein the lithium content in the alloy is greater than 88% by mass, and the magnesium content in the alloy is 0.01% by mass or more and 10% by mass or less.

[0015] Invention Effects

[0016] According to this application, it is possible to suppress the degradation of discharge characteristics of lithium primary batteries after long-term storage.

[0017] The novel features of the invention are set forth within the scope of the appended claims; however, the invention should be more fully understood, in both its composition and content, together with its other objects and features, by referring to the following detailed description of the accompanying drawings. Attached Figure Description

[0018] Figure 1 This is a front view of a cross-section of a portion of a primary lithium battery according to one embodiment of this application. Detailed Implementation

[0019] The following describes embodiments of this application by way of example; however, this application is not limited to the examples described below. In the following description, specific values ​​and materials are sometimes shown; however, other values ​​and materials can be applied as long as the effects of this application are achieved. In this specification, the phrase "value A to value B" includes both value A and value B, and can be changed to "value A or above and value B or below". In the following description, when lower and upper limits of values ​​relating to specific physical properties, conditions, etc., are shown, any combination of the shown lower limit and any shown upper limit can be used as long as the lower limit is not above the upper limit. When multiple materials are shown, one can be selected for use alone, or two or more can be used in combination.

[0020] The lithium primary battery of this application comprises a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode comprises a positive electrode additive, which includes manganese dioxide (positive electrode active material) and an oxide (additive) of a metallic Me other than manganese. The metallic Me has a valence of 2 or higher, an ionic radius of 0.8 Å or less, and an electronegativity of 1.65 or less. The amount of the metallic Me oxide contained in the positive electrode additive is 0.1 parts by mass or more and 5 parts by mass or less relative to 100 parts by mass of manganese dioxide contained in the positive electrode additive. The negative electrode comprises an alloy containing lithium (Li) and magnesium (Mg). Hereinafter, this alloy will also be referred to as a "lithium alloy containing Mg". The Li content in the lithium alloy is greater than 88% by mass. The Mg content in the lithium alloy is 0.01% by mass or more and 10% by mass or less.

[0021] By incorporating an oxide of metallic Me into the positive electrode mixture, the degradation of the non-aqueous electrolyte (solvent decomposition) during storage is suppressed, as are the gas generation and increased internal resistance associated with solvent decomposition, thus mitigating the decline in storage performance to some extent. It should be noted that the hydroxyl groups present on the surface of manganese dioxide and the trace amounts of water inevitably present in the non-aqueous electrolyte during manufacturing participate in the aforementioned solvent decomposition. However, the storage performance is still insufficient. To improve the storage performance, the inventors conducted in-depth research. The result is a new discovery: by incorporating an oxide of metallic Me into the positive electrode mixture and simultaneously incorporating Mg into the lithium alloy of the negative electrode, the decline in storage performance is significantly suppressed.

[0022] Under the aforementioned conditions, the increase in internal resistance and the associated decrease in discharge characteristics (e.g., voltage reduction during low-temperature pulsed discharge after storage) after long-term storage are suppressed. That is, the decrease in storage characteristics is suppressed. Although the detailed mechanism is unclear, it can be inferred as follows: During long-term storage, metallic Me (Me) contained in the positive electrode mixture dissolves from the positive electrode and precipitates at the negative electrode. Due to the contact between the negative electrode and the non-aqueous electrolyte, metallic Me is introduced into the coating formed on the surface of the negative electrode. If the dispersion of metallic Me in the coating is low, Li ions do not easily move within the coating, resulting in an increase in negative electrode resistance. Conversely, when the negative electrode (lithium alloy) contains Mg, a certain interaction occurs between Mg and metallic Me, improving the dispersion of metallic Me in the coating and suppressing the aforementioned increase in negative electrode resistance. It can be considered that the good dispersion of Mg is related to the aforementioned interaction.

[0023] If the amount of metal Me oxide in the positive electrode mixture is less than 0.1 parts by mass relative to 100 parts by mass of manganese dioxide in the positive electrode mixture, the effect of adding metal Me oxide is smaller, and the suppression of the reduction in preservation properties becomes insufficient.

[0024] If the amount of metal Me oxide in the positive electrode mixture is greater than 5 parts by mass relative to 100 parts by mass of manganese dioxide in the positive electrode mixture, the proportion of metal Me oxide in the positive electrode mixture increases, the positive electrode resistance increases, and thus the discharge characteristics decrease.

[0025] Assuming that the Mg content in the lithium alloy is greater than 10% by mass, the negative electrode resistance increases due to the increased proportion of Mg in the negative electrode, resulting in a decrease in discharge characteristics.

[0026] Assuming that the Li content in the lithium alloy is below 88% by mass, the negative electrode resistance increases due to the smaller proportion of Li in the negative electrode, resulting in a decrease in discharge characteristics.

[0027] (Oxides of metal Me)

[0028] Metallic Me (Me) has a valence of 2 or higher, an ionic radius of 0.8 Å or less, and an electronegativity of 1.65 or less. When the valence of metallic Me is within the above range, the conductivity of Li ions in the film is enhanced because metallic Me, which has a larger valence than Li, is present. When the ionic radius and electronegativity of metallic Me are within the above range, the movement of lithium ions in the film is less hindered due to factors such as the small difference in ionic radius and electronegativity compared to Li.

[0029] It should be noted that the valence of metallic Me refers to the valence of metallic Me when it exists in the form of its oxide. The ionic radius and electronegativity of metallic Me are those of Pauling. Metallic Me can be used alone or in combination of two or more types.

[0030] The metal Me preferably includes at least one selected from magnesium (Mg), aluminum (Al), titanium (Ti), zinc (Zn), zirconium (Zr), and niobium (Nb). Among these, zinc (Zn) is particularly preferred from the viewpoint of high surface coating properties of manganese dioxide.

[0031] The oxide of metallic Me preferably includes at least one selected from MgO, Al2O3, TiO2, ZnO, ZrO2, and Nb2O5. The cathode compound may include, for example, cathode active material particles, the oxide of metallic Me, and a binder. The cathode compound may comprise a composite in which the surface of the cathode active material particles is covered by the oxide of metallic Me. To obtain the composite, the cathode active material particles and the oxide particles of metallic Me can be composited. Alternatively, the cathode compound may comprise a mixture of cathode active material particles and oxide particles of metallic Me. One type of oxide of metallic Me may be used alone, or two or more types may be used in combination.

[0032] The amount of metal Me oxide contained in the positive electrode mixture is 0.1 parts by mass or more and 5 parts by mass or less relative to 100 parts by mass of manganese dioxide contained in the positive electrode mixture, preferably 0.5 parts by mass or more and 2 parts by mass or less.

[0033] When the positive electrode mixture contains MgO and manganese dioxide, the amount of Mg atoms in the positive electrode mixture is preferably 0.1 parts by mass or more and 4.8 parts by mass or less, more preferably 0.48 parts by mass or more and 1.9 parts by mass or less, relative to 100 parts by mass of Mn atoms in the positive electrode mixture.

[0034] When the positive electrode mixture contains Al2O3 and manganese dioxide, the amount of Al atoms in the positive electrode mixture is preferably 0.08 parts by mass or more and 4.2 parts by mass or less, more preferably 0.42 parts by mass or more and 1.7 parts by mass or less, relative to 100 parts by mass of Mn atoms in the positive electrode mixture.

[0035] When the cathode agent contains TiO2 and manganese dioxide, the amount of Ti atoms in the cathode agent is preferably 0.095 parts by mass or more and 4.7 parts by mass or less, more preferably 0.47 parts by mass or more and 1.9 parts by mass or less, relative to 100 parts by mass of Mn atoms in the cathode agent.

[0036] When the positive electrode mixture contains ZnO and manganese dioxide, the amount of Zn atoms in the positive electrode mixture is preferably 0.13 parts by mass or more and 6.4 parts by mass or less, more preferably 0.64 parts by mass or more and 2.5 parts by mass or less, relative to 100 parts by mass of Mn atoms in the positive electrode mixture.

[0037] When the cathode agent contains ZrO2 and manganese dioxide, the amount of Zr atoms in the cathode agent is preferably 0.12 parts by mass or more and 5.9 parts by mass or less, more preferably 0.59 parts by mass or more and 2.3 parts by mass or less, relative to 100 parts by mass of Mn atoms in the cathode agent.

[0038] When the positive electrode mixture contains Nb2O5 and manganese dioxide, the amount of Nb atoms contained in the positive electrode mixture is preferably 0.11 parts by mass or more and 5.5 parts by mass or less, more preferably 0.55 parts by mass or more and 2.2 parts by mass or less, relative to 100 parts by mass of Mn atoms contained in the positive electrode mixture.

[0039] In the above scenario, Mg, Al, Ti, Zn, Zr, and Nb originate from MgO, Al₂O₃, TiO₂, ZnO, ZrO₂, and Nb₂O₅, respectively. Mn originates from manganese dioxide.

[0040] The amount (mass parts) of metal Me atoms contained in the above-mentioned positive electrode mixture can be calculated as follows.

[0041] The initial battery (e.g., a battery that has just been manufactured or is unused within one week of purchase) is disassembled, and the positive electrode mixture is removed. It is then dissolved in an acid solution (such as hydrochloric acid), and the insoluble components are separated by filtration or centrifugation to obtain a sample solution. Using inductively coupled plasma (ICP) luminescence spectrophotometry, the amount of metallic Me (WMe) and Mn (WMn) in the sample solution are determined, and (WMe / WMn) × 100 is calculated as the amount (parts by mass) of metallic Me atoms. For example, the Thermofisher Scientific iCAP7400 Duo can be used for this determination.

[0042] (Lithium alloy)

[0043] From the perspective of reducing internal resistance and ensuring capacity, the Li content in the lithium alloy is greater than 88% by mass, or it can be 89% by mass or more, 90% by mass or more, or 95% by mass or more. Alternatively, the Li content in the lithium alloy can be 99.99% by mass or less. From the perspective of suppressing the decline in storage properties, the Mg content in the lithium alloy is 0.01% by mass or more and 10% by mass or less.

[0044] From the perspective of improving preservation properties, lithium alloys preferably further contain Al. Hereinafter, lithium alloys containing Mg but substantially not containing Al will be referred to as "Li-Mg alloys." Lithium alloys containing both Mg and Al will be referred to as "Li-Mg-Al alloys." It should be noted that "substantially not containing" means that the content is below the detection limit in the compositional analysis of the lithium alloy (e.g., ICP emission spectrophotometry, atomic absorption spectrometry, etc.).

[0045] By adding Al, the increase in internal resistance during storage (long-term use) is suppressed; however, Al tends to segregate in Li. On the other hand, Mg has excellent dispersibility in Li. When the lithium alloy contains both Mg and Al, Al segregation is suppressed due to the good dispersibility of Mg, and the uneven consumption of Li caused by Al segregation is also suppressed. In this case, the effects of Mg and Al are stably obtained throughout the negative electrode, while Li is uniformly consumed on the negative electrode surface, and the proportion of Li that can participate in the discharge reaction at the end of the discharge period becomes larger. When both Mg and Al are included, a low-resistivity film is easily and stably formed, the voltage at the end of the discharge period is further improved, and the decline in storage characteristics is further suppressed.

[0046] From the viewpoint of suppressing the degradation of storage properties, the Mg content in the lithium alloy is 0.01% by mass or more, preferably 0.2% by mass or more, and more preferably 0.5% by mass or more. From the viewpoint of reducing negative electrode resistance, the Mg content in the lithium alloy is 10% by mass or less, preferably 5% by mass or less, and more preferably 2% by mass or less. The range of Mg content in the lithium alloy can be, for example, 0.2% by mass or more and 5% by mass or less, or 0.5% by mass or more and 2% by mass or less. It should be noted that the Mg content in the lithium alloy described above refers to the Mg content in Li-Mg alloys or Li-Mg-Al alloys.

[0047] From the viewpoint of suppressing the degradation of preservation properties, the Al content in the lithium alloy (Li-Mg-Al alloy) is preferably 0.01% by mass or more (or 0.1% by mass or more) and 5% by mass or less, more preferably 0.1% by mass or more and 4% by mass or less (or 3% by mass or less). From the same viewpoint, the total Mg and Al content in the Li-Mg-Al alloy is preferably 0.02% by mass or more and 10% by mass or less. The molar ratio of Mg to Al: Mg / Al can, for example, be in the range of 0.02 or more and 3 or less.

[0048] Lithium alloys can also contain metallic elements other than Li, Mg, and Al. Examples of such metallic elements include Sn, Ni, Pb, In, Na, K, and Ca.

[0049] The composition of lithium alloys can be determined using inductively coupled plasma (ICP) emission spectrophotometry or atomic absorption spectrometry (AAS).

[0050] The lithium primary battery of this application will be described in more detail below.

[0051] [Lithium primary battery]

[0052] (positive electrode)

[0053] The positive electrode contains a positive electrode additive. The positive electrode additive includes manganese dioxide as the positive electrode active material. The positive electrode containing manganese dioxide exhibits a higher voltage and excellent pulse discharge characteristics. Manganese dioxide obtained by sintering electrolytic manganese dioxide can be suitable as the manganese dioxide. Manganese dioxide can also be in a mixed crystal state containing multiple crystalline states. The positive electrode may also contain manganese oxides other than manganese dioxide. Examples of manganese oxides other than manganese dioxide include MnO, Mn3O4, Mn2O3, and Mn2O7. Preferably, the main component of the manganese oxides contained in the positive electrode is manganese dioxide.

[0054] The manganese dioxide in the positive electrode can be doped with a small amount of lithium. If the lithium doping level is small, high capacity can be ensured. Manganese dioxide and manganese dioxide doped with a small amount of lithium can be processed using Li... xMnO2 (0≤x≤0.05) is used. It should be noted that the overall average composition of the manganese oxide in the positive electrode is Li. x MnO2 (0 ≤ x ≤ 0.05) is sufficient. It should be noted that the Li ratio x should be below 0.05 in the initial discharge state of the lithium primary battery. The Li ratio x typically increases as the lithium primary battery discharges. Theoretically, the manganese oxide in manganese dioxide is tetravalent. However, due to the presence of other manganese oxides in the positive electrode or the doping of lithium in manganese dioxide, the manganese oxide number may sometimes slightly increase or decrease relative to tetravalent. Therefore, in Li... x In MnO2, the permissible average oxidation number of manganese varies slightly relative to the 4-valent oxidation state.

[0055] The positive electrode may contain manganese dioxide as well as other positive electrode active materials used in primary lithium batteries. Examples of other positive electrode active materials include fluorinated graphite. The proportion of manganese dioxide in the total positive electrode active material is preferably 90% by mass or more.

[0056] Electrolytic manganese dioxide can be appropriately used as a form of manganese dioxide. By adjusting the calcination conditions, the crystallinity of manganese dioxide can be increased, and the specific surface area of ​​electrolytic manganese dioxide can be reduced. The BET specific surface area of ​​manganese dioxide can be 5 m². 2 / g or more and 40m 2 / g or less. When the BET specific surface area of ​​manganese dioxide is within the above range, self-discharge is suppressed, and the decrease in pulse discharge characteristics after storage can be further suppressed.

[0057] The BET specific surface area of ​​manganese dioxide can be determined using known methods, such as a specific surface area measuring device (e.g., manufactured by MOUNTECH Co., Ltd.) based on the BET method. For example, manganese dioxide separated from the positive electrode taken from a battery can be used as the test sample.

[0058] The central particle size of manganese dioxide can be greater than 5 μm and less than 40 μm. When the central particle size is within the above range, self-discharge is suppressed, and the decrease in pulse discharge characteristics after storage can be further suppressed.

[0059] The median particle size of manganese dioxide is, for example, the median of the particle size distribution determined using quantitative laser diffraction / scattering (qLD). For example, manganese dioxide separated from the positive electrode taken from a battery can be used as the test sample. For example, a SALD-7500 nano-sized laser manufactured by Shimadzu Corporation can be used for the measurement.

[0060] The positive electrode additive may contain a binder in addition to the positive electrode active material and the oxide of metallic Me. The positive electrode additive may contain a conductive agent.

[0061] Examples of adhesives include fluoropolymers, rubber particles, and acrylic resins.

[0062] Examples of conductive agents include conductive carbon materials. Examples of conductive carbon materials include natural graphite, synthetic graphite, carbon black, and carbon fiber.

[0063] The positive electrode may further include a positive current collector that retains the positive electrode binder. Examples of materials that can be used as the positive current collector include stainless steel, aluminum, and titanium.

[0064] In the case of a coin-shaped battery, the positive electrode can be formed by mounting an L-shaped annular positive current collector onto positive electrode particles, or the positive electrode can be formed using only positive electrode particles. Positive electrode particles can be obtained, for example, by compressing and drying a moistened positive electrode mixture prepared by adding an appropriate amount of water to the positive electrode active material and additives.

[0065] In the case of a cylindrical battery, a positive electrode comprising a sheet-like positive current collector and a positive electrode flux layer held by the positive current collector can be used. As the sheet-like positive current collector, a porous current collector is preferred. Examples of porous current collectors include stretched metal, mesh, and perforated metal. The positive electrode flux layer can be obtained, for example, by coating the surface of the sheet-like positive current collector or filling it into the positive current collector with the aforementioned wetted positive electrode flux, applying pressure along the thickness direction, and then drying.

[0066] The positive electrode preferably comprises a porous current collector as described above and a positive electrode filler filled within the current collector. Preferably, a current collector comprising at least one material selected from SUS444, SUS430, and SUS316 is used. By using such a current collector, side reactions with the aforementioned non-aqueous electrolyte and corrosion of the current collector can be suppressed in the lithium primary battery, and the increase in internal resistance and gas generation can be suppressed. In particular, when such a current collector is used in combination with a non-aqueous electrolyte comprising at least one of LiCF3SO3 and LiClO4, typically used in lithium primary batteries, as the lithium salt, side reactions between the current collector and the non-aqueous electrolyte can be suppressed more efficiently. The thickness of the positive electrode is, for example, 300 μm or more and 900 μm or less.

[0067] (negative electrode)

[0068] The negative electrode may, for example, comprise a foil (sheet) lithium alloy. The lithium alloy is shaped into any shape and thickness according to the shape, size, specifications, and performance characteristics of the primary lithium battery.

[0069] In the case of cylindrical batteries, the negative electrode can have a negative electrode current collector (e.g., copper foil) carrying a lithium alloy, or it can be a foil (sheet) lithium alloy without a negative electrode current collector. When the lithium alloy contains Mg, since the residual Mg has a high strength at the end of discharge, the negative electrode can be constructed using only the foil (sheet) lithium alloy without a negative electrode current collector. By using a lithium alloy containing Mg, the breakage and localized defects of the negative electrode at the end of discharge, which occurs when the negative electrode does not contain a negative electrode current collector, can be suppressed. The shape of the negative electrode (lithium alloy) can be maintained even at the end of discharge, and the conductivity of the entire negative electrode can be ensured even without a negative electrode current collector.

[0070] In the case of coin-shaped batteries, a material obtained by punching a ring-shaped lithium alloy into a disc shape can be used as the negative electrode. In the case of cylindrical batteries, a sheet-shaped lithium alloy can be used as the negative electrode. For example, the sheet can be obtained by extrusion molding. More specifically, in cylindrical batteries, lithium alloy foils or the like with shapes having both length and width directions are used.

[0071] (Non-aqueous electrolyte)

[0072] Non-aqueous electrolytes are used as non-aqueous electrolytes containing lithium salts dissolved in non-aqueous solvents.

[0073] Examples of non-aqueous solvents commonly used in non-aqueous electrolytes for primary lithium batteries include ethers, esters, and carbonates. Other non-aqueous solvents include dimethyl ether, γ-butyrolactone, propylene carbonate, ethylene carbonate, and 1,2-dimethoxyethane. Non-aqueous electrolytes may contain one or more non-aqueous solvents.

[0074] From the viewpoint of improving the discharge characteristics of lithium primary batteries, the non-aqueous solvent preferably comprises a cyclic carbonate with a high boiling point and a linear ether with low viscosity at low temperatures. The cyclic carbonate preferably comprises at least one selected from propylene carbonate (PC) and ethylene carbonate (EC), with PC being particularly preferred. The linear ether preferably has a viscosity of less than 1 mPa·s at 25°C, with dimethoxyethane (DME) being particularly preferred. It should be noted that the viscosity of the non-aqueous solvent is determined using a micro-sample viscometer m-VROC manufactured by RHEOSENSE at 25°C by measurement based on a shear rate of 10000 (1 / s).

[0075] Examples of lithium salts include LiCF3SO3, LiClO4, LiBF4, LiPF6, LiRaSO3 (Ra is a fluoroalkyl group with 1 to 4 carbon atoms), LiFSO3, LiN(SO2Rb)(SO2Rc) (Rb and Rc are each independently a fluoroalkyl group with 1 to 4 carbon atoms), and LiN(FSO2)2. A single lithium salt can be used, or two or more can be used in combination.

[0076] The concentration of lithium ions (total concentration of lithium salts) in the non-aqueous electrolyte is, for example, 0.2 mol / L or more and 2.0 mol / L or more and 0.3 mol / L or 1.5 mol / L or less.

[0077] Non-aqueous electrolytes may contain additives as needed. Examples of such additives include phthalimides, N-substituted phthalimide compounds, dimethyl phthalate, phthalate ester compounds, propanesulfonate lactone, and vinylene carbonate. The total concentration of such additives in the non-aqueous electrolyte is, for example, 0.003–5 mol / L.

[0078] (spacer)

[0079] Lithium-ion primary batteries typically have a spacer sandwiched between the positive and negative electrodes. As a spacer, a porous sheet made of an insulating material that is resistant to the internal environment of the lithium-ion primary battery can be used. Specifically, examples include nonwoven fabrics made of synthetic resin, microporous membranes made of synthetic resin, or laminates thereof.

[0080] Examples of synthetic resins used in nonwoven fabrics include polypropylene, polyphenylene sulfide, and polybutylene terephthalate. Examples of synthetic resins used in microporous membranes include polyethylene, polypropylene, and polyolefin resins such as ethylene-propylene copolymer. Microporous membranes may also contain inorganic particles as needed.

[0081] The thickness of the spacer is, for example, 5 μm or more and 100 μm or less.

[0082] There are no particular limitations on the structure of a primary lithium battery. A primary lithium battery can be a coin-shaped battery with a stacked electrode assembly consisting of a circular positive electrode and a circular negative electrode separated by a spacer. It can also be a cylindrical battery with a wound electrode assembly consisting of a strip-shaped positive electrode and a strip-shaped negative electrode separated by a spacer wound into a spiral shape.

[0083] Figure 1The image shows a front view of a portion of a cylindrical lithium primary battery according to one embodiment of this application, in cross-section. The lithium primary battery 10 houses an electrode assembly, formed by winding a positive electrode 1 and a negative electrode 2 separated by a spacer 3, within a battery casing 9 along with a non-aqueous electrolyte (not shown). A sealing plate 8 is installed at the opening of the battery casing 9. A positive electrode lead 4, connected to the current collector 1a of the positive electrode 1, is connected to the sealing plate 8. A negative electrode lead 5, connected to the negative electrode 2, is connected to the casing 9. Furthermore, to prevent internal short circuits, an upper insulating plate 6 and a lower insulating plate 7 are respectively disposed above and below the electrode assembly.

[0084] Postscript

[0085] The following technology is disclosed through the description of the above embodiments.

[0086] (Technology 1)

[0087] A primary lithium battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte.

[0088] The aforementioned positive electrode contains a positive electrode mixture.

[0089] The aforementioned positive electrode mixture contains manganese dioxide and oxides of metals other than manganese (Me).

[0090] The aforementioned metal Me has a valence of 2 or higher, an ionic radius of less than 0.8 Å, and an electronegativity of less than 1.65.

[0091] The amount of metal Me oxide contained in the above-mentioned positive electrode mixture is 0.1 parts by mass and less than 5 parts by mass relative to 100 parts by mass of manganese dioxide contained in the above-mentioned positive electrode mixture.

[0092] The aforementioned negative electrode contains an alloy of lithium and magnesium.

[0093] The lithium content in the above alloy is greater than 88% by mass.

[0094] The magnesium content in the above alloy is 0.01% by mass or more and 10% by mass or less.

[0095] (Technology 2)

[0096] According to the lithium primary battery described in Technology 1, the aforementioned alloy comprises aluminum.

[0097] The total content of the magnesium and aluminum in the above alloy is 0.02% by mass or more and 10% by mass or less.

[0098] (Technology 3)

[0099] According to the lithium primary battery described in technology 1 or 2, the aforementioned metal Me comprises at least one selected from magnesium, aluminum, titanium, zinc, zirconium, and niobium.

[0100] (Technology 4)

[0101] According to any one of the technologies 1 to 3, in a lithium primary battery, the central value of the particle size of the aforementioned manganese dioxide is 5 μm or more and 40 μm or less.

[0102] (Technology 5)

[0103] According to any one of the lithium primary batteries described in technology 1 to 4, the BET specific surface area of ​​the aforementioned manganese dioxide is 5 m². 2 / g or more and 40m 2 / g or less.

[0104] [Example]

[0105] The present application will now be described in detail based on the embodiments and comparative examples; however, the present application is not limited to the following embodiments.

[0106] (The production of the positive electrode)

[0107] Electrolyzed manganese dioxide after calcination was mixed with oxides of metallic Me and then subjected to a composite treatment. The composite treatment used a dry particle composite apparatus, "Nobilta NOB-130," manufactured by HOSOKAWA MICRON Co., Ltd. This resulted in a composite material in which the surface of manganese dioxide particles was covered with oxides of metallic Me. The metallic Me used were the metals listed in the table. The oxides of metallic Me used were MgO, Al₂O₃, TiO₂, ZnO, ZrO₂, Nb₂O₅, Y₂O₃, MoO₃, CdO, or In₂O₃.

[0108] To 100 parts by mass of the positive electrode active material, 3 parts by mass of Ketjenblack as a conductive agent, 5 parts by mass of polytetrafluoroethylene as a binder, and an appropriate amount of pure water are added and mixed to prepare a moist positive electrode mixture. The positive electrode active material used is the composite material obtained above or calcined electrolytic manganese dioxide.

[0109] The content of the oxide of metallic Me in the positive electrode mixture is set as shown in the table. It should be noted that the "content of oxide of metallic Me" in the positive electrode mixture column of the table is the amount (parts by mass) relative to 100 parts by mass of manganese dioxide contained in the positive electrode mixture. Therefore, the content of metallic Me atoms in the positive electrode mixture is the value shown in the table. It should also be noted that the "content of metallic Me atoms" in the positive electrode mixture column of the table is the amount (parts by mass) relative to 100 parts by mass of manganese atoms contained in the positive electrode mixture. Metallic Me atoms come from the oxide of metallic Me, and manganese atoms come from manganese dioxide.

[0110] Next, the positive electrode filler is filled into a 0.4mm thick sheet of stretched stainless steel (SUS444) metal current collector to create the positive electrode precursor. The precursor is then dried and rolled to a thickness of 0.5mm using a roller press, and cut to the specified dimensions to obtain the positive electrode. Next, a portion of the filled positive electrode filler is peeled off, and one end of a stainless steel positive electrode lead is resistance-welded to the exposed portion of the current collector.

[0111] (Making the negative electrode)

[0112] Lithium metal foil or lithium alloy foil (200 μm thick) is cut to specified dimensions to obtain the negative electrode. A nickel negative electrode lead is ultrasonically welded to a specified location on the negative electrode. Elements other than Li in the lithium alloy foil are designated as Mg and / or Al. The Mg and Al contents in the lithium alloy foil are set as shown in the table. A "-" in the Mg (or Al) content column of the table indicates that the Mg (or Al) content is less than the detection limit in compositional analysis (ICP-luminescence spectrophotometry, etc.).

[0113] (Fabrication of the electrode assembly)

[0114] The electrode assembly is fabricated by winding the positive and negative electrodes together with a spacer in between. The spacer is a microporous membrane made of polypropylene with a thickness of 25 μm.

[0115] (Preparation of non-aqueous electrolyte)

[0116] Propylene carbonate (PC), ethylene carbonate (EC), and 1,2-dimethoxyethane (DME) were mixed in a volume ratio of 4:2:4 to obtain a non-aqueous solvent. LiCF3SO3 was dissolved in the non-aqueous solvent at a concentration of 0.5 mol / L to prepare a non-aqueous electrolyte.

[0117] (Assembly of primary lithium batteries)

[0118] The electrode assembly is housed within a cylindrical battery casing that also serves as the negative terminal. The battery casing is made of iron (17 mm outer diameter, 45.5 mm height). After injecting a non-aqueous electrolyte into the battery casing, the opening of the battery casing is sealed using a metal sealing plate that also serves as the positive terminal. The other end of the positive electrode lead is connected to the sealing plate, and the other end of the negative electrode lead is connected to the inner bottom surface of the battery casing. A cylindrical primary lithium battery is thus fabricated. The newly assembled battery is discharged at 2.4 A for 2 minutes and then aged for 7 days at 45°C. It should be noted that the aged positive electrode active material is in the form of Li... x The chemical formula for MnO2 indicates that the x-value representing the amount of lithium doping is in the range of 0 < x ≤ 0.05.

[0119] It should be noted that the positive electrode mixture contains Li x The central particle size of MnO2 is 21–23 μm, and the BET specific surface area is 14–15 m². 2 / g.

[0120] In the table, A1-1 to A1-16, A2-1 to A2-16, A3-1 to A3-16, A3-1 to A3-16, A4-1 to A4-16, A5-1 to A5-16, A6-1 to A6-16, and A7-1 to A7-3 are batteries of the embodiments. Additionally, in the table, B1-1 to B1-7, B2-1 to B2-7, B3-1 to B3-7, B4-1 to B4-7, B5-1 to B5-7, and B6-1 to B6-7 are batteries of comparative examples. In the table, R1-1 to R1-3, R2-1 to R2-3, R3-1 to R3-3, R4-1 to R4-3, and R5-1 to R5-3 are batteries of comparative examples.

[0121] [evaluate]

[0122] (Internal resistance of the stored battery)

[0123] The aged batteries were stored at 70°C for 4 months. The internal resistance of the stored batteries was measured at 20°C.

[0124] (Low-temperature pulse discharge test of the stored battery)

[0125] The aged batteries were stored at 70°C for 4 months. After storage, the batteries were left to stand at -30°C for 2 hours. Then, they were subjected to a 1-second pulse discharge at 300mA at -30°C. The lowest voltage at this point was determined as the pulse discharge voltage.

[0126] The evaluation results are shown in Tables 1-13. In Tables 1-13, the internal resistance is expressed as a relative value when the internal resistance of battery B1-2 is set to 100. The pulse discharge voltage is expressed as a relative value when the pulse discharge voltage of battery B1-2 is set to 100. It should be noted that A7-1 to A7-3 in Table 13 are examples using oxides of two metals Me (a composite material in which the surface of manganese dioxide particles is covered by oxides of two metals Me).

[0127] [Table 1]

[0128]

[0129] [Table 2]

[0130]

[0131] [Table 3]

[0132]

[0133] [Table 4]

[0134]

[0135] [Table 5]

[0136]

[0137] [Table 6]

[0138]

[0139] [Table 7]

[0140]

[0141] [Table 8]

[0142]

[0143] [Table 9]

[0144]

[0145] [Table 10]

[0146]

[0147] [Table 11]

[0148]

[0149] [Table 12]

[0150]

[0151] [Table 13]

[0152]

[0153] Excellent storage characteristics were obtained in batteries A1-1 to A1-16, A2-1 to A2-16, A3-1 to A3-16, A3-1 to A3-16, A4-1 to A4-16, A5-1 to A5-16, and A6-1 to A6-16 (Tables 2 to 12).

[0154] In batteries R1-1 to R1-3, B1-1 to B1-7, B2-1 to B2-7, B3-1 to B3-7, B4-1 to B4-7, B5-1 to B5-7, and B6-1 to B6-7, the storage characteristics are reduced. In these batteries, negative electrodes with a Li content of less than 88% by mass or a Mg content outside the range of 0.01 to 10% by mass and / or positive electrodes with a Me oxide content outside the range of 0.1 to 5 parts by mass are used.

[0155] In batteries R2-1~R2-3, R3-1~R3-3, R4-1~R4-3, and R5-1~R5-3, the metallic Me has an ionic radius greater than 0.8 Å and / or an electronegativity greater than 1.65, resulting in reduced storage properties.

[0156] Comparing batteries R1-1 to R1-3 in Table 1, where no metal Me oxide was added, the increase in pulse discharge voltage after storage was smaller (88, 90 → 93) in battery R1-3, which used Li-Mg foil, compared to batteries R1-1 and R1-2, which used Li foil or Li-Al foil. On the other hand, comparing batteries B1-1, B1-2, and A1-1 in Table 2, where metal Me oxide was added and the metal Me was Mg, the increase in pulse discharge voltage after storage was significantly larger (98, 100 → 122) in battery A1-1, which used Li-Mg foil, compared to batteries B1-1 and B1-2, which used Li foil or Li-Al foil. The same trend was observed when the metal Me was Al, Ti, Zn, Zr, or Nb (Tables 2-3). These results indicate that a significant improvement in storage characteristics can be achieved by adding metal Me oxide to the positive electrode and using an alloy containing Li and Mg as the negative electrode.

[0157] Comparing batteries B1-1, B1-2, A1-1, and A1-2 in Table 2, where the metal Me is Mg, the increase in pulse discharge voltage after storage was smaller (98→100) in battery B1-2, which used Li-Al foil (Al content: 1% by mass), compared to battery B1-1, which used Li foil. On the other hand, in battery A1-1, which used Li-Mg foil (Mg content: 1% by mass), the pulse discharge voltage increased significantly as described above, and in battery A1-2, which used Li-Mg-Al foil (Mg content: 1% by mass, Al content: 1% by mass), the pulse discharge voltage increased even more significantly after storage (122→125). The same trend was observed when the metal Me was Al, Ti, Zn, Zr, or Nb (Tables 2-3).

[0158] Excellent storage characteristics were also obtained in batteries A7-1 to A7-3, which contain oxides of two metals Me (Table 13).

[0159] Industrial availability

[0160] The lithium primary battery of this application can be used as a main power source or memory backup power source for various instruments (such as smart meters for electricity, tap water, gas, etc.).

[0161] While the invention has been described with respect to preferred embodiments, this disclosure should not be interpreted as restrictive. Various modifications and alterations will be readily apparent to those skilled in the art upon reading the foregoing disclosure. Therefore, the scope of the appended claims should be interpreted as encompassing all modifications and alterations without departing from the true spirit and scope of the invention.

[0162] Explanation of reference numerals in the attached figures

[0163] 1. Positive electrode,

[0164] 1a Positive current collector,

[0165] 2. Negative electrode,

[0166] 3 spacers,

[0167] 4. Positive lead,

[0168] 5. Negative lead,

[0169] 6. Upper insulation board,

[0170] 7. Lower insulation board,

[0171] 8. Sealing board,

[0172] 9. Battery casing,

[0173] 10. Lithium primary 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. The positive electrode mixture contains manganese dioxide and oxides of metals other than manganese (Me). The metal Me has a valence of 2 or higher, an ionic radius of less than 0.8 Å, and an electronegativity of less than 1.

65. The amount of the oxide of metal Me contained in the positive electrode mixture is 0.1 parts by mass and less than 5 parts by mass relative to 100 parts by mass of manganese dioxide contained in the positive electrode mixture. The negative electrode contains an alloy containing lithium and magnesium. The lithium content in the alloy is greater than 88% by mass. The magnesium content in the alloy is 0.01% by mass or more and 10% by mass or less.

2. The lithium primary battery according to claim 1, wherein, The alloy contains aluminum. The total content of magnesium and aluminum in the alloy is more than 0.02% by mass and less than 10% by mass.

3. The lithium primary battery according to claim 1, wherein, The metal Me comprises at least one selected from magnesium, aluminum, titanium, zinc, zirconium, and niobium.

4. The lithium primary battery according to claim 1, wherein, The central particle size of the manganese dioxide is greater than 5 μm and less than 40 μm.

5. The lithium primary battery according to claim 1, wherein, The BET specific surface area of ​​the manganese dioxide is 5 m². 2 / g or more and 40m 2 / g or less.

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