Lithium primary battery

Abstract

This lithium primary battery is provided with a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte solution, and is characterized in that the positive electrode contains a positive electrode active material and a conductive material, the positive electrode active material contains manganese dioxide and / or graphite fluoride, and the conductive material contains carbon black. The carbon black contains 0.02-0.4 at% (inclusive) of a metal element, the negative electrode contains a lithium alloy, the lithium alloy contains magnesium, and the content of the magnesium in the lithium alloy is 0.01-11 mass% (inclusive).

Description

Technical Field

[0001] This invention 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. A wound electrode assembly for a lithium-ion primary battery is constructed by winding a strip-shaped positive electrode, a strip-shaped negative electrode, and a spacer positioned between the positive and negative electrodes into a spiral shape. The negative electrode may use sheet-like (foil-like) metallic lithium or a lithium alloy, for example.

[0003] Patent document 1 proposes "a lithium battery, characterized in that the negative electrode active material is composed of metallic lithium or a lithium-aluminum alloy, the positive electrode active material is composed of inorganic materials other than fluorinated carbon, the electrolyte is composed of a non-aqueous electrolyte, and the positive electrode active material further contains primary particles with a particle size of less than 25 nm and a specific surface area of ​​500 m²." 2 Acetylene black with a concentration of ≥ / g and metallic impurities of ≤500ppm.

[0004] Patent document 2 proposes "a lithium battery, characterized in that it comprises a positive electrode containing manganese dioxide as the positive electrode active material, a negative electrode containing at least one of lithium metal and lithium alloy as the negative electrode active material, a porous insulator disposed between the positive electrode and the negative electrode, and an organic electrolyte, wherein the organic electrolyte comprises 0.001 to 1% by weight of hydroxycarboxylic acid ester".

[0005] Patent document 2

[0034] states that "the negative electrode active material uses at least one of lithium metal and lithium alloy. For example, an alloy of lithium with at least one metal selected from aluminum, tin, magnesium, indium and calcium can be cited. The content of metals other than lithium in the lithium alloy is preferably 0.1 to 3% by weight."

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 62-188167

[0009] Patent Document 2: Japanese Patent Application Publication No. 2011-60655 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] Lithium-ion batteries are used in the power supply of devices such as AEDs (Automated External Defibrillators). In these cases, the lithium-ion battery is rapidly discharged with a large current after long-term storage. However, sometimes it is not possible to draw a sufficient large current from a lithium-ion battery after long-term storage.

[0012] To address this, it is believed that including carbon black as a conductive material in the positive electrode can improve discharge performance. However, the carbon black may contain residual metal elements used during manufacturing. It is argued that these metal elements in the carbon black can precipitate on the surface of lithium metal or lithium alloys used as the negative electrode, potentially leading to internal short circuits and a decrease in discharge capacity.

[0013] In addition, Patent Document 1 also states that if the metallic impurities in acetylene black are greater than 500 ppm, the inorganic matter in the positive electrode and the metallic impurities will form a local battery, and the probability of hindering the elementary reaction between lithium and inorganic matter will increase, resulting in a shorter battery life.

[0014] Methods for solving problems

[0015] One aspect of the present invention relates to a lithium primary battery comprising a positive electrode, a negative electrode, a spacer disposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte. The positive electrode comprises a positive electrode active material and a conductive material. The positive electrode active material comprises at least one of manganese dioxide and fluorinated graphite. The conductive material comprises carbon black, wherein the carbon black comprises 0.02 atomic% or more and 0.4 atomic% or less of a metallic element. The negative electrode comprises a lithium alloy, wherein the lithium alloy comprises magnesium, and the magnesium content in the lithium alloy is 0.01 wt% or more and 11 wt% or less.

[0016] Invention Effects

[0017] According to the present invention, sufficient discharge characteristics can be obtained when a primary lithium battery is discharged with a large current after storage.

[0018] 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

[0019] Figure 1 This is a schematic cross-sectional view of a primary lithium battery according to one embodiment of the present invention. Detailed Implementation

[0020] Hereinafter, embodiments of the present invention will be described by way of example; however, the present invention 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 the present invention can be obtained. 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 are shown for values ​​relating to specific physical properties, conditions, etc., any of the shown lower limits and any of the shown upper limits can be arbitrarily combined as long as the lower limit is not above the upper limit. When multiple materials are shown, one can be selected and used alone, or two or more can be used in combination.

[0021] Furthermore, this invention includes a combination of matters recited in two or more claims arbitrarily selected from the plurality of claims described in the appended claims. That is, as long as it does not create a technical contradiction, a combination of matters recited in two or more claims arbitrarily selected from the plurality of claims described in the appended claims is permissible.

[0022] The lithium primary battery according to embodiments of the present invention includes a positive electrode, a negative electrode, a spacer, and a non-aqueous electrolyte. The spacer is disposed between the positive and negative electrodes. The structure and shape of the lithium primary battery are not particularly limited. The lithium primary battery can be button-shaped, cylindrical, square, or flat.

[0023] A positive electrode, a negative electrode, and a spacer can form a wound electrode assembly. A wound electrode assembly is constructed by winding a strip-shaped positive electrode, a strip-shaped negative electrode, and a spacer positioned between the positive and negative electrodes into a spiral shape. Either a negative or a positive electrode can be placed on the outermost periphery of the electrode assembly. Similarly, either a negative or a positive electrode can be placed on the innermost periphery of the electrode assembly.

[0024] The positive electrode comprises a positive electrode active material and a conductive material. The positive electrode active material comprises at least one of manganese dioxide and fluorinated graphite. The conductive material comprises carbon black. The carbon black comprises 0.02 atomic% to 0.4 atomic% of a metallic element. The content of the metallic element in the carbon black may be 0.02 atomic% to 0.3 atomic% or 0.05 atomic% to 0.2 atomic%.

[0025] Here, the so-called metal element content in carbon black refers to the percentage (%) of the number of metal element atoms relative to the total number of carbon element atoms and metal element atoms in carbon black, which is 100%.

[0026] The content of metal elements in carbon black can be determined using inductively coupled plasma (ICP) luminescence spectrophotometry or atomic absorption spectrometry (AAS).

[0027] The metallic element is not particularly limited, and can be at least one selected from Fe, Sr, V, Ni, and Nb. Among them, Fe, which has high electronic conductivity and is inexpensive, is preferred. Fe can account for more than 50 atomic percent of the metallic element, and more specifically, more than 70 atomic percent or more than 90 atomic percent.

[0028] The metallic elements in carbon black facilitate contact between the carbon black's structural components. A higher content of metallic elements in carbon black enhances its electronic conductivity, which in turn improves the battery's discharge characteristics.

[0029] However, when carbon black with a high metal element content is used in positive electrode active materials such as manganese dioxide and fluorinated graphite, the metal elements may dissolve into the electrolyte due to the potential difference between them and the positive electrode active material. On the other hand, since lithium (Li) is the most negative (lowest) metal element, it is inherently prone to depositing metal elements present in the battery on the surface of lithium alloys. Therefore, it can be argued that the deposition of metal elements from carbon black on the surface of lithium alloys may be a cause of internal short circuits and a decrease in discharge capacity.

[0030] While the surface potential of lithium alloys can be increased by alloying them with other metallic elements, the solid solution state of the alloyed metals is not entirely uniform. Therefore, potential inhomogeneity (fluctuations in potential) occurs on the surface of lithium alloys. For example, lithium alloys containing aluminum (Al) tend to form a mixture of Li and Li-Al alloys, thus easily leading to potential inhomogeneity. Once this potential inhomogeneity occurs, it is difficult to suppress the precipitation of metallic elements.

[0031] On the other hand, the negative electrode of the present invention comprises a lithium alloy containing magnesium (Mg), wherein the Mg content in the lithium alloy is 0.01% by mass or more and 11% by mass or less. Since the lithium alloy containing Mg readily forms a uniform Li-Mg alloy, the potential at the alloy surface can be increased while maintaining a state where potential unevenness is not easily generated. Therefore, the precipitation of metal elements is less likely to occur on the surface of the negative electrode or lithium alloy of the present invention, and the improved discharge characteristics resulting from the increased electronic conductivity of carbon black can be obtained while suppressing the defects caused by the precipitation of metal elements. As a result, the discharge characteristics of the stored battery are significantly improved.

[0032] If the metal element content in carbon black is less than 0.02 atomic%, the effect of improving the electronic conductivity of carbon black cannot be fully achieved. Conversely, if the metal element content in carbon black is greater than 0.4 atomic%, the amount of non-aqueous electrolyte retained by the carbon black decreases, making it difficult to improve discharge characteristics.

[0033] If the Mg content in the lithium alloy is less than 0.01% by mass, the effect of Mg in suppressing the precipitation of metal elements cannot be fully obtained. Furthermore, if the Mg content in the lithium alloy is greater than 11% by mass, the activity of the lithium alloy decreases, the resistance of the negative electrode increases, and therefore it is difficult to improve the discharge characteristics.

[0034] From the viewpoint of further improving the effect of suppressing the precipitation of metal elements, the Mg content in the lithium alloy can be 0.02% by mass or more, or 0.05% by mass or more, preferably 0.1% by mass or more or 0.3% by mass or more. Furthermore, from the viewpoint of maintaining the high activity of the lithium alloy as much as possible and reducing the resistance of the negative electrode, the Mg content in the lithium alloy can be 7% by mass or less, or 5% by mass or less, or 2% by mass or less, preferably 1% by mass or less.

[0035] Lithium alloys containing Mg can be further enriched with Al. By incorporating Al into Mg-containing lithium alloys, the surface potential of the alloy is further increased. Even in Al-containing lithium alloys, the presence of Mg maintains a state where potential unevenness is less likely to occur. That is, the surface potential of the alloy can be further increased while maintaining a state where potential unevenness is less likely to occur. Therefore, the effect of suppressing the precipitation of metal elements is improved.

[0036] Al also promotes the formation of a low-resistivity film on the alloy surface. Therefore, by using a lithium alloy containing both Mg and Al, the output voltage can be increased compared to using a lithium alloy containing only Mg.

[0037] Hereinafter, lithium alloys containing Mg but not substantially Al will be referred to as "Li-Mg alloys". Additionally, lithium alloys containing both Mg and Al will be referred to as "Li-Mg-Al alloys". It should be noted that "substantially not containing Al" means that the Al content in the lithium alloy is less than the detection limit in compositional analysis (e.g., ICP emission spectrophotometry, atomic absorption spectrometry, etc.).

[0038] In the case of Li-Mg-Al alloys, the Al content in the lithium alloy is preferably 0.01% by mass or more and 3.0% by mass or less. If the Al content is 0.01% by mass or more, the surface potential of the alloy can be further enhanced. Furthermore, if the Al content is 3.0% by mass or less, the good processability of the lithium alloy can be maintained while simultaneously achieving the effect of further enhancing the surface potential. The Al content in the lithium alloy can also be 0.05% by mass or more, or 0.1% by mass or more. The Al content in the lithium alloy can also be 2.0% by mass or less, or 1.0% by mass or less.

[0039] In the case of Li-Mg-Al alloy, the total content of Mg and Al in the lithium alloy is preferably 0.01% by mass or more and 11.5% by mass or less, or it may be 0.02% by mass or more and 11.5% by mass or less, or it may be 0.03% by mass or more and 5.5% by mass or less, or it may be 0.11% by mass or more and 1.5% by mass or less, or it may be 0.2% by mass or more and 1.3% by mass or less.

[0040] The mass ratio of Mg to Al: Mg / Al can be, for example, greater than 0.2 and less than 50.

[0041] Lithium alloys may contain one or more metallic elements, other than Mg and Al, that can alloy with lithium. Examples of metallic elements that can alloy with lithium include Na, Ca, Sn, Ni, Pb, In, K, Fe, and Si, but there are no particular limitations. However, from the viewpoint of ensuring discharge capacity and stabilizing internal resistance, the overall content of metallic elements other than lithium in the lithium alloy is preferably 15% by mass or less or 11% by mass or less. That is, the content of Li in the lithium alloy used in the negative electrode is preferably 85% by mass or more or 89% by mass or more, and more preferably 95% by mass or more.

[0042] The composition of lithium alloys can be determined using inductively coupled plasma (ICP) emission spectrophotometry or atomic absorption spectrometry (AAS).

[0043] The lithium primary battery of the present invention will now be described in more detail.

[0044] [Lithium primary battery]

[0045] (positive electrode)

[0046] The positive electrode contains at least one of manganese dioxide and fluorinated graphite as the positive electrode active material. Manganese dioxide has a high operating voltage and excellent output characteristics and discharge characteristics (pulse discharge characteristics). On the other hand, fluorinated graphite has excellent high-temperature characteristics and long-term reliability, and has a higher capacity than manganese dioxide.

[0047] Manganese dioxide can be electrolytically produced manganese dioxide. It can also exist in a mixed crystalline state containing multiple crystal states. The cathode can also contain manganese oxides other than manganese dioxide. As long as the main component of the manganese oxides in the cathode is manganese dioxide, the proportion of manganese dioxide in the manganese oxides can be 50% by mass or more, 70% by mass or more, or 90% by mass or more. Examples of manganese oxides other than manganese dioxide include MnO, Mn3O4, Mn2O3, and Mn2O7. The particle size D at 50% volume fraction in the volumetric cumulative particle size distribution of manganese dioxide is also considered. 50 For example, 20μm to 60μm.

[0048] Fluorinated graphite can be obtained, for example, by fluorinating a carbon material containing a graphite structure. Fluorination occurs when the carbon material is heated together with fluorine gas. The particle size D at 50% volume fraction in the volumetric particle size distribution of fluorinated graphite is... 50 For example, the thickness can be 10μm to 30μm. Fluorinated graphite can be used with (CF) x ) n It is expressed as follows. In the formula, x is, for example, 0.4≤x≤1.15, or it can be 0.5~1.1.

[0049] The positive electrode may contain a positive electrode compound, which includes a positive electrode active material and a conductive material as essential components, and a binder or the like as optional components.

[0050] As a conductive material, carbon black containing metallic elements, as described above, can be used. Conductive materials may also include materials other than carbon black that have electronic conductivity. Examples of such materials include natural graphite, synthetic graphite, and carbon fiber.

[0051] There are no particular limitations on the types of carbon black used; for example, acetylene black, channel black, furnace black, lampblack, pyrolytic carbon black, and graphitized carbon black can be used. They can be used alone or in combination of two or more types.

[0052] The carbon black content in the positive electrode is, for example, 1.0 part by mass or more and 10 parts by mass or less, preferably 3.0 part by mass or more and 6.0 parts by mass or less, relative to 100 parts by mass of the total positive electrode active material (i.e., manganese dioxide and / or fluorinated graphite).

[0053] Examples of binders include fluoropolymers such as polytetrafluoroethylene, rubber particles, and acrylic resins. The binder content in the positive electrode is, for example, 0.1 parts by mass or more and 10 parts by mass or less, preferably 3.0 parts by mass or more and 6.0 parts by mass or less, relative to 100 parts by mass of the total positive electrode active material (i.e., manganese dioxide and / or fluorinated graphite).

[0054] 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.

[0055] In the case of cylindrical batteries, 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 a wet positive electrode flux onto the surface of the sheet-like positive current collector or filling it into the positive current collector, pressing it along the thickness direction, and then drying it. In the case of button-shaped batteries, a positive electrode can be formed by mounting an L-shaped annular positive current collector onto positive electrode flux particles, or the positive electrode can be formed using only positive electrode flux particles. Positive electrode flux particles can be obtained, for example, by compressing a wet positive electrode flux and then drying it.

[0056] (negative electrode)

[0057] The negative electrode comprises the lithium alloy described above. The lithium alloy can be formed into any shape and thickness according to the shape, size, specifications, and performance of the primary lithium battery.

[0058] In the case of cylindrical batteries, foil-shaped (sheet-shaped) lithium alloy can be used as the negative electrode. Sheets, for example, can be obtained by extrusion molding. More specifically, for cylindrical batteries, lithium alloy foil with shapes having both length and width directions can be used. In the case of button-shaped batteries, lithium alloy foil can be punched into a button shape for use as the negative electrode.

[0059] Foil-shaped (sheet-shaped) lithium alloys can have a negative electrode current collector (e.g., copper foil) supporting them. On the other hand, when the lithium alloy contains Mg, the Mg, which has a high intensity at the end of discharge, may remain thinly in foil-shaped (sheet-shaped) form. Therefore, it is also possible to construct the negative electrode using only foil-shaped (sheet-shaped) lithium alloy without using a negative electrode current collector.

[0060] (Non-aqueous electrolyte)

[0061] Non-aqueous electrolytes contain non-aqueous solvents and lithium salts. The concentration of lithium ions (concentration of lithium salts) in the non-aqueous electrolyte is, for example, 0.2 mol / L or more and 2.0 mol / L or less, or 0.3 mol / L or more and 1.5 mol / L or less.

[0062] As non-aqueous solvents, examples of organic solvents commonly used in non-aqueous electrolytes for primary lithium batteries include ethers, esters, and carbonates. More specifically, dimethyl ether, γ-butyrolactone, propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, 1,2-dimethoxyethane (DME), 1,2-diethoxyethane, methyl acetate, ethyl acetate, and propyl acetate can be used. A single non-aqueous solvent can be used, or two or more can be used in combination.

[0063] From the viewpoint of improving the discharge characteristics of lithium primary batteries, the non-aqueous solvent preferably includes cyclic carbonates with high boiling points and chain ethers with low viscosity at low temperatures. The cyclic carbonate preferably includes at least one selected from PC and EC, with PC being particularly preferred. The chain ether preferably includes DME.

[0064] Examples of lithium salts used as solutes in primary lithium batteries include LiCF3SO3, LiClO4, LiBF4, LiPF6, LiRaSO3 (Ra being a fluoroalkyl group with 1 to 4 carbon atoms), LiFSO3, LiN(SO2Rb)(SO2Rc) (Rb and Rc being fluoroalkyl groups with 1 to 4 carbon atoms), LiN(FSO2)2, LiN(SO2CF3)2, LiN(SO2F)(POF2), LiPO2F2, LiB(C2O4)2, and LiBF2(C2O4). From the viewpoint of stability of lithium alloys containing Al and Mg, at least one of LiCF3SO3, LiBF4, and LiN(FSO2)2 is preferred. The non-aqueous electrolyte may contain one or more of these lithium salts.

[0065] Non-aqueous electrolytes may further contain additives. Examples of additives include propanesulfonate lactone, propylene sulfonate lactone, vinyl sulfite, 3,2-dioxane-2,2-dioxide, vinylene carbonate, ethylene ethylene carbonate, fluoroethylene carbonate, adiponitrile, succinic anhydride, and phthalic anhydride.

[0066] (spacer)

[0067] As a spacer sandwiched between the positive and negative electrodes, a porous sheet formed of an insulating material resistant to the internal environment of a lithium primary battery is sufficient. Specifically, examples include nonwoven fabrics made of synthetic resin, microporous membranes made of synthetic resin, or laminates thereof. The thickness of the spacer is, for example, 5 μm or more and 100 μm or less.

[0068] Examples of synthetic resins used in nonwoven fabrics include polypropylene, polyphenylene sulfide, and polybutylene terephthalate. Examples of synthetic resins used in microporous membranes include polyethylene, polypropylene, and polyolefin resins such as ethylene-propylene copolymer. Microporous membranes may contain inorganic particles as needed.

[0069] (Lithium primary battery)

[0070] Figure 1 The image shows a front view of a portion of a lithium primary battery according to one embodiment of the present invention, in cross-section. The battery case 9 of the lithium primary battery 10 houses a wound electrode assembly and a non-aqueous electrolyte. The electrode assembly is constructed by winding a strip-shaped positive electrode 1 and a strip-shaped negative electrode 2 in a spiral shape, separated by a spacer 3. A sealing plate 8 is installed at the opening of the battery case 9. The positive electrode 1 includes a positive current collector 1a and a positive electrode alloy layer supported on one or both sides of the positive current collector 1a. The positive current collector 1a is connected to the sealing plate 8 via a positive electrode lead 4. The negative electrode 2 includes at least a foil-shaped (or sheet-shaped) negative electrode alloy. The negative electrode 2 is connected to the battery case 9 via a negative electrode lead 5. Furthermore, an upper insulating plate 6 and a lower insulating plate 7 are respectively provided at the upper and lower parts of the electrode assembly to prevent internal short circuits.

[0071] Postscript

[0072] Based on the description of the above embodiments, the following technology is disclosed.

[0073] (Technology 1)

[0074] A primary lithium battery includes a positive electrode, a negative electrode, a spacer disposed between the positive and negative electrodes, and a non-aqueous electrolyte.

[0075] The aforementioned positive electrode comprises a positive electrode active material and a conductive material.

[0076] The aforementioned positive electrode active material includes at least one of manganese dioxide and fluorinated graphite.

[0077] The aforementioned conductive material includes carbon black.

[0078] The aforementioned carbon black contains 0.02 atomic% to 0.4 atomic% of metallic elements.

[0079] The aforementioned negative electrode contains a lithium alloy.

[0080] The aforementioned lithium alloy contains magnesium.

[0081] The magnesium content in the aforementioned lithium alloy is 0.01% by mass or more and 11% by mass or less.

[0082] (Technology 2)

[0083] According to the lithium primary battery described in Technology 1, the content of magnesium in the lithium alloy is 0.1% by mass or more and 1% by mass or less.

[0084] (Technology 3)

[0085] According to the lithium primary battery described in technology 1 or 2, the aforementioned lithium alloy further comprises aluminum.

[0086] The aluminum content in the aforementioned lithium alloy is 0.01% by mass or more and 3.0% by mass or less.

[0087] The total content of the aforementioned magnesium and aluminum in the lithium alloy is 0.01% by mass or more and 11.5% by mass or less.

[0088] (Technology 4)

[0089] According to any one of the technologies 1 to 3, the lithium primary battery contains at least one metal element selected from Fe, Sr, V, Ni and Nb.

[0090] Example

[0091] The present invention will now be described in detail based on embodiments and comparative examples; however, the present invention is not limited to the following embodiments.

[0092] Examples 1-12 and Comparative Examples 1-23

[0093] (Synthesis of carbon black)

[0094] Carbon black is obtained by incomplete combustion of the raw oil. Then, an aqueous solution containing a specified amount of iron ions is added to the carbon black and the mixture is treated at 1200K to synthesize carbon black (CB1–CB5) containing iron (Fe) as a metallic element. Specifically, the carbon black contains Fe at the rates shown in Table 1. It should be noted that the Fe content in the carbon black is quantified by ICP-N (Inductively Coupled Plasma) spectral analysis of the filtrate obtained by dissolving the synthesized carbon black in aqua regia and filtering it.

[0095]

[0096] (The production of the positive electrode)

[0097] To 100 parts by mass of the positive electrode active material, 5 parts by mass of the aforementioned carbon black as a conductive material, 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. Electrolytic manganese dioxide is used as the positive electrode active material.

[0098] Next, the positive electrode filler was filled into a positive electrode current collector made of 0.1mm thick stainless steel mesh to create the positive electrode precursor. After drying, the positive electrode precursor was rolled using a roller press and cut into strips to obtain the positive electrode. Then, a portion of the filled positive electrode filler was peeled off, and a stainless steel positive electrode lead was resistance-welded to one end of the exposed portion of the positive electrode current collector. The theoretical capacity of the positive electrode was set at 1600mAh.

[0099] (Making the negative electrode)

[0100] The following lithium metal foil and lithium alloy foil are prepared as negative electrodes. The theoretical capacity of the negative electrode is set at 1750mAh.

[0101] Negative electrode 1: Pure lithium foil

[0102] Negative electrode 2: A lithium alloy (Li-Al0.2) containing 0.2% by mass of Al but without Mg.

[0103] Negative electrode 3: A lithium alloy (Li-Mg0.01) containing no Al but 0.01% by mass of Mg.

[0104] Negative electrode 4: A lithium alloy (Li-Mg0.3) containing no Al but 0.3% Mg by mass.

[0105] Negative electrode 5: A lithium alloy (Li-Mg5) containing 5% by mass of Mg but no Al.

[0106] Negative electrode 6: A lithium alloy (Li-Mg11) containing 11% by mass of Mg but no Al.

[0107] Negative electrode 7: A lithium alloy (Li-Mg13) containing 13% by mass of Mg but no Al.

[0108] Nickel negative electrode leads are crimped to the ends of lithium alloy foil. Synthetic resin adhesive tape is then applied to the portion of the negative electrode lead excluding the front end.

[0109] (Fabrication of the electrode assembly)

[0110] Prepare strip-shaped spacers of specified dimensions. The spacers are made of a 25 μm thick polyethylene microporous membrane. The spacers are placed between the positive and negative electrodes using specified carbon black, wound into a spiral shape with the positive electrode on the inside. This process creates an electrode assembly with the negative electrode on the outermost periphery. It should be noted that the leading end of the negative electrode lead is exposed from one end face of the electrode assembly, and the leading end of the positive electrode lead is exposed from the other end face of the electrode assembly.

[0111] (Preparation of non-aqueous electrolyte)

[0112] A non-aqueous electrolyte was prepared by dissolving LiCF3SO3 at a concentration of 0.5 mol / L in a mixed solvent of PC, EC and DME (volume ratio 3:2:5).

[0113] (Assembly of primary lithium batteries)

[0114] The electrode assembly is housed in a cylindrical battery case that also serves as the negative terminal. The battery case is made of iron (17mm outer diameter, 33.5mm height). After injecting a non-aqueous electrolyte into the battery case, the opening is sealed using a metal sealing plate that also serves as the positive terminal. The other end of the positive lead is connected to the sealing plate, and the other end of the negative lead is connected to the inner bottom surface of the battery case. This is how a primary lithium battery is manufactured.

[0115] It should be noted that batteries A1 to A12 in Table 2 are batteries from Examples 1 to 12. Batteries B1 to B23 are batteries from Comparative Examples 1 to 23.

[0116]

[0117] Each battery of the obtained embodiments and comparative examples was aged for 2 days at 60°C after assembly, and then evaluated as follows.

[0118] [evaluate]

[0119] The aged batteries were stored at 60°C for one month, and then discharged at 20°C with a current of 1A until the voltage reached 1.5V. The discharge capacity was then measured. In this evaluation, the condition of discharging the long-term stored batteries with a large current is assumed. For each battery, the relative values ​​with the discharge capacity of battery B6 as 100 are shown in Table 2.

[0120] It can be concluded that in the batteries B1 to B5 of Comparative Examples 1 to 5 that used lithium foil and the batteries B6 to B10 of Comparative Examples 6 to 10 that used Li-Al0.2, the deposition of Fe on the negative electrode surface could not be suppressed, resulting in a decrease in discharge capacity.

[0121] It can be assumed that in batteries B19 to B23 of Comparative Examples 19 to 23 that use Li-Mg13, the discharge capacity is reduced because the activity of the negative electrode decreases and the internal resistance increases.

[0122] It can be assumed that in batteries B11, B13, B15, and B17 of Comparative Examples 11, 13, 15, and 17, the Fe content in the carbon black is too low, and no effect on improving the electronic conductivity of the positive electrode can be observed, and the discharge capacity does not increase.

[0123] It can be assumed that in batteries B12, B14, B16, and B18 of Comparative Examples 12, 14, 16, and 18, the discharge capacity is reduced because the Fe content in the carbon black is too high, which reduces the amount of non-aqueous electrolyte retained by the carbon black.

[0124] Examples 13-24 and Comparative Examples 24-31

[0125] Prepare the following lithium alloy foil as the negative electrode. The theoretical capacity of the negative electrode is set at 1750mAh.

[0126] Negative electrode 8: A lithium alloy containing 0.01% by mass of Al and 0.3% by mass of Mg (Li-Mg0.3-Al0.01)

[0127] Negative electrode 9: A lithium alloy containing 0.05% by mass Al and 0.3% by mass Mg (Li-Mg0.3-Al0.05)

[0128] Negative electrode 10: A lithium alloy containing 0.2% by mass Al and 0.3% by mass Mg (Li-Mg0.3-Al0.2)

[0129] Negative electrode 11: A lithium alloy (Li-Mg0.3-Al3) containing 3% by mass Al and 0.3% by mass Mg.

[0130] Except for changing the negative electrode to any of negative electrodes 8 to 12, batteries A13 to A24 of Examples 13 to 24 and batteries B24 to B31 of Comparative Examples 24 to 31 were manufactured in the same manner as batteries A1 to A5, and were evaluated in the same way. In each battery, the relative values ​​of the discharge capacity of battery B6 in Table 2 when it is 100 are shown in Table 3.

[0131]

[0132] The discharge capacity was further increased by including Al in the Mg-containing lithium alloy foil. This can be attributed to the increased potential at the alloy surface, which more significantly suppressed Fe deposition.

[0133] It should be noted that in Table 3, the content of Mg in the lithium alloy was fixed at 0.3% by mass. However, even when the content of Mg in the lithium alloy varied in the range of 0.01% by mass to 11% by mass, the effect of Al on improving the discharge characteristics was still observed.

[0134] Furthermore, carbon black containing Sr, V, Ni, and Nb at the aforementioned content levels, which replaced Fe, was synthesized, and the same evaluation confirmed that the same trend could be obtained.

[0135] Industrial availability

[0136] The lithium primary battery of the present invention can be used, for example, as a power source for AEDs (automated external defibrillators), a main power source for various instruments (such as smart meters for electricity, tap water, gas, etc.), and a memory backup power source.

[0137] 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.

[0138] Explanation of reference numerals in the attached figures

[0139] 1 Positive electrode, 1a Positive current collector, 2 Negative electrode, 3 Spacer, 4 Positive lead, 5 Negative lead, 6 Upper insulating plate, 7 Lower insulating plate, 8 Sealing plate, 9 Battery box, 10 Primary lithium battery.

Claims

1. A primary lithium battery, It comprises a positive electrode, a negative electrode, a spacer disposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte. The positive electrode comprises a positive electrode active material and a conductive material. The positive electrode active material includes at least one of manganese dioxide and fluorinated graphite. The conductive material includes carbon black. The carbon black contains 0.02 atomic% and less than 0.4 atomic% of metallic elements. The negative electrode contains a lithium alloy. The lithium alloy contains magnesium. The magnesium content in the lithium alloy is more than 0.01% by mass and less than 11% by mass.

2. The lithium primary battery according to claim 1, wherein, The magnesium content in the lithium alloy is more than 0.1% by mass and less than 1% by mass.

3. The lithium primary battery according to claim 1 or 2, wherein, The lithium alloy further comprises aluminum. The aluminum content in the lithium alloy is 0.01% by mass or more and 3.0% by mass or less. The total content of magnesium and aluminum in the lithium alloy is more than 0.01% by mass and less than 11.5% by mass.

4. The lithium primary battery according to claim 1 or 2, wherein, The metallic element includes at least one selected from Fe, Sr, V, Ni and Nb.

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