Primary battery and communication device

Abstract

A primary battery with improved performance is provided. This primary battery includes: a negative electrode that contains lithium or a lithium alloy; a positive electrode that contains manganese dioxide (MnO2 ), carbon (C), and lithium fluoride (LiF); a separator that is provided between the negative electrode and the positive electrode; and an electrolyte solution.

Description

Primary batteries and communication equipment

[0001] This disclosure relates to a primary battery and a communication device equipped therewith.

[0002] Conventionally, the development of primary batteries has progressed, and various studies have been conducted on the configuration of such primary batteries. For example, Patent Document 1 discloses a primary battery comprising a positive electrode containing manganese dioxide, a negative electrode containing a lithium-based material, and an electrolyte containing an alkali metal compound and a dicarboxylic anhydride compound.

[0003] International Publication No. 2022 / 137667

[0004] Incidentally, various studies are being conducted to improve the performance of primary batteries. However, there is still room for improvement in the performance of primary batteries.

[0005] Therefore, primary batteries with superior performance are desired.

[0006] A primary battery according to one embodiment of the present disclosure comprises a negative electrode containing lithium or a lithium alloy, and manganese dioxide (MnO 2 The system comprises a positive electrode containing ), carbon (C), and lithium fluoride (LiF), a separator provided between the negative electrode and the positive electrode, and an electrolyte.

[0007] In one embodiment of the primary battery of this disclosure, lithium fluoride (LiF), which is a salt component in the electrolyte, is included in the positive electrode. Therefore, the formation of pathways for the movement of lithium ions, which are electrode reactants, is promoted within the positive electrode. As a result, in the primary battery of one embodiment of this disclosure, the diffusivity of lithium ions within the positive electrode is improved, and the heavy-load discharge characteristics are improved.

[0008] Furthermore, the effects of this disclosure are not necessarily limited to those described herein, but may include any of the effects of the series of effects related to this disclosure described later.

[0009] Figure 1 is a cross-sectional view showing an example of the overall configuration of a primary battery according to one embodiment of the present disclosure. Figure 2 is a cross-sectional view showing an example of the overall configuration of a primary battery as a first modification of the present disclosure. Figure 3 is a cross-sectional view showing an example of the overall configuration of a primary battery as a second modification of the present disclosure. Figure 4 is a cross-sectional view showing an example of the overall configuration of a primary battery as a third modification of the present disclosure. Figure 5 is a cross-sectional view showing an example of the overall configuration of a primary battery as a fourth modification of the present disclosure. Figure 6 is a block diagram showing the configuration of a smart meter equipped with a primary battery according to one embodiment of the present disclosure.

[0010] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. The order of description is as follows: 1. One Embodiment (Primary Battery) 1-1. Configuration 1-2. Manufacturing Method 1-3. Operation and Effects 2. Modifications 3. Applications of the Primary Battery 4. Examples

[0011] <<1. One Embodiment (Primary Battery)>> First, a primary battery according to one embodiment of the present disclosure will be described.

[0012] The primary battery described in this embodiment has a flattened three-dimensional shape. That is, the primary battery described below has a three-dimensional shape in which the outer diameter is greater than the height, and is referred to as a so-called coin-type primary battery. However, the primary battery of this disclosure is not limited to a coin-type primary battery, and may be a primary battery having an appearance different from that of a coin-type primary battery.

[0013] <1-1. Configuration> Figure 1 shows the cross-sectional configuration of the primary battery 1 of this embodiment. As shown in Figure 1, the primary battery 1 comprises a battery case 10, a gasket 20, a positive electrode 30, a negative electrode 40, a separator 50, a conductive layer 60, an aluminum-containing layer 70, and an electrolyte which is a liquid electrolyte. However, the electrolyte is not shown in Figure 1. The "outer diameter" mentioned above is the maximum dimension of the primary battery 1 in the horizontal direction in Figure 1, and the "height" mentioned above is the maximum dimension of the primary battery 1 in the vertical direction in Figure 1.

[0014] [Battery Can] The battery can 10 is a housing member that houses the positive electrode 30, the negative electrode 40, and the separator 50. Here, the battery can 10 has a container 11 and a lid member 12. The container 11 includes, for example, a bottom portion 11B having a disc-shaped appearance and a wall portion 11W having a substantially cylindrical appearance that is erected on the outer edge of the bottom portion 11B. The tip portion of the side wall portion 11W forms an opening 11K and may be curved toward the inside of the primary battery. Thus, the container 11 has a shape in which the lower end in the height direction is closed and the upper end in the height direction is open. The container 11 is indirectly connected to the positive electrode 30 via a conductive layer 60. Therefore, the container 11 also serves as a current collector for the positive electrode 30 and also as a terminal for external connection of the positive electrode 30, i.e., a positive electrode terminal. The container 11 contains one or more types of conductive materials such as metal materials. Specific examples of metal materials that make up the container 11 include, for example, aluminum (Al) and stainless steel. The type of stainless steel is not particularly limited, but specifically, examples include SUS316, SUS430, and SUS444. The container 11 may have a single-layer structure or a multi-layer structure. The surface of the container 11 may also be plated.

[0015] The lid member 12 includes, for example, a bottom portion 12B having a disc-like appearance, and a side wall portion 12W having a substantially cylindrical appearance that is erected on the outer edge of the bottom portion 12B. The tip portion of the side wall portion 12W forms an opening 12K. Thus, the lid member 12 has a shape in which the upper end in the height direction is closed and the lower end in the height direction is open. The lid member 12 is connected to the negative electrode 40. Therefore, the lid member 12 also serves as a current collector for the negative electrode 40, as well as a terminal for external connection of the negative electrode 40, i.e., a negative electrode terminal. Here, the lid member 12 covers the open upper end of the container 11 so as to close it. The inner diameter of the opening 12K of the lid member 12 is smaller than the inner diameter of the opening 11K of the container 11. Therefore, when the container 11 and the lid member 12 are arranged so that the openings 11K and 12K face each other, the lid member 12 is inserted into the inside of the container 11. The gap between the container 11 and the lid member 12 is sealed by a gasket 20. The lid member 12 contains one or more types of conductive materials, such as metal materials. The metal material constituting the lid member 12 can be the same type as the metal material constituting the container 11.

[0016] Here, the container 11 and the lid member 12 are crimped together via a gasket 20 when the lid member 12 is inserted into the container 11. In this case, the side wall portion 12W of the lid member 12 on the side facing the container 11 is folded back so as to approach the bottom portion 11B of the container 11 and then move away from the bottom portion 11B. With this structure, the battery can 10 is sealed with the positive electrode 30, negative electrode 40, separator 50, etc., housed inside.

[0017] [Gasket] The gasket 20 is interposed between the container 11 and the lid member 12 and is a ring-shaped sealing member that seals the gap between the container 11 and the lid member 12. The gasket 20 contains one or more types of polymer compounds. Specific examples of polymers include polypropylene (PP), polybutylene terephthalate (PBT), and nylon. Specific examples of polymer compounds include fluororesins such as perfluoroalkoxyalkanes (PFA) and polytetrafluoroethylene (PTFE). Further specific examples of polymer compounds include polyphenylene ether (PEE), polysulfone (PSF), polyalate (PAR), polyethersulfone (PES), polyphenylene sulfide (PPS), polyetheretherketone (PEEK), and polyetherimide (PEI). Among these, considering the sealing performance in high-temperature environments and the mass-producibility, i.e., moldability, of the gasket 20, any of PPS, PBT, and PEI is preferred, and PPS, which has excellent moisture resistance, is particularly preferred. However, the constituent materials of the gasket 20 are not limited to those mentioned above.

[0018] [Positive Electrode] The positive electrode 30 is a coin-shaped pellet, that is, a positive electrode mixture molded to be a coin-shaped pellet. The positive electrode 30 contains a positive electrode active material and may also contain a positive electrode binder and a positive electrode conductive agent.

[0019] The positive electrode active material is manganese dioxide (MnO ２ ) contains. This is because the operating voltage is higher compared to cases where the positive electrode active material contains iron sulfide and copper oxide, etc. Also, the load characteristics are improved compared to primary batteries that operate in almost the same voltage range, specifically primary batteries in which the positive electrode active material contains graphite fluoride, etc. Note that the positive electrode active material may contain multiple types of manganese dioxide having different crystallinity. The type of manganese dioxide is not particularly limited, but specifically, α-MnO ２ β-MnO ２ γ-MnO ２、 ε-MnO ２ These include, among others, β-MnO ２is preferable. This is because the highest theoretical capacity can be obtained. Note that manganese dioxide contains Mn as an impurity ２ O ３ and Mn ３ O ４ and the like. Although the specific surface area of manganese dioxide particles is not particularly limited, it is preferably 10 m ２ / g to 50 m ２ / g. This is because the reaction area of the manganese dioxide particles becomes appropriately large, which improves heavy-load characteristics and suppresses the decomposition reaction of the electrolyte solution in a high-temperature storage environment. Therefore, from the viewpoint of achieving both heavy-load characteristics and high-temperature storage characteristics, as described above, the specific surface area is 10 m ２ / g to 50 m ２ / g, which is effective. In addition, the positive electrode 30 may contain elemental boron. This is because elemental boron forms a film and suppresses the dissolution reaction of MnO ２ in a high-temperature storage environment. The positive electrode 30 preferably contains 0.3 µmol or more and 1.4 µmol or less of boron per 1 g. The positive electrode 30 more preferably contains 0.5 µmol or more and 1.2 µmol or less of boron per 1 g. This is because the impedance of the primary battery 1 can be reduced.

[0020] The positive electrode binder contains any one or two or more types of polymer compounds, and specific examples of the polymer compounds are fluorine-based polymer compounds such as polytetrafluoroethylene and polyvinylidene fluoride. When the positive electrode 30 contains the positive electrode binder, the moldability of the positive electrode 30 is improved. Although the content of the positive electrode binder in the positive electrode 30 is not particularly limited, it can be, for example, 1.4 mass% or more and less than 10 mass%. When the content of the positive electrode binder in the positive electrode 30 is 1.4 mass% or more and less than 10 mass%, excellent mechanical strength can be obtained while suppressing a decrease in discharge capacity. In addition, the positive electrode 30 may contain carboxylic acid. This is because the carboxylic acid forms a film and improves high-temperature storage characteristics. Although the carboxylic acid component is not limited, it is preferable that a carboxylic acid having a benzene ring is included. More preferably, pyromellitic anhydride is included.

[0021] The positive electrode conductive agent contains one or more types of conductive materials, such as carbon materials. The positive electrode conductive agent may also contain amorphous carbon as the carbon material. The amorphous carbon is preferably contained in the positive electrode 30 in an amount of 0.5% to 4% by weight. A content of 0.5% or more effectively contributes to improving heavy load performance by increasing conductivity, while a content of 4% or less avoids reducing the volume density of the positive electrode 30. Specific examples of carbon materials include carbon black, graphite, and graphene, and carbon fibers such as vapor-processed carbon fiber (VGCF) may also be used. The conductivity of the positive electrode 30 is improved by the inclusion of the positive electrode conductive agent. When the positive electrode 30 contains the positive electrode conductive agent (carbon material), the mixing ratio (weight ratio) of the positive electrode active material (manganese dioxide) and the positive electrode conductive agent is not particularly limited, but for example, the ratio of positive electrode active material to positive electrode conductive agent can be 90:10 to 97:3. With such a mixing ratio, excellent pulse discharge characteristics on the order of tens of mA can be obtained while ensuring electrical characteristics such as battery capacity.

[0022] The positive electrode 30 further contains lithium fluoride (LiF). The inclusion of lithium fluoride in the positive electrode 30 promotes the formation of pathways (i.e., ion paths) for the movement of lithium ions, which are the electrode reactants, within the positive electrode 30. As a result, the diffusivity of lithium ions within the positive electrode 30 is improved, and the heavy-load discharge characteristics of the primary battery in this embodiment are improved. The lithium fluoride content in the positive electrode 30 can be, for example, 100 ppm to 15,000 ppm. Such a lithium fluoride content can further improve the heavy-load discharge characteristics of the primary battery. Qualitative and quantitative analysis of the LiF contained in the positive electrode 30 can be performed using an NMR apparatus. For example, the positive electrode 30 can be immersed in heavy water, and the LiF extracted into the heavy water can be used as a sample for NMR measurement.

[0023] [Negative Electrode] The negative electrode 40 contains any one or two or more types of lithium-based materials. This is because a higher weight energy density allows the fabrication of a high-capacity primary battery, more specifically, a lithium primary battery. In order to improve the high-current characteristics of the primary battery in low-temperature environments, it is preferable to use two or more types of lithium-based materials. As described above, this "lithium-based material" is a general term for materials containing lithium as a constituent element. Therefore, the lithium-based material may be a simple substance of lithium, a lithium alloy, a lithium compound, or a mixture of two or more thereof. Specific examples of lithium alloys include lithium-aluminum alloy, lithium-tin alloy, lithium-silicon alloy, and lithium-nickel alloy. A specific example of a lithium compound is LiC 6 and the like. In the case where the lithium-based material is a lithium compound, the negative electrode 40 is a coin-shaped pellet, that is, it may be a negative electrode mixture molded into a coin-shaped pellet. In this case, the negative electrode 40 may contain a negative electrode binder. Details regarding the negative electrode binder are the same as those regarding the positive electrode binder.

[0024] [Separator] The separator 50 is interposed between the positive electrode 30 and the negative electrode 40. That is, the positive electrode 30 and the negative electrode 40 face each other via the separator 50. In the primary battery of this embodiment, the edge 50E of the separator 50 is configured to be sandwiched in the gap between the lid member 12 and the gasket 20. The separator 50 contains one or both of a porous membrane and a nonwoven fabric, and each of the porous membrane and the nonwoven fabric contains one or more polymer compounds such as polyethylene, polypropylene, methylpentene polymer, polybutylene terephthalate, and polyphenylene sulfide. The separator 50 may also contain one or more inorganic materials such as glass fiber and ceramic. Furthermore, the separator 50 may be a single layer or a multilayer. In addition, a surfactant or the like may be applied to the surface of the separator 50. Among these, the separator 50 is preferably a nonwoven fabric. This is because the separator 50 improves the electrolyte absorption capacity. The basis weight of the nonwoven fabric is 10 g / m². 2 ~100g / m 2 Furthermore, the thickness of the nonwoven fabric may be between 80 μm and 500 μm. When the basis weight and thickness of the nonwoven fabric are such that the electrolyte absorption capacity of the separator 50 is ensured, the occurrence of internal short circuits in the primary battery after high-temperature storage is suppressed.

[0025] [Conductive Layer] The conductive layer 60 is interposed between the positive electrode container 11 and the positive electrode 30. By providing the conductive layer 60 between the positive electrode container 11 and the positive electrode 30, pulse discharge characteristics on the order of tens of mA are improved. The conductive layer 60 contains one or more types of powdered conductive materials (multiple conductive particles), and specific examples of these conductive materials include silver and carbon materials.

[0026] [Electrolytic Solution] The electrolytic solution is impregnated into each of the positive electrode 30, the negative electrode 40, and the separator 50. The electrolytic solution contains a non-aqueous solvent (organic solvent) and an electrolyte salt that is a solute. As the non-aqueous solvent, for example, a high-boiling solvent, a low-boiling solvent, or a mixture of a high-boiling solvent and a low-boiling solvent can be used. Particularly from the viewpoint of electrical conductivity, it is preferable to use a cyclic carbonate as the high-boiling solvent and an ether compound as the low-viscosity solvent. As the cyclic carbonate, for example, at least one selected from the group consisting of ethylene carbonate, propylene carbonate, butylene carbonate and vinylene carbonate can be used. As the ether compound, for example, at least one selected from the group consisting of 1,2-dimethoxyethane (monoglyme), diglyme, triglyme, tetraglyme, methoxyethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, γ-butyrolactone and 1,3-dioxolane can be used. From the viewpoints of load characteristics and usable temperature range, it is preferable to use propylene carbonate and 1,2-dimethoxyethane as the non-aqueous solvent. The mass ratio of propylene carbonate to 1,2-dimethoxyethane (propylene carbonate:1,2-dimethoxyethane) is preferably 1:5 to 3:1. When the mass ratio of propylene carbonate to 1,2-dimethoxyethane falls within the above range, the pulse discharge characteristics on the order of several tens of mA can be particularly improved.

[0027] As the electrolyte salt, for example, lithium lower carboxylate, lithium halide, lithium nitrate, lithium perchlorate, lithium hexafluorophosphate, lithium borofluoride, lithium chloroboronate, lithium fluorine-containing alkylsulfonylimide, lithium hexafluoroarsenate, lithium hexafluoroantimonate, lithium tetraphenylborate, lithium bis(oxalato)borate, LiC n F 2n+1 SO 3 (n≧1), etc. These may be used alone, or two or more of these may be used in combination. Particularly from the viewpoints of cost, electrical conductivity and long-term reliability, it is preferable that the electrolyte salt contains at least lithium perchlorate.

[0028] The electrolyte may contain LiFSI (lithium bis(fluorosulfonyl)imide). The inclusion of LiFSI improves the conductivity of the electrolyte, which is expected to enhance battery performance. Furthermore, its excellent chemical stability contributes to improved operational reliability as a primary battery. Additionally, its excellent resistance to both high and low temperatures ensures stable operation of the primary battery in both high and low temperature environments. The LiFSI content of the electrolyte should ideally be between 0.5% and 20% by weight. A content of 0.5% or more effectively contributes to improved heavy-load performance by increasing conductivity, while a content of 20% or less avoids increasing the viscosity of the electrolyte, thus preventing a decrease in heavy-load performance. As an example of the LiFSI added here, Ionel (a registered trademark of Nippon Shokubai Co., Ltd.) LF-101 can be used.

[0029] The electrolyte may further contain carboxylic acid anhydrides or ester compounds to improve reliability after high-temperature storage. Preferred carboxylic acid anhydrides are those containing a benzene ring, and preferably include phthalic anhydride, pyromellitic anhydride, or mellitic anhydride. Benzene ring compounds are selected because they become carboxylic acids upon contact with moisture in the positive electrode. These carboxylic acids form a sterically hindered film or reduce the valence of MnO2, thereby strongly suppressing the electrolyte decomposition reaction under high-temperature storage conditions. In the case of ester compounds, it is preferable to add propanesultone or butanesultone, as sultones can exhibit the same function as carboxylic acids containing a benzene ring. The content should be adjusted to balance with heavy-load performance, preferably adding it to the electrolyte in a weight ratio of 0.1% to 3% when the total weight of the electrolyte is considered 100. If the amount added is too small, the decomposition reaction cannot be sufficiently suppressed, and if it is too large, MnO2 will decompose during the process of forming the positive electrode film. ２This is because reduction occurs, making it impossible to obtain sufficient heavy load performance. Note that carboxylic acid anhydrides and sulfonic acid esters having a benzene ring may be included in a mixture of each, and in addition to these, carboxylic acid anhydrides that do not have a benzene ring (for example, glutaric acid anhydride / maleic acid anhydride / succinic acid anhydride, etc.) may also be added.

[0030] The aluminum-containing layer 70 is provided between the negative electrode 40 and the separator 50. The aluminum-containing layer 70 contains, for example, an aluminum foil having a thickness of 1 μm to 15 μm. The aluminum-containing layer 70 is provided so as to be in contact with the surface of the negative electrode 40 that faces the positive electrode 30. A portion of the aluminum-containing layer 70 reacts with lithium to form a lithium-aluminum alloy layer. The presence of the aluminum-containing layer 70 sufficiently reduces the electrical resistance of the primary battery 1 and sufficiently improves electrical characteristics such as battery capacity. Specific examples of lithium-aluminum alloys include LiAl and Li 3 Al 2 Li 9 Al 4 Li 3 Al, Li 10 Al 90 and Li 5 Al 95 And so on.

[0031] <1-2. Manufacturing Method> The primary battery 1 of this embodiment can be manufactured, for example, by the procedure described below.

[0032] [Fabrication of the positive electrode] First, MnO ２ A positive electrode mixture is prepared by mixing a positive electrode active material containing MnO, a positive electrode binder, a positive electrode conductive agent containing carbon, and LiF. Then, a positive electrode mixture dispersion is prepared by mixing the prepared positive electrode mixture with a solvent. The solvent mixed with the positive electrode mixture may be an aqueous solvent or an organic solvent. However, MnO ２A mixture of aqueous solution and ethanol is preferred to improve dispersibility. Furthermore, to more homogeneously disperse LiF and the positive electrode binder, mixing is performed using a planetary desper for, for example, one hour. In addition, to improve the dispersibility of LiF and the positive electrode binder, it is desirable to mix a surfactant (for example, D-210C manufactured by Daikin Corporation) with LiF and the positive electrode binder. Subsequently, the prepared positive electrode mixture dispersion is heated to evaporate the solvent in the positive electrode mixture dispersion. Finally, the dried positive electrode mixture is pressure-molded using a tablet press. This produces a positive electrode 30, which is a molded body of the positive electrode mixture.

[0033] [Preparation of the negative electrode] Prepare lithium metal foil, which is elemental lithium, as the negative electrode 40.

[0034] [Preparation of Electrolyte] After adding the electrolyte salt to the solvent, the alkali metal compound and the dicarboxylic anhydride compound are added to the solvent. As a result, the electrolyte is prepared as the electrolyte salt, alkali metal compound and dicarboxylic anhydride compound are dispersed or dissolved in the solvent.

[0035] [Formation of the conductive layer] A conductive layer 60 is formed by applying a paste containing a conductive material to the inner bottom surface of the container 11. When silver is used as the conductive material, silver paste is used. When carbon is used as the conductive material, carbon paste is used.

[0036] [Assembly of the primary battery] First, the positive electrode 30 is placed inside the container 11, which has a conductive layer 60 formed on its inner bottom surface. This indirectly connects the positive electrode 30 to the container 11 via the conductive layer 60. Next, the negative electrode 40 is placed inside the lid member 12.

[0037] Next, a separator 50 impregnated with electrolyte is prepared, and then the positive electrode 30 housed inside the container 11 and the negative electrode 40 housed inside the lid member 12 are stacked on top of each other via the separator 50. In this case, the lid member 12 is inserted into the container 11 via a gasket 20. As a result, a portion of the electrolyte is impregnated into the positive electrode 30 and the negative electrode 40, respectively.

[0038] Finally, the battery can 10 is formed by crimping the container 11 and the lid member 12 via the gasket 20. This seals the positive electrode 30, negative electrode 40, separator 50, etc. inside the battery can 10, completing the primary battery 1.

[0039] <1-3. Function and Effects> In the primary battery 1 of this embodiment, the positive electrode 30 is MnO 2 The battery is configured to include carbon and LiF. This promotes the formation of pathways for the movement of lithium ions, which are electrode reactants, within the positive electrode 30. As a result, the primary battery 1 of this embodiment improves the diffusivity of lithium ions within the positive electrode 30, thereby improving the heavy-load discharge characteristics.

[0040] <<2. Modified Examples>> [Modified Example 1] Figure 1 illustrates a primary battery 1 having a conductive layer 60, in which the positive electrode 30 is indirectly connected to the container 11 via the conductive layer 60. However, in this disclosure, the conductive layer 60 is not required, as is the case with primary battery 1A as Modified Example 1 shown in Figure 2. In primary battery 1A, the positive electrode 30 is in direct contact with the bottom 11B of the container 11. In primary battery 1A shown in Figure 2, the positive electrode 30 is also MnO 2 It is configured to include carbon and LiF. Therefore, the primary battery 1A of Modification 1 (Figure 2) can be expected to have the same effects as the primary battery 1 of the above embodiment (Figure 1).

[0041] [Modification 2] In the primary battery 1 of Figure 1, the aluminum-containing layer 70 is provided between the negative electrode 40 and the separator 50. However, in this disclosure, the aluminum-containing layer 70 is not required, as in the primary battery 1B shown in Figure 3 as Modification 2. In the primary battery 1B shown in Figure 3, the positive electrode 30 is MnO 2 It is configured to include carbon and LiF. Therefore, the primary battery 1B of the modified example 2 (Figure 2) can be expected to have the same effects as the primary battery 1 of the above embodiment (Figure 1).

[0042] [Modification 3] The primary battery of the present disclosure may further include a positive electrode ring 80, as shown in Figure 4, for example, as primary battery 1C, modification 3. The positive electrode ring 80 is a ring-shaped member including, for example, a circular opening 80K, and is arranged to be in contact with both the positive electrode 30 and the conductive layer 60. The positive electrode 30 is in contact with the conductive layer 60 through the opening 80K of the positive electrode ring 80 while being supported by the positive electrode ring 80. The positive electrode ring 80 is made of a metal material such as stainless steel. Details regarding stainless steel are as described above. In Figure 4, the outer edge of the conductive layer 60 is shown to be located outside the outer edge of the positive electrode ring 80. However, the outer edge of the conductive layer 60 may be located inside the outer edge of the positive electrode ring 80. In that case, the positive electrode ring 80 may be fixed (welded) to the bottom 11B of the container 11. In this case as well, the positive electrode 30 is electrically connected to the container 11 via the conductive layer 60 by being adjacent to the conductive layer 60 via the positive electrode ring 80. In this case, the electrical connection between the positive electrode 30 and the container 11 is maintained more effectively, especially during discharge, thus suppressing a decrease in the so-called current collection effect. The positive electrode ring 80 may also be located between the bottom 11B of the container 11 and the conductive layer 60.

[0043] [Modification 4] In the primary battery 1 shown in Figure 1, the edge 50E of the separator 50 is configured to be sandwiched in the gap between the wall 12W of the lid member 12 and the gasket 20. However, in this disclosure, the edge 50E of the separator 50 may be terminated without being sandwiched between the wall 12W and the gasket 20, as shown in the primary battery 1D as Modification 4 in Figure 5. However, in the case of the primary battery 1D, the probability of a decrease in open-circuit voltage due to an internal short circuit may be higher compared to the primary battery 1 of the above embodiment.

[0044] <<3. Applications of Primary Batteries>> The primary batteries described above can be applied to a variety of uses. The applications of primary batteries are not particularly limited and can be selected arbitrarily. Here, we will explain the case in which primary batteries are applied to LPWA (Low Power Wide Area) communication equipment, which is an example of communication equipment.

[0045] Figure 6 shows the block configuration of a smart meter 100, which is an example of a communication device for LPWA. As shown in Figure 6, the smart meter 100 comprises a power supply board 101, a measurement circuit 102, a register board 103, and a communication interface board 104. The power supply board 101 includes the primary battery described above and supplies power to the measurement circuit 102, the register board 103, and the communication interface board 104. The measurement circuit 102 measures power consumption digitally. The register board 103 includes a microcontroller and memory, and executes software and security algorithms for setting charges, etc. Therefore, the smart meter 100 can realize a variety of functions that are difficult to realize with analog smart meters. The communication interface board 104 transmits information such as power consumption to power companies, relay devices, and base stations using the LPWA communication method. Therefore, unlike analog smart meters, the smart meter 100 can automate the monitoring of power consumption, etc., by communicating using the communication interface board 104.

[0046] The smart meter 100 is equipped with one of the primary batteries 1 according to the above-described embodiment or primary batteries 1A to 1C according to modified examples 1 to 3 on the power supply board 101. This improves the discharge characteristics of the smart meter 100 which employs an LPWA communication method.

[0047] <<4. Examples>> Examples of the present disclosure will be described below.

[0048] <Examples 1-1 to 1-6 and Comparative Example 1> A primary battery having the same configuration as the primary battery 1 described in the above embodiment was manufactured in the following manner, and its battery characteristics were evaluated.

[0049] [Manufacturing of Primary Batteries] A primary battery having the same configuration as primary battery 1 shown in Figure 1 was manufactured using the procedure described below.

[0050] (Preparation of the positive electrode) First, a positive electrode mixture was prepared by mixing MnO2 as the positive electrode active material, polytetrafluoroethylene (PTFE) as the positive electrode binder, natural graphite as the positive electrode conductive material, and LiF. In this case, β-MnO was used as the manganese dioxide. 2 In addition, the mixing ratio (by weight) of the positive electrode mixture was set to positive electrode active material: positive electrode binder: positive electrode conductive agent = 90:2:8. Furthermore, the LiF content in the positive electrode 30 was set to the values ​​shown in Table 1 below (75 ppm to 15200 ppm) by weight. However, in Comparative Example 1, LiF was not added when preparing the positive electrode mixture. Next, the positive electrode mixture was added to a mixture of aqueous solvent (pure water) and ethanol, and the aqueous solvent was stirred to prepare a positive electrode mixture dispersion. Subsequently, the positive electrode mixture dispersion was dried by heating (heating temperature = 180°C). Finally, the dried positive electrode mixture was pressure molded using a tablet press. This resulted in pellet-shaped positive electrodes (outer diameter = 14.0 mm, thickness = 1.82 mm, volume density = 2.90 g / cm³). 3 ) was created.

[0051] (Formation of conductive layer) Carbon paste was applied to the inner bottom surface of a container made of nickel-plated SUS430, and then the carbon paste was dried. This obtained a conductive layer containing carbon material.

[0052] (Fabrication of the negative electrode) A lithium metal foil with an outer diameter of 16.5 mm and a thickness of 0.84 mm was press-formed and attached to the inner bottom surface of a lid member made of nickel-plated SUS430. This resulted in obtaining a negative electrode containing elemental lithium.

[0053] (Preparation of electrolyte) Solvent (cyclic carbonate ester and dialkoxyalkane) and electrolyte salt (lithium perchlorate (LiClO) 4 The solvent was stirred by adding ( ). After that, the solvent was stirred by adding an alkali metal compound and a dicarboxylic anhydride compound. As a result, an electrolyte was prepared. Propylene carbonate (PC) was used as the cyclic carbonate ester, and dimethoxyethane (DME) was used as the dialkoxyalkane. The mixing ratio of propylene carbonate (PC) and dimethoxyethane (DME) was 1:1. The electrolyte salt in the electrolyte (LiClO) 4 The content (by weight) of ) was set at 6%. Furthermore, alkali metal compounds such as bis(fluorosulfonyl)imide lithium (LiFSI) were not added.

[0054] (Assembly of the primary battery) First, a separator (nonwoven fabric with a thickness of 190 μm) was placed on the negative electrode formed on the inner bottom surface of the lid member, and then a gasket (polyphenylene sulfide with a thickness of 0.37 mm) was placed on top of the separator. Next, the electrolyte prepared as described above was dropped onto the inside of the lid member from above the gasket, and then the positive electrode was placed on top of the gasket. As a result, a portion of the electrolyte was impregnated into the positive electrode, negative electrode, and separator, respectively. Finally, a container was placed on top of the positive electrode, and then the container and lid member were crimped together using a crimper. As a result, the battery can 10 was formed, and the positive electrode, negative electrode, separator, etc. were sealed inside the battery can, completing the primary battery (outer diameter = 20 mm and thickness = 3.2 mm). The open circuit voltage (OCV) was set to 3.25 V.

[0055] [Evaluation of Battery Characteristics] The battery characteristics of the primary battery prepared as described above were evaluated. Here, the discharge capacity value at a constant current of 5 mA (hereinafter simply referred to as the 5 mA discharge capacity value) was determined as a battery characteristic, and the results shown in Table 1 were obtained. Specifically, the 5 mA discharge capacity value was determined by the following procedure. First, a constant current of 5 mA was applied to the primary battery of Example 1-1 using the electrochemical measuring instrument "Squidstat plus" manufactured by Admiral Instrumental. Then, when the discharge voltage reached 1.8 V, the discharge was stopped. That is, a discharge voltage of 1.8 V was used as the cutoff condition. The time after the discharge was stopped was defined as T / hour, and the discharge capacity Q = 5T (mAh) was defined as the discharge capacity at a constant current of 5 mA.

[0056]

[0057] [Discussion] As shown in Table 1, the 5mA discharge capacity values ​​of the primary batteries in Examples 1-1 to 1-6 were higher than the 5mA discharge capacity value of the primary battery in Comparative Example 1. Therefore, the positive electrode is MnO 2 Furthermore, it was confirmed that by including LiF along with carbon, the diffusivity of lithium ions inside the positive electrode is improved, making it possible to improve the heavy-load discharge characteristics.

[0058] <Example 2-1> [Production of primary battery] LiFSI is further added to the electrolyte, and the LiClO contained in the electrolyte ４ Except for setting the content (by weight) of the active ingredient and the content (by weight) of LiFSI to the values ​​shown in Table 1, the primary battery of Example 2-1 was manufactured in the same manner as in Example 1-4. The 5mA discharge capacity value of the manufactured primary battery of Example 2-1 was also determined in the same manner as the primary battery of Example 1-4. The results are also shown in Table 1.

[0059] [Discussion] As shown in Table 1, the 5mA discharge capacity value of Example 2-1 was higher than that of Example 1-4. Therefore, it was confirmed that the conductivity of the electrolyte is improved by including an appropriate amount of LiFSI in the electrolyte.

[0060] <Example 3-1> [Manufacturing of Primary Battery] Except for adding amorphous carbon along with graphite as a positive electrode conductive agent to the positive electrode and setting the mixing ratio (weight ratio) of the positive electrode mixture to positive electrode active material: positive electrode binder: graphite: amorphous carbon = 90:2:6:2, the primary battery of Example 3-1 was manufactured in the same manner as in Example 2-1. The 5mA discharge capacity value of the manufactured primary battery of Example 3-1 was also determined in the same manner as the primary battery of Example 2-1. The results are also shown in Table 1.

[0061] [Discussion] As shown in Table 1, the 5mA discharge capacity value of Example 3-1 was even higher than the 5mA discharge capacity value of Example 2-1. Therefore, it was confirmed that the conductivity of the positive electrode is improved by including an appropriate amount of amorphous carbon in the positive electrode.

[0062] <Example 4-1> [Manufacturing of Primary Batteries] Five primary batteries of Example 4-1 were manufactured in the same manner as in Example 1-1, except that a primary battery with a structure in which the edge 50E of the separator 50 is terminated without being sandwiched between the wall 12W and the gasket 20, as shown in Figure 5 (Primary Battery 1D), was manufactured. The probability of open-circuit voltage (OCV) failure (ppm) occurring for the manufactured primary batteries of Example 4-1 was determined. Specifically, the probability of open-circuit voltage (OCV) failure was determined in the following manner. First, a 1MΩ resistor was connected to each of the five manufactured primary batteries, and the voltage was measured using a voltmeter. Next, primary batteries with an open-circuit voltage (OCV) of 3.05V or less were counted as primary batteries with open-circuit voltage (OCV) failure, and the probability of occurrence was calculated by dividing the number of failures by 5. For comparison, the probability of open-circuit voltage failure was also determined for the primary batteries of Example 3-1 in the same manner. The results are shown in Table 2.

[0063]

[0064] As shown in Table 2, the probability of OCV failure in Example 3-1 was kept significantly lower than that of Example 4-1. Therefore, it was confirmed that by configuring the separator 50's edge 50E to be sandwiched in the gap between the lid member 12 and the gasket 20, it is possible to effectively suppress, for example, conductive fine powder generated from the positive electrode from wrapping around the outer edge of the separator 50E and entering the negative electrode side.

[0065] <Examples 5-1 to 5-9> [Manufacturing of Primary Batteries] Boron was deposited on the positive electrode by using an electrolyte solution to which LiBOB (lithium bis(oxalate)boric acid) was further added, and by performing an aging treatment in which the batteries were stored at 70°C for 2 hours. Except for this point, the primary batteries of Examples 5-1 to 5-9 were manufactured in the same manner as in Example 3-1. The impedance of the manufactured primary batteries 5-1 to 5-9 was measured. In addition, the boron contained in the positive electrode of each of the manufactured primary batteries 5-1 to 5-9 was extracted in the following manner, and the boron content was determined as follows. Specifically, first, each primary battery was disassembled and the positive electrode was removed, and then the positive electrode was washed twice with a solvent (15 mL of DME). After that, the solvent was removed by heating in a vacuum oven at 40°C for 1 hour. Next, 50 g of distilled water was impregnated into the positive electrode, and the boron content in the distilled water was quantified using ICP-AES (inductively coupled plasma atomic emission spectroscopy). Subsequently, the boron content per unit weight of the positive electrode (μmol / g) was calculated. These results are shown in Table 3.

[0066]

[0067] As shown in Table 3, when the positive electrode contained boron in an amount of 0.3 μmol / g to 1.4 μmol / g (Examples 5-3 to 5-7), the impedance could be reduced compared to when it did not contain boron (Example 3-1). In particular, when the positive electrode contained boron in an amount of 0.5 μmol / g to 1.2 μmol / g (Examples 5-4 to 5-6), the impedance could be reduced even further.

[0068] Although the present disclosure has been described above with reference to one embodiment and one example, the configuration of the present disclosure is not limited to the configuration described in the one embodiment and one example, and can be modified in various ways.

[0069] Specifically, the case where the primary battery structure is coin-shaped was described. However, the primary battery structure is not particularly limited and may be button-shaped, cylindrical, or prismatic, etc. The effects described herein are merely illustrative, and therefore the effects of this disclosure are not limited to those described herein. Accordingly, other effects may be obtained with respect to this disclosure.

Claims

1. A negative electrode containing lithium or a lithium alloy, and manganese dioxide (MnO 2 A primary battery comprising a positive electrode containing ), carbon (C), and lithium fluoride (LiF), a separator provided between the negative electrode and the positive electrode, and an electrolyte.

2. The primary battery according to claim 1, wherein the lithium fluoride content in the positive electrode is 100 ppm or more and 15,000 ppm or less.

3. The primary battery according to claim 1 or claim 2, further comprising an aluminum-containing layer provided between the negative electrode and the separator.

4. The primary battery according to any one of claims 1 to 3, wherein the electrolyte comprises LiFSI.

5. The primary battery according to any one of claims 1 to 4, wherein the positive electrode comprises amorphous carbon.

6. The primary battery according to any one of claims 1 to 5, wherein the positive electrode contains boron.

7. The primary battery according to claim 6, wherein the positive electrode contains 0.3 μmol or more and 1.4 μmol or less of boron per gram.

8. The primary battery according to claim 6, wherein the positive electrode contains 0.5 μmol or more and 1.2 μmol or less of boron per gram.

9. A primary battery according to any one of claims 1 to 8, further comprising a container, a lid member, and a gasket for sealing the gap between the container and the lid member, wherein the edge of the separator is sandwiched in the gap between the lid member and the gasket.

10. A communication device comprising a primary battery according to any one of claims 1 to 9.

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