JP5407347B2 - Lithium primary battery - Google Patents

Description

  The present invention relates to a lithium primary battery using a negative electrode containing lithium or a lithium alloy as a negative electrode active material, and more particularly to improvement of pulse discharge characteristics in a low temperature environment in a lithium primary battery.

  Non-aqueous electrolyte batteries have high energy density, excellent reliability such as storage stability and leakage resistance, and can be reduced in size and weight. As a main power source for various electronic devices, power sources for memory backup, etc. The demand is constantly increasing. Among nonaqueous electrolyte batteries, a nonaqueous electrolyte lithium primary battery (hereinafter simply referred to as “lithium primary battery”) including a positive electrode and a negative electrode containing lithium or a lithium alloy as a negative electrode active material and a separator is widely used. Recently, it has been demanded that lithium primary batteries be used in more severe environments such as automobiles and industrial equipment, and at the same time, improvements for further higher performance are being promoted.

  For example, in a lithium battery, there is a problem that an electrochemically inactive compound such as lithium dendrite and other lithium compounds adheres to the surface of the negative electrode, thereby reducing the battery capacity. In order to prevent adhesion of an electrochemically inactive compound to the negative electrode, it has been proposed to provide a layer of carbonaceous powder on the surface of the negative electrode (see, for example, Patent Document 1).

In addition, a lithium primary battery including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte, in which carbon black is embedded in 10 to 50% of the area of the surface on the surface facing the positive electrode through the negative electrode separator is proposed. (For example, refer to Patent Document 2).
JP-A-11-135116 JP 2006-339046 A

  In Patent Document 1, an electrochemically inactive compound such as a lithium dendrite or other lithium compound adheres to the negative electrode surface by forming a carbonaceous powder layer in a state of biting into the negative electrode surface. It is possible to suppress. However, since lithium or lithium alloy having a very low potential is used for the negative electrode, the aprotic solvent used in the non-aqueous electrolyte solution is reduced and decomposed on the surface of the negative electrode. There is a possibility that decomposition products of the nonaqueous electrolytic solution are deposited and sufficient discharge characteristics cannot be obtained by covering the surface of the negative electrode. Particularly in a high temperature environment, reductive decomposition of the non-aqueous electrolyte is accelerated, so there is a problem in high temperature storage characteristics.

  Next, in Patent Document 2, the reduction in discharge characteristics caused by reductive decomposition of the nonaqueous electrolyte on the negative electrode surface is reduced by setting the carbon black embedded area in the range of 10 to 50% of the surface area of the negative electrode. It has been reported that a highly practical lithium primary battery excellent in characteristics and characteristics after high-temperature storage can be obtained. However, in Patent Document 2, it cannot be said that it is sufficient for applications such as automobiles and industrial equipment that are used in a severe environment at 100 ° C. or higher, and stored in a high temperature environment of 100 ° C. or higher as in Patent Document 1. As a result, decomposition products of the nonaqueous electrolytic solution may accumulate, and sufficient discharge characteristics may not be obtained.

  An object of the present invention is to provide a lithium primary battery excellent in pulse discharge characteristics in a low temperature environment even after being stored in a high temperature environment of 100 ° C. or higher.

To achieve the above object, the present invention provides a positive electrode containing a positive electrode active material, a negative electrode composed of lithium or a lithium alloy, a carbon layer formed on the surface of the negative electrode facing the positive electrode, A lithium primary battery comprising a solvent and a non-aqueous electrolyte comprising a lithium salt, wherein at least one compound selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate and derivatives thereof, and ethylene sulfite is non-aqueous. The electrolytic solution further contains.

  The lithium primary battery of the present invention can provide a lithium primary battery having stable discharge characteristics in a low temperature environment even after storage in a high temperature environment of 100 ° C. or higher.

  A first invention according to the present invention includes a positive electrode containing a positive electrode active material, a negative electrode composed of lithium or a lithium alloy, a carbon layer formed on a surface of the negative electrode facing the positive electrode, an aprotic solvent, A lithium primary battery comprising a non-aqueous electrolyte composed of a lithium salt. A compound that is reduced at the potential of the negative electrode to form a film and suppresses the decomposition of the nonaqueous electrolyte on the surface of the carbon layer, thereby suppressing the decomposition product of the nonaqueous electrolyte on the surface of the carbon layer. Is further contained. With this configuration, it is possible to obtain a lithium primary battery that has stable pulse discharge characteristics at a high level in a low-temperature environment even after storage in a high-temperature environment of 100 ° C. or higher compared to a conventional lithium primary battery.

  A second invention according to the present invention is the lithium primary battery according to the first invention, wherein the compound is vinylene carbonate (VC), vinyl ethylene carbonate (VEC) or a mixture thereof. By using these compounds in the above-described compounds, a lithium primary battery having a stable pulse discharge characteristic at a higher level in a low temperature environment even after storage in a high temperature environment of 100 ° C. or more can be obtained with a small amount of addition.

  A third invention according to the present invention is the lithium primary battery according to the first or second invention, wherein the carbon powder forming the carbon layer is carbon black. The use of carbon black, which is amorphous carbon, in the carbon layer is preferable because resistance when lithium ions move through the carbon layer is reduced, and the pulse discharge characteristics in a low temperature environment are stabilized at a higher level.

  According to a fourth aspect of the present invention, there is provided a positive electrode containing a positive electrode active material, a negative electrode composed of lithium or a lithium alloy, a carbon layer formed on a surface of the negative electrode facing the positive electrode, an aprotic solvent, A lithium primary battery comprising a non-aqueous electrolyte composed of a lithium salt. And before or at the time of battery construction, it is reduced at the potential of the negative electrode to form a film, and the decomposition of the non-aqueous electrolyte on the surface of the carbon layer is suppressed, so that the decomposition product of the non-aqueous electrolyte is It is characterized in that a non-aqueous electrolyte contains a compound that suppresses deposition in the aqueous solution.

  According to a fifth aspect of the present invention, there is provided a lithium primary battery according to the fourth aspect of the invention, wherein the compound is used in a nonaqueous electrolyte solution in the range of 0.1% by mass to 15% by mass. By containing and using the above compound in this range, not only the pulse discharge characteristics in a low temperature environment are stabilized at a higher level even after storage in a high temperature environment of 100 ° C. or higher, but also low temperature before storage. It is possible to obtain a lithium primary battery having a higher level of pulse discharge characteristics and a stable environment.

  A sixth invention according to the present invention is the lithium primary battery according to the fourth or fifth invention, wherein the compound is vinylene carbonate (VC), vinyl ethylene carbonate (VEC) or a mixture thereof. By using these compounds in the above-described compounds, a lithium primary battery having a stable pulse discharge characteristic at a higher level in a low temperature environment even after storage in a high temperature environment of 100 ° C. or more can be obtained with a small amount of addition.

  A seventh invention according to the present invention is the lithium primary battery according to the fourth to sixth inventions, wherein the carbon powder forming the carbon layer is carbon black. The use of carbon black, which is amorphous carbon, in the carbon layer is preferable because resistance when lithium ions move through the carbon layer is reduced, and the pulse discharge characteristics in a low temperature environment are stabilized at a higher level.

  Embodiments of the present invention will be described below. The embodiment described below is an example embodying the present invention, and does not limit the technical scope of the present invention.

  FIG. 1 is a longitudinal sectional view schematically showing a configuration of a lithium primary battery which is one embodiment of the present invention. This lithium primary battery has a coin shape and includes a negative electrode 1, a positive electrode 2, a separator 3, a negative electrode case 4, a positive electrode case 5, an insulating packing 6, a carbon layer 7, and a non-aqueous electrolyte (not shown). The carbon layer 7 is in pressure contact with the surface of the negative electrode 1. The separator 3 that holds the nonaqueous electrolytic solution is interposed between the negative electrode 1 and the positive electrode 2. The negative electrode 1, the positive electrode 2, and the separator 3 constitute a power generation element. The upper part of the positive electrode case 5 is open and accommodates this power generation element. An insulating packing 6 having an L-shaped cross-section is attached to the negative electrode case 4, the negative electrode case 4 is assembled in the positive electrode case 5, and then the opening of the positive electrode case 5 is crimped inward to seal the battery. Is done.

  The non-aqueous electrolyte contains an aprotic solvent such as γ-butyrolactone. Further, a lithium salt such as lithium borofluoride is dissolved as a solute. Further, a compound that is reduced at the potential of the negative electrode 1 to form a film is added to the non-aqueous electrolyte so as to have a predetermined ratio. This compound suppresses the decomposition of the nonaqueous electrolytic solution on the surface of the carbon layer, and suppresses the decomposition product of the nonaqueous electrolytic solution from being deposited on the surface of the carbon layer. With this configuration, it is possible to obtain a lithium primary battery that has stable pulse discharge characteristics at a high level in a low-temperature environment even after storage in a high-temperature environment of 100 ° C. or higher compared to a conventional lithium primary battery.

  Examples of such compounds include vinylene carbonate, vinyl ethylene carbonate, and derivatives thereof, which are cyclic carbonate compounds having an unsaturated bond, and more specifically vinylene carbonate (VC), 3-methyl vinylene carbonate, 3,4- Dimethyl vinylene carbonate, 3-ethyl vinylene carbonate, 3,4-diethyl vinylene carbonate, 3-propyl vinylene carbonate, 3,4-dipropyl vinylene carbonate, 3-phenyl vinylene carbonate, 3,4-diphenyl vinylene carbonate, vinyl ethylene carbonate (VEC). Moreover, ethylene sulfite etc. which are sulfur containing cyclic compounds are also mentioned. In particular, a small amount of VC or VEC can be added to obtain a lithium primary battery having a stable pulse discharge characteristic at a higher level in a low temperature environment even after storage in a high temperature environment of 100 ° C. or higher. Therefore, it is preferable to use these alone or as a mixture.

  In addition, it is preferable to use such a compound in a nonaqueous electrolytic solution in the range of 0.1% by mass or more and 15% by mass or less. By using it in this range, not only the pulse discharge characteristics in a low temperature environment are stabilized at a higher level even after storage in a high temperature environment of 100 ° C. or higher, but also in a low temperature environment before storage. A lithium primary battery having a higher level of pulse discharge characteristics and a stable level can be obtained.

  Conventionally, techniques for applying VC, VEC, and the like to lithium ion secondary batteries have been proposed. In a lithium ion secondary battery using a carbon material as a negative electrode, lithium ions solvated during charging are inserted into the carbon material. At that time, delamination of the carbon material occurs, causing irreversible loss of capacity. VC and VEC are added to prevent insertion of solvated lithium ions by forming a film on the surface of the carbon material and to reduce peeling of the carbon material. On the other hand, in the present embodiment, the coating caused by VC or VEC suppresses the decomposition of the nonaqueous electrolytic solution on the surface of the carbon layer 7 formed on the surface of the metallic lithium that is the negative electrode 1. As a result, the decomposition of the non-aqueous electrolyte proceeds and the product is prevented from depositing on the surface of the carbon layer 7. These purposes are therefore completely different.

  The positive electrode 2 includes a positive electrode active material, a conductive material, and a binder, and is provided to face the negative electrode 1 with the separator 3 interposed therebetween.

As the positive electrode active material, those commonly used in the field of lithium primary batteries can be used, and among them, fluorinated graphite, metal oxides and the like are preferable. As the fluorinated graphite, those represented by the chemical formula CF _x (0.8 ≦ x ≦ 1.1) are preferable. Fluorinated graphite is excellent in terms of long-term reliability, safety, and high-temperature stability. Fluorinated graphite is obtained by fluorinating petroleum coke, artificial graphite and the like. Examples of the metal oxide include manganese dioxide and copper oxide. A positive electrode active material can be used individually by 1 type or in combination of 2 or more types.

  As the conductive material, those commonly used in the field of lithium primary batteries can be used. For example, carbon black such as acetylene black and ketjen black, and graphite such as artificial graphite can be used. A conductive material can be used individually by 1 type or in combination of 2 or more types.

  As the binder, those commonly used in the field of lithium primary batteries can be used. For example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), modified PVDF, tetrafluoroethylene-hexafluoropropylene copolymer Copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer Polymer (ETFE resin), vinylidene fluoride-pentafluoropropylene copolymer, propylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer (ECTFE), vinylidene fluoride-hexafluoropropylene Pyrene - fluororesin such as tetrafluoroethylene copolymer, styrene-butadiene rubber (SBR), modified acrylonitrile rubber, ethylene - like acrylic acid copolymer. A binder can be used individually by 1 type or in combination of 2 or more types.

  The negative electrode 1 contains lithium or a lithium alloy, and is provided so as to face the positive electrode 2 with the separator 3 interposed therebetween. As the lithium alloy, those commonly used in the field of lithium primary batteries can be used, and examples thereof include Li—Al, Li—Sn, Li—NiSi, and Li—Pb.

  A carbon layer 7 is provided on the negative electrode surface 1 a of the negative electrode 1 facing the positive electrode 2 through the separator 3. The thickness of the carbon layer 7 is preferably 300 μm or less, more preferably in the range of 50 μm or more and 300 μm or less. By setting it within this range, a lithium primary battery having stable battery characteristics such as pulse discharge characteristics under a low temperature environment can be obtained. The carbon layer 7 is provided such that a part in the thickness direction is embedded in the negative electrode 1 and the other part protrudes outward from the negative electrode 1 from the negative electrode surface 1a. Alternatively, the entire carbon layer 7 may be embedded in the negative electrode 1, and the carbon layer 7 may be provided so that the surface of the carbon layer 7 and the negative electrode surface 1a form one plane. When contacting the electrolytic solution without using the carbon layer 7, a high resistance film is formed on the surface of the negative electrode 1 in a low temperature environment. However, by embedding part or all of the carbon layer 7 in the negative electrode 1 in this manner, the formation of a coating on the surface of the negative electrode 1 is suppressed, thereby improving the pulse discharge characteristics in a low temperature environment.

  The thickness of the carbon layer 7 was obtained by obtaining five cross sections in the thickness direction of the negative electrode 1 on which the carbon layer 7 was formed, and measuring the thickness of the carbon layer 7 at arbitrary five points for each cross section. The average value of the measured values was obtained. The cross section can be confirmed by a focused ion beam (FIB) processing observation apparatus. The FIB focuses an accelerated Ga (gallium) ion beam by an electrostatic lens system, scans the surface of the sample, detects the generated secondary electrons and secondary ions, and detects an image (SIM: Scanning Ion Microscope image). ).

  Further, the ratio (coverage) of the surface area of the carbon layer 7 to the area of the negative electrode surface 1a is preferably 80% or more and 100% or less, more preferably 90% or more and 100% or less as a percentage. As a result, a lithium primary battery having stable battery characteristics such as discharge characteristics under a low temperature environment can be obtained. The area of the negative electrode surface 1 a is the area of the surface of the negative electrode 1 that faces the positive electrode 2.

As the carbon forming the carbon layer 7, known carbon black can be used, and examples thereof include acetylene black, ketjen black, contact black, furnace black, and lamp black. Other carbons include graphite and graphite, but carbon black, which is amorphous carbon, has a lower resistance to lithium ions moving through the carbon layer and has a higher level of pulse discharge characteristics in a low temperature environment. Stabilize. Carbon black 16 can be used alone or in combination of two or more. The particle size of the carbon black is not particularly limited, but the average particle size (median diameter) of the primary particles is preferably 0.1 μm or less, more preferably 0.03 μm to 0 from the viewpoint of uniform distribution on the negative electrode surface 1a. .1 μm. Further, carbon black, from the viewpoint of reactivity with the electrolyte solution, preferably a BET specific surface area by nitrogen adsorption is ^{20 m} 2 / g or more, more preferably ^{50m 2} / ^g~100m 2 / g. Further, the carbon black is preferably dried with hot air at 150 ° C. to 250 ° C. or under reduced pressure before being pressed against the negative electrode surface 1a. By drying, volatile components adsorbed on the carbon black, adsorbed water, and the like are removed.

  Further, the method of placing the carbon black on the negative electrode surface 1a is not limited to placing the carbon black on the negative electrode surface 1a, and includes, for example, a method of stretching the carbon black on the negative electrode surface 1a using a roller press. . At this time, a carbon sheet on the negative electrode surface 1a may be covered with a polyethylene sheet, and the carbon black may be stretched over the entire surface of the negative electrode surface 1a by a roller press machine. Further, a method may be used in which a paste containing carbon black is prepared, this paste is applied, dried, and appropriately pressed with a roller press if necessary.

  As the separator 3, those commonly used in the field of lithium primary batteries can be used and are not particularly limited as long as they can prevent the positive electrode 2 and the negative electrode 1 from being short-circuited. Further, it is desirable that the non-aqueous electrolyte has excellent permeability and does not become an ion migration resistance. Typical materials include polyolefin, polyester, polycarbonate, polyacrylate, polymethacrylate, polyamide, polytetrafluoroethylene, polyvinylidene fluoride, polysulfone, polyethersulfone, polybenzimidazole, polyetheretherketone, polyphenylene, etc. Examples of the shape include a nonwoven fabric and a microporous film.

The nonaqueous electrolytic solution contains a solute and a nonaqueous solvent. As the solute, those commonly used in the field of lithium primary batteries can be used. For example, lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ) , Lithium-bispentafluoroethylsulfonic acid imide (LiN (SO ₂ C ₂ F ₅ ) ₂ ), lithium bis (trifluoromethylsulfonyl) imide (LiN (CF ₃ SO ₂ ) ₂ ), lithium tris (trifluoromethylsulfonyl) ) Methide (LiC (CF ₃ SO ₂ ) ₃ ), lithium perchlorate (LiClO ₄ ) and the like. Solutes can be used alone or in combination of two or more.

  As the non-aqueous solvent, those commonly used in the field of lithium primary batteries can be used. For example, γ-butyrolactone (γ-BL), γ-valerolactone (γ-VL), propylene carbonate (PC), ethylene carbonate ( EC), cyclic carbonates such as 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE), 1,3-dioxolane, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), N, N-dimethylformamide, tetrahydrofuran, 2-methyltetrahydrofuran, dimethylsulfoxide, formamide, acetamide, dimethylformamide, dioxolane, acetonitrile, propylnitrile, nitromethane, ethyl monoglyme, trimethoxyme Emissions, dioxolane derivatives, sulfolane, methyl sulfolane, propylene carbonate derivatives, tetrahydrofuran derivatives. A non-aqueous solvent can be used individually by 1 type or in combination of 2 or more types.

  The solute concentration in the nonaqueous electrolytic solution is not particularly limited, but is preferably 0.5 mol / L or more and 1.5 mol / L or less. If the solute concentration is less than 0.5 mol / L, the discharge characteristics at room temperature or the discharge characteristics after long-term storage may be deteriorated. When the solute concentration exceeds 1.5 mol / L, there is a possibility that the increase in viscosity and the decrease in ionic conductivity of the nonaqueous electrolytic solution become remarkable in a low temperature environment of about −40 ° C.

  The negative electrode case 4 also serves as a negative electrode current collector and a negative electrode terminal. The positive electrode case 5 also serves as a positive electrode current collector and a positive electrode terminal. The insulating packing 6 mainly insulates the negative electrode case 4 and the positive electrode case 5 from each other. As the negative electrode case 4, the positive electrode case 5, and the insulating packing 6, those commonly used in the field of lithium primary batteries can be used. For the negative electrode case 4 and the positive electrode case 5, for example, those made of stainless steel can be used. As the insulating packing 6, for example, a synthetic resin such as polypropylene can be used.

  The lithium primary battery can be manufactured, for example, as follows. First, the positive electrode 2 is accommodated in the positive electrode case 5 so as to be in contact with the inner surface of the positive electrode case 5, and the separator 3 is placed thereon. Further, a non-aqueous electrolyte is injected, and the positive electrode 2 and the separator 3 are impregnated with the non-aqueous electrolyte. On the other hand, the negative electrode 1 is pressure-bonded to the inner surface of the flat part of the negative electrode case 4, and the carbon layer 7 is formed on the negative electrode surface 1 a facing the positive electrode 2 of the negative electrode 1. Next, the negative electrode case 4 and the positive electrode case 5 are combined with the insulating packing 6 attached to the peripheral edge of the negative electrode case 4. At this time, the negative electrode surface 1 a on which the carbon layer 7 of the negative electrode 1 is formed is in contact with the separator 3. Furthermore, the coin-shaped lithium primary battery can be obtained by caulking and sealing the opening of the positive electrode case 5 inside. In addition, the above-mentioned compound may be mixed and used for a non-aqueous electrolyte before battery construction, or may be used for a non-aqueous electrolyte for battery construction.

  Although the coin-shaped lithium primary battery has been described in the present embodiment, the present invention is not limited to this. That is, cylindrical and rectangular lithium primary batteries are also included in the scope of the present invention.

  Examples and comparative examples are given below to specifically describe embodiments of the present invention.

Example 1
1) Preparation of positive electrode 100 parts by weight of fluorocarbon (positive electrode active material) and 10 parts by weight of acetylene black (conductive material) were dry-mixed, and methanol was added to the obtained dry mixture and kneaded. To this kneaded product, 5 parts by weight of styrene butadiene rubber (binder) was added and further kneaded, and the obtained kneaded product was dried and pulverized to prepare a powdered positive electrode mixture. 1.0 g of this positive electrode mixture was filled in a cylindrical mold having a diameter of 17.0 mm, and press-molded to produce a disk-shaped positive electrode 2.

2) Production of negative electrode Lithium metal was used as the negative electrode active material, and acetylene black (AB) manufactured by Denki Kagaku Kogyo Co., Ltd. was used as the carbon black. The average particle diameter of primary particles of acetylene black was 35 nm, and the BET specific surface area was 60 m ² / g. Acetylene black was vacuum dried at 200 ° C. and then introduced into an argon glove box.

  A 1.0 mm-thick lithium metal hoop was punched out to form a disc-shaped negative electrode 1, introduced into an argon glove box, and pressed against the inner surface of the flat part of the negative electrode case 4 on which the insulating packing 6 was mounted. Acetylene black 1.0 mg is placed on the surface of the negative electrode 1 and vibration and pressure are simultaneously applied at an amplitude of 5 μm and a pressure of 0.5 kN using an ultrasonic welder (trade name: SONOPET 302S, manufactured by Seidensha Electronics Co., Ltd.). did. The application time of vibration and pressure was 1.0 seconds. In this way, a carbon layer 7 having a thickness of 50 μm and a coverage of 100% was formed on the surface of the negative electrode 1. The coverage is obtained by observing the obtained negative electrode 1 with a microscope to determine the area of the portion shielded by acetylene black, and the ratio (= positive electrode area) of the area of the negative electrode 1 facing the positive electrode 2 (= positive electrode area) ( %).

3) Separator A polypropylene nonwoven fabric having a thickness of 200 μm was punched into a circular shape to produce a separator 3.

4) Preparation of Nonaqueous Electrolyte Solution As a solvent, γ-BL mixed with VC at a ratio of 0.1% by mass was used, and as a solute, lithium borofluoride dissolved at a ratio of 1 mol / L was used.

5) Battery assembly After placing the positive electrode 2 on the inner bottom surface of the positive electrode case 5 and covering the separator 3 thereon, 0.9 g of non-aqueous electrolyte was injected into the positive electrode case 5, The separator 3 was impregnated with a non-aqueous electrolyte. Next, the negative electrode case 4 to which the negative electrode 1 is pressure-bonded is attached to the positive electrode case 5 so that the negative electrode 1 and the positive electrode 2 face each other, and the peripheral edge of the positive electrode case 5 is attached to the negative electrode case 4. The coin-type lithium primary battery of the present invention (diameter 24.5 mm, thickness 5.0 mm) was produced. The battery had a diameter of 24.5 mm, a height of 5.0 mm, and a design capacity of 550 mAh. The assembly process was performed in dry air with a dew point of −50 ° C. or lower.

(Example 2)
A lithium primary battery of Example 2 was produced in the same manner as Example 1 except that VC was changed to a content of 0.5% by mass.

(Example 3)
A lithium primary battery of Example 3 was produced in the same manner as in Example 1 except that VC was changed to a content of 1.0% by mass.

Example 4
A lithium primary battery of Example 4 was produced in the same manner as in Example 1 except that VC was changed to a content of 5.0% by mass.

(Example 5)
A lithium primary battery of Example 5 was produced in the same manner as in Example 1 except that VC was changed to a content of 10.0% by mass.

(Example 6)
A lithium primary battery of Example 6 was produced in the same manner as in Example 1 except that VC was changed to a content of 15.0% by mass.

(Example 7)
A lithium primary battery of Example 7 was fabricated in the same manner as in Example 1 except that VEC was mixed at a content of 0.1% by mass instead of VC.

(Example 8)
A lithium primary battery of Example 8 was produced in the same manner as in Example 1 except that the VEC content was changed to 0.5% by mass.

Example 9
A lithium battery of Example 9 was produced in the same manner as Example 1 except that the VEC content was changed to 1.0% by mass.

(Example 10)
A lithium primary battery of Example 10 was produced in the same manner as in Example 1 except that the VEC content was changed to 5.0% by mass.

(Example 11)
A lithium primary battery of Example 11 was produced in the same manner as Example 1 except that the VEC content was changed to 10.0% by mass.

(Example 12)
A lithium primary battery of Example 12 was produced in the same manner as in Example 1 except that the VEC content was changed to 15.0% by mass.

(Example 13)
A lithium primary battery of Example 13 was produced in the same manner as in Example 1 except that VC was changed to a content of 0.05% by mass.

(Example 14)
A lithium primary battery of Example 14 was produced in the same manner as in Example 1 except that VC was changed to a content of 20.0% by mass.

(Example 15)
A lithium primary battery of Example 15 was made in the same manner as Example 1 except that the VEC content was changed to 0.05% by mass.

(Example 16)
A lithium primary battery of Example 16 was made in the same manner as Example 1 except that the VEC content was changed to 20.0% by mass.

(Example 17)
A lithium primary battery of Example 17 was produced in the same manner as in Example 1 except that VC and VEC were mixed at a content of 0.5% by mass in place of VC.

(Example 18)
A lithium primary battery of Example 18 was produced in the same manner as in Example 1 except that 3-methylvinylene carbonate (3-MVC) was mixed at a content of 1.0% by mass instead of VC.

(Example 19)
A lithium primary battery of Example 19 was made in the same manner as Example 1 except that ethylene sulfite (ES) was mixed at a content of 1.0% by mass instead of VC.

(Comparative Example 1)
A lithium primary battery of Comparative Example 1 was prepared in the same manner as in Example 1 except that only negative electrode 1 made of metallic lithium without carbon layer 7 and only γ-BL was used as the aprotic solvent of the non-aqueous electrolyte. Produced.

(Comparative Example 2)
A lithium primary battery of Comparative Example 2 was produced in the same manner as in Example 1 except that the negative electrode 1 made only of metallic lithium without forming the carbon layer 7 was used.

(Comparative Example 3)
A lithium primary battery of Comparative Example 3 was produced in the same manner as in Example 1 except that only γ-BL was used as the aprotic solvent of the nonaqueous electrolytic solution.

  First, for each of the 20 lithium primary batteries obtained in Examples 1 to 19 and Comparative Examples 1 to 3, a discharge test in a low temperature environment was performed before storage in a high temperature environment, and the average value of the pulse voltage and Standard deviation (σ) was determined. A higher value is desirable for the average value, and the standard deviation (σ) is approximately the same as that of Comparative Example 1 that does not contain a compound that forms a film or Comparative Example 3 that does not form the carbon layer 7. Is desirable. The average value and standard deviation (σ) of the pulse voltage were measured at the minimum voltage at the 20th cycle under the conditions of test temperature: −40 ° C., pulse load: 3 mA · 1 second on / 59 seconds off, and cycle number: 20 cycles. did. The results are shown in (Table 1).

  In (Table 1), a significant improvement in pulse voltage was seen compared to Comparative Example 1 in which the carbon layer 7 was not formed in Examples 1 to 19. Note that, in Comparative Example 3 in which the carbon layer 7 is formed, the pulse voltage is similarly superior to that of Comparative Example 1. In Example 17, as well as other examples in which a compound that forms a film is used alone, a significant improvement in pulse voltage has been observed, so that an effect can be obtained even when mixed and used. I understand that.

  However, in Examples 14 and 16, although the pulse voltage is improved, the pulse voltage is slightly lower and the variation is larger than in the other examples. Therefore, the content of the compound that suppresses the decomposition of the nonaqueous electrolytic solution on the surface of the carbon layer 7 and suppresses the deposition of decomposition products on the surface of the carbon layer 7 is 15% by mass regardless of the type of the compound. It turns out that it is preferable to set it as the following ratios. Further, in Comparative Example 2, although a compound that suppresses the decomposition of the nonaqueous electrolytic solution on the surface of the carbon layer 7 and suppresses the deposition of decomposition products on the surface of the carbon layer is contained, Similar to Comparative Example 1 in which no compound was contained, no significant difference was observed in both pulse voltage and standard deviation. Therefore, the effect by such a compound was not recognized in the state before high temperature storage.

  Next, 20 lithium primary batteries obtained in Examples 1 to 19 and Comparative Examples 1 to 3 were each stored at 125 ° C. for 10 days, then subjected to a discharge test in a low temperature environment, and an average value and a standard of pulse voltage. Deviation (σ) was determined. A higher value is desirable for the average value, and a standard deviation (σ) is desirably a variation similar to that of Comparative Example 1 that does not contain a compound that forms a passive film. The average value and standard deviation (σ) of the pulse voltage were measured under the aforementioned conditions. The results are shown in (Table 2).

  In Table 2, a significant drop in the pulse voltage was observed when stored in a high temperature environment of 125 ° C. in Comparative Example 3. This is presumably because the nonaqueous electrolytic solution was reduced and decomposed by the carbon layer 7 formed on the surface of the negative electrode 1, and the decomposition product was deposited on the surface of the carbon layer 7, thereby reducing the discharge characteristics. . However, in Examples 1 to 19, it can be seen that the drop and variation in pulse voltage are greatly reduced as compared with Comparative Example 3. Therefore, in the case of using the negative electrode 1 in which the carbon layer 7 is formed on the negative electrode surface 1 a facing the positive electrode 2, the compound contained in the non-aqueous electrolyte is the non-aqueous electrolyte on the surface of the carbon layer 7. It is presumed that the decomposition is suppressed and the deposition of decomposition products on the surface of the carbon layer 7 is suppressed. As a result, it is surmised that the excessive decomposition of the non-aqueous electrolyte in a high temperature environment of 100 ° C. or higher is greatly suppressed. Moreover, in Example 13 and Example 15, since there are few addition amounts, an effect is small. Therefore, it is preferable that the addition amount of the compound that suppresses the decomposition of the nonaqueous electrolytic solution on the surface of the carbon layer 7 and suppresses the deposition of decomposition products on the surface of the carbon layer 7 is at least 0.1% by mass. Further, in Examples 18 and 19, since the pulse voltage is lower than those in Examples 3 and 9 having the same contents, VC, VEC, or its compounds are used as the compound for forming a film on the negative electrode 1. It is preferred to use a mixture.

  The lithium primary battery of the present invention can be used in the same applications as conventional lithium primary batteries. Examples thereof include main power sources for various electronic devices, transportation devices, industrial devices, and memory backup power sources. Especially suitable for high temperature environment.

1 is a longitudinal sectional view schematically showing the configuration of a lithium primary battery that is one embodiment of the present invention.

DESCRIPTION OF SYMBOLS 1 Negative electrode 1a Negative electrode surface 2 Positive electrode 3 Separator 4 Negative electrode case 5 Positive electrode case 6 Insulation packing 7 Carbon layer

Claims (7)

A positive electrode containing a positive electrode active material;
A negative electrode composed of lithium or a lithium alloy;
A carbon layer formed on a surface of the negative electrode facing the positive electrode;
A non-aqueous electrolyte containing an aprotic solvent and a lithium salt,
The lithium primary battery, wherein the non-aqueous electrolyte further includes at least one compound selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate and derivatives thereof, and ethylene sulfite . 2. The lithium primary battery according to claim 1, wherein the compound is vinylene carbonate, vinyl ethylene carbonate, or a mixture thereof. The lithium primary battery according to claim 1 or 2, wherein the carbon powder forming the carbon layer is carbon black. A positive electrode containing a positive electrode active material;
A negative electrode composed of lithium or a lithium alloy;
A carbon layer formed on a surface of the negative electrode facing the positive electrode;
A non-aqueous electrolyte containing an aprotic solvent and a lithium salt, and a lithium primary battery comprising:
Before or at the time of battery construction, characterized in that at least one compound selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate and derivatives thereof, and ethylene sulfite is contained in the non-aqueous electrolyte and used. Primary lithium battery. 5. The lithium primary battery according to claim 4, wherein the compound is used by being contained in the nonaqueous electrolytic solution in a range of 0.1 mass% or more and 15.0 mass% or less. 6. The lithium primary battery according to claim 4, wherein the compound is vinylene carbonate, vinyl ethylene carbonate, or a mixture thereof. The lithium primary battery according to any one of claims 4 to 6, wherein the carbon powder forming the carbon layer is carbon black.

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