JP7079629B2 - Non-aqueous electrolyte secondary battery - Google Patents

Description

The present invention relates to a non-aqueous electrolyte secondary battery.

For coin-shaped non-aqueous electrolyte secondary batteries, reflow soldering is adopted to improve the efficiency of soldering when mounted on the circuit board. In order to have heat resistance in reflow soldering, various heat resistant members such as an electrolytic solution and a gasket are adopted in this type of secondary battery. Of these, for the electrolytic solution, a sulfone-based or grime-based solvent having a high boiling point is often used. For example, in the following Prior Art Document 1, by containing polyethylene glycol dialkyl ether and ethylene glycol dialkyl ether in a predetermined ratio as the solvent of the electrolytic solution, the heat resistance is high enough to withstand reflow soldering, and the discharge capacity is increased even in a low temperature environment. It has been shown to be maintained.

Japanese Unexamined Patent Publication No. 2011-060444

In such a reflow-compatible non-aqueous electrolyte secondary battery, a spinel-type lithium manganese oxide is used as the positive electrode active material, and a lithium-aluminum alloy is used as the negative electrode active material, whereby a high capacity can be obtained.
On the other hand, there is a demand for further increasing the capacity of such batteries. For example, it is conceivable to increase the amount of the negative electrode alloy or to use silicon oxide having a large theoretical capacity as the negative electrode active material. However, when the electrodes are changed in this way, it is necessary to ensure the stability of charge and discharge and suppress unexpected reactions of the electrodes and the electrolytic solution.

In view of these problems, it is an object of the present invention to improve the stability of a non-aqueous electrolyte secondary battery while having a small size and a high capacity and heat resistance to withstand reflow soldering.

"1" In order to solve the above-mentioned problems, the non-aqueous electrolyte secondary battery according to one embodiment of the present invention uses a positive electrode, a negative electrode, an electrolytic solution containing a supporting salt and a solvent, and a separator using a positive electrode can and a negative electrode can. A non-aqueous electrolyte secondary battery housed in a configured storage container, wherein the solvents are tetraglyme (TEG) and diethoxyethane (DEE), which are glyme-based solvents, ethylene carbonate (EC), and vinylene. Containing carbonate (VC), tetraglyme (TEG): 30% by mass or more and 48.5% by mass or less, diethoxyethane (DEE): 30% by mass or more and 48.5% by mass or less, ethylene carbonate (EC) : 0.5% by mass or more and 10% by mass or less, vinylene carbonate (VC): 2% by mass or more and 13% or less (total 100%) .

In this embodiment, since the glyme-based solvent containing tetraglyme or the like contains diethoxyethane, ethylene carbonate, and vinylene carbonate, heat resistance that can withstand heating during reflow soldering can be obtained, and deterioration of the electrode and the electrolytic solution is suppressed. It has the characteristics that can be.
If the solvent is a grime-based solvent mainly containing tetraglyme and diethoxyethane, the heat resistance can be enhanced due to the high boiling point of these solvents.
In the non-aqueous electrolyte secondary battery of this embodiment, since the glyme-based solvent containing tetraglyme contains an appropriate amount of vinylene carbonate, it has heat resistance that can withstand reflow soldering, and even if it is heated by reflow soldering. It is possible to provide a configuration in which the solvent is less likely to vaporize, the internal pressure of the accommodating container is less likely to increase, and the accommodating container is less likely to be deformed such as swelling.
Further, if the amount of vinylene carbonate added is within this range, the internal resistance of the non-aqueous electrolyte secondary battery can be reduced, so that the capacity can be increased and the swelling of the storage container can be suppressed, so that the electrodes and the electrolytic solution can be suppressed. It is possible to provide a non-aqueous electrolyte secondary battery that has not been deteriorated.

" 2 " In the non-aqueous electrolyte secondary battery of the above embodiment, the supporting salts are LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiN (CF ₃ SO ₃ ) ₂ , LiN (FSO ₂ ) ₂ organic acid lithium salt, or LiPF ₆ , LiBF ₄ , LiB (C ₆ H ₅ ) ₄ , It is preferably an inorganic acid lithium salt of either LiCl or LiBr.

In the non-aqueous electrolyte secondary battery of this embodiment, since the glyme-based solvent including tetraglyme and the like contains an appropriate amount of vinylene carbonate, it has heat resistance that can withstand reflow soldering, and it is assumed that it has been heated by reflow soldering. However, it is possible to provide a configuration in which the solvent is less likely to vaporize, the internal pressure of the accommodating container is less likely to increase, and the accommodating container is less likely to be deformed such as swelling. Further, if the amount of vinylene carbonate added is within this range, the internal resistance of the non-aqueous electrolyte secondary battery can be reduced, so that the capacity can be increased and the swelling of the storage container can be suppressed, so that the electrodes and the electrolytic solution can be suppressed. It is possible to provide a non-aqueous electrolyte secondary battery that has not been deteriorated.

" 3 " In the non-aqueous electrolyte secondary battery of the above embodiment, it is preferable that the solvent contains vinylene carbonate in an amount of 2.5% by mass or more and 10% by mass or less.

In the non-aqueous electrolyte secondary battery of this embodiment, since the glyme-based solvent containing tetraglyme and diethoxyethane contains a more preferable amount of vinylene carbonate of 2.5% by mass or more and 10% by mass or less, it can withstand reflow soldering. It has heat resistance to be obtained, and even if it is heated by reflow soldering, there is little possibility that the solvent is vaporized, there is little possibility that the internal pressure of the storage container rises, and it is possible to provide a configuration in which the storage container is hardly deformed. .. Further, if the amount of vinylene carbonate added is within this range, the internal resistance of the non-aqueous electrolyte secondary battery can be made smaller, so that the capacity can be increased and the swelling of the storage container can be further suppressed. It is possible to provide a non-aqueous electrolyte secondary battery in which the deterioration of the electrolytic solution is not caused.

" 4 " In the non-aqueous electrolyte secondary battery of the above embodiment, the positive electrode contains a lithium manganese oxide as a positive electrode active material, and the negative electrode contains a silicon oxide or a lithium aluminum alloy as a negative electrode active material. Is preferable.

Lithium manganese oxide can be used as the positive electrode active material, and silicon oxide or lithium aluminum alloy can be used as the negative electrode active material. A combination of a positive electrode active material of a lithium manganese oxide and a negative electrode active material of a lithium aluminum alloy can provide a high-capacity non-aqueous electrolyte secondary battery.

" 5 " In the non-aqueous electrolyte secondary battery of the above embodiment, the bottomed cylindrical positive electrode can and the positive electrode can are fixed with a gasket inside the opening of the positive electrode can to form a storage space between the positive electrode can and the positive electrode can. The storage container is sealed by providing a caulking portion for crimping the opening of the positive electrode can to the negative electrode can side, and the positive electrode, the negative electrode, the separator, and the electrolytic solution are stored in the storage container. Is preferable.

In the case of a structure in which the opening of the positive electrode can is crimped to the negative electrode can side to seal the storage container, a part of the solvent is vaporized by heating during reflow soldering depending on the component of the solvent stored inside, and the storage container The internal pressure may increase and the container may swell. If the above-mentioned glyme-based solvent contains an appropriate amount of vinylene carbonate, there is little possibility that the storage container will swell significantly even after heating by reflow soldering, and electrode deterioration after reflow soldering will not occur, and electrolysis will occur. It is possible to provide a non-aqueous electrolyte secondary battery in which deterioration of the liquid is unlikely to occur.

According to this embodiment, since the glyme-based solvent containing tetraglyme or the like contains diethoxyethane, ethylene carbonate, and vinylene carbonate, it can withstand heating during reflow soldering and can suppress deterioration of the electrode and the electrolytic solution. A water electrolyte secondary battery can be provided.

It is sectional drawing which shows the non-aqueous electrolyte secondary battery which concerns on 1st Embodiment. It is sectional drawing which shows the non-aqueous electrolyte secondary battery which concerns on 2nd Embodiment. The graph which shows the change amount of the battery thickness at the time of applying the heat treatment corresponding to the reflow soldering to the plurality of non-aqueous electrolyte secondary batteries constructed by using the plurality of solvents produced in the Example. The graph which shows the result of having measured the internal resistance (AC impedance) of a plurality of non-aqueous electrolyte secondary batteries configured by using the plurality of solvents prepared in the Example.

Hereinafter, an example of the non-aqueous electrolyte secondary battery according to the embodiment of the present invention will be given, and the configuration thereof will be described in detail with reference to FIGS. 1 and 2. The non-aqueous electrolyte secondary battery described in the present invention is a secondary battery in which an active material and a separator used as a positive electrode or a negative electrode are housed in a storage container. Further, in the drawings used in the following description, in order to make each member a recognizable size, the scale of each member is appropriately changed and displayed, so that the relative size of each member is limited to the form shown in the drawing. Of course not.

[First Embodiment of Non-Water Electrolyte Secondary Battery]
The non-aqueous electrolyte secondary battery 1 of the present embodiment shown in FIG. 1 is a so-called coin (button) type battery. The non-aqueous electrolyte secondary battery 1 includes a bottomed cylindrical positive electrode can 12, a covered cylindrical lid-shaped negative electrode can 22 that closes the opening of the positive electrode can 12, and a positive electrode can 12 along the inner peripheral surface of the positive electrode can 12. It has a provided gasket 40, and is provided with a thin (flat type) storage container 2 configured by caulking the peripheral edge of the opening of the positive electrode can 12 inward. A storage space surrounded by the positive electrode can 12 and the negative electrode can 22 is formed in the storage container 2, and the positive electrode 10 and the negative electrode 20 are arranged to face each other via the separator 30 in this storage space, and the electrolytic solution 50 is further filled. Has been done.
As the material of the positive electrode can 12, conventionally known materials are used, and examples thereof include stainless steel such as SUS316L, SUS329JL, and NAS64.
Examples of the material of the negative electrode can 22 include conventionally known stainless steel as in the material of the positive electrode can 12, and examples thereof include SUS316L, SUS329JL, and SUS304-BA.

(Positive electrode)
In the present embodiment, the positive electrode 10 is electrically connected to the inner surface of the positive electrode can 12 via the positive electrode current collector 14, and the negative electrode 20 is electrically connected to the inner surface of the negative electrode can 22 via the negative electrode current collector 24. .. The positive electrode current collector 14 and the negative electrode current collector 24 are abbreviated, and the positive electrode 10 may be directly connected to the positive electrode can 12 so that the positive electrode can 12 has the function of a current collector, and the negative electrode 12 is directly connected to the negative electrode. The negative electrode can 22 may be connected to the can 12 to have the function of a current collector.
The gasket 40 is connected to the outer periphery of the separator 30, and the gasket 40 holds the separator 30. The positive electrode 10, the negative electrode 20, and the separator 30 are impregnated with the electrolytic solution 50 filled in the storage container 2.

In the positive electrode 10, the type of the positive electrode active material is not particularly limited, but for example, it is preferable to use a positive electrode active material containing a lithium manganese oxide.
The content of the positive electrode active material in the positive electrode 10 is determined in consideration of the discharge capacity required for the non-aqueous electrolyte secondary battery 1 and the like, and can be in the range of 50 to 95% by mass. When the content of the positive electrode active material is not less than the lower limit of the above preferable range, a sufficient discharge capacity can be easily obtained, and when it is not more than the preferable upper limit, the positive electrode 10 can be easily formed.
The positive electrode 10 may contain a binder (hereinafter, the binder used for the positive electrode 10 may be referred to as a “positive electrode binder”).

Conventionally known substances can be used as the positive electrode binder, for example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), polyacrylic acid (PA), carboxymethyl cellulose (CMC). , Polyvinyl alcohol (PVA) and the like can be selected.
Further, as the positive electrode binder, one of the above may be used alone, or two or more of them may be used in combination. The content of the positive electrode binder in the positive electrode 10 can be, for example, 1 to 20% by mass.
As the positive electrode current collector 14, a conventionally known one can be used, and examples thereof include a conductive resin adhesive using carbon as a conductive filler.

Further, in the present embodiment, the positive electrode active material may contain other positive electrode active materials in addition to the above lithium manganese oxide, for example, molybdenum oxide, lithium iron phosphate compound, lithium cobalt oxide. , Lithium nickel oxide, vanadium oxide and the like may contain any one or more of other oxides.

(Negative electrode)
In the negative electrode 20, the type of the negative electrode active material is not particularly limited, but for example, it is preferable to contain a silicon oxide or an aluminum alloy as the negative electrode active material.
Further, in the negative electrode 20, it is preferable that the negative electrode active material is made of a silicon oxide represented by SiOx (0 ≦ x <2). In the negative electrode 20, a lithium aluminum alloy can also be used as the negative electrode active material. The structure when a lithium aluminum alloy is used as the negative electrode active material will be described in the second embodiment described later.

Further, the negative electrode 20 may contain another negative electrode active material in addition to the above SiO _X (0 ≦ x <2) as the negative electrode active material, for example, other negative electrode active materials such as Si and C. May be contained.
When granular SiO _X (0 ≦ x <2) is used as the negative electrode active material, these particle diameters (D50) are not particularly limited, and for example, a range of 0.1 to 30 μm can be selected. A range of up to 10 μm can be selected. When the particle size (D50) of SiO _X is less than the lower limit of the above range, for example, when the non-aqueous electrolyte secondary battery 1 is stored and used in a harsh high temperature and high humidity environment, or when the reactivity due to the reflow treatment is performed. The battery characteristics may be impaired, and if the upper limit is exceeded, the discharge rate may decrease.

The content of the negative electrode active material, that is, SiO _X (0 ≦ x <2) in the negative electrode 20, is determined in consideration of the discharge capacity required for the non-aqueous electrolyte secondary battery 1, and is 50% by mass or more. The range can be selected, and the range of 60 to 70% by mass can be selected.
In the negative electrode 20, if the content of the negative electrode active material composed of the above elements is at least the lower limit of the above range, a sufficient discharge capacity can be easily obtained, and if it is at least the upper limit, the negative electrode 20 can be easily molded. ..

The negative electrode 20 may contain a conductive auxiliary agent (hereinafter, the conductive auxiliary agent used for the negative electrode 20 may be referred to as a “negative electrode conductive auxiliary agent”). The negative electrode conductive auxiliary agent is the same as the positive electrode conductive auxiliary agent.
The negative electrode 20 may contain a binder (hereinafter, the binder used for the negative electrode 20 may be referred to as a “negative electrode binder”).
As the negative electrode binder, polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), polyacrylic acid (PA), carboxymethyl cellulose (CMC), polyimide (PI), polyimide amide (PAI) and the like can be selected.

Further, as the negative electrode binder, one of the above types may be used alone, or two or more types may be used in combination. When polyacrylic acid is used for the negative electrode binder, the pH of the polyacrylic acid can be adjusted to 3 to 10 in advance. For adjusting the pH in this case, for example, an alkali metal hydroxide such as lithium hydroxide or an alkaline earth metal hydroxide such as magnesium hydroxide can be used.
The content of the negative electrode binder in the negative electrode 20 is, for example, in the range of 1 to 20% by mass.

In this embodiment, the size and thickness of the negative electrode 20 can be formed in the same manner as the size and thickness of the positive electrode 10.
Further, in the non-aqueous electrolyte secondary battery 1 shown in FIG. 1, although not shown, a lithium body 60 such as a lithium foil is formed between the surface of the negative electrode 20, that is, between the negative electrode 20 and the separator 30 described later. It is possible to adopt a configuration provided with.

"Electrolytic solution"
The electrolytic solution 50 is usually obtained by dissolving the supporting salt in a non-aqueous solvent.
In the non-aqueous electrolyte secondary battery 1 of the present embodiment, the non-aqueous solvent forming the electrolytic solution 50 uses tetraglyme (TEG) as a main solvent, diethoxyethane (DEE) as a secondary solvent, and ethylene carbonate (EC). And vinylene carbonate (VC) are contained as an additive. The non-aqueous solvent is usually determined in consideration of the heat resistance, viscosity, etc. required for the electrolytic solution 50, but in this embodiment, the solvent consisting of each of the above solvents is used.
As the main solvent for forming the grime-based solvent, tetraglyme, triglyme, pentaglyme, diglyme and the like can be used.

In this embodiment, the electrolytic solution 50 using a non-aqueous solvent containing ethylene carbonate (EC), tetraglyme (TEG) and diethoxyethane (DEE) is adopted. By adopting such a configuration, DEE and TEG are solvated with Li ions forming the supporting salt.
At this time, since DEE has a higher donor number than TEG, DEE selectively solvates Li ions. In this way, DEE and TEG are solvated with the Li ions forming the supporting salt to protect the Li ions. As a result, even if water enters the inside of the non-aqueous electrolyte secondary battery in a high temperature and high humidity environment, it is possible to prevent the water from reacting with Li, so that the discharge capacity is reduced. The effect of suppressing and improving the storage characteristics can be obtained.

The ratio of each of the above solvents to the non-aqueous solvent in the electrolytic solution 50 is not particularly limited, but for example, TEG: 30% by mass or more and 48.5% by mass or less, DEE: 30% by mass or more and 48.5% by mass or less, EC. : 0.5% by mass or more and 10% by mass or less, VC: 2% by mass or more and 13% or less (total 100%) can be selected.
When the ratio of TEG, DEE and EC contained in the non-aqueous solvent is in the above range, the above-mentioned effect of solvating DEE to Li ions to protect Li ions can be obtained.
Even within the above range, the VC content is preferably in the range of 2.5% by mass or more and 10% by mass, and more preferably in the range of 5.0% by mass or more and 7.5% by mass. The upper limit of the contents of TEG and DEE is preferably 48.25% by mass or less, more preferably 48% by mass or less.
When the VC content is in the range of 2% by mass or more and 13% or less, the change in thickness that occurs in the storage container 2 composed of the positive electrode can 12 and the negative electrode can 22 is small even if it is heated during reflow soldering, and the internal resistance is small. Can be reduced. Further, when the VC content is in the range of 2.5% by mass or more and 10.0% by mass or less, the change in thickness that occurs in the storage container 2 can be made smaller even if it is heated during reflow soldering, and the internal resistance can be reduced. Can be less increased. Even within these ranges, the VC content is most preferably in the range of 5.0% by mass or more and 7.5% by mass or less.

As the supporting salt, a known Li compound used as a supporting salt in the electrolytic solution of the non-aqueous electrolyte secondary battery can be used, and for example, LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , LiN (CF 3 SO 2) 2, LiN (CF ₃ SO ₂ ) ₂ , Lithium organic acid salts such as LiN (C ₂ F ₅ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiN (CF ₃ SO ₃ ) ₂ , LiN (FSO ₂ ) ₂ ; LiPF ₆ , LiBF ₄ , LiB ( C ₆ H ₅ ) ₄ , Lithium salts such as inorganic acid lithium salts such as LiCl and LiBr, and the like can be mentioned. Among them, a lithium salt, which is a compound having lithium ion conductivity, is preferable, LiN (CF ₃ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , and LiBF ₄ are more preferable, and heat resistance and reactivity with water are low. LiN (CF ₃ SO ₂ ) ₂ is particularly preferable from the viewpoint of sufficiently exhibiting storage characteristics.
As the supporting salt, one of the above may be used alone, or two or more thereof may be used in combination.

The content of the supporting salt in the electrolytic solution 50 can be determined in consideration of the type of the supporting salt and the like. For example, 0.1 to 3.5 mol / L is preferable, 0.5 to 3 mol / L is more preferable, and 1 ~ 2.5 mol / L is particularly preferable. If the concentration of the supporting salt in the electrolytic solution 50 is too high or too low, the conductivity may be lowered and the battery characteristics may be adversely affected.

(Separator)
As the separator 30, an insulating film interposed between the positive electrode 10 and the negative electrode 20 and having a large ion transmittance and mechanical strength is used.
As the separator 30, those conventionally used for separators of non-aqueous electrolyte secondary batteries can be applied without any limitation. For example, alkaline glass, borosilicate glass, quartz glass, glass such as lead glass, polyphenylene sulfide (PPS), and the like. Examples thereof include non-woven fabrics made of resins such as polyetheretherketone (PEEK), polyethylene terephthalate (PET), polyamideimide (PAI), polyamide, and polyimide (PI). Among them, a non-woven fabric made of glass is preferable, and a non-woven fabric made of borosilicate glass is more preferable. Since the non-woven fabric made of glass has excellent mechanical strength and high ion permeability, it is possible to reduce the internal resistance and improve the discharge capacity.
The thickness of the separator 30 is determined in consideration of the size of the non-aqueous electrolyte secondary battery 1, the material of the separator 30, and the like, and can be, for example, 5 to 300 μm.

(gasket)
The gasket 40 is preferably made of, for example, a resin having a heat distortion temperature of 230 ° C. or higher. If the heat distortion temperature of the resin material used for the gasket 40 is 230 ° C. or higher, the gasket is significantly deformed due to reflow soldering treatment or heating during use of the non-aqueous electrolyte secondary battery 1 to prevent the electrolytic solution 50 from leaking. can.
As shown in FIG. 1, the gasket 40 is formed in an annular shape along the inner peripheral surface of the positive electrode can 12, and the outer peripheral end portion 22a of the negative electrode can 22 is arranged inside the annular groove 41.
The gasket 40 has a ring-shaped outer edge portion 40A having an outer diameter that is inserted without a gap on the inner peripheral side of the opening of the positive electrode can 12, a ring-shaped inner edge portion 40B, and the lower ends of the outer edge portion 40A and the inner edge portion 40B. It is composed of a bottom wall portion 40C to which the above is connected. Therefore, an annular groove 41 into which the outer peripheral end portion 22a of the negative electrode can 22 can be inserted is formed on the upper surface side of the outer peripheral edge of the gasket 40.
A storage container 2 having a structure in which the storage space is sealed by sandwiching the gasket 40 by crimping the peripheral edge portion 12b of the opening portion 12a of the positive electrode can 12 shown in FIG. 1 to the inside, that is, to the negative electrode can 22 side is configured.

Examples of the material of the gasket 40 as described above include polyphenyl sulfide (PPS), polyethylene terephthalate (PET), polyamide, liquid crystal polymer (LCP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA), and poly. Ether ether ketone resin (PEEK), polyether nitrile resin (PEN), polyether ketone resin (PEK), poly allylate resin, polybutylene terephthalate resin (PBT), polycyclohexanedimethylene terephthalate resin, polyether sulfone resin (PES) , Polyaminobismaleimide resin, polyetherimide resin, fluororesin and the like. Further, those to which glass fiber, mica whiskers, ceramic fine powder or the like are added in an addition amount of 30% by mass or less can be preferably used. By using such a material, the gasket is significantly deformed by heating, and it is possible to prevent the electrolytic solution 50 from leaking.

According to the non-aqueous electrolyte secondary battery 1 of the present embodiment described above, the non-aqueous solvent contains tetraglyme (TEG) and diethoxyethane (DEE) as main components, and ethylene carbonate (EC) and the above-mentioned appropriate amount range. Since the electrolytic solution 50 containing an appropriate amount of vinylene carbonate (VC) is provided, it has heat resistance that can withstand reflow soldering, and even if it is heated by reflow soldering, there is little risk of the solvent evaporating. It is possible to provide a configuration in which the internal pressure of the storage container 2 is unlikely to increase and the storage container 2 is unlikely to be deformed.
Further, if the solvent is a grime-based solvent mainly containing tetraglyme and diethoxyethane, the heat resistance of the electrolytic solution can be enhanced due to the high boiling point of these solvents.

"Second Embodiment of Non-Water Electrolyte Secondary Battery"
FIG. 2 shows the non-aqueous electrolyte secondary battery 11 of the second embodiment, and the non-aqueous electrolyte secondary battery 11 of this embodiment is a coin having a structure similar to that of the non-aqueous electrolyte secondary battery 1 of the first embodiment. It is a button) type battery. The non-aqueous electrolyte secondary battery 11 has a positive electrode can 12, a negative electrode can 25, and a gasket 42, and is a thin (flat type) storage container configured by crimping the peripheral edge of the opening of the positive electrode can 12 inward. It has the same structure as the non-aqueous electrolyte secondary battery 1 of the first embodiment in that it is provided with 2.
The negative electrode can 25 of the second embodiment is formed by laminating a stainless steel material and a hard aluminum material by rolling, and has a two-layer structure of an outer stainless steel layer 21 and an inner hard aluminum layer 23. ..

In the non-aqueous electrolyte secondary battery 11 of the second embodiment, the positive electrode 13 and the negative electrode 26 are arranged to face each other in the storage container 2 via the separator 30A, and the electrolytic solution 50 is filled in the closed space 16. The positive electrode 13, the negative electrode 26, and the separator 30A are impregnated with the electrolytic solution 50 filled in the storage container 2.
The positive electrode 13 is adhered to the inner bottom surface 10b of the positive electrode can 10 by a positive electrode current collector 14 made of a conductive resin adhesive containing carbon as a conductive filler, and a separator 30A is placed on the upper portion of the positive electrode 12. .. A negative electrode 26 is placed on the upper portion of the separator 30A, and the negative electrode 26 is crimped to the inner top surface 20b of the negative electrode can 25, that is, the hard aluminum layer 23.
As the positive electrode 13, a material equivalent to the material constituting the positive electrode 10 of the first embodiment can be applied.

Examples of the negative electrode 26 include a lithium foil (lithium foil), a lithium-aluminum alloy, carbon contacted or electrochemically doped with lithium, and the like.
The separator 30A is made of glass fiber, and examples thereof include glass non-woven fabrics such as borosilicate glass, quartz glass, and lead glass, and among them, borosilicate glass non-woven fabric is more preferable. Since the non-woven fabric made of borosilicate glass is excellent in mechanical strength and has a large ion permeability, it is possible to reduce the internal resistance and improve the discharge capacity.

The composition of the electrolytic solution 50 is the same as that of the electrolytic solution 50 of the first embodiment. An electrolytic solution containing tetraglyme (TEG) as a main solvent, diethoxyethane (DEE) as a secondary solvent, and vinyl carbonate (VC) as an additive in an appropriate amount in addition to ethylene carbonate (EC). The composition ratio of each component in the electrolytic solution 50 may be the same as that of the first embodiment.

Similar to the structure of the first embodiment, the structure of the second embodiment also has the heat resistance that can withstand reflow soldering because the electrolytic solution 50 containing the above-mentioned appropriate amount range of vinylene carbonate (VC) is provided. However, even if the solvent is heated due to reflow soldering, the solvent is less likely to vaporize, the internal pressure of the storage container 2 is less likely to increase, and the storage container 2 can be provided with a structure in which deformation is unlikely to occur.
In the structure of the second embodiment, a lithium foil (lithium foil) and a lithium-aluminum alloy are used as the negative electrode 25, so that the capacity can be increased.
In the structure of the second embodiment, the other structures are the same as the structures of the first embodiment, so that the same effects can be obtained.

In the above embodiment, preferably, a positive electrode can made of stainless steel and a negative electrode can made of stainless steel are used, and a non-aqueous electrolyte secondary battery having a coin-shaped structure provided with a storage container crimped thereof is taken as an example. As described above, this embodiment is not limited to this structure.
For example, the structure of the present invention is applied to a non-aqueous electrolyte secondary battery having a structure in which the opening of the ceramic container body is sealed with a ceramic lid by heat treatment such as seam welding using a metal sealing member. May be applied.

A non-aqueous electrolyte secondary battery having the configuration shown in FIG. 1 was prototyped and subjected to an evaluation test described later.
As the positive electrode 10, first, commercially available lithium manganese oxide (Li _1.14 Co _0.06 Mn _1.80 O ₄ ), graphite as a conductive auxiliary agent, polyacrylic acid as a binder, and lithium manganese oxide are used. : Graphite: Polyacrylic acid = 90: 8: 2 (mass ratio) was mixed to prepare a positive electrode mixture. 98.6 mg of this positive electrode mixture was pressurized with a pressure of 2 ton / cm ² , and pressure-molded into disc-shaped pellets having a diameter of 4 mm.

The obtained pellets (positive electrode) are bonded to the inner surface of a stainless steel (SUS316L: t = 0.20 mm) positive electrode can using a conductive resin adhesive containing carbon, and these are integrated to form a positive electrode unit. Obtained. Then, this positive electrode unit was heated and dried under reduced pressure in the air under the condition of 120 ° C. × 11 hours. Next, a sealant was applied to the inner surface of the opening of the positive electrode can in the positive electrode unit.

Next, as the negative electrode, SiO powder in which carbon (C) was formed on the entire surface was prepared, and this was used as the negative electrode active material. Then, graphite as a conductive agent and polyacrylic acid as a binder were mixed with this negative electrode active material at a ratio of 54:44: 2 (mass ratio) to obtain a negative electrode mixture. 15.1 mg of this negative electrode mixture was pressure-molded with a pressure of 2 ton / cm ² and pressure-molded into a disk-shaped pellet having a diameter of 4 mm.

The obtained pellets (negative electrode) are bonded to the inner surface of a negative electrode can made of stainless steel (SUS316L: t = 0.20 mm) using a conductive resin adhesive containing carbon as a conductive filler, and these are integrated. Obtained a negative electrode unit. Then, this negative electrode unit was heated and dried under reduced pressure in the air under the conditions of 160 ° C. × 11 hours.
A lithium foil punched to a diameter of 4 mm and a thickness of 0.38 mm was further pressure-bonded onto the pellet-shaped negative electrode to obtain a lithium-negative electrode laminated electrode.

As described above, in the present embodiment, the positive electrode can has the function of the positive electrode collector and the negative electrode can has the negative electrode collection without providing the positive electrode collector and the negative electrode current collector shown in the structure of the embodiment. A non-aqueous electrolyte secondary battery was produced by giving it the function of an electric body.

Next, after drying the non-woven fabric made of glass fiber, it was punched into a disk shape having a diameter of 4 mm to form a separator. Then, this separator was placed on a lithium foil crimped onto the negative electrode, and a polypropylene gasket was placed in the opening of the negative electrode can.

(Preparation of electrolyte)
Each solvent of tetraglyme (TEG), diethoxyethane (DEE), ethylene carbonate (EC), and vinylene carbonate (VC) was mixed to obtain a non-aqueous solvent, and the obtained non-aqueous solvent was used as a supporting salt for LiTFSI (. 1M) was dissolved to obtain an electrolytic solution. At this time, the mixing ratio of each solvent is mass%, and TEG: DEE: EC: VC = (41.25 to 48.25) :( 41.25 to 48.25): 2.5 :( 1. 0, 2.5, 5, 7.5, 10.0, 15).
The EC is fixed at 2.5% by mass for all samples, and 1.0% by mass, 2.5% by mass, 5% by mass, 7.5% by mass, 10.0% by mass, and 15 for VC. TEG and DEE, which are individually variable in 6 steps of mass% and constitute the balance, are blended in a ratio of 1: 1 to each other to prepare a plurality of samples.
The positive electrode can and the negative electrode can prepared as described above were filled with the electrolytic solution of each example prepared in the above procedure in a total of 40 μL per battery.

Next, the negative electrode unit was crimped to the positive electrode unit so that the separator was in contact with the positive electrode. Then, after sealing the positive electrode can and the negative electrode can by fitting the opening of the positive electrode can, the can is allowed to stand at 25 ° C. for 7 days, and the non-aqueous electrolytes 2 of Samples 1 to 6 having different amounts of vinylene carbonate added are used. I got the next battery. The gasket for sealing the positive electrode can and the negative electrode can was made of polyetheretherketone resin (PEEK resin).
These non-aqueous electrolyte secondary batteries of Samples 1 to 6 are samples in which the amounts of vinylene carbonate contained in the electrolytic solution are different as shown in Table 1 described later.

"Evaluation test"
(Measurement of battery thickness change)
The non-aqueous electrolyte secondary batteries of Samples 1 to 6 are preheated at 160 to 200 ° C. for 10 minutes, then subjected to a heat treatment equivalent to reflow soldering at 260 ° C. for 10 seconds, and then the battery thickness is increased. The amount of change (mm) was measured. By grasping the amount of change in the battery thickness, it is possible to grasp how much the internal pressure is increased by the gas vaporized or decomposed inside the container composed of the positive electrode can and the negative electrode can.
(Measurement of internal resistance)
The AC impedance (1 kHz: corresponding to the internal resistance) was measured for the non-aqueous electrolyte secondary batteries of Samples 1 to 6.
The above measurement results are summarized in Table 1 below, the measurement results of the battery thickness change amount are shown in FIG. 3, and the measurement results of the AC impedance (internal resistance) are shown in FIG.

From the measurement results of the change in battery thickness shown in Table 1 and FIG. 3, an appropriate amount of vinylene carbonate is added to a grime-based solvent mainly composed of tetraglyme (TEG) and diethoxyethane (DEE) in addition to ethylene carbonate. In this case, it was found that the amount of change was large regardless of whether the amount of vinylene carbonate added was too small or too large.
In the sample 1 in which the amount of vinylene carbonate added is 1.0% by mass and the sample 6 in which the amount of vinylene carbonate is 15.0% by mass, the amount of change exceeds 0.1 mm, which is clearly larger than that of the other samples. From this result, it can be seen that if the amount of change is 0.08 mm or less, it is desirable that the amount of vinylene carbonate added is 2% by mass or more and 13% by mass or less.
Further, since the amount of change in Samples 2 to 5 is clearly smaller than the amount of change in Samples 1 and 6, it is necessary to set the amount of vinylene carbonate added to 2.5% by mass or more and 10% by mass or less in the non-aqueous electrolyte secondary battery. It was found to be more preferable in suppressing swelling in the thickness direction after reflow soldering. Further, it was found that the amount of vinylene carbonate added was most preferably 5.0% by mass or more and 7.5% by mass or less.

From the measurement results of the internal resistance of the non-aqueous electrolyte secondary battery shown in Table 1 and FIG. 4, the same conclusion as the measurement result of the battery thickness change amount could be obtained.
That is, the internal resistance of the sample 1 in which the amount of vinylene carbonate added is 1.0% by mass and the sample 6 in which 15.0% by mass is 15.0% by mass exceeds 700Ω, and the internal resistance is clearly larger than that of the other samples. From this result, it can be seen that it is desirable that the amount of vinylene carbonate added is 2% by mass or more and 13% by mass or less in order to obtain an internal resistance of 700Ω or less and increase the capacity.
Further, since the internal resistance of the samples 2 to 5 is clearly smaller than the internal resistance of the samples 1 and 6, the amount of vinylene carbonate added should be 2.5% by mass or more and 10% by mass or less for the non-aqueous electrolyte secondary battery. It was found that it is more preferable to suppress the internal resistance and obtain a high capacity. Further, from the viewpoint of internal resistance, it was found that it is most preferable that the amount of vinylene carbonate added is 5.0% by mass or more and 7.5% by mass or less.

1, 11 ... Non-aqueous electrolyte secondary battery, 2 ... Storage container, 10 ... Positive electrode, 12 ... Positive electrode can, 12a ... Opening, 12b ... Peripheral portion, 13 ... Positive electrode, 14 ... Positive electrode current collector, 20 ... Negative electrode, 21 ... Stainless steel layer, 22 ... Negative electrode can, 22a ... Outer peripheral end, 23 ... Hard aluminum layer, 24 ... Negative electrode collector, 25 ... Negative electrode can, 26 ... Negative electrode, 30 ... Separator, 40, 42 ... Gasket, 41 ... Circular groove, 50 ... Electrolyte.

Claims (5)

A non-aqueous electrolyte secondary battery in which a positive electrode, a negative electrode, an electrolytic solution containing a supporting salt and a solvent, and a separator are housed in a storage container composed of a positive electrode can and a negative electrode can.
The solvent contains tetraglyme (TEG) and diethoxyethane (DEE), which are glyme-based solvents, ethylene carbonate (EC) and vinylene carbonate (VC), and tetraglyme (TEG): 30% by mass or more. 48.5% by mass or less, diethoxyethane (DEE): 30% by mass or more and 48.5% by mass or less, ethylene carbonate (EC): 0.5% by mass or more and 10% by mass or less, vinylene carbonate (VC): 2% by mass. A non-aqueous electrolyte secondary battery comprising a range of% or more and 13% or less (total 100%) . The supporting salts are LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiN (CF ₃ SO ₃ ). ) ₂ , LiN (FSO ₂ ) ₂ organic acid lithium salt, or LiPF ₆ , LiBF ₄ , LiB (C ₆ H ₅ ) ₄ , LiCl, LiBr inorganic acid lithium salt. The non-aqueous electrolyte secondary battery according to claim 1, wherein the non-aqueous electrolyte secondary battery is characterized. The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein the solvent contains vinylene carbonate in an amount of 2.5% by mass or more and 10% by mass or less. Any of claims 1 to 3 , wherein the positive electrode contains a lithium manganese oxide as a positive electrode active material, and the negative electrode contains a silicon oxide or a lithium aluminum alloy as a negative electrode active material. The non-aqueous electrolyte secondary battery according to item 1. The positive electrode can has a bottomed cylindrical shape.
The negative electrode can is fixed with a gasket inside the opening of the positive electrode can.
The claim is characterized in that the storage container is sealed by providing a caulking portion for crimping the opening of the positive electrode can on the negative electrode can side, and the positive electrode, the negative electrode, the separator, and the electrolytic solution are stored in the storage container. The non-aqueous electrolyte secondary battery according to any one of items 1 to 4 .

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