KR20190108477A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

An object of the present invention is to provide a non-aqueous electrolyte secondary battery having low internal resistance, high characteristics, and excellent heat resistance to withstand heating such as reflow solder. The non-aqueous electrolyte secondary battery of the present invention is a non-aqueous electrolyte secondary battery in which a positive electrode, negative electrode, an electrolyte comprising a supporting salt and a solvent, and a separator are accommodated in an accommodating container made of a positive electrode can and a negative electrode can. The solvent comprises ethylene carbonated (EC) and vinylene carbonate (VC) in a glyme-based solvent.

Description

Non-aqueous electrolyte secondary battery {NONAQUEOUS ELECTROLYTE SECONDARY BATTERY}

The present invention relates to a nonaqueous electrolyte secondary battery.

The coin-type nonaqueous electrolyte secondary battery employs reflow soldering to increase the efficiency of soldering at the time of mounting on a circuit board. In order to provide heat resistance in reflow soldering, various types of heat resistant members, such as electrolyte solution and gasket, are employed in this type of secondary battery. Among these, a sulfone-based or glyme-based solvent having a high boiling point is often used. For example, in the following prior art document 1, a polyethylene glycol dialkyl ether and an ethylene glycol dialkyl ether are contained as a solvent of an electrolyte solution, thereby having heat resistance to withstand reflow soldering and discharging even in a low temperature environment. Maintaining capacity has been shown.

Japanese Patent Publication No. 2011-060444

In such a reflow-compatible nonaqueous electrolyte secondary battery, a high capacity can be obtained by employing a spinel-type lithium manganese oxide as a positive electrode active material and a lithium-aluminum alloy as a negative electrode active material.

On the other hand, there is a demand for further increasing the capacity in such a battery. For example, it is possible 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 changing an electrode in this way, it is necessary to ensure stability of charge and discharge, and to suppress unexpected reaction of an electrode or electrolyte solution.

In view of such a problem, the present invention aims to improve the stability in a nonaqueous electrolyte secondary battery while having a small size, high capacity, heat resistance to withstand reflow soldering.

"1" In order to solve the said subject, the nonaqueous electrolyte secondary battery which concerns on one form of this invention is an electrolyte solution containing a positive electrode, a negative electrode, a supporting salt, and a solvent, and a separator consists of a positive electrode can and a negative electrode can. A nonaqueous electrolyte secondary battery that is housed in a configured container,

The solvent is characterized by containing ethylene carbonate (EC) and vinylene carbonate (VC) in a glame-based solvent.

In this embodiment, since diethoxy ethane, ethylene carbonate, and vinylene carbonate are included in the glyme solvent including tetraglyme and the like, heat resistance to withstand the heating during reflow soldering can be obtained, and deterioration of the electrode and the electrolyte solution is prevented. It has a feature that can be suppressed.

"2" In the nonaqueous electrolyte secondary battery of the above aspect, it is preferable that the solvent contains tetraglyme (TEG) as the main solvent and diethoxyethane (DEE) as the subsolvent.

If the solvent is a glyme-based solvent containing tetraglyme and diethoxyethane as a solvent, the heat resistance can be improved due to the high boiling point of these solvents.

"3" In the nonaqueous electrolyte secondary battery of the above-mentioned aspect, it is preferable that 2 mass% or more and 13 mass% or less of vinylene carbonate is contained in the said solvent.

In the nonaqueous electrolyte secondary battery of the present embodiment, since a suitable amount of vinylene carbonate is contained in a glyme solvent including tetraglyme, etc., the non-aqueous electrolyte secondary battery has heat resistance that can withstand reflow soldering, and the heating accompanying reflow soldering is prevented. Even if it is received, it is possible to provide a configuration in which the solvent is less likely to evaporate, the internal pressure of the storage container is less likely to rise, and the deformation of the storage container is less likely to occur. In addition, if the amount of vinylene carbonate added in this range can reduce the internal resistance of the nonaqueous electrolyte secondary battery, high capacity can be achieved, and swelling of the containing container can be suppressed, so that nonaqueous electrolyte secondary which does not cause deterioration of the electrode or the electrolyte solution can be obtained. A battery can be provided.

"4" In the nonaqueous electrolyte secondary battery of the above aspect, it is preferable that vinylene carbonate is contained in the solvent in an amount of 2.5% by mass or more and 10% by mass or less.

In the nonaqueous electrolyte secondary battery of the present embodiment, since a preferred amount of vinylene carbonate is contained by a glyme solvent including tetraglyme or the like, the nonaqueous electrolyte secondary battery has heat resistance to withstand reflow soldering and is accompanied by reflow soldering. Even if it is heated, there is little possibility that a solvent will vaporize, there is little possibility that the internal pressure of a storage container may rise, and the structure which hardly produces deformation in a storage container can be provided. In addition, if the amount of vinylene carbonate added in this range can reduce the internal resistance of the nonaqueous electrolyte secondary battery, the capacity can be increased and the swelling of the containing container can be further suppressed. An electrolyte secondary battery can be provided.

"5" In the nonaqueous electrolyte secondary battery of the above aspect, it is preferable that the positive electrode contains lithium manganese oxide as the positive electrode active material, and the negative electrode contains silicon oxide or a lithium aluminum alloy as the negative electrode active material.

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

"6" In the nonaqueous electrolyte secondary battery of the above aspect, a negative electrode can having a cylindrical cylindrical bottomed bottom and a gasket fixed inside a opening of the positive electrode can via a gasket to form a receiving space therebetween. And a caulking portion caulking the opening of the cathode can on the cathode can side to seal the container, and the cathode, the cathode, the separator and the electrolyte are accommodated in the container.

In the case of the structure in which the opening of the positive electrode can is sealed on the negative electrode can side to seal the container, a part of the solvent vaporizes by heating during reflow soldering depending on the component of the solvent contained therein so that the internal pressure of the container is increased. There is a fear that the container will rise and swell. If a solvent containing an appropriate amount of vinylene carbonate is contained in the above-mentioned glame-based solvent, even if the heating is performed by reflow soldering, there is little possibility that the receiving container will swell greatly, and the electrode degradation after reflow soldering will not be caused, and the electrolyte solution will be deteriorated. It is possible to provide a nonaqueous electrolyte secondary battery that is unlikely to occur.

According to this embodiment, since the dietary solvent including tetraglyme and the like contains diethoxyethane, ethylene carbonate and vinylene carbonate, it is able to withstand the heating during reflow soldering and to suppress deterioration of the electrode and the electrolyte solution. A nonaqueous electrolyte secondary battery can be provided.

1 is a cross-sectional view showing a nonaqueous electrolyte secondary battery according to the first embodiment.
2 is a cross-sectional view showing a nonaqueous electrolyte secondary battery according to a second embodiment.
3 is a graph showing the amount of change in battery thickness when a heat treatment corresponding to reflow soldering is applied to a plurality of nonaqueous electrolyte secondary batteries constructed using a plurality of solvents prepared in Examples.
4 is a graph showing the results of measuring internal resistance (AC impedance) for a plurality of nonaqueous electrolyte secondary batteries constructed using a plurality of solvents prepared in Examples.

Hereinafter, the structure of the nonaqueous electrolyte secondary battery according to the embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2. In addition, the nonaqueous electrolyte secondary battery demonstrated by this invention is a secondary battery in which the active material and separator which are used as a positive electrode or a negative electrode are accommodated in the accommodating container. In addition, in the drawings used for the following description, in order to make each member into a recognizable size, since the scale of each member is changed and displayed suitably, of course, the relative size of each member is not limited to the form shown by drawing. .

[First Embodiment of Nonaqueous Electrolyte Secondary Battery]

The nonaqueous electrolyte secondary battery 1 of this embodiment shown in FIG. 1 is a so-called coin (button) type battery. The nonaqueous electrolyte secondary battery 1 includes a cylindrical cylindrical canned bottom 12 having a bottom, a cylindrical lid-shaped negative electrode can 22 having a lid covering an opening of the positive electrode 12, and a positive electrode 12. A gasket 40 is provided along the inner circumferential surface of the circumference), and a thin (flat) storage container 2 formed by caulking the periphery of the opening of the anode can 12 inside is provided. In the storage container 2, a storage space surrounded by the positive electrode can 12 and the negative electrode can 22 is formed, and the positive electrode 10 and the negative electrode 20 are disposed to face each other via the separator 30. In addition, the electrolyte 50 is filled.

As a material of the positive electrode can 12, a conventionally well-known thing is used, For example, stainless steel, such as SUS316L, SUS329JL, or NAS64, is mentioned.

As the material of the negative electrode can 22, the conventionally well-known stainless steel can be mentioned similarly to the material of the positive electrode can 12, For example, SUS316L, SUS329JL, SUS304-BA, etc. are mentioned.

(anode)

In this 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 connected to the negative electrode can via the negative electrode current collector 24 ( It is electrically connected to the inner surface of 22). In addition, the positive electrode current collector 14 and the negative electrode current collector 24 may be omitted, and the positive electrode 10 may be directly connected to the positive electrode can 12 to give the positive electrode 12 the function of the current collector. The negative electrode 12 may be directly connected to the negative electrode can 12 to give the negative electrode can 22 a function of a current collector.

The gasket 40 is connected to the outer circumference 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 electrolyte 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. For example, it is preferable to use a lithium manganese oxide as the positive electrode active material.

Content of the positive electrode active material in the positive electrode 10 is determined in consideration of the discharge capacity required for the nonaqueous electrolyte secondary battery 1, and can be in the range of 50 to 95 mass%. If content of a positive electrode active material is more than the lower limit of the said preferable range, sufficient discharge capacity will be easy to be obtained, and if it is below a preferable upper limit, it will be easy to shape the positive electrode 10.

The positive electrode 10 may contain a binder (hereinafter, a binder used for the positive electrode 10 may be referred to as a "positive binder").

As a positive electrode binder, a conventionally well-known substance can be used, For example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), polyacrylic acid (PA), carboxymethylcellulose (CMC), polyvinyl alcohol (PVA), etc. can be selected.

In addition, a positive electrode binder may be used individually by 1 type, or may be used in combination of 2 or more type. Content of the positive electrode binder in the positive electrode 10 can be 1-20 mass%, for example.

As the positive electrode current collector 14, a conventionally known one can be used, and a conductive resin adhesive or the like which uses carbon as the conductive filler can be mentioned.

In addition, in this embodiment, in addition to said lithium manganese oxide, you may contain another positive electrode active material as a positive electrode active material, For example, molybdenum oxide, a lithium iron phosphate compound, lithium cobalt oxide, a lithium nickel oxide, vanadium oxide. It may contain any one or more of other oxides.

(cathode)

Although the kind of negative electrode active material in the negative electrode 20 is not specifically limited, For example, it is preferable to contain a silicon oxide or an aluminum alloy as a negative electrode active material.

Moreover, in the negative electrode 20, it is preferable that the negative electrode active material consists of silicon oxide represented by SiOx (0 <x <2). In the negative electrode 20, a lithium aluminum alloy may be used for the negative electrode active material. The structure in the case of using a lithium aluminum alloy for a negative electrode active material is demonstrated in 2nd Embodiment mentioned later.

In addition, the negative electrode 20 may contain another negative electrode active material in addition to SiOx (0 ≦ x <2) as the negative electrode active material, and may contain other negative electrode active materials such as Si and C, for example. do.

When granular SiOx (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, and a range of 1 to 10 μm is used. Can be selected. If the particle diameter (D50) of SiOx is less than the lower limit of the said range, for example, when the nonaqueous electrolyte secondary battery 1 is stored and used in severe high temperature, high humidity environment, reactivity will become high by reflow process, The battery characteristics may be impaired, and if the upper limit is exceeded, the discharge rate may be lowered.

The content of the negative electrode active material in the negative electrode 20, that is, SiOx (0 ≦ x <2) is determined in consideration of the discharge capacity required for the nonaqueous electrolyte secondary battery 1, and a range of 50% by mass or more can be selected. , The range of 60-70 mass% can be selected.

In the negative electrode 20, if content of the negative electrode active material which consists of the said element is more than the lower limit of the said range, sufficient discharge capacity will be easy to be obtained, and if it is below an upper limit, it will be easy to shape the negative electrode 20.

The negative electrode 20 may contain a conductive aid (hereinafter, a conductive aid used for the negative electrode 20 may be referred to as a "cathode conductive aid"). The negative electrode conductive assistant is the same as the positive electrode conductive assistant.

The negative electrode 20 may contain a binder (hereinafter, the binder used for the negative electrode 20 may be referred to as a "cathode binder").

As the negative electrode binder, polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), polyacrylic acid (PA), carboxymethyl cellulose (CMC), polyimide (PI), polyimideamide (PAI) and the like can be selected.

In addition, a negative electrode binder may be used individually by 1 type, or may be used in combination of 2 or more type. In addition, when polyacrylic acid is used for a negative electrode binder, polyacrylic acid can be adjusted to pH3-10 previously. In this case, for example, alkaline earth metal hydroxides such as alkali metal hydroxides such as lithium hydroxide and magnesium hydroxide can be used to adjust the pH.

Content of the negative electrode binder in the negative electrode 20 is, for example, in a range of 1 to 20 mass%.

In this embodiment, the size and thickness of the cathode 20 can be formed in the same manner as the size and thickness of the anode 10.

In addition, although the illustration is abbreviate | omitted in the nonaqueous electrolyte secondary battery 1 shown in FIG. 1, between the surface of the negative electrode 20, ie, between the negative electrode 20 and the separator 30 mentioned later, lithium foil etc. The structure which installed the lithium body 60 can be employ | adopted.

`` Electrolyte amount ''

The electrolyte solution 50 usually dissolves a supporting salt in a nonaqueous solvent.

In the nonaqueous electrolyte secondary battery 1 of this embodiment, the nonaqueous solvent constituting the electrolyte solution 50 uses tetraglyme (TEG) as the main solvent, diethoxyethane (DEE) as the secondary solvent, and further ethylene. Carbonate (EC) and vinylene carbonate (VC) are contained as an additive. The nonaqueous solvent is usually determined in consideration of heat resistance, viscosity, and the like required for the electrolytic solution 50. In the present embodiment, a nonaqueous solvent is used.

Tetraglyme, triglyme, pentaglyme, diglyme and the like can be used as the main solvent for constituting the glyme solvent.

In this embodiment, the electrolytic solution 50 using the nonaqueous solvent containing ethylene carbonate (EC), tetraglyme (TEG), and diethoxyethane (DEE) is employ | adopted. By adopting such a constitution, DEE and TEG are solvated to Li ions forming a supporting salt.

At this time, since DEE has a donor number higher than TEG, DEE selectively solvates with Li ion. In this way, DEE and TEG are solvated to Li ions forming the supporting salt, thereby protecting Li ions. As a result, even if moisture enters the inside of the nonaqueous electrolyte secondary battery in a high temperature and high humidity environment, the reaction between the moisture and Li can be prevented, so that the discharge capacity is reduced and the storage characteristics are improved. You can get the effect.

Although the ratio of each said solvent in the nonaqueous solvent in the electrolyte solution 50 is not specifically limited, For example, TEG: 30 mass% or more and 48.5 mass% or less, DEE: 30 mass% or more and 48.5 mass% or less, EC: The range of the range (total 100%) of 0.5 mass% or more and 10 mass% or less and VC: 2 mass% or more and 13% or less can be selected.

If the ratio of TEG, DEE, and EC contained in the nonaqueous solvent is within the above range, the above-described action of solvating the Li ions to Li ions results in the effect of protecting Li ions.

Even if it is the above-mentioned range, the range of 2.5 mass% or more and 10 mass% is preferable with respect to content of VC, and the range of 5.0 mass% or more and 7.5 mass% is more preferable. About the upper limit of content of TEG and DEE, 48.25 mass% or less is preferable, and 48 mass% or less is more preferable.

When the content of VC is in the range of 2% by mass or more and 13% or less, even if it is heated during reflow soldering, there is a small change in the thickness of the accommodating container 2 made of the positive electrode 12 and the negative electrode 22. Increasing the internal resistance can also be reduced. In the case where the content of VC is in the range of 2.5% by mass or more and 10.0% by mass or less, even if it is heated at the time of reflow soldering, the change in thickness generated in the container 2 can be made smaller, and the increase in internal resistance is also increased. It can be made smaller. Even if it exists in these ranges, the range whose content of VC is 5.0 mass% or more and 7.5 mass% or less is the most preferable.

Supported salts, non-aqueous can be used for the Li compound known to be used as the support salt in the electrolyte solution of the electrolyte secondary battery, for _{example, LiCH 3 SO 3, LiCF 3} SO 3, LiN (CF 3 SO 2) 2, LiN ( Organic acid lithium salts such as 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 ) Lithium salts, such as inorganic acid lithium salts, such as ₄ , LiCl, LiBr, etc. are mentioned. Among these, a compound of lithium salt having a lithium ion conductivity, and _{preferably, LiN (CF 3 SO 2)} 2, LiN (FSO 2) 2, and LiBF preferably ₄ more, low reactivity with heat and moisture, and storability LiN (CF ₃ SO ₂ ) ₂ is particularly preferable from the standpoint of being able to sufficiently exhibit.

A supporting salt may be used individually by 1 type, or may be used in combination of 2 or more type.

Content of the supporting salt in electrolyte solution 50 can be determined in consideration of the kind of supporting salt, etc., For example, 0.1-3.5 mol / L is preferable, 0.5-3 mol / L is more preferable, 1-2.5 mol / L is particularly preferred. Even if the concentration of the supporting salt in the electrolyte solution 50 is too high or too low, there is a possibility that a drop in conductivity occurs and adversely affects battery characteristics.

(Separator)

The separator 30 is interposed between the anode 10 and the cathode 20, an insulating film having a large ion permeability and a mechanical strength is used.

As the separator 30, what is conventionally used for the separator of a nonaqueous electrolyte secondary battery can be applied without a restriction | limiting, For example, glass, such as alkali glass, borosilicate glass, quartz glass, lead glass, polyphenylene sulfide ( PPS), polyether ether ketone (PEEK), polyethylene terephthalate (PET), polyamideimide (PAI), nonwoven fabric which consists of resin, such as polyamide, polyimide (PI), etc. are mentioned. Especially, a glass nonwoven fabric is preferable and a borosilicate glass nonwoven fabric is more preferable. Since the glass nonwoven fabric is excellent in mechanical strength and has a large ion permeability, the internal resistance can be reduced and the discharge capacity can be improved.

The thickness of the separator 30 is determined in consideration of the size of the nonaqueous electrolyte secondary battery 1, the material of the separator 30, and the like, and can be, for example, 5 to 300 μm.

(Gasket)

It is preferable that the gasket 40 consists of resin with a heat distortion temperature of 230 degreeC or more, for example. If the heat deformation temperature of the resin material used for the gasket 40 is 230 degreeC or more, a gasket will deform | deformed remarkably by the reflow soldering process and the heating during use of the nonaqueous electrolyte secondary battery 1, and electrolyte solution 50 will leak. Can be prevented.

As shown in FIG. 1, the gasket 40 is formed in an annular shape along the inner circumferential surface of the anode can 12, and the outer circumferential end 22 a of the cathode can 22 is disposed inside the annular groove 41. It is.

The gasket 40 includes a ring-shaped outer edge portion 40A having an outer diameter inserted into the opening inner peripheral side of the anode can 12 without a gap, a ring-shaped inner edge portion 40B, and these outer edge portions 40A and inner edge portions. It consists of the bottom wall part 40C which connected the lower end parts of 40B. Therefore, the annular groove 41 into which the outer peripheral end 22a of the cathode can 22 can be inserted is formed in the outer peripheral upper surface side of the gasket 40.

In the structure which sealed the accommodating space by interposing the gasket 40 by caulking the periphery part 12b of the opening part 12a of the anode can 12 shown in FIG. 1 inside, ie, the cathode can 22 side, The storage container 2 is comprised.

As a material of the gasket 40 as described above, for example, polyphenyl sulfide (PPS), polyethylene terephthalate (PET), polyamide, liquid crystal polymer (LCP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymerization Resin (PFA), polyether ether ketone resin (PEEK), polyether nitrile resin (PEN), polyether ketone resin (PEK), polyarylate resin, polybutylene terephthalate resin (PBT), polycyclohexanedimethylene And terephthalate resins, polyether sulfone resins (PES), polyaminobismaleimide resins, polyetherimide resins, and fluorine resins. Moreover, what added glass fiber, mica whisker, fine ceramic powder, etc. to these materials in the addition amount of 30 mass% or less can be used suitably. By using such a material, a gasket deforms remarkably by heating and it can prevent that electrolyte solution 50 leaks.

According to the nonaqueous electrolyte secondary battery 1 of the present embodiment described above, the nonaqueous solvent mainly contains tetraglyme (TEG) and diethoxyethane (DEE), and includes ethylene carbonate (EC) and vinyl in the appropriate amount range described above. Since the electrolyte solution 50 which contains the suitable amount of carbonate VC is provided, it has heat resistance which can endure reflow soldering, and even if it receives the heating accompanying reflow soldering, there is little possibility that a solvent will vaporize and receive There is little possibility that the internal pressure of the container 2 rises, and the structure which is hard to cause deformation | transformation to the accommodation container 2 can be provided.

If the solvent is a glyme-based solvent containing tetraglyme and diethoxyethane as a solvent, the heat resistance of the electrolyte can be improved due to the high boiling point of these solvents.

"Second Embodiment of Nonaqueous Electrolyte Secondary Battery"

FIG. 2 shows a nonaqueous electrolyte secondary battery 11 of the second embodiment, wherein the nonaqueous electrolyte secondary battery 11 of this embodiment has a coin (button) having a structure similar to that of the nonaqueous electrolyte secondary battery 1 of the first embodiment. ) Battery. This nonaqueous electrolyte secondary battery 11 has a positive electrode 12, a negative electrode can 25, and a gasket 42, and has a thin (flat) shape formed by caulking the periphery of the opening of the positive electrode can 12 inside. On the point provided with the storage container 2, it is the structure equivalent to the nonaqueous electrolyte secondary battery 1 of 1st Embodiment.

In the negative electrode can 25 of the second embodiment, the stainless steel material and the hard aluminum material are bonded to each other by rolling, and have a two-layer structure of the outer stainless layer 21 and the inner hard aluminum layer 23.

In the nonaqueous electrolyte secondary battery 11 of the second embodiment, the positive electrode 13 and the negative electrode 26 are disposed to face each other in the storage container 2 via the separator 30A, and the electrolyte solution 50 is in a sealed space. (16) is charged. The positive electrode 13, the negative electrode 26, and the separator 30A are impregnated with the electrolyte solution 50 filled in the storage container 2.

The positive electrode 13 is bonded to the inner bottom face 10b of the positive electrode can 10 by a positive electrode current collector 14 made of a conductive resin adhesive having carbon as a conductive filler, and a separator (on the upper side of the positive electrode 12). 30A) is mounted. The cathode 26 is placed on the separator 30A, and the cathode 26 is pressed against the inner upper surface 20b of the cathode can 25, that is, the hard aluminum layer 23.

As the anode 13, a material equivalent to the material constituting the anode 10 of the first embodiment can be applied.

Examples of the negative electrode 26 include lithium foil (lithium foil), lithium-aluminum alloy, carbon in which lithium is contacted or electrochemically doped.

The separator 30A is made of glass fibers, and examples thereof include glass nonwoven fabrics such as borosilicate glass, quartz glass, and lead glass, and among them, borosilicate glass nonwoven fabric is more preferable. Since the borosilicate glass nonwoven fabric is excellent in mechanical strength and has large ion permeability, the internal resistance can be reduced and the discharge capacity can be improved.

The composition of the electrolyte solution 50 is equivalent to the electrolyte solution 50 of the first embodiment. Tetraglyme (TEG) is a main solvent, diethoxyethane (DEE) is a subsolvent, and in addition to ethylene carbonate (EC), vinylene carbonate (VC) is an electrolyte solution containing a suitable amount range as an additive. In the electrolyte solution 50, the composition ratio of each component may also be equivalent to 1st Embodiment mentioned above.

Also in the structure of 2nd Embodiment, since the electrolyte solution 50 containing the vinylene carbonate (VC) of the suitable quantity range mentioned above is provided like the structure of 1st Embodiment, the heat resistance which can endure reflow soldering is provided. Even if the heating is accompanied by reflow soldering, the solvent is less likely to vaporize, the internal pressure of the storage container 2 is less likely to rise, and the storage container 2 is less likely to be deformed. Can be.

In the structure of 2nd Embodiment, since lithium foil (lithium foil) and a lithium-aluminum alloy are used as the negative electrode 25, high capacity can be attained.

In the structure of 2nd Embodiment, since the other structure is equivalent to the structure of 1st Embodiment, an equivalent effect can be acquired.

In addition, in the above embodiment, a coin-type nonaqueous electrolyte secondary battery having a storage container in which a positive electrode can made of stainless steel and a negative electrode can made of stainless steel is caulked using a stainless steel positive electrode can is described as an example. The form is not limited to this structure.

For example, this invention relates to the nonaqueous electrolyte secondary battery of the structure in which the opening part of the ceramic container main body was sealed by the ceramic individual by heat processing, such as the seam welding using the metal sealing member. You may apply a structure.

Example

The nonaqueous electrolyte secondary battery of the structure shown in FIG. 1 was started, and the evaluation test mentioned later was performed.

As the positive electrode 10, firstly, commercially available lithium manganese oxide (Li _1.14 Co _0.06 Mn _1.80 O ₄ ), graphite as a conductive aid, polyacrylic acid as a binder, lithium manganese oxide: graphite: polyacrylic acid = 90: 8 It mixed in the ratio of 2: 2 (mass ratio), and it was set as positive mix. 98.6 mg of this positive electrode mixture was pressed at a pressing force of ² ton / cm ² , and pressure molded into a disk-shaped pellet having a diameter of 4 mm.

The obtained pellets (anode) were adhered to the inner surface of a positive electrode can made of stainless steel (SUS316L: t = 0.20 mm) using a conductive resin adhesive containing carbon, and these were integrated to obtain a positive electrode unit. Then, this positive electrode unit was dried under reduced pressure and heat-dried under the conditions of 120 degreeC x 11 hours in air | atmosphere. Next, the sealing agent was apply | coated to the inner surface of the opening part of the positive electrode can in a positive electrode unit.

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

The obtained pellet (cathode) was adhered 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 the conductive filler, and these were integrated to obtain a negative electrode unit. Then, this negative electrode unit was dried under reduced pressure and heat-dried under the conditions of 160 degreeCx11 hours in air | atmosphere.

On the pellet-shaped negative electrode, a lithium foil punched with a diameter of 4 mm and a thickness of 0.38 mm was further pressed into a lithium-anode laminated electrode.

As described above, in the present embodiment, the positive electrode can has the function of the positive electrode current collector without providing the positive electrode current collector and the negative electrode current collector shown in the structure of the embodiment, and the negative electrode can has a negative electrode current collector. It had a function and produced the nonaqueous electrolyte secondary battery.

Next, after drying the nonwoven fabric which consists of glass fiber, it punched in the disk shape of diameter 4mm, and set it as the separator. And this separator was mounted on the lithium foil crimped | bonded on the negative electrode, and the gasket made of polypropylene was arrange | positioned at the opening part of a negative electrode can.

(Production of electrolyte)

Each solvent of tetraglyme (TEG), diethoxyethane (DEE), ethylene carbonate (EC), and vinylene carbonate (VC) is mixed to form a nonaqueous solvent, and LiTFSI (1M) as a supporting salt to the obtained nonaqueous solvent. Was dissolved to obtain an electrolyte solution. At this time, the mixing ratio of each solvent was% by 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) It was set as.

EC is made into the compounding quantity which fixed all the samples to 2.5 mass%, and about VC is changed into 6 steps of 1.0 mass%, 2.5 mass%, 5 mass%, 7.5 mass%, 10.0 mass%, and 15 mass%, respectively, TEG and DEE which comprise a part were mix | blended so that it might become a ratio of 1: 1, and several samples were produced.

The positive electrode can and the negative electrode can prepared as described above were filled with 40 µL of the electrolyte solution of each example adjusted in the above order in a total of one battery.

Next, the negative electrode unit was caulked to the positive electrode unit so that the separator abuts on the positive electrode. And after sealing the positive electrode can and the negative electrode can by fitting the opening part of a positive electrode can, it left still at 25 degreeC for 7 days, and obtained the nonaqueous electrolyte secondary battery of the sample 1-the sample 6 in which vinylene carbonate addition amount differs. The gasket for sealing the positive electrode can and the negative electrode can was constructed from polyether ether ketone resin (PEEK resin).

These nonaqueous electrolyte secondary batteries of Sample 1-Sample 6 are samples in which the quantity of the vinylene carbonate contained in electrolyte solution differs, respectively, as Table 1 mentioned later.

Evaluation test

(Measurement of Battery Thickness Change)

The amount of change in the battery thickness after the heat treatment corresponding to the reflow soldering to be heated at 260 ° C for 10 seconds after the pre-heating at 160 to 200 ° C for 10 minutes for the nonaqueous electrolyte secondary batteries of Samples 1 to 6 mm) was measured. By grasping the amount of change in the thickness of the battery, it is possible to grasp how much the internal pressure rises due to the gas vaporized or decomposed in the interior of the accommodating container including the positive electrode can and the negative electrode can.

(Internal resistance measurement)

About the nonaqueous electrolyte secondary battery of the sample 1-the sample 6, the alternating current impedance (1kHz: corresponded to internal resistance) was measured.

The above measurement result is put together in the following Table 1, and the measurement result of the battery thickness change amount is shown in FIG. 3, and the measurement result of alternating current impedance (internal resistance) is shown in FIG.

TABLE 1

From the measurement results of changes in battery thicknesses shown in Table 1 and FIG. 3, an appropriate amount of vinylene carbonate was added to ethylene carbonate in addition to ethylene carbonate in a solvent of a glyme system mainly composed of tetraglyme (TEG) and diethoxyethane (DEE). In this case, it was found that the amount of change increased even if the amount of vinylene carbonate added was too small or too large.

In the sample 1 of 1.0 mass% and the sample 6 of 15.0 mass%, the amount of change of vinylene carbonate exceeded 0.1 mm, and a change amount is large clearly compared with another sample. From this result, it turns out that it is preferable to set vinylene carbonate addition amount to 2 mass% or more and 13 mass% or less, if the amount of change is 0.08 mm or less.

In addition, since the amount of change of samples 2-5 is clearly smaller than the amount of change of samples 1, 6, it is preferable that the amount of vinylene carbonate added is 2.5 mass% or more and 10 mass% or less in the thickness direction after reflow soldering in a nonaqueous electrolyte secondary battery. It turned out that it is more preferable in suppressing bulging of. Moreover, it turned out that it is most preferable to make vinylene carbonate addition amount into 5.0 mass% or more and 7.5 mass% or less.

From the measurement result of the internal resistance of the nonaqueous electrolyte secondary battery shown in Table 1 and FIG. 4, the same conclusion as the measurement result of the battery thickness change amount was obtained.

That is, in the sample 1 of 1 mass% of vinylene carbonate, and the sample 6 of 15.0 mass%, internal resistance exceeds 700 ohms, and internal resistance is largely large compared with other samples. From this result, it is understood that when the internal resistance is 700 Ω or less and the capacity is increased, the amount of vinylene carbonate added is preferably 2 mass% or more and 13 mass% or less.

In addition, since the internal resistances of Samples 2 to 5 were clearly smaller than those of Samples 1 and 6, setting the amount of vinylene carbonate added to 2.5% by mass or more and 10% by mass or less suppressed the internal resistance of the nonaqueous electrolyte secondary battery. It turned out that it is more preferable in obtaining a high dose. Moreover, also from the viewpoint of internal resistance, it turned out that it is most preferable to make vinylene carbonate addition amount into 5.0 mass% or more and 7.5 mass% or less.

1, 11 non-aqueous electrolyte secondary battery, 2 accommodation containers, 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 end, 23 hard Aluminum layer, 24 negative electrode current collector, 25 negative electrode cans, 26 negative electrodes, 30 separators, 40, 42 gaskets, 41 annular grooves, 50 electrolytes.

Claims (6)

As a nonaqueous electrolyte secondary battery in which the positive electrode, the negative electrode, the electrolyte solution containing a support salt, and a solvent, and a separator are accommodated in the accommodating container comprised by a positive electrode can and a negative electrode can,
A nonaqueous electrolyte secondary battery, wherein the solvent comprises ethylene carbonate (EC) and vinylene carbonate (VC) in a glycol solvent. The method according to claim 1,
A nonaqueous electrolyte secondary battery, wherein the solvent contains tetraglyme (TEG) as a main solvent and diethoxyethane (DEE) as a subsolvent. The method according to claim 1 or 2,
2 mass% or more and 13 mass% or less of vinylene carbonate is contained in the said solvent, The nonaqueous electrolyte secondary battery characterized by the above-mentioned. The method according to claim 1 or 2,
A nonaqueous electrolyte secondary battery, wherein the solvent contains 2.5% by mass or more and 10% by mass or less of vinylene carbonate. The method according to any one of claims 1 to 4,
A nonaqueous electrolyte secondary battery, wherein the positive electrode contains lithium manganese oxide as a positive electrode active material, and the negative electrode contains silicon oxide or a lithium aluminum alloy as a negative electrode active material. The method according to any one of claims 1 to 5,
The anode can is cylindrical with a bottom,
The cathode can is fixed through a gasket inside the opening of the cathode can,
A nonaqueous electrolyte secondary battery, characterized in that the accommodating container is sealed by providing a caulking portion caulking the opening of the positive electrode can on the negative electrode can side, and the positive electrode, the negative electrode, the separator, and the electrolyte are accommodated in the accommodating container.

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