JP2003017120A - Lithium secondary cell for mounting on board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium secondary cell for mounting on a board, restrained from a reaction between the cell material like a positive electrode, a negative electrode, nonaqueous electrolyte liquid, and a separator caused by reflow or the like, when mounting the lithium secondary cell on the board, prevented from liquid leakage when the internal pressure of the cell is bigly increased, without big increase of internal resistance of the cell. SOLUTION: For the lithium secondary cell to be mounted on the board comprising a positive electrode 1, a negative electrode 2 made of an alloy containing lithium and aluminum, and nonaqueous electrolyte liquid composed of solvent and solute, the solvent contains sulfolane and 1,2-dimethoxyethane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium secondary battery for mounting a substrate, which is mounted on a substrate.
The present invention relates to a substrate mounting lithium secondary battery mounted on a substrate by automatic soldering by reflow.

[0002]

2. Description of the Related Art Lithium secondary batteries are small and lightweight,
Because of its high energy density and excellent storage characteristics, it has been widely used as a main power supply for various electronic devices and a power supply for memory backup.

Here, when the lithium secondary battery is used as a power source for memory backup, the lithium secondary battery is a substrate such as a printed circuit board so that the lithium secondary battery can operate stably for a long period of time. The method of directly implementing is widely adopted.

When mounting a lithium secondary battery on a substrate such as a printed circuit board as described above, one end of a metal lead plate for current extraction is spot-welded or laser-welded on the external terminal surface of the lithium secondary battery. It has been practiced to attach a part and insert the other end of the metal lead plate into a terminal hole provided in a substrate such as a printed circuit board for soldering.

Here, when soldering the other end of the metal lead plate attached to the external terminal surface of the lithium secondary battery to the substrate as described above, the work of individually soldering is troublesome, and production There was a problem that the cost was high and the cost was poor.

For this reason, in recent years, cream solder has been applied to the portion of the substrate on which electronic parts such as lithium secondary batteries are mounted, and after the electronic parts such as lithium secondary batteries have been placed on the application surface of the cream solder, An electronic component such as a lithium secondary battery is introduced together with a substrate into a reflow furnace and heated in the reflow furnace at a high temperature of about 230 ° C to 270 ° C for a short time to melt the solder. Attempts have been made to automatically solder the board to the board.

However, when the lithium secondary battery is introduced together with the substrate into the reflow furnace and mounted on the substrate, the lithium secondary battery is also exposed to a high temperature of about 230 ° C. to 270 ° C., and the lithium secondary battery is reflowed during the reflow process. Positive electrode in secondary battery,
Reacts violently between battery materials such as the negative electrode, the non-aqueous electrolyte, the separator, and the gasket that seals the container that houses them, which increases the internal pressure of the lithium secondary battery and causes liquid leakage, There was a problem that the internal resistance of the secondary battery increased significantly.

Therefore, in recent years, Japanese Patent Laid-Open No. 2000-2000
As disclosed in JP-A-40525 and JP-A-2000-48859, a non-aqueous electrolyte prepared by dissolving a lithium salt having a sulfone group in an organic solvent containing sulfolane or 3-methylsulfolane as a main component is used. A lithium secondary battery has been proposed which is used to prevent the non-aqueous electrolyte from vaporizing during reflow to prevent the internal pressure of the battery from rising.

However, even in those disclosed in these publications, the amount of sulfolane or 3-methylsulfolane used as the solvent of the non-aqueous electrolyte is not appropriate, or the kind of the solvent mixed with sulfolane or 3-methylsulfolane is not suitable. If not suitable, there are problems that the conductivity of the non-aqueous electrolyte is greatly reduced and the charge / discharge characteristics of the lithium secondary battery are deteriorated, or the high temperature stability of the lithium secondary battery cannot be sufficiently improved. It was

Further, in the prior art, Japanese Patent Laid-Open No. 6-223
In 874, a solvent of a non-aqueous electrolyte in a lithium secondary battery is mixed with sulfolane, an organic solvent having a low viscosity such as 1,2-dimethoxyethane, and an organic solvent having a high dielectric constant such as ethylene carbonate. It is proposed to use one that

However, in the above publication, it is not premised that the lithium secondary battery is mounted on the substrate by reflow or the like, so that there is no indication of the problem of the lithium secondary battery during reflow. Further, the type of the negative electrode has not been studied, and there is a problem that the high temperature stability in the lithium secondary battery cannot be sufficiently improved.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems in mounting a lithium secondary battery on a substrate by reflow or the like. When mounting a secondary battery, the positive electrode in the lithium secondary battery,
Substrate mounting that suppresses reactions between battery materials such as negative electrode, non-aqueous electrolyte, separator, etc., and does not cause liquid leakage due to increased internal pressure of the battery or large increase in internal resistance of the battery Is to provide a lithium secondary battery for use.

[0013]

In order to solve the above-mentioned problems, the present invention provides a substrate-mounting lithium secondary battery mounted on a substrate, which includes a positive electrode, lithium and aluminum. A negative electrode using an alloy, a non-aqueous electrolyte consisting of a solute and a solvent, a separator provided between the positive electrode and the negative electrode, a container for housing these, and a gasket for sealing the container. The solvent is provided so as to contain sulfolane and 1,2-dimethoxyethane.

Then, like the lithium secondary battery for mounting a substrate in the present invention, sulfolane and 1,
When a solvent containing 2-dimethoxyethane is used and an alloy containing lithium and aluminum is used for the negative electrode,
When a lithium secondary battery is mounted on a substrate by reflowing at a high temperature of about 230 ° C. to 270 ° C., the non-aqueous electrolytic solution is vaporized by the heat at the time of reflowing, or the non-aqueous electrolytic solution is positive electrode or negative electrode, especially negative electrode. Is suppressed from reacting with. As a result, it is possible to prevent the internal pressure of the battery from increasing, causing liquid leakage, and the internal resistance of the battery from increasing, and sufficient charging / discharging cycle characteristics and charging / discharging characteristics are exhibited.

Here, in the lithium secondary battery for mounting a substrate according to the present invention, sulfolane and 1,
The solvent containing 2-dimethoxyethane was used, but when sulfolane alone was used, the high temperature stability was increased,
The conductivity of the non-aqueous electrolyte is low and the charge / discharge characteristics are poor. On the other hand, with 1,2-dimethoxyethane alone, the conductivity of the non-aqueous electrolyte is high and the charge / discharge characteristics are good, but the high temperature stability is high. It will be worse.

When a solvent containing sulfolane and 1,2-dimethoxyethane is used in the non-aqueous electrolyte as described above, the high temperature stability of the non-aqueous electrolyte is improved and the conductivity of the non-aqueous electrolyte is improved. In order to increase the ratio, the proportion of sulfolane in the solvent is preferably in the range of 3 to 50% by volume, and more preferably the proportion of sulfolane in the solvent is in the range of 5 to 40% by volume.

When an alloy containing lithium and aluminum is used for the negative electrode as in the lithium secondary battery for mounting a substrate according to the present invention, even when reflowing at a high temperature of about 230 ° C. to 270 ° C. The reaction with the above-mentioned non-aqueous electrolyte using a solvent containing 1,2-dimethoxyethane is suppressed. In addition, although the cause of suppressing the reaction of the negative electrode using the alloy containing lithium and aluminum with the non-aqueous electrolytic solution during the reflow is unknown, the sulfolane used in the non-aqueous electrolytic solution and 1 It is considered that a high-quality film is formed on the surface of the negative electrode using the alloy containing lithium and aluminum by the solvent containing 1,2-dimethoxyethane, and this film greatly contributes to high-temperature stability. .

If propylene carbonate is used together with the above-mentioned sulfolane and 1,2-dimethoxyethane as the solvent of the above non-aqueous electrolyte, the cause is unknown,
A higher quality coating is formed on the surface of the negative electrode using the alloy containing lithium and aluminum, and the high temperature stability and charge / discharge characteristics are further improved.

When a solvent containing sulfolane, 1,2-dimethoxyethane and propylene carbonate is used in the non-aqueous electrolyte as described above, in order to further improve the high temperature stability and charge / discharge characteristics of the lithium secondary battery. For this reason, it is preferable that the ratio of propylene carbonate in the above solvent is in the range of 3 to 30% by volume. By doing so, the non-aqueous electrolytic solution reacts with the alloy containing lithium and aluminum during reflow. Is further reduced.

In the lithium secondary battery for mounting on a substrate according to the present invention, if manganese oxide is used as the material for the positive electrode, the positive electrode and the above-mentioned positive electrode can be used even during reflow at a high temperature of about 230 ° C to 270 ° C. The reaction with the non-aqueous electrolyte is also suppressed, and more excellent charge / discharge cycle characteristics and charge / discharge characteristics are exhibited.

When a manganese oxide having a spinel type structure (a cubic system is a cubic system and a space group is Fd3m) is used as the above manganese oxide, the positive electrode and the non-aqueous electrolytic solution are subjected to a reflow at about 230 ° C to 270 ° C. The reaction between and is further suppressed, and more excellent charge / discharge characteristics and high temperature stability are exhibited. The reason why the reaction between the positive electrode and the non-aqueous electrolytic solution is suppressed during reflow is unknown, but in the case of manganese oxide having a spinel structure, oxygen is hardly released during reflow. , With the reaction that oxidizes the non-aqueous electrolyte hardly occurs, since the spinel-type manganese oxide has a very stable structure, even if the positive electrode and the non-aqueous electrolyte react during reflow, It is considered that the positive electrode itself is hardly broken.

Further, a mandrel having a spinel type structure for the positive electrode
Charge and discharge characteristics and high temperature stability when using gun oxide
Manganese with spinel structure
As an oxide, its composition is Li_{1 + x}Mn_2-xO_Four(However
However, the condition of 0.05 ≦ x ≦ 0.33 is satisfied. )
Is preferably used, and more preferably Li_{1 + x}Mn
_2-xO_Four(However, the condition of 0.15 ≦ x ≦ 0.30 is satisfied.
You ) Is used.

If the specific surface area of the manganese oxide used for the positive electrode is smaller than 0.1 m ² / g, the contact area between the manganese oxide and the non-aqueous electrolyte becomes too small,
On the other hand, when the specific surface area of the manganese oxide is larger than 1.5 m ² / g while the charge / discharge characteristics are deteriorated, the area where the manganese oxide and the non-aqueous electrolyte are in contact with each other becomes too large, and manganese oxidation occurs during reflow. The substance and the non-aqueous electrolyte are likely to react with each other, and high temperature stability and charge / discharge characteristics are deteriorated. Therefore, the manganese oxide used for the positive electrode preferably has a specific surface area of 0.1 to 1.5 m ² / g, more preferably a specific surface area of 0.2 to 0.
It should be in the range of 8 m ² / g.

Further, in the substrate mounting lithium secondary battery of the present invention, when polyphenylene sulfide is used for the separator, it is possible to suppress the reaction of the separator with the non-aqueous electrolyte during reflow.

Further, in the lithium secondary battery for mounting a substrate according to the present invention, as a material of a gasket for sealing a container for accommodating the positive electrode, the negative electrode, the separator and the like,
Use of polyphenylene sulfide and / or polyether ether ketone also suppresses the reaction of the gasket with the above non-aqueous electrolyte during reflow.

Furthermore, when the cellulose resin is mixed with the gasket using polyphenylene sulfide and / or polyether ether ketone as described above, the reaction with the above non-aqueous electrolyte is further suppressed during reflow. , The strength of this gasket is also improved.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION A lithium secondary battery for mounting on a substrate according to an embodiment of the present invention will be specifically described below with reference to the accompanying drawings. The lithium secondary battery for mounting on a substrate according to the present invention is not particularly limited to the ones shown in the following embodiments, and can be appropriately modified and implemented without changing the gist thereof.

In the lithium secondary battery for mounting a substrate in this embodiment, as shown in FIG. 1, a separator 3 impregnated with a non-aqueous electrolyte is interposed between a positive electrode 1 and a negative electrode 2, The positive electrode case 4 a and the negative electrode case 4 b are housed in a battery case (housing body) 4 and the positive electrode 1
Is connected to the positive electrode case 4a via the positive electrode current collector 5, and the negative electrode 2 is connected to the negative electrode case 4b via the negative electrode current collector 6. Then, the positive electrode case 4a and the negative electrode case 4b are electrically insulated by a gasket 7 which is an insulating packing, and the positive electrode case 4a is caulked and sealed to form a flat coin-shaped lithium for substrate mounting. I got a secondary battery.

In the substrate mounting lithium secondary battery according to this embodiment, the positive electrode 1 is formed by mixing a positive electrode active material, a conductive agent and a binder.

As the positive electrode active material, known transition metal oxides generally used in lithium secondary batteries can be used. Examples thereof include titanium oxide, vanadium oxide, manganese oxide and cobalt. An oxide, a nickel oxide, a niobium oxide, a molybdenum oxide, or the like can be used, but it is preferable to use the manganese oxide as described above. In particular, it is preferable to use a manganese oxide having a spinel structure, and it is preferable to use one having a composition of Li _{1 + x} Mn _2-x O ₄ (0.05 ≦ x ≦ 0.33), more preferably Is Li _{1 + x} M
The one having n _2−x O ₄ (0.15 ≦ x ≦ 0.30) is used. Further, as described above, the specific surface area is 0.
It is preferable to use one having a range of 1 to 1.5 m ² / g, and more preferably one having a surface area of 0.2 to 0.8 m ² / g. Furthermore, in order to improve the high temperature stability, boric acid (H
The ₃ BO ₃₎ and boron oxide (B ₂ O ₃₎ boron compounds such as, B: the atomic ratio of Mn is 0.01 to 0.06: 1.0
It is preferable to use one that is mixed so as to be in the range of 0 and heat-treated at a temperature of about 300 to 400 ° C.

As the above-mentioned conductive agent used for the positive electrode 1, known materials generally used in lithium secondary batteries can be used. For example, natural graphite such as scaly graphite or earth-like graphite or artificial graphite can be used. Graphite, carbon black, acetylene black, Ketjen black, carbon fiber and the like can be used. Here, in order to further improve the charge / discharge characteristics in the battery of the present invention, it is preferable to use graphite and acetylene black in combination as the above-mentioned conductive agent, and in particular, graphite and acetylene black are used in a range of 3/7 to It is preferable to use a mixture in which the weight ratio is 7/3.

As the above-mentioned binder used in the positive electrode 1, known binders generally used in lithium secondary batteries can be used. Examples thereof include polytetrafluoroethylene, polyvinylidene fluoride, polyvinylpyrrolidone, and the like. Polyvinyl chloride, polyethylene, polypropylene, polyfluoroethylene propylene, ethylene-
Propylene-diene terpolymer, styrene butadiene rubber, carboxymethyl cellulose, fluororubber and the like can be used. In addition, at the time of reflow, it is 230 ℃ ~ 27
Since it is heated to about 0 ° C., it is preferable to use polyfluoroethylene propylene having high high-temperature stability, and it is particularly preferable to set the addition amount of polyfluoroethylene propylene in the positive electrode in the range of 1 to 10 wt%.

Further, as the negative electrode 2, an alloy containing lithium and aluminum is used in order to suppress reaction with the non-aqueous electrolytic solution during reflow. In addition,
In addition to lithium and aluminum, it is possible to include other elements such as lead, tin, magnesium, manganese, etc. within a range that does not deteriorate high temperature stability and charge / discharge characteristics.

Further, as the separator 3, it is preferable to use polyphenylene sulfide in order to suppress reaction with the non-aqueous electrolyte during reflow as described above. It is also possible to mix highly stable resins, or to mix inorganic fibers and cellulose resins in order to supplement strength.

As the non-aqueous electrolytic solution with which the separator 3 is impregnated, a suitable solute dissolved in a solvent containing sulfolane and 1,2-dimethoxyethane is preferably used. As the solvent, propylene carbonate is used together with sulfolane and 1,2-dimethoxyethane.

Further, in the above-mentioned solvent of the non-aqueous electrolyte, cyclic carboxylic acid esters such as ethylene carbonate and γ-butyrolactone, 1,2-diethoxyethane, 1,2- Add chain ethers such as ethoxymethoxyethane and diethylene glycol diethyl ether, chain carboxylic acid esters such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, chain esters such as methyl acetate, and cyclic ethers such as tetrahydrofuran. Is also possible.

The solute used in the above non-aqueous electrolyte is
For this reason, it is preferable to use a solute with excellent high temperature stability.
For example, lithium trifluoromethanesulfonate L
iCF₃SO₃, Lithium trifluoromethanesulfone
Acid imide LiN (CF₃SO ₂)₂, Lithium pentaf
Luoroethanesulfonic acid imide LiN (C₂F_FiveS
O ₂)₂, Lithium trifluoromethanesulfonate
De LiC (CF₃SO₂) ₃Etc., and
The concentration of this solute should be in the range of 0.3 to 1.5 mol / liter.
It is preferable to set it in the range of 0.5 to 1.
The range is 0 mol / liter.

In the above battery, the positive electrode case 4a and the negative electrode case 4b are made of stainless steel or the like and formed into a predetermined shape by press working.

Further, in order to enhance the conductivity between the positive electrode 1 and the positive electrode case 4a by providing the positive electrode current collector 5 between the positive electrode 1 and the positive electrode case 4a, graphite is formed on the inner surface of the positive electrode case 4a. A conductive paint or the like in which powder of water and water glass are mixed is applied, or a mesh-shaped current collector made of stainless steel, aluminum, titanium, or the like is provided.

In order to enhance the conductivity between the negative electrode 2 and the negative electrode case 4b by providing the negative electrode current collector 6 between the negative electrode 2 and the negative electrode case 4b, graphite is formed on the inner surface of the negative electrode case 4b. A conductive paint or the like in which powder of water and water glass is mixed is applied, or a mesh-shaped current collector made of stainless steel, copper, titanium, or the like is provided.

When polyphenylene sulfide and / or polyether ether ketone is used as the gasket 7 which is the above-mentioned insulating packing, the reaction with the non-aqueous electrolyte is suppressed during reflow,
In particular, when a cellulose resin is mixed, the reaction with the non-aqueous electrolyte solution during reflow is further suppressed, and the strength of the gasket is improved. Further, it is possible to mix another resin having high thermal stability as long as the thermal stability is not deteriorated.

[0042]

EXAMPLES Next, a substrate mounting lithium secondary battery according to a specific example satisfying the conditions of the present invention and a substrate mounting lithium secondary battery not satisfying the conditions of the present invention are compared. It is clarified that the lithium secondary battery for mounting on a substrate according to the embodiment of the present invention is excellent.

(Example 1) In Example 1, a positive electrode, a negative electrode and a non-aqueous electrolyte prepared as described below were used.
A flat coin-shaped lithium secondary battery for mounting on a substrate as shown in FIG. 1 was obtained.

[Preparation of Positive Electrode] In preparing a positive electrode, lithium hydroxide LiOH, boron oxide B ₂ O ₃ and manganese dioxide MnO ₂ were mixed at an atomic ratio of Li: B: Mn of 0.50: 0.01. : 1.00, mixed and heat-treated in air at 375 ° C. for 20 hours, pulverized to a specific surface area of 3 m ² / g, and a composite oxide of lithium, boron and manganese. To obtain a positive electrode active material. When the crystal structure of this positive electrode active material was examined by X-ray diffraction, it was confirmed that Li ₂ MnO ₃ (crystal system was monoclinic, space group was C2 / c) and MnO ₂ (because of low crystallinity) Although the crystal structure could not be analyzed, the crystal system was probably a cubic manganese oxide) and was a composite manganese oxide.

Then, this positive electrode active material, a conductive agent obtained by mixing graphite and acetylene black in a weight ratio of 1: 1 and polyfluoroethylene propylene were mixed in a weight ratio of 90: 5: 5. , This mixture was molded into a disc with a diameter of 4 mm and a thickness of 1.2 mm, and then 2 in vacuum.
A positive electrode was prepared by drying at 50 ° C. for 2 hours.

[Preparation of Negative Electrode] In preparing the negative electrode, a lithium-aluminum alloy is electrochemically prepared, and this lithium-aluminum alloy is punched out into a disk shape having a diameter of 4 mm and a thickness of 0.3 mm to form a negative electrode. It was made.

[Preparation of Non-Aqueous Electrolyte] In preparing the non-aqueous electrolyte, a solvent prepared by mixing sulfolane (SL) and 1,2-dimethoxyethane (DME) in a volume ratio of 30:70 is used. , Lithium trifluoromethanesulfonic acid imide LiN as a solute lithium salt in this solvent
(CF ₃ SO ₂ ) ₂ was dissolved to a concentration of 0.75 mol / liter to prepare a non-aqueous electrolytic solution.

Then, as shown in FIG. 1, on the negative electrode current collector 6 made of a stainless net, which is welded to the inner surface of the negative electrode case 4b made of stainless, the above negative electrode 2 and
The separator 3 made of polyphenylene sulfide and the positive electrode 1 are sequentially stacked, a gasket 7 which is an insulating packing made of polyphenylene sulfide is attached to the inner peripheral side of the negative electrode case 4b, and the nonaqueous electrolytic solution is injected. After doing
The positive electrode current collector 5 formed by coating a conductive coating material in which graphite powder and water glass are applied is covered with a positive electrode case 4a made of stainless steel, and the positive electrode 1 and the positive electrode current collector 5 are covered with each other. The positive electrode case 4a was brought into contact with it, and then the positive electrode case 4a was caulked and sealed to manufacture a lithium secondary battery for mounting a substrate of Example 1.

Example 2 In Example 2, lithium hydroxide LiOH and manganese manganese Mn (NO ₃ ) ₂ .6H ₂ O were mixed with Li: Mn atoms in the production of the positive electrode in Example 1 described above. Mix to give a ratio of 1.22: 1.78 and mix at 9 ° C in an oxygen flow at 800 ° C.
It was heat-treated for 6 hours and pulverized to a specific surface area of 0.5 m ² / g to obtain a positive electrode active material Li _1.22 Mn _1.78 O ₄ . When the crystal structure of this positive electrode active material was examined by X-ray diffraction, it was found to have a single-phase spinel structure (the crystal system is cubic and the space group is Fd3m).

Then, Example 1 was _repeated except that the positive electrode active material Li _1.22 Mn _1.78 O ₄ obtained as described above was used.
A lithium secondary battery for mounting a substrate of Example 2 was manufactured in the same manner as in the above case.

(Example 3) In Example 3, vanadium pentoxide V ₂ O ₅ was used as the positive electrode active material in the production of the positive electrode in Example 1 above, but otherwise, in Example 1 above. A lithium secondary battery for mounting a substrate of Example 3 was produced in the same manner as in the case of.

Comparative Example 1 In Comparative Example 1, only 1,2-dimethoxyethane (DME) was used as a solvent in the preparation of the nonaqueous electrolytic solution in Example 1 described above, and otherwise, In the same manner as in Example 1 above, a lithium secondary battery for mounting a substrate of Comparative Example 1 was produced.

(Comparative Example 2) In Comparative Example 2, sulfolane (SL) and γ-butyrolactone (γ-B) were used as solvents in the preparation of the non-aqueous electrolytic solution in Example 1 described above.
L) was mixed with the solvent in a volume ratio of 80:20, and a lithium secondary battery for mounting on a substrate of Comparative Example 2 was prepared in the same manner as in Example 1 except for the above. .

Comparative Example 3 In Comparative Example 3, sulfolane (SL) and propylene carbonate (P) were used as the solvent in the preparation of the non-aqueous electrolytic solution in Example 1 described above.
A solvent was prepared by mixing C) and C) in a volume ratio of 80:20, and otherwise the same as in Example 1 above, to prepare a lithium secondary battery for mounting on a substrate in Comparative Example 3. .

Comparative Example 4 In Comparative Example 4, as the negative electrode, a lithium metal punched into a disk shape having a diameter of 4 mm and a thickness of 0.3 mm was used.
A lithium secondary battery for mounting a substrate of Comparative Example 4 was produced in the same manner as in Example 1 above.

Next, Example 1 produced as described above.
About 3 to 3 and each of the lithium secondary batteries for mounting substrates of Comparative Examples 1 to 4, the voltage and the resistance were respectively inspected to prepare 5 batteries each having no defects such as a short circuit.

Then, after heating each of the five batteries of Examples 1 to 3 and Comparative Examples 1 to 4 at 180 ° C. for 1 minute,
Maximum temperature is 250 ℃, minimum temperature around the entrance is 180 ℃
After passing through the reflow furnace for 1 minute and then naturally cooling them to room temperature, the presence or absence of liquid leakage was examined, and the number of batteries leaking out of each of the 5 batteries was determined as shown in Table 1 below. It was shown to.

Then, using only the batteries which did not leak, the voltage and resistance were respectively checked to confirm that there was no defect such as a short circuit, and then each battery was charged at a constant charge current of 0.1 mA to a cutoff voltage of 3 mA. 0.1 after charging to 0.0V
It is discharged to a discharge end voltage of 2.0 V with a constant current of mA, and charging and discharging are repeated with this as one cycle, and the number of cycles until the discharge capacity becomes half of the discharge capacity of the first cycle is obtained, and the result is The results are shown in Table 1 below.

[0059]

[Table 1]

As is clear from these results, a lithium-aluminum alloy was used for the negative electrode and sulfolane (SL) and 1,2-dimethoxyethane (DM) were used for the non-aqueous electrolyte.
Each of the lithium secondary batteries for mounting a substrate of Examples 1 to 3 using the mixed solvent with E) was sulfolane (SL) in the non-aqueous electrolyte.
And a lithium secondary battery for mounting each substrate of Comparative Examples 1 to 3 which does not use a mixed solvent of 1,2-dimethoxyethane (DME) and a lithium secondary battery for mounting of Comparative Example 4 in which lithium metal is used as a negative electrode. Compared to the secondary battery, it showed less liquid leakage due to reflow and showed excellent charge-discharge cycle characteristics.

Further, when comparing the lithium secondary batteries for mounting a substrate of Examples 1 to 3, the lithium secondary batteries for mounting a substrate of Examples 1 and 2 using a manganese composite oxide as a positive electrode active material. In this case, liquid leakage due to reflow is more reliably prevented, and charge / discharge cycle characteristics are also improved. In particular, Li _1.22 Mn having a spinel structure as a positive electrode active material.
_The lithium secondary battery for mounting a substrate of Example 2 using _1.78 O ₄ exhibited excellent high temperature stability and further improved charge / discharge cycle characteristics.

(Examples 1.1 to 1.8) Examples 1.1 to
In 1.8, the volume ratio of sulfolane (SL) and 1,2-dimethoxyethane (DME) used as a solvent in the preparation of the non-aqueous electrolyte solution in Example 1 was changed, and Table 2 below is used. As shown, the volume ratio of SL to DME was 1:99 in Example 1.1, 3:97 in Example 1.2, 5:95 in Example 1.3, and Example 1.
4 at 10:90, Example 1.5 at 20:80,
40:60 in Example 1.6 and 5 in Example 1.7.
0:50, 70:30 in Example 1.8, and otherwise the same as Example 1 above.
A lithium secondary battery for mounting each substrate of 1 to 1.8 was produced.

The substrate-mounting lithium secondary batteries of Examples 1.1 to 1.8 produced as described above are the same as those of the substrate-mounting lithium secondary battery of Example 1 described above. Then, the presence or absence of liquid leakage due to reflow was examined, and the number of batteries that leaked out of each of the five batteries is shown in Table 2 below. Similarly to the case of the lithium secondary battery for mounting, the number of cycles until the discharge capacity became half of the discharge capacity in the first cycle was obtained, and the results are shown in Table 2 and FIG. 2 below.

[0064]

[Table 2]

As is clear from these results, a lithium-aluminum alloy was used for the negative electrode and sulfolane (SL) and 1,2-dimethoxyethane (DM) were used for the non-aqueous electrolyte.
In the lithium secondary battery for mounting a substrate of Example using a mixed solvent with E), Example 1 and Example in which the ratio of sulfolane (SL) in the non-aqueous electrolyte was in the range of 3 to 50% by volume. In each of the 1.2 to 1.7 lithium secondary batteries for mounting a substrate, liquid leakage due to reflow is suppressed,
It has excellent high-temperature stability, improved charge-discharge cycle characteristics, and a sulfolane (SL) ratio of 5-40.
Example 1 and Examples 1.3-1.
In each of the lithium secondary batteries for mounting a substrate of No. 6, charge / discharge cycle characteristics were further improved.

(Examples 1.9 to 1.11) Example 1.9
In Nos. 1 to 11, in the preparation of the nonaqueous electrolytic solution in Example 1 described above, three kinds of solvents were used for the nonaqueous electrolytic solution.

As shown in Table 3 below, in Example 1.9, sulfolane (SL), 1,2-dimethoxyethane (DME) and propylene carbonate (PC) were mixed at a volume ratio of 30:60:10. In Example 1.10, the solvent mixed with was mixed with sulfolane (SL), 1,2-dimethoxyethane (DME) and ethylene carbonate (EC) at a volume ratio of 30:60:10, Example 1.11 uses a solvent prepared by mixing sulfolane (SL), 1,2-dimethoxyethane (DME), and γ-butyrolactone (γ-BL) at a volume ratio of 30:60:10.
Except for this, the lithium secondary batteries for mounting the substrates of Examples 1.9 to 1.11 were produced in the same manner as in Example 1 above.

The substrate mounting lithium secondary batteries of Examples 1.9 to 1.11 produced as described above are the same as those of the substrate mounting lithium secondary battery of Example 1 described above. Then, the presence or absence of liquid leakage due to reflow was examined, and the number of batteries that leaked liquid out of each of the 5 batteries is shown in Table 3 below. Similarly to the case of the lithium secondary battery for mounting, the number of cycles until the discharge capacity became half of the discharge capacity in the first cycle was obtained, and the results are shown in Table 3 below.

[0069]

[Table 3]

As is clear from this result, an example using a solvent in which sulfolane (SL), 1,2-dimethoxyethane (DME) and propylene carbonate (PC) were mixed as the solvent of the non-aqueous electrolyte was used. The lithium secondary battery for mounting on a substrate of 1.9 is Example 1.10 and Example in which a solvent other than propylene carbonate (PC) is added in addition to sulfolane (SL) and 1,2-dimethoxyethane (DME). Compared with the lithium secondary battery for mounting a substrate of 1.11 and the lithium secondary battery for mounting a substrate of Example 1 in which propylene carbonate (PC) was not added, high stability at high temperature and excellent charging / discharging were obtained. The cycle characteristics are shown.

(Examples 1.12 to 1.15) Example 1.
In Nos. 12 to 1.15, the volumes of sulfolane (SL), 1,2-dimethoxyethane (DME), and propylene carbonate (PC) used as the solvent in the preparation of the nonaqueous electrolytic solution in Example 1.9 described above. The ratio was changed, and as shown in Table 4 below, the volume ratio of SL, DME, and PC was 30: 69: 1 in Example 1.12, and that of Example 1.
13: 30: 67: 3, Example 1.14: 30: 67: 3.
40:30, 30:30:40 in Example 1.15, and otherwise the same as in Example 1 above.
Lithium secondary batteries for mounting the substrates of Examples 1.12 to 1.15 were produced.

The substrate mounting lithium secondary batteries of Examples 1.12 to 1.15 produced as described above are the same as those of the substrate mounting lithium secondary battery of Example 1 described above. Then, the presence or absence of liquid leakage due to reflow was examined, and the number of the batteries that leaked out of each of the five batteries is shown in Table 4 below. Similarly to the case of the lithium secondary battery for mounting, the number of cycles until the discharge capacity became half of the discharge capacity in the first cycle was obtained, and the results are shown in Table 4 below.

[0073]

[Table 4]

As is clear from this result, a lithium secondary battery for mounting on a substrate using a mixed solvent of sulfolane (SL), 1,2-dimethoxyethane (DME) and propylene carbonate (PC) in the non-aqueous electrolyte. In a battery, propylene carbonate (P
Example 1 in which the proportion of C) was in the range of 3 to 30% by volume.
9. In each of the lithium secondary batteries for mounting a substrate of 9, Example 1.13 and Example 1.14, high stability at high temperature,
It showed better charge-discharge cycle characteristics.

(Example 1.16 and Example 1.17) In Example 1.16 and Example 1.17, the above-mentioned Example 1. As in the case of 9, sulfolane (SL) and 1,2
-A solvent in which dimethoxyethane (DME) and propylene carbonate (PC) were mixed at a volume ratio of 30:60:10 was used.

In the embodiment 1.16 and the embodiment 1.17, the embodiment 1 and the embodiment 1.9 described above are used.
In the above case, the material of the gasket 7 used in the battery was changed, and as shown in Table 5 below, in Example 1.16, a gasket made of polyether ether ketone was used, and in Example 1.17, cellulose was used. A gasket made of polyetheretherketone mixed with 30% by weight of a resin was used, and other than that, in the same manner as in Example 1 above, for mounting each substrate of Examples 1.16 and 1.17. A lithium secondary battery was produced.

Also, regarding the lithium secondary batteries for mounting substrates as in Examples 1.16 and 1.17 manufactured as described above, in the case of the lithium secondary batteries for mounting substrates as in Example 1 above. In the same manner as described above, the presence or absence of liquid leakage due to reflow was examined, and the number of batteries that leaked liquid out of each of the 5 batteries is shown in Table 5 below. Similarly to the case of the lithium secondary battery for mounting on a substrate, the number of cycles until the discharge capacity became half of the discharge capacity in the first cycle was obtained, and the results are shown in Table 5 below.

[0078]

[Table 5]

As is clear from this result, Example 1.16 in which polyetheretherketone or polyetheretherketone mixed with cellulose resin was used as the material of the gasket instead of polyphenylene sulfide
Also in each of the lithium secondary batteries for mounting a substrate of Example 1.17, liquid leakage due to reflow is suppressed, the high temperature stability is excellent, and the charge / discharge cycle characteristics are also improved. In particular, cellulose is used as a gasket material. Example 1.1 using polyetheretherketone mixed with resin
In the lithium secondary battery for mounting a substrate of No. 7, charge / discharge cycle characteristics were further improved.

(Examples 2.1 to 2.6) Example 2.1 to
In 2.6, in the production of the positive electrode active material in Example 2 described above, the ratio of mixing lithium hydroxide LiOH and manganese nitrate Mn (NO ₃ ) ₂ .6H ₂ O was changed.

Then, when mixing lithium hydroxide LiOH and manganese nitrate Mn (NO ₃ ) ₂ .6H ₂ O, the atomic ratio of Li: Mn was 1.0 in Example 2.1.
0: 2.00, and in Example 2.2, 1.05: 1.95.
In Example 2.3, 1.15: 1.85, Example 2.4: 1.30: 1.70, Example 2.5: 1.33: 1.67, Example 2: .6 is 1.36:
1.64, otherwise the above-mentioned Example 2
Each positive electrode active material shown in Table 6 below was prepared in the same manner as in the above case.

When the crystal structure of each of the positive electrode active materials was examined by X-ray diffraction, all the positive electrode active materials of Examples 2.1 to 2.5 had a single-phase spinel structure (crystal). Although the system was cubic and the space group was Fd3m), Example 2.6
In the positive electrode active material of No. ₃ , in addition to manganese oxide having a spinel structure, a small amount of Li ₃ MnO ₄ (orthorhombic crystal system, Pmnb space group) was mixed as impurities.

Then, in the same manner as in Example 1 except that each positive electrode active material produced as described above was used, the lithium secondary batteries for mounting substrates in Examples 2.1 to 2.6 were used. Was produced.

The substrate mounting lithium secondary batteries of Examples 2.1 to 2.6 produced as described above are the same as the substrate mounting lithium secondary battery of Example 1 described above. Then, the presence or absence of liquid leakage due to reflow was examined, and the number of the batteries that leaked out of each of the five batteries is shown in Table 6 below. Similarly to the case of the lithium secondary battery for mounting, the number of cycles until the discharge capacity became half of the discharge capacity in the first cycle was obtained, and the results are shown in Table 6 and FIG. 3 below.

[0085]

[Table 6]

As is clear from these results, when a lithium-aluminum alloy was used for the negative electrode and sulfolane (SL) and 1,2-dimethoxyethane (DME) were used as the solvent for the non-aqueous electrolyte, the On the positive electrode,
The value of x in Li _{1 + x} Mn _2-x O ₄ is 0.05 to 0.
In each of the lithium secondary batteries for mounting a substrate of Example 2 and Examples 2.2 to 2.5 using the positive electrode active material in the range of 33, liquid leakage during reflow was suppressed and it was excellent. It has high temperature stability and improved charge-discharge cycle characteristics. In particular, each of Example 2 and Examples 2.3 to 2.4 using the positive electrode active material in which the value of x in Li _{1 + x} Mn _2-x O _{4 was} in the range of 0.15 to 0.30. The lithium secondary battery for mounting on a substrate was more excellent in high temperature stability and further improved in charge / discharge cycle characteristics. In the substrate-installed lithium secondary battery of Example 2.6, the number of charge / discharge cycles was reduced because a small amount of manganese oxide other than the spinel structure was mixed in the positive electrode active material as described above. It is considered that this is because the positive electrode active material reacted with the non-aqueous electrolyte during reflow.

(Examples 2.7 to 2.12) Example 2.7
2 to 12.2, in the production of the positive electrode active material in Example 2 above, Li _1.22 Mn _1.78 O of the positive electrode active material was used.
The specific surface area was changed by changing the conditions for grinding ₄ .

Li as the positive electrode active material_1.22Mn
_1.78O_FourAs shown in Table 7 below, the specific surface area of
0.05m in Example 2.7²/ G, in Example 2.8
0.1 m ²/ G, 0.2 m in Example 2.9²/ G
In Example 2.10, 0.8 m²/ G in Example 2.
1.5 meters for 11²/ G, 1.8 in Example 2.12.
m²/ G.

Further, the lithium secondary batteries for mounting on substrates of Examples 2.7 to 2.12 were prepared in the same manner as in Example 1 except that each positive electrode active material thus prepared was used. It was made.

The substrate mounting lithium secondary batteries of Examples 2.7 to 2.12 produced as described above are the same as those of the substrate mounting lithium secondary battery of Example 1 described above. Then, the presence or absence of liquid leakage due to reflow was examined, and the number of batteries leaking out of each of the five batteries is shown in Table 7 below. Similarly to the case of the lithium secondary battery for mounting, the number of cycles until the discharge capacity became half of the discharge capacity in the first cycle was obtained, and the results are shown in Table 7 and FIG. 4 below.

[0091]

[Table 7]

As is clear from this result, the negative electrode
While using the um-aluminum alloy,
Sulfolane (SL) and 1,2-dimethoxyethane as solvent
When (DME) is used, a positive electrode is further applied to the positive electrode.
A comparison table of manganese oxides with a pinel structure
Area is 0.1-1.5m²Use the one in the range of / g
Each of the substrates of Example 2 and Examples 2.8 to 2.11.
Liquid lithium rechargeable battery for reflow
Leakage is suppressed and excellent high temperature stability
The discharge cycle characteristics were also improved. In particular, its specific surface area
0.2-0.8m ²/ G used in the range
Mounting of each substrate of Example 2, Example 2.9 and Example 2.10.
Lithium-ion rechargeable batteries for use in high temperature stability
Therefore, the charge / discharge cycle characteristics were further improved.

In the above embodiments and examples, a flat coin-shaped lithium secondary battery for mounting a substrate is shown, but the shape and size of the lithium secondary battery for mounting a substrate are limited. It is not something that will be done.

[0094]

As described in detail above, in the lithium secondary battery for mounting a substrate according to the present invention, a solvent containing sulfolane and 1,2-dimethoxyethane is used as the non-aqueous electrolyte, and lithium is used as the negative electrode. Since the alloy containing aluminum is used, when the lithium secondary battery for mounting the substrate is mounted on the substrate by reflow at a high temperature of about 230 ° C. to 270 ° C., the non-aqueous electrolyte is positive electrode or negative electrode, especially negative electrode. It has been suppressed to react with.

As a result, when the substrate mounting lithium secondary battery of the present invention is mounted on the substrate by reflowing or the like, the internal pressure of the battery rises and liquid leakage occurs, or the internal resistance of the battery rises. Was suppressed, and sufficient high temperature stability and charge / discharge characteristics were exhibited.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing an internal structure of a substrate mounting lithium secondary battery according to an embodiment of the present invention.

FIG. 2 is a first example of the present invention and Examples 1.1 to 1.8.
FIG. 6 is a diagram showing the relationship between the ratio of sulfolane (SL) in the solvent of the non-aqueous electrolyte solution and the number of charge / discharge cycles in each of the substrate-mounted lithium secondary batteries of FIG.

FIG. 3 is a second embodiment and a second embodiment to a second embodiment of the present invention.
In each lithium secondary battery for mounting on a substrate, the value of x in Li _{1 + x} Mn _2-x O ₄ used as the positive electrode active material,
It is a figure showing the relation with the number of charge / discharge cycles.

FIG. 4 is a second embodiment and a second embodiment of the present invention 2.7 to 2.1.
FIG. 2 is a diagram showing the relationship between the specific surface area of the positive electrode active material and the number of charge / discharge cycles in each of the lithium secondary batteries for mounting a substrate of No.

[Explanation of symbols]

1 positive electrode 2 Negative electrode 3 separator 4 battery case 4a Positive case 4b negative electrode case 5 Positive electrode current collector 6 Negative electrode current collector 7 gasket

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Maruo Jinno             2-5-3 Keihan Hondori, Moriguchi City, Osaka Prefecture             Within Yo Denki Co., Ltd. (72) Inventor Masahiro Imanishi             2-5-3 Keihan Hondori, Moriguchi City, Osaka Prefecture             Within Yo Denki Co., Ltd. (72) Inventor Nobuhiro Nishiguchi             2-5-3 Keihan Hondori, Moriguchi City, Osaka Prefecture             Within Yo Denki Co., Ltd. (72) Inventor Minoru Fujimoto             2-5-3 Keihan Hondori, Moriguchi City, Osaka Prefecture             Within Yo Denki Co., Ltd. F term (reference) 5H011 AA01 AA02 AA07 AA09 FF03                       GG02 HH02 HH12                 5H021 AA06 EE02                 5H029 AJ14 AJ15 AK02 AK03 AL12                       AM02 AM03 AM04 AM05 AM07                       BJ03 BJ12 CJ08 HJ02 HJ07                 5H050 AA19 AA20 BA16 CA09 CB12                       DA19 FA02 FA13 FA17 FA19                       GA10 HA02 HA07

Claims (15)

[Claims] 1. A lithium secondary battery for mounting on a substrate, comprising: a positive electrode, a negative electrode using an alloy containing lithium and aluminum, a non-aqueous electrolytic solution containing a solute and a solvent, The separator provided between the positive electrode and the negative electrode, a container for accommodating them, and a gasket for sealing the container, wherein the solvent contains sulfolane and 1,2-dimethoxyethane. Lithium secondary battery for board mounting. 2. The lithium secondary battery for mounting a substrate according to claim 1, wherein the lithium secondary battery for mounting a substrate is mounted on the substrate by automatic hunting by reflow. Next battery. 3. The lithium secondary battery for mounting on a substrate according to claim 1 or 2, wherein the ratio of sulfolane in the solvent of the non-aqueous electrolyte is in the range of 3 to 50% by volume. Lithium secondary battery for board mounting. 4. The substrate mounting lithium secondary battery according to claim 3, wherein the ratio of sulfolane in the solvent of the non-aqueous electrolyte is in the range of 5 to 40% by volume. Rechargeable lithium battery. 5. The lithium secondary battery for mounting on a substrate according to claim 1, wherein the solvent of the non-aqueous electrolyte is propylene carbonate together with the sulfolane and 1,2-dimethoxyethane. A lithium secondary battery for mounting on a substrate, comprising: 6. The lithium secondary battery for mounting on a substrate according to claim 5, wherein the proportion of propylene carbonate in the solvent of the non-aqueous electrolyte is in the range of 3 to 30% by volume. Lithium secondary battery for mounting. 7. The lithium secondary battery for mounting on a substrate according to claim 1, wherein manganese oxide is used as a material of the positive electrode. battery. 8. The lithium secondary battery for mounting on a substrate according to claim 7, wherein the crystal structure of the manganese oxide has a spinel structure. 9. The lithium secondary battery for mounting on a substrate according to claim 8, wherein the composition of the manganese oxide having a spinel structure is Li _{1 + x} Mn _2-x O ₄ (however,
The condition of 0.05 ≦ x ≦ 0.33 is satisfied. ) Is a lithium secondary battery for mounting on a substrate. 10. A substrate mounting Lithium according to claim 9.
In a secondary battery, a battery having the above spinel structure is used.
The composition of the gangan oxide is Li_{1 + x}Mn_2-xO _Four(However,
The condition of 0.15 ≦ x ≦ 0.30 is satisfied. ) Be
A lithium secondary battery for mounting on a substrate, which is characterized by: 11. The lithium secondary battery for mounting on a substrate according to claim 7, wherein the manganese oxide has a specific surface area of 0.1 to 1.5 m ² / g. A lithium secondary battery for mounting on a substrate, characterized in that 12. The substrate mounting lithium secondary battery according to claim 11, wherein the specific surface area of the manganese oxide is in the range of 0.2 to 0.8 m ² / g. Rechargeable lithium battery. 13. The lithium secondary battery for mounting on a substrate according to claim 1, wherein polyphenylene sulfide is used for the separator. 14. The substrate mounting lithium secondary battery according to claim 1, wherein polyphenylene sulfide and / or polyether ether ketone is used for the gasket. Rechargeable lithium battery. 15. The lithium secondary battery for mounting a substrate according to claim 14, wherein a cellulose resin is mixed in the gasket.