JP3380501B2 - Non-aqueous electrolyte secondary battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] TECHNICAL FIELD The present invention relates to a square non-aqueous electrolyte
Next battery. [0002] 2. Description of the Related Art In recent years, consumer mobile phones and portable telephones have been developed.
Rapid miniaturization and diversification of child devices and portable information terminals
As a result, the battery that is the power source is small, lightweight and
High energy density enables repeated charge and discharge for longer periods
There is a strong demand for the development of a viable secondary battery. in
Batteries and nickel cadmium that use aqueous electrolytes
Rechargeable batteries that meet these requirements compared to
Non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries
Are the most promising and active research is being conducted. The positive electrode active material of a non-aqueous electrolyte secondary battery includes
Titanium sulfide, vanadium pentoxide and molybdenum trioxide
Including lithium cobalt composite oxide, lithium
Nickel composite oxide and spinel lithium manganese
General formula LixMO such as oxide _Two(However, M is more than one kind
Of various transition metals) have been studied.
You. [0004] Among them, lithium cobalt composite oxide,
Lithium nickel composite oxide and spinel lithium
Manganese oxide and the like are 4V (vs. Li / Li⁺)
To charge and discharge at the extremely noble potential above
Battery with a high discharge voltage.
You. The negative electrode active material of the nonaqueous electrolyte secondary battery includes gold.
Lithium and other alloys containing lithium
Various materials such as carbon materials that can store and release
Although carbon materials are used,
There is an advantage that a battery having a long cycle life can be obtained. However, the non-aqueous electrolyte secondary
The pond has a certain amount of current that flows during charging for some reason.
When the battery is overcharged, the battery voltage increases and the electrolyte is separated.
Gas is generated and the internal pressure and temperature of the battery rise,
If this overcharge state continues, the rapid decomposition of the electrolyte and active material
Abnormal reaction may occur, causing the battery to rupture and damage.
You. As a countermeasure for such a problem, biphenyl is used in the electrolyte.
, Aromatization of 3-chlorothiophene and furan
Japanese Patent Application Laid-Open (JP-A) No. 9-10 / 1994
6835 and the like. However, these changes
The addition of the compound is effective against the above-mentioned battery rupture damage during overcharge.
Despite the effects, the battery's discharge characteristics, especially when left at high temperatures
There is a problem that the subsequent discharge characteristics are significantly deteriorated. [0008] SUMMARY OF THE INVENTION Therefore, the present invention
Excellent safety when charging and even after being left at high temperatures
Providing a prismatic non-aqueous electrolyte secondary battery with good discharge characteristics
Is to do. [0009] [MEANS FOR SOLVING THE PROBLEMS]
In addition, the present inventors have developed a material that occludes and releases lithium ions.
Positive electrode containing a substance and a substance that absorbs and releases lithium ions
A battery comprising a negative electrode comprising:
Therefore, the non-aqueous electrolyte is at least ethylene carbonate or
Contains carbonates such as propylene carbonate,
Add propane sultone and biphenyl to this.
And found that it was good. Then, propane sultone and biphenyl
The addition amount is 1 to 5% by weight based on the non-aqueous electrolyte.
I found something good. In this way, the overcharge
Suppresses battery rupture damage, and even after leaving batteries at high temperatures
It can have good discharge performance. That is, the rectangular non-aqueous electrolyte secondary battery of the present invention
Pond is a positive electrode containing a substance that absorbs and releases lithium ions
And a negative electrode containing a substance that absorbs and releases lithium ions
And a non-aqueous electrolyte, and the battery lid and the battery case are
Non-aqueous electrolyte secondary battery attached by laser welding
In the pond, the non-aqueous electrolyte contains carbonate and propane.
Contains sultone and biphenyl, and contains
Content of 1 to 5% by weight and content of biphenyl
Is 1 to 5% by weight. [0012] [0013] DESCRIPTION OF THE PREFERRED EMBODIMENTS Chemistry of biphenyl used in the present invention
The formula is shown in Chemical Formula 1. Also, the chemical formula of propane sultone has been
It is shown in FIG. [0014] Embedded image Embedded image Propane sultone is added at 1 to 5% by weight based on the non-aqueous electrolyte.
Add. If less than 1% by weight, after leaving the battery at high temperature
However, the effect of suppressing the deterioration of the discharge performance cannot be obtained.
%, The initial discharge capacity after battery assembly decreases
Because it will. Further, biphenyl is added to a non-aqueous electrolyte at a rate of 1%.
５5% by weight. If less than 1% by weight, overcharge
The effect of suppressing the rupture damage of the battery is not obtained.
If the amount is greater than%, the electricity is
This is because the initial discharge capacity after pond assembly is reduced.
You. If the added amount is too large, the initial discharge capacity will decrease.
The reason is that the viscosity of the electrolyte increases and the conductivity decreases.
It is. The positive electrode of the non-aqueous electrolyte secondary battery according to the present invention
Active materials include those that occlude and release lithium ions
Can be used. Specifically, LiMO_Two(T
However, M represents a basic structure represented by one or more transition metals).
Based on lithium transition metal composite oxide
Can be used alone or in combination of two or more.
In particular, because of the high discharge voltage, Co, Ni,
It is desirable to use by selecting from Mn. Also, Li
Mn_TwoO_FourLithium transition having basic structure represented by
Compounds mainly composed of metal composite oxides can be used
It is. As the negative electrode active material, cokes, glass
Carbons, graphites, non-graphitizable carbons, pyrolysis
Carbonaceous materials such as carbons and carbon fibers, or metal
Lithium, such as aluminum, lithium alloy, polyacene, etc.
Absorb and release substances, alone or as a mixture of two or more
Can be used.
It is desirable to use a base material. Carbonic acid used as a solvent for the non-aqueous electrolyte of the present invention
As esters, ethylene carbonate, propylene
Carbonate, butylene carbonate, vinylene carbonate
, Trifluoropropylene carbonate,
Chill carbonate, diethyl carbonate, methyl ethyl
Leucarbonate, dipropyl carbonate, methylpro
Pill carbonate, ethyl isopropyl carbonate,
Using dibutyl carbonate alone or two or more
These may be mixed and used. Further, as a solvent of the non-aqueous electrolyte of the present invention,
Is other than carbonate, propane sultone and biphenyl
Γ-butyrolactone, 2-methyl-γ-butyl lactone
, Acetyl-γ-butyrolactone, γ-valerolactone
, Sulfolane, 1,2-dimethoxyethane, 1,2-diethoxy
Cietan, tetrahydrofuran, 2-methyltetrahydro
Furan, 3-methyl-1,3-dioxolan, methyl acetate, vinegar
Ethyl acid, methyl propionate, ethyl propionate, etc.
May be contained. The electrolyte salt as a solute of the non-aqueous electrolyte is L
iCLO_Four, LiAsF₆, PiPF ₆, LiBF_Four, Li
CF_ThreeSO_Three, LiCF_ThreeCF_TwoSO_Three, LiCF_ThreeCF_TwoC
F_TwoSO_Three, LiN (CF_ThreeSO_Two)_Two, LiN (C_TwoF_FiveS
O_Two)_TwoEtc. may be used alone or as a mixture of two or more.
Can be. Among the electrolyte salts, LiPF₆Using
Preferably. [0021] EXAMPLES Examples of the present invention are described below together with comparative examples.
However, the present invention is limited by the present embodiment.
Not something. FIG. 1 shows the secondary non-aqueous electrolyte used in this embodiment.
It is a schematic sectional drawing of a battery. In FIG. 1, 1 is a square non-water
Electrolyte secondary battery, 2 is an electrode group, 3 is a positive electrode, 4 is a negative electrode, 5
Is a separator, 6 is a battery case, 7 is a lid, 8 is a safety valve,
9 is a positive electrode terminal and 10 is a positive electrode lead. This prismatic nonaqueous electrolyte secondary battery 1 is made of aluminum.
Positive current collector containing substances that occlude and release lithium ions
The following positive electrode 3 coated with an electrode mixture and lithium current collector
Apply a negative electrode mixture containing substances that occlude and release ions
And the following negative electrode 4 was wound via a separator 5
Flat-wound electrode group 2 and non-aqueous electrolyte containing electrolyte salt
Is stored in the battery case 6. A battery provided with a safety valve 8 in a battery case 6
The lid 7 is attached by laser welding and the positive terminal 9
Is connected to the positive electrode 3 via the positive electrode lead 10, and the negative electrode 4
It is electrically connected to the inner wall of the battery case 6 by contact.
You. The positive electrode mixture is LiCoO as an active material._Two90 weight
Parts, acetylene black 5 parts by weight of conductive material, and binding
5 parts by weight of polyvinylidene fluoride as an agent,
Chill-2-pyrrolidone is appropriately added and dispersed, and a slurry is prepared.
Was prepared. This slurry is made of 20 micron thick aluminum
After evenly coating and drying the current collector, press it with a roll press.
The positive electrode 3 was produced by compression molding. The negative electrode mixture was composed of 90 parts by weight of flaky graphite,
A mixture of 10 parts by weight of vinylidene refluoride and N-methyl
-2-Pyrrolidone is appropriately added and dispersed to prepare a slurry.
Made. This slurry is converted into a 10-micron thick copper current collector.
After uniform application and drying, compression molding with a roll press
Thereby, the negative electrode 4 was produced. The separator 5 has a fineness of 25 μm in thickness.
A porous polyethylene film was used. Using the above components, a width of 30 mm and a height of 30 mm
48mm thick 6mm square non-aqueous electrolyte secondary battery
Was. The non-aqueous electrolyte was prepared according to the following Examples and Comparative Examples.
Prepared as follows. Example 1 Ethylene carbonate (E
C) and a volume ratio of methyl ethyl carbonate (MEC) of 5
In a mixture of 0:50, LiPF₆1 mol / liter
5% by weight of propane sultone as an additive
% And biphenyl added by 3% by weight and dissolved.
It was used as an electrolyte for the water electrolyte secondary battery 1. Example 2 Propane Sult as an Additive
3% by weight and 3% by weight of biphenyl were added and dissolved
Was the same as in Example 1. Example 3 Propane Sult as an Additive
1% by weight and 3% by weight of biphenyl were added and dissolved
Was the same as in Example 1. Example 4 Propane Sult as an Additive
3% by weight and biphenyl 5% by weight
Was the same as in Example 1. Example 5 Propane Sult as an Additive
3% by weight and 1% by weight of biphenyl were added and dissolved.
Was the same as in Example 1. COMPARATIVE EXAMPLE 1 Propane Sult as an Additive
Example 1 except that no phenyl and biphenyl were added.
It was like. Comparative Example 2 Propane Sult as an Additive
Dissolve 3% by weight of benzene and do not add biphenyl
Except for the above, it was the same as Example 1. Comparative Example 3 Biphenyl was used as an additive
Dissolve by weight%, do not add propane sultone
Except for the above, it was the same as Example 1. Comparative Example 4 Propane Sult as an Additive
0.5% by weight of biphenyl and 0.5% by weight of biphenyl
The procedure was the same as in Example 1 except for the above. Comparative Example 5 Propane Sult as an Additive
And 10% by weight of biphenyl were added and dissolved.
The rest was the same as in Example 1. The batteries of Examples 1 to 5 and Comparative Examples 1 to 5
At a constant current and a constant voltage of 4.1 V at 25 ° C. and 1 C current.
After 3 hours, discharge at 25 ° C with a constant current of 1C.
Discharge to stop voltage 2.75V and measure initial discharge capacity
did. The above battery was charged at 60 ° C.
After leaving for 14 days, discharge is stopped at a constant current of 1C at 25 ° C.
Discharge to a voltage of 2.75V. Then, at 25 ° C, 1C
The constant current and constant voltage charging of 4.1 V was performed for 3 hours.
At a constant current of 1C at 25 ° C to a discharge end voltage of 2.75V.
And the discharge capacity of the battery after standing at high temperature was measured. The discharge capacity of the battery after being left at high temperature and the
The ratio of the discharge capacity of the battery before standing was taken as the recovery capacity. Sand
The higher the recovery capacity of the battery, the better the high-temperature storage performance of the battery
It will be good. Table 1 shows the test results. Next, in Examples 1 to 5 and Comparative Examples 1 to 5,
Continuous charging with 2A charging current using 20 batteries each
Battery explosion when the battery is overcharged.
The birth rate was investigated. The above-mentioned batteries of Examples 1 to 5 and Comparative Examples 1 to 5
Initial discharge capacity, recovery capacity when left at high temperatures, breakage when overcharged
Table 1 shows the crack damage occurrence rate. [0045] [Table 1] As shown in Examples 1 to 5 in Table 1,
Tylene carbonate (EC) and methyl ethyl carbonate
(MEC) in a 50:50 volume ratio of LiPF₆
In a solution of 1 mol / l dissolved in propane sultone
1-5% by weight and biphenyl 1-5% by weight
Batteries with an initial electrolyte discharge capacity and high temperature
The recovery capacity at the time and the overcharge resistance are both good. Further, from Comparative Examples 1 and 2 and Comparative Example 4,
If the amount of biphenyl added is 0.5% by weight or less,
The rate of occurrence of rupture damage during charging increased, and Comparative Example 3 and
And Comparative Example 4, the amount of propane sultone added was 0.5 times
%, The recovery capacity after leaving at high temperatures is small.
In comparison with Comparative Example 5, the amount of propane sultone added was 1
0% by weight or more and the amount of biphenyl added to 10% by weight or more
If so, the initial discharge capacity is reduced, which is not preferable. Example 6 Ethylene carbonate (E
C), methyl ethyl carbonate (MEC) and propio
Liquid mixture of methyl phosphate (MP) at a volume ratio of 50:25:25
And LiPF₆Is added to a solution of
3% by weight of propane sultone as additive and biphenyl 3
The above-mentioned prismatic non-aqueous electrolyte secondary battery in which
1 was used as the electrolytic solution. Example 7 The solvent used for the electrolytic solution was ethyl
Carbonate (EC) and methyl ethyl carbonate
(MEC) and 1,2-dimethoxyethane (DME) volume ratio
Same as Example 6 except that the mixture was 50:25:25.
It was like. Example 8 The solvent used for the electrolytic solution was ethyl
Carbonate (EC) and methyl ethyl carbonate
(MEC) and diethyl carbonate (DEC) volume ratio
Same as Example 6 except that the mixture was 50:25:25.
It was like. Example 9 The solvent used for the electrolytic solution was ethyl
Carbonate (EC) and dimethyl carbonate (DM
Example 1 except that the mixed solution of C) was in a volume ratio of 50:50.
Same as 6. Using the batteries of Examples 6 to 9 as described above,
Table 2 shows the results of the high-temperature storage test and the overcharge test.
Shown in [0052] [Table 2] As shown in Examples 6 to 9 in Table 2,
Methyl propionate (MP) or 1,2-dimethoate
When xyethane (DME) is added, the solvent of the electrolyte
Diethyl carbonate (DEC) as carbonate ester
Even when methyl carbonate (DMC) is added,
Dissolve and add propane sultone and biphenyl
Discharged batteries have initial discharge capacity and recovery capacity when left at high temperatures.
Both the amount and the overcharge resistance were good. From the above results, a small amount of non-aqueous electrolyte
At least carbonate carbonate such as ethylene carbonate (EC)
1% to 5% by weight of propane sultone
And 1 to 5% by weight of biphenyl,
After leaving the battery at high temperature while suppressing the rupture damage of the battery during overcharge
Of the recovery capacity can be suppressed. Effect by adding propane sultone
Fruit is remarkable, and the details of its mechanism of action are not clear.
However, 1-5% by weight of propane sultone is added to the electrolyte.
To prevent decomposition of the electrolyte when left at high temperatures.
Therefore, capacity deterioration should not be suppressed.
It is thought. Also, the amount of propane sultone added
Exceeds 5% by weight and the amount of biphenyl added exceeds 5% by weight
If the initial discharge capacity of the battery is
Because the viscosity of the electrolyte increases because the concentration of the additive increases
Is considered to be caused by the inhibition of the discharge reaction
You. [0056] The battery according to the present invention is a battery for overcharging.
Of recovery capacity after high-temperature storage while suppressing rupture damage of steel
It is possible to provide a good battery that can suppress
Wear.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing one embodiment of the present invention, and is a longitudinal sectional view of a prismatic nonaqueous electrolyte secondary battery. [Description of Signs] 1 Non-aqueous electrolyte secondary battery 2 Electrode group 3 Positive electrode 4 Negative electrode 5 Separator 6 Battery case 7 Cover 8 Safety valve 9 Positive electrode terminal 10 Positive electrode lead

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-102173 (JP, A) JP-A-11-162511 (JP, A) JP-A-10-321258 (JP, A) JP-A 9-102 171840 (JP, A) JP-A-9-106835 (JP, A) JP-A-11-31523 (JP, A) JP-A-11-47920 (JP, A) JP-A-10-241651 (JP, A) JP-A-9-213286 (JP, A) JP-A-10-228888 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 10/40

Claims (1)

(57) [Claims] (1) A positive electrode composed of a substance that absorbs and releases lithium ions, a negative electrode composed of a substance that absorbs and releases lithium ions, and a non-aqueous electrolyte equipped with a door, electricity
The lid and battery case are attached by laser welding.
In prismatic nonaqueous electrolyte secondary battery, the nonaqueous electrolytic solution contains a carbonic acid ester and propane sultone and biphenyl
And the content of propane sultone in the electrolyte is 1 to 5 weight
% And a prismatic nonaqueous electrolyte secondary battery, wherein the amount of biphenyl is 5 weight percent.