JPH09161844A - Nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower interface energy between a nonaqueous electrolyte and an electrode, to improve load and electric discharge characteristics, by adding a specific nonionic interface active agent to the solvent of a nonageous electrolyte. SOLUTION: Solute such as LiPF6 , LiBF4 , LiCF3 , and a nonionic interface active agent of 1×10<-5> -3×10<-1> mol/l having an HLB value of 15 or less are added to the solvent of a nonaqueous electrolyte to obtain a nonaqueous electrolyte. A separator 3 is interposed between positive and negative electrodes 1 and 2 to be spirally wound to be housed in a battery can 4. The nonaqueous elecdrolyte is injected into the battery can 4 to seal the battery can 4, and the positive electrode 1 is connected to a positive electrode external terminal 6 via a positive electrode lead 4, and also the negative electrode 2 is connected to the battery can 4 via a negative electrode lead 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte battery provided with a positive electrode, a negative electrode, and a non-aqueous electrolyte solution, and particularly to a low interfacial energy between the non-aqueous electrolyte solution and each electrode to diffuse ions. The present invention relates to a non-aqueous electrolyte battery having excellent properties and good load characteristics.

[0002]

2. Description of the Related Art In recent years, as one of new high-output and high-energy-density secondary batteries, a non-aqueous electrolyte is used as an electrolyte and discharge and charge are performed by utilizing oxidation reduction of lithium or the like. Non-aqueous electrolyte batteries have come into use.

Here, in such a non-aqueous electrolyte battery, generally, the interfacial energy between the positive electrode or the negative electrode and the non-aqueous electrolyte is high, and the diffusibility of ions such as lithium ions at this interface becomes poor. The load characteristics were low, the discharge characteristics at large currents were poor, and there was a problem in using it in equipment that requires large currents.

For this reason, in recent years, Japanese Patent Laid-Open No. 63-
As disclosed in Japanese Patent Laid-Open No. 236258, Japanese Patent Laid-Open No. 5-335018, etc., disclosed is one in which a surfactant is added to the positive electrode and the negative electrode.

However, when a surfactant is added to the positive electrode and the negative electrode as described above, there is a problem that the volume energy density and the weight energy density of these electrodes are lowered and the charge and discharge characteristics are deteriorated.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems in a non-aqueous electrolyte battery comprising a positive electrode, a negative electrode and a non-aqueous electrolyte solution. The interface energy between each electrode and each electrode is lowered to enhance the diffusivity of ions such as lithium ions at the interface, and the load characteristics are high, and the discharge characteristics at large currents are good, making it suitable for equipment that requires large currents. It is also an object of the present invention to provide a non-aqueous electrolyte battery which is excellent in charge and discharge characteristics and which can be suitably used and which does not lower the energy density.

[0007]

In order to solve the above problems, in the present invention, in a non-aqueous electrolyte battery comprising a positive electrode, a negative electrode and a non-aqueous electrolyte solution, the solvent in the non-aqueous electrolyte solution is used. The nonionic surfactant having an HLB value of 15 or less was added in the range of 1 × 10 ^{−5 to} 3 × 10 ⁻¹ mol / l.

Then, as in the non-aqueous electrolyte battery of the present invention, a non-ionic surfactant having an HLB value of 15 or less is added to the solvent in the non-aqueous electrolyte solution at 1 × 10 ^{−5 to} 3 × 1.
When 0 ⁻¹ mol / l is added, the nonionic surfactant lowers the interfacial energy between the nonaqueous electrolytic solution and each electrode, and enhances the diffusibility of ions such as lithium ions at this interface, thus increasing the load characteristics. Is improved and the discharge characteristics at a large current are improved, and a non-aqueous electrolyte battery suitable for use in a device requiring a large current can be obtained.

Here, the nonionic surfactant added to the solvent of the above non-aqueous electrolyte has an HLB value of 15 or less. The reason is that an HLB value higher than this is used. This is because this surfactant is decomposed at the time of charging / discharging and the like and the load characteristics cannot be improved. Therefore, it is preferable to use a nonionic surfactant having an HLB value of 6 or less.

Examples of the nonionic surfactant having an HLB value of 15 or less are polyoxyethylene nonylphenyl ethers having an oxyethylene number of 1 to 15 and polyoxyethylene ( 8) Dodecyl ether, sorbitan monostearate, stearic acid monoglyceride, etc. can be used.

When such a nonionic surfactant is added to the solvent, the addition amount is 1 × 10 ^{-5 to} 3
The amount of × 10 ^-1 mol / l was selected because the amount was 1 × 10 ^-5 m
If it is less than ol / l, the interfacial energy cannot be sufficiently reduced by the nonionic surfactant, and the load characteristics cannot be sufficiently improved, while the amount is 3 ×.
If it is more than 10 ^-1 mol / l, the viscosity of the non-aqueous electrolyte increases due to the nonionic surfactant, the ionic conductivity of lithium ions and the like in the nonaqueous electrolyte decreases, and the diffusion rate of the ions increases. This is because the internal resistance of the non-aqueous electrolyte battery increases and the load characteristics deteriorate.

The solvent of the non-aqueous electrolyte to which the above nonionic surfactant is added is, for example, propylene carbonate, ethylene carbonate, γ-butyrolactone, dimethyl carbonate, dimethyl sulfoxide, acetonitrile, butylene carbonate, 1,
A known organic solvent such as 2-dimethoxyethane or diethyl carbonate can be used.

When lithium is used as an active material, examples of solutes to be added to the above-mentioned solvent in the non-aqueous electrolyte include lithium trifluoromethanesulfonate LiCF ₃ SO ₃ and lithium hexafluorophosphate Li.
Known lithium compounds such as PF ₆ , lithium tetrafluoroborate LiBF ₄ , lithium perchlorate LiClO ₄ , and trifluoromethanesulfonic acid imide lithium LiN (CF ₃ SO ₂ ) ₂ can be used, and a non-aqueous electrolyte battery can be used. Among these solutes, LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , and especially LiPF ₆ are preferably used from the viewpoint of improving the load characteristics of the above.

When lithium is used as the active material as described above, a metal compound capable of inserting and extracting lithium can be used as the positive electrode material. For example, manganese, cobalt, nickel, vanadium, A transition metal oxide containing at least one of niobium can be used, and as the negative electrode material, metallic lithium, an alloy capable of inserting and extracting lithium, an oxide, a carbon material, and the like can be used. .

[0015]

EXAMPLES Hereinafter, the non-aqueous electrolyte battery according to the present invention will be specifically described with reference to Examples, and comparative examples will be given to describe the non-aqueous electrolyte batteries according to Examples of the present invention in terms of load characteristics and the like. Make it clear that you are good. However, the non-aqueous electrolyte battery according to the present invention is not limited to the ones shown in the following examples, and can be implemented by appropriately changing it without departing from the scope of the invention.

(Examples 1 to 3 and Comparative Examples 1 to 3) In these Examples 1 to 3 and Comparative Examples 1 to 3, the positive electrode and the negative electrode were prepared as follows, and the non-aqueous electrolyte solution was used. Was prepared as follows and had a diameter of 14 m as shown in FIG.
A cylindrical non-aqueous electrolyte battery having an m and a height of 50 mm was obtained.

[Production of Positive Electrode] In producing a positive electrode, lithium-containing cobalt dioxide Li is used as a positive electrode active material.
Using CoO ₂ , 90 parts by weight of this LiCoO ₂ powder, 5 parts by weight of artificial graphite powder as a conductive agent, and 5 parts by weight of polyvinylidene fluoride as a binder were added to an N-methylpyrrolidone solvent, and these were added. A slurry was prepared by kneading. Then, this slurry was applied to both surfaces of an aluminum foil, which is a positive electrode current collector, by a doctor blade method, and this was vacuum dried at 150 ° C. for 2 hours to produce a positive electrode.

[Preparation of Negative Electrode] When preparing a negative electrode, natural graphite powder was used as the active material, and 95 parts by weight of this natural graphite powder and 5 parts by weight of polyvinylidene fluoride as a binder were added to N-. A methylpyrrolidone solvent was added, and these were kneaded to prepare a slurry. And this slurry was apply | coated to both surfaces of the copper foil which is a negative electrode collector by the doctor blade method, and this was vacuum-dried at 150 degreeC for 2 hours, and the negative electrode was produced.

[Preparation of Non-Aqueous Electrolyte] In preparing the non-aqueous electrolyte, a mixed solvent prepared by mixing ethylene carbonate and diethyl carbonate in a volume ratio of 1: 1 was used as the solvent. In Examples 1 to 3 and Comparative Examples 2 and 3, polyoxyethylene (8) dodecyl ether C ₁₂ H ₂₅ -having an HLB value of 12.7 was used in this mixed solvent.
A nonionic surfactant composed of O— (CH ₂ CH ₂ O) ₈ H was added at the ratio shown in Table 1 below, while in Comparative Example 1, no such surfactant was added. . Then, LiPF ₆ as a solute was dissolved in these solvents at a ratio of 1 mol / l to prepare each nonaqueous electrolytic solution.

[Fabrication of Battery] And these examples 1
3 and Comparative Examples 1 to 3, as shown in FIG.
A lithium-ion permeable polypropylene microporous film is interposed as a separator 3 between the positive electrode 1 and the negative electrode 2 produced as described above, and these are spirally wound and housed in a battery can 4. After that, each of the above non-aqueous electrolytes is injected into each battery can 4 and sealed, and the above positive electrode 1
Was connected to the positive electrode external terminal 6 via the positive electrode lead 5, while the negative electrode 2 was connected to the battery can 4 via the negative electrode lead 7 to produce each non-aqueous electrolyte battery.

Next, the first embodiment manufactured as described above was used.
~ 3 and each of the non-aqueous electrolyte batteries of Comparative Examples 1 to 3 was charged to 4.2 V at an hour rate and then discharged to 2.75 V at an hour rate to obtain a low rate in each of the non-aqueous electrolyte cells. While obtaining the battery capacity, the high rate battery capacity in each non-aqueous electrolyte battery was obtained by charging to 4.2V at a 1-hour rate and then discharging to 2.75V at a 5-hour rate. From these results, the following formula ( The load characteristics of each non-aqueous electrolyte battery were obtained according to 1), and the results are also shown in Table 1 below. Load characteristics = High rate battery capacity / Low rate battery capacity (1)

[0022]

[Table 1]

As is clear from this result, a surfactant containing polyoxyethylene (8) dodecyl ether having an HLB value of 12.7 was added to the solvent in an amount of 1 × 10 ^{-5 to} 3 × 1.
The non-aqueous electrolyte batteries of Examples 1 to 3 added in the range of 0 ⁻¹ mol / l were the non-aqueous electrolyte batteries of Comparative Example 1 in which such a surfactant was not added, and Comparative Examples 2 and As in the non-aqueous electrolyte battery of Example 3, the amount of this surfactant was 1 × 10 5.
^{-5 to} 3 × 10 ^-1 mol / l, the load characteristics were higher and the discharge characteristics at large currents were significantly improved, and the large currents were It has become possible to suitably use it for necessary equipment.

(Examples 4 to 6 and Comparative Examples 4 and 5) In these Examples 4 to 6 and Comparative Examples 4 and 5, the case of the above Examples 1 to 3 and Comparative Examples 1 to 3 and non-aqueous Only the surfactant added to the mixed solvent of the electrolytic solution was changed, and in these Examples and Comparative Examples, the HL shown in Chemical Formula 1 below was used.
A polyoxyethylene (8) nonylphenyl ether having a B value of 12.4 was added at the ratio shown in Table 2 below, and otherwise, a cylindrical type as shown in FIG. 1 was obtained in the same manner as in the above case. A non-aqueous electrolyte battery was prepared.

[0025]

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The load characteristics of the nonaqueous electrolyte batteries of Examples 4 to 6 and Comparative Examples 4 and 5 were measured in the same manner as in the above case, and the results are shown in Table 2. .

[0027]

[Table 2]

As is clear from this result, also in this case, the HLB value with respect to the solvent is 12.4, as in the above case.
Each of the non-aqueous electrolyte batteries of Examples 4 to 6 to which the surfactant of Example 1 was added in the range of 1 × 10 ^{−5 to} 3 × 10 ⁻¹ mol / l had the same amount of the surfactant as in Comparative Examples 4 and 5. Is less than the above range non-aqueous electrolyte battery, compared to many non-aqueous electrolyte batteries, both have high load characteristics, discharge characteristics at large current has been significantly improved, for devices that require large current, etc. It was suitable for use.

(Examples 7 to 9 and Comparative Examples 6 and 7) Also in these Examples 7 to 9 and Comparative Examples 6 and 7, a surfactant added to the mixed solvent of the above case and the non-aqueous electrolyte solution. Only in these examples and comparative examples,
The sorbitan monostearate having an HLB value of 4.7 shown in Chemical Formula 2 below was added at the ratio shown in Table 3 below, and otherwise, the cylindrical shape shown in FIG. 1 was obtained in the same manner as in the above case. A non-aqueous electrolyte battery was produced.

[0030]

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The load characteristics of the nonaqueous electrolyte batteries of Examples 7 to 9 and Comparative Examples 6 and 7 were measured in the same manner as in the above case, and the results are shown in Table 3 together. .

[0032]

[Table 3]

As is clear from this result, also in this case, as in the case described above, 1 × 10 ^{−5 to} 3 × 10 ⁻¹ mol / l of the surfactant having an HLB value of 4.7 was added to the solvent. The non-aqueous electrolyte batteries of Examples 7 to 9 added in the range of are compared to non-aqueous electrolyte batteries in which the amount of the surfactant is less than the above range as in Comparative Examples 6 and 7, and non-aqueous electrolyte batteries in which the amount is large. All of them have improved load characteristics and significantly improved discharge characteristics at large currents, and are suitable for use in devices that require large currents, and have HLB values of 6 or more. The load characteristics were also improved as compared with the non-aqueous electrolyte batteries of Examples 1 to 6 using the above-mentioned surfactant.

(Examples 10 to 12 and Comparative Examples 8 and 9) Also in these Examples 10 to 12 and Comparative Examples 8 and 9,
By changing only the surfactant added to the above case and the mixed solvent of the non-aqueous electrolytic solution, in these Examples and Comparative Examples, stearic acid monoglyceride C ₁₇ H ₂₅ COOCH ₂ CH ₂ having an HLB value of 3.8 was used. (OH) CH (OH) was added in the ratio shown in Table 4 below, and otherwise,
The cylindrical non-aqueous electrolyte battery shown in FIG. 1 was produced in the same manner as in the above case.

The load characteristics of the nonaqueous electrolyte batteries of Examples 10 to 12 and Comparative Examples 8 and 9 were measured in the same manner as in the above case, and the results are also shown in Table 4. .

[0036]

[Table 4]

As is apparent from this result, also in this case, as in the case described above, 1 × 10 ^{−5 to} 3 × 10 ⁻¹ mol / l of the surfactant having an HLB value of 3.8 was added to the solvent. The non-aqueous electrolyte batteries of Examples 10 to 12 added in the range of 10 to 12 are compared to the non-aqueous electrolyte batteries in which the amount of the surfactant is less than the above range as in Comparative Examples 8 and 9 and the non-aqueous electrolyte batteries in which the amount is large. All of them have improved load characteristics and significantly improved discharge characteristics at large currents, and are suitable for use in devices that require large currents, and have HLB values of 6 or more. The load characteristics were improved as compared with those of the above Examples 1 to 6 in which the above-mentioned surfactant was used.

Comparative Examples 10 to 14 These Comparative Examples 10
In each of Examples 14 to 14, polyoxyethylene having a HLB value of 15.8, which is higher than 15, is changed in the above cases and only the surfactant added to the mixed solvent of the nonaqueous electrolytic solution is changed. (20) Dodecyl ether C _{12
H 25 -O- (CH 2 CH 2} O) was added to ₂₀ H in a proportion shown in Table 5 below, for otherwise, the non-aqueous electrolyte becomes cylindrical as shown in FIG. 1 in the same manner as described above A battery was made.

The load characteristics of each of the non-aqueous electrolyte batteries of Comparative Examples 10 to 14 were measured in the same manner as above, and the results are shown in Table 5.

[0040]

[Table 5]

From these results, in these comparative examples, since the surfactant having the HLB value of 15.8, which is higher than 15, was used, the ratio of adding this surfactant was 1 × 1.
Even in the range of 0 ^{-5 to} 3 × 10 ^-1 mol / l, the load characteristics were inferior to those of the nonaqueous electrolyte batteries of the above examples.

(Examples 13 to 18 and Comparative Examples 15 to 1)
7) Also in these Examples 13 to 18 and Comparative Examples 15 to 17, only the surfactant added to the mixed solvent of the non-aqueous electrolyte solution was changed in the above cases, and in these Examples and Comparative Examples, As a surfactant, polyoxyethylene (n) nonylphenyl ether represented by the general formula shown in Chemical Formula 3 below is used in an amount of 1 × 10 ^{−3 with} respect to the mixed solvent.
mol / l was added, and the value of n in polyoxyethylene was changed as shown in Table 6 below.
A cylindrical non-aqueous electrolyte battery shown in FIG. 1 was produced in the same manner as in the above case except that each surfactant having a different LB value was used.

[0043]

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The load characteristics of the nonaqueous electrolyte batteries of Examples 13 to 18 and Comparative Examples 15 to 17 were measured in the same manner as in the above case, and the results are shown in Table 6 below. Indicated.

[0045]

[Table 6]

As is clear from these results, each of the nonaqueous electrolyte batteries of Examples 13 to 18 in which a surfactant having an HLB value of 15 or less was added to the solvent of the nonaqueous electrolytic solution had an interface having an HLB value of more than 15. Compared to the non-aqueous electrolyte batteries of Comparative Examples 15 to 17 to which an activator was added, the load characteristics became higher and the discharge characteristics at large currents were significantly improved, and for devices that require large currents, etc. It was suitable for use.

(Examples 19 to 24) In the non-aqueous electrolyte batteries in these examples, the following HLB value of 5.7 was obtained as a surfactant for the mixed solvent in the non-aqueous electrolyte solution. 1 × 10 ⁻³ mol / l of polyoxyethylene (2) nonylphenyl ether shown in Chemical formula 4
And the type of solute to be added to the mixed solvent containing such a surfactant is changed as shown in Table 7 below, and each of these solutes is added in an amount of 1 mol.
The non-aqueous electrolyte solution was prepared by dissolving at a ratio of 1 / l, and otherwise the cylindrical non-aqueous electrolyte battery shown in FIG. 1 was prepared in the same manner as in the above cases.

[0048]

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The load characteristics of each of the nonaqueous electrolyte batteries of Examples 19 to 24 were measured in the same manner as in the above case, and the results are shown in Table 7 below.

[0050]

[Table 7]

As is clear from these results, each of the non-aqueous electrolyte batteries of these examples exhibits high load characteristics, and among these solutes, LiPF ₆ , LiBF ₄ ,
When LiCF ₃ SO ₃ is used, especially when LiPF ₆ is used, the load characteristics are further improved, and it is suitable for charging / discharging with a larger current, and is suitable for devices that require a large current. Was ready for use.

[0052]

As described above in detail, in the non-aqueous electrolyte battery of the present invention, the solvent of the non-aqueous electrolyte is
1 x 10 nonionic surfactant with HLB value of 15 or less
^{Since -5 to} 3 × 10 ^-1 mol / l is added, the volume energy density and the weight energy density of the electrode are not lowered unlike the case where the surfactant is added in the positive electrode or the negative electrode. The nonionic surfactant lowers the interfacial energy between the non-aqueous electrolyte and each electrode to enhance the diffusivity of ions such as lithium ions, and has good load characteristics and good discharge characteristics at large currents. A non-aqueous electrolyte battery that can be suitably used for a device that requires an electric current was obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional explanatory view showing an internal structure of a non-aqueous electrolyte battery in each of Examples and Comparative Examples.

[Explanation of symbols]

 1 Positive electrode 2 Negative electrode

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Koji Nishio 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (2)

[Claims] 1. A non-aqueous electrolyte battery comprising a positive electrode, a negative electrode and a non-aqueous electrolyte, wherein the solvent in the non-aqueous electrolyte is:
1 x 10 nonionic surfactant with HLB value of 15 or less
^{-5 to} 3 × 10 ^-1 mol / l added in a non-aqueous electrolyte battery. 2. The non-aqueous electrolyte battery according to claim 1, wherein at least one lithium salt selected from LiPF ₆ , LiBF ₄ , and LiCF ₃ SO _{3 is} added as a solute to the solvent in the non-aqueous electrolyte solution. A non-aqueous electrolyte battery characterized by being added.