JP2004055253A - Non-aqueous secondary battery and electronic device using the same - Google Patents

Abstract

An object of the present invention is to provide a non-aqueous secondary battery that ensures both safety and suppression of self-discharge, and an electronic device using the same.
A non-aqueous secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte contains 0.5 to 15% by mass of a non-ionic compound having an alkyl group bonded to an aromatic ring. 1 to 10000 ppm of an aromatic, phosphite-based, or quinone-based aromatic compound containing an amine-based aromatic, a sulfide-based aromatic, or R-SLi (R is a substituent containing an aromatic group such as an allyl group) Non-aqueous secondary batteries contained. Further, it is preferable that the non-aqueous electrolyte contains 1 to 12% by mass of a halogenated aromatic compound. An electronic device including the non-aqueous secondary battery may be charged with a current of 1 C or more.
[Selection diagram] Fig. 1

Description

【００８２】
※　ただし、比較例７は厚み２７μｍのセパレータ使用
【００８３】
実施例１〜１２の電池は、非水電解質中に芳香族環にアルキル基が結合した非イオン性化合物とアミン系芳香族、スルフィド系芳香族またはＲ−ＳＬｉで示される（Ｒはアリル基など芳香族を含む置換基）芳香族、ホスファイト系芳香族、キノン系芳香族を用いることで、安全性と自己放電抑制の両方が達成できた。
【００８４】
一方、比較例１〜７の電池は、安全性の確保または自己放電の抑制のいずれかが達成できなかった。
【００８５】
次に、本発明の実施例１、４、７，１０と比較例１〜４の電池を携帯電話の電源として用い、保護回路や充電回路が破損した場合を想定して、保護回路、ＰＴＣ、電圧制御回路を機能しなくしてから０．６Ａ（１．０Ｃ）の電流で電源電圧１２Ｖまで充電し、その後５．５Ｖで定電圧充電を行った。その結果、比較例１〜４の電池を用いた携帯機器ではいずれの電流値でも最高電池表面温度が２０℃以上高くなっており、特に１Ａの場合は機器の破損もあった。この実験では保護回路、ＰＴＣ、電圧制御回路を機能しないようにしたがそれぞれの保護機能を付加することで携帯電子機器の信頼性がさらに向上することは言うまでもない。
【００８６】
【発明の効果】
以上で説明したように、本発明は、正極、負極および非水電解質を備えた非水二次電池であって、前記非水電解質が、芳香族環にアルキル基が結合した非イオン性化合物を０．５〜１５質量％含有し、かつアミン系芳香族、スルフィド系芳香族またはＲ−ＳＬｉで示される（Ｒはアリル基など芳香族を含む置換基）芳香族、ホスファイト系芳香族、キノン系芳香族を１〜１００００ｐｐｍ含有している非水二次電池とすることにより、安全性の確保と自己放電抑制とを両立させた非水二次電池およびそれを用いた電子機器を提供できる。
【図面の簡単な説明】
【図１】本発明に係る非水二次電池の一例を模式的に示す図であり、（ａ）はその平面図、（ｂ）はその部分縦断面図である。
【符号の説明】
１　正極
２　負極
３　セパレータ
４　電池ケース
５　絶縁体
６　電極積層体
７　正極リード体
８　負極リード体
９　蓋板
１０　絶縁パッキング
１１　端子
１２　絶縁体
１３　リード板[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a non-aqueous secondary battery having excellent safety and low self-discharge, and an electronic device using the same.
[0002]
[Prior art]
Non-aqueous secondary batteries typified by lithium ion batteries tend to be increasingly demanded because of their large capacity, high voltage, high energy density and high output. The safety of the battery tends to decrease with the increase in the capacity of the battery, and it is becoming increasingly important to ensure the safety of the battery and the electronic device using the battery. Recently, additives such as cyclohexylbenzene have been proposed to ensure the safety of batteries. For example, JP-A-5-036439, JP-A-10-275632, JP-A-2001-015155, JP-A-2000-215909, JP-A-2001-15158 and the like.
[0003]
[Problems to be solved by the invention]
At present, it has been found that non-aqueous secondary batteries can be used more safely by using these additives. However, the use of these additives has the problem of increasing self-discharge during charge storage.
[0004]
Then, the present inventors examined the effects of various additives and members in order to suppress self-discharge while improving safety. As a result, they have developed a non-aqueous secondary battery that can achieve both safety and suppression of self-discharge. Further, it was found that the self-discharge phenomenon was greatly affected by the thickness of the separator and the like, and the present inventors examined these effects in detail.
[0005]
The present invention provides a non-aqueous secondary battery that achieves both safety and suppression of self-discharge, and an electronic device using the same.
[0006]
[Means for Solving the Problems]
A non-aqueous secondary battery of the present invention is a non-aqueous secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte contains a non-ionic compound having an alkyl group bonded to an aromatic ring. A non-aqueous secondary battery containing 0.5 to 15% by mass and containing 1 to 10000 ppm of an amine-based aromatic, sulfide-based aromatic, phosphite-based aromatic, or quinone-based aromatic. I do.
[0007]
Further, an electronic device of the present invention is an electronic device provided with the non-aqueous secondary battery, wherein the non-aqueous secondary battery is sometimes charged with a current of 1 C or more.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Further, the present invention is a non-aqueous secondary battery including a positive electrode, a negative electrode and a non-aqueous electrolyte, wherein the non-aqueous electrolyte contains a nonionic compound having an alkyl group bonded to an aromatic ring in an amount of 0.5 to 15 mass%. %, And 1 to 10000 ppm of an amine-based aromatic, a sulfide-based aromatic, a phosphite-based aromatic, or a quinone-based aromatic.
[0009]
The present invention includes a non-aqueous electrolyte containing a non-ionic compound having an alkyl group bonded to an aromatic ring and an amine-based aromatic or sulfide-based aromatic or phosphite-based aromatic or quinone-based aromatic. Thus, a non-aqueous secondary battery can be provided that ensures both safety such as suppression of heat generation of the battery and suppression of self-discharge.
[0010]
Examples of the nonionic compound having an alkyl group bonded to an aromatic ring (hereinafter referred to as “compound A” for convenience) used in the present invention include, for example, cyclohexylbenzene, isopropylbenzene, t-butylbenzene, octylbenzene, toluene, xylene and the like. Among them, a compound in which an alkyl group having 4 or more carbon atoms is bonded to a benzene ring, or a compound in which a saturated aliphatic ring is bonded to a benzene ring is particularly effective and preferable for improving safety. Among them, cyclohexylbenzene is most desirable.
[0011]
Compound A needs to be contained in an amount of 0.5% by mass or more based on the mass of the nonaqueous electrolyte (total mass of the electrolyte salt, the solvent, and the polymer), more preferably 2% by mass or more, and 4% by mass or more. Most desirable. This is because if the amount of the compound A is less than 0.5% by mass, the effect of suppressing heat generation is reduced. Further, the compound A needs to be 15% by mass or less based on the mass of the nonaqueous electrolyte, more preferably 10% by mass or less, and most preferably 8% or less. This is because when the amount of the compound A exceeds 15% by mass, the self-discharge of the battery increases.
[0012]
In the present invention, together with compound A, an amine-based aromatic, sulfide-based aromatic or R-SLi (R is a substituent containing an aromatic group such as an allyl group) aromatic, phosphite-based aromatic, quinone-based aromatic (Hereinafter, referred to as “compound B” for convenience). Examples of the amine-based aromatic compound B include phenyl-β-naphthylamine, triphenylamine, and R1R2R3N (R1-3 is an allyl group or an alkyl group and at least one is an allyl group).
[0013]
Further, as a sulfide compound or a compound represented by R-SLi (R is a substituent containing an aromatic group such as an allyl group), R1-S-R2, R-S-Li (R1 and R2 are at least one of Is an aromatic group, and R is a substituent containing an aromatic group such as an allyl group) Specific examples include diphenyl sulfide, phenylbutyl sulfide, and C6H5-S-Li. The phosphite-based aromatic is represented by (R1O) (R2O) (R3O) P (R1 to R3 are an aromatic group such as an alkyl group or a phenyl group, and at least one is an aromatic group). Specific examples include phenyldiisoalkyl (C1 to C10) phosphite, diphenylisoalkyl (C1 to C10) phosphite, and triphenyl phosphite.
[0014]
Further, quinone-based aromatics include 2,6-di-t-octylhydroquinone, 2,6-di-n-dodecyl-hydroquinone, 2-n-dodecyl-5-chlorohydroquinone, and 2-t-octyl-5. And hydroquinone-based compounds such as methyl-hydroquinone, and a compound in which the 2- or 6-position is substituted with an alkyl group or an alkylene group is desirable. It is more desirable that the alkyl group is substituted by an alkyl group having 8 or more carbon atoms.
[0015]
It is necessary that the compound B is contained in an amount of 1 ppm or more based on the mass of the nonaqueous electrolyte (total mass of the electrolyte salt, the solvent, and the polymer), preferably 10 ppm or more, more preferably 20 ppm or more, and most preferably 50 ppm or more. If the content of Compound B is less than 1 ppm, the self-discharge suppressing effect is reduced. It is necessary that the content of the compound B is 10000 ppm or less, more preferably 1000 ppm or less, most preferably 500 ppm or less based on the mass of the non-aqueous electrolyte. If the compound B exceeds 10,000 ppm, the battery characteristics are significantly reduced.
[0016]
Further, when compound A is contained in the non-aqueous electrolyte in an amount of 3% by mass or more and is relatively large, it is desirable to increase compound B accordingly. In this case, the content of the compound B is preferably 500 ppm or more, more preferably 1000 ppm or more, and most preferably 2000 ppm or more, based on the mass of the non-aqueous electrolyte. This is because the self-discharge tends to increase with an increase in the amount of the compound A, so that this self-discharge is more effectively suppressed. Further, the content of the compound B is preferably 5000 ppm or less based on the mass of the non-aqueous electrolyte. This is for suppressing the deterioration of the battery characteristics to be lower.
[0017]
In the nonaqueous secondary battery of the present invention, it is preferable that the nonaqueous electrolyte contains a halogenated aromatic compound (hereinafter, referred to as “compound C” for convenience). This is because the safety of the battery can be further improved. Compound C includes fluorobenzene, difluorobenzene, trifluorobenzene, chlorobenzene, or a compound in which a halogen group such as fluorine is bonded to an aromatic ring of cyclohexylbenzene, isopropylbenzene, t-butylbenzene, octylbenzene, toluene, or xylene. In particular, when the compound C to which a fluorine atom is bonded is used, safety can be improved and self-discharge can be more effectively suppressed.
[0018]
Compound C is preferably contained in an amount of 1% by mass or more based on the mass of the non-aqueous electrolyte (total mass of the electrolyte salt, the solvent, and the polymer), more preferably 2% by mass or more, and most preferably 3% by mass or more. The content of the compound C is preferably 12% by mass or less, more preferably 5% by mass or less, and most preferably 4% by mass or less based on the mass of the non-aqueous electrolyte. This is because if the amount is too large, the electrical characteristics of the battery tend to deteriorate.
[0019]
Further, the non-aqueous secondary battery of the present invention can use a separator having a thickness of 20 μm or less. Conventionally, when a separator having a thickness of 22 μm or less is used and the compound A is added to a non-aqueous electrolyte, self-discharge at the time of charging and storing tends to be large, and particularly, the thickness is 20 μm or less, more remarkable. Tended to increase the self-discharge phenomenon when a separator of 16 μm or less was used. However, self-discharge can be suppressed by adding the compound A together with the compound A in a non-aqueous electrolyte. As a result, a separator having a thickness of 20 μm or less can be used.
[0020]
The thickness of the separator is desirably thin for high energy density. On the other hand, if the thickness is too small, short-circuiting is likely to occur. Therefore, the thickness is preferably 5 μm or more, more preferably 9 μm or more, and most preferably 15 μm or more.
[0021]
The air permeability of the separator is 1000 seconds / 100 cm ³ The following is desirable, 700 seconds / 100 cm ³ The following is more desirable, 450 seconds / 100 cm ³ The following are most desirable. In addition, 30 seconds / 100cm ³ The above is desirable, 50 seconds / 100 cm ³ The above is more desirable, 80 seconds / 100 cm ³ The above is most desirable. This is because as the air permeability of the separator increases, the electric characteristics of the battery tend to decrease, and as the air permeability of the separator decreases, the reliability of the battery decreases and a possibility of a short circuit or the like occurs.
[0022]
The separator has a tensile strength of 700 kgf / cm in the machine direction (MD direction). ² More preferably, 1000 kgf / cm ² The above is more desirable, 1300kgf / cm ² Is most desirable. Further, it is desirable that the tensile strength in the width direction (TD direction) is smaller than that of MD. The ratio of the tensile strength in the TD direction to the tensile strength in the MD direction (tensile strength in the TD direction / tensile strength in the MD direction) is preferably 0.95 or less, more preferably 0.9 or less, and most preferably 0.85 or less. . Further, 0.5 or more is desirable, 0.7 or more is more desirable, and 0.8 or more is most desirable. This increases the strength in the MD direction to 700 kgf / cm ² By making the tensile strength in the TD direction smaller than that in the MD direction as described above, thermal contraction in the TD direction can be suppressed while maintaining the piercing strength.
[0023]
The heat shrinkage of the separator is determined by holding the separator up and down with a 5 mm thick glass plate, leaving it in a thermostat at 150 ° C. for 2 hours, and the length of the most shrunk part in the TD direction and the original length Measure the ratio of The heat shrinkage is preferably 30% or less, more preferably 10% or less, and most preferably 5% or less. If the heat shrinkage is too large, heat is easily generated during the heating test. That is, if the heat shrinkage rate is large, the battery is likely to shrink when the temperature reaches 110 ° C. or higher, and a short circuit occurs at the electrode edge portion, so that the battery temperature tends to increase. When the heat shrinkage is small, short-circuiting between the electrodes hardly occurs even at a high temperature, and heat is hardly generated. As a method of suppressing the heat shrinkage, there is a method of performing heat treatment at a temperature of about 124 ° C. in the case of a polyolefin separator as described in JP-A-2001-172420 and JP-A-11-302436. This makes it possible to reduce heat shrinkage, and it is possible to further reduce heat shrinkage by performing heat treatment in two or more stages and shrinkage in the TD direction.
[0024]
The piercing strength of the separator is preferably 300 g or more, more preferably 350 g or more, and most preferably 400 g or more. This is because a battery with a higher piercing strength is less likely to cause a short circuit. However, the upper limit of the piercing strength is usually restricted by the material of the separator, and for example, in the case of a polyethylene separator, the limit is about 1000 g.
[0025]
Further, the nonaqueous secondary battery of the present invention preferably contains a lithium salt in the electrode and the nonaqueous electrolyte, and the concentration of the lithium salt in the electrode is preferably higher than the concentration of the lithium salt in the nonaqueous electrolyte. This is because the ionic conductivity of the electrode is increased, the uniform reactivity of the electrode is improved, and the safety of the battery is further improved. LiBF as lithium salt ₄ , LiClO ₄ Inorganic salts such as C ₄ F ₉ SO ₃ Li, C ₈ F ₁₇ SO ₃ Li, (C ₂ F ₅ SO ₂ ) ₂ NLi, (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ) NLi, (CF ₃ SO ₂ ) ₃ CLi, C ₆ H ₅ SO ₃ Li, C ₁₇ H ₃₅ Although there are organic lithium salts such as COOLi, an organic lithium salt is desirable in terms of thermal stability and safety.
[0026]
As the positive electrode active material forming the positive electrode of the present invention, for example, LiCoO 2 having an open circuit voltage of 4 V or more on the basis of Li when charging is used. ₂ , LiMn ₂ O ₄ , LiNiO ₂ And the like. In the positive electrode active material, Co, Ni, and Mn may be partially substituted with different elements, and the other elements may not be dissolved in crystals of the positive electrode active material and may be around the positive electrode active material. May be localized. Further, the positive electrode active material more preferably contains at least one additional element of Ge, Ti, Ta, Nb, and Yb. The content of this additional element is 0.001 atomic% or more, more preferably 0.003 atomic% or more, and most preferably 0% or more with respect to each of Co, Ni and Mn elements in the positive electrode active material in the electrode mixture. 0.005 atomic% or more. Further, it is desirably 3% or less, more desirably 1% or less, and most desirably 0.5% or less.
[0027]
The positive electrode active material is 0.4 to 1.0 m. ² / G of specific surface area. The specific surface area is 0.5-0.7m ² / G is more preferable. If the specific surface area of the positive electrode active material is large, the battery characteristics are improved, but the safety is reduced. In combination with the separator, even if the specific surface area of the positive electrode active material is relatively large, it can be used more safely. The electrode density of the positive electrode is preferably 3.3 g / cm3 or more. This is because a high energy density can be obtained.
[0028]
A mixture obtained by appropriately adding a conductive additive or a binder such as polyvinylidene fluoride to these positive electrode active materials is used, and a current collector material such as a metal foil is used as a core material to finish a molded body to form a positive electrode. As the positive electrode conductive agent, a carbon material is desirable, and the use amount is preferably 5% by mass or less, more preferably 3% by mass or less based on the positive electrode active material. Further, it is desirably 1.5% by mass or more, and more desirably 2% by mass or more.
[0029]
As the current collector of the positive electrode used here, for example, a foil containing aluminum as a main component is preferably used, and its purity is desirably 98% or more and 99.9% or less. In a general lithium-ion battery, 99.9% or more of aluminum foil is usually used. However, when a metal foil of 15 μm or less is used, the purity is 99.9 mass% in order to secure a certain strength. % Aluminum foil is preferably used.
[0030]
Desirable metal elements particularly contained in addition to aluminum are iron and silicon. The iron element is desirably contained in an amount of 0.5% by mass or more, and more desirably 0.7% by mass or more. Further, it is desirably 2% by mass or less, and more desirably 1.3% by mass or less. Silicon is desirably contained in an amount of 0.1% by mass or more, and more desirably 0.2% by mass or more. Further, the content is preferably 1.0% by mass or less, more preferably 0.3% by mass or less.
[0031]
Desirable tensile strength of current collector made of aluminum foil is 150 N / mm ² 180 N / mm ² The above is more desirable. The breaking elongation is preferably 2% or more, more preferably 3% or more.
[0032]
It is preferable that the tensile strength and elongation at break of the current collector are large because the amount of discharge power per unit volume of the electrode laminate increases and the expansion during charging of the electrode increases, and the current collector tends to break. This is because it is necessary to suppress this.
[0033]
The material used for the negative electrode may be any material capable of doping and undoping lithium ions. Examples of the material include natural graphite, pyrolytic carbons, cokes, glassy carbons, fired bodies of organic polymer compounds, and mesocarbon micro-carbons. Any carbonaceous material such as beads, carbon fibers, activated carbon, etc. may be used. Further, an alloy such as Si, Sn, In, or a compound such as an oxide or a nitride that can be charged and discharged at a low potential close to Li is desirable. Further, these can be mixed or compounded for use.
[0034]
When a carbonaceous material is used for the negative electrode, one having the following characteristics is preferable. That is, the inter-plane distance d002 of the (002) plane is preferably 3.5 ° or less, more preferably 3.45 ° or less, and even more preferably 3.4 ° or less. The crystallite size Lc in the C-axis direction is preferably 30 ° or more, more preferably 80 ° or more, and further preferably 250 ° or more. Further, the average particle size of the carbonaceous material is preferably 8 to 40 μm, particularly preferably 10 to 35 μm, and the purity thereof is preferably 99.5% or more. When the carbonaceous material is used for a negative electrode, the electrode density is 1.5 g / cm. ³ The above is desirable for increasing the capacity, more preferably 1.55 g / cm ³ Above, most preferably 1.6 g / cm ³ That is all.
[0035]
In addition, a copper foil is generally used as the current collector of the negative electrode, and an electrolytic copper foil is preferably used.
[0036]
As the non-aqueous electrolyte of the present invention, any of a non-aqueous liquid electrolyte and a polymer electrolyte can be used. As the non-aqueous liquid electrolyte, an organic solvent-based electrolyte (organic electrolyte) prepared by dissolving an electrolyte salt such as a lithium salt in an organic solvent can be suitably used. Examples of the solvent used for the organic electrolyte include organic solvents having a chain COO-bond such as dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and methyl propionate; and chain phosphate triesters such as trimethyl phosphate; , 2-dimethoxyethane (DME), 1,3-dioxolane (DO), tetrahydrofuran (THF), 2-methyl-tetrahydrofuran (2Me-THF), diethyl ether (DEE) and the like. In addition, a sulfur organic solvent such as an amine imide or a sulfolane may be used. Among them, it is desirable to use a chain carbonate such as dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate. The proportion of these solvents is preferably less than 90% by volume, more preferably 80% by volume or less, and most preferably 70% by volume or less in the total solvent of the organic electrolyte. In addition, from the viewpoint of discharge characteristics, 40% or more is desirable, 50% by volume or more is more desirable, and 60% or more is most desirable.
[0037]
Further, the organic electrolyte may contain a polymer such as polyethylene oxide or polymethyl methacrylate.
[0038]
Further, as the other solvent component constituting the organic electrolyte, an ester is suitably used. Among them, it is more preferable to use a mixture of an ester having a high dielectric constant (dielectric constant of 30 or more). Examples of the ester having a high dielectric constant include, for example, ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), gamma-butyrolactone (γ-BL), and sulfur-based esters such as ethylene glycol sulfite (EGS). can give. Further, as the ester, a cyclic carbonate such as ethylene carbonate (EC) is particularly preferable.
[0039]
The ratio of the high dielectric constant ester is preferably less than 80% by volume, more preferably 50% by volume or less, and most preferably 35% by volume or less in the total solvent of the organic electrolytic solution. From the viewpoint of discharge characteristics, the content is preferably 1% by volume or more, more preferably 10% by volume or more, and most preferably 25% by volume or more.
[0040]
Examples of the electrolyte salt of the organic electrolyte include LiClO. ₄ , LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF ₆ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiCF ₃ CO ₂ , Li ₂ C ₂ F ₄ (SO ₃ ) ₂ , LiN (RfSO ₂ ) (RfSO ₂ ), LiN (RfOSO) ₂ ) (RfOSO ₂ ), LiC (Rf SO ₂ ) ₃ , LiCn F _{2n + 1} SO ₃ (N ≧ 2), LiN (RfOSO ₂ ) ₂ [Where Rf is a fluoroalkyl group], a polymer imide lithium salt or the like is used alone or in combination of two or more. When these are incorporated into the coating on the electrode surface, they can impart ionic conductivity to the coating, and particularly, LiPF ₆ When an organic lithium salt is combined with the organic lithium salt, the effect is enhanced. The concentration of the electrolyte salt in the organic electrolyte is not particularly limited, but may be 1 mol / dm. ³ The above is preferable because the safety is improved, and is preferably 1.2 mol / dm. ³ The above is more desirable. In addition, 1.7 mol / dm ³ It is desirable that the content be less than 1.5 because electric characteristics are improved. ³ The following is more desirable.
[0041]
Further, a solid polymer electrolyte in which an electrolyte salt is supported on a polymer support or a gel polymer electrolyte obtained by gelling a liquid electrolyte with a polymer can also be used as the organic electrolyte.
[0042]
Further, when the non-aqueous electrolyte of the present invention contains a cyclic carbonate having a carbon-carbon double bond (C = C) in a ring such as vinylene carbonate, the self-discharge becomes larger when the compound A is further used. However, by causing the compound B to coexist, self-discharge is suppressed.
[0043]
The non-aqueous secondary battery of the present invention has a great effect in a square battery or a laminated battery, but can be applied to various battery types such as a cylindrical battery, a button battery, and a coin battery.
[0044]
In addition, electronic devices using the non-aqueous secondary battery of the present invention include portable electronic devices such as mobile phones, notebook computers, PDAs, and small medical devices, OA electronic devices with a battery backup function, and medical electronic devices. and so on. In particular, a combination of an electronic device in which the mounted non-aqueous secondary battery can be charged with a current of 1 C or more and the non-aqueous secondary battery of the present invention is effective. Combinations with equipment are more preferred. In these electronic devices, when the charge control is removed and the battery is continuously overcharged, the surface temperature of the battery used may be 110 ° C. or higher. However, by using the non-aqueous secondary battery of the present invention, the battery becomes Even if heat is generated, reliability can be ensured, and even if the charge protection circuit does not function, the device will not be damaged. In addition, when a battery using a separator of 22 μm or less is used in a normal device, when the battery surface temperature becomes 110 ° C. or more due to such overcharging, the separator shrinks, and a short circuit easily occurs at an electrode edge portion. As a result, the battery generates heat and the electronic device is easily damaged by heat. However, such an inconvenience is eliminated in an electronic device combined with the non-aqueous secondary battery of the present invention.
[0045]
In addition, when a portable electronic device that is portable and the non-aqueous secondary battery of the present invention are combined, safety can be ensured even with a battery having a high energy density, which is more effective.
[0046]
【Example】
Next, the present invention will be described more specifically based on examples. However, the present invention is not limited to only these examples.
[0047]
(Example 1)
Ethylene carbonate (EC) and methyl ethyl carbonate (MEC) were mixed at a volume ratio of 1: 2, and LiPF was added to the mixed solvent. ₆ To 1.2 mol / dm ³ The organic electrolyte solution was adjusted by dissolving. In 90.5 parts by mass of the organic electrolyte, 4 parts by mass of cyclohexylbenzene (CB) as the compound A, 0.01 part by mass of phenyl-β-naphthylamine as the compound B, and 3 parts of fluorobenzene (FB) as the compound C 2 parts by mass of 1,3-propane sultone (PS) and 0.5 part by mass of vinylene carbonate (VC) were mixed as parts by mass and other additives, and the composition was 1.2 mol / dm. ³ An organic electrolyte solution represented by LiPF6 / EC: MEC (1: 2) +4 mass% of CB + 3 mass% of FB + 2 mass% of PS + 0.5 mass% of VC + 0.01 mass% of phenyl-β-naphthylamine was prepared.
[0048]
Separately, the specific surface area is 0.5 m as the positive electrode active material. ² / G LiCo _0.995 Ge _0.005 O ₂ Is prepared, and 97.9 parts by mass of this positive electrode active material is mixed with 2 parts by mass of carbon as a conductive auxiliary, and (C ₂ F ₅ SO ₂ ) ₂ 0.1 parts by mass of a lithium salt having a composition of NLi was added and mixed, and this mixture was mixed with a solution of polyvinylidene fluoride dissolved in N-methylpyrrolidone to prepare a positive electrode mixture slurry. After the positive electrode mixture slurry was passed through a filter to remove large pieces, the slurry was uniformly applied to both sides of a positive electrode current collector made of an aluminum foil having a thickness of 15 μm, dried, and then subjected to compression molding by a roller press. Then, the lead body was cut and welded to produce a belt-shaped positive electrode. The portion not facing the negative electrode was not coated.
[0049]
The aluminum foil used as the positive electrode current collector contained 1% by mass of iron and 0.15% by mass of silicon, and the purity of aluminum was 98% by mass or more. The tensile strength of this aluminum foil was 185 N / mm2. The wettability was 38 dyne / cm, and the elongation at break was 3%.
[0050]
Next, 99.9 parts by mass of a graphite-based carbon material having d002 = 3.35 ° and an average particle size of 15 μm were added to ₂ F ₅ SO ₂ ) ₂ 0.1 parts by mass of NLi was mixed with a solution of vinylidene fluoride dissolved in N-methylpyrrolidone to prepare a negative electrode mixture slurry. After passing the negative electrode mixture slurry through a filter to remove large pieces, the slurry was uniformly applied to a negative electrode current collector made of a strip-shaped copper foil having a thickness of 10 μm, dried, and then compression-molded by a roller press. After cutting, it was dried, and the lead body was welded to produce a strip-shaped negative electrode. The negative electrode mixture applied portion of the electrode was made to be 1 mm wider in the width direction than the coated portion of the positive electrode and about 5 mm larger in the longitudinal direction, but the negative electrode portion not facing the positive electrode during other windings Was not coated with the negative electrode slurry. This is because battery safety is also improved by making the size of the application portion of the positive electrode mixture slurry smaller than the size of the application portion of the negative electrode mixture slurry. Here, the electrode density of the negative electrode is 1.6 g / cm. ³ Met.
[0051]
Thickness 16 μm, air permeability 260 sec / 100 ml, piercing strength 410 g, porosity 44%. MD direction tensile strength 1600kgf / cm ² A microporous polyethylene film having a tensile strength in the MD direction of 1200 kgf / cm 2 and a heat shrinkage of 24% after 150 ° C. for 3 hours was prepared. Next, the strip-shaped positive electrode was stacked on the strip-shaped negative electrode via the microporous polyethylene film, and wound into a flat plate to form an electrode laminate. Then, after tape fixing, the electrode laminate is inserted into an aluminum alloy battery case having an outer thickness (depth) of 4 mm, a width of 30 mm, and a height of 48 mm, and welding of a lead body and a lid plate for sealing are performed. Laser welding was performed on the opening of the battery case.
[0052]
Finally, the organic electrolytic solution is injected into the battery case, and after the organic electrolytic solution has sufficiently permeated into the separator and the like, sealing, pre-charging and aging are performed, and a rectangular prism having a structure as shown in FIG. A non-aqueous secondary battery of the present invention was produced. Its capacity is 600 mAh.
[0053]
FIGS. 1A and 1B are diagrams schematically showing an example of a non-aqueous secondary battery according to the present invention, wherein FIG. 1A is a plan view thereof, and FIG. 1B is a partial longitudinal sectional view thereof. In FIG. 1, the positive electrode 1 and the negative electrode 2 are spirally wound through the separator 3 as described above, and then pressurized so as to be flat to form a flat wound electrode laminate 6 having a rectangular shape. The battery case 4 is accommodated together with the organic electrolyte. However, in FIG. 1, in order to avoid complication, a metal foil, an electrolytic solution, and the like as a current collector used for manufacturing the positive electrode 1 and the negative electrode 2 are not illustrated.
[0054]
The battery case 4 is formed of an aluminum alloy and serves as a battery exterior material. The battery case 4 also serves as a positive electrode terminal. An insulator 5 made of a polytetrafluoroethylene sheet is arranged at the bottom of the battery case 4, and a positive electrode 1 and a negative electrode are formed from an electrode laminate 6 having a flat wound structure including the positive electrode 1, the negative electrode 2 and the separator 3. The positive electrode lead 7 and the negative electrode lead 8 connected to one end of each of 2 are drawn out. Further, a stainless steel terminal 11 is attached to an aluminum alloy cover plate 9 for closing the opening of the battery case 4 via an insulating packing 10 made of polypropylene. A lead plate 13 made of stainless steel is attached. Further, the lid plate 9 is inserted into the opening of the battery case 4, and the joint of the two is welded, whereby the opening of the battery case 4 is sealed and the inside of the battery is sealed.
[0055]
The battery was charged at a constant current at room temperature with a current value of 0.12 A (0.2 C) until the battery voltage reached 4.2 V, and then a constant voltage charge of 4.2 V was performed. Charging was finished. At the end of charging, the potential of the positive electrode was about 4.3 V based on lithium.
[0056]
In order to exhibit more safety, it is desirable that the amount of the electrolyte is in an appropriate range. The desired amount of electrolyte per unit discharge capacity is 2 cm ³ / Ah or more is desirable and 2.3 cm ³ / Ah or more is more desirable 2.5 cm ³ / Ah or more is most desirable. In addition, 3.5cm ³ / Ah or less is desirable, and 3.1 cm ³ / Ah or less is more desirable, and 2.9 / Ah or less is most desirable. In this embodiment, 2.7 cm ³ / Ah.
[0057]
(Example 2)
A 600 mAh non-aqueous secondary battery of the present invention was produced in the same manner as in Example 1 except that 2,4-dimethyl-6-t-butylamine was used instead of phenyl-β-naphthylamine.
[0058]
This battery was charged at a constant current of 0.12 A (0.2 C) until the battery voltage reached 4.2 V, and was further charged at a constant voltage of 4.2 V, and was charged 7 hours after the start of charging. finished. At the end of charging, the potential of the positive electrode was about 4.3 V based on lithium. The amount of electrolyte per unit discharge capacity is 2.7 cm. ³ / Ah.
[0059]
(Example 3)
A non-aqueous secondary battery of 600 mAh according to the present invention was produced in the same manner as in Example 1 except that FB was not used for the electrolytic solution.
[0060]
This battery was charged at a constant current of 0.12 A (0.2 C) until the battery voltage reached 4.2 V, and was further charged at a constant voltage of 4.2 V, and was charged 7 hours after the start of charging. finished. Next, the battery was discharged to 3 V at 0.12 A (0.2 C). The positive electrode potential at the time of charging was about 4.3 V on the basis of lithium. The amount of electrolyte per unit discharge capacity is 2.7 cm ³ / Ah.
[0061]
(Example 4)
A 600 mAh non-aqueous secondary battery of the present invention was produced in the same manner as in Example 1, except that 0.05 parts by mass of diphenyl sulfide was used instead of 0.01 parts by mass of phenyl-β-naphthylamine.
[0062]
This battery was charged at a constant current of 0.12 A (0.2 C) until the battery voltage reached 4.2 V, and was further charged at a constant voltage of 4.2 V, and was charged 7 hours after the start of charging. finished. At the end of charging, the potential of the positive electrode was about 4.3 V based on lithium. The amount of electrolyte per unit discharge capacity is 2.7 cm. ³ / Ah.
[0063]
(Example 5)
C instead of diphenyl sulfide ₆ H ₅ -SC ₄ H ₉ A non-aqueous secondary battery of the present invention having a capacity of 600 mAh was prepared in the same manner as in Example 4 except for using. This battery was charged at a constant current of 0.12 A (0.2 C) until the battery voltage reached 4.2 V, and was further charged at a constant voltage of 4.2 V, and was charged 7 hours after the start of charging. finished. At the end of charging, the potential of the positive electrode was about 4.3 V based on lithium. The amount of electrolyte per unit discharge capacity is 2.7 cm. ³ / Ah.
[0064]
(Example 6)
A 600 mAh non-aqueous secondary battery of the present invention was produced in the same manner as in Example 4, except that FB was not used for the electrolytic solution. This battery was charged at a constant current of 0.12 A (0.2 C) until the battery voltage reached 4.2 V, and was further charged at a constant voltage of 4.2 V, and was charged 7 hours after the start of charging. finished. At the end of charging, the potential of the positive electrode was about 4.3 V based on lithium. The amount of electrolyte per unit discharge capacity is 2.7 cm. ³ / Ah.
[0065]
(Example 7)
A 600 mAh non-aqueous secondary battery of the present invention was produced in the same manner as in Example 1 except that triphenyl phosphite was used instead of phenyl-β-naphthylamine.
[0066]
This battery was charged at a constant current of 0.12 A (0.2 C) until the battery voltage reached 4.2 V, and was further charged at a constant voltage of 4.2 V, and was charged 7 hours after the start of charging. finished. At the end of charging, the potential of the positive electrode was about 4.3 V based on lithium. The amount of electrolyte per unit discharge capacity is 2.7 cm. ³ / Ah.
[0067]
(Example 8)
A 600 mAh non-aqueous secondary battery of the present invention was produced in the same manner as in Example 7, except that diphenylbutyl phosphite was used instead of triphenyl phosphite. This battery was charged at a constant current of 0.12 A (0.2 C) until the battery voltage reached 4.2 V, and was further charged at a constant voltage of 4.2 V, and was charged 7 hours after the start of charging. finished. At the end of charging, the potential of the positive electrode was about 4.3 V based on lithium. The amount of electrolyte per unit discharge capacity is 2.7 cm. ³ / Ah.
[0068]
(Example 9)
A 600 mAh non-aqueous secondary battery of the present invention was produced in the same manner as in Example 7, except that FB was not used for the electrolytic solution. This battery was charged at a constant current of 0.12 A (0.2 C) until the battery voltage reached 4.2 V, and was further charged at a constant voltage of 4.2 V, and was charged 7 hours after the start of charging. finished. At the end of charging, the potential of the positive electrode was about 4.3 V based on lithium. The amount of electrolyte per unit discharge capacity is 2.7 cm. ³ / Ah.
[0069]
(Example 10)
A 600 mAh non-aqueous secondary battery of the present invention was produced in the same manner as in Example 1, except that 2,5-di-t-octylhydroquinone was used instead of phenyl-β-naphthylamine.
[0070]
This battery was charged at a constant current of 0.12 A (0.2 C) until the battery voltage reached 4.2 V, and was further charged at a constant voltage of 4.2 V, and was charged 7 hours after the start of charging. finished. At the end of charging, the potential of the positive electrode was about 4.3 V based on lithium. The amount of electrolyte per unit discharge capacity is 2.7 cm. ³ / Ah.
[0071]
(Example 11)
A 600 mAh non-aqueous secondary battery of the present invention was produced in the same manner as in Example 10, except that 2,6-di-n-dodecyl-hydroquinone was used instead of 2,5-di-t-octylhydroquinone. This battery was charged at a constant current of 0.12 A (0.2 C) until the battery voltage reached 4.2 V, and was further charged at a constant voltage of 4.2 V, and was charged 7 hours after the start of charging. finished. At the end of charging, the potential of the positive electrode was about 4.3 V based on lithium. The amount of electrolyte per unit discharge capacity is 2.7 cm. ³ / Ah.
[0072]
(Example 12)
A non-aqueous secondary battery of 600 mAh of the present invention was produced in the same manner as in Example 10 except that FB was not used for the electrolytic solution. This battery was charged at a constant current of 0.12 A (0.2 C) until the battery voltage reached 4.2 V, and was further charged at a constant voltage of 4.2 V, and was charged 7 hours after the start of charging. finished. At the end of charging, the potential of the positive electrode was about 4.3 V based on lithium. The amount of electrolyte per unit discharge capacity is 2.7 cm. ³ / Ah.
[0073]
(Comparative Example 1)
A non-aqueous secondary battery of the present invention having a capacity of 600 mAh was prepared in the same manner as in Example 1 except that CB was not used as the electrolytic solution. This battery was charged at a constant current of 0.12 A (0.2 C) until the battery voltage reached 4.2 V, and was further charged at a constant voltage of 4.2 V, and was charged 7 hours after the start of charging. finished. The positive electrode potential at the time of charging was about 4.3 V based on lithium. The amount of electrolyte per unit discharge capacity is 2.7 cm ³ / Ah.
[0074]
(Comparative Example 2)
A non-aqueous secondary battery of the present invention having a capacity of 600 mAh was prepared in the same manner as in Example 4, except that CB was not used as the electrolytic solution. This battery was charged at a constant current of 0.12 A (0.2 C) until the battery voltage reached 4.2 V, and was further charged at a constant voltage of 4.2 V, and was charged 7 hours after the start of charging. finished. The positive electrode potential at the time of charging was about 4.3 V based on lithium. The amount of electrolyte per unit discharge capacity is 2.7 cm ³ / Ah.
[0075]
(Comparative Example 3)
A non-aqueous secondary battery of the present invention having a capacity of 600 mAh was prepared in the same manner as in Example 7, except that CB was not used as the electrolytic solution. This battery was charged at a constant current of 0.12 A (0.2 C) until the battery voltage reached 4.2 V, and was further charged at a constant voltage of 4.2 V, and was charged 7 hours after the start of charging. finished. The positive electrode potential at the time of charging was about 4.3 V based on lithium. The amount of electrolyte per unit discharge capacity is 2.7 cm ³ / Ah.
[0076]
(Comparative Example 4)
A non-aqueous secondary battery of 600 mAh was prepared in the same manner as in Example 10, except that CB was not used as the electrolyte. This battery was charged at a constant current of 0.12 A (0.2 C) until the battery voltage reached 4.2 V, and was further charged at a constant voltage of 4.2 V, and was charged 7 hours after the start of charging. finished. The positive electrode potential at the time of charging was about 4.3 V based on lithium. The amount of electrolyte per unit discharge capacity is 2.7 cm ³ / Ah.
[0077]
(Comparative Example 5)
A non-aqueous secondary battery of the present invention having a capacity of 600 mAh was prepared in the same manner as in Example 1, except that phenyl-β-naphthylamine was not added to the electrolytic solution. This battery was charged at a constant current of 0.12 A (0.2 C) until the battery voltage reached 4.2 V, and was further charged at a constant voltage of 4.2 V, and was charged 7 hours after the start of charging. finished. The positive electrode potential at the time of charging was about 4.3 V based on lithium. The amount of electrolyte per unit discharge capacity is 2.7 cm ³ / Ah.
[0078]
(Comparative Example 6)
A 600 mAh non-aqueous secondary battery of the present invention was produced in the same manner as in Example 1, except that phenyl-β-naphthylamine was not added to the electrolytic solution and vinylene carbonate was not added. This battery was charged at a constant current of 0.12 A (0.2 C) until the battery voltage reached 4.2 V, and was further charged at a constant voltage of 4.2 V, and was charged 7 hours after the start of charging. finished. The positive electrode potential at the time of charging was about 4.3 V based on lithium. The amount of electrolyte per unit discharge capacity is 2.7 cm ³ / Ah.
[0079]
(Comparative Example 7)
No phenyl-β-naphthylamine was added to the electrolyte, and a 27-micron separator (air permeability, 90 seconds / 100 ml, piercing strength 440 g, porosity 50%. A battery was produced in the same manner as in Example 1 except that the tensile strength in the width direction (TD) was 260 kgf / cm 2, and the heat shrinkage was 28% in the width direction at 150 ° C. for 3 hours. This battery was charged at a constant current of 0.12 A (0.2 C) until the battery voltage reached 4.2 V, and was further charged at a constant voltage of 4.2 V, and was charged 7 hours after the start of charging. finished. The positive electrode potential at the time of charging was about 4.3 V based on lithium. The amount of electrolyte per unit discharge capacity is 2.7 cm ³ / Ah.
[0080]
The batteries of Example 1-12 and Comparative Example 1-7 were charged to 4.2V at 1C, and then charged at 4.2V constant voltage for 3 hours, then discharged to 3V at 1C, and the discharge capacity was measured (Q1). Similarly, after charging to 4.2 V, the battery was stored at 60 ° C. for 20 days, taken out, discharged after 12 hours at 1 C to 3 V, and the discharge capacity Q2 after storage was measured. (%: (Q1-Q2) / Q1 * 100) was measured. Each of the five batteries was charged at 0.6 A to 5.5 V, and the percentage of the battery whose battery surface temperature exceeded 130 ° C. and the maximum temperature were determined. Examined. Table 1 shows the results.
[0081]
[Table 1]

[0082]
* However, Comparative Example 7 uses a 27 μm thick separator
[0083]
The batteries of Examples 1 to 12 are represented by a nonionic compound in which an alkyl group is bonded to an aromatic ring in a nonaqueous electrolyte and an amine-based aromatic, sulfide-based aromatic or R-SLi (R is an allyl group or the like) By using an aromatic, a phosphite-based aromatic or a quinone-based aromatic, both safety and suppression of self-discharge were achieved.
[0084]
On the other hand, the batteries of Comparative Examples 1 to 7 failed to achieve either safety or suppression of self-discharge.
[0085]
Next, using the batteries of Examples 1, 4, 7, and 10 of the present invention and Comparative Examples 1 to 4 as a power source for a mobile phone, assuming that the protection circuit and the charging circuit were damaged, the protection circuit, the PTC, After disabling the voltage control circuit, the battery was charged to a power supply voltage of 12 V with a current of 0.6 A (1.0 C), and thereafter, was charged at a constant voltage of 5.5 V. As a result, in the portable devices using the batteries of Comparative Examples 1 to 4, the maximum battery surface temperature was increased by 20 ° C. or more at any current value, and especially at 1 A, the device was damaged. In this experiment, the protection circuit, the PTC, and the voltage control circuit were disabled, but it goes without saying that adding the respective protection functions further improves the reliability of the portable electronic device.
[0086]
【The invention's effect】
As described above, the present invention is a non-aqueous secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte includes a non-ionic compound in which an alkyl group is bonded to an aromatic ring. Aromatic, phosphite-based aromatic, quinone containing 0.5 to 15% by mass and represented by an amine-based aromatic, sulfide-based aromatic or R-SLi (R is a substituent containing an aromatic group such as an allyl group) By using a non-aqueous secondary battery containing 1 to 10000 ppm of a system aromatic, it is possible to provide a non-aqueous secondary battery that achieves both safety and suppression of self-discharge, and an electronic device using the same.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing an example of a non-aqueous secondary battery according to the present invention, wherein (a) is a plan view thereof, and (b) is a partial longitudinal sectional view thereof.
[Explanation of symbols]
1 positive electrode
2 Negative electrode
3 separator
4 Battery case
5 Insulator
6. Electrode laminate
7 Positive lead body
8 Negative electrode lead body
9 Cover plate
10 Insulation packing
11 terminals
12 Insulator
13 Lead plate

Claims (9)

A non-aqueous secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte contains 0.5 to 15% by mass of a non-ionic compound in which an alkyl group is bonded to an aromatic ring, and A non-aqueous secondary battery comprising 1 to 10000 ppm of an amine-based aromatic. A non-aqueous secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte contains 0.5 to 15% by mass of a non-ionic compound in which an alkyl group is bonded to an aromatic ring, and A non-aqueous secondary battery containing a sulfide-based aromatic in an amount of 1 to 10000 ppm. A non-aqueous secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte contains 0.5 to 15% by mass of a non-ionic compound in which an alkyl group is bonded to an aromatic ring, and A non-aqueous secondary battery comprising 1 to 10000 ppm of a phosphite-based aromatic. A non-aqueous secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte contains 0.5 to 15% by mass of a non-ionic compound in which an alkyl group is bonded to an aromatic ring, and A non-aqueous secondary battery comprising 1 to 10,000 ppm of any of quinone-based aromatics. The nonaqueous secondary battery according to claim 1, wherein the nonaqueous electrolyte contains 1 to 12% by mass of a halogenated aromatic compound. The non-aqueous secondary battery according to claim 1, further comprising a separator having a thickness of 20 μm or less. The non-aqueous secondary battery according to claim 1, wherein the positive electrode is formed from a positive electrode active material having a specific surface area of 0.4 to 1.0 m 2 / g. The nonaqueous secondary battery according to any one of claims 1 to 7, wherein the type of the battery is a prismatic battery or a laminated battery. An electronic device comprising the non-aqueous secondary battery according to claim 1, wherein the non-aqueous secondary battery may be charged with a current of 1.0 C or more.

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