JP2001202990A - Nonaqueous electrolytic battery and charging method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolytic battery, minimizing not only the increase of the internal pressure of the battery but the expansion of the battery case. SOLUTION: The nonaqueous electrolytic battery contains chain carbonic acid ester in its electrolytic solution and is provided inside the battery with an adsorbent for carbon dioxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a non-aqueous electrolyte battery.

[0002]

2. Description of the Related Art In recent years, electronic devices such as a portable radio telephone, a portable personal computer, and a portable video camera have been developed, and various electronic devices have been reduced in size to be portable. Along with this, a battery having a high energy density and a light weight is also adopted as a built-in battery. A typical battery that satisfies such a requirement is an active material such as lithium metal or lithium alloy, or a host material containing lithium ions (here, a host material refers to a material that can occlude and release lithium ions). Lithium intercalation compound occluded in a certain carbon is used as a negative electrode material, and LiC
This is a non-aqueous electrolyte secondary battery using an aprotic organic solvent in which a lithium salt such as 10 ₄ or LiPF ₆ is dissolved as an electrolyte.

This non-aqueous electrolyte secondary battery has a negative electrode plate in which the above-mentioned negative electrode material is held on a negative electrode current collector as a support, and a reversible electrochemical reaction with lithium ions such as a lithium-cobalt composite oxide. The positive electrode plate, which holds the positive electrode active material that reacts on the positive electrode current collector that is the support, from the separator that holds the electrolytic solution and intervenes between the negative electrode plate and the positive electrode plate to prevent a short circuit between the two electrodes Has become.

[0004] Each of the positive electrode plate and the negative electrode plate is formed into a thin sheet or foil shape, and is a power generating element formed by sequentially laminating or spirally winding through a separator. Then, the power generating element is housed in a battery container made of a metal can made of stainless steel, nickel-plated iron, aluminum, or the like. After the electrolyte is injected, the battery is assembled and sealed with a lid plate.

However, when a metal can battery container is used,
Although it is highly airtight and has excellent mechanical strength,
There are great restrictions on battery weight, battery container material and design. As a solution to the problem, there has been proposed a method using a material in which a metal foil is laminated with a resin film on a material of a battery case. According to this method, there is no leakage of the electrolytic solution or intrusion of moisture or the like from the outside of the battery, and the weight of the battery can be reduced.

The shape of the power generating element is a wound type,
In particular, when the cross section is non-circular or oval, the electrode surface area can be increased and the manufacturing process can be simplified.

When such a non-aqueous electrolyte secondary battery is used in an electronic device, a predetermined voltage is obtained as a unit cell or a plurality of cells connected in series. The single or plural batteries are housed in a housing made of resin or metal and resin together with the charge / discharge control circuit, and sealed so that the contents cannot be taken out, and used as a battery pack.

However, LiCoO ₂ , LiNi
Lithium batteries using O ₂ , LiMn ₂ O _4, etc. require a positive electrode of 4 V vs.
It is charged to a potential higher than Li / Li +. Therefore, when a charged battery is exposed to a high temperature such as being left in a car in the summer, part of the electrolyte is oxidized and decomposed to generate gas, and the pressure inside the battery increases. There is a problem that the battery case swells. When the battery case swells, the battery cannot be accommodated in the electronic device, or the battery shape is distorted, the element shape is distorted, the distance between the positive electrode and the negative electrode becomes uneven, and the battery performance is deteriorated. .

By changing the type of the non-aqueous solvent used for the electrolytic solution, it is possible to suppress the swelling of the battery when left at a high temperature to some extent. However, when a non-aqueous solvent that does not easily swell the battery is used, the battery is charged at a low temperature. The discharge characteristics tended to be inferior. Therefore, it has not been possible to produce a battery which is excellent in low-temperature charge / discharge characteristics while hardly swelling when left at high temperature.

In order to solve the problem of battery swelling when left at high temperature, it has been proposed that carbon dioxide generated in the battery when left at high temperature is adsorbed by an adsorbent (Japanese Patent Application Laid-Open No. Hei 1 (1999)).
0-255860). This proposal focuses on carbon dioxide as the main component of a gas that is a decomposition product of an electrolyte solvent or an electrolyte, and ethylene carbonate, propylene carbonate, γ-butyrolactone as an organic solvent,
It uses 1,2-dimethoxyethane, tetrahydrofuran or the like, and uses a carbon dioxide absorbent such as synthetic zeolite having a molecular sieve action. However, even in this case, the low-temperature charge / discharge characteristics have not been improved.
It was not possible to produce a battery having excellent low-temperature charge / discharge characteristics in addition to being difficult to swell when left at high temperatures.

[0011]

In a non-aqueous electrolyte battery, it is better to use a chain carbonate such as dimethyl carbonate than to use a cyclic carbonate such as ethylene carbonate or propylene carbonate as an electrolyte solvent. It is known that low-temperature characteristics are improved. However, when the electrolytic solution solvent is decomposed at a high temperature, a larger amount of carbon dioxide is generated in the chain carbonate than in the cyclic carbonate.

Therefore, there has been a demand for a non-aqueous electrolyte battery which does not easily swell when left at high temperatures and has excellent low-temperature charge / discharge characteristics.

[0013]

SUMMARY OF THE INVENTION The non-aqueous electrolyte battery according to the present invention has been made in view of the above problems, and has a chain carbonate in an electrolytic solution and a carbon dioxide adsorbent in the battery. It is characterized by having.

The present invention also provides a non-aqueous electrolyte battery according to the present invention, wherein the supporting electrolyte salt concentration in the non-aqueous electrolyte is 0.9 mol.
/ L or more and 2 mol / L or less.

Further, in the non-aqueous electrolyte battery according to the present invention, the chain carbonate is at least one selected from the group consisting of dimethyl carbonate, methyl ethyl carbonate and diethyl carbonate.

Further, in the non-aqueous electrolyte battery according to the present invention, the weight ratio of ethylene carbonate to the solvent of the non-aqueous electrolyte is 10% or more and less than 50%.

Further, the non-aqueous electrolyte battery according to the present invention comprises:
The positive electrode active material contains a cobalt atom or a nickel atom.

Further, the nonaqueous electrolyte battery according to the present invention comprises:
It is characterized by using a rectangular parallelepiped or bag-shaped battery case.

Further, the non-aqueous electrolyte battery according to the present invention comprises:
In the battery case, a sheet in which a metal foil and a resin film are bonded to each other or a metal mainly containing aluminum is used.

Further, according to the method for charging a non-aqueous electrolyte battery according to the present invention, there is provided a non-aqueous electrolyte battery comprising a chain carbonate in an electrolyte and a carbon dioxide adsorbent in the battery.
The battery is charged to a voltage of 1 V or more and 4.31 V or less.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION In a non-aqueous electrolyte battery, a chain carbonate rather than a cyclic carbonate is used as an electrolyte solvent in order to improve low-temperature characteristics. However, when the chain carbonate is thermally decomposed, a large amount of carbon dioxide is generated as compared with the cyclic carbonate.

Therefore, in the present invention, by providing a carbon dioxide adsorbent in a battery, carbon dioxide generated by thermal decomposition of an electrolytic solution or the like is adsorbed. As the carbon dioxide adsorbent, various substances such as hydroxides, oxides, carbonates and synthetic zeolites of alkali metals and alkaline earth metals can be used. No, synthetic zeolites are preferred. Synthetic zeolites having a molecular sieving action and having pores of various sizes are commercially available, and can selectively adsorb only molecules smaller than the pore size. Therefore, by providing a carbon dioxide adsorbent in the battery, carbon dioxide generated when the battery is left at high temperature in a charged state is absorbed by the carbon dioxide adsorbent.

For this reason, an increase in the internal pressure in the battery is suppressed, and the degree of swelling of the battery case is reduced. As a result, even if a charged battery is exposed to high temperatures due to being left in a car in the summer, the battery does not swell and does not fit in the electronic device, and the battery shape A non-aqueous electrolyte battery is obtained in which the element shape is not distorted due to the distortion, the distance between the positive electrode and the negative electrode is kept uniform, and the battery performance is not easily reduced.

In the present invention, a chain carbonate is used as the non-aqueous solvent used for the non-aqueous electrolyte. Chain carbonates are low-viscosity and easily move ions.
Excellent low-temperature discharge characteristics can be obtained. However, chain carbonates tend to decompose when left at high temperatures and generate gas,
Conventionally, it has not been possible to manufacture a battery that is excellent in both low-temperature charge / discharge characteristics and that it does not easily swell when left at high temperatures.

In the present invention, the combination of the provision of the chain carbonate in the electrolytic solution and the provision of the carbon dioxide adsorbent in the battery makes it difficult for the resin to swell when left at high temperatures, and to improve the low-temperature charge / discharge characteristics. An excellent non-aqueous electrolyte battery can be manufactured.

Conventionally, in order to manufacture a battery which does not easily swell when left at a high temperature, the concentration of the supporting electrolyte salt in the electrolyte must be 0.8 m or less.
ol / L or less, but even when the concentration of the supporting electrolyte salt in the battery electrolyte according to the present invention is 0.9 mol / L or more, the swelling when left at high temperature is small. However, when the concentration of the supporting electrolyte salt in the electrolytic solution exceeds 2 mol / L, the discharge capacity at a low temperature is greatly reduced. Therefore, the concentration of the supporting electrolyte salt in the nonaqueous electrolyte is 0.9 mol / L or more and 2 m / L or more.
ol / L or less.

As an electrolyte for a non-aqueous electrolyte battery charged up to 4 V or more, a carbonate ester is usually used because of its excellent oxidation resistance and reduction resistance. As the carbonate used, a cyclic carbonate capable of dissolving the supporting electrolyte salt at a high concentration and a chain carbonate which is low in viscosity and rapidly diffuses ions are used as a mixture. . In a lithium ion battery using a graphite-based negative electrode, ethylene carbonate is used as a cyclic carbonate since a protective film is formed on the graphite surface with a small irreversible capacity at the time of initial charging.

Conventionally, in order to manufacture a battery that does not easily swell when left at high temperatures, it has been necessary to use ethylene carbonate in 50% by weight or more of the solvent in the electrolyte. However, this battery was inferior in low-temperature characteristics. Therefore, in the present invention, the weight ratio of ethylene carbonate to the solvent of the electrolyte is set to 1 at the same time that the chain carbonate is provided in the electrolyte.
By setting the content to 0% or more and less than 50%, it is possible to manufacture a non-aqueous electrolyte battery which is less likely to swell when left at a high temperature and has excellent low-temperature charge / discharge characteristics. When the weight ratio of ethylene carbonate in the electrolyte solvent is set to 10% or less, the irreversible capacity at the time of initial charging increases, and as a result, the charge / discharge capacity of the battery decreases.

In a gas generated in a battery case when a nonaqueous electrolyte battery is left at a high temperature in a charged state, ethylene, ethane, and the like occupy a high ratio after carbon dioxide. Therefore, by providing not only carbon dioxide, but also ethylene and ethane adsorbents in the battery case,
Further, swelling of the battery case can be suppressed, and the present invention is more effective.

As a positive electrode active material of a non-aqueous electrolyte battery, it is possible to design a battery with a high energy density and charge / discharge at a high rate. Therefore, it is very difficult to use lithium cobaltate or lithium nickelate. It is valid. However, cobalt or nickel has a catalytic action in the oxidative decomposition of the electrolyte at the positive electrode. Therefore, when cobalt or nickel is used for the positive electrode, there is a problem that a battery that does not easily swell when left at high temperature in a charged state cannot be manufactured.

When the present invention is used, since the positive electrode active material contains a cobalt atom or a nickel atom and a carbon dioxide adsorbent is provided in the battery, the energy density is high and the high rate charge / discharge characteristics are excellent. In addition, it becomes possible to manufacture a battery in which the battery case does not easily swell when left at high temperature in a charged state.

In a battery having a cylindrical battery case, the curved surface, which is the widest surface, receives the internal pressure of the battery in a point-symmetric manner, so that the battery case does not easily expand. On the other hand, in the case of a non-cylindrical battery such as a square battery or a battery using a bag-shaped case using a metal laminated resin film as a battery case material, the widest surface receives pressure from a biased direction. Even when the internal pressure of the battery is the same, the battery easily swells as compared with the cylindrical battery. Therefore, it has been difficult to manufacture a thin battery that does not easily swell when left at high temperature in a charged state. When the present invention is used, by providing a carbon dioxide adsorbent in the battery in addition to using a rectangular parallelepiped or bag-shaped battery case, a thin battery that does not easily swell when left at high temperature in a charged state. It can be manufactured.

As a material of the nonaqueous electrolyte battery case, a sheet in which a metal foil and a resin film are bonded, iron, aluminum, or the like is used. Since the sheet in which the metal foil and the resin film are bonded to each other and aluminum are lighter than iron, the weight of the battery can be reduced by using them as a case material, and the weight energy density of the battery can be increased. . However, since the sheet in which the metal foil and the resin film are bonded to each other and aluminum are soft and easily bent as compared with iron, when these are used as the battery case material, even if the battery internal pressure is the same. It swells more easily than when using an iron case.

Therefore, it has been difficult to manufacture a battery which is unlikely to swell when left at high temperature in a charged state and has a high weight energy density by using a light material for the battery case. When the present invention is used, as a material of the battery case, a sheet in which a metal foil and a resin film are bonded together, or aluminum is used, and a battery is provided with a carbon dioxide adsorbent, and the battery is charged. This makes it possible to manufacture a battery having a high weight energy density while the battery case is unlikely to swell when left at a high temperature.

The power generating element according to the present invention may be either a positive electrode plate or a negative electrode plate formed into a thin sheet or foil, which are sequentially laminated or spirally wound. .

The material of the battery case may be any of a sheet in which a metal foil and a resin film are bonded, iron, or aluminum. The present invention is particularly effective when a sheet in which a metal foil and a resin film are bonded or aluminum is used as the material of the battery case.

When a sheet in which a metal foil and a resin film are bonded is used as the material of the battery case, aluminum, an aluminum alloy, titanium foil, or the like is used as the metal material of the metal laminated resin film. Can be. As the material of the heat-welded portion of the metal laminate resin film, any material may be used as long as it is a thermoplastic polymer material such as polyethylene, polypropylene, and polyethylene terephthalate. Further, the resin layer and the metal foil layer of the metal laminate resin film are not limited to one layer each, and may be two or more layers. As the cell case, a laminated case formed into an envelope shape by heat welding a metal laminated resin film, a case in which four sides of two metal laminated resin sheets are heat welded, or one sheet folded in two A metal-laminated resin film case of any shape can be used, such as a case in which the three sides are heat-welded and a metal-laminated resin sheet formed by press-forming a metal-laminated resin sheet into a cup-like shape and a power generation element.

The chain carbonate used in the electrolyte of the nonaqueous electrolyte battery according to the present invention may be dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, or a mixture thereof.

As the non-aqueous solvent other than the chain carbonate used in the electrolyte solvent of the non-aqueous electrolyte battery according to the present invention, ethylene carbonate, propylene carbonate,
polar solvents such as γ-butyrolactone, sulfolane, dimethyl sulfoxide, acetonitrile, dimethylformamide, dimethylacetamide, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dioxolan, methyl acetate, or these May be used.

Lithium salts dissolved in an organic solvent include LiPF ₆ , LiClO ₄ , LiBF ₄ , LiAs
F ₆ , LiCF ₃ CO ₂ , LiCF ₃ SO ₃ , LiN (SO ₂
CF ₃ ) ₂ , LiN (SO ₂ CF ₂ CF ₃ ) ₂ , LiN (CO
Salts such as CF ₃ ) ₂ and LiN (COCF ₂ CF ₃ ) ₂ or mixtures thereof may be used.

The separator of the non-aqueous electrolyte battery according to the present invention may be a material obtained by impregnating an electrolytic solution in a microporous insulating polyethylene film, a solid polymer electrolyte, or a solid polymer electrolyte containing an electrolyte solution. A gel electrolyte or the like can also be used. Further, an insulating microporous film and a solid polymer electrolyte may be used in combination. Further, when a porous solid polymer electrolyte membrane is used as the solid polymer electrolyte, the electrolyte contained in the polymer and the electrolyte contained in the pores may be different.

Further, as a compound capable of inserting and extracting lithium as a positive electrode material, an inorganic compound is represented by a composition formula L
i _x MO ₂ or Li _y M ₂ O _4, (where M is a transition metal,
A composite oxide represented by 0 ≦ x ≦ 1, 0 ≦ y ≦ 2),
An oxide having tunnel-like holes and a metal chalcogenide having a layered structure can be used. Specific examples thereof include LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , Li ₂
Mn ₂ O ₄ , MnO ₂ , FeO ₂ , V ₂ O ₅ , V ₆ O ₁₃ , Ti
O ₂ and TiS ₂ are mentioned. Examples of the organic compound include a conductive polymer such as polyaniline. Further, the above-mentioned various active materials may be mixed and used regardless of an inorganic compound or an organic compound.

Further, as a compound as a negative electrode material, A
1, alloys of lithium with Si, Pb, Sn, Zn, Cd, Sb, etc., transition metal oxides such as LiFe ₂ O ₃ , WO ₂ , MoO ₂ , graphite, carbonaceous materials such as carbon, tin oxide, Lithium nitride such as Li ₅ (Li ₃ N), metallic lithium, or a mixture thereof may be used.

The present invention is not limited to a secondary battery, but may be applied to a primary battery using lithium metal as a negative electrode active material and manganese oxide, carbon fluoride or thionyl chloride as a positive electrode active material. Good.

[0045]

Next, the present invention will be described based on preferred embodiments.

Example 1 A lithium-cobalt composite oxide was used as a positive electrode active material. The positive electrode plate is obtained by holding the above-mentioned lithium cobalt composite oxide as an active material on a current collector. An aluminum foil having a thickness of 20 μm was used for the current collector. The positive electrode plate was prepared by combining 6 parts of polyvinylidene fluoride as a binder and 3 parts of acetylene black as a conductive agent with an active material 91.
Then, the mixture was mixed with the mixture, and N-methylpyrrolidone was appropriately added to prepare a paste. Then, the mixture was applied to both surfaces of the current collector material and dried to produce a paste.

The negative electrode plate was prepared by mixing 92 parts of graphite (graphite) as a host substance and 8 parts of polyvinylidene fluoride as a binder on both sides of a current collector, and adding N-methylpyrrolidone as appropriate. Was prepared by coating and drying. A 14-μm-thick copper foil was used as the current collector of the negative electrode plate.

The separator was a polyethylene microporous membrane. Further, after mixing ethylene carbonate and methyl ethyl carbonate which is a chain carbonate at a weight ratio of 5: 5, LiPF ₆ was mixed with 0.8, 0.9, 1.0, 1.1,
1.2, 1.3, 1.4, 1.5, 1.6, 1.7,
Thirteen types of batteries were manufactured using thirteen types of electrolytes added at concentrations of 1.8, 1.9, and 2.0 mol / L.

The dimensions of the electrode plate were such that the thickness of the positive electrode plate was 180 μm,
Width 49mm, separator thickness 25μm, width 53mm,
The negative electrode plate has a thickness of 170 μm and a width of 51 mm, and the lead terminals are welded to the positive electrode plate and the negative electrode plate, respectively, and superimposed in order, with a rectangular core of polyethylene as a center, and a long side having a winding center axis of a power generating element. Was wound in an elliptical spiral shape around it so as to be in parallel with the above, to obtain a power generating element having a size of 53 × 35 × 4 mm.

Then, the insulating portion of the electrode is covered with a winding tape made of polypropylene (here, an adhesive is applied on one side) to the electrode width (the length of the power generation element parallel to the winding central axis of the power generation element). Was attached to the side wall of the power generation element parallel to the winding center axis, and the power generation element was stopped and fixed.

This was housed in a metal-laminated resin film case so that the winding axis of the elliptical wound type power generation element was perpendicular to the opening surface of the bag-shaped metal-laminated resin film case. At that time, 0.3 g of a powdery molecular sieve as an adsorbent having a molecular sieve action was inserted into the battery case. The molecular sieve used had a pore size large enough to adsorb carbon dioxide, and the cation contained in the molecular sieve was replaced with lithium ions. Thereafter, the electrodes and the separator were sufficiently wetted by the vacuum injection of the electrolyte so that free electrolyte did not exist outside the power generating element.

The laminated resin film uses a 12 μm PET film for surface protection as the outermost layer, a 9 μm aluminum foil as a barrier layer inside the PET film, and a 100 μm acid-modified low-density polyethylene layer as a heat welding layer as the innermost layer. . In this metal laminated resin film, the outermost PET film for surface protection and an aluminum foil as a barrier layer are bonded with a urethane-based adhesive. The positive electrode lead terminal and the negative electrode lead terminal have a thickness of 50 to 100.
It is a metal conductor of copper, aluminum, nickel or the like of μm.

Finally, a sealed unit cell (A) having a nominal capacity of 500 mAh according to the present invention was manufactured by sealing and welding. Further, except that the molecular sieve was not put in the battery case, the same as the battery (A) according to the present invention,
A comparative battery (B) was manufactured.

All of these batteries were manufactured at 25 ° C.
In the above, after charging to 4.1 V at a constant current of 500 mA and further performing constant voltage charging at 4.1 V for 2 hours,
The battery was discharged to 3 V at a constant current of 500 mA at -10 ° C. FIG. 1 shows the discharge capacity obtained at that time. Using these batteries, the battery was charged to 4.1 V at a constant current of 500 mA at 25 ° C., further charged at a constant voltage of 4.1 V for 2 hours, and then heated at 85 ° C. for 4 hours. FIG. 2 shows the amount of increase in battery thickness due to heating.

As can be seen from FIG. 2, when the concentration of the supporting electrolyte salt in the electrolytic solution is 0.8 mol / L, the swelling of the battery (A) according to the present invention and the comparative battery (B) when left at high temperature is small. Although there is almost no difference, when the concentration of the supporting electrolyte salt in the electrolytic solution is 0.9 mol / L or more, the swelling of the battery (A) according to the present invention at high temperature is small, but the comparative battery (B) is left at high temperature. As for the swelling, the swelling when left at a high temperature increased as the supporting electrolyte salt concentration increased. Therefore, conventionally, it is difficult to swell when left at high temperature in a charged state,
It has been difficult to produce a battery having excellent low-temperature discharge characteristics.

As described above, conventionally, in order to manufacture a battery which does not easily swell when left at a high temperature, the concentration of the supporting electrolyte salt in the electrolyte must be limited to 0.8 mol / L or less.
The battery according to the present invention including the molecular sieve having a hole sized to adsorb carbon dioxide in the battery case can suppress swelling when left at a high temperature compared to a comparative battery not using a molecular sieve. I understood. According to the present invention, it is difficult to swell when left at high temperature in a charged state,
It is understood that a battery having excellent low-temperature discharge characteristics can be manufactured.

[0057] Further, as the supporting electrolyte salt, in place of _{LiPF 6, LiClO 4, LiBF 4} , LiAsF 6, L
iCF ₃ CO ₂ , LiCF ₃ SO ₃ , LiN (SO ₂ CF ₃ )
₂ , LiN (SO ₂ CF ₂ CF ₃ ) ₂ , LiN (COCF ₃ )
_{In the case where 2} or LiN (COCF ₂ CF ₃ ) ₂ was used, the same result as that of LiPF ₆ was obtained.

As is clear from FIG. 1, when the concentration of the supporting electrolyte salt in the electrolytic solution exceeds 2 mol / L, the discharge capacity at a low temperature is greatly reduced. Therefore, according to the present invention, the supporting electrolyte salt concentration in the non-aqueous electrolyte is 0.9 mol /
It is particularly effective when the amount is L or more and 2 mol / L or less.

The weight of the molecular sieve provided in the battery case was 0.3 g, but this was 0.4, 0.
The same results as above were obtained when the amount was 5, 0.6, 0.7, 0.8, 0.9 or 1 g. Conversely, if less than 0.3 g, 0.2, 0.1, 0.05, 0.0
Even when the weight was set to 2, 0.01 g, the result was obtained that the swelling of the battery when left at a high temperature was suppressed as compared with the case where the molecular sieve was not used. However, if the molecular sieve is less than 0.3 g,
Compared with 0.3 g, the effect of suppressing battery swelling when left at high temperature was reduced.

Example 2 The procedure of Example 2 was repeated except that the weight ratio of ethylene carbonate and methyl ethyl carbonate in the electrolyte was 1: 9, 2: 8, 3: 7, 4: 6, and 5: 5, respectively. Battery (C) according to the present invention in the same manner as battery (A) according to the present invention using an electrolyte having a lithium hexafluorophosphate concentration of 1.0 mol / L manufactured in Example 1.
Was made. A comparative battery (D) was manufactured in the same manner as the battery (C) according to the present invention except that the molecular sieve was not placed in the battery case.

All of these fabricated batteries were stored at 25 ° C.
In the above, after charging to 4.1 V at a constant current of 500 mA and further performing constant voltage charging at 4.1 V for 2 hours,
The battery was discharged to 3 V at a constant current of 500 mA at -10 ° C. FIG. 3 shows the discharge capacity obtained at that time. Using these batteries, the battery was charged to 4.1 V at a constant current of 500 mA at 25 ° C., further charged at a constant voltage of 4.1 V for 2 hours, and then heated at 85 ° C. for 4 hours. FIG. 4 shows the amount of increase in battery thickness due to heating.

FIG. 4 shows that when the weight ratio of ethylene carbonate to the solvent in the electrolytic solution is 50%, the swelling of the battery (C) according to the present invention and the battery (D) for comparison at the time of being left at a high temperature is small. Almost the same, but when the weight ratio of ethylene carbonate to the solvent in the electrolyte was less than 50%,
Although the swelling of the battery (C) according to the present invention when left at high temperature did not change much, it was found that the swelling of the comparative battery (D) when left at high temperature increased as the weight ratio of ethylene carbonate decreased. .

On the other hand, as can be seen from FIG. 3, the discharge capacity at low temperature is lower when the weight ratio of ethylene carbonate to the solvent in the electrolyte is 50% than when the weight ratio is 10% or more and less than 50%. Has become quite small. When the weight ratio of ethylene carbonate to the electrolyte solvent is set to 10% or less, the irreversible capacity at the time of initial charging becomes large, and as a result, the charge / discharge capacity of the battery becomes small.

As described above, according to the present invention, the weight ratio of ethylene carbonate to the electrolyte solvent is 10% to 5%.
When it is less than 0%, it becomes possible to manufacture a battery which is less likely to swell when left at high temperature in a charged state and has excellent low-temperature discharge characteristics.

When dimethyl carbonate, diethyl carbonate or methyl propyl carbonate was used as the chain carbonate mixed with ethylene carbonate instead of methyl ethyl carbonate, the same results as those obtained with methyl ethyl carbonate were obtained. .

[Embodiment 3]
Twenty-one batteries (E) according to the present invention were manufactured in the same manner as the battery (A) according to the present invention using an electrolyte having a lithium hexafluorophosphate concentration of 1.0 mol / L. Also, 21 batteries (F) for comparison were manufactured in the same manner as the battery (E) according to the present invention except that the molecular sieve was not placed in the battery case.

These batteries were stored at 25 ° C. for 500
4.10V to 4.31 each at mA constant current
After charging to each voltage of 0.01 V in increments up to V and further performing constant voltage charging for 2 hours at each of the above voltages,
A capacity confirmation test was performed in which the battery was discharged to 3 V at 500 ° C. at a constant current of 500 ° C. FIG. 5 shows the discharge capacity obtained at that time.
Shown in FIG. 6 shows the increase in battery thickness due to heating when these batteries were charged in the same manner as in the capacity confirmation test and heated at 85 ° C. for 4 hours. From FIG. 6, when the charging voltage is 4.10 V, the swelling of the battery (E) according to the present invention and the comparative battery (F) when left at a high temperature is almost the same, but the charging voltage is 4.10 V. When the voltage is 11 V or more, the swelling of the battery (E) according to the present invention when left at high temperature does not change much, but the swelling of the comparative battery (F) when left at high temperature increases as the charging voltage increases. I understand.

Conventionally, in order to manufacture a battery that does not easily swell when left at high temperature, it is necessary to limit the voltage during charging to 4.10 V or less.
Moreover, it was difficult to produce a battery having a large discharge capacity and a high energy density.

From FIGS. 5 and 6, according to the present invention, it is possible to obtain a battery which does not easily swell when left at high temperature in a charged state, has a large discharge capacity, and has a high energy density.

The battery manufactured in the same manner as described above was used for 4.32 batteries.
When charged to V or more, the charge / discharge cycle characteristics were inferior, and practical life performance was not obtained. Therefore,
The present invention is particularly effective when combined with a charging method for charging to a voltage of 4.11 V or more and 4.31 V or less.

Example 4 As the non-aqueous solvent in the electrolytic solution,
A battery (A) according to the present invention using an electrolyte having a lithium hexafluorophosphate concentration of 1.0 mol / L manufactured in Example 1 except that γ-butyrolactone was used instead of methyl ethyl carbonate. Similarly, a conventionally known comparative battery (G) using no chain carbonate was produced. When the concentration of lithium hexafluorophosphate is 1.
Battery (A) according to the present invention using 0 mol / L electrolytic solution
And comparative battery (G) at 25 ° C. with 500 mA
The battery was charged to 4.1 V with a constant current, and further charged at a constant voltage of 4.1 V for 2 hours.
The battery was discharged to 3 V at a constant current of 0 mA. The discharge capacity obtained at that time was 117 mAh for the battery (A), while it was 52 mAh for the battery (G). From the above results, it is understood that excellent low-temperature discharge characteristics can be obtained by using the chain carbonate in the electrolytic solution.
From these results and the results in Examples 1 to 3, it is understood that the present invention makes it possible to manufacture a battery that does not easily swell when left at high temperatures and that exhibits excellent low-temperature discharge characteristics.

[0072]

According to the present invention, by providing a carbon dioxide adsorbent in a battery, carbon dioxide generated when the battery is left at a high temperature in a charged state is absorbed by the carbon dioxide adsorbent. For this reason, an increase in the internal pressure in the battery is suppressed, and the degree of swelling of the battery case is reduced. As a result, even if a charged battery is exposed to high temperatures due to being left in a car in the summer, the battery does not swell and does not fit in the electronic device, and the battery shape No distortion of the element shape due to
A non-aqueous electrolyte battery in which the distance between the negative electrodes is kept uniform and battery performance does not easily deteriorate can be obtained.

In the present invention, a chain carbonate is used as the non-aqueous solvent used in the non-aqueous electrolyte. Since the chain carbonate has a low viscosity and the ions can easily move, an excellent low-temperature discharge characteristic can be obtained by using the chain carbonate. However, since the chain carbonate easily decomposes when left at high temperature to generate gas, it has not been possible to manufacture a battery having both excellent low-temperature charge / discharge characteristics and low swelling at high temperature. In the present invention, by providing a chain carbonate in the electrolytic solution and combining a carbon dioxide adsorbent in the battery, it is difficult for the battery to swell when left at high temperatures and also has excellent low-temperature charge / discharge characteristics. Enables production.

[0074]

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between a supporting electrolyte salt concentration in an electrolytic solution and a low-temperature discharge capacity in a nonaqueous electrolyte battery and a comparative battery according to the present invention.

FIG. 2 is a graph showing the relationship between the concentration of a supporting electrolyte salt in an electrolyte and the amount of increase in battery thickness due to heating in a nonaqueous electrolyte battery and a comparative battery according to the present invention.

FIG. 3 is a diagram showing the relationship between the weight ratio of ethylene carbonate in the solvent in the electrolytic solution and the low-temperature discharge capacity in the nonaqueous electrolyte battery and the comparative battery according to the present invention.

FIG. 4 is a graph showing the relationship between the weight ratio of ethylene carbonate in the solvent in the electrolytic solution and the increase in battery thickness due to heating in the nonaqueous electrolyte battery and the comparative battery according to the present invention.

FIG. 5 is a diagram showing a relationship between a charging voltage and a discharge capacity in a nonaqueous electrolyte battery and a comparative battery according to the present invention.

FIG. 6 is a diagram showing the relationship between the charging voltage and the amount of increase in battery thickness due to heating in the nonaqueous electrolyte battery and the comparative battery according to the present invention.

Claims (8)

[Claims] 1. A non-aqueous electrolyte battery comprising a chain carbonate in an electrolyte and a carbon dioxide adsorbent provided in the battery. 2. The non-aqueous electrolyte battery according to claim 1, wherein the supporting electrolyte salt concentration in the non-aqueous electrolyte is 0.9 mol / L or more and 2 mol / L or less. 3. The non-aqueous electrolyte battery according to claim 1, wherein the chain carbonate is at least one selected from the group consisting of dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, and methyl propyl carbonate. . 4. The nonaqueous electrolyte battery according to claim 1, wherein the weight ratio of ethylene carbonate to the solvent of the nonaqueous electrolyte is 10% or more and less than 50%. 5. The non-aqueous electrolyte battery according to claim 1, wherein the positive electrode active material contains a cobalt atom or a nickel atom. 6. The non-aqueous electrolyte battery according to claim 1, wherein a rectangular parallelepiped or bag-shaped battery case is used. 7. The battery case according to claim 1, wherein a sheet in which a metal foil and a resin film are bonded or a metal containing aluminum as a main component is used.
7. The non-aqueous electrolyte battery according to 4, 5 or 6. 8. The non-aqueous electrolyte battery according to claim 1,
A method for charging a non-aqueous electrolyte battery, comprising charging to a voltage of 4.11 V or more and 4.31 V or less.