JP2003059536A - Nonaqueous electrolyte cell and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve high-rate discharge performance of a nonaqueous electrolyte cell with a little electrolyte solution. SOLUTION: With the manufacturing method of nonaqueous electrolyte cell consisting of a first process of making a power-generating element provided with a porous polymer at either of positive and negative pole plates and a separator, a second process of housing the power-generating element in a cell vessel, and a third process of pouring nonaqueous electrolyte solution of not less than 30% and not more than 100% against the total hole volume of the positive and negative pole plates, the separator, and the porous polymer electrolyte, another process is provided, after the third process, for heating the cell at temperature of not less than 40 deg.C.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a non-aqueous electrolyte battery and a method for manufacturing the same.

[0002]

2. Description of the Related Art Due to the rapid development of portable electronic devices, there has been an urgent need to improve the performance of batteries used as the power source thereof. One of the batteries is a lithium secondary battery using metallic lithium for the negative electrode. Since lithium shows the lowest potential among metals and has a small specific gravity, lithium batteries have high energy density. However, since dendrites of lithium are deposited by repeated charging / discharging, there are problems in cycle performance and safety.

Therefore, a lithium ion secondary battery using graphite or carbon as the negative electrode active material has been devised. Lithium-ion secondary batteries are less prone to dendrites, and thus have improved safety over lithium batteries.

[0004]

Since non-aqueous electrolyte batteries such as lithium ion secondary batteries contain a large amount of combustible electrolyte, the battery temperature rises due to external heating or internal short circuit. At this time, there is a problem that gas is generated due to the reaction between the electrolytic solution and the positive and negative electrode active materials, and the safety of the battery is impaired. Therefore, it was considered to improve safety by reducing the amount of electrolytic solution in the battery.

However, when the amount of the electrolytic solution is 100% or less with respect to the total pore volume of the positive and negative electrode plates and the separator, there is a problem that the high rate discharge performance of the battery is significantly reduced. The reason for this is that the electrolyte does not evenly permeate the entire battery, especially inside the porous positive and negative plates, in the pores of the separator, and between the plates and the separator. Was not uniform.

The present invention solves these problems, and an object thereof is to improve the high rate discharge performance of a non-aqueous electrolyte battery having a small amount of electrolyte.

[0007]

The invention of claim 1 relates to a method for producing a non-aqueous electrolyte battery, in which at least one of a positive electrode plate and a negative electrode plate and a separator are provided with a porous polymer electrolyte. And a second step of accommodating the power generation element in a battery container, and the total pore volume of the positive and negative electrode plates, the separator and the porous polymer electrolyte is 30% or more and 100% or less. A method of manufacturing a non-aqueous electrolyte battery, comprising a third step of injecting a non-aqueous electrolyte solution, characterized by comprising a step of heating the battery at a temperature of 40 ° C. or higher after the third step. .

According to the invention of claim 1, the distribution of the electrolytic solution in the battery becomes uniform, and a non-aqueous electrolyte battery excellent in high rate discharge performance can be obtained.

According to a second aspect of the present invention, in the method for producing a non-aqueous electrolyte battery according to the first aspect, the melting point (Tpm) of the porous polymer electrolyte, the melting point (Tsm) of the separator and the boiling point (Teb) of the electrolytic solution are set. Among them, the battery is characterized by being heated at the lowest temperature or lower.

According to the second aspect of the present invention, the excellent high rate discharge performance of the battery can be maintained, and at the same time, the expansion of the battery can be prevented.

The invention of claim 3 is characterized in that, in the method for producing a non-aqueous electrolyte battery according to claim 1 or 2, the battery in a discharged state is heated.

According to the third aspect of the invention, it is possible to suppress the deterioration of the high rate discharge performance of the battery.

The invention of claim 4 is the invention of claim 1, 2 or 3.
The non-aqueous electrolyte battery obtained by the manufacturing method described above is characterized in that the gas in the battery contains 1% by volume or more of carbon dioxide.

According to the invention of claim 4, the high rate discharge performance of the battery can be remarkably improved.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing a non-aqueous electrolyte battery of the present invention comprises a first step of producing a power generating element having a porous polymer electrolyte on at least one of the positive and negative electrode plates and a separator, and Second step of accommodating the power generating element in the battery container, and injecting 30% or more and 100% or less of the non-aqueous electrolyte solution with respect to the total pore volume of the positive / negative electrode plates, the separator and the porous polymer electrolyte The method for producing a non-aqueous electrolyte battery including the third step is characterized by including a step of heating the battery at a temperature of 40 ° C. or higher after the third step.

The porous polymer electrolyte is a combination of a porous polymer and an organic electrolytic solution. By containing an organic electrolytic solution in the pores of the polymer, lithium ions can move through the pores, By wetting or swelling the part with the organic electrolyte, lithium ions can move in the polymer. Further, the porous polymer electrolyte preferably has a network structure, more preferably a three-dimensional network structure. The porosity is preferably 10% or more and 90% or less, more preferably 30% or more and 90% or less, and further preferably 40% or more and 80% or less.

In the first step of the method for producing a non-aqueous electrolyte battery of the present invention, a power generating element having a porous polymer electrolyte on at least one of the positive and negative electrode plates and the separator is produced. The positive and negative electrode plates are provided with a porous mixture layer containing an active material, and the electrode plate provided with a porous polymer electrolyte means that the mixture layer has pores inside or inside the mixture layer surface. The polymer electrolyte is present, and the separator provided with the porous polymer electrolyte means that the porous polymer electrolyte is present in the pores or on the surface of the separator.
Further, the power generation element can be manufactured by combining these positive and negative electrode plates and a separator.

The porous polymer electrolyte may be present in at least a part of the mixture layer of the electrode plate or the pores of the separator, but it is preferable that it is uniformly distributed in these pores. Further, at least one of the positive and negative electrode plates may be provided with the porous polymer electrolyte, but it is preferable that both the positive and negative electrode plates are provided with the porous polymer electrolyte. Further, the separator may be a porous polymer electrolyte.

In the second step of the method for producing a non-aqueous electrolyte battery of the present invention, the power generating element obtained in the first step is housed in a battery container. Then, in the third step, 30% or more and 100% or less of a non-aqueous electrolyte solution is injected to the total pore volume of the positive and negative electrode plates, the separator and the porous polymer electrolyte.
When the amount of the electrolyte solution with respect to the total pore volume exceeds 100%, the safety of the battery is deteriorated because an extra electrolyte solution exists in the battery. Further, when the amount of the electrolytic solution with respect to the total pore volume is less than 30%, the electrolytic solution becomes insufficient, and the electrode reaction is slow.
The discharge capacity will decrease.

Since the amount of the electrolyte solution is small in the battery containing the electrolyte solution amount of 30% or more and 100% or less with respect to the total pore volume of the positive and negative electrode plates, the separator and the porous polymer electrolyte,
The high rate discharge performance of the battery was not sufficient because the electrolyte was unevenly distributed inside the positive electrode plate or negative electrode plate, in the pores of the separator, between the electrode plate and the separator, etc. . Further, even in a non-aqueous electrolyte battery comprising a porous polymer electrolyte in at least one of the positive and negative electrode plates and the separator, since the porous polymer electrolyte does not sufficiently absorb the electrolyte solution at around room temperature, its high rate The discharge performance was not sufficient.

Therefore, the method for producing a non-aqueous electrolyte battery of the present invention has a step of heating the battery at a temperature of 40 ° C. or higher after the third step, so that the porous polymer provided in the electrode plate or the separator is provided. Since the electrolyte sufficiently absorbs the electrolyte solution, the electrolyte solution permeates the entire battery, and even after the battery temperature is returned to room temperature, the distribution of the electrolyte solution in the battery becomes uniform, and as a result, The rate discharge performance is also good.

In the manufacture of a non-aqueous electrolyte battery, usually, after the step of injecting the electrolytic solution, the step of sealing the battery container,
Go through the steps of charging the battery. In the present invention, the step of heating the battery may be performed after the third step of injecting the electrolytic solution, and the step of heating the battery, the step of sealing the battery container, and the step of charging the battery , In any order.

The temperature for heating the battery is 4
The temperature is preferably 0 ° C. or higher, more preferably 60 ° C. or higher, and further preferably 80 ° C. or higher in order to allow the porous polymer electrolyte to sufficiently absorb the electrolytic solution.

The heating temperature of the battery is determined by the melting point of the porous polymer electrolyte (Tpm) and the melting point of the separator (Tsm).
And the boiling point (Teb) of the electrolytic solution, the temperature is set to the lowest temperature or lower.

When the heating temperature is not higher than the melting point (Tpm) of the porous polymer electrolyte, the pores of the porous polymer electrolyte are less likely to be blocked, and the excellent high rate discharge performance of the battery can be maintained. Furthermore, the melting point of the porous polymer electrolyte is T
When it is set to pm, it is preferable to set it as (Tpm-10) ° C or less, and it is preferred to set it as (Tpm-20) ° C.

The heating temperature of the battery depends on the melting point (Ts) of the separator.
When it exceeds m), the pores of the separator are closed and the high rate discharge performance of the battery is significantly reduced. Therefore, if the heating temperature is set to be equal to or lower than the melting point (Tsm) of the separator, the holes of the separator are not blocked, and the excellent high rate discharge performance of the battery can be maintained. Furthermore, the heating temperature is (Tsm-10) ° C.
The following is preferable, and (Tsm-20) ° C or less is more preferable.

Furthermore, the heating temperature is set to the boiling point (Te
In the case of b) or less, it is possible to prevent the electrolytic solution from becoming a gas, increasing the internal pressure of the battery, and expanding the battery.

In the present invention, the total pore volume of the positive and negative electrode plates, the separator and the porous polymer electrolyte can be determined as follows. First, charging / discharging the non-aqueous electrolyte battery is repeated 5 times or more, and the positive electrode plate, the negative electrode plate, the separator, and the porous polymer electrolyte are taken out from the battery. Next, they are washed with a solvent such as dimethyl carbonate (DMC), dried, and then their pore volume is measured with a mercury porosimeter. Moreover, in order to further improve the cycle performance of the battery, the amount of the electrolytic solution is preferably 40% or more, and more preferably 60% or more.

As a method of heating the battery, a constant temperature bath, a water bath, an oil bath or the like can be used. Further, as the heating time, an optimum heating time may be selected according to the size of the battery and the heating temperature.

Further, the present invention is characterized in that in the above method for producing a non-aqueous electrolyte battery, the battery in a discharged state is heated. When the battery in the charged state is heated, the reaction between the positive and negative electrode active materials and the electrolytic solution is likely to proceed, so that the high rate discharge performance of the battery is significantly lowered. Therefore, in the present invention, by heating the battery in the discharged state, the deterioration of the high rate discharge performance of the battery is suppressed.

Here, the battery in the discharged state means a state in which a constant capacity is discharged from the charged state when the discharge capacity at room temperature is C _D (Ah). Here, when the discharge capacity from the charged state is Cx (Ah), the discharge depth is (Cx / C
_D ) × 100. In the present invention, the depth of discharge when heating the battery is preferably 20% or more, more preferably 50% or more, and most preferably 70% or more.

Further, the present invention is characterized in that in the non-aqueous electrolyte battery obtained by the above-mentioned manufacturing method, the gas in the battery contains 1% by volume or more of carbon dioxide. Here, the content rate of carbon dioxide is defined by (volume of carbon dioxide / (volume of carbon dioxide + volume of other gas)) × 100 / volume%. The volume of those gases can be measured by a gas chromatograph. Further, its content is preferably 10% by volume or more, more preferably 30% by volume or more, and preferably 50% by volume or more. Further, the gas other than carbon dioxide is not particularly limited, but air that is present in a large amount and is inexpensive is preferable.

When the battery is heated, the reaction between the positive and negative electrode active materials and the electrolytic solution is promoted, and as a result, the high rate discharge performance is lowered. In the present invention, the high rate discharge performance of the battery is remarkably improved by previously inserting an appropriate amount of carbon dioxide into the battery. The reason is that reduction of carbon dioxide on the surface of the negative electrode active material forms a film of lithium carbonate on the surface, and as a result, reductive decomposition of the electrolytic solution is suppressed. Furthermore, it is considered that the progress of the decomposition reaction can be suppressed by previously putting carbon dioxide, which is a product of oxidative decomposition of the electrolytic solution in the positive electrode plate, into the battery.

The porous polymer electrolyte is preferably one having flexibility capable of responding to expansion / contraction of the volume of the active material due to charging / discharging, and further, the polymer is preferably wetted or swollen with an electrolytic solution. Specifically, polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyethylene oxide (PEO), polypropylene oxide (PPO), polymethyl methacrylate (PMMA), polyvinyl fluoride, polyvinyl chloride, polyvinylidene chloride, Polymethyl acrylate,
Polymethacrylonitrile, polyvinyl acetate, polyvinylpyrrolidone, polyethylene terephthalate, polyhexamethylene adipamide, polycaprolactam, polyvinyl alcohol, polyurethane, polyethyleneimine, polycarbonate, polytetrafluoroethylene,
Polyethylene, polypropylene, polybutadiene, polystyrene, polyisoprene, carboxymethyl cellulose, methyl cellulose and derivatives thereof can be used alone or in combination.

Further, a combination of the monomers constituting these polymers can be used. Specifically, vinylidene fluoride / hexafluoropropylene copolymer (P (VdF / HFP)), styrene butadiene rubber, ethylene propylene rubber, styrene elastomer, fluorine elastomer, olefin elastomer, etc. can be used. Among them, P
VdF, P (VdF / HFP), PAN, PEO, P
It is preferable to use PO, PMMA and their derivatives alone or in combination.

Furthermore, polymers containing fluorine are most preferred. Polymers containing fluorine such as PVdF and P (VdF / HFP) are electrochemically stable as compared with other polymers, and therefore can be used for all positive and negative electrode plates and separators.

As a method for producing the porous polymer, a method of phase-separating the polymer from the solution is desirable. Examples of the method include temperature change due to heating or cooling of the polymer solution, concentration change due to evaporation of the solvent of the polymer solution, etc., but particularly extraction of the solvent from the polymer solution,
That is, the solvent extraction method is preferable. Specifically, a method of extracting the first solvent by immersing the polymer solution in a second solvent that is incompatible with the polymer and compatible with the first solvent of the polymer solution. is there. As a result, the portions where the first solvent has been removed become pores, so that a porous polymer can be produced. In this method, circular holes are formed in the polymer.

Further, as a method for producing a porous polymer,
Those that utilize the change in the solubility of the polymer with respect to temperature are also preferable. In this method, the polymer is supersaturated by dissolving the polymer in a third solvent at a certain temperature and then lowering the temperature of the polymer solution, so that the polymer and the third solvent are phase-separated in the solution. . The porous polymer can then be prepared by removing the third solvent.

The porous polymer obtained by the above method is wetted or swollen with an electrolytic solution to obtain a porous polymer electrolyte.

The first solvent used in the method for producing the porous polymer may be any solvent capable of dissolving the polymer, and specifically, propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC). ), Diethyl carbonate (DEC), carbonic acid ester such as methyl ethyl carbonate (MEC), dimethyl ether, diethyl ether, ethyl methyl ether, ether such as tetrahydrofuran, methyl ethyl ketone, ketone such as acetone, dimethyl formamide, dimethyl acetamide, 1-methyl- Examples thereof include pyrrolidinone and N-methyl-2-pyrrolidone (NMP).

The third solvent is preferably one in which the solubility of the polymer at a certain temperature is low and the polymer is easily dissolved at a higher temperature. For example, methyl ethyl ketone, ketones such as acetone, PC, E
Carbonic acid esters such as C, DMC, DEC and MEC, dimethyl ether, diethyl ether, ethyl methyl ether, ethers such as tetrahydrofuran, dimethylformamide and the like are preferable. Among them, the third solvent is preferably a ketone, particularly preferably methyl ethyl ketone.

The second solvent may be any solvent that is incompatible with the polymer and compatible with the first solvent.
For example, water, alcohol, acetone, etc. may be mentioned. Furthermore, you may use these mixed solutions.

In the present invention, a battery containing carbon dioxide in an amount of 1% by volume or more is manufactured by putting carbon dioxide into the battery and then closing the hole of the container. Here, the step of adding carbon dioxide may be performed before or after the step of adding the electrolytic solution. Further, carbon dioxide and the electrolytic solution may be added at the same time. Furthermore, the step of initial charging may be performed before or after the step of adding carbon dioxide.

Since the distribution of the electrolyte is non-uniform from the time the electrolyte is put into the battery until charging and discharging are repeated, carbon dioxide is preferably contained in the battery at the time of initial charging. As a result, a uniform film is formed on the surface of the negative electrode active material, and gas generation can be suppressed. further,
The step of closing the battery container may be performed before or after the initial charging step.

Further, in the present invention, it is preferable that the pressure of the battery is reduced and then carbon dioxide is put therein. At that time, it is preferable to reduce the pressure of the battery to 0.09 MPa or less. Further, the pressure is preferably 0.05 MPa or less, more preferably 0.01 MPa or less. Further, the pressure inside the battery container after closing the hole is preferably equal to or lower than the pressure outside the hole.

As the solvent for the electrolytic solution, an aprotic solvent is preferable. Specifically, EC, PC, butylene carbonate, DMC, DEC, MEC, γ-butyrolactone, sulfolane, dimethyl sulfoxide, acetonitrile, dimethylformamide, dimethylacetamide,
1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, methyl acetate, NM
P, 4-methyl-1,3-dioxolane, N-methylpyrrolidine, ethyl methyl ketone, methyl propionate, acetone, diethyl ether, ethyl methyl ether, dimethyl ether, etc., or mixtures thereof may be used.

Further, as the salt contained in the electrolytic solution,
LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiCl
O ₄ , LiSCN, LiI, LiCF ₃ SO ₃ , Li
C ₄ F ₉ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC
1, lithium salts such as LiBr, LiCF ₃ CO ₂ or mixtures thereof are preferred.

Further, the positive electrode active material of the present invention may be any compound capable of inserting and extracting lithium. For example, as the inorganic compound, the composition formula Li _x MO ₂ or Li
_y M ₂ O ₄ (where M is a transition metal, 0 ≦ x ≦ 1, 0 ≦ y
A complex oxide represented by ≦ 2), an oxide having a tunnel-shaped hole, a metal chalcogenide having a layered structure, or the like can be used. Specific examples thereof include LiCoO ₂ and Li.
NiO ₂ , LiMn ₂ O ₄ , NiOOH, LiFeO ₂ , T
Examples include iS ₂ , TiO ₂ , V ₂ O ₅ , MnO _{2 and the} like.
Alternatively, it is also possible to use inorganic compound obtained by substituting a part by another element, for _example, LiCo _{0.9 Al} 0.1 _{O 2,}
LiMn _1.85 Al _0.15 O ₄ , LiNi _0.5 M
Examples include n _1.5 O ₄ , Ni _0.80 Co _0.20 OOH, and the like. Examples of organic compounds include conductive polymers such as polyaniline. Further, those positive electrode active materials may be mixed and used.

Particularly in the present invention, nickel is used as the positive electrode active material.
Cycle performance of non-aqueous electrolyte battery using lithium oxide
Is improved. The lithium nickelate in the present invention is particularly limited.
Although not specified, as a typical one, LiNiO₂And
And some of them are replaced with other elements. Specifically
Is LiNi_0.80Co_0.20O_Two, LiNi
_0.80Al_0.20O_Two, LiNi_0.80Co
_0.17Al_0.03O_TwoIs mentioned. In addition,
Even if the lithium kerate contains another active material, the present invention
Is effective. For example, lithium cobalt oxide, man
Examples thereof include a mixture with lithium cancerate and the like.

Further, as a conductive agent, carbon black such as acetylene black, graphite,
A conductive polymer or the like may be mixed.

As the negative electrode active material, for example, graphite
Carbon materials such as gallium and carbon, Al, Si, Pb, S
An alloy of lithium with n, Zn, Cd, etc., LiFe_TwoO
_ThreeTransition metal composite oxides such as WO_Two, MoO_TwoSuch as
Transition metal oxide, Li_3-xM _xN (however, M is a transition
Metal, lithium nitride such as 0 ≦ x ≦ 0.8), or
Examples include metallic lithium. Also a mixture of these
May be used. Carbon materials include coke and meso-ca
Carbon micro beads (MCMB), mesophase pick
Graphitization of H-based carbon fiber, pyrolysis vapor grown carbon fiber, etc.
Carbon, Phenol resin fired body, Polyacrylonitrile
-Based carbon fiber, pseudo-isotropic carbon, furfuryl alcohol resin
Non-graphitizable carbon such as fired body, natural graphite, artificial graphite, black
Leaded MCMB, graphitized mesophase pitch carbon fiber,
Graphite materials such as graphite whiskers, as well as blends of these
There is a compound.

As the current collectors for the positive electrode plate and the negative electrode plate,
Iron, copper, aluminum, stainless steel, nickel and the like can be used. The shape may be any of sheet, foam, sintered porous body, expanded lattice, and the like. Further, the current collector may be perforated in any shape.

The binder for adhering the active material, the conductive agent and the current collector is preferably a flexible material capable of responding to expansion and contraction of the volume of the active material due to charge and discharge, and therefore the porous polymer. Polymers similar to the electrolyte can be used. For example, as the binder for the positive electrode plate, an electrochemically stable polymer containing fluorine is preferable, and specifically,
Polymers such as PVdF, P (VdF / HFP), and fluorine-based elastomers and their derivatives can be used alone or in combination. . On the other hand, as the binder for the negative electrode plate, PVdF, P (VdF / HFP), a fluorine-containing polymer such as a fluorine-based elastomer, styrene butadiene rubber, ethylene propylene rubber, carboxymethyl cellulose, methyl cellulose and derivatives thereof alone or It can be mixed and used.

As the separator, a microporous film of polyolefin such as polyethylene or polypropylene is preferable. Alternatively, a microporous film formed by laminating polyethylene and polypropylene may be used.

As the battery container, a metal such as stainless steel, iron, or aluminum, a laminate of a metal such as aluminum and a polymer, a polymer such as polyethylene or polypropylene, or the like can be used.

[0056]

The preferred embodiments of the present invention will be described below.

Example 1 First, the relationship between the heating temperature and the high rate discharge performance of the non-aqueous electrolyte battery was examined.

The positive electrode plate was manufactured as follows. Lithium nickelate (LiNi _{0.8 5} Co
_0.15 O ₂ ) 55 wt%, acetylene black 2 wt
%, PVdF 4 wt%, NMP 39 wt%, and then mix it with a width of 100 mm, a length of 600 mm, and a thickness of 20 μ.
m aluminum foil was applied to both sides and dried at 100 ° C.

The negative electrode plate was manufactured as follows. Graphite 50wt%, PVdF 5wt%, NMP45
After mixing wt%, it is 100mm in width and 60 in length
Apply to both sides of 0mm, 10μm thick copper foil, and 1
It was dried at 00 ° C.

Next, 6 and 4 wt% P (VdF /
The polymer solution was impregnated into the holes of the electrode plate by immersing the positive and negative electrode plates in the NMP solution of HFP). Here, VdF and HF of this P (VdF / HFP)
The molar ratio with P was VdF: HFP = 95: 5, and this polymer was used in the examples unless otherwise specified. Then, the excess polymer solution on the surface of the electrode plate was removed by passing the electrode plate between rollers. Furthermore, by immersing the positive and negative electrode plates in 0.001 mol / l phosphoric acid aqueous solution and deionized water respectively,
NMP was extracted to form a porous polymer in and on the surface of the electrode plate.

Then, by pressing,
The positive electrode plate was thinned from 270 μm to 165 μm, and then cut into a size of 26 mm in width and 495 mm in length. Similarly, change the thickness of the negative electrode plate from 250 μm to 195 μm.
Then, it was cut into a size of width 27 mm and length 450 mm.

Next, a polyethylene separator provided with a porous polymer was produced by the following method. The polyethylene separator has a thickness of 20 μm and a width of 29.5 m.
m and porosity of 40% were used. First, the separator was immersed in a 20 wt% P (VdF / HFP) solution, taken out, and then passed between two rollers. Then, the separator was immersed in deionized water and then dried. The thickness of the polyethylene separator provided with the porous polymer was 23 μm.

Next, after winding the positive and negative electrode plates and a polyethylene separator provided with a porous polymer, a height of 48.0 mm, a width of 29.2 mm and a thickness of 5.0 m.
m aluminum container. Furthermore, 1 mol / l of Li was added to a mixed solution of EC and DEC having a volume ratio of 1: 1.
1.20 g of the electrolyte solution containing PF ₆ (100% of the electrolyte solution volume is 2.00 g based on the total pore volume of the positive and negative electrode plates, the separator and the porous polymer electrolyte, and therefore 1.2
The amount of 0 g was 60% of the total pore volume of the electrolytic solution). Here, the porous polymer holds the electrolytic solution in the pores, and at the same time, the polymer portion swells with the electrolytic solution to become a porous polymer electrolyte.

Thereafter, the battery was placed under a reduced pressure of 0.008 MPa, carbon dioxide was put into the battery, and then 148
A battery with a nominal capacity of 740 mAh was made by charging at a current value of mA for 1 hour and closing the hole in the battery container. The container of the battery was equipped with a non-reset type safety valve.

After that, these batteries were placed in a constant temperature bath,
It was heated at a temperature of 30 ° C to 120 ° C for 15 minutes and then left at room temperature. Next, these batteries were tested under the following conditions. 4.2V at 148mA constant current at 25 ℃
The battery was charged up to 4.2 V and further charged at 4.2 V for 2 hours. Next, 2.75 at a constant current of 1480 mA corresponding to high rate discharge.
Discharged to V.

FIG. 1 shows the relationship between the heating temperature of the battery and the discharge capacity.
Shown in. From FIG. 1, it was found that heating at a temperature of 40 ° C. or higher increases the discharge capacity. further,
When the heating temperature is over 60 ℃, the discharge capacity increases greatly,
The discharge capacity increases most at 100 ° C to 100 ° C.
It was found that even at ˜110 ° C. the discharge capacity increased compared to heating at 30 ° C. However, when heated at 120 ° C, the discharge capacity was about the same as when heated at 30 ° C.

By heating the battery at a temperature of 40 ° C. or higher, the porous polymer electrolyte sufficiently absorbs the electrolytic solution, so that the electrolytic solution permeates the entire battery. Therefore, even after returning the temperature to room temperature, the distribution of the electrolyte solution in the mixture layer of the electrode plate, in the holes of the separator, between the electrode plate and the separator becomes uniform, and as a result, its high rate discharge performance is improved. Is considered to have improved.

Further, when the heating temperature of the battery is 120 ° C., the melting point of the separator or the porous polymer electrolyte is exceeded, so that the holes of the separator are closed, and as a result, the high rate discharge performance of the battery is deteriorated. Also, 100 to 11
It is considered that the cause of the slight decrease in the discharge performance at 0 ° C is that the pores of the porous polymer electrolyte are blocked.

[Example 2] Next, the relationship between the amount of electrolytic solution and the high rate discharge performance was examined. In the battery of Example 1,
An injection amount of 0.40 g to 2.60 g of electrolyte (20% to 130% of the total pore volume of the positive and negative electrode plates, the separator, and the porous polymer electrolyte) was injected. , It was heated at a temperature of 80 ° C. for 15 minutes. afterwards,
These batteries were tested under the same conditions as in Example 1.

The relationship between the amount of electrolytic solution and the high rate discharge performance is shown in FIG. From FIG. 2, 30% to 100% of the total pore volume
It was found that the discharge capacity was increased in the battery containing the amount of electrolyte solution. That is, it was found that by heating the battery, the high rate discharge performance of the battery having a small amount of electrolyte was improved.

[Example 3] Furthermore, the relationship between the discharge depth and discharge capacity of the battery when the battery was heated was examined. Using the battery of Example 1, at 25 ° C., a constant current of 148 mA, 4.2 V
The battery was charged up to 4.2 V and further charged at 4.2 V for 2 hours. Next, the battery was discharged at a constant current of 148 mA to 2.75 V, the discharge capacity at this time was set to C _D (Ah), and this state was set to a discharge depth of 100% of the battery. And a battery with a discharge depth of 0%
0.9 C _D (Ah) was discharged at a constant current of 148 mA to obtain a battery having a discharge depth of 90%. Similarly, a battery having a discharge depth of 10% to 80% was manufactured by discharging the battery for a certain period of time. Next, the batteries were heated at 80 ° C. for 15 minutes and then left at room temperature. Then, the battery was charged and discharged under the same conditions as in Example 1.

FIG. 3 shows the relationship between the depth of discharge and the discharge capacity when the battery is heated. From FIG. 3, it was found that if the battery is heated in a slightly discharged state, the discharge capacity is increased as compared with the battery that is not discharged at all. Especially, the depth of discharge is 20
It was found that the discharge capacity increased as the depth of discharge deepened when the battery was heated at a rate of not less than%. By heating the battery in the discharged state, the reaction between the positive / negative electrode active material and the electrolytic solution is less likely to proceed, and it is considered that the deterioration of the high rate discharge performance is suppressed.

[Example 4] Further, the relationship between the carbon dioxide concentration in the gas in the battery and the discharge capacity was examined. Using the battery of Example 1, the carbon dioxide concentration in the gas in the battery was set to 0,0.
5, 1, 10, 20, 30, 40, 50, 60, 70,
80, 90 and 100% by volume, these batteries at a depth of discharge of 100% and heated at 80 ° C. for 15 minutes,
It was left at room temperature. Then, these batteries were charged and discharged under the same conditions as in Example 1.

FIG. 4 shows the relationship between the carbon dioxide concentration in the gas in the battery and the discharge capacity. From FIG. 4, it was found that the discharge capacity was increased by setting the carbon dioxide concentration in the gas in the battery to be 1% by volume or more. Furthermore, it was found that the discharge capacity increased as the carbon dioxide concentration in the gas in the battery increased. As described above, it was found that the high-rate discharge performance of the battery was remarkably improved by previously inserting an appropriate amount of carbon dioxide into the battery.

The reason is that reduction of carbon dioxide on the surface of the negative electrode active material forms a film of lithium carbonate on the surface, and as a result, reductive decomposition of the electrolytic solution at high temperature is suppressed. Further, it is considered that the progress of the decomposition reaction at high temperature can be suppressed by previously inserting carbon dioxide, which is an oxidative decomposition product of the electrolytic solution in the positive electrode plate, into the battery.

[0076]

The method for producing a non-aqueous electrolyte battery of the present invention comprises:
A first step of producing a power generating element provided with a porous polymer electrolyte in at least one of the positive and negative electrode plates and a separator, and a second step of housing the power generating element in a battery container,
Manufacture of a non-aqueous electrolyte battery comprising a positive / negative electrode plate, a separator and a third step of injecting a non-aqueous electrolyte solution of 30% or more and 100% or less with respect to the total pore volume of the porous polymer electrolyte. The method is characterized by including a step of heating the battery at a temperature of 40 ° C. or higher after the third step.

In the battery with a small amount of electrolyte, the electrolyte was unevenly distributed, so the high rate discharge performance of the battery was not sufficient. Further, even in a non-aqueous electrolyte battery having a porous polymer electrolyte in at least one of the positive and negative electrode plates and the separator, the performance is not sufficient because the polymer electrolyte does not sufficiently absorb the electrolytic solution near room temperature. There wasn't.

According to the production method of the present invention, since the porous polymer electrolyte provided in the electrode plate or the separator sufficiently absorbs the electrolytic solution, the electrolytic solution permeates the entire battery,
Even after the temperature of the battery is returned to room temperature, the distribution of the electrolytic solution in the battery becomes uniform, and as a result, the high rate discharge performance of the battery also becomes good.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a heating temperature of a battery and a discharge capacity.

FIG. 2 is a diagram showing a relationship between an electrolytic solution amount and a discharge capacity.

FIG. 3 is a diagram showing the relationship between the depth of discharge and the discharge capacity when the battery is heated.

FIG. 4 is a diagram showing a relationship between a carbon dioxide concentration in a battery and a discharge capacity.

Claims (4)

[Claims] 1. A first step of producing a power generation element including a porous polymer electrolyte on at least one of the positive and negative electrode plates and a separator, and a second step of housing the power generation element in a battery container. Manufacture of a non-aqueous electrolyte battery comprising a positive / negative electrode plate, a separator and a third step of injecting a non-aqueous electrolyte solution of 30% or more and 100% or less with respect to the total pore volume of the porous polymer electrolyte. A method for producing a non-aqueous electrolyte battery, which comprises a step of heating the battery at a temperature of 40 ° C. or higher after the third step in the method. 2. The melting point (Tpm) of the porous polymer electrolyte.
And melting point of separator (Tsm) and boiling point of electrolyte (Te
The method for producing a non-aqueous electrolyte battery according to claim 1, wherein the battery is heated at the lowest temperature or lower in b). 3. The method for producing a non-aqueous electrolyte battery according to claim 1, wherein the battery in a discharged state is heated. 4. The non-aqueous electrolyte battery obtained by the method according to claim 1, 2 or 3, wherein the gas in the battery contains 1% by volume or more of carbon dioxide.