JP2008218268A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery capable of reducing the amount of carbon dioxide generated from a positive electrode plate even when charging and discharging cycles are repeated in high temperature storage or under high temperature. <P>SOLUTION: The nonaqueous electrolyte secondary battery includes: an electrode plate group 4 formed by laminating or winding around a belt-like positive electrode plate 5 and negative electrode plate 6 through a separator 7; and a nonaqueous electrolyte. On a surface of the positive electrode plate 5 opposite to the separator 7, a fluorine-containing resin layer is provided which suppresses generation of carbon dioxide from the positive electrode plate 5. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for improving high-temperature storage characteristics and charge / discharge cycle characteristics under high temperature of a non-aqueous electrolyte secondary battery, and more particularly to a technique for suppressing gas generation from a positive electrode plate when stored at a high temperature.

  In recent years, electronic devices have become portable and cordless, and there is an increasing demand for secondary batteries that are small, lightweight, and have high energy density as power sources for driving these devices. Therefore, expectation for non-aqueous electrolyte secondary batteries having high voltage and high energy density, particularly lithium secondary batteries, is increasing.

  Among them, demand for non-aqueous electrolyte secondary batteries is growing, and demands for smaller and lighter weight are increasing. On the other hand, gas generation from the positive electrode plate when carbon dioxide is stored at high temperature (carbon dioxide gas) Has been a traditional problem. Due to this gas generation, in the cylindrical non-aqueous electrolyte secondary battery equipped with a current cutoff valve, the internal pressure in the battery may increase, and the current cutoff valve may malfunction. In addition, the prismatic nonaqueous electrolyte secondary battery has a problem that the battery case expands due to gas generation.

  Since gas generation during high-temperature storage is caused by an oxidation reaction between the non-aqueous electrolyte and the positive electrode active material, the solvent composition of the non-aqueous electrolyte is optimized to a composition resistant to the oxidation reaction as a means to prevent this. A method has been proposed (see, for example, Patent Document 1).

In addition, the method of suppressing the oxidative decomposition of the non-aqueous electrolyte by reducing the amount of metal elution from the positive electrode active material that acts as a catalyst by promoting the oxidative decomposition of the non-aqueous electrolyte by changing the material of the separator or modifying the surface Etc. have been proposed (see, for example, Patent Document 2).
JP 2002-83632 A Japanese Patent No. 3838492

Patent Documents 1 and 2 described above are methods for suppressing the generation of carbon dioxide gas accompanying oxidative decomposition of a nonaqueous electrolytic solution. However, in these methods, carbon dioxide gas is generated when the nonaqueous electrolyte secondary battery is stored at a high temperature for a long time or when the charge / discharge cycle is repeated at a high temperature, and the battery of the rectangular nonaqueous electrolyte secondary battery is produced. The problem that the case swells and the problem that the current cutoff valve of the cylindrical non-aqueous electrolyte secondary battery may malfunction could not be solved. Therefore, as a result of investigating the mechanism of carbon dioxide generation, lithium carbonate (Li ₂ CO ₃ ) remaining in the positive electrode active material is electrochemically oxidized and decomposed in addition to the oxidative decomposition of the non-aqueous electrolyte. It was determined that gas was generated (see Chemical Formula 1).

(Chemical formula 1)
Li ₂ CO ₃ → Li ₂ O + CO ₂ ↑
Further, this lithium carbonate is hardly present in the positive electrode active material when the positive electrode active material is synthesized, and reacts with the Li source in the positive electrode active material, moisture in the air and carbon dioxide gas in the process of producing the positive electrode plate. It was found that it was produced over time (see Chemical Formula 2).

(Chemical formula 2)
Li ₂ O + H ₂ O → 2LiOH
2LiOH + CO ₂ → Li ₂ CO ₃ + H ₂ O
The present invention solves such a problem, and provides a non-aqueous electrolyte secondary battery that suppresses the generation of carbon dioxide gas when stored at high temperature for a long time or when charging and discharging cycles are repeated at high temperature. To do.

  In order to solve the above-described problems, a non-aqueous electrolyte secondary battery of the present invention includes an electrode plate group formed by laminating or winding a strip-like positive electrode plate and a negative electrode plate with a separator interposed therebetween, and a non-aqueous electrolyte solution. The nonaqueous electrolyte secondary battery is characterized in that a fluorine-containing resin layer that suppresses the generation of carbon dioxide from the positive electrode plate is provided on the surface of the positive electrode plate facing the separator.

  Since the positive electrode plate provided with the fluorine-containing resin layer of the present invention can block contact between the positive electrode active material and moisture or carbon dioxide in the air, the positive electrode active material and moisture or carbon dioxide in the air Lithium carbonate produced by the reaction can be suppressed. In addition, it is known that when the separator component (polymer material such as polyethylene or polypropylene) is oxidized (deteriorated) by the positive electrode active material, the high-temperature storage characteristics and charge / discharge cycle characteristics deteriorate. Since the active material and the separator are not in direct contact, it is possible to suppress the separator from being oxidized by the positive electrode active material. Therefore, by using the positive electrode plate of the present invention, it is possible to suppress the generation of carbon dioxide gas when stored for a long time at a high temperature or when a charge / discharge cycle is repeated at a high temperature.

  According to the present invention, the provision of the fluorine-containing resin layer on the surface of the positive electrode plate can block the contact between the positive electrode active material and moisture in the air or carbon dioxide gas. And lithium carbonate produced by the reaction with carbon dioxide can be suppressed. By suppressing the production of this lithium carbonate, the problem that lithium carbonate is electrochemically oxidized and decomposed to generate carbon dioxide as shown in (Chemical Formula 1) can be solved.

  Further, if the electrode plate group is formed using the positive electrode plate provided with such a fluorine-containing resin layer, the separator and the positive electrode active material are not in direct contact with each other, so that the separator is prevented from being oxidized by the positive electrode active material. be able to.

  Based on the above, non-aqueous electrolytes with excellent high-temperature storage characteristics and high-temperature charge-discharge cycle characteristics that suppress the generation of carbon dioxide gas when stored for a long time at high temperatures or when repeated charge-discharge cycles are performed at high temperatures. A secondary battery can be provided.

  In the present invention, a non-aqueous electrolyte secondary battery comprising a group of electrode plates formed by laminating or winding a strip-like positive electrode plate and a negative electrode plate with a separator interposed therebetween, and a non-aqueous electrolyte solution, A fluorine-containing resin layer that suppresses the generation of carbon dioxide from the positive electrode plate is provided on the surface of the opposing positive electrode plate.

  According to this configuration, by providing the fluorine-containing resin layer on the surface of the positive electrode plate, the contact between the Li source in the positive electrode active material and the moisture or carbon dioxide in the air in the process of producing the positive electrode plate, Since generation of lithium carbonate can be suppressed, generation of carbon dioxide gas due to oxidative decomposition of lithium carbonate can be suppressed. Further, if the electrode plate group is configured using the positive electrode plate provided with the fluorine-containing resin layer, the positive electrode active material and the separator are not in direct contact with each other, so that the separator is prevented from being oxidized by the positive electrode active material. . Based on the above, non-aqueous electrolytes with excellent high-temperature storage characteristics and high-temperature charge-discharge cycle characteristics that suppress the generation of carbon dioxide gas when stored for a long time at high temperatures or when repeated charge-discharge cycles are performed at high temperatures. A secondary battery can be provided.

  In addition, the thickness of the layer containing the fluororesin is preferably 0.1 μm to 1.0 μm.

  If the thickness of the fluorine-containing resin layer is 0.1 μm or more, cracks or the like may occur in the fluorine-containing resin layer provided on the surface of the positive electrode plate even if the belt-like positive electrode plate is laminated or wound when forming the electrode plate group. It does not occur. In addition, when the thickness of the fluorine-containing resin layer is larger than 1.0 μm, the resistance of the electrode plate group is increased and the discharge characteristics are deteriorated. It can be said.

Further, as a positive electrode active material of the positive electrode plate, the general formula Li _x Ni _y M _1-y O ₂ (x: 0.95 ≦ x ≦ 1.10, M is Co, Mn, Cr, Fe, Mg, and Al) It is good also as a lithium complex oxide represented by y: 0 <= y <= 1.0) including at least 1 type chosen from these.

  The material of the fluorine-containing resin is at least selected from PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), and FEP (tetrafluoroethylene / hexafluoropropylene copolymer). One type is preferable, and the shape of the particles is preferably a microbead shape having a size of about 0.01 μm to 0.5 μm.

  In addition, the resin layer covering the surface of the positive electrode plate was found to have the same effect with a polymer resin other than the fluorine-containing resin, but the fluorine-containing resin was used in terms of voltage resistance, chemical resistance, and water repellency. Most preferred.

  The cylindrical lithium secondary battery will be described in detail below as the nonaqueous electrolyte secondary battery of the present invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a schematic longitudinal sectional view of a cylindrical lithium secondary battery in an embodiment of the present invention.

  In FIG. 1, the positive electrode plate 5 and the negative electrode plate 6 are wound as a separator 7 in a spiral shape through a porous film made of polypropylene resin, and the electrode plate group 4 is configured. The electrode plate group 4 was inserted into a battery case 1 made of a stainless steel plate having a diameter of 13.8 mm and a height of 50 mm. The positive electrode lead 5 a drawn from the positive electrode plate 5 was welded to the lower part of the sealing plate 2, and the negative electrode lead 6 a drawn from the negative electrode plate 6 was welded to the bottom of the battery case 1. Insulating rings 8 were arranged above and below the electrode plate group 4, respectively. After injecting the non-aqueous electrolyte into the battery case 1, the sealing plate 2 is disposed in the opening of the battery case 1 through the insulating packing 3, and the opening of the battery case 1 is caulked inward and sealed. .

  Hereinafter, the positive electrode plate 5, the negative electrode plate 6, and the non-aqueous electrolyte will be described in detail.

The positive electrode plate 5 includes 100 parts by weight of a powder of lithium cobalt oxide (LiCoO ₂ ) as a positive electrode active material, 5 parts by weight of acetylene black as a conductive material, and 5 parts by weight of polyvinylidene fluoride (PVDF) as a binder. Is added to an appropriate amount of N-methylpyrrolidone (NMP) organic solvent to prepare a paste-like positive electrode mixture, and this positive electrode mixture is applied to the surface of an aluminum foil having a thickness of 0.010 mm and dried. Made. Furthermore, the positive electrode plate 5 was coated on both surfaces of the positive electrode plate 5 using a solution in which polytetrafluoroethylene (PTFE) was dispersed as a fluorine-containing resin, and dried. This was rolled to a thickness of 0.17 mm by a roll press machine, cut into a size of 35 mm in width and 250 mm in length, and a positive electrode plate 5 provided with a fluorine-containing resin layer was obtained.

  The negative electrode plate 6 is obtained by mixing 10 parts by weight of a styrene-based binder as a binder with 100 parts by weight of carbon powder obtained by heat-treating coke, which is a negative electrode active material, and mixing this with an aqueous solution of carboxymethyl cellulose (CMC). A paste-like negative electrode mixture was prepared by suspending in an aqueous solution, and this negative electrode mixture was applied to the surface of a copper foil having a thickness of 0.015 mm and dried. After drying, it was rolled to a thickness of 0.2 mm by a roll press machine, cut into a size of 37 mm width and 280 mm length, and used as negative electrode plate 6.

The nonaqueous electrolytic solution was obtained by dissolving 1.0 mol / L of lithium hexafluorophosphate (LiPF ₆ ) as an electrolyte salt in an equal volume mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC). A predetermined amount of this non-aqueous electrolyte was injected into the battery case 1 in which the electrode plate group 4 was housed.
Thus, a so-called 14500 size cylindrical lithium secondary battery having a rated capacity of 500 mAh, a size of 14 mm in diameter, and a height of 50 mm was produced.

(Example 1)
As the fluorine-containing resin layer, a PTFE resin layer having a thickness of 0.1 μm was provided on both surfaces of the positive electrode plate 5. A cylindrical lithium secondary battery produced using this positive electrode plate 5 was taken as Example 1.

(Example 2)
A PTFE resin layer having a thickness of 1.0 μm was provided on both surfaces of the positive electrode plate 5 as a fluorine-containing resin layer. A cylindrical lithium secondary battery produced using this positive electrode plate 5 in the same manner as in Example 1 was designated as Example 2.

(Example 3)
As a fluorine-containing resin layer, a PTFE resin layer having a thickness of 0.05 μm was provided on both surfaces of the positive electrode plate 5. A cylindrical lithium secondary battery produced in the same manner as in Example 1 using this positive electrode plate 5 was designated as Example 3.

Example 4
As a fluorine-containing resin layer, a PTFE resin layer having a thickness of 1.2 μm was provided on both surfaces of the positive electrode plate 5. A cylindrical lithium secondary battery produced in the same manner as in Example 1 using this positive electrode plate 5 was designated as Example 4.

(Example 5)
An FEP resin layer having a thickness of 0.1 μm was provided on both surfaces of the positive electrode plate 5 as a fluorine-containing resin layer. A cylindrical lithium secondary battery produced in the same manner as in Example 1 using this positive electrode plate 5 was designated as Example 5.

(Example 6)
As the fluorine-containing resin layer, an FEP resin layer having a thickness of 1.0 μm was provided on both surfaces of the positive electrode plate 5. A cylindrical lithium secondary battery produced in the same manner as in Example 1 using this positive electrode plate 5 was designated as Example 6.

(Example 7)
As the fluorine-containing resin layer, FEP resin layers having a thickness of 0.05 μm were provided on both surfaces of the positive electrode plate 5. A cylindrical lithium secondary battery produced in the same manner as in Example 1 using this positive electrode plate 5 was designated as Example 7.

(Example 8)
As the fluorine-containing resin layer, a 1.2 μm thick FEP resin layer was provided on both surfaces of the positive electrode plate 5. A cylindrical lithium secondary battery produced in the same manner as in Example 1 using this positive electrode plate 5 was designated as Example 8.

(Comparative Example 1)
A cylindrical lithium secondary battery produced in the same manner as in Example 1 except that the fluorine-containing resin layer was not provided on the positive electrode plate 5 was used as Comparative Example 1.

Example 9
LiNi _1/3 Co _1/3 Mn _1/3 O ₂ was used as the positive electrode active material, and a PTFE resin layer having a thickness of 0.1 μm was provided on both surfaces of the positive electrode plate 5 as a fluorine-containing resin layer. A cylindrical lithium secondary battery produced in the same manner as in Example 1 using this positive electrode plate 5 was designated as Example 9.

(Example 10)
LiNi _1/3 Co _1/3 Mn _1/3 O ₂ was used as the positive electrode active material, and a PTFE resin layer having a thickness of 1.0 μm was provided on both surfaces of the positive electrode plate 5 as a fluorine-containing resin layer. A cylindrical lithium secondary battery produced in the same manner as in Example 1 using this positive electrode plate 5 was designated as Example 10.

(Example 11)
LiNi _1/3 Co _1/3 Mn _1/3 O ₂ was used as the positive electrode active material, and a PTFE resin layer having a thickness of 0.05 μm was provided on both surfaces of the positive electrode plate 5 as a fluorine-containing resin layer. A cylindrical lithium secondary battery produced in the same manner as in Example 1 using this positive electrode plate 5 was designated as Example 11.

(Example 12)
LiNi _1/3 Co _1/3 Mn _1/3 O ₂ was used as the positive electrode active material, and a PTFE resin layer having a thickness of 1.2 μm was provided on both surfaces of the positive electrode plate 5 as a fluorine-containing resin layer. A cylindrical lithium secondary battery produced in the same manner as in Example 1 using this positive electrode plate 5 was designated as Example 12.

(Example 13)
LiNi _1/3 Co _1/3 Mn _1/3 O ₂ was used as the positive electrode active material, and a 0.1 μm thick FEP resin layer was provided on both surfaces of the positive electrode plate 5 as a fluorine-containing resin layer. A cylindrical lithium secondary battery produced in the same manner as in Example 1 using this positive electrode plate 5 was designated as Example 13.

(Example 14)
LiNi _1/3 Co _1/3 Mn _1/3 O ₂ was used as the positive electrode active material, and FEP resin layers having a thickness of 1.0 μm were provided on both surfaces of the positive electrode plate 5 as fluorine-containing resin layers. A cylindrical lithium secondary battery produced in the same manner as in Example 1 using this positive electrode plate 5 was designated as Example 14.

(Example 15)
LiNi _1/3 Co _1/3 Mn _1/3 O ₂ was used as a positive electrode active material, and FEP resin layers having a thickness of 0.05 μm were provided on both surfaces of the positive electrode plate 5 as fluorine-containing resin layers. A cylindrical lithium secondary battery produced in the same manner as in Example 1 using this positive electrode plate 5 was designated as Example 15.

(Example 16)
LiNi _1/3 Co _1/3 Mn _1/3 O ₂ was used as the positive electrode active material, and a 1.2 μm thick FEP resin layer was provided on both surfaces of the positive electrode plate 5 as a fluorine-containing resin layer. A cylindrical lithium secondary battery produced in the same manner as in Example 1 using this positive electrode plate 5 was designated as Example 16.

(Comparative Example 2)
Cylindrical lithium secondary produced in the same manner as in Example 1 except that LiNi _1/3 Co _1/3 Mn _1/3 O ₂ was used as the positive electrode active material and the fluorine-containing resin layer was not provided on the positive electrode plate 5. The battery was referred to as Comparative Example 2.

  The cylindrical lithium secondary batteries of Examples 1 to 16 and Comparative Examples 1 and 2 were evaluated as follows.

<Measurement of gas generation during high temperature storage>
Each cylindrical lithium secondary battery is charged to a voltage of 4.20 V at a constant current of 500 mA at an environmental temperature of 20 ° C. After reaching the voltage of 4.20 V, the constant voltage 4 is set so that the total charging time is 2 hours. The battery was charged at 20V. Thereafter, the charged cylindrical lithium secondary battery at an environmental temperature of 60 ° C. was stored for 3 days. After cooling, a hole was made in the bottom of the battery case, and the amount of gas generated was measured.

<Charge / discharge cycle characteristics>
Each cylindrical lithium secondary battery was charged and discharged under the following conditions at an environmental temperature of 45 ° C.

  The charging conditions were a constant current of 500 mA and a battery voltage of 4.2 V. After the battery voltage reached 4.2 V, the battery was charged at a constant voltage of 4.2 V so that the total charging time was 2 hours.

  The discharge was performed at a constant current of 1000 mA until the battery discharge starting voltage reached 3.0V.

  These charge and discharge were made into 1 cycle, and 100 cycles were repeated. From the discharge capacity at the first cycle and the discharge capacity at the 100th cycle, the discharge capacity retention ratio was calculated by the following formula.

Discharge capacity retention rate (%) = 100th cycle discharge capacity (mAh) / 1st cycle discharge capacity (mAh) × 100
The measurement of the amount of gas generated during high temperature storage and the results of charge / discharge cycle characteristics are shown in Table 1.

From the results of (Table 1), it was found that Example 1 and Example 2 significantly reduced the amount of gas generated when stored at 60 ° C. compared to Comparative Example 1. This is because Example 1 and Example 2 reacted with the Li source in the positive electrode active material and moisture or carbon dioxide in the air by the action of the PTFE resin layer provided with the surface of the positive electrode plate as a fluorine-containing resin layer. It is considered that the amount of gas generated during storage at 60 ° C. could be reduced because the generated lithium carbonate could be suppressed.

  In Example 3, the amount of gas generated during storage at 60 ° C. is larger than that in Examples 1 and 2, but this is because the PTFE resin layer provided on the surface of the positive electrode plate is thin, so that the positive electrode active material and air This is thought to be because the reaction with moisture and carbon dioxide in the interior could not be sufficiently suppressed. In particular, it is considered that the positive electrode plate at the beginning of rolling of the electrode plate group formed by winding has a small radius of curvature, so that a thin PTFE resin layer provided on the surface of the positive electrode plate cracked and reacted with carbon dioxide.

  Example 4 was found to have lower charge / discharge cycle characteristics than Examples 1-3. Moreover, when the battery resistance of Example 4 was measured by the alternating current measurement method (1 kHz), it was 4 to 6 mΩ higher than that of Examples 1 to 3. This is presumably because the PTFE resin layer provided on the surface of the positive electrode plate is thick, so that the resistance of the positive electrode plate is increased, leading to deterioration of charge / discharge cycle characteristics.

  In Comparative Example 1, the charge / discharge cycle characteristics are greatly deteriorated as compared with Examples 1 to 3 and Example 4. This is because the positive electrode active material is in direct contact with the separator, so that polypropylene which is a component of the separator is used. This is thought to be due to oxidative degradation.

  Moreover, according to Examples 5-8, even if it provided the FEP resin layer as a fluorine-containing resin layer, it turned out that the effect similar to a PTFE resin layer is acquired.

Further, it was found that the same effect as when using the even LiCoO ₂ using LiNi _1/3 Co _1/3 Mn _1/3 O ₂ in the positive electrode active material according to Examples 9 to 16 is obtained.

  From the above results, a non-aqueous electrolyte secondary battery comprising a group of electrode plates formed by laminating or winding a strip-like positive electrode plate and a negative electrode plate via a separator, and a non-aqueous electrolyte solution, facing the separator By providing a fluorine-containing resin layer on the surface of the positive electrode plate, the generation of carbon dioxide gas is suppressed when stored for a long time at high temperatures or when charge / discharge cycles are repeated at high temperatures. It was found that a non-aqueous electrolyte secondary battery excellent in charge / discharge cycle characteristics was obtained.

  In this example, the results of evaluation using a cylindrical lithium secondary battery were described. However, the same effect can be obtained even if the battery shape is different, such as a square shape, a coin shape, a button shape, and a laminate shape. .

  In this embodiment, the cylindrical lithium secondary battery having a rated capacity of 500 mAh has been described. However, a nonaqueous electrolyte secondary battery having a capacity other than 500 mAh may be used.

In this example, LiCoO ₂ and LiNi _1/3 Co _1/3 Mn _1/3 O ₂ have been described as the positive electrode active material. However, the present invention is not limited to these positive electrode active materials.

  In this example, coke was used as a negative electrode material that reversibly reacts with lithium. However, carbon materials such as graphite and amorphous materials or mixtures thereof, metal oxides such as silicide, or mixtures thereof were used. May be used.

  In this example, evaluation was performed using a porous film made of polypropylene resin as a separator, but an organic microporous film such as polyethylene or an inorganic microporous film may be used.

Further, in this example, a 1: 1 (volume ratio) mixed solvent of EC and DEC was used as the non-aqueous electrolyte, but as other non-aqueous solvents, for example, cyclic esters such as propylene carbonate (PC), tetrahydrofuran, etc. Nonaqueous solvents such as cyclic ethers such as (THF), chain ethers such as dimethoxyethane (DME), chain esters such as methyl propionate (MP), and these multicomponent mixed solvents may be used.

In this example, LiPF ₆ was used as the electrolyte salt, but other lithium salts may be lithium perchlorate (LiClO ₄ ), lithium tetrafluoroborate (LiBF ₄ ), or the like. Moreover, although the density | concentration of electrolyte salt was 1.0 mol / L, you may use a salt density | concentration of 0.5-2.0 mol / L.

  Moreover, although the lithium secondary battery has been described as the nonaqueous electrolyte secondary battery, the same effect can be obtained in a nonaqueous electrolyte secondary battery such as a magnesium secondary battery other than the lithium secondary battery. is there.

  The non-aqueous electrolyte secondary battery according to the present invention is useful as a power source for portable electric equipment having excellent high-temperature storage characteristics and charge / discharge cycle characteristics at high temperatures, and is used as a driving power source for automobiles and residential equipment such as elevators. It is also useful as a driving power source.

Schematic longitudinal sectional view of a cylindrical lithium secondary battery in an embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery case 2 Sealing plate 3 Insulation packing 4 Electrode plate group 5 Positive electrode plate 5a Positive electrode lead 6 Negative electrode plate 6a Negative electrode lead 7 Separator 8 Insulation ring

Claims (3)

  A non-aqueous electrolyte secondary battery comprising a non-aqueous electrolyte solution comprising a group of electrode plates formed by laminating or winding a strip-shaped positive electrode plate and a negative electrode plate with a separator interposed therebetween, and a positive electrode plate facing the separator A non-aqueous electrolyte secondary battery comprising a fluorine-containing resin layer for suppressing generation of carbon dioxide gas from a positive electrode plate on a surface.   The nonaqueous electrolyte secondary battery according to claim 1, wherein the thickness of the fluorine-containing resin layer is 0.1 μm to 1.0 μm. As a positive electrode active material of the positive electrode plate, a general formula Li _x Ni _y M _1-y O ₂ (x: 0.95 ≦ x ≦ 1.10, M is selected from Co, Mn, Cr, Fe, Mg, and Al) 2. The non-aqueous electrolyte secondary battery according to claim 1, wherein a lithium composite oxide represented by y: 0 ≦ y ≦ 1.0) is included.

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