JPWO2012127561A1 - Non-aqueous electrolyte battery - Google Patents

Abstract

The non-aqueous electrolyte battery of the present invention includes a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte. The positive electrode and the negative electrode are formed on the current collector and the current collector, respectively. The current collector includes a resin film and a conductive layer provided on at least one side of the resin film, and the active material-containing layer is formed on the conductive layer, and The Young's modulus Ya in the arbitrary direction of the electric body and the Young's modulus Yb in the direction orthogonal to the arbitrary direction are 4 GPa or more and 17 GPa or less, respectively, and the absolute value of the difference between the Young's modulus Ya and the Young's modulus Yb | Ya−Yb | Is 5.0 or less.

Description

  The present invention relates to a non-aqueous electrolyte battery such as a lithium ion secondary battery.

  A non-aqueous electrolyte battery represented by a lithium ion secondary battery is widely used as a power source for portable devices such as a mobile phone and a notebook personal computer because of its high energy density. As the performance of portable devices increases, the capacity of lithium ion secondary batteries tends to increase further, and it is necessary to further improve the energy density.

  The nonaqueous electrolyte battery includes electrodes (positive electrode and negative electrode) in which an active material-containing layer is provided on one side or both sides of a current collector. The current collector is usually formed from a metal foil. However, in order to reduce the weight of the current collector, which is a component of the nonaqueous electrolyte battery, to the limit and improve the energy density of the nonaqueous electrolyte battery, a resin is used. A current collector in which a conductive thin film is formed on the surface of a film has been proposed (see, for example, Patent Document 1 and Patent Document 2).

JP-A-9-213338 JP-A-9-283149

  However, when a resin film is used as the base material of the current collector, it is inevitable that the resin film expands as the temperature rises due to charging and discharging of the battery. When the resin film, which is the base material of the current collector, expands during use of the battery, the entire current collector also expands, and the active material-containing layer provided on the current collector is not bonded to the current collector. This may be sufficient, and the charge / discharge characteristics of the battery may be reduced.

  The present invention solves the above problems and provides a nonaqueous electrolyte battery that is lightweight and has high charge / discharge characteristics.

  The non-aqueous electrolyte battery of the present invention is a non-aqueous electrolyte battery including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte, wherein the positive electrode and the negative electrode are a current collector and a current collector, respectively. An active material-containing layer formed thereon, the current collector includes a resin film and a conductive layer provided on at least one surface of the resin film, and the active material-containing layer is formed of the conductive layer. The Young's modulus Ya in the arbitrary direction of the current collector and the Young's modulus Yb in the direction orthogonal to the arbitrary direction are 4 GPa or more and 17 GPa or less, respectively, and the difference between the Young's modulus Ya and the Young's modulus Yb The absolute value of | Ya−Yb | is 5.0 or less.

  According to the present invention, a non-aqueous electrolyte battery that is lightweight and has high charge / discharge characteristics can be provided.

FIG. 1 is a schematic cross-sectional view showing an example of an electrode used in the nonaqueous electrolyte battery of the present invention. FIG. 2 is a schematic cross-sectional view showing another example of an electrode used in the nonaqueous electrolyte battery of the present invention. 3A is a perspective view for explaining an electrode body used in the present invention, FIG. 3B is a perspective view showing a state in which the electrode body is housed in an exterior material, and FIG. 3C is a view in which the electrode body is housed in an exterior material. FIG.

  The nonaqueous electrolyte battery of the present invention includes a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte. The positive electrode and the negative electrode each include a current collector and an active material-containing layer formed on the current collector, and the current collector is disposed on at least one surface of the resin film and the resin film. The active material-containing layer is formed on the conductive layer. Furthermore, the Young's modulus Ya in the arbitrary direction of the current collector and the Young's modulus Yb in the direction orthogonal to the arbitrary direction are 4 GPa or more and 17 GPa or less, respectively, and the absolute value of the difference between the Young's modulus Ya and the Young's modulus Yb | Ya-Yb | is set to 5.0 or less.

  Usually, after a resin film is formed by extrusion molding, strength is imparted by uniaxial stretching or biaxial stretching. The inventors pay attention to the Young's modulus, which is one of the measures of the strength of the resin film, examine the relationship between the Young's modulus of the resin film and the temperature expansion coefficient of the resin film, and specify the Young's modulus of the resin film. By setting the range, a resin film having a small temperature expansion coefficient was realized. By using the resin film as a base material for the current collector, a non-aqueous electrolyte battery that is light in weight and high in charge / discharge characteristics is realized by realizing a current collector that is small in expansion even when the temperature changes.

  In the present invention, the Young's modulus Ya in the arbitrary direction of the current collector and the Young's modulus Yb in the direction orthogonal to the arbitrary direction are 4 GPa or more and 17 GPa or less, more preferably 7 GPa or more and 17 GPa or less. Thereby, the expansion | swelling by the temperature rise of a collector can be suppressed. When at least one of the Young's moduli Ya and Yb is less than 4 GPa, the current collector expands due to temperature rise, and the charge / discharge characteristics of the battery deteriorate. The higher the Young's modulus Ya, Yb is, the more the current collector can be prevented from expanding due to the temperature rise, but the upper limit of the Young's modulus of the industrial resin that is the material of the resin film used as the base material of the current collector Is about 17 GPa, the upper limit of the Young's modulus of the current collector is about 17 GPa as long as an industrial resin is used.

  In the present invention, the absolute value | Ya−Yb | of the difference between the Young's modulus Ya and the Young's modulus Yb is set to 5.0 or less. Thereby, since the expansion | swelling by the temperature rise of a collector can be suppressed equally, the charging / discharging characteristic of a battery can be maintained reliably.

  In the present invention, the Young's modulus of a current collector including a resin film and a conductive layer is measured based on the following measurement method. The measurement environment is a temperature of 23 ° C. ± 5 ° C. and a relative humidity of 50% ± 10%. Using a tensile tester as the measuring device, set the measurement sample with the load cell interval of the tensile tester set to 10 cm, pull the sample at a pulling speed of 10 mm / min, read the weight at that time, and read the sample at a load of 1.5 N The Young's modulus is obtained by dividing the difference between the amount of elongation and the amount of elongation of the sample at 0.5 N by the thickness of the sample.

  The thickness of the resin film is preferably 3 μm or more and 20 μm or less, and more preferably 4.5 μm or more and 10 μm or less. If it is less than 3 μm, it is too thin to make it difficult to process the film, and it tends to be difficult to ensure the strength of the film. On the other hand, when the thickness exceeds 20 μm, the volume occupied by the film increases, and in the case of a battery having the same volume, the volume of the active material-containing layer decreases by the volume increase of the film.

  The conductive layer preferably has a thickness of 100 nm to 3 μm. If it is less than 100 nm, the electrical resistance as a current collector increases, and the current collection effect tends to decrease. If the thickness exceeds 3 μm, the stress of the conductive layer increases, and the current collector may be warped and undulated, making it difficult to use it as a current collector.

  Hereinafter, embodiments of electrodes used in the present invention will be described with reference to the drawings. However, in FIGS. 1-2, the same code | symbol is attached | subjected to the same part and the overlapping description is abbreviate | omitted.

  FIG. 1 is a schematic cross-sectional view showing an example of an electrode used in the nonaqueous electrolyte battery of the present invention. In FIG. 1, an electrode (positive electrode or negative electrode) 10 includes a current collector 11 and an active material containing layer 12 formed on both surfaces of the current collector 11. The current collector 11 includes a resin film 11a and conductive layers 11b provided on both surfaces of the resin film 11a, and the active material-containing layer 12 and the conductive layer 11b are electrically joined.

  As the resin constituting the resin film 11a, for example, one resin selected from the group consisting of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), aramid, polyethylene, polypropylene, polystyrene, polyamide and polyimide is used. Can do. Moreover, as the resin film 11a, it is good also as a conductive resin film by mixing a conductive filler etc. with the said resin. As described above, the thickness of the resin film 11a is set to 3 μm or more and 20 μm or less.

  As a material constituting the conductive layer 11b, for example, a metal such as aluminum or copper, or a carbon material such as graphite can be used. Although the method of forming the conductive layer 11b on the resin film 11a is not limited, for example, a vacuum deposition method, a sputtering method, a plating method, or the like can be used. As described above, the thickness of the conductive layer 11b is set to 100 nm or more and 3 μm or less.

  The Young's modulus of the current collector 11 can be substantially controlled by adjusting the Young's modulus of the resin film 11a. Moreover, the Young's modulus of the resin film 11a can be controlled by adjusting the draw ratio, for example. Generally, increasing the draw ratio increases the Young's modulus of the resin film.

  The active material-containing layer 12 is formed of an active material, a conductive aid, a binder, and the like. The thickness of the active material-containing layer 12 is not particularly limited, but if it is too thin, the volume of the active material-containing layer 12 is relatively reduced in the entire battery, and is preferably 150 μm or more per side.

  FIG. 2 is a schematic cross-sectional view showing another example of an electrode used in the nonaqueous electrolyte battery of the present invention. 2, the electrode 20 is the electrode 10 shown in FIG. 1 except that the conductive layer 11b is provided only on one surface of the resin film 11a and the active material-containing layer 12 is formed only on the conductive layer 11b. It is the same composition as.

  Next, an embodiment of the nonaqueous electrolyte battery of the present invention will be described by taking a flat lithium ion secondary battery as an example. 3A is a perspective view for explaining an electrode body used in the present embodiment, FIG. 3B is a perspective view showing a state in which the electrode body is housed in an exterior material, and FIG. 3C is an electrode body as an exterior material. It is a perspective view of the stored state.

  3A, the electrode body 30 is produced by laminating a rectangular positive electrode 31 and a rectangular negative electrode 32 with a rectangular separator 33 interposed therebetween. A positive electrode lead terminal 31 a is provided at one end of the positive electrode 31, and a negative electrode lead terminal 32 a is provided at one end of the negative electrode 32.

  In FIG. 3B, the rectangular-shaped exterior material 34 which has flexibility is valley-folded, and is comprised from the 1st exterior surface 34a and the 2nd exterior surface 34b. An electrode housing portion 35 is formed on the first exterior surface 34a by deep drawing. Also, each positive electrode lead terminal 31a (FIG. 3A) and each negative electrode lead terminal 32a (FIG. 3A) are overlapped and welded to form a positive electrode lead terminal portion 36a and a negative electrode lead terminal portion 36b, respectively.

  In FIG. 3C, the electrode body 30 is housed in an electrode housing portion 35 formed by a first exterior surface 34a and a second exterior surface 34b that are valley-folded together with the nonaqueous electrolyte. Further, among the outer periphery of the exterior member 34, three sides other than the one side that is valley-folded are joined with a predetermined width to form the sealing portions 37a, 37b, and 37c. The positive electrode lead terminal portion 36 a and the negative electrode lead terminal portion 36 b are drawn out from the sealing portion 37 c facing one side of the exterior material 34 that is folded down.

  The positive electrode 31 is a mixture of a positive electrode active material, a positive electrode conductive additive, a positive electrode binder, and the like, and a positive electrode mixture paste obtained by sufficiently kneading the mixture with a solvent. After coating and drying, the positive electrode mixture layer (positive electrode active material-containing layer) can be formed by controlling it to a predetermined thickness and a predetermined electrode density.

As the positive electrode active material, for example, a lithium manganese composite oxide having a spinel structure having a composition of the general formula LiMn ₂ O ₄ (a part of the constituent elements is replaced by an element such as Ge, Zr, Mg, Ni, Al, Co) A lithium cobalt composite oxide having a composition of the general formula LiCoO _{2 (} a composite in which some of the constituent elements are substituted with elements such as Ni, Al, Mg, Zr, Ti, and B) And a lithium nickel composite oxide having a composition of the general formula LiNiO ₂ (a composite oxide in which a part of the constituent elements is substituted with an element such as Co, Al, Mg, Zr, Ti, B, etc.) . including) composite oxide of a layered structure such as, lithium-containing composite oxide of olivine structure having a composition of general formula LiMPO ₄ (where, M is at least one selected from Ni, Co and Fe). There are exemplified.

  The positive electrode conductive auxiliary agent may be added as necessary for the purpose of improving the electric conductivity of the positive electrode mixture layer. Examples of the conductive powder used as the conductive auxiliary agent include carbon black, ketjen black, and acetylene black. Carbon powder such as fibrous carbon and graphite, and metal powder such as nickel powder can be used.

  Examples of the positive electrode binder include, but are not limited to, polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE).

  As the positive electrode current collector, one having the same structure as the current collector 10 shown in FIG. 1 and using, for example, a PET film as the resin film 11a and an aluminum layer as the conductive layer 11b is used. .

  As the solvent, for example, N-methyl-2-pyrrolidone or the like can be used.

  The negative electrode 32 is obtained by using a negative electrode mixture paste obtained by sufficiently kneading a mixture containing a negative electrode active material, a negative electrode conductive additive, a negative electrode binder, and the like, with both sides of the negative electrode current collector according to the present invention. After coating and drying, the negative electrode mixture layer (negative electrode active material-containing layer) can be formed by controlling it to a predetermined thickness and a predetermined electrode density.

  Examples of the negative electrode active material include carbon materials such as natural graphite or artificial graphite such as massive graphite, flaky graphite, and earthy graphite, but are not limited thereto as long as lithium ions can be occluded / released. .

  As the negative electrode current collector, one having the same structure as the current collector 10 shown in FIG. 1 and using a PET film as the resin film 11a and a copper layer as the conductive layer 11b is used, for example. .

  About the said conductive additive for negative electrodes, the binder for negative electrodes, and a solvent, the thing similar to what was used for the positive electrode can be used.

  As the separator 33, it is preferable to use a separator having a two-layer structure including a heat-resistant porous substrate having a thickness of 10 to 50 μm and a microporous film made of a thermoplastic resin having a thickness of 10 to 30 μm.

  The heat-resistant porous substrate may be formed of, for example, a fibrous material having a heat-resistant temperature of 150 ° C. or higher, and the fibrous material may be cellulose or a modified product thereof, polyolefin, polyester, polyacrylonitrile, aramid, polyamide. It can be formed of at least one material selected from the group consisting of imides and polyimides. More specifically, sheet-like materials such as woven fabrics and nonwoven fabrics (including paper) made of the above materials can be used as heat-resistant porous materials. It can be used as a quality substrate.

  The microporous film made of the thermoplastic resin has a melting point of 80 to 140 ° C., for example, in order to provide the separator with a shutdown function that closes the micropores at a certain temperature (100 to 140 ° C.) and increases the resistance. A microporous film made of a certain thermoplastic resin can be used. More specifically, a microporous sheet made of an olefin polymer such as polypropylene and polyethylene having resistance to organic solvents and hydrophobicity can be used.

  In order to further improve the heat resistance of the separator 33, an inorganic filler may be included in the heat-resistant porous substrate, and an inorganic filler layer having a thickness of about 3 to 10 μm is provided on the microporous film. May be. As the inorganic filler, for example, particles of at least one inorganic oxide selected from the group consisting of alumina, silica, titanium oxide, zirconium oxide, and boehmite can be used.

  Although the thickness of the separator 33 is not specifically limited, Usually, it is 25-90 micrometers.

  As the exterior material 34, a laminate film in which a metal layer such as aluminum and a thermoplastic resin layer are laminated can be used. For example, a laminate film in which a thermoplastic resin layer having a thickness of 20 to 50 μm is provided on the outer side of an aluminum layer having a thickness of 20 to 100 μm and an adhesive layer having a thickness of 20 to 100 μm is provided on the inner side thereof can be used. Thereby, sealing part 37a, 37b, 37c can be joined reliably by heat welding.

  Although the thickness of the exterior material 34 is not specifically limited, Usually, it is 60-250 micrometers.

  As the non-aqueous electrolyte, a solution (non-aqueous electrolytic solution) in which a lithium salt is dissolved in an organic solvent is used.

Examples of the organic solvent include vinylene carbonate (VC), propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (MEC). , Γ-butyrolactone or other organic solvents can be used alone or in combination. Furthermore, as the lithium salt, for _example, it can be used at least one lithium salt selected from _{LiClO 4, LiPF 6, LiBF 4} , LiAsF 6, LiSbF 6, LiCF 3 SO 3 and the like. The concentration of Li ions in the nonaqueous electrolytic solution may be 0.5 to 1.5 mol / L.

  In the embodiment of the non-aqueous electrolyte battery, an example using a laminated electrode body in which rectangular electrodes are stacked via a separator is shown. However, a wound electrode body in which a long electrode is wound via a separator. May be used.

  Next, this invention is demonstrated based on an Example.

Example 1
<Preparation of current collector>
The current collector used for the positive electrode and the negative electrode was produced as follows.

A PEN film “Teonex” (trade name) manufactured by Teijin Ltd. having a thickness of 6.1 μm was used as the resin film. First, the resin film is set on the unwinding part of the vacuum evaporation apparatus, and after reducing the pressure to 1.5 × 10 ⁻³ Pa, the resin film is conveyed at a conveyance speed of 60 m / min and a conveyance tension through a cooling drum at −20 ° C. The vehicle was run at 100 N / m. At this time, aluminum having a purity of 99.99% by weight was evaporated by heating with an electron beam (output 5.1 kW), aluminum was deposited on the surface of the resin film to form an aluminum thin film, and the resin film was wound up. The thickness of the aluminum thin film was about 150 nm. Next, after forming the aluminum thin film in the same manner as described above except that the transport tension was set to 80 N / min on the surface opposite to the surface on which the aluminum thin film was formed of the resin film wound up earlier, As a result, a positive electrode current collector in which an aluminum thin film was formed on both surfaces of the resin film was produced.

  Further, in place of the deposition of aluminum, copper having a purity of 99.99% by weight was deposited on a resin film, and a copper thin film having a thickness of about 150 nm was formed on both surfaces of the resin film. A negative electrode current collector was produced in the same manner.

<Measurement of Young's modulus of current collector>
The Young's modulus of the produced current collector was measured as follows. First, a sample having a width of 12.65 mm and a length of 15 cm was cut out from the produced current collector in an arbitrary direction to be a first sample, and the cutting direction of the first sample was taken as a first direction. Next, the first test sample is set with the load cell interval of the tensile tester set to 10 cm, pulled in the length direction at a speed of 10 mm / min, the weight at that time is read, and the amount of elongation of the sample when the weight is 1.5 N The Young's modulus Ya in the first direction (arbitrary direction) was determined by dividing the difference between the sample elongation at 0.5N and the thickness of the first sample.

  However, the size of the sample used for measuring the Young's modulus of the current collector is not limited to the size of the sample.

  Next, the second sample is cut out in the same manner as the first sample except that it is cut out from the same current collector in the direction perpendicular to the cutting direction of the first sample, the cutting direction of the second sample is set as the second direction, The Young's modulus Yb in the second direction (direction perpendicular to the arbitrary direction) was determined in the same manner as in the first sample except that the second sample was used.

  The Young's modulus was measured in an atmospheric environment at a temperature of 23 ° C. ± 5 ° C. and a relative humidity of 50% ± 10%.

<Measurement of temperature change of current collector length>
As a measurement sample of the temperature change amount of the current collector length, a first sample and a second sample are prepared in the same manner as in the measurement of the Young's modulus of the current collector, and the first sample and The amount of temperature change in the length of the second sample was measured. First, the length of each sample in the length direction was measured at an ambient temperature of 10 ° C., and the length was defined as L1. Next, the ambient temperature was raised to 29 ° C., the length in the length direction of each sample was measured, and the length was defined as L2. Subsequently, (L2-L1) / L1 was calculated, and the temperature change amount was determined in ppm.

<Production of nonaqueous electrolyte battery>
A nonaqueous electrolyte battery was produced using the produced current collector as follows.

94 parts by mass of LiMn ₂ O ₄ as a positive electrode active material, 3 parts by mass of acetylene black as a conductive additive, and 3 parts by mass of polyvinylidene fluoride as a binder are mixed so as to be uniform using N-methyl-2-pyrrolidone as a solvent. Then, a positive electrode mixture-containing paste was prepared. The paste is applied to both sides of the positive electrode current collector, dried to form a positive electrode mixture layer, press-formed with a roller, and then cut so that the electrode application surface has a width of 40 mm and a length of 72 mm. Thus, a positive electrode was produced. Moreover, the positive electrode lead terminal was formed in the one end part of the positive electrode in which the positive mix layer was not formed.

Water as a solvent using graphite powder having a BET specific surface area of 2.2 m ² / g and an average particle diameter of 18 μm as the negative electrode active material, and carboxymethyl cellulose (CMC) and styrene-butadiene copolymer rubber (SBR) as the binder. At the same time, graphite powder, CMC, and SBR were mixed at a mass ratio of 96: 2: 2 to prepare a slurry-like negative electrode mixture-containing paste. The paste is applied to both sides of the negative electrode current collector, dried to form a negative electrode mixture layer, press-formed with a roller, and then cut so that the electrode application surface has a width of 42 mm and a length of 74 mm. Thus, a negative electrode was produced. Moreover, the negative electrode lead terminal was formed in the one end part of the negative electrode in which the negative mix layer was not formed.

  As a separator, a porous laminated film was prepared by laminating a porous film in which a boehmite particle layer having a thickness of 5 μm was formed on a microporous film made of polyethylene having a thickness of 16 μm and a nonwoven fabric made of polyethylene terephthalate having a thickness of 20 μm. The total thickness of the porous laminated film (separator) was about 20 μm, and the opening ratio was 50%.

  Next, using the 15 positive electrodes and the 16 negative electrodes, the separator is disposed between the positive electrode and the negative electrode so that the nonwoven fabric is in contact with the positive electrode, and each positive electrode and each negative electrode are laminated. Were welded to form a positive electrode lead terminal portion, each negative electrode lead terminal was welded to form a negative electrode lead terminal portion, and then inserted into an outer packaging material made of a laminate film.

A solution obtained by dissolving LiPF ₆ at a ratio of 1.2 mol / L in a solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 2 in a non-aqueous electrolyte was injected into the exterior material. After that, the opening was sealed to produce a nonaqueous electrolyte battery.

(Example 2)
Instead of the PEN film as a resin film, a current collector was prepared in the same manner as in Example 1 except that a PET film “Lumirror” (trade name) manufactured by Toray Industries, Inc. having a thickness of 6.1 μm was used. The temperature change of the Young's modulus of the current collector and the length of the current collector was measured to produce a nonaqueous electrolyte battery.

(Example 3)
Instead of the PEN film as a resin film, a current collector was prepared in the same manner as in Example 1 except that an aramid film “Mikutron” (trade name) manufactured by Toray Industries, Inc. having a thickness of 3.6 μm was used. The temperature change of the Young's modulus of the current collector and the length of the current collector was measured to produce a nonaqueous electrolyte battery.

(Comparative Example 1)
After applying a polyvinyl alcohol (PVA) aqueous solution to one side of the PET film used in Example 2, it was dried at 80 ° C. to form a PVA layer having a thickness of 1.0 μm to prepare a PET film with reduced strength. A current collector was prepared in the same manner as in Example 2 except that the PET film was used, and the temperature change in the Young's modulus of the current collector and the length of the current collector was measured. A battery was produced.

(Comparative Example 2)
The PEN film used in Example 1 was pulled in a dryer at 130 ° C. with a tension of 150 N / m in the longitudinal direction to increase the strength in the longitudinal direction, and the PEN film was used except that the PEN film was used. A current collector was prepared in the same manner as in Example 1, and the temperature change of the Young's modulus of the current collector and the length of the current collector was measured to prepare a nonaqueous electrolyte battery.

<Charge / discharge cycle test>
Next, the charge / discharge cycle test was performed as follows about the nonaqueous electrolyte battery of Examples 1-3 and Comparative Examples 1-2.

  Each battery was subjected to constant current-constant voltage charging (total charging time: 3 hours) with a constant current of 1C and a constant voltage of 4.2V, and then a constant current discharge at 1C (end-of-discharge voltage: 2.7V). The discharge capacity (mAh) was measured. With this as one cycle, charging and discharging were repeated under the above conditions until the discharge capacity of each cycle was less than 90% of the discharge capacity of the first cycle. However, the maximum number of charge / discharge cycles was 500. As a result, in the batteries of Examples 1 to 3, the discharge capacity at the 500th cycle was maintained at 90% or more with respect to the discharge capacity at the first cycle. On the other hand, in the battery of Comparative Example 1, the discharge capacity is less than 90% with respect to the discharge capacity of the first cycle at the 225th cycle, and with respect to the discharge capacity of the first cycle at the 348th cycle in the battery of Comparative Example 2. The number of cycles in which the discharge capacity was less than 90% and the discharge capacity was less than 90% was defined as the life cycle number.

  When the batteries of Comparative Example 1 and Comparative Example 2 after the above test were disassembled and the state of the electrode surface was observed, wrinkles that were thought to be due to the contraction of the current collector were observed on the surface of the electrode in any battery.

  The above results are summarized in Table 1.

  From Table 1, in Examples 1 to 3, where Ya and Yb are both in the range of 4 to 17 GPa and | Ya-Yb | is in the range of 5.0 or less, the temperature change amount of the current collector is small, and charging / discharging It can be seen that the characteristics are excellent. On the other hand, in Comparative Example 1 in which Ya was lower than 4 GPa and Comparative Example 2 in which | Ya-Yb | was higher than 5.0, it was found that the charge / discharge characteristics were inferior to those in Examples 1 to 3. .

  The present invention can be implemented in other forms than the above without departing from the spirit of the present invention. The embodiments disclosed in the present application are merely examples, and the present invention is not limited thereto. The scope of the present invention is construed in preference to the description of the appended claims rather than the description of the above specification, and all modifications within the scope equivalent to the claims are construed in the scope of the claims. It is included.

  As described above, the present invention can provide a nonaqueous electrolyte battery that is lightweight and has high charge / discharge characteristics, and can be widely used as a power source for portable devices such as mobile phones and notebook personal computers.

DESCRIPTION OF SYMBOLS 10 Electrode 11 Current collector 11a Resin film 11b Conductive layer 12 Active material containing layer 20 Electrode 30 Electrode body 31 Positive electrode 31a Positive electrode lead terminal 32 Negative electrode 32a Negative electrode lead terminal 33 Separator 34 Exterior material 34a First exterior surface 34b Second exterior surface 35 Electrode storage part 36a Positive electrode lead terminal part 36b Negative electrode lead terminal part 37a, 37b, 37c Sealing part

【００７２】
表１からＹａ及びＹｂがともに４〜１７ＧＰａの範囲にあり、且つ｜Ｙａ−Ｙｂ｜が５．０以下の範囲にある実施例１〜３では、集電体の温度変化量が小さく、充放電特性が優れていることが分かる。一方、Ｙａが４ＧＰａを下回った比較例１及び｜Ｙａ−Ｙｂ｜が５．０を上回った比較例２では、いずれも実施例１〜３に比べて、充放電特性が劣っていることが分かる。
【００７３】
本発明は、その趣旨を逸脱しない範囲で、上記以外の形態としても実施が可能である。本出願に開示された実施形態は一例であって、これらに限定はされない。本発明の範囲は、上述の明細書の記載よりも、添付されている請求の範囲の記載を優先して解釈され、請求の範囲と均等の範囲内での全ての変更は、請求の範囲に含まれるものである。
【産業上の利用可能性】
【００７４】
以上説明したように、本発明は、軽量で且つ充放電特性が高い非水電解質電池を提供でき、携帯電話やノート型パーソナルコンピューター等の携帯機器の電源として広く利用できる。
【符号の説明】
【００７５】
１０ 電極
１１ 集電体
１１ａ 樹脂フィルム
１１ｂ 導電層
１２ 活物質含有層
２０ 電極
３０ 電極体
３１ 正極
３１ａ 正極リード端子
３２ 負極
３２ａ 負極リード端子
３３ セパレータ
３４ 外装材
３４ａ 第１外装面
３４ｂ 第２外装面
３５ 電極収納部
３６ａ 正極リード端子部
３６ｂ 負極リード端子部
３７ａ、３７ｂ、３７ｃ 封止部
[Document Name] Description [Title of Invention] Nonaqueous Electrolyte Battery [Technical Field]
[0001]
The present invention relates to a non-aqueous electrolyte battery such as a lithium ion secondary battery.
[Background]
[0002]
A non-aqueous electrolyte battery represented by a lithium ion secondary battery is widely used as a power source for portable devices such as a mobile phone and a notebook personal computer because of its high energy density. As the performance of portable devices increases, the capacity of lithium ion secondary batteries tends to increase further, and it is necessary to further improve the energy density.
[0003]
The nonaqueous electrolyte battery includes electrodes (positive electrode and negative electrode) in which an active material-containing layer is provided on one side or both sides of a current collector. The current collector is usually formed from a metal foil. However, in order to reduce the weight of the current collector, which is a component of the nonaqueous electrolyte battery, to the limit and improve the energy density of the nonaqueous electrolyte battery, a resin is used. A current collector in which a conductive thin film is formed on the surface of a film has been proposed (see, for example, Patent Document 1 and Patent Document 2).
[Prior art documents]
[Patent Literature]
[0004]
[Patent Document 1] JP-A-9-213338 [Patent Document 2] JP-A-9-283149 [Summary of Invention]
[Problems to be solved by the invention]
[0005]
However, when a resin film is used as the base material of the current collector, it is inevitable that the resin film expands as the temperature rises due to charging / discharging of the battery. When the resin film, which is the base material of the current collector, expands during use of the battery, the entire current collector also expands, and the active material-containing layer provided on the current collector is not bonded to the current collector. This may be sufficient, and the charge / discharge characteristics of the battery may be reduced.
[0006]
The present invention solves the above problems and provides a nonaqueous electrolyte battery that is lightweight and has high charge / discharge characteristics.
[Means for Solving the Problems]
[0007]
The non-aqueous electrolyte battery of the present invention is a non-aqueous electrolyte battery including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte, wherein the positive electrode and the negative electrode are a current collector and a current collector, respectively. An active material-containing layer formed thereon, the current collector includes a resin film and a conductive layer provided on at least one surface of the resin film, and the active material-containing layer is formed of the conductive layer. The Young's modulus Ya in the arbitrary direction of the current collector and the Young's modulus Yb in the direction orthogonal to the arbitrary direction are 4 GPa or more and 17 GPa or less, respectively, and the difference between the Young's modulus Ya and the Young's modulus Yb The absolute value of | Ya−Yb | is 5.0 or less.
【Effect of the invention】
[0008]
According to the present invention, a non-aqueous electrolyte battery that is lightweight and has high charge / discharge characteristics can be provided.
[Brief description of the drawings]
[0009]
FIG. 1 is a schematic cross-sectional view showing an example of an electrode used in a nonaqueous electrolyte battery of the present invention.
FIG. 2 is a schematic cross-sectional view showing another example of an electrode used in the nonaqueous electrolyte battery of the present invention.
3A is a perspective view for explaining an electrode body used in the present invention, FIG. 3B is a perspective view showing a state in which the electrode body is housed in an exterior material, and FIG. 3C is an electrode body. It is a perspective view of the state accommodated in the exterior material.
BEST MODE FOR CARRYING OUT THE INVENTION
[0010]
The nonaqueous electrolyte battery of the present invention includes a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte. The positive electrode and the negative electrode each include a current collector and an active material-containing layer formed on the current collector, and the current collector is disposed on at least one surface of the resin film and the resin film. The active material-containing layer is formed on the conductive layer. Furthermore, the Young's modulus Ya in the arbitrary direction of the current collector and the Young's modulus Yb in the direction orthogonal to the arbitrary direction are 4 GPa or more and 17 GPa or less, respectively, and the absolute value of the difference between the Young's modulus Ya and the Young's modulus Yb | Ya-Yb | is set to 5.0 or less.
[0011]
Usually, after a resin film is formed by extrusion molding, strength is imparted by uniaxial stretching or biaxial stretching. The inventors pay attention to the Young's modulus, which is one of the measures of the strength of the resin film, examine the relationship between the Young's modulus of the resin film and the temperature expansion coefficient of the resin film, and specify the Young's modulus of the resin film. By setting the range, a resin film having a small temperature expansion coefficient was realized. By using the resin film as a base material for the current collector, a non-aqueous electrolyte battery that is light in weight and high in charge / discharge characteristics is realized by realizing a current collector that is small in expansion even when the temperature changes.
[0012]
In the present invention, the Young's modulus Ya in the arbitrary direction of the current collector and the Young's modulus Yb in the direction orthogonal to the arbitrary direction are 4 GPa or more and 17 GPa or less, more preferably 7 GPa or more and 17 GPa or less. Thereby, the expansion | swelling by the temperature rise of a collector can be suppressed. When at least one of the Young's moduli Ya and Yb is less than 4 GPa, the current collector expands due to temperature rise, and the charge / discharge characteristics of the battery deteriorate. The higher the Young's modulus Ya, Yb is, the more the current collector can be prevented from expanding due to the temperature rise, but the upper limit of the Young's modulus of the industrial resin that is the material of the resin film used as the base material of the current collector Is about 17 GPa, the upper limit of the Young's modulus of the current collector is about 17 GPa as long as an industrial resin is used.
[0013]
In the present invention, the absolute value | Ya−Yb | of the difference between the Young's modulus Ya and the Young's modulus Yb is set to 5.0 or less. Thereby, since the expansion | swelling by the temperature rise of a collector can be suppressed equally, the charging / discharging characteristic of a battery can be maintained reliably.
[0014]
In the present invention, the Young's modulus of a current collector including a resin film and a conductive layer is measured based on the following measurement method. The measurement environment is a temperature of 23 ° C. ± 5 ° C. and a relative humidity of 50% ± 10%. Using a tensile tester as the measuring device, set the measurement sample with the load cell interval of the tensile tester set to 10 cm, pull the sample at a pulling speed of 10 mm / min, read the weight at that time, and read the sample at a load of 1.5 N The Young's modulus is obtained by dividing the difference between the amount of elongation and the amount of elongation of the sample at 0.5 N by the thickness of the sample.
[0015]
The thickness of the resin film is preferably 3 μm or more and 20 μm or less, and more preferably 4.5 μm or more and 10 μm or less. If it is less than 3 μm, it is too thin to make it difficult to process the film, and it tends to be difficult to ensure the strength of the film. On the other hand, when the thickness exceeds 20 μm, the volume occupied by the film increases, and in the case of a battery having the same volume, the volume of the active material-containing layer decreases by the volume increase of the film, so the volume energy density of the battery decreases.
[0016]
The conductive layer preferably has a thickness of 100 nm to 3 μm. If it is less than 100 nm, the electrical resistance as a current collector increases, and the current collection effect tends to decrease. If the thickness exceeds 3 μm, the stress of the conductive layer increases, and the current collector may be warped and undulated, making it difficult to use it as a current collector.
[0017]
Hereinafter, embodiments of electrodes used in the present invention will be described with reference to the drawings. However, in FIGS. 1-2, the same code | symbol is attached | subjected to the same part and the overlapping description is abbreviate | omitted.
[0018]
FIG. 1 is a schematic cross-sectional view showing an example of an electrode used in the nonaqueous electrolyte battery of the present invention. In FIG. 1, an electrode (positive electrode or negative electrode) 10 includes a current collector 11 and an active material containing layer 12 formed on both surfaces of the current collector 11. The current collector 11 includes a resin film 11a and conductive layers 11b provided on both surfaces of the resin film 11a, and the active material-containing layer 12 and the conductive layer 11b are electrically joined.
[0019]
As the resin constituting the resin film 11a, for example, one resin selected from the group consisting of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), aramid, polyethylene, polypropylene, polystyrene, polyamide and polyimide is used. Can do. Moreover, as the resin film 11a, it is good also as a conductive resin film by mixing a conductive filler etc. with the said resin. As described above, the thickness of the resin film 11a is set to 3 μm or more and 20 μm or less.
[0020]
As a material constituting the conductive layer 11b, for example, a metal such as aluminum or copper, or a carbon material such as graphite can be used. Although the method of forming the conductive layer 11b on the resin film 11a is not limited, for example, a vacuum deposition method, a sputtering method, a plating method, or the like can be used. As described above, the thickness of the conductive layer 11b is set to 100 nm or more and 3 μm or less.
[0021]
The Young's modulus of the current collector 11 can be substantially controlled by adjusting the Young's modulus of the resin film 11a. Moreover, the Young's modulus of the resin film 11a can be controlled by adjusting the draw ratio, for example. Generally, increasing the draw ratio increases the Young's modulus of the resin film.
[0022]
The active material-containing layer 12 is formed of an active material, a conductive aid, a binder, and the like. The thickness of the active material-containing layer 12 is not particularly limited, but if it is too thin, the volume of the active material-containing layer 12 is relatively reduced in the entire battery, and is preferably 150 μm or more per side.
[0023]
FIG. 2 is a schematic cross-sectional view showing another example of an electrode used in the nonaqueous electrolyte battery of the present invention. 2, the electrode 20 is the electrode 10 shown in FIG. 1 except that the conductive layer 11b is provided only on one surface of the resin film 11a and the active material-containing layer 12 is formed only on the conductive layer 11b. It is the same composition as.
[0024]
Next, an embodiment of the nonaqueous electrolyte battery of the present invention will be described by taking a flat lithium ion secondary battery as an example. 3A is a perspective view for explaining an electrode body used in the present embodiment, FIG. 3B is a perspective view showing a state in which the electrode body is housed in an exterior material, and FIG. 3C is an electrode body as an exterior material. It is a perspective view of the stored state.
[0025]
3A, the electrode body 30 is produced by laminating a rectangular positive electrode 31 and a rectangular negative electrode 32 with a rectangular separator 33 interposed therebetween. A positive electrode lead terminal 31 a is provided at one end of the positive electrode 31, and a negative electrode lead terminal 32 a is provided at one end of the negative electrode 32.
[0026]
In FIG. 3B, the rectangular-shaped exterior material 34 which has flexibility is valley-folded, and is comprised from the 1st exterior surface 34a and the 2nd exterior surface 34b. An electrode housing portion 35 is formed on the first exterior surface 34a by deep drawing. Also, each positive electrode lead terminal 31a (FIG. 3A) and each negative electrode lead terminal 32a (FIG. 3A) are overlapped and welded to form a positive electrode lead terminal portion 36a and a negative electrode lead terminal portion 36b, respectively.
[0027]
In FIG. 3C, the electrode body 30 is housed in an electrode housing portion 35 formed by a first exterior surface 34a and a second exterior surface 34b that are valley-folded together with the nonaqueous electrolyte. Further, among the outer periphery of the exterior member 34, three sides other than the one side that is valley-folded are joined with a predetermined width to form the sealing portions 37a, 37b, and 37c. The positive electrode lead terminal portion 36 a and the negative electrode lead terminal portion 36 b are drawn out from the sealing portion 37 c facing one side of the exterior material 34 that is folded down.
[0028]
The positive electrode 31 is a mixture of a positive electrode active material, a positive electrode conductive additive, a positive electrode binder, and the like, and a positive electrode mixture paste obtained by sufficiently kneading the mixture with a solvent. After coating and drying, the positive electrode mixture layer (positive electrode active material-containing layer) can be formed by controlling it to a predetermined thickness and a predetermined electrode density.
[0029]
As the positive electrode active material, for example, a lithium manganese composite oxide having a spinel structure having a composition of the general formula LiMn ₂ O ₄ (a part of the constituent elements is replaced with an element such as Ge, Zr, Mg, Ni, Al, Co) A lithium cobalt composite oxide having a composition of the general formula LiCoO _{2 (} a composite in which some of the constituent elements are substituted with elements such as Ni, Al, Mg, Zr, Ti, B, etc.) And a lithium nickel composite oxide having a composition of the general formula LiNiO ₂ (a composite oxide in which some of the constituent elements are substituted with elements such as Co, Al, Mg, Zr, Ti, and B) A composite oxide having a layered structure such as a lithium-containing composite oxide having an olivine structure having a composition of the general formula LiMPO ₄ (where M is at least one selected from Ni, Co and Fe). Example It is.
[0030]
The positive electrode conductive auxiliary agent may be added as necessary for the purpose of improving the electric conductivity of the positive electrode mixture layer. Examples of the conductive powder used as the conductive auxiliary agent include carbon black, ketjen black, and acetylene black. Carbon powder such as fibrous carbon and graphite, and metal powder such as nickel powder can be used.
[0031]
Examples of the positive electrode binder include, but are not limited to, polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE).
[0032]
As the positive electrode current collector, one having the same structure as the current collector 10 shown in FIG. 1 and using, for example, a PET film as the resin film 11a and an aluminum layer as the conductive layer 11b is used. .
[0033]
As the solvent, for example, N-methyl-2-pyrrolidone or the like can be used.
[0034]
The negative electrode 32 is obtained by using a negative electrode mixture paste obtained by sufficiently kneading a mixture containing a negative electrode active material, a negative electrode conductive additive, a negative electrode binder, and the like, with both sides of the negative electrode current collector according to the present invention. After coating and drying, the negative electrode mixture layer (negative electrode active material-containing layer) can be formed by controlling it to a predetermined thickness and a predetermined electrode density.
[0035]
Examples of the negative electrode active material include carbon materials such as natural graphite or artificial graphite such as massive graphite, flaky graphite, and earthy graphite, but are not limited thereto as long as lithium ions can be occluded / released. .
[0036]
As the negative electrode current collector, one having the same structure as the current collector 10 shown in FIG. 1 and using a PET film as the resin film 11a and a copper layer as the conductive layer 11b is used, for example. .
[0037]
About the said conductive additive for negative electrodes, the binder for negative electrodes, and a solvent, the thing similar to what was used for the positive electrode can be used.
[0038]
As the separator 33, it is preferable to use a separator having a two-layer structure including a heat-resistant porous substrate having a thickness of 10 to 50 μm and a microporous film made of a thermoplastic resin having a thickness of 10 to 30 μm.
[0039]
The heat-resistant porous substrate may be formed of, for example, a fibrous material having a heat-resistant temperature of 150 ° C. or higher, and the fibrous material may be cellulose or a modified product thereof, polyolefin, polyester, polyacrylonitrile, aramid, polyamide. It can be formed of at least one material selected from the group consisting of imides and polyimides. More specifically, sheet-like materials such as woven fabrics and nonwoven fabrics (including paper) made of the above materials can be used as heat-resistant porous materials. It can be used as a quality substrate.
[0040]
The microporous film made of the thermoplastic resin has a melting point of 80 to 140 ° C., for example, in order to provide the separator with a shutdown function that closes the micropores at a certain temperature (100 to 140 ° C.) and increases the resistance. A microporous film made of a certain thermoplastic resin can be used. More specifically, a microporous sheet made of an olefin polymer such as polypropylene and polyethylene having resistance to organic solvents and hydrophobicity can be used.
[0041]
In order to further improve the heat resistance of the separator 33, an inorganic filler may be included in the heat-resistant porous substrate, and an inorganic filler layer having a thickness of about 3 to 10 μm is provided on the microporous film. May be. As the inorganic filler, for example, particles of at least one inorganic oxide selected from the group consisting of alumina, silica, titanium oxide, zirconium oxide, and boehmite can be used.
[0042]
Although the thickness of the separator 33 is not specifically limited, Usually, it is 25-90 micrometers.
[0043]
As the exterior material 34, a laminate film in which a metal layer such as aluminum and a thermoplastic resin layer are laminated can be used. For example, a laminate film in which a thermoplastic resin layer having a thickness of 20 to 50 μm is provided on the outer side of an aluminum layer having a thickness of 20 to 100 μm and an adhesive layer having a thickness of 20 to 100 μm is provided on the inner side thereof can be used. Thereby, sealing part 37a, 37b, 37c can be joined reliably by heat welding.
[0044]
Although the thickness of the exterior material 34 is not specifically limited, Usually, it is 60-250 micrometers.
[0045]
As the non-aqueous electrolyte, a solution (non-aqueous electrolytic solution) in which a lithium salt is dissolved in an organic solvent is used.
[0046]
Examples of the organic solvent include vinylene carbonate (VC), propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (MEC). , Γ-butyrolactone or other organic solvents can be used alone or in combination. Furthermore, as the lithium salt, for example, it can be used at least one lithium salt selected from _{LiClO 4, LiPF 6, LiBF 4} , LiAsF 6, LiSbF 6, LiCF 3 SO 3 and the like. The concentration of Li ions in the nonaqueous electrolytic solution may be 0.5 to 1.5 mol / L.
[0047]
In the embodiment of the non-aqueous electrolyte battery, an example using a laminated electrode body in which rectangular electrodes are stacked via a separator is shown. However, a wound electrode body in which a long electrode is wound via a separator. May be used.
[0048]
【Example】
Next, this invention is demonstrated based on an Example.
[0049]
Example 1
<Preparation of current collector>
The current collector used for the positive electrode and the negative electrode was produced as follows.
[0050]
A PEN film “Teonex” (trade name) manufactured by Teijin Ltd. having a thickness of 6.1 μm was used as the resin film. First, the resin film is set on the unwinding part of the vacuum deposition apparatus, and after reducing the pressure to 1.5 × 10 ⁻³ Pa, the resin film is conveyed through a cooling drum at −20 ° C. at a conveyance speed of 60 m / min and a conveyance tension. The vehicle was run at 100 N / m. At this time, aluminum having a purity of 99.99% by weight was evaporated by heating with an electron beam (output 5.1 kW), aluminum was deposited on the surface of the resin film to form an aluminum thin film, and the resin film was wound up. The thickness of the aluminum thin film was about 150 nm. Next, after forming the aluminum thin film in the same manner as described above except that the transport tension was set to 80 N / min on the surface opposite to the surface on which the aluminum thin film was formed of the resin film wound up earlier, As a result, a positive electrode current collector in which an aluminum thin film was formed on both surfaces of the resin film was produced.
[0051]
Further, in place of the deposition of aluminum, copper having a purity of 99.99% by weight was deposited on a resin film, and a copper thin film having a thickness of about 150 nm was formed on both surfaces of the resin film. A negative electrode current collector was produced in the same manner.
[0052]
<Measurement of Young's modulus of current collector>
The Young's modulus of the produced current collector was measured as follows. First, a sample having a width of 12.65 mm and a length of 15 cm was cut out from the produced current collector in an arbitrary direction to be a first sample, and the cutting direction of the first sample was taken as a first direction. Next, the first test sample is set with the load cell interval of the tensile tester set to 10 cm, pulled in the length direction at a speed of 10 mm / min, the weight at that time is read, and the amount of elongation of the sample when the weight is 1.5 N The Young's modulus Ya in the first direction (arbitrary direction) was determined by dividing the difference between the sample elongation at 0.5N and the thickness of the first sample.
[0053]
However, the size of the sample used for measuring the Young's modulus of the current collector is not limited to the size of the sample.
[0054]
Next, the second sample is cut out in the same manner as the first sample except that it is cut out from the same current collector in the direction perpendicular to the cutting direction of the first sample, the cutting direction of the second sample is set as the second direction, The Young's modulus Yb in the second direction (direction perpendicular to the arbitrary direction) was determined in the same manner as in the first sample except that the second sample was used.
[0055]
The Young's modulus was measured in an atmospheric environment at a temperature of 23 ° C. ± 5 ° C. and a relative humidity of 50% ± 10%.
[0056]
<Measurement of temperature change of current collector length>
As a measurement sample of the temperature change amount of the current collector length, a first sample and a second sample are prepared in the same manner as in the measurement of the Young's modulus of the current collector, and the first sample and The amount of temperature change in the length of the second sample was measured. First, the length of each sample in the length direction was measured at an ambient temperature of 10 ° C., and the length was defined as L1. Next, the ambient temperature was raised to 29 ° C., the length in the length direction of each sample was measured, and the length was defined as L2. Subsequently, (L2-L1) / L1 was calculated, and the temperature change amount was determined in ppm.
[0057]
<Production of nonaqueous electrolyte battery>
A nonaqueous electrolyte battery was produced using the produced current collector as follows.
[0058]
94 parts by mass of LiMn ₂ O ₄ as a positive electrode active material, 3 parts by mass of acetylene black as a conductive additive, and 3 parts by mass of polyvinylidene fluoride as a binder are mixed so as to be uniform using N-methyl-2-pyrrolidone as a solvent. Then, a positive electrode mixture-containing paste was prepared. The paste is applied to both sides of the positive electrode current collector, dried to form a positive electrode mixture layer, press-formed with a roller, and then cut so that the electrode application surface has a width of 40 mm and a length of 72 mm. Thus, a positive electrode was produced. Moreover, the positive electrode lead terminal was formed in the one end part of the positive electrode in which the positive mix layer was not formed.
[0059]
Water as a solvent using graphite powder having a BET specific surface area of 2.2 m ² / g and an average particle diameter of 18 μm as the negative electrode active material, and carboxymethyl cellulose (CMC) and styrene-butadiene copolymer rubber (SBR) as the binder. At the same time, graphite powder, CMC, and SBR were mixed at a mass ratio of 96: 2: 2 to prepare a slurry-like negative electrode mixture-containing paste. The paste is applied to both sides of the negative electrode current collector, dried to form a negative electrode mixture layer, press-formed with a roller, and then cut so that the electrode application surface has a width of 42 mm and a length of 74 mm. Thus, a negative electrode was produced. Moreover, the negative electrode lead terminal was formed in the one end part of the negative electrode in which the negative mix layer was not formed.
[0060]
As a separator, a porous laminated film was prepared by laminating a porous film in which a boehmite particle layer having a thickness of 5 μm was formed on a microporous film made of polyethylene having a thickness of 16 μm and a nonwoven fabric made of polyethylene terephthalate having a thickness of 20 μm. The total thickness of the porous laminated film (separator) was about 20 μm, and the opening ratio was 50%.
[0061]
Next, using the 15 positive electrodes and the 16 negative electrodes, the separator is disposed between the positive electrode and the negative electrode so that the nonwoven fabric is in contact with the positive electrode, and each positive electrode and each negative electrode are laminated. Were welded to form a positive electrode lead terminal portion, each negative electrode lead terminal was welded to form a negative electrode lead terminal portion, and then inserted into an outer packaging material made of a laminate film.
[0062]
Using a solution obtained by dissolving LiPF ₆ at a ratio of 1.2 mol / L in a solvent obtained by mixing ethylene carbonate and diethyl carbonate in a volume ratio of 1: 2 in a non-aqueous electrolyte, this was injected into the outer packaging. After that, the opening was sealed to produce a nonaqueous electrolyte battery.
[0063]
(Example 2)
Instead of the PEN film as a resin film, a current collector was prepared in the same manner as in Example 1 except that a PET film “Lumirror” (trade name) manufactured by Toray Industries, Inc. having a thickness of 6.1 μm was used. The temperature change of the Young's modulus of the current collector and the length of the current collector was measured to produce a nonaqueous electrolyte battery.
[0064]
(Example 3)
Instead of the PEN film as a resin film, a current collector was prepared in the same manner as in Example 1 except that an aramid film “Mikutron” (trade name) manufactured by Toray Industries, Inc. having a thickness of 3.6 μm was used. The temperature change of the Young's modulus of the current collector and the length of the current collector was measured to produce a nonaqueous electrolyte battery.
[0065]
(Comparative Example 1)
After applying a polyvinyl alcohol (PVA) aqueous solution to one side of the PET film used in Example 2, it was dried at 80 ° C. to form a PVA layer having a thickness of 1.0 μm to prepare a PET film with reduced strength. A current collector was prepared in the same manner as in Example 2 except that the PET film was used, and the temperature change in the Young's modulus of the current collector and the length of the current collector was measured. A battery was produced.
[0066]
(Comparative Example 2)
The PEN film used in Example 1 was pulled in a dryer at 130 ° C. with a tension of 150 N / m in the longitudinal direction to increase the strength in the longitudinal direction, and the PEN film was used except that the PEN film was used. A current collector was prepared in the same manner as in Example 1, and the temperature change of the Young's modulus of the current collector and the length of the current collector was measured to prepare a nonaqueous electrolyte battery.
[0067]
<Charge / discharge cycle test>
Next, the charge / discharge cycle test was performed as follows about the nonaqueous electrolyte battery of Examples 1-3 and Comparative Examples 1-2.
[0068]
Each battery was subjected to constant current-constant voltage charging (total charging time: 3 hours) with a constant current of 1C and a constant voltage of 4.2V, and then a constant current discharge at 1C (end-of-discharge voltage: 2.7V). The discharge capacity (mAh) was measured. With this as one cycle, charging and discharging were repeated under the above conditions until the discharge capacity of each cycle was less than 90% of the discharge capacity of the first cycle. However, the maximum number of charge / discharge cycles was 500. As a result, in the batteries of Examples 1 to 3, the discharge capacity at the 500th cycle was maintained at 90% or more with respect to the discharge capacity at the first cycle. On the other hand, in the battery of Comparative Example 1, the discharge capacity is less than 90% with respect to the discharge capacity of the first cycle at the 225th cycle, and with respect to the discharge capacity of the first cycle at the 348th cycle in the battery of Comparative Example 2. The number of cycles in which the discharge capacity was less than 90% and the discharge capacity was less than 90% was defined as the life cycle number.
[0069]
When the batteries of Comparative Example 1 and Comparative Example 2 after the above test were disassembled and the state of the electrode surface was observed, wrinkles that were thought to be due to the contraction of the current collector were observed on the surface of the electrode in any battery.
[0070]
The above results are summarized in Table 1.
[0071]
[Table 1]

[0072]
From Table 1, in Examples 1 to 3, where Ya and Yb are both in the range of 4 to 17 GPa and | Ya-Yb | is in the range of 5.0 or less, the temperature change amount of the current collector is small, and charging / discharging It can be seen that the characteristics are excellent. On the other hand, in Comparative Example 1 in which Ya was lower than 4 GPa and Comparative Example 2 in which | Ya-Yb | was higher than 5.0, it was found that the charge / discharge characteristics were inferior to those in Examples 1 to 3. .
[0073]
The present invention can be implemented in other forms than the above without departing from the spirit of the present invention. The embodiments disclosed in the present application are merely examples, and the present invention is not limited thereto. The scope of the present invention is construed in preference to the description of the appended claims rather than the description of the above specification, and all modifications within the scope equivalent to the claims are construed in the scope of the claims. It is included.
[Industrial applicability]
[0074]
As described above, the present invention can provide a nonaqueous electrolyte battery that is lightweight and has high charge / discharge characteristics, and can be widely used as a power source for portable devices such as mobile phones and notebook personal computers.
[Explanation of symbols]
[0075]
DESCRIPTION OF SYMBOLS 10 Electrode 11 Current collector 11a Resin film 11b Conductive layer 12 Active material containing layer 20 Electrode 30 Electrode body 31 Positive electrode 31a Positive electrode lead terminal 32 Negative electrode 32a Negative electrode lead terminal 33 Separator 34 Exterior material 34a First exterior surface 34b Second exterior surface 35 Electrode storage part 36a Positive electrode lead terminal part 36b Negative electrode lead terminal part 37a, 37b, 37c Sealing part

Claims (3)

A non-aqueous electrolyte battery comprising a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte,
The positive electrode and the negative electrode each include a current collector and an active material-containing layer formed on the current collector,
The current collector includes a resin film and a conductive layer provided on at least one side of the resin film,
The active material-containing layer is formed on the conductive layer,
The Young's modulus Ya in the arbitrary direction of the current collector and the Young's modulus Yb in the direction orthogonal to the arbitrary direction are 4 GPa or more and 17 GPa or less, respectively.
An absolute value | Ya−Yb | of a difference between the Young's modulus Ya and the Young's modulus Yb is 5.0 or less.   The nonaqueous electrolyte battery according to claim 1, wherein a thickness of the resin film is 3 μm or more and 20 μm or less. The nonaqueous electrolyte battery according to claim 1, wherein the conductive layer has a thickness of 100 nm to 3 μm.

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