JP2010080422A - Electrode body and nonaqueous electrolyte battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode body for manufacturing a nonaqueous electrolyte battery having a large discharge capacity, and to provide a nonaqueous electrolyte battery using the electrode body. <P>SOLUTION: The electrode body has an average thickness of 0.05 to 0.3 mm and a porosity of 15 vol.% or less. The electrode body is used as a cathode active material layer 11 in a nonaqueous electrolyte battery 100. The electrode body can be a supporting body for forming other composition members 12, 31, 21, 22 of the battery when the nonaqueous electrolyte battery 100 is manufactured. By making the electrode body to be the supporting body, a cathode collector can be made an average thickness of 0.01 to 30 μm; and since the ratio of the cathode active material layer 11 in the battery can be made large, the nonaqueous electrolyte battery 100 can have an excellent discharging capacity. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrode body used for a nonaqueous electrolyte battery, a nonaqueous electrolyte battery using the electrode body, and a method for producing a nonaqueous electrolyte battery.

  Nonaqueous electrolyte batteries are used as power sources for relatively small electric devices such as portable devices. The non-aqueous electrolyte battery includes a positive electrode active material layer, a negative electrode active material layer, and a lithium ion conductive layer that mediates lithium ion conduction therebetween (see, for example, Patent Documents 1 and 2).

  In the non-aqueous electrolyte battery of Patent Document 1, a paste (slurry) in which a positive electrode active material is mixed with a resin binder or a solvent is prepared, and this slurry applied to a substrate (support) is used as a positive electrode. In this positive electrode, the support functions as a positive electrode current collector, and a slurry obtained by drying the slurry applied on the support functions as a positive electrode active material layer.

  In patent document 2, what formed the metal electrical power collector layer on the board | substrate is used as a support body, and what formed the positive electrode active material into a film by the vapor phase method on this support body is utilized as a positive electrode. .

Japanese Patent Publication No. 7-50617 JP 2005-251417 A

  However, since the non-aqueous electrolyte battery described in any of the above patent documents has a positive electrode active material layer formed on the support, damage to the support such as cracks, chips, and bending is caused when the positive electrode active material layer is formed. Thickness that does not occur is required. That is, the proportion of the support in the nonaqueous electrolyte battery is large, and the proportion of the positive electrode active material layer in the nonaqueous electrolyte battery is relatively small. Therefore, in a non-aqueous electrolyte battery whose overall size is determined, a positive electrode in which a positive electrode active material layer is formed on a support may not be a non-aqueous electrolyte battery having a discharge capacity according to the application. .

  In addition to the above problems, when the positive electrode active material layer is formed by the coating method described in Patent Document 1, there is a problem that voids are easily formed in the positive electrode active material layer, and the discharge capacity is further reduced by the amount of the voids. In addition, when the positive electrode active material layer is formed by the vapor phase method described in Patent Document 2, stress remains in the positive electrode active material layer, and is easily peeled off from the support. In particular, as the thickness of the positive electrode active material layer increases, the residual stress increases and it becomes easier to peel off from the support. Therefore, the thickness of the positive electrode active material layer can be practically only about 10 μm, and the discharge capacity reaches a peak. There is also a problem of becoming.

  The present invention has been made in view of the above circumstances, and one of its purposes is to provide an electrode body for producing a nonaqueous electrolyte battery having a large discharge capacity. Another object of the present invention is to provide a nonaqueous electrolyte battery using the electrode body of the present invention and a method for producing the same.

(1) The electrode body of the present invention is an electrode body used as a positive electrode active material layer or a negative electrode active material layer of a nonaqueous electrolyte battery, and has an average thickness of 0.05 mm to 0.3 mm and a porosity of 15 It is characterized by being not more than volume%. The average thickness is the thickness obtained by averaging the thicknesses of different locations, and the same applies to the average thickness of each layer in the non-aqueous electrolyte battery described later.

The electrode body of the present invention is classified into one used as a positive electrode active material layer (positive electrode body) and one used as a negative electrode active material layer (negative electrode body) depending on the type of active material constituting the electrode body. For example, an electrode body made of LiCoO ₂ is a positive electrode body, and an electrode body made of Li ₅ Ti ₄ O ₁₂ is a negative electrode body.

  According to the configuration of the present invention, since the electrode body can be handled alone, when manufacturing a non-aqueous electrolyte battery, the electrode body is replaced with other battery constituent members (specifically, a current collector or a lithium ion). The support can be a conductive layer. That is, according to the electrode body of the present invention, like the conventional battery, when forming the positive electrode active material layer or the negative electrode active material layer, the current collector that does not directly contribute to increasing the discharge capacity of the battery is supported. There is no need to use it as a body. As a result, a very thin current collector can be used as compared with the conventional nonaqueous electrolyte battery, so that the proportion of the positive electrode active material layer in the battery can be increased, and the discharge capacity of the nonaqueous electrolyte battery can be increased. Can be bigger.

  The reason why the electrode body can be handled as a single body is that the electrode body has a strength that does not easily cause cracking or chipping, and the strength is ensured by the thickness and porosity of the electrode body. The average thickness d of the electrode body of the present invention is 0.05 mm to 0.3 mm. By setting the thickness within this range, a sufficient discharge capacity can be secured while maintaining the strength of the electrode body. . Moreover, the porosity of the electrode body of this invention is 15 volume% or less, By setting it as the porosity of this range, sufficient discharge capacity can be ensured, maintaining the intensity | strength of an electrode body. If the porosity exceeds 15% by volume, the electrode body may become brittle, the diffusion resistance of lithium ions in the electrode body becomes too high, and the discharge capacity of the battery decreases. In addition, it is technically difficult to manufacture an electrode body having a porosity of 0.1% by volume or less.

(2) As an embodiment of the electrode body of the present invention, the variation in thickness with respect to the average thickness d of the electrode body is ± 0.05 d or less, and the warp of the electrode body is a warp having a radius of 1.5 m or more. preferable.

  If the variation in the thickness of the electrode body is small, when this electrode body is incorporated in a nonaqueous electrolyte battery and charged and discharged, there are no portions that are partially overcharged or overdischarged, and the battery performance is unlikely to deteriorate. Here, the variation in the thickness of the electrode body can be determined by measuring the thickness at any of a plurality of locations (3 or more, preferably 10 or more, more preferably 50 or more) in the plane of the electrode body. good. Further, in a large electrode body, for example, assuming a square square of 1 cm square with respect to the electrode body, the variation may be obtained by measuring the thickness of the electrode body at each square position. If the thickness variation at the measured location is ± 0.05 d or less, it can be considered that the thickness variation is ± 0.05 d or less over the entire surface of the electrode body.

  In addition, since the warpage of the electrode body is equal to or larger than the above radius, the electrode body is nearly flat. Therefore, when another layer (for example, a solid electrolyte layer) is formed on the electrode body by pressing, the electrode There is almost no risk of defects such as cracks in the body. The warpage of the electrode body is obtained as follows. First, when the electrode body is placed on a flat surface so that the upper surface is concave, the floating amount from the flat surface at both ends of the structure on the side facing the flat surface is measured. Next, from the measured floating amount and the dimensions of the electrode body, an arc that touches the plane passing through both ends of the structure, which is the measurement point of the floating amount, is assumed. The radius of this arc is regarded as the radius of curvature of the electrode body.

(3) A nonaqueous electrolyte battery can be produced using the electrode body described above. The nonaqueous electrolyte battery includes a positive electrode, a negative electrode, and a lithium ion conductive layer that mediates lithium ion conduction therebetween. As this positive electrode or negative electrode, one having a metal thin film having an average thickness of 0.01 μm to 30 μm is used on one surface of the electrode body of the present invention. For the formation of the metal thin film, a vapor phase method may be used. Specifically, the electrode body of the present invention is prepared, the electrode body is used as a support, and the metal thin film is formed on one surface of the electrode body by the vapor phase method. It is good to form.

  In the nonaqueous electrolyte battery of the present invention, the electrode body functions as a positive electrode active material layer, and the metal thin film functions as a current collector. Here, in the nonaqueous electrolyte battery of the present invention, since the electrode body is used as a support and a metal thin film is provided on one surface thereof, the average thickness of the metal thin film may be in the range of 0.01 μm to 30 μm. it can. The metal thin film of this thickness is difficult to handle by itself, and the electrode body can be formed by using the metal thin film as a support, or the metal thin film and the positive electrode material are put into a mold and pressure-molded. I can't really do that either. That is, the non-aqueous electrolyte battery of the present invention is a non-aqueous electrolyte battery having a thin current collector (metal thin film) that could not be a conventional non-aqueous electrolyte battery. Therefore, the nonaqueous electrolyte battery of the present invention has a larger proportion of the positive electrode active material layer in the battery and a larger discharge capacity per battery volume than the conventional nonaqueous electrolyte battery.

(4) As one form of the nonaqueous electrolyte battery of the present invention, the lithium ion conductive layer may be a polymer resin containing lithium. For example, a polymer resin separator impregnated with an electrolyte containing lithium (for example, a non-aqueous organic electrolyte obtained by dissolving a lithium compound in an organic solvent), a gel polymer resin containing lithium, etc. Is representative.

  By using a polymer resin as the lithium ion conductive layer, a positive electrode and a negative electrode are prepared separately, and a non-aqueous electrolyte battery is produced by a simple operation of stacking the positive electrode and the negative electrode with the polymer resin in between. can do.

(5) As one form of the nonaqueous electrolyte battery of the present invention, arithmetic mean roughness Ra (JIS B0601) of a surface (one surface) different from the surface (one surface) on which the current collector is formed in the electrode body 01) may be 0.1 μm or less, and a lithium ion conductive layer made of a solid electrolyte may be formed on the other surface.

  By using a solid electrolyte as the lithium ion conductive layer, problems when using a liquid electrolyte, for example, a problem of liquid leakage from the battery can be solved. In addition, by defining the surface roughness of the other surface of the electrode body, when forming a lithium ion conductive layer made of a solid electrolyte on the other surface of the electrode body, a coating failure is unlikely to occur. Therefore, it is possible to prevent a short circuit between the positive electrode and the negative electrode due to this defective coating.

(6) The manufacturing method of the nonaqueous electrolyte battery of the present invention is characterized by having the following configuration.
A step of preparing the above-described electrode body of the present invention.
Forming a metal thin film having an average thickness of 0.01 to 30 μm on one surface of the electrode body by a vapor phase method;

  According to the method for producing a nonaqueous electrolyte battery, a metal thin film serving as a current collector can be formed very thinly with respect to an electrode body serving as a positive electrode active material or a negative electrode active material. As a result, since the proportion of the current collector in the nonaqueous electrolyte can be kept low, a battery with a large capacity can be manufactured.

  In the electrode body of the present invention, the electrode body itself can be used as a support when producing a nonaqueous electrolyte battery. Therefore, when a non-aqueous electrolyte battery is produced using the electrode body of the present invention, the ratio of the positive electrode active material layer to the battery is increased, so that the discharge capacity per battery volume can be increased.

1 is a longitudinal sectional view of a nonaqueous electrolyte battery according to Embodiment 1. FIG. 3 is a longitudinal sectional view of a nonaqueous electrolyte battery according to Embodiment 2. FIG.

<Embodiment 1>
≪Overall structure≫
FIG. 1 is a longitudinal sectional view of a nonaqueous electrolyte battery according to this embodiment. The non-aqueous electrolyte battery 100 includes a positive electrode 1, a negative electrode 2, and a lithium ion conductive layer 31 disposed between both electrodes. The positive electrode 1 includes a positive electrode active material layer 11 and a positive electrode current collector 12, and the negative electrode 2 includes a negative electrode active material layer 21 and a negative electrode current collector 22. Furthermore, the battery 100 includes a buffer layer 41 that buffers the bias of lithium ions between the positive electrode active material layer 11 and the lithium ion conductive layer 31.

≪Each component≫
(Positive electrode active material layer)
The positive electrode active material layer 11 is a layer containing an active material that occludes and releases lithium ions. In particular, an oxide represented by LiAO ₂ or LiB ₂ O ₄ (A and B include at least one of Co, Mn, Al, and Ni) is preferable. For example, lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.5 Mn _1.5 O ₄ or LiMn ₂ O ₄ or a mixture thereof is suitable. Can be used for The total of Co, Mn, Al, and Ni in A and B may be 50% or more, and the positive electrode active material may be, for example, LiCo _0.5 Fe _0.5 O ₂ . Other may be used a positive electrode active material composed of spinel crystals such as LiNi _0.5 Mn _1.5 O ₄ and LiMn ₂ O ₄ as a cathode active material.

  The positive electrode active material layer 11 has an average thickness of 0.05 mm to 0.3 mm and a porosity of 15% by volume or less. By having such a thickness and porosity, even when only the positive electrode active material layer 11 is taken out (hereinafter, this state is referred to as a positive electrode body), it can be handled without causing cracks or chips. . As a result, as will be described later, the positive electrode current collector 12 can be formed using the positive electrode body as a support.

  If the thickness of the positive electrode active material layer 11 is too small, that is, if the thickness of the positive electrode body is too small, the capacity of the battery becomes small and it becomes difficult to handle the positive electrode body alone. On the other hand, if the thickness is too thick, the diffusion of lithium ions inside the positive electrode active material layer 11 becomes rate limiting, and the performance as the positive electrode active material layer 11 may be reduced.

  Further, when the porosity of the positive electrode active material layer 11 is large, the diffusion resistance of lithium ions and the electron conduction resistance inside the positive electrode active material layer 11 increase, so that the performance of the battery decreases. A more preferable porosity is 8% by volume or less.

  By the way, since the void portion formed in the positive electrode active material layer 11 is a factor that lowers the lithium ion conductivity of the layer 11, it is preferable that a lithium ion conductive material is disposed in the void portion. For example, an oxide containing Li and at least one of Ti, Nb, and Ta (a Li-La-Ti composite oxide, a Li-Ti composite oxide, or the like), Li, La, Zr, and When an oxide containing at least one of Ti (such as a Li-La-Zr composite oxide) is disposed in the void portion, the decrease in lithium ion conductivity due to the void portion can be compensated by the complex oxide.

Examples of the lithium ion conductive substance disposed in the gap of the positive electrode body include a polymer material having lithium ion conductivity. For example, a polymer material (for example, polyethylene oxide or the like) in which a compound containing lithium such as LiPF ₆ is dissolved may be filled in the voids. According to this configuration, similarly to the electrode body in which the composite oxide is disposed in the void portion, the void portion that hinders the conduction of lithium ions can be used as a lithium ion conduction path, so it can be used for a non-aqueous electrolyte battery. In this case, the discharge capacity of the battery can be increased.

  Such a positive electrode active material layer 11 can be formed by using a sintering method as described in Examples described later, for example. Here, as described above, if the void portion exists in the positive electrode active material layer 11, the lithium ion conductivity of the layer 11 is lowered. Therefore, the same layer 11 is formed so as to reduce the void portion. For example, a method of sintering the material of the positive electrode active material layer 11 after isotropic compression molding, a method of sintering while applying compression, and the like can be mentioned.

(Positive electrode current collector)
As the positive electrode current collector 12, one selected from Al, Ni, alloys thereof, and stainless steel can be suitably used. Here, as described above, since the electrode body to be the positive electrode active material layer 11 can be used as a support, the positive electrode current collector 12 is formed with respect to the electrode body (positive electrode active material layer 11). become. That is, conventionally, a positive electrode current collector is used as a support and a positive electrode active material layer is formed thereon, but the reverse is true in the present invention. By reversing the formation order, in the conventional nonaqueous electrolyte battery, the positive electrode current collector 12 that must be thickened can be made 0.01 μm to 30 μm on average. In other words, the positive electrode current collector 12 occupying the nonaqueous electrolyte battery 100 is thin, and the positive electrode active material layer 11 is correspondingly thick. Such a positive electrode current collector 12 can be formed using a vapor deposition method using the positive electrode active material layer 11 as a base material.

(Negative electrode active material layer)
The negative electrode active material layer 21 is composed of a layer containing an active material that occludes and releases lithium ions. For example, as the negative electrode active material layer 21, one selected from the group consisting of Li metal and a metal capable of forming an alloy with Li metal, or a mixture or alloy thereof can be preferably used. The element capable of forming an alloy with Li is preferably at least one selected from the group consisting of Al, Si, C, Sn, Bi, and In. In addition, a composite oxide of Li and Ti (Li ₄ Ti ₅ O ₁₂ or the like), an oxide of Si, Sn, or V (SiO, SnO, V ₂ O ₅ or the like) can be used.

  Similarly to the positive electrode active material layer 11, the negative electrode active material layer 21 can also be an electrode body (hereinafter referred to as a negative electrode body) that can be handled alone. The average thickness and porosity of the negative electrode body are set to 0.05 mm to 0.3 mm and 15% by volume or less so that the negative electrode body can be handled alone (same as the positive electrode body). You may arrange | position a lithium ion conductive substance also to the space | gap part of the negative electrode active material layer 21 (negative electrode body).

  Moreover, the negative electrode active material layer 21 does not necessarily need to be composed of a negative electrode body that can be handled alone. For example, the lithium ion conductive layer 31 is laminated on the positive electrode body described above, and the negative electrode active material layer 21 is further formed thereon. At that time, the negative electrode active material layer 21 may be formed by a vapor deposition method or may be formed by bonding a foil.

(Negative electrode current collector)
As the negative electrode current collector 22, one selected from Cu, Ni, Fe, Cr, and alloys thereof can be suitably used. When the negative electrode active material layer 21 is composed of a negative electrode body, the negative electrode current collector 22 can be made very thin. In addition, when the negative electrode active material layer 21 is composed of a highly conductive member, the negative electrode current collector 22 can be omitted.

(Lithium ion conductive layer)
The lithium ion conductive layer (hereinafter, SE layer) 31 is an oxide or sulfide solid electrolyte having lithium ion conductivity. The SE layer 31 preferably has a lithium ion conductivity (20 ° C.) of 10 ⁻⁵ S / cm or more and a Li ion transport number of 0.9 or more. The SE layer 31 preferably has an electron conductivity of 10 ⁻⁸ S / cm or less. Examples of the material of the SE layer 31 include Li—P—S—O composed of Li, P, S, and O, Li—PS—amorphous film or polycrystal composed of Li ₂ S and P ₂ S _5. It is preferable to comprise a film or the like.

  The average thickness of the SE layer 31 is preferably 0.3 to 10 μm. If the SE layer 31 is too thick, the internal resistance of the battery will increase. Conversely, if the SE layer 31 is too thin, it will be difficult to ensure insulation between the positive and negative electrodes.

(Buffer layer)
The buffer layer 41 is a layer for buffering the bias of lithium ions at the interface between the SE layer 31 and the positive electrode active material layer 11 when the SE layer 31 is a sulfide. The material of the buffer layer 41 is preferably a composite oxide containing Li and at least one of Ti, Nb, Ta and Si. Specifically, LixLa _{(2-X) / 3} TiO ₃ ( X = 0.1-0.5), Li ₄ Ti ₅ O ₁₂ , Li _3.6 Si _0.6 P _0.4 O ₄ , Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ Li _1.8 Cr _0.8 Ti _1.2 (PO ₄ ) ₃ , LiNbO ₃ , LiTaO ₃ , Li _1.4 In _0.4 Ti _1.6 (PO ₄ ) ₃ or the like is used alone or in combination. it can. When the SE layer 31 is made of an oxide, the buffer layer 41 may be omitted.

  The average thickness of the buffer layer 41 is preferably 5 to 100 nm. If the thickness of the buffer layer 41 is too thick, the internal resistance of the nonaqueous electrolyte battery increases and the output of the battery decreases. On the contrary, if the thickness is too thin, it is impossible to buffer the deviation of lithium ions.

<Embodiment 2>
≪Overall structure≫
In the second embodiment, a nonaqueous electrolyte battery having a lithium ion conductive layer configuration different from that of the first embodiment will be described with reference to FIG. The nonaqueous electrolyte battery 200 of the present embodiment has the same configuration as that of the battery of the first embodiment, except that the configuration of the lithium ion conductive layer 32 is different and a buffer layer is not required due to the difference in this configuration. Therefore, only the lithium ion conductive layer 32 will be described.

≪Lithium ion conductive layer≫
The lithium ion conductive layer 32 of the present embodiment is composed of a polymer resin having lithium ion conductivity. Typically, it is composed of an electrolytic solution having lithium ion conductivity and a polymer resin separator that insulates between the positive electrode active material layer 11 and the negative electrode active material layer 21. As an electrolytic solution, a single solvent or a mixed solvent of an organic solvent such as ethylene carbonate, propylene carbonate, γ-butyrolactone, diethyl carbonate, tetrahydrofuran, acetonitrile, etc., and LiPF ₆ , LiClO ₄ , LiBF ₄ , lithium halide, etc. as an electrolyte are used. Nonaqueous organic electrolyte solution in which one type or two or more types are dissolved may be mentioned. Moreover, as a separator, porous bodies (for example, nonwoven fabric), such as polyethylene and a polypropylene, are mentioned.

  A non-aqueous electrolyte battery having the configuration shown in FIGS. 1 and 2 was actually fabricated and its battery performance was evaluated.

  First, as shown below, a plurality of electrode bodies (hereinafter, referred to as a positive electrode body) serving as a positive electrode active material layer of a nonaqueous electrolyte battery and a plurality of positive electrode current collectors formed on one surface side of the positive electrode body Positive electrodes (positive electrode samples 1-3, 101-103) were produced.

<Preparation of positive electrode sample>
≪Positive electrode sample 1≫
Lithium hydroxide (LiOH) and cobalt acetate (Co (CH ₃ COO) ₂ ) were mixed in equimolar amounts, poured into distilled water, mixed and stirred, and then dried to obtain a precursor powder. This precursor powder was pressed into a pellet shape of φ20 mm × thickness 1 mm by applying a pressure of 80 MPa with a cold isostatic press, and calcined at 900 ° C. for 5 hours and calcined at 1050 ° C. for 3 hours. Thus, a positive electrode body made of LiCoO ₂ was obtained. This positive electrode body was formed without using a base material, and could be handled without causing cracks or chips.

Next, after the shape processing of the obtained positive electrode body, the surface was polished, and the final size was φ15 mm × average thickness 0.1 mm. During polishing, the parallelism between the positive electrode body and the polishing plate was adjusted so that the thickness variation of the positive electrode body was small and the radius of warpage was large. When the surface of the polished positive electrode body was measured with a step gauge, the arithmetic average roughness Ra (JIS B060001) was 0.03 μm. In addition, the thickness was measured 50 times while arbitrarily shifting the position with respect to the positive electrode body, and the variation of the measured value was calculated to be within 2% (the average thickness d of the positive electrode body The variation was ± 0.02 d). Furthermore, when the positive electrode body was placed on a flat surface and the radius of curvature of the positive electrode body was calculated, the positive electrode body had a curvature of radius R = 2 m. Further, the porosity of the structure obtained from the weight and volume of the polished positive electrode body was 8%, and the amount of LiCoO ₂ per 1 cm ² was 46 mg.

  Finally, a positive electrode current collector made of Al and having an average thickness of 0.1 μm was formed on one surface of the polished positive electrode body to prepare a positive electrode sample 1. Note that Al was formed by a vapor deposition method.

≪Positive electrode sample 2≫
The positive electrode body (after sintering and before polishing treatment) described in the column of the positive electrode sample 1 was impregnated with an ethanol solution in which 10 mol% of pentaethoxyniobium and lithium ethoxide were dissolved under reduced pressure (50 kPa). This positive electrode body was heated in the atmosphere at 400 ° C. for 1 hour so that LiNbO ₃ (lithium ion conductive composite oxide) was held in the voids of the positive electrode body. Then, the positive electrode body after the heat treatment is polished to a diameter of 15 mm × average thickness of 0.1 mm, and then the positive electrode current collector made of Al having an average thickness of 0.1 μm on one surface of the polished positive electrode body Was formed by vapor deposition method to obtain a positive electrode sample 2. The positive electrode body in the positive electrode sample 2 had a thickness variation of 2% or less, a surface roughness Ra of 0.03 μm, and a warp with a radius of 2 m. Further, the amount of LiCoO ₂ per 1 cm ^{2 of the} positive electrode sample 2 was 46 mg.

≪Positive electrode sample 3≫
A solution in which an equal weight of ethylene carbide and polyethylene oxide (PEO) in which 5 mol% of lithium perchlorate (LiClO ₄ ) is dissolved in the positive electrode body (after sintering and before polishing treatment) described in the column of the positive electrode sample 1 is mixed. Was impregnated under reduced pressure (50 kPa). This positive electrode body was heat-treated in argon at 45 ° C. for 1 hour so that PEO (lithium ion conductive polymer material) was held in the voids of the positive electrode body. Then, the positive electrode body after the heat treatment was polished to φ15 mm × thickness 0.1 mm, and then a positive electrode current collector made of Al having a thickness of 0.1 μm was deposited on one surface of the polished positive electrode body. The positive electrode sample 3 was obtained by forming by the phase evaporation method. The positive electrode body in the positive electrode sample 3 had a thickness variation of 2% or less, a surface roughness Ra of 0.02 μm, and a warp with a radius of 2 m. Further, the amount of LiCoO ₂ per 1 cm ^{2 of the} positive electrode sample 3 was 46 mg.

≪Positive electrode sample 101≫
A slurry was prepared by mixing LiCoO ₂ powder (8 parts by weight), polyvinylidene fluoride (1 part by weight), and N-methyl-2-pyrrolidone (10 parts by weight). And this slurry is apply | coated on Al foil ((phi) 15mm, average thickness 10micrometer), it is made to dry at 150 degreeC x 2 hours, and the positive electrode sample 101 which has a positive electrode collector layer whose final average thickness is 90 micrometers is obtained. It was. The amount of LiCoO ₂ per 1 cm ^{2 of} this positive electrode sample 101 was 25 mg. In the positive electrode sample 101, an Al foil serves as a positive electrode current collector.

≪Positive electrode sample 102≫
On a stainless foil base material (positive electrode current collector) having an average thickness of 20 μm, a thin film having an average thickness of 10 μm made of LiCoO ₂ was formed by an electron beam evaporation method, and a positive electrode sample 102 was obtained. The electron beam evaporation method was performed in an oxygen atmosphere of 1 to 10 Pa with a base material temperature of 500 ° C. The amount of LiCoO ₂ per 1 cm ^{2 of} this positive electrode sample 102 was 5 mg. In addition, when the average thickness of the thin film was more than 10 μm, the stress accumulated in the thin film increased, and it was very easy to peel off from the stainless steel foil.

≪Positive electrode sample 103≫
Lithium hydroxide (LiOH) and cobalt acetate (Co (CH ₃ COO) ₂ ) were mixed in equimolar amounts, poured into distilled water, mixed and stirred, and then dried to obtain a precursor powder. This precursor powder was pressed into a pellet with a diameter of 20 mm and an average thickness of 1 mm by applying a pressure of 80 MPa with a cold isostatic pressing device, and calcined at 900 ° C. for 5 hours and calcined at 950 ° C. for 3 hours. And a positive electrode body made of LiCoO ₂ was obtained.

Next, after the shape processing of the obtained positive electrode body, the surface is polished so that the variation in the thickness of the positive electrode body is small and the radius of warpage is large, and the final size is φ15 mm × average thickness of 0.1 mm. It was 1 mm. The polished positive electrode body had a warp with a surface roughness Ra of 0.2 μm, a thickness variation of 2% or less, and a radius R of 2 m. Moreover, the porosity of the structure determined from the weight and volume of the polished positive electrode body was 20%, and the amount of LiCoO ₂ per 1 cm ² was 40 mg. Since this positive electrode sample 103 had a high porosity, it was necessary to handle it carefully so as not to cause cracks.

  Finally, a positive electrode current collector made of Al and having an average thickness of 0.1 μm was formed on one surface of the polished positive electrode body by vapor deposition.

<Preparation of nonaqueous electrolyte battery and evaluation of battery performance>
A plurality of nonaqueous electrolyte batteries (batteries A to I) using the above-described positive electrode samples 1 to 101 and 101 to 103 were produced. Table 1 shows the configuration of each layer in the nonaqueous electrolyte battery.

<< Manufacturing conditions for the configuration of FIG. 1 >>
The batteries B, C, D, E, G, H, and I having the configuration of FIG. 1 have the positive electrode 1 as a base material, a buffer layer 41 (no batteries E and H are provided) on the positive electrode 1, and lithium ion conduction. The layer 31 and the negative electrode 2 were formed in this order by vapor deposition. The formation method of each structure is explained in full detail below.

The buffer layer 41 made of LiNbO ₃ was formed by excimer laser ablation using the positive electrode 1 as a base material. The average thickness of the buffer layer 41 was 10 nm. The buffer layer 41 was deposited under an oxygen atmosphere with an evaporation source output of 500 mJ and a pressure of 1 Pa. After deposition, oxygen annealing was performed in an atmospheric furnace at 400 ° C. for 0.5 hour. By performing oxygen annealing, LiNbO ₃ constituting the buffer layer 41 was diffused into the positive electrode active material layer 11.

When the lithium ion conductive layer 31 is Li ₂ S + P ₂ S ₅ , the layer 31 is an excimer laser that targets lithium sulfide (Li ₂ S) and phosphorus pentasulfide (P ₂ S ₅ ) in an Ar atmosphere of 1 Pa. It was formed by the ablation method. Further, when the lithium ion conductive layer 31 is Li—P—O—N, the layer 31 is formed by a high frequency magnetron sputtering method using LiPO ₄ as a target in an N ₂ atmosphere of 1 Pa.

The negative electrode active material layer 21 made of Li was formed by a resistance heating method under a vacuum of 10 ⁻⁴ Pa or less. Since this negative electrode active material layer 21 also serves as a current collector, the negative electrode current collector 22 in FIG. 1 is omitted in this embodiment.

<< Manufacturing conditions for the configuration of FIG. 2 >>
The batteries A and F having the configuration of FIG. 2 are formed by preparing a negative electrode 2 made of Li foil with an average thickness of 100 μm separately from the positive electrode 1 and sandwiching a lithium ion conductive layer 32 between the positive electrode 1 and the negative electrode 2. did.

As the lithium ion conductive layer 32, a mixed porous body of polyethylene and polypropylene (trade name: Celgard) was used. As the electrolytic solution, a non-aqueous organic electrolytic solution in which LiPF ₆ was dissolved in a solvent in which ethylene carbonate: diethyl carbonate was mixed at a volume ratio of 3: 7 was used.

<Battery performance evaluation>
Regarding the batteries A to I described above, the discharge capacity (mAh / cm ² ) when charged to 4.2 V with a constant current of 0.05 mA and discharged at 3 V was measured. Also, the internal resistance of the battery was determined from the voltage drop at the start of discharge. The results are shown in Table 2. In Table 2, the structure of each layer of the battery is also shown.

  From the results in Table 2, the following became clear.

  First, when a battery of almost the same size is manufactured by comparing the battery A and the battery F, which are electrolyte type batteries shown in FIG. 2, the battery A using the positive electrode body (positive electrode sample 1) The discharge capacity was larger than that of the battery F (using the positive electrode sample 101) in which the positive electrode active material layer was formed by a coating method using the body as a base material. The reason is that the amount of active material per unit volume in the positive electrode active material layer (positive electrode body) of the positive electrode sample 1 composed of a sintered body is the unit volume in the positive electrode active material layer of the positive electrode sample 101 formed by a coating method. This is because the amount of active material per unit is larger. Further, the thickness of the positive electrode current collector in the batteries A and F is also a cause of the discharge capacity of the battery A being larger than that of the battery F. In the positive electrode sample 1, since the positive electrode current collector can be formed by a vapor deposition method using the positive electrode body as a base material, the thickness of the current collector in the battery is thin. On the other hand, in the positive electrode sample 101, since the positive electrode active material layer is formed on the foil serving as a current collector by a coating method, a foil having a certain thickness must be used. The thickness of the current collector is increased.

  Next, batteries B, C, and D, which are batteries of the solid electrolyte type (sulfide-based solid electrolyte) shown in FIG. Batteries B, C, and D using the positive electrode body (positive electrode samples 1, 2, and 3) have a larger amount of positive electrode active material than the battery G (using the positive electrode sample 102). Had. This is because the positive electrode active material layer of the positive electrode sample 102 is formed by a vapor deposition method in which it is difficult to form a thin film having a thickness of more than 10 μm, and thus the thickness has to be 10 μm. Although it is actually difficult, even if the thickness of the positive electrode active material layer of the battery G can be set to 100 μm by vapor deposition, the current collector of the battery G is thicker than those of the batteries B, C, D. If the discharge capacities per unit volume are compared, the batteries B, C, and D are higher than the battery G.

  Further, looking at the relationship between the battery E and the battery H using an oxide as a solid electrolyte, the same tendency as the relationship between the batteries B, C, D and the battery G was recognized.

  Further, by comparing the battery B (using the positive electrode sample 1) and the battery I (using the positive electrode sample 103), in the battery using the solid electrolyte, the battery I having a high porosity of the positive electrode body has the porosity of the positive electrode body. It was revealed that the discharge capacity was smaller than that of the battery B having a low value and the internal resistance was high. Similarly, even in a battery using a positive electrode body, when the lithium ion conductive layer is a solid electrolyte, it has been found that the influence of the porosity of the positive electrode body on the internal resistance of the battery is large.

  In Example 2, the performance of the electrode body (positive electrode sample 4) in which the warpage was not adjusted strictly was examined.

<Positive electrode sample 4>
A sintered body (positive electrode body) having a diameter of 20 mm and an average thickness of 1 mm was obtained by the same method as that of the positive electrode sample 1 of Example 1, and the surface was polished to have a final size of 15 mm × 0.2 μm. . And the positive electrode electrical power collector was formed in the one surface of the positive electrode body by the vapor deposition method, and the positive electrode sample 4 was produced. Here, the degree of parallelism between the sintered body and the polishing plate was not strictly specified during polishing. Positive sample 1 after polishing, 8% porosity, 46 mg is LiCoO ₂ per 1 cm ^2, the surface roughness Ra is 0.03 .mu.m, with variations in the thickness of 6% has a warping of the radius R = 1 m It was.

  When the other layer (solid electrolyte layer or negative electrode layer) of the battery is formed on the positive electrode sample 4, if the treatment is performed such that pressure is applied to the positive electrode sample 4, the positive electrode sample 4 may be cracked. It was. The treatment for applying pressure is, for example, a case where a solid electrolyte layer is formed by a solid phase method such as pressing the positive electrode sample 4 and electrolyte powder into a mold. It is assumed that the damage such as cracking occurs in the positive electrode sample 4 because the thickness variation of the positive electrode sample 4 is large and the radius of warpage is small. However, if the other layer is formed by a vapor phase method, the positive electrode sample 4 does not have a defect such as a crack, and has a discharge capacity equivalent to that of the battery B shown in Example 1 and a battery with a small internal resistance. became.

  The above-described embodiments can be modified as appropriate without departing from the gist of the present invention. For example, the negative electrode active material layer may be formed of a sintered body, and the negative electrode current collector may be formed on the sintered body by a vapor deposition method. Also in this case, it goes without saying that the thickness of the negative electrode current collector in the battery can be made thinner than when the negative electrode active material layer is formed using the negative electrode current collector as a substrate.

  The nonaqueous electrolyte battery of the present invention can be suitably used as a power source for portable devices and the like.

DESCRIPTION OF SYMBOLS 100,200 Nonaqueous electrolyte battery 1 Positive electrode 11 Positive electrode active material layer 12 Positive electrode collector 2 Negative electrode 21 Negative electrode active material layer 22 Negative electrode collector 31,32 Lithium ion conductive layer 41 Buffer layer

Claims (6)

An electrode body used as a positive electrode active material layer or a negative electrode active material layer of a nonaqueous electrolyte battery,
An electrode body having an average thickness d of 0.05 mm to 0.3 mm and a porosity of 15% by volume or less.   2. The electrode body according to claim 1, wherein the variation in thickness with respect to the average thickness of the electrode body is ± 0.05 d or less, and the warpage of the electrode body is a warp having a radius of 1.5 m or more. A non-aqueous electrolyte battery comprising a positive electrode, a negative electrode, and a lithium ion conductive layer that mediates conduction of lithium ions between the two electrodes,
At least one of the positive electrode and the negative electrode is
An electrode body according to claim 1 or 2,
It consists of a metal thin film provided on one surface of this electrode body,
The metal thin film has an average thickness of 0.01 μm to 30 μm.   The non-aqueous electrolyte battery according to claim 3, wherein the lithium ion conductive layer is made of a polymer resin containing lithium. The other surface of the electrode body has an arithmetic average roughness Ra (JIS B060001) of 0.1 μm or less,
4. The nonaqueous electrolyte battery according to claim 3, wherein a lithium ion conductive layer made of a solid electrolyte is formed on the other surface. Preparing the electrode body according to claim 1 or 2,
And a step of forming a metal thin film having an average thickness of 0.01 to 30 μm on one surface of the electrode body by a vapor phase method.

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