JPWO2016068258A1 - Positive electrode and non-aqueous electrolyte battery - Google Patents

Abstract

According to one embodiment, a positive electrode is provided. The positive electrode includes a positive electrode current collector and a positive electrode layer formed on the positive electrode current collector. The positive electrode layer includes a positive electrode active material, a conductive additive, and a binder. The positive electrode layer includes a plurality of regions having a resistance value of 1 GΩ or less. The proportion of the plurality of regions in the positive electrode layer is 4% or more and 20% or less. The average area of the plurality of regions included in the mapping image obtained by scanning probe microscope observation of the positive electrode layer is greater than 0 μm 2 and less than 0.2 μm 2.

Description

  Embodiments described herein relate generally to a positive electrode and a nonaqueous electrolyte battery.

  With the increase in energy density and capacity of batteries, there is a need to reduce the number of auxiliary members such as conductive additives or increase the density of electrodes. However, when the amount of the conductive additive is reduced, it is expected that battery performance such as output characteristics and cycle characteristics may be deteriorated if no measures are taken. One reason for this is that if the amount of the conductive additive in the electrode is small, the dispersed state of the conductive additive in the electrode may be non-uniform. If the dispersion state of the conductive auxiliary agent in the electrode is not uniform, a portion where the conductive network in the electrode is absent appears, and as a result, the active material used during charging and discharging may be biased. When the utilization rate of the active material is biased, the burden on the active material having a high charge / discharge frequency is increased, which becomes a factor of accelerating the deterioration of the battery when repeatedly used. In addition, when the number of places where the conductive network is lacking increases, it is expected that the overvoltage increases when a large current is discharged, resulting in a decrease in output characteristics. As described above, increasing the energy density of the electrode by reducing the amount of the conductive additive in the electrode can lead to non-uniform dispersion of the conductive additive in the electrode, and thus other battery characteristics such as input / output characteristics. And a trade-off relationship with cycle characteristics.

  A measure for eliminating such a trade-off relationship, that is, a measure for reducing the amount of the conductive aid while ensuring the battery performance, is to uniformly disperse the active material and the conductive aid in the electrode. .

JP 2011-192620 A JP 2011-146284 A JP2012-243415A JP2011-238461A

  An object of the present invention is to provide a positive electrode capable of realizing a non-aqueous electrolyte battery capable of exhibiting high energy density, excellent input / output characteristics, and excellent cycle characteristics, and such a non-aqueous electrolyte battery.

According to a first embodiment, a positive electrode is provided. The positive electrode includes a positive electrode current collector and a positive electrode layer formed on the positive electrode current collector. The positive electrode layer includes a positive electrode active material, a conductive additive, and a binder. The positive electrode layer includes a plurality of regions having a resistance value of 1 GΩ or less. The ratio of the plurality of regions having a resistance value of 1 GΩ or less to the positive electrode layer is 4% or more and 20% or less. The average area of the plurality of areas the resistance value included in the mapping image obtained by scanning probe microscopy of the positive electrode layer is not more than 1GΩ is a large 0.2μm less than ² than 0 .mu.m ^2.

  According to the second embodiment, a nonaqueous electrolyte battery is provided. The nonaqueous electrolyte battery includes a positive electrode according to the first embodiment, a negative electrode, and a nonaqueous electrolyte.

According to a third embodiment, a positive electrode is provided. The positive electrode includes a positive electrode current collector and a positive electrode layer formed on the positive electrode current collector. The positive electrode layer includes a positive electrode active material, a conductive additive, and a binder. The positive electrode layer includes a plurality of regions having a resistance value of 1 GΩ or less. The volume ratio of the plurality of regions having a resistance value of 1 GΩ or less in the positive electrode layer is 4% or more and 20% or less. The average area of each of the plurality of areas the resistance value included in the mapping image obtained by scanning probe microscopy is below 1GΩ the positive electrode layer, a large 0.2μm less than ² than 0 .mu.m ^2.

FIG. 1 is an example of a mapping image obtained by observation with a scanning probe microscope about the positive electrode layer of the positive electrode of the example according to the first embodiment. FIG. 2 is a schematic cross-sectional view of an example positive electrode according to the first embodiment. FIG. 3 is a partially cutaway schematic perspective view of an example nonaqueous electrolyte battery according to the second embodiment. 4 is an enlarged cross-sectional view of part A of the nonaqueous electrolyte battery of FIG. FIG. 5 is a partially cutaway perspective view of a non-aqueous electrolyte battery of a second example according to the second embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. In addition, the same code | symbol shall be attached | subjected to a common structure through embodiment and the overlapping description is abbreviate | omitted. Each figure is a schematic diagram for promoting explanation and understanding of the embodiment, and its shape, dimensions, ratio, etc. are different from the actual device, but these are the following explanations and known techniques. The design can be changed as appropriate.

[First Embodiment]
According to a first embodiment, a positive electrode is provided. The positive electrode includes a positive electrode current collector and a positive electrode layer formed on the positive electrode current collector. The positive electrode layer includes a positive electrode active material, a conductive additive, and a binder. The positive electrode layer includes a plurality of regions having a resistance value of 1 GΩ or less. The ratio of the plurality of regions having a resistance value of 1 GΩ or less to the positive electrode layer is 4% or more and 20% or less. The average area of the plurality of areas the resistance value included in the mapping image obtained by scanning probe microscopy of the positive electrode layer is not more than 1GΩ is a large 0.2μm less than ² than 0 .mu.m ^2.

  As described above, as a means for increasing the energy density by reducing the amount of the conductive assistant while maintaining good battery characteristics, it is possible to uniformly disperse the active material and the conductive assistant. Examples of such a dispersion method include an example using an apparatus such as a roll mill or an ultrasonic dispersion. Conventionally, in order to determine the dispersion state of the constituent materials in the electrode, an observation using a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDX) is used. (SEM-EDX) has been widely used.

  When the cross section of the electrode actually produced using an apparatus such as a roll mill or ultrasonic dispersion is observed with SEM-EDX and image analysis is performed, it can be confirmed that the conductive auxiliary agent is uniformly dispersed. . However, even in a battery using a positive electrode in which the conductive additive is in such a state, poor output characteristics and cycle characteristics may be confirmed as a result of evaluation of battery characteristics.

As a result of intensive studies, the inventors have found that such a result is that the dispersion state of the conductive additive is judged by the SEM-EDX observation result. Specifically, it is as follows.
Since the mapping analysis based on the SEM-EDX observation result can identify each element, it is possible to determine the conductive auxiliary agent present in the electrode cross section. However, since the SEM-EDX observation is a surface analysis, it is difficult to determine whether or not the conductive auxiliary agent in the electrode forms a conductive network, and the conductive auxiliary agent that is electrically isolated and does not participate in charge / discharge Are also included in the component forming the conductive network in the electrode. Therefore, at first glance from the results obtained from the SEM image, the nonaqueous electrolyte battery using the electrode in which the conductive auxiliary agent is uniformly dispersed may include batteries having poor battery characteristics such as output characteristics and cycle characteristics. From these considerations, in order to determine whether the electrode is an electrode capable of realizing a nonaqueous electrolyte battery having excellent battery characteristics, the conductive assistant that forms a conductive network in a dispersed state is used. Only found that it is necessary to identify. The inventors realized the positive electrode according to the first embodiment, starting from this discovery.

The positive electrode according to the first embodiment includes a plurality of regions in which the positive electrode layer has a resistance value of 1 GΩ or less. The proportion of the plurality of regions in the positive electrode layer is 4% or more and 20% or less. The average area of the plurality of areas the resistance value included in the mapping image obtained by scanning probe microscopy of the positive electrode layer is not more than 1GΩ is a large 0.2μm less than ² than 0 .mu.m ^2. In the positive electrode according to the first embodiment, the positive electrode layer can contain a sufficient amount of a conductive additive, and the conductive additive that forms a conductive network in the positive electrode layer is uniformly dispersed in the positive electrode layer. Yes. Thanks to this, the positive electrode according to the first embodiment can realize a non-aqueous electrolyte battery that can exhibit high energy density, excellent input / output characteristics, and excellent cycle characteristics. The reason will be described in detail below.

  The ratio of the plurality of regions having a resistance value of 1 GΩ or less to the positive electrode layer and the average area of the plurality of regions having a resistance value of 1 GΩ or less included in the mapping image obtained by scanning probe microscopy of the positive electrode layer are: It can calculate from the observation result by the scanning probe microscope (Scanning Probe Microscopy: SPM) demonstrated below.

  In the observation of the positive electrode by SPM, a bias voltage is applied using the positive electrode as a sample, the current flowing through the conductive probe is measured by a wide range logarithmic amplifier, and a resistance distribution is obtained. Thereby, it is possible to know the ratio, specifically the area ratio, of the plurality of regions having a resistance value of 1 GΩ or less in the positive electrode layer. The positive electrode layer in which a plurality of regions having a resistance value of 1 GΩ or less occupy 4% or more and 20% or less can contain the conductive additive without excess or deficiency. When the ratio of the plurality of regions having a resistance value of 1 GΩ or less is less than 4%, the amount of the conductive auxiliary agent that forms the conductive network is insufficient in the positive electrode layer, and the conductive network is likely to be lacking in the positive electrode layer. In a non-aqueous electrolyte battery using such a positive electrode, an uneven utilization rate of the active material in the positive electrode and an increase in overvoltage occur, and the battery characteristics deteriorate. On the other hand, when the ratio of the plurality of regions having a resistance value of 1 GΩ or less is larger than 20%, the conductive additive in the positive electrode layer becomes excessive, and the energy density is lowered. The proportion of the plurality of regions having a resistance value of 1 GΩ or less in the positive electrode layer is preferably 10% or more and 15% or less.

In addition, even in the case of a positive electrode including a positive electrode layer in which a plurality of regions having a resistance value of 1 GΩ or less occupy 4% or more and 20% or less, the resistance value included in the mapping image obtained by the scanning probe microscope observation of the positive electrode layer A non-aqueous electrolyte battery using a positive electrode having an average area of 0 μm ² in a plurality of regions having an area of 1 GΩ or less, or a positive electrode having an average area of 0.2 μm ² or more in the plurality of regions is excellent for the following reasons. Battery characteristics cannot be exhibited.

  First, the average area of a plurality of regions having a resistance value of 1 GΩ or less included in a mapping image obtained by observation of the positive electrode layer with a scanning probe microscope is an indicator of the state of dispersion of the conductive additive in the positive electrode layer.

  According to the observation of the positive electrode layer by SPM, it is possible to examine the distribution of the conductive additive forming the conductive network in the positive electrode layer. Specifically, in the mapping image obtained by SPM observation of the positive electrode layer, the resistance value of the region of the conductive additive forming the conductive network is 1 GΩ or less. On the other hand, the region of the conductive assistant that is isolated without forming a conductive network has a resistance value greater than 1 GΩ. Therefore, according to the observation of the positive electrode by SPM, the conductive auxiliary agent forming the conductive network can be distinguished from the isolated conductive auxiliary agent.

A plurality of regions having a resistance value of 1 GΩ or less occupy 4% or more and 20% or less, and an average area of a plurality of regions having a resistance value of 1 GΩ or less included in the mapping image obtained by scanning probe microscope observation of the positive electrode layer In the positive electrode in which is larger than 0 μm ^{2 and} smaller than 0.2 μm ² , the conductive auxiliary forming the conductive network is present in the vicinity of the positive electrode active material with a high probability. Thanks to this, the positive electrode according to the first embodiment can have a conductive network that can sufficiently participate in the positive electrode active material in the positive electrode layer. On the other hand, a positive electrode in which the average area of a plurality of regions having a resistance value of 1 GΩ or less included in the mapping image is 0 μm ^{2 is} in a state where the conductive additive is not included in the positive electrode, and thus cannot function as a battery. . In addition, in the positive electrode in which the average area of a plurality of regions having a resistance value of 1 GΩ or less included in the mapping image is 0.2 μm ² or more, aggregation of the conductive auxiliary agent occurs, and the conductivity present in the vicinity of the positive electrode active material. There is a shortage of auxiliaries. Therefore, such a positive electrode cannot have a conductive network that can sufficiently participate in the positive electrode active material in the positive electrode layer. As a result, the nonaqueous electrolyte battery including this positive electrode exhibits poor battery characteristics. The average area of the plurality of regions having a resistance value of 1 GΩ or less included in the mapping image obtained by the scanning probe microscope observation of the positive electrode layer is preferably larger than 0 μm ^{2 and} smaller than 0.09 μm ² , more preferably 0.8. area resistance value is less 1GΩ in 02Myuemu ² or 0.09 .mu.m ² or less is the positive electrode layer, a conductive auxiliary agent which forms a conductive network can be referred to as a region that contains sufficient. This region can exhibit a resistance of 10 mΩ or more, for example. On the other hand, it can be inferred that the region having a resistance value of less than 10 mΩ is a metal piece impurity derived from, for example, a current collector foil. In addition, the region where the resistance value is larger than 1 GΩ is a region that does not contain the conductive auxiliary agent forming the conductive network sufficiently or does not contain at all, for example, a region made of a positive electrode active material and / or a binder. It can be said that there is.

  Next, an example of the mapping image of the positive electrode layer of the positive electrode according to the first embodiment will be described.

  The mapping image of the positive electrode layer can be obtained by the following procedure. First, the nonaqueous electrolyte battery is decomposed in a glove box filled with argon, and the positive electrode to be measured is taken out from the nonaqueous electrolyte battery. Next, the taken out positive electrode is washed with methyl ethyl carbonate (MEC). Next, the cleaned positive electrode is dried under an atmosphere of 100 ° C. and a gauge pressure of −75 kPa. The dried positive electrode is cut into a thickness of 1 μm to 100 μm, a width of 0.5 cm to 1.5 cm, and a height of 1.5 to 2.5 cm to obtain a measurement sample.

  The measurement sample thus prepared is observed with a scanning probe microscope measuring apparatus. E-sweep manufactured by Hitachi High-Tech Science Co., Ltd. (formerly SII Nanotechnology) is used as the measuring device. The measurement sample and the holder are connected by screwing the portion of the positive electrode current collector of the measurement sample where the positive electrode layer is not formed on the surface to the holder as it is. The measurement conditions are an applied voltage of 0.2 to 0.5 V and a protective resistance of 10 MΩ. A probe having a tip diameter of 20 nm is used.

  By the measurement, for example, a mapping image shown in FIG. 1 can be obtained. In the mapping image shown in FIG. 1, a white portion 3c indicates a region having a resistance value of 1 GΩ or less.

  Next, the current image thus obtained is divided into a plurality of pixels and binarized. The threshold value for the binarization process is 1 GΩ. For example, it can be 20% higher than the maximum noise value measured in advance. A pixel consisting of 0 and 1 is created with 1 being the pixel below the threshold and 0 being the pixel exceeding the threshold. From the matrix thus obtained, a region having a resistance value of 1 GΩ or less is confirmed as shown in the following example.

  Tables 1 and 2 below show analysis examples of current images of 3 vertical pixels × 3 horizontal pixels.

  A region having a resistance value of 1 GΩ or less is defined as a set of “1” pixels surrounded by “0” pixels in a matrix. For example, in the matrix shown in Table 1, there is one “1” pixel, and all the pixels adjacent to this pixel are “0”. Therefore, in the matrix shown in Table 1, there is one region where the resistance value is 1 GΩ or less. On the other hand, in the matrix shown in Table 2, there are three “1” pixels. Among them, two “1” pixels located at the upper left of the matrix are adjacent to each other. These two “1” pixels are surrounded by “0” pixels. Therefore, the number of regions in which the resistance value represented by these pixels is 1 GΩ or less is regarded as one. On the other hand, all the pixels adjacent to one “1” pixel located below are “0”. Therefore, the number of regions in which the resistance value indicated by the one “1” pixel located below is 1 GΩ or less is regarded as one. That is, in the matrix shown in Table 2, there are two regions having a resistance value of 1 GΩ or less. By applying such a method to the entire field of view of the current image obtained, the area of a plurality of regions that are 1 GΩ or less in the obtained field of view and the number of regions that are 1 GΩ or less included in the obtained field of view are obtained. I can know.

Specifically, the average area of a plurality of regions having a resistance value of 1 GΩ or less included in the mapping image can be obtained as follows. 30 fields of 3000 μm ² are selected from the positive electrode layer, and mapping images corresponding to these fields, that is, current images, are analyzed as described above. The average area of the plurality of regions having a resistance value of 1 GΩ or less is obtained by dividing the total area of the plurality of regions having a resistance value of 1 GΩ or less by the number of the plurality of regions having a resistance value of 1 GΩ or less. And

  Next, the positive electrode according to the first embodiment will be described in more detail.

The positive electrode according to the first embodiment includes a positive electrode current collector.
As the positive electrode current collector, a sheet containing a material having high electrical conductivity can be used. For example, an aluminum foil or an aluminum alloy foil can be used as the positive electrode current collector. When using aluminum foil or aluminum alloy foil, the thickness is 20 micrometers or less, for example, Preferably it is 15 micrometers or less. The aluminum alloy foil can include magnesium, zinc, silicon and the like. Moreover, it is preferable that content of transition metals, such as iron, copper, nickel, and chromium contained in aluminum alloy foil, is 1% or less.

  The positive electrode according to the first embodiment further includes a positive electrode layer formed on the positive electrode current collector. The positive electrode layer may be formed on one side of the positive electrode current collector, or may be formed on both sides. The positive electrode current collector can also include a portion that does not carry the positive electrode layer on the surface. This portion can also serve as, for example, a positive electrode current collecting tab. Or the positive electrode which concerns on 1st Embodiment can also contain the positive electrode current collection tab separate from a positive electrode current collector.

The positive electrode layer includes a positive electrode active material, a conductive additive, and a binder.
The positive electrode active material is not particularly limited. Examples of the positive electrode active material, nickel-cobalt-manganese composite oxide _{(e.g., Li a Ni 1-xy Co} x Mn y O 2 ( subscripts x and y, 0 <x ≦ 0.30 and 0 <y ≦ 0. 45, 0.9 ≦ a ≦ 1.25)), lithium manganese composite oxide (eg LiMn ₂ O ₄ or LiMnO ₂ ), lithium nickel composite oxide (eg LiNiO ₂ ), lithium cobalt composite oxide (LiCoO ₂ ), lithium nickel cobalt composite oxide (for example, LiNi _1-x Co _x O ₂ , 0 <x ≦ 1), lithium manganese cobalt composite oxide (for example, LiMn _x Co _1-x O ₂ , 0 <x ≦ 1), lithium iron phosphate (for example, LiFePO ₄ ), and lithium composite phosphate compound (for example, LiMn _x Fe _1-x PO ₄ , 0 <x ≦ 1).

  The conductive aid preferably contains at least one selected from the group consisting of carbon black, carbon nanotubes, carbon nanofibers, and graphite.

  The binder is used to bond the positive electrode active material and the positive electrode current collector. Examples of binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine rubber, styrene-butadiene rubber (SBR), polypropylene (PP), polyethylene (PE), and acrylic copolymer as the main component. And binder and carboxymethylcellulose (CMC).

  The proportions of the positive electrode active material, conductive additive and binder contained in the positive electrode layer are preferably 80 to 95% by weight, 3 to 20% by weight and 2 to 7% by weight, respectively.

  The positive electrode according to the first embodiment can be obtained, for example, by a method described in each example shown below. In particular, the ratio of the plurality of regions having a resistance value of 1 GΩ or less to the positive electrode layer, and the average area of the plurality of regions having a resistance value of 1 GΩ or less included in the mapping image obtained by the scanning probe microscope observation of the positive electrode layer are as follows: For example, it depends on the dispersion state of the conductive additive in the positive electrode layer and the type of conductive additive. Therefore, these parameters are greatly influenced by, for example, the selection of the conductive additive and the dispersion condition of the positive electrode paint for forming the positive electrode layer. For example, as described in Examples, the positive electrode according to the first embodiment can be manufactured by adjusting these conditions that can be changed in a complex manner.

  In each of the following examples, specifically, a positive electrode paint for forming a positive electrode layer was prepared by the following procedure. First, the positive electrode active material was dispersed together with a binder to prepare a solution A. Separately from the solution A, a conductive additive was dispersed together with a binder to prepare a solution B. Next, the solution A and the solution B prepared as described above were mixed to prepare a mixed solution. Next, this mixed solution was processed with a roll mill to prepare a paste-like positive electrode paint.

  The reason why the solution A containing the positive electrode active material and the solution B containing the conductive additive are separately dispersed, that is, the pre-dispersed solution is prepared will be described below.

  When a positive electrode active material having a large particle size and a large amount and a conductive assistant having a small particle size and a small amount compared to the positive electrode active material are dispersed together with a binder, the large volume active material has a small volume of the conductive material. Inhibits dispersion of auxiliaries. On the other hand, when the conductive additive is dispersed together with the binder before mixing with the positive electrode active material, it is possible to reduce the factor that inhibits the dispersion of the conductive aid. Therefore, the solution B obtained by the prior dispersion of the conductive assistant is excellent in the dispersion state of the conductive assistant. By further dispersing the pre-dispersion solution B, which is excellent in the dispersion state of the conductive auxiliary agent, together with the solution A containing the positive electrode active material, a positive electrode paste excellent in the dispersion of the conductive auxiliary agent can be prepared.

Next, an example of the positive electrode according to the first embodiment will be described with reference to the drawings.
FIG. 2 is a schematic cross-sectional view of an example positive electrode according to the first embodiment.
A positive electrode 3 shown in FIG. 2 includes a strip-shaped positive electrode current collector 3a. The positive electrode 3 further includes a positive electrode layer 3b formed on both surfaces of a strip-shaped positive electrode current collector 3a.

The positive electrode according to the first embodiment includes a plurality of regions in which the positive electrode layer has a resistance value of 1 GΩ or less. The proportion of this region in the positive electrode layer is 4% or more and 20% or less. The average area of the plurality of areas the resistance value is less 1GΩ included in the mapping image obtained by scanning probe microscopy of the positive electrode layer is larger 0.2μm less than ² than 0 .mu.m ^2. Thanks to this, the positive electrode according to the first embodiment can include a sufficient amount of a plurality of regions having a resistance value of 1 GΩ or less in the positive electrode layer in a sufficiently dispersed state. As a result, the positive electrode according to the first embodiment can realize a nonaqueous electrolyte battery that can exhibit high energy density, excellent input / output characteristics, and excellent cycle characteristics.

[Second Embodiment]
According to the second embodiment, a nonaqueous electrolyte battery is provided. The nonaqueous electrolyte battery includes a positive electrode according to the first embodiment, a negative electrode, and a nonaqueous electrolyte.

  Next, the nonaqueous electrolyte battery according to the second embodiment will be described in more detail.

  The nonaqueous electrolyte battery according to the second embodiment includes the positive electrode according to the first embodiment.

The nonaqueous electrolyte battery according to the second embodiment further includes a negative electrode.
The negative electrode can include a negative electrode current collector and a negative electrode layer provided on the negative electrode current collector.

  The negative electrode layer may be provided on any one surface of the negative electrode current collector, or may be provided on both surfaces thereof.

  The negative electrode layer can include a negative electrode active material, a conductive additive, and a binder.

  The negative electrode current collector can also include a portion that does not carry the negative electrode layer on the surface. This portion can also serve as a negative electrode current collecting tab, for example. Alternatively, the negative electrode can include a negative electrode current collector tab that is separate from the negative electrode current collector.

  For example, the negative electrode is prepared by suspending a negative electrode active material, a binder, and a conductive additive in a suitable solvent to prepare a negative electrode paint, applying the paint on the surface of the negative electrode current collector, and drying to form a negative electrode layer. It can be produced by applying a press.

  The positive electrode and the negative electrode can be arranged such that the positive electrode layer and the negative electrode layer face each other to constitute an electrode group. Between the positive electrode layer and the negative electrode layer, a member that transmits lithium ions but does not conduct electricity, such as a separator, can be disposed.

  The electrode group can have various structures. The electrode group may have a stacked structure or a wound structure. The stack type structure has, for example, a structure in which a plurality of negative electrodes and a plurality of positive electrodes are stacked with a separator interposed between the negative electrode and the positive electrode. The electrode group having a wound structure may be, for example, a can-type structure in which a negative electrode and a positive electrode are laminated with a separator interposed therebetween, or by pressing the can-type structure. The resulting flat structure may be used.

  The positive electrode current collecting tab can be electrically connected to the positive electrode terminal. Similarly, the negative electrode current collecting tab can be electrically connected to the negative electrode terminal. The positive electrode terminal and the negative electrode terminal can extend from the electrode group.

  The electrode group can be housed in the exterior member. The exterior member may have a structure that allows the positive electrode terminal and the negative electrode terminal to extend outward. Alternatively, the exterior member may include two external terminals, each of which is electrically connected to each of the positive terminal and the negative terminal. Alternatively, the exterior member itself can serve as either a positive terminal or a negative terminal.

  The nonaqueous electrolyte battery according to the second embodiment further includes a nonaqueous electrolyte. The non-aqueous electrolyte can be impregnated in the electrode group. The nonaqueous electrolyte can be stored in the exterior member.

  Hereinafter, the material of each member that can be used in the nonaqueous electrolyte battery according to the second embodiment will be described.

1. Positive electrode As the material of the positive electrode, for example, those described in the first embodiment can be used.

2. Negative electrode As the negative electrode current collector, a sheet containing a material having high electrical conductivity and capable of suppressing corrosion in the working potential range of the negative electrode can be used. For example, an aluminum foil or an aluminum alloy foil can be used as the negative electrode current collector. When using aluminum foil or aluminum alloy foil, the thickness is 20 micrometers or less, for example, Preferably it is 15 micrometers or less. The aluminum alloy foil can include magnesium, zinc, silicon and the like. Moreover, it is preferable that content of transition metals, such as iron, copper, nickel, and chromium contained in aluminum alloy foil, is 1% or less.

The negative electrode active material can include one or more negative electrode active materials. As the negative electrode active material, for example, metals, metal alloys, metal oxides, metal sulfides, metal nitrides, graphite materials, carbonaceous materials, and the like can be used. Examples of the metal oxide include titanium-containing substances such as titanium oxide (for example, monoclinic titanium dioxide TiO ₂ (B)) and lithium titanium composite oxide (for example, titanic acid having a spinel crystal structure). Lithium (for example, Li _{4 + s} Ti ₅ O ₁₂ (s varies within the range of 0 ≦ s ≦ 3 depending on the state of charge)) and lithium titanate having a ramsdellite type crystal structure (for example, Li _{2 + l} Ti ₃ O ₇ (l changes within a range of −1 ≦ l ≦ 3 by charge / discharge reaction)) and niobium titanium composite oxide (for example, niobium titanium composite oxide having a monoclinic crystal structure (for example, Nb ₂ TiO ₇ )) can be used. Examples of the metal sulfide include titanium sulfide such as TiS ₂ , molybdenum sulfide such as MoS ₂ , and iron sulfide such as FeS, FeS ₂ , and LixFeS ₂ . Examples of the graphite material and the carbonaceous material include natural graphite, artificial graphite, coke, vapor grown carbon fiber, mesophase pitch carbon fiber, spherical carbon, and resin-fired carbon.

  As the conductive additive that can be included in the negative electrode layer, for example, a carbon material can be used. Examples of the carbon material include carbon black, coke, carbon fiber, and graphite.

  The binder is used to bond the negative electrode active material and the negative electrode current collector. As the binder that can be included in the negative electrode layer, the same binders that can be used in the positive electrode layer can be used.

  The negative electrode active material, the conductive additive and the binder contained in the negative electrode layer may be blended at a ratio of 70% by mass to 96% by mass, 2% by mass to 20% by mass and 2% by mass to 10% by mass, respectively. preferable. The current collection performance of the negative electrode layer can be improved by setting the amount of the conductive auxiliary to 2% by mass or more. Further, by setting the amount of the binder to 1% by mass or more, the binding property between the negative electrode layer and the negative electrode current collector can be improved, and excellent cycle characteristics can be expected. On the other hand, the conductive assistant and the binder are each preferably 16% by mass or less in order to increase the capacity.

3. Separator The separator is made of an insulating material and can prevent electrical contact between the positive electrode and the negative electrode. Preferably, the separator is made of a material through which the non-aqueous electrolyte can pass, or has a shape through which the non-aqueous electrolyte can pass. Examples of the separator are a porous film or a nonwoven fabric separator made of one or two kinds of polyethylene, polypropylene, polyethylene terephthalate, cellulose, and vinylon.

4). Nonaqueous Electrolyte The nonaqueous electrolyte can include, for example, a nonaqueous solvent, an electrolyte dissolved in the nonaqueous solvent, and optional additives.

  The non-aqueous solvent may be a known non-aqueous solvent used for non-aqueous electrolyte batteries. A first example of a non-aqueous solvent is a cyclic carbonate such as ethylene carbonate (EC) and propylene carbonate (PC). Second examples of non-aqueous solvents are linear carbonates such as dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate; gamma-butyrolactone, acetonitrile, methyl propionate, ethyl propionate; cyclic ethers such as tetrahydrofuran and 2-methyltetrahydrofuran; and dimethoxy Chain ethers such as ethane and diethoxyethane. The solvent of the second example generally has a lower viscosity than the solvent of the first example. The non-aqueous solvent may be a solvent obtained by mixing the solvent of the first example and the solvent of the second example.

The electrolyte is, for example, an alkali salt, preferably a lithium salt. The electrolyte preferably contains at least one lithium salt having an van der Waals ionic radius of an anion of 0.25 nm to 0.4 nm. Examples of such lithium salts are lithium hexafluorophosphate (LiPF ₆ ), lithium arsenic hexafluoride (LiAsF ₆ ), and lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ). Preferably, the electrolyte is lithium hexafluorophosphate (LiPF ₆ ). The concentration of the electrolyte in the nonaqueous electrolyte is preferably 0.5 to 2 mol / L.

The additive may be, for example, a sulfonyl group (R ¹ —S (═O) ₂ —R ² ), a sulfonamide group (R ¹ —SO ₂ —NR ² R ³ ), a sultone group (R ¹ —) in its molecular structure. S (═O) ₂ —OR ² ), a sulfate group (R ¹ O—SO ₂ —OR ² ), and a sulfite group (R ¹ O—SO—OR ² ). Examples of such additives include dimethyl sulfone (DMS), ethyl methyl sulfone (EMS), diphenyl sulfone (DPS), sulfolane (SL) as compounds having a sulfonyl group, and as compounds having a sulfonamide group, Lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), lithium bis (pentafluoroethanesulfonyl) imide (LiBETI), lithium trifluoromethanesulfonate (LiTFS), 1,2-ethanesultone (1,2) as a compound having a sultone group -ES), 1,3-propane sultone (1,3-PS), 1,4-butane sultone (1,4-BS), 1,5-pentane sultone (1,5-PS), 1,3-propene Sultone (1,3-PRS) and 1,4-butenesulfur Ton (1,4-BRS), dimethyl sulfate (DMSFA) as a compound having a sulfate ester group, dimethyl sulfite (DMSF), dipropyl sulfite (DPSF), ethylene sulfite (ESF) as a compound having a sulfite group It is. The concentration of the additive is preferably 0.5% by mass or more and 3.0% by mass or less.

5. Negative electrode current collecting tab, positive electrode current collecting tab, negative electrode terminal and positive electrode terminal It is preferable that the negative electrode current collecting tab, the positive electrode current collecting tab, the negative electrode terminal and the positive electrode terminal are formed of a material having high electrical conductivity. When connecting to a current collector, these members are preferably made of the same material as the current collector in order to reduce contact resistance.

6). Exterior Material As the exterior material, for example, a metal container or a laminate film container can be used, but it is not particularly limited.

  By using a metal container as the exterior material, a nonaqueous electrolyte battery excellent in impact resistance and long-term reliability can be realized. By using a laminate film container as the exterior material, it is possible to realize a non-aqueous electrolyte battery excellent in corrosion resistance and to reduce the weight of the non-aqueous electrolyte battery.

  For example, a metal container having a thickness in the range of 0.2 to 5 mm can be used. More preferably, the metal container has a thickness of 0.5 mm or less.

  The metal container preferably contains at least one selected from the group consisting of Fe, Ni, Cu, Sn, and Al. The metal container can be made of, for example, aluminum or an aluminum alloy. The aluminum alloy is preferably an alloy containing elements such as magnesium, zinc, and silicon. When the alloy contains a transition metal such as iron, copper, nickel, or chromium, the content is preferably 1% by weight or less. Thereby, long-term reliability and impact resistance in a high temperature environment can be dramatically improved.

For example, a laminate film container having a thickness in the range of 0.1 to 2 mm can be used. The thickness of the laminate film is more preferably 0.2 mm or less.
As the laminate film, a multilayer film including a metal layer and a resin layer sandwiching the metal layer is used. The metal layer preferably contains a metal including at least one selected from the group consisting of Fe, Ni, Cu, Sn, and Al. The metal layer is preferably an aluminum foil or an aluminum alloy foil for weight reduction. For the resin layer, for example, a polymer material such as polypropylene (PP), polyethylene (PE), nylon, polyethylene terephthalate (PET) can be used. The laminate film can be molded into the shape of an exterior material by sealing by heat sealing.

  Examples of the shape of the exterior material include a flat type (thin type), a square type, a cylindrical type, a coin type, and a button type. An exterior material can take various dimensions according to a use. For example, when the nonaqueous electrolyte battery according to the second embodiment is used for a portable electronic device, the exterior material can be made small in accordance with the size of the mounted electronic device. Alternatively, in the case of a non-aqueous electrolyte battery mounted on a two-wheel or four-wheel automobile, the container may be a large battery container.

  Next, an example of the nonaqueous electrolyte battery according to the second embodiment will be described in more detail with reference to the drawings.

  FIG. 3 is a partially cutaway perspective view of the first example nonaqueous electrolyte battery according to the second embodiment. 4 is an enlarged cross-sectional view of part A of the nonaqueous electrolyte battery shown in FIG.

  A nonaqueous electrolyte battery 100 shown in FIGS. 3 and 4 includes a flat electrode group 1.

  The flat electrode group 1 includes a negative electrode 2, a positive electrode 3, and a separator 4.

  As shown in FIG. 4, the negative electrode 2 includes a negative electrode current collector 2a and a negative electrode layer 2b carried on the negative electrode current collector 2a. As shown in FIG. 4, the positive electrode 3 includes a positive electrode current collector 3a and a positive electrode layer 3b supported on the positive electrode current collector 3a. That is, the positive electrode 3 has the same structure as the positive electrode of the example according to the first embodiment shown in FIG.

  In the electrode group 1, as shown in FIG. 4, the negative electrode 2 and the positive electrode 3 are laminated with the separator 4 interposed between the negative electrode layer 2b and the positive electrode layer 3b. Such an electrode group 1 can be obtained by the following procedure. First, one flat negative electrode 2 and one flat positive electrode 3 are laminated with a separator 4 interposed therebetween. Next, another separator 4 is laminated on the positive electrode layer 3b not facing the negative electrode 2 to make a laminate. The laminate is wound with the negative electrode 2 facing outside. Next, after removing the winding core, press to make it flat. Thus, the electrode group 1 shown in FIGS. 3 and 4 can be obtained.

  A strip-shaped negative electrode terminal 5 is electrically connected to the negative electrode 2. A belt-like positive electrode terminal 6 is electrically connected to the positive electrode 3.

  The nonaqueous electrolyte battery 100 shown in FIGS. 3 and 4 further includes an outer package bag 7 made of a laminate film as a container.

  The electrode group 1 is accommodated in an outer bag 7 made of a laminate film with the ends of the negative electrode terminal 5 and the positive electrode terminal 6 extended from the outer bag 7. A non-aqueous electrolyte (not shown) is accommodated in the laminated film-made outer bag 7. The nonaqueous electrolyte is impregnated in the electrode group 1. The outer bag 7 is heat-sealed at the periphery, thereby sealing the electrode group 1 and the nonaqueous electrolyte.

  Next, a second example of the nonaqueous electrolyte battery according to the second embodiment will be described in detail with reference to FIG.

  FIG. 5 is a partially cutaway perspective view of a non-aqueous electrolyte battery of a second example according to the second embodiment.

  The nonaqueous electrolyte battery 100 shown in FIG. 5 is greatly different from the nonaqueous electrolyte battery 100 of the first example in that the exterior material is composed of a metal container 7a and a sealing plate 7b.

  A nonaqueous electrolyte battery 100 shown in FIG. 5 includes an electrode group 1 similar to the electrode group 1 of the nonaqueous electrolyte battery 100 of the first example. The difference from the first example is that, in the second example shown in FIG. 5, the member 5a used as the negative electrode terminal 5 in the first example is used as the negative electrode tab, and the positive electrode in the first example. The member 6a used as the terminal 6 is used as a positive electrode tab.

  In the nonaqueous electrolyte battery 100 shown in FIG. 5, such an electrode group 1 is accommodated in a metal container 7a. The metal container 7a further stores a nonaqueous electrolyte. The metal container 7a is sealed with a metal sealing plate 7b.

  The sealing plate 7 b is provided with a negative electrode terminal 5 and a positive electrode terminal 6. An insulating member 7c is disposed between the positive terminal 6 and the sealing plate 7b. Thereby, the positive electrode terminal 6 and the sealing board 7b are electrically insulated.

  As shown in FIG. 5, the negative electrode terminal 5 is connected to the negative electrode tab 5a. Similarly, the positive electrode terminal 6 is connected to the positive electrode tab 6a.

  The nonaqueous electrolyte battery according to the second embodiment includes the positive electrode according to the first embodiment. Thanks to this, the nonaqueous electrolyte battery according to the second embodiment can exhibit high energy density, excellent input / output characteristics, and excellent cycle characteristics.

[Example]
Hereinafter, based on an Example, the said embodiment is described in detail.

(Example 1-1)
In Example 1-1, the nonaqueous electrolyte battery of Example 1-1 having the same structure as that shown in FIG.

(1) Production of positive electrode LiNi _1/3 Co _1/3 Mn _1/3 O ₂ was prepared as a positive electrode active material, and polyvinylidene fluoride as a binder. These were dissolved and mixed in N-methylpyrrolidone as a solvent so that the weight ratio of active material: binder was 100: 1. The solution thus obtained was charged into a bead-type wet fine particle dispersion pulverizer “sand grinder” which is a bead mill disperser. In this bead mill disperser, glass beads having a diameter of 2 mm were used, the number of blade rotations was set to 800 rpm, and dispersion was performed for 60 minutes. Thus, Solution A was obtained.

  On the other hand, graphite and acetylene black (weight ratio 2: 1) as conductive aids and polyvinylidene fluoride as a binder were prepared. The average particle sizes of graphite and acetylene black were 5 μm and 40 nm, respectively. These were dissolved and mixed in N-methylpyrrolidone as a solvent so that the weight ratio of conductive assistant (total of graphite and acetylene black): binder was 3: 1. The solution thus obtained was treated with a sand grinder used for preparing the solution A using glass beads having a diameter of 2 mm at a rotation speed of 800 rpm for 60 minutes. In this way, Solution B was obtained.

  The solution A and the solution B prepared as described above were mixed so that the weight ratio of the positive electrode active material, the conductive additive and the binder was 100: 3: 2. Specifically, a solution A in which the weight ratio of positive electrode active material: conductive auxiliary agent: binder is 100: 0: 1 and a solution in which the weight ratio of positive electrode active material: conductive auxiliary agent and binder is 0: 3: 1 B was mixed in a 1: 1 weight ratio. The mixed solution thus obtained was treated with two roll mills at 50 ° C. for 1 hour in an environment of 50 ° C. to prepare a paste-like positive electrode paint.

The paste-like positive electrode paint was uniformly applied to both the front and back surfaces of a positive electrode current collector made of an aluminum foil having a band thickness of 15 μm, and the coating film was dried. The coating amount of the paint was 100 g / m ² . Moreover, the area | region where the coating material was not apply | coated to both front and back was left to the positive electrode collector at the time of application | coating. The coating film after drying the paint and the positive electrode current collector were pressed and cut into predetermined dimensions. Next, a positive electrode tab was welded to the positive electrode paint uncoated portion. Thus, a positive electrode including a positive electrode current collector and a positive electrode layer formed on both surfaces of the positive electrode current collector was obtained.

(2) Production of negative electrode First, lithium titanate Li ₄ Ti ₅ O ₁₂ as a negative electrode active material, graphite as a conductive auxiliary agent, and polyvinylidene fluoride as a binder were prepared. These materials were mixed so that the weight ratio of active material: conductive auxiliary agent: binder was 100: 5: 5. The mixture thus obtained was dissolved and mixed in N-methylpyrrolidone as a solvent. Thus, a paste-like negative electrode paint was prepared.

This paste-like negative electrode paint was uniformly applied to both the front and back surfaces of a negative electrode current collector made of an aluminum foil having a band-like thickness of 15 μm, and the coating film was dried. The coating amount of the paint was 100 g / m ² . Moreover, the area | region where the coating material was not apply | coated to both the front and back was left in the negative electrode collector at the time of application | coating. The coating film after drying the paint and the negative electrode current collector were pressed and cut into predetermined dimensions. Subsequently, the negative electrode tab was welded to the negative electrode paint uncoated part. Thus, a negative electrode including a negative electrode current collector and a negative electrode layer formed on both surfaces of the negative electrode current collector was obtained.

(3) Production of electrode group The positive electrode and the negative electrode obtained as described above were wound with a separator interposed therebetween. As the separator, two polyethylene films having a thickness of 20 μm were used. Thus, an electrode group having a wound structure was produced.

(4) Preparation of non-aqueous electrolyte As a non-aqueous solvent, a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) was prepared. In this mixed solvent, the weight ratio of EC: EMC was 1: 2. In this mixed solvent, lithium hexafluorophosphate LiPF ₆ as an electrolyte was dissolved at a concentration of 1.0M. Thus, a non-aqueous electrolyte was prepared.

(5) Assembling the nonaqueous electrolyte battery Next, the container is made of a laminate film having a width of 80 mm, a height of 110 mm, a thickness of 3 mm, and having an opening, and a positive electrode terminal and a negative electrode terminal. A prepared sealing body was prepared. The sealing body further had a liquid injection port and a safety valve.

  Next, the positive electrode tab of the electrode group produced previously was connected to the positive electrode terminal of the sealing body. Similarly, the negative electrode tab of the electrode group produced previously was connected to the negative electrode terminal of the sealing body.

Next, the electrode group was accommodated in the prepared container. Next, the opening of the container was sealed with a sealing body. Next, the previously prepared non-aqueous electrolyte was injected into the container through the injection port of the sealing body and impregnated in the electrode group.
Thus, a square nonaqueous electrolyte battery of Example 1-1 was produced.

(Example 1-2)
In Example 1-2, the nonaqueous electrolyte battery of Example 1-2 was fabricated by the same procedure as in Example 1-1, except that carbon nanotubes were used instead of graphite as the conductive assistant for the positive electrode. The average diameter of the carbon nanotubes was 2 nm and the average length was 6 μm.

(Example 1-3)
In Example 1-3, the mixture ratio of the positive electrode active material, the conductive additive, and the binder at the time of producing the positive electrode was set to 100: 4: 3 by weight, and the same procedure as in Example 1-1 was performed. A nonaqueous electrolyte battery of Example 1-3 was produced.

  Specifically, in Example 1-3, a paste-like positive electrode paint was prepared by the following procedure.

  First, a solution A was prepared by the same procedure as in Example 1-1.

  On the other hand, in Example 1-3, instead of Solution B, Solution C was prepared according to the following procedure. First, graphite and acetylene black (weight ratio 2: 1) as conductive assistants and polyvinylidene fluoride as a binder were prepared. These were the same as those used in Example 1-1. These were dissolved and mixed in N-methylpyrrolidone as a solvent so that the weight ratio of conductive assistant (total of graphite and acetylene black): binder was 4: 2. The solution thus obtained was treated with a sand grinder used for preparing the solution A using glass beads having a diameter of 2 mm at a rotation speed of 800 rpm for 60 minutes. In this way, Solution C was obtained.

  Next, the solution A and the solution C prepared as described above were mixed so that the weight ratio of the positive electrode active material: conductive auxiliary agent: binder was 100: 4: 3. Specifically, a solution A in which the weight ratio of positive electrode active material: conductive auxiliary agent: binder is 100: 0: 1 and a solution in which the weight ratio of positive electrode active material: conductive auxiliary agent: binder is 0: 4: 2 C was mixed in a 1: 1 weight ratio. The mixed solution thus obtained was treated with two roll mills at 50 ° C. for 1 hour in an environment of 50 ° C. to prepare a paste-like positive electrode paint.

  In Example 1-3, a positive electrode was produced in the same manner as in Example 1-1 except that this paste-like positive electrode paint was used.

(Comparative Example 1-1)
In Comparative Example 1-1, in the preparation of the positive electrode coating material, the positive electrode active material, the conductive auxiliary agent, and the binder were all mixed at the same time in Fillmix (registered trademark) (40-40 type, manufactured by Primix). A nonaqueous electrolyte battery of Comparative Example 1-1 was produced by the same procedure as 1-1. Mixing with Fillmix (registered trademark) was performed under conditions of 25 m / sec and 3 minutes.

(Comparative Example 1-2)
In Comparative Example 1-2, the mixture ratio of the positive electrode active material, the conductive additive and the binder at the time of producing the positive electrode was the same as that of Example 1-1 except that the weight ratio was 100: 0.5: 5. The nonaqueous electrolyte battery of Comparative Example 1-2 was produced by the procedure.

  Specifically, in Comparative Example 1-2, a paste-like positive electrode paint was prepared by the following procedure.

  First, a solution A was prepared by the same procedure as in Example 1-1.

  On the other hand, in Comparative Example 1-2, instead of Solution B, Solution D was prepared by the following procedure. First, graphite and acetylene black (weight ratio 2: 1) as conductive assistants and polyvinylidene fluoride as a binder were prepared. These were the same as those used in Example 1-1. These were dissolved and mixed in N-methylpyrrolidone as a solvent so that the weight ratio of conductive assistant (total of graphite and acetylene black): binder was 0.5: 4. The solution thus obtained was treated with a sand grinder used for preparing the solution A using glass beads having a diameter of 2 mm at a rotation speed of 800 rpm for 60 minutes. In this way, Solution D was obtained.

  The solution A and the solution D prepared as described above were mixed so that the weight ratio of the positive electrode active material, the conductive additive and the binder was 100: 0.5: 5. Specifically, the weight ratio of positive electrode active material: conductive auxiliary agent: binder is 100: 0: 1 and the positive electrode active material: conductive auxiliary agent: binder weight ratio is 0: 0.5: 4. A solution D was mixed in a 1: 1 weight ratio. The mixed solution thus obtained was treated with two roll mills at 50 ° C. for 1 hour in an environment of 50 ° C. to prepare a paste-like positive electrode paint.

  In Comparative Example 1-2, a positive electrode was produced by the same procedure as in Example 1-1 except that this paste-like positive electrode paint was used.

(Example 2-1)
In Example 2-1, the nonaqueous electrolyte battery of Example 2-1 was produced by the same procedure as Example 1-1 except that the positive electrode was produced by the following procedure.

In Example 2-1, instead of Solution A, Solution E was prepared by the following procedure. First, lithium manganese composite oxide LiMn ₂ O ₄ was prepared as a positive electrode active material. This positive electrode active material and polyvinylidene fluoride as a binder were dissolved and mixed in N-methylpyrrolidone as a solvent at a weight ratio of 100: 1. The solution thus obtained was put into a sand grinder similar to that used in the preparation of solution A in Example 1-1. In this bead mill disperser, glass beads having a diameter of 2 mm were used, the number of rotations of the wings was set to 600 rpm, and dispersion was performed for 50 minutes. In this way, Solution E was obtained.

  On the other hand, Solution B was prepared by the same procedure as in Example 1-1.

  Solution E and solution B prepared as described above were mixed so that the weight ratio of positive electrode active material: conductive auxiliary agent: binder was 100: 3: 2. Specifically, a solution E in which the weight ratio of positive electrode active material: conductive auxiliary agent: binder is 100: 0: 1 and a solution in which the weight ratio of positive electrode active material: conductive auxiliary agent: binder is 0: 3: 1 B was mixed in a 1: 1 weight ratio. The mixed solution thus obtained was treated with two roll mills at 50 ° C. for 1 hour in an environment of 50 ° C. to prepare a paste-like positive electrode paint.

  In Example 2-1, a positive electrode was produced in the same procedure as in Example 1-1 except that this paste-like positive electrode paint was used.

(Comparative Example 2-1)
In Comparative Example 2-1, in preparing the positive electrode paint, Example 2-1 except that the positive electrode active material, the conductive additive, and the binder were mixed at the same time in a planetary mixer (3D-5 type, manufactured by Primex). A non-aqueous electrolyte battery of Comparative Example 2-1 was produced by the same procedure as described above. Mixing with a planetary mixer was performed under conditions of 50 rpm and 1 hour.

(Example 3-1)
In Example 3-1, the nonaqueous electrolyte battery of Example 3-1 was produced in the same procedure as in Example 1-1, except for the following points.

  First, in Example 3-1, a paste-like positive electrode paint was prepared by the following procedure.

  First, a solution A was prepared by the same procedure as in Example 1-1.

  On the other hand, in Example 3-1, instead of the solution B, the solution F prepared by the same procedure as the preparation procedure of the solution B except for the following points was used. In Example 3-1, the dispersion of the N-methylpyrrolidone solution containing the conductive assistant was made of glass beads having a diameter of 2 mm in the same sand grinder as used in Example 1-1. Solution F was prepared by setting the rotation speed of the wings to 700 rpm and performing the dispersion time for 60 minutes. In the solution F obtained by dispersion under such conditions, the ratio of the total weight of graphite and acetylene black to the weight of polyvinylidene fluoride was 3: 1.

  Next, the solution A and the solution F prepared as described above were mixed so that the weight ratio of positive electrode active material: conductive auxiliary agent: binder was 100: 3: 2. Specifically, a solution A in which the weight ratio of positive electrode active material: conductive auxiliary agent: binder is 100: 0: 1 and a solution in which the weight ratio of positive electrode active material: conductive auxiliary agent: binder is 0: 3: 1 F was mixed in a 1: 1 weight ratio. The mixed solution thus obtained was treated with two roll mills at 50 ° C. for 1 hour in an environment of 50 ° C. to prepare a paste-like positive electrode paint. A positive electrode was produced in the same procedure as in Example 1-1 except that the positive electrode paint thus obtained was used.

  In Example 3-1, a negative electrode was produced in the same procedure as in Example 1-1 except that MCF (mesophase pitch carbon fiber) was used as the negative electrode active material instead of lithium titanate.

(Comparative Example 3-1)
In Comparative Example 3-1, the mixing ratio of the positive electrode active material, the conductive additive and the binder in the production of the positive electrode was 100: 1: 5 in the same procedure as in Example 3-1, except that the mixing ratio was 100: 1: 5. A nonaqueous electrolyte battery of Comparative Example 3-1 was produced.

  Specifically, in Comparative Example 3-1, a paste-like positive electrode paint was prepared by the following procedure.

  First, a solution A was prepared by the same procedure as in Example 1-1.

  On the other hand, in Comparative Example 3-1, a solution G was prepared in the following procedure instead of the solution B. First, graphite and acetylene black (weight ratio 2: 1) as conductive assistants and polyvinylidene fluoride as a binder were prepared. These were the same as those used in Example 1-1. These were dissolved and mixed in N-methylpyrrolidone as a solvent so that the weight ratio of conductive assistant (total of graphite and acetylene black): binder was 1: 4. The solution thus obtained was treated with a sand grinder used for the preparation of the solution A using glass beads having a diameter of 2 mm at a rotation speed of 700 rpm for 60 minutes. In this way, Solution G was obtained.

  Next, the solution A and the solution G prepared as described above were mixed so that the weight ratio of positive electrode active material: conductive auxiliary agent: binder was 100: 1: 5. Specifically, a solution A in which the weight ratio of positive electrode active material: conductive auxiliary agent: binder is 100: 0: 1 and a solution in which the weight ratio of positive electrode active material: conductive auxiliary agent: binder is 0: 1: 4 G was mixed in a 1: 1 weight ratio. The mixed solution thus obtained was treated with two roll mills at 50 ° C. for 1 hour in an environment of 50 ° C. to prepare a paste-like positive electrode paint.

  In Comparative Example 3-1, a positive electrode was produced in the same manner as in Example 3-1, except that this paste-like positive electrode paint was used.

[Evaluation]
<Adjustment to the shipment status>
The nonaqueous electrolyte batteries of Examples 1-1 to 1-3, 2-1 and Comparative Examples 1-1, 1-2, and 2-1 were adjusted to the shipment state according to the following procedure.

  First, each nonaqueous electrolyte battery was initially charged in a 25 ° C. environment and at a rate of 1 C until the battery voltage reached 2.8V. Each non-aqueous electrolyte battery was then discharged at a rate of 1C until the battery voltage reached 1.3V. The capacity discharged at this time was defined as the rated capacity. The product obtained by applying the average operating voltage to the rated capacity divided by the battery weight (unit: Wh / kg) was used as the energy density of each nonaqueous electrolyte battery. The energy density of each nonaqueous electrolyte battery is shown in Table 3 below.

  Each non-aqueous electrolyte battery was then charged at a rate of 1 C until SOC 50% was reached. A non-aqueous electrolyte battery with 50% SOC was set to the shipping state.

  About the nonaqueous electrolyte battery of Example 1-3 and Comparative Example 3-1, it adjusted to the shipment state with the following procedures.

  First, each nonaqueous electrolyte battery was initially charged at 25 ° C. and at a rate of 0.1 C until the battery voltage reached 4.3V. Each nonaqueous electrolyte battery was then discharged at a rate of 1C until the battery voltage reached 3.0V. The capacity discharged at this time was defined as the rated capacity. The product obtained by applying the average operating voltage to the rated capacity divided by the battery weight (unit: Wh / kg) was used as the energy density of each nonaqueous electrolyte battery. The energy density of each nonaqueous electrolyte battery is shown in Table 3 below.

  Each non-aqueous electrolyte battery was then charged at a rate of 1 C until SOC 50% was reached. A non-aqueous electrolyte battery with 50% SOC was set to the shipping state.

<Low temperature output test>
Each nonaqueous electrolyte battery in the shipping state was subjected to a low-temperature output test according to the following procedure.

  First, the nonaqueous electrolyte battery was discharged at 1 C in an environment of 25 ° C. from the shipment state to SOC 30%. Next, the environmental temperature was set to −20 ° C., and the system was waited for 3 hours. After confirming that the cell temperature became −20 ° C., a 6 W constant power test was performed.

  The resulting output time is shown in Table 3 below.

<Cycle characteristic evaluation test>
Each non-aqueous electrolyte battery subjected to the low temperature output test was then subjected to 500 charge / discharge cycles at a rate of 2C. For the non-aqueous electrolyte batteries of Examples 1-1 to 1-3 and 2-1, and Comparative Examples 1-1, 1-2, and 2-1, the voltage range in the cycle test was 2.7 V to 1.5 V. did. On the other hand, for the nonaqueous electrolyte batteries of Example 3-1 and Comparative Example 3-1, the voltage range in the cycle test was set to 4.2 V to 3.0 V. About each nonaqueous electrolyte battery, the capacity | capacitance after 500 cycles was confirmed. The relative values of the confirmed capacity after 500 cycles with respect to the rated capacity are shown in Table 3 below as capacity retention rates.

<Observation of positive electrode layer with scanning probe microscope>
As described above, the positive electrode was taken out from each non-aqueous electrolyte battery subjected to the various evaluation tests described above. Next, as described above, a positive electrode measurement sample was prepared from the extracted positive electrode. The prepared measurement sample was subjected to scanning probe microscope observation using E-sweep manufactured by Hitachi High-Tech Science Co., Ltd. (formerly SII nanotechnology) as a measuring device.

The mapping image shown in FIG. 1 is one mapping image for the positive electrode of the nonaqueous electrolyte battery of Example 1-1. By analyzing according to the method demonstrated previously from the mapping image obtained about the positive electrode of the nonaqueous electrolyte battery of Example 1-1, in the positive electrode of the nonaqueous electrolyte battery of Example 1-1, the resistance value is 1 GΩ or less. The ratio of the plurality of regions to the positive electrode layer is 12%, and the average area of the plurality of regions having a resistance value of 1 GΩ or less included in the mapping image obtained by the scanning probe microscope observation of the positive electrode layer is 0.03 μm. It turned out to be ² .

  With respect to the non-aqueous electrolyte batteries of Examples 1-1 to 1-3, 2-1, and 3-1, and Comparative Examples 1-1, 1-2, 2-1, and 3-1, the resistance value is 1 GΩ or less. Table 3 below shows the proportion of the plurality of regions in the positive electrode layer and the average area of the plurality of regions having a resistance value of 1 GΩ or less included in the mapping image obtained by observation with the scanning probe microscope of the positive electrode layer. .

  From the results in Table 3, it can be seen that the nonaqueous electrolyte batteries of Examples 1-1 to 1-3 are superior in battery characteristics to the nonaqueous electrolyte batteries of Comparative Examples 1-1 and 1-2. That is, each of the nonaqueous electrolyte batteries of Examples 1-1 to 1-3 has a high energy density, excellent input / output characteristics, and the nonaqueous electrolyte batteries of Comparative Examples 1-1 and 1-2. It can be seen that excellent cycle characteristics could be exhibited.

In Comparative Example 1-1, the average area of a plurality of regions having a resistance value of 1 GΩ or less included in the mapping image obtained by observation of the positive electrode layer with a scanning probe microscope was 0.2 μm ² or more. Therefore, in the nonaqueous electrolyte battery of Comparative Example 1-1, it is considered that the conductive auxiliary agent forming a conductive network in the positive electrode layer was not sufficiently present in the vicinity of the positive electrode active material. This is considered to be the reason why the nonaqueous electrolyte battery of Comparative Example 1-1 was inferior to the battery characteristics of the nonaqueous electrolyte batteries of Examples 1-1 to 1-3.

  In Comparative Example 1-2, the ratio of the plurality of regions having a resistance value of 1 GΩ or less to the positive electrode layer was less than 4. Therefore, in Comparative Example 1-2, it is considered that the amount of the conductive auxiliary agent that forms the conductive network is insufficient in the positive electrode layer, and the conductive network is lacking in the positive electrode layer. This is considered to be the reason why the nonaqueous electrolyte battery of Comparative Example 1-2 was inferior to the battery characteristics of the nonaqueous electrolyte batteries of Examples 1-1 to 1-3.

  Moreover, from the results in Table 3, it can be seen that the nonaqueous electrolyte battery of Example 2-1 is superior to the nonaqueous electrolyte battery of Comparative Example 2-1 in terms of output time, energy density, and capacity retention rate.

In Comparative Example 2-1, the average area of the plurality of regions having a resistance value of 1 GΩ or less included in the mapping image obtained by observation with the scanning probe microscope of the positive electrode layer was 0.2 μm ² or more. Therefore, in the nonaqueous electrolyte battery of Comparative Example 2-1, it is considered that the conductive auxiliary agent forming the conductive network in the positive electrode layer was not sufficiently present in the vicinity of the positive electrode active material. This is considered to be the reason why the nonaqueous electrolyte battery of Comparative Example 2-1 was inferior to the battery characteristics of the nonaqueous electrolyte battery of Example 2-1.

  Furthermore, it can be seen from the results in Table 3 that the nonaqueous electrolyte battery of Example 3-1 is superior to the nonaqueous electrolyte battery of Comparative Example 3-1 in terms of output time, energy density, and capacity retention rate.

  In Comparative Example 3-1, the ratio of the plurality of regions having a resistance value of 1 GΩ or less to the positive electrode layer was less than 4%. Therefore, in Comparative Example 3-1, it is considered that the amount of the conductive auxiliary agent forming the conductive network is insufficient in the positive electrode layer, and the conductive network is lacking in the positive electrode layer. This is considered to be the reason why the nonaqueous electrolyte battery of Comparative Example 3-1 was inferior to the battery characteristics of the nonaqueous electrolyte battery of Example 3-1.

  And from the results shown in Table 3 and the previous discussion, the difference in battery characteristics between the non-aqueous electrolyte battery of Example 2-1 and the non-aqueous electrolyte battery of Comparative Example 2-1 is the same as that of Example 1-1. It turns out that it is the same as the difference of the battery characteristic between a nonaqueous electrolyte battery and the nonaqueous electrolyte battery of Comparative Example 1-1. From this fact, the non-aqueous electrolyte batteries of Example 1-1 and Example 2-1 are similarly high energy density, excellent input / output characteristics, and excellent cycle even if the type of the positive electrode active material is different. It turns out that the characteristic was able to be shown.

  Similarly, from the results shown in Table 3 and the previous discussion, the difference in battery characteristics between the non-aqueous electrolyte battery of Example 3-1 and the non-aqueous electrolyte battery of Comparative Example 3-1 is similar to Example 1-1. It turns out that it is the same as that of the difference of the battery characteristic between the nonaqueous electrolyte battery of this, and the nonaqueous electrolyte battery of Comparative Example 1-2. From this fact, the non-aqueous electrolyte batteries of Example 1-1 and Example 3-1 have the same high energy density, excellent input / output characteristics, and excellent cycle even if the types of the negative electrode active materials are different. It turns out that the characteristic was able to be shown.

(Example 1-4)
In Example 1-4, the mixture ratio of the positive electrode active material, the conductive additive, and the binder in the production of the positive electrode was set to 100: 5: 2 by weight, and the same procedure as in Example 1-1 was performed. The nonaqueous electrolyte battery of Example 1-4 was produced.

  Specifically, in Example 1-4, a paste-like positive electrode paint was prepared by the following procedure.

  First, a solution A was prepared by the same procedure as in Example 1-1.

  On the other hand, in Example 1-4, instead of Solution B, Solution H was prepared by the following procedure. First, graphite and acetylene black (weight ratio 2: 1) as conductive assistants and polyvinylidene fluoride as a binder were prepared. These were the same as those used in Example 1-1. These were dissolved and mixed in N-methylpyrrolidone as a solvent so that the weight ratio of conductive assistant (total of graphite and acetylene black): binder was 5: 1. The solution thus obtained was treated with a sand grinder used for preparing the solution A using glass beads having a diameter of 2 mm at a rotation speed of 800 rpm for 60 minutes. In this way, Solution H was obtained.

  Next, the solution A and the solution H prepared as described above were mixed so that the weight ratio of positive electrode active material: conductive auxiliary agent: binder was 100: 5: 2. Specifically, a solution A having a positive electrode active material: conductive auxiliary agent: binder weight ratio of 100: 0: 1 and a positive electrode active material: conductive auxiliary agent: binder weight ratio of 0: 5: 1 H was mixed in a 1: 1 weight ratio. The mixed solution thus obtained was treated with two roll mills at 50 ° C. for 1 hour in an environment of 50 ° C. to prepare a paste-like positive electrode paint.

  In Example 1-4, a positive electrode was produced in the same manner as in Example 1-1 except that this paste-like positive electrode paint was used.

(Example 1-5)
In Example 1-5, a nonaqueous electrolyte battery according to Example 1-5 was produced in the same manner as in Example 1-1, except for the following points.

  Specifically, in Example 1-5, a paste-like positive electrode paint was prepared by the following procedure.

  First, a solution A was prepared by the same procedure as in Example 1-1.

  On the other hand, in Example 1-5, the solution I was used instead of the solution B. Solution I was prepared by the same procedure as the preparation method of Solution B except for the dispersion conditions. Dispersion for preparing the solution I was carried out by a sand grinder like the solution B. Dispersion was carried out over 60 minutes using glass beads with a diameter of 1 mm, with the wing rotation speed set to 800 rpm. In solution I obtained by dispersion under such conditions, the ratio of the total weight of graphite and acetylene black to the weight of polyvinylidene fluoride was 3: 1.

  Next, the solution A and the solution I prepared as described above were mixed so that the weight ratio of positive electrode active material: conductive auxiliary agent: binder was 100: 3: 2. Specifically, a solution A in which the weight ratio of positive electrode active material: conductive auxiliary agent: binder is 100: 0: 1 and a solution in which the weight ratio of positive electrode active material: conductive auxiliary agent: binder is 0: 3: 1 I was mixed in a 1: 1 weight ratio. The mixed solution thus obtained was treated with two roll mills at 50 ° C. for 1 hour in an environment of 50 ° C. to prepare a paste-like positive electrode paint.

  In Example 1-5, a positive electrode was produced in the same manner as in Example 1-1 except that this paste-like positive electrode paint was used.

(Comparative Example 1-3)
In Comparative Example 1-3, the mixing ratio of the positive electrode active material, the conductive additive and the binder at the time of producing the positive electrode was the same as that of Example 1-1 except that the weight ratio was 100: 15: 2. The nonaqueous electrolyte battery of Comparative Example 1-3 was produced.

  Specifically, in Comparative Example 1-3, a paste-like positive electrode paint was prepared by the following procedure.

  First, a solution A was prepared by the same procedure as in Example 1-1.

  On the other hand, in Comparative Example 1-3, instead of Solution B, Solution J was prepared by the following procedure. First, graphite and acetylene black (weight ratio 2: 1) as conductive assistants and polyvinylidene fluoride as a binder were prepared. These were the same as those used in Example 1-1. These were dissolved and mixed in N-methylpyrrolidone as a solvent so that the weight ratio of conductive assistant (total of graphite and acetylene black): binder was 15: 1. The solution thus obtained was treated with a sand grinder used for the preparation of the solution A using glass beads having a diameter of 2 mm at a rotation speed of 800 rpm for 60 minutes. In this way, Solution J was obtained.

  Next, the solution A and the solution J prepared as described above were mixed so that the weight ratio of the positive electrode active material, the conductive additive and the binder was 100: 15: 2. Specifically, a solution A having a positive electrode active material: conductive auxiliary agent: binder weight ratio of 100: 0: 1 and a positive electrode active material: conductive auxiliary agent: binder weight ratio of 0: 15: 1. J was mixed in a 1: 1 weight ratio. The mixed solution thus obtained was treated with two roll mills at 50 ° C. for 1 hour in an environment of 50 ° C. to prepare a paste-like positive electrode paint.

  In Comparative Example 1-3, a positive electrode was produced by the same procedure as in Example 1-1, except that this paste-like positive electrode paint was used.

(Comparative Example 1-4)
In Comparative Example 1-4, a nonaqueous electrolyte battery according to Comparative Example 1-4 was produced according to the same procedure as Example 1-1 except for the following points.

  Specifically, in Comparative Example 1-4, a paste-like positive electrode paint was prepared by the following procedure.

  First, a solution A was prepared by the same procedure as in Example 1-1.

  On the other hand, in Comparative Example 1-4, the solution K was used instead of the solution B. Solution K was prepared by the same procedure as the preparation method of Solution B except for the dispersion conditions. Dispersion for preparing the solution K was performed by a sand grinder as in the case of the solution B. Dispersion was performed over 60 minutes by using glass beads having a diameter of 2 mm, setting the number of wing rotations to 100 rpm. In the solution K obtained by dispersion under such conditions, the ratio of the total weight of graphite and acetylene black to the weight of polyvinylidene fluoride was 3: 1.

  Next, the solution A and the solution K prepared as described above were mixed so that the weight ratio of positive electrode active material: conductive auxiliary agent: binder was 100: 3: 2. Specifically, a solution A in which the weight ratio of positive electrode active material: conductive auxiliary agent: binder is 100: 0: 1 and a solution in which the weight ratio of positive electrode active material: conductive auxiliary agent: binder is 0: 3: 1 K was mixed in a 1: 1 weight ratio. The mixed solution thus obtained was treated with two roll mills at 50 ° C. for 1 hour in an environment of 50 ° C. to prepare a paste-like positive electrode paint.

  In Comparative Example 1-4, a positive electrode was produced in the same manner as in Example 1-1 except that this paste-like positive electrode paint was used.

(Comparative Example 1-5)
In Comparative Example 1-5, a nonaqueous electrolyte battery according to Comparative Example 1-5 was produced in the same manner as in Example 1-1, except for the following points.

  Specifically, in Comparative Example 1-5, a paste-like positive electrode paint was prepared by the following procedure.

  First, a solution A was prepared by the same procedure as in Example 1-1.

  On the other hand, in Comparative Example 1-5, the solution L was used instead of the solution B. Solution L was prepared by the same procedure as the preparation method of Solution B except for the dispersion conditions. Dispersion for preparing the solution L was performed by a sand grinder in the same manner as the solution B. Dispersion was carried out over 10 minutes using glass beads having a diameter of 2 mm, setting the number of wing rotations to 800 rpm. In the solution L obtained by dispersion under such conditions, the ratio of the total weight of graphite and acetylene black to the weight of polyvinylidene fluoride was 3: 1.

  Next, the solution A and the solution L prepared as described above were mixed so that the weight ratio of positive electrode active material: conductive auxiliary agent: binder was 100: 3: 2. Specifically, a solution A in which the weight ratio of positive electrode active material: conductive auxiliary agent: binder is 100: 0: 1 and a solution in which the weight ratio of positive electrode active material: conductive auxiliary agent: binder is 0: 3: 1 L was mixed in a 1: 1 weight ratio. The mixed solution thus obtained was treated with two roll mills at 50 ° C. for 1 hour in an environment of 50 ° C. to prepare a paste-like positive electrode paint.

  In Comparative Example 1-5, a positive electrode was produced in the same procedure as in Example 1-1 except that this paste-like positive electrode paint was used.

(Example 4-1)
In Example 4-1, the same procedure as in Example 1-1 was used except that titanium oxide TiO ₂ (B) was used instead of lithium titanate as the negative electrode active material. A water electrolyte battery was prepared.

(Comparative Example 4-1)
In Comparative Example 4-1, the same procedure as in Comparative Example 1-4 was performed except that titanium oxide TiO ₂ (B) was used as the negative electrode active material instead of lithium titanate. A water electrolyte battery was prepared.

  That is, in Comparative Example 4-1, the solution A and the solution K were mixed at a weight ratio of 1: 1 to obtain a paste-like positive electrode paint. Dispersion for preparing the solution K was performed for 60 minutes by using glass beads having a diameter of 2 mm and setting the rotation speed of the wings to 100 rpm.

(Example 5-1)
In Example 5-1, the same procedure as in Example 1-1 was performed except that niobium titanium composite oxide Nb ₂ TiO ₇ was used as the negative electrode active material instead of lithium titanate. A nonaqueous electrolyte battery was produced.

(Comparative Example 5-1)
In Comparative Example 5-1, the same procedure as in Comparative Example 5-1 was performed except that niobium titanium composite oxide Nb ₂ TiO ₇ was used as the negative electrode active material instead of lithium titanate. A nonaqueous electrolyte battery was produced.

  That is, in Comparative Example 5-1, the solution A and the solution L were mixed at a weight ratio of 1: 1 to obtain a paste-like positive electrode paint. Dispersion for preparing the solution L was performed for 10 minutes by using glass beads having a diameter of 2 mm and setting the rotation speed of the wings to 800 rpm.

[Evaluation]
<Preparation to shipment>
The nonaqueous electrolyte batteries of Examples 1-4 and 1-5, Comparative Examples 1-3 to 1-5, Example 4-1, Comparative Example 4-1, Example 5-1, and Comparative Example 5-1. The non-aqueous electrolyte battery of Example 1-1 was adjusted to the shipping state by the same procedure as that performed at the time of adjustment to the pickup state. The energy density of each non-aqueous electrolyte battery measured during this procedure is shown in Table 4 below.

<Low temperature output test>
Each nonaqueous electrolyte battery in the shipping state was subjected to a low-temperature output test according to the procedure described above. The output time for each nonaqueous electrolyte battery obtained in this test is shown in Table 4 below.

<Cycle characteristic evaluation test>
Each nonaqueous electrolyte battery subjected to the low-temperature output test was then subjected to the charge / discharge cycle at the 2C rate described above 500 times. The voltage range in the cycle test was 2.7 V to 1.5 V.

  About each nonaqueous electrolyte battery, the capacity | capacitance after 500 cycles was confirmed. The relative values of the confirmed capacity after 500 cycles with respect to the rated capacity are shown in Table 4 below as capacity retention rates. In addition, the rated capacity of each nonaqueous electrolyte battery was measured during the procedure for adjustment to the shipping state as described above.

<Observation of positive electrode layer with scanning probe microscope>
The positive electrode was taken out from each non-aqueous electrolyte battery subjected to the various evaluation tests described above by the procedure described above. For each positive electrode taken out, the positive electrode layer was observed with a scanning probe microscope in the same manner as described above. The results of observation with a scanning probe microscope are shown in Table 4 below.

  From the results of Table 3 and Table 4, each non-aqueous electrolyte battery of Examples 1-1 to 1-5 is superior to each non-aqueous electrolyte battery of Comparative Examples 1-1 to 1-5. I understand. That is, each nonaqueous electrolyte battery of Examples 1-1 to 1-5 has higher energy density, superior input / output characteristics, and more than each nonaqueous electrolyte battery of Comparative Examples 1-1 to 1-5. It can be seen that excellent cycle characteristics could be exhibited.

  The reason why the nonaqueous electrolyte batteries of Comparative Examples 1-1 to 1-3 were inferior to the nonaqueous electrolyte batteries of Examples 1-1 to 1-5 was described in detail above. It is thought to be the cause.

In Comparative Example 1-3, the ratio of the plurality of regions having a resistance value of 1 GΩ or less to the positive electrode layer is more than 20%, and the resistance value included in the mapping image obtained by the scanning probe microscope observation of the positive electrode layer is 1 GΩ or less. The average area of the plurality of regions was 0.2 μm ² or more. Therefore, in the nonaqueous electrolyte battery of Comparative Example 1-3, the positive electrode layer included an excessive amount of conductive additive relative to the positive electrode active material. As a result, as shown in Tables 3 and 4, the nonaqueous electrolyte battery of Comparative Example 1-3 had a lower energy density than the nonaqueous electrolyte batteries of Examples 1-1 to 1-5. Further, in the nonaqueous electrolyte battery of Comparative Example 1-3, the load on the positive electrode active material during the cycle test was increased due to the low proportion of the positive electrode active material in the positive electrode layer, and the positive electrode active material was deteriorated. It is done. This is considered to be the reason why the output time and capacity retention rate of the nonaqueous electrolyte battery of Comparative Example 1-3 were inferior to those of the nonaqueous electrolyte batteries of Examples 1-1 to 1-5.

In Comparative Example 1-4, the average area of the plurality of regions having a resistance value of 1 GΩ or less included in the mapping image obtained by the scanning probe microscope observation of the positive electrode layer was 0.2 μm ² or more. Therefore, in the nonaqueous electrolyte battery of Comparative Example 1-4, it is considered that the conductive auxiliary agent forming a conductive network in the positive electrode layer was not sufficiently present in the vicinity of the positive electrode active material. This is considered to be the reason why the nonaqueous electrolyte battery of Comparative Example 1-4 was inferior to the battery characteristics of the nonaqueous electrolyte batteries of Examples 1-1 to 1-5.

In Comparative Example 1-5, the average area of the plurality of regions in which the resistance value included in the mapping image obtained by the scanning probe microscope observation of the positive electrode layer was 10 mΩ or more and 1 GΩ or less was 0.2 μm ² or more. Therefore, in the nonaqueous electrolyte battery of Comparative Example 1-5, it is considered that the conductive auxiliary agent forming the conductive network in the positive electrode layer was not sufficiently present in the vicinity of the positive electrode active material. This is considered to be the reason why the nonaqueous electrolyte battery of Comparative Example 1-5 was inferior to the battery characteristics of the nonaqueous electrolyte batteries of Examples 1-1 to 1-5.

  From the results shown in Table 4, it can be seen that the nonaqueous electrolyte battery of Example 4-1 is superior to the nonaqueous electrolyte battery of Comparative Example 4-1 in terms of output time, energy density, and capacity retention rate. .

In Comparative Example 4-1, the average area of the plurality of regions having a resistance value of 1 GΩ or less included in the mapping image obtained by the scanning probe microscope observation of the positive electrode layer was 0.2 μm ² or more. Therefore, in the nonaqueous electrolyte battery of Comparative Example 4-1, it is considered that the conductive auxiliary agent forming a conductive network in the positive electrode layer was not sufficiently present in the vicinity of the positive electrode active material. This is considered to be the reason why the nonaqueous electrolyte battery of Comparative Example 4-1 was inferior to the battery characteristics of the nonaqueous electrolyte battery of Example 4-1.

  Furthermore, from the results shown in Table 4, it can be seen that the nonaqueous electrolyte battery of Example 5-1 is superior to the nonaqueous electrolyte battery of Comparative Example 5-1 in terms of output time, energy density, and capacity retention rate. .

In Comparative Example 5-1, the average area of the plurality of regions having a resistance value of 1 GΩ or less included in the mapping image obtained by observation with the scanning probe microscope of the positive electrode layer was 0.2 μm ² or more. Therefore, in the nonaqueous electrolyte battery of Comparative Example 5-1, it is considered that the conductive auxiliary agent forming a conductive network in the positive electrode layer was not sufficiently present in the vicinity of the positive electrode active material. This is considered to be the reason why the nonaqueous electrolyte battery of Comparative Example 5-1 was inferior to the battery characteristics of the nonaqueous electrolyte battery of Example 5-1.

  And from the results shown in Tables 3 and 4 and the previous discussion, the difference in battery characteristics between the nonaqueous electrolyte battery of Example 4-1 and the nonaqueous electrolyte battery of Comparative Example 4-1 is different from Example 1-1. It turns out that it is the same as the difference of the battery characteristic of 1 nonaqueous electrolyte battery and the nonaqueous electrolyte battery of Comparative Example 1-4. Further, the difference in battery characteristics between the non-aqueous electrolyte battery of Example 5-1 and the non-aqueous electrolyte battery of Comparative Example 5-1 is the battery between Example 1-1 and the non-aqueous electrolyte battery of Comparative Example 1-5. It can be seen that this is the same as the difference in characteristics. Furthermore, as described above, from the results shown in Table 3 and the previous discussion, the difference in battery characteristics between the nonaqueous electrolyte battery of Example 3-1 and the nonaqueous electrolyte battery of Comparative Example 3-1 is as follows. It turns out that it is the same as the difference of the battery characteristic between the nonaqueous electrolyte battery of Example 1-1 and the nonaqueous electrolyte battery of Comparative Example 1-2. From these facts, each of the nonaqueous electrolyte batteries of Example 1-1, Example 3-1, Example 4-1, and Example 5-1 is the same even if the type of the negative electrode active material is different. It can be seen that high energy density, excellent input / output characteristics, and excellent cycle characteristics could be exhibited.

The positive electrode according to at least one embodiment and example described above includes a plurality of regions in which the positive electrode layer has a resistance value of 1 GΩ or less. The proportion of this region in the positive electrode layer is 4% or more and 20% or less. The average area of the plurality of areas the resistance value is less 1GΩ included in the mapping image obtained by scanning probe microscopy of the positive electrode layer is larger 0.2μm less than ² than 0 .mu.m ^2. Thanks to this, the positive electrode according to the first embodiment can include a sufficient amount of a plurality of regions having a resistance value of 1 GΩ or less in the positive electrode layer in a sufficiently dispersed state. As a result, this positive electrode can realize a non-aqueous electrolyte battery that can exhibit high energy density, excellent input / output characteristics, and excellent cycle characteristics.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Electrode group, 2 ... Negative electrode, 2a ... Negative electrode collector, 2b ... Negative electrode layer, 3 ... Positive electrode, 3a ... Positive electrode collector, 3b ... Positive electrode layer, 3c ... Area | region whose resistance value is 1 Gohm or less, 4 ... Separator, 5 ... Negative electrode terminal, 5a ... Negative electrode tab, 6 ... Positive electrode terminal, 6a ... Positive electrode tab, 7 ... Exterior material, 7a ... Metal container, 7b ... Sealing plate, 7c ... Insulating member, 100 ... Nonaqueous electrolyte battery.

Claims (7)

A positive electrode current collector;
A positive electrode layer formed on the positive electrode current collector and including a positive electrode active material, a conductive additive, and a binder;
Comprising
The positive electrode layer includes a plurality of regions having a resistance value of 1 GΩ or less,
The proportion of the plurality of regions in the positive electrode layer is 4% or more and 20% or less,
The positive electrode in which the average area of the plurality of areas included in the map image obtained by scanning probe microscopy of the positive electrode layer, characterized in that it is a larger 0.2μm less than ² than 0 .mu.m ^2. Wherein the average area of the plurality of areas included in the mapping image obtained by the scanning probe microscope of the positive electrode layer, according to claim 1, characterized in that less than ² greater than 0 .mu.m ² 0.09 .mu.m Positive electrode.   The positive electrode according to claim 2, wherein a ratio of the plurality of regions to the positive electrode layer is 10% or more and 15% or less.   The positive electrode according to claim 2, wherein the conductive auxiliary agent includes at least one selected from the group consisting of carbon black, carbon nanotubes, carbon nanofibers, and graphite.   The positive electrode active material is nickel cobalt manganese composite oxide, lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt composite oxide, lithium nickel cobalt composite oxide, lithium manganese cobalt composite oxide, lithium iron phosphate, and The positive electrode according to claim 2, comprising at least one selected from the group consisting of lithium composite phosphate compounds. The positive electrode according to any one of claims 1 to 5,
A negative electrode,
A non-aqueous electrolyte battery comprising: a non-aqueous electrolyte.   The non-aqueous electrolyte battery according to claim 6, wherein the negative electrode includes at least one selected from the group consisting of titanium oxide, lithium titanium composite oxide, and niobium titanium composite oxide.