JP6988896B2 - Negative electrode active material and its manufacturing method, batteries and electronic devices - Google Patents

Description

The present disclosure relates to a negative electrode active material and a method for producing the same, a battery and an electronic device.

In recent years, there is an urgent need to develop technology for increasing the capacity of lithium-ion secondary batteries. Si-based materials are being developed all over the world as negative electrode materials with higher capacities than carbon-based materials. Among Si-based materials, silicon oxide (SiO _x ) can be mentioned as one of the materials having the best cycle characteristics. The silicon oxide has an advantage that the stability of the Si—O—Si bond due to oxygen can suppress the structural collapse due to expansion and contraction. On the other hand, silicon oxide is known to have low initial charge / discharge efficiency.

Patent Document 1 proposes a technique of pre-doping lithium (Li) into a silicon oxide in order to suppress a decrease in initial charge / discharge efficiency. Specifically, a technique for inserting lithium into a silicon-based material while performing potential regulation and current regulation has been proposed.

In Patent Document 2, in order to suppress the progress of the irreversible reaction between the silicon oxide and the conduction ion such as lithium ion, the silicon oxide and the transition metal oxide are mixed and heat-treated in a non-oxidizing atmosphere. Therefore, a technique for producing a negative electrode active material containing a silicon oxide and a silicate compound has been proposed.

Japanese Unexamined Patent Publication No. 2015-11547 Japanese Unexamined Patent Publication No. 2013-8567

An object of the present disclosure is to provide a negative electrode active material capable of improving the initial charge / discharge efficiency, a method for producing the same, a battery, and an electronic device including the battery.

To solve the above problems, the first disclosure discloses at least one oxide of silicon dioxide and germanium dioxide and at least one of tin, zinc, lead, bismuth, indium, gold and cadmium. A first agglomerate containing the first element of the above and at least one second element of silicon and germanium, and containing the first element and the second element, is composed of the first agglomerate. Contains a mixture of crystalline or amorphous first micrograins containing the first element and crystalline or amorphous second micrograins containing the second element, the first micrograins and the first. the average size of the second fine particle is 2 nm Ri der hereinafter, the average size of the first small grains randomly picked ten first minute particle from a cross-sectional TEM images of the negative electrode active material, the first The area of the cross section of the micrograins was measured by image processing, and the diameter of each first micrograin was obtained from the area of the cross section of each first micrograin assuming that the cross section of the first micrograin was circular. The average size of the second micrograins is determined by arithmetically averaging the diameters of the 10 first micrograins obtained, and the average size of the second micrograins is 10 second micrograins randomly selected from the cross-sectional TEM image of the negative electrode active material. Is selected, the area of the cross section of each second micrograin is measured by image processing, and it is assumed that the cross section of the second micrograin is circular, and the area of each second micrograin is taken from the area of the cross section of each second micrograin. It determined the particle diameter, ten second diameter of the fine particles obtained are negative electrode active material that is determined by arithmetic average.

The second disclosure is at least one first element of tin, zinc, lead, bismuth, indium, gold, silver and cadmium, and at least one second element of silicon and germanium. Using a mixture containing an oxide of the second element of the seed as a vapor deposition source, which is solidified by immersing it in a solvent, a negative electrode active material is deposited on a substrate with an electron beam, and the deposited negative electrode active material is heat-treated. It is a method of manufacturing a negative electrode active material including.

The third disclosure is a battery comprising a negative electrode containing the negative electrode active material of the first disclosure, a positive electrode, and an electrolyte.

The fourth disclosure is an electronic device comprising the battery of the third disclosure and receiving power from the battery.

According to the present disclosure, the initial charge / discharge efficiency can be improved. The effects described herein are not necessarily limited, and may be any of the effects described in the present disclosure or an effect different from them.

It is sectional drawing which shows an example of the structure of the negative electrode active material which concerns on 1st Embodiment of this disclosure. It is sectional drawing which shows an example of the structure of the negative electrode active material which concerns on the modification of 1st Embodiment of this disclosure. It is sectional drawing which shows an example of the structure of the non-aqueous electrolyte secondary battery which concerns on 2nd Embodiment of this disclosure. FIG. 3 is an enlarged cross-sectional view showing a part of the wound type electrode body shown in FIG. It is an exploded perspective view which shows an example of the structure of the non-aqueous electrolyte secondary battery which concerns on 3rd Embodiment of this disclosure. FIG. 5 is a cross-sectional view taken along the line VI-VI of FIG. It is a block diagram which shows an example of the structure of the electronic device as an application example. It is a schematic diagram which shows an example of the structure of the vehicle as an application example. It is a schematic diagram which shows an example of the structure of the power storage system as an application example. FIG. 10 is a cross-sectional SEM image of Si particles doped with Sn by heat treatment at 800 ° C. FIG. 11A is a surface SEM image of a _{Sn-added SiO x thin film without heat treatment.} FIG. 11B is a surface SEM image of a _{Sn-added SiO x} thin film with heat treatment at 800 ° C. FIG. 12A is a graph showing the XPS spectrum inside the _{additive-free SiO x thin film.} FIG. 12B is a graph showing the XPS spectrum inside the _{Fe-added SiO x thin film.} FIG. 12C is a graph showing the XPS spectrum inside the _{Ni-added SiO x thin film.} FIG. 12D is a graph showing the XPS spectrum inside the _{Sn-added SiO x thin film.} FIG. 13A is a structural image diagram of the inside of an additive-free SiO _{x thin film with heat treatment.} FIG. 13B is a structural image diagram of the inside of the Fe-added SiO _{x thin film with heat treatment.} FIG. 13C is a structural image diagram of the inside of the Ni-added SiO _{x thin film with heat treatment.} FIG. 13D is a structural image diagram of the inside of the Sn-added SiO _{x thin film with heat treatment.} Ellingham diagram of Sn and Si (Gibbs free energy for oxygen). FIG. 15A is a low magnification TEM image of a _{Sn-added SiO x thin film without heat treatment.} FIG. 15B is a low-magnification TEM image of a _{Sn-added SiO x thin film with heat treatment.} FIG. 16A is a high-magnification TEM image of an additive-free SiO _x thin film (with heat treatment at 800 ° C.). 16B is an FFT image of the high magnification TEM image of FIG. 16A. FIG. 17A is _{a high-magnification TEM image of a Sn-added SiO x} thin film (with heat treatment at 800 ° C.). FIG. 17B is an FFT image of the high magnification TEM image of FIG. 17A. It is a figure which shows STEM-EDX mapping of Sn addition SiO _{x thin film (with heat treatment at 800 degreeC).} FIG. 19A is _{a STEM-HAADF image of a Sn-added SiO x} thin film (with heat treatment at 800 ° C.). FIG. 19B is a diagram in which _{a STEM image of a Sn-added SiO x} thin film (with heat treatment at 800 ° C.) and a Sn element map are overlaid.

The embodiments and application examples of the present disclosure will be described in the following order.
1 First embodiment (example of negative electrode active material)
2 Second embodiment (example of cylindrical battery)
3 Third embodiment (example of laminated film type battery)
4 Application example 1 (example of battery pack and electronic device)
5 Application example 2 (example of vehicle)
6 Application example 3 (example of power storage system)

<1 First Embodiment>
[Construction of negative electrode active material]
The negative electrode active material according to the first embodiment of the present disclosure includes powder of negative electrode active material particles. This negative electrode active material is for a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. As shown in FIG. 1, the negative electrode active material particles include a matrix 111 and an aggregate 112 dispersed in the matrix 111.

The matrix 111 contains an oxide of at least one of silicon dioxide and germanium dioxide. Here, the silicon dioxide includes those having a slight oxygen deficiency, and specifically, those represented by the average composition SiO _2-x (x is 0 ≦ x ≦ 0.5). It shall be. Further, germanium dioxide includes those having a slight oxygen deficiency, and specifically, those represented by the average composition GeO _2-y (y is 0 ≦ y ≦ 0.5). It shall be. The average composition can be measured by, for example, X-ray Photoelectron Spectroscopy (XPS). The matrix 111 is preferably amorphous. This is because it is possible to suppress the structural collapse of the negative electrode active material particles due to expansion and contraction. It can be confirmed that the matrix 111 is amorphous by observing the cross section of the negative electrode active material particles by TEM (Transmission Electron Microscope).

The aggregate 112 is the first element of at least one of tin (Sn), zinc (Zn), lead (Pb), bismuth (Bi), indium (In), gold (Au) and cadmium (Cd). Metal element) is included. The first element may constitute a metallic phase. The first element is difficult to form bonds with silicon and germanium (second element) and can diffuse in silicon, germanium, silicon oxide and germanium oxide (second element and its oxides). It has the characteristic of being difficult.

The average size of the aggregate 112 is preferably 10 nm or less. If the average size of the agglomerates 112 exceeds 10 nm, the amount of expansion displacement of the agglomerates 112 may increase and the cycle characteristics may deteriorate. The lower limit of the average size of the aggregate 112 is not particularly limited, but is, for example, 2 nm or more.

The average size of the aggregate 112 is determined as follows. First, a cross section of the negative electrode active material particles is cut out by a focused ion beam (FIB). Next, using TEM, a cross-sectional TEM image of the negative electrode active material particles was photographed, 10 aggregates 112 were randomly selected from the photographed TEM images, and the cross-sectional area of the aggregates 112 was measured by image processing. The particle size (diameter) of each particle is determined on the assumption that the cross section of the aggregate 112 is circular. Subsequently, the particle size of the obtained 10 particles is simply averaged (arithmetic mean) to obtain the average particle size, which is used as the average size of the aggregate 112.

The aggregate 112 is preferably in an amorphous state or a mixed state of an amorphous phase and a crystalline phase. In the above mixed state, the crystalline phase may be fine crystal grains. In this case, the average size of the crystal grains is, for example, 2 nm or less. When the aggregate 112 is in an amorphous state or a mixed state as described above, it is possible to suppress the structural collapse of the negative electrode active material particles due to expansion and contraction. The fact that the aggregate 112 is in an amorphous state or a mixed state can be confirmed by TEM observation of the cross section of the negative electrode active material particles. Further, the average size of the crystal grains is obtained by the same calculation method as the above-mentioned average size of the aggregate 112.

At least one of the matrix 111 and the aggregate 112 contains at least one second element (semiconductor element) of silicon (Si) and germanium (Ge). When the aggregate 112 contains the second element, the first element and the second element do not form a bond. The aggregate 112 containing the first element and the second element is (a) an amorphous phase containing the first element and the second element, or (b) a crystalline or amorphous first containing the first element. It contains a mixture of the fine particles of 1 and the crystalline or amorphous second fine particles containing the second element. The average size of the first and second fine particles is, for example, 2 nm or less. The average size of the first and second fine particles is obtained by the same calculation method as the average size of the aggregate 112 described above. When the agglomerate 112 contains (a) an amorphous phase containing the first element and the second element, the amorphous phase is an amorphous phase containing the first element and an amorphous phase containing the second element. It may be a mixture with a phase.

When the matrix 111 contains a second element, the second element may be dispersed in the matrix 111. The second element may form fine particles having an average size of 2 nm or less, and the fine particles may be dispersed in the matrix 111. The fine particles may be crystalline or amorphous, but are preferably amorphous. This is because it is possible to suppress the structural collapse of the negative electrode active material particles due to expansion and contraction. The average size of the fine particles is obtained by the same calculation method as the average size of the aggregate 112 described above. Further, it can be confirmed by TEM observation of the cross section of the negative electrode active material particles that the fine particles are amorphous.

The content of the first element with respect to the total amount of the first element, the second element and oxygen is preferably 30 at% or more and 70 at% or less. The content of the second element with respect to the total amount of the first element, the second element and oxygen is preferably 1 at% or more and 50 at% or less. The oxygen content with respect to the total amount of the first element, the second element and the oxygen is preferably 20 at% or more and 70 at% or less. The contents of the first and second elements and oxygen can be measured by XPS.

The negative electrode active material particles do not contain the first compound in which the first element and the second element are bonded, and the second compound in which the first element and oxygen are bonded. This is because the first element usually does not form a bond with the second element, and the first element and oxygen do not form a bond with the negative electrode active material manufacturing method described later. .. When the second element is silicon, the first compound is a silicide compound and the second compound is a silicate compound.

When the first element contains tin, the negative electrode active material has a peak top in the range of binding energy 484 eV or more and 486 eV or less in the Sn3d waveform obtained from XPS. A peak having a peak top in the range of binding energy of 484 eV or more and 486 eV or less is a peak caused by Sn—Sn coupling.

[Manufacturing method of negative electrode active material]
Hereinafter, an example of a method for producing a negative electrode active material according to the first embodiment will be described. This method for producing a negative electrode active material is to synthesize a negative electrode active material by using a co-deposited method.

First, a powder of at least one first element of tin, zinc, lead, bismuth, indium, gold, silver and cadmium, a powder of at least one second element of silicon and germanium, and at least the powder of the second element. Mix with the oxide of one second element to obtain a mixture. Next, this mixture is immersed in a solvent such as water, uniformly dispersed by an ultrasonic cleaner or the like, and then the solvent is dried to obtain a solidified mixture. When the powder immersed in the liquid solidifies, the surface tension generates a capillary suction force generated between the particles. Due to this capillary suction force, the powder as a vapor deposition material is solidified in a uniform state. The smaller the particle size of the powder of the first element, the smaller the splash (melted particles ejected by non-uniform evaporation), and the more uniform the film becomes. Among the first elements, those having a particularly low melting point are preferably powders having a small particle size of 5 μm or less.

Subsequently, a thin film is deposited on the substrate by a co-deposited method using the solidified mixture as a vapor deposition source. Specifically, the solidified mixture is placed in a crucible in a vacuum chamber, and the mixture is heated and evaporated by an electron beam and deposited on a substrate facing the crucible. As a result, a thin film (negative electrode active material layer) can be obtained.

Then, the obtained thin film is heat-treated. When the thin film _{contains silicon oxide (SiO x} ), silicon oxide is changed to silicon dioxide by the action of the first element during the heat treatment. When the thin film _{contains germanium oxide (GeO x} ), germanium oxide is changed to germanium dioxide by the action of the first element during the heat treatment. Further, during the heat treatment, the first element aggregates in the thin film to form an aggregate 112. By this aggregation, the first element may form a metallic phase.

The temperature of the heat treatment is preferably 600 ° C. or higher, more preferably 730 ° C. or higher, in order to promote the change _{from silicon oxide (SiO x} ) to silicon dioxide and _{from germanium oxide (GeO x) to germanium dioxide.} Even more preferably 800 ° C. or higher, particularly preferably 900 ° C. or higher. Finally, the thin film is peeled off from the substrate and crushed. As a result, a powdery negative electrode active material can be obtained.

[effect]
In the negative electrode active material particles according to the first embodiment, the matrix 111 contains at least one of silicon dioxide and germanium dioxide. Since silicon dioxide and germanium dioxide are in a stable or nearly stable state, the reactivity between lithium and oxygen is reduced, and lithium loss is reduced. Therefore, the initial charge / discharge efficiency can be improved.

On the other hand, the negative electrode active material of Patent Document 2 _{contains a silicon oxide represented by the general formula SiO x} (0 <x <2) and a silicate compound. Further, in Patent Document 2, _{by coexisting the silicon oxide SiO x} and the silicate compound in this way, it is possible to prevent the entry of conduction ions into the Si defect, and the progress of a chained irreversible reaction is effective. This can suppress _{irreversible side reactions between SiO x} and conduction ions such as lithium ions.

Therefore, the negative electrode active material according to the first embodiment and the negative electrode active material of Patent Document 2 have different configurations and mechanisms for improving the initial charge / discharge efficiency.

In the negative electrode active material of Patent Document 1, since oxygen sites and lithium are bonded to each other, lithium may elute to the outside of the particles and the safety may be lowered. On the other hand, in the negative electrode active material according to the first embodiment, since oxygen sites and lithium are not bonded, lithium does not elute to the outside of the particles. Therefore, the initial charge / discharge efficiency can be improved, and the safety of the negative electrode active material can be improved.

Further, since the aggregate 112 contains at least one first element of tin, zinc, lead, bismuth, indium, gold and cadmium, it functions as an active material. Therefore, it is possible to suppress the volume decrease due to the addition of the first element.

In the method for producing a negative electrode active material according to the first embodiment, when the thin film formed by the co-deposition method _{contains silicon oxide (SiO x} ), when the thin film is heat-treated, the action of the first element is applied. Changes silicon oxide to silicon dioxide. When the thin film formed by the co-deposited method _{contains germanium oxide (GeO x} ), when the thin film is heat-treated, the germanium oxide is changed to germanium dioxide by the action of the first element.

Further, during the heat treatment of the negative electrode active material, the first element aggregates in the thin film to form an aggregate 112. Further, the first element suppresses the crystallization of the second element in the thin film or the enlargement of the crystal grains containing the second element. Therefore, even when crystal grains containing the second element are formed, it is possible to suppress an increase in the amount of expansion and displacement of the crystal grains. Therefore, the cycle characteristics can be improved.

Since the crystal containing the second element has low electron conductivity, if the crystal grains containing the second element become enlarged, the load characteristics may deteriorate. However, the first element contains the second element as described above. By suppressing the enlargement of the crystal grains, it is possible to suppress the deterioration of the load characteristics. Further, by suppressing the enlargement of the crystal containing the second element, it is possible to suppress the decrease in the number of nanoparticles containing the second element, which is a lithium ion path.

Since the first element is a metal element and the second element is a semiconductor element, the first element has higher electron conductivity than the second element. Therefore, when the negative electrode active material contains the first element, the electron conductivity of the negative electrode active material can be improved, and good current collecting property can be obtained. Therefore, the load characteristics can be improved.

[Modification example]
As shown in FIG. 2, the negative electrode active material particles may further contain the aggregate 113 dispersed in the matrix 111. The aggregate 113 contains at least one second element of silicon and germanium. The aggregate 113 is preferably in an amorphous state or a mixed state of an amorphous phase and a crystalline phase. In the above mixed state, the crystalline phase may be fine crystal grains. In this case, the average size of the crystal grains is, for example, 2 nm or less. When the aggregate 113 is in an amorphous state or a mixed state as described above, it is possible to suppress the structural collapse of the negative electrode active material particles due to expansion and contraction. The fact that the aggregate 113 is in an amorphous state or a mixed state can be confirmed by TEM observation of the cross section of the negative electrode active material particles. Further, the average size of the crystal grains is obtained by the same calculation method as the above-mentioned average size of the aggregate 112.

The average size of the aggregate 113 is preferably 10 nm or less. If the average size of the agglomerates 113 exceeds 10 nm, the amount of expansion displacement of the agglomerates 113 may increase and the cycle characteristics may deteriorate. The lower limit of the average size of the aggregate 113 is not particularly limited, but is, for example, 2 nm or more. The average size of the aggregate 113 is obtained by the same calculation method as the above-mentioned average size of the aggregate 112.

The shape of the negative electrode active material is not limited to the powder shape, but may be a thin film shape, a block shape, or the like.

A thin film electrode (negative electrode) is formed by using a negative electrode current collector as a substrate on which a thin film (negative electrode active material layer) is deposited and directly forming a thin film (negative electrode active material layer) on the negative electrode current collector by a co-deposited method. You may make it. In this case, the negative electrode active material layer can be formed without using a binder or a conductive auxiliary agent.

In the above-mentioned first embodiment, the case where the powdery negative electrode active material is obtained by crushing the thin film has been described, but the powdery negative electrode active material may be synthesized by the co-deposited method. More specifically, the chamber of the vacuum vapor deposition apparatus may be configured to be coolable, and the mixture as the vapor deposition source may be evaporated and cooled and aggregated to synthesize a powdery negative electrode active material.

In the first embodiment described above, the case where the mixture (deposited source) is heated by the electron beam has been described, but the mixture (deposited source) may be heated by a heating means other than the electron beam. However, a heating means capable of heating the mixture (deposited source) up to 1700 ° C. is preferable. On the Ellingham diagram showing the reactivity with oxygen, the temperature can be lowered to about 1100 ° C by mixing with a foreign element such as carbon or metal, and the heating temperature is not limited to 1700 ° C. ..

In the process of manufacturing the negative electrode active material, the particle size of the powder of the first element is preferably 10 μm or less. This is because it is possible to suppress the generation of metal droplets (particles of a single molten metal). The forms of the first, second and second element oxides are preferably, but not limited to, powdery as in the first embodiment described above.

In the above-mentioned first embodiment, the case where the powder of the first element, the powder of the second element, and the powder of the oxide of the second element are mixed to prepare a vapor deposition source has been described. The production method is not limited to this. For example, in place of or with the powder of the first element, oxides, nitrides, chlorides, carbides, sulfides, bromides, fluorides, iodides, sulfates, carbonates of the first element. , Nitrate, acetate and at least one powder of organic metal may be used. Further, a metal silicide may be used instead of silicon as the second element, or a metal silicate may be used instead of silicon dioxide as the oxide of the second element.

In the first embodiment described above, the case where the thin film formed on the substrate is heat-treated has been described. However, after the thin film is crushed to produce a powdery negative electrode active material, the powdery negative electrode active material is produced. The heat treatment may be performed on the film.

<2 Second Embodiment>
In the second embodiment, the secondary battery including the negative electrode containing the negative electrode active material according to the first embodiment described above will be described.

[Battery configuration]
Hereinafter, an example of the configuration of the non-aqueous electrolyte secondary battery (hereinafter, simply referred to as “battery”) according to the second embodiment of the present disclosure will be described with reference to FIG. This battery is, for example, a so-called lithium ion secondary battery in which the capacity of the negative electrode is represented by a capacity component due to occlusion and release of lithium, which is an electrode reactant. This battery is a so-called cylindrical type, and a pair of strip-shaped positive electrodes 21 and strip-shaped negative electrodes 22 are laminated and wound inside a substantially hollow cylindrical battery can 11 via a separator 23. It has a mold electrode body 20. The battery can 11 is made of nickel-plated iron (Fe), one end of which is closed and the other end of which is open. An electrolytic solution as a liquid electrolyte is injected into the inside of the battery can 11 and impregnated into the positive electrode 21, the negative electrode 22 and the separator 23. Further, a pair of insulating plates 12 and 13 are arranged perpendicular to the winding peripheral surface so as to sandwich the winding type electrode body 20.

At the open end of the battery can 11, a battery lid 14, a safety valve mechanism 15 provided inside the battery lid 14, and a heat-sensitive temperature coefficient (PTC element) 16 are interposed via a sealing gasket 17. It is attached by being crimped. As a result, the inside of the battery can 11 is sealed. The battery lid 14 is made of, for example, the same material as the battery can 11. The safety valve mechanism 15 is electrically connected to the battery lid 14, and when the internal pressure of the battery exceeds a certain level due to an internal short circuit or external heating, the disk plate 15A is inverted and wound around the battery lid 14. The electrical connection with the rotary electrode body 20 is cut off. The sealing gasket 17 is made of, for example, an insulating material, and the surface thereof is coated with asphalt.

For example, a center pin 24 is inserted in the center of the wound electrode body 20. A positive electrode lead 25 made of aluminum (Al) or the like is connected to the positive electrode 21 of the wound electrode body 20, and a negative electrode lead 26 made of nickel (Ni) or the like is connected to the negative electrode 22. The positive electrode lead 25 is electrically connected to the battery lid 14 by being welded to the safety valve mechanism 15, and the negative electrode lead 26 is welded to the battery can 11 and electrically connected.

Hereinafter, the positive electrode 21, the negative electrode 22, the separator 23, and the electrolytic solution constituting the battery will be sequentially described with reference to FIG.

(Positive electrode)
The positive electrode 21 has, for example, a structure in which positive electrode active material layers 21B are provided on both sides of the positive electrode current collector 21A. Although not shown, the positive electrode active material layer 21B may be provided on only one side of the positive electrode current collector 21A. The positive electrode current collector 21A is made of, for example, a metal foil such as an aluminum foil, a nickel foil, or a stainless steel foil. The positive electrode active material layer 21B contains a positive electrode active material capable of occluding and releasing lithium. The positive electrode active material layer 21B may further contain at least one of a conductive agent and a binder, if necessary.

(Positive electrode active material)
As the positive electrode active material, for example, a lithium-containing compound such as a lithium oxide, a lithium phosphorus oxide, a lithium sulfide, or an interlayer compound containing lithium is suitable, and two or more of these may be mixed and used. In order to increase the energy density, a lithium-containing compound containing lithium, a transition metal element and oxygen is preferable. Examples of such a lithium-containing compound include a lithium composite oxide having a layered rock salt type structure represented by the formula (A), a lithium composite phosphate having an olivine type structure represented by the formula (B), and the like. Can be mentioned. The lithium-containing compound is more preferably one containing at least one of the group consisting of cobalt (Co), nickel, manganese (Mn) and iron as a transition metal element. Examples of such a lithium-containing compound include a lithium composite oxide having a layered rock salt type structure represented by the formula (C), the formula (D) or the formula (E), and a spinel type represented by the formula (F). Examples thereof include a lithium composite oxide having a structure, a lithium composite phosphate having an olivine-type structure represented by the formula (G), and specifically, LiNi _0.50 Co _0.20 Mn _0.30 O ₂ , Li _a CoO _{2. (a ≒ 1), Li b} NiO 2 (b ≒ 1), Li c1 Ni c2 Co 1-c2 O 2 (c1 ≒ 1,0 <c2 <1), Li d Mn 2 O 4 (d ≒ 1) or There are Li _e FePO ₄ (e≈1) and the like.

Li _p Ni _(1-qr) Mn _q M1 _r O _(2-y) X _z ... (A)
(However, in the formula (A), M1 represents at least one of the elements selected from Group 2 to Group 15 excluding nickel and manganese. X is at least one of Group 16 and Group 17 elements other than oxygen. Indicates a species. p, q, y, z are 0 ≦ p ≦ 1.5, 0 ≦ q ≦ 1.0, 0 ≦ r ≦ 1.0, −0.10 ≦ y ≦ 0.20, 0 ≦ It is a value within the range of z ≦ 0.2.)

Li _a M2 _b PO ₄ ... (B)
(However, in the formula (B), M2 represents at least one of the elements selected from groups 2 to 15. a and b are 0 ≦ a ≦ 2.0 and 0.5 ≦ b ≦ 2.0. It is a value within the range of.)

Li _f Mn _(1-gh) Ni _g M3 _h O _(2-j) F _k ... (C)
(However, in the formula (C), M3 is cobalt, magnesium (Mg), aluminum, boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron, copper (Cu), zinc, Represents at least one of the group consisting of zirconium (Zr), molybdenum (Mo), tin, calcium (Ca), strontium (Sr) and tungsten (W). F, g, h, j and k are 0. .8 ≤ f ≤ 1.2, 0 <g <0.5, 0 ≤ h ≤ 0.5, g + h <1, -0.1 ≤ j ≤ 0.2, 0 ≤ k ≤ 0.1 The composition of lithium differs depending on the state of charge and discharge, and the value of f represents the value in the state of complete discharge.)

Li _m Ni _(1-n) M4 _n O _(2-p) F _q ... (D)
(However, in formula (D), M4 is at least in the group consisting of cobalt, manganese, magnesium, aluminum, boron, titanium, vanadium, chromium, iron, copper, zinc, molybdenum, tin, calcium, strontium and tungsten. Represents one type. M, n, p and q are 0.8 ≦ m ≦ 1.2, 0.005 ≦ n ≦ 0.5, −0.1 ≦ p ≦ 0.2, 0 ≦ q ≦ 0. The value is within the range of 1. The composition of lithium differs depending on the state of charge and discharge, and the value of m represents the value in the state of complete discharge.)

Li _r Co _(1-s) M5 _s O _{(2-t) Fu} ... (E)
(However, in formula (E), M5 is at least in the group consisting of nickel, manganese, magnesium, aluminum, boron, titanium, vanadium, chromium, iron, copper, zinc, molybdenum, tin, calcium, strontium and tungsten. Represents one type. R, s, t and u are 0.8 ≦ r ≦ 1.2, 0 ≦ s <0.5, −0.1 ≦ t ≦ 0.2, 0 ≦ u ≦ 0.1. The composition of lithium differs depending on the state of charge and discharge, and the value of r represents the value in the state of complete discharge.)

Li _v Mn _2-w M6 _w O _x F _y ... (F)
(However, in formula (F), M6 is at least in the group consisting of cobalt, nickel, magnesium, aluminum, boron, titanium, vanadium, chromium, iron, copper, zinc, molybdenum, tin, calcium, strontium and tungsten. Represents one type. V, w, x and y are 0.9 ≦ v ≦ 1.1, 0 ≦ w ≦ 0.6, 3.7 ≦ x ≦ 4.1, 0 ≦ y ≦ 0.1. It is a value within the range. The composition of lithium differs depending on the state of charge and discharge, and the value of v represents the value in the state of complete discharge.)

Li _z M7PO ₄ ... (G)
(However, in formula (G), M7 is composed of cobalt, manganese, iron, nickel, magnesium, aluminum, boron, titanium, vanadium, niobium (Nb), copper, zinc, molybdenum, calcium, strontium, tungsten and zirconium. Represents at least one of the groups. Z is a value within the range of 0.9 ≦ z ≦ 1.1. The composition of lithium differs depending on the state of charge and discharge, and the value of z is the state of complete discharge. Represents the value in.)

Examples of the lithium composite oxide containing Ni include a lithium composite oxide containing lithium, nickel, cobalt, manganese and oxygen (NCM), and a lithium composite oxide containing lithium, nickel, cobalt, aluminum and oxygen (NCA). May be used. Specifically, as the lithium composite oxide containing Ni, those represented by the following formula (H) or formula (I) may be used.

Li _v1 Ni _{w1 M1'x1} O _z1・ ・ ・ (H)
(In the formula, 0 <v1 <2, w1 + x1 ≦ 1, 0.2 ≦ w1 ≦ 1, 0 ≦ x1 ≦ 0.7, 0 <z <3, and M1 ′ is cobalt, iron, manganese, copper, At least one element composed of transition metals such as zinc, aluminum, chromium, vanadium, titanium, magnesium and zirconium.)

Li _v2 Ni _{w2 M2'x2} O _z2・ ・ ・ (I)
(In the formula, 0 <v2 <2, w2 + x2 ≦ 1, 0.65 ≦ w2 ≦ 1, 0 ≦ x2 ≦ 0.35, 0 <z2 <3, and M2'is cobalt, iron, manganese, copper, At least one element composed of transition metals such as zinc, aluminum, chromium, vanadium, titanium, magnesium and zirconium.)

Other positive electrode materials capable of occluding and releasing lithium include lithium-free inorganic compounds such as _{MnO 2} , V ₂ O ₅ , V ₆ O _{13, NiS, and MoS.}

The positive electrode material capable of occluding and releasing lithium may be other than the above. Further, the positive electrode materials exemplified above may be mixed in any combination of two or more.

(Binder)
Examples of the binder include resin materials such as polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), polyacrylonitrile (PAN), styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC), and resins thereof. At least one selected from a material-based copolymer and the like is used.

(Conducting agent)
Examples of the conductive agent include carbon materials such as graphite, carbon fiber, carbon black, Ketjen black or carbon nanotubes, and one of these may be used alone or two or more thereof may be mixed. May be used. Further, in addition to the carbon material, a metal material, a conductive polymer material, or the like may be used as long as it is a conductive material.

(Negative electrode)
The negative electrode 22 has, for example, a structure in which the negative electrode active material layers 22B are provided on both sides of the negative electrode current collector 22A. Although not shown, the negative electrode active material layer 22B may be provided on only one side of the negative electrode current collector 22A. The negative electrode current collector 22A is made of, for example, a metal foil such as a copper foil, a nickel foil, or a stainless steel foil.

The negative electrode active material layer 22B contains one or more negative electrode active materials capable of occluding and releasing lithium. The negative electrode active material layer 22B may further contain at least one of a binder and a conductive agent, if necessary.

In this battery, the electrochemical equivalent of the negative electrode 22 or the negative electrode active material is larger than the electrochemical equivalent of the positive electrode 21, and theoretically, lithium metal does not precipitate on the negative electrode 22 during charging. It is preferable to have.

(Negative electrode active material)
As the negative electrode active material, the negative electrode active material according to the first embodiment is used. The negative electrode active material according to the first embodiment may be used together with the carbon material. In this case, a high energy density can be obtained and excellent cycle characteristics can be obtained.

Examples of the carbon material used together with the negative electrode active material according to the first embodiment include graphitizable carbon, graphitizable carbon, graphite, thermally decomposed carbons, cokes, glassy carbons, and organic polymer compounds. Examples thereof include a calcined body, carbon fiber, and a carbon material such as activated carbon. Among these, cokes include pitch coke, needle coke, petroleum coke and the like. A calcined organic polymer compound is a material obtained by calcining a polymer material such as phenol formaldehyde or furan resin at an appropriate temperature to carbonize it, and some of it is non-graphitizable carbon or easily graphitizable carbon. Some are classified as. These carbon materials are preferable because the change in the crystal structure that occurs during charging / discharging is very small, a high charging / discharging capacity can be obtained, and good cycle characteristics can be obtained. In particular, graphite is preferable because it has a large electrochemical equivalent and can obtain a high energy density. Further, graphitizable carbon is preferable because excellent cycle characteristics can be obtained. Furthermore, those having a low charge / discharge potential, specifically those having a charge / discharge potential close to that of lithium metal, are preferable because high energy density of the battery can be easily realized.

(Binder)
As the binder, for example, at least one selected from resin materials such as polyvinylidene fluoride, polytetrafluoroethylene, polyacrylonitrile, styrene butadiene rubber and carboxymethyl cellulose, and copolymers mainly composed of these resin materials. Is used.

(Conducting agent)
Examples of the conductive agent include carbon materials such as graphite, carbon fiber, carbon black, Ketjen black or carbon nanotubes, and one of these may be used alone or two or more thereof may be mixed. May be used. Further, in addition to the carbon material, a metal material, a conductive polymer material, or the like may be used as long as it is a conductive material.

(Separator)
The separator 23 separates the positive electrode 21 and the negative electrode 22 and allows lithium ions to pass through while preventing a short circuit of current due to contact between the two electrodes. The separator 23 is made of, for example, a porous film made of a resin such as polytetrafluoroethylene, polypropylene, or polyethylene, and may have a structure in which two or more of these porous films are laminated. Above all, the porous film made of polyolefin is preferable because it has an excellent short-circuit prevention effect and can improve the safety of the battery by the shutdown effect. In particular, polyethylene is preferable as a material constituting the separator 23 because it can obtain a shutdown effect in the range of 100 ° C. or higher and 160 ° C. or lower and is also excellent in electrochemical stability. In addition, a material obtained by copolymerizing or blending a resin having chemical stability with polyethylene or polypropylene can be used. Alternatively, the porous membrane may have a structure of three or more layers in which a polypropylene layer, a polyethylene layer, and a polypropylene layer are sequentially laminated.

The separator 23 may have a structure including a base material and a surface layer provided on one side or both sides of the base material. The surface layer contains inorganic particles having an electrically insulating property and a resin material that binds the inorganic particles to the surface of the base material and also binds the inorganic particles to each other. This resin material may have, for example, a three-dimensional network structure in which fibrils are formed and the fibrils are continuously connected to each other. By being supported on the resin material having this three-dimensional network structure, the inorganic particles can maintain a dispersed state without being connected to each other. Further, the resin material may be bonded to the surface of the base material or the inorganic particles without being made into fibril. In this case, higher binding properties can be obtained. By providing the surface layer on one side or both sides of the base material as described above, oxidation resistance, heat resistance and mechanical strength can be imparted to the base material.

The base material is a porous layer having porosity. More specifically, the base material is a porous membrane composed of an insulating membrane having a large ion permeability and a predetermined mechanical strength, and the electrolytic solution is held in the pores of the base material. It is preferable that the base material has a predetermined mechanical strength as a main part of the separator, but has high resistance to an electrolytic solution, low reactivity, and resistance to expansion.

As the resin material constituting the base material, for example, it is preferable to use a polyolefin resin such as polypropylene or polyethylene, an acrylic resin, a styrene resin, a polyester resin, a nylon resin or the like. In particular, polyethylene such as low-density polyethylene, high-density polyethylene and linear polyethylene, or their low-molecular-weight wax components, or polyolefin resins such as polypropylene are preferably used because they have an appropriate melting temperature and are easily available. Further, a structure in which these two or more kinds of porous films are laminated, or a porous film formed by melt-kneading two or more kinds of resin materials may be used. Those containing a porous film made of a polyolefin resin have excellent separability between the positive electrode 21 and the negative electrode 22, and can further reduce the decrease in internal short circuit.

As the base material, a non-woven fabric may be used. As the fiber constituting the non-woven fabric, aramid fiber, glass fiber, polyolefin fiber, polyethylene terephthalate (PET) fiber, nylon fiber and the like can be used. Further, these two or more kinds of fibers may be mixed to form a nonwoven fabric.

The inorganic particles contain at least one kind such as a metal oxide, a metal nitride, a metal carbide and a metal sulfide. Metal oxides include aluminum oxide (alumina, Al ₂ O ₃ ), boehmite (hydrated aluminum oxide), magnesium oxide (magnesia, MgO), titanium oxide (titania, TiO ₂ ), zirconium oxide (zirconia, ZrO _2). ), Silicon oxide (silica, SiO ₂ ), yttrium oxide (itria, Y ₂ O ₃ ) and the like can be preferably used. As the metal nitride, silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), boron nitride (BN), titanium nitride (TiN) and the like can be preferably used. As the metal carbide, silicon carbide (SiC), boron carbide (B4C) or the like can be preferably used. As the metal sulfide, barium sulfate (BaSO ₄ ) or the like can be preferably used. In addition, _{porous aluminosilicates such as zeolite (M 2 / n} O, Al ₂ O ₃ , xSiO ₂ , yH ₂ O, M is a metal element, x ≧ 2, y ≧ 0), layered silicate, and barium titanate. Minerals such as barium (BaTIO ₃ ) or strontium titanate (SrTiO ₃ ) may be used. Of these, alumina, titania (particularly those having a rutile-type structure), silica or magnesia are preferably used, and alumina is more preferable. The inorganic particles have oxidation resistance and heat resistance, and the surface layer on the side surface facing the positive electrode containing the inorganic particles has strong resistance to the oxidizing environment in the vicinity of the positive electrode during charging. The shape of the inorganic particles is not particularly limited, and any of spherical, plate-like, fibrous, cubic, random and the like can be used.

Examples of the resin material constituting the surface layer include fluororesins such as polyvinylidene fluoride and polytetrafluoroethylene, fluororubber containing vinylidene fluoride-tetrafluoroethylene copolymer, and fluororubber such as ethylene-tetrafluoroethylene copolymer, and styrene. -Butadiene copolymer or its hydride, acrylonitrile-butadiene copolymer or its hydride, acrylonitrile-butadiene-styrene copolymer or its hydride, methacrylic acid ester-acrylic acid ester copolymer, styrene-acrylic acid ester Copolymers, acrylonitrile-acrylic acid ester copolymers, rubbers such as ethylene propylene rubber, polyvinyl alcohol, vinyl acetate, cellulose derivatives such as ethyl cellulose, methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, polyphenylene ether, polysulfone, polyether sulfone , Polyphenylene sulfide, polyetherimide, polyimide, polyamide such as total aromatic polyamide (aramid), polyamideimide, polyacrylonitrile, polyvinyl alcohol, polyether, acrylic acid resin or polyester, etc. Examples thereof include resins having high heat resistance of ° C. or higher. These resin materials may be used alone or in combination of two or more. Among them, a fluororesin such as polyvinylidene fluoride is preferable from the viewpoint of oxidation resistance and flexibility, and aramid or polyamide-imide is preferably contained from the viewpoint of heat resistance.

The particle size of the inorganic particles is preferably in the range of 1 nm to 10 μm. If it is smaller than 1 nm, it is difficult to obtain it, and even if it can be obtained, it is not worth the cost. On the other hand, if it is larger than 10 μm, the distance between the electrodes becomes large, the amount of active material filled cannot be sufficiently obtained in a limited space, and the battery capacity becomes low.

As a method for forming the surface layer, for example, a slurry composed of a matrix resin, a solvent and an inorganic substance is applied onto a base material (porous film), and the matrix resin is passed through a poor solvent and a parent solvent bath of the above solvent to form a phase. A method of separating and then drying can be used.

The above-mentioned inorganic particles may be contained in a porous membrane as a base material. Further, the surface layer may not contain inorganic particles and may be composed only of a resin material.

(Electrolytic solution)
The separator 23 is impregnated with an electrolytic solution which is a liquid electrolyte. The electrolytic solution contains a solvent and an electrolyte salt dissolved in the solvent. The electrolytic solution may contain known additives in order to improve the battery characteristics.

As the solvent, a cyclic carbonate ester such as ethylene carbonate or propylene carbonate can be used, and it is preferable to use one or a mixture of ethylene carbonate and propylene carbonate in particular. This is because the cycle characteristics can be improved.

As the solvent, in addition to these cyclic carbonate esters, it is preferable to mix and use a chain carbonate ester such as diethyl carbonate, dimethyl carbonate, ethylmethyl carbonate or methylpropyl carbonate. This is because high ionic conductivity can be obtained.

The solvent preferably further contains 2,4-difluoroanisole or vinylene carbonate. This is because 2,4-difluoroanisole can improve the discharge capacity, and vinylene carbonate can improve the cycle characteristics. Therefore, it is preferable to mix and use these because the discharge capacity and the cycle characteristics can be improved.

In addition to these, as solvents, butylene carbonate, γ-butyrolactone, γ-valerolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltransferase, 1,3-dioxolane, 4-methyl-1,3- Dioxolane, Methyl Acetate, Methyl Propionate, acetonitrile, Glutaronitrile, Adiponitrile, methoxynitrile, 3-methoxypropyronitrile, N, N-dimethylformamide, N-methylpyrrolidinone, N-methyloxazolidinone, N, N-dimethyl Examples thereof include imidazolidinone, nitromethane, nitroethane, sulfolane, dimethylsulfoxide, trimethyl phosphate and the like.

It should be noted that a compound in which at least a part of hydrogen in these non-aqueous solvents is replaced with fluorine may be preferable because the reversibility of the electrode reaction may be improved depending on the type of the electrode to be combined.

Examples of the electrolyte salt include lithium salts, and one type may be used alone or two or more types may be mixed and used. Lithium salts include LiPF ₆ , LiBF ₄ , _{LiAsF 6} , LiClO ₄ , LiB (C ₆ H ₅ ) ₄ , LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , LiN (SO ₂ CF ₃ ) ₂ , LiC (SO ₂ CF). ₃ ) ₃ , LiAlCl ₄ , LiSiF ₆ , LiCl, difluoro [oxorat-O, O'] lithium borate, lithium bisoxalate volate, LiBr and the like can be mentioned. Above all, LiPF ₆ is preferable because it can obtain high ionic conductivity and improve cycle characteristics.

[Positive potential]
The positive electrode potential (vsLi / Li ⁺ ) in the fully charged state preferably exceeds 4.20 V, more preferably 4.25 V or more, still more preferably more than 4.40 V, and particularly preferably 4.45 V or more, most preferably. Is 4.50V or higher. However, the positive electrode potential ( ^{vsLi / Li +} ) in the fully charged state may be 4.20 V or less. The upper limit of the positive electrode potential (vsLi / Li ⁺ ) in the fully charged state is not particularly limited, but is preferably 6.00 V or less, more preferably 5.00 V or less, and even more preferably 4.80 V or less. Particularly preferably, it is 4.70 V or less.

[Battery operation]
In the battery having the above configuration, when charging is performed, lithium ions are released from the positive electrode active material layer 21B and are occluded in the negative electrode active material layer 22B via the electrolytic solution. Further, when the electric discharge is performed, lithium ions are released from the negative electrode active material layer 22B and are occluded in the positive electrode active material layer 21B via the electrolytic solution.

[Battery manufacturing method]
Next, an example of a battery manufacturing method according to the second embodiment of the present disclosure will be described.

First, for example, a positive electrode active material, a conductive agent, and a binder are mixed to prepare a positive electrode mixture, and the positive electrode mixture is dispersed in a solvent such as N-methyl-2-pyrrolidone (NMP). A paste-like positive electrode mixture slurry is prepared. Next, this positive electrode mixture slurry is applied to the positive electrode current collector 21A, the solvent is dried, and the positive electrode active material layer 21B is formed by compression molding with a roll press machine or the like to form the positive electrode 21.

Further, for example, the negative electrode active material according to the first embodiment and the binder are mixed to prepare a negative electrode mixture, and the negative electrode mixture is dispersed in a solvent such as N-methyl-2-pyrrolidone. A paste-like negative electrode mixture slurry is prepared. In addition to the negative electrode active material and the binder according to the first embodiment, a carbon material may be further added and mixed. Next, this negative electrode mixture slurry is applied to the negative electrode current collector 22A, the solvent is dried, and compression molding is performed by a roll press machine or the like to form the negative electrode active material layer 22B, and the negative electrode 22 is manufactured.

Next, the positive electrode lead 25 is attached to the positive electrode current collector 21A by welding or the like, and the negative electrode lead 26 is attached to the negative electrode current collector 22A by welding or the like. Next, the positive electrode 21 and the negative electrode 22 are wound around the separator 23. Next, the tip of the positive electrode lead 25 is welded to the safety valve mechanism 15, the tip of the negative electrode lead 26 is welded to the battery can 11, and the wound positive electrode 21 and the negative electrode 22 are formed by a pair of insulating plates 12 and 13. It is stored inside the sandwiched battery can 11. Next, after the positive electrode 21 and the negative electrode 22 are housed inside the battery can 11, the electrolytic solution is injected into the inside of the battery can 11 to impregnate the separator 23. Next, the battery lid 14, the safety valve mechanism 15, and the heat-sensitive resistance element 16 are fixed to the open end of the battery can 11 by caulking via the sealing gasket 17. As a result, the battery shown in FIG. 3 is obtained.

[effect]
In the battery according to the second embodiment, since the positive electrode active material layer 21B contains the positive electrode active material according to the first embodiment, the initial charge / discharge efficiency can be improved.

[Modification example]
In the second embodiment, an example in which the negative electrode 22 is provided on both sides of the negative electrode current collector 22A and the negative electrode current collector 22A and includes the negative electrode active material layer 22B containing the powder of the negative electrode active material particles has been described. The configuration of the negative electrode 22 is not limited to this. For example, the negative electrode 22 may be a thin film electrode including a negative electrode current collector and thin films provided on both sides of the negative electrode current collector. The thin film is composed of a negative electrode active material. The negative electrode active material is the same as the negative electrode active material according to the first embodiment except that it has a thin film shape.

<3 Third embodiment>
[Battery configuration]
As shown in FIG. 5, the battery according to the third embodiment of the present disclosure is a so-called laminated film type battery, and the wound electrode body 30 to which the positive electrode lead 31 and the negative electrode lead 32 are attached has a film-like exterior. It is housed inside the member 40, and can be made smaller, lighter, and thinner.

The positive electrode lead 31 and the negative electrode lead 32 are respectively led out from the inside of the exterior member 40 toward the outside, for example, in the same direction. The positive electrode lead 31 and the negative electrode lead 32 are each made of a metal material such as aluminum, copper, nickel, or stainless steel, and have a thin plate shape or a mesh shape, respectively.

The exterior member 40 is made of, for example, a rectangular aluminum laminated film in which a nylon film, an aluminum foil, and a polyethylene film are bonded in this order. The exterior member 40 is arranged so that, for example, the polyethylene film side and the wound electrode body 30 face each other, and the outer edge portions thereof are brought into close contact with each other by fusion or adhesive. A close contact film 41 for preventing the intrusion of outside air is inserted between the exterior member 40 and the positive electrode lead 31 and the negative electrode lead 32. The adhesion film 41 is made of a material having adhesion to the positive electrode lead 31 and the negative electrode lead 32, for example, a polyolefin resin such as polyethylene, polypropylene, modified polyethylene or modified polypropylene.

The exterior member 40 may be made of a laminate film having another structure, a polymer film such as polypropylene, or a metal film instead of the aluminum laminate film described above. Alternatively, a laminated film in which an aluminum film is used as a core material and a polymer film is laminated on one side or both sides thereof may be used.

FIG. 6 is a cross-sectional view taken along the line VV of the wound electrode body 30 shown in FIG. The winding type electrode body 30 is formed by laminating and winding a positive electrode 33 and a negative electrode 34 via a separator 35 and an electrolyte layer 36, and the outermost peripheral portion thereof is protected by a protective tape 37.

The positive electrode 33 has a structure in which the positive electrode active material layer 33B is provided on one side or both sides of the positive electrode current collector 33A. The negative electrode 34 has a structure in which the negative electrode active material layer 34B is provided on one side or both sides of the negative electrode current collector 34A, and the negative electrode active material layer 34B and the positive electrode active material layer 33B are arranged so as to face each other. There is. The configurations of the positive electrode collector 33A, the positive electrode active material layer 33B, the negative electrode current collector 34A, the negative electrode active material layer 34B, and the separator 35 are the positive electrode current collector 21A, the positive electrode active material layer 21B, and the negative electrode, respectively, in the second embodiment. This is the same as the current collector 22A, the negative electrode active material layer 22B, and the separator 23.

The electrolyte layer 36 contains an electrolytic solution and a polymer compound serving as a retainer for holding the electrolytic solution, and is in the form of a so-called gel. The gel-like electrolyte layer 36 is preferable because it can obtain high ionic conductivity and can prevent liquid leakage from the battery. The electrolytic solution is the electrolytic solution according to the second embodiment. Examples of the polymer compound include polyacrylonitrile, polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, polyphosphazene, and polysiloxane. , Polyvinylacetate, polyvinyl alcohol, polymethylmethacrylate, polyacrylic acid, polymethacrylic acid, styrene-butadiene rubber, nitrile-butadiene rubber, polystyrene or polycarbonate. Particularly from the viewpoint of electrochemical stability, polyacrylonitrile, polyvinylidene fluoride, polyhexafluoropropylene or polyethylene oxide are preferable.

The electrolyte layer 36 may contain inorganic particles. This is because the heat resistance can be further improved. As the inorganic particles, the same inorganic particles contained in the surface layer of the separator 23 of the second embodiment can be used. Further, an electrolytic solution may be used instead of the electrolyte layer 36.

[Battery manufacturing method]
Next, an example of a battery manufacturing method according to the third embodiment of the present disclosure will be described.

First, a precursor solution containing a solvent, an electrolyte salt, a polymer compound, and a mixed solvent is applied to each of the positive electrode 33 and the negative electrode 34, and the mixed solvent is volatilized to form the electrolyte layer 36. Next, the positive electrode lead 31 is attached to the end of the positive electrode current collector 33A by welding, and the negative electrode lead 32 is attached to the end of the negative electrode current collector 34A by welding. Next, the positive electrode 33 and the negative electrode 34 on which the electrolyte layer 36 is formed are laminated via the separator 35 to form a laminated body, and then the laminated body is wound in the longitudinal direction thereof, and a protective tape 37 is placed on the outermost peripheral portion thereof. They are adhered to form a wound electrode body 30. Finally, for example, the wound electrode body 30 is sandwiched between the exterior members 40, and the outer edge portions of the exterior members 40 are brought into close contact with each other by heat fusion or the like and sealed. At that time, the adhesion film 41 is inserted between the positive electrode lead 31 and the negative electrode lead 32 and the exterior member 40. As a result, the batteries shown in FIGS. 5 and 6 can be obtained.

Further, this battery may be manufactured as follows. First, the positive electrode 33 and the negative electrode 34 are manufactured as described above, and the positive electrode lead 31 and the negative electrode lead 32 are attached to the positive electrode 33 and the negative electrode 34. Next, the positive electrode 33 and the negative electrode 34 are laminated and wound via the separator 35, and the protective tape 37 is adhered to the outermost peripheral portion to form a wound body. Next, the wound body is sandwiched between the exterior members 40, and the outer peripheral edge portion excluding one side is heat-sealed to form a bag shape, which is stored inside the exterior member 40. Next, an electrolyte composition containing a solvent, an electrolyte salt, a monomer as a raw material for a polymer compound, a polymerization initiator, and other materials such as a polymerization inhibitor, if necessary, is prepared, and an exterior member is prepared. Inject into the inside of 40.

Next, after the electrolyte composition is injected into the exterior member 40, the opening of the exterior member 40 is heat-sealed and sealed in a vacuum atmosphere. Next, heat is applied to polymerize the monomers to form a polymer compound, thereby forming a gel-like electrolyte layer 36. As a result, the batteries shown in FIGS. 5 and 6 can be obtained.

<4 Application example 1>
"Battery packs and electronic devices as application examples"
In Application Example 1, a battery pack and an electronic device including a battery according to a second or third embodiment will be described.

[Battery pack and electronic device configuration]
Hereinafter, a configuration example of the battery pack 300 and the electronic device 400 as application examples will be described with reference to FIG. 7. The electronic device 400 includes an electronic circuit 401 of the main body of the electronic device and a battery pack 300. The battery pack 300 is electrically connected to the electronic circuit 401 via the positive electrode terminal 331a and the negative electrode terminal 331b. The electronic device 400 has, for example, a configuration in which the battery pack 300 can be freely attached and detached by the user. The configuration of the electronic device 400 is not limited to this, and has a configuration in which the battery pack 300 is built in the electronic device 400 so that the battery pack 300 cannot be removed from the electronic device 400 by the user. You may.

When charging the battery pack 300, the positive electrode terminal 331a and the negative electrode terminal 331b of the battery pack 300 are connected to the positive electrode terminal and the negative electrode terminal of the charger (not shown), respectively. On the other hand, when the battery pack 300 is discharged (when the electronic device 400 is used), the positive electrode terminal 331a and the negative electrode terminal 331b of the battery pack 300 are connected to the positive electrode terminal and the negative electrode terminal of the electronic circuit 401, respectively.

Examples of the electronic device 400 include a notebook personal computer, a tablet computer, a mobile phone (for example, a smartphone), a personal digital assistant (PDA), a display device (LCD, EL display, electronic paper, etc.), and an image pickup. Devices (eg digital still cameras, digital video cameras, etc.), audio equipment (eg portable audio players), game equipment, cordless phone handsets, electronic books, electronic dictionaries, radios, headphones, navigation systems, memory cards, pacemakers, hearing aids, etc. Electric tools, electric shavers, refrigerators, air conditioners, TVs, stereos, water heaters, microwave ovens, dishwashers, washing machines, dryers, lighting equipment, toys, medical equipment, robots, road conditioners, traffic lights, etc. It is not limited to.

(Electronic circuit)
The electronic circuit 401 includes, for example, a CPU, a peripheral logic unit, an interface unit, a storage unit, and the like, and controls the entire electronic device 400.

(Battery pack)
The battery pack 300 includes an assembled battery 301 and a charge / discharge circuit 302. The assembled battery 301 is configured by connecting a plurality of secondary batteries 301a in series and / or in parallel. The plurality of secondary batteries 301a are connected, for example, in n parallel m series (n and m are positive integers). Note that FIG. 7 shows an example in which six secondary batteries 301a are connected in two parallels and three series (2P3S). As the secondary battery 301a, the battery according to the second or third embodiment is used.

Here, a case where the battery pack 300 includes an assembled battery 301 composed of a plurality of secondary batteries 301a will be described, but the battery pack 300 includes one secondary battery 301a instead of the assembled battery 301. It may be adopted.

The charge / discharge circuit 302 is a control unit that controls the charge / discharge of the assembled battery 301. Specifically, at the time of charging, the charging / discharging circuit 302 controls the charging of the assembled battery 301. On the other hand, at the time of discharging (that is, when the electronic device 400 is used), the charge / discharge circuit 302 controls the discharge to the electronic device 400.

<5 Application example 2>
"Power storage system in vehicles as an application example"
An example in which the present disclosure is applied to a power storage system for a vehicle will be described with reference to FIG. FIG. 8 schematically shows an example of a configuration of a hybrid vehicle that employs a series hybrid system to which the present disclosure applies. The series hybrid system is a vehicle that runs on a power drive power converter using the electric power generated by a generator powered by an engine or the electric power temporarily stored in a battery.

The hybrid vehicle 7200 includes an engine 7201, a generator 7202, a power driving force conversion device 7203, a drive wheel 7204a, a drive wheel 7204b, a wheel 7205a, a wheel 7205b, a battery 7208, a vehicle control device 7209, various sensors 7210, and a charging port 7211. Is installed. The above-mentioned power storage device of the present disclosure is applied to the battery 7208.

The hybrid vehicle 7200 travels by using the electric power driving force conversion device 7203 as a power source. An example of the power driving force conversion device 7203 is a motor. The electric power of the battery 7208 operates the electric power driving force conversion device 7203, and the rotational force of the electric power driving force conversion device 7203 is transmitted to the drive wheels 7204a and 7204b. By using direct current-AC (DC-AC) or reverse conversion (AC-DC conversion) at necessary locations, the power driving force conversion device 7203 can be applied to either an AC motor or a DC motor. The various sensors 7210 control the engine speed via the vehicle control device 7209, and control the opening degree (throttle opening degree) of a throttle valve (not shown). The various sensors 7210 include a speed sensor, an acceleration sensor, an engine speed sensor, and the like.

The rotational force of the engine 7201 is transmitted to the generator 7202, and the electric power generated by the generator 7202 by the rotational force can be stored in the battery 7208.

When the hybrid vehicle decelerates due to a braking mechanism (not shown), the resistance force during deceleration is applied to the power driving force conversion device 7203 as a rotational force, and the regenerative power generated by the power driving force conversion device 7203 by this rotational force is applied to the battery 7208. Accumulate.

By connecting the battery 7208 to an external power source of the hybrid vehicle, it is possible to receive electric power from the external power source using the charging port 211 as an input port and store the received electric power.

Although not shown, an information processing device that performs information processing related to vehicle control based on information related to the secondary battery may be provided. As such an information processing device, for example, there is an information processing device that displays the remaining battery level based on information on the remaining battery level.

In the above description, a series hybrid vehicle that runs on a motor using the electric power generated by the generator operated by the engine or the electric power temporarily stored in the battery has been described as an example. However, the present disclosure is also valid for a parallel hybrid vehicle in which the outputs of the engine and the motor are used as drive sources, and the three methods of running only with the engine, running only with the motor, and running with the engine and the motor are appropriately switched. Applicable. Further, the present disclosure can be effectively applied to a so-called electric vehicle that travels by being driven only by a drive motor without using an engine.

The example of the hybrid vehicle 7200 to which the technology according to the present disclosure can be applied has been described above. The technique according to the present disclosure can be suitably applied to the battery 7208 among the configurations described above.

<6 Application example 3>
"Power storage system in a house as an application example"
An example of applying the present disclosure to a residential power storage system will be described with reference to FIG. For example, in the power storage system 9100 for a residential 9001, power is stored from a centralized power system 9002 such as thermal power generation 9002a, nuclear power generation 9002b, and hydroelectric power generation 9002c via a power network 9009, an information network 9012, a smart meter 9007, a power hub 9008, and the like. It is supplied to the device 9003. At the same time, electric power is supplied to the power storage device 9003 from an independent power source such as the home power generation device 9004. The electric power supplied to the power storage device 9003 is stored. The electric power used in the house 9001 is supplied by using the power storage device 9003. The same power storage system can be used not only for the house 9001 but also for the building.

The house 9001 is provided with a power generation device 9004, a power consumption device 9005, a power storage device 9003, a control device 9010 for controlling each device, a smart meter 9007, and a sensor 9011 for acquiring various information. Each device is connected by a power grid 9009 and an information network 9012. A solar cell, a fuel cell, or the like is used as the power generation device 9004, and the generated power is supplied to the power consumption device 9005 and / or the power storage device 9003. The power consuming device 9005 includes a refrigerator 9005a, an air conditioner 9005b, a television receiver 9005c, a bath 9005d, and the like. Further, the power consuming device 9005 includes an electric vehicle 9006. The electric vehicle 9006 is an electric vehicle 9006a, a hybrid car 9006b, and an electric motorcycle 9006c.

The battery unit of the present disclosure described above is applied to the power storage device 9003. The power storage device 9003 is composed of a secondary battery or a capacitor. For example, it is composed of a lithium ion battery. The lithium ion battery may be a stationary type or may be used in the electric vehicle 9006. The smart meter 9007 has a function of measuring the usage of commercial power and transmitting the measured usage to the electric power company. The power grid 9009 may be a combination of any one or a plurality of DC power supply, AC power supply, and non-contact power supply.

The various sensors 9011 are, for example, a human sensor, an illuminance sensor, an object detection sensor, a power consumption sensor, a vibration sensor, a contact sensor, a temperature sensor, an infrared sensor, and the like. The information acquired by the various sensors 9011 is transmitted to the control device 9010. With the information from the sensor 9011, the state of the weather, the state of a person, and the like can be grasped, and the power consumption device 9005 can be automatically controlled to minimize the energy consumption. Further, the control device 9010 can transmit information about the house 9001 to an external electric power company or the like via the Internet.

The power hub 9008 performs processing such as branching of power lines and DC / AC conversion. As a communication method of the information network 9012 connected to the control device 9010, a method using a communication interface such as UART (Universal Asynchronous Receiver-Transmitter), Bluetooth (registered trademark), ZigBee (registered trademark). , Wi-Fi, etc. There is a method of using a sensor network based on a wireless communication standard. The Bluetooth® method is applied to multimedia communication and can perform one-to-many connection communication. ZigBee® uses the physical layer of the Institute of Electrical and Electronics Engineers (IEEE) 802.15.4. IEEE802.154 is the name of a short-range wireless network standard called PAN (Personal Area Network) or W (Wireless) PAN.

The control device 9010 is connected to an external server 9013. The server 9013 may be managed by any of the housing 9001, the electric power company, and the service provider. The information sent and received by the server 9013 is, for example, power consumption information, life pattern information, power charges, weather information, natural disaster information, and power transaction information. These information may be transmitted and received from a power consuming device in the home (for example, a television receiver), or may be transmitted and received from a device outside the home (for example, a mobile phone). This information may be displayed on a device having a display function, for example, a television receiver, a mobile phone, a PDA (Personal Digital Assistants), or the like.

The control device 9010 that controls each unit is composed of a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and the like, and is stored in the power storage device 9003 in this example. The control device 9010 is connected to a power storage device 9003, a home power generation device 9004, a power consumption device 9005, various sensors 9011, and a server 9013 by an information network 9012, and has a function of adjusting, for example, the amount of commercial power used and the amount of power generated. have. In addition, it may be provided with a function of conducting electric power transactions in the electric power market.

As described above, not only the centralized power system 9002 such as thermal power 9002a, nuclear power 9002b, and hydraulic power 9002c, but also the power generated by the domestic power generation device 9004 (solar power generation, wind power generation) can be stored in the power storage device 9003. can. Therefore, even if the generated power of the home power generation device 9004 fluctuates, it is possible to control the amount of power sent to the outside to be constant or to discharge as much as necessary. For example, the electric power obtained by solar power generation is stored in the power storage device 9003, the late-night power with a low charge is stored in the power storage device 9003 at night, and the power stored by the power storage device 9003 is discharged during the time when the charge is high in the daytime. You can also use it.

In this example, although the example in which the control device 9010 is stored in the power storage device 9003 has been described, it may be stored in the smart meter 9007 or may be configured independently. Further, the power storage system 9100 may be used for a plurality of homes in an apartment house, or may be used for a plurality of detached houses.

The example of the power storage system 9100 to which the technique according to the present disclosure can be applied has been described above. The technique according to the present disclosure can be suitably applied to the secondary battery included in the power storage device 9003 among the configurations described above.

Hereinafter, the present disclosure will be specifically described with reference to Examples, but the present disclosure is not limited to these Examples.

[Example 1-1]
First, the mass of Si powder (manufactured by High Purity Chemical Laboratory Co., Ltd.), SiO ₂ powder (manufactured by High Purity Chemical Laboratory Co., Ltd.), and Sn powder (manufactured by High Purity Chemical Laboratory Co., Ltd.) The mixture was weighed and mixed so that the ratio was Si powder: SiO ₂ powder: Cu powder = 1: 1: 0.1 to obtain a mixture. Next, an appropriate amount of the obtained mixture was added to water as a solvent, and the mixture was uniformly dispersed by an ultrasonic cleaner, and then the solvent was dried to obtain a solidified mixture. Subsequently, the solidified mixture was installed in a vacuum chamber as a vapor deposition source, evaporated by electron beam heating, and a thin film (thickness: 9 μm, dimensions: 10 cm × 20 cm) was deposited on the opposite Cu foil (deposited substrate). I let you. As a result, a laminated body was obtained. As the Cu foil, a Cu-coated foil was used in order to prevent film peeling due to charge and discharge. Then, the laminate was subjected to vacuum heat treatment at 600 ° C. in an infrared vacuum furnace. From the above, the target thin film electrode (negative electrode) was obtained.

[Example 1-2]
A thin film electrode was obtained in the same manner as in Example 1-1 except that the laminate was subjected to vacuum heat treatment at 800 ° C. in an infrared vacuum furnace.

[Reference Example 1-1]
A thin film electrode was obtained in the same manner as in Example 1-1 except that the laminate was not subjected to vacuum heat treatment.

[Examples 2-1 and 2-2, Reference Example 2-1]
Si powder (manufactured by High Purity Chemical Laboratory Co., Ltd.), SiO ₂ powder (manufactured by High Purity Chemical Laboratory Co., Ltd.), and Zn powder (manufactured by High Purity Chemical Laboratory Co., Ltd.) by mass ratio. Si powder: SiO ₂ powder: Zn powder = 1: 1: 0.1 Weigh and mix the thin film electrodes in the same manner as in Examples 1-1 and 1-2 and Reference Example 1-1, except that they are mixed. Obtained.

[Comparative Examples 1-1, 1-2, 1-3]
Thin film electrodes were obtained in the same manner as in Examples 1-1 and 1-2 and Reference Example 1-1 except that Sn powder was not mixed.

[Comparative Examples 2-1, 2-2, 2-3]
Si powder (manufactured by High Purity Chemical Laboratory Co., Ltd.), SiO ₂ powder (manufactured by High Purity Chemical Laboratory Co., Ltd.), and Cu powder (manufactured by High Purity Chemical Laboratory Co., Ltd.) by mass ratio. Si powder: SiO ₂ powder: Cu powder = 1: 1: 0.1 Weigh and mix the thin film electrodes in the same manner as in Examples 1-1 and 1-2 and Reference Example 1-1, except that they are mixed. Obtained.

[Comparative Examples 3-1, 3-2, 3-3]
Si powder (manufactured by High Purity Chemical Laboratory Co., Ltd.), SiO ₂ powder (manufactured by High Purity Chemical Laboratory Co., Ltd.), and Co powder (manufactured by High Purity Chemical Laboratory Co., Ltd.) by mass ratio. Si powder: SiO ₂ powder: Co powder = 1: 1: 0.1 Weighed and mixed so that the thin film electrodes were the same as in Examples 1-1 and 1-2 and Reference Example 1-1. Obtained.

[Comparative Examples 4-1 and 4-2, 4-3]
Si powder (manufactured by High Purity Chemical Laboratory Co., Ltd.), SiO ₂ powder (manufactured by High Purity Chemical Laboratory Co., Ltd.), and Fe powder (manufactured by High Purity Chemical Laboratory Co., Ltd.) by mass ratio. Si powder: SiO ₂ powder: Fe powder = 1: 1: 0.1 Weigh and mix the thin film electrodes in the same manner as in Examples 1-1 and 1-2 and Reference Example 1-1, except that they are mixed. Obtained.

[Comparative Examples 5-1, 5-2, 5-3]
Si powder (manufactured by High Purity Chemical Laboratory Co., Ltd.), SiO ₂ powder (manufactured by High Purity Chemical Laboratory Co., Ltd.), and Ni powder (manufactured by High Purity Chemical Laboratory Co., Ltd.) by mass ratio. Si powder: SiO ₂ powder: Ni powder = 1: 1: 0.1 Weigh and mix the thin film electrodes in the same manner as in Examples 1-1 and 1-2 and Reference Example 1-1, except that they are mixed. Obtained.

[evaluation]
(XPS)
The thin film electrodes were analyzed by XPS. The measuring device and measuring conditions are shown below.
Equipment: JEOL JPS9010
Measurement: Wide scan, narrow scan (Si2p, C1s, O1s, Cu2p)
All peaks were corrected with 248.4 eV of C1s, and the binding state was analyzed by performing background removal and peak fitting.

(SEM)
The thin film electrodes were analyzed with a scanning electron microscope (SEM). The measuring device and measuring conditions are shown below.
Equipment: Hitachi High-Tech S-4800
Measurement: Surface observation (acceleration voltage 5 kV), EDX (Energy Dispersive X-ray Spectroscopy) measurement (acceleration voltage 15 kV)

(TEM)
The thin film electrodes were analyzed by a transmission electron microscope (TEM). The measuring device and measuring conditions are shown below.
Equipment: JEOL JEM-ARM300F
Measurement: Acceleration voltage 300 kV, TEM-bright field image, STEM-HAADF image, STEM-EDX map image FIB (Focused Ion Beam) was used for slicing the sample. Further, in order to acquire the average information of the thin film electrodes, TEM images were taken at random in each of the vicinity of the electrode surface and the depth of about 200 nm from the surface. In addition, a local EDX map image was acquired in STEM mode.

(Battery characteristics)
A 2016 size (diameter 20 mm, height 1.6 mm size) coin-shaped half-cell (hereinafter referred to as "coin cell") having a thin film electrode (negative electrode) as a working electrode and a lithium metal foil as a counter electrode is as follows. I made it.

First, the thin film electrode (negative electrode) was punched into a circular shape having a diameter of 15 mm. Next, a lithium metal foil punched into a circular shape having a diameter of 15 mm as a counter electrode and a polyethylene microporous film as a separator were prepared. Subsequently, LiPF as an electrolyte salt was added to a solvent in which ethylene carbonate (EC), fluoroethylene carbonate (FEC), and dimethyl carbonate (DMC) were mixed so that the mass ratio was EC: FEC: DMC = 40: 10: 50. ₆ was dissolved to a concentration of 1 mol / kg to prepare a non-aqueous electrolyte solution.

Next, the positive electrode and the negative electrode were laminated via a microporous film to form a laminated body, and the non-aqueous electrolytic solution was housed inside the outer cup and the outer can together with the laminated body and crimped via the gasket. As a result, the desired coin cell was obtained.

(Initial charge capacity, initial charge / discharge efficiency, initial impedance)
First, the obtained coin cell was charged and discharged under the following conditions, and the initial charge capacity and the initial discharge capacity were determined.
Charge 0V CCCV (Constant Current / Constant Voltage) 0.05C (0.04mA cut)
Discharge 1.5V CC (Constant Current) 0.05C
Next, the initial charge / discharge efficiency was calculated by the following formula.
Initial charge / discharge efficiency [%] = (Initial discharge capacity / Initial charge capacity) x 100

Further, after the initial discharge, the AC impedance was measured at room temperature of 25 ° C., and a Cole-Cole plot was created to obtain the initial impedance. The initial impedance shown in Table 1 is a numerical value at a frequency of 1 kHz.

(Cycle characteristics, OCV after discharge)
First, the obtained coin cell was charged and discharged under the following conditions, and the discharge capacities in the first cycle and the 50th cycle were determined.
1st cycle: Charge 0V CCCV 0.05C (0.04mA cut), Discharge 1.5V CC 0.05C
After 2nd Cycle: Charge 0V CCCV 0.5C (0.04mA cut), Discharge 1.5V CC 0.5C
Next, the cycle characteristics were obtained by the following formula.
Cycle characteristics [%] = (Discharge capacity in the 50th cycle / Discharge capacity in the 1st cycle) x 100
Moreover, OCV (Open Circuit Voltage) was measured after 50 cycles of discharge.

Ｎ／Ａ：not applicable（該当せず）
ＲＴ：Room Temperature（熱処理なし）
ＯＣＶ：Open Circuit Voltage[result]
Table 1 shows the configurations and evaluation results of the thin film electrodes of Examples 1-1 to 2-2, Reference Examples 1-1 and 2-1 and Comparative Examples 1-1 to 5-3.

N / A: not applicable
RT: Room Temperature (without heat treatment)
OCV: Open Circuit Voltage

As shown in Table 1, in the Cu-added SiO _x thin film, high initial charge / discharge efficiency was obtained without heat treatment. This is because the combination of Cu and oxygen suppresses the Li trap phenomenon (that is, the generation of Li loss) due to non-stoichiometric oxygen. On the other hand, among the Sn, Zn, Co, Fe or Ni-added SiO _x thin films, the Sn-added SiO _x thin film heat-treated at 800 ° C. had the highest initial charge / discharge efficiency of 74.9%. However, the Sn composition ratio by XPS is about 1 at% (the amount of each element charged is 10% by mass, and the Sn of the heavy element is a relatively low composition ratio (at%) (Sn10 mass% is almost equal to Sn2at%). )), And the efficiency improvement of more than 6% ( _{efficiency improvement for additive-free SiO x} thin film heat-treated at 800 ° C.) cannot be explained by the oxygen compensation effect of Sn. The O / Si ratio does not change before and after the heat treatment, and there is no oxygen reduction effect due to reduction. In addition, the 2.5V discharge cycle characteristics that are thought to be related to the strength of the Si—O bond are also the same for the Sn-added SiO _x thin film as the additive-free SiO _x thin film, and a dramatic effect like the addition of Cu can be seen. No. From the above results, _{it is considered that the improvement of the initial charge / discharge efficiency of the Sn-added SiO x} thin film is due to the structure and mechanism completely different from the above-mentioned Cu-added thin film.

Further, as shown in Table 1, Sn is an element that can hardly be diffused in Si. Further, it is also known that Sn does not alloy with Si (does not dissolve in solid solution) even when 0.001 at% of Sn is added, and Sn silicide formation cannot occur.

FIG. 10 shows a cross-sectional SEM image of Si particles doped with Sn by heat treatment at 800 ° C. As described above, since Sn cannot be hardly diffused in Si, Sn precipitates on the surface, and particulate or fibrous precipitates are formed. When a coin cell was assembled using the powder of Si particles, charging and discharging could not be performed.

11A and 11B show surface SEM images of Sn-added SiO _{x thin film.} A grain structure of 2 to 10 μm was confirmed, and it can be seen that columnar deposits were made on the current collector foil. In addition, it was confirmed from EDX mapping that Sn precipitates were not observed on the surface regardless of the presence or absence of heat treatment, and there was no local precipitation. The melting point of Sn metal is as low as 232 ° C, and if it precipitates on the surface, it should be confirmed after heat treatment at 800 ° C. Considering the above-mentioned low Sn diffusivity, it is unlikely that Sn diffuses and precipitates to the surface, and it is presumed that Sn remains inside _{SiO x.}

FIGS. 12A, 12B, 12C, and 12D show XPS spectra inside the _{SiO x} thin film without addition, Fe addition, Ni addition, and Sn addition, respectively. 13A, 13B, 13C, and 13D show structural image views of the inside of the _{SiO x} thin film with no heat treatment, Fe addition, Ni addition, and Sn addition, respectively.

In the case of the additive-free SiO _{x thin film, it can be seen that the SiO 2} component decreases and the Si component increases due to the heat treatment. That is, it is expected that the additive-free SiO _x thin film has a structure in which nano-Si is generated in the matrix of _{SiO 2-x by heat treatment.} In the case of the Fe and Ni-added SiO _x thin film, the SiO ₂ component does not change due to the heat treatment, and the Si component and the silicide component increase. Fe2p and Ni2p indicate that they are Fe silicide and Ni silicide, respectively, and since they do not change even with heat treatment, it is considered that they have already been silicidized at the time of thin film formation. Therefore, the Fe, Ni-added SiO _x thin film seems to have a structure in which nano-Si and nano silicide are dispersed in the matrix of _{SiO 2-x.} It seems that the addition of Fe and Ni has a smaller effect of improving the initial charge / discharge efficiency than Sn, and the formation of nano silicide has little relation to the initial charge / discharge efficiency.

On the other hand, the Sn-added SiO _x thin film having improved initial charge / discharge efficiency is significantly different from the _{additive-free SiO x} thin film and the Fe and Ni-added SiO _{x thin films.} The heat treatment did not change the bonded state of Si, suggesting that nano-Si was not produced and that Sn was present in the metallic state. That is, Sn is neither oxygen nor Si bonded, and the Sn-added SiO _x thin film after 800 ° C. treatment has a completely different structure from oxygen-compensated predoping (Li, Cu, etc.) and silicidization (Fe, Co, Ni, etc.). Is considered to have.

FIG. 14 shows an Ellingham diagram of Sn and Si. It can be seen that the SnO line is the most unstable, and the SnO ₂ line also reverses with the SiO line at 730 ° C. Also, SiO ₂ has the lowest energy (most stable). That is, the following reactions can occur under the conditions of 800 ° C. vacuum heat treatment.
2SnO → Sn + SnO ₂
SnO ₂ + 2SiO → Sn + 2SiO ₂

Since the above reaction is more reactive than the nano-Si reaction (disproportionation reaction; SiO + SiO → Si + SiO _{2 ) generated in the additive-free SiO x} , Sn oxide and SiO are consumed. _{Therefore, it is presumed that the formation of "nano Sn + SiO 2} " in which neither Sn oxide nor nano Si is present is a factor for improving the initial charge / discharge efficiency by adding Sn. Here, _{it should be added that since SiO 2} is in a stable state, Li loss is unlikely to occur.

Figure 15A, respectively 15B, showing Sn added SiO _x film without heat treatment, a low-magnification TEM image of Sn added SiO _x thin film there heat treatment. No aggregates could be confirmed in the thin film without heat treatment, but many fine aggregates (~ 5 nm) with high contrast were observed in the thin film with heat treatment at 800 ° C.

16A and 16B show a high-magnification TEM image of an additive-free SiO _x thin-film film (with heat treatment at 800 ° C.) and an FFT image thereof. 17A and 17B show a high-magnification TEM image of a Sn-added SiO _x thin-film film (with heat treatment at 800 ° C.) and an FFT image thereof. When no additives are added, a crystalline Si phase of 2 to 10 nm is detected by heat treatment at 800 ° C. On the other hand, in the case of Sn addition, agglomerates having a diameter of 2 to 6 nm were observed, but they were in an amorphous phase. The average size of the aggregate was 4 nm. STEM analysis was performed on this aggregate (FIGS. 18, 19A, 19B). As analyzed by XPS and the like, it was confirmed that Sn was the main component of the aggregate, and no nano-Si crystals were observed. That is, it can be said that the result supports the formation of _{"nano Sn + SiO 2} " in which neither the Sn oxide nor the nano Si is present.

From the above, the possibility of Sn pre-doping with a mechanism different from that of oxygen-compensated pre-doping (Li, Cu, etc.) was shown as a method for improving the initial charge / discharge efficiency of _{SiO x active material.} The addition of Sn suppressed the formation of nano-Si crystals and the reaction of non-stoichiometric oxygen (SiO), and improvement of the initial charge / discharge efficiency was observed.

In the above-mentioned examples, the case where tin and zinc are used as the first element has been described, but zinc, lead, bismuth, indium, gold and cadmium form a bond with the second element in the same manner as tin and zinc. It is difficult to do so, and it has the property that it is difficult to diffuse into the first element and the oxide of the first element. Therefore, it is presumed that when lead, bismuth, indium, gold or cadmium is used as the first element, the same effect as when tin or zinc is used as the first element can be obtained. Further, when two or more of tin, zinc, lead, bismuth, indium, gold and cadmium are used in combination as the first element, it is the same as when tin and zinc are used alone as the first element. It is presumed that the effect will be obtained.

Further, in the above-described embodiment, the case where silicon is used as the second element has been described, but germanium is a group 14 element like silicon and has similar characteristics to silicon as a negative electrode active material. Therefore, it is presumed that even when germanium is used as the second element, the same effect as when silicon is used as the second element can be obtained. Further, it is presumed that even when silicon and germanium are used in combination as the second element, the same effect as when silicon and germanium are used alone as the second element can be obtained.

Although the embodiments of the present disclosure, variations thereof, and examples have been specifically described above, the present disclosure is not limited to the above-described embodiments, variations thereof, and examples, and the present disclosure is not limited to the above-mentioned embodiments. Various modifications based on technical ideas are possible.

For example, the above-described embodiments and modifications thereof, as well as the configurations, methods, processes, shapes, materials, numerical values, and the like given in the embodiments are merely examples, and different configurations, methods, processes, and shapes are required as necessary. , Materials, numerical values, etc. may be used. Further, the chemical formulas of the compounds and the like are typical, and if they are the general names of the same compounds, they are not limited to the stated valences and the like.

In addition, the above-described embodiments and modifications thereof, as well as the configurations, methods, processes, shapes, materials, numerical values, and the like of the embodiments can be combined with each other as long as they do not deviate from the gist of the present disclosure.

Further, in the above-described embodiments and examples, examples of applying the present disclosure to cylindrical and laminated film type secondary batteries have been described, but the shape of the battery is not particularly limited. For example, the present disclosure can be applied to secondary batteries such as square type and coin type, and can be applied to flexible batteries mounted on wearable terminals such as smart watches, head-mounted displays, and iGlass (registered trademark). It is also possible to apply the disclosure.

Further, in the above-described embodiments and examples, an example in which the present disclosure is applied to a wound type secondary battery has been described, but the structure of the battery is not limited to this, and for example, a positive electrode and a negative electrode are described. The present disclosure is also applicable to a laminated battery (stack type battery) in which the above-mentioned batteries are laminated via a separator, or a battery in which a positive electrode and a negative electrode are folded with a separator sandwiched between them.

Further, in the above-described embodiments and examples, an example in which the present disclosure is applied to a lithium ion secondary battery and a lithium ion polymer secondary battery has been described, but the types of batteries to which the present disclosure can be applied are limited to this. Not a thing. For example, the present disclosure may be applied to an all-solid-state battery such as an all-solid-state lithium-ion secondary battery.

Further, in the above-described embodiments and examples, the configuration in which the electrode includes the current collector and the active material layer has been described as an example, but the configuration of the electrode is not limited to this. For example, the electrode may be configured to consist only of an active material layer.

The present disclosure may also adopt the following configuration.
(1)
With at least one oxide of silicon dioxide and germanium dioxide,
The first element of at least one of tin, zinc, lead, bismuth, indium, gold and cadmium,
Contains at least one second element of silicon and germanium
A negative electrode active material in which the first aggregate containing the first element is composed.
(2)
The negative electrode active material according to (1), wherein the first aggregate is dispersed in a matrix containing the oxide.
(3)
The negative electrode active material according to (1) or (2), wherein the first aggregate is amorphous.
(4)
The negative electrode active material according to any one of (1) to (3), wherein the average size of the first aggregate is 2 nm or more and 10 nm or less.
(5)
The negative electrode active material according to any one of (1) to (4), wherein the first aggregate further contains the second element.
(6)
The first aggregate is a mixture of crystalline or amorphous first fine particles containing the first element and crystalline or amorphous second fine particles containing the second element. Including
The negative electrode active material according to (1) or (2), wherein the average size of the first fine particles and the second fine particles is 2 nm or less.
(7)
The negative electrode active material according to any one of (1) to (6) constituting the metal phase.
(8)
The negative electrode active material according to any one of (1) to (7), wherein the second aggregate containing the second element is composed.
(9)
The negative electrode active material according to (8), wherein the second aggregate is amorphous.
(10)
The negative electrode active material according to (8) or (9), wherein the average size of the second aggregate is 2 nm or more and 10 nm or less.
(11)
The silicon dioxide is represented by SiO _2-x (x is 0 ≦ x ≦ 0.5).
The negative electrode active material according to any one of (1) to (10), wherein the germanium dioxide is represented by GeO _{2-y (y is 0 ≦ y ≦ 0.5).}
(12)
The content of the first element with respect to the total amount of the first element, the second element and oxygen is 30 at% or more and 70 at% or less.
The content of the second element with respect to the total amount is 1 at% or more and 50 at% or less.
The negative electrode active material according to any one of (1) to (11), wherein the oxygen content with respect to the total amount is 20 at% or more and 70 at% or less.
(13)
The negative electrode according to any one of (1) to (12), which does not contain the first compound in which the first element and the second element are bonded and the second compound in which the first element and oxygen are bonded. Active material.
(14)
The first element contains tin and
In the Sn3d waveform obtained from X-ray photoelectron spectroscopy, it has a peak top in the range of binding energy of 484 eV or more and 486 eV or less.
The negative electrode active material according to any one of (1) to (13), wherein the peak having the peak top is a peak caused by the Sn—Sn bond.
(15)
The negative electrode active material according to any one of (1) to (14), which has a thin film form or a powder form.
(16)
At least one first element of tin, zinc, lead, bismuth, indium, gold, silver and cadmium, at least one second element of silicon and germanium, and at least one second element. By heating and vaporizing the material containing the oxide of, a negative electrode active material is formed.
A method for producing a negative electrode active material, which comprises heat-treating the formed negative electrode active material.
(17)
Further comprising producing the material by immersing the first element powder, the second element powder and the second element oxide powder in a liquid and then evaporating the liquid (16). The method for producing a negative electrode active material according to.
(18)
The temperature of the heat treatment is 600 ° C. or higher.
The method for producing a negative electrode active material according to (16) or (17), wherein a metal phase containing the first element is formed by the heat treatment.
(19)
A negative electrode containing the negative electrode active material according to any one of (1) to (15), and a negative electrode.
With the positive electrode
Batteries with electrolytes.
(20)
Equipped with the battery described in (19),
An electronic device that receives power from the battery.
(21)
It is equipped with a current collector and a thin film provided on the current collector.
The thin film is a thin film electrode containing the negative electrode active material according to any one of (1) to (15).
(22)
The battery according to (19) and
A battery pack including a control unit for controlling the battery.
(23)
The battery according to (19) and
A conversion device that receives electric power from the battery and converts it into vehicle driving force.
An electric vehicle including a control device that processes information related to vehicle control based on the information related to the battery.
(24)
Equipped with the battery described in (19),
A power storage device that supplies electric power to an electronic device connected to the battery.
(25)
Equipped with the battery described in (19),
A power system that receives power from the battery.

11 Battery can 12, 13 Insulation plate 14 Battery lid 15 Safety valve mechanism 15A Disc plate 16 Heat-sensitive resistance element 17 Gasket 20 Winding type electrode body 21 Positive electrode 21A Positive electrode collector 21B Positive electrode active material layer 22 Negative electrode 22A Negative electrode current collector 22B Negative electrode active material layer 23 Separator 24 Center pin 25 Positive electrode lead 26 Negative electrode lead 111 Matrix 112 Aggregate 300 Battery pack 400 Electronic equipment 7200 Hybrid vehicle 9100 Power storage system

Claims (17)

With at least one oxide of silicon dioxide and germanium dioxide,
The first element of at least one of tin, zinc, lead, bismuth, indium, gold and cadmium,
Contains at least one second element of silicon and germanium
A first aggregate containing the first element and the second element is composed.
The first aggregate is a mixture of crystalline or amorphous first fine particles containing the first element and crystalline or amorphous second fine particles containing the second element. Including
The average size of the first fine particle and the second fine grain state, and are less 2 nm,
For the average size of the first micrograins, 10 of the first micrograins are randomly selected from the cross-sectional TEM image of the negative electrode active material, and the area of the cross section of each of the first micrograins is measured by image processing. Then, assuming that the cross section of the first micrograin is circular, the diameter of each of the first micrograins is obtained from the area of the cross section of each of the first micrograins, and the obtained 10 first micrograins are obtained. Obtained by arithmetically averaging the diameters of the fine grains,
For the average size of the second fine particles, 10 of the second fine particles were randomly selected from the cross-sectional TEM image of the negative electrode active material, and the area of the cross section of each of the second fine particles was measured by image processing. Then, assuming that the cross section of the second micrograin is circular, the diameter of each of the second micrograins is obtained from the area of the cross section of each of the second micrograins, and the obtained 10 second micrograins are obtained. negative electrode active material that is determined by the arithmetic mean diameter of the fine particle. The negative electrode active material according to claim 1, wherein the first aggregate is dispersed in a matrix containing the oxide. The negative electrode active material according to claim 1 or 2, wherein the first aggregate is amorphous. The average size of the first aggregate state, and are less 10 nm,
For the average size of the first aggregates, 10 of the first aggregates were randomly selected from the cross-sectional TEM image of the negative electrode active material, and the area of the cross section of each of the first aggregates was measured by image processing. Then, assuming that the cross section of the first aggregate is circular, the diameter of each of the first aggregates is obtained from the area of the cross section of each of the first aggregates, and the obtained 10 first aggregates are obtained. negative active material according to any one of the diameter of the aggregate claims 1 that is determined by the arithmetic mean 3. The negative electrode active material according to any one of claims 1 to 4, wherein the first element constitutes a metal phase. The negative electrode active material according to any one of claims 1 to 5, further comprising a second aggregate containing the second element. The negative electrode active material according to claim 6, wherein the second aggregate is amorphous. The average size of the second aggregate state, and are more 10nm or less 2 nm,
For the average size of the second aggregate, 10 of the second aggregate were randomly selected from the cross-sectional TEM image of the negative electrode active material, and the area of the cross section of each of the second aggregate was measured by image processing. Then, assuming that the cross section of the second aggregate is circular, the diameter of each of the second aggregates is obtained from the area of the cross section of each of the second aggregates, and the obtained 10 second aggregates are obtained. negative electrode active material according to the diameter of the aggregates in claim 6 or 7 that are determined by arithmetic average. The silicon dioxide is represented by SiO _2-x (x is 0 ≦ x ≦ 0.5).
The negative electrode active material according to any one of claims 1 to 8, wherein the germanium dioxide is represented by GeO _{2-y (y is 0 ≦ y ≦ 0.5).} The content of the first element with respect to the total amount of the first element, the second element and oxygen is 30 at% or more and 70 at% or less.
The content of the second element with respect to the total amount is 1 at% or more and 50 at% or less.
The negative electrode active material according to any one of claims 1 to 9, wherein the oxygen content with respect to the total amount is 20 at% or more and 70 at% or less. The negative electrode active material according to any one of claims 1 to 10, which does not contain the first compound in which the first element and the second element are bonded, and the second compound in which the first element and oxygen are bonded. .. The first element contains tin and
In the Sn3d waveform obtained from X-ray photoelectron spectroscopy, it has a peak top in the range of binding energy of 484 eV or more and 486 eV or less.
The negative electrode active material according to any one of claims 1 to 11, wherein the peak having the peak top is a peak caused by the Sn—Sn bond. The negative electrode active material according to any one of claims 1 to 12, which has a thin film form or a powder form. At least one first element of tin, zinc, lead, bismuth, indium, gold, silver and cadmium, at least one second element of silicon and germanium, and at least one second element. The negative electrode active material is deposited on the substrate with an electron beam using a mixture containing the oxide of cadmium immersed in a solvent and solidified as a vapor deposition source .
A method for producing a negative electrode active material, which comprises heat-treating the deposited negative electrode active material. The temperature of the heat treatment is 600 ° C. or higher.
The method for producing a negative electrode active material according to claim 14 , wherein a metal phase containing the first element is formed by the heat treatment. A negative electrode containing the negative electrode active material according to any one of claims 1 to 13 and a negative electrode.
With the positive electrode
Batteries with electrolytes. The battery according to claim 16 is provided.
An electronic device that receives power from the battery.

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