JP2017022141A - Manufacturing method of active material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture an electrode in which charge/discharge cycle characteristics is enhanced and deterioration due to peeling of active material or the like is unlikely to occur, and to provide a power storage device.SOLUTION: In an electrode for a power storage device, by using a collector, and an electrode on the collector having an active material layer that has particles containing niobium oxide and granular active material, charge/discharge cycle characteristics of the power storage device can be enhanced. Furthermore, the granular active material and the particles containing niobium oxide come into contact with each other, whereby, the granular active material is fixed physically. Thus, pulverization of the active material due to expansion or contraction accompanying charge/discharge of the power storage device, and deterioration due to peeling or the like from the collector can be suppressed.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electrode manufacturing method and a power storage device.

Note that the power storage device in this specification refers to all elements or devices having a power storage function.

In recent years, various power storage devices such as lithium ion secondary batteries, lithium ion capacitors, and air batteries have been developed. Especially as a secondary battery with high output and high energy density
Attention has been focused on lithium ion secondary batteries in which charging and discharging are performed by moving lithium ions between a positive electrode and a negative electrode.

An electrode used for a power storage device is manufactured by forming an active material layer over one surface of a current collector. The active material layer is formed of an active material capable of storing and releasing ions serving as carriers such as carbon or silicon. For example, when an active material layer is formed of silicon or silicon to which phosphorus is added, the theoretical capacity is larger than that of forming an active material layer of carbon, which is superior in terms of increasing the capacity of a power storage device (Patent Document) 1).

However, it is known that silicon, which is an active material, expands or contracts when the lithium is occluded or released. Therefore, the active material layer is pulverized with charging / discharging, causing problems such as detachment from the current collector. As a result, the current collecting property in the electrode is lowered, and the charge / discharge cycle characteristics are deteriorated. As a countermeasure against this, there is a method of suppressing the collapse of silicon by coating the surface of the active material layer with carbon, copper, nickel or the like. However, when these coatings are performed, there is a drawback that the reactivity between lithium and silicon is lowered, and the charge / discharge capacity is lowered.

JP 2001-210115 A

An object of one embodiment of the present invention is to provide a method for manufacturing a power storage device and an electrode that can improve performance of the power storage device such as cycle characteristics.

One embodiment of the present invention is a power storage device including an electrode including a current collector, and an active material layer including particles having niobium oxide and a granular active material over the current collector.

According to one embodiment of the present invention, a negative electrode including a current collector, a particle having niobium oxide and an active material layer having a granular active material over the current collector, and an electrolyte formed in contact with the negative electrode And a positive electrode facing the negative electrode with the electrolyte interposed therebetween.

One embodiment of the present invention is a power storage device in which the active material includes one or more materials selected from silicon, tin, aluminum, or germanium. The above material can be alloyed with lithium, and an impurity such as phosphorus or boron may be added to the material to lower the electrical resistance value.

One embodiment of the present invention is a method in which an electrode formed by applying a binder, a conductive additive, particles having niobium oxide, and a slurry having a granular active material on a current collector includes the particles having niobium oxide. This is a method for producing an electrode produced by a sol-gel method.

One embodiment of the present invention is a method for manufacturing an electrode in which the active material includes one or more materials selected from silicon, tin, aluminum, or germanium. The above material can be alloyed with lithium, and an impurity such as phosphorus or boron may be added to the material to lower the electrical resistance value.

The active material described above is a material that forms an alloy with lithium and can reversibly insert and desorb lithium ions. In addition, the theoretical capacity 37 of graphite, which has been widely used conventionally,
Compared to 2 mAh / g, for example, silicon has a theoretical capacity of 4000 mAh / g, which is about 10 times higher. However, as described above, the volume change of silicon, which is an active material, is very large due to charging / discharging by insertion / extraction of lithium ions. Therefore, defects such as pulverization of the active material and peeling from the current collector occur due to charge / discharge, and deterioration of the charge / discharge cycle increases.

In one embodiment of the present invention, the granular active material is physically fixed when the granular active material is in contact with the particles having niobium oxide, and therefore, due to expansion or contraction of the active material accompanying charging / discharging of the power storage device, Deterioration such as pulverization can be suppressed. Therefore, it is preferable that many particles having niobium oxide are in contact with the granular active material. Niobium oxide is excellent in the conductivity of ions (lithium ions, etc.) serving as carriers, and functions as a battery even if it covers an active material. However, since niobium oxide is an electrically insulating material, when the active material is completely enclosed, resistance is sandwiched between the current collector and the active material, which is not preferable.

The crystallinity of the active material or niobium oxide is not particularly limited, and may be any of amorphous, microcrystalline, or single crystal. Moreover, the material in which different crystallinity is mixed may be sufficient.

The particles having niobium oxide may contain a niobium lithium alloy, for example, L
i ₂ Nb ₂ O ₅ may be included.

The Li ₂ Nb ₂ O ₅ is formed by reaction of Nb ₂ O ₅ and Li by the initial discharge of the battery. Furthermore the _Li 2 _Nb 2 _{O 5,} which may be also retained in the subsequent charge and _discharge, Li 2 _Nb 2 _{O 5} Li is desorbed from the, it may serve as _Nb 2 _{O 5.} Thus, Li
By forming ₂ Nb ₂ O ₅ on the active material, Li ₂ Nb ₂ O ₅ becomes organic SEI (So
Stable inorganic SEI instead of lid Electrolyte Interface)
As a result, effects such as lowering resistance, improving lithium diffusibility, and relaxing volume expansion of the active material are exhibited.

In the electrode used for the power storage device, the cycle characteristics of the power storage device can be improved by forming an active material layer including particles having niobium oxide and a granular active material over a current collector.

In addition, particles having niobium oxide may be contained in the conductive additive or binder used for manufacturing the electrode.

As a material for the current collector, a highly conductive material such as a metal element typified by platinum, aluminum, or copper can be used. The current collector may be formed using a metal element that forms silicide by reacting with silicon.

The electrolyte formed between the negative electrode in the power storage device and the positive electrode facing the negative electrode can be formed of a liquid or a solid, and the electrolyte may include particles containing niobium oxide.

In one embodiment of the present invention, an electrode having a particle having niobium oxide and an active material layer having a granular active material on a current collector, and further providing a carbon-based film on the active material layer Can do. That is, a carbon-based film can be provided around the particles having niobium oxide and the granular active material.

The carbon-based film is made of a film-like carbon-based material, and is graphite or 1 to 100 sheets,
Preferably, it has 10 or more and 30 or less graphene. The film thickness of the carbonaceous material is 2
When three to three graphene layers are stacked, the film thickness is 1 nm to 2 nm. The film-like carbon-based material may be amorphous or crystalline.

Such a film-like carbon-based material has an advantage that a lithium diffusion path in the active material is short as a negative electrode active material. As a conductive support agent, there exists an advantage which can build a conductive network in a wide range.

According to one embodiment of the present invention, deterioration of a power storage device due to peeling of an active material or the like can be reduced,
Therefore, a power storage device with improved performance such as cycle characteristics can be provided.

4A and 4B are a cross-sectional view and a top view illustrating electrodes of a power storage device according to one embodiment of the present invention. 10A to 10D illustrate a method for manufacturing an electrode according to one embodiment of the present invention. 2A and 2B are a plan view and a cross-sectional view of one embodiment of a power storage device. It is a perspective view of one form of application of a power storage device. It is a figure which shows the example of a structure of a wireless electric power feeding system. It is a figure which shows the example of a structure of a wireless electric power feeding system. FIG. 11 illustrates a manufacturing process of a power storage device. It is a figure which shows the battery characteristic result of an electrical storage apparatus.

An example of an embodiment of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the following description, and it is easily understood by those skilled in the art that modes and details can be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments below. Note that in the description of the drawings, the same reference numerals may be used in common in different drawings. In addition, the same hatch pattern is used when referring to the same thing, and there is a case where no reference numeral is given.

(Embodiment 1)
In this embodiment, an electrode of a power storage device which is one embodiment of the present invention and a manufacturing method thereof are as follows.
This will be described with reference to FIGS.

FIG. 1 is a diagram illustrating one embodiment of an electrode of a power storage device. 1A is a cross-sectional view of the electrode, and FIG.
B) shows a top view of the electrode. The electrode of the power storage device illustrated in FIG. 1 includes a current collector 101 and a current collector 1.
01, an active material layer 100 having particles 109 having niobium oxide and a granular active material 103 provided on one surface. Although not shown here because it is complicated, FIG.
In addition to the granular active material 103 and the particles 109 having niobium oxide shown in FIG. 2, a binder for fixing the particles, a conductive auxiliary agent for improving the conductivity, and a viscosity adjusting agent (N-methyl- 2 pyrrolidone: NMP) may be included.

The current collector 101 is formed using a material having conductivity that can be used as a current collector for a negative electrode and heat resistance for subsequent heat treatment as appropriate. Examples of conductive materials that can be used as a current collector include copper, platinum, aluminum, nickel, tungsten, molybdenum,
Although there are titanium, iron, and the like, it is not limited thereto. Note that when aluminum is used for the current collector, an aluminum alloy to which an element for improving heat resistance such as silicon, titanium, neodymium, scandium, or molybdenum is added is preferably used. Alternatively, an alloy of the above conductive material may be used.

Alternatively, the current collector 101 may be formed using a metal element that forms silicide by reacting with silicon. Examples of metal elements that react with silicon to form silicide include zirconium, titanium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, nickel, and the like.

An oxide conductive material can be used for the current collector 101. Typical examples of the oxide conductive material include indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, and indium containing titanium oxide. Examples thereof include oxides, indium tin oxide containing titanium oxide, indium tin oxide, indium zinc oxide, and indium tin oxide to which silicon oxide is added. Note that the current collector 101 may have a foil shape, a plate shape, or a net shape. In the case of such a shape, since the shape can be maintained by the current collector 101 alone, it is not necessary to use a support substrate.

As the granular active material 103, a material that is alloyed with ions that exchange charges is preferably used. The ions that transfer and receive charges may be alkali metal ions such as lithium and sodium, alkaline earth metal ions such as calcium, strontium, and barium, beryllium ions, or magnesium ions, and lithium ions are preferably used. Active material 103
For example, as the material that can be alloyed with lithium, one or more materials selected from silicon, tin, aluminum, and germanium can be used.

By applying a slurry made of the above active material powder or the like onto the current collector 101, an active material layer can be formed over the current collector. At this time, it is preferable to use an active material powder having a small particle size because the storage capacity per unit volume can be increased.

The particles 109 containing niobium oxide can be manufactured by a sol-gel method, a solid phase method, or the like. Instead of niobium oxide, an oxide of vanadium, tantalum, tungsten, zirconium, molybdenum, hafnium, chromium, or titanium can be used. The crystal structure may be amorphous, polycrystalline, or single crystal.

<Method for producing particles having niobium oxide>
Here, a method for manufacturing the particles 109 containing niobium oxide will be described. First, to niobium alkoxide (Nb (OCH ₂ CH ₃ ) ₅ ), a stabilizer, ethyl acetoacetate and a solvent, toluene, are added and stirred to prepare a solution. Next, the niobium alkoxide in the solution gradually reacts with moisture in the atmosphere, and is condensed and gelled by the hydrolysis reaction shown in Chemical Formula 1.

Nb (OCH ₂ CH ₃ ) ₅ + 5H ₂ O → Nb (OH) ₅ + 5CH ₂ CH ₃ OH
(Chemical formula 1)

The gel obtained by the above steps is diluted by adding water and stirred using an ultrasonic cleaner to prepare a dispersion. Next, the dispersion liquid is baked (about 500 to 600 ° C.), so that the Nb (OH) ₅ gel is converted to niobium oxide (Nb) by the condensation reaction shown in Chemical Formula 2.
Particles with ₂ O ₅ ) can be produced.

2Nb (OH) ₅ → (Nb (OH) ₄ ) ₂ O + H ₂ O (Chemical formula 2)

As described above, the particles 109 containing niobium oxide can be manufactured.

In addition, active material particles such as silicon grains can be mixed with the gel generated by the hydrolysis reaction shown in Chemical Formula 1. Thus, the particles 109 having niobium oxide can be uniformly attached to the active material particles.

(Production method of electrode)
Next, a method for manufacturing the electrode illustrated in FIG. 1 will be described with reference to FIGS.

First, as shown in step S111 of FIG. 2, slurry is applied on the current collector. The slurry contains particulate active material 103 and particles 109 having niobium oxide. The thickness of the applied slurry is preferably 20 μm or more and 30 μm or less, but is not limited thereto, and may be appropriately adjusted according to desired battery characteristics.

By applying the slurry onto the current collector, an active material layer 100 having particles 109 having niobium oxide and a granular active material 103 is formed as shown in FIG. Further, it is preferable that the ratio of the particles 109 having niobium oxide in contact with the surface of the granular active material 103 is larger. Further, the granular active material 103 and the particles 109 having niobium oxide
An alloy of niobium and an active material may be formed at a location where the contact is made.

<Method for producing slurry>
Here, a method for producing the slurry will be described. As described above, particles having niobium oxide produced on the surface of the granular active material by mixing and stirring the particles having niobium oxide prepared by the sol-gel method, the granular active material, the binder, the conductive additive, and the viscosity modifier. A slurry to which is attached is prepared. In the preparation of the slurry, the conductive assistant is dispersed in a solvent containing a binder, and the active material is mixed there. At this time, in order to improve dispersibility, it is preferable that the amount of the solvent is suppressed and kneading is performed. Then, a solvent is added and a slurry is produced. The ratios of the active material, the conductive auxiliary agent, the binder and the solvent can be adjusted as appropriate. However, the higher the ratio of the conductive auxiliary agent and the binder, the higher the battery performance per active material amount.

In addition, the smaller the particle size of the granular active material, the better the capacity and cycle characteristics, and the particle size is preferably 10 μm or less.

The conductive assistant may be any material as long as the material itself is an electronic conductor and does not cause a chemical change with other substances in the battery device. For example, carbon-based materials such as graphite, carbon fiber, carbon black, acetylene black, ketjen black, VGCF (registered trademark), copper, nickel,
Examples thereof include powders and fibers of a metal material such as aluminum or silver or a mixture thereof. The conductive assistant is a substance that helps conductivity between the active materials, and is a material that is filled between the active materials that are separated from each other to establish conduction between the active materials.

Examples of the binder include starch, polyimide, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose, diacetyl cellulose, polyvinyl chloride, polyvinyl pyrrolidone, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, and EPDM (Ethylene Propylene).
e Diene Monomer), sulfonated EPDM, styrene butadiene rubber, butadiene rubber, polysaccharides such as fluoro rubber or polyethylene oxide, thermoplastic resin or rubber elastic polymer.

Examples of the solvent include water, N-methyl-2-pyrrolidone, and lactic acid ester.

Next, as shown in step S112 of FIG. 2, a heat treatment is performed to evaporate the solvent. A hot plate or an oven can be used, and the processing conditions are, for example, a nitrogen atmosphere, 3
What is necessary is just to carry out at 50 degreeC.

Next, as shown in step S113, it is preferable to increase the adhesion between the current collector and the slurry by pressing from above the slurry. Further, the active material layer is flattened by pressing.

Next, as shown in step S114, the current collector is punched into a desired shape.

Finally, as shown in step S115, the heat treatment is performed again. For example, the processing conditions may be set in a reduced-pressure atmosphere and 100 ° C.

Through the above steps, the electrode shown in FIG. 1 can be manufactured.

As described above, when the granular active material is in contact with the particles having niobium oxide, the granular active material is physically fixed, thereby pulverizing, etc. due to expansion or contraction of the active material accompanying charging / discharging of the battery. Can be prevented.

Further, the formation of organic SEI (Solid Electrolyte Interface) on the surface of the active material can be suppressed by forming the particles containing niobium oxide in contact with the active material. As a result, there are effects such as lowering resistance, improving lithium diffusibility, and relaxing the volume expansion of the active material.

As described above, in the electrode used for the power storage device, the cycle characteristics of the power storage device can be improved by forming the active material layer including the particles having niobium oxide and the granular active material over the current collector.

(Embodiment 2)
In this embodiment, the structure of the power storage device will be described with reference to FIGS.

First, a structure of a secondary battery as a power storage device will be described below. Here, the structure of a lithium ion battery, which is a typical example of a secondary battery, will be described.

FIG. 3A is a plan view of the power storage device 151, and FIG. 3B is a cross-sectional view taken along one-dot chain line AB in FIG. In this embodiment mode, a pouched thin power storage device is shown as the power storage device 151.

A power storage device 151 illustrated in FIG. 3A includes a power storage cell 155 inside an exterior member 153.
In addition, terminal portions 157 and 159 connected to the storage cell 155 are provided. As the exterior member 153, a laminate film, a polymer film, a metal film, a metal case, a plastic case, or the like can be used.

As shown in FIG. 3B, the power storage cell 155 includes a negative electrode 163, a positive electrode 165, and a negative electrode 163.
And the separator 167 provided between the positive electrode 165, the exterior member 153, and the storage cell 15
5 and the electrolyte 169.

The negative electrode 163 includes a negative electrode current collector 171 and a negative electrode active material layer 173. The negative electrode active material layer 173 is formed on one or both surfaces of the negative electrode current collector 171.

The positive electrode 165 includes a positive electrode current collector 175 and a positive electrode active material layer 177. The positive electrode active material layer 177 is formed on one or both surfaces of the positive electrode current collector 175.

Further, the negative electrode current collector 171 is connected to the terminal portion 159. The positive electrode current collector 175 has a terminal portion 15.
7 is connected. Further, a part of each of the terminal portions 157 and 159 is led out of the exterior member 153.

Note that in this embodiment, a thin pouched power storage device is shown as the power storage device 151; however, various shapes of power storage devices such as a button power storage device, a cylindrical power storage device, and a rectangular power storage device can be used. . Further, although a structure in which the positive electrode, the negative electrode, and the separator are stacked is shown in this embodiment mode, a structure in which the positive electrode, the negative electrode, and the separator are wound may be used.

As the negative electrode current collector 171, the current collector 101 described in Embodiment 1 can be used.

As the negative electrode active material layer 173, the active material layer 100 described in Embodiment 1 can be used. Further, it is preferable to use silicon having a high capacity as the active material.

As the positive electrode current collector 175, aluminum, stainless steel, or the like is used. The positive electrode current collector 175 can have a foil shape, a plate shape, a net shape, a film shape, or the like as appropriate.

As the positive electrode active material layer 177, LiFeO ₂ , LiCoO ₂ , LiNiO ₂ , LiMn ₂
O ₄ , LiFePO ₄ , LiCoPO ₄ , LiNiPO ₄ , LiMn ₂ PO ₄ , V ₂ O ₅
, Cr ₂ O ₅ , MnO ₂ , and other lithium compounds can be used as materials. Note that in the case where the carrier ions are alkali metal ions or alkaline earth metal ions other than lithium, as the positive electrode active material layer 177, an alkali metal (for example, sodium or potassium) or an alkali instead of lithium in the lithium compound is used. An earth metal (eg, calcium, strontium, barium, etc.) can also be used.

The solute of the electrolyte 169 is made of a material that can transport lithium ions that are carrier ions and stably exist. As a representative example of the electrolyte solute, LiClO ₄
, LiAsF ₆ , LiBF ₄ , LiPF ₆ , and Li (C ₂ F ₅ SO ₂ ) ₂ N. When the carrier ion is an alkali metal ion or alkaline earth metal ion other than lithium, an alkaline earth salt such as a sodium salt or potassium salt, a calcium salt, a strontium salt, or a barium salt is used as the solute of the electrolyte 169. A metal salt, beryllium salt, magnesium salt, or the like can be used as appropriate.

As a solvent for the electrolyte 169, a material that can transfer lithium ions (or other carrier ions) is used. The solvent for the electrolyte 169 is preferably an aprotic organic solvent. Typical examples of the aprotic organic solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, acetonitrile, dimethoxyethane, tetrahydrofuran and the like, and one or more of these can be used. In addition, the use of a polymer material that is gelled as a solvent for the electrolyte 169 increases safety including liquid leakage. Further, the power storage device 151 can be reduced in thickness and weight. Typical examples of the polymer material to be gelated include silicon gel, acrylic gel, acrylonitrile gel, polyethylene oxide, polypropylene oxide, and fluorine-based polymer.

In addition, as the electrolyte 169, Li ₃ PO ₄ , Li ₃ PO _(4-x) N _x , Li _x PS _y (
Solid electrolytes such as x, y: natural numbers) can be used. Furthermore, in the electrolyte 169,
Niobium may be included. Moreover, vinylene carbonate etc. may be included.

The separator 167 uses an insulating porous body. Typical examples of the separator 167 include cellulose (paper), polyethylene, polypropylene, glass fiber, and the like. Further, these materials can be used in a single layer or laminated.

Lithium ion batteries have a small memory effect, a high energy density, and a large discharge capacity. Also, the operating voltage is high. For these reasons, it is possible to reduce the size and weight. In addition, there is little deterioration due to repeated charging and discharging, long-term use is possible, and cost reduction is possible.

Next, a capacitor will be described as the power storage device. Typical examples of capacitors include
There are double layer capacitors, lithium ion capacitors and the like.

In the case of a capacitor, a material capable of reversibly occluding at least one of lithium ions (or other carrier ions) and anions is used as the positive electrode active material layer 177 of the secondary battery illustrated in FIG. That's fine. Typical examples of the positive electrode active material layer 177 include activated carbon, a conductive polymer, and a polyacene organic semiconductor (PAS).

Lithium ion capacitors have high charge / discharge efficiency, can be rapidly charged / discharged, and have a long life due to repeated use.

By using the negative electrode described in Embodiment 1 as the negative electrode 163, a power storage device with improved cycle characteristics can be manufactured.

In addition, by using the current collector and the active material layer described in Embodiment 1 for the negative electrode of the air battery which is one embodiment of the power storage device, a power storage device with improved cycle characteristics can be manufactured.

As described above, in one embodiment of the present invention, a current collector layer, particles having niobium oxide, and an active material layer having a granular active material can be used. Accordingly, a power storage device with improved cycle characteristics can be provided. In addition, a power storage device that can reduce deterioration of the power storage device due to peeling of the active material or the like can be provided.

(Embodiment 3)
In this embodiment, application modes of the power storage device described in Embodiment 2 are described with reference to FIGS.

The power storage device described in Embodiment 2 includes a camera such as a digital camera or a video camera, a digital photo frame, a mobile phone (also referred to as a mobile phone or a mobile phone device), a portable game machine,
It can be used for electronic devices such as portable information terminals and sound reproduction devices. Further, it can be used for electric propulsion vehicles such as electric vehicles, hybrid vehicles, railway electric vehicles, work vehicles, carts, and electric wheelchairs. Here, an example of an electric propulsion vehicle will be described.

FIG. 4A shows a configuration of a four-wheeled automobile 300 that is one of electric propulsion vehicles. Car 30
0 is an electric vehicle or a hybrid vehicle. An automobile 300 shows an example in which a power storage device 302 is provided at the bottom. In order to clarify the position of the power storage device 302 in the car 300, FIG. 4B illustrates the car 300 in which only the outline is shown, and the power storage device 302 provided at the bottom of the car 300. The power storage device described in Embodiment 4 can be used for the power storage device 302. The power storage device 302 can be charged by external power supply using a plug-in technology or a wireless power feeding system.

FIG. 4C illustrates a configuration of a motor boat 1301 that is one of the electric propulsion vehicles. FIG.
C) illustrates a case where the motor boat 1301 includes the power storage device 1302 on the side of the hull. The power storage device described in Embodiment 4 can be used for the power storage device 1302. The power storage device 1302 can be charged by external power supply using plug-in technology or a wireless power feeding system. Charging the motor boat 1301 (ie,
The power supply device for charging the power storage device 1302 can be provided, for example, in a mooring facility for mooring a ship in a harbor.

FIG. 4D illustrates a structure of an electric wheelchair 1311 that is one of the electric propulsion vehicles. FIG. 4 (D)
Then, the case where the electric wheelchair 1311 includes the power storage device 1312 at the bottom is illustrated. The power storage device described in Embodiment 4 can be used for the power storage device 1312.
The power storage device 1312 can be charged by external power supply using plug-in technology or a wireless power feeding system.

(Embodiment 4)
In this embodiment, an example in which a secondary battery which is an example of a power storage device according to one embodiment of the present invention is used for a wireless power feeding system (hereinafter referred to as an RF power feeding system) is described with reference to FIGS. This will be described with reference to the block diagram of FIG. In each block diagram, the components in the power receiving device and the power feeding device are classified by function and shown as blocks independent of each other, but the actual components are difficult to completely separate for each function, One component may be related to a plurality of functions.

First, the RF power feeding system will be described with reference to FIG.

The power receiving device 600 is an electronic device or an electric propulsion vehicle that is driven by power supplied from the power feeding device 700, but can be appropriately applied to other devices that are driven by power. Representative examples of electronic devices include cameras such as digital cameras and video cameras, digital photo frames, mobile phones (also referred to as mobile phones and mobile phone devices), portable game machines, portable information terminals, sound playback devices, display devices, There are computers. Typical examples of the electric propulsion vehicle include an electric vehicle, a hybrid vehicle, a railway electric vehicle, a work vehicle, a cart, and an electric wheelchair.
In addition, the power feeding device 700 has a function of supplying power to the power receiving device 600.

In FIG. 5, the power receiving device 600 includes a power receiving device portion 601 and a power load portion 610.
The power receiving device portion 601 includes at least a power receiving device antenna circuit 602, a signal processing circuit 603, and a secondary battery 604. In addition, the power feeding device 700 includes a power feeding device antenna circuit 70.
1 and a signal processing circuit 702 at least.

The power receiving device antenna circuit 602 has a function of receiving a signal transmitted from the power feeding device antenna circuit 701 or transmitting a signal to the power feeding device antenna circuit 701. The signal processing circuit 603 processes the signal received by the power receiving device antenna circuit 602 to generate the secondary battery 60.
4, and the supply of power from the secondary battery 604 to the power load unit 610 are controlled. The signal processing circuit 603 controls the operation of the power receiving device antenna circuit 602. That is, the intensity, frequency, and the like of a signal transmitted from the power receiving device antenna circuit 602 can be controlled.
The power load unit 610 is a drive unit that receives power from the secondary battery 604 and drives the power receiving device 600. Typical examples of the power load unit 610 include a motor, a drive circuit, and the like, but a device that receives other power and drives the power receiving device can be used as appropriate. The power feeding device antenna circuit 701 has a function of transmitting a signal to the power receiving device antenna circuit 602 or receiving a signal from the power receiving device antenna circuit 602. The signal processing circuit 702
The signal received by the power feeding device antenna circuit 701 is processed. The signal processing circuit 702 controls the operation of the power feeding device antenna circuit 701. That is, the intensity, frequency, and the like of a signal transmitted from the power feeding device antenna circuit 701 can be controlled.

A secondary battery according to one embodiment of the present invention includes a power receiving device 6 in the RF power feeding system described with reference to FIG.
00 is used as a secondary battery 604 of 00.

By using the secondary battery according to one embodiment of the present invention for the RF power feeding system, a discharge capacity or a charge capacity (also referred to as a charged amount) can be increased as compared with a conventional secondary battery. Therefore, the time interval of wireless power feeding can be extended (the trouble of repeatedly feeding power can be saved).

Further, by using the secondary battery according to one embodiment of the present invention for the RF power feeding system, if the discharge capacity or the charge capacity capable of driving the power load portion 610 is the same as the conventional one, the power receiving device 6
00 can be reduced in size and weight. Therefore, the total cost can be reduced.

Next, another example of the RF power feeding system will be described with reference to FIG.

In FIG. 6, the power receiving device 600 includes a power receiving device portion 601 and a power load portion 610.
The power receiving device portion 601 includes at least a power receiving device antenna circuit 602, a signal processing circuit 603, a secondary battery 604, a rectifier circuit 605, a modulation circuit 606, and a power supply circuit 607. The power feeding device 700 includes a power feeding device antenna circuit 701 and a signal processing circuit 702.
A rectifier circuit 703, a modulation circuit 704, a demodulation circuit 705, and an oscillation circuit 706.

The power receiving device antenna circuit 602 has a function of receiving a signal transmitted from the power feeding device antenna circuit 701 or transmitting a signal to the power feeding device antenna circuit 701. When a signal transmitted from the power feeding device antenna circuit 701 is received, the rectifier circuit 605 has a role of generating a DC voltage from the signal received by the power receiving device antenna circuit 602. Signal processing circuit 6
03 processes the signal received by the power receiving device antenna circuit 602 to charge the secondary battery 604,
It has a role of controlling power supply from the secondary battery 604 to the power supply circuit 607. Power circuit 6
07 has a role of converting the voltage stored in the secondary battery 604 into a voltage necessary for the power load portion 610. The modulation circuit 606 is used when a certain response is transmitted from the power receiving apparatus 600 to the power feeding apparatus 700.

By including the power supply circuit 607, the power supplied to the power load portion 610 can be controlled. For this reason, it is possible to reduce that an overvoltage is applied to the power load part 610, and deterioration and destruction of the power receiving apparatus 600 can be reduced.

In addition, by including the modulation circuit 606, a signal can be transmitted from the power receiving device 600 to the power feeding device 700. Therefore, the charging amount of the power receiving device 600 is determined, and when a certain amount of charging is performed, a signal is transmitted from the power receiving device 600 to the power feeding device 700, and power feeding from the power feeding device 700 to the power receiving device 600 is stopped. be able to. As a result, the number of times the secondary battery 604 is charged can be increased by not setting the amount of power received by the secondary battery 604 to 100%.

The power feeding device antenna circuit 701 sends a signal to the power receiving device antenna circuit 602.
Alternatively, it has a role of receiving a signal from the power receiving device antenna circuit 602. When a signal is transmitted to the power receiving device antenna circuit 602, the signal processing circuit 702 is a circuit that generates a signal to be transmitted to the power receiving device. The oscillation circuit 706 is a circuit that generates a signal having a constant frequency. The modulation circuit 704 has a role of applying a voltage to the power feeding device antenna circuit 701 in accordance with the signal generated by the signal processing circuit 702 and the signal of a certain frequency generated by the oscillation circuit 706. By doing so, a signal is output from the power feeding device antenna circuit 701. On the other hand, when a signal is received from the power receiving device antenna circuit 602, the rectifier circuit 703 has a role of rectifying the received signal. The demodulator circuit 705 receives the power receiving device 6 from the signal rectified by the rectifier circuit 703.
00 extracts the signal sent to the power supply device 700. The signal processing circuit 702 has a role of analyzing the signal extracted by the demodulation circuit 705.

Note that any circuit may be provided between the circuits as long as RF power feeding can be performed. For example, after the power receiving apparatus 600 receives a signal and generates a DC voltage by the rectifier circuit 605, the constant voltage may be generated by a circuit such as a DC-DC converter or a regulator provided in a subsequent stage. By doing so, it is possible to suppress application of an overvoltage inside the power receiving device 600.

The secondary battery according to one embodiment of the present invention includes the power receiving device 6 in the RF power feeding system described with reference to FIG.
00 is used as a secondary battery 604 of 00.

By using the secondary battery according to one embodiment of the present invention for the RF power feeding system, the discharge capacity or the charging capacity can be increased as compared with the conventional secondary battery, so that the time interval of wireless power feeding can be extended. (It can save the trouble of supplying power many times).

Further, by using the secondary battery according to one embodiment of the present invention for the RF power feeding system, if the discharge capacity or the charge capacity capable of driving the power load portion 610 is the same as the conventional one, the power receiving device 6
00 can be reduced in size and weight. Therefore, the total cost can be reduced.

Note that when the secondary battery according to one embodiment of the present invention is used for the RF power feeding system and the antenna circuit 602 for the power receiving device and the secondary battery 604 are stacked, the secondary battery 6 is charged and discharged by the secondary battery 604.
It is preferable that the impedance of the power receiving device antenna circuit 602 does not change due to the deformation of 04 and the change in the shape of the antenna accompanying the deformation. This is because if the impedance of the antenna changes, there is a possibility that sufficient power is not supplied. For example, the secondary battery 604 may be loaded into a metal or ceramic battery pack. At that time, it is desirable that the power receiving device antenna circuit 602 and the battery pack be separated from each other by several tens of μm or more.

In this embodiment, the frequency of the charging signal is not particularly limited, and any band may be used as long as power can be transmitted. The charging signal may be, for example, a 135 kHz LF band (long wave), a 13.56 MHz HF band (short wave), or 900 MHz.
The UHF band (ultra high frequency) of z to 1 GHz may be used, or the microwave band of 2.45 GHz may be used.

There are various signal transmission methods such as an electromagnetic coupling method, an electromagnetic induction method, a resonance method, and a microwave method, which may be selected as appropriate. However, in order to suppress energy loss due to moisture and other foreign matters such as rain and mud, a low frequency band, specifically, a short wave of 3 MHz to 30 MHz, a medium wave of 300 kHz to 3 MHz, and a long wave 30kHz ~
It is desirable to use an electromagnetic induction method or a resonance method using a frequency of 300 kHz and a super long wave of 3 kHz to 30 kHz.

This embodiment can be implemented in combination with the above embodiment.

In this example, a secondary battery which is one embodiment of the present invention will be described. In this example, a secondary battery which is one embodiment of the present invention and a comparative secondary battery (hereinafter referred to as a comparative secondary battery) were manufactured, and the characteristics were compared. The manufacturing process of the secondary battery electrode will be described below.

<Slurry production process>
First, a method for producing a slurry used for an electrode of a secondary battery will be described.

The slurry is composed of silicon particles (particle size is about 5 μm) used as an active material, particles containing niobium oxide, ketjen black (KB) as a conductive additive, and polyimide (PI) as a binder.
) And mixed. The weight ratio of each material is (silicon particles + particles with niobium oxide)
: KB: PI = 80: 5: 15. Further, silicon particles: particles having niobium oxide = 92: 8 were prepared at a weight ratio.

The silicon particles are preferably covered with niobium oxide, but if the coating ratio is too large, the resistance increases because niobium oxide is insulative. Therefore, the ratio of active material / (active material + niobium oxide) is preferably in the range of 0.7 to 0.999.

Here, a method for manufacturing the particles having niobium oxide will be described. First, with respect to 1 mol of niobium alkoxide (Nb (OCH ₂ CH ₃ ) ₅ ), the stabilizer ethyl acetoacetate 2
mol and toluene as a solvent were added and stirred to prepare a solution. Next, the niobium alkoxide in the solution gradually reacts with moisture in the atmosphere, and is condensed and gelled by the hydrolysis reaction shown in Chemical Formula 1. Water was added to the gel thus obtained and diluted about 70 times by weight,
A dispersion is prepared by stirring using an ultrasonic cleaner. Next, the dispersion is mixed with 50
By calcination at 0 ° C., a condensation reaction occurs, and niobium oxide (from Nb (OH) ₅ gel (
Particles with Nb ₂ O ₅ ) were produced.

The slurry was produced by the above process.

Next, an electrode of a secondary battery was formed by applying a slurry on the current collector to form an active material layer.

Titanium was used as a material for the current collector. As the current collector, a sheet-like titanium foil (also referred to as a titanium sheet) having a thickness of 17 μm was used.

Next, heat treatment was performed at 350 ° C. for 3 hours in a nitrogen atmosphere to dry the slurry. Then, it compressed with the press machine and punched the electrical power collector in the desired shape.

Finally, a drying treatment was performed at 100 ° C. for 12 hours in a nitrogen atmosphere.

Through the above steps, an electrode of a secondary battery was produced.

<Production process of secondary battery>
The manufacturing process of the secondary battery of this example is shown.

A secondary battery was manufactured using an electrode formed by forming an active material layer by applying a slurry on a current collector through the steps as described above. A method for manufacturing a secondary battery will be described below.

As shown in FIG. 7, the fabricated secondary battery includes a negative electrode 204, a positive electrode 232, a separator 210,
An electrolytic solution (not shown), a housing 206, and a housing 244 are included. In addition, a ring-shaped insulator 220 is provided. Lithium metal (lithium foil) was used for the negative electrode 204. As the positive electrode 232, an electrode manufactured by the above process was used. In this example, a titanium foil was used as the current collector of the electrode, and an active material layer was formed by the method shown in Embodiment Mode 1 to produce an electrode. Polypropylene was used for the separator 210 and the ring-shaped insulator 220. The housing 206 and the housing 244 are made of stainless steel (SUS). The housing 206 and the housing 244 are the negative electrode 2
04 and the positive electrode 232 are electrically connected to the outside.

The negative electrode 204, the positive electrode 232, and the separator 210 were impregnated with an electrolytic solution. Then, as shown in FIG. 7, the negative electrode 204, the separator 210, the ring insulator 220, the positive electrode 232, and the housing 244 are stacked and fixed in this order with the bottom of the housing 206 facing down, and the secondary battery is mounted. Produced.

As the electrolytic solution, a solution obtained by dissolving LiPF _{6 in} a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) was used.

<Production process of comparative secondary battery electrode>
Next, a process for manufacturing an electrode of the comparative secondary battery will be described. The secondary battery which is one embodiment of the present invention and the comparative secondary battery are different in the production process of the positive electrode, and the positive electrode of the comparative secondary battery is different in the slurry applied on the current collector. Since other configurations are common, they are omitted.

The slurry for preparing the electrode of the comparative secondary battery is prepared by mixing silicon particles (particle size is about 5 μm) used as an active material, ketjen black (KB) as a conductive additive, and polyimide (PI) as a binder. did. The weight ratio of each material is silicon particles: KB: PI = 80
: Produced at a ratio of 5:15.

The active material layer was formed by applying the slurry on the current collector as described above, and an electrode serving as the positive electrode of the comparative secondary battery was produced. A comparative secondary battery was produced using the positive electrode. The production of the comparative secondary battery was performed in the same manner as the production of the secondary battery except for the production process of the positive electrode.

<Characteristic comparison of secondary battery and comparative secondary battery>
About the secondary battery produced as mentioned above and a comparison secondary battery, the battery characteristic was compared using the charging / discharging measuring machine. A constant current method was adopted for the measurement of charging / discharging, and the initial discharge was measured at a current value corresponding to 0.5 C, and the subsequent discharge was measured at a current value reaching 2000 (mAh / g) in 2 hours. The measurement was performed at room temperature. The result is shown in FIG.

FIG. 8 shows the result of the lithium release amount with respect to the charge / discharge cycle. From this result, it was found that the secondary battery produced according to Embodiment 1 did not show a decrease in lithium release capacity even when the number of charge / discharge cycles increased compared to the comparative secondary battery.

From the result of FIG. 8, it was found that the secondary battery manufactured according to the first embodiment has improved cycle characteristics compared to the comparative secondary battery.

DESCRIPTION OF SYMBOLS 100 Active material layer 101 Current collector 103 Active material 109 Particle 151 Power storage device 153 Exterior member 155 Power storage cell 157 Terminal portion 159 Terminal portion 163 Negative electrode 165 Positive electrode 167 Separator 169 Electrode 171 Negative electrode current collector 173 Negative electrode active material layer 175 Positive electrode current collector Body 177 Positive electrode active material layer 204 Negative electrode 206 Case 210 Separator 220 Ring-shaped insulator 232 Positive electrode 244 Case 300 Car 302 Power storage device 600 Power reception device 601 Power reception device portion 602 Power reception device antenna circuit 603 Signal processing circuit 604 Secondary battery 605 Rectification circuit 606 Modulation circuit 607 Power supply circuit 610 Power supply load unit 700 Power supply device 701 Power supply device antenna circuit 702 Signal processing circuit 703 Rectification circuit 704 Modulation circuit 705 Demodulation circuit 706 Oscillation circuit 1301 Motor boat 1302 Power storage device 13 11 Electric Wheelchair 1312 Power Storage Device

Claims (1)

Having a step of attaching particles having niobium oxide to a granular active material;
The granular active material has silicon particles,
Niobium alkoxide is gradually reacted with moisture, and the niobium alkoxide is condensed by hydrolysis to produce a gel,
The granular active material is mixed with the gel, water is added to the mixed material to prepare a dispersion, and the dispersion is baked to attach the particles having the niobium oxide to the granular active material. Let
Production of an active material, characterized in that a ratio of the weight of the granular active material to the sum of the weights of the granular active material and the niobium oxide-containing particles is in the range of 0.7 to 0.999. Method.

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