KR102136899B1 - Active material, electrode, secondary battery, battery pack, electric vehicle, electric power storage system, electric power tool, and electronic apparatus - Google Patents

Abstract

The secondary battery comprises: a cathode; An anode containing an active material; And an electrolytic solution, the active material includes a central portion, and a coating portion provided on the surface of the central portion, the central portion contains silicon (Si) as a constituent element, and the coating portion contains carbon (C) and hydrogen (H) as constituent elements. One or more cations represented by C _x H _y (where x and y satisfy 2≤x≤6 and 3≤y≤9) are detected by cation analysis of the covering portion using the flight time type secondary ion mass spectrometry. .

Description

Active Materials, Electrodes, Secondary Batteries, Battery Packs, Electric Vehicles, Electric Power Storage Systems, Power Tools and Electronic Equipments

Cross reference to related applications

This application claims the priority of Japanese Priority Patent Application No. 2013-44020, filed on March 6, 2013, the entire contents of which are hereby incorporated by reference.

The present invention relates to an active material containing silicon (Si) as a constituent element, an electrode and a secondary battery using an active material, and a battery pack using a secondary battery, an electric vehicle, a power storage system, a power tool, and an electronic device.

Recently, various electronic devices such as mobile phones and personal digital assistants (PDAs) have been widely used, and miniaturization, light weight, and long life of electronic devices have been required. Accordingly, a battery as a power source for electronic devices, in particular, a small and lightweight secondary battery capable of providing a high energy density has been developed.

Nowadays, it has been considered to apply the above secondary battery to various uses other than electronic devices. Examples of the use other than the electronic device may include a battery pack detachably mounted on an electronic device or the like, an electric vehicle such as an electric vehicle, an electric power storage system such as a household electric power server, and an electric tool such as an electric drill. . In addition, uses other than the above examples may also be employed.

Secondary batteries using various charging and discharging principles have been proposed to obtain battery capacity. Particularly, a secondary battery using an insertion and extraction of an electrode reactant attracted attention because it provides a higher energy density than a lead battery, a nickel-cadmium battery, or the like.

The secondary battery includes a cathode, an anode, and an electrolyte. The anode includes an active material (anode active material) capable of occluding and releasing the electrode reactant. As the anode active material, carbon materials such as graphite are widely used. In recent years, since it is required to further improve the battery capacity, it is considered to use silicon. One of the reasons is that the theoretical capacity of silicon (4199 mAh/g) is significantly larger than the theoretical capacity of graphite (372 mAh/g), and the battery capacity is greatly improved.

However, since silicon expands and contracts violently when the electrode reactant is occluded and released (at the time of charging and discharging), the anode active material is apt to break mainly near the surface layer. When the anode active material breaks, a highly reactive new surface (active surface) is generated, and thus, the surface area (reaction area) of the anode active material increases. Thereby, the decomposition reaction of the electrolytic solution occurs on the new side, and the electrolytic solution is consumed to form a coating derived from the electrolytic solution on the new side, and thus the battery characteristics tend to deteriorate.

Therefore, in order to improve the battery characteristics, the configuration of the secondary battery has been studied in various ways. Specifically, in order to improve cycle characteristics and the like, the surfaces of particles such as silicon and silicon oxide are coated with graphite (for example, Japanese Patent Publication Nos. 2009-212074, 2011-090869, and 2011-076788) See). In order to improve the initial efficiency and the like, a silicon-silicon oxide-lithium complex doped with lithium is used (for example, see Japanese Patent No. 4985949). In order to improve overcharge and overdischarge characteristics, silicon oxide or silicon salts each containing lithium are used (for example, see Japanese Patent No. 2997741).

2. Description of the Related Art Since electronic devices and the like are increasingly high-performance and multi-functional, and frequency of use of electronic devices is also increasing, secondary batteries tend to be frequently charged and discharged. Therefore, it has been desired to further improve the battery characteristics of the secondary battery.

It is desirable to provide an active material, an electrode, a secondary battery, a battery pack, an electric vehicle, a power storage system, a power tool, and electronic equipment capable of obtaining excellent battery characteristics.

According to an embodiment of the invention, the center; And an active material including a covering provided on the surface of the center, wherein the center includes silicon (Si) as a constituent element, and the covering includes carbon (C) and hydrogen (H) as constituent elements, and C _x H _y (x and y are 2≤x≤6 and 3≤y≤9 by cation analysis of the coating part using time-of-flight secondary ion mass spectrometry (TOF-SIMS) Is satisfied) is detected.

According to an embodiment of the present invention, an electrode including an active material is provided, wherein the active material includes a central portion, and a coating portion provided on the surface of the central portion, the central portion comprising silicon (Si) as a constituent element, and the coating portion As a constituent element, carbon (C) and hydrogen (H) are included, and by cation analysis of a coating portion using a time-of-flight secondary ion mass spectrometry, C _x H _y (x and y are 2≤x≤6 and 3≤y ≤9).

In accordance with an embodiment of the present invention, a cathode; An anode containing an active material; And a secondary battery including an electrolyte, wherein the active material includes a central portion, and a coating portion provided on the surface of the central portion, and the central portion includes silicon (Si) as a constituent element, and the coating portion includes carbon (C) as a constituent element. ) And hydrogen (H), and C _x H _y (x and y satisfy 2≤x≤6 and 3≤y≤9) by cation analysis of the cladding using a flight-time secondary ion mass spectrometry. One or more cations indicated are detected.

According to an embodiment of the present invention, a secondary battery; A control unit configured to control the operation of the secondary battery; And a switch unit configured to switch the operation of the secondary battery according to the instructions of the control unit, wherein the secondary battery includes a cathode, an anode including an active material, and an electrolyte, and the active material includes a central portion and a central portion. Includes a coating provided on the surface, the central portion contains silicon (Si) as a constituent element, and the coating part contains carbon (C) and hydrogen (H) as constituent elements, and is coated using a time-of-flight secondary ion mass spectrometry. One or more cations represented by C _x H _y (x and y satisfy 2≤x≤6 and 3≤y≤9) are detected by negative cation analysis.

According to an embodiment of the present invention, a secondary battery; A conversion unit configured to convert power supplied from the secondary battery into driving power; A driving unit configured to operate according to the driving force; And a control unit configured to control the operation of the secondary battery, wherein the secondary battery includes a cathode, an anode including an active material, and an electrolyte, and the active material includes a central portion, and a coating provided on the surface of the central portion Containing parts, the central part contains silicon (Si) as a constituent element, and the covering part contains carbon (C) and hydrogen (H) as constituent elements, and by cation analysis of the covering part using a time-of-flight secondary ion mass spectrometry. , One or more cations represented by C _x H _y (x and y satisfy 2≤x≤6 and 3≤y≤9) are detected.

According to an embodiment of the present invention, a secondary battery; At least one electrical device configured to be supplied with power from the secondary battery; And a control unit configured to control supply of power from the secondary battery to one or more electric devices, wherein the secondary battery includes a cathode, an anode including an active material, and an electrolyte, and the active material is A central portion, and a coating portion provided on the surface of the central portion, the central portion contains silicon (Si) as a constituent element, and the coating portion includes carbon (C) and hydrogen (H) as constituent elements, and the time-of-flight secondary ion One or more cations represented by C _x H _y (where x and y satisfy 2≤x≤6 and 3≤y≤9) are detected by cation analysis of the coated portion using mass spectrometry.

According to an embodiment of the present invention, a secondary battery; And a movable part configured to supply electric power from the secondary battery, wherein the secondary battery includes a cathode, an anode containing an active material, and an electrolyte, and the active material includes a core, and a coating provided on the surface of the center Containing parts, the central part contains silicon (Si) as a constituent element, and the covering part contains carbon (C) and hydrogen (H) as constituent elements, and by cation analysis of the covering part using a time-of-flight secondary ion mass spectrometry. , One or more cations represented by C _x H _y (x and y satisfy 2≤x≤6 and 3≤y≤9) are detected.

According to an embodiment of the present invention, an electronic device including a secondary battery as a power supply is provided, wherein the secondary battery includes a cathode, an anode containing an active material, and an electrolyte, and the active material is on a central portion and a surface of the central portion It includes a coating provided in the center, the center contains silicon (Si) as a constituent element, the coating part contains carbon (C) and hydrogen (H) as constituent elements, and the cation of the coating part using a time-of-flight secondary ion mass spectrometry. By analysis, one or more cations represented by C _x H _y (x and y satisfy 2≤x≤6 and 3≤y≤9) are detected.

As a time-of-flight secondary ion mass spectrometry (TOF-SIMS) apparatus used for cation analysis, for example, TOF-SIMS V manufactured by ION-TOF can be used. Analysis condition is the primary ion species Bi ^{3 +,} the ion gun acceleration voltage is 25 kV, and a punching mode, wherein the irradiated ion current is 0.3 pA (measured in a pulse mode), the mass range is 1 amu and above to 800 amu or less , The scanning range is 200 μm×200 μm.

In the active material, the electrode, and the secondary battery according to the embodiment of the present invention, in the active material, the center portion contains silicon as a constituent element, and the coating portion contains carbon and hydrogen as a constituent element. In addition, one or more cations represented by C _x H _y (where x and y satisfy 2≤x≤6 and 3≤y≤9) are detected by cation analysis of a coating portion using a time-of-flight secondary ion mass spectrometry. Therefore, excellent battery characteristics can be obtained. In addition, similar effects can be obtained in the battery pack, the electric vehicle, the electric power storage system, the electric tool, and the electronic device according to the embodiment of the present invention.

It will be understood that the foregoing general description and the following detailed description are both exemplary and intended to provide further explanation of the invention as claimed.

The accompanying drawings are included to provide a further understanding of the present application, and are included in and constitute a part of this specification. The drawings illustrate embodiments and together with the specification serve to illustrate the principles of the invention.
1 is a cross-sectional view illustrating a configuration of an active material of an embodiment of the present invention.
2 is a scanning electron microscope (SEM) photograph of the surface of an active material.
3 is an SEM photograph of the surface of an active material in a comparative example.
4 is a cross-sectional view illustrating the configuration of a secondary battery (square) using the electrode of the embodiment of the present invention.
5 is a cross-sectional view taken along the line VV of the secondary battery illustrated in FIG. 4.
6 is a plan view schematically illustrating the configuration of the cathode and anode illustrated in FIG. 5.
7 is a cross-sectional view illustrating a configuration of a secondary battery (cylindrical) using the electrode of the embodiment of the present invention.
8 is a cross-sectional view illustrating an enlarged portion of a spiral wound electrode body illustrated in FIG. 7.
9 is an exploded perspective view illustrating a configuration of a secondary battery (laminated film type) using the electrode of the embodiment of the present invention.
10 is a cross-sectional view taken along line XX of the spiral wound electrode body illustrated in FIG. 9.
11 is a block diagram illustrating a configuration of a battery pack as an example of application of a secondary battery.
12 is a block diagram illustrating a configuration of an electric vehicle as an application example of a secondary battery.
13 is a block diagram illustrating a configuration of a power storage system as an example of application of a secondary battery.
14 is a block diagram illustrating a configuration of a power tool as an example of application of a secondary battery.

Embodiments of the present invention will be described in detail below with reference to the drawings. The description will be given in the following order.

1. Active material

2. Electrode and secondary battery

2-1. Square

2-2. Cylindrical

2-3. Laminate film type

3. Use of secondary battery

3-1. Battery pack

3-2. Electric vehicle

3-3. Power storage system

3-4. Power tools

[One. Active substance]

1 illustrates a cross-sectional configuration of an active material of an embodiment of the present invention. FIG. 2 is an SEM photograph of the surface of the active material illustrated in FIG. 1. 3 is a SEM photograph of the surface of the active material of the comparative example.

The active material described herein can be used, for example, in electrodes such as lithium ion secondary batteries. However, the active material may be used for the cathode as the cathode active material, or may be used for the anode as the anode active material.

[Composition of active substances]

As the above-described active material, the active material 1 includes, as illustrated in FIG. 1, a particulate center 2 and a covering 3 provided on the surface of the center 2.

In order to confirm the configuration of the active material 1 in which the central portion 2 is covered with the covering part 3, a cross section of the active material 1 can be observed using, for example, a microscope such as SEM. Alternatively, for example, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray analysis (EDX) The active material 1 can be analyzed using one or more of methods such as ray spectroscopy.

Note that when the active material 1 at the electrode is mixed with other materials such as a binder and a conductive agent, the active material 1 can be separated from the other materials using, for example, a centrifuge. Further, after the secondary battery using the electrode is completely formed, it may be desirable to observe and analyze a part of the active material 1 in the non-opposite region, as will be described later.

[center]

The central portion 2 is an inner-core portion of the active material 1, and mainly has a function of occluding and releasing electrode reactants. An example of the "electrode reactant" may include lithium (lithium ion) in the case of a lithium ion secondary battery. The central portion 2 includes an active material capable of occluding and releasing electrode reactants. Since silicon has a high energy density and therefore a high battery capacity can be obtained, the active material contains silicon (Si) as a constituent element. However, the active material may include one or more other elements as other constituent elements together with silicon.

The active material is not particularly limited as long as it is at least one material containing silicon as a constituent element. That is, the active material may be any of simple substances, alloys, and compounds of silicon. When the active material contains silicon as a constituent element, a high energy density can be obtained without depending on the type of the active material. The term "organization" as used herein simply refers to a general organization and does not necessarily refer to an organization with a purity of 100%. Therefore, the silicon alone may contain trace impurities.

Silicon alloy is a constituent element other than silicon, for example, tin (Sn), nickel (Ni), copper (Cu), iron (Fe), cobalt (Co), manganese (Mn), zinc (Zn), It may include one or more elements such as indium (In), silver (Ag), titanium (Ti), germanium (Ge), bismuth (Bi), antimony (Sb) and chromium (Cr). The silicon compound may contain one or more of carbon, oxygen, and the like as constituent elements other than silicon. Note that, for example, a silicon compound may include one or more of elements described for a silicon alloy as a constituent element other than silicon.

Specific examples of silicon alloys and silicon compounds are SiB ₄ , SiB ₆ , Mg ₂ Si, Ni ₂ Si, TiSi ₂ , MoSi ₂ , CoSi ₂ , NiSi ₂ , CaSi ₂ , CrSi ₂ , Cu ₅ Si, FeSi ₂ , MnSi ₂ , NbSi ₂ , TaSi ₂ , VSi ₂ , WSi ₂ , ZnSi ₂ , SiC, Si ₃ N ₄ , Si ₂ N ₂ O, SiO _w (0<w≤2) and LiSiO.

The active material may preferably contain oxygen (O) as a constituent element together with silicon. One of the reasons is that in this case, the irreversible capacity decreases during charging and discharging (especially during initial charging and discharging), so that higher battery capacity can be obtained. Specifically, it may be preferable that the active material includes silicon oxide represented by SiO _w (0<w≤2).

The composition of silicon oxide (SiO _w ) is not particularly limited as long as the above condition (0<w≤2) is satisfied. In particular, it may be desirable that w satisfies 0.3 ≤ w <1.9, because the electrode reactant is easily occluded and released from the central portion 2.

In the central portion 2 including silicon oxide, silicon and oxygen as constituent elements of the silicon oxide may be distributed in any state. Specifically, the abundance (atomic amount) of silicon may be constant in the direction from the surface (top surface) of the center 2 to the inside (center), or may change (increase or decrease) in the direction. When the atomic mass of silicon changes, the atomic mass may change continuously (increase or decrease gradually), or the atomic mass may change intermittently (increase or decrease rapidly).

On the surface of the central portion 2, that is, on the interface between the central portion 2 and the covering portion 3, the ratio of the atomic atomic weight to the atomic oxygen content (atomic ratio: Si/O) is not particularly limited. In particular, the atomic ratio may be preferably 75 atomic% or less, and more preferably 30 atomic% or more to 70 atomic% or less. One of the reasons is that in this case, the electrode reactant is easily occluded and discharged from the central portion 2, and the electrical resistance of the central portion 2 is lowered.

More specifically, when the atomic ratio is less than 30 atomic%, the oxygen atomic amount becomes too large with respect to the silicon atomic weight, and electrical resistance tends to increase. On the other hand, when the atomic ratio is greater than 75 atomic% (or 70 atomic%), the silicon atomic mass becomes too large for the oxygen atomic mass, so that the electrode reactant is easily occluded and released in the central portion 2, whereas charge and discharge are repeated In this case, silicon is liable to deteriorate (surface deterioration).

The atomic ratio is calculated by [atomic ratio (atomic %) = (silicon atomic mass/oxygen atomic mass)x100]. To measure the atomic weight of each of silicon and oxygen, the center 2 surface may be analyzed using, for example, a transmission electron microscope (TEM) and an energy dispersive X-Ray analysis (EDX) device. The TEM may be, for example, JEM-2100F manufactured by JEOL, and the EDX apparatus may be JED-2300T manufactured by JEOL, for example. As measurement conditions, for example, the acceleration voltage is 200 kV, the beam current is 240 pA, the beam diameter is 0.15 mm, and the analysis (integration) time is 30 seconds.

In order to confirm the composition of silicon oxide (SiO _w ), the oxidation degree (value of atomic ratio w) of the central portion 2 can be investigated. In this case, for example, in order to obtain the central portion 2, an acid such as hydrogen fluoride (HF) can be used to dissolve and remove the covering 3.

Note that the active material may preferably contain at least one metal element as a constituent element, because this is because the electrical resistance of the central portion 2 is lowered. As a result, even when the central portion 2 contains high-resistance silicon oxide, the electrical resistance of the entire active material 1 is kept low. In the central portion 2, any metal element may exist separately (in glass) from silicon, or may form an alloy or compound with silicon. The chemical state (for example, the bonding state of metal atoms) of the central portion 2 containing any metal element can be confirmed, for example, using an EDX device or the like.

Although the type of the metal element is not particularly limited, for example, the type of the metal element is iron (Fe), aluminum (Al), calcium (Ca), manganese (Mn), chromium (Cr), magnesium (Mg), Nickel (Ni), boron (B), titanium (Ti), vanadium (V), cobalt (Co), copper (Cu), germanium (Ge), yttrium (Y), zirconium (Zr), molybdenum (Mo) ), silver (Ag), indium (In), tin (Sn), antimony (Sb), tantalum (Ta), tungsten (W), lead (Pb), lanthanum (La), cesium (Ce), plutonium (Pr) ), neodymium (Nd) or the like. In particular, one or more of iron, aluminum, calcium, manganese, chromium, magnesium and nickel may be preferable, because this effectively reduces the electrical resistance of the central portion 2.

The crystal state of the central portion 2 is not particularly limited, and may be crystalline or amorphous. In particular, it may be preferable that the crystalline state of the central portion 2 is amorphous or low crystalline. One of the reasons is that in this case, even when the active material 1 expands and contracts during charging and discharging, there is less possibility that the active material 1 is damaged (eg, broken).

Specifically, the term “low crystallinity” refers to a state in which a crystalline region (crystal grain) is scattered in an amorphous region. More specifically, the term, in the case of observing the cross-section or surface of the central portion 2 using a high-angle annular dark-field scanning transmission electron microscopy (HAADF STEM), etc., crystalline region (crystal grain) and amorphous region Refers to the mixed crystal state. When the state in which the amorphous region and the crystal region are mixed is confirmed by a TEM photograph, the crystal state of the central portion 2 is low crystallinity. Note that, in the case where the amorphous region and the crystal region are mixed, the crystal regions are observed as regions (grains) each having a contour of a granular shape. In each crystal grain, a stripe pattern due to crystallinity (crystal lattice stripes) is observed, so it is possible to discriminate the crystal grain from the amorphous region. On the other hand, the term "amorphous" is synonymous with the so-called amorphous state, and refers to a crystal state in which only the amorphous region exists and the crystal region does not exist when observing the central portion 2 using HAADF STEM or the like. Note that although the magnification in observation is not particularly limited, the magnification may be, for example, 1.2x10 ⁶ .

Whether the crystalline state is amorphous or low crystalline can be determined based on the TEM photograph. When the crystal state of the central portion 2 is amorphous, only the amorphous regions exist and no crystal regions (crystal grains each having crystal lattice lines). On the other hand, when the crystal state of the central portion 2 is low crystalline, crystal grains are scattered in the amorphous region. Each crystal grain has crystal lattice lines at predetermined intervals according to the lattice spacing d of silicon, so that the crystal grains are clearly distinguished from the surrounding amorphous regions.

When the crystal state of the central portion 2 is low crystallinity, the degree of crystallinity is not particularly limited. In particular, the average area occupancy of the crystal grains resulting from the (111) and (220) planes of silicon may be preferably 35% or less, and the average grain size of the crystal grains may be 30 nm or less. One of the reasons is that in this case, since the active material 1 is less likely to expand and contract during charging and discharging, the probability of breakage is less.

The process of calculating the average area share is as follows. First, a cross section of the central portion 2 is observed using a HAADF STEM to obtain a TEM photograph. In this example, the observation magnification is 1.2x10 ⁶ and the observation area is 65.6 nm x 65.7 nm. Next, the presence or absence of crystal lattice lines, the lattice spacing (d) value, and the like are investigated to identify regions where crystal grains originating from the (111) plane and crystal grains originating from the (220) plane exist. Thereafter, the outline of the crystal grains is depicted in the TEM photograph. The crystal grains originating from the (111) plane refer to crystal regions each having a crystal lattice line with a lattice spacing (d) of 0.31 nm, and the crystal grains originating from the (220) plane have a lattice spacing (d) of 0.19 nm. Refers to the crystal regions each having a line. Subsequently, after calculating each area of each crystal grain, [area share (%) = (sum of crystal grain area/observed area) x 100] is calculated. Delineation of grain contours and calculation of area occupancy may be performed manually, or may be performed mechanically using dedicated processing software or the like. Finally, after repeating the work of calculating the area share for 40 areas, the average value (average area share) of the area share calculated in each area is calculated.

The process of calculating the average particle size of the crystal grains is calculated in the case of calculating the average area share, except that after measuring each average particle diameter for each region, calculating the average value (final average particle diameter) of the measured average particle diameter It is similar to the process. When measuring the grain size of a grain, for example, after converting the contour of the grain to a circle (specifying a circle having the same area as the area defined by the contour of the grain), the diameter of the circle is regarded as the grain size Pay attention to. The calculation of the average particle diameter can be performed manually or mechanically, as in the calculation of the average area share.

Although the average particle diameter of the central portion 2 (middle diameter D50) is not particularly limited, it is particularly preferable that the average particle diameter of the central portion is 0.1 µm or more to 20 µm or less. One of the reasons is that in this case, there is less possibility that the active material 1 is damaged during charging and discharging, and high stability is obtained. More specifically, when D50 is less than 0.1 μm, due to an excessive increase in the surface area (reaction area) of the central portion 2, the decomposition reaction of the electrolytic solution or the like is promoted, and safety is likely to be lowered. On the other hand, when D50 is larger than 20 μm, the active material 1 is easily damaged due to expansion during charging, and it is difficult to apply the slurry containing the active material 1 in the electrode manufacturing step.

When the average particle diameter of the central portion 2 is investigated, the average particle diameter of the central portion 2 may be measured, or the average particle diameter of the central portion 2 may be calculated using the active material 1. In the case of using the active material 1, after obtaining the average particle diameter (medium diameter (D50)) of the active material 1 by laser analysis (diffraction), for example, avoiding described below in the average particle diameter of the active material 1 The value obtained by subtracting the average thickness of the abdomen 3 can be obtained, and the obtained value can be regarded as the average particle diameter of the center 2. When the average thickness of the coating portion 3 is remarkably small, specifically, 200 nm or less, the average particle diameter of the active material 1 obtained by laser analysis is regarded as a value substantially corresponding to the average particle diameter of the central portion 2 Note that it can be.

Note that in the central portion 2, some or all of the constituent element silicon may be preferably alloyed with the electrode reactant in the uncharged state. That is, in the central portion 2 in the non-charged state, it may be desirable that the electrode reactant is previously occluded (so-called pre-doping) in the central portion 2. One of the reasons is that in this case, the irreversible capacity during initial charge/discharge is reduced, so that higher battery capacity can be obtained. Whether or not the central portion 2 is pre-doped may be determined by irradiating a part of the active material 1 in the non-opposite region in a completely formed secondary battery, as described later.

In particular, when the active material 1 is used in a lithium ion secondary battery, it may be preferable that the central portion 2 includes lithium silicate. One of the reasons is that in this case, the central portion 2 is pre-doped, so that the irreversible capacity decreases as described above.

[Skin]

The covering portion 3 is an outer portion of the active material 1 and mainly has a function of physically and chemically protecting the central portion 2. The covering portion 3 contains a conductive material, and the conductive material contains carbon (C) and hydrogen (H) as constituent elements. One of the reasons why the covering portion 3 contains carbon as a constituent element is that in this case, high conductivity is obtained, and the electrical resistance of the entire active material 1 is lowered. Therefore, even when the central portion 2 contains high-resistance silicon oxide, the electrical resistance of the entire active material 1 is kept low. However, the covering portion 3 may include one or more other elements as constituent elements together with carbon and hydrogen.

Note that the covering 3 can be provided on part or all of the surface of the center 2. That is, the covering portion 3 may cover only a part of the surface of the central portion 2 or may cover the entire surface of the central portion 2. In the former case, the covering portion 3 may exist in a plurality of places on the surface of the central portion 2. In addition, the covering portion 3 may have a single-layer structure or a multi-layer structure.

As described above, since the covering portion 3 contains carbon and hydrogen as constituent elements, the covering portion 3 includes a hydrocarbon component together with a carbon component and a hydrogen component. The composition (carbon and hydrogen bonding state) of the hydrocarbon component included in the coating 3 is appropriately set in relation to the reactivity of the coating 3.

More specifically, C _x H _y (x and y is 2≤x≤6 and 3≤y≤ by performing cation analysis of the coating part 3 using a time-of-flight secondary ion mass spectrometry (TOF-SIMS) 9 is satisfied). One of the reasons why the cation is detected by the cation analysis of the coating 3 is that in this case, the reactivity on the surface of the coating 3 is reduced. Thereby, the decomposition reaction of the electrolytic solution is suppressed, and the irreversible reaction (side reaction) that inhibits the storage and release of the electrode reactant is also suppressed. Note that when the above-mentioned value x is larger than 6, the covering portion 3 becomes chemically unstable, and the adhesion of the covering portion 3 to the central portion 2 is significantly reduced.

In the following description, cations that satisfy the composition conditions will be referred to as “specific ions”, and cations that do not satisfy the conditions will be referred to as “other ions”, respectively.

The type of specific ion is not particularly limited as long as the above-described composition conditions are satisfied. For example, the type of specific ion is C ₂ H ₃ , C ₂ H ₄ , C ₂ H ₅ , C ₃ H ₅ , C ₃ H ₇ , C ₄ H ₈ , C ₄ H ₉ , C ₅ H ₇ and C ₆ H ₅ . However, certain ions of the kind described above are only examples, which are part of cations each having a relatively high detection intensity. Therefore, cations other than the above-described cations can be adopted as long as the above composition conditions are satisfied. Meanwhile, examples of other ions may include one or more of C, CH ₂ and CH ₃ .

As the TOF-SIMS device used for the cation analysis, for example, TOF-SIMS V manufactured by ION-TOF can be used. Analysis conditions, the primary ion species Bi ^{3 +,} and the ion gun acceleration voltage is 25 kV, the punching mode, and the irradiated ion current is 0.3 pA (measured in a pulse mode), the mass range is 1 amu or more to 800 amu or less, and , The scanning range is 200 μm×200 μm.

To investigate whether a specific ion is detected, it is possible to obtain a TOF-SIMS spectrum (horizontal axis: mass, vertical axis: intensity) that includes, for example, peaks due to a plurality of cations. It is possible to determine whether a specific ion is detected by specifying the type of cation from the detection position (mass) of each peak.

As long as a specific ion is detected by cation analysis of the coating 3, the detection strength of the specific ion is not particularly limited. In particular, of certain ions, C ₂ H ₃ , C ₂ H ₅ And The ratio (D1/D2) between the sum (D1) of the detection strengths of the cations represented by C ₃ H ₅ and the detection strength (D2) of C (x=1 and y=0 in C _x H _y ) is preferably 1.25 or more. It can be, and more preferably 50 or more. In addition, C ₂ H ₃ , C ₂ H ₅ And the ratio (D1/D3) between the sum (D1) of the detection intensity of the cations represented by C ₃ H ₅ and the sum (D3) of the detection intensity of the cations represented by CH _z (z satisfies 0≤z≤3). Larger may be desirable. In both cases, the reactivity on the surface of the covering 3 is further reduced. In particular, when the ratio D1/D2 is 50 or more, the mixed state of the slurry containing the active material 1 (for example, the dispersibility of the active material 1) described later becomes good, the coating surface becomes smooth and the coating thickness is uniform. Is done. Note that the type of cation represented by CH _z (z satisfies 0≤z≤3) may be one or more of C, CH, CH ₂ and CH ₃ .

The surface of the coating 3 where specific ions are detected by TOF-SIMS has a characteristic structure. Specifically, a fine uneven structure due to a specific ion is formed on the surface of the coating 3 where a specific ion is detected, as illustrated in FIG. 2. In this case, the adhesiveness of the binder or the like to the active material 1 is improved, so that the active material 1 is less likely to peel off the binder or the like. Therefore, as will be described later, when the electrode including the binder with the active material 1 is wound in a spiral, the likelihood of the electrode collapsing is less, thereby improving the so-called electrode winding characteristics. On the other hand, a fine uneven structure due to a specific ion is not formed on the surface of the covering portion 3 in which a specific ion is not detected, as illustrated in FIG. 3, so that the surface is substantially flat.

Although the average thickness of the covering portion 3 is not particularly limited, in particular, the average thickness thereof may be as thin as possible, specifically, it may be preferable to be 500 nm or less. One of the reasons is that, in this case, the electrode reactant is easily occluded and released in the central portion 2. However, it may be preferable that the average thickness of the covering portion 3 is 20 nm or more. One of the reasons is that when the covering portion 3 is excessively thin, the active material 1 is fragile during charging and discharging.

The average thickness of the covering portion 3 is calculated by the following procedure. First, one active material 1 is observed using SEM or the like. The magnification upon observation may be preferably a magnification capable of visually confirming (determining) the interface between the central portion 2 and the covering portion 3 to measure the thickness of the covering portion 3. Subsequently, the thickness of the covering portion 3 is measured at arbitrary 10 positions, and its average value (average thickness T per one active material 1) is calculated. In this case, it may be desirable to set the measurement location so that it is not concentrated around a specific place and is distributed as widely as possible. Subsequently, the average value calculation operation is repeated until the total number of active material 1 observed by SEM reaches 100. Finally, the average value (average thickness of each average thickness) calculated for 100 active materials 1 (average thickness per each active material 1) is calculated, and the obtained value is the average thickness of the coating 3 It is considered as.

Although the average coverage of the covering portion 3 with respect to the central portion 2 is not particularly limited, it is particularly preferable that the average coverage thereof is as large as possible, specifically, 30% or more (30% or more and 100% or more) Or less) may be preferred. One of the reasons is that in this case, the reactivity on the surface of the covering portion 3 is effectively reduced.

The average covering ratio of the covering portion 3 is calculated by the following procedure. First, as in the case of calculating the average thickness, one active material 1 is observed using SEM or the like. The magnification when observing may be preferably a magnification in which the portion covered with the covering portion 3 and the portion not covered with the covering portion 3 can be visually identified in the central portion 2. Subsequently, at the outer edge (contour) of the center 2, the length of the portion covered with the covering portion 3 and the length of the portion not covered with the covering portion 3 are measured. Then, [Coverage rate (coverage rate per active material 1: %) = (Length of the part covered with the covering part 3 / Length of the outer edge of the center part 2) x 100] is calculated. Subsequently, the above-mentioned coverage calculation operation is repeated until the total number of the numbers observed by the SEM reaches 100. Lastly, the average value of the coverage ratio (coverage ratio of each active substance 1) calculated for 100 active substances 1 is calculated, and the calculated value is regarded as the average coverage ratio of the coating portion 3.

In general, when analyzing a carbon material by the Raman spectrum method, in the analysis result (Raman spectrum), the G band peak derived from the graphite structure is detected in the vicinity of 1590 cm ^-1 , and the D band peak derived from the defect is 1350 It is detected in the vicinity of cm- ¹ . The ratio (IG/ID) between the intensity (IG) of the G band peak and the intensity (ID) of the D band peak is also referred to as the G/D ratio, and is an indicator of the crystal state (purity) of the carbon material.

Although the ratio (IG/ID) of the coating portion 3 containing carbon as a constituent element is not particularly limited, the ratio (IG/ID) may be preferably 0.3 or more and 3 or less, and the vicinity of 2 is more It may be desirable. One of the reasons is that in this case, excellent binding properties, excellent conductivity and excellent deformability can be obtained.

More specifically, when the ratio (IG/ID) is less than 0.3, the binding property increases, so that the adhesion between each individual coating part 3 and the adhesion of the coating part 3 to the central portion 2 are improved. However, in this case, the conductivity is lowered and the covering portion 3 becomes hard, so as to the expansion and contraction of the active material 1, the possibility that the covering portion 3 expands and contracts may be less, and excellent There is a possibility that conductivity may not be obtained. On the other hand, when the ratio (IG/ID) is greater than 3, the conductivity increases, and the covering portion 3 softens, so that the covering portion 3 is easy to expand and contract in relation to expansion and contraction of the active material 1 Sufficient conductivity is obtained. However, in this case, the binding property is lowered, and there is a possibility that the adhesion between the respective coating parts 3 and the adhesion of the coating part 3 to the central portion 2 decrease. On the other hand, when the ratio (IG/ID) is 0.3 or more and 3 or less, the binding property and conductivity of the coating part 3 increase, and the coating part 3 expands and contracts in relation to the expansion and contraction of the active material 1 Easy to be

When using the Raman spectrum method, for example, the analyte can be irradiated with laser light (wavelength: 523 nm) so that the irradiated intensity on the analyte is 0.3 mW, and a Raman spectrum device having a broken line resolution of 4 cm ^-1 is used. use.

[Method of manufacturing active material]

The active material 1 is produced, for example, by the following procedure.

First, a central portion 2 capable of occluding and releasing electrode reactants is prepared. The forming material (active material) of the central portion 2 is not particularly limited as long as the material is a particulate (powder) containing silicon as a constituent element. Further, although the formation method of the central portion 2 is not particularly limited, for example, one or more of a gas atomization method, a water atomization method, a fusion pulverization method, or the like. Can be used. In this case, it is possible to control the crystal state of the central portion 2 by changing conditions such as the formation temperature of the central portion 2. Note that by melting the metal material together with the active material, a metal element such as iron can be included in the central portion 2 together with silicon.

When forming the central portion 2 containing silicon oxide, the silicon oxide can be obtained by one or more of, for example, a gas spraying method, a water jetting method, or a melt grinding method. In this case, the composition (degree of oxidation) of silicon oxide can be controlled by introducing gases such as hydrogen (H ₂ ) and oxygen (O ₂ ) and adjusting conditions such as the amount of gas introduced. Thereafter, the surface of the silicon oxide can be reduced by heating the silicon oxide. In this case, the atomic ratio (Si/O) on the surface of the central portion 2 can be controlled by a gas such as hydrogen or by changing conditions such as pressure, heating temperature, and gas introduction amount.

Subsequently, a covering portion 3 is formed on the surface of the central portion 2. The method of forming the covering 3 may be, for example, a vapor deposition method. The vapor deposition method may be, for example, one or more of vapor deposition, sputtering, and CVD. Particularly, a pyrolysis CVD method may be preferable, because it is easy to control the kind of cation and the like detected by TOF-SIMS. In the case of forming the covering 3, the type of cation and the like can be controlled by adjusting conditions such as the formation method, the carbon source gas used for the thermal decomposition reaction (type and amount introduced), the thermal decomposition temperature, and the auxiliary gas (type and amount introduced). Can. The carbon source gas can be, for example, one or more hydrocarbons such as methane gas (CH ₃ ) and acetylene (C ₂ H ₂ ). The auxiliary gas can be, for example, one or more of hydrogen and argon (Ar).

As a result, the covering portion 3 is provided on the surface of the central portion 2, and specific ions are detected by cation analysis of the covering portion 3 using TOF-SIMS, and the active material 1 is completed.

Note that although the method for pre-doping the active material 1 is not particularly limited, for example, a powder mixing method, a vapor deposition method, or the like can be used. In the powder mixing method, for example, after mixing the active material 1 and the lithium metal powder, the mixture is heated under an inert atmosphere. In the deposition method, for example, after preparing an electrode including the active material 1, a deposition process is performed on the electrode using lithium metal as a deposition source.

[Action and effect of active substance]

In the active material 1, a coating portion 3 comprising carbon and hydrogen as constituent elements is provided on the surface of the central portion 2 containing silicon as constituent elements. In addition, specific ions are detected by cation analysis of the coating 3 using TOF-SIMS. In this case, as described above, the electrical resistance of the entire active material 1 is lowered. In addition, since the reactivity on the surface of the coating portion 3 decreases, the decomposition reaction of the electrolytic solution is suppressed, and the irreversible reaction (side reaction) that inhibits the storage and release of the electrode reactant is also suppressed. Therefore, it is possible to improve the battery characteristics of the secondary battery using the active material 1.

In particular, certain ions (C ₂ H ₃ , C ₂ H ₅ And If the ratio (D1/D2) between the sum (D1) of the detection strengths of C ₃ H ₅ and the detection strength (D2) of the other ions (C) is 1.25 or higher, a higher effect can be obtained. In addition, specific ions (C ₂ H ₃ , C ₂ H ₅ And the ratio (D1/D3) between the sum (D1) of the detection intensity of C ₃ H ₅ and the sum (D3) of the detection intensity of other ions (CH _z (z satisfies 0≤z≤3)) In large cases, a higher effect can be obtained.

[2. Electrode and secondary battery]

Next, an example of application of the active material will be described. The active material is used in electrodes and secondary batteries as follows.

[2-1. Square]

4 and 5 illustrate a cross-sectional configuration of a prismatic secondary battery. 5 illustrates a cross-section taken along line V-V of the secondary battery illustrated in FIG. 4. 6 schematically illustrates the planar configuration of the cathode 21 and anode 22 illustrated in FIG. 5.

[Overall configuration of secondary battery]

The secondary battery described herein is a lithium ion secondary battery in which the capacity of the anode 22 is obtained by occluding and releasing lithium (lithium ion) as an electrode reactant, and has a so-called prismatic battery structure. In this example, an electrode is applied to the anode 22.

The secondary battery may include the battery element 20 inside the battery can 11, for example. The battery element 20 can be formed, for example, by laminating the cathode 21 and the anode 22 with the separator 23 interposed therebetween, and then spirally winding the obtained laminate. The battery element 20 has a flat shape corresponding to the shape of the battery can 11.

The battery can 11 may be, for example, a rectangular exterior member. As illustrated in FIG. 5, the prismatic sheathing member has a rectangular or substantially rectangular shape (including curves on a part) in the longitudinal section, and is applicable not only to rectangular prismatic cells, but also to elliptical prismatic cells. That is, the rectangular exterior member has a rectangular opening or a substantially rectangular (elliptical) opening obtained by connecting arcs in a straight line, a serving-dish-shaped serving of a rectangular shape having a base portion or an elliptical shape having a base portion. It is dish-like. Note that FIG. 5 illustrates a case where the battery can 11 has a rectangular cross-sectional shape.

The battery can 11 may be formed of one or more of, for example, iron, aluminum, and alloys thereof, and may have a function as an electrode terminal. In particular, iron that is harder than aluminum may be preferred to use stiffness (hard to deform) to suppress the swollenness of the battery can 11 during charging and discharging. Note that when the battery can 11 is formed of iron, the surface of the battery can 11 may be plated with nickel or the like.

Further, the battery can 11 may have, for example, a hollow structure in which one end of the battery can 11 is opened and the other end of the battery can 11 is closed. The battery can 11 is sealed by an insulating plate 12 and a battery cover 13 attached to an open end. The insulating plate 12 is provided between the battery element 20 and the battery cover 13, and may be formed of an insulating material, for example, polypropylene. The battery cover 13 can be formed of, for example, a material similar to the battery can 11, and can function as an electrode terminal like the battery can 11.

Outside the battery cover 13, a terminal plate 14 is provided as a cathode terminal. The terminal plate 14 is electrically insulated from the battery cover 13 with an insulating case 16 interposed therebetween. The insulating case 16 may be formed of an insulating material, for example, polyethylene terephthalate. A through-hole is provided at a substantially center of the battery cover 13. The cathode pin 15 is inserted into the through hole so that the cathode pin 15 is electrically connected to the terminal plate 14 and electrically isolated from the battery cover 13 with the gasket 17 interposed therebetween. The gasket 17 can be formed of an insulating material, for example. The surface of the gasket 17 can be applied with asphalt.

In the periphery of the battery cover 13, a cleavage valve 18 and an injection hole 19 are provided. The opening valve 18 is electrically connected to the battery cover 13. When the internal pressure of the battery becomes a certain level or higher due to internal short circuit, external heating, or the like, the opening valve 18 is separated from the battery cover 13 to open the internal pressure. The injection hole 19 may be sealed by a sealing member 19A, for example, a stainless corundum.

A cathode lead 24 formed of a conductive material such as aluminum can be attached to the end (eg, the inner end) of the cathode 21. An anode lead 25 formed of a conductive material such as nickel may be attached to the end (eg, the outer end) of the anode 22. The cathode lead 24 can be welded to one end of the cathode pin 15 and can be electrically connected to the terminal plate 14. The anode lead 25 can be welded to the battery can 11 and electrically connected to the battery can 11.

[Cathode]

The cathode 21 has a cathode active material layer 21B on one side or both sides of the cathode current collector 21A. The cathode current collector 21A may be formed of a conductive material such as aluminum, nickel and stainless steel, for example.

The cathode active material layer 21B includes, as a cathode active material, one or more cathode materials capable of occluding and releasing lithium ions. The cathode active material layer 21B may further include one or more other materials such as a cathode binder and a cathode conductive agent.

The cathode material may be preferably a lithium-comprising compound, since a high energy density is thereby obtained. Examples of the lithium-comprising compound may include a lithium transition metal complex oxide and a lithium transition metal phosphate compound. The lithium transition metal composite oxide is an oxide containing lithium (Li) and one or more transition metal elements as constituent elements. The lithium transition metal phosphate compound is a phosphoric acid compound containing lithium and one or more transition metal elements as constituent elements. In particular, the transition metal element may be preferably one or more of cobalt (Co), nickel (Ni), manganese (Mn), iron (Fe), etc., because a higher voltage is thereby obtained. The chemical formula of the lithium transition metal composite oxide may be represented by, for example, Li _x M1O ₂ , and the chemical formula of the lithium transition metal phosphate compound may be represented by, for example, Li _y M2PO ₄ . In the formula, M1 and M2 represent one or more transition metal elements. The x and y values change depending on the state of charge and discharge, and may be, for example, in the range of 0.05≤x≤1.10 and 0.05≤y≤1.10.

Specific examples of the lithium transition metal complex oxide may include LiCoO ₂ , LiNiO ₂ , and a lithium-nickel complex oxide represented by the following formula (1). Specific examples of the lithium transition metal phosphate compound may include LiFePO ₄ and LiFe _{1 -u} Mn _u PO ₄ (u<1), because high battery capacity is obtained, excellent cycle characteristics, etc. are also obtained. .

LiNi _{1 - z} M _z O ₂ .....(1)

In formula (1), M is cobalt (Co), manganese (Mn), iron (Fe), aluminum (Al), vanadium (V), tin (Sn), magnesium (Mg), titanium (Ti), strontium (Sr), Calcium (Ca), Zirconium (Zr), Molybdenum (Mo), Technetium (Tc), Ruthenium (Ru), Tantalum (Ta), Tungsten (W), Rhenium (Re), Ytterbium (Yb) , Copper (Cu), zinc (Zn), barium (Ba), boron (B), chromium (Cr), silicon (Si), gallium (Ga), phosphorus (P), antimony (Sb), and niobium (Nb) ); z satisfies 0.005<z<0.5.

In addition to this, the cathode material may be, for example, one or more of oxide, disulfide, chalcogenide, conductive polymer, and the like. Examples of the oxide may include titanium oxide, vanadium oxide and manganese dioxide. Examples of the disulfide may include titanium disulfide and molybdenum sulfide. Examples of chalcogenides can include niobium selenide. Examples of the conductive polymer may include sulfur, polyaniline and polythiophene. However, the cathode material is not limited to one of the above materials, and may be other materials.

Examples of the cathode binder may include one or more of synthetic rubber, polymer material, and the like. Examples of the synthetic rubber may include styrene-butadiene rubber, fluorine rubber and ethylene propylene diene. Examples of the polymer material may include polyvinylidene fluoride and polyimide.

Examples of the cathode conductive agent may include one or more of carbon materials and the like. Examples of the carbon material may include graphite, carbon black, acetylene black and ketjen black. Note that the cathode conductive material can be other materials, such as metallic materials and conductive polymers, as long as the material is conductive.

[Anode]

The anode 22 has an anode active material layer 22B on one side or both sides of the anode current collector 22A.

The anode current collector 22A may be formed of a conductive material such as copper, nickel and stainless steel, for example.

When the anode current collector 22A contains copper as a constituent element, it may be preferable that the anode current collector 22A further includes carbon (C) and sulfur (S) as constituent elements. One of the reasons is that, in this case, the physical strength (durability) of the anode current collector 22A is improved, so that the anode current collector 22A is deformed even when the anode active material layer 22B expands and contracts during charging and discharging. It is less likely to break or break (eg, break). Specifically, the anode current collector 22A may be, for example, a copper foil doped with carbon and ions. Although the sum of the respective contents of carbon and sulfur in the anode current collector 22A is not particularly limited, in particular, it may be preferable that the sum thereof is 100 ppm or less, because a higher effect is thereby obtained.

Although the average particle diameter of the copper crystallite is not particularly limited, in particular, it may be preferable that the average particle diameter thereof is 0.01 µm or more to 5 µm or less, because a higher effect is thereby obtained. The procedure for calculating the average particle diameter of the copper crystallites may be similar to, for example, the procedure for calculating the average particle diameter of the crystal grains described above.

It may be desirable to roughen the surface of the anode current collector 22A. This improves the adhesion of the anode active material layer 22B to the anode current collector 22A due to the so-called anchor effect. In this case, it is sufficient that the surface of the anode current collector 22A in the region opposite to the anode active material layer 22B is roughened to a minimum. Examples of the roughening method may include a method of forming fine particles by using electrolytic treatment. The electrolytic treatment is a method of providing unevenness on the surface of the anode current collector 22A by forming fine particles on the surface of the anode current collector 22A using an electrolysis method in an electrolytic cell. Copper foil produced by an electrolytic method is generally referred to as “electrolytic copper foil”.

The anode active material layer 22B includes at least one anode material capable of occluding and releasing lithium ions as the anode active material, and the anode material includes the above-described active material. However, the anode active material layer 22B may further include one or more other materials, such as an anode binder and an anode conductive agent. The details of the anode binder and the anode conducting agent may be similar to the details of the cathode binder and the cathode conducting agent, for example.

In order to prevent accidental precipitation of lithium metal on the anode 22 during charging, it may be desirable that the chargeable capacity of the anode material is greater than the discharge capacity of the cathode 21. That is, it may be desirable that the electrochemical equivalent of the anode material capable of occluding and releasing lithium ions is greater than that of the cathode 21.

Note that the anode active material layer 22B may further include other anode materials as long as it includes the above-described active material as the anode material. Examples of such other materials may include, for example, one or more carbon materials. In the carbon material, the change in crystal structure at the time of storage and release of lithium ions is extremely small. Therefore, the carbon material provides high energy density and excellent cycle characteristics. In addition, the carbon material also functions as an anode conductive agent. Examples of carbon materials may include graphitizable carbon, non-graphitizable carbon and graphite. It may be preferable that the (002) plane spacing of the non-graphitizable carbon is 0.37 nm or more, and the (002) plane spacing of graphite may be preferably 0.34 nm or less. More specifically, examples of the carbon material may include pyrolysis carbons, coke, glassy carbon fiber, organic polymer compound fired body, activated carbon and carbon black. Examples of coke may include pitch coke, needle coke and petroleum coke. The organic polymer compound fired body is obtained by firing (carbonizing) a polymer compound such as a phenol resin and a furan resin at an appropriate temperature. In addition to this, examples of the carbon material may include low crystalline carbon and amorphous carbon heat-treated at a temperature of about 1000° C. or less. Note that the shape of any carbon material can be any of fibrous, spherical, granular and scale-like shapes.

In addition, examples of other anode materials may include metal-based materials (excluding materials containing silicon as a constituent element) including one or more metal elements and semimetal elements as constituent elements, which results in higher energy density. It is because it is obtained. The metal-based material may be any of a simple substance, an alloy, and a compound, may be two or more kinds thereof, or a material having one or more phases in some or all of them. Note that "alloy" includes, in addition to a material composed of two or more types of metal elements, a material containing one or more metal elements and one or more semi-metal elements. In addition, "alloy" may include a non-metallic element. Examples of its structure may include a solid solution, a eutectic crystal (eutectic mixture), an intermetallic compound, and a structure in which two or more types thereof coexist.

Examples of the above-mentioned metal element and the above-mentioned semi-metal element may include one or more metal elements and semi-metal elements capable of forming an alloy with lithium. Specific examples thereof may include Mg, B, Al, Ga, In, Ge, Sn, Pb, Bi, Cd, Ag, Zn, Hf, Zr, Y, Pd and Pt. In particular, tin (Sn) may be preferable because tin has a high energy density due to its excellent ability to absorb and release lithium ions.

The material containing tin as a constituent element may be any of a single substance, an alloy and a compound of tin, may be two or more kinds thereof, or may be a material having one or more phases thereof in some or all of them. Note that the term “single body” only refers to a general body (which may contain small amounts of impurities), and not necessarily to a body having a purity of 100%.

The alloy of tin is a constituent element other than tin, for example, nickel (Ni), copper (Cu), iron (Fe), cobalt (Co), manganese (Mn), zinc (Zn), indium (In) , Silver (Ag), titanium (Ti), germanium (Ge), bismuth (Bi), antimony (Sb), and chromium (Cr). The compound of tin may contain one or more of carbon, oxygen, and the like as constituent elements other than tin. Note that, for example, a compound of tin may include one or more elements described for an alloy of tin as constituent elements other than tin. Specific examples of the tin alloy and the tin compound may include SnO _v (0<v≤2), SnSiO ₃ , LiSnO, and Mg ₂ Sn.

In particular, as a material containing tin as a constituent element, for example, a material including a second constituent element and a third constituent element in addition to tin as the first constituent element may be preferable. Examples of the second constituent elements are Co, Fe, Mg, Ti, V, Cr, Mn, Ni, Cu, Zn, Ga, Zr, Nb, Mo, Ag, In, Ce, Hf, Ta, W, Bi and Si It may include one or more of the elements. Examples of the third constituent element may include one or more of B, C, Al, P, and the like. When the second constituent element and the third constituent element are included, high battery capacity, excellent cycle characteristics, and the like are obtained.

In particular, a material containing tin, cobalt, and carbon (SnCoC-containing material) as a constituent element may be preferable. In the SnCoC-containing material, for example, the carbon content may be 9.9% by mass or more and 29.7% by mass or less, and the ratio of the tin and cobalt content (Co/(Sn+Co)) is 20% by mass or more and 70% by mass or less This may be because this results in a high energy density.

It may be desirable for the SnCoC-comprising material to have a phase comprising tin, cobalt and carbon. It may be desirable for the phase to be low crystalline or amorphous. The phase is a reaction phase capable of reacting with lithium. Therefore, due to the presence of the reaction phase, excellent properties are obtained. The half bandwidth of the diffraction peak obtained by X-ray diffraction on the phase is based on the diffraction angle of 2θ when CuKα rays are used as specific X-rays and the insertion rate is 1°/min. It may be desirable to be more than ˚. As a result, lithium ions are more easily occluded and released, and reactivity with the electrolyte is reduced. Note that in some cases, the SnCoC-comprising material includes a phase comprising a single or a portion of each constituent element, in addition to the low crystalline phase or the amorphous phase.

Whether the diffraction peak obtained by X-ray diffraction corresponds to a reaction phase capable of reacting with lithium can be easily judged by comparing between X-ray diffraction charts before and after the electrochemical reaction with lithium. For example, if the position of the diffraction peak after the electrochemical reaction with lithium is changed at the position of the diffraction peak before the electrochemical reaction with lithium, the obtained diffraction peak corresponds to a reaction phase capable of reacting with lithium. In this case, for example, the diffraction peak of the low-crystalline reaction phase or the amorphous reaction phase is seen in a range of 2θ=20° or more to 50° or less. The reaction phase may, for example, have each of the above-mentioned constituent elements, and its low crystalline or amorphous structure is possibly primarily due to the presence of C.

In the SnCoC-comprising material, it may be desirable that some or all of the carbon as a constituent element is bonded to a metal element or a semimetal element as another constituent element, because aggregation or crystallization of tin or the like is thereby suppressed. For example, it is possible to check the bonding state of elements using XPS or the like. In a commercially available device, for example, as soft X-rays, Al-Kα rays, Mg-Kα rays, or the like can be used. When some or all of the carbon is bonded to a metal element, a semimetal element, or the like, the peak of the synthetic wave of the 1s orbital (C1s) of carbon appears in a region lower than 284.5 eV. Note that in the device, energy calibration is made so that the peak of the 4f orbital (Au4f) of the gold (Au) atom is obtained at 84.0 eV. At this time, in general, since surface-contaminated carbon is present on the surface of the material, the peak of C1s of the surface-contaminated carbon is regarded as 284.8 eV, which is used as an energy reference. In XPS measurements, the waveform of the C1s peak is obtained in the form comprising a peak of surface contaminated carbon and a peak of carbon in the SnCoC-containing material. Thus, for example, analysis can be performed using commercially available software to separate both peaks from each other. In waveform analysis, the position of the main peak present on the lowest bound energy side is the energy reference (284.8 eV).

Note that the SnCoC-containing material is not limited to a material consisting only of tin, cobalt and carbon (SnCoC) as constituent elements. The SnCoC-containing material is a constituent element in addition to tin, cobalt, and carbon, for example, one or more of Si, Fe, Ni, Cr, In, Nb, Ge, Ti, Mo, Al, P, Ga, Bi, etc. It may further include.

In addition to the SnCoC-containing material, materials comprising tin, cobalt, iron and carbon as constituent elements (SnCoFeC-containing material) may also be preferred. The composition of the SnCoFeC-containing material can be set arbitrarily. For example, the composition in which the iron content can be set is as follows. That is, the carbon content may be 9.9 mass% or more to 29.7 mass% or less, the iron content may be 0.3 mass% or more to 5.9 mass% or less, and the content ratio of tin and cobalt (Co/(Sn+Co)) is 30 mass% % Or more to 70% by mass or less. In addition, the composition having a large iron content is as follows. That is, the carbon content may be 11.9 mass% or more and 29.7 mass% or less, and the content ratio ((Co+Fe)/(Sn+Co+Fe)) of tin, cobalt, and iron is 26.4 mass% or more and 48.5 mass% or less. The content ratio of cobalt and iron (Co/(Co+Fe)) may be 9.9% by mass or more and 79.5% by mass or less. In this composition range, a high energy density is obtained. Note that the properties of the SnCoFeC-containing material (half width, etc.) are similar to those of the SnCoC-containing material described above.

In addition to this, other anode materials may be, for example, one or more metal oxides, polymer compounds, and the like. Examples of the metal oxide may include iron oxide, ruthenium oxide and molybdenum oxide. Examples of the polymer compound may include polyacetylene, polyaniline and polypyrrole.

The anode active material layer 22B may be formed by one or more of, for example, a coating method, a vapor deposition method, a liquid deposition method, a spraying method, and a firing method (sintering method). The coating method is, for example, a method in which a particle (powder) anode active material is mixed with an anode binder or the like, and then the mixture is dispersed in a solvent such as an organic solvent, and the product is applied to the anode current collector 22A. Examples of the vapor deposition method may include a physical deposition method and a chemical deposition method. More specifically, examples thereof may include vacuum vapor deposition, sputtering, ion plating, laser ablation, thermochemical vapor deposition, chemical vapor deposition (CVD), and plasma chemical vapor deposition. Examples of the liquid deposition method may include an electrolytic plating method and an electroless plating method. The spraying method is a method of spraying the anode active material in a molten state or a semi-melt state to the anode current collector 22A. The firing method is, for example, a method of applying a mixture dispersed in a solvent to the anode current collector 22A using a coating method, and then performing heat treatment at a temperature higher than the melting point of the anode binder or the like. Examples of the firing method may include an atmosphere firing method, a reaction firing method and a hot press firing method.

In the secondary battery, as described above, in order to prevent accidental precipitation of lithium metal on the anode 22 during charging, the electrochemical equivalent of the anode material capable of occluding and releasing lithium ions is the electrochemical equivalent of the cathode. Greater than equivalent In addition, when the open circuit voltage (ie, battery voltage) when fully charged is 4.25 V or more, the emission amount of lithium ions per unit mass is greater than the emission amount when the open circuit voltage is 4.2 V even if the same cathode active material is used. . Accordingly, the amounts of the cathode active material and the anode active material are adjusted accordingly. Thereby, a high energy density can be obtained.

The maximum utilization rate in the fully charged state of the anode 22 (hereinafter simply referred to as “anode utilization rate”) is not particularly limited, and may be arbitrarily set according to a ratio between the capacity of the cathode 21 and the capacity of the anode 22. have.

"Anode utilization rate" described above is [availability (Z)(%) = (X/Y) x 100] (where X represents the amount of storage of lithium ions per unit area in the fully charged state of the anode 22, Y Denotes the amount of lithium ions that can be electrochemically stored per unit area of the anode 22).

The storage amount (X) can be obtained, for example, by the following procedure. First, the secondary battery is charged until the secondary battery is fully charged. Thereafter, the secondary battery is disassembled, and a portion of the anode 22 (inspection anode) facing the cathode 21 is cut out. Then, using the inspection anode, an evaluation battery in which metallic lithium is a counter electrode is assembled. Finally, the evaluation battery is discharged, the discharge capacity at the time of initial discharge is measured, and the discharge capacity is divided by the area of the inspection anode to calculate the storage amount (X). In this case, the term "discharge" refers to energization in the direction in which lithium ions are discharged from the test anode. For example, a constant current discharge is performed until the battery voltage reaches 1.5 V with a current density of 0.1 mA/cm ² .

On the other hand, the storage amount Y can be calculated as follows, for example. After measuring the charging capacity by performing constant current and constant voltage charging to the discharged evaluation battery until the battery voltage reaches 0 V, the charging capacity is divided by the area of the test anode to obtain the storage amount (Y). In this case, the term "charge" refers to the energization in the direction in which lithium ions are occluded in the test anode. For example, constant voltage charging is performed at a current density of 0.1 mA/cm ² and a cell voltage of 0 V until the current density reaches 0.02 mA/cm ² .

In particular, it may be desirable that the anode utilization rate is 35% or more to 80% or less, since this can obtain excellent initial charge/discharge characteristics, excellent cycle characteristics, and excellent load characteristics.

As illustrated in FIG. 6, the cathode active material layer 21B may be provided, for example, on a portion of the surface of the cathode current collector 21A (eg, a central region in the longitudinal direction). Meanwhile, the anode active material layer 22B may be provided on the entire surface of the anode current collector 22A, for example. Thereby, the anode active material layer 22B is provided in the region opposite the cathode active material layer 21B (opposing region R1) and in the region not facing the cathode active material layer 21B (non-opposing region R2). . In this case, in the anode active material layer 22B, the portion provided in the opposite region R1 is involved in charge and discharge, while the portion provided in the non-opposite region R2 is less likely to be involved in charge and discharge. Note that, in FIG. 6, the cathode active material layer 21B and the anode active material layer 22B are shaded.

As described above, in relation to the physical properties of the anode active material contained in the anode active material 22B, specific ions are detected by cation analysis using TOF-SIMS. However, when lithium ions are occluded and released from the anode active material during charge and discharge, the physical properties of the anode active material may change from the state at the time of formation of the anode active material 22B. However, in the non-opposite region R2, the physical properties of the anode active material 22B are maintained to be hardly affected by charging and discharging. Accordingly, it may be desirable to irradiate the anode active material 22B in the non-opposite region R2 in relation to the physical properties of the anode active material. One of the reasons is that, in this case, it is possible to accurately and accurately examine the physical properties of the anode active material without depending on the charge/discharge history (for example, the presence or absence of charge/discharge and the number of charge/discharge). The same applies to other variables such as the physical properties of the anode active material (average area share and average particle size of crystal grains) and composition (atomic ratios x, y and z).

[Separator]

The separator 23 separates the cathode 21 from the anode 22, and passes lithium ions while preventing a short circuit of current due to contact of both electrodes. The separator 23 may be, for example, a porous film formed of synthetic resin, ceramic, or the like. The separator 23 may be a laminated film in which two or more types of porous films are laminated. Examples of synthetic resins may include polytetrafluoroethylene, polypropylene and polyethylene.

In particular, the separator 23 may include, for example, a polymer compound layer on one side or both sides of the aforementioned porous membrane (base layer). Thereby, the adhesiveness of the separator 23 to the cathode 21 and the anode 22 is improved, and skewness and the like of the spiral wound electrode body 20 are suppressed. Thereby, the decomposition reaction of the electrolyte solution is suppressed, and the leakage of the electrolyte solution impregnated into the base layer is suppressed. Therefore, even when charging/discharging is repeated, the possibility of increasing the resistance of the secondary battery is less, and battery expansion is suppressed.

The polymer compound layer may include, for example, a polymer material such as polyvinylidene fluoride, because the polymer material has excellent physical strength and is electrochemically stable. However, the polymer material may be a polymer material other than polyvinylidene fluoride. When forming a polymer compound layer, for example, after preparing a solution in which a polymer material is dissolved, the solution is applied to a substrate layer, and then dried. Alternatively, the substrate layer can be immersed in solution and then dried.

[Electrolyte amount]

The separator 23 is impregnated with an electrolyte, which is a liquid electrolyte. The electrolyte solution includes a solvent and an electrolyte salt, and may further include one or more other materials such as additives.

The solvent includes one or more non-aqueous solvents such as organic solvents. Examples of non-aqueous solvents may include cyclic ester carbonates, chain ester carbonates, lactones, chain carboxylic acid esters, and nitriles, since this results in excellent battery capacity, excellent cycle characteristics, excellent storage characteristics, and the like. . Examples of cyclic ester carbonates may include ethylene carbonate, propylene carbonate and butylene carbonate. Examples of the chain ester carbonate may include dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate and methylpropyl carbonate. Examples of lactones may include γ-butyrolactone and γ-valerolactone. Examples of the carboxylic acid ester may include methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethyl acetate and ethyl trimethyl acetate. Examples of nitriles may include acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile and 3-methoxypropionitrile.

In addition, examples of the non-aqueous solvent include 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, N,N-dimethylformamide, N-methylpyrrolidinone, N-methyloxazolidinone, N,N'-dimethylimidazolidinone, nitromethane, Nitroethane, sulfolane, trimethyl phosphate and dimethyl sulfoxide. Thereby, similar advantages are obtained.

In particular, one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate may be preferable, because excellent battery capacity, excellent cycle characteristics, excellent storage characteristics, and the like are obtained. In this case, high viscosity (high dielectric constant) solvents such as ethylene carbonate and propylene carbonate (e.g., relative dielectric constant ε≥30), and low viscosity solvents such as dimethyl carbonate, ethylmethyl carbonate and diethyl carbonate (e.g. , Viscosity ≤ 1 mPa·s) may be more preferable. One of the reasons is that the dissociation properties and ionic mobility of the electrolyte salt are improved.

In particular, the solvent may include one or more of unsaturated cyclic ester carbonate, halogenated ester carbonate, sultone (cyclic sulfonic acid ester) and acid anhydride, because this improves the chemical stability of the electrolyte. The unsaturated cyclic ester carbonate is a cyclic ester carbonate having at least one unsaturated bond (carbon-carbon double bond), and may be, for example, vinylene carbonate, vinylethylene carbonate, methyleneethylene carbonate, and the like. Halogenated ester carbonates are cyclic ester carbonates or chain ester carbonates containing one or more halogens as constituent elements. Examples of cyclic halogenated ester carbonates may include 4-fluoro-1,3-dioxol-2-one and 4,5-difluoro-1,3-dioxol-2-one. Examples of halogenated ester carbonates may include fluoromethyl methyl carbonate, bis(fluoromethyl) carbonate and difluoromethyl methyl carbonate. Examples of the sultone may include propane sultone and propene sultone. Examples of the acid anhydride may include succinic anhydride, ethane disulfonic anhydride and sulfobenzoic anhydride. However, examples of the solvent are not limited to the above-described materials, and may include other materials.

The electrolyte salt may include one or more salts, for example lithium salts. However, the electrolyte salt may include, for example, salts other than lithium salts. Examples of “salts other than lithium salts” may include light metal salts other than lithium salts.

Examples of lithium salts are LiPF ₆ (lithium hexafluorophosphate), LiBF ₄ (lithium tetrafluoroborate), LiClO ₄ (lithium perchlorate), LiAsF ₆ (lithium hexafluoroarsenate), LiB(C ₆ H ₅ ) ₄ (lithium tetraphenylborate), LiCH ₃ SO ₃ ( lithium methanesulfonate), LiCF ₃ SO ₃ (lithium trifluoromethane sulfonate), LiAlCl ₄ (lithium tetrachloroaluminate), Li ₂ SiF ₆ (dilithium hexafluorosilicate), LiCl (lithium chloride) and LiBr (lithium bromide). Thereby, excellent battery capacity, excellent cycle characteristics, excellent storage characteristics, and the like are obtained.

In particular, one or more of LiPF ₆ , LiBF ₄ , LiClO ₄ and LiAsF ₆ may be preferred, and LiPF ₆ may be more preferable, because the internal resistance is lowered to obtain a higher effect. However, examples of the electrolyte salt are not limited to the materials described above, and may include other materials.

Although the content of the electrolyte salt is not particularly limited, in particular, it may be preferable that the content is 0.3 mol/kg or more and 3.0 mol/kg or less with respect to the solvent, because high ion conductivity is thereby obtained.

[Operation of secondary battery]

The secondary battery can operate as follows, for example. During charging, lithium ions released from the cathode 21 are stored in the anode 22 through the electrolyte. Meanwhile, during discharge, lithium ions emitted from the anode 22 are stored in the cathode 21 through the electrolyte.

In the secondary battery, as described above, it may be desirable to pre-dope lithium ions on the anode active material of the anode 22 in a non-charged state. One of the reasons is that, in this case, the irreversible capacity at the time of initial charge and initial discharge is reduced, thereby improving initial charge and discharge characteristics, cycle characteristics, and the like. As to the presence or absence of pre-doping, it may be desirable to irradiate the anode active material 22B of the non-opposite region R2, as described with reference to FIG.

[Method of manufacturing secondary battery]

The secondary battery can be produced, for example, by the following procedure.

First, the cathode 21 is manufactured. A cathode mixture is prepared by mixing a cathode binder and a cathode conductive material with the cathode active material. Subsequently, the cathode mixture is dispersed in an organic solvent or the like to obtain a paste cathode mixture slurry. Subsequently, both surfaces of the cathode current collector 21A are coated with the cathode mixture slurry, and dried to form the cathode active material layer 21B. Subsequently, the cathode active material layer 21B may be compression molded using a roll pressing machine or the like. In this case, compression molding may be performed while heating the cathode active material layer 21B, or compression molding may be repeated several times.

When manufacturing the anode 22, for example, the anode active material layer 22B is formed on the anode current collector 22A by a procedure similar to that of the cathode 21 described above. Specifically, an anode active material including the above-described active material is mixed with an anode binder, an anode conductive agent, and the like to prepare an anode mixture, and then, it is dispersed in an organic solvent or the like to form a paste anode mixture slurry. Subsequently, both surfaces of the anode current collector 22A are applied as an anode mixture slurry, and dried to form an anode active material layer 22B. Thereafter, the anode active material layer 22B is compression molded.

Finally, the secondary battery is assembled using the cathode 21 and the anode 22. The cathode lead 24 is attached to the cathode current collector 21A using a welding method or the like, and the anode lead 25 is attached to the anode current collector 22A using a welding method or the like. Subsequently, the cathode 21 and the anode 22 are stacked with the separator 23 interposed therebetween, and spirally wound in the longitudinal direction to form the battery element 20. Subsequently, the battery element 20 is housed in the battery can 11, and then the insulating plate 12 is placed on the battery element 20. Subsequently, the cathode lead 24 is attached to the cathode pin 15 using a welding method or the like, and the anode lead 25 is attached to the battery can 11 using a welding method or the like. In this case, the battery cover 13 is fixed to the open end of the battery can 11 by laser welding or the like. Finally, an electrolyte is injected into the battery can 11 from the injection hole 19 to impregnate the separator 23 with the electrolyte, and then the injection hole 19 is sealed with a sealing member 19A.

[Action and Effect of Secondary Battery]

In the prismatic secondary battery, the anode active material layer 22B of the anode 22 includes the above-described active material as the anode active material. Therefore, the electrical resistance of the anode active material is lowered, the decomposition reaction of the electrolyte solution, etc. are suppressed, and excellent battery characteristics can be obtained. Other effects are similar to those of the active material.

[2-2. Cylindrical]

7 and 8 illustrate a cross-sectional configuration of a cylindrical secondary battery. FIG. 8 illustrates an enlarged part of the spiral wound electrode body 40 illustrated in FIG. 7. In the following description, the components of the above-described prismatic secondary battery will be used as appropriate.

[Overall configuration of secondary battery]

The secondary battery described herein is a so-called cylindrical lithium ion secondary battery. For example, the secondary battery may include a pair of insulating plates 32 and 33 and a spiral wound electrode body 40 inside the hollow cylindrical battery can 31. The spiral wound electrode body 40 can be formed by, for example, laminating the cathodes 41 and anodes 42 with the separators 43 interposed therebetween, and then spirally winding the obtained laminates. .

The battery can 31 may have, for example, a hollow structure in which one end of the battery can 31 is closed and the other end of the battery can 31 is opened. The battery can 31 may be formed of, for example, iron, aluminum, or an alloy thereof. The surface of the battery can 31 may be plated with nickel or the like. The pair of insulating plates 32 and 33 are disposed so as to extend perpendicular to the helically wound peripheral surface of the spiral wound electrode body 40 with the spiral wound electrode body 40 interposed therebetween.

At the open end of the battery can 31, a battery cover 34, a safety valve mechanism 35 and a positive temperature coefficient device (PTC element) 36 are swaged with a gasket 37 Attach. Thereby, the battery can 31 is sealed. The battery cover 34 may be formed of, for example, a material similar to the battery can 31 material. The safety valve mechanism 35 and the PTC element 36 are provided inside the battery cover 34. The safety valve mechanism 35 is electrically connected to the battery cover 34 through the PTC element 36. In the safety valve mechanism 35, when the internal pressure exceeds a certain level due to internal short circuit, external heating, or the like, the disk plate 35A is inverted to electrically connect the battery cover 34 and the spiral wound electrode body 40. Hang up. The PTC element 36 prevents abnormal heat generation due to large current. As the temperature rises, the resistance of the PTC element 36 also increases accordingly. The gasket 37 may be formed of an insulating material, for example. The surface of the gasket 37 can be applied with asphalt.

The center pin 44 may be inserted into the hollow space in the center of the spiral wound electrode body 40. However, the center pin 44 need not necessarily be included therein. For example, a cathode lead 45 formed of a conductive material such as aluminum can be connected to the cathode 41. For example, an anode lead 46 formed of a conductive material such as nickel can be connected to the anode 42. For example, the cathode lead 45 can be welded to the safety valve mechanism 35 and can be electrically connected to the battery cover 34. For example, the anode lead 46 can be welded to the battery can 31 and can be electrically connected to the battery can 31.

The cathode 41 may have the cathode active material layer 41B on one side or both sides of the cathode current collector 41A, for example. The anode 42 may have, for example, an anode active material layer 42B on one side or both sides of the anode current collector 42A. The configurations of the cathode current collector 41A, the cathode active material layer 41B, the anode current collector 42A, and the anode active material layer 42B are respectively the cathode current collector 21A, the cathode active material layer 21B, and the anode current collector 22A. ) And the anode active material layer 22B. That is, the anode active material layer 42B of the anode 42, which is an electrode, includes the above-described active material as the anode active material. The configuration of the separator 43 is similar to that of the separator 23. The composition of the electrolyte impregnated in the separator 43 is similar to that of the prismatic secondary battery.

[Operation of secondary battery]

The cylindrical secondary battery can operate, for example, as follows. During charging, lithium ions released from the cathode 41 are stored in the anode 42 through the electrolyte. Meanwhile, during discharge, lithium ions emitted from the anode 42 are stored in the cathode 41 through the electrolyte.

[Method of manufacturing secondary battery]

The cylindrical secondary battery can be produced, for example, by the following procedure. First, for example, the cathode 41 and the anode 42 are manufactured by a manufacturing procedure similar to that of the cathode 21 and the anode 22. That is, the cathode active material layer 41B is formed on both surfaces of the cathode current collector 41A to form the cathode 41, and the anode active material layer 42B is formed on both surfaces of the anode current collector 42A to form the anode ( 42). Next, the cathode lead 45 is attached to the cathode 41 using a welding method or the like, and similarly, the anode lead 46 is attached to the anode 42 using a welding method or the like. Subsequently, the cathode 41 and the anode 42 are stacked with the separator 43 interposed therebetween, and wound spirally to prepare a spiral wound electrode body 40. Thereafter, the center pin 44 is inserted into the hollow space in the center of the spiral wound electrode body 40. Subsequently, the spiral wound electrode body 40 is interposed between the pair of insulating plates 32 and 33, and is accommodated in the battery can 31. In this example, the cathode lead 45 is attached to the safety valve mechanism 35 using a welding method or the like, and the tip end of the anode lead 46 is attached to the battery can 31 using a welding method or the like. Next, an electrolyte is injected into the battery can 31, and the separator 43 is impregnated with the electrolyte. Finally, the battery cover 34, the safety valve mechanism 35 and the PTC element 36 are attached to the open end of the battery can 31, and compressed by a gasket 37 to fix it.

[Action and Effect of Secondary Battery]

In the cylindrical secondary battery, the anode active material layer 42B of the anode 42 includes the above-described active material as the anode active material. Therefore, excellent battery characteristics can be obtained for a similar reason to the prismatic secondary battery. Other actions and other effects are similar to those of the prismatic secondary battery.

[2-3. Laminate film type]

9 illustrates an exploded perspective configuration of a laminate film type secondary battery. 10 illustrates an enlarged cross-section taken along the X-X line of the spiral wound electrode body 50 illustrated in FIG. 9. 9 illustrates a state in which the spiral wound electrode body 50 is separated from the two exterior members 60. In the following description, the components of the cylindrical secondary battery described above will be used as needed.

[Overall configuration of secondary battery]

The secondary battery described herein may be, for example, a so-called laminate film type lithium ion secondary battery. For example, in the secondary battery, the spiral wound electrode body 50 may be accommodated in the film-shaped exterior member 60. The spiral wound electrode body 50 stacks the cathode 53 and the anode 54, for example, with the separator 55 and the electrolyte layer 56 interposed therebetween, and then the obtained laminate is spirally wound. It can be formed by winding. The cathode lead 51 is attached to the cathode 53, and the anode lead 52 is attached to the anode 54. The outermost circumference of the spiral wound electrode body 50 is protected by a protective tape 57.

The cathode lead 51 and the anode lead 52 may be drawn out from the inside of the exterior member 60 in the same direction, for example. The cathode lead 51 may be formed of one or more conductive materials, for example, aluminum. The anode lead 52 may be formed of one or more conductive materials, such as copper, nickel, and stainless steel, for example. The conductive material may be, for example, a thin plate or a mesh.

The exterior member 60 may be, for example, a laminate film in which a welding layer, a metal layer, and a surface protective layer are laminated in this order. The exterior member 60 may be formed by, for example, laminating two laminate films such that the fusion layer and the spiral wound electrode body 50 face each other, and then fusion each outer peripheral portion of the fusion layer to each other. Alternatively, two laminate films can be attached to each other by an adhesive or the like. Examples of the fusion layer may include a film formed of polyethylene, polypropylene, or the like. Examples of the metal layer may include aluminum foil. Examples of the surface protective layer may include a film formed of nylon, polyethylene terephthalate, or the like.

In particular, as the exterior member 60, an aluminum laminate film in which a polyethylene film, an aluminum foil and a nylon film are laminated in this order may be preferable. However, the exterior member 60 may be formed of a laminate film having a different laminated structure, a polymer film such as polypropylene, or a metal film.

An adhesive film 61 is inserted between the exterior member 60 and the cathode lead 51 and between the exterior member 60 and the anode lead 52 to protect it from outside air intrusion. The adhesion film 61 is formed of a material having adhesion to the cathode lead 51 and the anode lead 52. Examples of the adhesive material may include polyolefin resin. More specific examples may include polyethylene, polypropylene, modified polyethylene and modified polypropylene.

The cathode 53 may have, for example, a cathode active material layer 53B on one side or both sides of the cathode current collector 53A. The anode 54 may have, for example, an anode active material layer 54B on one or both sides of the anode current collector 54A. The configurations of the cathode current collector 53A, the cathode active material layer 53B, the anode current collector 54A, and the anode active material layer 54B are respectively the cathode current collector 21A, the cathode active material layer 21B, and the anode current collector 22A. ) And the anode active material layer 22B. That is, the anode active material layer 54B of the anode 54, which is an electrode, includes the above-described active material as the anode active material. The configuration of the separator 55 is similar to that of the separator 23.

In the electrolyte layer 56, the electrolyte solution is supported by a polymer compound. The electrolyte layer 56 is a so-called gel electrolyte, since a high ionic conductivity (for example, 1 mS/cm or more at room temperature) is obtained and leakage of the electrolyte is prevented. The electrolyte layer 56 may further include other materials, such as additives.

The polymer compound includes one or more polymer materials. Examples of the polymer material include polyacrylonitrile, polyvinylidene fluoride, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, polyphosphazene, polysiloxane, polyvinyl fluoride, polyvinyl acetate, Polyvinyl alcohol, polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, styrene-butadiene polymer, nitrile-butadiene rubber, polystyrene and polycarbonate. In addition to this, examples of the polymer material may include a copolymer. Examples of copolymers may include copolymers of vinylidene fluoride and hexafluoro propylene. In particular, polyvinylidene fluoride or a copolymer of vinylidene fluoride and hexafluoro propylene may be preferred, and polyvinylidene fluoride may be more preferred, because the polymer compound is electrochemically stable. to be.

For example, the composition of the electrolyte solution may be similar to that of the prismatic secondary battery. However, in the electrolyte layer 56, which is a gel electrolyte, the term "solvent" of the electrolyte refers to a broad concept including liquid solvents, as well as materials having ionic conductivity that can dissociate electrolyte salts. Therefore, when a polymer compound having ionic conductivity is used, the polymer compound may also be included in the solvent.

Note that instead of the gel electrolyte layer 56, an electrolyte can be used as it is. In this case, the electrolyte solution is impregnated into the separator 55.

[Operation of secondary battery]

The secondary battery can operate as follows, for example. Upon charging, lithium ions released from the cathode 53 are stored in the anode 54 through the electrolyte layer 56. On the other hand, during discharge, lithium ions released from the anode 54 are stored in the cathode 53 through the electrolyte layer 56.

[Method of manufacturing secondary battery]

The secondary battery comprising the gel electrolyte layer 56 can be produced, for example, by the following three procedures.

In the first procedure, the cathode 53 and the anode 54 are manufactured by a manufacturing procedure similar to that of the cathode 21 and anode 22. That is, the cathode active material layer 53B is formed on both surfaces of the cathode current collector 53A to form the cathode 53, and the anode active material layer 54B is formed on both surfaces of the anode current collector 54A to form the anode ( 54). Subsequently, a precursor solution containing a solvent such as an electrolyte solution, a polymer compound, and an organic solvent is prepared. Thereafter, a precursor solution is applied to the cathode 53 and the anode 54 to form a gel electrolyte layer 56. Next, the cathode lead 51 is attached to the cathode current collector 53A using a welding method or the like, and the anode lead 52 is attached to the anode current collector 54A using a welding method or the like. Subsequently, the cathode 53 and the anode 54 are stacked with the separator 55 interposed therebetween, and wound spirally to prepare a spiral wound electrode body 50. Thereafter, a protective tape 57 is adhered to its outermost circumference. Subsequently, after the spiral wound electrode body 50 is interposed between the two film-shaped exterior members 60, the outer peripheral portion of the exterior member 60 is bonded using a heat fusion method or the like. Thereby, the spiral wound electrode body 50 is sealed inside the exterior member 60. In this case, the adhesion film 61 is inserted between the cathode lead 51 and the exterior member 60 and between the anode lead 52 and the exterior member 60.

In the second procedure, the cathode lead 51 is attached to the cathode 53, and the anode lead 52 is attached to the anode 54. Subsequently, the cathode 53 and the anode 54 are stacked with the separator 55 interposed therebetween, and wound spirally to prepare a spiral wound body as a precursor of the spiral wound electrode body 50. Thereafter, a protective tape 57 is adhered to its outermost circumference. Subsequently, after the spiral winding body is disposed between the two film-shaped exterior members 60, the outermost circumference except one side is adhered to each other using a heat fusion method or the like to obtain a pouch state, and the pouch-shaped exterior member 60 The spiral wound body is accommodated in the inside. Subsequently, an electrolyte composition is prepared by mixing other materials such as a monomer, a polymerization initiator, and a polymerization inhibitor as raw materials for the electrolyte solution and the polymer compound. Subsequently, the electrolyte composition is injected into the pouch-shaped exterior member 60. Thereafter, the exterior member 60 is sealed using a thermal fusion method or the like. Subsequently, the monomer is thermally polymerized to form a polymer compound. Accordingly, the polymer compound is impregnated with an electrolyte, and the polymer compound is gelled to form the electrolyte layer 56.

In the third procedure, a spiral wound body is manufactured and housed in a pouch-shaped exterior member 60 in a manner similar to the second procedure described above, except that the separator 55 coated on both sides of the polymer compound is used. Examples of the polymer compound applied to the separator 55 may include a polymer (homopolymer, copolymer or polypolymer) containing vinylidene fluoride as a component. Specific examples of homopolymers may include polyvinylidene fluoride. Specific examples of the copolymer may include binary copolymers including vinylidene fluoride and hexafluoro propylene as constituent components. Specific examples of the multi-membered copolymer may include a terpolymer based on vinylidene fluoride, hexafluoro propylene and chlorotrifluoroethylene as components. Note that, in addition to the polymer containing vinylidene fluoride as a component, one or more other polymer compounds may be used. Next, an electrolyte solution is prepared and injected into the exterior member 60. Thereafter, the opening of the exterior member 60 is sealed using a thermal fusion method or the like. Subsequently, the resultant is heated while applying a load to the exterior member 60, and the separator 55 is brought into close contact with the cathode 53 and the anode 54 by interposing a polymer compound therebetween. Thereby, the electrolyte is impregnated with the polymer compound, and accordingly, the polymer compound is gelled to form the electrolyte layer 56.

In the third procedure, expansion of the secondary battery is suppressed more than in the first procedure. Further, in the third procedure, the possibility that monomers, solvents, and the like as raw materials for the polymer compound remain in the electrolyte layer 56 is less than in the second procedure. Therefore, the step of forming the polymer compound is preferably controlled. Therefore, the cathode 53, the anode 54 and the separator 55 are sufficiently adhered to the electrolyte layer 56.

[Action and Effect of Secondary Battery]

In the laminated film type secondary battery, the anode active material layer 54B of the anode 54 includes the above-described active material as the anode active material. Therefore, excellent battery characteristics can be obtained for similar reasons as in the prismatic secondary battery. Other actions and other effects are similar to those of the prismatic secondary battery.

[3. Use of secondary battery]

Next, an application example of the above-described secondary battery will be described.

The use of the secondary battery is not particularly limited as long as the secondary battery is applied to a machine, device, apparatus, apparatus, system (aggregate of multiple devices, etc.) that can use the secondary battery as a driving power source or a power storage source for power storage. Does not. The secondary battery used as a power source may be a main power source (preferably used power source) or an auxiliary power source (a power source used instead of the main power source or switched from the main power source). When a secondary battery is used as an auxiliary power source, the type of main power source is not limited to the secondary battery.

Examples of the use of the secondary battery may include electronic devices (including portable electronic devices) such as video camcorders, digital still cameras, cell phones, notebook PCs, cordless phones, headphone stereos, portable radios, portable TVs, and PDAs. Additional examples thereof include portable appliances such as electric shavers; Memory devices such as backup power and memory cards; Power tools such as power drills and power saws; Battery pack used in a notebook PC as a removable power supply; Medical electronic devices such as pacemakers and hearing aids; Electric vehicles such as electric vehicles (including hybrid vehicles); And a power storage system such as a household battery system for storing power in an emergency or the like. Needless to say, other than the above-mentioned uses may also be employed.

In particular, the secondary battery can be effectively applied to a battery pack, an electric vehicle, a power storage system, a power tool, an electronic device, and the like. One of the reasons is that in these applications, excellent battery characteristics are required, and performance is effectively improved by using the secondary battery according to the embodiment of the present invention. Note that the battery pack is a power source using a secondary battery and is a so-called assembled battery. An electric vehicle is a vehicle operated (driving) using a secondary battery as a driving power source. As described above, the electric vehicle may be a vehicle (for example, a hybrid vehicle) including a driving source other than a secondary battery. The power storage system is a system using a secondary battery as a power storage source. For example, in a home electric power storage system, since electric power is stored in a secondary battery as a power storage source, household electric appliances and the like can be used by using the electric power. The power tool is a tool in which a movable part (for example, a drill) is operated using a secondary battery as a driving power source. An electronic device is a device that performs various functions using a secondary battery as a driving power source (power source).

Some application examples of the secondary battery will be described in detail. Note that the configuration of each application example described below is merely an example and can be changed as appropriate.

[3-1. Battery pack]

11 illustrates a block configuration of a battery pack. For example, the battery pack is a housing 60 formed of a plastic material, a control unit 61, a power supply 62, a switch unit 63, a current measurement unit 64, a temperature detection unit 65, a voltage detection unit (66), a switch control unit 67, a memory 68, a temperature detection element 69, a current detection resistor 70, may include a cathode terminal 71 and an anode terminal 72.

The control unit 61 controls the operation of the entire battery pack (including the operation of the power source 62), and may include, for example, a central processing unit (CPU). The power source 62 includes one or more secondary batteries (not shown). The power source 62 may be, for example, an assembled battery including two or more secondary batteries. The type of connection of these secondary batteries may be a series type, a parallel type, or a mixed type. As an example, the power supply 62 may include six secondary batteries connected in a two-parallel and three-series manner.

The switch unit 63 switches the operation of the power source 62 (whether the power source 62 is connectable to an external device) according to the instructions of the control unit 61. The switch unit 63 may include, for example, a charge control switch, a discharge control switch, a charge diode, a discharge diode, and the like (not shown). Each of the charge control switch and the discharge control switch may be a semiconductor switch, such as a field effect transistor (MOSFET) using a metal oxide semiconductor.

The current measurement unit 64 measures the current using the current detection resistor 70, and outputs the measurement result to the control unit 61. The temperature detection unit 65 measures the temperature using the temperature detection element 69 and outputs the measurement result to the control unit 61. The temperature measurement result can be used, for example, when the control unit 61 controls charging and discharging during abnormal heat generation or when the control unit 61 performs a correction process when calculating the residual capacity. The voltage detector 66 measures the voltage of the secondary battery at the power source 62, performs analog-to-digital conversion on the measured voltage, and supplies the result to the controller 61.

The switch control unit 67 controls the operation of the switch unit 63 according to signals input from the current measurement unit 64 and the voltage detection unit 66.

The switch control unit 67 disconnects the switch unit 63 (charge control switch) when the battery voltage reaches the overcharge detection voltage, for example, so that the charging current flows in the current path of the power source 62 Control to prevent it. Thus, in the power source 62, only discharge can be performed through the discharge diode. Note that, for example, when a large current flows during charging, the switch control unit 67 blocks the charging current.

In addition, the switch control unit 67, for example, by disconnecting the switch unit 63 (discharge control switch) when the battery voltage reaches the over-discharge detection voltage, discharge current in the current path of the power source 62 Control is executed to prevent the flow. In this way, only the charging can be performed at the power source 62 through the charging diode. Note that, for example, when a large current flows during discharge, the switch control unit 67 blocks the discharge current.

Note that in the secondary battery, for example, the overcharge detection voltage may be 4.20 V±0.05 V, and the overdischarge detection voltage may be 2.4 V±0.1 V.

The memory 68 may be, for example, EEPROM, which is a nonvolatile memory. In the memory 68, for example, numerical values calculated by the control unit 61 and information of the secondary battery measured in the manufacturing step (eg, internal resistance in an initial state) may be stored. Note that when the full charge capacity of the secondary battery is stored in the memory 68, the control unit 61 can grasp information such as the residual capacity.

The temperature detection element 69 measures the temperature of the power supply 62 and outputs the measurement result to the control unit 61. The temperature detection element 69 may be, for example, a thermistor or the like.

The cathode terminal 71 and the anode terminal 72 are connected to an external device (for example, a notebook PC) driven by using the battery pack or an external device (for example, a battery charger) used to charge the battery pack. Terminal. The power source 62 is charged and discharged through the cathode terminal 71 and the anode terminal 72.

[3-2. Electric vehicle]

12 illustrates a block configuration of a hybrid vehicle as an example of an electric vehicle. For example, the electric vehicle, inside the housing 73 formed of a metal, the control unit 74, the engine 75, the power supply 76, the driving motor 77, the differential device 78, the generator 79, It may include a transmission 80, a clutch 81, intervers 82 and 83, and various sensors 84. In addition to this, the electric vehicle may include, for example, a front wheel drive shaft 85 and a front wheel 86, a rear wheel drive shaft 87, and a rear wheel 88 connected to the differential device 78 and the transmission 80. Can.

The electric vehicle can travel using, for example, one of the engine 75 and the motor 77 as a driving source. The engine 75 is the main power source and can be, for example, a petrol engine. When the engine 75 is used as a power source, the driving force (rotating power) of the engine 75 is, for example, the front wheel 86 through the differential device 78, the transmission 80 and the clutch 81, which are the driving parts, and It can be transmitted to the rear wheel 88. The rotational force of the engine 75 can also be transmitted to the generator 79. Due to the rotational force, the generator 79 generates AC power. The AC power is converted to DC power through the inverter 83, and the converted power is stored in the power supply 76. On the other hand, when the motor 77 that is the conversion unit is used as a power source, power (DC power) supplied from the power source 76 is converted into AC power through the inverter 82. The motor 77 can be driven by AC power. The driving force (rotating power) obtained by converting electric power by the motor 77 is, for example, the front wheel 86 or the rear wheel 88 via the differential device 78, the transmission 80 and the clutch 81, which are the driving parts. Can be passed on.

Note that alternatively, subsequent mechanisms can be employed. In the mechanism, when the electric vehicle is decelerated by a brake mechanism (not shown), the resistance at the time of deceleration is transmitted to the motor 77 as a rotational force, and the motor 77 generates AC power by the rotational force. The AC power may be converted to DC power through the inverter 82, and the DC regenerative power may be preferably stored in the power supply 76.

The control unit 74 controls the operation of the entire electric vehicle, and may include, for example, a CPU. The power source 76 includes one or more secondary batteries (not shown). Alternatively, the power supply 76 may be connected to an external power supply, and power may be stored by receiving power from the external power supply. For example, various sensors 84 may be used to control the number of revolutions of the engine 75 or the opening level (throttle opening) of a throttle valve (not shown). The various sensors 84 may include, for example, a speed sensor, an acceleration sensor, an engine speed sensor, and the like.

Note that the hybrid vehicle has been described above as an electric vehicle. However, the example of the electric vehicle may include a vehicle (electric vehicle) that operates using only the power source 76 and the motor 77 without using the engine 75.

[3-3. Power storage system]

13 illustrates a block configuration of a power storage system. For example, the power storage system may include a control unit 90, a power supply 91, a smart meter 92, and a power hub 93 inside a house 89 such as a general house and commercial building. Can.

In this case, the power source 91 can be connected to, for example, an electric device 94 installed inside the house 89 and to an electric vehicle 96 parked outside the house 89. have. In addition, for example, the power source 91 may be connected to the self-generator 95 installed inside the house 89 through the power hub 93, and external through the smart meter 92 and the power hub 93. It can be connected to the centralized power system (97).

Note that the electrical device 94 may include one or more household appliances, for example, refrigerators, air conditioners, televisions, and hot water heaters. The self-generator 95 may be, for example, one or more of a solar power generator and a wind power generator. The electric vehicle 96 may be, for example, one or more of an electric vehicle, an electric motorcycle, and a hybrid vehicle. The centralized power system 97 may be, for example, one or more of thermal power plants, nuclear power plants, hydro power plants, wind power plants, and the like.

The control unit 90 controls the operation of the entire power storage system (including the operation of the power source 91), and may include, for example, a CPU. The power supply 91 includes one or more secondary batteries (not shown). The smart meter 92 may be, for example, a network-compatible power meter installed in a house 89 that requires power, and may be capable of communicating with a power supply side. Accordingly, for example, while the smart meter 92 communicates with the outside, the smart meter 92 controls the balance between supply and demand in the house 89 to enable efficient and stable energy supply.

In the power storage system, for example, power can be stored in the power source 91 from the centralized power system 97, which is an external power source, through the smart meter 92 and the power hub 93. Electric power may be stored in the power source 91 from the power hub 93 through the power hub 93. Power stored in the power supply 91 is supplied to the electric device 94 or the electric vehicle 96 according to the instructions of the control unit 90. Thus, the electric device 94 becomes operable, and the electric vehicle 96 becomes chargeable. That is, the power storage system is a system that can store and supply power to the house 89 using the power source 91.

The power stored in the power supply 91 can be used arbitrarily. Thus, for example, it is possible to store electric power from the centralized power system 97 to the power source 91 in the middle of the night when electricity is inexpensive, and to use the electric power stored in the power source 91 during the daytime when the electricity fee is expensive. It is possible.

Note that the above-described power storage system may be installed for each household (one household) or may be installed for a plurality of households (multiple households).

[3-4. Power tools]

14 illustrates a block configuration of a power tool. For example, the power tool may be an electric drill, and may include a control unit 99 and a power supply 100 in a tool body 98 formed of plastic material or the like. For example, the tool body 98 may be attached to a drill portion 101 that is a movable part in an activatable (rotating) manner.

The control unit 99 controls the operation (including the operation of the power supply 100) of the entire power tool, and may include, for example, a CPU. The power supply 100 includes one or more secondary batteries (not shown). The control unit 99 enables electric power to be supplied from the power source 100 to the drill unit 101 according to an operation of an operation switch (not shown) that operates the drill unit 101.

[Example]

It will be described in detail a specific embodiment according to an embodiment of the present invention.

[Examples 1-1 to 1-8]

The laminate film type lithium ion secondary battery illustrated in FIGS. 9 and 10 was prepared by the following procedure.

When preparing the cathode 53, first, the cathode active material (LiCoO ₂ ) 91 parts by mass, the cathode conductive agent (graphite) 6 parts by mass, and the cathode binder (polyvinylidene fluoride: PVDF) 3 parts by mass of the cathode mixture Was obtained. Then, the cathode mixture was dispersed in an organic solvent (N-methyl-2-pyrrolidone:NMP) to obtain a paste cathode mixture slurry. Subsequently, a cathode mixture slurry was uniformly applied to both surfaces of the cathode current collector 53A (12 μm-thick stripe-shaped aluminum foil) using a coating device, and the applied cathode mixture slurry was dried to obtain the cathode active material layer 53B. Formed. Finally, the cathode active material layer 53B was compression molded using a roll press machine. In this embodiment, the thickness of the cathode active material layer 53B was adjusted so that lithium metal did not precipitate on the anode 54 during full charge.

When preparing the anode 54, first, an anode active material including a central portion and a coating portion was obtained by the following procedure.

In the case of forming the center, a film formed of an active material (silicon oxide) was formed using a resistive heating evaporation source and an induction heating evaporation source inside a vacuum deposition apparatus using a turbopump. In these examples, the pressure was 1x10 ^-3 Pa and the deposition rate was 100 nm/sec. Thereafter, the formed film was crushed, and then the particle diameter was selected to obtain a central portion containing silicon oxide (SiO _w ).

When forming the coating, a conductive material was deposited on the surface of the central portion using a thermal decomposition CVD method. In the pyrolysis CVD method, methane and acetylene were used as carbon source gases, and argon and hydrogen were used as auxiliary gases. In these examples, conditions such as the mixing ratio between methane gas and acetylene gas, heating temperature, and the type of auxiliary gas were adjusted to control the physical properties of the coating (kind of cations). Note that as a method of forming the coating, a pyrolysis CVD method is used when CH ₂ or the like is detected with C as another ion, while a sputtering method is used when only C is detected as another ion.

Subsequently, after mixing the anode active material and the precursor of the anode binder in a dry weight ratio of 90:10, the obtained mixture was diluted with NMP to obtain a paste anode mixture slurry. The precursor of the anode binder was a polyamic acid comprising NMP and N,N-dimethylacetoamide (DMAC). Subsequently, an anode mixture slurry was applied to both surfaces of the anode current collector 54A (rolled copper foil having a thickness of 15 µm) using a coating apparatus, and the applied anode mixture slurry was dried. Finally, in order to improve the binding properties, the applied film was heat pressed (thermally pressed), and then the applied film was calcined in a vacuum atmosphere (400° C. for 1 hour). Thus, an anode binder (polyimide:PI) was formed, and thus, an anode active material layer 54B including an anode active material and an anode binder was formed. Note that the thickness of the anode active material layer 54B was adjusted so that the anode utilization rate was 65%.

Cation analysis was performed on the anode active material (coat) by TOF-SIMS. Accordingly, a plurality of peaks (plural cations) were detected in the analysis results (TOF-SIMS spectrum). Table 1 shows the types of cations, ratios D1/D2 and ratios D1/D3.

When preparing the electrolytic solution, the electrolyte salt (LiPF ₆ ) was dissolved in a solvent (ethylene carbonate and diethyl carbonate). In these examples, the composition of the solvent was ethylene carbonate:diethyl carbonate=50:50 by weight, and the electrolyte salt content was 1 mol/kg with respect to the solvent.

When assembling the secondary battery, first, the cathode lead 51 formed of aluminum was welded to one end of the cathode current collector 53A, and the anode lead 52 formed of nickel was welded to one end of the anode current collector 54A. Did. Subsequently, the cathode 53, the separator 55, the anode 54, and the separator 55 are stacked in this order, and the obtained laminate is spirally wound in the longitudinal direction to be a precursor of the spiral wound electrode body 50. As, a spiral wound body was formed. Thereafter, the spiral wound end was fixed with a protective tape 57 (adhesive tape). The separator 55 was a multi-layer film (20 μm thick) in which a film containing porous polyethylene as a main component was interposed between films containing porous polypropylene as a main component. Subsequently, a spiral wound body was interposed between the exterior members 60, and then the outer peripheral portion excluding one side of the exterior member 60 was heat-sealed to accommodate the spiral winding body inside the exterior member 60. The exterior member 60 was an aluminum laminate film in which a nylon film (30 μm thick), an aluminum foil (40 μm thick), and an unstretched polypropylene film (30 μm thick) were laminated from the outside. Subsequently, an electrolyte solution was injected from the opening of the exterior member 60, and the electrolyte solution was impregnated into the separator 55 to prepare a spiral wound electrode body 50. Finally, the opening of the exterior member 60 was heat-sealed in a vacuum atmosphere.

The initial charge and discharge characteristics and cycle characteristics of the secondary battery were investigated. The results illustrated in Table 1 were obtained.

When examining the initial charge/discharge characteristics, in order to stabilize the battery state, charge/discharge of a cycle was performed for the secondary battery in a room temperature atmosphere (23° C.). Subsequently, the secondary battery was charged again in the same atmosphere to measure the charge capacity, and then the secondary battery was discharged to measure the discharge capacity. From the measurement results, [initial efficiency (%) = (discharge capacity/charge capacity) x 100] was calculated. Upon charging in the first cycle, charging was performed until the voltage reached 4.25 V with a current density of 0.7 mA/cm ² , and further, with a constant voltage of 4.2 V, the current density would reach 0.3 mA/cm ² Charging was carried out until. Upon discharge in the first cycle, discharge was performed with a constant current density of 0.7 mA/cm ² until the voltage reached 2.5 V. The charging and discharging conditions in the second cycle were similar to the charging and discharging conditions in the first cycle, except that the current density during charging and discharging was changed to 3 mA/cm ² .

When examining the cycle characteristics, a secondary battery was used that stabilized the battery state by a procedure similar to the case of examining the initial charge/discharge characteristics. The secondary battery was charged and discharged to measure the discharge capacity in the second cycle. Subsequently, the secondary battery was repeatedly charged and discharged until the total number of cycles reached 100 cycles, and the discharge capacity at the 100th cycle was measured. From the measurement results, [capacity retention ratio (%) = (discharge capacity at 100th cycle/2 discharge capacity at 2nd cycle) x 100] was calculated. The charging and discharging conditions were similar to those of the initial charging and discharging characteristics (the second cycle and later).

The surface of the anode active material (coat) was observed using SEM. Accordingly, SEM photographs illustrated in FIGS. 2 and 3 were obtained. Figure 2 is a SEM image of a specific ion detected by the cation analysis of the coating (Example 1-1), Figure 3 is a specific ion is not detected by the cation analysis of the coating (Example 1-6) It is a SEM photograph.

The initial efficiency and capacity retention rate varied greatly depending on the presence or absence of the coating and its physical properties (kind of cation). More specifically, when the covering was provided on the center, the initial efficiency was significantly increased and the capacity retention rate was increased as compared to the case where the covering was not formed. In addition, when the coating portion was provided on the center portion, when a specific ion was detected by cation analysis of the coating portion, the initial efficiency was further increased and the capacity retention rate was significantly increased compared to a case where no specific ion was detected.

When a specific ion was detected by cation analysis of the coating, as shown in FIG. 2, an uneven structure due to the specific ion was formed on the surface of the coating. On the other hand, when a specific ion was not detected, as illustrated in FIG. 3, an uneven structure due to the specific ion was not formed, and the surface of the coating was substantially flat.

[Examples 2-1 to 2-11]

A secondary battery was prepared by a procedure similar to that of Example 1-1, except that the ratio D1/D2 and the ratio D1/D3 were changed as illustrated in Table 2, and various characteristics were investigated. In these embodiments, the ratio D1/D2 and ratio D1/D3 are changed by changing conditions such as the mixing ratio between methane gas and acetylene gas, the heating temperature, and the type of auxiliary gas in the step of forming the coating by the pyrolysis CVD method. Adjusted.

When a specific ion is detected by cation analysis of the coating, a high initial efficiency of 70% or more and a high capacity retention rate of 80% or more are obtained, when the ratio D1/D2 is 1.25 or more, and when the ratio D1/D2 is less than 1.25 Became. When the ratio D1/D2 is 50 or more, the initial efficiency and capacity retention rate are further increased, so that both are substantially maximized. In addition, when the ratio D1/D3 is greater than 1, the initial efficiency and capacity retention rate are increased more than when the ratio D1/D3 is less than 1.

[Examples 3-1 to 3-9]

A secondary battery was manufactured by a procedure similar to that of Example 1-1, except that the average thickness and average coverage of the coating portion were changed as illustrated in FIG. 3, and various characteristics were investigated. In these embodiments, the average thickness was adjusted by changing conditions such as deposition rate and deposition time in the step of forming the coating, and the average coverage was adjusted by changing conditions such as input power and deposition time.

High initial efficiency and high capacity retention were obtained without depending on the average thickness of the coating. However, when the average thickness was larger than 500 nm, the amount of formation of the coating portion was excessively large, so that the battery capacity was lowered. Therefore, when the average thickness was 500 nm or less, high initial efficiency and high capacity retention were obtained, and high cell capacity was also obtained. In addition, when the average coverage of the coating portion was 30% or more, high initial efficiency and high capacity retention were obtained.

[Examples 4-1 to 4-9]

A secondary battery was prepared by a procedure similar to that of Example 1-1, except that the ratio IG/ID of the coating portion was changed as illustrated in Table 4, and various characteristics were investigated. In these examples, in the step of forming the coating, the ratio IG/ID was adjusted by changing conditions such as pressure, thermal decomposition temperature, and type of carbon source gas.

When the ratio IG/ID was 0.3 or more and 3 or less, a high initial efficiency of 70% or more and a high capacity retention rate of 80% or more were obtained when the ratio IG/ID was outside the above range.

[Examples 5-1 to 5-5]

A secondary battery was prepared by a procedure similar to that of Example 1-1, except that the composition (SiO _w ) of the central portion was changed as illustrated in Table 5, and various characteristics were investigated. In these examples, the composition (atomic ratio w) was adjusted by changing the amount of oxygen introduced during melting and solidification of the raw material silicon.

When the atomic ratio (w) was 0.3 or more, compared with the case where the atomic ratio (w) was less than 0.3, a high capacity retention rate was obtained while maintaining high initial efficiency. In addition, when the atomic ratio (w) was less than 1.9, high initial efficiency was obtained while maintaining a high capacity retention rate, compared to when the atomic ratio (w) was 1.9 or more.

[Examples 6-1 to 6-9]

A secondary battery was manufactured by a procedure similar to that of Example 1-1, except that the atomic ratio (Si/O) on the center surface was changed as illustrated in Table 6, and various characteristics were investigated. In these embodiments, the atomic ratio was adjusted by changing conditions such as the amount of supply of hydrogen gas and the heating temperature in the step of reducing the surface of the center by heating the center while supplying hydrogen gas. Note that the term "trend" illustrated in Table 6 refers to the transition of the atomic ratio from the surface of the center to its interior.

When the atomic ratio was 75 atomic% or less, the capacity retention rate was significantly increased. Further, when the atomic ratio was 30 atomic% or more to 70 atomic% or less, a high capacity retention rate of 80% or more was obtained. In these embodiments, when the transition of the atomic ratio is in a reduced state or a constant state, the initial efficiency and capacity retention rate are increased more than when the transition of the atomic ratio is in an increased state.

[Examples 7-1 to 7-6]

A secondary battery was manufactured by a procedure similar to that of Example 1-1, except that the middle diameter (D50) of the center was changed as illustrated in Table 7, and various characteristics were investigated. In these examples, the median diameter was adjusted by changing the crushing conditions and the like of the formed film.

When the median diameter (D50) was 0.1 µm or more and 20 µm or less, the initial efficiency and capacity retention rate were further increased, and particularly, a high capacity retention rate of 80% or more was obtained.

[Examples 8-1 to 8-12]

A secondary battery was manufactured by a procedure similar to that of Example 1-1, except that the average area occupancy and average particle size of the central grains were changed as illustrated in Table 8, and various characteristics were investigated. In these examples, the average area occupancy and average particle diameter were adjusted by changing conditions such as temperature and time during heating in the step of depositing silicon oxide while heating silicon oxide in an argon gas atmosphere.

When the average area occupancy was 35% or less and the average particle diameter was 30 nm or less, the initial efficiency and capacity retention rate were further increased.

[Examples 9-1 to 9-9]

A secondary battery was manufactured by a procedure similar to that of Example 1-1, except that the metal element was contained in the center as illustrated in Table 9, and various characteristics were investigated. In these embodiments, co-deposition was performed using a silicon oxide powder and a metal powder in the step of forming the central portion.

When the central portion contains a metal element, one or both of the initial efficiency and capacity retention rate was further increased.

[Examples 10-1 and 10-2]

A secondary battery was prepared by a procedure similar to that of Example 1-1, except that the anode active material was pre-doped with lithium as illustrated in Table 10, and various characteristics were investigated. In these examples, the lithium metal powder was mixed with the anode active material and the like, and then the obtained mixture was heated in an inert gas (Ar) atmosphere (heating temperature: 500°C) (powder mixing method). Further, after the anode 54 was prepared, lithium metal was deposited on the anode 54 using a vapor deposition method (deposition method).

When the center was pre-doped, the initial efficiency and capacity retention rate increased further.

[Examples 11-1 to 11-9]

A secondary battery was manufactured by a procedure similar to that of Example 1-1 except for changing the type of anode binder, as illustrated in Table 11, to investigate various characteristics. In these embodiments, as the anode binder, polyamideimide (PAI), polyvinylidene fluoride (PVDF), polyamide (PA), polyacrylic acid (PAA), lithium polyacrylate (PAALi), polyimide carbide ( PI carbide), polyethylene (PE), polymaleic acid (PMA) and aramid (AR) were used. When PAA or PAALi was used, an anode mixture slurry was prepared using 17 volume% aqueous solution (containing 1.5% by weight of polyethylene particles) obtained by dissolving PAA or PAALi in pure water, and heat-pressing the obtained anode mixture slurry , Note that the anode active material layer 54B was formed without firing.

When the type of anode binder was changed, high initial efficiency and high capacity retention were obtained.

[Examples 12-1 to 12-3]

As illustrated in Table 12, a secondary battery was prepared by a procedure similar to that of Example 1-1, except that the anode current collector 54A contained carbon and sulfur, and various characteristics were investigated. In these embodiments, as the anode current collector 54A, a rolled copper foil doped with carbon and sulfur was used.

When carbon and sulfur are included in the anode current collector 54A, initial efficiency and capacity retention are further increased. In these examples, when the sum of carbon content and sulfur content is 100 ppm or less, the capacity retention rate is further increased.

From the results of Tables 1 to 12, excellent initial charge/discharge characteristics are obtained when specific ions are detected by cation analysis of a coating portion using TOF-SIMS in a coating portion provided on a central portion containing silicon as a constituent element. And excellent cycle characteristics were obtained.

The present invention has been described with reference to embodiments and examples. However, the present invention is not limited to the examples described in the embodiments and examples, and various modifications can be made. For example, the secondary battery of the present invention, the capacity of the anode includes a capacity related to the deposition and dissolution of lithium metal and the capacity by adsorption and release of lithium ions, and the battery capacity is represented by a sum of the above capacity Similar can be applied. In this case, an anode material capable of occluding and releasing lithium ions is used, and the chargeable capacity of the anode material is set to a value smaller than the discharge capacity of the cathode.

Further, for example, the secondary battery of the present invention can be similarly applied to a battery having a different battery structure such as a coin-type battery or a button-type battery, and a battery in which the battery element has a different structure such as a stacked structure.

Further, for example, the electrode reactant may be another group 1 element such as sodium (Na) and potassium (K), a group 2 element such as magnesium (Mg) and calcium (Ca), or other light metal such as aluminum (Al). Can be The effect of the present invention can be obtained without depending on the type of the electrode reactant, and thus, even when the type of the electrode reactant is changed, a similar effect can be obtained.

In addition, in the embodiments and examples, appropriate ranges derived from the results of the examples have been described in relation to the properties of the coating (ratio D1/D2 and ratio D1/D3). However, the above description does not completely deny the possibility that the ratio D1/D2 and the ratio D1/D3 are out of the above range. That is, the appropriate range described above is a particularly preferred range for obtaining the effect of the present invention. Therefore, as long as the effect of the present invention is obtained, the ratio D1/D2 and the ratio D1/D3 may slightly fall outside the above range. The same may be applied to other numerical ranges (eg, atomic ratio ranges) specified in the claims.

It is possible to achieve at least the following configuration from the above-described exemplary embodiment of the present application.

(1) As a secondary battery,

Cathode;

An anode containing an active material; And

Electrolyte

It includes,

The active material includes a central portion and a coating provided on the surface of the central portion,

The central portion includes silicon (Si) as a constituent element,

The coating portion includes carbon (C) and hydrogen (H) as constituent elements,

Secondary, wherein one or more cations represented by C _x H _y (where x and y satisfy 2≤x≤6 and 3≤y≤9) are detected by cation analysis of the coating portion using a time-of-flight secondary ion mass spectrometry. battery.

(2) In (1),

A secondary battery in which the ratio D1/D2 between the sum (D1) of the detection strengths of the cations represented by C ₂ H ₃ , C ₂ H ₅ and C ₃ H ₅ and the detection strength (D2) of C is about 1.25 or more, or about 50 or more .

(3) In (1) or (2),

Sum of detection strengths of cations represented by C ₂ H ₃ , C ₂ H ₅ and C ₃ H ₅ (D1) and sum of detection strengths of cations represented by CH _z (z satisfies 0≤z≤3) (D3) A secondary battery in which the liver ratio D1/D3 is greater than about 1.

(4) The method according to any one of (1) to (3),

The average thickness of the coating is about 500 nm or less,

The average coverage of the coating portion relative to the central portion is about 30% or more,

A secondary battery in which the ratio (IG/ID) between the intensity (IG) of the G band and the intensity (ID) of the D band measured by the Raman spectrum method is about 0.3 or more to about 3 or less.

(5) The method according to any one of (1) to (4),

The surface of the coating portion has a concavo-convex structure due to one or more cations represented by the C _x H _y (2≤x≤6, 3≤y≤9).

(6) The method according to any one of (1) to (5),

The central portion includes a secondary battery, containing oxygen (O) as a constituent element.

(7) In (6),

The center portion includes silicon oxide represented by SiO _w (w satisfies 0.3≦w<1.9),

The atomic ratio (Si/O) of silicon to oxygen on the surface of the center is about 75 atomic% or less, or about 30 atomic% or more to about 70 atomic% or less.

(8) The method according to any one of (1) to (7),

The middle diameter (D50) of the center is about 0.1 μm or more to about 20 μm or less, the secondary battery.

(9) The method according to any one of (1) to (8),

The central portion includes at least one of iron (Fe), aluminum (Al), calcium (Ca), manganese (Mn), chromium (Cr), magnesium (Mg), and nickel (Ni) as constituent elements.

(10) The method according to any one of (1) to (9),

A crystal region (crystal grain) is scattered in the amorphous region in the center,

The average area occupancy of the crystal grains due to the (111) and (220) planes of silicon is about 35% or less,

A secondary battery having an average particle diameter of the crystal grains of about 30 nm or less.

(11) The method according to any one of (1) to (10),

Part or all of the silicon is alloyed with lithium (Li) in the central portion of the uncharged state,

A secondary battery, wherein the central portion comprises a lithium silicate.

(12) The method according to any one of (1) to (11),

The anode includes an active material layer on the current collector,

The active material layer includes the active material,

The current collector includes copper (Cu), carbon (C), and sulfur (S) as constituent elements,

A secondary battery in which the sum of carbon and sulfur content in the current collector is about 100 ppm or less.

(13) The secondary battery according to any one of (1) to (12), wherein the secondary battery is a lithium ion secondary battery.

(14) As an electrode,

Contains active substances,

The active material includes a central portion, and a coating provided on the surface of the central portion,

The central portion includes silicon (Si) as a constituent element,

The coating portion includes carbon (C) and hydrogen (H) as constituent elements,

An electrode in which one or more cations represented by C _x H _y (where x and y satisfy 2≤x≤6 and 3≤y≤9) are detected by cation analysis of the coated portion using a time-of-flight secondary ion mass spectrometry. .

(15) As an active material,

center; And

The covering provided on the surface of the center

It includes,

The central portion includes silicon (Si) as a constituent element,

The coating portion includes carbon (C) and hydrogen (H) as constituent elements,

An active material in which one or more cations represented by C _x H _y (where x and y satisfy 2≤x≤6 and 3≤y≤9) are detected by cation analysis of the coating portion using a time-of-flight secondary ion mass spectrometry .

(16) As a battery pack,

Secondary battery;

A control unit configured to control the operation of the secondary battery; And

A switch unit configured to switch the operation of the secondary battery according to the instructions of the control unit

It includes,

The secondary battery includes a cathode, an anode containing an active material, and an electrolyte,

The active material includes a central portion, and a coating provided on the surface of the central portion,

The central portion includes silicon (Si) as a constituent element,

The coating portion includes carbon (C) and hydrogen (H) as constituent elements,

A battery in which one or more cations represented by C _x H _y (where x and y satisfy 2≤x≤6 and 3≤y≤9) are detected by cation analysis of the coated portion using a time-of-flight secondary ion mass spectrometry. pack.

(17) As an electric vehicle,

Secondary battery;

A converter configured to convert power supplied from the secondary battery into driving force;

A driving unit configured to operate according to the driving force; And

Control unit configured to control the operation of the secondary battery

It includes,

The secondary battery includes a cathode, an anode containing an active material, and an electrolyte,

The active material includes a central portion, and a coating provided on the surface of the central portion,

The central portion includes silicon (Si) as a constituent element,

The coating portion includes carbon (C) and hydrogen (H) as constituent elements,

The cation analysis of the cladding portion using the time-of-flight secondary ion mass spectrometry detects one or more cations represented by C _x H _y (where x and y satisfy 2≤x≤6 and 3≤y≤9). vehicle.

(18) As a power storage system

Secondary battery;

At least one electrical device configured to receive power from the secondary battery; And

A control unit configured to control supply of power from the secondary battery to the one or more electrical devices

It includes,

The secondary battery includes a cathode, an anode containing an active material, and an electrolyte,

The active material includes a central portion, and a coating provided on the surface of the central portion,

The central portion includes silicon (Si) as a constituent element,

The coating portion includes carbon (C) and hydrogen (H) as constituent elements,

Power by which one or more cations represented by C _x H _y (where x and y satisfy 2≤x≤6 and 3≤y≤9) are detected by cation analysis of the coating portion using a time-of-flight secondary ion mass spectrometry. Storage system.

(19) As a power tool,

Secondary battery; And

A movable unit configured to receive power from the secondary battery

It includes,

The secondary battery includes a cathode, an anode containing an active material, and an electrolyte,

The active material includes a central portion, and a coating provided on the surface of the central portion,

The central portion includes silicon (Si) as a constituent element,

The coating portion includes carbon (C) and hydrogen (H) as constituent elements,

The cation analysis of the cladding portion using the time-of-flight secondary ion mass spectrometry detects one or more cations represented by C _x H _y (where x and y satisfy 2≤x≤6 and 3≤y≤9). tool.

(20) As an electronic device,

It includes a secondary battery as a power source,

The secondary battery includes a cathode, an anode containing an active material, and an electrolyte,

The active material includes a central portion, and a coating provided on the surface of the central portion,

The central portion includes silicon (Si) as a constituent element,

The coating portion includes carbon (C) and hydrogen (H) as constituent elements,

One or more cations represented by C _x H _y (where x and y satisfy 2≤x≤6 and 3≤y≤9) are detected by cation analysis of the coating portion using a time-of-flight secondary ion mass spectrometry electron device.

It should be understood by those skilled in the art that various modifications, combinations, sub-combinations, and substitutions may occur depending on design requirements and other factors, as long as they are within the scope of the appended claims and equivalents thereof.

Claims (20)

As a secondary battery,
Cathode;
An anode containing an active material; And
Electrolyte
It includes,
The active material includes a central portion, and a coating provided on the surface of the central portion,
The central portion includes silicon (Si) as a constituent element,
The coating portion includes carbon (C) and hydrogen (H) as constituent elements,
One or more cations represented by C _x H _y (where x and y satisfy 2≤x≤6 and 3≤y≤9) are detected by cation analysis of the coating part using a time-of-flight secondary ion mass spectrometry,
The ratio D1/D2 between the sum (D1) of the detection strengths of the cations represented by C ₂ H ₃ , C ₂ H ₅ and C ₃ H ₅ and the detection strength (D2) of C is 1.25 or more,
Sum of detection strengths of cations represented by C ₂ H ₃ , C ₂ H ₅ and C ₃ H ₅ (D1) and sum of detection strengths of cations represented by CH _z (z satisfies 0≤z≤3) (D3) A secondary battery in which the ratio D1/D3 of the liver is greater than 1. delete delete According to claim 1,
The average thickness of the coating is 500 nm or less,
The average coverage of the coating portion relative to the central portion is 30% or more,
A secondary battery in which the ratio (IG/ID) between the intensity (IG) of the G band and the intensity (ID) of the D band measured by the Raman spectrum method is 0.3 or more and 3 or less. The secondary battery according to claim 1, wherein the surface of the coating portion has an uneven structure caused by one or more cations represented by C _x H _y (2≤x≤6, 3≤y≤9). The secondary battery according to claim 1, wherein the central portion contains oxygen (O) as a constituent element. The method of claim 6,
The center portion includes silicon oxide represented by SiO _w (w satisfies 0.3≦w<1.9),
On the surface of the central portion, the atomic ratio (Si/O) of silicon to oxygen is 75 atomic% or less, or 30 atomic% or more to 70 atomic% or less. The secondary battery according to claim 1, wherein an intermediate diameter (D50) of the central portion is 0.1 μm or more to 20 μm or less. The method of claim 1, wherein the central portion is at least one of iron (Fe), aluminum (Al), calcium (Ca), manganese (Mn), chromium (Cr), magnesium (Mg), and nickel (Ni) as constituent elements. Included, secondary battery. According to claim 1,
A crystal region (crystal grain) is scattered in the amorphous region in the center,
The average area occupancy of the crystal grains due to the (111) and (220) planes of silicon is 35% or less,
A secondary battery having an average particle size of the crystal grains of 30 nm or less. According to claim 1,
Part or all of the silicon is alloyed with lithium (Li) in the central portion of the uncharged state,
A secondary battery, wherein the central portion comprises a lithium silicate. According to claim 1,
The anode includes an active material layer on the current collector,
The active material layer includes the active material,
The current collector includes copper (Cu), carbon (C), and sulfur (S) as constituent elements,
A secondary battery in which the sum of the content of carbon and sulfur in the current collector is 100 ppm or less. The secondary battery according to claim 1, wherein the secondary battery is a lithium ion secondary battery. As an electrode,
Contains active substances,
The active material includes a central portion, and a coating provided on the surface of the central portion,
The central portion includes silicon (Si) as a constituent element,
The coating portion includes carbon (C) and hydrogen (H) as constituent elements,
One or more cations represented by C _x H _y (where x and y satisfy 2≤x≤6 and 3≤y≤9) are detected by cation analysis of the coating part using a time-of-flight secondary ion mass spectrometry,
The ratio D1/D2 between the sum (D1) of the detection strengths of the cations represented by C ₂ H ₃ , C ₂ H ₅ and C ₃ H ₅ and the detection strength (D2) of C is 1.25 or more,
Sum of detection strengths of cations represented by C ₂ H ₃ , C ₂ H ₅ and C ₃ H ₅ (D1) and sum of detection strengths of cations represented by CH _z (z satisfies 0≤z≤3) (D3) The electrode, wherein the liver ratio D1/D3 is greater than 1. As an active material,
center; And
The covering provided on the surface of the center
It includes,
The central portion includes silicon (Si) as a constituent element,
The coating portion includes carbon (C) and hydrogen (H) as constituent elements,
One or more cations represented by C _x H _y (where x and y satisfy 2≤x≤6 and 3≤y≤9) are detected by cation analysis of the coating part using a time-of-flight secondary ion mass spectrometry,
The ratio D1/D2 between the sum (D1) of the detection strengths of the cations represented by C ₂ H ₃ , C ₂ H ₅ and C ₃ H ₅ and the detection strength (D2) of C is 1.25 or more,
Sum of detection strengths of cations represented by C ₂ H ₃ , C ₂ H ₅ and C ₃ H ₅ (D1) and sum of detection strengths of cations represented by CH _z (z satisfies 0≤z≤3) (D3) Liver ratio D1/D3 is greater than 1, active material. As a battery pack,
Secondary battery;
A control unit configured to control the operation of the secondary battery; And
A switch unit configured to switch the operation of the secondary battery according to the instructions of the control unit
It includes,
The secondary battery includes a cathode, an anode containing an active material, and an electrolyte,
The active material includes a central portion, and a coating provided on the surface of the central portion,
The central portion includes silicon (Si) as a constituent element,
The coating portion includes carbon (C) and hydrogen (H) as constituent elements,
One or more cations represented by C _x H _y (where x and y satisfy 2≤x≤6 and 3≤y≤9) are detected by cation analysis of the coating part using a time-of-flight secondary ion mass spectrometry,
The ratio D1/D2 between the sum (D1) of the detection strengths of the cations represented by C ₂ H ₃ , C ₂ H ₅ and C ₃ H ₅ and the detection strength (D2) of C is 1.25 or more,
Sum of detection strengths of cations represented by C ₂ H ₃ , C ₂ H ₅ and C ₃ H ₅ (D1) and sum of detection strengths of cations represented by CH _z (z satisfies 0≤z≤3) (D3) A battery pack in which the liver ratio D1/D3 is greater than 1. As an electric vehicle,
Secondary battery;
A converter configured to convert power supplied from the secondary battery into driving force;
A driving unit configured to operate according to the driving force; And
Control unit configured to control the operation of the secondary battery
It includes,
The secondary battery includes a cathode, an anode containing an active material, and an electrolyte,
The active material includes a central portion, and a coating provided on the surface of the central portion,
The central portion includes silicon (Si) as a constituent element,
The coating portion includes carbon (C) and hydrogen (H) as constituent elements,
One or more cations represented by C _x H _y (where x and y satisfy 2≤x≤6 and 3≤y≤9) are detected by cation analysis of the coating part using a time-of-flight secondary ion mass spectrometry,
The ratio D1/D2 between the sum (D1) of the detection strengths of the cations represented by C ₂ H ₃ , C ₂ H ₅ and C ₃ H ₅ and the detection strength (D2) of C is 1.25 or more,
Sum of detection strengths of cations represented by C ₂ H ₃ , C ₂ H ₅ and C ₃ H ₅ (D1) and sum of detection strengths of cations represented by CH _z (z satisfies 0≤z≤3) (D3) The electric vehicle which the ratio D1/D3 of the liver is greater than one. As a power storage system,
Secondary battery;
At least one electrical device configured to receive power from the secondary battery; And
A control unit configured to control supply of power from the secondary battery to the one or more electrical devices
It includes,
The secondary battery includes a cathode, an anode containing an active material, and an electrolyte,
The active material includes a central portion, and a coating provided on the surface of the central portion,
The central portion includes silicon (Si) as a constituent element,
The coating portion includes carbon (C) and hydrogen (H) as constituent elements,
One or more cations represented by C _x H _y (where x and y satisfy 2≤x≤6 and 3≤y≤9) are detected by cation analysis of the coating part using a time-of-flight secondary ion mass spectrometry,
The ratio D1/D2 between the sum (D1) of the detection strengths of the cations represented by C ₂ H ₃ , C ₂ H ₅ and C ₃ H ₅ and the detection strength (D2) of C is 1.25 or more,
Sum of detection strengths of cations represented by C ₂ H ₃ , C ₂ H ₅ and C ₃ H ₅ (D1) and sum of detection strengths of cations represented by CH _z (z satisfies 0≤z≤3) (D3) A power storage system in which the ratio D1/D3 of the liver is greater than 1. As a power tool,
Secondary battery; And
A movable unit configured to receive power from the secondary battery
It includes,
The secondary battery includes a cathode, an anode containing an active material, and an electrolyte,
The active material includes a central portion, and a coating provided on the surface of the central portion,
The central portion includes silicon (Si) as a constituent element,
The coating portion includes carbon (C) and hydrogen (H) as constituent elements,
One or more cations represented by C _x H _y (where x and y satisfy 2≤x≤6 and 3≤y≤9) are detected by cation analysis of the coating part using a time-of-flight secondary ion mass spectrometry,
The ratio D1/D2 between the sum (D1) of the detection strengths of the cations represented by C ₂ H ₃ , C ₂ H ₅ and C ₃ H ₅ and the detection strength (D2) of C is 1.25 or more,
Sum of detection strengths of cations represented by C ₂ H ₃ , C ₂ H ₅ and C ₃ H ₅ (D1) and sum of detection strengths of cations represented by CH _z (z satisfies 0≤z≤3) (D3) Power tool with liver ratio D1/D3 greater than 1. As an electronic device,
It includes a secondary battery as a power source,
The secondary battery includes a cathode, an anode containing an active material, and an electrolyte,
The active material includes a central portion, and a coating provided on the surface of the central portion,
The central portion includes silicon (Si) as a constituent element,
The coating portion includes carbon (C) and hydrogen (H) as constituent elements,
One or more cations represented by C _x H _y (where x and y satisfy 2≤x≤6 and 3≤y≤9) are detected by cation analysis of the coating part using a time-of-flight secondary ion mass spectrometry,
The ratio D1/D2 between the sum (D1) of the detection strengths of the cations represented by C ₂ H ₃ , C ₂ H ₅ and C ₃ H ₅ and the detection strength (D2) of C is 1.25 or more,
Sum of detection strengths of cations represented by C ₂ H ₃ , C ₂ H ₅ and C ₃ H ₅ (D1) and sum of detection strengths of cations represented by CH _z (z satisfies 0≤z≤3) (D3) An electronic device having a liver ratio D1/D3 greater than 1.

Images