JP6213980B2 - Electrochemical cell - Google Patents

Description

  The present invention relates to an electrochemical cell, and more particularly to an electrochemical cell such as a non-aqueous electrolyte secondary battery, an electric double layer capacitor, or an ion capacitor.

  An electrochemical cell such as a non-aqueous electrolyte secondary battery that is an electricity storage device includes a pair of polarizable electrodes composed of a positive electrode and a negative electrode in a sealed storage container, and a separator interposed between the positive electrode and the negative electrode, A positive electrode, a negative electrode, and a separator are impregnated and provided with an electrolytic solution containing a supporting salt and a nonaqueous solvent. Such electrochemical cells are used in various small electronic devices such as mobile phones, PDAs, and portable game machines, and in particular, those of laminate type, cylinder, bottomed rectangular shape, coin (button) type, etc. Is frequently used.

Further, SiO _x , Si, and C are widely used as negative electrode active materials in negative electrodes provided in lithium ion batteries that are electrochemical cells. The negative electrode used in such an electrochemical cell has a negative electrode active material capable of inserting and extracting lithium ions, a conductive agent that exchanges electrons with the negative electrode active material, and a contact state between the negative electrode active material and the conductive agent. It consists of a binder for maintaining, and a negative electrode material is formed by mixing these. Alternatively, when the negative electrode active material constituting the negative electrode is formed as a thin film, a structure in which the negative electrode material is physically brought into direct contact with a current collector made of a metal foil such as copper foil or stainless steel is employed. Sometimes.

  Since the negative electrode active material as described above is in an amorphal form, when an alkali metal ion typified by lithium ion or an alkaline earth metal ion such as magnesium is inserted into the amorphal negative electrode active material. Volume expansion occurs, and abrupt contraction occurs when lithium ions are deinserted, which may cause cracks in the particles of amorphal. When the electrolytic solution comes into contact with such a crack, a new SEI (Solid Electrolite Interface) is formed. By repeating the charging cycle, the crack of the negative electrode active material spreads and the crack progresses further. Peeling of the negative electrode active material occurs. For this reason, the electron conductivity path is severed, and at the same time, the ionic conductivity is significantly reduced, which causes a problem of deterioration in cycle life characteristics such as a decrease in charge / discharge capacity of the electrochemical cell. .

Therefore, for negative electrode active materials mainly composed of silicon (Si), alkali metals such as sodium, potassium and rubidium, alkaline earth metals such as magnesium and calcium, and / or iron, nickel, cobalt, manganese, vanadium, titanium Li _x M with addition of metals such as niobium, tungsten, molybdenum, copper, zinc, tin, lead, aluminum, indium, bismuth, gallium, germanium, carbon, boron, nitrogen, phosphorus, semi-metals or non-metals _{A material} composed of _y SiO _z (where 0 ≦ x, 0 ≦ y <2, 0 <z ≦ 4, M is one or more elements selected from metals and nonmetallic elements other than lithium and silicon) has been proposed. (For example, see Patent Document 1).

In addition, for the purpose of imparting electronic conductivity to deterioration of cycle life characteristics, a method of imparting natural scaly graphite or expanded graphite to a negative electrode active material has been proposed (for example, Patent Document 2). See).
Also, electron conductivity is imparted to the negative electrode active material by plating in a molten state metal material particles made of any of Al, Ti, Fe, Ni, Cu, Zn, Pd, Ag, In, and Sn. It has also been proposed (see, for example, Patent Document 3).

Japanese Patent No. 3405380 Japanese Patent No. 3188533 JP-A-11-250869

  However, since the negative electrode active material containing Si element has a large amount of Li occlusion during charge / discharge, the volume change rate associated with charge / discharge also increases. For this reason, due to the stress caused by the volume change during charging / discharging, the deterioration of current collection occurs, the internal resistance increases, and the capacity deterioration due to pulverization increases, so the cycle life characteristics deteriorate. However, the conventional techniques represented by Patent Documents 1 to 3 and the like are not sufficient to solve the above problem.

  The present invention has been made in view of the above problems, and suppresses generation of cracks in the negative electrode due to volume expansion / reduction during charge / discharge, and is highly reliable, high capacity, and excellent in cycle life characteristics. It is an object to provide an electrochemical cell.

  The present inventors diligently studied to solve the above-mentioned problems, and regarding the negative electrode active material used for the negative electrode, by adopting a configuration including at least a Si element and further including a specific additive element, charging and discharging are performed. It has been found that cracking of the negative electrode can be suppressed by the volume expansion / reduction of. As a result, it was found that an increase in internal resistance and capacity deterioration can be suppressed, and the cycle life characteristics are improved, and the present invention has been completed.

That is, the invention described in claim 1 is an electrochemical cell comprising a positive electrode, a negative electrode, an electrolyte containing a supporting salt and a nonaqueous solvent, and a separator, wherein the negative electrode active material used for the negative electrode is And a substance containing at least Si element, represented by the following formula {A _x SiO _y M _z + R}, capable of reversibly inserting and desorbing ions of alkali metal or alkaline earth metal, and One or both of the first additive element M and the second additive element R shown in FIG. 1 is 1 ppm or more by mass ratio with respect to the total amount of Si element contained in the negative electrode active material. D50 is a fine particle having an average particle diameter of D50 of 1 nm or more and 50 μm or less, and the negative electrode is graphite as a carbon material for imparting electronic conductivity , and optionally carbon fiber. And the compounding ratio of SiO _y M _z + R, which is the precursor of the negative electrode active material, the graphite, and the carbon fiber is represented by the following formula {SiO _y M _z + R: graphite: carbon fiber = 45: An electrochemical cell having a range of 45: 0 to 45:35:10}.
(1) First additive element M: at least one element of B or P.
(2) Second additive element R: At least one element selected from the group consisting of Ti and C.
However, in the above formula _{{A x SiO y M z +} R} , A represents a cationic species, an alkali metal ion or alkaline earth metal ions of elements, x is the formula in ionic species content A { It takes a value of 0 ≦ x ≦ 4.4}, y is the amount of oxygen and is the following formula {0 ≦ y ≦ 2}, M is the first additive element, and R is the second additive element.
The invention according to claim 2 is an electrochemical cell comprising a positive electrode, a negative electrode, an electrolyte containing a supporting salt and a non-aqueous solvent, and a separator, wherein the negative electrode active material used for the negative electrode is And containing at least Si element , represented by the following formula {A _x SiO _y M _z + R}, comprising a substance capable of reversibly inserting and desorbing alkali metal or alkaline earth metal ions, and The first additive element M shown below is 10 ppm or more and 1% or less and the second additive element R shown below is 0.5% or more and 2% or less with respect to the total amount of Si element contained in the negative electrode active material. D50 is a fine particle having an average particle diameter of D50 of 1 nm or more and 50 μm or less, and the negative electrode is made of graphite as a carbon material for imparting electronic conductivity, and optionally carbon fiber. Including And, and, the negative active and _SiO y _M z + R which is a precursor material, said graphite, the mixing ratio of the carbon fibers have the following formula _{{SiO y M} z + R: Graphite: Carbon Fiber = 45: 45: An electrochemical cell having a range of 0 to 45:35:10}.
(1) First additive element M: at least one element of B or P.
(2) Second additive element R: At least one element selected from the group consisting of Ti and C.
However, in the above formula _{{A x SiO y M z +} R} , A represents a cationic species, an alkali metal ion or alkaline earth metal ions of elements, x is the formula in ionic species content A { It takes a value of 0 ≦ x ≦ 4.4}, y is the amount of oxygen and is the following formula {0 ≦ y ≦ 2}, M is the first additive element, and R is the second additive element.

According to the above configuration, since the negative electrode active material is stably present in an amorphous state by including the first additive element M, the insertion of alkali metal ions such as lithium by the charging / discharging of the electrochemical cell is performed. When the desorption is repeated, it is possible to suppress the generation of cracks due to the volume expansion / contraction that occurs in the negative electrode.
Moreover, since the negative electrode active material stably exists in an amorphous state by including the second additive element R, when repeatedly inserting and desorbing alkali metal ions such as lithium by charging and discharging the electrochemical cell, The electron conductivity in the negative electrode active material is increased, and the charge uniformity in the negative electrode active material can be increased. Thereby, it is possible to prevent the occurrence of cracks by preventing the bias at the time of insertion of alkali metal ions and by preventing the localization of volume expansion and contraction.
In addition, since the negative electrode active material is made of an oxide containing Si element, it is possible to reduce the non-uniformity of elements during the synthesis of the negative electrode active material. As a result, when the insertion and desorption of alkali metal ions such as lithium are repeated by charging and discharging the electrochemical cell, the electron conductivity in the negative electrode active material is increased, and the homogeneity of the charge in the negative electrode active material is increased. Is possible. Therefore, it is possible to prevent the occurrence of cracks by preventing the bias at the time of insertion of alkali metal ions and by preventing the localization of volume expansion and contraction.
In addition, when the average particle diameter of D50 of the negative electrode active material is 1 nm or more and 50 μm or less, the effect of suppressing the occurrence of cracks due to volume expansion / contraction generated in the negative electrode during charge / discharge of the battery is more remarkable. Is obtained.
Further, when the negative electrode contains a carbon material for imparting electronic conductivity with the above composition, the negative electrode is repeatedly inserted and desorbed by alkali metal ions such as lithium by charging and discharging the electrochemical cell. Electron conductivity is imparted to the entire surface around the active material particles, and the electron conductivity of the negative electrode active material particles is enhanced. As a result, it is possible to prevent unevenness at the time of insertion of alkali metal ions in the thickness direction and the horizontal direction in the electrode layer of the negative electrode, and to prevent localization of volume expansion and contraction. It becomes possible.

  Here, the “average particle diameter” described in the present invention refers to a value corresponding to D50 of the accumulated particle diameter of foreign particles having various shapes in addition to a spherical shape.

According to the electrochemical cell of the present invention, as described above, the negative electrode active material used for the negative electrode contains at least Si element and can reversibly insert and desorb ions of alkali metal or alkaline earth metal. Furthermore, the first additive element M {at least one of B or P} or the second additive element R {In, Sn, Ti, Al, Ge, C, Zr is selected from the group One or both of the at least one element} is a fine particle added by 1 ppm or more and 20% or less by mass ratio with respect to the total amount of Si element contained in the negative electrode active material. Adopted.
Thereby, it can suppress that a negative electrode cracks by the volume expansion / contraction at the time of charging / discharging, and it becomes possible to suppress a raise of internal resistance and capacity | capacitance degradation.
Therefore, it is possible to provide an electrochemical cell having high reliability, high capacity, and excellent cycle life characteristics.

FIG. 1 shows a nonaqueous electrolyte secondary battery and an electric double layer capacitor which are embodiments of the electrochemical cell of the present invention, or an electrode for an electric double layer capacitor is used for the positive electrode and the nonaqueous electrolyte of the present invention is used for the negative electrode. It is a figure which illustrates typically the hybrid capacitor using the electrode for secondary batteries, (a) is a disassembled perspective view which shows the state in which the electrode body was accommodated in the accommodating part of an exterior body, (b) is sectional drawing, ( c) is a perspective view showing a laminate structure of an electrode body. FIG. 2 shows a nonaqueous electrolyte secondary battery and an electric double layer capacitor which are embodiments of the electrochemical cell of the present invention, or an electrode for an electric double layer capacitor is used for the positive electrode and the nonaqueous electrolyte of the present invention is used for the negative electrode. It is process drawing which shows the manufacturing method of the hybrid capacitor using the electrode for secondary batteries.

  Hereinafter, as an embodiment of the electrochemical cell of the present invention, an embodiment of a non-aqueous electrolyte secondary battery (electric double layer capacitor) will be given, and each of those configurations will be described in detail with reference to the drawings. The electrochemical cell described in the present invention is specifically a non-aqueous electrolyte secondary battery or an electric double layer capacitor in which an active material used as a positive electrode or a negative electrode and an electrolytic solution are contained in a container, Alternatively, a hybrid capacitor using an electrode for an electric double layer capacitor as a positive electrode and an electrode for a non-aqueous electrolyte secondary battery according to the present invention as a negative electrode, and the like will be described in the present embodiment as an example. .

"Nonaqueous electrolyte secondary battery (electric double layer capacitor)"
The nonaqueous electrolyte secondary battery 1 of the present embodiment shown in FIGS. 1A to 1C is a so-called laminate type. 1A is an exploded perspective view showing a state in which the electrode body 10 is accommodated in the exterior body 2, FIG. 1B is a cross-sectional view of the nonaqueous electrolyte secondary battery 1, and FIG. 1C is an electrode body. It is a perspective view which shows the laminate structure of 10. FIG. In addition, the exploded perspective view of FIG. 1A is an exploded view of the integrally formed exterior body 2 divided into a first container portion 21 and a second container portion for convenience of explanation.
This non-aqueous electrolyte secondary battery 1 has a substantially flat shape in which the electrode body 10 is housed in housing portions 21a and 22a provided in a concave shape on the inner surface of an exterior body 2 made of a laminate film. In addition, in the housing portions 21a and 22a of the exterior body 2 in which the electrode body 10 is housed, an electrolyte solution (not shown) is filled.

Further, in the non-aqueous electrolyte secondary battery 1 of the present embodiment, the negative electrode active material used for the negative electrode 40 contains at least Si element and can reversibly insert and desorb ions of alkali metal or alkaline earth metal. Further, one or both of the first additive element M and the second additive element R shown below are each in mass with respect to the total amount of Si element contained in the negative electrode active material. It is set as the structure which is the microparticles | fine-particles added by 1 ppm or more and 20% or less by ratio.
(1) First additive element M: at least one element of B or P.
(2) Second additive element R: At least one element selected from the group consisting of In, Sn, Ti, Al, Ge, C, and Zr.

  The exterior body 2 used for the nonaqueous electrolyte secondary battery 1 of this embodiment is composed of, for example, an aluminum laminate film in which a nylon film, an aluminum foil, a polypropylene film, and the like are sequentially laminated and bonded together. At that time, an adhesive (not shown) may be interposed between the above-described layers. In the example shown in FIGS. 1A and 1B, the exterior body 2 is superposed on the first container part 21 in which a concave accommodating part 21 a is formed in a substantially central part in plan view, and the first container part 21. The second container portion 22 is formed with a concave accommodating portion 22a which is sealed inside. Moreover, in the example of illustration, the 1st container part 21 and the 2nd container part 22 are integrally formed.

  As described above, as a method of obtaining the battery structure by accommodating the electrode body 10 in the internal space of the exterior body 2 made of an aluminum laminate film, for example, the electrode body 10 is placed in a bag-like internal space made of an aluminum laminate film. And an electrolytic solution are injected, and after defoaming the inside, the aluminum laminate film is heat-sealed and sealed.

  Alternatively, a method in which the first and second container parts 21 and 22 are separately manufactured in advance is adopted, and the above-mentioned aluminum laminate film is set in a mold and then subjected to drawing and molding by applying pressure. 21a, 22a is formed, and then the electrode body 10 is loaded into the accommodating portions 21a, 22a and the electrolyte is injected, and then the peripheral portions of the first and second container portions 21, 22 can be bonded together. It is. In this case, it is preferable that these peripheral portions are welded or bonded together from the viewpoint of preventing leakage of the electrolytic solution accommodated in the accommodating portions 21a and 22a.

  As shown in FIG. 1C, the electrode body 10 includes a film-like positive electrode body 3 composed of a positive electrode 30 and a positive electrode current collector 31, and a film-shaped negative electrode body 4 composed of a negative electrode 40 and a negative electrode current collector 41. The laminate structure is formed by laminating a film-like separator 5 provided between the positive electrode body 3 and the negative electrode body 4. That is, the electrode body 10 has a configuration in which the positive electrode 30 and the negative electrode 40 are overlapped with each other with the separator 5 therebetween. Moreover, in the example shown to Fig.1 (a)-(c), the electrode body 10 is made into the spiral shape by which the laminated body which consists of each of these film-like layers was wound by the same direction.

  The positive electrode body 3, the negative electrode body 4, and the separator 5 are impregnated with an electrolyte solution (not shown) filled in the accommodating portions 21 a and 22 a of the first and second container portions 21 and 22.

  Further, each of the positive electrode current collector 31 and the negative electrode current collector 41 is connected to the positive electrode terminal 31a and the negative electrode terminal 41a as external terminals so as to be led out from the respective current collectors. It is set as the structure which can take out. In the nonaqueous electrolyte secondary battery 1, even when the positive electrode terminal 31 a and the negative electrode terminal 41 a protrude to the outside, the first container portion 21 and the second container portion 22 are overlapped and sealed. , Sealing is ensured.

  Below, each element which comprises the nonaqueous electrolyte secondary battery 1 is demonstrated in more detail.

"Electrode body"
As described above, as shown in FIGS. 1A to 1C, the electrode body 10 of the present embodiment is a laminated body in which the positive electrode body 3, the negative electrode body 4, and the separator 5 that are each formed into a film are sequentially laminated. The body has a structure in which the body is wound a predetermined number of times. The number of times the electrode body 10 is stacked, that is, the number of times the laminate structure is folded, can be appropriately set in consideration of battery characteristics and the like.

  The electrode body 10 is obtained by winding a laminate having the above-described laminate structure into a spiral shape, and then pressing the laminate so as to have a flat shape as shown in the illustrated example. Then, the electrode body 10 is loaded into the inner space of the bag made of an aluminum laminate film so that the positive electrode terminal 31a and the negative electrode terminal 41a taken out from the electrode body 10 are led out, and a predetermined amount of electrolyte is injected. After defoaming, the aluminum laminate film is heat-sealed and sealed.

(Positive electrode)
As the positive electrode 30, a conventionally known positive electrode active material, conductive additive, binder, or the like can be used.
First, examples of the positive electrode active material include a molybdenum oxide, a lithium manganate compound, a lithium iron phosphate compound, a lithium cobaltate compound, a lithium nickelate compound, and a layered compound composed of Co—Ni—Mn. , Lithium manganate compounds and lithium iron phosphate compounds are preferred. The positive electrode 30 contains the above-exemplified positive electrode active material, so that the heat resistance of the nonaqueous electrolyte secondary battery 1 is increased, for example, reflow treatment or discharge due to heating during use of the nonaqueous electrolyte secondary battery 1. A decrease in capacity is suppressed.

Examples of the lithium manganate compound include spinel type lithium manganese oxide, and Li ₄ Mn _5-w M ¹ _w O ₁₂ (0 ≦ w <1, M1 is Ni, Co, Ti, Fe, Cr, Al, At least one of Mo, V, Cu, Nb, Zn, Ca, Mg), (Li ₂ O) z · LiMn _{2 -y} M ² _y O ₄ (0 ≦ y <1, 0 ≦ z <1, M2 is the same as M1, etc.), and Li ₄ Mn ₅ O ₁₂ in which w = 0 is particularly preferable.
Examples of the lithium iron phosphate compound include LiFe _1-p M ⁴ _p PO ₄ (0 ≦ p ≦ 1, M4 is at least one of Mn, Ni, Co, Ti, Al, Cr, V, and Nb), Li ₃ Fe _{2 -q} M ⁵ _q (PO ₄ ) ₃ (0 ≦ q ≦ 1, M5 is the same as M4) and the like, among which LiFePO ₄ is preferable.
Lico _1-r M ⁶ _r O ₂ (0 ≦ r <1, M6 is Mn, Ti, Fe, Cr, Al, Mo, V, Cu, Nb, Zn, Ca, Mg as lithium cobaltate compounds At least one kind), and LiCoO ₂ is particularly preferable.
LiNi _1-s M ⁷ _s O ₂ (0 ≦ s <1, M7 is Mn, Co, Ti, Fe, Cr, Al, Mo, V, Cu, Nb, Zn, Ca, Mg Among them, LiNiO ₂ is preferable.
As the positive electrode active material, for example, one of the above may be used alone, or two or more may be used in combination.

Here, when using a granular positive electrode active material, the average particle diameter (D50) is preferably 0.1 to 100 μm, and more preferably 1 to 10 μm, for example, in the case of molybdenum oxide.
Moreover, in the case of lithium manganese oxide, 0.1-100 micrometers is preferable and 10-50 micrometers is more preferable.
Moreover, in the case of a lithium iron phosphate compound, 0.001-1 micrometer is preferable and 0.01-0.1 micrometer is more preferable.
When the particle diameter (D50) of the positive electrode active material is less than the lower limit value of the above preferable range, the reactivity increases during reflow treatment, which makes it difficult to handle, and when the upper limit value is exceeded, the discharge rate may decrease. .
In the present invention, the “particle diameter of positive electrode active material (D50)” is a particle diameter measured using a laser diffraction method and means a median diameter.

  The content of the positive electrode active material in the positive electrode 30 is determined in consideration of the discharge capacity required for the nonaqueous electrolyte secondary battery 1, and is preferably 50 to 95 mass%, more preferably 70 to 88 mass%. If the content of the positive electrode active material is not less than the lower limit value of the above preferable range, a sufficient discharge capacity can be easily obtained, and if it is not more than the preferable upper limit value, the positive electrode 30 can be easily formed.

The positive electrode 30 may contain a conductive auxiliary (hereinafter, the conductive auxiliary used for the positive electrode 30 may be referred to as a “positive electrode conductive auxiliary”).
Examples of the positive electrode conductive assistant include carbonaceous materials such as furnace black, ketjen black, acetylene black, and graphite.
As the positive electrode conductive assistant, one of the above may be used alone, or two or more may be used in combination.
Moreover, 4-40 mass% is preferable and, as for content of the positive electrode conductive support agent in the positive electrode 30, 10-25 mass% is more preferable. If the content of the positive electrode active material is not less than the lower limit of the above preferred range, sufficient conductivity can be easily obtained. In addition, it becomes easier to form the electrode when it is formed into a pellet. On the other hand, if the content of the positive electrode conductive additive in the positive electrode 30 is not more than the upper limit of the above preferred range, a sufficient discharge capacity can be easily obtained for the positive electrode 30.

The positive electrode 30 may contain a binder (hereinafter, the binder used for the positive electrode 30 may be referred to as a “positive electrode binder”).
As the positive electrode binder, conventionally known materials can be used. For example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), polyacrylic acid (PA), carboxymethyl cellulose (CMC) ), Polyvinyl alcohol (PVA) and the like, among which polyvinylidene fluoride (PVDF) and its compound (copolymer) (PVDF-HFP) are more preferable. In particular, polyvinylidene fluoride (PVDF) and compound (PVDF-HFP) synthesized by emulsion polymerization can use water without using NMP as a solvent for the binder, thereby reducing environmental burdens and running costs. From the viewpoint, it is more preferable.
As the positive electrode binder, one of the above may be used alone, or two or more may be used in combination.
Content of the positive electrode binder in the positive electrode 30 can be 1-20 mass%, for example.

The size of the positive electrode 30, that is, the size after the spirally-structured electrode body 10 is formed by winding a film having a laminate structure in which the positive electrode body 3, the negative electrode body 4, and the separator 5 are laminated is as follows. It is determined according to the size of the secondary battery 1.
Also, the thickness of the positive electrode 30 is determined according to the size of the non-aqueous electrolyte secondary battery 1 as described above, and if the non-aqueous electrolyte secondary battery 1 is of a laminate type for small electronic devices, For example, in the case of a film type or coin type of about 10 to 500 μm, for example, it is about 300 to 1000 μm.

The positive electrode 30 can be manufactured by a conventionally known manufacturing method.
For example, as a method for producing the positive electrode 30, a positive electrode active material and, if necessary, a positive electrode conductive additive and / or a positive electrode binder are mixed to form a positive electrode mixture. The method of shape | molding in arbitrary shapes is mentioned. For example, it can be formed by mixing an arbitrary solvent and a positive electrode mixture to prepare a slurry, applying the slurry to the positive electrode current collector 31 and drying it, followed by compression molding.

Moreover, it does not specifically limit as the positive electrode electrical power collector 31, A conventionally well-known thing can be used. For example, an aluminum foil made of an aluminum alloy or pure aluminum can be used.
Furthermore, it is desirable that the aluminum foil has been processed to increase its specific surface area, such as mechanical processing such as sandblasting, or processing using chemical methods using chemicals such as acids and alkalis. It is desirable to carry out in advance.

(Negative electrode)
As the negative electrode 40, in addition to the negative electrode active material of the present invention, conventionally known conductive assistants, binders and the like can be used.
First, the negative electrode active material of the present invention comprises at least a Si element and is made of a material that can reversibly insert and desorb alkali metal or alkaline earth metal ions, and further includes a first additive element shown below. Fine particles formed by adding one or both of M and the second additive element R at a mass ratio of 1 ppm or more and 20% or less with respect to the total amount of Si element contained in the negative electrode active material, respectively. It is. The first additive element M is composed of at least one element of B or P. The second additive element R is made of at least one element selected from the group consisting of In, Sn, Ti, Al, Ge, C, and Zr.

  Here, the alkali metal or alkaline earth metal ions described in the present invention are solvated with the supporting salt in the electrolyte containing the supporting salt and the non-aqueous solvent, that is, the non-aqueous organic solvent in which the supporting salt is dissolved. It is desirable that the ability is high, the ion radius is relatively small, and in particular, the ion mobility is high at room temperature. Furthermore, in view of these, elements that are highly safe for the human body are desirable for industrial production. Therefore, Li ions or Na ions are preferable for alkali metal ions, and Mg ions are preferable for alkaline earth metal ions. Is preferred.

Moreover, the negative electrode active material used for the negative electrode 40 is a substance in which ions can be reversibly inserted and desorbed as an element containing the above ions, and is made of a compound containing at least a Si element.
Here, the general formula of the negative electrode active material containing Si (silicon) is represented by a composition formula {A _x SiO _y M _z }, in which the element A is a cation species, an alkali metal ion or an alkaline earth metal. X is the content x of the ionic species of the element A and takes the value of the following formula {0 ≦ x ≦ 4.4}, and the oxygen amount y is the following formula {0 ≦ y ≦ 2}.
The element M in the above formula is at least one of B and P as the first additive element M, and when the first additive element M is included, it is contained in the negative electrode active material. It is contained in a mass ratio of 1 ppm or more and 20% or less with respect to the total amount of Si element.

In the present invention, as the second additive element R, at least one element selected from the group of In, Sn, Ti, Al, Ge, C, and Zr can be added. Even when the second additive element R is contained, as in the case of the first additive element M, the mass ratio is 1 ppm or more and 20% or less with respect to the total amount of the Si element contained in the negative electrode active material. It is included. Such a second additive element R can be added not only as a metal element in the negative electrode active material but also in the form of an oxide or a nitride thereof, for example.
Further, the Si element forming the negative electrode active material and the second additive element R, In, Sn, Ti, Al, Ge, and C, are fine particles in a state where at least a part of the surface thereof is carbonized. good.

Furthermore, the negative electrode active material represented by the composition formula {A _x SiO _y M _z } is not a complete compound, but may be, for example, a composite (matrix) formed as an aggregate of fine particles. Furthermore, the negative electrode active material represented by the compositional formula {A _x SiO _y M _z } is obtained by adding an A element as a cation species to the SiO _y M _z that is a precursor, electrochemically or chemically. In particular, it is preferable to insert the cation species: element A using an electrochemical method.

In the nonaqueous electrolyte secondary battery 1 of the present embodiment, first, the first additive element M is added to the negative electrode active material forming the negative electrode 40, so that the negative electrode active material is stably present in an amorphous state. It becomes like this. This makes it possible to suppress the occurrence of cracks due to volume expansion / contraction that occurs in the negative electrode when the insertion and desorption of alkali metal ions such as lithium are repeated by charging and discharging the electrochemical cell.
In addition, since the second additive element R is added to the negative electrode active material so that the negative electrode active material is stably present in an amorphous state, alkali metal ions such as lithium can be charged and discharged by the electrochemical cell. When the insertion and the detachment are repeated, the electron conductivity in the negative electrode active material is increased, and the charge uniformity in the negative electrode active material is improved. Thereby, it is possible to prevent the occurrence of cracks by preventing the bias at the time of insertion of alkali metal ions and by preventing the localization of volume expansion and contraction.

Here, SiO _y M _z which is a precursor of the negative electrode active material represented by the composition formula {A x _SiO y _{M z}} may form a secondary particle which is an aggregate by the primary particles Furthermore, the secondary particles may be formed in a state in which one or both of the first additive element M and the second additive element R are added.

  The particle size of the negative electrode active material is preferably 1 nm or more and 50 μm or less in terms of average particle diameter. The average particle size of the negative electrode active material is more preferably 20 μm or less, and particularly preferably in the range of 1 nm to 2 μm. When the average particle diameter of the negative electrode active material is in the above range, the effect of suppressing cracks in the negative electrode 40 at the time of volume expansion / contraction that occurs in the negative electrode during charge / discharge of the battery is remarkably obtained.

Moreover, as a form of a negative electrode active material, it is preferable that it consists of secondary particles with an average particle diameter of 0.1 micrometer or more and 100 micrometers or less formed by aggregating primary particles with an average particle diameter of 1 nm or more and 50 micrometers or less.
Furthermore, the form of the negative electrode active material is more preferably composed of secondary particles having an average particle diameter of 0.5 μm or more and 4 μm or less, which is a collection of primary particles having an average particle diameter of 1 nm or more and 2 μm or less.
Furthermore, in the secondary particles of the negative electrode active material, 85% or more of the total volume is preferably primary particles having an average particle diameter of 1 nm or more and 8 μm or less, and 90% or more of the total volume is 1 nm or more and 2 μm of average particle diameter. The following primary particles are more preferable.

  In addition, when the average particle diameter of the negative electrode active material is less than 1 nm, for example, reactivity due to reflow treatment or heating during use of the nonaqueous electrolyte secondary battery 1 may increase, and battery characteristics may be impaired. Moreover, when the average particle diameter of the negative electrode active material exceeds 50 μm, the discharge rate may be reduced.

The content of the negative electrode active material in the negative electrode 40, that is, the Si element or the compound containing Si element such as SiO _x is determined in consideration of the discharge capacity required for the non-aqueous electrolyte secondary battery 1, 50 mass% or more is preferable and 60-70 mass% is more preferable.
In the negative electrode 40, if the content of the negative electrode active material composed of the above elements is not less than the lower limit value of the above preferable range, sufficient discharge capacity is easily obtained, and if the content is not more than the upper limit value, the negative electrode 40 is formed. There is a merit that it is easy.

  The amount of the first additive element M or the second additive element R added to the negative electrode active material is 1 ppm in terms of mass ratio with respect to the total amount of Si element contained in the negative electrode active material. More preferably, it is 1% or less. By further limiting the amount of each additive element added to the negative electrode active material to the above range, the effect of suppressing the occurrence of cracks due to volume expansion / contraction that occurs in the negative electrode during charge / discharge of the electrochemical cell is more effective. Remarkably obtained.

In the present invention, the negative electrode active material forming the negative electrode 40 is made of an Si element oxide: SiO _x (0 <x <2), and the second additive element R is In and / or Sn. You may employ | adopt the structure which is an oxide.
Thus, when the negative electrode active material is made of an oxide containing an Si element, the non-uniformity of elements during the synthesis of the negative electrode active material can be reduced. As a result, when the insertion and desorption of alkali metal ions such as lithium are repeated by charging and discharging the electrochemical cell, the electron conductivity in the negative electrode active material is enhanced, and the homogeneity of the charge in the negative electrode active material is improved. Can do. Therefore, it is possible to suppress the occurrence of cracks in the negative electrode 40 by preventing the bias at the time of insertion of the alkali metal ions and preventing the localization of volume expansion and contraction.

In the present invention, the second additive element R added to the negative electrode active material can adopt a configuration in which the mixing ratio of In and Sn is 1: 9 by mass ratio.
By setting the second additive element R to the above blending ratio, the negative electrode active material is more stably present in an amorphous state. As a result, when the insertion and desorption of alkali metal ions such as lithium are repeated by charging and discharging the electrochemical cell, the electron conductivity in the negative electrode active material is increased, and the charge homogeneity in the negative electrode active material is improved. Therefore, it is possible to suppress the occurrence of cracks in the negative electrode 40 by preventing the bias at the time of insertion of the alkali metal ions and preventing the localization of volume expansion and contraction.

Further, in the present invention, the negative electrode 40 contains a carbon material for imparting electronic conductivity in addition to the negative electrode active material, and the carbon material is a carbon tube or a carbon product. A configuration including at least one of sheets (graphene) can be employed.
As described above, when the negative electrode 40 includes the above carbon material, when the insertion and desorption of alkali metal ions such as lithium are repeatedly performed by charging and discharging the electrochemical cell, the entire surface around the negative electrode active material particles has electron conductivity. The electron conductivity of the negative electrode active material particles is improved. As a result, it is possible to prevent the negative electrode 40 from being cracked by preventing the bias at the time of insertion of alkali metal ions in the thickness direction and the horizontal direction in the electrode layer of the negative electrode 40 and by preventing the localization of volume expansion and contraction. Can be suppressed.

The negative electrode 40 may contain a conductive auxiliary (hereinafter, the conductive auxiliary used for the negative electrode 40 may be referred to as “negative electrode conductive auxiliary”). The negative electrode conductive auxiliary is the same as the positive electrode conductive auxiliary.
The negative electrode 40 may contain a binder (hereinafter, the binder used for the negative electrode 40 may be referred to as a “negative electrode binder”).
Examples of the negative electrode binder include polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), polyacrylic acid (PA), carboxymethyl cellulose (CMC), polyimide (PI), and polyimide amide (PAI). Acrylic acid (PA) and polyimide (PI) are preferable, and cross-linked polyacrylic acid is more preferable. Moreover, the material which neutralized polyacrylic acid is preferable.
As the negative electrode binder, one of the above may be used alone, or two or more may be used in combination. In addition, when using polyacrylic acid for a negative electrode binder, it is preferable to adjust polyacrylic acid to pH 3-10 previously. For adjusting the pH in this case, for example, an alkali metal hydroxide such as lithium hydroxide or an alkaline earth metal hydroxide such as magnesium hydroxide can be used.
When polyimide (PI) or polyimide amide (PAI) is used for the negative electrode binder, it is desirable to dry the raw materials in advance at a temperature of 60 ° C. or higher and to mix the raw materials in a dry manner.
The content of the negative electrode binder in the negative electrode 40 is, for example, 1 to 20% by mass.

The negative electrode 40 can be manufactured by a conventionally known manufacturing method.
For example, as a manufacturing method of the negative electrode 40, a negative electrode active material and, if necessary, a negative electrode conductive additive and / or a negative electrode binder are mixed to form a negative electrode mixture. The method of shape | molding in arbitrary shapes is mentioned. For example, it can be formed by mixing an arbitrary solvent and a negative electrode mixture to prepare a slurry, applying the slurry to the negative electrode current collector 41 and drying, followed by compression molding. However, when PI or PAI is used for the binder, it is desirable to use a drying chamber in which the humidity is controlled to 5% RH or less, more preferably 1% RH or less, in the mixing process of the raw materials dried in advance. . Moreover, it is good to use NMP which performed the dehydration process to 100 ppm or less as a dispersion medium.

Moreover, as a method of apply | coating an electrode mixture on the negative electrode collector 41, it can select suitably from the method shown below. Examples include spin coating method, doctor blade method, reverse roll method, direct roll method, dipping method, squeeze method, extrusion method, curtain method, bar method, knife method, etc. It is not limited.
The coat thickness, length and width are determined by the size of the electrochemical cell, and the coat thickness is particularly preferably 1 to 200 μm in a compressed state after drying.

In addition, as a sheet pressing method, a conventionally employed method can be used, and a mold pressing method and a calendar pressing method are particularly preferable. Although it does not specifically limit as a press pressure in this case, 0.2-3 t / cm < ² > is preferable. Moreover, the press speed of the calendar press method is preferably 0.1 to 50 m / min. Furthermore, the press temperature at this time is preferably room temperature to 200 ° C.
The negative electrode 40 can be disposed on the negative electrode current collector 41 by the process as described above.

  By adopting the negative electrode 40 having the above-described configuration, it is possible to suppress cracks from being generated in the negative electrode due to volume expansion / contraction during charge / discharge, and it is possible to suppress an increase in internal resistance and capacity deterioration, thereby providing high reliability and high capacity. In addition, the nonaqueous electrolyte secondary battery 1 having excellent cycle life characteristics can be realized.

  The size and thickness of the negative electrode 40 are determined according to the size of the non-aqueous electrolyte secondary battery 1 as in the case of the positive electrode 30, and the non-aqueous electrolyte secondary battery 1 is a laminate type for small electronic devices. If it is, for example, if it is a film type of about 10-500 micrometers, and a coin type thing, it will be about 300-1000 micrometers, for example.

As the negative electrode current collector 41, for example, a copper foil made of a copper alloy or pure copper can be used. In particular, SUS foil is preferably used, and SUS304, SUS316, etc. having a thickness of 10 μm or less are preferable. When SUS foil is used for the negative electrode current collector 41, it is desirable to perform a pretreatment for increasing the surface area with a sandblast or a roll. At this time, the effect of increasing the surface area and the anchor effect of the binder can prevent the active material from being detached due to the volume change due to the expansion and contraction of the electrode active material due to charge and discharge.
Further, this pretreatment may use a chemical method or a mechanical method. In the case of using a chemical technique, for example, by performing chemical etching on the surface of the SUS foil, the anchor effect can be exhibited and the electrode active material can be strongly fixed to the surface of the SUS foil. Thereby, since an increase in internal resistance and capacity deterioration can be suppressed, the nonaqueous electrolyte secondary battery 1 having high reliability, high capacity, and excellent cycle life characteristics can be realized.

(Electrolyte)
The electrolytic solution (not shown) is obtained by dissolving a supporting salt in a non-aqueous solvent.
As the supporting salt, a known substance used as a supporting salt in the electrolyte solution of the nonaqueous electrolyte secondary battery can be used. For example, LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , Organic acid lithium salts such as LiN (C ₂ F ₅ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiN (CF ₃ SO ₃ ) ₂ , LiN (FSO ₂ ) ₂ ; LiPF ₆ , LiBF ₄ , LiB ( Examples thereof include lithium salts such as inorganic acid lithium salts such as C ₆ H ₅ ) ₄ , LiCl and LiBr. Among them, a lithium salt that is a compound having lithium ion conductivity is preferable, and it is more preferable to use LiPF ₆ , LiN (CF ₃ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , LiBF ₄ alone or in a mixed state. .
As the supporting salt, one of the above may be used alone, or two or more may be used in combination.

  The non-aqueous solvent is determined in consideration of the heat resistance and viscosity required for the electrolytic solution. For example, formic acid esters such as ethyl formate, propyl formate and n-propyl formate; propionic acid such as methyl propionate and ethyl propionate Esters; Aliphatic monocarboxylic acid esters such as butyric acid esters such as methyl butyrate and ethyl butyrate; Chain carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate; Ethylene carbonate (EC), Propylene carbonate (PC), 1, 2 -Cyclic carbonates such as butylene carbonate (BC) and vinylene carbonate (VC); chain sulfones such as dimethyl sulfone and ethyl methyl sulfone; glycol ethers such as tetraethylene glycol dimethyl ether and ethylene glycol diethyl ether Sulfolane (SL), γ-butyrolactone (GBL), 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE), 1,2-ethoxymethoxyethane (EME), tetrahydrofuran (THF), 1 , 3-dioxolane (DOL) and the like.

  The content of the supporting salt in the electrolytic solution can be determined in consideration of the type of the supporting salt, etc., for example, preferably 0.1 to 3.5 mol / L, more preferably 0.5 to 3 mol / L, 2.5 mol / L is particularly preferable. Even if the supporting salt concentration in the electrolytic solution is too high or too low, the conductivity is lowered, which may adversely affect the battery characteristics.

(Separator)
The separator 5 is interposed between the positive electrode 30 and the negative electrode 40, and an insulating film having high ion permeability and mechanical strength is used.
As the separator 5, a film-like material conventionally used for a separator of a non-aqueous electrolyte secondary battery can be applied without any limitation, and as a laminate-type electrochemical cell, pores are blocked by heating due to abnormality of the electrochemical cell. Olefin such as polyethylene and polypropylene having a shutdown function due to the above, polyamide, or polyethylene / polypropylene composite membrane. In the button type, for example, glass such as alkali glass, borosilicate glass, quartz glass, lead glass, polyphenylene sulfide (PPS), polyetheretherketone (PEEK), polyethylene terephthalate (PET), polyamideimide (PAI), Nonwoven fabric made of a resin such as polyamide or polyimide (PI) can be used. Furthermore, pseudo polymers such as PVdF-HFP, EO (ethylene oxide), PO (polyethylene oxide), copolymers thereof, and gels such as polyacrylonitrile can be used.
The thickness of the separator 5 is determined in consideration of the size of the nonaqueous electrolyte secondary battery 1, the material of the separator 5, and the like, like the positive electrode 30 and the negative electrode 40, and can be set to 5 to 300 μm, for example.

  In the present embodiment, the nonaqueous electrolyte secondary battery having a laminate type structure as shown in FIGS. 1A to 1C has been described as an example, but the present invention is limited to this. It is not a thing. For example, a non-aqueous electrolyte secondary having a button-type structure or a structure in which the opening of a ceramic container body is sealed with a ceramic lid by heat treatment such as seam welding using a metal sealing member It may be a battery.

As described above, according to the non-aqueous electrolyte secondary battery (electric double layer capacitor) 1 of the present embodiment, the negative electrode active material used for the negative electrode 40 contains at least Si element, and an alkali metal or alkaline earth metal. Of the first additive element M {at least one of B or P} or the second additive element R {In, Sn, Ti. , One or both of at least one element selected from the group consisting of Al, Ge, C, and Zr} is 1 ppm or more by mass ratio with respect to the total amount of Si element contained in the negative electrode active material, respectively. The structure which is a fine particle added at 20% or less is adopted.
Thereby, it can suppress that a negative electrode cracks by the volume expansion / contraction at the time of charging / discharging, and it becomes possible to suppress a raise of internal resistance and capacity | capacitance degradation.
Therefore, it is possible to provide the nonaqueous electrolyte secondary battery 1 having high reliability, high capacity, and excellent cycle life characteristics.

"Production method"
Next, the manufacturing method of the nonaqueous electrolyte secondary battery (electric double layer capacitor) which is the electrochemical cell of this invention is demonstrated, referring FIGS.
A method for manufacturing a non-aqueous electrolyte secondary battery, which is a preferred aspect of the present embodiment, is a method for manufacturing a laminate-type non-aqueous electrolyte secondary battery 1 as shown in FIGS.
First, as shown in FIG. 1C, a separator 5 is provided between a positive electrode body 3 in which the positive electrode 30 is formed on the surface of the positive electrode current collector 31 and a negative electrode body 4 in which the negative electrode 40 is formed on the surface of the negative electrode current collector 41. And the electrode body 10 is produced. And as shown to Fig.1 (a), the electrode body 10 is loaded into the exterior body 2 in which the concave accommodating parts 21a and 22a were formed previously. Then, electrolyte solution is inject | poured and the exterior body 2 is sealed after internal defoaming.

Next, based on FIG. 2, the negative electrode active material and the negative electrode 40 which are embodiment of the electrochemical cell of this invention are demonstrated.
First, a method for producing the negative electrode active material A _x SiO _y M _z + R used for the negative electrode 40 will be briefly described. Further, as materials to be used, Si-containing material, silicon oxide (SiO), first additive element M, second additive element R, element A of alkali metal ions or alkaline earth metal ions are used. Details will be described later.

First, the Si-containing material as a raw material is pulverized and refined (Si refinement process).
Next, a first additional element M and high-purity silicon oxide was added to and mixed with the Si-containing compound which is miniaturized, to synthesize the _{SiO y M z (SiO y M} z synthesis step).
Next, a stabilization process is performed on the synthesized SiO _y M _z using the second additive element R. Since the stabilization process will be described in detail later, the description is omitted here. By this step, SiOyMz + R fine particles are purified.
Next, an alkali metal ion such as Li, Na, K or the like, or an alkaline earth metal ion element A is used to insert the alkali metal ion into the SiO _y M _z + R fine particles, thereby producing A _x SiO _y M _z + R. (Alkali metal ion insertion step).
Moreover, it is preferable to form the negative electrode 40 in an arbitrary shape using SiO _y M _z + R fine particles before insertion of alkali metal ions.
Then, each process is explained in full detail.

Si-containing compounds, which are one of the materials of the negative electrode active material A _x SiO _y M _z + R, can be classified into semiconductor grades with high Si purity and solar cell grades equivalent to them according to their Si purity. In detail, it can be classified into (K-1) to (K-5) shown below.

(K-1) Using metal silicon (Si) with a purity of 99.9999999999% or more synthesized by the Siemens method, and when the metal silicon is columnar or massive, after processing into a plate (wafer), B (boron) or P (phosphorus) is added as a dopant. In this case, the metal silicon is crystalline silicon (microcrystalline silicon, polycrystalline silicon), amorphous silicon, or a mixture of both.
(K-2) Using metal silicon having a purity of 99.99% or more synthesized by any of the fluidized bed method, metallurgical method, zinc reduction method, water vitrification method, tube furnace method, and melt precipitation method, When metallic silicon is columnar or massive, it is processed into a plate shape and then B (boron) or P (phosphorus) is added as a dopant. At this time, the metallic silicon is crystalline silicon (microcrystalline silicon, polycrystalline silicon), amorphous silicon, or a mixture of both.
(K-3) Silicon having a purity of 96% or more obtained by reducing silicon dioxide using an arc furnace using a carbon electrode, and the total of B (boron) or P (phosphorus) as impurities is 1%. The following is crystalline silicon (microcrystalline silicon, polycrystalline silicon) or amorphous silicon.
(K-4) Silicon powder obtained by collecting cutting wastes such as ingots and wafers produced in the manufacturing process of photovoltaic cell wafers or semiconductors, cutting residue, sludge from wastewater discharged from chips, cutting devices, and the like.
(K-5) Remove the antireflection film from the used solar cell, grind the photovoltaic cell holding the front and back electrodes to 1 mm or less, and further remove the coarse powder mixture by removing the metal component by acid treatment, Silicon powder in micronized state.

In addition, the Si-containing product obtained in the above (K-1) to (K-5) is combined with any of the methods (B-1) to (B-12) shown below, and is a coarse crushing step. It can manufacture by using the manufacturing process which micronizes through (Si refinement | miniaturization process).
In addition, using fine particles of titanium or copper prepared in advance by the plasma atomization method, or metal fibers (including nano-sized fibers) as the core, a fluidized bed method is used to produce fine metal powders and metals. It is also possible to obtain a Si-containing material in which the surface of the fiber is coated with silicon fine powder.

  For example, in addition to atomization methods such as (B-1) gas atomization method, (B-2) water atomization method, (B-3) centrifugal force atomization method, (B-4) plasma atomization method, etc. (B-5) Rotating Electrode Process (REP method) using high temperature plasma, (B-6) Stamp mill, (B-7) Ball mill, (B-8) Jet mill, (B-9) ) Attritor, (B-10) Bead mill, (B-11) Roll crusher, (B-12) Planetary stirrer can be used in combination.

  In the pulverization, the above-mentioned (B-6) stamp mill, (B-7) ball mill, (B-8) jet mill, (B-9) attritor, (B-10) bead mill, (B-11) ) In the roll crusher, oxidation of the Si-containing compound can be suppressed by performing the pulverization step in an inert gas atmosphere. In particular, in (B-8) jet mill and (B-9) attritor, it is preferable to use an inert gas as a carrier gas. As such an inert gas species, for example, nitrogen gas or argon gas can be used. In consideration of production quality, argon gas is most preferable. Further, in the (B-7) ball mill and (B-10) bead mill, it is desirable to perform crushing and crushing in a wet process using a solvent in addition to dry crushing and crushing performed in an inert gas atmosphere. At this time, water or an organic solvent can be used as the solvent, but it is preferable to use an organic solvent from the viewpoint of improving the grinding efficiency. As such an organic solvent, for example, a low molecular weight organic solvent having a low boiling point can be used in addition to a protic polar solvent such as alcohol and an aprotic polar solvent such as ether. Further, as the organic solvent, halogenated organic solvents such as chlorofluorocarbon and defluorocarbon having a low boiling point are more preferable.

In particular, the Si-containing material has a high hardness, and there is a high possibility of contamination from an apparatus used in the pulverization process. For this reason, the (B-6) stamp mill, (B-7) ball mill, (B-8) jet mill, (B-9) attritor, and (B-10) bead mill, which are pulverizers, are hard and electric. It is desirable to use a chemically inert material. Specifically, it is desirable to use alumina (Al ₂ O ₃ ), zirconium oxide (ZnO ₂ ), or the like as an inner surface (also referred to as a lining) of a pulverizer or a medium used for pulverization. In such a pulverization step, it is preferable to use an inert gas atmosphere or a cyclic solvent as the pulverization atmosphere.

Also as part of the material of the anode active material _{A x SiO y M z + R} , it is possible to use a high-purity silicon oxide, as its production method, the following (S-1) ~ (S -3) Either method can be used.
(S-1) Silicon dioxide (SiO ₂ ) obtained by adding an acid to high-purity water glass (NaSiO ₃ ), separating and washing the precipitated gel, firing, dehydrating, and pulverizing.
(S-2) Silicon dioxide obtained by purifying silica gel powder obtained by hydrolysis of tetraalkoxysilane, baking, dehydrating, and pulverizing.
(S-3) Silicon dioxide obtained by chemical vapor deposition (CVD) from a gas of silicon tetrachloride (SiCl ₄ ) and then pulverization.

Next, a detailed method for synthesizing SiO _y M _z is shown in the following (Method-1) to (Method-3) (SiO _{y Mz} synthesizing step).

(Method-1) Si-containing compound and high-purity silicon oxide are mixed in a vapor state by heating in a temperature range of 400 to 1600 ° C. under an inert gas or under reduced pressure, respectively, and generated mixed steam By precipitating and solidifying in a reaction vessel, it is possible to synthesize fine particle SiO _{y Mz} as a precursor.
(Method-2) Si-containing compound and high-purity silicon oxide are sufficiently mixed, and the mixed raw material powder is heated in a temperature range of 400 to 1600 ° C. under an inert gas or under reduced pressure, so that silicon oxide vapor having a non-stoichiometric ratio is obtained. Can be synthesized by precipitating and solidifying fine particle SiO _{y Mz} as a precursor.
(Method-3) An inert gas is made to flow from below the vertical cylinder, and a silicon-containing compound and a high-purity silicon oxide vapor are sprayed into the gas stream, and the two are contact-reacted in the stream. And can be synthesized by precipitation and solidification. In this case, it is preferable that the obtained powder is a fine powder having a desired particle diameter because the pulverization step can be omitted.

In (Method-1) and (Method-2), the Si-containing compound and the high-purity silicon oxide are mixed by a method of directly dry-mixing the powders of the respective raw materials, as well as by adding these raw materials to water. A method of dispersing and mixing alcohol or other solvent can be used.
Specifically, the above (B-6) stamp mill, (B-7) ball mill, (B-8) jet mill, (B-10) bead mill and the like can be appropriately combined and adjusted.
Moreover, as a method for making the synthesized SiO _{y Mz} into fine particles, the above-mentioned methods such as (B-6) stamp mill, (B-7) ball mill, (B-8) jet mill, (B-10) bead mill, etc. Can be used in appropriate combination.

(Method-1) to (Method-3) described above are cases where the value of y of SiO _y M _z is greater than 0. When y = 0, it can be selected not to mix high-purity silicon oxide.
Moreover, when the addition amount of the 1st addition element M is 1 ppm or more and 20% or less by mass ratio with respect to the whole quantity of Si element, it is not necessary to add the 2nd addition element R. Similarly, when the addition amount of the second additive element R is 1 ppm or more and 20% or less by mass ratio with respect to the total amount of Si element, the first additive element R may not be added. .

The specific surface area of the fine particles of the synthesized _SiO y _{M z} is preferably 0.05~1500m ² / g, more preferably 0.1~150m ² / g, particularly preferably 0.1 to 100 m ² / g .

Next, the stabilization process will be described. This stabilization process is a process of forming a conductive film on the surface of SiO _{y Mz} . By forming such a conductive film, SiO _y M _z can stably maintain electrical connection with the conductive additive dispersed in the electrode even when charging and discharging are repeated. This conductive film can be mechanically milled using a ball mill in an oxygen-free atmosphere. Moreover, as this conductive film, In, Sn, Ti, Al, Ge, C, and Zr are particularly preferable.
Further, a dry plating method, a coating method, or the like can be used. As a dry plating method, PVD methods such as thermal spraying, other resistance heating vapor deposition, electron beam vapor deposition, molecular beam epitaxy, ion plating (ion plating), ion beam deposition, and sputtering are used. be able to.

  Here, the following method can be adopted as the stabilization step described above.

(D-1) A method of mixing SiO _{y Mz} , carbon powder, a binder, and a solvent.
(D-2) A method of obtaining a matrix mechanochemically by repeating mixing and pulverization of fine particles of metal titanium or copper and SiO _{y Mz} .
(D-3) SiO _y M _z and a carbon precursor obtained by carbonizing highly crystalline carbon powder by heating are mixed, and the carbon precursor is _{added to} the surface of SiO _y M _z in a reducing atmosphere. A method of coating by thermal decomposition.

  The method shown in the above D-1 will be described in detail. As the carbon, as a starting material, petroleum coke, pitch coke, hydrocarbons such as methane, propane, benzene, acetylene, cellulose, polyacrylotolyl (PAN), pitch system Artificial carbon using fibers or the like can be used. Moreover, what was obtained by thermally decomposing those starting materials at 1200 to 3000 degreeC is preferable, and what was obtained by processing at the graphitization temperature of 2500 to 3000 degreeC is more preferable. Carbon blacks such as furnace black, channel black, thermal black, and lamp black can also be used as starting materials.

  The carbon is particularly preferably a material obtained by pulverizing thermally expanded graphite, and it is preferable to use a carbon material in which the spreading direction of the hexagonal network surface of the carbon element is cylindrical or planar. Specifically, carbon nanofibers, carbon nanotubes, and graphene can be used alone or as a mixture of a plurality of types.

In addition, when increasing the conductivity by adding a conventionally known carbon material to SiO _y M _z , it is necessary to increase the rate of addition in the electrode because the particle shape is close to a sphere, but in this case Since the energy density may decrease, it is preferable to use a carbon material having a large aspect ratio (length / diameter or plane / thickness). Therefore, although use for the purpose of imparting conductivity to the SiO _y M _z carbon material is more preferable are those having a large aspect ratio. Such a carbon material may be a single-wall SWCNT (single-walled carbon nanotube) or a multi-walled MWCNT (multi-walled carbon nanotube), for example, having a diameter of 5 nm to 20 nm and a length of 5 to 10 μm. A carbon tube or carbon fiber having an equivalent diameter and a sub-mm length can be used. However, even if a carbon material having a high aspect ratio is used, if the mixing ratio of these carbon fibers is increased, the molding density at the time of forming an electrode by compression molding or rolling tends not to be increased. Therefore, it is desirable that the content of carbon nanofibers, carbon nanotubes, graphene, and the like be suppressed to less than 7 wt% with respect to the mixture mass.

  Here, carbon nanofibers and carbon nanotubes can be synthesized using each method such as arc discharge, laser ablation, CVD method (chemical vapor deposition method), for example, vapor phase growth manufactured by Showa Denko KK Carbon fiber (VGCF) or the like can be used. As the above-described CVD method, in addition to a substrate method such as an alcohol CVD method or an SG-CVD method, a gas layer flow method such as a DIPS method, a CoMoCAT method, a HiPCO method, or a super growth CVD method can be used.

Graphene can be obtained by a method such as a CVD method, a production method by sublimation of a single crystal of SiC, or a peeling method (including physical peeling, chemical peeling, or a combination thereof). In particular, when the CVD method is used, a nano-sized nano-size obtained by covering the surface of SiO _y M _z with an organometallic compound (for example, ferrocene) containing a metal element as a catalyst in advance and decomposing and generating by heat or light. In a fluidized bed heated to 350 ° C. or more and less than 1500 ° C. while flowing a high-concentration hydrocarbon stream upward from the bottom vertically, using the particles formed with the catalyst particles fixed to the surface as seeds Can be carbonized. At this time, in particular, by converting the hydrocarbon into plasma, it is possible to generate the hydrocarbon at a low temperature of 800 ° C. or less. At this temperature, silicon and silicon dioxide can be formed inside the SiO _y M _z as a precursor. Disproportionation can be suppressed, and a negative electrode active material suitable for large current characteristics can be synthesized. Moreover, the transition metal species remaining as a catalyst after coating with carbon can be removed by pickling treatment.

  Moreover, it is desirable to improve the affinity with the electrolytic solution and the binder by chemically modifying the surface of the carbon material. In this case, for example, the wettability of the electrolytic solution with the solvent is improved by treating the surface with a strong acid and adding a carbonyl group. As a result, the rate of impregnation of the electrolyte into the negative electrode when assembling the electrochemical cell is increased, and the effect of shortening the manufacturing time and improving the adhesion with the binder can be obtained. The effect of maintaining the electronic connection when the expansion and contraction of the film occurs can be expected.

Next, a method of inserting an alkali metal ion into SiO _y M _z + R that has undergone the stabilization process will be described below. (Alkali Metal Ion Insertion Step) Hereinafter, the case where lithium is used as the alkali metal element A will be described as an example.

Specifically, a method of immersing SiO _y M _z + R in a high-purity nonpolar organic solvent in which high-concentration alkyl lithium is dissolved can be employed. At this time, the concentration of the alkyl lithium can be 1 mol / L or more. As the alkyl lithium, for example, n-butyl lithium, 2-butyl lithium, t-butyl lithium or the like can be used. Moreover, as a high purity nonpolar organic solvent, for example, at least one of an n-pentane solution, an n-hexane solution, an n-heptane solution, an n-octane solution, an n-nonatan solution, an n-nonatan solution, etc. You can choose from one type. Further, the immersion time at this time depends on the particle diameter of SiOyMz + R, but is preferably immersed for at least 2 hours, more preferably 12 hours or more. However, when the immersion time at this time is 144 hours or longer, an equilibrium state is obtained. Therefore, the immersion effect does not change even if the immersion is performed for a longer time.

Further, as a method of inserting alkali metal ions into SiO _y M _z + R, it is desirable to perform the above pulverization step and also the pulverization step in a ball mill. At this time, since the organic solvent has a low surface tension and the dispersibility of the pulverized body is higher than that of water, the surface of the powder becomes hard and brittle by inserting alkali metal ions, and at the same time the pulverization efficiency is improved. It becomes possible to obtain a fine powder.

As a method of obtaining a negative electrode active material _{A x SiO y M z + R} , the previous _SiO y _M z + R, a method of inserting a alkali metal ions may be employed using techniques by catalytic reaction.
Specifically, the fine particles or the metal lithium foil of the metal lithium, to keep the state of being physically contacting the SiO y M _z + _R, can be diffused lithium ion state SiO y M _z + _R It is. In this case, the mechanism may be the same as that of the local battery. In that case, it is desirable that an electrolyte be present between SiO _y M _z + R and lithium metal in order to promote the reaction. In this case, the electrolyte may be liquid, but may be a solid electrolyte or a polymer electrolyte. When the electronic conductivity of SiO _y M _z + R is poor, a decomposition product obtained by reducing and decomposing a part of the electrolyte may form a film that inhibits lithium ion diffusion on the surface of SiO _y M _z + R. It is desirable to give electron conductivity to SiO _y M _z + R in advance. Details of the method for imparting such electron conductivity will be described later.
Moreover, you may implement the insertion of the alkali metal ion by a contact reaction demonstrated by this invention, after forming the negative electrode sheet mentioned later. Moreover, since the insertion method of the alkali metal ion by such a contact reaction is implemented before an electrochemical cell is assembled, it can be called pre-doping.

Further, as a method of obtaining a negative electrode active material _{A x SiO y M z + R} , the previous _SiO y _M z + R, it is also possible to adopt a method of inserting the alkali metal ions using electrochemical techniques.
Such an electrochemical method can be performed in the electrochemical cell after the electrochemical cell is assembled or in the electrochemical cell or outside the electrochemical cell in the course of the electrochemical cell manufacturing process. ) To (3) can be exemplified.

(1) One electrode (working electrode) is formed by mixing a mixture of SiO _y M _z + R, a conductive agent, a binder, and the like into a predetermined shape, and metallic lithium or a substance containing lithium is used as the other electrode (counter electrode) as), it is opposed to the electrodes in contact with the non-aqueous electrolyte of a lithium ion conductivity to constitute an electrochemical cell, energized with a suitable electric current in the direction the working electrode is the cathode reaction, the previous working electrode SiO _y by inserting the lithium ions M _z + R, a method of obtaining a negative electrode active material _{a x SiO y M z + R} .
(2) A mixture of SiO _y M _z + R, a conductive agent, a binder, and the like is formed into a predetermined shape, and lithium or a lithium alloy or the like is pressed or brought into contact with the laminated electrode as a negative electrode. Built into water electrolyte secondary battery. Then, this laminated electrode forms a kind of local battery by touching the electrolyte in the electrochemical cell, and the lithium is electrochemically occluded in SiO _y M _z + R by self-discharge, so that the negative electrode active method for obtaining a substance _{a x SiO y M z + R} .
(3) A non-aqueous electrolyte secondary battery using SiO _y M _z + R as a negative electrode active material and a material containing lithium and capable of occluding and releasing lithium ions as a positive electrode active material is configured. Then, by performing charging before use as an electrochemical cell, lithium ions released from the positive electrode are occluded in SiO _y M _z + R serving as a precursor of the negative electrode, so that the negative electrode active material A _x SiO _y M _z + R How to get.

The negative electrode active material A _x SiO _y M _z + R can be obtained by the methods shown in the above (1) to (3). In addition, when the electrochemical method is used, when reversibly inserting / desorbing lithium ions present in the positive electrode are transferred from the positive electrode to the negative electrode, the electrochemical cell is assembled in an assembled electrochemical cell. It may be a method of obtaining a negative electrode active material _a x _SiO y _M z + R to.

Thus, the nonaqueous electrolyte secondary battery 1 of the present invention can be manufactured through the Si refinement process, the SiO _{y Mz} synthesis process, the stabilization process, and the alkali metal ion insertion process.
According to the manufacturing method of this embodiment, since the negative electrode active material can be stably present in an amorphous state by adding the first additive element M to the negative electrode active material, charging and discharging of the electrochemical cell The nonaqueous electrolyte secondary battery 1 capable of suppressing the occurrence of cracks due to the volume expansion / contraction that sometimes occurs in the negative electrode 40 can be manufactured.
Further, by adding the second additive element R to the negative electrode active material, the negative electrode active material can be stably present in an amorphous state. Therefore, during charging / discharging of the electrochemical cell, Electron conductivity is enhanced, it is possible to improve the homogeneity of the charge in the negative electrode active material, it is possible to prevent localization of volume expansion and contraction of the negative electrode 40 due to the bias when inserting alkali metal ions, and cracks The nonaqueous electrolyte secondary battery 1 capable of suppressing the generation can be manufactured.

  The nonaqueous electrolyte secondary battery (electric double layer capacitor) 1 of the present embodiment is obtained by the procedure as described above.

According to the manufacturing method of this embodiment, since the negative electrode active material can be stably present in an amorphous state by adding the first additive element M to the negative electrode active material, charging and discharging of the electrochemical cell The nonaqueous electrolyte secondary battery 1 capable of suppressing the occurrence of cracks due to the volume expansion / contraction that sometimes occurs in the negative electrode 40 can be manufactured.
Further, by adding the second additive element R to the negative electrode active material, the negative electrode active material can be stably present in an amorphous state. Therefore, during charging / discharging of the electrochemical cell, Electron conductivity is enhanced, it is possible to improve the homogeneity of the charge in the negative electrode active material, it is possible to prevent localization of volume expansion and contraction of the negative electrode 40 due to the bias when inserting alkali metal ions, and cracks The nonaqueous electrolyte secondary battery 1 capable of suppressing the generation can be manufactured.

  Next, an Example and a comparative example are shown and this invention is demonstrated further more concretely. It should be noted that the scope of the present invention is not limited by this example, and the electrochemical cell according to the present invention can be appropriately modified and implemented without departing from the scope of the present invention.

[Example 1]
In Example 1, first, a laminate-type nonaqueous electrolyte secondary battery as shown in FIGS. 1A to 1C was produced as an electrochemical cell.
In this embodiment, as shown in FIG. 1A, the outer package 2 is an aluminum laminated film in which a nylon layer (25 μm), an aluminum foil (40 μm), and a polypropylene layer (30 μm) are sequentially laminated.
The negative electrode body 4 includes a negative electrode 40 and a negative electrode current collector 41. The negative electrode 40 is configured by using a negative electrode active material according to the present invention described later, a conductive additive and a binder, and is formed on both surfaces of a negative electrode current collector 41 made of pure copper foil.
The positive electrode body 3 includes a positive electrode 30 and a positive electrode current collector 31. The positive electrode 30 is composed of a positive electrode active material, a conductive additive and a binder, and is formed on both surfaces of a positive electrode current collector 31 made of pure aluminum foil.
The separator 4 is disposed between the negative electrode body 4 and the positive electrode body 3.
As for the electrode body 10, the laminated body which consists of each of these film-like layers is wound by the same direction.
As the non-aqueous electrolyte constituting the electrolytic solution, an electrolytic solution in which 1 M / L of LiFP ₆ was dissolved as a supporting salt in a solvent in which PC: EC: EMC was mixed at a volume ratio of 1: 1: 2 was used.
The size of the produced nonaqueous electrolyte secondary battery was 21 mm in width, 30 mm in length, and 3 mm in height.

Here, the _{SiO y (0 ≦ y <2} ) which is a precursor of the negative electrode active material used for the negative electrode 40, respectively, to prepare the respective silicon oxide (SiO ₂₎ powder and silicon (Si) powder and green compact The material was obtained by vaporizing by heating the heater temperature to 1400 ° C. or higher in a vacuum and depositing the vapor on a SUS substrate. The composition of this material was SiO.
Next, this SiO thin plate was directly put into an agate ball mill pot, and further agate balls were added together with ethanol to perform pulverization. At this time, in the initial stage of pulverization, coarse pulverization was performed by 72 hours of operation using a ball having a diameter of 8 mm, and after classification, fine pulverization was further performed by operation of 72 hours using a ball having a diameter of 2 mm.
Next, the pulverized SiO particles are sufficiently dried, classified to 10 μm or less, mixed with expanded graphite used as a conductive auxiliary agent, and then, using a ball mill, the expanded graphite is simultaneously crushed to the surface of SiO. Coating was performed by fixing. At this time, the expanded graphite is cleaved with respect to the d002 surface by a ball mill, easily forms a carbon sheet (graphene), and is brought into contact with SiO in a highly active state to form a firmly fixed state. A carbon coat was applied.

Here, the adjustment conditions and procedure of the negative electrode mixture were as follows.
First, as a binder, lithium hydroxide (LiOH · LiOH ·) is added to an aqueous solution in which a powder of a crosslinked polyacrylic acid resin having a carboxyl group content of 50 to 70% (polyacrylic acid manufactured by Wako Pure Chemical Industries, Ltd.) is added to purified water and dissolved. Using an aqueous solution of (H ₂ O) n), neutralization treatment was performed so that the pH was approximately 7.
Next, the conductive assistant was added to the previous binder and dispersed. At this time, graphite (Japan graphite exfoliated graphite: CMX) was used as the conductive assistant, and the carbon-coated SiO obtained by the above method was further added and dispersed. The particle diameter of this graphite was approximately 5 μm. At this time, the blending ratio of SiO, graphite, and carbon fiber was blending ratio number H- 1 shown in Table 2 below. For dispersion, a Kurabo Industries planetary stirring mixer (K102 type) was used to prepare a negative electrode mixture slurry.
Next, this negative electrode mixture slurry was uniformly applied to both sides of a copper foil having a thickness of 20 μm and dried, followed by compression molding with a roll press machine, and a negative electrode sheet (the negative electrode was laminated on the negative electrode current collector). Negative electrode body). The thickness of this negative electrode sheet was 70 μm.

Moreover, the positive electrode 30 was produced in the following procedures.
First, lithium manganese composite oxide as a positive electrode active material, graphite as a conductive material, and polyvinylidene fluoride as a binder are mixed (mass ratio 85: 5: 10) and dispersed in N-methyl-2-pyrrolidone as a solvent. A positive electrode mixture slurry was prepared.
Next, this positive electrode mixture slurry was applied to an aluminum foil having a thickness of 20 μm and dried, and then compression-molded by a roll press machine to form a positive electrode sheet (a positive electrode negative electrode having a positive electrode laminated on a positive electrode current collector) Was made.

  Next, a positive electrode sheet and a negative electrode sheet are cut out, and after attaching a positive electrode terminal and a negative electrode terminal to each, a 8 μm thick lithium metal is pasted on the negative electrode sheet, and a separator is a microporous polyethylene film having a thickness of 20 μm. Was sandwiched between the positive electrode sheet and the lithium metal on the negative electrode sheet, and wound in the longitudinal direction a predetermined number of times to produce a battery element (electrode body).

As the exterior, an aluminum laminate film in which a nylon layer (25 μm), an aluminum foil (40 μm), and a polypropylene layer (30 μm) were sequentially laminated was used. At this time, the battery element produced by the above procedure was loaded into an aluminum laminate film formed in a substantially bag shape, and a mixed solvent of LiBF ₄ (1 mol / l concentration), propylene carbonate, ethylene carbonate, and ethyl methyl carbonate (volume ratio 1: 1). : The electrolyte solution which consists of 2) was inject | poured, and it sealed by heat-sealing an aluminum laminate film after defoaming.

Thereafter, the produced electrochemical cell was left at room temperature for 1 week to perform lithium doping on SiO, which is the negative electrode active material in the negative electrode sheet.
Further, after that, a part of the aluminum laminate film was cut, gas generated at the time of lithium doping of SiO was released from the aluminum laminate film, and the aluminum laminate film was heat sealed again for sealing.

And the cycle life characteristic was evaluated on the following conditions regarding the electrochemical cell produced in the said procedure.
The cycle life characteristic test was performed by charging at a constant current of 100 μA up to a charge end voltage of 3.3 V at normal temperature (24 ° C.), reaching 3.3 V, and holding at the constant voltage for 96 hours. Thereafter, 15 μA constant current discharge was performed as one cycle up to a discharge end voltage of 2.0 V, and was performed up to 5 cycles. At this time, the capacity retention rate was {(discharge capacity at the fifth cycle / discharge capacity at the fourth cycle) × 100}.

  The production conditions of the negative electrode active material in Example 1 and Examples 2 to 21 and Comparative Example 1 described later are shown in Table 1 below, and the blending ratio of SiO, graphite, and carbon fiber as a precursor is shown. The results are shown in Table 2 below, and the evaluation results of the cycle life characteristics are shown in Tables 3 to 7 below.

[Examples 2 , 3, 6-16, 19-21 ]
[Comparative Example 1]
In Examples 2 and 3 shown in Table 4 (including Example 1), graphite (Japanese graphite flakes) was used as a conductive aid used in preparing the negative electrode mixture with respect to the production conditions of the electrochemical cell in Example 1. In addition to graphite (CMX), carbon fiber (Showa Denko vapor-grown carbon fiber: VGCF) was added. The carbon fiber had a diameter of 0.15 μm and a length of approximately 10 μm. Further, a non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the mixing ratio of SiO, graphite, and carbon fiber was changed at the ratio shown in Table 2, and the same method was used. The cycle life characteristics were evaluated and the results are shown in Table 4.

Further, in Example 6 (including Example 1) shown in Table 5, except that the precursor SiO is added with C and subjected to a stabilization process for granulation and sizing, A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1, and the cycle life characteristics were evaluated in the same manner.
Further, in Examples 7 to 16 , 19 to 21 shown in Tables 6 and 7, the production conditions of the negative electrode active material were changed under the conditions of the respective active material numbers shown in Table 1, and further, the precursor SiO was changed to SiO. A non-aqueous electrolyte secondary battery is produced in the same manner as in Example 1 except that the treatment is performed in the stabilization process in which C, Ti is added and granulation and sizing is performed. Characteristics were evaluated.

[Evaluation results]
The active material numbers 1-1 to 5-5 shown in Table 1 are the production conditions of the precursors of the negative electrode active material in each Example and Comparative Example, and the compounding ratio numbers shown in Table 2 are the precursors in the negative electrode, It is the mixing condition of graphite and carbon fiber. Tables 3 to 7 show a list of discharge capacity and cycle retention ratio (cycle life characteristics) in addition to the active material numbers and blending ratio numbers in the examples and comparative examples.

As shown in Tables 1 to 7, the nonaqueous electrolyte secondary batteries of Examples 1 to 16 and 19 to 21 each including a negative electrode using a negative electrode active material defined in the present invention as the negative electrode active material The cycle retention after 5 cycles is 87.7% or more, and it is clear that the cycle life characteristics are excellent. In particular, in Examples 7 to 9, Examples 11 to 13, and Examples 15 and 16, since the cycle maintenance ratio is almost 100%, it can be seen that the cycle life characteristics are more excellent. In addition, although not shown in the table, the cycle retention rate was almost the same as in Examples 7 to 16 even when the mass ratio of the second additive element R was 0.5% or 2%. .

On the other hand, in Comparative Example 1 in which the negative electrode active material used for the negative electrode was manufactured under conditions outside the range defined in the present invention, the cycle retention rate was 78.8%, which was compared with Examples 1 to 16, 19 to 21. It is extremely inferior. This is because the negative electrode active material produced in Comparative Example 1 was not added with either the first additive element M or the second additive element R defined in the present invention, and thus during charge / discharge in each cycle. This is probably because the negative electrode was cracked by the volume expansion / contraction of the negative electrode, resulting in an increase in internal resistance and capacity degradation.

  Although not described as an example, even when Al, Ge, or Zr was used as the second additive element R, the cycle retention rate was 87.7% or more. From this, even when Al, Ge, Zr is added as the second additive element R, an electrochemical cell having excellent cycle life characteristics can be obtained as in the case of using In, Sn, Ti, C. It is clear.

  Moreover, electrochemical cells, such as a nonaqueous electrolyte secondary battery provided with the negative electrode of this embodiment, are used suitably for the small portable apparatus of the power supply of voltage value 2-3V, for example.

  As described above, it is apparent that an electrochemical cell such as a nonaqueous electrolyte secondary battery having excellent cycle life characteristics can be obtained by providing a negative electrode using the negative electrode active material defined in the present invention.

  According to the electrochemical cell of the present invention, by providing the negative electrode, it is possible to suppress cracking of the negative electrode due to volume expansion / reduction during charging / discharging, and to suppress an increase in internal resistance and capacity deterioration. It becomes. Thereby, an electrochemical cell having high reliability, high capacity, and excellent cycle life characteristics can be provided. Therefore, by applying the present invention to an electrochemical cell such as a non-aqueous electrolyte secondary battery (electric double layer capacitor) used in the field of various electronic devices, for example, it contributes to improving the performance of various devices. It can be done.

1 ... non-aqueous electrolyte secondary battery (electric double layer capacitor: electrochemical cell),
2 ... exterior body,
21 ... container part,
21a ... accommodating part,
22 ... the lid,
22a ... accommodating part,
10 ... electrode body,
3 ... positive electrode body,
30 ... positive electrode,
31 ... Positive electrode current collector,
4 ... negative electrode body,
40 ... negative electrode,
41 ... negative electrode current collector,
5 ... separator,

Claims (2)

An electrochemical cell comprising a positive electrode, a negative electrode, an electrolyte containing a supporting salt and a nonaqueous solvent, and a separator,
The negative electrode active material used for the negative electrode contains at least Si element and is represented by the following formula {A _x SiO _y M _z + R}, and can reversibly insert and desorb ions of alkali metal or alkaline earth metal. And one or both of the following first additive element M and second additive element R with respect to the total amount of Si element contained in the negative electrode active material, respectively, Fine particles having an average particle diameter of D50 of 1 nm or more and 50 μm or less, added at a mass ratio of 1 ppm or more and 1 % or less,
Furthermore, the negative electrode contains graphite as a carbon material for imparting electronic conductivity , and, if necessary, carbon fiber, and is a precursor of the negative electrode active material, SiO _y M _z + R, An electrochemical cell characterized in that the compounding ratio of graphite and the carbon fiber is in the range of the following formula {SiO _y M _z + R: graphite: carbon fiber = 45: 45: 0 to 45:35:10}.
(1) First additive element M: at least one element of B or P.
(2) Second additive element R: At least one element selected from the group consisting of Ti and C.
However, in the above formula _{{A x SiO y M z +} R} , A represents a cationic species, an alkali metal ion or alkaline earth metal ions of elements, x is the formula in ionic species content A { It takes a value of 0 ≦ x ≦ 4.4}, y is the amount of oxygen and is the following formula {0 ≦ y ≦ 2}, M is the first additive element, and R is the second additive element. An electrochemical cell comprising a positive electrode, a negative electrode, an electrolyte containing a supporting salt and a nonaqueous solvent, and a separator,
The negative electrode active material used for the negative electrode contains at least Si element and is represented by the following formula {A _x SiO _y M _z + R}, and can reversibly insert and desorb ions of alkali metal or alkaline earth metal. consists substances, and the relative to the total amount of Si elements contained in the negative electrode active material, 1% or less first additive element M shown below than 10 ppm, the second additional element R shown below 0 .5% or more and 2% or less, respectively added , and D50 has an average particle diameter of 1 nm or more and 50 μm or less,
Furthermore, the negative electrode contains graphite as a carbon material for imparting electronic conductivity, and, if necessary, carbon fiber, and is a precursor of the negative electrode active material, SiO _y M _z + R, An electrochemical cell characterized in that the compounding ratio of graphite and the carbon fiber is in the range of the following formula {SiO _y M _z + R: graphite: carbon fiber = 45: 45: 0 to 45:35:10}.
(1) First additive element M: at least one element of B or P.
(2) Second additive element R: At least one element selected from the group consisting of Ti and C.
However, in the above formula _{{A x SiO y M z +} R} , A represents a cationic species, an alkali metal ion or alkaline earth metal ions of elements, x is the formula in ionic species content A { It takes a value of 0 ≦ x ≦ 4.4}, y is the amount of oxygen and is the following formula {0 ≦ y ≦ 2}, M is the first additive element, and R is the second additive element.

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