JP2010147006A - Negative electrode and secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a secondary battery having excellent cycle characteristics and expansion characteristics. <P>SOLUTION: The secondary battery includes a positive electrode 21, a negative electrode 22, and an electrolyte. A separator 23 arranged between the positive electrode 21 and negative electrode 22 is impregnated with the electrolyte. A negative electrode active material layer 22B includes a crystalline negative electrode active material layer formed on a negative electrode collector 22A and containing crystalline negative electrode active material, and a noncrystalline negative electrode active material layer formed on the crystalline negative electrode active material layer and containing noncrystalline negative active material. A property of the negative electrode active material can be prevented from being changed over time. Adhesiveness for withstanding stress by expansion and contraction of the negative electrode active material layer 22B is maintained in charging and discharging. Diffusivity of lithium ions is improved and reactivity of the negative electrode 22 on the electrolyte is reduced. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a negative electrode capable of occluding and releasing an electrode reactant and a secondary battery using the same.

  In recent years, portable electronic devices such as a video camera, a digital still camera, a mobile phone, and a laptop computer have been widely used, and there is a strong demand for miniaturization, weight reduction, and long life. Accordingly, as a power source, development of a battery, in particular, a secondary battery that is small and lightweight and capable of obtaining a high energy density is in progress.

  Among them, lithium ion secondary batteries that use the insertion and extraction of lithium ions for charge / discharge reactions are widely put into practical use because they have higher energy density than lead batteries and nickel cadmium batteries.

  A lithium ion secondary battery includes a positive electrode including a positive electrode active material capable of inserting and extracting lithium ions, a negative electrode including a negative electrode active material capable of inserting and extracting lithium ions, and an electrolyte. Yes.

  Carbon materials are widely used as the negative electrode active material. On the other hand, recently, with the improvement in performance and multi-function of portable electronic devices, further improvement in battery capacity has been demanded. Therefore, the use of silicon instead of carbon materials has been studied. This is because the theoretical capacity of silicon (4199 mAh / g) is much larger than the theoretical capacity of graphite (372 mAh / g), so that significant improvement in battery capacity is expected.

  When silicon is used as the negative electrode active material, a deposition method such as a vapor deposition method is used as a method for forming the negative electrode active material layer. Since silicon is directly deposited on the surface of the negative electrode current collector and the negative electrode active material (silicon deposition film) is connected (fixed) to the negative electrode current collector, the negative electrode active material layer expands and contracts during charge and discharge. Because it becomes difficult to do.

  However, due to the following reasons, there are concerns about deterioration of cycle characteristics and swelling characteristics, which are important characteristics of the secondary battery.

  First, since the negative electrode active material that occludes lithium ions during charge / discharge becomes highly active, some of the lithium ions are inactivated and gas is easily generated in the battery due to the decomposition reaction of the electrolyte. Become. For this reason, when charging and discharging are repeated, the discharge capacity is lowered and the battery is liable to swell.

  Second, even if the negative electrode active material is connected to the negative electrode current collector, the negative electrode active material layer may be cracked and the negative electrode current collector depending on the degree of expansion and contraction of the negative electrode active material layer during charge / discharge. There is a possibility of dropping out. In this case, when the negative electrode active material layer is vigorously expanded and contracted, the negative electrode current collector may be deformed. In particular, since the silicon film deposited by the vapor deposition method is a dense film, the adhesion between silicon is increased, but the stress generated in the negative electrode active material layer during charge / discharge tends to be less likely to be relaxed. For this reason, when charging and discharging are repeated, the discharge capacity is lowered and the battery is liable to swell.

  Thirdly, since the deposited film of silicon becomes amorphous (amorphous), the negative electrode active material is easily affected by oxidation. As a result, the physical properties of the negative electrode active material change with time, and the adhesion strength of the negative electrode active material layer to the negative electrode current collector tends to decrease. For this reason, if charge and discharge are repeated, the discharge capacity tends to decrease.

Therefore, several techniques have been proposed to improve various performances of the lithium ion secondary battery. Specifically, in order to improve battery capacity and the like, a three-dimensional mesh plastic substrate is plated so as to cover the entire three-dimensional mesh lattice surface from the surface of the plastic substrate to the innermost part. A metal layer is formed (see, for example, Patent Document 1). In addition, in order to improve cycle characteristics, a cathode active material layer is formed by alternately laminating silicon layers and silver layers (see, for example, Patent Document 2). Further, in order to improve battery capacity and cycle characteristics, a layer containing a material having lithium ion conductivity (such as silicon) is laminated on the layer containing a carbonaceous material by using a vapor deposition method or the like (for example, , See Patent Documents 3 to 5.) Further, in order to improve cycle characteristics and the like, the active material is formed so that an amorphous region is arranged around the crystal region (see, for example, Patent Documents 6 and 7).
Japanese Patent Laid-Open No. 06-349481 JP 2002-198037 A JP 2003-297353 A JP 2003-303618 A Japanese Patent Laid-Open No. 2004-164921 International Publication No. 01/029912 Pamphlet Japanese Patent Laid-Open No. 2002-083594

In addition, related techniques aiming to improve cycle characteristics have also been proposed. Specifically, an intermediate layer including a material having superelasticity or a shape memory effect is formed between the negative electrode current collector and the negative electrode active material layer (see, for example, Patent Document 8). Further, a conductive adhesive layer containing conductive particles and a binder is formed between the negative electrode current collector and the negative electrode active material layer (see, for example, Patent Document 9). Furthermore, the negative electrode active material layer is formed so that the lower layer having the first particles grown using the vapor phase method and the upper layer having the second particles deposited using the coating method are laminated. (For example, refer to Patent Document 10).
Japanese Patent Laid-Open No. 2005-141991 JP 2007-123141 A JP 2007-122915 A

  In recent years, portable electronic devices have become more sophisticated and multifunctional, and their power consumption has increased. Therefore, charging and discharging of secondary batteries tend to be repeated frequently. Therefore, in order to use the secondary battery safely at a high frequency, further improvement in cycle characteristics and swelling characteristics is desired.

  The present invention has been made in view of such problems, and an object thereof is to provide a negative electrode capable of obtaining excellent cycle characteristics and swelling characteristics and a secondary battery using the same.

  The negative electrode of the present invention can occlude and release electrode reactants and has a negative electrode active material layer on the negative electrode current collector. The negative electrode active material layer is formed on the negative electrode current collector and includes a crystalline negative electrode active material layer, and a crystalline negative electrode active material layer and a non-crystalline negative electrode A non-crystalline negative electrode active material layer containing an active material. The secondary battery of the present invention includes a positive electrode and a negative electrode capable of inserting and extracting electrode reactants, and an electrolyte containing a solvent and an electrolyte salt, and the negative electrode has the above-described configuration.

  According to the negative electrode of the present invention, the negative electrode active material layer is formed on the negative electrode current collector and formed on the crystalline negative electrode active material layer including the crystalline negative electrode active material and the crystalline negative electrode active material layer And a non-crystalline negative electrode active material layer containing a non-crystalline negative electrode active material. In this case, the physical properties of the negative electrode active material are less likely to change with time than when the negative electrode active material layer is composed of only the amorphous negative electrode active material layer, and the negative electrode active material layer is expanded and contracted during the electrode reaction. Adhesiveness that can withstand stress is maintained. In addition, the diffusibility (ease of entering and exiting) of the electrode reactant is improved and the reactivity of the negative electrode is reduced as compared with the case where the negative electrode active material layer is composed only of the crystalline negative electrode active material layer. Therefore, according to the secondary battery using the negative electrode of the present invention, excellent cycle characteristics and swelling characteristics can be obtained.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The order of explanation is as follows.

1. Negative electrode Electrochemical device using a negative electrode (secondary battery)
2-1. First secondary battery (battery structure: square)
2-2. Second secondary battery (battery structure: cylindrical)
2-3. Third secondary battery (battery structure: laminate film type)

<1. Negative electrode>
FIG. 1 shows a cross-sectional configuration of a negative electrode according to an embodiment of the present invention. This negative electrode is used for an electrochemical device such as a secondary battery, for example, and has a negative electrode active material layer 2 on a negative electrode current collector 1.

[Negative electrode current collector]
The negative electrode current collector 1 is preferably made of a material having good electrochemical stability, electrical conductivity, and mechanical strength. Examples of such a material include copper, nickel, and stainless steel, and copper is preferable. This is because high electrical conductivity can be obtained.

  The surface of the negative electrode current collector 1 is preferably roughened. This is because the adhesion of the negative electrode active material layer 2 to the negative electrode current collector 1 is improved by a so-called anchor effect. In this case, the surface of the negative electrode current collector 1 may be roughened at least in a region facing the negative electrode active material layer 2. Examples of the roughening method include a method of forming fine particles by electrolytic treatment. This electrolytic treatment is a method of forming irregularities by forming fine particles on the surface of the negative electrode current collector 1 by an electrolytic method in an electrolytic bath. The copper foil produced by the electrolytic method is generally called “electrolytic copper foil”. In addition, examples of the roughening method include a method of sandblasting a rolled copper foil.

  The ten-point average roughness Rz of the surface of the negative electrode current collector 1 is not particularly limited, but is preferably 1.5 μm or more. In this case, it is more preferably 1.5 μm or more and 30 μm or less, and further preferably 3 μm or more and 30 μm or less. This is because the adhesion of the negative electrode active material layer 2 to the negative electrode current collector 1 is further improved. In detail, when it is smaller than 1.5 μm, there is a possibility that sufficient adhesion cannot be obtained, and when it is larger than 30 μm, there is a possibility that the adhesion is deteriorated.

[Negative electrode active material layer]
The negative electrode active material layer 2 is provided on both surfaces of the negative electrode current collector 1, for example. However, the negative electrode active material layer 2 may be provided only on one side of the negative electrode current collector 1.

  This negative electrode active material layer 2 contains, as a negative electrode active material, any one or more of negative electrode materials capable of occluding and releasing electrode reactants such as lithium ions, for example. Other materials such as a negative electrode conductive agent may be included.

  As the negative electrode material, a material containing silicon as a constituent element is preferable. This is because a high energy density can be obtained because the ability to occlude and release the electrode reactant is excellent. Such a material may be a simple substance, an alloy, or a compound of silicon, or two or more thereof, or one having at least a part of one or two or more phases thereof. Among these, at least one of silicon simple substance, alloy and compound is preferable, and silicon simple substance is more preferable. Note that “single substance” is a simple substance in a general sense, and does not necessarily mean 100% purity.

  The “alloy” in the present invention includes one containing one or more metal elements and one or more metalloid elements in addition to one containing two or more metal elements. Of course, the above-mentioned “alloy” may contain a nonmetallic element. The structure includes solid solution, eutectic (eutectic mixture), intermetallic compound, or coexistence of two or more thereof.

  Examples of silicon alloys include those containing at least one of the following elements as constituent elements other than silicon. Examples thereof include tin, nickel, copper, iron, cobalt, manganese, zinc, indium (In), silver, titanium, germanium, bismuth (Bi), antimony, and chromium.

  Examples of the silicon compound include those containing oxygen and carbon (C) as constituent elements other than silicon. The silicon compound may contain, for example, any one or more of the elements described for the silicon alloy as a constituent element other than silicon.

Examples of silicon alloys or compounds include the following. _{SiB 4, SiB 6, Mg 2} Si, is like _{Ni 2 Si, TiSi 2, MoSi} 2, CoSi 2, NiSi 2, CaSi 2, CrSi 2, Cu 5 Si, FeSi 2, MnSi 2, NbSi 2 or TaSi _2. VSi ₂ , WSi ₂ , ZnSi ₂ , SiC, Si ₃ N ₄ , Si ₂ N ₂ O, SiO _v (0 <v ≦ 2), SnO _w (0 <w ≦ 2), LiSiO, or the like.

  The negative electrode active material preferably contains oxygen as a constituent element in addition to the above-described silicon. This is because expansion and contraction of the negative electrode active material layer 2 are suppressed during the electrode reaction. In this case, it is preferable that at least part of oxygen is bonded to part of silicon. The bonding state may be silicon monoxide or silicon dioxide, or another metastable state.

  Although oxygen content in a negative electrode active material is not specifically limited, Especially, it is preferable that they are 1.5 atomic% or more and 40 atomic% or less. This is because expansion and contraction of the negative electrode active material layer 2 are suppressed. Specifically, if the amount is less than 1.5 atomic%, the negative electrode active material layer 2 may not be sufficiently suppressed in expansion and contraction. If the amount is more than 40 atomic%, the resistance may increase excessively. There is. When the negative electrode is used in an electrochemical device together with an electrolyte, a film formed by a decomposition reaction of the electrolyte is not included in the negative electrode active material. That is, when the oxygen content in the negative electrode active material is calculated, oxygen in the above-described coating is not included.

  The negative electrode active material containing oxygen is formed, for example, by continuously introducing oxygen gas into the chamber when depositing the negative electrode material. In particular, when a desired oxygen content cannot be obtained simply by introducing oxygen gas, a liquid (for example, water vapor) may be introduced into the chamber as an oxygen supply source.

  The negative electrode active material preferably contains a metal element as a constituent element in addition to the above-described silicon. This is because the resistance of the negative electrode active material is lowered and the expansion and contraction of the negative electrode active material layer 2 are suppressed during the electrode reaction. Examples of such metal elements include at least one of the following elements. Iron, nickel, molybdenum, titanium, chromium, cobalt, copper, manganese, zinc, germanium, aluminum, zirconium, silver, tin, antimony or tungsten. The content of the metal element in the negative electrode active material is not particularly limited. However, when the negative electrode is used in a secondary battery, if the content of the metal element is excessive, the negative electrode active material layer 2 must be thickened to obtain a desired battery capacity. It should be noted that the material layer 2 may crack and peel from the negative electrode current collector 1.

  In this case, the negative electrode active material may contain a metal element as a whole, or may partially contain a metal element. The state of the negative electrode active material containing a metal element may be a complete alloy state (alloy state), or a state in which silicon and metal elements are mixed (compounds) without reaching a complete alloy. State or phase separation state). The state of the negative electrode active material can be confirmed by, for example, energy dispersive x-ray fluorescence spectroscopy (EDX).

  The negative electrode active material containing a metal element is formed by, for example, using alloy particles as a forming material when depositing a negative electrode material, or depositing a metal material together with the negative electrode material.

  The negative electrode active material preferably includes a high oxygen content region having a higher oxygen content and a low oxygen content region having a lower oxygen content in the thickness direction of the negative electrode active material layer 2. . This is because expansion and contraction of the negative electrode active material layer 2 are suppressed during the electrode reaction. The oxygen content in the low oxygen content region is preferably as small as possible. The oxygen content in the high oxygen content region is not particularly limited, but is preferably the same as the oxygen content (1.5 atomic% to 40 atomic%) in the negative electrode active material.

  In this case, it is preferable that the high oxygen content region is sandwiched by the low oxygen content region, and it is more preferable that the low oxygen content region and the high oxygen content region are alternately laminated. This is because expansion and contraction of the negative electrode active material layer 2 are further suppressed. When the low oxygen content region and the high oxygen content region are alternately laminated, the oxygen content is distributed while repeating high and low in the negative electrode active material.

  The negative electrode active material including the high oxygen content region and the low oxygen content region is, for example, intermittently introducing oxygen gas into the chamber or changing the amount of oxygen gas introduced into the chamber when depositing the negative electrode material. Formed. Of course, when a desired oxygen content cannot be obtained simply by introducing oxygen gas, a liquid (for example, water vapor) may be introduced into the chamber.

  Note that the oxygen content may or may not be clearly different between the high oxygen content region and the low oxygen content region. In particular, when the amount of oxygen gas introduced is continuously changed, the oxygen content may also be continuously changed. The high oxygen content region and the low oxygen content region are so-called “layers” when the oxygen gas introduction amount is changed intermittently, and “layers” when the oxygen gas introduction amount is continuously changed. Rather, it becomes “layered”. In this case, it is preferable that the oxygen content changes stepwise or continuously between the high oxygen content region and the low oxygen content region. This is because, if the oxygen content changes rapidly, the diffusibility of ions may decrease and the resistance may increase.

  The negative electrode active material layer 2 may contain other negative electrode materials as long as the negative electrode material contains a material containing silicon as a constituent element.

  As another negative electrode material, for example, it is possible to occlude and release an electrode reactant, and a material containing at least one of a metal element and a metalloid element as a constituent element (a material containing silicon as a constituent element) Excluding those that apply). This is because a high energy density can be obtained. Such a material may be a single element, an alloy or a compound of a metal element or a metalloid element, or may be two or more of them, or may have at least a part of one or more of those phases. .

  The metal element or metalloid element described above is, for example, a metal element or metalloid element capable of forming an alloy with the electrode reactant, and specifically, at least one of the following elements. Magnesium, boron, aluminum, gallium, indium, germanium, tin, or lead (Pb). Further, bismuth, cadmium (Cd), silver, zinc, hafnium (Hf), zirconium, yttrium (Y), palladium (Pd), or platinum (Pt). Of these, tin is preferable. This is because a high energy density can be obtained because the ability to occlude and release the electrode reactant is excellent. The material containing tin may be a simple substance, an alloy or a compound of tin, or two or more thereof, or one having at least a part of one or two or more phases thereof.

Examples of the tin alloy include at least one of silicon, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony, and chromium as constituent elements other than tin. Things. Examples of tin compounds include those containing oxygen or carbon as constituent elements other than tin. In addition, the compound of tin may contain any 1 type (s) or 2 or more types of the element demonstrated about the alloy of tin as structural elements other than tin, for example. Examples of tin alloys or compounds include SnSiO ₃ , LiSnO, Mg ₂ Sn, and the like.

  In particular, as a material containing tin, for example, a material containing tin as a first constituent element and further containing second and third constituent elements is preferable. This is because when the negative electrode is used in a secondary battery, a high battery capacity is obtained and cycle characteristics are improved. The second constituent element is, for example, at least one of the following elements. Cobalt, iron, magnesium, titanium, vanadium, chromium, manganese, nickel, copper, zinc, gallium or zirconium. Niobium, molybdenum, silver, indium, cerium (Ce), hafnium, tantalum, tungsten, bismuth, or silicon. The third constituent element is, for example, at least one of boron, carbon, aluminum, and phosphorus.

  Among these, a material containing Sn, cobalt, and carbon (SnCoC-containing material) is preferable. The composition of the SnCoC-containing material is such that the carbon content is 9.9 mass% or more and 29.7 mass% or less, and the ratio of content of tin and cobalt (Co / (Sn + Co)) is 20 mass% or more and 70 It is below mass%. This is because a high energy density can be obtained in such a composition range. In the SnCoC-containing material, it is preferable that at least a part of carbon that is a constituent element is bonded to a metal element or a metalloid element that is another constituent element. This is because aggregation or crystallization of tin or the like is suppressed.

  This SnCoC-containing material has a phase containing tin, cobalt and carbon, and the phase is preferably low crystalline or amorphous. This phase is a reaction phase capable of reacting with the electrode reactant, and excellent characteristics can be obtained by the presence of the reaction phase. The half width of the diffraction peak obtained by X-ray diffraction of this phase is preferably 1 ° or more at a diffraction angle 2θ when CuKα ray is used as the specific X-ray and the drawing speed is 1 ° / min. . This is because the electrode reactant is occluded and released more smoothly, and the reactivity with the electrolyte and the like is further reduced. In addition to the low crystalline or amorphous phase, the SnCoC-containing material may have a phase containing a single element or a part of each constituent element.

  Note that the SnCoC-containing material may further contain other constituent elements as necessary. Examples of such other constituent elements include at least one of silicon, iron, nickel, chromium, indium, niobium, germanium, titanium, molybdenum, aluminum, phosphorus, gallium, and bismuth.

  In addition to this SnCoC-containing material, a material containing tin, cobalt, iron and carbon (SnCoFeC-containing material) is also preferable. The composition of the SnCoFeC-containing material can be arbitrarily set. For example, the composition when the content of iron is set to be small is as follows. The carbon content is 9.9 mass% or more and 29.7 mass% or less, the iron content is 0.3 mass% or more and 5.9 mass% or less, and the content ratio of tin and cobalt (Co / (Sn + Co)) is 30% by mass or more and 70% by mass or less. For example, the composition in the case where the content of iron is set to be large is as follows. The carbon content is 11.9% by mass or more and 29.7% by mass or less. Further, the content ratio of tin, cobalt, and iron ((Co + Fe) / (Sn + Co + Fe)) is 26.4 mass% to 48.5 mass%, and the content ratio of cobalt and iron (Co / (Co + Fe) )) Is 9.9 mass% or more and 79.5 mass% or less. This is because a high energy density can be obtained in such a composition range. The physical properties and the like (half width, etc.) of this SnCoFeC-containing material are the same as those of the above-described SnCoC-containing material.

  Moreover, as another negative electrode material, a carbon material is mentioned, for example. This is because there is very little change in the crystal structure accompanying the insertion and extraction of the electrode reactant, and a high energy density can be obtained. Further, it also functions as a conductive agent. Examples of the carbon material include graphitizable carbon, non-graphitizable carbon having a (002) plane spacing of 0.37 nm or more, or graphite having a (002) plane spacing of 0.34 nm or less. Can be mentioned. More specifically, there are pyrolytic carbons, cokes, glassy carbon fibers, organic polymer compound fired bodies, activated carbon or carbon blacks. Of these, the cokes include pitch coke, needle coke, petroleum coke, and the like. The organic polymer compound fired body is obtained by firing and carbonizing a phenol resin, a furan resin, or the like at an appropriate temperature. The shape of the carbon material may be any of fibrous, spherical, granular or scale-like.

  Furthermore, examples of other negative electrode materials include metal oxides and polymer compounds. Examples of the metal oxide include iron oxide, ruthenium oxide, and molybdenum oxide. Examples of the polymer compound include polyacetylene, polyaniline, and polypyrrole.

  Of course, the negative electrode material may be other than the above. A series of negative electrode active materials may be mixed in any combination of two or more.

  The negative electrode active material layer 2 is preferably alloyed at least at a part of the interface with the negative electrode current collector 1. This is because the negative electrode active material layer 2 is less likely to expand and contract during the electrode reaction, and electronic conductivity is improved between the negative electrode current collector 1 and the negative electrode active material layer 2. This “alloying” is not only when the constituent elements of the negative electrode current collector 1 and the constituent elements of the negative electrode active material layer 2 form a complete alloy, but also when both constituent elements are in a mixed state. Including. In this case, the constituent element of the negative electrode current collector 1 may diffuse into the negative electrode active material layer 2 at the interface between them, or the constituent element of the negative electrode active material layer 2 diffuses into the negative electrode current collector 1. The constituent elements of both may be diffused.

  Moreover, it is preferable that the negative electrode active material layer 2 has a space | gap inside. This is because the void serves as a refuge (relaxation space) when the negative electrode active material layer 2 expands and contracts during the electrode reaction, so that the negative electrode active material layer 2 is difficult to expand and contract.

  In particular, the negative electrode active material layer 2 includes a lower layer formed on the negative electrode current collector 1 and an upper layer formed thereon. The lower layer is a crystalline negative electrode active material layer 2X containing a crystalline negative electrode active material, and the upper layer is a non-crystalline negative electrode active material layer 2Y containing an amorphous negative electrode active material.

  The negative electrode active material layer 2 includes the crystalline negative electrode active material layer 2X (crystalline negative electrode active material) and the non-crystalline negative electrode active material layer 2Y (noncrystalline negative electrode active material) in the positional relationship described above. For the following reasons. First, since the crystalline negative electrode active material layer 2X is adjacent to the negative electrode current collector 1, the negative electrode active material layer 2 to the negative electrode current collector 1 is more than the case where the amorphous negative electrode active material layer 2Y is adjacent. Improved adhesion. Second, since the crystalline negative electrode active material layer 2X is less susceptible to oxidation than the non-crystalline negative electrode active material layer 2Y, the physical properties of the negative electrode active material change over time as compared with the case where the crystalline negative electrode active material layer 2X is not included. It becomes difficult to do. Third, since the crystalline negative electrode active material layer 2X is less likely to expand and contract than the non-crystalline negative electrode active material layer 2Y during the electrode reaction, the electrode reaction is greater than when the crystalline negative electrode active material layer 2X is not included. In some cases, adhesion capable of withstanding stress due to expansion and contraction of the negative electrode active material layer 2 is maintained. Fourth, since the non-crystalline negative electrode active material layer 2Y is located outside the crystalline negative electrode active material layer 2X, the diffusibility of the electrode reactant is larger than when the crystalline negative electrode active material layer 2X is located outside. (Ease of entering and exiting) is improved. This “outside” means the side in contact with the electrolyte when the negative electrode is used in an electrochemical device together with the electrolyte. Fifth, since the non-crystalline negative electrode active material layer 2Y is located outside, the reactivity of the negative electrode is reduced as compared with the case where the crystalline negative electrode active material layer 2X is located outside. Thereby, when the negative electrode is used in an electrochemical device together with an electrolyte, the decomposition reaction of the electrolyte is reduced.

  The crystal state (crystalline or non-crystalline) of the negative electrode active material can be confirmed by X-ray diffraction. Specifically, as a result of analyzing the negative electrode active material, it is crystalline when a sharp peak is detected, and is amorphous when a broad peak is detected.

  In the negative electrode active material layer 2, at least a part of the crystalline negative electrode active material layer 2X and the non-crystalline negative electrode active material layer 2Y may be laminated in this order. That is, as long as the negative electrode active material layer 2 includes a portion in which the crystalline negative electrode active material layer 2X and the amorphous negative electrode active material layer 2Y are laminated in this order, only one of them is formed. It may contain parts. As long as the crystalline negative electrode active material layer 2X and the non-crystalline negative electrode active material layer 2Y include a portion formed in this order, the above-described series of advantages can be obtained, unlike the case where the layer is not included at all. is there. When there is a portion where only the non-crystalline negative electrode active material layer 2Y is formed, the non-crystalline negative electrode active material layer 2Y is directly formed on the negative electrode current collector 1.

  The crystalline negative electrode active material in the crystalline negative electrode active material layer 2X has, for example, a plurality of particles. In this case, the plurality of negative electrode active materials may be arranged on the negative electrode current collector 1, may be stacked, or may be mixed. Moreover, the shape of the negative electrode active material may be any shape, but among them, at least a part is preferably flat. This is because the negative electrode active materials easily overlap each other, and the number of contact points between the negative electrode active materials increases, so that the electron conductivity in the negative electrode active material layer 2 increases. This “flat shape” is a shape extending in a direction along the surface of the negative electrode current collector 1, that is, in a direction having a major axis in the direction along the surface of the negative electrode current collector 1 and intersecting the surface. It means that it is substantially elliptical with a short axis. This flat shape is a characteristic seen when, for example, a negative electrode material is deposited by a thermal spraying method. In this case, if the melting temperature of the negative electrode material is increased, the negative electrode active material tends to become flat.

  The full width at half maximum (2θ) of the diffraction peak on the (111) crystal plane of the crystalline negative electrode active material obtained by X-ray diffraction is not particularly limited, but is preferably 20 ° or less. The crystallite size resulting from the same crystal plane is not particularly limited, but is preferably 100 nm or more. This is because the adhesion of the negative electrode active material layer 2 to the negative electrode current collector 1 is further improved and the physical properties of the negative electrode active material are less likely to change over time.

  The crystalline negative electrode active material is preferably connected to the surface of the negative electrode current collector 1. This is because since the crystalline negative electrode active material layer 2X is physically fixed to the negative electrode current collector 1, the negative electrode active material layer 2 is unlikely to expand and contract during the electrode reaction. In this case, as described above, the crystalline negative electrode active material layer 2X is preferably alloyed at least at a part of the interface with the negative electrode current collector 1.

  The above-mentioned “negative electrode active material is connected to the negative electrode current collector 1” means that the negative electrode material is directly deposited on the surface of the negative electrode current collector 1 to form the crystalline negative electrode active material layer 2X. It means that. For this reason, when the negative electrode active material layer is formed by, for example, a coating method or a sintering method, the negative electrode active material is not connected to the negative electrode current collector 1. In this case, the negative electrode active material is indirectly connected to the negative electrode current collector 1 via another material (for example, a binder), or the negative electrode active material is simply adjacent to the surface of the negative electrode current collector 1. I'm just doing it.

  Note that the crystalline negative electrode active material may be at least partially connected to the negative electrode current collector 1. This is because if only a part of the negative electrode current collector 1 is connected to the negative electrode current collector 1, the adhesion of the negative electrode active material layer 2 to the negative electrode current collector 1 is improved as compared with the case where the negative electrode current collector 1 is not connected at all.

  When the crystalline negative electrode active material is partially connected to the negative electrode current collector 1, the crystalline negative electrode active material layer 2 </ b> X includes a portion (contact portion) in contact with the negative electrode current collector 1, and a negative electrode current collector. It will have a part (non-contact part) which does not contact the electric body 1. FIG.

  In the case where the crystalline negative electrode active material layer 2X has a non-contact portion, there is a escape place (relaxation space) when the crystalline negative electrode active material layer 2X expands and contracts during the electrode reaction, and therefore the expansion Further, the negative electrode current collector 1 is hardly deformed due to the influence of stress due to shrinkage. On the other hand, since there is a portion that is not in contact between the negative electrode current collector 1 and the crystalline negative electrode active material layer 2X, there is a possibility that the electron conductivity between the two is lowered.

  On the other hand, when the crystalline negative electrode active material layer 2X does not have a non-contact portion, the crystalline negative electrode active material layer 2X is in contact with the negative electrode current collector 1 over the entire area. The electron conductivity between them increases. On the other hand, since there is no escape field (relaxation space) when the crystalline negative electrode active material layer 2X expands and contracts during the electrode reaction, the negative electrode current collector 1 is deformed under the influence of stress due to the expansion and contraction. there is a possibility.

  The crystalline negative electrode active material layer 2X preferably has voids therein. This is because the negative electrode active material layer 2 is less likely to expand and contract because there is a escape field (relaxation space) when the crystalline negative electrode active material layer 2X expands and contracts during the electrode reaction.

  The crystalline negative electrode active material layer 2X is formed by, for example, a thermal spraying method. Since the negative electrode active material is likely to be crystalline, as described above, the physical properties of the negative electrode active material are less likely to change with time, and adhesion that can withstand stress due to expansion and contraction of the negative electrode active material layer 2 during electrode reaction is achieved. This is because it is easy to maintain. Further, the thermal spraying method is superior in productivity because it has a higher deposition rate than the vapor deposition method described later. In the case of forming the crystalline negative electrode active material layer 2X using the thermal spraying method, for example, by adjusting the material and shape of the negative electrode material, the cooling temperature of the substrate, the film forming conditions, etc., the crystalline negative electrode active material layer 2X is adjusted. It is possible to control the presence or absence, the number and size of voids in the material layer 2X. However, the crystalline negative electrode active material layer 2X may be formed by a method other than the thermal spraying method as long as the negative electrode active material becomes crystalline.

  The non-crystalline negative electrode active material in the non-crystalline negative electrode active material layer 2Y is, for example, a plurality of particles. In this case, the non-crystalline negative electrode active material is arranged on the crystalline negative electrode active material layer 2X and connected to the surface thereof, for example. This is because the non-crystalline negative electrode active material layer 2Y is physically fixed to the crystalline negative electrode active material layer 2X, so that the non-crystalline negative electrode active material layer 2Y hardly expands and contracts during the electrode reaction. The meaning of “connected to the crystalline negative electrode active material layer 2X” is the same as the case described for “connected to the negative electrode current collector 1” of the crystalline negative electrode active material layer 2X.

  The non-crystalline negative electrode active material layer 2Y is formed by, for example, a vapor phase method such as a vapor deposition method, a sputtering method, or a CVD method, and is formed by at least one of a vapor deposition method, a sputtering method, and a CVD method. It is preferable. This is because the negative electrode active material is likely to be amorphous, and as described above, the diffusibility of the electrode reactant is improved and the reactivity of the negative electrode is reduced. However, the non-crystalline negative electrode active material layer 2Y may be formed by a method other than vapor deposition as long as the negative electrode active material becomes non-crystalline.

  When the non-crystalline negative electrode active material is formed by a deposition method such as a vapor deposition method, the non-crystalline negative electrode active material may have a single layer structure formed by a single deposition process. However, it may have a multilayer structure formed by a plurality of deposition steps. However, when high temperature is accompanied during deposition, it is preferable to have a multilayer structure. The time during which the negative electrode current collector 1 is exposed to higher heat than the case where the deposition process is performed once by performing the deposition process of the negative electrode material divided into a plurality of times (the negative electrode material is successively formed and deposited). It is because it becomes difficult to receive thermal damage.

  When the thickness of the crystalline negative electrode active material layer 2X is T1, and the thickness of the non-crystalline negative electrode active material layer 2Y is T2, the thickness ratio (T1 / (T1 + T2)) is not particularly limited. As described above, each of the crystalline negative electrode active material layer 2X and the non-crystalline negative electrode active material layer 2Y has unique advantages, and thus has more (composite) advantages than the case where only one of them is provided. This is because

  Especially, it is preferable that thickness ratio is 0.1 or more and 0.995 or less. For the performance of the whole negative electrode, the advantage (physical property change with time and adhesion) obtained by the crystalline negative electrode active material layer 2X rather than the advantage (diffusibility and reaction reduction) obtained by the amorphous negative electrode active material layer 2Y. This is because it has a big influence. The thickness ratio is more preferably 0.3 or more and 0.95 or less. This is because a higher effect can be obtained. A method for determining the thicknesses T1 and T2 will be described later (see FIG. 2).

  Here, a detailed configuration example of the negative electrode will be described.

  2 to 6 show an enlarged part of the negative electrode shown in FIG. 2 to 6, (A) is a scanning electron microscope (SEM) photograph (secondary electron image), and (B) is a schematic picture of the SEM image shown in (A).

  2, 3 and 6 show the case where the negative electrode active material is a simple substance of silicon, and FIGS. 4 and 5 show the case where the negative electrode active material is a material containing silicon and a metal element. ing. 2 shows a case where the crystalline negative electrode active material layer 2X and the amorphous negative electrode active material layer 2Y are formed, and FIGS. 3 to 6 show a case where only one of them is formed. ing. The case where only one of them is formed in FIGS. 3 to 6 is to make the cross-sectional structure easier to see.

  For example, after the crystalline negative electrode active material layer 2X is formed on the negative electrode current collector 1 by a spraying method or the like, the negative electrode active material layer 2 is formed on the crystalline negative electrode active material layer 2X by a vapor deposition method or the like. The active material layer 2Y is formed. In this case, the crystalline negative electrode active material layer 2X includes a plurality of crystalline negative electrode active materials (negative electrode active material particles 201X), and the non-crystalline negative electrode active material layer 2Y is non-crystalline. A plurality of particulate negative electrode active materials (negative electrode active material particles 201Y).

  In the crystalline negative electrode active material layer 2X, the plurality of negative electrode active material particles 201X are connected to the surface of the negative electrode current collector 1 as shown in FIGS. When the negative electrode current collector 1 is a roughened electrolytic copper foil or the like, the negative electrode material is formed so as to cover a plurality of protrusions (for example, fine particles) existing on the surface and to enter gaps between the protrusions. This is because the negative electrode active material particles 201X grow by being deposited.

  The negative electrode active material particles 201X may have a single layer structure arranged in a direction intersecting with the thickness direction of the negative electrode active material layer 2 as shown in FIG. As shown, the negative electrode active material layer 2 may have a multilayer structure stacked in the thickness direction. Of course, both structures may be mixed.

  The crystalline negative electrode active material layer 2X has a plurality of voids 202 therein. In addition, the crystalline negative electrode active material layer 2X is partially connected to the negative electrode current collector 1, for example, and a portion in contact with the negative electrode current collector 1 (contact portion P1) and the negative electrode current collector 1 And a portion that does not contact (non-contact portion P2).

  A part of the negative electrode active material particles 201X has a flat shape, for example, as shown in FIG. That is, the plurality of negative electrode active material particles 201X includes flat particles 201XP. The flat particles 201XP overlap and contact the adjacent negative electrode active material particles 201X.

  In the non-crystalline negative electrode active material layer 2Y, the plurality of negative electrode active material particles 201Y are arranged on the surface of the crystalline negative electrode active material layer 2X. When the crystalline negative electrode active material layer 2X includes a plurality of negative electrode active material particles 201X, the negative electrode active material particles 201Y mainly grow by depositing the negative electrode material for each negative electrode active material particle 201X. Because. The gap 203 formed between the negative electrode active material particles 201Y is evidence that the negative electrode active material particles 201Y have grown for each negative electrode active material particle 201X. 2 shows a case where the negative electrode active material particles 201Y have a single layer structure, and FIG. 6 shows a case where the negative electrode active material particles 201Y have a multilayer structure. In the latter case, a gap 203 is formed to the inside of the negative electrode active material particles 201Y, and each layer of the negative electrode active material particles 201Y is partitioned by the gap 203.

  In the case where the negative electrode active material particle 201X includes silicon and a metal element, for example, as illustrated in FIGS. 4 and 5, a part of the negative electrode active material particle 201X includes silicon and a metal element. . In this case, the crystal state of the negative electrode active material particles 201X may be an alloy state (AP) or a compound (phase separation) state (SP). Note that the state of the negative electrode active material particles 201X containing only silicon and not containing a metal element is a single state (MP).

  The three states (MP, AP, SP) related to these negative electrode active material particles 201X are clearly shown in FIG. That is, the single state (MP) is observed as a uniform gray region. The alloy state (AP) is observed as a uniform white area. The phase separation state (SP) is observed as a region where a gray portion and a white portion are mixed.

  Here, a method for determining the thicknesses T1 and T2 is as follows. First, using a SEM (magnification = 500 times), 10 cross-sections (FIG. 2) of the negative electrode are observed randomly (while the observation location is arbitrarily changed). Subsequently, for each SEM image, the thickness T1 of the crystalline negative electrode active material layer 2X and the thickness T2 of the amorphous negative electrode active material layer 2Y are measured. In this case, after drawing a reference line S (a line perpendicular to the surface of the negative electrode current collector 1) at a position where the negative electrode active material particles 201X and 201Y overlap in the thickness direction of the negative electrode active material layer 2, The thicknesses T1 and T2 are measured along the reference line S. The thickness T1 is the distance from the lower end to the upper end of the negative electrode active material particle 201X along the reference line S, and the thickness T2 is the distance from the lower end to the upper end of the negative electrode active material particle 201Y along the reference line S. is there. Note that the lower end and the upper end of the negative electrode active material particles 201X described above vary depending on the number of the negative electrode active material particles 201X present along the reference line S. When only one negative electrode active material particle 201X is present, it is the lower end and the upper end of one negative electrode active material particle 201C. In contrast, when a plurality of negative electrode active material particles 201X are present, they are the lower end of the lowermost negative electrode active material particle 201X and the upper end of the uppermost negative electrode active material particle 201X. The same applies to the lower end and the upper end of the negative electrode active material particles 20Y. Finally, an average value of the thicknesses T1 and T2 measured for each SEM image is calculated, and the average value is determined as the final thickness T1 and T2. The total thickness of the negative electrode active material layer 2 is the sum of the thicknesses T1 and T2 described above.

  This negative electrode is manufactured, for example, by the following procedure.

  First, a negative electrode current collector 1 made of a roughened electrolytic copper foil or the like is prepared. Subsequently, a negative electrode material is deposited on the surface of the negative electrode current collector 1 using a thermal spraying method or the like to form a crystalline negative electrode active material layer 2X (thickness T1) containing a crystalline negative electrode active material. Finally, a negative electrode material is deposited on the surface of the crystalline negative electrode active material layer 2X using a vapor deposition method or the like to form an amorphous negative electrode active material layer 2Y (thickness T2) containing an amorphous negative electrode active material. To do. Thereby, since the negative electrode active material layer 2 in which the crystalline negative electrode active material layer 2X and the amorphous negative electrode active material layer 2Y are laminated in this order is formed, the negative electrode is completed.

  When the negative electrode active material layer 2 is formed, for example, the deposition time of the negative electrode material is adjusted in the step of forming the crystalline negative electrode active material layer 2X and the non-crystalline negative electrode active material layer 2Y, and the thickness ratio (T1 / (T1 + T2)) can be changed.

  According to this negative electrode, the negative electrode active material layer 2 is formed on the negative electrode current collector 1 and includes a crystalline negative electrode active material layer 2X containing a crystalline negative electrode active material, and the crystalline negative electrode active material layer 2X. And a non-crystalline negative electrode active material layer 2Y including a non-crystalline negative electrode active material. In this case, the physical properties of the negative electrode active material are less likely to change over time than the case where the negative electrode active material layer 2 is made of only the amorphous negative electrode active material layer 2Y, and the negative electrode active material layer 2 expands during the electrode reaction. In addition, adhesion that can withstand stress due to shrinkage is maintained. Further, the diffusibility (ease of entering and exiting) of the electrode reactant is improved and the reactivity of the negative electrode is reduced as compared with the case where the negative electrode active material layer 2 is composed of only the crystalline negative electrode active material layer 2X. Therefore, it can contribute to the performance improvement of the electrochemical device using a negative electrode. More specifically, when the negative electrode is used for a secondary battery, excellent cycle characteristics and swelling characteristics can be obtained.

  In particular, in the crystalline negative electrode active material layer 2X, if at least a part of the crystalline negative electrode active material is flat, a higher effect can be obtained. If the half width of the diffraction peak at the (111) crystal plane of the crystalline negative electrode active material obtained by X-ray diffraction is 20 ° or less, or the crystallite size resulting from the crystal plane is 100 nm or more, A higher effect can be obtained.

  Further, the thickness ratio (T1 / (T1 + T2)) of the crystalline negative electrode active material layer 2X and the amorphous negative electrode active material layer 2Y is 0.1 to 0.995, preferably 0.3 to 0.95. If so, a higher effect can be obtained.

  In addition, if the negative electrode active material contains oxygen and the oxygen content in the negative electrode active material is 1.5 atomic% to 40 atomic%, or the negative electrode active material contains a metal element such as iron Higher effects can be obtained. Similarly, if the negative electrode active material includes a high oxygen content region and a low oxygen content region, a higher effect can be obtained.

  Further, if the surface of the negative electrode current collector 1 is roughened, the adhesion of the negative electrode active material layer 2 to the negative electrode current collector 1 can be improved. In this case, a higher effect can be obtained if the ten-point average roughness Rz of the surface of the negative electrode current collector 1 is 1.5 μm or more, preferably 3 μm or more and 30 μm or less.

<2. Secondary battery>
Next, usage examples of the above-described negative electrode will be described. Here, taking a secondary battery as an example of an electrochemical device, the above-described negative electrode is used as follows.

<2-1. First secondary battery>
7 and 8 show a cross-sectional configuration of the first secondary battery, and FIG. 8 shows a cross section taken along the line VIII-VIII shown in FIG. The secondary battery described here is, for example, a lithium ion secondary battery in which the capacity of the negative electrode is expressed by insertion and extraction of lithium ions that are electrode reactants.

[Overall structure of secondary battery]
In the secondary battery, a battery element 20 having a flat winding structure is mainly accommodated in a battery can 11.

  The battery can 11 is, for example, a square exterior member. As shown in FIG. 8, the rectangular exterior member has a cross section in the longitudinal direction of a rectangular shape or a substantially rectangular shape (including a curve in part). The shape is also included. More specifically, the square-shaped exterior member is a bottomed rectangular or bottomed oval shaped container having a rectangular shape or a substantially rectangular (oval shape) opening formed by connecting arcs with straight lines. It is a member. FIG. 8 shows a case where the battery can 11 has a rectangular cross-sectional shape. Such a battery structure including the battery can 11 is called a square shape.

  The battery can 11 is made of, for example, iron, aluminum, or an alloy thereof, and may have a function as an electrode terminal. Among these, iron that is harder than aluminum is preferable in order to suppress battery swelling by utilizing the hardness (hardness of deformation) of the battery can 11 during charging and discharging. When the battery can 11 is made of iron, for example, the surface of the battery can 11 may be plated with nickel or the like.

  The battery can 11 has a hollow structure in which one end is opened and the other end is closed, and an insulating plate 12 and a battery lid 13 are attached to the open end to be sealed. The insulating plate 12 is disposed between the battery element 20 and the battery lid 13 so as to be perpendicular to the winding peripheral surface of the battery element 20, and is made of, for example, polypropylene. The battery lid 13 is made of, for example, the same material as that of the battery can 11 and may have a function as an electrode terminal.

  A terminal plate 14 serving as a positive terminal is provided outside the battery lid 13, and the terminal plate 14 is electrically insulated from the battery lid 13 through an insulating case 16. The insulating case 16 is made of, for example, polybutylene terephthalate. In addition, a through hole is provided in a substantially central portion of the battery lid 13, and the through hole is electrically connected to the terminal plate 14 and is electrically insulated from the battery lid 13 through the gasket 17. A positive electrode pin 15 is inserted as shown. The gasket 17 is made of, for example, an insulating material, and for example, asphalt is applied to the surface thereof.

  In the vicinity of the periphery of the battery lid 13, a cleavage valve 18 and an injection hole 19 are provided. The cleavage valve 18 is electrically connected to the battery lid 13, and is disconnected from the battery lid 13 to reduce the internal pressure when the internal pressure of the battery exceeds a certain level due to an internal short circuit or external heating. It is designed to be opened. The injection hole 19 is closed by a sealing member 19A made of, for example, a stainless steel ball.

  The battery element 20 is formed by laminating and winding a positive electrode 21 and a negative electrode 22 via a separator 23, and has a flat shape according to the shape of the battery can 11. A positive electrode lead 24 made of aluminum or the like is attached to an end portion (for example, an inner terminal portion) of the positive electrode 21, and a negative electrode lead 25 made of nickel or the like to an end portion (for example, the outer terminal portion) of the negative electrode 22. Is attached. The positive electrode lead 24 is welded to one end of the positive electrode pin 15 and is electrically connected to the terminal plate 14, and the negative electrode lead 25 is welded to and electrically connected to the battery can 11.

[Positive electrode]
The positive electrode 21 is, for example, one in which a positive electrode active material layer 21B is provided on both surfaces of a positive electrode current collector 21A. However, the positive electrode active material layer 21B may be provided only on one surface of the positive electrode current collector 21A.

  The positive electrode current collector 21A is made of, for example, aluminum, nickel, stainless steel, or the like.

  The positive electrode active material layer 21B includes one or more positive electrode materials capable of inserting and extracting lithium ions as a positive electrode active material, and a positive electrode binder or a positive electrode as necessary. Other materials such as a conductive agent may be included.

As the positive electrode material, a lithium-containing compound is preferable. This is because a high energy density can be obtained. Examples of the lithium-containing compound include a composite oxide containing lithium and a transition metal element as constituent elements, or a phosphate compound containing lithium and a transition metal element as constituent elements. Especially, what contains at least 1 sort (s) of cobalt, nickel, manganese, and iron as a transition metal element is preferable. This is because a higher voltage can be obtained. The chemical formula is represented by, for example, Li _x M1O ₂ or Li _y M2PO ₄ . In the formula, M1 and M2 represent one or more transition metal elements. Moreover, the values of x and y vary depending on the charge / discharge state, and are generally 0.05 ≦ x ≦ 1.10 and 0.05 ≦ y ≦ 1.10.

Examples of the composite oxide containing lithium and a transition metal element include lithium cobalt composite oxide (Li _x CoO ₂ ), lithium nickel composite oxide (Li _x NiO ₂ ), or lithium represented by the formula (12). Examples include nickel-based composite oxides. Examples of the phosphate compound containing lithium and a transition metal element include a lithium iron phosphate compound (LiFePO ₄ ) or a lithium iron manganese phosphate compound (LiFe _1-u Mn _u PO ₄ (u <1)). Is mentioned. This is because high battery capacity is obtained and excellent cycle characteristics are also obtained.

LiNi _1-x M _x O ₂ (12)
(M is cobalt, manganese, iron, aluminum, vanadium, tin, magnesium, titanium, strontium, calcium, zirconium, molybdenum, technetium, ruthenium, tantalum, tungsten, rhenium, ytterbium, copper, zinc, barium, boron, chromium, silicon And at least one of gallium, phosphorus, antimony, and niobium, and x is 0.005 <x <0.5.)

  In addition, examples of the positive electrode material include oxides, disulfides, chalcogenides, and conductive polymers. Examples of the oxide include titanium oxide, vanadium oxide, and manganese dioxide. Examples of the disulfide include titanium disulfide and molybdenum sulfide. An example of the chalcogenide is niobium selenide. Examples of the conductive polymer include sulfur, polyaniline, and polythiophene.

  Of course, the positive electrode material may be other than the above. Further, two or more kinds of the series of positive electrode materials described above may be mixed in any combination.

  Examples of the positive electrode binder include synthetic rubbers such as styrene butadiene rubber, fluorine rubber, and ethylene propylene diene, and polymer materials such as polyvinylidene fluoride. These may be single and multiple types may be mixed.

  Examples of the positive electrode conductive agent include carbon materials such as graphite, carbon black, acetylene black, and ketjen black. These may be single and multiple types may be mixed. The positive electrode conductive agent may be a metal material or a conductive polymer as long as it is a conductive material.

[Negative electrode]
In the negative electrode 22, for example, a negative electrode active material layer 22B is provided on both surfaces of a negative electrode current collector 22A. The configurations of the negative electrode current collector 22A and the negative electrode active material layer 22B are the same as the configurations of the negative electrode current collector 1 and the negative electrode active material layer 2 in the above-described negative electrode, respectively. That is, the negative electrode active material layer 22B includes a structure in which a crystalline negative electrode active material layer containing a crystalline negative electrode active material and an amorphous negative electrode active material layer containing a non-crystalline negative electrode active material are laminated in this order. Yes. In this negative electrode 22, the chargeable capacity of the negative electrode material capable of inserting and extracting lithium ions is preferably larger than the discharge capacity of the positive electrode 21. This is to prevent unintentional precipitation of lithium metal during charging.

  FIG. 9 schematically shows a planar configuration of the positive electrode 21 and the negative electrode 22 shown in FIG. In FIG. 9, the formation ranges of the positive electrode active material layer 21 </ b> B in the positive electrode 21 and the negative electrode active material layer 22 </ b> B in the negative electrode 22 are shaded.

  The positive electrode active material layer 21B is provided, for example, on a part of the surface of the positive electrode current collector 21A (for example, a central region in the longitudinal direction). On the other hand, the negative electrode active material layer 22B is provided on the entire surface of the negative electrode current collector 22A, for example. That is, the negative electrode active material layer 22B is provided on the negative electrode current collector 22A in a region facing the positive electrode active material layer 21B (opposing region R1) and a region not facing (non-opposing region R2). In this case, in the negative electrode active material layer 22B, the portion provided in the facing region R1 contributes to charging / discharging, and the portion provided in the non-facing region R2 hardly contributes to charging / discharging.

  As described above, the negative electrode active material layer 22B includes a structure in which a crystalline negative electrode active material layer and an amorphous negative electrode active material layer are stacked in this order. However, when the negative electrode active material layer 22B expands and contracts during charge and discharge, the above-described stacked structure (positional relationship between the crystalline negative electrode active material layer and the amorphous negative electrode active material layer) is disturbed due to the stress caused thereby. There is a possibility that. In this case, the non-facing region R2 is hardly affected by charging / discharging, and the laminated structure of the negative electrode active material layer 22B is maintained as it is immediately after formation. For this reason, when confirming whether the negative electrode active material layer 22B has a laminated structure, it is preferable to investigate the negative electrode active material layer 22B in the non-facing region R2. This is because whether or not the negative electrode active material layer 22B has a laminated structure can be accurately examined with good reproducibility without depending on the charge / discharge history (the presence / absence and number of times of charge / discharge).

[Separator]
The separator 23 separates the positive electrode 21 and the negative electrode 22 and allows lithium ions to pass through while preventing a short circuit due to contact between the two electrodes. The separator 23 is made of, for example, a porous film made of a synthetic resin such as polytetrafluoroethylene, polypropylene, or polyethylene, or a porous film made of ceramic. The separator 23 may be a laminate of two or more porous films.

[Electrolytes]
The separator 23 is impregnated with an electrolytic solution that is a liquid electrolyte. This electrolytic solution is obtained by dissolving an electrolyte salt in a solvent, and may contain other materials such as various additives as necessary.

  The solvent contains, for example, one or more of nonaqueous solvents such as organic solvents. A series of solvents (nonaqueous solvent) described below may be used alone or in combination of two or more.

  Examples of the non-aqueous solvent include the following. Ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, γ-butyrolactone, γ-valerolactone, 1,2-dimethoxyethane or tetrahydrofuran. Also, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, or 1,4-dioxane. Further, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethyl acetate or ethyl trimethyl acetate. Acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, N, N-dimethylformamide, N-methylpyrrolidinone or N-methyloxazolidinone. Further, N, N'-dimethylimidazolidinone, nitromethane, nitroethane, sulfolane, trimethyl phosphate or dimethyl sulfoxide. This is because excellent battery capacity, cycle characteristics, storage characteristics, and the like can be obtained.

  Among these, at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate is preferable. This is because excellent battery capacity, cycle characteristics, storage characteristics, and the like can be obtained. In this case, a high viscosity (high dielectric constant) solvent such as ethylene carbonate or propylene carbonate (for example, a relative dielectric constant ε ≧ 30) and a low viscosity solvent such as dimethyl carbonate, ethyl methyl carbonate or diethyl carbonate (for example, viscosity ≦ 1 mPas). -A combination with s) is more preferred. This is because the dissociation property of the electrolyte salt and the ion mobility are improved.

  In particular, the solvent preferably contains at least one of a halogenated chain carbonate represented by the formula (1) and a halogenated cyclic carbonate represented by the formula (2). This is because a stable protective film is formed on the surface of the negative electrode 22 at the time of charge and discharge, so that the decomposition reaction of the electrolytic solution is suppressed. “Halogenated chain carbonate ester” is a chain carbonate ester containing halogen as a constituent element, and “halogenated cyclic carbonate ester” is a cyclic carbonate ester containing halogen as a constituent element. In addition, R11-R16 in Formula (1) may be the same, and may differ. The same applies to R17 to R20 in the formula (2).

（Ｒ１１〜Ｒ１６は水素基、ハロゲン基、アルキル基あるいはハロゲン化アルキル基であり、それらのうちの少なくとも１つはハロゲン基あるいはハロゲン化アルキル基である。）

(R11 to R16 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of them is a halogen group or a halogenated alkyl group.)

（Ｒ１７〜Ｒ２０は水素基、ハロゲン基、アルキル基あるいはハロゲン化アルキル基であり、それらのうちの少なくとも１つはハロゲン基あるいはハロゲン化アルキル基である。）

(R17 to R20 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of them is a halogen group or a halogenated alkyl group.)

  The kind of halogen is not particularly limited, but among them, fluorine, chlorine or bromine is preferable, and fluorine is more preferable. This is because an effect higher than that of other halogens can be obtained. However, the number of halogens is preferably two rather than one, and may be three or more. This is because the ability to form a protective film is increased and a stronger and more stable protective film is formed, so that the decomposition reaction of the electrolytic solution is further suppressed.

  Examples of the halogenated chain carbonate represented by the formula (1) include fluoromethyl methyl carbonate, bis (fluoromethyl) carbonate, difluoromethyl methyl carbonate, and the like.

  Examples of the halogenated cyclic carbonate represented by the formula (2) include a series of compounds represented by the formula (2-1) to the formula (2-21). This halogenated cyclic carbonate includes geometric isomers.

  Among them, 4-fluoro-1,3-dioxolan-2-one represented by the formula (2-1) or 4,5-difluoro-1,3-dioxolan-2-one represented by the formula (2-3) is preferable. The latter is preferred and the latter is more preferred. In particular, 4,5-difluoro-1,3-dioxolan-2-one is preferably a trans isomer rather than a cis isomer. This is because it is easily available and a high effect can be obtained.

  Moreover, it is preferable that the solvent contains at least 1 sort (s) of the unsaturated carbon bond cyclic carbonate represented by Formula (3)-Formula (5). This is because a stable protective film is formed on the surface of the negative electrode 22 at the time of charge and discharge, so that the decomposition reaction of the electrolytic solution is suppressed. The “unsaturated carbon bond cyclic ester carbonate” is a cyclic ester carbonate having an unsaturated carbon bond.

（Ｒ２１およびＲ２２は水素基あるいはアルキル基である。）

(R21 and R22 are a hydrogen group or an alkyl group.)

（Ｒ２３〜Ｒ２６は水素基、アルキル基、ビニル基あるいはアリル基であり、それらのうちの少なくとも１つはビニル基あるいはアリル基である。）

(R23 to R26 are a hydrogen group, an alkyl group, a vinyl group, or an allyl group, and at least one of them is a vinyl group or an allyl group.)

（Ｒ２７はアルキレン基である。）

(R27 is an alkylene group.)

  The unsaturated carbon bond cyclic ester carbonate shown in Formula (3) is a vinylene carbonate compound. Examples of the vinylene carbonate-based compound include the following. Vinylene carbonate (1,3-dioxol-2-one), methyl vinylene carbonate (4-methyl-1,3-dioxol-2-one) or ethyl vinylene carbonate (4-ethyl-1,3-dioxol-2-one) ). 4,5-dimethyl-1,3-dioxol-2-one, 4,5-diethyl-1,3-dioxol-2-one, 4-fluoro-1,3-dioxol-2-one or 4- Trifluoromethyl-1,3-dioxol-2-one. Among these, vinylene carbonate is preferable. This is because it is easily available and a high effect can be obtained.

  The unsaturated carbon bond cyclic carbonate represented by the formula (4) is a vinyl ethylene carbonate compound. Examples of the vinyl carbonate-based compound include the following. Vinyl ethylene carbonate (4-vinyl-1,3-dioxolan-2-one), 4-methyl-4-vinyl-1,3-dioxolan-2-one or 4-ethyl-4-vinyl-1,3-dioxolane -2-one. Further, 4-n-propyl-4-vinyl-1,3-dioxolan-2-one, 5-methyl-4-vinyl-1,3-dioxolan-2-one, 4,4-divinyl-1,3- Dioxolan-2-one or 4,5-divinyl-1,3-dioxolan-2-one. Of these, vinyl ethylene carbonate is preferred. This is because it is easily available and a high effect can be obtained. Of course, as R23 to R26, all may be vinyl groups, all may be allyl groups, or vinyl groups and allyl groups may be mixed.

  The unsaturated carbon bond cyclic carbonate represented by the formula (5) is a methylene ethylene carbonate compound. Examples of the methylene ethylene carbonate compound include the following. 4-methylene-1,3-dioxolan-2-one, 4,4-dimethyl-5-methylene-1,3-dioxolan-2-one or 4,4-diethyl-5-methylene-1,3-dioxolane- 2-one. As this methylene ethylene carbonate compound, there may be one having two methylene groups in addition to one having one methylene group (compound shown in formula (5)).

  In addition, as unsaturated carbon bond cyclic carbonate ester, the catechol carbonate (catechol carbonate) etc. which have a benzene ring other than what was shown to Formula (3)-Formula (5) may be sufficient.

  Moreover, it is preferable that the solvent contains sultone (cyclic sulfonate ester). This is because the chemical stability of the electrolytic solution is further improved. Examples of sultone include propane sultone and propene sultone. The content of sultone in the solvent is, for example, 0.5% by weight or more and 5% by weight or less.

  Furthermore, it is preferable that the solvent contains an acid anhydride. This is because the chemical stability of the electrolytic solution is further improved. Examples of the acid anhydride include carboxylic acid anhydride, disulfonic acid anhydride, and anhydride of carboxylic acid and sulfonic acid. Examples of the carboxylic acid anhydride include succinic anhydride, glutaric anhydride, and maleic anhydride. Examples of the disulfonic anhydride include ethane disulfonic anhydride and propane disulfonic anhydride. Examples of the anhydride of carboxylic acid and sulfonic acid include anhydrous sulfobenzoic acid, anhydrous sulfopropionic acid, and anhydrous sulfobutyric acid. The content of the acid anhydride in the solvent is, for example, 0.5% by weight or more and 5% by weight or less.

  The electrolyte salt includes, for example, any one or more of light metal salts such as lithium salts. The series of electrolyte salts described below may be used alone or in combination of two or more.

Examples of the lithium salt include the following. Lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate or lithium hexafluoroarsenate. Further, lithium tetraphenylborate (LiB (C ₆ H ₅ ) ₄ ), lithium methanesulfonate (LiCH ₃ SO ₃ ), lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ) or lithium tetrachloroaluminate (LiAlCl ₄ ) It is. Further, dilithium hexafluorosilicate (Li ₂ SiF ₆ ), lithium chloride (LiCl) or lithium bromide (LiBr). This is because excellent battery capacity, cycle characteristics, storage characteristics, and the like can be obtained.

  Among these, at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, and lithium hexafluoroarsenate is preferable, and lithium hexafluorophosphate is more preferable. This is because a higher effect can be obtained because the internal resistance is lowered.

  In particular, the electrolyte salt preferably contains at least one of the compounds represented by the formulas (6) to (8). This is because a higher effect can be obtained. In addition, R31 and R33 of Formula (6) may be the same or different. The same applies to R41 to R43 in formula (7) and R51 and R52 in formula (8).

（Ｘ３１は長周期型周期表における１族元素あるいは２族元素、またはアルミニウムである。Ｍ３１は遷移金属元素、または長周期型周期表における１３族元素、１４族元素あるいは１５族元素である。Ｒ３１はハロゲン基である。Ｙ３１は−（Ｏ＝）Ｃ−Ｒ３２−Ｃ（＝Ｏ）−、−（Ｏ＝）Ｃ−Ｃ（Ｒ３３）₂ −あるいは−（Ｏ＝）Ｃ−Ｃ（＝Ｏ）−である。ただし、Ｒ３２はアルキレン基、ハロゲン化アルキレン基、アリーレン基あるいはハロゲン化アリーレン基である。Ｒ３３はアルキル基、ハロゲン化アルキル基、アリール基あるいはハロゲン化アリール基である。なお、ａ３は１〜４の整数であり、ｂ３は０、２あるいは４であり、ｃ３、ｄ３、ｍ３およびｎ３は１〜３の整数である。）

(X31 is a group 1 element or group 2 element in the long-period periodic table, or aluminum. M31 is a transition metal element, or a group 13 element, group 14 element, or group 15 element in the long-period periodic table. R31 Y31 is — (O═) C—R32—C (═O) —, — (O═) C—C (R33) ₂ — or — (O═) C—C (═O) Where R32 is an alkylene group, a halogenated alkylene group, an arylene group or a halogenated arylene group, R33 is an alkyl group, a halogenated alkyl group, an aryl group or a halogenated aryl group, and a3 is (It is an integer of 1 to 4, b3 is 0, 2 or 4, and c3, d3, m3 and n3 are integers of 1 to 3.)

（Ｘ４１は長周期型周期表における１族元素あるいは２族元素である。Ｍ４１は遷移金属元素、または長周期型周期表における１３族元素、１４族元素あるいは１５族元素である。Ｙ４１は−（Ｏ＝）Ｃ−（Ｃ（Ｒ４１）₂ ）_b4−Ｃ（＝Ｏ）−、−（Ｒ４３）₂ Ｃ−（Ｃ（Ｒ４２）₂ ）_c4−Ｃ（＝Ｏ）−、−（Ｒ４３）₂ Ｃ−（Ｃ（Ｒ４２）₂ ）_c4−Ｃ（Ｒ４３）₂ −、−（Ｒ４３）₂ Ｃ−（Ｃ（Ｒ４２）₂ ）_c4−Ｓ（＝Ｏ）₂ −、−（Ｏ＝）₂ Ｓ−（Ｃ（Ｒ４２）₂ ）_d4−Ｓ（＝Ｏ）₂ −あるいは−（Ｏ＝）Ｃ−（Ｃ（Ｒ４２）₂ ）_d4−Ｓ（＝Ｏ）₂ −である。ただし、Ｒ４１およびＲ４３は水素基、アルキル基、ハロゲン基あるいはハロゲン化アルキル基であり、それぞれのうちの少なくとも１つはハロゲン基あるいはハロゲン化アルキル基である。Ｒ４２は水素基、アルキル基、ハロゲン基あるいはハロゲン化アルキル基である。なお、ａ４、ｅ４およびｎ４は１あるいは２であり、ｂ４およびｄ４は１〜４の整数であり、ｃ４は０〜４の整数であり、ｆ４およびｍ４は１〜３の整数である。）

(X41 is a group 1 element or group 2 element in the long periodic table. M41 is a transition metal element, or a group 13, element or group 15 element in the long period periodic table. Y41 is − ( O =) C- (C (R41 ) 2) b4 -C (= O) -, - (R43) 2 C- (C (R42) 2) c4 -C (= O) -, - (R43) 2 C -(C (R42) ₂ ) _c4 -C (R43) ₂ -,-(R43) ₂ C- (C (R42) ₂ ) _c4 -S (= O) ₂ -,-(O =) ₂ S- ( C (R42) ₂ ) _d4- S (= O) _2- or-(O =) C- (C (R42) ₂ ) _d4- S (= O) _2- where R41 and R43 are hydrogen groups. , An alkyl group, a halogen group, or a halogenated alkyl group, and at least one of each is a halogen group or a halogenated alkyl group. R42 is a hydrogen group, an alkyl group, a halogen group or a halogenated alkyl group, wherein a4, e4 and n4 are 1 or 2, b4 and d4 are integers of 1 to 4, and c4 Is an integer from 0 to 4, and f4 and m4 are integers from 1 to 3.)

（Ｘ５１は長周期型周期表における１族元素あるいは２族元素である。Ｍ５１は遷移金属元素、または長周期型周期表における１３族元素、１４族元素あるいは１５族元素である。Ｒｆはフッ素化アルキル基あるいはフッ素化アリール基であり、いずれの炭素数も１〜１０である。Ｙ５１は−（Ｏ＝）Ｃ−（Ｃ（Ｒ５１）₂ ）_d5−Ｃ（＝Ｏ）−、−（Ｒ５２）₂ Ｃ−（Ｃ（Ｒ５１）₂ ）_d5−Ｃ（＝Ｏ）−、−（Ｒ５２）₂ Ｃ−（Ｃ（Ｒ５１）₂ ）_d5−Ｃ（Ｒ５２）₂ −、−（Ｒ５２）₂ Ｃ−（Ｃ（Ｒ５１）₂ ）_d5−Ｓ（＝Ｏ）₂ −、−（Ｏ＝）₂ Ｓ−（Ｃ（Ｒ５１）₂ ）_e5−Ｓ（＝Ｏ）₂ −あるいは−（Ｏ＝）Ｃ−（Ｃ（Ｒ５１）₂ ）_e5−Ｓ（＝Ｏ）₂ −である。ただし、Ｒ５１は水素基、アルキル基、ハロゲン基あるいはハロゲン化アルキル基である。Ｒ５２は水素基、アルキル基、ハロゲン基あるいはハロゲン化アルキル基であり、そのうちの少なくとも１つはハロゲン基あるいはハロゲン化アルキル基である。なお、ａ５、ｆ５およびｎ５は１あるいは２であり、ｂ５、ｃ５およびｅ５は１〜４の整数であり、ｄ５は０〜４の整数であり、ｇ５およびｍ５は１〜３の整数である。）

(X51 is a group 1 element or group 2 element in the long-period periodic table. M51 is a transition metal element, or a group 13, element or group 15 element in the long-period periodic table. Rf is fluorinated. An alkyl group or a fluorinated aryl group, each having 1 to 10 carbon atoms Y51 is — (O═) C— (C (R51) ₂ ) _d5 —C (═O) —, — (R52); ₂ C- (C (R51) ₂ ) _d5 -C (= O)-,-(R52) ₂ C- (C (R51) ₂ ) _d5 -C (R52) ₂ -,-(R52) ₂ C- ( _{C (R51) 2) d5 -S} (= O) 2 -, - (O =) 2 S- (C (R51) 2) e5 -S (= O) 2 - or - (O =) C- (C _{(R51) 2) e5 -S (} = O) 2 -. is, however, R51 is a hydrogen group, an alkyl group, a halogen group, or a halogen Kaa R52 is a hydrogen group, an alkyl group, a halogen group or a halogenated alkyl group, at least one of which is a halogen group or a halogenated alkyl group, wherein a5, f5 and n5 are 1 or 2; B5, c5 and e5 are integers of 1 to 4, d5 is an integer of 0 to 4, and g5 and m5 are integers of 1 to 3.)

  Group 1 elements are hydrogen, lithium, sodium, potassium, rubidium, cesium, and francium. Group 2 elements are beryllium, magnesium, calcium, strontium, barium and radium. Group 13 elements are boron, aluminum, gallium, indium and thallium. Group 14 elements are carbon, silicon, germanium, tin and lead. Group 15 elements are nitrogen, phosphorus, arsenic, antimony and bismuth.

  Examples of the compound represented by the formula (6) include compounds represented by the formula (6-1) to the formula (6-6). Examples of the compound represented by formula (7) include compounds represented by formula (7-1) to formula (7-8). Examples of the compound represented by the formula (8) include a compound represented by the formula (8-1). Needless to say, the compounds are not limited to the above-described compounds as long as they have the structures shown in the formulas (6) to (8).

  Moreover, it is preferable that electrolyte salt contains at least 1 sort (s) of the compounds represented by Formula (9)-Formula (11). This is because a higher effect can be obtained. In addition, m and n in Formula (9) may be the same or different. The same applies to p, q and r in the formula (11).

_{LiN (C m F 2m + 1} SO 2) (C n F 2n + 1 SO 2) ... (9)
(M and n are integers of 1 or more.)

（Ｒ６１は炭素数が２以上４以下の直鎖状あるいは分岐状のパーフルオロアルキレン基である。）

(R61 is a linear or branched perfluoroalkylene group having 2 to 4 carbon atoms.)

LiC (C _p F _{2p + 1} SO ₂ ) (C _q F _{2q + 1} SO ₂ ) (C _r F _{2r + 1} SO ₂ ) (11)
(P, q and r are integers of 1 or more.)

The compound represented by the formula (9) is a chain imide compound, and examples of such a compound include the following. Bis (trifluoromethanesulfonyl) imide lithium (LiN (CF ₃ SO ₂ ) ₂ ) or bis (pentafluoroethanesulfonyl) imide lithium (LiN (C ₂ F ₅ SO ₂ ) ₂ ). Further, it is (trifluoromethanesulfonyl) (pentafluoroethanesulfonyl) imidolithium (LiN (CF ₃ SO ₂ ) (C ₂ F ₅ SO ₂ )). Further, it is (trifluoromethanesulfonyl) (heptafluoropropanesulfonyl) imidolithium (LiN (CF ₃ SO ₂ ) (C ₃ F ₇ SO ₂ )). Further, (trifluoromethanesulfonyl) (nonafluorobutanesulfonyl) imidolithium (LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ )).

  The compound represented by Formula (10) is a cyclic imide compound, and examples of such a compound include compounds represented by Formula (10-1) to Formula (10-4).

The compound represented by the formula (11) is a chain-like methide compound, and examples of such a compound include lithium tris (trifluoromethanesulfonyl) methide (LiC (CF ₃ SO ₂ ) ₃ ).

  The content of the electrolyte salt is preferably 0.3 mol / kg or more and 3.0 mol / kg or less with respect to the solvent. This is because high ionic conductivity is obtained.

[Operation of secondary battery]
In this secondary battery, at the time of charging, for example, lithium ions are released from the positive electrode 21 and inserted in the negative electrode 22 through the electrolytic solution impregnated in the separator 23. On the other hand, at the time of discharging, for example, lithium ions are released from the negative electrode 22 and inserted in the positive electrode 21 through the electrolytic solution impregnated in the separator 23.

[Method for producing secondary battery]
This secondary battery is manufactured by the following procedure, for example.

  First, the positive electrode 21 is produced. First, a positive electrode active material, a positive electrode binder, and a positive electrode conductive agent are mixed to form a positive electrode mixture, and then dispersed in an organic solvent to obtain a paste-like positive electrode mixture slurry. Subsequently, the positive electrode mixture slurry is uniformly applied to both surfaces of the positive electrode current collector 21A using a doctor blade or a bar coater, and then dried to form the positive electrode active material layer 21B. Finally, the positive electrode active material layer 21B is compression-molded using a roll press or the like while being heated as necessary. In this case, compression molding may be repeated a plurality of times.

  Next, the negative electrode 22 is manufactured according to the negative electrode manufacturing procedure described above. In this case, the negative electrode active material layer 22B is formed by forming a crystalline negative electrode active material layer and an amorphous negative electrode active material layer in this order on both surfaces of the negative electrode current collector 22A.

  The secondary battery is assembled as follows. First, after storing the battery element 20 in the battery can 11, the insulating plate 12 is disposed on the battery element 20. Subsequently, the positive electrode lead 24 is connected to the positive electrode pin 15 by welding or the like, and the negative electrode lead 25 is connected to the battery can 11 by welding or the like, and then the battery lid is attached to the open end of the battery can 11 by laser welding or the like. 13 is fixed. Finally, after injecting the electrolyte into the battery can 11 from the injection hole 19 and impregnating the separator 23, the injection hole 19 is closed with a sealing member 19A. Thereby, the secondary battery shown in FIGS. 7 and 8 is completed.

  According to the first secondary battery, the negative electrode 22 has the same configuration as the negative electrode described above. For this reason, the physical properties of the negative electrode active material are less likely to change with time, and adhesion that can withstand stress due to expansion and contraction of the negative electrode active material layer 22B is maintained during charging and discharging. Further, the diffusibility of lithium ions is improved, and the reactivity of the negative electrode 22 with respect to the electrolytic solution is reduced. Therefore, excellent cycle characteristics and swelling characteristics can be obtained.

  In particular, if the solvent of the electrolytic solution contains at least one of halogenated chain carbonate, halogenated cyclic carbonate, unsaturated carbon bond cyclic carbonate, sultone, and acid anhydride, cycle characteristics are further improved. Can be made.

  Moreover, electrolyte salt of electrolyte solution is lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, and the compound shown in Formula (6)-Formula (11) If at least one kind is included, cycle characteristics can be further improved.

<2-2. Second secondary battery>
10 and 11 show a cross-sectional configuration of the second secondary battery, and FIG. 11 shows an enlarged part of the spirally wound electrode body 40 shown in FIG.

  This secondary battery is a lithium ion secondary battery as in the case of the first secondary battery, and mainly includes a wound electrode body 40 and a pair of insulating plates 32 inside a substantially hollow cylindrical battery can 31. , 33 are stored. A battery structure using such a battery can 31 is called a cylindrical type.

  The battery can 31 is made of, for example, the same material as that of the battery can 11 in the first secondary battery. One end of the battery can 31 is open and the other end is closed. The pair of insulating plates 32 and 33 are arranged so as to sandwich the wound electrode body 40 from above and below and to extend perpendicular to the wound peripheral surface.

  A battery lid 34, a safety valve mechanism 35 and a heat sensitive resistance element (Positive Temperature Coefficient: PTC element) 36 provided inside thereof are caulked through a gasket 37 at the open end of the battery can 31. By this caulking, the inside of the battery can 31 is sealed. The battery lid 34 is made of, for example, the same material as the battery can 31. The safety valve mechanism 35 is electrically connected to the battery lid 34 via the heat sensitive resistance element 36. In the safety valve mechanism 35, when the internal pressure becomes a certain level or more due to an internal short circuit or external heating, the disk plate 35A is reversed and the electric power between the battery lid 34 and the wound electrode body 40 is reversed. Connection is cut off. The heat-sensitive resistance element 36 has a resistance that increases with an increase in temperature and limits the current to prevent abnormal heat generation due to a large current. The gasket 37 is made of, for example, an insulating material, and for example, asphalt is applied to the surface thereof.

  The wound electrode body 40 is obtained by laminating and winding a positive electrode 41 and a negative electrode 42 with a separator 43 interposed therebetween. For example, a center pin 44 is inserted in the center of the wound electrode body 40. In this wound electrode body 40, a positive electrode lead 45 made of aluminum or the like is connected to the positive electrode 41, and a negative electrode lead 46 made of nickel or the like is connected to the negative electrode 42. The positive electrode lead 45 is welded to the safety valve mechanism 35 and electrically connected to the battery lid 34, and the negative electrode lead 46 is welded to the battery can 31 and electrically connected thereto.

  In the positive electrode 41, for example, a positive electrode active material layer 41B is provided on both surfaces of a positive electrode current collector 41A. The configurations of the positive electrode current collector 41A and the positive electrode active material layer 41B are the same as the configurations of the positive electrode current collector 21A and the positive electrode active material layer 21B in the first secondary battery, respectively.

  In the negative electrode 42, for example, a negative electrode active material layer 42B is provided on both surfaces of a negative electrode current collector 42A. The configurations of the negative electrode current collector 42A and the negative electrode active material layer 42B are the same as the configurations of the negative electrode current collector 22A and the negative electrode active material layer 22B in the first secondary battery, respectively. That is, the negative electrode active material layer 42B includes a structure in which a crystalline negative electrode active material layer containing a crystalline negative electrode active material and an amorphous negative electrode active material layer containing a non-crystalline negative electrode active material are laminated in this order. Yes.

  The configuration of the separator 43 and the composition of the electrolytic solution are the same as the configuration of the separator 23 and the composition of the electrolytic solution in the first secondary battery, respectively.

  In this secondary battery, at the time of charging, for example, lithium ions are released from the positive electrode 41 and inserted in the negative electrode 42 through the electrolytic solution. On the other hand, at the time of discharge, for example, lithium ions are released from the negative electrode 42 and inserted in the positive electrode 41 through the electrolytic solution.

  This secondary battery is manufactured by the following procedure, for example.

  First, according to the same procedure as the positive electrode 21 and the negative electrode 22 in the first secondary battery, the positive electrode active material layer 41B is formed on both surfaces of the positive electrode current collector 41A to produce the positive electrode 41, and the negative electrode current collector 42A The negative electrode 42 is fabricated by forming the negative electrode active material layer 42B on both sides. Subsequently, the positive electrode lead 45 is attached to the positive electrode 41 by welding or the like, and the negative electrode lead 46 is attached to the negative electrode 42 by welding or the like. Subsequently, the positive electrode 41 and the negative electrode 42 are stacked and wound through the separator 43 to produce the wound electrode body 40, and then the center pin 44 is inserted into the winding center. Subsequently, the wound electrode body 40 is accommodated in the battery can 31 while being sandwiched between the pair of insulating plates 32 and 33. In this case, the tip of the positive electrode lead 45 is welded to the safety valve mechanism 35 and the tip of the negative electrode lead 46 is welded to the battery can 31. Subsequently, an electrolytic solution is injected into the battery can 31 and impregnated in the separator 43. Finally, the battery lid 34, the safety valve mechanism 35, and the heat sensitive resistance element 36 are caulked to the opening end of the battery can 31 via the gasket 37. Thereby, the secondary battery shown in FIGS. 10 and 11 is completed.

  According to the second secondary battery, since the negative electrode 42 has the same configuration as the negative electrode described above, excellent cycle characteristics and swelling characteristics can be obtained by the same action as the first secondary battery. Can do. Other effects relating to the secondary battery are the same as those of the first secondary battery.

<2-3. Third secondary battery>
FIG. 12 shows an exploded perspective configuration of the third secondary battery, and FIG. 13 shows an enlarged cross section taken along line XIII-XIII of the spirally wound electrode body 50 shown in FIG.

  This secondary battery is a lithium ion secondary battery, like the first secondary battery, and is mainly a wound electrode in which a positive electrode lead 51 and a negative electrode lead 52 are attached inside a film-like exterior member 60. The body 50 is stored. A battery structure using such an exterior member 60 is called a laminate film type.

  The positive electrode lead 51 and the negative electrode lead 52 are led out in the same direction from the inside of the exterior member 60 to the outside, for example. However, the installation position of the positive electrode lead 51 and the negative electrode lead 52 with respect to the spirally wound electrode body 50 and the direction in which they are derived are not particularly limited. The positive electrode lead 51 is made of, for example, aluminum, and the negative electrode lead 52 is made of, for example, copper, nickel, stainless steel, or the like. These materials have, for example, a thin plate shape or a mesh shape.

  The exterior member 60 is, for example, a laminate film in which a fusion layer, a metal layer, and a surface protective layer are laminated in this order. In this case, for example, the outer edges of the fusion layers of the two films are bonded to each other with an adhesive or the like so that the fusion layer faces the wound electrode body 50. Examples of the fusion layer include a film of polyethylene or polypropylene. Examples of the metal layer include aluminum foil. Examples of the surface protective layer include films of nylon or polyethylene terephthalate.

  Especially, as the exterior member 60, an aluminum laminated film in which a polyethylene film, an aluminum foil, and a nylon film are laminated in this order is preferable. However, the exterior member 60 may be a laminated film having another laminated structure instead of the aluminum laminated film, or may be a polymer film such as polypropylene or a metal film.

  An adhesion film 61 is inserted between the exterior member 60 and the positive electrode lead 51 and the negative electrode lead 52 to prevent the outside air from entering. The adhesion film 61 is made of a material having adhesion to the positive electrode lead 51 and the negative electrode lead 52. Examples of such a material include polyolefin resins such as polyethylene, polypropylene, modified polyethylene, and modified polypropylene.

  The wound electrode body 50 is obtained by laminating and winding a positive electrode 53 and a negative electrode 54 via a separator 55 and an electrolyte layer 56, and the outermost peripheral portion thereof is protected by a protective tape 57.

  In the positive electrode 53, for example, the positive electrode active material layer 53B is provided on both surfaces of the positive electrode current collector 53A. The configurations of the positive electrode current collector 53A and the positive electrode active material layer 53B are the same as those of the positive electrode current collector 21A and the positive electrode active material layer 21B in the first secondary battery, respectively.

  In the negative electrode 54, for example, a negative electrode active material layer 54B is provided on both surfaces of a negative electrode current collector 54A. The configurations of the negative electrode current collector 54A and the negative electrode active material layer 54B are the same as the configurations of the negative electrode current collector 22A and the negative electrode active material layer 22B in the first secondary battery, respectively. That is, the negative electrode active material layer 54B includes a structure in which a crystalline negative electrode active material layer containing a crystalline negative electrode active material and an amorphous negative electrode active material layer containing a non-crystalline negative electrode active material are laminated in this order. Yes.

  The configuration of the separator 55 is the same as the configuration of the separator 23 in the first secondary battery.

  The electrolyte layer 56 is one in which an electrolytic solution is held by a polymer compound, and may contain other materials such as various additives as necessary. The electrolyte layer 56 is a so-called gel electrolyte. A gel electrolyte is preferable because high ion conductivity (for example, 1 mS / cm or more at room temperature) is obtained and leakage of the electrolyte is prevented.

  Examples of the polymer compound include the following. Polyacrylonitrile, polyvinylidene fluoride, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, polyphosphazene, polysiloxane, or polyvinyl fluoride. Polyvinyl acetate, polyvinyl alcohol, polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, styrene-butadiene rubber, nitrile-butadiene rubber, polystyrene or polycarbonate. Further, it is a copolymer of vinylidene fluoride and hexafluoropyrene. These may be single and multiple types may be mixed. Among these, polyvinylidene fluoride or a copolymer of vinylidene fluoride and hexafluoropyrene is preferable. This is because it is electrochemically stable.

  The composition of the electrolytic solution is the same as the composition of the electrolytic solution in the first secondary battery. However, in the electrolyte layer 56 which is a gel electrolyte, the solvent of the electrolytic solution is a wide concept including not only a liquid solvent but also a material having ion conductivity capable of dissociating the electrolyte salt. Therefore, when using a polymer compound having ion conductivity, the polymer compound is also included in the solvent.

  Instead of the gel electrolyte layer 56 in which the electrolyte is held by the polymer compound, the electrolyte may be used as it is. In this case, the separator 55 is impregnated with the electrolytic solution.

  In this secondary battery, during charging, for example, lithium ions are released from the positive electrode 53 and inserted into the negative electrode 54 via the electrolyte layer 56. On the other hand, at the time of discharging, for example, lithium ions are released from the negative electrode 54 and inserted in the positive electrode 53 through the electrolyte layer 56.

  The secondary battery provided with the gel electrolyte layer 56 is manufactured by, for example, the following three types of procedures.

  In the first manufacturing method, first, the positive electrode 53 and the negative electrode 54 are manufactured by the same manufacturing procedure as that of the positive electrode 21 and the negative electrode 22 in the first secondary battery. Specifically, the positive electrode active material layer 53B is formed on both surfaces of the positive electrode current collector 53A to produce the positive electrode 53, and the negative electrode active material layer 54B is formed on both surfaces of the negative electrode current collector 54A to produce the negative electrode 54. To do. Then, after preparing the precursor solution containing electrolyte solution, a high molecular compound, and a solvent and apply | coating to the positive electrode 53 and the negative electrode 54, the solvent is volatilized and the gel electrolyte layer 56 is formed. Subsequently, the positive electrode lead 51 is attached to the positive electrode current collector 53A by welding or the like, and the negative electrode lead 52 is attached to the negative electrode current collector 54A by welding or the like. Subsequently, the positive electrode 53 and the negative electrode 54 on which the electrolyte layer 56 is formed are stacked and wound via a separator 55, and then a protective tape 57 is adhered to the outermost peripheral portion thereof to produce the wound electrode body 50. . Finally, after sandwiching the wound electrode body 50 between the two film-shaped exterior members 60, the outer edges of the exterior member 60 are bonded to each other by heat fusion or the like, and the wound electrode body 50 is enclosed. To do. At this time, the adhesion film 61 is inserted between the positive electrode lead 51 and the negative electrode lead 52 and the exterior member 60. Thereby, the secondary battery shown in FIGS. 12 and 13 is completed.

  In the second manufacturing method, first, the positive electrode lead 51 is attached to the positive electrode 53 and the negative electrode lead 52 is attached to the negative electrode 54. Subsequently, after the positive electrode 53 and the negative electrode 54 are laminated and wound via the separator 55, a protective tape 57 is adhered to the outermost periphery thereof, and a wound body that is a precursor of the wound electrode body 50. Is made. Subsequently, after sandwiching the wound body between the two film-like exterior members 60, the remaining outer peripheral edge portion excluding the outer peripheral edge portion on one side is adhered by heat fusion or the like, and the bag-shaped exterior The wound body is accommodated in the member 60. Subsequently, an electrolyte composition containing an electrolytic solution, a monomer that is a raw material of the polymer compound, a polymerization initiator, and other materials such as a polymerization inhibitor as necessary is prepared to form a bag-shaped exterior member. After injecting into the inside of 60, the opening part of the exterior member 60 is sealed by heat sealing or the like. Finally, the monomer is thermally polymerized to obtain a polymer compound, and the gel electrolyte layer 56 is formed. Thereby, the secondary battery is completed.

  In the third manufacturing method, a wound body is formed by forming a wound body in the same manner as the above-described second manufacturing method, except that the separator 55 coated with the polymer compound on both sides is used first. 60 is housed inside. Examples of the polymer compound applied to the separator 55 include a polymer (such as a homopolymer, a copolymer, or a multi-component copolymer) containing vinylidene fluoride as a component. Specifically, polyvinylidene fluoride, a binary copolymer containing vinylidene fluoride and hexafluoropropylene as components, and a ternary copolymer containing vinylidene fluoride, hexafluoropropylene and chlorotrifluoroethylene as components. Such as coalescence. In addition, the high molecular compound may contain the other 1 type, or 2 or more types of high molecular compound with the polymer which uses the above-mentioned vinylidene fluoride as a component. Subsequently, after the electrolytic solution is prepared and injected into the exterior member 60, the opening of the exterior member 60 is sealed by thermal fusion or the like. Finally, the exterior member 60 is heated while applying a load, and the separator 55 is brought into close contact with the positive electrode 53 and the negative electrode 54 through the polymer compound. Thereby, the electrolytic solution is impregnated into the polymer compound, and the polymer compound is gelled to form the electrolyte layer 56, whereby the secondary battery is completed.

  In the third manufacturing method, battery swelling is suppressed more than in the first manufacturing method. Further, in the third manufacturing method, almost no monomer or solvent, which is a raw material for the polymer compound, remains in the electrolyte layer 56 as compared with the second manufacturing method, and the formation process of the polymer compound is better controlled. . For this reason, sufficient adhesion is obtained between the positive electrode 53, the negative electrode 54 and the separator 55 and the electrolyte layer 56.

  According to the third secondary battery, since the negative electrode 54 has the same configuration as the negative electrode described above, excellent cycle characteristics and swelling characteristics can be obtained by the same action as the first secondary battery. Can do. Other effects relating to the secondary battery are the same as those of the first secondary battery.

  Examples of the present invention will be described in detail.

(Experimental Examples 1-1 to 1-10)
The laminate film type lithium ion secondary battery shown in FIGS. 12 and 13 was produced by the following procedure.

  First, the positive electrode active material layer 53B was formed on the positive electrode current collector 53A using a coating method, and the positive electrode 53 was manufactured.

In this case, lithium carbonate (Li ₂ CO ₃ ) and cobalt carbonate (CoCO ₃ ) are first mixed at a molar ratio of 0.5: 1, and then calcined in air at 900 ° C. for 5 hours. A cobalt composite oxide (LiCoO ₂ ) was obtained. Subsequently, 91 parts by mass of lithium cobalt composite oxide as a positive electrode active material, 6 parts by mass of graphite as a positive electrode conductive agent, and 3 parts by mass of polyvinylidene fluoride as a positive electrode binder were mixed to obtain a positive electrode mixture. Subsequently, the positive electrode mixture was dispersed in N-methyl-2-pyrrolidone to obtain a paste-like positive electrode mixture slurry. Subsequently, the positive electrode mixture slurry was uniformly applied to both surfaces of the positive electrode current collector 53A using a coating apparatus, and then dried to form the positive electrode active material layer 53B. As the positive electrode current collector 53A, a strip-shaped aluminum foil (thickness = 12 μm) was used. Finally, the positive electrode active material layer 53B was compression molded using a roll press.

  Next, a negative electrode active material layer 54B including a crystalline negative electrode active material layer and an amorphous negative electrode active material layer was formed on the negative electrode current collector 54A, so that the negative electrode 54 was produced.

  In this case, first, a silicon powder as a negative electrode material is sprayed in a molten state or a semi-molten state on both surfaces of the negative electrode current collector 54A using a thermal spraying method (gas flame spraying method), and a plurality of particulate negative electrode active materials are sprayed. A crystalline negative electrode active material layer containing the material (crystalline) was formed. As the negative electrode current collector 54A, a strip-shaped electrolytic copper foil (thickness = 15 μm, surface ten-point average roughness Rz = 3 μm) was used. As the silicon powder, one having a median diameter of 1 μm to 300 μm was used. In the thermal spraying process, oxygen gas and hydrogen gas were used as the gas for generating the thermal spray flame, nitrogen gas was used as the gas for spraying the negative electrode material, and the spraying speed was about 45 m / second or more and 55 m / second or less. Further, a spraying process was performed while cooling the substrate with carbon dioxide gas so that the negative electrode current collector 54A was not thermally damaged. Further, oxygen gas and water vapor as necessary were continuously introduced into the chamber, so that the oxygen content in the crystalline negative electrode active material was 5 atomic%.

  Subsequently, silicon is deposited as a negative electrode material on the surface of the crystalline negative electrode active material layer using a vapor deposition method (electron beam vapor deposition method), so that the non-crystalline property includes a plurality of particulate negative electrode active materials (non-crystalline). A negative electrode active material layer was formed. In the vapor deposition process, silicon having a purity of 99% was used as a deflection electron beam vapor deposition source, and the deposition rate was set to 100 nm / second. In addition, oxygen gas and water vapor as necessary were continuously introduced into the chamber, so that the oxygen content in the amorphous negative electrode active material was 5 atomic%.

  In particular, when forming a crystalline negative electrode active material layer, the median diameter, input amount and melting temperature of the negative electrode material, and the cooling temperature of the substrate were adjusted so as to satisfy the following setting conditions. First, the plurality of particulate negative electrode active materials are made to contain flat particles. Second, the half width (2θ) of the diffraction peak on the (111) crystal plane of the crystalline negative electrode active material obtained by X-ray diffraction was 1 °, and the crystallite size attributable to the crystal plane was 400 nm. In this case, an X-ray diffractometer (Ryukyu Electric Co., Ltd .: CuKa) manufactured by Rigaku Electric Co., Ltd. is used. ≦ 90 °. Note that the setting conditions described above were examined for the negative electrode active material layer 54B in the non-facing region R2 described with reference to FIG.

  When the negative electrode active material layer 54B is formed, the total thickness (the total of the thickness T1 of the crystalline negative electrode active material layer and the thickness T2 of the amorphous negative electrode active material layer) is set to 15 μm. As shown in FIG. 1, the thickness ratio (T1 / (T1 + T2)) was changed. The procedure for calculating the thickness ratio is as described for the negative electrode.

Next, after mixing ethylene carbonate (EC) and diethyl carbonate (DEC) as a solvent, lithium hexafluorophosphate (LiPF ₆ ) was dissolved as an electrolyte salt to prepare a liquid electrolyte (electrolytic solution). . In this case, the composition of the solvent (EC: DEC) was 50:50 by weight, and the content of the electrolyte salt was 1 mol / kg with respect to the solvent.

  Finally, a secondary battery was assembled using the electrolytic solution together with the positive electrode 53 and the negative electrode 54. First, the positive electrode lead 51 made of aluminum was welded to one end of the positive electrode current collector 53A, and the negative electrode lead 52 made of nickel was welded to one end of the negative electrode current collector 54A. Subsequently, after the positive electrode 53, the separator 55, the negative electrode 54, and the separator 55 are laminated in this order and wound in the longitudinal direction, the winding end portion is fixed with the protective tape 57 made of an adhesive tape, A wound body that is a precursor of the wound electrode body 50 was formed. As the separator 55, a three-layer structure (thickness = 23 μm) in which a film mainly composed of porous polyethylene was sandwiched between films mainly composed of porous polypropylene. Subsequently, after the wound body was sandwiched between the exterior members 60, the outer edge portions except for one side were heat-sealed, and the wound body was accommodated in the bag-shaped exterior member 60. As the exterior member 60, a laminate having a three-layer structure in which a nylon film (thickness = 30 μm), an aluminum foil (thickness = 40 μm), and an unstretched polypropylene film (thickness = 30 μm) are laminated from the outside. A film (total thickness = 100 μm) was used. Subsequently, an electrolytic solution was injected from the opening of the exterior member 60 and impregnated in the separator 55, thereby manufacturing the wound electrode body 50. Finally, the laminated film type secondary battery was completed by thermally sealing and sealing the opening of the exterior member 60 in a vacuum atmosphere. In the production of this secondary battery, the thickness of the positive electrode active material layer 53B was adjusted so that lithium metal did not deposit on the negative electrode 54 during full charge.

(Experimental Examples 1-11 to 1-14)
As shown in Table 2, the same procedure as in Experimental Examples 1-1 to 1-10 was performed, except that only one of the crystalline negative electrode active material layer and the amorphous negative electrode active material layer was formed. In this case, as a method for forming the amorphous negative electrode active material layer, a sputtering method or a CVD method was used in addition to the vapor deposition method. In the sputtering process (RF magnetron sputtering), silicon having a purity of 99.99% was used as a target, and the deposition rate was set to 0.5 nm / second. In the CVD process, silane (SiH ₄ ) gas was used as the raw material, argon (Ar) gas was used as the excitation gas, the deposition rate was 1.5 nm / second, and the substrate temperature was 200 ° C.

  When the cycle characteristics and the swollenness characteristics of the secondary batteries of Examples 1-1 to 1-14 were examined, the results shown in Tables 1 and 2 and FIG. 14 were obtained.

When examining the cycle characteristics, a cycle test was conducted to determine the discharge capacity retention rate. First, in order to stabilize the battery state, the battery was charged and discharged for 1 cycle in an atmosphere at 23 ° C., then charged and discharged again, and the discharge capacity at the second cycle was measured. Subsequently, 99 cycles were charged and discharged in the same atmosphere, and the discharge capacity at the 101st cycle was measured. Finally, discharge capacity retention ratio (%) = (discharge capacity at the 101st cycle / discharge capacity at the second cycle) × 100 was calculated. In this case, charging was performed at a constant current density of 3 mA / cm ² until the battery voltage reached 4.2 V, and then charging was performed at a constant voltage of 4.2 V until the current density reached 0.3 mA / cm ² . . The battery was discharged at a constant current density of 3 mA / cm ² until the battery voltage reached 2.5V.

  When investigating the swollenness characteristics, the swollenness ratio during the above cycle test was determined. That is, after measuring the thickness after the discharge at the second cycle and the 101st cycle, the swelling ratio (%) = [(the thickness after the discharge at the 101st cycle−the thickness after the discharge at the second cycle) / 2. Thickness after discharge at the cycle] × 100 was calculated.

  Note that the procedure and conditions for examining the cycle characteristics and swelling are the same in the following series of experimental examples.

  In the case where the negative electrode active material layer 54B includes a crystalline negative electrode active material layer and an amorphous negative electrode active material layer, unlike the case where only one of them is provided, good results for both the discharge capacity retention rate and the swelling rate are obtained. was gotten. In particular, when a crystalline negative electrode active material layer and an amorphous negative electrode active material layer are included, the thickness ratio is preferably 0.1 or more and 0.995 or less, more preferably 0.3 or more and 0.95 or less. Results were obtained. For these reasons, in the secondary battery of the present invention, the negative electrode active material layer 54B includes a structure in which a crystalline negative electrode active material layer and an amorphous negative electrode active material layer are laminated in this order. Swelling characteristics are obtained. In this case, if the thickness ratio is 0.1 or more and 0.995 or less, both characteristics are further improved.

(Experimental examples 2-1 to 2-6)
As shown in Table 3, similar to Experimental Examples 1-3 and 1-6, except that the formation method of the amorphous negative electrode active material layer was changed and the formation method of the crystalline negative electrode active material layer was changed I went through the procedure. The conditions of the sputtering process and the CVD process are the same as in Experimental Examples 1-13 and 1-14.

  The formation procedure using the coating method is as follows. First, silicon powder (median diameter = 8 μm) as a negative electrode active material and a polyamic acid solution were mixed at a dry weight ratio of 80:20 to obtain a negative electrode mixture. The solvents for this polyamic acid solution are N-methyl-2-pyrrolidone and N, N-dimethylacetamide. Subsequently, the negative electrode mixture was dispersed in N-methyl-2-pyrrolidone to obtain a negative electrode mixture slurry. Finally, after applying the negative electrode mixture slurry uniformly on both surfaces of the negative electrode current collector 54A using a coating apparatus and drying, the negative electrode active material is heated in a vacuum atmosphere at 400 ° C. for 1 hour. A material layer was formed.

  When the cycle characteristics and the swollenness characteristics of the secondary batteries of Experimental Examples 2-1 to 2-6 were examined, the results shown in Table 3 were obtained.

  Even when the formation method of the amorphous negative electrode active material layer was changed, the same results as in Tables 1 and 2 were obtained. In this case, the discharge capacity retention ratio and the swelling ratio were substantially the same as compared with each thickness ratio. Further, when the coating method was used as the method for forming the negative electrode active material layer, the discharge capacity retention rate was lower and the swelling rate was larger than when the thermal spraying method was used. For these reasons, in the secondary battery of the present invention, excellent cycle characteristics and swollenness characteristics can be obtained even when the sputtering method or the CVD method is used as the method for forming the amorphous negative electrode active material layer. In addition, when a thermal spraying method is used as a method for forming the crystalline negative electrode active material layer, cycle characteristics and swelling characteristics superior to those obtained when a coating method is used can be obtained.

(Experimental examples 3-1 to 3-7)
As shown in Table 4, the same procedure as in Experimental Examples 1-1, 1-3, 1-6, 1-9 to 1-12 was performed, except that the total thickness of the negative electrode active material layer 54B was changed. . When the cycle characteristics and the swollenness characteristics of the secondary batteries of Examples 3-1 to 3-7 were examined, the results shown in Table 4 were obtained.

  Even when the total thickness of the negative electrode active material layer 54B was changed, the same results as in Tables 1 and 2 were obtained. Therefore, in the secondary battery of the present invention, when the negative electrode active material layer 54B includes a crystalline negative electrode active material layer and an amorphous negative electrode active material layer, an excellent cycle is achieved without depending on the total thickness. Characteristics and blister characteristics are obtained.

(Experimental examples 4-1 to 4-5)
As shown in Table 5, the same procedure as in Experimental Example 1-3 was performed except that the half width and the crystallite size of the crystalline negative electrode active material layer (crystalline negative electrode active material) were changed. When the cycle characteristics and the swollenness characteristics of the secondary batteries of Examples 4-1 to 4-5 were examined, the results shown in Table 5 and FIG. 15 were obtained.

  Even when the full width at half maximum and the crystallinity size were changed, the same results as in Tables 1 and 2 were obtained. In this case, when the half width was 20 ° or less and the crystallite size was 100 nm or more, the discharge capacity retention ratio was higher. For these reasons, in the secondary battery of the present invention, if the half width (2θ) of the diffraction peak on the (111) crystal plane of the crystalline negative electrode active material is 20 ° or less and the crystallite size is 100 nm or more, , Cycle characteristics are further improved.

(Experimental examples 5-1 to 5-3)
A procedure similar to that of Experimental Examples 1-3, 1-6, and 1-9 was performed except that the plurality of particulate negative electrode active materials did not contain flat particles in the crystalline negative electrode active material layer. The cycle characteristics and the swollenness characteristics of the secondary batteries of Examples 5-1 to 5-3 were examined. The results shown in Table 6 were obtained.

  Even when the crystalline negative electrode active material layer did not contain flat particles, the same results as in Tables 1 and 2 were obtained. In this case, the discharge capacity retention rate was lowered and the swelling rate was increased as compared with the case where flat particles were included. For these reasons, in the secondary battery of the present invention, if the plurality of particulate negative electrode active materials include flat particles in the crystalline negative electrode active material layer, the cycle characteristics and the swollenness characteristics are further improved.

(Experimental examples 6-1 to 6-9)
As shown in Table 7, the same procedure as in Experimental Example 1-3 was performed except that the oxygen content in the negative electrode active material was changed in the crystalline negative electrode active material layer and the amorphous negative electrode active material layer. When the cycle characteristics and the swollenness characteristics of the secondary batteries of Examples 6-1 to 6-9 were examined, the results shown in Table 7 and FIG. 16 were obtained.

  Even when the oxygen content in the negative electrode active material was changed, the same results as in Tables 1 and 2 were obtained. In this case, when the oxygen content was 1.5 atomic% or more and 40 atomic% or less, a high discharge capacity retention rate was obtained and a sufficient battery capacity was also obtained. For these reasons, in the secondary battery of the present invention, excellent cycle characteristics and battery capacity can be obtained if the oxygen content in the negative electrode active material is 1.5 atomic% to 40 atomic%.

(Experimental examples 7-1 to 7-16)
As shown in Table 8 and Table 9, the same procedure as in Experimental Example 1-3 was performed, except that the negative electrode active material contained a metal element in the crystalline negative electrode active material layer. In this case, when forming the negative electrode active material layer 54B, the silicon alloy particles formed by the gas atomization method are sprayed in a molten state or a semi-molten state, and the content of the metal element in the negative electrode active material is set to 5 atoms. %.

(Experimental examples 8-1 to 8-3)
As shown in Table 10, the same procedure as in Experimental Example 1-3 was performed, except that the negative electrode active material contained a metal element in the amorphous negative electrode active material layer.

(Experimental examples 9-1 to 9-3)
As shown in Table 11, the same procedure as in Experimental Example 1-3 was performed, except that the negative electrode active material contained a metal element in the crystalline negative electrode active material layer and the amorphous negative electrode active material layer.

  The cycle characteristics and the swollenness characteristics of the secondary batteries of Experimental Examples 7-1 to 7-16, 8-1 to 8-3, and 9-1 to 9-3 were examined. The results are shown in Tables 8 to 11. Results were obtained.

  Even when the negative electrode active material contained a metal element, the same results as in Tables 1 and 2 were obtained. In this case, the discharge capacity retention rate was higher than when no metal element was included. From these facts, in the secondary battery of the present invention, if the negative electrode active material contains a metal element in at least one of the crystalline negative electrode active material layer and the non-crystalline negative electrode active material layer, the cycle characteristics are further improved. improves.

(Experimental examples 10-1 to 10-3)
As shown in Table 12, experimental examples except that the negative electrode active material layer 54B was formed so as to include a high oxygen content region and a low oxygen content region by intermittently introducing oxygen gas or the like into the chamber. The same procedure as in 1-3 was performed. In this case, the high oxygen content region is sandwiched by the low oxygen content region, and they are alternately stacked. Further, the oxygen content in the negative electrode active material in the high oxygen content region was set to 5 atomic%. When the cycle characteristics and the swollenness characteristics of the secondary batteries of Experimental Examples 10-1 to 10-3 were examined, the results shown in Table 12 and FIG. 17 were obtained.

  Even when the negative electrode active material layer 54B includes the high oxygen content region and the low oxygen content region, the same results as in Table 1 and Table 2 were obtained. In this case, the discharge capacity retention rate is higher and the swelling rate is smaller than when the high oxygen content region and the low oxygen content region are not included, and the discharge capacity retention rate increases as the number of high oxygen content regions increases. The bulge rate became smaller with higher. For these reasons, in the secondary battery of the present invention, if the negative electrode active material layer 54B includes a high oxygen content region and a low oxygen content region, the cycle characteristics and the swollenness characteristics are further improved.

(Experimental examples 11-1 to 11-13)
As shown in Table 13, the same procedure as in Experimental Example 1-3 was performed, except that the ten-point average roughness Rz of the surface of the negative electrode current collector 54A was changed. When the cycle characteristics and the swollenness characteristics of the secondary batteries of Examples 11-1 to 11-13 were examined, the results shown in Table 13 and FIG. 18 were obtained.

  Even when the ten-point average roughness Rz was changed, the same results as in Tables 1 and 2 were obtained. In this case, when the ten-point average roughness Rz was 1.5 μm or more, and further 3 μm or more and 30 μm or less, a high discharge capacity retention rate was obtained and a sufficient battery capacity was also obtained. For these reasons, in the secondary battery of the present invention, if the ten-point average roughness Rz of the surface of the negative electrode current collector 54A is 1.5 μm or more, preferably 3 μm or more and 30 μm or less, excellent cycle characteristics and battery capacity are obtained. Is obtained.

(Experimental examples 12-1 to 12-8)
As shown in Table 14 and Table 15, the same procedure as in Experimental Example 1-3 was performed except that the composition of the electrolytic solution was changed. In this case, 4-fluoro-1,3-dioxolan-2-one (FEC) or 4,5-difluoro-1,3-dioxolan-2-one (DFEC) was used as a solvent. As other solvents, vinylene carbonate (VC), vinyl ethylene carbonate (VEC), propene sultone (PRS), anhydrous sulfobenzoic acid (SBAH) or anhydrous sulfopropionic acid (SPAH) was used. Furthermore, lithium tetrafluoroborate (LiBF ₄ ) was used as the electrolyte salt. The content of other solvents in the solvent was 1% by weight. The LiBF ₄ content was 0.1 mol / kg with respect to the solvent, and the LiPF ₆ content was 0.9 mol / kg with respect to the solvent. When the cycle characteristics and the swollenness characteristics of the secondary batteries of Examples 12-1 to 12-8 were examined, the results shown in Table 14 and Table 15 were obtained.

Even when the composition of the electrolytic solution was changed, the same results as in Tables 1 and 2 were obtained. In particular, when FEC or the like was added and LiBF ₄ was added, the discharge capacity retention rate was higher than when no such components were added. Moreover, when PRS etc. were added, the swelling rate became smaller than the case where they were not added. For these reasons, in the secondary battery of the present invention, if a halogenated chain carbonate, halogenated cyclic carbonate, unsaturated carbon bond cyclic carbonate, sultone or acid anhydride is used as a solvent, cycle characteristics are further improved. improves. Moreover, if lithium tetrafluoroborate is used as the electrolyte salt, the cycle characteristics are further improved. Furthermore, if sultone or an acid anhydride is used as a solvent, the swelling characteristics are further improved.

(Experimental examples 13-1 to 13-4)
As shown in Table 16, the same procedure as in Experimental Example 1-3 was performed except that a lithium nickel composite oxide was used as the positive electrode active material. When the cycle characteristics and the swollenness characteristics of the secondary batteries of Examples 13-1 to 13-4 were examined, the results shown in Table 16 were obtained.

  Even when lithium nickel cobalt based composite oxide was used as the positive electrode active material, the same results as in Tables 1 and 2 were obtained. In this case, the discharge capacity retention rate was higher than when the lithium cobalt composite oxide was used. For these reasons, in the secondary battery of the present invention, the cycle characteristics are further improved by using a lithium nickel cobalt composite oxide as the positive electrode active material.

(Experimental Examples 14-1 and 14-2)
A procedure similar to that of Experimental Example 1-3 was performed, except that a square secondary battery was manufactured. In this case, first, the positive electrode 21 and the negative electrode 22 were prepared, and then the positive electrode lead 24 made of aluminum was welded to the positive electrode current collector 21A, and the negative electrode lead 25 made of nickel was welded to the negative electrode current collector 22A. . Subsequently, the positive electrode 21, the separator 23, and the negative electrode 22 were laminated in this order and wound in the longitudinal direction, and then formed into a flat shape to produce the battery element 20. Subsequently, as shown in Table 17, after the battery element 20 was housed inside the metal battery can 11, the insulating plate 12 was disposed on the battery element 20. Subsequently, the positive electrode lead 24 was welded to the positive electrode pin 15 and the negative electrode lead 25 was welded to the battery can 11, and then the battery lid 13 was laser welded to the open end of the battery can 11. Finally, an electrolyte was injected into the battery can 11 through the injection hole 19, and then the injection hole 19 was closed with a sealing member 19A to complete a square battery. When the cycle characteristics and the swollenness characteristics of the secondary batteries of Examples 14-1 and 14-2 were examined, the results shown in Table 17 were obtained.

  Even when the battery structure was changed, the same results as in Tables 1 and 2 were obtained. In particular, when the battery structure is a square type, the discharge capacity retention rate is higher and the swelling rate is smaller than when the battery structure is a laminate film type. In this case, when the material of the battery can 11 was iron, the discharge capacity retention rate was higher and the swelling rate was smaller. For these reasons, in the secondary battery of the present invention, if the battery structure is square, the cycle characteristics and the swollenness characteristics are further improved.

  From the results shown in Tables 1 to 17 and FIGS. 14 to 18, the following was confirmed for the secondary battery of the present invention. In the secondary battery of the present invention, the negative electrode has a negative electrode active material layer on the negative electrode current collector. The negative electrode active material layer is formed on the negative electrode current collector and includes a crystalline negative electrode active material layer including a crystalline negative electrode active material, and is formed on the crystalline negative electrode active material layer and is non-crystalline. And an amorphous negative electrode active material layer containing a negative electrode active material. Thereby, excellent cycle characteristics and swelling characteristics can be obtained without depending on the oxygen content in the negative electrode active material, the presence or absence of metal elements in the negative electrode active material, the composition of the electrolytic solution, or the battery structure.

  The present invention has been described with reference to the embodiments and examples. However, the present invention is not limited to the embodiments described in the above embodiments and examples, and various modifications can be made. For example, the use application of the negative electrode of the present invention is not necessarily limited to the secondary battery, but may be other electrochemical devices. Other applications include, for example, capacitors.

  In the above-described embodiments and examples, the lithium ion secondary battery in which the capacity of the negative electrode is expressed by insertion and extraction of lithium ions is described as the type of the secondary battery, but is not necessarily limited thereto. The secondary battery of the present invention also includes a secondary battery in which the capacity of the negative electrode includes a capacity due to insertion and extraction of lithium ions and a capacity due to precipitation and dissolution of lithium metal, and is represented by the sum of these capacities. The same applies. In this case, a material capable of inserting and extracting lithium ions is used as the negative electrode active material, and the chargeable capacity of the material is set to be smaller than the discharge capacity of the positive electrode.

  Further, in the above-described embodiments and examples, the case where the battery structure is a square shape, the cylindrical shape, or the laminate film type, or the case where the battery element has a winding structure has been described as an example. However, the secondary battery of the present invention can be similarly applied to a case where it has another battery structure such as a coin type or a button type, and a case where the battery element has another structure such as a laminated structure.

  In the above-described embodiments and examples, the case where lithium (lithium ion) is used as the electrode reactant has been described, but the present invention is not necessarily limited thereto. The electrode reactant may be, for example, another group 1 element such as sodium (Na) or potassium (K), a group 2 element such as magnesium or calcium, or another light metal such as aluminum. Since the effect of the present invention should be obtained without depending on the type of the electrode reactant, the same effect can be obtained even if the type of the electrode reactant is changed.

  In the above-described embodiments and examples, the appropriate range derived from the results of the examples is used for the thickness ratio of the crystalline negative electrode active material layer and the amorphous negative electrode active material layer in the secondary battery of the present invention. Explains. However, the explanation does not completely deny the possibility that the thickness ratio is outside the above range. In other words, the appropriate range described above is a particularly preferable range for obtaining the effect of the present invention, and the thickness ratio may be slightly deviated from the above range as long as the effect of the present invention is obtained. The same applies to the half width and crystallite size of the negative electrode active material, the oxygen content in the negative electrode active material, or the ten-point average roughness Rz of the surface of the negative electrode current collector.

It is sectional drawing showing the structure of the negative electrode which concerns on one embodiment of this invention. FIG. 2 is an SEM photograph showing a cross-sectional structure of the negative electrode shown in FIG. 1 and a schematic diagram thereof. FIG. 2 is an SEM photograph showing another cross-sectional structure of the negative electrode shown in FIG. 1 and a schematic diagram thereof. FIG. 4 is an SEM photograph showing still another cross-sectional structure of the negative electrode shown in FIG. 1 and a schematic diagram thereof. FIG. 4 is an SEM photograph showing still another cross-sectional structure of the negative electrode shown in FIG. 1 and a schematic diagram thereof. FIG. 4 is an SEM photograph showing still another cross-sectional structure of the negative electrode shown in FIG. 1 and a schematic diagram thereof. It is sectional drawing showing the structure of the 1st secondary battery provided with the negative electrode which concerns on one embodiment of this invention. It is sectional drawing along the VIII-VIII line of the 1st secondary battery shown in FIG. It is a top view which represents typically the structure of the positive electrode and negative electrode which were shown in FIG. It is sectional drawing showing the structure of the 2nd secondary battery provided with the negative electrode which concerns on one embodiment of this invention. It is sectional drawing which expands and represents a part of winding electrode body shown in FIG. It is a perspective view showing the structure of the 3rd secondary battery provided with the negative electrode which concerns on one embodiment of this invention. It is sectional drawing along the XIII-XIII line | wire of the winding electrode body shown in FIG. It is a figure showing the correlation between thickness ratio, a discharge capacity maintenance factor, and a swelling rate. It is a figure showing the correlation between a half value width, a discharge capacity maintenance factor, and a swelling rate. It is a figure showing the correlation between oxygen content, a discharge capacity maintenance factor, and a swelling rate. It is a figure showing the correlation between the number of high oxygen content area | regions, a discharge capacity maintenance factor, and a swelling rate. It is a figure showing the correlation between ten-point average roughness Rz, a discharge capacity maintenance factor, and a swelling rate.

Explanation of symbols

  1, 22A, 42A, 54A ... negative electrode current collector, 2, 22B, 42B, 54B ... negative electrode active material layer, 2K ... gap, 2X ... crystalline negative electrode active material layer, 2Y ... non-crystalline negative electrode active material layer, 11 , 31 ... Battery can, 12, 32, 33 ... Insulating plate, 13, 34 ... Battery cover, 14 ... Terminal plate, 15 ... Positive electrode pin, 16 ... Insulating case, 17, 37 ... Gasket, 18 ... Cleavage valve, 19 ... Injection hole, 19A ... sealing member, 20 ... battery element, 21, 41, 53 ... positive electrode, 21A, 41A, 53A ... positive electrode current collector, 21B, 41B, 53B ... positive electrode active material layer, 22, 42, 54 ... Negative electrode, 23, 43, 55 ... Separator, 24, 45, 51 ... Positive electrode lead, 25, 46, 52 ... Negative electrode lead, 35 ... Safety valve mechanism, 35A ... Disc plate, 36 ... Thermal resistance element, 40, 50 ... Winding Rotating electrode body, 44 ... center pin, 56 Electrolyte 57 ... protective tape 61 ... adhesive film 60 ... exterior member 201, 201X, 201Y ... negative electrode active material particle, 201XP ... flat particle, 202 ... gap, 203 ... gap, P1 ... contact part, P2 ... non-contact portion.

Claims (20)

A positive electrode and a negative electrode capable of occluding and releasing an electrode reactant, and an electrolyte containing a solvent and an electrolyte salt;
The negative electrode has a negative electrode active material layer on a negative electrode current collector,
The negative electrode active material layer is formed on the negative electrode current collector and includes a crystalline negative electrode active material layer including a crystalline negative electrode active material, and is formed on the crystalline negative electrode active material layer and is non-crystalline. And a non-crystalline negative electrode active material layer containing a negative electrode active material.   The secondary battery according to claim 1, wherein the crystalline negative electrode active material has a plurality of particles, and at least a part of the crystalline negative electrode active material has a flat shape extending in a direction along the surface of the negative electrode current collector. .   The secondary battery according to claim 1, wherein the crystalline negative electrode active material is connected to a surface of the negative electrode current collector.   The secondary battery according to claim 1, wherein the non-crystalline negative electrode active material has a plurality of particles and is arranged on the crystalline negative electrode active material layer.   2. The secondary battery according to claim 1, wherein a half-value width (2θ) of a diffraction peak in a (111) crystal plane of the crystalline negative electrode active material obtained by X-ray diffraction is 20 ° or less.   The secondary battery according to claim 1, wherein a crystallite size caused by a (111) crystal plane of the crystalline negative electrode active material obtained by X-ray diffraction is 100 nm or more.   When the thickness of the crystalline negative electrode active material layer is T1 and the thickness of the non-crystalline negative electrode active material layer is T2, the thickness ratio (T1 / (T1 + T2)) is 0.1 or more and 0.00. The secondary battery according to claim 1, which is 995 or less.   The crystalline negative electrode active material layer is formed by a thermal spraying method, and the non-crystalline negative electrode active material layer is formed by a vapor deposition method, a sputtering method, or a thermal chemical vapor deposition (CVD) method. The secondary battery according to claim 1.   The secondary battery according to claim 1, wherein the negative electrode active material contains silicon (Si) as a constituent element.   The secondary battery according to claim 1, wherein the negative electrode active material contains oxygen (O) as a constituent element, and an oxygen content in the negative electrode active material is 1.5 atomic% to 40 atomic%.   The negative electrode active material is iron (Fe), nickel (Ni), molybdenum (Mo), titanium (Ti), chromium (Cr), cobalt (Co), copper (Cu), manganese (Mn), zinc (Zn). , Containing at least one metal element of germanium (Ge), aluminum (Al), zirconium (Zr), silver (Ag), tin (Sn), antimony (Sb) and tungsten (W) as a constituent element Item 11. A secondary battery according to Item 1.   The secondary battery according to claim 1, wherein the negative electrode active material includes a high oxygen content region and a low oxygen content region in a thickness direction of the negative electrode active material layer.   The secondary battery according to claim 1, wherein the ten-point average roughness Rz of the surface of the negative electrode current collector is 1.5 μm or more.   The secondary battery according to claim 13, wherein the ten-point average roughness Rz is 3 μm or more and 30 μm or less. The solvent includes a halogenated chain carbonate represented by the formula (1), a halogenated cyclic carbonate represented by the formula (2), and an unsaturated carbon bond represented by the formula (3) to the formula (5). The secondary battery according to claim 1, comprising at least one of cyclic carbonate, sultone, and acid anhydride.

(R11 to R16 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of them is a halogen group or a halogenated alkyl group.)

(R17 to R20 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of them is a halogen group or a halogenated alkyl group.)

(R21 and R22 are a hydrogen group or an alkyl group.)

(R23 to R26 are a hydrogen group, an alkyl group, a vinyl group, or an allyl group, and at least one of them is a vinyl group or an allyl group.)

(R27 is an alkylene group.) The electrolyte salt includes lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium perchlorate (LiClO ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), and a formula ( The secondary battery according to claim 1, comprising at least one of compounds represented by 6) to formula (11).

(X31 is a group 1 element or group 2 element in the long-period periodic table, or aluminum (Al). M31 is a transition metal element, or a group 13 element, group 14 element, or group 15 element in the long-period periodic table. is .R31 is a halogen group .Y31 - (O =) C- R32-C (= O) -, - (O =) C-C (R33) 2 - or - (O =) C-C ( ═O) —, wherein R32 is an alkylene group, a halogenated alkylene group, an arylene group or a halogenated arylene group, and R33 is an alkyl group, a halogenated alkyl group, an aryl group or a halogenated aryl group. A3 is an integer of 1 to 4, b3 is 0, 2 or 4, and c3, d3, m3 and n3 are integers of 1 to 3.)

(X41 is a group 1 element or group 2 element in the long periodic table. M41 is a transition metal element, or a group 13, element or group 15 element in the long period periodic table. Y41 is − ( O =) C- (C (R41 ) 2) b4 -C (= O) -, - (R43) 2 C- (C (R42) 2) c4 -C (= O) -, - (R43) 2 C -(C (R42) ₂ ) _c4 -C (R43) ₂ -,-(R43) ₂ C- (C (R42) ₂ ) _c4 -S (= O) ₂ -,-(O =) ₂ S- ( C (R42) ₂ ) _d4- S (= O) _2- or-(O =) C- (C (R42) ₂ ) _d4- S (= O) _2- where R41 and R43 are hydrogen groups. , An alkyl group, a halogen group, or a halogenated alkyl group, and at least one of each is a halogen group or a halogenated alkyl group. R42 is a hydrogen group, an alkyl group, a halogen group or a halogenated alkyl group, wherein a4, e4 and n4 are 1 or 2, b4 and d4 are integers of 1 to 4, and c4 Is an integer from 0 to 4, and f4 and m4 are integers from 1 to 3.)

(X51 is a group 1 element or group 2 element in the long-period periodic table. M51 is a transition metal element, or a group 13, element or group 15 element in the long-period periodic table. Rf is fluorinated. An alkyl group or a fluorinated aryl group, each having 1 to 10 carbon atoms Y51 is — (O═) C— (C (R51) ₂ ) _d5 —C (═O) —, — (R52); ₂ C- (C (R51) ₂ ) _d5 -C (= O)-,-(R52) ₂ C- (C (R51) ₂ ) _d5 -C (R52) ₂ -,-(R52) ₂ C- ( _{C (R51) 2) d5 -S} (= O) 2 -, - (O =) 2 S- (C (R51) 2) e5 -S (= O) 2 - or - (O =) C- (C _{(R51) 2) e5 -S (} = O) 2 -. is, however, R51 is a hydrogen group, an alkyl group, a halogen group, or a halogen Kaa R52 is a hydrogen group, an alkyl group, a halogen group or a halogenated alkyl group, at least one of which is a halogen group or a halogenated alkyl group, wherein a5, f5 and n5 are 1 or 2; B5, c5 and e5 are integers of 1 to 4, d5 is an integer of 0 to 4, and g5 and m5 are integers of 1 to 3.)
_{LiN (C m F 2m + 1} SO 2) (C n F 2n + 1 SO 2) ... (9)
(M and n are integers of 1 or more.)

(R61 is a linear or branched perfluoroalkylene group having 2 to 4 carbon atoms.)
LiC (C _p F _{2p + 1} SO ₂ ) (C _q F _{2q + 1} SO ₂ ) (C _r F _{2r + 1} SO ₂ ) (11)
(P, q and r are integers of 1 or more.) The secondary battery according to claim 1, wherein the positive electrode includes a composite oxide represented by Formula (12) as a positive electrode active material.
LiNi _1-x M _x O ₂ (12)
(M is cobalt, manganese, iron, aluminum, vanadium (V), tin, magnesium (Mg), titanium, strontium (Sr), calcium (Ca), zirconium, molybdenum, technetium (Tc), ruthenium (Ru), tantalum (Ta), tungsten, rhenium (Re), ytterbium (Yb), copper, zinc, barium (Ba), boron (B), chromium, silicon, gallium (Ga), phosphorus (P), antimony and niobium (Nb) And x is 0.005 <x <0.5.)   The secondary battery according to claim 1, wherein the electrode reactant is lithium ion. It is possible to occlude and release the electrode reactant, and has a negative electrode active material layer on the negative electrode current collector,
The negative electrode active material layer is formed on the negative electrode current collector and includes a crystalline negative electrode active material layer including a crystalline negative electrode active material, and is formed on the crystalline negative electrode active material layer and is non-crystalline. And a non-crystalline negative electrode active material layer containing a negative electrode active material.   The negative electrode according to claim 19, which is used for a secondary battery.

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