JP2009295422A - Anode collector, anode and secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a secondary battery capable of obtaining superior cycle characteristics. <P>SOLUTION: An anode 50 has an anode active material layer 52 containing at least a kind from among a group consisting of a single body and a compound of silicon fitted to an anode collector 51. The anode collector 51 has a base material 51A with protruding parts 51B made of copper provided on the surface, and a plated film 51C continuously covering at least a part of the protruding parts 51B and at least a part of the surface of the base material 51A. The plated film 51C is structured of a metal other than copper, such as single bodies and compounds or the like of cobalt, iron, or nickel. Due to the existence of the protruding parts 51B, internal stresses generated at the anode active material layer 52 at expansion and contraction are dispersed, and moreover, a contact area of the anode collector 51 and the anode active material layer 52 is increased to improve their mutual adhesion. The protruding parts 51B are covered with the plated film 51C, and so, are less apt to exfoliate from the base material 51A. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a negative electrode current collector provided with a protrusion made of copper on the surface, and a negative electrode and a secondary battery including the same.

In recent years, as mobile devices have higher performance and more functions, there is a demand for higher capacities of secondary batteries serving as power sources thereof. A lithium ion secondary battery is given as a secondary battery that meets this requirement. However, since lithium ion secondary batteries that are currently in practical use use graphite for the negative electrode, the battery capacity is in a saturated state and it is difficult to significantly increase the capacity. Thus, it has been studied to increase the capacity of lithium ion secondary batteries by using silicon for the negative electrode (see, for example, Patent Document 1).
JP 2004-171876 A

  However, since silicon expands and contracts due to charging and discharging, repeated charging and discharging causes the negative electrode active material layer to fall off from the negative electrode current collector due to the stress caused by expansion and contraction, resulting in a decrease in current collection and cycle characteristics. There was a problem of doing.

Therefore, the present applicant has already proposed a negative electrode in which a negative electrode active material layer containing tin is formed on a negative electrode current collector provided with a protrusion on a base material and alloyed at least in part of the interface. (For example, refer to Patent Document 2).
JP 2004-207112 A

  However, even when a negative electrode current collector provided with a protrusion is used as in the above-mentioned Patent Document 2, some protrusions are caused by intense expansion and contraction of the negative electrode active material layer. May peel from the substrate, and the adhesion between the negative electrode current collector and the negative electrode active material layer may be impaired.

  The present invention has been made in view of such problems, and a first object thereof is to provide a negative electrode current collector capable of improving adhesion to the negative electrode active material layer. Furthermore, the second object of the present invention is to provide a negative electrode and a secondary battery that include the negative electrode current collector as described above and that can improve cycle characteristics.

  The negative electrode current collector of the present invention continuously covers a conductive base material provided with a protrusion made of copper on the surface, at least a part of the protrusion and at least a part of the surface of the base material, and And a plating film made of a metal other than copper.

  The negative electrode of the present invention is formed on the side of the negative electrode current collector of the present invention described above and the negative electrode current collector provided with the protrusion, and is at least one member selected from the group consisting of a simple substance of silicon and a compound. And a negative electrode active material layer.

  The secondary battery of the present invention comprises a positive electrode, the above-described negative electrode of the present invention, and an electrolyte.

  In the negative electrode current collector, the negative electrode, and the secondary battery of the present invention, a protrusion made of copper is provided on the surface of the substrate. For this reason, the contact area of a negative electrode collector and a negative electrode active material layer increases, and mutual adhesiveness improves. In addition, internal stress generated during expansion and contraction in the negative electrode active material layer is dispersed by the protrusions, and cracks are less likely to occur in the negative electrode active material layer. Furthermore, since the protrusion is covered with a plating film made of a metal other than copper together with the base material, the protrusion becomes difficult to peel from the base material.

  According to the negative electrode current collector of the present invention, the protrusions made of copper are provided on the substrate surface and the protrusions and the surface of the substrate are continuously covered with the plating film made of a metal other than copper. In the case where a negative electrode active material layer is provided thereover, stress due to expansion and contraction of the negative electrode active material layer can be relieved and the protrusions can be prevented from peeling from the substrate. Therefore, in the negative electrode of the present invention, adhesion between the negative electrode current collector and the negative electrode active material layer and current collection can be improved. Therefore, according to the secondary battery of the present invention using this negative electrode, excellent cycle characteristics can be obtained.

  In particular, when the plating film contains at least one member selected from the group consisting of simple substances and compounds of cobalt, iron or nickel, the cycle characteristics can be further improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a configuration of a negative electrode 10 having a negative electrode current collector 1 according to an embodiment of the present invention. The negative electrode 10 includes, for example, the negative electrode current collector 1 and the negative electrode active material layer 2 provided on one side or both sides of the negative electrode current collector 1. The negative electrode current collector 1 has a particulate protrusion 1B provided on the surface of the substrate 1A on the side where the negative electrode active material layer 2 is formed. Due to the excellent anchoring effect of the protrusion 1B, in the negative electrode 10, the adhesion between the negative electrode current collector 1 and the negative electrode active material layer 2 is improved, and the negative electrode active material layer 2 expands and contracts due to charge / discharge. Dropping, peeling, and miniaturization due to are suppressed. Furthermore, the negative electrode current collector 1 has a plating film 1C that continuously covers the protrusion 1B and the surface of the base 1A.

  The substrate 1A is preferably made of a material having good mechanical strength and electrochemical stability and high electrical conductivity. For example, it is preferable to include at least one selected from the group consisting of copper (Cu), stainless steel, nickel (Ni), titanium (Ti), tungsten (W), molybdenum (Mo), and aluminum (Al). Among these, it may be more preferable that the negative electrode active material layer 2 is made of a metal that is easily alloyed. In the present embodiment, as will be described later, the negative electrode active material layer 2 contains at least one member selected from the group consisting of a simple substance, an alloy or a compound of silicon, and a simple substance, an alloy or a compound of tin. Examples of a material suitable for constituting 1A include copper, titanium, aluminum, and nickel.

  Among them, copper is a metal element that has high conductivity, can be alloyed with the constituent material of the negative electrode active material layer 2 and does not form an intermetallic compound with lithium. It is particularly preferable to use a copper foil or the same alloy foil. In that case, the thickness of the substrate 1A is preferably set to 25 μm or less, for example. This is because if the thickness is too thick, excessive stress is applied due to the expansion and contraction of the negative electrode active material layer 2, and the adhesion between the negative electrode current collector 1 and the negative electrode active material layer 2 decreases. Moreover, it is preferable that the thickness of 1 A of base materials is 8 micrometers or more. This is because if the thickness is too thin, the mechanical strength decreases.

  In addition, although 1 A of base materials may be comprised by a single layer, you may comprise by multiple layers. In that case, the layer in contact with the negative electrode active material layer 2 may be made of a metal material that is easily alloyed with the negative electrode active material layer 2, and the other layers may be made of another metal material.

  The protrusion 1B is a metal fine particle such as copper, and is deposited by, for example, an electrolytic deposition method. Alternatively, it may be fixed to the surface of the substrate 1A by sintering. As described above, the protrusion 1B enhances the adhesion between the negative electrode current collector 1 and the negative electrode active material layer 2 by the anchor effect, and disperses cracks generated in the negative electrode active material layer 2 in multiple directions due to charge / discharge. Let it be small. The shape of the protruding portion 1B may be any shape such as a spherical shape or a square shape, but the average diameter of the protruding portion 1B is preferably not less than 0.5 μm and not more than 5.0 μm, for example. Moreover, it is preferable that the surface roughness of the negative electrode current collector 1 is 3.2 μm or more and 5.2 μm or less in terms of the ten-point average roughness Rz value because there are a plurality of protrusions 1B on the surface of the substrate 1A. . Under such conditions, the internal stress generated in the negative electrode active material layer 2 can be effectively relieved while sufficiently improving the adhesion between the negative electrode current collector 1 and the negative electrode active material layer 2. is there.

  The plating film 1 </ b> C preferably contains an element that can be alloyed with the negative electrode active material layer 2. This is because alloying of the negative electrode current collector 1 and the negative electrode active material layer 2 is promoted and the adhesiveness is further improved. Furthermore, it is preferable that the material has higher mechanical strength than copper, such as a metal including at least one member selected from the group consisting of simple substance and compound of cobalt (Co), iron (Fe), or nickel (Ni). . Although an oxide film may be provided on the surface of the plating film 1C, an element that can be alloyed with the negative electrode active material layer 12 exists near the interface with the negative electrode active material layer 12. It is preferable.

Further, the weight X per unit area of the plating film 1C is preferably greater than 0.5 and less than 5.0 with respect to the total weight Y per unit area of the base material 1A and the protrusion 1B. That is, it is desirable to satisfy the following conditional expression (1).
0.5 <X / Y ≦ 5.0 (1)
By making the weight ratio X / Y larger than 0.5, it is possible to reliably prevent the protruding portion 1B from being peeled off from the base material 1A by the plating film 1C. On the other hand, by making the weight ratio X / Y less than 5.0, the uneven shape on the surface of the negative electrode current collector 1 is ensured, and an excellent anchor effect is exhibited, and the negative electrode current collector 1 and the negative electrode active material layer 2 are obtained. Adhesion with can be improved.

  The negative electrode active material layer 2 includes one or more negative electrode materials capable of inserting and extracting an electrode reactant as a negative electrode active material. The negative electrode active material layer 2 is preferably alloyed with the negative electrode current collector 1 at least at a part of the interface with the negative electrode current collector 1. Specifically, it is preferable that the constituent element of the negative electrode current collector 1 is diffused in the negative electrode active material layer 2 or the constituent element of the negative electrode active material is diffused in the negative electrode current collector 1 or they are mutually diffused at the interface. That is, the negative electrode active material layer 2 is preferably alloyed at least at a part of the interface with the protrusion 1B of the negative electrode current collector 1 or the plating film 1C. This is because breakage due to expansion and contraction of the negative electrode active material layer 2 during charging and discharging is suppressed, and electronic conductivity between the negative electrode current collector 1 and the negative electrode active material layer 2 is improved. This alloying often occurs simultaneously when the negative electrode active material layer 2 is formed by a vapor phase method, a liquid phase method, or a firing method, which will be described later, but it may also be caused by further heat treatment. Note that in this specification, the above-described element diffusion is also included in one form of alloying.

  Examples of the negative electrode material capable of inserting and extracting lithium include materials capable of inserting and extracting lithium and having at least one of a metal element and a metalloid element as a constituent element. . This is because a high energy density can be obtained. Such a negative electrode material may be a single element or an alloy or a compound of a metal element or a metalloid element, and may have one or two or more phases thereof at least in part.

  The “alloy” in the present invention includes an alloy containing one or more metal elements and one or more metalloid elements in addition to an alloy composed of two or more metal elements. Further, the “alloy” may contain a nonmetallic element. This structure includes a solid solution, a eutectic (eutectic mixture), an intermetallic compound, or one in which two or more of them coexist.

  Examples of the metal element or metalloid element described above include a metal element or metalloid element capable of forming an alloy with lithium. Specifically, magnesium (Mg), boron (B), aluminum (Al), gallium (Ga), indium (In), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), Examples thereof include bismuth (Bi), cadmium (Cd), silver (Ag), zinc (Zn), hafnium (Hf), zirconium (Zr), yttrium (Y), palladium (Pd), and platinum (Pt). Among these, at least one of silicon and tin is preferable, and silicon is more preferable. This is because a high energy density can be obtained because the ability to occlude and release lithium is large.

  Examples of the negative electrode material having at least one of silicon and tin include at least a part of a simple substance, an alloy or a compound of silicon, a simple substance, an alloy or a compound of tin, or one or two or more phases thereof. The material which has in is mentioned. These may be single and multiple types may be mixed.

  Examples of the negative electrode material having a simple substance of silicon include a material mainly having a simple substance of silicon. The negative electrode active material layer 2 including this negative electrode material has, for example, a structure in which a second constituent element other than silicon and oxygen are present between silicon single layers. The total content of silicon and oxygen in the negative electrode active material layer 2 is preferably 50% by mass or more, and the content of silicon alone is particularly preferably 50% by mass or more. Examples of the second constituent element other than silicon include titanium (Ti), chromium, manganese (Mn), iron, cobalt (Co), nickel, copper, zinc, indium, silver, magnesium, aluminum, germanium, tin, Bismuth or antimony (Sb) can be used. The negative electrode active material layer 2 containing a material mainly composed of silicon can be formed, for example, by co-evaporation of silicon and other constituent elements.

As an alloy of silicon, for example, as a second constituent element other than silicon, among the group consisting of tin, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony and chromium And those having at least one of the following. Examples of the silicon compound include those having oxygen or carbon (C), and may contain the second constituent element described above in addition to silicon. Examples of silicon alloys or compounds include SiB ₄ , SiB ₆ , Mg ₂ Si, Ni ₂ Si, TiSi ₂ , MoSi ₂ , CoSi ₂ , NiSi ₂ , CaSi ₂ , CrSi ₂ , Cu ₅ Si, FeSi ₂ , MnSi. ₂ , NbSi ₂ , TaSi ₂ , VSi ₂ , WSi ₂ , ZnSi ₂ , SiC, Si ₃ N ₄ , Si ₂ N ₂ O, SiO _v (0 <v ≦ 2) or LiSiO.

As an alloy of tin, for example, as a second constituent element other than tin, among the group consisting of silicon, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony and chromium The thing which has at least 1 sort (s) of these is mentioned. Examples of the tin compound include those having oxygen or carbon, and may contain the above-described second constituent element in addition to tin. Examples of tin alloys or compounds include SnO _w (0 <w ≦ 2), SnSiO ₃ , LiSnO, Mg ₂ Sn, and the like.

  In particular, as the negative electrode material having at least one of silicon and tin, for example, a material having tin and the second constituent element in addition to tin as the first constituent element is preferable. The second constituent element is cobalt, iron, magnesium, titanium, vanadium (V), chromium, manganese, nickel, copper, zinc, gallium, zirconium, niobium (Nb), molybdenum (Mo), silver, indium, cerium ( Ce), hafnium, tantalum (Ta), tungsten (W), bismuth and silicon. The third constituent element is at least one selected from the group consisting of boron, carbon, aluminum, and phosphorus (P). This is because the inclusion of the second and third constituent elements improves the cycle characteristics when the negative electrode is used in an electrochemical device such as a secondary battery.

  Among them, tin, cobalt and carbon are included as constituent elements, the carbon content is 9.9 mass% or more and 29.7 mass% or less, and the ratio of cobalt to the total of tin and cobalt (Co / (Sn + Co)) is 30. An SnCoC-containing material having a mass% of 70% by mass or less is preferable. This is because a high energy density can be obtained in such a composition range.

  This SnCoC-containing material may further contain other constituent elements as necessary. As other constituent elements, for example, silicon, iron, nickel, chromium, indium, niobium, germanium, titanium, molybdenum, aluminum, phosphorus, gallium, bismuth, and the like are preferable, and two or more of them may be included. Good. This is because a higher effect can be obtained.

  The SnCoC-containing material has a phase containing tin, cobalt, and carbon, and the phase is preferably a low crystalline or amorphous phase. This phase is a reaction phase capable of reacting with lithium, whereby excellent cycle characteristics can be obtained. The half-value width of the diffraction peak obtained by X-ray diffraction of this phase is 1.0 ° or more at a diffraction angle 2θ when CuKα ray is used as the specific X-ray and the drawing speed is 1 ° / min. Is preferred. This is because lithium is more smoothly inserted and extracted, and the reactivity with the electrolytic solution is reduced when the negative electrode is used in an electrochemical device such as a secondary battery equipped with the electrolytic solution.

  Whether or not the diffraction peak obtained by X-ray diffraction corresponds to a reaction phase capable of reacting with lithium can be easily determined by comparing X-ray diffraction charts before and after electrochemical reaction with lithium. can do. For example, if the position of the diffraction peak changes before and after the electrochemical reaction with lithium, it corresponds to a reaction phase capable of reacting with lithium. In this case, for example, a diffraction peak of a low crystalline or amorphous reaction phase is observed between 2θ = 20 ° and 50 °. This low crystalline or amorphous reaction phase contains, for example, each of the above-described constituent elements, and is considered to be mainly low-crystallized or amorphous due to carbon.

  In addition to the low crystalline or amorphous phase, the SnCoC-containing material may have a phase containing a simple substance or a part of each constituent element.

  In particular, in the SnCoC-containing material, it is preferable that at least a part of carbon as a constituent element is bonded to a metal element or a metalloid element as another constituent element. This is because aggregation or crystallization of tin or the like is suppressed.

  As a measuring method for examining the bonding state of elements, for example, X-ray photoelectron spectroscopy (XPS) can be cited. This XPS irradiates the sample surface with soft X-rays (Al-Kα ray or Mg-Kα ray is used in a commercial apparatus), and measures the kinetic energy of photoelectrons jumping out of the sample surface. To elemental composition in the region of several nanometers and the bonding state of the elements.

  The binding energy of the core orbital electrons of the element changes in a first approximation in correlation with the charge density on the element. For example, when the charge density of the carbon element decreases due to an interaction with an element present in the vicinity, the outer electrons such as 2p electrons decrease, so the 1s electron of the carbon element exerts a strong binding force from the shell. Will receive. That is, the binding energy increases as the charge density of the element decreases. In XPS, when the binding energy increases, the peak shifts to a high energy region.

  In XPS, if the peak of carbon 1s orbital (C1s) is graphite, it appears at 284.5 eV in an energy calibrated apparatus so that the peak of 4f orbital (Au4f) of gold atom is obtained at 84.0 eV. . Moreover, if it is surface contamination carbon, it will appear at 284.8 eV. On the other hand, when the charge density of the carbon element is high, for example, when it is bonded to an element more positive than carbon, the C1s peak appears in a region lower than 284.5 eV. That is, when at least a part of carbon contained in the SnCoC-containing material is bonded to a metal element or a metalloid element that is another constituent element, the peak of the synthetic wave of C1s obtained for the SnCoC-containing material is 284. Appears in a region lower than 5 eV.

  When performing XPS measurement, it is preferable that the surface is lightly sputtered with an argon ion gun attached to the XPS apparatus when the surface is covered with surface-contaminated carbon. In addition, when a negative electrode having a SnCoC-containing material to be measured is present in an electrochemical device such as a secondary battery provided with an electrolytic solution, the electrochemical device is disassembled and the negative electrode is taken out, and then dimethyl carbonate, etc. It is good to wash with a volatile solvent. This is for removing the low-volatile solvent and the electrolyte salt present on the negative electrode surface. These samplings are preferably performed under an inert atmosphere.

  In XPS measurement, for example, the peak of C1s is used to correct the energy axis of the spectrum. Usually, since surface-contaminated carbon exists on the surface of the substance, the C1s peak of the surface-contaminated carbon is set to 284.8 eV, and this is used as an energy standard. In XPS measurement, the waveform of the peak of C1s is obtained as a form including the surface contamination carbon peak and the carbon peak in the SnCoC-containing material. For example, by analyzing using commercially available software, The surface contamination carbon peak is separated from the carbon peak in the SnCoC-containing material. In the waveform analysis, the position of the main peak existing on the lowest bound energy side is used as the energy reference (284.8 eV).

  This SnCoC-containing material can be formed by, for example, a method in which a mixture obtained by mixing raw materials of each constituent element is melted in an electric furnace, a high-frequency induction furnace, an arc melting furnace or the like and then solidified. Also, various atomizing methods such as gas atomization or water atomization, methods using various mechanochemical reactions such as various roll methods, mechanical alloying methods, and mechanical milling methods may be used. Among these, a method using a mechanochemical reaction is preferable. This is because the SnCoC-containing material has a low crystalline or amorphous structure. In the method using the mechanochemical reaction, for example, a manufacturing apparatus such as a planetary ball mill or an attritor can be used.

  The raw material may be a mixture of individual constituent elements, but it is preferable to use an alloy for some of the constituent elements other than carbon. This is because, by adding carbon to such an alloy and synthesizing it by a method using a mechanical alloying method, a low crystalline or amorphous structure is obtained, and the reaction time is shortened. The raw material may be in the form of powder or a block.

  In addition to this SnCoC-containing material, an SnCoFeC-containing material having tin, cobalt, iron and carbon as constituent elements is also preferable. The composition of the SnCoFeC-containing material can be arbitrarily set. For example, as the composition when the iron content is set to be small, the carbon content is 9.9 mass% or more and 29.7 mass% or less, and the iron content is 0.3 mass% or more and 5.9 weight% %, And the ratio of cobalt to the total of tin and cobalt (Co / (Sn + Co)) is preferably 30% by mass or more and 70% by mass or less. In addition, for example, as a composition when the content of iron is set to be large, the content of carbon is 11.9 mass% or more and 29.7 mass% or less, and cobalt and iron with respect to the total of tin, cobalt, and iron The total ratio of (Co + Fe) / (Sn + Co + Fe)) is 26.4 mass% to 48.5 mass%, and the ratio of cobalt to the total of cobalt and iron (Co / (Co + Fe)) is 9.9 mass% It is preferable that it is 79.5 mass% or more. This is because a high energy density can be obtained in such a composition range. The crystallinity of the SnCoFeC-containing material, the method for measuring the bonding state of elements, the formation method, and the like are the same as those of the above-described SnCoC-containing material.

  As a negative electrode material capable of inserting and extracting lithium, a simple substance, an alloy or a compound of silicon, a simple substance, an alloy or a compound of tin, or a material having one or more phases thereof at least in part. The used negative electrode active material layer 12 is formed by using, for example, a gas phase method, a liquid phase method, a thermal spraying method, a coating method or a firing method, or two or more of these methods. As the vapor phase method, for example, physical deposition method or chemical deposition method, specifically, vacuum deposition method, sputtering method, ion plating method, laser ablation method, thermal chemical vapor deposition (CVD) method or Examples include plasma chemical vapor deposition. As the liquid phase method, a known method such as electrolytic plating or electroless plating can be used. The application method is, for example, a method in which a particulate negative electrode active material is mixed with a binder and then dispersed in a solvent and applied. The baking method is, for example, a method in which a heat treatment is performed at a temperature higher than the melting point of a binder or the like after coating by a coating method. A known method can also be used for the firing method, for example, an atmospheric firing method, a reactive firing method, or a hot press firing method.

  For example, the negative electrode 10 is manufactured as follows.

  First, after preparing the above-mentioned material consisting of a single layer or a plurality of layers as the base material 1A, particulate projections are formed on the surface of the base material 1A by, for example, a gas phase method or a liquid phase method (for example, electrolytic deposition method). 1B is formed. Alternatively, a powder made of metal fine particles is dissolved in a predetermined solvent to prepare a slurry, and the slurry is applied to the base material 1A and then sintered, thereby providing a particulate protrusion 1B on the surface of the base material 1A. . In this case, the metal fine particles are not limited to the spherical shape, but may be a rock shape, a block shape, or other shapes. In addition, after forming the protrusion 1B by these methods, heat treatment is further performed in a vacuum atmosphere or a non-oxidizing atmosphere to promote alloying at the interface between the base 1A and the protrusion 1B. May be. Due to the formation of the protrusion 1B, an uneven shape appears on the surface of the base 1A. The negative electrode current collector 1 is produced by forming a plating film 1C so as to connect the protruding portion 1B and the substrate 1A by plating so as not to impair the uneven shape. This plating process is so-called cover plating, and is a process for forming a dense plating film rather than particles. At this time, as shown in FIG. 1, the plating film 1C desirably covers the entire surface of the base 1A and the periphery of the protrusion 1B. You may make it provide over a part of circumference | surroundings of the projection part 1B.

  After preparing the negative electrode current collector 1, the negative electrode active material layer 2 is formed by depositing the negative electrode active material containing the above-described negative electrode material on the negative electrode current collector 1 by a vapor phase method or a liquid phase method. Moreover, after forming the precursor layer containing a particulate negative electrode active material in the negative electrode electrical power collector 1, the negative electrode active material layer 2 may be formed by the baking method which bakes this, a vapor phase method, a liquid phase method Alternatively, the negative electrode active material layer 2 may be formed by combining two or three of the firing methods. Thus, the negative electrode active material layer 2 is formed at the interface with the negative electrode current collector 1 by forming the negative electrode active material layer 2 by at least one method selected from the group consisting of a vapor phase method, a liquid phase method, and a firing method. At least a part thereof is alloyed. In order to further alloy the interface between the negative electrode current collector 1 and the negative electrode active material layer 2, it is preferable to perform a heat treatment in a vacuum atmosphere or a non-oxidizing atmosphere.

  As the vapor phase method, for example, a physical deposition method or a chemical deposition method can be used. Specifically, a vacuum deposition method, a sputtering method, an ion plating method, a laser ablation method, a thermal CVD (Chemical Vapor Deposition) A chemical vapor deposition method) or a plasma CVD method can be used. As the liquid phase method, a known method such as electrolytic plating or electroless plating can be used. As for the sintering method, a known method can be used, for example, an atmosphere sintering method, a reaction sintering method, or a hot press sintering method can be used. Thus, the negative electrode 10 is completed.

  According to the negative electrode 10, since the protrusion 1 </ b> B made of copper is provided on the surface of the base material 1 </ b> A in the negative electrode current collector 1, the contact area between the negative electrode current collector 1 and the negative electrode active material layer 2 increases. , Mutual adhesion is improved. In addition, the internal stress of the negative electrode active material layer 2 generated during expansion and contraction is dispersed by the protrusions 1B, so that the negative electrode active material layer 2 is hardly cracked. Furthermore, since the protrusion 1B is covered with the plating film 1C made of a metal other than copper together with the base 1A, the protrusion 1B is difficult to peel off from the base 1A. Therefore, in the negative electrode 10, adhesion between the negative electrode current collector 1 and the negative electrode active material layer 2 and current collection can be improved. Therefore, the negative electrode 10 can contribute to improvement of cycle characteristics when used in an electrochemical device such as a 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 negative electrode is used as follows.

(First secondary battery)
FIG. 2 shows a cross-sectional configuration of the first secondary battery. The first secondary battery is a so-called coin-type battery. The negative electrode 50 accommodated in the exterior cup 55 and the positive electrode 57 accommodated in the exterior can 54 are impregnated with an electrolyte solution. Are stacked. The peripheral portions of the outer cup 55 and the outer can 54 are sealed by caulking through an insulating gasket 56. The exterior cup 55 and the exterior can 54 are made of metal such as stainless steel or aluminum (Al), for example.

  The positive electrode 57 has a positive electrode active material layer 57B provided on one surface of a positive electrode current collector 57A. The positive electrode current collector 57A is made of, for example, aluminum, nickel, stainless steel, or the like. The positive electrode active material layer 57B contains a positive electrode active material, and may contain other materials such as a binder and a conductive agent as necessary.

The positive electrode active material includes one or more positive electrode materials capable of inserting and extracting lithium as an electrode reactant. As the positive electrode material, for example, 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, or a phosphate compound containing lithium and a transition metal element. In particular, cobalt, nickel, manganese, and iron are used as the transition metal element. What contains at least 1 sort (s) of the group which consists of 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. The values of x and y vary depending on the charge / discharge state of the secondary battery, 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 ), and lithium nickel cobalt composite oxide (Li _x Ni). _(1-z) Co _z O ₂ (z <1)), lithium nickel cobalt manganese composite oxide (Li _x Ni _(1-vw) Co _v Mn _w O ₂ (v + w <1)), or spinel type structure And a lithium manganese composite oxide (LiMn ₂ O ₄ ). Among these, a complex oxide containing cobalt is preferable. This is because high capacity can be obtained and excellent cycle characteristics can be obtained. 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). ) And the like.

  Other positive electrode materials include, for example, oxides such as titanium oxide, vanadium oxide or manganese dioxide, disulfides such as titanium disulfide or molybdenum sulfide, chalcogenides such as niobium selenide, sulfur, polyaniline or Examples also include conductive polymers such as polythiophene.

  The negative electrode 50 has the same configuration as the above-described negative electrode. For example, the negative electrode active material layer 52 is provided on the surface of the negative electrode current collector 51 facing the positive electrode active material layer 57B. . The configurations of the negative electrode current collector 51 and the negative electrode active material layer 52 are the same as the configurations of the negative electrode current collector 1 and the negative electrode active material layer 2 in the negative electrode 10 described above, respectively. That is, the negative electrode current collector 51 is obtained by covering the protrusion 51B provided on the surface of the base 51A with the plating film 51C made of a metal other than copper together with the base 51A. In the negative electrode 50, the charge capacity of the negative electrode material capable of inserting and extracting lithium is preferably larger than the charge capacity of the positive electrode 57. This is because even when fully charged, the possibility that lithium is deposited as dendrites on the negative electrode 50 is reduced.

  The separator 53 separates the positive electrode 57 and the negative electrode 50 and allows lithium ions to pass through while preventing a short circuit of current due to contact between the two electrodes. The separator 53 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, and these two or more kinds of porous films are laminated. It may be what was done. Among these, a porous film made of polyolefin is preferable because it is excellent in short-circuit preventing effect and can improve the safety of the secondary battery due to the shutdown effect. In particular, polyethylene is preferable because a shutdown effect can be obtained at 100 ° C. or higher and 160 ° C. or lower and the electrochemical stability is excellent. Polypropylene is also preferable, and other resins having chemical stability may be copolymerized with polyethylene or polypropylene, or may be blended.

  The separator 53 is impregnated with an electrolytic solution that is a liquid electrolyte. This electrolytic solution contains a solvent and an electrolyte salt dissolved in the solvent.

  The solvent contains, for example, one or more of nonaqueous solvents such as organic solvents. Examples of the non-aqueous solvent include ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, γ-butyrolactone, γ-valerolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, Methyl butyrate, methyl isobutyrate, methyl trimethylacetate, ethyl trimethylacetate, acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, N, N-dimethylformamide, N-methylpyrrolidinone, N -Methyloxazolidinone, N, N'-dimethylimidazolidinone, nitromethane, nitroethane, sulfolane, trimethyl phosphate or dimethyl sulfoxide. Among these, at least one selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate is preferable. This is because excellent capacity characteristics, cycle characteristics and storage characteristics can be obtained. In this case, in particular, a high viscosity (high dielectric constant) solvent such as ethylene carbonate or propylene carbonate (for example, relative dielectric constant ε ≧ 30) and a low viscosity solvent such as dimethyl carbonate, ethyl methyl carbonate or diethyl carbonate (for example, A combination with (viscosity ≦ 1 mPa · s) is more preferable. This is because the dissociation property of the electrolyte salt and the ion mobility are improved, so that a higher effect can be obtained.

  This solvent preferably contains a cyclic carbonate having an unsaturated bond represented by Chemical Formulas 1 to 3. This is because high cycle characteristics can be obtained. These may be used alone or in combination.

（Ｒ１１およびＲ１２は水素基あるいはアルキル基である。）

(R11 and R12 are a hydrogen group or an alkyl group.)

（Ｒ１３〜Ｒ１６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。）

(R13 to R16 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.)

（Ｒ１７はアルキレン基である。）

(R17 is an alkylene group.)

  The cyclic ester carbonate having an unsaturated bond shown in Chemical Formula 1 is a vinylene carbonate-based compound. Examples of the vinylene carbonate compound include vinylene carbonate (1,3-dioxol-2-one), methyl vinylene carbonate (4-methyl-1,3-dioxol-2-one), and 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, Examples thereof include 3-dioxol-2-one and 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 cyclic ester carbonate having an unsaturated bond shown in Chemical Formula 2 is a vinyl ethylene carbonate compound. Examples of the vinyl carbonate-based compound include vinyl ethylene carbonate (4-vinyl-1,3-dioxolan-2-one), 4-methyl-4-vinyl-1,3-dioxolan-2-one, and 4-ethyl. -4-vinyl-1,3-dioxolan-2-one, 4-n-propyl-4-vinyl-1,3-dioxolan-2-one, 5-methyl-4-vinyl-1,3-dioxolane-2 -One, 4,4-divinyl-1,3-dioxolan-2-one, 4,5-divinyl-1,3-dioxolan-2-one, and the like. Among these, vinyl ethylene carbonate is preferable. This is because it is easily available and a high effect can be obtained. Of course, as R13 to R16, all may be vinyl groups, all may be allyl groups, or vinyl groups and allyl groups may be mixed.

  The cyclic ester carbonate having an unsaturated bond shown in Chemical Formula 3 is a methylene ethylene carbonate compound. Examples of the methylene ethylene carbonate compound include 4-methylene-1,3-dioxolan-2-one, 4,4-dimethyl-5-methylene-1,3-dioxolan-2-one, and 4,4-diethyl-5. -Methylene-1,3-dioxolan-2-one and the like. This methylene ethylene carbonate compound may have one methylene group (compound shown in Chemical Formula 3) or two methylene groups.

  The cyclic carbonate having an unsaturated bond may be catechol carbonate having a benzene ring in addition to those shown in Chemical Formulas 1 to 3.

  The content of the cyclic carbonate having an unsaturated bond in the solvent is preferably 0.01% by weight or more and 10% by weight or less. This is because a sufficient effect can be obtained.

  The solvent contains at least one of a chain carbonate having a halogen represented by Chemical Formula 4 as a constituent element and a cyclic carbonate having a halogen represented by Chemical Formula 5 as a constituent element. preferable. This is because a stable protective film is formed on the surface of the negative electrode 50 and the decomposition reaction of the electrolytic solution is suppressed, so that the cycle characteristics are improved.

（Ｒ２１〜Ｒ２６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。）

(R21 to R26 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.)

（Ｒ２７〜Ｒ３０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。）

(R27 to R30 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.)

  In addition, R21 to R26 in Chemical formula 4 may be the same or different. The same applies to R27 to R30 in Chemical Formula 5. Although the kind of halogen is not specifically limited, For example, at least 1 type in the group which consists of a fluorine, chlorine, and a bromine is mentioned, Among these, a fluorine is preferable. This is because a high effect can be obtained. Of course, other halogens may be used.

  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 chain carbonate having a halogen shown in Chemical Formula 4 include fluoromethyl methyl carbonate, bis (fluoromethyl) carbonate, difluoromethyl methyl carbonate, and the like. These may be single and multiple types may be mixed.

  Examples of the cyclic carbonate having a halogen shown in Chemical formula 5 include a series of compounds represented by Chemical formula 6 and Chemical formula 7. That is, 4-fluoro-1,3-dioxolan-2-one of (1) shown in Chemical formula 6, 4-chloro-1,3-dioxolan-2-one of (2), 4,5 of (3) -Difluoro-1,3-dioxolan-2-one, (4) tetrafluoro-1,3-dioxolan-2-one, (5) 4-fluoro-5-chloro-1,3-dioxolane-2-one ON, (6) 4,5-dichloro-1,3-dioxolan-2-one, (7) tetrachloro-1,3-dioxolan-2-one, (8) 4,5-bistrifluoromethyl 1,3-dioxolan-2-one, 4-trifluoromethyl-1,3-dioxolan-2-one of (9), 4,5-difluoro-4,5-dimethyl-1,3 of (10) -Dioxolan-2-one, 4-methyl-5,5 of (11) Difluoro-1,3-dioxolan-2-one, and the like 5,5-difluoro-1,3-dioxolan-2-one (12). In addition, 4-trifluoromethyl-5-fluoro-1,3-dioxolan-2-one of (1) shown in Chemical Formula 7 and 4-trifluoromethyl-5-methyl-1,3-dioxolane of (2) 2-one, 4-fluoro-4,5-dimethyl-1,3-dioxolan-2-one of (3), 4,4-difluoro-5- (1,1-difluoroethyl)-of (4) 1,3-dioxolan-2-one, 4,5-dichloro-4,5-dimethyl-1,3-dioxolan-2-one in (5), 4-ethyl-5-fluoro-1, in (6) 3-dioxolan-2-one, 4-ethyl-4,5-difluoro-1,3-dioxolan-2-one of (7), 4-ethyl-4,5,5-trifluoro-1 of (8) , 3-Dioxolan-2-one, 4-fluoro-4-methyl-1 of (9) 3-dioxolan-2-one, and the like. These may be single and multiple types may be mixed.

  Of these, 4-fluoro-1,3-dioxolan-2-one or 4,5-difluoro-1,3-dioxolan-2-one is preferred, and 4,5-difluoro-1,3-dioxolan-2-one is preferred. 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.

The electrolyte salt includes, for example, any one or more of light metal salts such as a lithium salt. Examples of the lithium salt include lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium perchlorate, and lithium hexafluoroarsenate. This is because excellent capacity characteristics, cycle characteristics and storage characteristics can be obtained. Among these, lithium hexafluorophosphate is preferable. This is because a higher effect can be obtained because the internal resistance is lowered.

  This electrolyte salt preferably contains at least one selected from the group consisting of compounds represented by Chemical Formulas 8 to 10. This is because a higher effect can be obtained when used together with the above-described lithium hexafluorophosphate or the like. In addition, R33 in Chemical formula 8 may be the same or different. The same applies to R41 to R43 in Chemical Formula 9 and R51 and R52 in Chemical Formula 10.

（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−ＯＣ−Ｒ３２−ＣＯ−、−ＯＣ−Ｃ（Ｒ３３）₂ −あるいは−ＯＣ−ＣＯ−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 —OC—R32—CO—, —OC—C (R33) ₂ — or —OC—CO—, wherein R32 is an alkylene group, a halogenated alkylene group, an arylene group or a halogen. R33 is an alkyl group, a halogenated alkyl group, an aryl group or a halogenated aryl group, wherein 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−ＯＣ−（Ｃ（Ｒ４１）₂ ）_b4−ＣＯ−、−（Ｒ４３）₂ Ｃ−（Ｃ（Ｒ４２）₂ ）_c4−ＣＯ−、−（Ｒ４３）₂ Ｃ−（Ｃ（Ｒ４２）₂ ）_c4−Ｃ（Ｒ４３）₂ −、−（Ｒ４３）₂ Ｃ−（Ｃ（Ｒ４２）₂ ）_c4−ＳＯ₂ −、−Ｏ₂ Ｓ−（Ｃ（Ｒ４２）₂ ）_d4−ＳＯ₂ −あるいは−ＯＣ−（Ｃ（Ｒ４２）₂ ）_d4−ＳＯ₂ −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-period 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 —OC. — (C (R41) ₂ ) _b4 —CO—, — (R43) ₂ C— (C (R42) ₂ ) _c4 —CO—, — (R43) ₂ C— (C (R42) ₂ ) _c4 —C ( R43) ₂ —, — (R43) ₂ C— (C (R42) ₂ ) _c4 —SO ₂ —, —O ₂ S— (C (R42) ₂ ) _d4 —SO ₂ — or —OC— (C (R42 ₂ ) _d4— SO ₂ —, wherein R41 and R43 are a hydrogen group, 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 hydrogen group, alkyl group, halo. Or a4, e4 and n4 are 1 or 2, b4 and d4 are integers of 1 to 4, c4 is an integer of 0 to 4, and f4 and m4 are It is an integer 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−ＯＣ−（Ｃ（Ｒ５１）₂ ）_d5−ＣＯ−、−（Ｒ５２）₂ Ｃ−（Ｃ（Ｒ５１）₂ ）_d5−ＣＯ−、−（Ｒ５２）₂ Ｃ−（Ｃ（Ｒ５１）₂ ）_d5−Ｃ（Ｒ５２）₂ −、−（Ｒ５２）₂ Ｃ−（Ｃ（Ｒ５１）₂ ）_d5−ＳＯ₂ −、−Ｏ₂ Ｓ−（Ｃ（Ｒ５１）₂ ）_e5−ＳＯ₂ −あるいは−ＯＣ−（Ｃ（Ｒ５１）₂ ）_e5−ＳＯ₂ −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 —OC— (C (R51) ₂ ) _d5 —CO—, — (R52) ₂ C— (C (R51) _{2) d5 -CO -, - (} R52) 2 C- (C (R51) 2) d5 -C (R52) 2 -, - (R52) 2 C- (C (R51) 2) d5 -SO 2 -, —O ₂ S— (C (R51) ₂ ) _e5 —SO ₂ — or —OC— (C (R51) ₂ ) _e5 —SO ₂ —, wherein R51 is a hydrogen group, alkyl group, halogen group or halogen R52 represents a hydrogen group, an alkyl group, or a halo group. Or at least one of them is a halogen group or a halogenated alkyl group, wherein a5, f5 and n5 are 1 or 2, and b5, c5 and e5 are 1-4. D5 is an integer of 0 to 4, and g5 and m5 are integers of 1 to 3.)

  The group 1 elements in the long-period periodic table 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 Chemical formula 8 include the compounds represented by Chemical formulas (1) to (6). Examples of the compound represented by Chemical formula 9 include the compounds represented by Chemical formulas (1) to (8). Examples of the compound represented by Chemical formula 10 include the compound represented by Chemical formula 13 and the like. It is needless to say that the compound having the structure shown in Chemical Formula 8 to Chemical Formula 10 is not limited to the compound shown in Chemical Formula 11 to Chemical Formula 13.

  Moreover, it is preferable that electrolyte salt contains at least 1 sort (s) of the group which consists of a compound represented by Chemical formula 14-Chemical formula 16. This is because a higher effect can be obtained when used together with the above-described lithium hexafluorophosphate or the like. Note that m and n in Chemical formula 14 may be the same or different. The same applies to p, q and r in Chemical formula 16.

（ｍおよびｎは１以上の整数である。）

(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.)

（ｐ、ｑおよびｒは１以上の整数である。）

(P, q and r are integers of 1 or more.)

Examples of the chain compound shown in Chemical formula 14 include bis (trifluoromethanesulfonyl) imide lithium (LiN (CF ₃ SO ₂ ) ₂ ), bis (pentafluoroethanesulfonyl) imide lithium (LiN (C ₂ F ₅ SO ₂ ) ₂ ), (trifluoromethanesulfonyl) (pentafluoroethanesulfonyl) imide lithium (LiN (CF ₃ SO ₂ ) (C ₂ F ₅ SO ₂ )), (trifluoromethanesulfonyl) (heptafluoropropanesulfonyl) imide lithium ( LiN (CF ₃ SO ₂ ) (C ₃ F ₇ SO ₂ )) or (trifluoromethanesulfonyl) (nonafluorobutanesulfonyl) imidolithium (LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ )) Can be mentioned. These may be single and multiple types may be mixed.

  Examples of the cyclic compound represented by Chemical formula 15 include a series of compounds represented by Chemical formula 17. That is, 1,2-perfluoroethanedisulfonylimide lithium of (1) shown in Chemical formula 17, 1,3-perfluoropropane disulfonylimide lithium of (2), 1,3-perfluorobutane of (3) Disulfonylimide lithium, 1,4-perfluorobutane disulfonylimide lithium of (4), and the like. These may be single and multiple types may be mixed. Among these, 1,3-perfluoropropane disulfonylimide lithium is preferable. This is because a high effect can be obtained.

Examples of the chain compound shown in Chemical formula 16 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, outside this range, the ion conductivity may be extremely lowered.

  The electrolytic solution may contain various additives along with the solvent and the electrolyte salt. This is because the chemical stability of the electrolytic solution is further improved.

  Examples of this additive include sultone (cyclic sulfonic acid ester). This sultone is, for example, propane sultone or propene sultone, among which propene sultone is preferable. These may be single and multiple types may be mixed.

  Moreover, as an additive, an acid anhydride is mentioned, for example. Examples of the acid anhydride include carboxylic acid anhydrides such as succinic acid anhydride, glutaric acid anhydride and maleic acid anhydride, disulfonic acid anhydrides such as ethanedisulfonic acid anhydride and propanedisulfonic acid anhydride, Examples thereof include carboxylic acid and sulfonic acid anhydrides such as benzoic acid anhydride, sulfopropionic acid anhydride and sulfobutyric acid anhydride, among which sulfobenzoic acid anhydride and sulfopropionic acid anhydride are preferable. These may be single and multiple types may be mixed.

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

  First, the positive electrode 57 is produced. First, a positive electrode active material, a binder, and a conductive agent are mixed to prepare a positive electrode mixture, which is 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 one surface of the positive electrode current collector 57A by a doctor blade or a bar coater and dried. Furthermore, the positive electrode active material layer 57B is formed by compression molding the coating film with a roll press or the like while heating as necessary. In this case, compression molding may be repeated a plurality of times. Finally, the positive electrode 57 is obtained by punching out the positive electrode current collector 57A on which the positive electrode active material layer 57B is formed into pellets having a predetermined diameter.

  Further, the negative electrode 50 is manufactured by the same procedure as that of the negative electrode 10 described above. Specifically, first, the protrusion 51B is formed on the surface of the base 51A, and the negative electrode current collector 51 is manufactured by covering with a plating film 51C. After that, the negative electrode active material layer 52 is formed on the surface of the negative electrode current collector 51 on which the protrusions 51B and the plating film 51C are provided, and punched out to form pellets having a predetermined diameter.

  Subsequently, the positive electrode 57, the negative electrode 50, and the separator 53 were stacked so that the positive electrode active material layer 57 </ b> B and the negative electrode active material layer 52 face each other with the separator 53 interposed therebetween, and then accommodated in the outer can 54. After that, an electrolytic solution is injected, and the outer cup 55 is covered and caulked through the gasket 56, thereby completing the first secondary battery having a coin type.

  In the first secondary battery, lithium ions are occluded and released between the positive electrode 57 and the negative electrode 50. That is, when charged, for example, lithium ions are extracted from the positive electrode 57 and inserted into the negative electrode 50 through the electrolytic solution impregnated in the separator 53. On the other hand, when discharging is performed, for example, lithium ions are released from the negative electrode 50 and inserted into the positive electrode 57 through the electrolytic solution impregnated in the separator 53.

  According to the coin-type secondary battery, since the negative electrode 50 has the same configuration as the negative electrode 10 described above, adhesion between the negative electrode current collector 51 and the negative electrode active material layer 52 and current collection are improved. And excellent cycle characteristics can be realized.

  In particular, the solvent of the electrolytic solution is at least one of a chain carbonate having a halogen shown in Chemical Formula 1 and a cyclic carbonate having a halogen shown in Chemical Formula 2 or unsaturated shown in Chemical Formula 5 to Chemical Formula 7. If at least one of cyclic carbonic acid esters having a bond, sultone, or an acid anhydride is contained, higher effects can be obtained.

  The electrolyte salt of the electrolyte salt is at least one selected from the group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate and lithium hexafluoroarsenate, A higher effect can be obtained if at least one of the group consisting of the compounds shown in the formula (1) or at least one of the group consisting of the compounds shown in formulas (14) to (16) is contained.

  The effects of the secondary battery other than those described above are the same as those of the negative electrode 10 described above.

(Secondary secondary battery)
3 and 4 show a cross-sectional configuration of the second secondary battery, and FIG. 4 shows a cross section taken along line IV-IV shown in FIG. The secondary battery described here is a lithium ion secondary battery, similar to the first secondary battery described above.

  In the second secondary battery, a wound electrode body 20 having a flat wound structure is housed inside a battery can 11.

  The battery can 11 is, for example, a square exterior member. As shown in FIG. 4, the rectangular exterior member has a rectangular or substantially rectangular cross section in the longitudinal direction (partly including a curve), and is a rectangular prismatic battery. In addition to this, an oval prismatic battery is also configured. That is, the square-shaped exterior member is a bottomed rectangular type or bottomed oval shaped vessel-like member having a rectangular shape or a substantially rectangular shape (oval shape) obtained by connecting arcs with straight lines. FIG. 4 shows a case where the battery can 11 has a rectangular cross-sectional shape. The battery structure including the battery can 11 is called a so-called square shape.

  The battery can 11 is made of, for example, a metal material such as iron, aluminum, or an alloy thereof, and may have a function as an electrode terminal. In this case, iron that is harder than aluminum is preferable in order to suppress swelling of the secondary battery by utilizing the hardness (hardness of deformation) of the battery can 11 during charging and discharging. In the case where the battery can 11 is made of iron, for example, plating such as nickel may be applied.

  The battery can 11 has a hollow structure in which one end and the other end are closed and opened, respectively, and an insulating plate 12 and a battery lid 13 are attached to the open end of the battery can 11 so as to be sealed. The insulating plate 12 is disposed between the wound electrode body 20 and the battery lid 13 so as to be perpendicular to the winding peripheral surface of the wound electrode body 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 in the same manner.

  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 at substantially the center of the battery cover 13, and the through hole is electrically connected to the terminal plate 14 and electrically insulated from the battery cover 13 through the gasket 17. Thus, the positive electrode pin 15 is inserted. The gasket 17 is made of, for example, an insulating material, and 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 wound electrode body 20 is obtained 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 a metal material such as aluminum is attached to the end of the positive electrode 21 (for example, the inner terminal), and an end (for example, the outer terminal) of the negative electrode 22 is made of a metal material such as nickel. A configured negative electrode lead 25 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.

  The positive electrode 21 is, for example, provided with a positive electrode active material layer 21B 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 configurations of the positive electrode current collector 21A and the positive electrode active material layer 21B are the same as those of the positive electrode current collector 57A and the positive electrode active material layer 57B in the first secondary battery described above, respectively.

  The negative electrode 22 has the same configuration as that of the negative electrode 10 described above. For example, the negative electrode active material layer 22B is provided on both surfaces of the 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 negative electrode 10 described above, respectively. 3 and 4, the protrusions and the plating film in the negative electrode 22 are not shown. In the negative electrode 22, the chargeable capacity of the negative electrode material capable of inserting and extracting lithium is preferably larger than the discharge capacity of the positive electrode 21.

  The separator 23 and the electrolyte solution impregnated in the separator 23 are the same as the separator 53 and the electrolyte solution impregnated in the separator 53 of the first secondary battery, respectively.

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

  First, the positive electrode 21 is produced. First, a positive electrode active material, a positive electrode binder, and a positive electrode conductive material 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, using a doctor blade or a bar coater, the positive electrode mixture slurry is uniformly applied to both surfaces of the positive electrode current collector 21A and dried. Furthermore, the positive electrode active material layer 21 </ b> B is formed by compression-molding the coating film using a roll press machine or the like while heating as necessary. In this case, compression molding may be repeated a plurality of times.

  Next, in the same manner as the preparation procedure of the negative electrode 10 described above, the negative electrode current collector 22A is manufactured by forming protrusions on both surfaces of the base material and covering with a plating film, and the negative electrode current collector 22A has negative electrodes on both surfaces. The active material layer 22B is formed to produce the negative electrode 22.

  Next, the wound electrode body 20 is produced using the positive electrode 21 and the negative electrode 22. First, the positive electrode lead 24 is attached to the positive electrode current collector 21A by welding or the like, and the negative electrode lead 25 is attached to the negative electrode current collector 22A by welding or the like. Subsequently, after laminating the positive electrode 21 and the negative electrode 22 via the separator 23, the wound electrode body 20 is manufactured by forming it into a flat shape while being wound in the longitudinal direction.

  The secondary battery is assembled as follows. First, after the wound electrode body 20 is accommodated in the battery can 11, the insulating plate 12 is disposed on the wound electrode body 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. 3 and 4 is completed.

  In the secondary battery, when charged, for example, lithium ions are extracted 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, when discharging is performed, for example, lithium ions are released from the negative electrode 22 and inserted into the positive electrode 21 through the electrolytic solution impregnated in the separator 23.

  According to this rectangular secondary battery, since the negative electrode 22 has the same configuration as the negative electrode 10 described above, cycle characteristics can be improved.

  In addition, if the battery can 11 is made of a hard metal, the negative electrode 22 is less likely to be damaged when the negative electrode active material layer 22B expands and contracts compared to a case where the battery can 11 is made of a soft film. Therefore, the cycle characteristics can be further improved. In this case, a higher effect can be obtained if the battery can 11 is made of iron that is harder than aluminum. The effects of the secondary battery other than those described above are the same as those of the first secondary battery.

(Third secondary battery)
5 and 6 show a cross-sectional configuration of the third secondary battery, and FIG. 6 shows an enlarged part of the spirally wound electrode body 40 shown in FIG. The third secondary battery is, for example, a lithium ion secondary battery, similar to the first and second secondary batteries described above. The third secondary battery mainly includes a winding tube in which a positive electrode 41 and a negative electrode 42 are stacked and wound inside a substantially hollow cylindrical battery can 31 via a separator 43 impregnated with a predetermined electrolytic solution. The rotating electrode body 40 and a pair of insulating plates 32 and 33 are accommodated. The battery structure including the battery can 31 is called a so-called cylindrical type. The positive electrode 41 is, for example, one in which a positive electrode active material layer 41B is provided on both surfaces of a positive electrode current collector 41A, and the negative electrode 42 is, for example, in which a negative electrode active material layer 42B is provided on both surfaces of a negative electrode current collector 42A. is there. The configurations of the positive electrode current collector 41A, the positive electrode active material layer 41B, the negative electrode current collector 42A, the negative electrode active material layer 42B, and the separator 43, and the composition of the electrolytic solution are respectively the positive electrode current collector in the first secondary battery described above. The configurations of 57A, the positive electrode active material layer 57B, the negative electrode current collector 51, the negative electrode active material layer 52 and the separator 53, and the composition of the electrolytic solution are the same. 5 and 6, the protrusions and the plating film in the negative electrode 42 are not shown.

  The battery can 31 is made of, for example, the same metal material as that of the battery can 11 in the second secondary battery described above, and one end and the other end thereof are closed and opened, respectively. 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 thermal resistance element (Positive Temperature Coefficient: PTC element) 36 provided on the inside of the battery can 31 are caulked through a gasket 37 at the open end of the battery can 31. It is attached. Thereby, the inside of the battery can 31 is sealed. The battery lid 34 is made of, for example, the same metal 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 this 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 resistor element 36 limits the current by increasing the resistance in accordance with the temperature rise, and prevents abnormal heat generation due to a large current. The gasket 37 is made of, for example, an insulating material, and asphalt is applied to the surface thereof.

  A center pin 44 may be inserted in the center of the wound electrode body 40. In the wound electrode body 40, a positive electrode lead 45 made of a metal material such as aluminum is connected to the positive electrode 41, and a negative electrode lead 46 made of a metal material such as nickel 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.

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

  First, for example, the positive electrode 41 is formed by forming the positive electrode active material layer 41B on both surfaces of the positive electrode current collector 41A by the same procedure as the positive electrode 21 and the negative electrode 22 in the second secondary battery described above. Then, the negative electrode active material layer 42B is formed on both surfaces of the negative electrode current collector 42A to produce the negative electrode 42. 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, 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 attached. It welds 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 and fixed to the opening end of the battery can 31 via the gasket 37. Thereby, the secondary battery shown in FIGS. 5 and 6 is completed.

  In the secondary battery, when charged, for example, lithium ions are extracted from the positive electrode 41 and inserted in the negative electrode 42 through the electrolytic solution. On the other hand, when discharging is performed, for example, lithium ions are released from the negative electrode 42 and inserted into the positive electrode 41 through the electrolytic solution.

  According to this cylindrical secondary battery, since the negative electrode 42 has the same configuration as the negative electrode 10 described above, cycle characteristics can be improved. The effects of the secondary battery other than those described above are the same as those of the first secondary battery.

(Fourth secondary battery)
FIG. 7 shows an exploded perspective configuration of the fourth secondary battery, and FIG. 8 shows an enlarged cross section along the line VIII-VIII shown in FIG. The fourth secondary battery is a lithium ion secondary battery similarly to the first to third secondary batteries described above. In the fourth secondary battery, a wound electrode body 70 to which a positive electrode lead 71 and a negative electrode lead 72 are attached is mainly housed in a film-shaped exterior member 60. The battery structure including the exterior member 60 is called a so-called laminate film type.

  For example, the positive electrode lead 71 and the negative electrode lead 72 are led out in the same direction from the inside of the exterior member 60 to the outside. The positive electrode lead 71 is made of, for example, a metal material such as aluminum, and the negative electrode lead 72 is made of, for example, a metal material such as copper, nickel, or stainless steel. These metal materials are, for example, in a thin plate shape or a mesh shape.

  The exterior member 60 is made of, for example, an aluminum laminated film in which a nylon film, an aluminum foil, and a polyethylene film are bonded together in this order. The exterior member 60 has a structure in which, for example, the outer edges of two rectangular aluminum laminate films are bonded to each other by fusion or an adhesive so that the polyethylene film faces the wound electrode body 70. ing.

  An adhesive film 61 is inserted between the exterior member 60 and the positive electrode lead 71 and the negative electrode lead 72 in order to prevent intrusion of outside air. The adhesion film 61 is made of a material having adhesion to the positive electrode lead 71 and the negative electrode lead 72. Examples of such a material include polyolefin resins such as polyethylene, polypropylene, modified polyethylene, and modified polypropylene.

  In addition, the exterior member 60 may be composed of a laminate film having another laminated structure instead of the above-described aluminum laminate film, or may be composed of a polymer film such as polypropylene or a metal film.

  The wound electrode body 70 is obtained by laminating and winding a positive electrode 73 and a negative electrode 74 via a separator 75 and an electrolyte 76, and an outermost peripheral portion thereof is protected by a protective tape 77.

  The positive electrode 73 is, for example, one in which the positive electrode active material layer 73B is provided on both surfaces of the positive electrode current collector 73A, and the negative electrode 74 is, for example, in which the negative electrode current collector 74A is provided on both surfaces with the negative electrode active material layer 74B. is there. The configurations of the positive electrode current collector 73A, the positive electrode active material layer 73B, the negative electrode current collector 74A, the negative electrode active material layer 74B, and the separator 73 are respectively the positive electrode current collector 57A and the positive electrode active material layer in the first secondary battery described above. The configurations of 57B, the negative electrode current collector 51, the negative electrode active material layer 52, and the separator 53 are the same. 7 and 8, the protrusions and the plating film in the negative electrode 74 are not shown.

  The electrolyte 76 includes an electrolytic solution and a polymer compound that holds the electrolytic solution, and is a so-called gel electrolyte. The gel electrolyte is preferable because high ion conductivity (for example, 1 mS / cm or more at room temperature) is obtained and liquid leakage is prevented.

  Examples of the polymer compound include polyacrylonitrile, polyvinylidene fluoride, a copolymer of polyvinylidene fluoride and polyhexafluoropyrene, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, polyphosphazene, poly Examples thereof include siloxane, polyvinyl acetate, polyvinyl alcohol, polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, styrene-butadiene rubber, nitrile-butadiene rubber, polystyrene, and polycarbonate. These may be single and multiple types may be mixed. Among these, polyacrylonitrile, polyvinylidene fluoride, polyhexafluoropropylene or polyethylene oxide 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 76 which is a gel electrolyte, the solvent of the electrolytic solution is a wide concept including not only a liquid solvent but also an ion conductive substance capable of dissociating the electrolyte salt. Accordingly, when a polymer compound having ion conductivity is used, the polymer compound is also included in the solvent.

  Instead of the gel electrolyte 76 in which the electrolytic solution is held by the polymer compound, the electrolytic solution may be used as it is. In this case, the separator 75 is impregnated with the electrolytic solution.

  The secondary battery including the gel electrolyte 76 is manufactured by, for example, the following three types of procedures.

  In the first manufacturing method, first, the positive electrode active material layer 73B is formed on both surfaces of the positive electrode current collector 73A, for example, by the same procedure as the positive electrode 21 and the negative electrode 22 in the second secondary battery described above. Thus, the negative electrode 74 is manufactured by forming the negative electrode active material layer 74B on both surfaces of the negative electrode current collector 74A. Subsequently, a precursor solution containing an electrolytic solution, a polymer compound, and a solvent is prepared and applied to the positive electrode 73 and the negative electrode 74, and then the solvent is volatilized to form a gel electrolyte 76. Subsequently, the positive electrode lead 71 is attached to the positive electrode current collector 73A, and the negative electrode lead 72 is attached to the negative electrode current collector 74A. Subsequently, the positive electrode 73 and the negative electrode 74 on which the electrolyte 76 is formed are stacked and wound via the separator 75, and then a protective tape 77 is adhered to the outermost peripheral portion to produce the wound electrode body 70. Finally, for example, after the wound electrode body 70 is sandwiched between two film-shaped exterior members 60, the outer edge portions of the exterior member 60 are bonded to each other by heat fusion or the like, so that the wound electrode body 70 is Encapsulate. At this time, the adhesion film 61 is inserted between the positive electrode lead 71 and the negative electrode lead 72 and the exterior member 60. Thereby, the secondary battery shown in FIGS. 7 and 8 is completed.

  In the second manufacturing method, first, the positive electrode lead 71 is attached to the positive electrode 73 and the negative electrode lead 72 is attached to the negative electrode 74. Subsequently, after the positive electrode 73 and the negative electrode 74 are laminated and wound via the separator 75, a protective tape 77 is adhered to the outermost periphery thereof, and the wound body that is a precursor of the wound electrode body 70. 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 interior of the 60, the opening of the exterior member 60 is sealed by heat sealing or the like. Finally, the gel electrolyte 76 is formed by thermally polymerizing the monomer to obtain a polymer compound. Thereby, the secondary battery shown in FIGS. 7 and 8 is completed.

  In the third manufacturing method, a wound body is formed by forming a wound body in the same manner as in the above-described second manufacturing method, except that the separator 75 coated with the polymer compound on both sides is used first. 60 is housed inside. Examples of the polymer compound applied to the separator 75 include a polymer containing vinylidene fluoride as a component, that is, a homopolymer, a copolymer, or a multi-component copolymer. Specifically, polyvinylidene fluoride, binary copolymers containing vinylidene fluoride and hexafluoropropylene as components, and ternary copolymers 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 75 is brought into close contact with the positive electrode 73 and the negative electrode 74 through the polymer compound. As a result, the electrolytic solution is impregnated into the polymer compound, and the polymer compound is gelled to form the electrolyte 76. Thus, the secondary battery shown in FIGS. 7 and 8 is completed.

  In the third manufacturing method, the swollenness of the secondary battery is suppressed as compared with the first manufacturing method. Further, in the third manufacturing method, compared to the second manufacturing method, there are hardly any monomers or solvents that are raw materials for the polymer compound remaining in the electrolyte 76, and the formation process of the polymer compound is well controlled. Therefore, sufficient adhesion is obtained between the positive electrode 73, the negative electrode 74, the separator 75, and the electrolyte 76.

  According to this laminated film type secondary battery, since the negative electrode 74 has the same configuration as the negative electrode 10 described above, cycle characteristics can be improved. The effects of the secondary battery other than those described above are the same as those of the first secondary battery.

  Examples of the present invention will be described in detail.

(Example 1-1)
The coin-type secondary battery shown in FIG. 2 was manufactured by the following procedure. At this time, a lithium ion secondary battery in which the capacity of the negative electrode 50 was expressed based on insertion and extraction of lithium was made.

First, the positive electrode 57 was produced. First, lithium carbonate (Li ₂ CO ₃ ) and cobalt carbonate (CoCO ₃ ) were mixed at a molar ratio of 0.5: 1, and then fired in air at 900 ° C. for 5 hours, so that the average particle size was 5 μm. Lithium cobalt composite oxide (LiCoO ₂ ) was obtained. Subsequently, 96 parts by mass of the lithium cobalt composite oxide as a positive electrode active material, 1 part by mass of carbon black as a positive electrode conductive material, and 3 parts by mass of polyvinylidene fluoride as a positive electrode binder are mixed, and a positive electrode mixture is obtained. After that, the mixture was dispersed in N-methyl-2-pyrrolidone to obtain a paste-like positive electrode mixture slurry. Further, the positive electrode mixture slurry is uniformly applied to one surface of the positive electrode current collector 57A made of a strip-shaped aluminum foil (thickness = 15 μm), dried, and then compression-molded with a roll press to obtain a positive electrode active material Layer 57B was formed. Finally, a positive electrode 57 was obtained by punching out the positive electrode current collector 57A on which the positive electrode active material layer 57B was formed into pellets having a diameter of 15.5 mm.

Next, the negative electrode 50 was produced. First, an electrolytic copper foil having a thickness of 15 μm that was not roughened was prepared as the base 51A, and then a protrusion 51B made of copper fine particles was formed on one surface of the base 51A by electrolytic deposition. Specifically, a plating bath containing 50 g / dm ^{3 of} copper sulfate pentahydrate (CuSO ₄ .5H ₂ O), 100 g / dm ^{3 of} sulfuric acid, and 1 g / dm ^{3 of} gelatin is maintained at 30 ° C., and 30 A / By energizing for 5 seconds at a current density of dm ² , fine copper particles having an average diameter of 2.0 μm were deposited. Subsequently, a plating process (cover plating) was performed to form a plating film 51C that continuously covers the protrusion 51B and the base 51A. Here, a plating bath containing 100 g / dm ^{3 of} cobalt sulfate heptahydrate (CoSO ₄ .7H ₂ O) and 10 g / dm ^{3 of} boric acid is maintained at 60 ° C., and the current density is 15 A at a current density of 10 A / dm ^2. A plating film 51C made of cobalt was formed by energizing for a second. Further, the weight ratio X / Y = 1.0 (X is the weight per unit area of the plating film 51C, and Y is the total weight per unit area of the base material 51A and the protrusion 51B). did. As a result, a negative electrode current collector 51 having a surface roughness Rz value of 2.5 μm was obtained. After that, a negative electrode active material layer 52 made of silicon and having a thickness of 6 μm was formed on one surface of the negative electrode current collector 51 by an electron beam vapor deposition method, and further punched into pellets having a diameter of 16 mm to obtain the negative electrode 50. .

  The weights X and Y can be obtained as follows, for example. The weight X can be obtained, for example, by comparing the weight of the base 51A before forming the protrusions 51B with the total weight after forming the protrusions 51B and the plating film 51C on the base 51A. The weight of the base material 51A can also be calculated from its thickness. The weight Y is an element (here, copper) in the negative electrode current collector 51 in which the protrusions 51B and the plating film 51C are formed by inductively coupled plasma (ICP) analysis, energy dispersive X-ray analysis (EDS), or the like. And the abundance ratio of cobalt), and can be calculated from the relationship between the total weight and the weight X.

  Subsequently, the separator 53 made of the positive electrode 57, the negative electrode 50, and the microporous polypropylene film is laminated so that the positive electrode active material layer 57 </ b> B and the negative electrode active material layer 52 face each other with the separator 53 interposed therebetween, and then the outer can 54. Housed in. After that, an electrolytic solution was injected, and the outer cup 55 was covered and caulked through the gasket 56 to complete a coin-type secondary battery.

Here, the electrolyte solution, were mixed with ethylene carbonate and (EC) and diethyl carbonate (DEC) and vinylene carbonate (VC) as a solvent was dissolved lithium hexafluorophosphate (LiPF ₆₎ as an electrolyte salt Things were used. At this time, the composition of the solvent (EC: DEC: VC) was 30:60:10 by weight, and the content of LiPF ₆ was 1.0 mol / kg with respect to the solvent.

(Example 1-2)
Other than that, the plating film 51C made of nickel was formed using a plating bath containing 200 g / dm ^{3 of} nickel sulfate hexahydrate (NiSO ₄ .6H ₂ O) and 30 g / dm ^{3 of} boric acid. A coin-type secondary battery was fabricated in the same manner as in Example 1-1.

(Example 1-3)
Plating made of iron using a plating bath containing 250 g / dm ^{3 of} iron sulfate heptahydrate (FeSO ₄ .7H ₂ O) and 100 g / dm ^{3 of} iron chloride hexahydrate (FeCl ₃ .6H ₂ O) A coin-type secondary battery was fabricated in the same manner as in Example 1-1 except that the film 51C was formed.

(Example 1-4)
A coin-type secondary battery was fabricated in the same manner as in Example 1-1 except that a commercially available zinc plating bath (for example, manufactured by High-Purity Chemical) was used and the plated film 51C made of zinc was formed.

(Example 1-5)
Using a commercially available iron-cobalt alloy plating bath (for example, manufactured by High-Purity Chemical Co., Ltd.), except that the plated film 51C made of iron-cobalt alloy (FeCo) was formed, the rest of the coin type was the same as in Example 1-1. A secondary battery was produced.

(Comparative Example 1-1)
Except that the plating film 51C made of copper was formed using a plating bath containing 200 g / dm ^{3 of} copper sulfate pentahydrate (CuSO ₄ .5H ₂ O) and 100 g / dm ^{3 of} sulfuric acid. A coin-type secondary battery was produced in the same manner as in 1-1.

(Comparative Example 1-24
A coin-type secondary battery was fabricated in the same manner as in Example 1-1 except that the plating film 51C was not formed.

  When the cycle characteristics of the secondary batteries of Examples 1-1 to 1-5 and Comparative examples 1-1 and 1-2 were examined, the results shown in Table 1 were obtained.

  Specifically, charging / discharging was performed in the following manner in an atmosphere at 23 ° C. First, for charging, constant current charging was performed at a constant current of 0.2 C until the battery voltage reached 4.2 V, and then constant voltage charging was performed at a constant voltage of 4.2 V until the current value reached 0.05 C. . Next, for discharging, constant current discharging was performed at a constant current of 0.2 C until the battery voltage reached 2.5V. This combination of charge and discharge is defined as one cycle, and charge and discharge are repeated up to 100 cycles. As a discharge capacity retention rate (cycle characteristics), the ratio of the discharge capacity at the 100th cycle to the discharge capacity at the first cycle, that is, the discharge Capacity retention ratio (%) = (discharge capacity at the 100th cycle / discharge capacity at the first cycle) × 100 was calculated.

  The procedure and conditions for examining the cycle characteristics described above are the same for the evaluation of the same characteristics regarding a series of examples and comparative examples.

  As shown in Table 1, in Examples 1-1 to 1-5, the electrolytic copper foil as the base material 51A is provided with the protrusions 51B made of copper fine particles and is made of a metal other than copper so as to cover them. Since the plating film 51C is provided, the discharge capacity is maintained as compared with the case where the plating film 51C made of copper is formed (Comparative Example 1-1) and the case where the plating film 51C is not formed (Comparative Example 1-2). The rate has increased. This is because, in Examples 1-1 to 1-5, the protrusions 51B provided on the base material 51A are firmly protected by the plating film 51C to sufficiently exhibit the anchor effect, and the negative electrode current collector 51 and the negative electrode active This is considered to be a result of improving the adhesion with the material layer 52 and the current collecting property. In particular, it has been found that the plating film 51C made of iron, cobalt, nickel, and FeCo is more effective. In Comparative Example 1-2 where the plating film 51C does not exist, the adhesion between the negative electrode current collector and the copper particles was extremely weak, and the discharge capacity retention rate was also extremely low.

(Examples 2-1 to 2-8)
A coin is formed in the same manner as in Example 1-1 except that the weight ratio X / Y is changed as shown in Table 2 below by adjusting the energization time when forming the plating film 51C. A type secondary battery was produced. Here, the surface roughness Rz was not greatly changed by, for example, adding a predetermined additive to the plating bath when the protrusion 51B was deposited.

  When the cycle characteristics of the secondary batteries of Examples 2-1 to 2-8 were examined, the results shown in Table 2 were obtained.

  As shown in Table 2, a particularly high discharge capacity retention ratio was obtained when the weight ratio X / Y was greater than 0.5 and less than 5.0.

(Example 3-1)
When forming the protrusion 51B, a plating bath containing 50 g / dm ^{3 of} copper sulfate pentahydrate (CuSO ₄ .5H ₂ O), 100 g / dm ^{3 of} sulfuric acid, and 1.2 g / dm ^{3 of} gelatin is used. A coin-type secondary battery was fabricated in the same manner as in Example 1-1 except that the surface roughness Rz was changed as shown in Table 3 below by adjusting the energization time. .

(Example 3-2)
When forming the protrusion 51B, and copper sulfate pentahydrate _{(CuSO 4 · 5H 2 O)} 45g / dm 3, and sulfuric acid 100 g / dm ^3, with use of the plating bath containing gelatin 1.5 g / dm ³ A coin-type secondary battery was fabricated in the same manner as in Example 1-1 except that the surface roughness Rz was changed as shown in Table 3 below by adjusting the energization time. .

(Example 3-3)
When forming the protrusion 51B, a plating bath containing 40 g / dm ^{3 of} copper sulfate pentahydrate (CuSO ₄ .5H ₂ O), 100 g / dm ^{3 of} sulfuric acid, and 2.0 g / dm ^{3 of} gelatin is used. A coin-type secondary battery was fabricated in the same manner as in Example 1-1 except that the surface roughness Rz was changed as shown in Table 3 below by adjusting the energization time. .

(Example 3-4)
When forming the protrusion 51B, a plating bath containing 40 g / dm ^{3 of} copper sulfate pentahydrate (CuSO ₄ .5H ₂ O), 100 g / dm ^{3 of} sulfuric acid, and 1.5 g / dm ^{3 of} gelatin is used. A coin-type secondary battery was fabricated in the same manner as in Example 1-1 except that the surface roughness Rz was changed as shown in Table 3 below by adjusting the energization time. .

(Example 3-5)
When forming the protrusion 51B, a plating bath containing 35 g / dm ^{3 of} copper sulfate pentahydrate (CuSO ₄ .5H ₂ O), 100 g / dm ^{3 of} sulfuric acid, and 1.2 g / dm ^{3 of} gelatin is used. A coin-type secondary battery was fabricated in the same manner as in Example 1-1 except that the surface roughness Rz was changed as shown in Table 3 below by adjusting the energization time. .

(Example 3-6)
When forming the protrusion 51B, a plating bath containing 30 g / dm ^{3 of} copper sulfate pentahydrate (CuSO ₄ .5H ₂ O), 100 g / dm ^{3 of} sulfuric acid, and 1.0 g / dm ^{3 of} gelatin is used. A coin-type secondary battery was fabricated in the same manner as in Example 1-1 except that the surface roughness Rz was changed as shown in Table 3 below by adjusting the energization time. .

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

  As shown in Table 3, when the weight ratio X / Y was 1.0, a particularly high discharge capacity retention rate was obtained when the surface roughness Rz value was 3.2 μm or more and 5.2 μm or less.

(Example 4-1)
Instead of EC and VC as a solvent, 4-fluoro-1,3-dioxolan-2-one (FEC), which is one of the cyclic carbonates having a halogen shown in Chemical Formula 5, was added, and the composition of the solvent (FEC: A coin-type secondary battery was fabricated in the same manner as in Example 1-1 except that DEC) was changed to 50:50 by weight.

(Example 4-2)
Instead of VC as a solvent, 4,5-difluoro-1,3-dioxolan-2-one (DFEC), which is one of the cyclic carbonates having a halogen shown in Chemical Formula 5, was added, and the composition of the solvent (FEC: A coin-type secondary battery was fabricated in the same manner as in Example 1-1 except that DEC: DFEC was changed to 30: 65: 5 by weight.

(Examples 4-3 and 4-4)
Except that the acid anhydride sulfobenzoic anhydride (SBAH: Example 4-3) or sulfopropionic anhydride (SPAH: Example 4-4) was added to the electrolyte as an additive. A coin-type secondary battery was produced in the same manner as in Example 4-2. At this time, the contents of SBAH and SPAH in the electrolytic solution were 1% by weight. This “1 wt%” means that PRS or the like is added by an amount corresponding to 1 wt% when the entire solvent is 100 wt%.

(Example 4-5)
Other than the addition of lithium tetrafluoroborate (LiBF ₄ ) as the electrolyte salt, the LiPF ₆ content was changed to 0.9 mol / kg, and the LiBF ₄ content was changed to 0.1 mol / kg. A coin-type secondary battery was produced in the same manner as in Example 4-2.

  When the cycle characteristics of the secondary batteries of Examples 4-1 to 4-5 were examined, the results shown in Table 4 were obtained.

As shown in Table 4, it was found that when FEC or DFEC was added as a solvent, the discharge capacity retention rate was further improved. In addition, when SBAH or SPAH is added as an additive to the electrolyte (Examples 4-3 and 4-4), or when LiBF ₄ is added as an electrolyte salt (Example 4-5), The result was almost the same as when not added (Example 4-2).

(Examples 5-1 to 5-6)
Example 1 except that the average diameter of the protrusion 51B was changed as shown in Table 5 below by adjusting the energization time when forming the copper particles by the electrolytic deposition method. In the same manner as in Example 1, a coin-type secondary battery was produced. Even in this case, the surface roughness Rz was not changed greatly.

  When the cycle characteristics of the secondary batteries of Examples 5-1 to 5-6 were examined, the results shown in Table 5 were obtained. Table 5 also shows the value of the surface roughness Rz.

  As shown in Table 5, a particularly high discharge capacity retention rate was obtained when the average diameter of the protrusions 51B was 0.5 μm or more and 5.0 μm or less.

  In each of the above examples and comparative examples, the protruding portion 51B made of copper fine particles was formed by electrolytic deposition. However, when the protruding portion 1B was provided on the surface of the base material 51A as follows. A similar trend was also observed. That is, when the powder of copper fine particles is dispersed in N-methyl-2-pyrrolidone to produce a slurry, and the slurry is uniformly applied to the base material 51A and then sintered to form the protrusion 1B. In addition, the same results as in the above-mentioned Examples and Comparative Examples were obtained.

  Although the present invention has been described with reference to the embodiments and examples, the present invention is not limited to the embodiments and examples, and various modifications can be made. For example, in the above embodiments and examples, a battery using lithium as an electrode reactant has been described. However, other alkali metals such as sodium (Na) or potassium (K), or alkalis such as magnesium or calcium (Ca) are used. The present invention can also be applied to the case of using an earth metal or another light metal such as aluminum. At that time, the positive electrode active material capable of inserting and extracting the electrode reactant is selected according to the electrode reactant.

  Further, in the above embodiments and examples, a secondary battery or a coin-type secondary battery including a battery element (winding electrode body) having a cylindrical and flat (elliptical) winding structure is specifically described. However, the present invention is not limited to a secondary battery including a battery element having a polygonal winding structure, a structure in which a positive electrode and a negative electrode are folded, or a structure in which a plurality of layers are stacked. The present invention can be similarly applied to a secondary battery including the battery element. In addition, the present invention can be similarly applied to secondary batteries having other exterior shapes such as a square shape.

  In the above embodiments and examples, the case where a liquid electrolytic solution is used as the electrolyte has been described. However, a gel electrolyte in which the electrolytic solution is held in a holding body such as a polymer compound may be used. . Examples of such a polymer compound include polyacrylonitrile, polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, and polyphosphazene. , Polysiloxane, polyvinyl acetate, polyvinyl alcohol, polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, styrene-butadiene rubber, nitrile-butadiene rubber, polystyrene or polycarbonate. In particular, polyacrylonitrile, polyvinylidene fluoride, polyhexafluoropropylene, or polyethylene oxide is preferable from the viewpoint of electrochemical stability. Although the ratio of the polymer compound to the electrolytic solution varies depending on the compatibility thereof, it is usually preferable to add a polymer compound corresponding to 5% by mass or more and 50% by mass or less of the electrolytic solution.

  Furthermore, in the above-described embodiments and examples, the appropriate ranges derived from the results of the examples were explained for the surface roughness and the weight ratio X / Y in the negative electrode current collector of the secondary battery of the present invention. The explanation does not completely deny the possibility that these parameters are outside the above-mentioned range. That is, the appropriate range described above is a particularly preferable range for obtaining the effects of the present invention, and each parameter may be slightly deviated from the above ranges as long as the effects of the present invention are obtained.

It is sectional drawing showing the structure of the negative electrode which concerns on one embodiment of this invention. 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 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 showing the structure of the arrow direction along the IV-IV line of the wound electrode body shown in FIG. It is sectional drawing 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 which expands and represents a part of winding electrode body shown in FIG. It is a disassembled perspective view showing the structure of the 4th secondary battery provided with the negative electrode which concerns on one embodiment of this invention. It is sectional drawing showing the structure of the arrow direction along the VIII-VIII line of the wound electrode body shown in FIG.

Explanation of symbols

  10, 22, 42, 50 ... negative electrode, 1, 22A, 42A, 51 ... negative electrode current collector, 1A, 51A ... substrate, 1B, 51B ... projection, 1C, 51C ... plating film, 2, 22B, 42B, 52 ... Negative electrode active material layer, 21, 41, 57, 73 ... Positive electrode, 21A, 41A, 57A, 73A ... Positive electrode current collector, 21B, 41B, 57B, 73B ... Positive 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, 56 ... Gasket, 18 ... Cleavage valve, 19 ... Injection hole, 19A ... Sealing member, 20, 40, 70 ... Winding electrode body, 23, 43, 53, 75 ... Separator, 24, 45, 71 ... Positive electrode lead, 25, 46, 72 ... Negative electrode lead, 35A ... Disc plate, 35 ... Safety valve mechanism, 36 ... Heat sensitive element 44 ... center pin, 54 ... outer can, 55 ... outer cup, 60 ... outer member, 61 ... adhesive film, 76 ... electrolyte, 77 ... protective tape.

Claims (22)

A conductive base material provided with a protrusion made of copper on the surface;
A negative electrode current collector comprising: a plating film that continuously covers at least a part of the protrusion and at least a part of the surface of the base material and is made of a metal other than copper. The negative electrode current collector according to claim 1, wherein the protrusions are copper fine particles deposited by electrolytic deposition. The negative electrode current collector according to claim 1, wherein the plating film includes at least one selected from the group consisting of a simple substance and a compound of cobalt (Co), iron (Fe), or nickel (Ni). The negative electrode current collector according to claim 3, wherein a ratio of the weight of the plating film to the total weight of the base material and the protrusion is greater than 0.5 and less than 5.0. 2. The negative electrode current collector according to claim 1, wherein the surface roughness is 3.2 μm or more and 5.2 μm or less in terms of a ten-point average roughness Rz value. The negative electrode current collector according to claim 1, wherein an average diameter of the protrusions is 0.5 μm or more and 5.0 μm or less. The negative electrode current collector according to claim 1, wherein the base material is made of copper or a copper alloy and has a thickness of 8 μm to 25 μm. A negative electrode current collector, and a negative electrode active material layer provided on the negative electrode current collector and including at least one member selected from the group consisting of a simple substance and a compound of silicon (Si),
The negative electrode current collector continuously covers the conductive base material provided with a protrusion made of copper on the surface on the negative electrode active material layer side, the protrusion and the surface of the base material, and A negative electrode having a plating film made of a metal other than copper. The negative electrode according to claim 8, wherein the protrusion is a copper fine particle deposited by electrolytic deposition. The negative electrode according to claim 8, wherein the plating film includes at least one selected from the group consisting of a simple substance and a compound of cobalt (Co), iron (Fe), or nickel (Ni). 11. The negative electrode according to claim 10, wherein a ratio of the weight of the plating film to the total weight of the base material and the protrusion is greater than 0.5 and less than 5.0. The negative electrode according to claim 8, wherein the negative electrode current collector has a surface roughness of 3.2 μm or more and 5.2 μm or less as a ten-point average roughness Rz value. The negative electrode according to claim 8, wherein an average diameter of the protrusions is 0.5 μm or more and 5.0 μm or less. The negative electrode according to claim 8, wherein the base material is made of copper or a copper alloy and has a thickness of 8 μm to 25 μm. An electrolyte is provided with a positive electrode and a negative electrode,
The negative electrode includes a negative electrode current collector, and a negative electrode active material layer provided on the negative electrode current collector and including at least one member selected from the group consisting of a simple substance and a compound of silicon (Si),
The negative electrode current collector continuously covers a conductive base material provided with a protrusion made of copper on the surface on the negative electrode active material layer side, the protrusion and the surface of the base material, and A secondary battery having a plating film made of a metal other than copper. The secondary battery according to claim 15, wherein the plating film includes at least one selected from the group consisting of a simple substance and a compound of cobalt (Co), iron (Fe), or nickel (Ni). The secondary battery according to claim 15, wherein a ratio of the weight of the plating film to the total weight of the base material and the protrusion is greater than 0.5 and less than 5.0. The secondary battery according to claim 15, wherein the base material is made of copper or a copper alloy and has a thickness of 8 μm to 25 μm. The secondary battery according to claim 15, wherein the negative electrode active material layer is formed by a vapor phase method. The electrolyte includes at least one of 4-fluoro-1,3-dioxolan-2-one and 4,5-difluoro-1,3-dioxolan-2-one as a solvent. Secondary battery. The secondary battery according to claim 15, wherein the electrolyte includes an electrolyte salt containing at least one of lithium hexafluorophosphate (LiPF ₆ ) and lithium tetrafluoroborate (LiBF ₄ ). The secondary battery according to claim 15, wherein the electrolyte includes at least one of sulfobenzoic anhydride and sulfopropionic anhydride.

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