JP2012190727A - Electrode plate for nonaqueous electrolyte secondary battery, nonaqueous electrolyte secondary battery, and battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode plate for a nonaqueous electrolyte secondary battery which is excellent in output/input characteristics and cycle characteristics, and also to provide the nonaqueous electrolyte secondary battery using the electrode plate for the nonaqueous electrolyte secondary battery as a positive electrode plate and/or a negative electrode plate, and a battery pack.SOLUTION: The electrode plate for the nonaqueous electrolyte secondary battery is constituted by containing a metal oxide capable of lithium ion insertion/elimination reaction in an electrode active material layer as a binder for fixing electrode active material particles onto a current collector, and installing a coating layer made of the metal oxide at least at a part of the current collector surface.

Description

  The present invention relates to a nonaqueous electrolyte secondary battery electrode plate, a nonaqueous electrolyte secondary battery, and a battery pack.

  A non-aqueous electrolyte secondary battery represented by a lithium ion secondary battery has a high energy density and a high voltage, and has a memory effect during charging / discharging (when the battery is charged before it is completely discharged, Since there is no phenomenon in which the capacity decreases, it is used in various fields such as portable devices and large devices.

At present, efforts are being made to reduce CO ₂ emissions on a global scale. Plug-in hybrids that can greatly contribute to CO ₂ reduction by reducing the dependence on oil and enabling driving with low environmental impact. There is an urgent need to develop and spread next-generation clean energy vehicles such as automobiles and electric cars. Driving power that does not depend on gasoline is essential for the development and popularization of these next-generation clean energy vehicles. Non-aqueous electrolyte secondary batteries represented by lithium ion secondary batteries are expected as the driving force.

  Currently, various proposals of non-aqueous electrolyte secondary batteries include a positive electrode plate, a negative electrode plate, a separator, and a non-aqueous electrolyte solution. As the positive electrode plate, one having an electrode active material layer containing a positive electrode active material on a current collector such as a metal foil is generally used. In general, the negative electrode plate includes an electrode active material layer containing a negative electrode active material on a current collector such as a copper foil or an aluminum foil.

  For example, as a conventionally known electrode plate, there is known an electrode plate in which electrode active material particles are fixed on a current collector with a binder made of polyvinylidene fluoride (PVDF) resin, thereby forming an electrode active material layer. (For example, Patent Document 1). In addition, as an alternative to PVDF, styrene butadiene copolymer (SBR), carboxymethyl cellulose (CMC), or a water-based binder in which a mixed material of SBR and CMC is dispersed in water is used as a resin binder. Yes.

  On the other hand, the present applicant has developed an electrode plate in which an electrode active material layer is formed by fixing electrode active material particles on a current collector with a metal oxide (for example, Patent Documents 2 to 11). ). Alternatively, there has been proposed a positive electrode plate in which positive electrode active material particles are fixed on a current collector with a positive electrode active material binder on a current collector to form an electrode active material layer (Patent Document 12).

JP 2006-310010 A WO2010 / 122922A1 WO2010 / 122983A1 WO2010 / 122984A1 WO2010 / 122974A1 WO2010 / 122975A1 JP 2010-272503 A JP 2010-272512 A JP 2010-272511 A JP 2010-272510 A JP 2010-272509 A JP 2009-181879 A

  Here, the electrode plate for a non-aqueous electrolyte secondary battery has a feature that it is repeatedly used for charging and discharging. Therefore, the electrode plate for a non-aqueous electrolyte secondary battery has a problem that it exhibits high input / output characteristics and can maintain the high input / output characteristics even by repeatedly charging and discharging.

  The present invention has been made in view of the above problems, and provides an electrode plate for a non-aqueous electrolyte secondary battery that exhibits high input / output characteristics and can maintain the input / output characteristics even by repeated charge and discharge. Another object of the present invention is to provide a non-aqueous electrolyte secondary battery and a battery pack using the electrode plate for a non-aqueous electrolyte secondary battery of the present invention.

The present invention
(1) A nonaqueous electrolyte secondary battery electrode plate comprising a current collector and an electrode active material layer formed on the current collector, wherein an alkali is provided between the current collector and the electrode active material layer. A coating layer in which a metal oxide capable of insertion / release reaction covers the current collector is formed, and the electrode active material layer is formed of electrode active material particles, a conductive material, and a metal forming the coating layer A binder that is the same metal oxide as the oxide, and the electrode active material particles and the conductive material are fixed to the current collector and / or the coating layer by the binder. Non-aqueous electrolyte secondary battery electrode plate,
(2) A triple structure in which the current collector, the coating layer covering the current collector, and the conductive material fixed to the coating layer are connected to each other is formed. The electrode plate for a non-aqueous electrolyte secondary battery according to (1) above,
(3) In the non-aqueous electrolyte secondary battery comprising at least a positive electrode plate, a negative electrode plate, a separator provided between the positive electrode plate and the negative electrode plate, and an electrolyte solution containing a non-aqueous solvent, the positive electrode A nonaqueous electrolyte secondary battery, wherein at least one of the plate and the negative electrode plate is an electrode plate for a nonaqueous electrolyte secondary battery according to (1) or (2),
(4) A storage case, a nonaqueous electrolyte secondary battery including a positive electrode terminal and a negative electrode terminal, and a protection circuit having an overcharge and overdischarge protection function are provided, and the storage case includes the nonaqueous electrolyte secondary battery. In the battery pack configured to house the battery and the protection circuit, the non-aqueous electrolyte secondary battery includes a positive electrode plate including an electrode active material, a negative electrode plate, and the positive electrode plate and the negative electrode plate. A non-aqueous electrolyte secondary battery comprising at least a separator provided and an electrolytic solution containing a non-aqueous solvent, wherein at least one of the positive electrode plate and the negative electrode plate is the above (1) or (2) A battery pack, which is an electrode plate for a non-aqueous electrolyte secondary battery according to any one of the above,
Is the gist.

The electrode plate for a non-aqueous electrolyte secondary battery of the present invention is excellent in output / input characteristics, and the excellent input / output characteristics are well maintained even by repeated charge / discharge, and excellent in cycle characteristics.

  A non-aqueous electrolyte secondary battery and a battery pack configured using the electrode plate for a non-aqueous electrolyte secondary battery of the present invention reflect the above effects of the electrode plate for a non-aqueous electrolyte secondary battery of the present invention. Thus, it is possible to improve the input / output characteristics and maintain good output / input characteristics even by repeated charging and discharging to improve the cycle characteristics.

It is a schematic diagram which shows the cross section at the time of cut | disconnecting the electrode plate of this invention substantially perpendicularly to the collector surface. 2A to 2D are schematic cross-sectional views illustrating exemplary embodiments of the current collector used in the present invention. It is a schematic sectional drawing in one form of the lithium ion secondary battery of this invention. It is a schematic exploded view in one embodiment of the battery pack of this invention. 5A is a TEM photograph of observing a cross section of the electrode active material layer of Reference Example 1, and 5B maps silicon contained as a marker to the metal oxide in the cross section of the electrode active material layer of Reference Example 1, It is the TEM photograph which confirmed the metal oxide.

  Hereinafter, an electrode plate for a non-aqueous electrolyte secondary battery of the present invention (hereinafter sometimes simply referred to as “electrode plate”), a non-aqueous electrolyte secondary battery and a battery pack using the electrode plate of the present invention are described. The form for implementing is demonstrated in order.

[Electrode plate for non-aqueous electrolyte secondary battery]
The electrode plate of the present invention is a nonaqueous electrolyte secondary battery electrode plate comprising a current collector and an electrode active material layer formed on the current collector, wherein the electrode active material layer comprises an electrode active material layer. It contains substance particles and a metal oxide binder (hereinafter also simply referred to as “metal oxide binder”) which is a metal oxide capable of alkali ion insertion / release reaction. A coating layer is formed between the current collector and the electrode active material layer, in which a metal oxide capable of alkali insertion / release reaction covers the current collector.

  The alkali metal that contributes to charging / discharging contained in the metal oxide binder in the present invention contributes to charging / discharging in the non-aqueous electrolyte secondary battery, as exemplified by lithium in the lithium ion secondary battery. Any alkali metal may be used. For example, other than lithium, sodium, potassium and the like can be mentioned, but the present invention is not limited thereto. In the present specification, a metal capable of lithium ion insertion and desorption reaction is mainly used as a metal oxide capable of alkali ion insertion and desorption reaction, taking as an example the electrode plate of the present invention that can be used for a lithium ion secondary battery. Although the present invention will be described in an aspect using an oxide, the description is not intended to exclude the aspect of the present invention in which an alkali metal other than lithium acts during charging and discharging.

  In FIG. 1, the cross-sectional schematic of one embodiment of the electrode plate of this invention is shown. The electrode plate 10 is configured such that an electrode active material layer 2 is provided on a current collector 1, and a coating layer 15 </ b> A is provided between the current collector 1 and the electrode active material layer 2. The electrode active material layer 2 includes electrode active material particles 13, conductive material particles 14, and a metal oxide binder 15, and there are voids 16 between them. The electrode active material particles 13, the conductive material particles 14, and the electrode active material particles 13 and the conductive material particles 14 are fixed on the current collector 1 with a metal oxide binder 15, whereby the electrode An active material layer 2 is formed. Further, the same metal oxide as the metal oxide binder 15 covers the current collector 1 to form a coating layer 15A. In FIG. 1, the coating layer 15A covers substantially the entire surface of the current collector 1. However, in the present invention, the coating layer does not have to cover the entire surface of the current collector, and the coating layer is a current collector. It is only necessary to partially cover the body.

  Electrode plate 10 includes a triple structure including current collector 1, coating layer 15 </ b> A covering current collector 1, and electrode active material particles 13 </ b> A fixed to coating layer 15 </ b> A. By providing the triple structure, the cycle characteristics of the electrode plate 10 tend to be further improved, which is desirable. On the other hand, the electrode plate 10 may include electrode active material particles 13B that are directly fixed to the current collector 1, and such a fixing mode is preferable from the viewpoint of improving the input / output characteristics of the electrode plate.

  The electrode plate 10 includes a triple structure including the current collector 1, a coating layer 15 </ b> A covering the current collector 1, and a conductive material 14 </ b> A fixed to the coating layer 5 </ b> A. Such a triple structure is desirable from the viewpoint of providing a conductive path with good durability that connects the electrode active material particles 13 and the current collector 1 in the electrode plate 10, and further improves the cycle characteristics of the electrode plate 10. It is also desirable from the viewpoint of tending to On the other hand, the electrode plate 10 may include conductive material particles 14B that are in direct contact with the current collector 1, and such an adhering mode is preferable from the viewpoint of improving the input / output characteristics of the electrode plate.

  The covering layer 15 </ b> A in the electrode plate 10 is intermittently formed on substantially the entire surface between the current collector 1 and the electrode active material layer 2. That is, as illustrated by reference numeral 17, there is a slight break between the coating layer 15A and the coating layer 15A, and the contact surface between the current collector 1 and the electrode active material particles 13B or the current collector. The coating layer 15A is also discontinuous at the contact surface between the body 1 and the conductive material particles 14B. The coating layer 15 </ b> A includes such a discontinuous portion, and may be provided on substantially the entire surface between the current collector 1 and the electrode active material layer 2. Alternatively, although not shown in the drawings, in the present invention, which is different from the electrode plate, the coating layer made of the metal oxide binder has substantially no discontinuous portion on the current collector, and is not between the current collector and the electrode active material layer. The current collector may be coated substantially continuously over substantially the entire surface. Thus, the electrode plate of the present invention in which the coating layer is provided on substantially the entire surface between the current collector and the electrode active material layer is preferable because it can exhibit particularly high cycle characteristics. However, the above description does not exclude an aspect in which the coating layer in the present invention is provided in a part between the current collector and the electrode active material layer. This is because in the present invention in which the coating layer is provided in part between the current collector and the electrode active material layer, the cycle characteristics are sufficiently improved.

  The coating layer and the electrode active material layer in the present invention may not substantially have an interface. Therefore, the electrode plate of the present invention includes a portion where the metal oxide that forms the coating layer and the metal oxide that is the metal oxide binder contained in the electrode active material layer are continuously connected. May be. Thus, the structure in which the metal oxide that forms the coating layer and the metal oxide that is the metal oxide binder contained in the electrode active material layer are continuously connected is the production of the electrode plate of the present invention described later. It is understood from the method. That is, when the electrode active material layer forming liquid is applied to the current collector to form a coating film, and the electrode active material layer forming step is performed by means such as heating, the current collector is coated to be generated. It is because a metal oxide may become a coating layer.

  In the present invention, the case of being fixed by a metal oxide binder includes the following two aspects. That is, the above-mentioned fixing mode is between the objects to be bonded (for example, between the electrode active material particles, between the electrode active material particles and the current collector surface, or when using a conductive material, the conductive material and the electrode active material). When the metal oxide binder is interposed between the particles and between the conductive material particles (hereinafter referred to as “fixing mode 1”), the objects to be fixed are in direct contact with each other and surround the contact portion. And the case where the adherends are fixed together by the presence of the metal oxide binder (hereinafter referred to as “fixing mode 2”). In many embodiments of the present invention, either one or both of the fixing modes 1 and 2 described above are present in the electrode active material layer.

  In the case where the electrode active material layer is configured to include either or both of the fixing modes 1 and 2, the present invention exhibits an excellent effect in terms of improving the conductivity. In order to understand the above effect, attention is paid particularly to the adhesion between the conductive material particles in the electrode active material layer containing the conductive material particles. When the conductive material particles are fixed by the fixing mode 1, the binding material of the present invention is a metal oxide. Therefore, compared to the conventional resin binding material, electrons between the conductive material particles It is difficult to become an obstacle to interaction. Furthermore, when the conductive material particles are fixed by the fixing mode 2, since the particles are in direct contact with each other, the flow of electrons is naturally smooth, and excellent conductivity is ensured. . The same can be said for the above-mentioned effect regarding the adhesion between the conductive material particles and the active material particles. In addition, at the boundary between the current collector and / or the coating layer and the electrode active material layer, the current collector and / or the coating layer and the electrode active material particles and the conductive material particles are fixed through the binder. Or they are brought into direct contact and fixed by the presence of a binder around the contact portion. Therefore, the flow of electrons between the current collector and the electrode active material layer is smooth for the same reason as described above. That is, the electrode plate of the present invention has a metal oxide as a binder in the electrode active material layer, a coating layer on the current collector, and various configurations depending on the fixing modes 1 and / or 2. The electrical resistance can be kept low by fixing the material, and it is particularly preferable that the fixing modes 1 and 2 are mixed.

  The electrode plate of the present invention having the above configuration exhibits an advantageous effect of being excellent in output / input characteristics. The reason why the input / output characteristics in the present invention are improved is not clear, but the present inventors have, as one of the causes of the above effect, a metal oxide that exhibits an active material action on the surface of the electrode active material particles. The electrode active material particles are fixed to each other while adhering to each other, and the electrode active material particles are fixed to the current collector. Therefore, the mutual adhesion is high, and as a result, excellent input / output characteristics are not exhibited. I guess that. In particular, in the state where at least a part of the surface of the electrode active material particles is covered with the metal oxide binder, the improvement of the input / output characteristics is better.

  In addition, the present invention includes a coating layer formed by coating the current collector with a metal oxide capable of inserting and releasing an alkali metal, so that the movement of electrons between the electrode active material layer and the current collector is smooth and good. It is preferable because the input / output characteristics are easily obtained.

  As described above, the electrode plate of the present invention having excellent output / input characteristics can be maintained well even when the excellent input / output characteristics are repeatedly charged and discharged, and the effect of excellent cycle characteristics is exhibited. The present inventors infer the reason why the electrode plate of the present invention exhibits excellent cycle characteristics as follows.

  The deterioration due to the use of the electrode plate for a non-aqueous electrolyte secondary battery, or the non-aqueous electrolyte secondary battery and battery pack using the same, as well as the deterioration of the electrode active material particles themselves, the current collector and the electrode active material It was considered that the electrical resistance in the electrode plate increased due to the deterioration of the adhesion state with the particles. That is, it has been inferred that resin binders that have been widely used are likely to deteriorate by repeated charge and discharge. It has been suggested that alkaline ions such as lithium ions are inserted into and desorbed from the electrode active material particles during charging and discharging, and at this time, the electrode active material particles expand and contract. When the electrode active material particles expand and contract, the resin binder that fixes the electrode active material particles is also affected by the expansion and contraction, and is forced to expand and contract. By repeating this, the resin binder deteriorates. As a result, it was speculated that the fixed state might deteriorate. It was speculated that this deterioration of the fixed state was remarkable particularly at the interface between the current collector and the electrode active material layer.

  On the other hand, the metal oxide binder and the metal oxide forming the coating layer in the present invention are metal oxides capable of alkali ion insertion / release reaction. It is presumed that alkali metal ions such as lithium ions are inserted into and desorbed from the metal, and expansion and contraction are caused accordingly. That is, in the electrode plate of the present invention, the electrode active material particles, the metal oxide binder, and the metal oxide forming the coating layer expand and contract in synchronism during charging and discharging. There is little or no physical failure in the metal oxide forming the layer, and therefore, the maintenance of a good binding state is significantly greater than that of the resin binder, resulting in durability against repeated charge and discharge It is presumed that the property is excellent. In particular, since the electrode plate of the present invention is provided with the above-mentioned coating layer, the fixing state at the interface between the current collector and the electrode active material layer is well maintained over a long period of time, and as a result, excellent cycle characteristics in the present invention are exhibited. It is inferred that

(Electrode active material layer)
Hereinafter, the electrode active material layer in the present invention will be described more specifically. As described above, the electrode active material layer in the present invention includes electrode active material particles, a conductive material, and a metal oxide binder.

  The thickness of the electrode active material layer in the present invention can be appropriately designed in consideration of electrode capacity and input / output characteristics required for the electrode plate. In general, the thickness of the electrode active material layer is designed to be 200 μm or less, more generally 100 μm or more and 150 μm or less. However, in the positive electrode plate of the present invention, the electrode active material layer can be formed very thin, and conversely, it can be formed thicker than 200 μm. In order to achieve a thin film, it can be realized by thinly applying an electrode active material layer forming liquid, which will be described later, onto the current collector, and then heating, depending on the particle size of the electrode active material particles used. An electrode active material layer having a thickness of 300 nm or more and 200 μm or less can be formed. From the viewpoint that the electrode capacity can be improved while improving the input / output characteristics, the thickness of the electrode active material layer is particularly preferably 300 nm to 150 μm, and more preferably 500 nm to 100 μm. On the other hand, in order to increase the film thickness beyond 200 μm, it is possible to adjust the viscosity of the electrode active material layer described later to a value suitable for application, or to apply it twice or more. In addition, when enlarging a film thickness, it is desirable to contain a electrically conductive material in an electrode active material layer.

Electrode active material particles:
The electrode active material particles contained in the electrode active material layer in the electrode plate of the present invention are electrode active material particles that exhibit a lithium ion insertion / release reaction generally used in electrode plates for non-aqueous electrolyte secondary batteries. If there is, it will not be specifically limited. The electrode active material particles in the positive electrode and the electrode active material particles in the negative electrode may be determined as the positive electrode active material particles and the negative electrode active material particles depending on the potential difference between the positive electrode plate and the negative electrode plate that are actually combined. In general, as the electrode active material particles in the positive electrode plate, for example, a _{LiCoO 2, LiMn 2 O 4,} LiNiO 2, LiFeO 2, LiTiO 2, LiFePO 4, Li 4 Ti 5 lithium and a transition metal, such as _{O 12} Including a lithium transition metal composite oxide, or a metal oxide having the same content as the chemical formula described above, the composition ratio of which is changed, or an element in which some of the metal oxides are different Examples thereof include substituted metal oxides. Further, as a general example of the electrode active material particles in the negative electrode plate of the present invention, for example, natural graphite, artificial graphite, amorphous carbon, carbon black, or carbonaceous materials such as those obtained by adding different elements to these components Active material particles made of a material, or electrode active material particles made of a material capable of inserting and releasing lithium ions, such as metallic lithium and its alloys, tin, silicon, and alloys thereof, or SiO ₂ , V ₂ O ₅ , metal oxides such as Li ₄ Ti ₅ O ₁₂ or the above-described examples, those in which the composition ratio is changed, and those in which some elements are replaced with other elements can be mentioned.

  The particle diameter of the electrode active material particles used in the present invention is not particularly limited, and those having an arbitrary size can be appropriately selected and used. In particular, with the positive electrode plate of the present invention using active material particles having a small particle diameter, the total amount of the surface area of the active material particles in the electrode active material layer can be increased, and within one active material particle Since it is possible to shorten the distance of lithium movement, the input / output characteristics can be dramatically improved. From the viewpoint of improving the input / output characteristics, the particle diameter of the active material particles to be used is preferably less than 10 μm, more preferably 5 μm or less, and particularly preferably 1 μm or less. In the case of producing an electrode plate using only a resin binder as a binder, the electrode active material layer forming liquid becomes a slurry, and if the active material particle diameter used is less than 10 μm, the coating suitability becomes poor. If the thickness is 5 μm or less, the fluidity of the forming liquid becomes extremely poor, making it difficult to apply to mass production equipment such as a printing press, and if it is 1 μm or less, the active material particles are dispersed in the forming liquid. It itself tended to be difficult. On the other hand, when the present invention is manufactured, a metal oxide binder is included as a binder, or the binder is substantially only a metal oxide binder, so that Since the problem is avoided, the particle diameter of the active material particles can be arbitrarily selected. The particle diameter of the active material particles shown in the present specification is an average particle diameter (volume median particle diameter: D50) measured by laser diffraction / scattering particle size distribution measurement.

  The particle diameter of the electrode active material particles contained in the electrode active material layer is arbitrarily selected from electron microscope observation results using image analysis type particle size distribution measurement software (manufactured by Mount Tech Co., Ltd., MAC VIEW). It can be obtained by measuring the longest diameter of active material particles (for example, about 10) and calculating the average value.

Metal oxide binder:
The metal oxide binder contained in the electrode active material layer is a metal oxide capable of lithium ion insertion / release reaction, and is contained in the electrode active material layer to collect the active material particles and the conductive material. Any material can be used as long as it can be fixed on the electric body. In the present invention, the metal oxide constituting the metal oxide binder includes a metal phosphorus oxide.

  In the present invention, whether or not the metal oxide binder exhibits a lithium ion insertion / elimination reaction can be confirmed by an electrochemical measurement (cyclic voltammetry) method.

  Alternatively, an electrode active material layer in an already completed electrode plate is observed with a transmission electron microscope, and the crystal lattice of a metal oxide as a binder is the same as the crystal lattice of a compound known as a conventionally known active material If so, it can be determined that the metal oxide as the binder is a metal oxide capable of lithium ion insertion / release reaction. However, the method for confirming the presence or absence of the lithium ion insertion / release reaction of the metal oxide binder is not limited to the above.

The metal oxide binder in the present invention is not particularly limited as long as it is an oxide of an element generally understood as a metal. More specifically, the metal oxide includes Li, Be, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Cs, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, A metal oxide containing one kind of metal element selected from the group consisting of Tl, Pb, Bi, Fr, Ra and Ce, or a composite metal oxide containing two or more kinds of metal elements selected from the above group; can do. Such metal oxides include SiO ₂ , V ₂ O _{5 and the} like.

  The metal oxide in the present invention is desirable because it can be suitably used as an electrode plate of a lithium ion secondary battery by selecting a lithium composite oxide. In particular, when the metal oxide is a composite oxide of any one or more transition metals and lithium selected from transition elements such as cobalt, nickel, manganese, iron, and titanium, lithium It is preferable because an electrode plate suitable for an ion secondary battery can be provided. More specifically, in the electrode active material layer in the electrode plate for a lithium ion secondary battery, the metal oxide can act as a binder and can also act as an active material. In addition, an electrode plate having an increased electrode capacity can be provided, which is preferable.

The metal element oxides listed above are metal oxides in which oxygen is bonded to any one of the above metal elements, or a composite metal containing two or more metal elements selected from the above metal elements Any of oxides may be used. In the case of using the electrode plate of the present invention as a positive electrode plate, preferred examples of the metal oxide binder _{is, LiCoO 2, LiMn 2 O 4} , LiNiO 2, LiFeO 2, LiTiO 2, LiFePO 4, V 2 O 5, Li ₄ Ti ₅ O ₁₂ or the like, or those in which the composition ratio of the metal element contained in the above metal oxide is changed, or some of the metal elements contained in the above metal oxide and other elements The substituted one can be mentioned. Similarly, preferable examples of the metal oxide binder when the electrode plate of the present invention is used as the negative electrode plate include Li ₄ Ti ₅ O ₁₂ , SiO ₂ , or the above-described metal oxide. Examples include those in which the composition ratio of the metal element is changed, or those in which part of the metal element contained in the metal oxide described above is replaced with another element. However, the metal oxide binder contained in the electrode plate of the present invention is not limited to the above examples.

  As exemplified above, since the metal oxide in the present invention is a metal oxide capable of lithium ion insertion / release reaction, it can also act as an active material. In view of the combination of the electrode active material particles and the metal oxide that is a binding material for fixing the electrode active material particles on the current collector, a combination of the positive electrode active material particles and the metal oxide that can be the positive electrode active material, Or the combination of a negative electrode active material particle and the metal oxide which can become a negative electrode active material is preferable.

  In particular, an embodiment in which the metal oxide material constituting the electrode active material particles and the metal oxide as the binder are the same compound is a preferred embodiment for solving the intended problem of the present invention. . That is, during charge and discharge, when lithium ions expand and contract with the electrode active material particles due to insertion / desorption, the metal oxide binder is expected to expand and contract in the same manner as the electrode active material particles. Because.

  In the present invention, that the electrode active material particles and the metal oxide binder are the same compound means that both are compounds containing the same metal element, and the electrode active material particles and the metal oxide binder are the same. Adhesive materials include those shown by completely the same chemical formula and those having different composition ratios. Further, the electrode active material particles and the metal oxide binder are compounds containing the same metal element, and any element in the electrode active material particles and the metal oxide binder or both compounds is Both compounds can be understood to be identical even if they are substituted to the extent that they do not depart from the spirit of the present invention.

  Further, as another method for determining that the electrode active material particles and the metal oxide binder are the same compound by another means other than the analysis of the chemical composition, the crystal structure of the compound may be confirmed. In other words, a compound that is an electrode active material particle and a compound that is a metal oxide binder are observed with a transmission electron microscope. If the crystal structures of the two compounds are the same, they are determined to be the same compound. can do. Here, the same crystal structure means that the crystal structure is included in the same crystal phase. In other words, when the active material particles and the metal oxide are not the same, it means that the crystal structures of the two are located in different crystal phases, and the narrowly defined identity based on the difference in symmetry of the crystal lattice. Not intended.

  In the present invention, the mixing ratio of the electrode active material particles and the metal oxide binder in the electrode active material layer is not particularly specified, and the type and size of the electrode active material particles used, the metal oxide binder It can be determined as appropriate in consideration of the type and functions required of the electrode. For example, in the electrode active material layer, when the weight ratio of the electrode active material particles is 100 parts by weight, the weight ratio of the metal oxide binder is 1 part by weight or more and 50 parts by weight or less. Can do. If it is less than 1 part by weight, the electrode active material particles may not be satisfactorily fixed on the current collector. On the other hand, the description of the upper limit of the weight ratio of the metal oxide binder is not intended to exclude that the metal oxide binder exceeds 50 parts by weight in the present invention.

Coating layer:
The covering layer in the present invention is a layer formed by covering the current collector with a metal oxide capable of alkali insertion / release reaction between the current collector and the electrode active material layer. The metal oxide forming the coating layer and the metal oxide contained in the metal oxide binder are the same. The “same metal oxide” as used herein refers to an embodiment in which the constituent elements of the metal oxide and the composition ratio thereof are completely the same, and an embodiment in which the constituent elements of the metal oxide are the same, but the composition ratio is different. Including. Therefore, since the metal oxide which comprises a coating layer is the same as the metal oxide contained in the metal oxide binder mentioned above, description is omitted in this paragraph.

  The thickness of the coating layer in the present invention is not particularly limited, but contributes to the improvement of the input / output characteristics of the present invention and the improvement of the cycle characteristics to maintain the excellent input / output characteristics in the range of 3 nm to 20 nm. . Further, even when the metal oxide binder constituting the coating layer is made of a metal oxide having low conductivity, the thickness between the electrode active material particles and the current collector is within the above thickness range. There is no worry about blocking the movement of electrons.

Conductive material:
The electrode active material layer in the present invention contains a conductive material. By containing a conductive material in the present invention, the conductivity of the electrode plate can be increased. Moreover, the present invention contains a metal oxide as a binder, and as described above, the conductive material and the conductive material and the current collector, and the conductive material and the electrode active material particles have an excellent fixing mode. Since it is realized, an excellent effect is exhibited by the use of the conductive material in the present invention.

  As the conductive material, those usually used for electrode plates for non-aqueous electrolyte secondary batteries can be used, and examples thereof include carbon materials such as acetylene black and carbon black such as ketjen black. It is not limited to. The average particle size of the conductive material is preferably about 20 nm to 50 nm. Also, as a different conductive material, a fibrous carbon conductive material such as VGCF is known.

  When the conductive material is contained in the electrode active material layer, the content is not particularly limited, but in general, the conductive material is 100 parts by weight with respect to the total amount of the electrode active material particles and the metal oxide binder. It is desirable that the ratio is 5 parts by weight or more and 20 parts by weight or less.

Additive:
The electrode active material layer can be composed only of the above-described active material particles, a metal oxide as a binder, and a conductive material, but is optional in the range not departing from the gist of the present invention, An additive may be contained.

  In the present invention, the electrode active material particles can be fixed on the current collector without using a resin binder. This indicates that the resin component is contained in the electrode active material layer. This is not a ban. For example, when assembling a battery using a negative electrode plate, it is necessary to soak the electrolyte into the pores of the negative electrode plate. At this time, in order to improve the permeability of the electrolyte solution, the resin component in the electrode active material layer May be contained in an amount of about 1 to 10%. Thus, if necessary, a small amount of resin material may be contained in the electrode active material layer in the present invention. Alternatively, as the binder, in addition to the metal oxide binder, a resin binder may be included in the electrode active material layer. An example of a method for infiltrating the resin binder into the electrode active material layer will be described together in the description of the production method of the present invention described later.

(Current collector)
The current collector used in the present invention is not particularly limited as long as it is a current collector that can be generally used for an electrode plate for a nonaqueous electrolyte secondary battery. For example, the current collector is preferably a nickel foil, an aluminum foil or the like formed from a single element or an alloy, or a highly conductive foil such as a carbon sheet, a carbon plate, and a carbon textile. It is not limited to these. Moreover, the member understood as a sheet | seat, a film, a board, etc. other than the member with the small film thickness generally understood as foil may be sufficient. The current collector used in the present invention may be a current collector that has been subjected to surface processing on the surface on which the electrode active material layer is to be formed, if necessary. Examples of the current collector that has been subjected to surface processing treatment include those in which a conductive material is laminated, surface treatments such as chemical polishing treatment, corona treatment, and oxygen plasma treatment. Alternatively, the current collector may be physically provided with any unevenness on the surface.

  As described above, the present invention has a feature that a coating layer formed by coating a metal oxide binder is formed on at least a part of the surface of the current collector, in direct contact with the current collector. Yes. Such a feature is effective when a current collector that is conventionally known to form a passive film, such as a current collector containing aluminum or a current collector containing nickel, is selected. That is, it is possible to prevent or suppress the formation of a passive film by forming a coating layer made of a metal oxide binder on the current collector surface, and between the electrode active material layer and the current collector. It is possible to move the electrons smoothly.

  As the current collector, for example, as shown in FIG. 2A, the current collector 1 used for the electrode plate 20 for a non-aqueous electrolyte secondary battery has a current collecting base such as a metal foil that itself has a current collecting function. Only material 3 can be used. Examples of the current collecting base 3 include the above-described aluminum foil, nickel foil, carbon sheet, and the like. In such a case, the electrode active material layer 2 is provided on at least a part of the surface 101 of the current collecting base material 3. In FIGS. 2A to 2D for explaining the current collector, the coating layer is not shown.

  Moreover, as an example of a different collector, as shown in FIG. 2B, a collector 1 itself having a collector function is used as a collector 1 ′ used for the electrode plate 20 ′ for a nonaqueous electrolyte secondary battery. A current collector 1 ′ in which an arbitrary conductive layer 4 having conductivity is provided on the upper surface of the material 3 can be used. The electroconductive layer 4 should just show electroconductivity of the grade which does not prevent the movement of the electron between the electrode active material layer 2 and the current collection base material 3. FIG. For example, the conductive layer 4 is a laminated layer made of copper or a copper alloy, a layer in which arbitrary conductive fine particles are deposited by plating or sputtering, or a layer in which one or more conductive thin films are provided. However, the present invention is not limited to these examples. In the current collector 1 ′, the surface of the conductive layer 4 becomes the surface 102 of the current collector 1 ′, and the electrode active material layer 2 is provided on at least a part of the surface 102. Note that FIG. 2B shows a mode in which the arbitrary conductive layer 4 is a single layer. However, the configuration of the current collector 1 ′ is not limited to this, and the conductive layer 4 may have a stacked configuration in which two or more arbitrary conductive layers are stacked.

  Further, as an example of a different current collector, as shown in FIG. 2C, a current collector 1 ″ used for the electrode plate 20 ″ for a nonaqueous electrolyte secondary battery itself has a current collecting function. A current collector in which an arbitrary intermittent layer 5 formed intermittently is provided on the upper surface of the electric substrate 3 can be used. The intermittent layer 5 may be a conductive layer similar to the conductive layer 4 described above, or may be a layer that does not exhibit conductivity. That is, in the electrode plate 20 ″ for the non-aqueous electrolyte secondary battery, the surface of the current collector 1 ″ is the surface 103 which is the surface of the intermittent layer 5, and the current collector base is not provided with the intermittent layer 5. It consists of surface 103 'which is the surface of material 3 itself. At this time, the electrode active material layer 2 can be formed so as to be in contact with both the surface 103 and the surface 103 ′. In the electrode plate 20 ″ for a nonaqueous electrolyte secondary battery, the intermittent layer 5 may or may not have conductivity. Even if the intermittent layer 5 is a non-conductive layer, the electrode active material layer 2 is in direct contact with the current collector base 3 on the surface 103 ′ of the current collector 1 ″. And the current collector 1 ″ ensure the movement of electrons. However, from the viewpoint of reducing the electrical resistance of the electrode plate 20 ″ for the nonaqueous electrolyte secondary battery itself, it is preferable that the intermittent layer 5 also exhibits conductivity.

  When the intermittent layer 5 exhibits conductivity, as shown in FIG. 2D, an electrode active material layer 2 ′ is selectively provided only on the intermittent layer 5 on the surface of the current collector 1 ″. You may comprise electrode board 20 '' 'for nonaqueous electrolyte secondary batteries. That is, the electrode active material layer 2 ′ may be selectively provided on at least a part of the surface 103 of the surface of the current collector 1 ″. Alternatively, although not shown, when the intermittent layer 5 does not exhibit conductivity, the electrode active material layer 2 ′ may be selectively provided on at least a part of the surface 103 ′ of the current collector 1 ″.

  The description of the current collector described above does not limit the current collector used in the present invention. As exemplified above, the current collector used in the present invention may be only a current collecting base material having a current collecting function, and in such an embodiment, the surface of the current collector on which the electrode active material layer is provided is defined. , Refers to the surface of the current collecting substrate. Alternatively, in the present invention, the current collector may have a current collecting base material having a current collecting function and an arbitrary laminated layer provided on the current collecting base material. In such an embodiment, the surface of the current collector on which the electrode active material layer is provided is within the range in which the movement of electrons is ensured in at least one region between the current collector base material and the electrode active material layer. It refers to the surface, or the surface of the current collecting base material on which the laminated layer is not provided, or the surface of the current collecting base material on which the surface of the laminated layer is not provided.

  As the current collector used in the present invention, one having a heat resistant temperature of 800 ° C. or lower, further 600 ° C. or lower, and particularly 400 ° C. or lower can be selected. The selection of the current collector is determined by the relationship with the temperature condition in the electrode active material layer forming step in the production method of the present invention exemplified later. In the manufacturing method of this invention, when an electrode active material layer formation process is a heating process, an electrode active material layer can be directly formed on a collector at the heating temperature of 400 degrees C or less, for example. Accordingly, the current collector can be selected to have a heat resistant temperature of 800 ° C. or lower, more preferably 600 ° C. or lower, and particularly 400 ° C. or lower, and an electrode active material layer is directly formed on the current collector. An electrode plate of the present invention can be provided. The electrode active material layer directly provided on the current collector having low heat resistance of 400 ° C. or lower is preferably a combination in which the active material particles and the binder are made of the same compound. It is not limited.

  The thickness of the current collector is not particularly limited as long as it is generally a thickness that can be used as a current collector of a nonaqueous electrolyte secondary battery electrode plate, but is preferably 10 to 200 μm, and preferably 15 to 50 μm. It is more preferable.

[Nonaqueous electrolyte secondary battery]
The nonaqueous electrolyte secondary battery of the present invention generally includes a negative electrode plate 21 in which an electrode active material layer 23 is provided on one surface side of a current collector 22 and the same as illustrated in FIG. A positive electrode plate 10 in which the electrode active material layer 2 is provided on one side of the current collector 1 to be combined, and a separator 24 such as a polyethylene porous film are provided therebetween. These are housed in the exteriors 25 and 26 and are sealed and manufactured in a state where the exteriors 25 and 26 are filled with the non-aqueous electrolyte 27 to form the non-aqueous electrolyte secondary battery 28. The The nonaqueous electrolyte secondary battery 28 uses the positive electrode plate 10 of the present invention, and the negative electrode plate 28 may be the electrode plate of the present invention or any electrode plate.

(Electrode plate)
The nonaqueous electrolyte secondary battery of the present invention is characterized in that, in particular, the electrode plate for a nonaqueous electrolyte secondary battery of the present invention described above is used as at least one of the positive electrode plate and the negative electrode plate. Therefore, the effect brought about by the electrode plate of the present invention is also reflected in the non-aqueous electrolyte secondary battery, so that an excellent non-aqueous electrolyte secondary battery can be provided. That is, the non-aqueous electrolyte secondary battery is excellent in output / input characteristics, and can have good cycle characteristics in the excellent input / output characteristics.

  In particular, conventionally, when the negative electrode plate is composed of a carbonaceous material, it has been common to add a large amount of conductive material to the positive electrode plate in order to increase the conductivity of the positive electrode plate accordingly. For this reason, the porosity of the positive electrode plate is lowered, and the permeability of the electrolytic solution is lowered, so that it is difficult to increase the output of the battery. However, since the electrode plate of the present invention is an electrode plate having excellent input / output characteristics, when it is used as a positive electrode plate, it is possible to reduce the amount of conductive material used as compared with the prior art.

  In addition, non-aqueous electrolyte secondary batteries do not insert and remove lithium ions, such as metallic lithium and its alloys, tin, silicon, and their alloys, rather than carbonaceous materials such as graphite, as the negative electrode active material used in the negative electrode plate. The aspect which comprises a negative electrode plate using the material which can be separated is also included. In such a battery, a nonaqueous electrolyte secondary battery can be produced by positively using the electrode plate of the present invention as a negative electrode.

  Moreover, a nonaqueous electrolyte secondary battery can also be comprised using the electrode plate of this invention for both a positive electrode plate and a negative electrode plate.

  In the nonaqueous electrolyte secondary battery of the present invention, when the electrode plate of the present invention is used in either the positive electrode plate or the negative electrode plate, the other electrode plate is used in the nonaqueous electrolyte secondary battery. The conventionally well-known electrode plate used can be used suitably.

  As a conventionally well-known positive electrode plate, in general, at least part of the current collector surface similar to the current collector used in the electrode plate of the present invention, positive electrode active material particles, conductive material, resin binder Although what was formed by apply | coating the positive electrode active material layer forming liquid to which etc. were added, drying and pressing as needed can be used, it is not limited to this. An electrode plate manufactured by another configuration or by another manufacturing method may be used. For example, the electrode plate previously proposed by the present applicant shown as the above-described prior art document may be used as the non-aqueous electrolyte solution of the present invention. You may use as a positive electrode plate of a secondary battery.

  On the other hand, as a conventionally known negative electrode plate, in general, a negative electrode active material particle, a conductive material, and a resin binder are formed on at least a part of the current collector surface similar to the current collector used in the electrode plate of the present invention. An electrode active material layer-forming solution to which a dressing material or the like is added can be applied, dried, and pressed as necessary. However, the present invention is not limited to this. A negative electrode plate manufactured by another configuration or by another manufacturing method may be used. For example, the negative electrode plate previously proposed by the present applicant shown as the above-described prior art document may be used as the non-aqueous electrolyte solution of the present invention. You may use as a negative electrode plate of a secondary battery.

(Nonaqueous electrolyte)
The non-aqueous electrolyte used in the present invention is not particularly limited as long as it is generally used as a non-aqueous electrolyte for a non-aqueous electrolyte secondary battery, but a lithium salt is dissolved in an organic solvent. A non-aqueous electrolyte is preferably used.

Examples of the lithium salt include inorganic lithium salts such as LiClO ₄ , LiBF ₄ , LiPF ₆ , LiAsF ₆ , LiCl, and LiBr; LiB (C ₆ H ₅ ) ₄ , LiN (SO ₂ CF ₃ ) ₂ , LiC ( Organic compounds such as SO ₂ CF ₃ ) ₃ , LiOSO ₂ CF ₃ , LiOSO ₂ C ₂ F ₅ , LiOSO ₂ C ₄ F ₉ , LiOSO ₂ C ₅ F ₁₁ , LiOSO ₂ C ₆ F ₁₃ , and LiOSO ₂ C ₇ F ₁₅ Typical examples include lithium salts.

  Examples of the organic solvent used for dissolving the lithium salt include cyclic esters such as propylene carbonate and butylene carbonate, chain esters such as dimethyl carbonate and diethyl carbonate, cyclic ethers such as tetrahydrofuran and alkyltetrahydrofuran, and 1,2- Examples include, but are not limited to, chain ethers such as dimethoxyethane and 1,2-diethoxyethane.

  As the structure of the non-aqueous electrolyte secondary battery of the present invention produced using the positive electrode plate, the negative electrode plate, the separator, and the non-aqueous electrolyte solution, a conventionally known structure can be appropriately selected and employed. For example, the structure which winds a positive electrode plate and a negative electrode plate in the shape of a spiral via the separator like a polyethylene porous film, and accommodates in a battery container is mentioned. As another aspect, a structure in which a positive electrode plate and a negative electrode plate cut out in a predetermined shape are stacked and fixed via a separator and accommodated in a battery container may be employed. It is not limited. In any structure, for example, after the positive electrode plate and the negative electrode plate are accommodated in the battery container, the lead wire attached to the positive electrode plate is connected to the positive electrode terminal provided in the outer container, while being attached to the negative electrode plate. A non-aqueous electrolyte secondary battery can be manufactured by connecting the lead wire to a negative electrode terminal provided in the outer container, and further filling the battery container with a non-aqueous electrification solution and then sealing it.

[Battery pack]
The nonaqueous electrolyte secondary battery using the electrode plate of the present invention as a positive electrode plate and / or a negative electrode plate can be used as a so-called nonaqueous electrolyte secondary battery used in a battery pack. That is, the battery pack of the present invention uses the electrode plate of the present invention as a positive electrode plate and / or a negative electrode plate, and includes a nonaqueous electrolyte secondary battery including a positive electrode terminal and a negative electrode terminal, and a protection circuit having an overdischarge protection function Are housed in a storage case. The battery pack of the present invention is equipped with a protection function for protecting the battery from, for example, overcharge, overdischarge, overcurrent, a short circuit of the battery peripheral circuit, a short circuit between the positive and negative electrodes, etc., in the nonaqueous electrolyte secondary battery itself. In addition, it may be a battery pack in which a protection circuit for preventing overcharge and overdischarge is housed and integrated in a storage case together with the non-aqueous electrolyte secondary battery. The battery pack of the present invention can be suitably used as a battery power supply device for a device that consumes a large amount of power relative to the scale of the device, such as a portable device such as a notebook computer, a camera, or a mobile phone.

  FIG. 4 shows a schematic exploded view of a battery pack 30 of the present invention using a lithium ion secondary battery 31 configured by using the electrode plate of the present invention as a positive electrode plate as one embodiment of the battery pack of the present invention. . The battery pack 30 includes a lithium ion secondary battery 31 housed in a resin container 36a, a resin container 36b, and an end case 37. At this time, a protection circuit for preventing overcharge and overdischarge between one end face of the lithium ion secondary battery 31 and a face including the positive electrode terminal 32 and the negative electrode terminal 33 and the end case 37. A substrate 34 is provided. The protection circuit board 34 includes an external connection connector 35. The external connection connector 35 is inserted into an external connection window 38a provided in the resin container 36a and an external connection window 38b provided in the end case 37. Connected to an external terminal. The protection circuit board 34 includes a charge / discharge safety circuit (not shown) for controlling charge / discharge, a wiring circuit for connecting the external connection terminal and the lithium ion secondary battery 31, and the like. In addition, the battery pack 30 can employ | adopt the structure of a conventionally well-known battery pack suitably except using the lithium ion secondary battery 31 in which the positive electrode plate of this invention was used. Although not shown, the battery pack 30 includes a positive electrode lead plate connected to the positive electrode terminal 32, a negative electrode lead plate connected to the negative electrode terminal 33, an insulator, and the like between the lithium ion secondary battery 31 and the end case 37. , May be provided as appropriate.

  In addition, the non-aqueous electrolyte secondary battery of the present invention using the electrode plate of the present invention has functions such as overcurrent blocking and battery temperature monitoring in addition to the above-described protection circuit, in addition to the usage mode for battery packs. And the protection circuit may be used by being integrated with the secondary battery itself. In such an embodiment, the battery pack can be used as a secondary battery having a protection function and a protection circuit without constituting a battery pack, and is highly versatile. In addition, some aspects mentioned above are only illustrations, and do not limit use of the electrode plate of this invention, or the nonaqueous electrolyte secondary battery of this invention at all.

[Method for producing electrode plate for non-aqueous electrolyte secondary battery]
Next, an example of a method for producing the electrode plate for a non-aqueous electrolyte secondary battery of the present invention (hereinafter sometimes simply referred to as “the production method of the present invention”) will be described. The production method of the present invention first comprises an electrode active material comprising a metal element-containing compound and electrode active material particles that serve as a precursor of a metal oxide binder, a solvent for the metal element-containing compound, or an optional additive. A layer forming solution is prepared. The production method of the present invention includes an application step of applying the electrode active material layer forming liquid to a desired region of the current collector surface to form a coating film, and an electrode active material layer forming the electrode active material layer from the coating film. And a material layer forming step. Here, the coating layer in the present invention can be formed between the current collector and the electrode active material layer in the step by performing the electrode active material layer forming step. In other words, in the manufacturing method of the present invention, the electrode active material layer forming step includes a coating layer forming step. Therefore, in the description of the manufacturing method of the present invention, which will be described later, the description of the coating layer forming step is omitted by describing the electrode active material layer forming step.

  In the electrode active material layer forming step, the solvent contained in the coating film is removed and a metal element-containing compound contained in the coating film is reacted to generate a metal oxide. It may be a step of forming an electrode active material layer containing the metal oxide and the electrode active material particles on the current collector by fixing the electrode active material particles on the current collector.

  Alternatively, in the electrode active material layer forming step in the present invention, an optional step is provided between the coating step and the electrode active material layer forming step, and after removing the solvent in the coating film, the electrode active material layer forming step May be implemented. That is, in the electrode active material layer forming step, the metal element-containing compound contained in the coating film from which the solvent has been removed is reacted to generate a metal oxide, and the electrode active material particles are formed by the metal oxide. It may be a step of forming an electrode active material layer containing the metal oxide and the electrode active material particles on the current collector by being fixed on the current collector.

  Unlike the slurry-like electrode active material layer forming liquid containing a conventional resin binder, the electrode active material layer forming liquid used in the production method of the present invention has a particle diameter of the electrode active material particles contained therein. Regardless, the viscosity of the degree that the applicability to the current collector is maintained well is shown. Therefore, electrode active material particles having a small particle diameter, which has been difficult to use due to a significant increase in viscosity in the conventional electrode active material layer forming liquid, can be used in the production method of the present invention. In addition, since the production method of the present invention has good applicability to the current collector of the electrode active material layer forming liquid, it can be applied to a desired thickness, and the electrode active material layer can be made thin. It was. On the other hand, it can also be formed to have a film thickness exceeding 200 μm so as to have a desired thickness.

  Examples of the electrode active material layer forming step include, but are not limited to, a heating step, a reduced pressure drying step, a reduced pressure heating step, or a combination thereof, and an electrode active material applied on a current collector. It may be a step of implementing means capable of forming a coating film formed by the layer forming liquid as an electrode active material layer. For example, the electrode active material layer forming step may include two or more means such as a means for removing the solvent contained in the coating film and then a means for reacting the metal element-containing compound. .

  When the electrode active material layer forming step is a heating step for performing a heating means, the production method of the present invention applies the electrode active material layer forming solution in which the metal element-containing compound is dissolved onto the current collector. Then, the metal element-containing compound can be heated and decomposed at a temperature equal to or higher than the thermal decomposition start temperature, and the metal element contained therein can be oxidized to produce a metal oxide exhibiting a lithium insertion / elimination reaction. In the electrode active material layer forming step, the metal oxide produced on the current collector is coated on the current collector so as to embrace the electrode active material particles contained in the solution. Can be fixed on the current collector. The active material particles contained in the electrode active material layer forming liquid, or further the conductive material particles, in addition to the fixing mode 1, as shown as the fixing mode 2, is a state in which the direct contact between the particles is satisfactorily maintained. The aspect fixed by is included. As described above, the factors that enable the fixing state as shown in the fixing modes 1 and 2 are that the metal element-containing compound is dissolved in the solvent and the electrode active material particles in the manufacturing method of the present invention. When forming the electrode active material layer by applying the electrode active material layer forming liquid mixed with the above to the current collector, the solvent is removed by means such as heating and the resulting metal oxide (binder) Is presumed to be generated around the contact portion where the particles are in direct contact with each other. As a result, the manufacturing method of the present invention can manufacture an electrode plate that has good conductivity and can keep electric resistance low. In addition, in the manufacturing method of this invention, the metal element containing compound contained in an electrode active material layer forming liquid is called a metal element containing compound including the state melt | dissolved in the solvent.

Electrode active material particles:
Since the electrode active material particles contained in the electrode active material layer forming liquid are the same as the electrode active material particles contained in the electrode plate of the present invention already described above, the description thereof is omitted here. The electrode active material layer forming liquid used in the production method of the present invention is a case where active material particles having a small average particle diameter are used as compared with a conventional electrode active material layer forming liquid using a resin binder. Even so, viscosity adjustment is easy. In particular, the electrode active material layer forming liquid used in the production method of the present invention is such that the coatability is reduced even when the electrode active material particles have a particle size of 10 μm or less, and even 1 μm or less. It has a desirable feature that no increase in viscosity is observed. Therefore, a desired size can be selected as the particle diameter of the electrode active material particles used.

Metal element-containing compounds:
The metal element-containing compound dissolved in the electrode active material layer forming liquid is contained in the electrode active material layer, and the electrode active material particles are fixed to each other as a binder, and the electrode active material particles are collected as a current collector. It is a metal oxide precursor which is fixed on the surface and exhibits a lithium ion insertion / release reaction. Therefore, the metal element-containing compound can be applied to the substrate in a state dissolved in a solution, and can generate the metal oxide described above when heated at a temperature equal to or higher than the thermal decomposition start temperature. Good. Whether or not the metal oxide produced from the metal element-containing compound to be used exhibits a lithium ion insertion / release reaction is determined by applying a solution containing the metal element-containing compound on the substrate in a preliminary experiment. Is heated to form a metal oxide, which can be confirmed by the cyclic voltammetry method described above.

  For example, specific examples of the metal element-containing compound include Li, Be, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu. Zn, Ga, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Cs, Ba, Hf, Ta, W, Re, Os, Ir, Pt , Au, Hg, Tl, Pb, Bi, Fr, Ra, and Ce, any one or two or more metal elements may be used. In particular, the metal element-containing compound preferably contains a transition element. Among these, a combination of a lithium element-containing compound and one or more metal element-containing compounds containing any metal element selected from transition elements such as cobalt, nickel, manganese, iron, and titanium can be given. Further, the metal element-containing compound used in the present invention may be an inorganic metal element-containing compound that does not contain carbon in the compound, or an organic metal constituted by containing carbon in the compound. It may be an element-containing compound. In the present invention and the present specification, the inorganic metal element-containing compound and the organic metal-containing compound may be collectively referred to simply as a metal element-containing compound.

  For example, as an example of the metal element-containing compound, one or more of a lithium element-containing compound and a metal element-containing compound containing any metal element selected from cobalt, nickel, manganese, iron or titanium The combination of is mentioned. Further, the metal element-containing compound used in the present invention may be an inorganic metal element-containing compound that does not contain carbon in the compound, or an organic metal constituted by containing carbon in the compound. It may be an element-containing compound. In the present invention and the present specification, the inorganic metal element-containing compound and the organic metal-containing compound may be collectively referred to simply as a metal element-containing compound.

  Examples of the metal element-containing compound include chlorides, nitrates, sulfates, perchlorates, acetates, phosphates and bromates of other metal elements such as lithium element and cobalt. Among them, in the present invention, chloride, nitrate, and acetate are preferably used because they are easily available as general-purpose products. In particular, nitrate is preferably used because it has good film forming properties for a wide variety of current collectors. It is preferable to use at least a lithium salt as the metal element-containing compound because it facilitates the production of an electrode plate for a lithium ion secondary battery. In particular, as the metal element-containing compound, by using one or more metal salts containing a metal selected from cobalt, nickel, manganese, iron and titanium, and a lithium salt, a lithium composite metal oxide Can be produced in the electrode active material layer.

For example, as a metal element-containing compound for generating LiCoO ₂ as a metal oxide on a current collector, a Li element-containing compound and a Co element-containing compound can be used in combination as main raw materials, and further necessary Depending on the case, other raw materials may be used in combination with the main raw material. Examples of the Li element-containing compound include lithium citrate tetrahydrate, lithium perchlorate trihydrate, lithium acetate dihydrate, lithium nitrate, and lithium phosphate. Examples of the contained compound include cobalt (II) chloride hexahydrate, cobalt (II) formate dihydrate, cobalt (III) acetylacetonate, cobalt (II) acetylacetonate dihydrate, cobalt acetate ( II) Tetrahydrate, cobalt (II) oxalate dihydrate, cobalt (II) nitrate hexahydrate, cobalt (II) ammonium chloride hexahydrate, sodium cobalt (III) nitrite, and cobalt sulfate (II) The heptahydrate etc. are mentioned. The combination ratio (Li: Co = X: 1) of the Li element-containing compound and the Co element-containing compound used as the main raw material is not particularly limited, but is preferably 1 ≦ X <2, and preferably 1 ≦ X ≦ 1. 2 is more preferable.

For example, as a metal element-containing compound for producing LiNi _0.5 Mn _1.5 O ₄ as a metal oxide on a current collector, a Li element-containing compound and a Mn element-containing compound are used as a main raw material, and Ni Element-containing compounds can be used in combination, and other raw materials can be used in combination with the main raw material as necessary. Examples of the Li element-containing compound are the same as in the case of producing LiCoO ₂ described above, and examples of the Mn element-containing compound include manganese acetate (III) dihydrate, manganese nitrate (II) hexahydrate. Products, manganese (II) sulfate pentahydrate, manganese (II) oxalate dihydrate, manganese (III) acetylacetonate, and the like. Also, for example, nickel (II) chloride hexahydrate, nickel acetate (II) tetrahydrate, nickel (II) perchlorate hexahydrate, nickel (II) bromide trihydrate, nickel nitrate ( II) Hexahydrate, nickel (II) acetylacetonate dihydrate, nickel (II) hypophosphite hexahydrate, nickel sulfate (II) hexahydrate and the like.

  In the electrode active material layer forming liquid described above, the ratio of the total amount of one or more metal element-containing compounds added in the solvent is 0.01 to 5 mol / L, particularly 0.1 to 5 mol / L. 2 mol / L is preferred. By the said density | concentration being 0.01 mol / L or more, a collector and the electrode active material layer produced | generated on this collector surface adhere | attach favorably, and fixation of an electrode active material particle is achieved. Further, when the concentration is 5 mol / L or less, the electrode active material layer forming liquid can maintain a good viscosity enough to be applied to the current collector surface, and a uniform coating film is formed. Is done.

Conductive material:
Since the conductive material contained in the electrode active material layer forming liquid used in the production method of the present invention is the same as the conductive material described in the description of the electrode plate of the present invention, the description is omitted here.

  When the conductive material is added to the electrode active material layer forming liquid, the active material particles generated on the surface of the current collector, or the electrode active material particles and the total amount of metal oxides to be formed are 100 parts by weight. Thus, it is desirable that the addition amount of the conductive material is 5 to 20 parts by weight. In addition, the above is not the meaning which excludes adding a conductive material exceeding 20 weight.

(Other additives)
In addition to the electrode active material particles, the metal element-containing compound, and the conductive material described above, other additives may be added to the electrode active material layer forming liquid without departing from the spirit of the present invention. . The said other additive can use the thing similar to the content described in description of the electrode active material layer in the electrode plate of this invention.

(solvent)
The solvent for the metal element-containing compound and used for preparing the electrode active material layer forming liquid is not particularly limited. For example, water or methanol, ethanol, isopropyl alcohol, propanol, butanol, etc. Lower alcohol having a total carbon number of 5 or less, diketones such as acetylacetone, diacetyl, benzoylacetone, ketoesters such as ethyl acetoacetate, ethyl pyruvate, ethyl benzoylacetate, ethyl benzoylformate, toluene, and mixed solvents thereof Can be mentioned. In this specification, the liquid component used in the preparation of the electrode active material layer forming liquid is referred to as a solvent for the sake of convenience, but this means that all the solid components added to the electrode active material layer forming liquid are dissolved in the solvent. This means that at least the metal element-containing compound is dissolved.

  The electrode active material layer forming liquid contains electrode active material particles, metal oxides, conductive materials, and other additives as required in the electrode active material layer scheduled to be formed on the current collector. These amounts are determined in consideration of inclusion. At that time, the ratio of the components (that is, the electrode active material particles, the metal element-containing compound and the conductive material, or further optional additives) added to the liquid used as the solvent for the metal element-containing compound is determined in the application process. Appropriate adjustment is made in consideration of the coating property on the body and the removal of the solvent in the electrode active material layer forming step. Generally, when the electrode active material layer forming liquid is 100% by weight, the total amount of solutes contained is adjusted to be 30 to 70% by weight.

  Next, the electrode active material layer forming liquid prepared as described above is applied onto a current collector to form a coating film. The current collector used in the production method of the present invention is the same as the current collector used in the electrode plate for a non-aqueous electrolyte secondary battery, and the description thereof is omitted here.

  In the coating step in the production method of the present invention, a known coating method can be appropriately selected and implemented as a solution coating method. For example, the electrode active material layer forming liquid can be applied to any region of the current collector surface to form a coating film by printing, spin coating, dip coating, bar coating, spray coating, or the like. In this coating step, the electrode active material layer forming liquid can be applied to any surface of the current collector, and the electrode active material layer can be applied to only one side or both sides of the current collector. In addition, the electrode active material layer may be applied to almost the entire surface of the current collector on one or both sides of the current collector, or the electrode active material layer forming solution may be partially applied. May be. In addition, when the current collector surface is porous, has a large number of irregularities, or has a three-dimensional structure, the coating method is other than the above method, for example, a manual coating method. Is also possible. Note that the current collector used in the present invention is preferable because corona treatment, oxygen plasma treatment, and the like can be performed in advance as necessary to further improve the film forming property of the electrode active material layer.

  The amount of the electrode active material layer forming liquid applied to the current collector can be arbitrarily determined according to the application of the electrode plate to be produced. Since the electrode active material layer in the present invention can be formed very thin as described above, when it is desired to reduce the thickness, the final electrode active material layer has a thickness of 300 nm to 150 μm, particularly 500 nm. You may apply | coat thinly so that it may be set to about ~ 100 micrometers. As described above, a coating film for forming an electrode active material layer containing a metal element-containing compound that is a precursor of a metal oxide that is a binder is formed by applying an electrode layer forming solution to a substrate. The

  A pressing step may be further performed between the coating step and the electrode active material layer forming step or after the electrode active material layer forming step. The said press process can be implemented by drying the said coating film for electrode active material layer formation formed on the electrical power collector as needed, removing a solvent, and pressing it after that. Therefore, when performing an electrode active material layer formation process after a press process, a part or all of the solvent in a coating film may be removed beforehand before this electrode active material layer formation process. The pressing method can be carried out in the same manner as the press performed by applying a slurry-like electrode active material layer forming liquid containing a conventional resin binder on the current collector and drying it. However, it is not limited to this. Thus, the manufacturing method of the present invention can adjust the porosity of the electrode active material layer in the finally manufactured electrode plate and increase the energy density per volume by performing the pressing step. .

  Next, the electrode active material layer forming step for forming the electrode active material layer from the coating film formed in the coating step will be described by taking a heating step for heating the coating film as an example. This heating step is carried out for the purpose of thermally decomposing and oxidizing the metal element-containing compound present in the coating film, and removing the solvent contained in the coating film (but before the heating step) When carrying out the pressing step, the solvent is substantially removed beforehand by drying before pressing). The heating method is not particularly limited as long as it is a heating method or a heating apparatus capable of heating the coating film at a heating temperature described later, and can be appropriately selected and carried out. Specific examples include a method of using a hot plate, an oven, a heating furnace, an infrared heater, a halogen heater, a hot air blower, or the like, or a combination of two or more. In addition, when the electrode active material layer forming liquid is applied to both sides of the current collector, the electrode active material layer can be formed on both sides of the current collector by performing a heating step on one side or on both sides simultaneously. . When the current collector to be used is planar, it is preferable to use a hot plate or the like for the heating step. In addition, when heating using a hot plate, it is preferable to install and heat the coating film surface side in a direction not in contact with the hot plate surface. The heating temperature varies depending on the type of the metal element-containing compound used. However, the metal element-containing compound is favorably thermally decomposed by heating the coating film in a temperature range of 150 ° C. to 800 ° C. An oxide is produced. The generated metal oxide is understood to be a crystalline metal oxide because it exhibits a lithium ion insertion / release reaction.

  Here, generally, when producing a crystalline metal oxide, it is necessary to heat the coating film at a temperature of at least about 800 ° C. or higher. On the other hand, in the production method of the present invention, the crystalline metal oxide is generated even at a low heating temperature of 700 ° C. or lower, further 600 ° C. or lower, particularly 400 ° C. or lower. This is one of the characteristic points of the manufacturing method. Note that the crystalline metal oxide includes a microcrystalline state. According to the study by the present inventors, the coating step and the heating step in the production method of the present invention were carried out using a test solution prepared in the same manner as the electrode active material layer forming liquid except that the electrode active material particles were not included. It was also found that a crystalline metal oxide (hereinafter referred to as metal oxide A) exhibiting a lithium ion insertion / elimination reaction was produced even when the above was carried out. In addition to this, when an electrode active material layer is formed on a current collector using an electrode active material layer forming liquid containing electrode active material particles, the binding contained in the electrode active material layer It was found that the metal oxide (hereinafter referred to as “metal oxide B” in this paragraph) as a material exhibits a lithium ion insertion / release reaction and a discharge capacity (μAh) superior to that of the metal oxide A. It was. The discharge capacity (μAh) shown in the metal oxide B tends to be shown to a value very close to the theoretical value of the metal oxide B. The point that a metal oxide having such a high discharge capacity (that is, excellent crystallinity) can be produced at a heating temperature as low as 700 ° C. or less, further 600 ° C. or less, particularly 400 ° C. or less. This is a notable advantage of the production method of the present invention. The relationship between the heating temperature described above and the development of crystallinity of the metal oxide produced is estimated as follows. That is, since electrode active material particles are contained in the electrode active material layer forming liquid, the generated metal oxide follows the crystallinity of the electrode active material particles and is 700 ° C. or lower. It is presumed that lithium insertion / extraction reaction is possible even at a heating temperature of 600 ° C. or lower, particularly 400 ° C. or lower, resulting in a metal oxide having high crystallinity. In particular, when the chemical composition of the electrode active material particles to be mixed with the metal oxide to be generated is the same, this follow-up action is assumed to be remarkable.

  The heating step is performed at a heating temperature of 400 ° C. or less, so that the selection range of the current collector is widened, and the electrode active material layer can be directly formed on various current collectors. Since various effects, such as the point that cost merit improves by having low temperature, are preferable.

  In addition, the heating temperature is preliminarily applied to a suitable substrate with a solution in which a metal element-containing compound to be used is dissolved and heated, and a film laminated on the substrate is scraped and used as a sample. By performing composition analysis and measuring the content ratio of the metal element and oxygen, it can be determined whether or not a metal oxide is formed. And when the metal oxide was produced | generated, it was confirmed that the used metal element containing compound was heated at the temperature more than thermal decomposition start temperature on a board | substrate. That is, in the present invention, the “thermal decomposition start temperature of the metal element-containing compound” can be understood as a temperature at which the metal element-containing compound is decomposed by heating and the oxidation of the metal element starts.

  In the heating step, when determining the heating temperature, it is desirable to further consider the heat resistance of the current collector, electrode active material particles, conductive material, and the like used. For example, since the heat resistance of an aluminum foil generally used as a current collector for a positive electrode plate is around 660 ° C., the current collector may be damaged if the heating temperature exceeds 660 ° C. Therefore, the current collector, active material particles, etc. to be used are determined first, taking into account their heat resistance, taking into account their heat resistant temperature and thermal decomposition starting temperature, and selecting a metal element-containing compound. Also good. Further, for example, when using a current collector containing copper, a preferable heating atmosphere may be selected so that the current collector is not oxidized during the manufacturing process, or the current collector oxidized during the heating process may be used in a subsequent process. You may reduce | restore in. In the production method of the present invention, “heating temperature” means the highest temperature in the heating step. The heating mode in the heating step may be arbitrarily determined, for example, by gradually increasing the temperature, heating at a constant temperature, or heating at a stepped temperature.

  The electrode plate of the present invention may further contain a resin component in the electrode active material layer produced as described above. For example, the electrode active material layer may further contain a resin component by, for example, applying a resin mixed solution to the surface of the electrode active material layer or immersing an electrode plate in a resin mixed solution tank, A method of removing the solvent of the resin mixed solution impregnated in the electrode active material layer by infiltrating the gaps in the electrode active material layer and then drying, and leaving only the resin component inside the electrode active material layer. Can be mentioned. Thus, if it is the electrode plate of this invention which contains a resin component in an electrode active material layer, the bending tolerance of an electrode plate will improve by presence of a resin component, and it can improve a process characteristic. In particular, when the resin component is a conventionally used resin binder, the film adhesion of the electrode active material layer to the current collector can be further improved.

  As the resin material contained in the resin mixed solution, for example, a conventional resin binder such as PVDF, styrene butadiene rubber (SBR), carboxymethoxy cellulose (CMC), or those listed in the viscosity modifier are selected. However, the present invention is not limited to this. The resin material is appropriately selected to have a size that can penetrate into the voids in the electrode active material layer. Examples of the solvent for the resin mixture include lower alcohols having a total carbon number of 5 or less such as methanol, ethanol, isopropyl alcohol, propanol, and butanol, diketones such as acetylacetone, diacetyl, and benzoylacetone, ethyl acetoacetate, and pyrubin. Ketoesters such as ethyl acetate, ethyl benzoylacetate and ethyl benzoylformate, pyrrolidones such as N-methylpyrrolidone (NMP), toluene, a mixed solvent thereof, water, and the like can be used. Can be mixed to prepare a resin mixed solution.

  When the resin component is contained in the electrode active material layer, the content may be appropriately determined within a range not departing from the gist of the present invention.

Example 1
Li (CH ₃ COO) · 2H ₂ O: 10 g and Mn (CH ₃ COO) ₂ · 4H ₂ O: 55 g were used as the metal element-containing compound, and these were added to water: 50 g and mixed, and further methylcellulose (60SH4000) (Shin-Etsu Chemical Co., Ltd.): 5 g dissolved, lithium manganate particles: 40 g as positive electrode active material particles, acetylene black HS-100: 5 g, VGCF: 0.5 g as a conductive material, and Excel Auto Homogenizer (Nippon Seiki Co., Ltd.) A positive electrode active material layer forming solution was obtained by stirring for 10 minutes at a rotational speed of 7000 rpm in a manufacturing plant).

Next, a 15 μm-thick aluminum foil as a positive electrode current collector is placed, and the positive electrode active material layer forming solution prepared above is applied to one side of the positive electrode current collector with an applicator to form a coating film did. The coating amount is shown in Table 1 as the weight per unit area of the finally obtained electrode active material layer. Next, the positive electrode current collector having the above-mentioned coating film was gradually heated from room temperature to 450 ° C. over 30 minutes using an electric furnace (Muffle Furnace Denken, P90), and the positive electrode current collector was placed on the positive electrode current collector. An active material layer was formed to obtain a positive electrode plate of the present invention. And the said positive electrode plate was cut | judged to predetermined magnitude | size (15 mmphi), and this was set as Example 1. FIG. In addition, when the thickness of the said positive electrode active material layer was measured 10 points | pieces in arbitrary places using the micrometer, and the average value was computed, it was 35 micrometers. In addition, the content (mg / 1.77 cm ² ) of active material particles per unit area in Example 1 was calculated from the amount of active material particles used and the like and shown in Table 2. In the examples and comparative examples, the heating atmosphere in the heating step was an atmospheric atmosphere unless otherwise specified.

(Example 2)
As the metal element-containing _{compound, Li (CH 3 COO) ·} 2H 2 O and 10g and _{Co (NO 3) 2 · 6H} 2 O and with 25 g, was mixed with these to water 50 g, further methylcellulose (60SH4000 Etsu Chemical 5 g of lithium manganate particles as positive electrode active material particles, 5 g of acetylene black HS-100 as a conductive material, and 0.5 g of VGCF are added, and an Excel auto homogenizer (Nippon Seiki Seisakusho Co., Ltd.) is dissolved. ) To obtain a positive electrode active material layer forming solution by stirring at 7000 rpm for 10 minutes.

Next, a 15 μm-thick aluminum foil as a positive electrode current collector is placed, and the positive electrode active material layer forming solution prepared above is applied to one side of the positive electrode current collector with an applicator to form a coating film did. The coating amount is shown in Table 1. Next, the positive electrode current collector having the above-mentioned coating film was gradually heated from room temperature to 450 ° C. over 30 minutes using an electric furnace (Muffle Furnace Denken, P90), and the positive electrode current collector was placed on the positive electrode current collector. An active material layer was formed to obtain a positive electrode plate of the present invention. And the said positive electrode plate was cut | judged to predetermined magnitude | size (15 mmphi), and this was made into Example 2. FIG. In addition, it was 37 micrometers when the thickness of the said positive electrode active material layer was measured 10 points | pieces in arbitrary places using the micrometer, and the average value was computed. In addition, the content (mg / 1.77 cm ² ) of active material particles per unit area in Example 2 was calculated from the amount of active material particles used and the like and shown in Table 2.

(Example 3)
First, as a metal element-containing compound, Li (CH ₃ COO) · 2H ₂ O [molecular weight: 102.02]: 4 g and titanium dioctyloxybis (octylene glycolate) [molecular weight: 548]: 25 g were used. Is added to 30 g of water and mixed, and further 5 g of methylcellulose (60SH4000 manufactured by Shin-Etsu Chemical Co., Ltd.) is dissolved. Further, 40 g of lithium titanate particles are used as negative electrode active material particles, 5 g of acetylene black HS-100 is used as a conductive material, and VGCF is added. In addition, 0.5 g was added, and the negative electrode active material layer forming solution was obtained by stirring for 10 minutes with the rotation speed of 7000 rpm with an Excel auto homogenizer (Nippon Seiki Seisakusho).

Next, a 15 μm thick aluminum foil as a negative electrode current collector is placed, and the negative electrode active material layer forming solution prepared above is applied to one surface side of the negative electrode current collector with an applicator to form a coating film did. The coating amount is shown in Table 1. Next, the negative electrode current collector having the above-mentioned coating film was gradually heated from room temperature to 450 ° C. over 30 minutes using an electric furnace (Muffle furnace manufactured by Denken Co., Ltd., P90). An active material layer was formed to obtain the negative electrode plate of the present invention. And the said negative electrode plate was cut | judged to predetermined magnitude | size (15 mmphi), and this was made into Example 3. FIG. In addition, when the thickness of the said negative electrode active material layer was measured 10 points | pieces using the micrometer, and the average value was computed, it was 33 micrometers. In addition, the content (mg / 1.77 cm ² ) of active material particles per unit area in Example 1 was calculated from the amount of active material particles used and the like and shown in Table 2.

(Comparative Example 1)
A positive electrode active material layer forming solution for forming a positive electrode active material layer in a positive electrode plate for a non-aqueous electrolyte secondary battery was prepared as follows. First, lithium manganate powder having an average particle diameter of 5 μm as positive electrode active material particles: 80 parts by weight (40 g), acetylene black (Denka Black, manufactured by Denki Kagaku Kogyo Co., Ltd.) as a conductive material: 10 parts by weight (5 g), carbon fiber (Showa Denko Co., Ltd., VGCF): 1.5 g, and PVDF (Kureha, KF # 1100): 10 parts by weight (5 g) as a resin binder, NMP (Mitsubishi Chemical Corporation) as an organic solvent 36 g) was added and dispersed, and dispersed and / or kneaded so that the solid content concentration became 55% by weight to obtain a slurry-like positive electrode active material layer forming solution.
The coating amount of the positive electrode active material layer solution after drying is adjusted to 64 g / m ² on the 15 μm-thick aluminum foil as the positive electrode current collector. It apply | coated and dried in 120 degreeC air atmosphere using oven, and formed the positive electrode active material layer.
Furthermore, after pressing using a roll press machine so that the coating density of the formed positive electrode active material layer is 2.0 g / cm ³ (thickness of the positive electrode active material layer: 31 μm), a predetermined size is obtained. Cut to (15φ) and vacuum dried at 140 ° C. for 5 minutes to produce a positive electrode plate.

(Comparative Example 2)
A positive electrode plate was produced in the same manner as in Example 1 except that no conductive material was used, and this was used as Comparative Example 2.

(Comparative Example 3)
First, as a metal element-containing compound, Al (NO ₃ ) ₃ · 9H ₂ O: 25 g was added to 50 g of water and mixed, and methylcellulose (60SH4000, manufactured by Shin-Etsu Chemical Co., Ltd.): 5 g was further dissolved, and the positive electrode active Lithium manganate particles: 40 g as material particles, acetylene black HS-100: 5 g, VGCF: 0.5 g as conductive materials, and stirring with an Excel auto homogenizer (Nihon Seiki Seisakusho Co., Ltd.) at a rotation speed of 7000 rpm for 10 minutes. Thus, a positive electrode active material layer forming solution was obtained.

Next, a 15 μm-thick aluminum foil as a positive electrode current collector is placed, and the positive electrode active material layer forming solution prepared above is applied to one side of the positive electrode current collector with an applicator to form a coating film did. The coating amount is shown in Table 1. Next, the positive electrode current collector having the above-mentioned coating film was gradually heated from room temperature to 450 ° C. over 30 minutes using an electric furnace (Muffle Furnace Denken, P90), and the positive electrode current collector was placed on the positive electrode current collector. An active material layer was formed to obtain a positive electrode plate. And the said positive electrode plate was cut | judged to predetermined magnitude | size (15 mmphi), and this was made into the comparative example 3. In addition, when the thickness of the said positive electrode active material layer was measured 10 points | pieces in arbitrary places using the micrometer, and the average value was computed, it was 33 micrometers. In addition, from the amount of active material particles used and the like, the content (mg / 1.77 cm ² ) of active material particles per unit area in Example 1 was calculated and shown in Table 2.

  A tripolar coin cell was manufactured by using Examples 1 to 3 and Comparative Examples 1 to 3 described above as working electrodes, respectively, and a charge / discharge test was performed. As described below, input / output characteristics and cycle characteristics were evaluated. In addition, as described below, Examples 1 to 3 were cut substantially perpendicular to the current collector surface, and using a transmission electron microscope, the surface of the current collector was coated with a metal oxide to form a coating layer. Confirmed whether or not.

(Battery characteristics evaluation)
<Production of tripolar coin cell>
Lithium hexafluorophosphate (LiPF ₆ ) is added as a solute to a mixed solvent of ethylene carbonate (EC) / dimethyl carbonate (DMC) (volume ratio = 1: 1), and the concentration of LiPF _{6 as} the solute is 1 mol. The non-aqueous electrolyte was prepared by adjusting the concentration to be / L. The examples and comparative examples produced as described above as the positive electrode plate were used as the working electrode, the metal lithium plate was used as the counter electrode plate and the reference electrode plate, and the non-aqueous electrolyte produced as described above was used as the electrolyte. A type coin cell was assembled and used as a test cell for the following charge / discharge test.

<Charge / discharge test>
In the test cell which is a tripolar coin cell prepared as described above, in order to perform the discharge test of the working electrode plate, the example test cell 1 using Example 1 was first fully charged as shown in the following charging test.
(Charge test)
Example Test cell 1 was charged at a constant current (equivalent to 1C, 1010 μA) under a 25 ° C. environment until the voltage reached 5.0 V, and the voltage reached 5.0 V (full charge voltage). After that, the current (discharge rate: 1C) is reduced until the voltage becomes 5% or less so that the voltage does not exceed 5.0V, the battery is charged at a constant voltage, fully charged, and then suspended for 10 minutes. It was. Here, the “1C” means a current value (current value reaching the discharge end voltage) at which constant current discharge is performed using the tripolar coin cell and discharge is completed in one hour. The constant current is a current value set so that the working electrode plate in the example test cell 1 can discharge the capacity that can be discharged in 1 hour in this charge / discharge test in 1 hour.

(Discharge test)
Thereafter, the fully charged example test cell 1 was subjected to a constant current (1010 μA) (discharge) under a 25 ° C. environment until the voltage was changed from 5.0 V (full charge voltage) to 3.0 V (discharge end voltage). A constant current discharge at a rate of 1 C), the cell voltage (V) on the vertical axis, the discharge time (h) on the horizontal axis, a discharge curve is created, and the discharge capacity (mAh) of the electrode plate for positive electrode is obtained. Conversion was made to the discharge capacity (mAh / g) per weight of the positive electrode plate.

  Following the charge / discharge test described above, a charge / discharge test was performed on the test cells using Examples 2 and 3 and Comparative Examples 1 to 3, respectively. The constant current in each test cell is shown in Table 2.

Cycle characterization:
The 1C300 cycle characteristic test was repeated 1000 times with one charge and discharge as one cycle at the discharge rate 1C in the charge / discharge test described above. Then, the cycle characteristic evaluation is obtained by dividing the discharge capacity after 300 cycles (mAhr / g) by the discharge capacity after 1 cycle (mAhr / g) and multiplying by 100 to obtain the 1C300 cycle discharge capacity maintenance ratio. Evaluated. The results are shown in Table 2.

DC resistance evaluation:
The test cell created using each of Examples 1 to 3 and Comparative Examples 1 to 3 was provided, and the DC resistance value of the electrode plate was calculated as follows. When a discharge test is performed under the condition of a discharge rate of 1C, a voltage value (V1) (mV) 10 seconds after the start of discharge is measured. Furthermore, also when the discharge test is performed under the condition of the discharge rate 5C, the voltage value (V5) (mV) 10 seconds after the start of discharge is measured. Based on these measured values (V1, V5) and the constant current values (I1, I5) (mA) corresponding to the discharge rates 1C, 5C, the direct current resistance value (Ω) is expressed by the following equation (1). Calculated. The results are shown in Table 2.

Transmission electron microscope observation:
An electrode plate was prepared in the same manner as in Examples 1 to 3 except that 5 g of KBM503 (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a silane coupling agent to the electrode active material layer forming liquid used in Examples 1 to 3. And it was set as Reference Examples 1-3. In Reference Examples 1 to 3, a metal oxide binder containing a silane coupling agent was produced. Next, cut pieces were prepared when Reference Examples 1 to 3 were each cut in a substantially vertical direction with respect to the current collector surface. About the cross section of the said reference examples 1-3, a part of interface of a collector and an electrode active material layer was observed with the transmission electron microscope. Next, in order to observe the metal oxide binder produced in the electrode active material layer in Reference Examples 1 to 3, silicon was mapped by the TEM-EDX (Energy Dispersive X-ray Spectroscopy) method and the above The interface was observed. As a result, in any of Reference Examples 1 to 3, it was confirmed that a metal oxide containing silicon was coated on the current collector and a coating layer was formed. A transmission micrograph of Reference Example 1 is shown as FIG. 5A. Moreover, the transmission electron micrograph at the time of silicon being mapped in TEM-EDX of the reference example 1 is shown as FIG. 5B.

  Referring to FIG. 5A, lithium manganate particles 41 are present on the surface of the aluminum current collector 40, and the metal oxide binder 42 and the conductive material particles 43, which are lithium manganate, surround the periphery of these particles. Is understood to exist. 5B, the coating layer 44 was clearly shown, and it was observed that the coating layer 44 formed from the metal oxide that is lithium manganate was present on the surface of the aluminum current collector 40. Although not shown, in Reference Examples 2 and 3 as well, it was confirmed that a coating layer made of a metal oxide was formed on the surface of the current collector. Although the thickness of the coating layer was partially different, it was about several nm to 10 nm. Moreover, the coating layer covered substantially the entire surface of the current collector within the scope of this observation.

DESCRIPTION OF SYMBOLS 1, 1 ', 1''Current collector 2, 2' Electrode active material layer 3 Current collecting base material 4 Conductive layer 5 Intermittent layer 6 Core body 7 Enclosure 8 Void 10 Positive electrode plate 20, 20 ', 20'' , 20 '''Nonaqueous electrolyte secondary battery electrode plate 21 Negative electrode plate 22 Current collector 23 Electrode active material layer 24 Separator 25, 26 Exterior 27 Nonaqueous electrolyte 28 Nonaqueous electrolyte secondary battery 30 Battery pack 31 Lithium ion secondary battery 32 Positive electrode terminal 33 Negative electrode terminal 34 Protective circuit board 35 External connector 36a, 36b Resin container 37 End case 38a, 38b External connection window 101, 102, 103, 103 ′ Surface

Claims (4)

A non-aqueous electrolyte secondary battery electrode plate comprising a current collector and an electrode active material layer formed on the current collector,
Between the current collector and the electrode active material layer, a coating layer in which a metal oxide capable of alkali insertion / release reaction covers the current collector is formed,
The electrode active material layer contains a binder, electrode active material particles, and a conductive material, which are the same metal oxide as the metal oxide forming the coating layer,
The electrode plate for a non-aqueous electrolyte secondary battery, wherein the electrode active material particles and the conductive material are fixed to the current collector and / or the coating layer by the binder.   A triple structure is formed in which the current collector, the coating layer covering the current collector, and the conductive material fixed to the coating layer are connected to each other. The electrode plate for nonaqueous electrolyte secondary batteries according to claim 1. In a nonaqueous electrolyte secondary battery comprising at least a positive electrode plate, a negative electrode plate, a separator provided between the positive electrode plate and the negative electrode plate, and an electrolyte containing a nonaqueous solvent,
The nonaqueous electrolyte secondary battery according to claim 1, wherein at least one of the positive electrode plate and the negative electrode plate is the electrode plate for a nonaqueous electrolyte secondary battery according to claim 1. A storage case; a non-aqueous electrolyte secondary battery including a positive electrode terminal and a negative electrode terminal; and a protection circuit having an overcharge and over-discharge protection function, wherein the storage case includes the non-aqueous electrolyte secondary battery and the In a battery pack configured to contain a protection circuit,
The non-aqueous electrolyte secondary battery includes at least a positive electrode plate containing an electrode active material, a negative electrode plate, a separator provided between the positive electrode plate and the negative electrode plate, and an electrolyte solution containing a non-aqueous solvent. Non-aqueous electrolyte secondary battery,
3. The battery pack, wherein at least one of the positive electrode plate and the negative electrode plate is the electrode plate for a non-aqueous electrolyte secondary battery according to claim 1.