WO2013172007A1

WO2013172007A1 - Current collector for non-aqueous electrolyte secondary cell positive electrode, method for manufacturing same, positive electrode for non-aqueous electrolyte secondary cell, and non-aqueous electrolyte secondary cell

Info

Publication number: WO2013172007A1
Application number: PCT/JP2013/003025
Authority: WO
Inventors: 達哉江口; 剛志牧; 弘樹大島; 友哉佐藤; 仁愛清
Original assignee: 株式会社豊田自動織機
Priority date: 2012-05-16
Filing date: 2013-05-13
Publication date: 2013-11-21

Abstract

Provided is a current collector for a non-aqueous electrolyte secondary cell positive electrode, the current collector having: a main current collector body; and a coat layer formed on the surface of the main current collector body, the coat layer comprising an electroconductive oxide having a specific resistance no greater than 9.9 × 10^-3 Ωcm or an electroconductive nitride having a specific resistance no greater than 9.9 × 10^-3 Ωcm. Also provided is a non-aqueous electrolyte secondary cell having: a positive electrode for a non-aqueous electrolyte secondary cell having a current collector for a non-aqueous electrolyte secondary cell positive electrode having a main current collector body and a coat layer formed on the surface of the main current collector body, the coat layer comprising an electroconductive oxide; and a non-aqueous electrolyte containing LiBF₄ (lithium tetrafluoroborate) as an electrolytic salt. Also provided is a positive electrode for a non-aqueous electrolyte secondary cell, having a main current collector body, a first layer formed on the surface of the main current collector body, a second layer formed on the surface of the first layer, and an active material layer formed on the surface of the second layer, the specific resistance of the first layer being lower than the specific resistance of the second layer and higher than the specific resistance of the main current collector body. Also provided is a current collector for a non-aqueous electrolyte secondary cell positive electrode having a main current collector body and a coating layer containing a metal oxide or a metal nitride, wherein a high-resistance metal having a higher specific resistance than the main current collector body is provided between the main current collector body and the coating layer.

Description

Non-aqueous electrolyte secondary battery positive electrode current collector, manufacturing method thereof, non-aqueous electrolyte secondary battery positive electrode and non-aqueous electrolyte secondary battery

The present invention relates to a current collector for a positive electrode of a nonaqueous electrolyte secondary battery, a manufacturing method thereof, a positive electrode for a nonaqueous electrolyte secondary battery, and a nonaqueous electrolyte secondary battery.

For the positive electrode current collector of a non-aqueous electrolyte secondary battery, it is common to use a metal such as Al that spontaneously forms a stable passive film on the surface in order to withstand corrosion caused by electrolytic salts. is there. For example, when Al is used for the current collector body, a passive film such as Al ₂ O ₃ or AlF ₃ is formed on the surface thereof. When a passive film is formed on the surface of the current collector body, contact between the electrolytic salt or the like and the current collector body is reduced, so that the current collector body is hardly corroded by the electrolytic salt or the like. For this reason, the current collector main body on which the passive film is formed can maintain a good current collecting function. However, since the passive film on the surface has high resistance, when the passive film is formed on the current collector body, the discharge capacity of the battery is reduced as compared with the case where there is no passive film.

In recent years, demands for higher potentials of non-aqueous electrolyte secondary batteries have increased, and various potential studies have been conducted. With respect to the current collector, for example, it has been studied to form a protective film on the current collector body in order to improve cycle characteristics at a high potential.

For example, Patent Document 1 discloses a current collector body including an oxidation-resistant protective film containing, as a constituent, a compound selected from Al iodide, TiN, Ti ₂ O ₃ , SnO ₂ , In ₂ O ₃ , RuO _{2, and the} like. It is described that it forms on the surface. These compounds contained in the protective film have conductivity and are electrochemically stable even under high voltage. By forming a protective film containing the above compound on the current collector body, the contact between the electrolyte salt in the electrolyte and the current collector body of the positive electrode can be reduced. Can be suppressed. As a result, cycle characteristics and capacity maintenance characteristics can be improved. Patent Document 1 describes the capacity retention rate (%) and capacity recovery rate (%) after standing at 50 ° C. for 2 weeks, and the cycle characteristics (%) of 300 cycles at 50 ° C. However, Patent Document 1 does not describe the discharge capacity.

In Patent Document 2, the thickness of the oxide film formed on the surface of the current collector body made of aluminum or aluminum alloy is set to 3 nm or less, and the oxide film is less susceptible to corrosion than aluminum. A positive electrode current collector in which a conductive layer made of metal or metal carbide is formed is described. In the example of Patent Document 2, the discharge capacity of the battery at each discharge rate is measured. According to this, at a rate of 50 C or higher, the discharge capacity of the battery is improved by the conductive layer. However, when compared with the 1 / 3C, 1C, and 5C rates, the aluminum foil with the conductive layer formed is compared with the discharge capacity of the battery of Test Example 1 in which the aluminum foil without the conductive layer is used as the current collector body. The discharge capacities of the batteries of Test Examples 2 to 7 in which is used as the current collector are low.

As described above, none of these protective films has yet achieved a non-aqueous electrolyte secondary battery having desirable cycle characteristics and output characteristics exhibiting desirable discharge capacity.

On the other hand, a lithium salt of a fluorine-containing anion such as LiPF ₆ (lithium hexafluorophosphate) or LiBF ₄ (lithium tetrafluoroborate) is generally used as an electrolyte salt of a nonaqueous electrolyte secondary battery. . LiPF ₆ is known to exhibit higher conductivity than LiBF ₄ while having low thermal stability. When the conductivity of the electrolyte is high, the initial capacity of the nonaqueous electrolyte secondary battery is increased, but when the thermal stability of the electrolyte is low, the cycle characteristics of the nonaqueous electrolyte secondary battery are deteriorated. From this, the non-aqueous electrolyte secondary battery using LiPF ₆ as the electrolytic salt has a higher initial capacity when using a high voltage than the non-aqueous electrolyte secondary battery using LiBF ₄ as the electrolytic salt, but the cycle characteristics are lowered. . Conversely, non-aqueous electrolyte secondary batteries using LiBF ₄ as the electrolyte salt can suppress deterioration of cycle characteristics when using high voltage because of the high thermal stability of the electrolyte, but the electrolyte has low conductivity and high resistance. It was difficult to obtain an initial capacity.
JP 2004-55247 A JP 2011-96667 A

(First issue)
The present inventors have formed a layer that does not hinder electron transfer on the surface of the current collector body, thereby suppressing corrosion of the current collector due to electrolytic salt or the like even at a high potential, and a passive film is spontaneously generated. It was examined whether the discharge capacity of the battery could be improved as compared with the case where the current collector body formed in the above was used. The present invention has been made in view of such circumstances, and a current collector for a positive electrode of a nonaqueous electrolyte secondary battery having excellent cycle characteristics and output characteristics even at a high potential, a method for producing the same, and a nonaqueous It is a first object of the present invention to provide an electrolyte secondary battery.

(Second problem)
It is a second object of the present invention to provide a non-aqueous electrolyte secondary battery capable of improving cycle characteristics while maintaining the initial capacity of the non-aqueous electrolyte secondary battery in a high voltage use environment.

(Third issue)
When the present inventors examined the protective layer of the current collector body, in the nonaqueous electrolyte secondary battery using Al as the positive electrode current collector body, on which a passive film can be formed on the surface, the resistance is low. It turned out to be difficult to maintain the capacity maintenance rate. Moreover, in the non-aqueous electrolyte secondary battery using the positive electrode having the current collector body on which the protective layer made of SnO ₂ is formed on the surface, the capacity retention rate is not maintained in the above-mentioned Patent Document 1. It turned out that resistance was high. That is, it can be said that none of these protective layers has yet achieved a desirable nonaqueous electrolyte secondary battery. The present invention has been made in view of such circumstances, and a third object of the present invention is to provide a positive electrode for a non-aqueous electrolyte secondary battery having a low resistance and a good capacity retention rate. And

(Fourth issue)
It is a fourth object of the present invention to provide a non-aqueous electrolyte secondary battery positive electrode current collector for achieving a non-aqueous electrolyte secondary battery having a low resistance and a good capacity retention rate.

(First means)
As a result of intensive studies of the first problem by the present inventors, the conductive oxide or specific resistance having a specific resistance of 9.9 × 10 ⁻³ Ωcm or less on the surface of the current collector body for positive electrode is 9.9. It has been found that by forming a coating layer made of a conductive nitride of × 10 ⁻³ Ωcm or less, the nonaqueous electrolyte secondary battery has excellent cycle characteristics and output characteristics even at a high potential.

That is, the current collector for a nonaqueous electrolyte secondary battery positive electrode of the present invention that solves the first problem has a current collector body and a specific resistance of 9.9 × formed on the surface of the current collector body. has a 10 ^-3 [Omega] cm or less is conductive oxide or the specific resistance is made of conductive nitride is 9.9 × 10 ^-3 Ωcm or less coating layer, a conductive oxide, Zn oxide, indium , Mo, W, Ti, Zr, Sn and H added at least one element selected, tin oxide added at least one element selected from F, W, Ta, Sb, P and B, It is one selected from zinc oxide added with at least one element selected from Ga, Al and B and titanium oxide added with Nb element, and the conductive nitride is TiN, ZrN, HfN, TaN, NbN, VN and Characterized in that it is a one selected from N.

A material obtained by adding at least one element selected from Zn, Mo, W, Ti, Zr, Sn and H to indium oxide is preferably indium zinc oxide. A material in which at least one element selected from Ga, Al, and B is added to zinc oxide is preferably aluminum zinc oxide or gallium zinc oxide.

The conductive oxide is preferably one in which at least one element selected from F, Sb and P is added to tin oxide.

The conductive nitride is preferably TiN.

The thickness of the coat layer is preferably 10 nm to 1 μm.

The nonaqueous electrolyte secondary battery of the present invention that solves the first problem includes the current collector for a positive electrode of the nonaqueous electrolyte secondary battery.

The nonaqueous electrolyte secondary battery of the present invention that solves the first problem has the current collector for a positive electrode of the nonaqueous electrolyte secondary battery, and when the total amount of the nonaqueous electrolyte is 100% by mass, It is preferable to have a non-aqueous electrolyte solution containing 2.0% by mass or more and 6.0% by mass or less of a cyclic compound having a sultone group.

Particularly, cyclic compounds having a sultone group are 1,3-propane sultone, 1,4-butene sultone, 1,3-propene sultone, 3-methyl-1,3-propene sultone, 1-methyl-1,3-propane sultone. It is preferably at least one selected from the group consisting of 2-methyl-1,3-propane sultone and 3-methyl-1,3-propane sultone.

The non-aqueous electrolyte secondary battery is for a non-aqueous electrolyte secondary battery positive electrode having a coating layer made of the above non-aqueous electrolyte and a conductive oxide in which at least one selected from F, Sb and P is added to tin oxide. And a current collector.

The method for producing a current collector for a positive electrode of a nonaqueous electrolyte secondary battery according to the present invention that solves the above first problem has a specific resistance of 9.9 × 10 ⁻³ Ωcm or less by sputtering on the surface of the current collector body. A coating layer forming step of forming a coating layer made of a certain conductive oxide or a conductive nitride having a specific resistance of 9.9 × 10 ⁻³ Ωcm or less, and the conductive oxide includes Zn, One in which at least one element selected from Mo, W, Ti, Zr, Sn and H is added, one in which at least one element selected from F, W, Ta, Sb, P and B is added to tin oxide, oxidation It is one selected from zinc added with at least one element selected from Ga, Al and B and titanium oxide added with Nb element. The conductive nitride is TiN, ZrN, HfN, TaN. , N N, characterized in that it is one selected from the VN and WN.

(Second means)
As a result of intensive studies on the second problem by the present inventors, a coating layer made of a conductive oxide is formed on the surface of the current collector body for positive electrode, and LiBF ₄ (lithium tetrafluoroborate) is added. It was found that by using a non-aqueous electrolyte contained as an electrolytic salt, the cycle characteristics can be improved while maintaining the initial capacity even in an environment where high voltage is used.

That is, the nonaqueous electrolyte secondary battery of the present invention that solves the second problem includes a current collector body and a coating layer made of a conductive oxide formed on the surface of the current collector body. A non-aqueous electrolyte secondary battery positive electrode having a current collector for a water electrolyte secondary battery positive electrode, and a non-aqueous electrolyte containing LiBF ₄ (lithium tetrafluoroborate) as an electrolyte salt, and conductive oxidation The product is an indium oxide to which at least one element selected from Zn, Mo, W, Ti, Zr, Sn and H is added, and at least one selected from F, W, Ta, Sb, P and B to tin oxide. It is any one selected from those obtained by adding at least one element selected from Ga, Al and B to zinc oxide, and those obtained by adding Nb element to titanium oxide. .

A material obtained by adding at least one element selected from Zn, Mo, W, Ti, Zr, Sn, and H to indium oxide is preferably indium tin oxide or indium zinc oxide.

What added at least one element chosen from Ga, Al, and B to zinc oxide is preferably aluminum zinc oxide or gallium zinc oxide.

The conductive oxide preferably has a specific resistance of 9.9 × 10 ⁻³ Ωcm or less.

The film thickness of the coating layer is preferably 10 nm to 1 μm.

(Third means)
As a result of the present inventors diligently examining the third problem, the specific resistance between the positive electrode current collector main body and the protective layer such as SnO ₂ is higher than the specific resistance of the current collector main body and the ratio of the protective layer. It has been found that by introducing a new protective layer lower than the resistance, a positive electrode for a non-aqueous electrolyte secondary battery having a low resistance and a good capacity retention rate can be provided.

That is, the positive electrode for a nonaqueous electrolyte secondary battery of the present invention that solves the third problem is formed on the surface of the current collector body, the first layer formed on the surface of the current collector body, and the surface of the first layer. In the positive electrode for a non-aqueous electrolyte secondary battery having the second layer and the active material layer formed on the surface of the second layer, the specific resistance of the first layer is lower than the specific resistance of the second layer, and It is characterized by being higher than the specific resistance of the current collector body.

The reason why low resistance is exhibited when the positive electrode for a non-aqueous electrolyte secondary battery of the present invention that solves the third problem is used is considered to be as follows.

First, in the conventional positive electrode, considering the resistance when flowing electricity to the protective layer of the collector body and SnO _2, the collector body itself, in addition to the resistance caused by SnO ₂ itself, the current collector body and SnO ₂ There is a resistance that occurs at the interface. Since electrochemical properties in the collector body and SnO ₂ (each specific resistance value) are largely different, it is considered very large Schottky barrier arises at the interface of the current collector body and SnO _2. As a result, it is assumed that the resistance of the conventional positive electrode has increased.

In the positive electrode for a non-aqueous electrolyte secondary battery of the present invention that solves the third problem, a current collector body, a first layer (for example, In ₂ O ₃ —ZnO (IZO)), and a second layer (for example, SnO ₂ ) In addition to the resistance generated in the current collector body itself, IZO itself, and SnO ₂ itself, the resistance generated in the interface between the current collector body and IZO, and the interface between IZO and SnO ₂ is considered. Exists. However, since the electrochemical properties (respective resistivity values) of the current collector body and IZO are closer than the electrochemical properties of the current collector body and SnO ₂ , the current collector body and IZO The Schottky barrier generated at the interface is significantly lower than the Schottky barrier generated at the interface between the current collector body and SnO ₂ . As a result, it is presumed that the resistance at the interface between the current collector body and the IZO is extremely low. Furthermore, since the electrochemical properties (respective specific resistance and band gap) of IZO and SnO ₂ are both closer to the electrochemical properties of the current collector body and SnO ₂ , IZO and SnO ₂ It is assumed that the resistance generated at the interface is extremely low.

Therefore, the positive electrode for a non-aqueous electrolyte secondary battery according to the present invention that solves the above third problem has a lower resistance than the conventional positive electrode, although a protective layer is newly added to the conventional positive electrode. Show.

(Fourth means)
As a result of the present inventors diligently examining the fourth problem, a non-aqueous electrolyte in which a metal having a higher specific resistance than the current collector body is introduced between the current collector body for the positive electrode and the coating layer such as SnO _2. The non-aqueous electrolyte secondary battery using the secondary battery positive electrode current collector was found to have a low resistance and a good capacity retention rate.

That is, the non-aqueous electrolyte secondary battery positive electrode current collector of the present invention that solves the fourth problem is a non-aqueous electrolyte secondary battery having a current collector body and a coating layer containing a metal oxide or a metal nitride. The current collector for the battery positive electrode has a high resistance metal (hereinafter sometimes simply referred to as “high resistance metal”) having a specific resistance higher than that of the current collector body between the current collector body and the coating layer. It is characterized by.

When the non-aqueous electrolyte secondary battery positive electrode current collector of the present invention that solves the fourth problem is used, the non-aqueous electrolyte secondary battery exhibits a low resistance for the following reason. .

First, in the conventional current collector, considering the resistance when electricity flows through the current collector body and the SnO ₂ protective layer, the current collector body itself, the resistance generated by the SnO ₂ itself, There is a resistance that occurs at the SnO ₂ interface. Since electrochemical properties in the collector body and SnO ₂ (each specific resistance value) are largely different, it is considered very large Schottky barrier arises at the interface of the current collector body and SnO _2. As a result, it is assumed that the resistance of the current collector has increased.

Next, in the current collector for the positive electrode of the nonaqueous electrolyte secondary battery of the present invention that solves the fourth problem, the resistance when electricity flows through the current collector body, the high-resistance metal, and the coating layer (for example, SnO ₂ ). In addition to the resistance generated by the current collector body, the high resistance metal itself, and SnO ₂ itself, there is a resistance generated at the interface between the current collector body and the high resistance metal and the interface between the high resistance metal and SnO _2. To do. Here, it is considered that the resistance generated at the interface between the current collector body and the high resistance metal is extremely low. This is because both the current collector body and the high resistance metal are metals, and the electrochemical properties (respective resistivity values) of both are similar. Then, considering the resistance generated at the interface between the high-resistance metal and SnO _2, electrochemical properties (each specific resistance value) between the high resistance metal and SnO ₂ are electrochemical the collector body and SnO ₂ Since it is closer to the nature, the Schottky barrier generated at the interface between the high-resistance metal and SnO ₂ is significantly lower than the Schottky barrier generated at the interface between the current collector body and SnO ₂ . As a result, it is assumed that the resistance generated at the interface between the high resistance metal and SnO ₂ is significantly lower than the resistance generated at the interface between the current collector body and SnO ₂ .

Therefore, the non-aqueous electrolyte secondary battery positive electrode current collector of the present invention that solves the fourth problem shows lower resistance than a conventional current collector having a coating layer of SnO ₂ or the like.

(First effect)
The non-aqueous electrolyte secondary battery positive electrode current collector of the present invention according to the first means is a conductive oxide or specific resistance having a specific resistance of 9.9 × 10 ⁻³ Ωcm or less on the surface of the current collector body. Has a coat layer made of a conductive nitride having a thickness of 9.9 × 10 ⁻³ Ωcm or less. Since the coat layer has conductivity, the electron mobility to the current collector body is not greatly reduced even if the coat layer is on the surface of the current collector body. Further, since the surface of the current collector body is protected by the coat layer, the current collector body is prevented from being corroded by the electrolytic salt or the like. Therefore, the non-aqueous electrolyte secondary battery having the non-aqueous electrolyte secondary battery positive electrode current collector has excellent cycle characteristics and output characteristics.

The method for producing a current collector for a nonaqueous electrolyte secondary battery positive electrode according to the present invention as the first means can easily form a coat layer on the surface of the current collector body.

Since the nonaqueous electrolyte secondary battery of the present invention as the first means has the current collector for the positive electrode of the nonaqueous electrolyte secondary battery, it has excellent cycle characteristics and output characteristics.

The non-aqueous electrolyte secondary battery of the present invention of the first means has a non-aqueous electrolyte solution containing the non-aqueous electrolyte secondary battery positive electrode current collector and a cyclic compound having a sultone group, and thus a further excellent cycle. Has characteristics.

(Second effect)
In the non-aqueous electrolyte secondary battery according to the second means of the present invention, the coat layer made of a conductive oxide is formed on the surface of the current collector body for positive electrode. Resistance can be reduced. In addition, since the nonaqueous electrolyte secondary battery of the present invention of the second means further has a nonaqueous electrolyte containing LiBF ₄ (lithium tetrafluoroborate) as an electrolyte salt, cycle characteristics are improved. LiBF ₄ has a problem that the conductivity of the battery is low and the battery capacity increases and the initial capacity is low, but the resistance of the positive electrode can be reduced by the effect of the coating layer formed on the positive electrode current collector body. A decrease in initial capacity can be prevented.

(Third effect)
The positive electrode for a non-aqueous electrolyte secondary battery according to the third aspect of the present invention has the protective layers of the first layer and the second layer on the surface of the current collector body, so that the current collector body is extremely unlikely to corrode. . In addition, the positive electrode for a non-aqueous electrolyte secondary battery according to the third aspect of the present invention has a low resistance despite the fact that the positive electrode current collector has two protective layers. Mobility does not decrease greatly. As a result, the nonaqueous electrolyte secondary battery using the positive electrode for a nonaqueous electrolyte secondary battery of the present invention of the third means can exhibit a good capacity retention rate even under high potential driving conditions.

(4th effect)
The non-aqueous electrolyte secondary battery using the non-aqueous electrolyte secondary battery positive electrode current collector of the present invention of the fourth means can have a low resistance and a good capacity retention rate.

It is a schematic diagram explaining the positive electrode for nonaqueous electrolyte secondary batteries of 1st Embodiment. It is a graph which shows the relationship between the cycle number of Example 1, Example 2, and the comparative example 1, and a capacity | capacitance maintenance factor (%). It is a schematic diagram explaining the positive electrode for nonaqueous electrolyte secondary batteries of 3rd Embodiment.

1: current collector body, 2: coat layer, 3: active material layer, 4: current collector for non-aqueous electrolyte secondary battery positive electrode, 10: current collector body, 21: first layer, 22: second layer , 31: active material layer, 50: positive electrode for nonaqueous electrolyte secondary battery.

Each embodiment of the present invention will be described below. Unless otherwise specified, the numerical range “x to y” described in this specification includes the lower limit x and the upper limit y. The numerical range can be configured by arbitrarily combining these upper limit value and lower limit value and the numerical values listed in the examples. Furthermore, numerical values arbitrarily selected from the numerical value range can be used as upper and lower numerical values.
(First embodiment)
<Nonaqueous electrolyte secondary battery positive electrode current collector>
The non-aqueous electrolyte secondary battery positive electrode current collector according to the first embodiment of the present invention has a current collector body and a specific resistance of 9.9 × 10 ⁻³ Ωcm formed on the surface of the current collector body. A conductive oxide or a coat layer made of conductive nitride having a specific resistance of 9.9 × 10 ⁻³ Ωcm or less.

The current collector body refers to a chemically inert electronic high conductor that keeps current flowing through the electrode during discharge or charging of the nonaqueous electrolyte secondary battery. In the current collector for a nonaqueous electrolyte secondary battery positive electrode according to the first embodiment of the present invention, a coat layer is formed on the surface of the current collector body. The coat layer reduces the contact between the electrolytic salt and the current collector body, and suppresses the corrosion of the current collector body by the electrolytic salt and the like. Therefore, a metal material such as stainless steel, titanium, nickel, aluminum, copper, or a conductive resin can be used as a material for the current collector body. The current collector body can take the form of a foil, a sheet, a film and the like. Therefore, for example, a metal foil such as a copper foil, a nickel foil, an aluminum foil, and a stainless steel foil can be suitably used as the current collector body.

The current collector body preferably has a thickness of 10 μm to 100 μm.

The coat layer is formed on the surface of the current collector body and has a specific resistance of 9.9 × 10 ⁻³ Ωcm or less or a conductive nitride having a specific resistance of 9.9 × 10 ⁻³ Ωcm or less. It consists of things. Normally, when an aluminum foil is used as a current collector body, the surface of the aluminum foil is formed by a reaction with Al ₂ O ₃ formed by a natural reaction with oxygen in the atmosphere and an electrolytic salt in the electrolytic solution. A passive film such as AlF ₃ is formed. This passive film is an insulator, and the number of digits of the specific resistance (Ωcm) is about 10 ⁸ . The aluminum foil is protected from the electrolytic salt by a passive film. However, the passive film is a high resistance film. Therefore, an electrode using a current collector body having a passive film on its surface has a high resistance, and a battery using the electrode has a reduced discharge capacity compared to a battery using a current collector body without a passive film. Output characteristics deteriorate.

In the current collector for a nonaqueous electrolyte secondary battery positive electrode according to the first embodiment of the present invention, a coat layer is formed in advance on the surface of the current collector body. Therefore, it is difficult to form the passive film on the surface of the current collector body. That is, this coat layer can suppress the formation of the high resistance layer on the surface of the current collector body. Further, since the contact between the electrolytic salt or the like and the current collector main body can be reduced by the coat layer, corrosion due to the electrolytic salt or the like of the current collector main body can be suppressed.

Further, since the specific resistance of the coat layer is 9.9 × 10 ⁻³ Ωcm or less, the resistance of the electrode is not substantially increased by this coat layer. Therefore, the battery having the current collector for a nonaqueous electrolyte secondary battery positive electrode according to the first embodiment of the present invention can maintain the output characteristics of the battery well.

The coating layer is made of conductive oxide or conductive nitride. The conductive oxide is indium oxide added with at least one element selected from Zn, Mo, W, Ti, Zr, Sn and H, and tin oxide is selected from F, W, Ta, Sb, P and B Any one selected from the group consisting of zinc oxide added with at least one element selected from Ga, Al and B, and titanium oxide added with an Nb element. The conductive nitride is any one selected from TiN, ZrN, HfN, TaN, NbN, VN and WN. Since the coating layer is made of the above-mentioned conductive oxide or conductive nitride, it is electrochemically stable to oxygen, electrolytic solution and electrolytic salt in the atmosphere, and is electrochemically stable even at high voltage. is there.

All of the above conductive oxides are metal oxides with other elements added. The element may be added alone or in the form of an oxide containing the element. The above conductive oxide has a charge transfer body that can move freely, that is, carriers due to the addition of elements to the metal oxide as a base material and the generation of oxygen vacancies in the structure of the metal oxide. Indicates. Therefore, the specific resistance of the conductive oxide is low.

Such a material can change the specific resistance by changing the ratio of the element to be added. In the present invention, the amount of each element added may be adjusted so that the conductive oxide has a specific resistance in the above range.

Among those in which at least one element selected from Zn, Mo, W, Ti, Zr, Sn and H is added to indium oxide, those in which Zn element or Sn element is added to indium oxide are preferable. Examples of the indium oxide added with the Zn element include indium zinc oxide, and examples of the indium oxide added with the Sn element include indium tin oxide. In ₂ O ₃ —ZnO (IZO) is preferable as the indium zinc oxide, and In ₂ O ₃ —SnO ₂ (ITO) is preferable as the indium tin oxide.

Of those obtained by adding at least one element selected from F, W, Ta, Sb, P and B to tin oxide, those obtained by adding F element, Sb element, Ta element or P element to tin oxide are preferable. Fluorine tin oxide can be cited as the addition of F element to tin oxide, antimony tin oxide can be cited as the addition of Sb element to tin oxide, and tantalum as the addition of Ta element to tin oxide. Examples of the tin oxide include phosphorous tin oxide as a P element added to tin oxide. Fluorine tin oxide is preferably fluorine-added tin oxide (FTO), antimony tin oxide is preferably antimony-added tin oxide (ATO), tantalum tin oxide is preferably tantalum-added tin oxide (TaTO), and phosphorus tin oxide is preferred. Phosphorus-doped tin oxide (PTO) is preferred.

Among those obtained by adding at least one element selected from Ga, Al and B to zinc oxide, those obtained by adding Ga element or Al element to zinc oxide are preferable. Examples of the zinc oxide added with the Ga element include gallium zinc oxide, and examples of the zinc oxide added with the Al element include aluminum zinc oxide. Gallium-doped zinc oxide (GZO) is preferred as the gallium zinc oxide, and aluminum-doped zinc oxide (AZO) is preferred as the aluminum zinc oxide.

An example of the titanium oxide added with Nb element is titanium niobium oxide. The titanium niobium oxide is preferably TiO ₂ ; Nb.

Here, when an aluminum foil is used for the current collector body, if the coat layer is formed on the current collector body at a high temperature, the difference in heat shrinkage between the current collector body and the coat layer when the temperature is returned to room temperature. Due to the film stress. Therefore, the current collector body on which the coat layer is formed is not flat, and when an active material or the like is applied to the current collector body on which the coat layer is formed, the applicability is affected and the battery characteristics are impaired. For this reason, it is desirable that the coat layer be formed on the current collector body as much as possible at room temperature.

In order to form the coating layer on the current collector body at room temperature, the conductive oxide is preferably AZO. AZO is a crystalline material, but can have a sufficiently low resistance even at room temperature. In general, when the resistance of a crystalline material is to be lowered, heat treatment is performed to increase the crystallinity. AZO can achieve low resistance even at room temperature, largely because of the physical properties of the material. AZO can adjust the specific resistance appropriately by optimizing the amount of Al added to zinc oxide without heat treatment. Is possible.

The conductive oxide is preferably IZO. IZO is a composite of indium oxide and zinc oxide and has an amorphous structure. IZO has sufficiently low resistance even at room temperature. IZO has a high smoothness and does not cause a local reaction. Due to its characteristics, IZO has a small film stress and little influence on battery characteristics.

The conductive oxide is preferably GZO. GZO can be further reduced in resistance at room temperature when compared with AZO.

The conductive oxide is preferably one in which at least one element selected from F, W, Ta, Sb, P and B is added to tin oxide. When these additive elements enter tin oxide, the conductivity can be improved.

The conductive nitride is any one selected from TiN, ZrN, HfN, TaN, NbN, VN and WN. Conductive nitrides have higher hardness than conductive oxides, high wear resistance, and high mechanical strength. Therefore, by using conductive nitride for the coat layer, the strength of the coat layer is improved and the coatability of the coat layer is improved. In particular, the conductive nitride is preferably TiN. TiN is excellent in conductivity and corrosion resistance.

The film thickness of the coating layer is preferably 10 nm to 1 μm, and more preferably 20 nm to 800 nm. If the thickness of the coat layer is 10 nm or more, the surface of the current collector body can be protected and corrosion of the current collector body due to the electrolytic solution can be suppressed. If the thickness of the coat layer is 1 μm or less, the volume occupied by the current collector inside the battery can be made appropriate. If the volume occupied by the current collector in the battery becomes too large, the amount of active material and the like must be reduced, which leads to a decrease in battery capacity.

As a method for forming a coating layer on the current collector body, a sol-gel method, a pyrolysis spray method, a CVD method (Chemical Vapor Deposition method), a sputtering method, a vacuum deposition method, a coating method, or the like can be used. This coat layer forming method may be appropriately selected and used according to the material and shape of the current collector body and the type of conductive oxide and conductive nitride constituting the coat layer.

The current collector for the positive electrode of the nonaqueous electrolyte secondary battery according to the first embodiment of the present invention can be preferably manufactured by using the following manufacturing method.

<Method for producing current collector for positive electrode of nonaqueous electrolyte secondary battery>
In the method for producing a current collector for a nonaqueous electrolyte secondary battery positive electrode according to the first embodiment of the present invention, the specific resistance is 9.9 × 10 ⁻³ Ωcm or less by sputtering on the surface of the current collector body. A coating layer forming step of forming a coating layer made of a conductive oxide or a conductive nitride having a specific resistance of 9.9 × 10 ⁻³ Ωcm or less.

In the coat layer forming step, the coat layer is formed by a sputtering method using a conductive oxide or a conductive nitride as a target. The specific resistance of the formed coating layer is 9.9 × 10 ⁻³ Ωcm or less. As the conductive oxide or the conductive nitride, the same materials as those described in the description of the current collector for the positive electrode of the nonaqueous electrolyte secondary battery can be used. Note that the specific resistance of the conductive oxide or the conductive nitride is preferably 1.0 × 10 ⁻⁴ Ωcm or more and 1.0 × 10 ⁻³ Ωcm or less. By using the sputtering method, a thin coating layer having high adhesion can be easily formed on the surface of the current collector body.

The conductive oxide is preferably any one selected from IZO, AZO and GZO. If these conductive oxides are used, the coating layer forming step can be performed not at a high temperature but at a temperature close to room temperature.

The conductive nitride is preferably TiN.

<Nonaqueous electrolyte secondary battery>
The nonaqueous electrolyte secondary battery according to the first embodiment of the present invention has the current collector for a nonaqueous electrolyte secondary battery positive electrode according to the first embodiment. The non-aqueous electrolyte secondary battery having the non-aqueous electrolyte secondary battery positive electrode current collector has a large charge / discharge capacity and excellent cycle performance.

(Positive electrode for non-aqueous electrolyte secondary battery)
The non-aqueous electrolyte secondary battery has a positive electrode having the current collector for a non-aqueous electrolyte secondary battery positive electrode.

In the positive electrode, a positive electrode active material layer formed by binding a positive electrode active material with a binder is attached to the non-aqueous electrolyte secondary battery positive electrode current collector. The schematic diagram explaining the positive electrode for nonaqueous electrolyte secondary batteries of 1st Embodiment is shown in FIG. As shown in FIG. 1, a coat layer 2 is formed on the current collector body 1, and a positive electrode active material layer 3 is formed on the coat layer 2. In the first embodiment, the current collector body 1 on which the coat layer 2 is formed is referred to as a non-aqueous electrolyte secondary battery positive electrode current collector 4.

The positive electrode active material layer may further contain a conductive additive. The positive electrode is prepared by preparing a composition for forming a positive electrode active material layer containing a positive electrode active material, a binder and, if necessary, a conductive additive, and adding a suitable solvent to the above composition to form a paste, and then coating After applying to the surface of the current collector body on which the layer is formed, it can be dried and compressed to increase the electrode density as necessary.

As a method for applying the composition for forming a positive electrode active material layer, a conventionally known method such as a roll coating method, a dip coating method, a doctor blade method, a spray coating method, or a curtain coating method may be used.

As the solvent for adjusting the viscosity, N-methyl-2-pyrrolidone (NMP), methanol, methyl isobutyl ketone (MIBK) and the like can be used.

A lithium-containing compound is suitable as the positive electrode active material. For example, lithium cobalt composite oxide having a layered structure, lithium nickel composite oxide having a layered structure, lithium manganese composite oxide having a spinel structure, general formula:
_{_{_{_{LiCo p Ni q Mn r D s}}}} O 2 (D is the doping component, Al, Mg, Ti, Sn , Zn, W, Zr, Mo, Fe, and a component consisting of Na, added are if necessary P + q + r + s = 1, 0 <p <1, 0 ≦ q <1, 0 ≦ r <1, 0 ≦ s <1), a lithium composite metal oxide having an olivine type lithium iron phosphate Lithium-containing metal composite oxides such as composite oxides can be used. Other metal compounds can also be used as the positive electrode active material. Examples of other metal compounds include oxides such as titanium oxide, vanadium oxide, and manganese dioxide, or disulfides such as titanium sulfide and molybdenum sulfide.

In particular, the positive electrode active material has the general formula:
_{_{_{_{LiCo p Ni q Mn r D s}}}} O 2 (D is the doping component, Al, Mg, Ti, Sn , Zn, W, Zr, Mo, Fe, and a component consisting of Na, added are if necessary P + q + r + s = 1, 0 <p <1, 0 ≦ q <1, 0 ≦ r <1, 0 ≦ s <1). It is preferable to include a lithium mixed metal oxide having a layered structure represented by: The lithium composite metal oxide is excellent in thermal stability and low in cost. Therefore, by including the lithium composite metal oxide, an inexpensive non-aqueous electrolyte secondary battery with good thermal stability can be obtained.

Examples of the lithium composite metal oxide include LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ , LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , LiNi _0.5 Co _0.2 Mn _{0. 3} O ₂ , LiCoO ₂ , LiNi _0.8 Co _0.2 O ₂ , LiCoMnO ₂ can be used. Among these, LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ and LiNi _0.5 Co _0.2 Mn _0.3 O ₂ are preferable in terms of thermal stability.

The binder serves to bind the positive electrode active material and the conductive additive to the current collector. As the binder, for example, a fluorine-containing resin such as polyvinylidene fluoride, polytetrafluoroethylene, or fluororubber, a thermoplastic resin such as polypropylene or polyethylene, an imide resin such as polyimide or polyamideimide, or an alkoxysilyl group-containing resin is used. be able to.

Conductive aid is added to increase the conductivity of the electrode. As the conductive assistant, for example, carbon black, graphite, acetylene black (AB), ketjen black (KB), vapor grown carbon fiber (Vapor Carbon Carbon Fiber: VGCF), etc., which are carbonaceous fine particles, are used alone. Or in combination of two or more. The amount of the conductive aid used is not particularly limited, but can be, for example, about 1 to 30 parts by mass with respect to 100 parts by mass of the active material contained in the positive electrode.

(Other components)
The non-aqueous electrolyte secondary battery according to the first embodiment of the present invention uses a negative electrode, a separator, and a non-aqueous electrolyte in addition to the above-described positive electrode for a non-aqueous electrolyte secondary battery as a battery component.

The negative electrode has a current collector and a negative electrode active material layer bound to the surface of the current collector. A negative electrode active material layer contains a negative electrode active material and a binder, and contains a conductive support agent as needed. The current collector, binder, and conductive additive are the same as those described for the current collector body, binder, and conductive additive in the positive electrode.

As the negative electrode active material, a carbon-based material that can occlude and release lithium, an element that can be alloyed with lithium, an elemental compound that has an element that can be alloyed with lithium, or a polymer material can be used.

Examples of the carbon-based material include non-graphitizable carbon, artificial graphite, coke, graphite, glassy carbon, a fired organic polymer compound, carbon fiber, activated carbon, or carbon black. Here, the organic polymer compound fired body refers to a material obtained by firing and carbonizing a polymer material such as phenols and furans at an appropriate temperature.

Elements that can be alloyed with lithium include Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Ti, Ag, Zn, Cd, Al, Ga, In, Si, Ge, Sn , Pb, Sb and Bi. In particular, silicon (Si) or tin (Sn) is preferable.

Examples of elemental compounds having elements that can be alloyed with lithium include ZnLiAl, AlSb, SiB ₄ , SiB ₆ , Mg ₂ Si, Mg ₂ Sn, Ni ₂ Si, TiSi ₂ , MoSi ₂ ,
_{_{_{CoSi 2, NiSi 2, CaSi 2}}} , CrSi 2, Cu 5 Si, FeSi 2, MnSi 2, NbSi 2, TaSi 2, VSi 2, WSi 2, ZnSi 2, SiC, Si 3 N 4, Si 2 N 2 O, SiO _v (0 <v ≦ 2), SnO _w (0 <w ≦ 2), SnSiO ₃ , LiSiO
Alternatively, LiSnO can be used. As the elemental compound having an element that can be alloyed with lithium, a silicon compound or a tin compound is preferable. As the silicon compound, SiO _v (0.5 ≦ v ≦ 1.5) is preferable. As the tin compound, for example, a tin alloy (Cu—Sn alloy, Co—Sn alloy, etc.) can be used.

As the polymer material, polyacetylene, polypyrrole, or the like can be used.

The separator separates the positive electrode and the negative electrode and allows lithium ions to pass through while preventing a short circuit of current due to contact between the two electrodes. As the separator, for example, a porous film made of synthetic resin such as polytetrafluoroethylene, polypropylene, or polyethylene, or a porous film made of ceramics can be used.

The nonaqueous electrolytic solution contains a solvent and an electrolyte dissolved in the solvent.

As the solvent, for example, cyclic esters, chain esters, and ethers can be used. As cyclic esters, for example, ethylene carbonate, propylene carbonate, butylene carbonate, gamma butyrolactone, vinylene carbonate, 2-methyl-gamma butyrolactone, acetyl-gamma butyrolactone, and gamma valerolactone can be used. Examples of the chain esters include dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dipropyl carbonate, methyl ethyl carbonate, propionic acid alkyl ester, malonic acid dialkyl ester, and acetic acid alkyl ester. Examples of ethers that can be used include tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-diethoxyethane, and 1,2-dibutoxyethane.

Moreover, as an electrolyte dissolved in the solvent, for example, a lithium salt such as LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ can be used.

As the non-aqueous electrolyte, for example, a lithium salt such as LiClO ₄ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO _{3 is} added in a solvent such as ethylene carbonate, dimethyl carbonate, propylene carbonate, and dimethyl carbonate to 0.5 mol / l to 1.7 mol. A solution dissolved at a concentration of about 1 / l can be used.

The nonaqueous electrolytic solution may contain an additive for suppressing the decomposition of the nonaqueous electrolytic solution. As the additive, for example, a sulfone compound, an α, β-unsaturated hostone, a phosphocarboxylic acid anhydride, or a cyclic compound having a sultone group can be used.

Examples of the sulfone compound include sulfobenzoic anhydride and 1,2-benzenedisulfonic anhydride.

Examples of α, β-unsaturated hostons include 2-methoxy-2,5-dihydro-1,2-oxaphosphole-2-oxide, 2-ethoxy-2,5-dihydro-1,2-oxaphos Hole-2-oxide, 2- (2,2,2-trifluoroethoxy) -2,5-dihydro-1,2-oxaphosphole-2-oxide, 1-ethoxy-1,3-dihydro-2, 1-benzooxaphosphol-1-oxide.

Examples of phosphocarboxylic acid anhydrides include 2-methyl-1,2-oxaphosphole-5 (2H) -one-2-oxide, 2-ethyl-1,2-oxaphosphole-5 (2H)- On-2-oxide, 2-vinyl-1,2-oxaphosphole-5 (2H) -one-2-oxide, 2-ethoxy-1,2-oxaphosphole-5 (2H) -one-2- Oxide, 1-ethoxy-2,1-benzooxaphosphole-3 (1H) -one-1-oxide.

The cyclic compound having a sultone group can be selected from those having a 4-membered ring, a 5-membered ring, a 6-membered ring, or a 7-membered ring. Examples of cyclic compounds having a sultone group include 1,3-propane sultone, 1,4-butane sultone, 1,4-butene sultone, 1,3-propene sultone, 1-methyl-1,3-propane sultone, and 2-methyl. -1,3-propane sultone and 3-methyl-1,3-propane sultone, 1,1,2,2-tetrafluoro-2-hydroxyethanesulfonic acid sultone, 3,8 (10) -p-menthadiene-3 , 10-sultone, 1,8-naphtha sultone, 4,5,6,7-tetrabromophenol sulfophthalene, 2- [bis (3,5-dibromo-4-hydroxyphenyl) hydroxymethyl] benzenesulfonic acid γ- Sultone, 4-hydroxy-2,5-naphthalenedisulfonic acid 5,4-sultone, 2,4-butane sultone, γ-butane sultone, δ-hexadecane sultone, 1,2,5,6-tetradeoxy-1-[(1 , 2,3,4-Tetrahydro-5-methyl-2,4-dioxo Limidin) -1-yl] -6-sulfo-β-D-erythro-hexofuranose sultone, sultone 3-hydroxy-2-octanesulfonate, sultone 4-hydroxy-2-octanesulfonate, 1,2,3a , 4,8,14,15,17-Octahydro-1β-[(methylsulfonyloxy) methyl] -1,3aβ-dimethyl-2,8,14,17-tetraoxo-11,12-dimethoxy-15,16- Dihydroxy [1] benzopyrano [2 ', 3': 6,7] naphtho [2,1-g] oxazolo [3,2-b] isoquinoline-15β- (methanesulfonic acid) 15,16-sultone, 1-chloro -1,2,2-trifluoro-2-hydroxyethanesulfonic acid sultone, 2-chloro-1,2,2-trifluoro-2-hydroxyethanesulfonic acid sultone, biphenyl sultone, HBP sultone, (3R) -2 -Salicyl-3α- (1-pyrenyl) -5β- (hydroxymethyl) isoxazolidine-4β-sulfonic acid 4,5-sultone, 3-hydroxy-1-propene-1-sulphonic acid sultone, 3-hydroxy-3- (G Rimethoxysilyl) -1-propanesulfonic acid 1,3-sultone, 1-hydroxy-1,1,2,3,3,3-hexafluoropropane-2-sulfonic acid 2,1-sultone, 2'-hydroxy -1,1'-biacenaphthylene-2-sulfonic acid 2,2'-sultone, 3- (tributylaminio) -3-hydroxy-1-propanesulfonic acid 1,3-sultone, 1- (hydroxymethyl) -2 -Azabicyclo [2,2,2] octane-2-sulfonic acid sultone, 1-hydroxy-6- (triethoxysilyl) -3-hexanesulfonic acid 3,1-sultone, 2,2-dimethyl-3bα-hydroxy- 6-oxo-3aβ, 5,6,7,7aα, 8aβ-hexahydro-2H-1,3,4,8-tetraoxa-6a-azadicyclopenta [a, f] pentalene-3cα (3bβH) -methanesulfone Sultone acid, 2α, 3α- (isopropylidenebisoxy) -2,3,6,7,8,8aα-hexahydro-3aα-hydroxy-5H-1,4-dioxa-7a-azacyclopenta [a] indene- 3bα (3aH) -sultone methanesulfonate, 2,2- Dimethyl-3bα-hydroxy-3aβ, 5,6,7,7aα, 8aβ-hexahydro-2H-1,3,4,8-tetraoxa-6a-azadicyclopenta [a, f] pentalene-3cα (3bβH)- Sultone methanesulfonate, 2,2-dimethyl-3bα-hydroxy-3aβ, 5,6,7,7aα, 8aβ-hexahydro-2H, 4H-1,3,8-trioxa-4,6a-diazadicyclopenta [ a, f] pentalene-3cα (3bβH) -sultone methanesulfonate, 2,2-dimethyl-3bα-hydroxy-4-ethoxy-3aβ, 3b, 5,6,6aα, 7aβ-hexahydro-4H-1,3, 7-trioxa-5-aza-2H-cyclopenta [a] pentalene-4α-methanesulfonic acid sultone, 2,2,5β-trimethyl-3bα-hydroxy-6-oxo-3aβ, 5,6,7,7aα, 8aβ -Hexahydro-2H, 4H-1,3,8-trioxa-4,6a-diazadicyclopenta [a, f] pentalene-3cα (3bβH) -sultone methanesulfonate, 2- (2-hydroxyphenyl) -4 -Oxo-1,2,3,4-tetrahydropyridine-1-sulfonic acid sultone, 2- (2-hydroxy- 1-naphthyl) -4-methylbenzenesulfonic acid sultone, 2- (2-methyl-3-chloro-6-hydroxyphenyl) -4-methylbenzenesulfonic acid sultone, 2- (1-hydroxy-2-naphthyl)- Sultone 4-methylbenzenesulfonate, 2- (2-hydroxy-5-methylphenyl) -4-methylbenzenesulfonate, 2- (2-hydroxy-4-methyl-5-chlorophenyl) -4-methylbenzenesulfone Sultone acid, (2R) -2β- (2,4-dioxo-5-methyl-1,2,3,4-tetrahydropyrimidin-1-yl) -3aα, 3bβ-dihydroxy-5,5,7-trimethyl- 2,3,3a, 3b, 4,5,7a, 8,8a α-nonahydro-1-oxa-7a-azacyclopenta [a] indene-4α-sulfonic acid 4,3a-sultone, (2R) -2β- (2,4-Dioxo-5-methyl-1,2,3,4-tetrahydropyrimidin-1-yl) -3aα, 3bβ-dihydroxy-5,7,7-trimethyl-2,3,3a, 3b, 6 , 7,7a, 8,8aα-Nonahydro-1-oxa-7a-azacyclopenta [a] indene-4-s Phosphonic acid 4,3a-sultone, (2R) -2β- (2,4-dioxo-5-methyl-1,2,3,4-tetrahydropyrimidin-1-yl) -3aα, 3bβ-dihydroxy-5-methyl -5β, 7-diethyl-2,3,3a, 3b, 4,5,7a, 8,8a α-nonahydro-1-oxa-7a-azacyclopenta [a] indene-4α-sulfonic acid 4,3a-sultone (2R) -2β- (2,4-dioxo-5-methyl-1,2,3,4-tetrahydropyrimidin-1-yl) -3aα, 3bβ-dihydroxy-5-methyl-5α, 7-diethyl- 2,3,3a, 3b, 4,5,7a, 8,8a α-nonahydro-1-oxa-7a-azacyclopenta [a] indene-4α-sulfonic acid 4,3a-sultone, (2R, 5Z)- 2β- (2,4-Dioxo-5-methyl-1,2,3,4-tetrahydropyrimidin-1-yl) -3aα, 3bβ-dihydroxy-5-ethylidene-7,7-diethyl-2,3,3a , 3b, 4,5,6,7,7a, 8,8a α-Undecahydro-1-oxa-7a-azacyclopenta [a] indene-4α-sulfonic acid 4,3a-sultone, N- [2β- (2 -Hydroxyethyl) -2-allyltetrahydro-2H-pyran-3α-yl] ami Sulfuric sultone include (4aa) -7 [beta] acetoxy -8aα- (2- hydroxyethyl) octahydro -5H- pyrano [3,2-b] pyridine-5-sultone.

Particularly, cyclic compounds having a sultone group are 1,3-propane sultone, 1,4-butene sultone, 1,3-propene sultone, 3-methyl-1,3-propene sultone, 1-methyl-1,3-propane sultone. It is preferably at least one selected from the group consisting of 2-methyl-1,3-propane sultone and 3-methyl-1,3-propane sultone. These cyclic compounds exhibit high effects as additives.

In particular, the nonaqueous electrolytic solution preferably contains 2.0% by mass or more and 6.0% by mass or less of a cyclic compound having a sultone group when the entire nonaqueous electrolytic solution is 100% by mass.

A cyclic compound having a sultone group has a small LUMO (lowest unoccupied molecular orbital) and is easily reduced. Therefore, at the time of charge / discharge of the nonaqueous electrolyte secondary battery, the cyclic compound having a sultone group is reduced and decomposed preferentially over the main component of the nonaqueous electrolyte. Therefore, the reduction | restoration of a non-aqueous electrolyte is suppressed because the cyclic compound which has a sultone group is contained in a non-aqueous electrolyte.

It is also considered that the activation energy when lithium is solvated by oxygen of the sultone group decreases. The decomposition of the non-aqueous electrolyte is also suppressed by a decrease in activation energy when lithium solvates.

That is, the nonaqueous electrolyte contains a cyclic compound having a sultone group, so that the decomposition of the nonaqueous electrolyte is suppressed, and the cycle characteristics of the nonaqueous electrolyte secondary battery that progresses by the decomposition of the nonaqueous electrolyte are degraded. Is suppressed, and the nonaqueous electrolyte secondary battery has improved cycle characteristics.

When the amount of the cyclic compound having a sultone group is less than 2.0% by mass when the nonaqueous electrolytic solution is 100% by mass, the effect of suppressing the decomposition of the nonaqueous electrolytic solution is small, and the cyclic compound having a sultone group is 6 When the content is more than 0.0% by mass, the internal resistance of the nonaqueous electrolyte secondary battery increases. Therefore, when the nonaqueous electrolytic solution is 100% by mass, the cyclic compound having a sultone group is preferably contained in an amount of 2.0% by mass or more and 6.0% by mass or less.

Further, the nonaqueous electrolyte secondary battery includes a nonaqueous electrolyte solution containing 2.0% by mass or more and 6.0% by mass or less of a cyclic compound having a sultone group, when the nonaqueous electrolyte solution is 100% by mass, And a positive electrode current collector having a coating layer made of a conductive oxide in which at least one selected from F, Sb, Ta and P is added to tin. The non-aqueous electrolyte secondary battery having this combination has improved cycle characteristics when driven at a high voltage (4.3 V or higher).

(Second Embodiment)
<Nonaqueous electrolyte secondary battery>
A nonaqueous electrolyte secondary battery according to a second embodiment of the present invention is a nonaqueous electrolyte secondary battery having a current collector body and a coat layer made of a conductive oxide formed on the surface of the current collector body. A positive electrode for a non-aqueous electrolyte secondary battery having a positive electrode current collector; and a non-aqueous electrolyte containing LiBF ₄ (lithium tetrafluoroborate) as an electrolytic salt.

(Current collector for positive electrode of non-aqueous electrolyte secondary battery)
The description of the current collector body is the same as the description of the current collector body of the first embodiment.

The coating layer is formed on the surface of the current collector body and is made of a conductive oxide. Normally, when an aluminum foil is used as the current collector body, the passive film described in the first embodiment is formed on the surface of the aluminum foil. Since the passive film is a high-resistance film, an electrode using the current collector body having the passive film on the surface has a high resistance, and the output characteristics of a battery using the electrode deteriorate.

In the current collector for a nonaqueous electrolyte secondary battery positive electrode used in the second embodiment of the present invention, a coating layer made of a conductive oxide is formed on the surface of the current collector body in advance. Therefore, it is difficult to form the passive film. That is, this coat layer can suppress the formation of the high resistance layer on the surface of the current collector body. Further, since the contact between the electrolytic salt or the like and the current collector main body can be reduced by the coat layer, corrosion due to the electrolytic salt or the like of the current collector main body can be suppressed.

The coating layer is made of a conductive oxide. The conductive oxide is indium oxide added with at least one element selected from Zn, Mo, W, Ti, Zr, Sn and H, and tin oxide is selected from F, W, Ta, Sb, P and B Any one selected from the group consisting of zinc oxide added with at least one element selected from Ga, Al and B, and titanium oxide added with an Nb element. Since the coat layer is made of the above conductive oxide, it is resistant to oxygen, electrolytic solution and electrolytic salt in the atmosphere, and can withstand high voltage.

All of the above conductive oxides are metal oxides with other elements added. The element may be added alone or in the form of an oxide containing the element. The above conductive oxide has a charge transfer body that can move freely, that is, carriers due to the addition of elements to the metal oxide as a base material and the generation of oxygen vacancies in the structure of the metal oxide. Indicates. Therefore, the conductive oxide has a low specific resistance. Since the conductive oxide has a low specific resistance, the resistance of the electrode using the non-aqueous electrolyte secondary battery positive electrode current collector used in the second embodiment of the present invention does not substantially decrease. Therefore, the nonaqueous electrolyte secondary battery according to the second embodiment of the present invention can suppress a decrease in output characteristics.

The specific resistance of the conductive oxide can be changed by changing the ratio of the element to be added.

As the conductive oxide, the same conductive oxide as described in the first embodiment can be used. The description of the conductive oxide of the second embodiment is the same as that of the conductive oxide of the first embodiment.

Among those in which at least one element selected from Zn, Mo, W, Ti, Zr, Sn, and H is added to indium oxide used in the second embodiment, those in which Sn element or Zn element is added to indium oxide are preferable. . Indium tin oxide may be used as the indium oxide added with Sn element, and indium zinc oxide may be used as the indium oxide added with Zn element. In ₂ O ₃ —SnO ₂ (ITO) is preferable as the indium tin oxide, and In ₂ O ₃ —ZnO (IZO) is preferable as the indium zinc oxide.

ITO is a composite of indium oxide and tin oxide, and can take various crystal states depending on the film formation technique. By selecting the respective conditions such as the tin doping amount, film forming conditions, and heat treatment, the ITO film can be made a low resistance film. The ITO film is also characterized by a small specific resistance even when the film thickness is small. Therefore, the ratio of the coat layer using ITO to the current collector can be reduced.

IZO is a complex of indium oxide and zinc oxide and has an amorphous structure. In order to reduce the resistance of the crystalline material, heat treatment is performed to increase the crystallinity. On the other hand, when an aluminum foil is used for the current collector body, film stress occurs when film formation is performed at a high temperature and then returned to room temperature, which affects the flatness of the current collector body. As a result, when an active material or the like is applied to the current collector main body on which the coat layer is formed, the coating property is affected, leading to the deterioration of battery characteristics. Therefore, it is desirable to form the coat layer at room temperature as much as possible. Since IZO has a sufficiently low resistance even at room temperature, no special heat treatment is required. Moreover, since the film stress is small due to the characteristics, the influence on the battery characteristics is small.

Of the zinc oxide used in the second embodiment, at least one element selected from Ga, Al and B is added, and zinc oxide is preferably added with an Al element or Ga element. Aluminum zinc oxide can be cited as a material in which Al element is added to zinc oxide, and gallium zinc oxide can be cited as a material in which Ga element is added to zinc oxide. Aluminum-doped zinc oxide (AZO) is preferred as the aluminum zinc oxide, and gallium-doped zinc oxide (GZO) is preferred as the gallium zinc oxide.

AZO is a crystalline material, but it can have a sufficiently low resistance even by room temperature film formation. AZO can achieve low resistance even at room temperature, largely because of the physical properties of the material. AZO can adjust the specific resistance appropriately by optimizing the amount of Al added to zinc oxide without heat treatment. Is possible.

The conductive oxide is preferably GZO. In general, the resistance of GZO can be further reduced by room temperature film formation as compared with AZO.

The film thickness of the coat layer of the second embodiment is preferably 10 nm to 1 μm, and more preferably 20 nm to 800 nm. If the thickness of the coat layer is 10 nm or more, the surface of the current collector body can be protected and corrosion of the current collector body due to the electrolytic solution can be suppressed. If the thickness of the coat layer is 1 μm or less, the volume occupied by the current collector inside the battery can be made appropriate. If the volume occupied by the current collector in the battery becomes too large, the amount of active material and the like must be reduced, which leads to a decrease in battery capacity.

As a method for forming a coating layer on the current collector body, a sol-gel method, a pyrolysis spray method, a CVD method (Chemical Vapor Deposition method), a sputtering method, a vacuum deposition method, a coating method, or the like can be used. This coating layer forming method may be appropriately selected and used according to the material and shape of the current collector body and the type of conductive oxide forming the coating layer.

The current collector for a non-aqueous electrolyte secondary battery positive electrode used in the second embodiment of the present invention can be preferably manufactured by using the following manufacturing method.

(Method for producing current collector for positive electrode of non-aqueous electrolyte secondary battery)
The method for producing a current collector for a nonaqueous electrolyte secondary battery positive electrode according to the second embodiment includes a coat layer forming step of forming a coat layer made of a conductive oxide on the surface of the current collector by a sputtering method. Features.

In the coating layer forming step, the coating layer is formed by a sputtering method using a conductive oxide as a target. As the conductive oxide, the same oxide as described in the explanation of the current collector for the positive electrode of the nonaqueous electrolyte secondary battery can be used. Note that the specific resistance of the conductive oxide is preferably 1.0 × 10 ⁻⁴ Ωcm or more and 1.0 × 10 ⁻³ Ωcm or less.

The conductive oxide is preferably any one selected from ITO, IZO, AZO, and GZO.

(Positive electrode for non-aqueous electrolyte secondary battery)
A nonaqueous electrolyte secondary battery according to a second embodiment of the present invention has a positive electrode having the current collector for a nonaqueous electrolyte secondary battery positive electrode. The description about the positive electrode of the second embodiment is the same as the description of the positive electrode of the first embodiment.

(Non-aqueous electrolyte secondary battery)
The nonaqueous electrolyte secondary battery of the second embodiment of the present invention uses an electrolyte that uses LiBF ₄ as a negative electrode, a separator, and an electrolyte salt, in addition to the above-described positive electrode for a nonaqueous electrolyte secondary battery, as a battery component. .

The negative electrode and separator of the second embodiment can be the same as those of the first embodiment. The description of the negative electrode and separator of the second embodiment is the same as the description of the negative electrode and separator of the first embodiment.

As the electrolyte of the second embodiment, an electrolyte that can be used for a general non-aqueous electrolyte secondary battery can be used except that LiBF ₄ is used as an electrolyte salt. The electrolyte includes a solvent and an electrolytic salt dissolved in the solvent.

The solvent of the second embodiment can be the same as that of the first embodiment. The description of the solvent of the second embodiment is the same as the description of the solvent of the first embodiment.

As the electrolytic salt, LiBF ₄ is used. LiBF ₄ is less conductive than LiPF ₆ and is hydrophobic. Therefore, the reactivity with water is low and the hydrolysis resistance is excellent.

As the electrolyte, for example, a solution in which LiBF ₄ is dissolved at a concentration of about 0.5 mol / l to 1.7 mol / l in a solvent such as ethylene carbonate, dimethyl carbonate, propylene carbonate, and dimethyl carbonate can be used.

The nonaqueous electrolyte secondary battery of the second embodiment of the present invention has a positive electrode for a nonaqueous electrolyte secondary battery of the second embodiment and has an electrolyte having LiBF ₄ as an electrolytic salt. It has charge / discharge capacity and excellent cycle performance.

(Third embodiment)
Below, the positive electrode for nonaqueous electrolyte secondary batteries and the nonaqueous electrolyte secondary battery of the 3rd Embodiment of this invention are demonstrated.

The positive electrode for a nonaqueous electrolyte secondary battery according to the third embodiment of the present invention includes a current collector body, a first layer formed on the surface of the current collector body, and a second layer formed on the surface of the first layer. And the positive electrode for a nonaqueous electrolyte secondary battery having an active material layer formed on the surface of the second layer, the specific resistance of the first layer is lower than the specific resistance of the second layer, and the current collector body It is characterized by being higher than the specific resistance.

The current collector body refers to a chemically inert electronic high conductor that keeps current flowing through the electrode during discharge or charging of the nonaqueous electrolyte secondary battery. In the current collector for the nonaqueous electrolyte secondary battery positive electrode according to the third embodiment of the present invention, the first and second protective layers are formed on the surface of the current collector body. Can withstand corrosion of electrolytic salts and the like.

Examples of the material for the current collector main body include metal materials such as stainless steel, titanium, nickel, aluminum, copper, gold, tungsten, and molybdenum, or conductive resins. For reference, specific resistance values (μΩcm) of the above materials are as follows: stainless steel: 71 μΩcm, titanium: 43 μΩcm, nickel: 6 μΩcm, aluminum: 2.5 μΩcm, copper: 1.6 μΩcm, gold: 2 μΩcm, tungsten: 5 μΩcm, molybdenum : About 5 μΩcm.

The specific resistance value of the current collector body is not particularly limited, but the specific resistance value of the current collector body is preferably 1 μΩcm to 200 μΩcm, more preferably 1.5 μΩcm to 100 μΩcm.

The current collector body can take the form of a foil, a sheet, a film, a line, a bar, and the like. Therefore, for example, a metal foil such as a copper foil, a nickel foil, an aluminum foil, and a stainless steel foil can be suitably used as the current collector body. When the current collector body is in the form of foil, sheet or film, the thickness is preferably in the range of 10 μm to 100 μm.

The first layer is a protective layer formed on the surface of the current collector body. Therefore, as the protective layer, the first layer is preferably formed on the entire surface of the current collector body. However, in order to obtain the effect of the third embodiment of the present invention, the first layer may be formed on at least a part of the surface of the current collector body. In particular, the first layer is preferably formed at least between the second layer described later and the current collector body.

The specific resistance of the first layer is higher than the specific resistance of the current collector body used. The specific resistance value of the material of the first layer is preferably 1.5 μΩcm to 1 Ωcm, and more preferably 100 μΩcm to 0.01 Ωcm.

The material constituting the first layer has a specific resistance higher than the specific resistance of the current collector body to be used. The material constituting the first layer is a degenerate semiconductor, that is, a conductive metal oxide, a conductive metal nitride, a conductive metal carbide, or a conductive organic polymer obtained by adding (doping) another element to a metal oxide. Is preferred.

Examples of the metal oxide include indium oxide (In ₂ O ₃ ), zinc oxide (ZnO), zinc peroxide (ZnO ₂ ), tin oxide (II) (SnO), tin oxide (IV) (SnO ₂ ), and oxidation. Tin (VI) (SnO ₃ ), titanium dioxide (TiO ₂ ), dititanium trioxide (Ti ₂ O ₃ ), ruthenium oxide (RuO ₂ ), aluminum oxide (Al ₂ O ₃ ), nickel oxide (NiO), oxide Examples include tantalum (Ta ₂ O ₃ ), tungsten oxide (III) (W ₂ O ₃ ), tungsten oxide (IV) (WO ₂ ), tungsten oxide (VI) (WO ₃ ), and chromium oxide (Cr ₂ O ₃ ). it can.

When other elements added to the metal oxide are added (dope) to the metal oxide, the specific resistance of the compound after addition is lower than that of the compound before addition. Examples of the other elements include Zn, Mo, W, Ti, Zr, Sn, H, F, Ta, Sb, P, B, Ga, Al, and Nb.

Conductive metal oxide, conductive metal nitride, or conductive metal carbide has higher specific resistance than the current collector body used. Specific examples of the conductive metal oxide include indium oxide added with at least one element selected from Zn, Mo, W, Ti, Zr, Sn and H, tin oxide with F, W, Ta, Sb, Examples include those obtained by adding at least one element selected from P and B, those obtained by adding at least one element selected from Ga, Al and B to zinc oxide, and those obtained by adding Nb element to titanium oxide. Specific examples of the conductive metal nitride include titanium nitride (TiN), zirconium nitride (ZrN), hafnium nitride (HfN), tantalum nitride (TaN), niobium nitride (NbN), vanadium nitride (VN), and tungsten nitride ( WN). Specific examples of the conductive metal carbide include titanium carbide (TiC), molybdenum carbide (MoC), tungsten carbide (WC), tantalum carbide (TaC), niobium carbide (NbC), vanadium carbide (VC), and zirconium carbide (ZrC). Can be illustrated.

In the conductive metal oxide, other elements are added to the base metal oxide, or oxygen vacancies are generated in the structure of the metal oxide due to the addition of other elements. , Showing conductivity. By changing the ratio of other elements to be added, the specific resistance of the conductive metal oxide changes. In the conductive metal oxide of the present invention, other elements may be added to the metal oxide at an appropriate ratio as appropriate so as to exhibit a specific resistance within the scope of the present invention.

Among those in which at least one element selected from Ga, Al, and B is added to zinc oxide, gallium zinc oxide can be cited as an example in which Ga element is added to zinc oxide, and Al element is added to zinc oxide. And aluminum zinc oxide, and boron zinc oxide may be mentioned as the element in which element B is added to zinc oxide. Gallium-doped zinc oxide (GZO) is preferred as the gallium zinc oxide, aluminum-doped zinc oxide (AZO) is preferred as the aluminum zinc oxide, and boron-doped zinc oxide (BZO) is preferred as the boron zinc oxide.

In general, for example, IZO is a material in which 90% by mass of indium oxide is added with 10% by mass of zinc oxide and has an amorphous structure, and ITO is generally 90% by mass. In the present specification, it means that 10% by mass of tin oxide is added to indium oxide. Unless otherwise specified, indium zinc oxide, aluminum zinc oxide, boron zinc oxide, indium tin oxide, When expressed as gallium zinc oxide, fluorine tin oxide, antimony tin oxide, or titanium niobium oxide, the mixing ratio of the metal element in each oxide is not limited.

Generally, when the resistance of a crystalline material is to be lowered, a heat treatment is performed to increase the crystallinity. Here, when an aluminum foil is used for the current collector body, if the first layer is formed at a high temperature, film stress is generated when the temperature is returned to room temperature, which affects the flatness of the current collector body. . As a result, when the second layer and the active material layer are applied to the current collector body on which the first layer is formed, the battery characteristics may be impaired. For this reason, it is desirable to form the first layer as much as possible at room temperature.

IZO is advantageous because it exhibits a sufficiently low resistance even in film formation at room temperature and does not require special heat treatment. Furthermore, since IZO has a characteristic that the film stress is small, it is advantageous in that it has little influence on battery characteristics.

AZO is a crystalline material and exhibits sufficiently low resistance even at room temperature. GZO is a film formed at room temperature and exhibits a lower resistance than AZO.

The band gap indicated by the material of the first layer is preferably 7 eV or less, and more preferably 1 eV to 4 eV.

The thickness of the first layer is preferably 10 nm to 1 μm, more preferably 20 nm to 500 nm, and even more preferably 50 nm to 200 nm.

Examples of the method for forming the first layer on the surface of the current collector body include a sol-gel method, a pyrolysis spray method, a CVD method (Chemical Vapor Deposition method), a sputtering method, a vacuum deposition method, and a coating method. This first layer forming method may be appropriately selected and used according to the material and shape of the current collector body and the type of material constituting the first layer.

The second layer is a protective layer for the current collector body formed on the surface of the first layer. In the present invention, the current collector body is protected by the two protective layers, so that the current collector body is more stable than the protection by only one protective layer. Then, on the surface of the current collector body, a first layer having a specific resistance larger than that of the current collector body and a second layer having a specific resistance larger than that of the first layer are sequentially formed, as described above. The resistance of the positive electrode obtained is low. For this reason, the second layer is preferably formed on the entire surface of the first layer. However, in order to obtain the effects of the present invention, the second layer may be formed on at least a part of the surface of the first layer.

The specific resistance of the second layer is higher than the specific resistance of the first layer used. The resistivity of the material of the second layer, preferably 100μΩcm ~ 10 ⁸ Ωcm, and more preferably further 10,000μΩcm ~ 10 ⁸ Ωcm.

The closer the electrochemical properties of the material constituting the first layer and the second layer are, the better. It is preferable that the material of both layers has the same band gap. The band gap exhibited by the material of the second layer is preferably 7 eV or less, and more preferably 1 eV to 4 eV.

Also, since the second layer is in direct contact with the active material and the electrolytic solution, the material of the second layer is preferably a material having a lower carrier density than the material of the first layer. By selecting a material having a low carrier density, the decomposition reaction caused by the active material and the electrolytic solution can be suppressed.

The material constituting the second layer has a specific resistance higher than that of the first layer to be used. The material constituting the second layer is preferably a metal oxide, metal nitride, or metal carbide.

Specific examples of the material constituting the second layer include indium oxide (In ₂ O ₃ ), zinc oxide (ZnO), tin oxide (IV) (SnO ₂ ), titanium dioxide (TiO ₂ ), dititanium trioxide ( Ti ₂ O ₃ ), ruthenium oxide (RuO ₂ ), aluminum oxide (Al ₂ O ₃ ), tantalum oxide (Ta ₂ O ₃ ), tungsten oxide (III) (W ₂ O ₃ ), tungsten oxide (IV) (WO ₂ ), tungsten oxide (VI) (WO ₃ ), chromium oxide (Cr ₂ O ₃ ), aluminum nitride (AlN), and silicon carbide (SiC).

The film thickness of the second layer is preferably 10 nm to 1 μm, more preferably 20 nm to 500 nm, and even more preferably 50 nm to 200 nm.

The combination of the first layer and the second layer only needs to satisfy the condition that the specific resistance of the first layer is lower than the specific resistance of the second layer. As a combination of the first layer and the second layer, if the first layer is a conductive metal oxide, the second layer is a metal oxide, and if the first layer is a conductive metal nitride, the second layer is a metal nitride. If the first layer is a conductive metal carbide, the second layer is preferably a metal carbide.

The total thickness of the first layer and the second layer is preferably 20 nm to 2 μm, more preferably 40 nm to 1 μm, and even more preferably 100 nm to 500 nm.

Examples of the method for forming the second layer on the surface of the first layer include a sol-gel method, a pyrolysis spray method, a CVD method (Chemical Vapor Deposition method), a sputtering method, a vacuum deposition method, and a coating method. This second layer forming method may be appropriately selected and used according to the material and shape of the current collector main body and the first layer, and the type of material constituting the second layer.

The active material contained in the positive electrode active material layer may be any material that can occlude and release lithium ions, for example, in the case of a positive electrode active material for a lithium secondary battery. As an active material of the positive electrode for the lithium secondary battery, cobalt composite oxide such as LiCoO ₂ , manganese composite oxide such as LiMn ₂ O ₄ and Li ₂ MnO ₃ , nickel composite oxide such as LiNiO ₂ , LiFePO ₄ , LiFeVO ₄ , iron complex oxides, Li (Ni, Co) O ₂ , Li (Ni, Mn) O ₂ , Li (Co, Mg) O ₂ , Li (Ni, Co, Mn) O ₂ , Li Examples thereof include composite oxides such as (Ni, Co, Al) O ₂ , Li (Co, Mg, Al) O ₂ , and Li (Ni, Co, Mn, Al) O ₂ . These materials may be used as a mixture.

In particular, the active material of the positive electrode has the general formula:
LiCo _p Ni _q Mn _r D _S O ₂ (D is selected from Al, Mg, Ti, Sn, Zn, W, Zr, Mo, Fe, Na, p + q + r + s = 1, 0 ≦ p ≦ 1, 0 ≦ q ≦ It is preferable to include a composite metal oxide represented by 1, 0 ≦ r ≦ 1, 0 ≦ s <1). Here, the above-mentioned p, q, and r can be in the ranges of 0 <p <1, 0 <q <1, and 0 <r <1, respectively.

Since this composite metal oxide is excellent in thermal stability and low in cost, a non-aqueous electrolyte secondary battery including the composite metal oxide can be excellent in thermal stability and inexpensive.

As the above composite metal oxide, LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ , Li _1.0 Ni _0.6 Co _0.2 Mn _0.2 O ₂ , Li _1.0 Ni _0.5 Co Examples include _0.2 Mn _0.3 O ₂ , LiCoO ₂ , and LiNi _0.8 Co _0.2 O ₂ .

The active material layer may contain a conductive aid. The same conductive assistant as that in the first embodiment can be used. The description of the conductive auxiliary agent of the third embodiment is the same as the description of the conductive auxiliary agent of the first embodiment.

The active material layer may contain a binder. The binder serves to bind the active material and the conductive additive to the surface of the second layer. Examples of the binder include fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber, thermoplastic resins such as polypropylene and polyethylene, imide resins such as polyimide and polyamideimide, and alkoxysilyl group-containing resins. be able to.

As a method for forming the active material layer on the surface of the second layer, a conventionally known method such as a roll coating method, a dip coating method, a doctor blade method, a spray coating method, or a curtain coating method is used. An active material may be applied to the surface. Specifically, an active material layer-forming composition containing an active material and, if necessary, a binder and a conductive aid is prepared, and an appropriate solvent is added to the composition to form a paste. After coating on the surface of the two layers, it is dried. If necessary, the dried product may be compressed to increase the electrode density.

Examples of the solvent include N-methyl-2-pyrrolidone (NMP), methanol, and methyl isobutyl ketone (MIBK).

FIG. 3 is a schematic diagram for explaining a positive electrode for a nonaqueous electrolyte secondary battery according to a third embodiment of the present invention. As shown in FIG. 3, the first layer 21 is formed on the surface of the current collector 10, the second layer 22 is formed on the surface of the first layer 21, and the active material layer 31 is formed on the surface of the second layer 22. Thus, the positive electrode 50 for a non-aqueous electrolyte secondary battery is obtained.

The nonaqueous electrolyte secondary battery according to the third embodiment of the present invention has the positive electrode for a nonaqueous electrolyte secondary battery according to the third embodiment. The nonaqueous electrolyte secondary battery having the positive electrode for a nonaqueous electrolyte secondary battery according to the third embodiment can exhibit a good capacity retention rate even under high potential driving conditions. Therefore, the nonaqueous electrolyte secondary battery according to the third embodiment of the present invention has a large charge / discharge capacity and excellent cycle performance.

Here, the high potential driving condition means that the operating potential of lithium ions with respect to lithium metal is 4.3 V or more, and further 4.5 to 5.5 V. When the non-aqueous electrolyte secondary battery according to the third embodiment of the present invention is used, the charging potential of the positive electrode for the non-aqueous electrolyte secondary battery is 4.3 V or higher, further 4.5 V to 5.V. 5V can be set. Note that, under the driving conditions of a general lithium ion secondary battery, the operating potential of lithium ions with respect to lithium metal is less than 4.3V.

The nonaqueous electrolyte secondary battery according to the third embodiment of the present invention includes a negative electrode, a separator, and an electrolyte in addition to the above-described positive electrode for a nonaqueous electrolyte secondary battery as battery components. The negative electrode, separator, and electrolyte solution of the third embodiment can be the same as those of the first embodiment. The description of the negative electrode, separator, and electrolytic solution of the third embodiment is the same as the description of the negative electrode, separator, and electrolytic solution of the first embodiment.

(Fourth embodiment)
A current collector for a nonaqueous electrolyte secondary battery positive electrode according to a fourth embodiment of the present invention includes a current collector body and a coating layer containing a metal oxide or metal nitride for a nonaqueous electrolyte secondary battery positive electrode current collector. The electric body is characterized by having a high resistance metal between the current collector body and the coating layer.

The current collector body refers to a chemically inert electronic high conductor that keeps current flowing through the electrode during discharge or charging of the nonaqueous electrolyte secondary battery. In the current collector for a non-aqueous electrolyte secondary battery positive electrode according to the present invention, a coating layer containing a metal oxide or a metal nitride is formed as a protective layer for the current collector body. Can withstand corrosion.

As a material of the current collector body, at least one selected from silver, copper, gold, aluminum, magnesium, tungsten, cobalt, zinc, nickel, iron, platinum, tin, indium, titanium, ruthenium, tantalum, chromium, molybdenum, In addition, metal materials such as stainless steel can be exemplified. For reference, some of the specific resistance values (μΩcm) of the above materials are shown: silver: 1.5 μΩcm, copper: 1.6 μΩcm, gold: 2 μΩcm, aluminum: 2.5 μΩcm, magnesium 4 μΩcm, tungsten: 5 μΩcm, cobalt: 6 μΩcm, zinc: 6 μΩcm, nickel: 6 μΩcm, iron: 9 μΩcm, platinum: 10 μΩcm, tin: 11 μΩcm, indium: 5 μΩcm, titanium: 43 μΩcm, tantalum: 12 μΩcm, chromium: 13 μΩcm, molybdenum: 5 μΩcm, stainless steel: 71 μΩcm.

The specific resistance value of the current collector body is preferably 1.5 μΩcm to 150 μΩcm, and more preferably 1.5 μΩcm to 100 μΩcm.

The current collector body can take the form of foil, sheet, film, wire, rod, or the like. Therefore, for example, a metal foil such as a copper foil, a nickel foil, an aluminum foil, and a stainless steel foil can be suitably used as the current collector body. When the current collector body is in the form of foil, sheet or film, the thickness is preferably in the range of 10 μm to 100 μm.

In the current collector for the nonaqueous electrolyte secondary battery positive electrode according to the fourth embodiment of the present invention, the high-resistance metal exists between the current collector body and the coating layer. As long as this condition is satisfied, the existence form of the high-resistance metal is not particularly limited. For example, the high-resistance metal may be present in layers on the entire surface or part of the current collector body, or may be scattered on the entire surface or part of the current collector body. The thickness in the case where the high resistance metal is present in layers or the thickness in the case where the high resistance metal is scattered is preferably 10 nm to 1 μm, more preferably 20 nm to 500 nm, and even more preferably 50 nm to 200 nm.

Examples of the high resistance metal are the same as those described in the current collector body except for silver having the lowest specific resistance. The specific resistance value of the high resistance metal only needs to be higher than that of the current collector body. The specific resistance value of the high resistance metal is preferably 1.6 μΩcm to 200 μΩcm, and more preferably 1.6 μΩcm to 150 μΩcm.

The coating layer in the fourth embodiment of the present invention contains a metal oxide or a metal nitride. The current collector for a nonaqueous electrolyte secondary battery positive electrode according to the fourth embodiment of the present invention has a coating layer containing a metal oxide or metal nitride, and therefore exhibits corrosion resistance, and the current collector main body is extremely corroded. Hateful.

Examples of the metal oxide include indium oxide (In ₂ O ₃ ), zinc oxide (ZnO), zinc peroxide (ZnO ₂ ), tin oxide (II) (SnO), tin oxide (IV) (SnO ₂ ), and tin oxide. (VI) (SnO ₃ ), titanium dioxide (TiO ₂ ), dititanium trioxide (Ti ₂ O ₃ ), ruthenium oxide (RuO ₂ ), aluminum oxide (Al ₂ O ₃ ), nickel oxide (NiO), tantalum oxide (Ta ₂ O ₃ ), tungsten oxide (III) (W ₂ O ₃ ), tungsten oxide (IV) (WO ₂ ), tungsten oxide (VI) (WO ₃ ), chromium oxide (Cr ₂ O ₃ ), magnesium oxide (MgO), cobalt oxide (II) (CoO), cobalt oxide (III) (Co ₂ O ₃ ), tricobalt tetroxide (Co ₃ O ₄ ), iron oxide (II) (FeO), iron oxide (III) _(Fe 2 _{O 3} , Triiron tetraoxide _(Fe 3 _{O 4)} is exemplified.

Examples of the metal nitride include aluminum nitride (AlN), titanium nitride (TiN), copper nitride (Cu ₃ N ₂ ), magnesium nitride (Mg ₃ N ₂ ), tungsten nitride (WN), cobalt nitride (Co ₃ N), Zinc nitride (Zn ₃ N ₂ ), nickel nitride (Ni ₃ N), iron nitride (FeN), tin nitride (Sn ₃ N ₂ ), indium nitride (InN), ruthenium nitride (Ru ₃ N ₄ ), tantalum nitride ( Examples are TaN) and chromium nitride (CrN).

The material constituting the coating layer may be a degenerate semiconductor, that is, a metal oxide obtained by adding (doping) another element. Specific examples of the metal oxide in this case can include those listed above. Examples of the element added to the metal oxide include Zn, Mo, W, Ti, Zr, Sn, H, F, Ta, Sb, P, B, Ga, Al, and Nb. As the degenerate semiconductor, indium oxide added with at least one element selected from Zn, Mo, W, Ti, Zr, Sn, and H, tin oxide from F, W, Ta, Sb, B, and P Those obtained by adding at least one selected element, those obtained by adding at least one element selected from Ga, Al and B to zinc oxide, and those obtained by adding Nb element to titanium oxide are preferred.

Generally, when the resistance of a crystalline material is to be lowered, a heat treatment is performed to increase the crystallinity. Here, when an aluminum foil is used for the current collector body, if an attempt is made to form a coating layer at a high temperature, film stress is generated when the temperature is returned to room temperature, which affects the flatness of the current collector body. As a result, when the active material layer is applied to the current collector body on which the coating layer is formed, there is a possibility that battery characteristics may be impaired. For this reason, it is desirable to form the coating layer at room temperature as much as possible.

In this regard, IZO is advantageous because it exhibits a sufficiently low resistance even at room temperature film formation and does not require any special heat treatment. Furthermore, since IZO has a characteristic that the film stress is small, it is advantageous in that it has little influence on battery characteristics. AZO is a crystalline material and exhibits sufficiently low resistance even at room temperature. GZO exhibits a lower resistance than AZO in film formation at room temperature.

The specific resistance value of the material of the coating layer is preferably 10 μΩcm to 10 ⁸ Ωcm, and more preferably 10 μΩcm to 10 ⁶ Ωcm.

The coating layer is a current collector body and a protective layer of high resistance metal. The coating layer may be formed on at least a part of the surface of the high resistance metal. It is assumed that the coating layer is formed on a part or the whole of the surface of the high-resistance metal, or formed on a part or the whole of the exposed surface of the current collector body and the surface of the high-resistance metal. Is done. In particular, the coating layer is preferably formed on the entire surface of the high-resistance metal, or formed on the entire surface of the current collector body and the entire surface of the high-resistance metal.

The film thickness of the coating layer is preferably 10 nm to 1 μm, more preferably 20 nm to 500 nm, and even more preferably 50 nm to 200 nm.

Regarding the combination of the material constituting the high-resistance metal and the coating layer, it is preferable that the electrochemical properties (specific resistance values) of the two are close from the viewpoint of reducing the Schottky barrier generated at these interfaces. Furthermore, it is particularly preferable that the high resistance metal and the metal element of the material constituting the coating layer are the same. When both metals are the same, the efficient continuous manufacturing method can be provided so that it may mention later. According to this manufacturing method, it is possible to prevent formation of a clear interface between the high-resistance metal and the coating layer, so that a significant reduction in the Schottky barrier can be achieved.

A manufacturing method of a current collector for a nonaqueous electrolyte secondary battery positive electrode according to a fourth embodiment of the present invention is a coating process for coating a high resistance metal on the surface of a current collector body, and a high resistance metal obtained in the coating process. A coating step of coating the surface of the current collector body coated with metal oxide or metal nitride.

Examples of the coating process include a sputtering method and a coating method. These methods may be appropriately selected and used according to the material and shape of the current collector body and the type of the high resistance metal.

Examples of the coating process include a sol-gel method, a pyrolysis spray method, a CVD method (Chemical Vapor Deposition method), a sputtering method, a vacuum deposition method, and a coating method. These methods may be appropriately selected and used according to the material and shape of the current collector body and the high resistance metal.

The coating step is preferably performed by sputtering a metal in an oxygen or nitrogen atmosphere. For example, when a metal is sputtered in an oxygen atmosphere, the metal and the metal react to form a metal oxide coating layer.

When manufacturing a current collector for a positive electrode of a non-aqueous electrolyte secondary battery in which the high resistance metal and the metal element of the material constituting the coating layer are manufactured, the coating process is performed by sputtering the metal under an argon gas atmosphere. It is preferable that the coating process is performed by sputtering the same metal as that used in the coating process in an oxygen or nitrogen atmosphere. In particular, it is preferable that the coating process and the coating process are made continuous by introducing oxygen or nitrogen into the sputtering apparatus immediately before the coating process is completed. The continuous manufacturing method is advantageous in terms of efficiency from the viewpoint of the manufacturing process. Moreover, in the obtained current collector, it is substantially possible to prevent the formation of a clear interface between the high-resistance metal and the coating layer, so that a low-resistance current collector can be obtained. Further advantageous.

The current collector for a nonaqueous electrolyte secondary battery positive electrode according to the fourth embodiment of the present invention can be used as a positive electrode for a nonaqueous electrolyte secondary battery by forming an active material layer on the surface thereof.

The active material contained in the positive electrode active material layer of the fourth embodiment can be the same as the active material described in the third embodiment. The description of the positive electrode active material in the fourth embodiment is the same as the description of the positive electrode active material described in the third embodiment.

The active material layer may contain a conductive aid. The conductive assistant is added to increase the conductivity of the electrode. The same thing as the conductive support agent described in 1st Embodiment can be used for the conductive support agent of 4th Embodiment. The description of the conductive auxiliary agent of the fourth embodiment is the same as the description of the conductive auxiliary agent of the first embodiment.

The active material layer may contain a binder. The binder serves to bind the active material and the conductive additive to the surface of the second layer. As the binder of the fourth embodiment, the same binder as exemplified in the third embodiment can be used. The description of the binder of the fourth embodiment is the same as the description of the binder of the third embodiment.

As a method for forming an active material layer on the surface of the current collector for a nonaqueous electrolyte secondary battery positive electrode according to the fourth embodiment of the present invention, a roll coating method, a dip coating method, a doctor blade method, a spray coating method, a curtain The active material may be applied to the surface of the current collector using a conventionally known method such as a coating method. Specifically, an active material layer-forming composition containing an active material and, if necessary, a binder and a conductive aid is prepared, and an appropriate solvent is added to the composition to make a paste, and then the collection is performed. After applying to the surface of the electric body, it is dried. If necessary, the dried product may be compressed to increase the electrode density.

The current collector for a nonaqueous electrolyte secondary battery positive electrode according to the fourth embodiment of the present invention has a coating layer containing a metal oxide or metal nitride, and therefore exhibits corrosion resistance, and the current collector main body is extremely corroded. Hateful. Moreover, since the non-aqueous electrolyte secondary battery positive electrode current collector according to the fourth embodiment of the present invention exhibits low resistance, the electron mobility does not decrease greatly. As a result of these, the non-aqueous electrolyte secondary battery using the non-aqueous electrolyte secondary battery positive electrode current collector of the fourth embodiment of the present invention exhibits low resistance and good capacity even under high-potential driving conditions. The maintenance rate can be shown. Therefore, the nonaqueous electrolyte secondary battery according to the fourth embodiment of the present invention has a large charge / discharge capacity and excellent cycle performance. Here, the high potential driving condition means that the operating potential of lithium ions with respect to lithium metal is 4.3 V or more, and further 4.5 to 5.5 V. When the non-aqueous electrolyte secondary battery according to the fourth embodiment of the present invention is used, the charging potential of the positive electrode can be set to 4.3 V or higher, further 4.5 V to 5.5 V on the basis of lithium. Note that, under the driving conditions of a general lithium ion secondary battery, the operating potential of lithium ions with respect to lithium metal is less than 4.3V.

The nonaqueous electrolyte secondary battery according to the fourth embodiment of the present invention includes a negative electrode, a separator, and an electrolytic solution as a battery component in addition to the positive electrode having the above-described current collector. The negative electrode, separator, and electrolyte solution of the fourth embodiment can be the same as those of the first embodiment. The description of the negative electrode, separator, and electrolytic solution of the fourth embodiment is the same as that of the negative electrode, separator, and electrolytic solution of the first embodiment.

The nonaqueous electrolyte secondary batteries of the first to fourth embodiments of the present invention are not particularly limited in shape, and various shapes such as a cylindrical shape, a stacked shape, and a coin shape can be adopted. Regardless of the shape, a separator is sandwiched between the positive electrode and the negative electrode to form an electrode body, and the space between the positive electrode current collector and the negative electrode current collector to the positive electrode terminal and the negative electrode terminal is used for current collection. After connecting using a lead or the like, the electrode body is sealed in a battery case together with an electrolytic solution to form a battery.

The nonaqueous electrolyte secondary batteries of the first to fourth embodiments can be mounted on a vehicle. The vehicle can be equipped with a non-aqueous electrolyte secondary battery having a high capacity and a high energy density, and can be a high-performance vehicle. The vehicle may be a vehicle that uses electric energy from a battery as a whole or a part of a power source. For example, an electric vehicle, a hybrid vehicle, a plug-in hybrid vehicle, a hybrid railway vehicle, a forklift, an electric wheelchair, an electric assist. Bicycles and electric motorcycles are examples.

As described above, the embodiments of the current collector for the nonaqueous electrolyte secondary battery positive electrode of the present invention, the manufacturing method thereof, the positive electrode for the nonaqueous electrolyte secondary battery and the nonaqueous electrolyte secondary battery have been described. It is not limited to the embodiment. The present invention can be implemented in various forms without departing from the gist of the present invention, with modifications and improvements that can be made by those skilled in the art.

Hereinafter, the present invention will be described in more detail with reference to examples.

(Examples 1 to 7 and Comparative Examples 1 to 7)
<Formation of coat layer on current collector>
An aluminum foil having a thickness of 20 μm was prepared as a current collector. As the coating layer material, IZO, AZO, ITO, zinc sulfide (ZnS), TiN, ATO, PTO, AlN, SnO ₂ were prepared.

(Current collector 1)
The aluminum foil was put in a sputtering apparatus, and IZO was sputtered on the surface thereof to form a 100 nm-thick IZO coating layer. This is the current collector 1.

(Current collector 2)
The aluminum foil was put into a sputtering apparatus, and AZO was sputtered on the surface to form an AZO coating layer having a thickness of 100 nm. This is the current collector 2.

(Current collector 3)
The aluminum foil was put into a sputtering apparatus, and ITO was sputtered on the surface to form an ITO coat layer having a thickness of 100 nm. This is the current collector 3.

(Current collector 4)
The aluminum foil was put in a sputtering apparatus, and ZnS was sputtered on the surface thereof to form a ZnS coat layer having a thickness of 100 nm. This is the current collector 4.

(Current collector 5)
The aluminum foil is used as the current collector 5.

(Current collector 6)
The aluminum foil was put in a sputtering apparatus, and TiN was sputtered on the surface to form a 100 nm-thick TiN coat layer. This is the current collector 6.

(Current collector 7)
The aluminum foil was put into a sputtering apparatus, and ATO was sputtered on the surface thereof to form an ATO coating layer having a thickness of 100 nm. This is the current collector 7.

(Current collector 8)
The aluminum foil was put in a sputtering apparatus, and PTO was sputtered on the surface thereof to form a PTO coating layer having a thickness of 100 nm. This is the current collector 8.

(Current collector 9)
The aluminum foil was put into a sputtering apparatus, and AlN was sputtered on the surface thereof to form an AlN coat layer having a thickness of 100 nm. This is the current collector 9.

(Current collector 10)
The aluminum foil was put into a sputtering apparatus, and SnO ₂ was sputtered on the surface thereof to form a SnO ₂ coating layer having a thickness of 100 nm. This is the current collector 10.

<Specific resistance measurement>
In order to measure the specific resistance values of the current collectors 1 to 4 and 6 to 10, a 100 nm coat layer was formed on the glass in the same manner as the current collectors 1 to 4 and 6 to 10, and each coat layer The specific resistance value was measured by the four-end needle method. The specific resistance value of the coat layer of the current collector 1 is 8 × 10 ⁻⁴ Ωcm, the specific resistance value of the coat layer of the current collector 2 is 3 × 10 ⁻³ Ωcm, and the specific resistance value of the coat layer of the current collector 3 is 1 × 10 ⁻² Ωcm, the specific resistance value of the coat layer of the current collector 4 is 1 × 10 ⁸ Ωcm or more, and the specific resistance value of the coat layer of the current collector 6 is 5 × 10 ⁻³ Ωcm, The specific resistance value of the coat layer is 7 × 10 ⁻³ Ωcm, the specific resistance value of the coat layer of the current collector 8 is 3 × 10 ⁻³ Ωcm, and the specific resistance value of the coat layer of the current collector 9 is 1 × 10 ⁸ Ωcm. As described above, the specific resistance value of the coat layer of the current collector 10 was 1 Ωcm.

<Production of laminated lithium-ion secondary battery>
Example 1
A laminate type lithium ion secondary battery of Example 1 using the current collector 1 as a positive electrode current collector was produced as follows. First, LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ as a positive electrode active material, acetylene black as a conductive additive, 88 parts by mass and 6 parts by mass, respectively, and polyvinylidene fluoride (PVDF) 6 as a binder A slurry was prepared by mixing the mixture with parts by mass and dispersing the mixture in an appropriate amount of N-methyl-2-pyrrolidone (NMP).

The slurry was placed on the current collector 1 and applied to the current collector 1 using a doctor blade so that the slurry became a film. The positive electrode active material layer was formed on the surface of the current collector 1 by drying the current collector 1 coated with the slurry at 80 ° C. for 20 minutes and removing NMP by volatilization. Thereafter, the current collector 1 and the positive electrode active material layer on the current collector 1 were firmly bonded to each other by a roll press. Here, the electrode density of the positive electrode was set to 2.3 g / cm ³ . The bonded product was heated with a vacuum dryer at 120 ° C. for 6 hours, cut into a predetermined shape (rectangular shape of 25 mm × 30 mm), and the positive electrode 1 having a thickness of about 50 μm was obtained.

The negative electrode was produced as follows. A mixture of 97 parts by weight of graphite powder, 1 part by weight of acetylene black as a conductive additive, 1 part by weight of styrene-butadiene rubber (SBR) and 1 part by weight of carboxymethylcellulose (CMC) as a binder was obtained. A slurry was prepared by dispersing in an appropriate amount of ion-exchanged water. This slurry was applied to a copper foil having a thickness of 20 μm, which is a negative electrode current collector, in a film shape using a doctor blade. The current collector coated with the slurry was dried to remove the ion exchange water, thereby forming a negative electrode active material layer on the surface of the current collector. Thereafter, the current collector and the negative electrode active material layer on the current collector were tightly bonded by a roll press. The electrode density of the negative electrode was 1.4 g / cm ³ . The joined product of the negative electrode active material layer was heated in a vacuum dryer at 120 ° C. for 6 hours, cut into a predetermined shape (25 mm × 30 mm rectangular shape), and formed into a negative electrode having a thickness of about 45 μm.

A laminate type lithium ion secondary battery was manufactured using the positive electrode 1 and the negative electrode. Specifically, a rectangular sheet (27 × 32 mm, thickness 25 μm) made of polypropylene resin as a separator was sandwiched between the positive electrode 1 and the negative electrode to form an electrode plate group. The electrode plate group was covered with a set of two laminated films, and the three sides were sealed, and then an electrolyte solution was injected into the bag-like laminated film. As an electrolytic solution, a solution obtained by dissolving LiPF ₆ at 1 mol / l in a solvent obtained by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) at EC: DEC = 3: 7 (volume ratio) was used. Thereafter, the remaining one side was sealed to obtain a laminate type lithium ion secondary battery in which the four sides were hermetically sealed and the electrode plate group and the electrolyte were sealed. Note that the positive electrode and the negative electrode each have a tab that can be electrically connected to the outside, and a part of the tab extends to the outside of the laminated lithium ion secondary battery. The laminated lithium ion secondary battery of Example 1 was produced through the above steps.

(Example 2)
A laminated lithium ion secondary battery of Example 2 was produced in the same manner as in Example 1 except that the current collector 2 was used instead of the current collector 1 in Example 1.

(Comparative Example 1)
A laminated lithium ion secondary battery of Comparative Example 1 was produced in the same manner as in Example 1 except that the current collector 5 was used instead of the current collector 1 in Example 1.

(Comparative Example 2)
A laminated lithium ion secondary battery of Comparative Example 2 was produced in the same manner as in Example 1 except that the current collector 3 was used instead of the current collector 1 in Example 1.

(Comparative Example 3)
A laminated lithium ion secondary battery of Comparative Example 3 was produced in the same manner as in Example 1 except that the current collector 4 was used instead of the current collector 1 in Example 1.

(Example 3)
LiNi _0.5 Co _0.2 Mn _0.3 O ₂ is used as the positive electrode active material, the current collector 6 is used instead of the current collector 1, the negative electrode thickness is about 60 μm, and the positive electrode thickness is about 50 μm. As in Example 1, except that the density was about 3.0 g / cm ^{3 and} the P / N ratio in Example 1 was 1.8, whereas the P / N ratio was 1.3. Thus, a laminate type lithium ion secondary battery of Example 3 was produced.

(Example 4)
A laminated lithium ion secondary battery of Example 4 was produced in the same manner as Example 3 except that the current collector 7 was used instead of the current collector 6.

(Example 5)
A laminated lithium ion secondary battery of Example 5 was produced in the same manner as Example 3 except that the current collector 8 was used instead of the current collector 6.

(Comparative Example 4)
A laminated lithium ion secondary battery of Comparative Example 4 was produced in the same manner as in Example 3 except that the current collector 5 was used instead of the current collector 6.

(Comparative Example 5)
A laminated lithium ion secondary battery of Comparative Example 5 was produced in the same manner as in Example 3 except that the current collector 9 was used instead of the current collector 6.

(Comparative Example 6)
A laminated lithium ion secondary battery of Comparative Example 6 was produced in the same manner as in Example 3 except that the current collector 10 was used instead of the current collector 6.

Example 6
A laminated lithium ion secondary battery of Example 6 was produced in the same manner as in Example 3 except that the current collector 1 was used instead of the current collector 6.

(Example 7)
A laminated lithium ion secondary battery of Example 7 was produced in the same manner as in Example 4 except that 4% by mass of 1,3-propane sultone was added to the electrolytic solution when the total amount of the electrolytic solution was 100% by mass.

(Comparative Example 7)
A laminated lithium ion secondary battery of Comparative Example 7 was produced in the same manner as Comparative Example 4 except that 4% by mass of 1,3-propane sultone was added to the electrolytic solution when the total amount of the electrolytic solution was 100% by mass.

<Initial capacity measurement>
The initial capacities of the laminated lithium ion secondary batteries of Example 1, Example 2, and Comparative Example 1 were measured. Charging was CCCV charging (constant current constant voltage charging) at a 1C rate and a voltage of 4.5 V at 25 ° C. The voltage was held for 1 hour. The discharge was a CC discharge (constant current discharge) at a voltage of 3.0 V and a 1 C rate. The discharge capacity was measured and the results are shown in Table 1.

As seen in Table 1, the initial discharge capacities of Examples 1 and 2 were 4% and 9% larger than those of Comparative Example 1, respectively. There is no difference between the laminated lithium ion secondary batteries of Comparative Example 1 and Example 1 and Example 2 except that the coat layer is formed on the current collector body, and the above-described coat layer is formed on the current collector body. It was found that the discharge capacity of the lithium ion secondary battery can be improved as compared with the lithium ion secondary battery of Comparative Example 1.

Here, it is expected that a passive film formed naturally is formed on the current collector body in Comparative Example 1. This passive film is expected to inhibit the flow of electrons on the surface of the current collector body. On the other hand, the current collector main body in Example 1 and Example 2 is formed with a coat layer made of a conductive oxide having a specific resistance with digits of 10 ⁻⁴ and 10 ⁻³ . Therefore, since it is suppressed that the flow of electrons is inhibited on the surface of the current collector body, it is presumed that the initial discharge capacity of Example 1 and Example 2 is higher than the initial discharge capacity of Comparative Example 1. Further, it was confirmed that the initial discharge capacity of the laminated lithium ion secondary battery can be improved under a high voltage condition of 4.5 V to 3.0 V.

<Rate characteristics evaluation>
The rate characteristics at 25 ° C. were measured using the laminate type lithium ion secondary batteries of Example 1, Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 3. The voltage range is 4.5V-3.0V, and the current rate for discharging in 1 hour is 1C. The discharge capacity when the current rate was 0.33C, 1C, 5C, and 10C was measured. Based on the capacity when the current rate is 0.33 C, the ratio of 1 C capacity / 0.33 C capacity, 5 C capacity / 0.33 C capacity, 10 C capacity / 0.33 C capacity is expressed in%. The results are shown in Table 2.

As can be seen from Table 2, the capacity decreases as the current rate increases in any laminated lithium ion secondary battery, but the laminated lithium ion secondary batteries of Example 1 and Example 2 are comparative examples 1, As compared with the laminate type lithium ion secondary batteries of Comparative Examples 2 and 3, it was found that the capacity could be maintained even at a high rate, and the capacity reduction was suppressed. This is because the current collector has a coating layer made of a conductive oxide having a specific resistance with a digit number of 10 ⁻⁴ and 10 ⁻³ . It turned out that there exists an effect that it can suppress that a flow is inhibited. Moreover, it turned out that the effect becomes remarkable as a rate becomes high.

Further, when the laminate type lithium ion secondary batteries of Comparative Example 1, Comparative Example 2 and Comparative Example 3 were compared, a current collector formed with a coat layer having a specific resistance of 10 ⁻² or more (Comparative Example 2 and Comparative Example 2). It was found that the laminate type lithium ion secondary battery using Example 3) had a larger capacity drop at a higher rate than the laminate type lithium ion secondary battery using a current collector (Comparative Example 1) that did not form a coating layer. . From the above results, the laminate-type lithium ion secondary battery is particularly high by forming a coat layer made of a conductive oxide having a specific resistance with digits of 10 ⁻⁴ and 10 ⁻³ on the current collector body. It was found that capacity reduction can be suppressed at the rate.

<Cycle characteristic evaluation>
The cycle characteristics of the laminated lithium ion secondary batteries of Example 1, Example 2, and Comparative Example 1 were evaluated. As an evaluation of the cycle characteristics, a cycle test in which charging and discharging were repeated under the following conditions was performed, and the discharge capacity of each cycle was measured. Charging was CCCV charging (constant current constant voltage charging) at a 1C rate at 55 ° C. and a voltage of 4.5V. The voltage was held for 1 hour. Discharging performed CC discharge (constant current discharge) at 3.0V and 1C rate. This charging / discharging was made into 1 cycle, and the cycle test was done to 25 cycles. Each discharge capacity retention rate was calculated based on the discharge capacity at the first cycle. The discharge capacity retention rate (%) was determined by the following formula.

Discharge capacity maintenance rate (%) = (discharge capacity of each cycle / discharge capacity of the first cycle) × 100

FIG. 2 shows a graph showing the relationship between the number of cycles and the capacity retention rate (%) of the laminated lithium ion secondary batteries of Example 1, Example 2 and Comparative Example 1. As shown in FIG. 2, the capacity retention rate of the laminated lithium ion secondary batteries of Example 1 and Example 2 was higher than that of the laminated lithium ion secondary battery of Comparative Example 1 in each cycle. When comparing the capacity retention rate at the 25th cycle, the capacity retention rate of the laminated lithium ion secondary battery of Comparative Example 1 was 64.8%, whereas that of the laminate type lithium ion secondary battery of Example 1 was The capacity retention rate was 72.5%, and the capacity retention rate of the laminated lithium ion secondary battery of Example 2 was 68.5%.

By forming a coating layer made of a conductive oxide having a specific resistance of 10 ⁻⁴ and 10 ⁻³ on the current collector body, the cycle of the laminate-type lithium ion secondary battery can be achieved even at a high temperature of 55 ° C. It was found that the characteristics were improved as compared with Comparative Example 1. Therefore, the protective film prevents the current collector body from being corroded by the electrolytic solution, and the laminated lithium ion secondary battery of Example 1 and Example 2 is also more effective than the laminated lithium ion secondary battery of Comparative Example 1. The secondary battery was found to be superior.

<Measurement of Initial Capacity and Cell Resistance of Laminated Lithium Ion Secondary Batteries of Example 3, Example 4, Comparative Example 4, Comparative Example 5, and Comparative Example 6>
The initial capacity and cell resistance of the laminated lithium ion secondary batteries of Example 3, Example 4, Comparative Example 4, Comparative Example 5, and Comparative Example 6 were measured as follows, and the numerical value of Comparative Example 4 was set to 100. And digitized.

The initial capacity measurement was performed by first conditioning each laminated lithium ion secondary battery. The conditioning treatment was performed by repeating charging and discharging three times at a predetermined voltage and a predetermined rate at 25 ° C. Initial capacity measurement was performed as follows. Charging was CCCV charging (constant current constant voltage charging) at a 1C rate and a voltage of 4.5 V at 25 ° C. The voltage was maintained for 1 hour, and the discharge was a CC discharge (constant current discharge) at a voltage of 3.0V and a 1C rate. Then, it set to 25 degreeC, the discharge capacity in 0.33C was measured, and it was set as the initial stage capacity | capacitance.

Also, the discharge capacity at the 1C rate was measured, and the discharge capacity at the 1C rate was normalized with the discharge capacity at each 0.33C rate as 100.

The cell resistance (Ω) was measured by 3C rate and 10 second discharge at a voltage of 20% SOC (State of charge). The results are shown in Table 3.

As can be seen from Table 3, the standard value of the initial capacity of the laminated lithium ion secondary battery of Example 3 and Example 4 is 100 or more, and the standard of the initial capacity of the laminated lithium ion secondary battery of Comparative Example 4 The standard value of the cell resistance of the laminated lithium ion secondary battery of Example 3 and Example 4 is smaller than 100, and the standard value of the cell resistance of the laminated type lithium ion secondary battery of Comparative Example 4 It was small compared to. The laminated lithium ion secondary batteries of Comparative Examples 5 and 6 having a large specific resistance have an initial capacity smaller than 100, smaller than the initial capacity of the laminated lithium ion secondary battery of Comparative Example 4, and are comparative examples. The standard value of the cell resistance of the laminate type lithium ion secondary battery of No. 5 and Comparative Example 6 was larger than 100, which was larger than the standard value of the cell resistance of the laminate type lithium ion secondary battery of Comparative Example 4.

Here, since the cell resistance is measured at a 3C rate, it is an index showing high rate characteristics. A smaller value of the cell resistance indicates better high rate characteristics. The standard value of the cell resistance being 100 or less indicates that the high rate characteristic is higher than that of the laminate type lithium ion secondary battery of Comparative Example 4.

Therefore, it was found that the laminated lithium ion secondary batteries of Example 3 and Example 4 had higher initial capacity and higher high rate characteristics than the laminated lithium ion secondary battery of Comparative Example 4.

Further, the results of the laminated lithium ion secondary battery of Example 3 in which the current collector body was coated with conductive nitride, and the laminated lithium ion secondary battery of Example 4 in which the current collector body was coated with conductive oxide. Comparing the results of the secondary battery, the standard value of the cell resistance of the laminated lithium ion secondary battery of Example 3 is smaller than the standard value of the cell resistance of the laminated lithium ion secondary battery of Example 4, and the 1C rate Since the laminate type lithium ion secondary battery of Example 3 is higher than the laminate type lithium ion secondary battery of Example 4 in comparison with the discharge capacity at 0.33C rate, the high rate characteristics are It was found that the laminate type lithium ion secondary battery of Example 3 was superior to the laminate type lithium ion secondary battery of Example 4. The reason for this is thought to be because the conductive nitride has higher mechanical strength than the conductive oxide, but it is not clear.

<Initial capacity, cycle characteristics and cell resistance measurement of laminated lithium ion secondary batteries of Example 4, Example 5, Example 6, Example 7, Comparative Example 4, Comparative Example 6, and Comparative Example 7>
Example 4, Example 5, Example 6, Example 7, Comparative Example 4, Comparative Example 6, Comparative Example 7, Laminate type lithium ion secondary battery of initial capacity, cycle characteristics and cell resistance measurement as follows went.

The initial capacity was measured as follows. Charging was CCCV charging (constant current constant voltage charging) at a 1C rate and a voltage of 4.5 V at 25 ° C. The voltage was maintained for 1 hour, and the discharge was a CC discharge (constant current discharge) at a voltage of 3.0V and a 1C rate. Then, it set to 25 degreeC, the discharge capacity in 0.33C was measured, and it was set as the initial stage capacity (mAh / g).

The cell resistance (Ω) was measured by 3C rate and 10 second discharge at a voltage of 20% SOC (State of charge).

The capacity maintenance rate was measured by measuring the discharge capacity of each cycle by performing a cycle test in which charging and discharging were repeated under the following conditions. Charging was CCCV charging (constant current constant voltage charging) at a 1C rate at 55 ° C. and a voltage of 4.5V. The voltage was held for 1 hour. Discharging performed CC discharge (constant current discharge) at 3.0V and 1C rate. This charging / discharging was made into 1 cycle, and the cycle test was done to 25 cycles. Then, it set to 25 degreeC and measured the discharge capacity in 0.33C. Based on the initial capacity, the capacity retention rate after 25 cycles was calculated from the discharge capacity after 25 cycles. The capacity retention rate (%) was obtained by the following formula.

Capacity retention rate (%) = (discharge capacity after 25 cycles / initial capacity) × 100

The results are summarized in Table 4.

When comparing the initial capacities, the laminated lithium ion secondary batteries of Example 4, Example 5, Example 6, Example 7, Comparative Example 4, Comparative Example 6, and Comparative Example 7 all showed equivalent values. It was.

When the cell resistance was compared, the same value was obtained except that the cell resistance of the laminate type lithium ion secondary battery of Comparative Example 6 was increased. As described above, the cell resistance is an index indicating the high rate characteristic, and the lower the value, the higher the high rate characteristic.

Regarding the capacity retention rate, the laminate type lithium ion secondary battery of Comparative Example 4, the laminate type lithium ion secondary battery of Example 4, and the laminate type lithium ion secondary battery of Example 7 were compared. The capacity retention rate of the laminate type lithium ion secondary battery of Example 4 in which the ATO coat layer was formed on the current collector was compared with the capacity retention rate of the laminate type lithium ion secondary battery of Comparative Example 4 having no coat layer. Improved. Further, the capacity retention rate of the laminated lithium ion secondary battery of Example 7 in which the ATO coat layer was formed on the current collector and 1,3-propane sultone was added to the electrolyte was the laminated lithium ion of Example 4. The capacity retention rate of the ion secondary battery was improved.

In addition, for the laminated lithium ion secondary battery of Example 7, the protective film acts to prevent the current collector body from being corroded by the electrolytic solution resulting from the formation of the coat layer on the current collector body, and the sultone group. It was confirmed that the inclusion of the cyclic compound having the non-aqueous electrolyte exhibited both the effect of suppressing the decomposition of the non-aqueous electrolyte due to the active material and the like, and the cycle characteristics were greatly improved.

In the laminated lithium ion secondary battery of Example 5, a coating layer made of PTO is formed on the current collector body. From Table 4 to Example 5, the laminate-type lithium ion secondary battery has an initial capacity higher than that of the laminate-type lithium ion secondary battery of Example 4 using the current collector body on which the coating layer made of ATO is formed. As a result, the cell resistance and the capacity retention ratio were the same.

(Examples 8 to 10 and Comparative Examples 8 to 10)
<Production of laminated lithium-ion secondary battery>
(Example 8)
A laminated lithium ion secondary battery of Example 8 was produced in the same manner as in Example 1 except that the current collector 3 was used as a positive electrode current collector and LiBF ₄ was used as an electrolytic salt instead of LiPF ₆ .

Example 9
A laminated lithium ion secondary battery of Example 9 was produced in the same manner as in Example 8 except that the current collector 3 in Example 8 was changed to the current collector 1.

(Example 10)
A laminated lithium ion secondary battery of Example 10 was produced in the same manner as in Example 8 except that the current collector 3 in Example 8 was changed to the current collector 2.

(Comparative Example 8)
A laminated lithium ion secondary battery of Comparative Example 8 was produced in the same manner as in Example 8 except that the current collector 3 in Example 8 was changed to the current collector 5 and the electrolytic salt was changed to LIPF ₆ .

(Comparative Example 9)
A laminated lithium ion secondary battery of Comparative Example 9 was produced in the same manner as in Example 8 except that the electrolytic salt in Example 8 was changed to LIPF ₆ .

(Comparative Example 10)
A laminated lithium ion secondary battery of Comparative Example 10 was produced in the same manner as in Example 8 except that the current collector 3 in Example 8 was changed to the current collector 5.

<Initial capacity measurement>
The initial capacities of the laminated lithium ion secondary batteries of Examples 8 to 10 and Comparative Examples 8 to 10 were measured. Charging was CCCV charging (constant current constant voltage charging) at a 1C rate and a voltage of 4.5 V at 25 ° C. The voltage was held for 1 hour. The discharge was a CC discharge (constant current discharge) at a voltage of 3.0 V and a 1 C rate. The discharge capacity is measured and used as the initial capacity.

<Cycle characteristic evaluation>
Following the initial capacity measurement, the cycle characteristics of the laminated lithium ion secondary batteries of Examples 8 to 10 and Comparative Examples 8 to 10 were evaluated. As an evaluation of the cycle characteristics, a cycle test in which charge and discharge were repeated under the following conditions was performed. Charging was CCCV charging (constant current constant voltage charging) at a 1C rate at 55 ° C. and a voltage of 4.5V. The voltage was held for 1 hour. Discharging performed CC discharge (constant current discharge) at 3.0V and 1C rate. This charging / discharging was made into 1 cycle, and the cycle test was done to 25 cycles. Thereafter, the temperature was returned to 25 ° C., and the discharge capacity was measured at a 1 C rate. This discharge capacity was taken as the post-cycle capacity. The capacity retention rate (%) was obtained by the following formula.

Capacity retention rate (%) = capacity after cycle / initial capacity x 100

Table 5 shows the initial capacity, post-cycle capacity, and capacity retention rate of each of the examples and comparative examples.

From the results of Table 5, the results of the laminated lithium ion secondary batteries of Comparative Example 8 and Comparative Example 10 are compared. The laminate type lithium ion secondary batteries of Comparative Example 8 and Comparative Example 10 differ only in the electrolytic salt. The laminated lithium ion secondary battery of Comparative Example 10 using LiBF ₄ as the electrolytic salt has a lower initial capacity than the laminated lithium ion secondary battery of Comparative Example 8 using LIPF ₆ as the electrolytic salt, but maintains the capacity. The rate was high and the cycle characteristics were good. The laminated lithium ion secondary batteries of Comparative Example 8 and Comparative Example 9 differ only in whether a coating layer is formed. The laminate type lithium ion secondary battery of Comparative Example 9 on which the coating layer was formed had a higher capacity retention rate but a lower initial capacity than the laminate type lithium ion secondary battery of Comparative Example 8.

Comparing the initial capacities of the laminate type lithium ion secondary batteries of Example 8 and Comparative Example 10, the initial capacity of the laminate type lithium ion secondary battery of Example 8 in which the coat layer was formed was that of Comparative Example 10 having no coat layer. It was found that the initial capacity of the laminated lithium ion secondary battery can be greatly improved. The capacity retention rate of the laminated lithium ion secondary battery of Example 8 was found to be greater than the capacity retention rate of the laminated lithium ion secondary battery of Comparative Example 10. Compared with the laminate type lithium ion secondary battery of Comparative Example 10, the laminate type lithium ion secondary battery of Example 8 not only improved the initial capacity but also increased the capacity retention rate. From this, it was found that a synergistic effect was produced by forming a coat layer and further using LiBF ₄ as an electrolytic salt.

Comparing the capacity retention rates of the laminated lithium ion secondary batteries of Example 8 and Comparative Example 9, the capacity retention ratio of the laminated lithium ion secondary battery of Example 8 using LiBF ₄ as the electrolytic salt is It was found that the capacity retention rate of the laminated lithium ion secondary battery of Comparative Example 9 using LIPF ₆ was higher. It was found that the initial capacity of the laminated lithium ion secondary battery of Example 8 did not decrease as much as the initial capacity of the laminated lithium ion secondary battery of Comparative Example 10. That is, the laminate type lithium ion secondary battery of Example 8 was able to suppress the reduction of the initial capacity and further improve the cycle characteristics. Further, when the laminate type lithium ion secondary battery of Example 9 and Example 10 and the laminate type lithium ion secondary battery of Example 8 were compared, the initial stage of the laminate type lithium ion secondary battery of Example 9 and Example 10 was compared. The capacity was almost the same as the initial capacity of the laminated lithium ion secondary battery of Example 8, and the cycle characteristics were further improved as compared with the laminated lithium ion secondary battery of Example 8. Therefore, it was found that the laminate type lithium ion secondary batteries of Examples 8 to 10 were excellent in both initial capacity and cycle characteristics even under a high voltage use environment.

(Example 11 and Comparative Examples 11 to 14)
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. In addition, this invention is not limited by these Examples. In the following, unless otherwise specified, “part” means part by mass, and “%” means mass%.

(Example 11)
An aluminum foil having a thickness of 20 μm was prepared as a positive electrode current collector body. This aluminum foil was put into a sputtering apparatus, and IZO in which 10% by mass of zinc oxide was added to 90% by mass of indium oxide was sputtered on the surface of the aluminum foil to form a first layer having a thickness of 100 nm. Thereafter, SnO ₂ was sputtered on the surface of the first layer to form a second layer having a thickness of 100 nm. The total film thickness of the first layer and the second layer is 200 nm.

Next, 88 parts by mass of Li _1.0 Ni _0.5 Co _0.2 Mn _0.3 O ₂ as an active material, 6 parts by mass of acetylene black as a conductive additive, and 6 parts by mass of polyfluoride as a binder. Vinylidene chloride (PVDF) was mixed. This mixture was dispersed in an appropriate amount of N-methyl-2-pyrrolidone (NMP) to prepare a slurry.

The slurry was placed on the surface of the second layer, and applied with a doctor blade so that the slurry became a film. The current collector coated with the slurry was dried at 80 ° C. for 20 minutes, NMP was removed by volatilization, and an active material layer was formed on the surface of the second layer. Thereafter, the current collector on which the active material layer was formed was compressed by a roll press, and the current collector, the first layer, the second layer, and the active material layer were firmly bonded. The joined product was heated with a vacuum dryer at 120 ° C. for 6 hours, cut into a predetermined shape (rectangular shape of 25 mm × 30 mm), and used as a positive electrode for a nonaqueous electrolyte secondary battery.

The negative electrode was produced as follows. 97 parts by mass of graphite powder, 1 part by mass of acetylene black as a conductive auxiliary agent, 1 part by mass of styrene-butadiene rubber (SBR) and 1 part by mass of carboxymethyl cellulose (CMC) as a binder were mixed, and this mixture was mixed. A slurry was prepared by dispersing in an appropriate amount of ion-exchanged water. This slurry was applied to a copper foil having a thickness of 20 μm, which is a negative electrode current collector, in a film shape using a doctor blade. The current collector coated with the slurry is dried and pressed, and the bonded product is heated in a vacuum dryer at 120 ° C. for 6 hours, cut into a predetermined shape (rectangular shape of 25 mm × 30 mm), and a negative electrode having a thickness of about 60 μm did.

A laminate type lithium ion secondary battery was manufactured using the positive electrode and the negative electrode for the nonaqueous electrolyte secondary battery. Specifically, a rectangular sheet (27 × 32 mm, thickness 25 μm) made of polypropylene resin as a separator was sandwiched between a positive electrode and a negative electrode for a nonaqueous electrolyte secondary battery to form an electrode plate group. The electrode plate group was covered with a set of two laminated films, and the three sides were sealed, and then an electrolyte solution was injected into the bag-like laminated film. As an electrolytic solution, a solution in which LiPF ₆ was dissolved at 1 mol / l in a solvent obtained by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) at EC: DEC = 3: 7 (volume ratio) was used. Thereafter, the remaining one side was sealed to obtain a laminate type lithium ion secondary battery in which the four sides were hermetically sealed and the electrode plate group and the electrolyte were sealed. In addition, the positive electrode and negative electrode for nonaqueous electrolyte secondary batteries are provided with a tab that can be electrically connected to the outside, and a part of the tab extends to the outside of the laminated lithium ion secondary battery.

Through the above steps, a laminated lithium ion secondary battery of Example 11 was produced.

(Comparative Example 11)
An active material layer was formed directly on the surface of the current collector body of the positive electrode. That is, a laminated lithium ion secondary battery of Comparative Example 11 was produced in the same manner as in Example 11 except that the first layer and the second layer were not formed.

(Comparative Example 12)
A laminated lithium ion secondary battery of Comparative Example 12 was produced in the same manner as in Example 11 except that the second layer was not formed. The thickness of the IZO layer is 100 nm.

(Comparative Example 13)
A laminated lithium ion secondary battery of Comparative Example 13 was produced in the same manner as in Example 11 except that the first layer was not formed. The film thickness of the SnO ₂ layer is 100 nm.

(Comparative Example 14)
The order of formation of the first layer and the second layer was reversed, that is, the SnO ₂ layer was formed on the surface of the current collector body, and the IZO layer was formed on the surface of this layer. The laminate type lithium ion secondary battery of Comparative Example 14 was produced by the method described above. The total film thickness of the SnO ₂ layer and the IZO layer is 200 nm.

<Evaluation method>
The initial capacities of the laminated lithium ion secondary batteries of Example 11 and Comparative Examples 11 to 14 were measured. The battery to be measured is CCCV charged (constant current constant voltage charge) at 25 ° C., 0.33 C rate, voltage 4.5 V, and CC discharge (constant current discharge) is performed at voltage 3.0 V, 0.33 C rate. The discharge capacity when measured was measured and used as the initial capacity.

Moreover, AC impedance resistance measurement was performed, and the resistance value at 100 mHz was calculated.

Further, 200 cycles of 4.5V-3.0V charge / discharge cycles were performed at 55 ° C. and 1C rate, and then the discharge capacity at 0.33C rate was measured to calculate the capacity retention rate. The capacity retention rate (%) was obtained by the following formula.

Capacity retention rate (%) = capacity after cycle / initial capacity x 100

For example, the current rate for discharging in 1 hour is called 1C.

These results are shown in Table 6.

As seen in Table 6, when the laminate type lithium ion secondary battery of Example 11 and the laminate type lithium ion secondary batteries of Comparative Examples 11 and 12 were compared, the laminate type lithium ion secondary battery of Example 11 was The laminated lithium ion secondary battery and the protective layer of Comparative Example 11 in which the protective layer was not formed in advance even though two types of protective layers of the IZO layer and the SnO ₂ layer were formed on the current collector body. The resistance value was equal to or lower than that of the laminate type lithium ion secondary battery of Comparative Example 12 having only the IZO layer. Furthermore, the laminate type lithium ion secondary battery of Example 11 exhibited a capacity retention rate superior to the laminate type lithium ion secondary batteries of Comparative Example 11 and Comparative Example 12.

When the laminate type lithium ion secondary battery of Example 11 and the laminate type lithium ion secondary batteries of Comparative Examples 13 and 14 are compared, the protective layer of the laminate type lithium ion secondary battery of Example 11 is only SnO ₂ layer. The resistance value of the laminate type lithium ion secondary battery of Comparative Example 13 and the protective layer in the order of the laminate type lithium ion secondary battery of Comparative Example 14, which is different from the laminate type lithium ion secondary battery of Example 11, is significantly lower. Indicated.

The low resistance value of the laminated lithium ion secondary battery of Example 11 is that the first layer in contact with the current collector body uses IZO, which is a degenerate semiconductor and has a high carrier density. The Schottky barrier generated at the interface between the layers is remarkably reduced, and the second layer in contact with the first layer uses SnO ₂ having the same band gap as that of IZO. It can be understood that the result was obtained.

From these results that the nonaqueous electrolyte secondary battery of the present invention has a low resistance and a good capacity retention rate, the nonaqueous electrolyte secondary battery of the present invention is excellent in output characteristics and cycle characteristics. It could be confirmed. It was also confirmed that the nonaqueous electrolyte secondary battery of the present invention can be used under a high potential driving condition of 4.5V.

(Example 12 and Comparative Examples 15 and 16)
Example 12
An aluminum foil having a thickness of 20 μm was prepared as a positive electrode current collector body. This aluminum foil was put into a sputtering apparatus, and tin was sputtered to a thickness of about 100 nm on the surface of the aluminum foil under an argon gas atmosphere. Oxygen gas was introduced into the sputtering apparatus during the sputtering of tin. By doing so, a coating layer containing SnO ₂ was formed to a thickness of about 100 nm on the exposed aluminum foil surface and tin surface. That is, the current collector 11 was obtained by continuously performing the coating process and the coating process. Here, the specific resistance of aluminum as a current collector body is 2.5 μΩcm, and the specific resistance of Sn (tin) as a high resistance metal is 11 μΩcm.

The positive electrode was created as follows.

94 parts by mass of Li _1.0 Ni _0.5 Co _0.2 Mn _0.3 O ₂ as an active material, 3 parts by mass of acetylene black as a conductive additive, and 3 parts by mass of polyvinylidene fluoride (as a binder) PVDF) was mixed. This mixture was dispersed in an appropriate amount of N-methyl-2-pyrrolidone (NMP) to prepare a slurry.

The slurry was placed on the surface of the coating layer of the current collector 11 and applied using a doctor blade so that the slurry became a film. The current collector 11 coated with the slurry was dried at 80 ° C. for 20 minutes, NMP was removed by volatilization, and an active material layer was formed on the surface of the coating layer. Thereafter, the current collector 11 on which the active material layer was formed was compressed by a roll press machine, and the current collector 11 and the active material layer were firmly bonded. The joined product was heated with a vacuum dryer at 120 ° C. for 6 hours and cut into a predetermined shape (rectangular shape of 25 mm × 30 mm) to obtain a positive electrode.

The negative electrode was produced as follows.

97 parts by mass of graphite powder, 1 part by mass of acetylene black as a conductive auxiliary agent, 1 part by mass of styrene-butadiene rubber (SBR) and 1 part by mass of carboxymethyl cellulose (CMC) as a binder were mixed, and this mixture was mixed. A slurry was prepared by dispersing in an appropriate amount of ion-exchanged water. This slurry was applied to a copper foil having a thickness of 20 μm as a negative electrode current collector so as to form a film using a doctor blade, and the current collector coated with the slurry was dried and pressed. It was heated for a time with a vacuum dryer, cut into a predetermined shape (rectangular shape of 25 mm × 30 mm), and a negative electrode having a thickness of about 60 μm was obtained.

A laminate type lithium ion secondary battery was manufactured using the positive electrode and the negative electrode. Specifically, a rectangular sheet (27 × 32 mm, thickness 25 μm) made of polypropylene resin as a separator was sandwiched between the positive electrode and the negative electrode to form an electrode plate group. The electrode plate group was covered with a set of two laminated films, and the three sides were sealed, and then an electrolyte solution was injected into the bag-like laminated film. As an electrolytic solution, a solution in which LiPF ₆ was dissolved at 1 mol / l in a solvent obtained by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) at EC: DEC = 3: 7 (volume ratio) was used. Thereafter, the remaining one side was sealed to obtain a laminate type lithium ion secondary battery in which the four sides were hermetically sealed and the electrode plate group and the electrolyte were sealed. Note that the positive electrode and the negative electrode each have a tab that can be electrically connected to the outside, and a part of the tab extends to the outside of the laminated lithium ion secondary battery. Through the above steps, a laminated lithium ion secondary battery of Example 12 was produced.

(Comparative Example 15)
An aluminum foil itself having a thickness of 20 μm was used as a current collector for the positive electrode. Except for this, a laminated lithium ion secondary battery of Comparative Example 15 was produced in the same manner as in Example 12.

(Comparative Example 16)
The positive electrode current collector was formed by directly forming a coating layer containing SnO ₂ with a thickness of about 100 nm on the surface of an aluminum foil having a thickness of 20 μm. That is, a laminated lithium ion secondary battery of Comparative Example 16 was produced in the same manner as in Example 12 except that the high resistance metal was not formed between the aluminum foil and the coating layer.

<Evaluation method>
The initial capacities of the laminated lithium ion secondary batteries of Example 12 and Comparative Examples 15 and 16 were measured. The battery to be measured is CCCV charged (constant current constant voltage charge) at 25 ° C., 0.33 C rate, voltage 4.5 V, and CC discharge (constant current discharge) is performed at voltage 3.0 V, 0.33 C rate. The discharge capacity when measured was measured and used as the initial capacity.

Capacity retention rate (%) = capacity after cycle / initial capacity x 100

For example, the current rate for discharging in 1 hour is called 1C. Table 7 shows the results of the initial capacity, resistance, and capacity retention rate.

When the laminated lithium ion secondary battery of Example 12 and Comparative Example 15 are compared, the laminated lithium ion secondary battery of Example 12 has a coating film in advance even though the SnO ₂ coating layer is formed. A low resistance value equivalent to that of the laminate type lithium ion secondary battery of Comparative Example 15 in which was not formed was shown. In addition, the laminate type lithium ion secondary battery of Example 12 exhibited a capacity retention rate superior to that of the laminate type lithium ion secondary battery of Comparative Example 15.

When the laminated lithium ion secondary battery of Example 12 and Comparative Example 16 are compared, it can be seen that the resistance value of the laminated lithium ion secondary battery of Example 12 is extremely low.

The laminated lithium ion secondary battery of Comparative Example 16 is a high resistance, since the electrochemical properties of aluminum and SnO ₂ which constitute the current collector is greatly different, and SnO ₂ of the aluminum foil and the covering layer This is probably due to the large Schottky barrier at the interface.

On the other hand, in the laminated lithium ion secondary battery of Example 12, the presence of Sn between the aluminum foil and the SnO _{2 of the} coating layer allows the interface between aluminum and Sn and the interface between Sn and SnO ₂ to be present. Exists. Here, the resistance generated at the interface between aluminum and Sn is not a problem because both are metals and their electrochemical properties are similar. Considering the interface between the Sn and SnO _2, the difference in electrochemical properties between Sn and SnO ₂ is less than the difference in the electrochemical properties between aluminum and SnO _2. Therefore, it is presumed that the Schottky barrier generated at the interface between Sn and SnO ₂ is lower than the Schottky barrier generated at the interface between aluminum and SnO ₂ . Moreover, since the current collector of Example 12 was obtained by continuously performing the Sn coating step and the SnO ₂ coating step, it is presumed that the generation of the interface generated between Sn and SnO ₂ itself is reduced. Therefore, it is considered that the resistance value of the laminated lithium ion secondary battery of Example 12 was significantly lower than the resistance value of the laminated lithium ion secondary battery of Comparative Example 16.

Further, since the capacity retention rate after 200 cycles under the high potential driving condition is the same for the laminated lithium ion secondary battery of Example 1 and the laminated lithium ion secondary battery of Comparative Example 2, the present invention It can be said that the current collector for positive electrode of non-aqueous electrolyte secondary battery is excellent in corrosion resistance.

From the above results that the non-aqueous electrolyte secondary battery using the current collector for positive electrode of the non-aqueous electrolyte secondary battery of the present invention has a low resistance and a good capacity retention rate, the non-aqueous electrolyte secondary battery outputs It was confirmed that the characteristics and cycle characteristics were excellent. It was also confirmed that the current collector for the positive electrode of the non-aqueous electrolyte secondary battery of the present invention can be used under a high potential driving condition of 4.5V.

From the results and considerations of Example 12 and Comparative Examples 15 and 16, the relationship between the current collector body aluminum, the high resistance metal Sn and the coating layer SnO ₂ is present and the current collector resistance is clarified. It was. That is, it was confirmed that the resistance of the current collector is remarkably lowered by the presence of a high-resistance metal having a specific resistance higher than that of the current collector body between the current collector body and the coating layer. This relationship is not limited to the above embodiments, the current collector body silver than aluminum, for metals such as copper, indium oxide of the coating layer other than SnO _2, zinc oxide, nickel oxide, titanium oxide, etc. From the results and discussion of Example 12 and Comparative Examples 15 and 16, it can be applied to metal nitrides such as metal nitrides such as aluminum nitride and titanium nitride, and degenerate semiconductors such as IZO, AZO, and ITO. Will be apparent to those skilled in the art.

Claims

A current collector body;
From a conductive oxide having a specific resistance of 9.9 × 10 −3 Ωcm or less or a conductive nitride having a specific resistance of 9.9 × 10 −3 Ωcm or less formed on the surface of the current collector body A coat layer,
Have
The conductive oxide is obtained by adding at least one element selected from Zn, Mo, W, Ti, Zr, Sn and H to indium oxide, and from F, W, Ta, Sb, P and B to tin oxide. Any one selected from those obtained by adding at least one element selected, those obtained by adding at least one element selected from Ga, Al and B to zinc oxide, and those obtained by adding Nb element to titanium oxide.
The non-aqueous electrolyte secondary battery positive electrode current collector, wherein the conductive nitride is any one selected from TiN, ZrN, HfN, TaN, NbN, VN, and WN.
2. The non-aqueous electrolyte secondary battery positive electrode collector according to claim 1, wherein the indium oxide added with at least one element selected from Zn, Mo, W, Ti, Zr, Sn, and H is indium zinc oxide. Electric body.
The current collector for a positive electrode of a non-aqueous electrolyte secondary battery according to claim 1, wherein the zinc oxide added with at least one element selected from Ga, Al and B is aluminum zinc oxide or gallium zinc oxide.
The current collector for a nonaqueous electrolyte secondary battery positive electrode according to claim 1, wherein the conductive oxide is obtained by adding at least one element selected from F, Ta, Sb, and P to tin oxide.
The current collector for a nonaqueous electrolyte secondary battery positive electrode according to claim 1, wherein the conductive nitride is TiN.
The current collector for a positive electrode of a non-aqueous electrolyte secondary battery according to any one of claims 1 to 5, wherein the coating layer has a thickness of 10 nm to 1 µm.
A nonaqueous electrolyte secondary battery comprising the current collector for a positive electrode of the nonaqueous electrolyte secondary battery according to any one of claims 1 to 6.
The current collector for a non-aqueous electrolyte secondary battery positive electrode according to claim 1,
A non-aqueous electrolyte, and
The non-aqueous electrolyte is a non-aqueous electrolyte secondary battery containing 2.0% by mass or more and 6.0% by mass or less of a cyclic compound having a sultone group when the non-aqueous electrolyte is 100% by mass.
The cyclic compound having a sultone group is 1,3-propane sultone, 1,4-butene sultone, 1,3-propene sultone, 3-methyl-1,3-propene sultone, 1-methyl-1,3-propane sultone The nonaqueous electrolyte secondary battery according to claim 8, which is at least one selected from the group consisting of 2-methyl-1,3-propane sultone and 3-methyl-1,3-propane sultone.
The non-aqueous electrolyte secondary battery according to claim 8 or 9, wherein the coating layer is made of tin oxide added with at least one selected from F, Sb, Ta and P.
Coat made from the current collector conductive oxide resistivity by the sputtering method is 9.9 × 10 -3 Ωcm or less on the surface of the body or resistivity conductive nitride is 9.9 × 10 -3 Ωcm or less A coat layer forming step of forming a layer;
The conductive oxide is obtained by adding at least one element selected from Zn, Mo, W, Ti, Zr, Sn and H to indium oxide, and from F, W, Ta, Sb, P and B to tin oxide. Any one selected from those obtained by adding at least one element selected, those obtained by adding at least one element selected from Ga, Al and B to zinc oxide, and those obtained by adding Nb element to titanium oxide.
The method for producing a current collector for a positive electrode of a nonaqueous electrolyte secondary battery, wherein the conductive nitride is any one selected from TiN, ZrN, HfN, TaN, NbN, VN, and WN.
A positive electrode for a non-aqueous electrolyte secondary battery having a current collector for a non-aqueous electrolyte secondary battery positive electrode having a current collector body and a coating layer made of a conductive oxide formed on the surface of the current collector body When,
A non-aqueous electrolyte containing LiBF 4 (lithium tetrafluoroborate) as an electrolytic salt;
Have
The conductive oxide is obtained by adding at least one element selected from Zn, Mo, W, Ti, Zr, Sn and H to indium oxide, and from F, W, Ta, Sb, P and B to tin oxide. Any one selected from those obtained by adding at least one element selected, those obtained by adding at least one element selected from Ga, Al and B to zinc oxide, and those obtained by adding Nb element to titanium oxide. A non-aqueous electrolyte secondary battery.
The non-aqueous electrolyte according to claim 12, wherein the indium oxide added with at least one element selected from Zn, Mo, W, Ti, Zr, Sn, and H is indium tin oxide or indium zinc oxide. Next battery.
13. The nonaqueous electrolyte secondary battery according to claim 12, wherein the zinc oxide added with at least one element selected from Ga, Al and B is aluminum zinc oxide or gallium zinc oxide.
The nonaqueous electrolyte secondary battery according to any one of claims 12 to 14, wherein the conductive oxide has a specific resistance of 9.9 × 10 -3 Ωcm or less.
The non-aqueous electrolyte secondary battery according to any one of claims 12 to 15, wherein the coating layer has a thickness of 10 nm to 1 µm.
A current collector body;
A first layer formed on the surface of the current collector body;
A second layer formed on the surface of the first layer; and
An active material layer formed on the surface of the second layer;
The positive electrode for a non-aqueous electrolyte secondary battery, wherein the specific resistance of the first layer is lower than the specific resistance of the second layer and higher than the specific resistance of the current collector body.
The positive electrode for a non-aqueous electrolyte secondary battery according to claim 17, wherein the second layer is made of a metal oxide, a metal nitride, or a metal carbide.
The non-aqueous solution according to claim 17, wherein the second layer is at least one selected from indium oxide, zinc oxide, tin oxide, titanium oxide, ruthenium oxide, aluminum oxide, tantalum oxide, tungsten oxide, chromium oxide, and aluminum nitride. Positive electrode for electrolyte secondary battery.
The nonaqueous electrolyte according to any one of claims 17 to 19, wherein the first layer is made of a conductive metal oxide, a conductive metal nitride, or a conductive metal carbide obtained by adding another element to a metal oxide. Secondary battery positive electrode.
The non-aqueous electrolyte secondary according to claim 20, wherein the other element is at least one selected from Zn, Mo, W, Ti, Zr, Sn, H, F, Ta, Sb, B, Ga, Al, and Nb. Battery positive electrode.
The combination of the first layer and the second layer is selected from any one of a conductive metal oxide and a metal oxide, a conductive metal nitride and a metal nitride, or a combination of a conductive metal carbide and a metal carbide. The positive electrode for a non-aqueous electrolyte secondary battery according to any one of claims 17 to 21.
The positive electrode for a non-aqueous electrolyte secondary battery according to any one of claims 17 to 22, wherein the total thickness of the first layer and the second layer is 20 nm to 2 μm.
The positive electrode for a nonaqueous electrolyte secondary battery according to any one of claims 17 to 23, wherein the first layer has a thickness of 10 nm to 1 µm, and the second layer has a thickness of 10 nm to 1 µm.
The active material layer has the general formula:
LiCo p Ni q Mn r D S O 2 (D is selected from Al, Mg, Ti, Sn, Zn, W, Zr, Mo, Fe, Na, p + q + r + s = 1, 0 ≦ p ≦ 1, 0 ≦ q ≦ The positive electrode for a non-aqueous electrolyte secondary battery according to any one of claims 17 to 24, comprising a composite metal oxide represented by 1, 0 ≦ r ≦ 1, 0 ≦ s <1).
A nonaqueous electrolyte secondary battery comprising the positive electrode for a nonaqueous electrolyte secondary battery according to any one of claims 17 to 25.
27. The non-aqueous electrolyte secondary battery according to claim 26, wherein a charge potential of the positive electrode for the non-aqueous electrolyte secondary battery is 4.3 V or more based on lithium.
In the current collector for a positive electrode of a non-aqueous electrolyte secondary battery having a current collector body and a coating layer containing a metal oxide or metal nitride,
A current collector for a nonaqueous electrolyte secondary battery positive electrode, comprising a high-resistance metal having a higher specific resistance than the current collector body between the current collector body and the coating layer.
The current collector body has a specific resistance of 1.5 μΩcm to 150 μΩcm, the high resistance metal has a specific resistance of 1.6 μΩcm to 200 μΩcm, and the metal oxide or the metal nitride has a specific resistance of 10 μΩcm to 10 8. The current collector for a positive electrode of a nonaqueous electrolyte secondary battery according to claim 28, wherein the current collector is Ωcm.
The high resistance metal is at least one selected from copper, gold, aluminum, magnesium, tungsten, cobalt, zinc, nickel, iron, platinum, tin, indium, titanium, ruthenium, tantalum, and chromium. A current collector for a positive electrode of the nonaqueous electrolyte secondary battery as described.
The metal oxide is selected from indium oxide, zinc oxide, tin oxide, nickel oxide, copper oxide, titanium oxide, ruthenium oxide, aluminum oxide, tantalum oxide, tungsten oxide, chromium oxide, magnesium oxide, cobalt oxide, and iron oxide. At least one kind,
The metal nitride is selected from aluminum nitride, titanium nitride, copper nitride, magnesium nitride, tungsten nitride, cobalt nitride, zinc nitride, nickel nitride, iron nitride, tin nitride, indium nitride, ruthenium nitride, tantalum nitride, and chromium nitride. The current collector for a positive electrode of a nonaqueous electrolyte secondary battery according to any one of claims 28 to 30, wherein the current collector is at least one kind.
The non-aqueous electrolyte secondary battery positive electrode current collector according to any one of claims 28 to 31, wherein the high-resistance metal and the metal constituting the metal oxide or the metal nitride are the same element.
A method for producing a current collector for a non-aqueous electrolyte secondary battery positive electrode according to claim 28, comprising:
An application process of applying a high-resistance metal to the surface of the current collector body;
A coating step of coating the surface of the current collector obtained in the coating step with a metal oxide or metal nitride;
Of a current collector for a positive electrode of a non-aqueous electrolyte secondary battery comprising:
The method for producing a current collector for a nonaqueous electrolyte secondary battery positive electrode according to claim 33, wherein the coating step is performed by sputtering a metal in an oxygen or nitrogen atmosphere.
The coating process is performed by sputtering metal,
The manufacture of a current collector for a nonaqueous electrolyte secondary battery positive electrode according to claim 33 or 34, wherein the coating step is performed by sputtering the same metal as that used in the coating step in an oxygen or nitrogen atmosphere. Method.
36. The method for producing a current collector for a non-aqueous electrolyte secondary battery positive electrode according to claim 35, wherein the application step and the coating step are continuous steps by being in an oxygen or nitrogen atmosphere immediately before the end of the application step. .