JP2022189954A - Nonaqueous electrolyte battery and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte battery which is high in long-term reliability even in a high-temperature environment.

SOLUTION: A nonaqueous electrolyte battery comprises positive and negative electrodes. The positive electrode includes: a positive electrode collector; and a positive electrode mixture layer formed on the positive electrode collector. The positive electrode mixture layer is capable of occluding and releasing Li ions. The negative electrode has an area larger than an area of the positive electrode mixture layer of the positive electrode. The negative electrode is arranged so as to cover a whole surface of the positive electrode mixture layer through a separator. The negative electrode includes: an Al layer; and a Li-Al alloy layer formed on a surface of the Al layer. The negative electrode has a tensile strength of 4 N/mm or larger. The Al layer has a maximum thickness of 30 μm or more and 150 μm or less. The positive electrode has a capacity of 0.68 mAh/cm² or more and 4.87 mAh/cm² or less. The positive electrode mixture layer contains, as a positive electrode active material, at least one kind selected from the group consisting of a lithium cobalt oxide, a lithium manganese oxide and a lithium-containing composite oxide of an olivine structure.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2023,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a non-aqueous electrolyte battery having good high-temperature storage characteristics and a method for producing the same.

Non-aqueous electrolyte batteries are used in various applications, taking advantage of their characteristics such as high capacity and high voltage. Especially in recent years, the demand for non-aqueous electrolyte batteries for in-vehicle equipment is increasing.

Conventionally, as a power source for automotive electronic devices, non-aqueous batteries have better storage characteristics than the commonly used non-aqueous electrolyte secondary batteries, and their capacity hardly decreases even after long-term storage of several years or more. Electrolyte primary batteries are used.

Metallic lithium and lithium alloys such as Li—Al (lithium-aluminum) alloys are used as the negative electrode active material of the non-aqueous electrolyte primary battery. Since a lithium alloy can be used as a material, battery characteristics are stabilized by constructing a negative electrode using a clad material of a metal capable of absorbing and desorbing lithium and a dissimilar metal not capable of absorbing and desorbing lithium. is also proposed (Patent Documents 1 and 2).

In addition, for the purpose of enabling repeated charging and improving storage characteristics in a high-temperature environment, a laminate containing a metal substrate layer that does not alloy with Li and an Al active layer on both sides of the metal substrate layer is provided. A non-aqueous electrolyte battery has been proposed that uses, as a negative electrode, a clad material in which a Li—Al alloy is formed on the surface side of an Al active layer (Patent Document 3).

JP-A-8-293302 JP-A-10-106628 WO2016/039323

On the other hand, the non-aqueous electrolyte battery disclosed in Patent Document 3 using a clad material as a negative electrode can be repeatedly charged and can improve storage characteristics in a high-temperature environment, but the clad material is expensive, Moreover, when the battery is overdischarged, the metal forming the metal substrate layer of the clad material is eluted into the non-aqueous electrolyte, which adversely affects the battery characteristics.

In order to deal with this problem, as partially disclosed in Patent Document 2, it is conceivable to use an inexpensive aluminum plate instead of an expensive clad material for the negative electrode. However, if only an aluminum plate is used as the negative electrode, Al and Li react excessively when charged excessively, and the thickness of the Li—Al alloy layer formed on both sides of the aluminum plate gradually increases. At the same time, the thickness of the aluminum plate (Al layer) gradually decreases, and along with this, the negative electrode itself expands due to the formation of the Li—Al alloy layer. It is expected that the battery will break and the reliability of the battery will decrease in a high-temperature environment. In particular, compared to the cylindrical battery disclosed in Cited Document 2, in the case of a prismatic battery in which a wound electrode body is enclosed in a prismatic outer body, a large stress is applied to the R portion of the negative electrode, resulting in deterioration of the reliability of the battery. is of more concern.

The present invention solves the above problems, and provides a non-aqueous electrolyte battery that can maintain the strength of the negative electrode even when aluminum is used alone as a negative electrode material, and that has high long-term reliability in a high-temperature environment. be.

A non-aqueous electrolyte battery of the present invention is a non-aqueous electrolyte battery comprising a positive electrode, a negative electrode, a non-aqueous electrolyte, and a separator, wherein the positive electrode is formed on a positive electrode current collector and the positive electrode current collector. The positive electrode mixture layer is capable of intercalating and deintercalating Li ions, the area of the negative electrode is larger than the area of the positive electrode mixture layer of the positive electrode, and the negative electrode is is disposed so as to cover the entire surface of the positive electrode mixture layer with the separator interposed therebetween, the negative electrode includes an Al layer and a Li—Al alloy layer formed on the surface of the Al layer, Tensile strength is 4 N/mm or more.

A method of manufacturing a non-aqueous electrolyte battery of the present invention is a method of manufacturing the non-aqueous electrolyte battery of the present invention, wherein a positive electrode mixture layer is formed on at least one surface of a positive electrode current collector, and a step of preparing a positive electrode having a capacity of 0.68 mAh/cm ² or more and 4.87 mAh/cm ² or less; a step of preparing a negative electrode precursor made of an aluminum base material having a thickness of 150 μm or less; and disposing the negative electrode precursor via a separator so as to cover the entire surface of the positive electrode mixture layer of the positive electrode to produce an electrode assembly. and a step of charging after enclosing the electrode body and the non-aqueous electrolyte in an outer package.

According to the present invention, it is possible to provide a non-aqueous electrolyte battery with high long-term reliability in a high-temperature environment.

FIG. 1 is a schematic cross-sectional view of an aluminum base material used for a negative electrode precursor. FIG. 2 is a schematic cross-sectional view of the negative electrode after initial charging. FIG. 3 is a perspective view schematically showing the non-aqueous electrolyte battery of the example. 4 is a cross-sectional view taken along the line II of FIG. 3. FIG.

Embodiments of the non-aqueous electrolyte battery disclosed in the present application will be described. The non-aqueous electrolyte battery of the present embodiment includes a positive electrode, a negative electrode, a non-aqueous electrolyte, and a separator, and the positive electrode includes a positive electrode current collector and a positive electrode mixture layer formed on the positive electrode current collector. wherein the positive electrode mixture layer can occlude and release Li ions, the area of the negative electrode is larger than the area of the positive electrode mixture layer of the positive electrode, and the negative electrode is connected through the separator The negative electrode is arranged to cover the entire surface of the positive electrode mixture layer, and the negative electrode includes an Al layer and a Li—Al alloy layer formed on the surface of the Al layer, and the tensile strength of the negative electrode is 4 N/mm. That's it.

The non-aqueous electrolyte battery of the present embodiment can improve long-term reliability in a high-temperature environment by adopting the above configuration.

Li (metallic Li) and Li—Al alloys (alloys of Li and Al) have lower acceptance of Li (Li ions) than carbon materials. A secondary battery tends to lose its capacity at an early stage when charging and discharging are repeated. For this reason, carbon materials such as graphite are widely used as negative electrode active materials in conventional non-aqueous electrolyte secondary batteries that are expected to be used by repeatedly performing charging and discharging.

However, in a non-aqueous electrolyte secondary battery using a carbon material as a negative electrode active material, self-discharge tends to occur, and the capacity tends to decrease when stored in a charged state.

For these reasons, as a battery for use in in-vehicle equipment and outdoor equipment, it has better storage characteristics than conventional non-aqueous electrolyte secondary batteries, and even after long-term storage of several years or more, the capacity hardly decreases. Non-aqueous electrolyte primary batteries are applied.

On the other hand, even in such applications, for reasons such as ease of maintenance, it is possible to charge the battery several times to several tens of times, even though it is not required to repeat charging and discharging many times like a normal secondary battery. There is a request for the application of possible batteries.

Therefore, the non-aqueous electrolyte battery of the present embodiment can realize high storage characteristics and high capacity even when used in high-temperature environments such as for vehicles and outdoor equipment. , the Li—Al alloy formed on the surface of the Al layer was used as the negative electrode active material so that the battery could be charged a certain number of times.

In addition, when aluminum is used as the negative electrode material, the negative electrode precursor is composed of aluminum foil or the like, and the negative electrode precursor, the positive electrode, the separator, the non-aqueous electrolyte, etc. are placed in the battery, and then the initial charge (chemical ) to electrochemically react the aluminum foil and Li ions in the non-aqueous electrolyte to form a Li—Al alloy on the surface of the aluminum foil, forming an Al layer and the surface of the Al layer A negative electrode having a Li—Al alloy layer coated with the above is formed and used. If the Li—Al alloy is formed on the surface of the aluminum foil without limit during the initial charge, the Al layer that serves as the core material of the negative electrode becomes too thin and the strength decreases. -Al alloy, the core material of the negative electrode disappears, and the strength of the negative electrode may be extremely reduced. Therefore, in the present embodiment, the tensile strength of the negative electrode is set to 4 N/mm or more in order to maintain the strength of the negative electrode and ensure the reliability of the battery. Setting the tensile strength of the negative electrode to 4 N/mm or more substantially means maintaining the strength by maintaining the thickness of the Al layer, which is the core material of the negative electrode, at a certain value or more.

Each component of the non-aqueous electrolyte battery of this embodiment will be described below.

<Negative Electrode>
In the formation of the negative electrode according to the non-aqueous electrolyte battery of the present embodiment, only an Al base material (such as Al foil) is used as a negative electrode precursor without using a current collector. Specifically, the negative electrode precursor made of the Al base is used as it is for assembling a battery, and the Al of the Al base electrochemically reacts with Li ions in the non-aqueous electrolyte by charging after assembling. to form a negative electrode having an Al layer and a Li—Al alloy layer formed on the surface of the Al layer.

Since the negative electrode always has an Al layer with a constant thickness, the Al layer serves as a core material of the negative electrode, and the tensile strength of the negative electrode can be 4 N/mm or more. The tensile strength of the negative electrode is more preferably 7 N/mm or more. On the other hand, if the tensile strength of the negative electrode is too large, the thickness of the Al layer becomes too large, the volume of the core portion that does not contribute to charging and discharging increases, and the volumetric energy density of the battery decreases. The upper limit of strength is preferably about 11 N/mm.

Examples of the Al base material include a foil made of Al (and unavoidable impurities), and alloy components including Cu, Fe, Ni, Co, Mn, Cr, V, Ti, Zr, Nb, Mo, etc., and the balance being A foil made of Al and an Al alloy that is an unavoidable impurity (the total content of the alloy components is, for example, 50% by mass or less). For example, when the alloy component of the Al base material is Cu, the Cu content is preferably 7% by mass or less, more preferably 2% by mass or less, and more preferably 0.4% by mass or less. Within this range, the elution of Cu during overdischarge can be suppressed more reliably.

The thickness of the Al base material as the negative electrode precursor is preferably 30 μm or more, more preferably 40 μm or more, preferably 150 μm or less, and more preferably 100 μm or less. When the thickness of the Al base material is within the above range, the capacity of the negative electrode can be kept at a certain level or more while maintaining the tensile strength of the negative electrode after charging at 4 N/mm or more. However, since the non-aqueous electrolyte battery of the present embodiment is configured with a positive electrode capacity regulation, when the thickness of the Al base material as the negative electrode precursor is 30 μm or more and 150 μm or less, the tensile strength of the negative electrode after charging is To achieve 4 N/mm or more, the capacity of the positive electrode is preferably 0.68 mAh/cm ² or more and 4.87 mAh/cm ² or less, more preferably 3.65 mAh/cm ² or less.

A negative electrode lead body can be provided on each of the Al substrates used as the negative electrode precursor according to a conventional method.

FIG. 1 shows a cross-sectional view schematically showing an example of the Al base material used for the negative electrode precursor of the non-aqueous electrolyte battery of the present embodiment. In FIG. 1, the thickness a of the Al base material (negative electrode precursor) 100 is set to 30 μm or more and 150 μm or less.

FIG. 2 shows a cross-sectional view schematically showing an example of a state in which the Al base 100 of FIG. 1 is initially charged (formed) to form a negative electrode. In FIG. 2, negative electrode 200 includes Al layer 201 and Li—Al alloy layer 202 formed on the surface of Al layer 201 . The thickness b of the Al layer 201 is smaller than the thickness a of the Al base in FIG. 1 due to the formation of the Li—Al alloy layer 202 . On the other hand, the thickness c of the Li—Al alloy layer 202 expands in the direction of the arrow in FIG. 2 due to the reaction between Al and Li ions. becomes larger than a. However, in practice, the reaction between the Al base layer and the Li ions does not necessarily occur uniformly, and undulations occur at the interface between the Al layer 201 and the Li—Al alloy layer 202. Therefore, the thickness of the Al layer 201 b And the thickness c of the Li—Al alloy layer 202 varies depending on the location, but the thickness a of the Al base material before anodization is usually uniform.

Further, in the non-aqueous electrolyte battery of the present embodiment, the area of the negative electrode is set larger than the area of the positive electrode mixture layer capable of intercalating and deintercalating Li ions of the positive electrode described later, and the negative electrode serves as a separator. Since the positive electrode mixture layer is arranged to cover the entire surface of the positive electrode mixture layer through the not likely to be formed. Therefore, when observing the entire thickness of the Al layer of the negative electrode, the thickness b of the Al layer in the portion where the Li—Al alloy layer is formed is greater than the thickness a of the Al base before the first charge. However, the thickness of the Al layer in the portion where the Li—Al alloy layer is not formed is the same as the thickness a of the Al base before the initial charge. corresponds to the thickness a of the Al base (negative electrode precursor) before the initial charge.

The term "positive electrode mixture layer" as used herein refers to a portion of the positive electrode that is capable of intercalating and deintercalating Li ions. For example, when a layer containing a positive electrode active material is formed on a positive electrode current collector and then a layer (such as a tape) that inhibits the permeation of Li ions is attached on the layer, the layer at the attached portion is , does not correspond to the positive electrode material mixture layer referred to in the present embodiment.

The Al layer 201 and the Li—Al alloy layer 202 in FIG. 2 can be identified by observing the cross section of the negative electrode with a scanning electron microscope (SEM). Whether or not the negative electrode is broken can also be confirmed by observing the cross section of the negative electrode with an SEM.

<Positive electrode>
The positive electrode according to the non-aqueous electrolyte battery of the present embodiment has a structure in which, for example, a positive electrode mixture layer containing a positive electrode active material, a conductive aid, a binder, and the like is provided on one or both sides of a positive electrode current collector. Available. As described above, when the maximum thickness of the Al layer of the negative electrode is 30 μm or more and 150 μm or less, that is, when the thickness of the Al base material which is the negative electrode precursor before the initial charge (chemical conversion) is 30 μm or more and 150 μm or less, Preferably, the capacity of the positive electrode is set to 0.68 mAh/cm ² or more and 4.87 mAh/cm ² or less. This prevents the Al base material of the negative electrode precursor from excessively reacting with Li ions, making the thickness of the Al layer of the negative electrode too thin, and the tensile strength of the negative electrode falling below 4 N/mm.

The capacity of the positive electrode shall be measured as follows. That is, the non-aqueous electrolyte battery of this embodiment is disassembled after the initial charge (formation), and the positive electrode is taken out. After that, when the positive electrode taken out has a positive electrode mixture layer only on one side of the positive electrode current collector, the positive electrode mixture layer portion of the positive electrode is cut into a size of 1 cm ² to obtain a positive electrode capacity measurement sample. . When the positive electrode taken out has positive electrode mixture layers on both sides of the positive electrode current collector, the positive electrode mixture layer on one side is removed from the taken-out positive electrode, and the positive electrode mixture layer is removed from the one side. A portion of the mixture layer is cut into a size of 1 cm ² to obtain a positive electrode capacity measurement sample. Next, the positive electrode capacity measurement sample and Li foil are combined to produce a model cell. As the non-aqueous electrolyte for this model cell, the same non-aqueous electrolyte as used in the non-aqueous electrolyte battery of the present embodiment is used. Subsequently, this model cell is charged at a constant current of 0.25 mA to a predetermined voltage obtained by adding 0.35 V to the initial charging voltage of the non-aqueous electrolyte battery. A constant voltage charge is performed until it drops to 0.025 mA. Thereafter, the battery is discharged at a constant current of 0.25 mA until it reaches 3 V, and the capacity at that time is taken as the capacity of the positive electrode.

Further, the mass of the positive electrode mixture layer per one side of the positive electrode current collector is preferably 7 mg/cm ² or more and 30 mg/cm ² or less, and is 8.5 mg/cm ² or more and 25 mg/cm ² or less. is more preferable. When the mass of the positive electrode mixture layer is less than 7 mg/cm ² , the discharge load per unit mass of the positive electrode active material during high-rate discharge increases, resulting in a decrease in output characteristics, and the mass of the positive electrode mixture layer decreases to 30 mg. /cm ² , it may be difficult to set the upper limit of the capacity of the positive electrode to 4.87 mAh/cm ² .

The mass of the positive electrode mixture layer can be controlled by adjusting the amount of the positive electrode mixture applied per unit area to the positive electrode current collector.

Although the positive electrode active material is not particularly limited, it is preferable to use a lithium-containing nickel layered oxide.

In general, a positive electrode active material reacts with a non-aqueous electrolyte in a high-temperature environment, depositing a reaction product on the positive electrode and generating gas at the same time. When lithium cobalt oxide, which is commonly used in non-aqueous electrolyte batteries such as lithium ion secondary batteries, is used as a positive electrode active material, the surface of lithium cobalt oxide reacts with the non-aqueous electrolyte at high temperatures to generate Co. A reaction product containing Co is deposited on the surface of the positive electrode, and gas is generated at the same time. Then, the surface of the lithium cobalt oxide reacts with the non-aqueous electrolyte again to produce a reaction product containing Co and gas. In other words, if the positive electrode active material contains a large amount of lithium cobaltate, Co continues to be eluted and gas is generated every time the battery is exposed to high temperatures.

However, the lithium-containing nickel layered oxide once reacts with a non-aqueous electrolyte at a high temperature to produce a reaction product containing Ni and generate gas, but the reaction product containing Ni is not decomposed. It stays on the positive electrode and forms a film. Also, even if the battery is exposed to high temperatures thereafter, the elution of Ni and the generation of gas are suppressed. Therefore, metal elution is less likely to occur even at high temperatures when the battery is charged. Therefore, even if the battery is stored at high temperature for a long period of time, gas generation can be suppressed, and a decrease in discharge capacity can be suppressed.

As the lithium-containing nickel layered oxide, it is preferable to use a composite oxide represented by the following general formula (1). The use of the composite oxide represented by the following general formula (1) not only suppresses gas generation during long-term storage, but also suppresses an increase in resistance.

_{Li1 + xNi1 -yzM1yM2zO2} ⁽ ₁ ⁾

In the general formula (1), M ¹ is at least one element selected from the group consisting of Co, Mn, Al, Mg, Zr, Mo, Ti, Ba, W and Er, M ² is Li, It is an element other than Ni and M ¹ and satisfies −0.1≦x≦0.1, 0≦y<0.85, and 0≦z≦0.05.

When Co is present in the crystal lattice in the composite oxide represented by the general formula (1), the phase transition of the lithium-containing composite oxide due to the insertion and extraction of Li during charging and discharging of the non-aqueous electrolyte battery Since the irreversible reaction that occurs can be moderated and the reversibility of the crystal structure of the composite oxide can be enhanced, it is possible to construct a non-aqueous electrolyte battery with a longer charge-discharge cycle life.

When the composite oxide represented by the general formula (1) contains Mg, Mg ²⁺ is rearranged to the Li site when the phase transition of the composite oxide occurs due to desorption and insertion of Li. Therefore, the irreversible reaction is moderated, and the reversibility of the layered crystal structure of the composite oxide represented by the space group R3-m is improved.

When the composite oxide represented by the general formula (1) contains Mn, the tetravalent Mn stabilizes the unstable tetravalent Ni. It becomes possible to construct an electrolyte battery.

When the composite oxide represented by the general formula (1) contains W or Mo, it is possible to reduce the expansion/contraction rate of crystals during charge/discharge, and charge/discharge cycle characteristics of the battery. lead to an improvement in

In the composite oxide represented by the general formula (1), when Al is present in the crystal lattice, the crystal structure can be stabilized and the thermal stability can be improved. It becomes possible to configure a high-quality non-aqueous electrolyte battery. In addition, since Al is present at the grain boundaries and surfaces of the particles of the composite oxide, it is possible to suppress the stability over time and the side reaction with the non-aqueous electrolyte, and the non-aqueous electrolyte battery has a longer life. can be configured.

When Er is present at the grain boundaries and surfaces of the particles of the composite oxide represented by the general formula (1), the catalytic properties on the surface of the positive electrode active material can be reduced, and the decomposition of the non-aqueous electrolyte can be suppressed. .

In the composite oxide represented by the general formula (1), when an alkaline earth metal element such as Ba is contained in the particles, the growth of the primary particles is promoted and the crystallinity of the composite oxide is improved. A secondary reaction with the non-aqueous electrolyte is suppressed, and a battery that is less likely to swell during high-temperature storage can be constructed.

In the composite oxide represented by the general formula (1), when Ti is contained in the particles, it is arranged in crystal defects such as oxygen defects in the LiNiO ₂ type crystal structure to stabilize the crystal structure. Therefore, the reversibility of the reaction of the composite oxide is enhanced, and a non-aqueous electrolyte battery having better charge-discharge cycle characteristics can be constructed.

When the composite oxide represented by the general formula (1) contains Zr, it is present at the grain boundaries and surfaces of the particles of the composite oxide, so that the electrochemical properties of the composite oxide are not impaired. , suppresses its surface activity. In addition, due to the effect of suppressing the activity of the particle surface by Zr, it is possible to construct a non-aqueous electrolyte battery with excellent storability and long life.

In the composite oxide represented by the general formula (1), the elements of M ¹ may or may not be contained depending on the desired properties of the respective elements described above.

The composite oxide represented by the general formula (1) may or may not contain ^M2 which is an element ^other than Li, Ni and M1. If z representing the content of the element ^M2 is 0.05 or less, the effect of this embodiment is not impaired, but it is more preferably 0.01 or less.

The composition analysis of the positive electrode active material can be performed as follows using an ICP (Inductive Coupled Plasma) method. First, 0.2 g of the positive electrode active material to be measured is collected and placed in a 100 mL container. After that, 5 mL of pure water, 2 mL of aqua regia, and 10 mL of pure water are added in this order and dissolved by heating. is used to analyze the composition by the calibration curve method. From the results obtained, composition amounts can be derived.

The positive electrode active material may contain one type of the lithium-containing nickel layered oxide, or may contain two or more types.

In addition, the positive electrode active material can contain a lithium-containing composite oxide different from the lithium-containing nickel layered oxide according to the required battery characteristics.

Examples of the lithium _- containing composite oxide different from the lithium _- containing nickel layered oxide include lithium cobalt oxides such as _LiCoO2 ; lithium manganese oxides such as _LiMnO2 and _Li2MnO3 ; _LiMn2O4 ; spinel structure lithium-containing composite oxides such as Li _4/3 Ti _5/3 O ₄ ; olivine structure lithium-containing composite oxides such as LiFePO ₄ ; oxides substituted with other elements; and the like. One type of these lithium-containing composite oxides may be used, or two or more types may be used.

Even when the positive electrode active material contains a lithium-containing composite oxide different from the lithium-containing nickel layered oxide, the positive electrode active material contains 50% by mass or more of the lithium-containing nickel layered oxide. is preferable, and it is more preferable to contain 80% by mass or more. This is because the effect of the lithium-containing nickel layered oxide described above can be obtained satisfactorily.

Examples of conductive aids for the positive electrode mixture layer include carbon blacks such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; carbon fibers; and other carbon materials such as metal fibers. carbon fluoride; metal powders such as copper and nickel; organic conductive materials such as polyphenylene derivatives;

Examples of binders for the positive electrode mixture layer include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), carboxymethylcellulose (CMC), and polyvinylpyrrolidone (PVP).

For the positive electrode, for example, a positive electrode mixture containing a positive electrode active material, a conductive agent, a binder, etc. is dispersed in an organic solvent such as N-methyl-2-pyrrolidone (NMP) or water, and a positive electrode mixture-containing paint (paste , slurry, etc.) is prepared, the positive electrode mixture-containing coating material is applied to one or both sides of a current collector, dried, and pressed if necessary.

Alternatively, the positive electrode mixture may be used to form a molded body, and a part or all of one side of the molded body may be bonded to a positive electrode current collector to form a positive electrode. The positive electrode material mixture molded body and the positive electrode current collector can be bonded together by pressing or the like.

As the current collector of the positive electrode, foils of metal such as Al and Al alloys, punching metals, nets, expanded metals, and the like can be used, but usually Al foils are preferably used. The thickness of the positive electrode current collector is preferably 10 to 30 μm.

The composition of the positive electrode mixture layer is, for example, 80.0 to 99.8% by mass of the positive electrode active material, 0.1 to 10% by mass of the conductive aid, and 0.1 to 10% by mass of the binder. is preferred. Moreover, the thickness of the positive electrode mixture layer is preferably 15 to 100 μm per side of the current collector.

A positive electrode lead body can be provided on the current collector of the positive electrode according to a conventional method.

<Separator>
The separator preferably has a property of closing its pores (that is, a shutdown function) at 80° C. or higher (more preferably 100° C. or higher) and 170° C. or lower (more preferably 150° C. or lower). Separators used in nonaqueous electrolyte batteries such as lithium ion secondary batteries, for example, polyolefin microporous membranes such as polyethylene (PE) and polypropylene (PP) can be used. The microporous membrane constituting the separator may be, for example, one using only PE or one using only PP, or a laminate of a PE microporous membrane and a PP microporous membrane. There may be. The thickness of the separator is preferably 10 to 30 μm, for example.

<Electrode body>
In the non-aqueous electrolyte battery of the present embodiment, the positive electrode and the negative electrode are, for example, an electrode body stacked with a separator interposed therebetween, a wound electrode body formed by further spirally winding the electrode body, or It is used in the form of a laminated electrode body in which a plurality of positive electrodes and a plurality of negative electrodes are alternately laminated. Since a large stress is applied to the R portion of the negative electrode, the strength of the negative electrode can be maintained even if aluminum is used alone as the negative electrode material, and the non-aqueous electrolyte battery of the present embodiment can ensure long-term reliability in a high-temperature environment. configuration is preferably used.

<Non-aqueous electrolyte>
As the non-aqueous electrolyte, a solution in which a lithium salt is dissolved in an organic solvent is used.

Examples of organic solvents for the non-aqueous electrolyte include cyclic carbonates such as ethylene carbonate, propylene carbonate (PC), butylene carbonate and vinylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate and methyl ethyl carbonate; Chain esters such as; Cyclic esters such as compounds having a lactone ring; Chain ethers such as dimethoxyethane, diethyl ether, 1,3-dioxolane, diglyme, triglyme, and tetraglyme; Dioxane, tetrahydrofuran, 2-methyltetrahydrofuran, etc. cyclic ethers; nitriles such as acetonitrile, propionitrile and methoxypropionitrile; sulfites such as ethylene glycol sulfite; In order to obtain a battery with better characteristics, it is desirable to use a combination capable of obtaining a high electrical conductivity, such as a mixed solvent of a cyclic carbonate and the above-exemplified chain carbonate.

Moreover, it is more preferable to use PC as the organic solvent of the non-aqueous electrolyte. PC particularly contributes to ensuring the low-temperature discharge characteristics of non-aqueous electrolyte batteries. For example, ethylene carbonate is often used as an organic solvent for the non-aqueous electrolyte in non-aqueous electrolyte batteries. It is possible to improve the characteristics.

Furthermore, from the viewpoint of further improving the low-temperature discharge characteristics of non-aqueous electrolyte batteries, it is preferable to use a compound having a lactone ring together with PC as the organic solvent for the non-aqueous electrolyte.

Examples of compounds having a lactone ring include γ-butyrolactone and lactones having a substituent at the α-position.

Lactones having a substituent at the α-position are preferably, for example, those having a 5-membered ring (having 4 carbon atoms in the ring). The lactones may have one or two α-substituents.

Examples of the substituent include a hydrocarbon group, a halogen group (fluoro group, chloro group, bromo group, iodo group) and the like. The hydrocarbon group is preferably an alkyl group, an aryl group, or the like, and preferably has 1 to 15 carbon atoms (more preferably 6 or less). When the substituent is a hydrocarbon group, methyl group, ethyl group, propyl group, butyl group, phenyl group and the like are more preferable.

Specific examples of lactones having a substituent at the α-position include α-methyl-γ-butyrolactone, α-ethyl-γ-butyrolactone, α-propyl-γ-butyrolactone, α-butyl-γ-butyrolactone, α-phenyl -γ-butyrolactone, α-fluoro-γ-butyrolactone, α-chloro-γ-butyrolactone, α-bromo-γ-butyrolactone, α-iodo-γ-butyrolactone, α,α-dimethyl-γ-butyrolactone, α,α -diethyl-γ-butyrolactone, α,α-diphenyl-γ-butyrolactone, α-ethyl-α-methyl-γ-butyrolactone, α-methyl-α-phenyl-γ-butyrolactone, α,α-difluoro-γ-butyrolactone , α,α-dichloro-γ-butyrolactone, α,α-dibromo-γ-butyrolactone, α,α-diiodo-γ-butyrolactone and the like. The above may be used in combination. Among these, α-methyl-γ-butyrolactone is more preferred.

The content of PC in the total organic solvent used in the non-aqueous electrolyte is preferably 10% by volume or more, and preferably 30% by volume or more, from the viewpoint of ensuring the above-mentioned effects due to its use. more preferred. As described above, since the organic solvent of the non-aqueous electrolyte may be PC alone, the upper limit of the preferred content of PC in the total organic solvent used in the non-aqueous electrolyte is 100% by volume.

When using a compound having a lactone ring, the content of the compound having a lactone ring in the total organic solvent used in the non-aqueous electrolyte is 0.1 mass, from the viewpoint of ensuring good effects of its use. % or more, and it is desirable to use within a range that satisfies this preferred value and that the content of PC in the total organic solvent satisfies the aforementioned preferred value.

The lithium salt of the non-aqueous electrolyte has high heat resistance and can improve the storage characteristics of the non-aqueous electrolyte battery in a high-temperature environment. Therefore, it is preferred to use LiBF ₄ .

Other lithium salts for the non _- aqueous electrolyte include, for example, LiClO4, _LiPF6 , _LiAsF6 , _LiSbF6 , _{LiCF3SO3 , LiCF3CO2 , Li2C2F4 (} SO3) _{2 , LiN} ( _CF3SO2 ) ₂ , _{LiC(CF3SO2)3 , LiCnF2n + 1SO3 ( 2≤n≤7), LiN(RfOSO2)2 [ wherein} Rf is a fluoroalkyl group], etc. is mentioned.

The concentration of the lithium salt in the non-aqueous electrolyte is preferably 0.6 mol/L or more, more preferably 0.9 mol/L or more.

The concentration of all lithium salts in the non-aqueous electrolyte is preferably 1.8 mol/L or less, more preferably 1.6 mol/L or less. Therefore, when only LiBF ₄ is used as the lithium salt, it is preferable to use the concentration within the range that satisfies the above preferred upper limit. On the other hand, when other lithium salts are used together with LiBF ₄ , it is preferable that the concentration of LiBF ₄ satisfies the preferred lower limit and the concentration of all lithium salts satisfies the preferred upper limit. .

Moreover, it is preferable that the non-aqueous electrolyte contains a nitrile compound as an additive. By using a non-aqueous electrolyte to which a nitrile compound is added, the nitrile compound is adsorbed on the surface of the positive electrode active material to form a film, and this film suppresses gas generation due to oxidative decomposition of the non-aqueous electrolyte. In particular, swelling of the battery when stored in a high-temperature environment can be suppressed.

Nitrile compounds added to the non-aqueous electrolyte include mononitriles such as acetonitrile, propionitrile, butyronitrile, valeronitrile, benzonitrile and acrylonitrile; , 1,5-dicyanopentane (pimelonitrile), 1,6-dicyanohexane (suberonitrile), 1,7-dicyanoheptane (azelaonitrile), 2,6-dicyanoheptane, 1,8-dicyanooctane, 2,7-dicyano dinitriles such as octane, 1,9-dicyanononane, 2,8-dicyanononane, 1,10-dicyanodecane, 1,6-dicyanodecane and 2,4-dimethylglutaronitrile; cyclic nitriles such as benzonitrile; methoxyacetonitrile and the like alkoxy-substituted nitriles of; Among these nitrile compounds, dinitriles are more preferred, and adiponitrile, pimelonitrile and suberonitrile are even more preferred.

The content of the nitrile compound in the non-aqueous electrolyte used in the battery is preferably 0.1% by mass or more, and preferably 1% by mass or more, from the viewpoint of ensuring the above-mentioned effects of using them. is more preferred. However, if the amount of the nitrile compound in the non-aqueous electrolyte is too large, the low-temperature discharge characteristics of the battery tend to deteriorate. Therefore, from the viewpoint of limiting the amount of the nitrile compound in the non-aqueous electrolyte to some extent and improving the low-temperature discharge characteristics of the battery, the content of the nitrile compound in the non-aqueous electrolyte used in the battery is , is preferably 10% by mass or less, more preferably 5% by mass or less.

Moreover, the non-aqueous electrolyte preferably contains a phosphoric acid compound or a boric acid compound having a group represented by the following general formula (2) in its molecule.

In the general formula (2), X is Si, Ge or Sn, and R ¹ , R ² and R ³ are each independently an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms or It represents an aryl group having 6 to 10 carbon atoms, and some or all of the hydrogen atoms may be substituted with fluorine.

For example, in the case of batteries used for on-vehicle equipment and equipment for outdoor equipment, it is conceivable to use them not only in high-temperature environments but also in cold regions. In a low-temperature environment, the operability of the battery is lower than in the normal temperature environment, and in particular, batteries that have deteriorated over time tend to have lower discharge characteristics. Therefore, assuming use under all temperatures, it is preferable that high-rate discharge can be performed even in a low-temperature environment after being placed in a high-temperature environment for a certain period of time (in a state similar to deterioration over time).

In the non-aqueous electrolyte battery of the present embodiment, when a non-aqueous electrolyte containing a phosphoric acid compound or boric acid compound having a group represented by the general formula (2) in the molecule is used, long-term After storage, high-rate discharge characteristics can be enhanced in a low-temperature environment. The reason for this is not clear, but the inventors presume as follows.

When using a non-aqueous electrolyte containing a phosphoric acid compound or a boric acid compound having a group represented by the general formula (2) in the molecule, the phosphoric acid compound or boric acid compound is the surface of the positive electrode active material described above. Since it forms a strong film with low resistance, the film is not destroyed even when the battery is stored at high temperatures for a long period of time, and elution of metal from the positive electrode active material can be suppressed. In addition, since this coating hardly inhibits the insertion of Li ions even at low temperatures, it is possible to improve the high-rate discharge characteristics at low temperatures of the battery after long-term storage at high temperatures.

Furthermore, the phosphoric acid compound or boric acid compound also acts on the negative electrode of the non-aqueous electrolyte battery to form a film. It is believed that the phosphoric acid compound or boric acid compound reduces the amount of Li used to form a coating on the surface of the negative electrode, thereby forming a thin and good quality coating on the surface of the negative electrode. As a result, deterioration of the negative electrode can be suppressed because the film on the surface of the negative electrode is not destroyed even during long-term storage at high temperatures. In addition, this film does not easily inhibit detachment of Li ions even at low temperatures. For these reasons as well, it is possible to improve the high-rate discharge characteristics at low temperature of the battery after long-term storage at high temperature.

As described above, by combining the specific positive electrode and the specific negative electrode according to the present embodiment with the non-aqueous electrolyte containing the phosphoric acid compound or the boric acid compound, each of the above effects functions synergistically. Therefore, the battery can have better storage characteristics in a high-temperature environment and can cope with temperature changes.

In the general formula (2), X is Si, Ge or Sn, preferably Si. That is, the phosphoric acid compound is more preferably a silyl phosphate, and the boric acid compound is more preferably a silyl borate. In general formula (2), R ¹ , R ² and R ³ are each independently an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms. However, a methyl or ethyl group is more preferred. A trimethylsilyl group is particularly preferable as the group represented by the general formula (2).

Further, in the phosphoric acid compound, only one of the hydrogen atoms of the phosphoric acid may be substituted with the group represented by the general formula (2), and among the hydrogen atoms of the phosphoric acid, Two may be substituted with a group represented by the general formula (2), and all three hydrogen atoms of phosphoric acid may be substituted with a group represented by the general formula (2). However, it is more preferable that all three hydrogen atoms of the phosphoric acid are substituted with the groups represented by the general formula (2).

As such a phosphoric acid compound, tris(trimethylsilyl) phosphate is particularly preferred.

Further, in the boric acid compound, only one of the hydrogen atoms of boric acid may be substituted with a group represented by the general formula (2), and among the hydrogen atoms of boric acid, Two may be substituted with a group represented by the general formula (2), and all three hydrogen atoms of boric acid may be substituted with a group represented by the general formula (2). However, it is more preferable that all three hydrogen atoms of boric acid are substituted with groups represented by the general formula (2).

As such a boric acid compound, tris(trimethylsilyl) borate is particularly preferred.

The content of the phosphoric acid compound or boric acid compound having the group represented by the general formula (2) in the molecule in the non-aqueous electrolyte used in the battery ensures the above-mentioned effects due to its use. From the viewpoint of reducing the content, the content is preferably 0.2% by mass or more, and more preferably 0.5% by mass or more. In addition, if the content is too large, a large amount of gas is generated when the film is formed. The content of the compound or boric acid compound is preferably 7% by mass or less, more preferably 5% by mass or less, and particularly preferably 3% by mass or less.

In the non-aqueous electrolyte battery, in addition to the phosphoric acid compound or boric acid compound, the non-aqueous electrolyte contains _LiBF4 as a lithium salt, PC as an organic solvent, and a nitrile compound. is particularly preferred. When such a non-aqueous electrolyte is used, the action of each component functions synergistically, and swelling of the battery during high-temperature storage can be suppressed to a greater extent, and in a low-temperature environment after high-temperature storage (for example, −20° C. or lower) can be further improved.

In addition, vinylene carbonates, 1,3-propanesultone, diphenyl disulfide, cyclohexylbenzene, biphenyl, fluorobenzene, t-butylbenzene and the like are added to these non-aqueous electrolytes for the purpose of further improving various characteristics of the battery. Additives can be added as appropriate. Furthermore, the non-aqueous electrolyte may be gelled (gelled electrolyte) using a gelling agent such as a known polymer.

<Non-aqueous electrolyte battery>
In the non-aqueous electrolyte battery of the present embodiment, for example, the electrode body is loaded into the exterior body, and the non-aqueous electrolyte is injected into the exterior body to immerse the electrode body in the non-aqueous electrolyte. is manufactured by sealing the opening of the As the exterior body, an exterior can made of steel, aluminum, or an aluminum alloy, or an exterior body composed of a laminate film in which metal is vapor-deposited can be used.

Since the non-aqueous electrolyte battery of the present embodiment is configured with positive electrode capacity regulation, it is possible to detect the charging end time by controlling the amount of charge electricity and the control of the charging voltage. It is possible to set the charge end condition.

The assembled battery is preferably subjected to aging treatment at a relatively high temperature (for example, 60° C.) in a fully charged state. The aging treatment advances the formation of a Li—Al alloy in the negative electrode, thereby further improving the discharge capacity and output characteristics of the battery.

Next, an embodiment of a method for manufacturing a non-aqueous electrolyte battery disclosed in the present application will be described. The method for manufacturing the non-aqueous electrolyte battery of the present embodiment is a method for manufacturing the non-aqueous electrolyte battery of the above-described embodiment, in which a positive electrode mixture layer is formed on at least one surface of a positive electrode current collector, and a capacity is 0.68 mAh/cm ² or more and 4.87 mAh/cm ² or less, and the positive electrode has an area larger than that of the positive electrode mixture layer and a thickness of 30 μm or more and 150 μm. The following steps of preparing a negative electrode precursor made of an aluminum base material, and disposing the negative electrode precursor through a separator so as to cover the entire surface of the positive electrode mixture layer of the positive electrode to produce an electrode body. and charging after enclosing the electrode body and the non-aqueous electrolyte in the exterior body.

In the step of preparing the positive electrode, the positive electrode described in the non-aqueous electrolyte battery of the embodiment is prepared. In addition, in the step of preparing the negative electrode precursor, the negative electrode precursor described in the non-aqueous electrolyte battery of the embodiment is prepared. As for the separator and the non-aqueous electrolyte, the separator and the non-aqueous electrolyte described in the non-aqueous electrolyte battery of the embodiment are used.

By using an Al base material having a thickness of 30 μm or more and 150 μm or less as a negative electrode precursor and using a positive electrode having a capacity of 0.68 mAh/cm ² or more and 4.87 mAh/cm ² or less, after the initial charging (chemical conversion) step, A negative electrode having an Al layer and a Li—Al alloy layer formed on the surface of the Al layer is formed, and the tensile strength of the negative electrode can be 4 N/mm or more. Once the negative electrode is formed, even if the battery is charged and discharged again, the thickness of the Al layer constituting the negative electrode does not change significantly, and the negative electrode can maintain a constant tensile strength.

As described above, according to the manufacturing method of the present embodiment, the strength of the negative electrode can be maintained even if aluminum alone is used as the negative electrode material, and a non-aqueous electrolyte battery with high long-term reliability in a high-temperature environment can be provided.

The present invention will be described in detail below based on examples. However, the following examples do not limit the present invention.

(Example 1)
<Preparation of positive electrode>
First, a lithium-containing nickel layered oxide represented by LiNi _0.33 Co _0.33 Mn _0.33 O ₂ as a positive electrode active material: 97 parts by mass, acetylene black as a conductive aid: 1.5 parts by mass, and PVDF as a binder : 1.5 parts by mass were dispersed in NMP to prepare a positive electrode mixture-containing slurry. Next, this positive electrode mixture-containing slurry was applied to both sides of an Al foil having a thickness of 12 μm, dried, and subjected to a press treatment, so that a mass of 10 mg/cm ² per side was applied to both sides of the Al foil current collector. to form a positive electrode mixture layer. Furthermore, a strip-shaped positive electrode having a length of 974 mm and a width of 40 mm was produced by subjecting the positive electrode mixture layer to a press treatment. However, the positive electrode mixture layer is not formed on a part of the slurry application surface, and a portion where the Al foil is exposed is provided. The lead bodies were ultrasonically welded.

<Preparation of negative electrode precursor>
A strip-shaped Al foil having a thickness of 70 μm, a length of 988 mm, and a width of 44 mm was used as a negative electrode precursor. However, Ni lead bodies for conductive connection with the outside of the battery were ultrasonically welded to the ends of the Al foil.

<Preparation of electrode body>
The positive electrode and the negative electrode precursor were laminated via a separator made of a microporous PE film having a thickness of 16 μm.

<Preparation of non-aqueous electrolyte>
LiBF ₄ was dissolved at a concentration of 1.2 mol/L in a mixed solvent of propylene carbonate (PC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) at a volume ratio of 17:63:20. A nonaqueous electrolytic solution was prepared by adding tris phosphate (trimethylsilyl: TMSP) in an amount of 2% by mass.

<Battery assembly>
By enclosing the wound electrode body and the non-aqueous electrolyte in a 103450-size aluminum alloy outer can having a plate thickness of 0.8 mm, a square shaped battery with a rated capacity of 800 mAh and shown in FIGS. A non-aqueous electrolyte battery was produced.

3 and 4, FIG. 3 is a perspective view schematically showing the non-aqueous electrolyte battery of this embodiment, and FIG. 4 is a cross-sectional view taken along line II of FIG. be. In FIG. 4, the inner peripheral portion of the electrode body and the separator are not shown in cross section. In FIGS. 3 and 4, the positive electrode 1 and the negative electrode 2 are spirally wound with a separator 3 interposed therebetween, and then pressurized so as to be flattened to form a flattened wound electrode body 6, which is formed into a square (rectangular tube). type) is housed in the outer can 4 together with the non-aqueous electrolyte. However, in order to avoid complication, FIG. 4 does not show an Al foil as a current collector used in fabricating the positive electrode 1, a non-aqueous electrolyte, and the like.

The outer can 4 is made of an aluminum alloy and constitutes the outer body of the battery, and this outer can 4 also serves as a positive electrode terminal. An insulator 5 made of a polyethylene sheet is arranged at the bottom of the outer can 4, and a flat wound electrode body 6 made of the positive electrode 1, the negative electrode 2 and the separator 3 is connected to one end of each of the positive electrode 1 and the negative electrode 2. The connected positive electrode lead body 7 and negative electrode lead body 8 are pulled out. A terminal 11 made of stainless steel is attached to a cover plate 9 made of aluminum alloy for sealing the opening of the outer can 4 via an insulating packing 10 made of polypropylene. A lead plate 13 made of stainless steel is attached via the .

The cover plate 9 is inserted into the opening of the outer can 4 and welded together to seal the opening of the outer can 4 and hermetically seal the inside of the battery. A non-aqueous electrolyte injection port 14 is provided in the cover plate 9, and the non-aqueous electrolyte injection port 14 is welded and sealed with a sealing member inserted thereinto to provide airtightness of the battery. is ensured. Further, the cover plate 9 is provided with a splitting vent 15 as a mechanism for discharging internal gas to the outside when the temperature of the battery rises.

(Example 2)
A non-aqueous electrolyte battery was fabricated in the same manner as in Example 1, except that an Al foil having a thickness of 38 μm, a length of 988 mm, and a width of 44 mm was used as the negative electrode precursor.

(Example 3)
An Al foil having a thickness of 56 μm, a length of 988 mm, and a width of 44 mm was used as the negative electrode precursor. A positive electrode was prepared in the same manner as in Example 1, except that a positive electrode material mixture layer having a mass of 25 mg/cm ² per side was formed on both sides of the Al foil current collector. A non-aqueous electrolyte battery was produced in the same manner as in Example 1, except that the above negative electrode precursor and the above positive electrode were used.

(Example 4)
In the same manner as in Example 1, except that 97 parts by mass of a lithium-containing nickel layered oxide represented by LiNi _0.80 Co _0.15 Al _0.05 O ₂ was used as the positive electrode active material instead of the positive electrode active material of Example 1. A positive electrode was produced. A non-aqueous electrolyte battery was produced in the same manner as in Example 1, except that this positive electrode was used.

(Example 5)
In the same manner as in Example 1, except that 97 parts by mass of a lithium-containing nickel layered oxide represented by LiNi _0.5 Co _0.2 Mn _0.3 O ₂ was used as the positive electrode active material instead of the positive electrode active material of Example 1. A positive electrode was produced. A non-aqueous electrolyte battery was produced in the same manner as in Example 1, except that this positive electrode was used.

(Example 6)
A positive electrode was produced in the same manner as in Example 1, except that 97 parts by mass of a lithium-containing composite oxide represented by LiCoO ₂ was used as the positive electrode active material instead of the positive electrode active material of Example 1. A non-aqueous electrolyte battery was produced in the same manner as in Example 1, except that this positive electrode was used.

(Example 7)
A positive electrode was produced in the same manner as in Example 1, except that 97 parts by mass of a lithium-containing composite oxide represented by LiMn ₂ O ₄ was used as the positive electrode active material instead of the positive electrode active material of Example 1. A non-aqueous electrolyte battery was produced in the same manner as in Example 1, except that this positive electrode was used.

(Example 8)
An Al foil having a thickness of 31 μm, a length of 988 mm, and a width of 44 mm was used as the negative electrode precursor. Further, instead of the positive electrode active material of Example 1, 97 parts by mass of a lithium-containing composite oxide represented by LiMn ₂ O ₄ was used as a positive electrode active material, and 7 mg per side was applied to both sides of the Al foil current collector. A positive electrode was produced in the same manner as in Example 1, except that the positive electrode mixture layer having a mass of 1/cm ² was formed. A non-aqueous electrolyte battery was produced in the same manner as in Example 1, except that the above negative electrode precursor and the above positive electrode were used.

(Example 9)
Instead of the positive electrode active material of Example 1, 97 parts by mass of a lithium-containing composite oxide represented by LiNi _0.80 Co _0.15 Al _0.05 O ₂ was used as a positive electrode active material. A positive electrode was produced in the same manner as in Example 1, except that the positive electrode mixture layer having a mass of 30 mg/cm ² was formed. A non-aqueous electrolyte battery was produced in the same manner as in Example 1, except that this positive electrode was used.

(Comparative example 1)
A non-aqueous electrolyte battery was fabricated in the same manner as in Example 1, except that an Al foil having a thickness of 25 μm, a length of 988 mm, and a width of 44 mm was used as the negative electrode precursor.

(Comparative example 2)
An Al foil having a thickness of 60 μm, a length of 988 mm, and a width of 44 mm was used as the negative electrode precursor. A positive electrode was produced in the same manner as in Example 1, except that a positive electrode material mixture layer having a mass of 40 mg/cm ² per side was formed on both sides of the Al foil current collector. A non-aqueous electrolyte battery was produced in the same manner as in Example 1, except that the above negative electrode precursor and the above positive electrode were used.

(Comparative Example 3)
An Al foil having a thickness of 40 μm, a length of 988 mm, and a width of 44 mm was used as the negative electrode precursor. A positive electrode was produced in the same manner as in Example 1, except that a positive electrode material mixture layer having a mass of 20 mg/cm ² per side was formed on both sides of the Al foil current collector. A non-aqueous electrolyte battery was produced in the same manner as in Example 1, except that the above negative electrode precursor and the above positive electrode were used.

Table 1 shows the configurations of the positive electrodes of the nonaqueous electrolyte batteries of Examples 1 to 9 and Comparative Examples 1 to 3.

The nonaqueous electrolyte batteries of Examples 1 to 9 and Comparative Examples 1 to 3 were evaluated for positive electrode capacity, negative electrode tensile strength, and high-temperature storage characteristics.

<Positive electrode capacity>
Each battery of Examples and Comparative Examples was subjected to initial charging (formation) at a constant current (100 mA)/constant voltage (3.8 V), and when the charging current decreased to 10 mA, charging was stopped and the battery was fully charged. did. Next, each battery was disassembled, the positive electrode was taken out, the positive electrode mixture layer on one side of the taken-out positive electrode was removed, and the positive electrode mixture layer portion of the positive electrode from which the positive electrode mixture layer was removed from the one side was 1 cm ² . It was cut out to a size and used as a positive electrode capacity measurement sample. Subsequently, a model cell was produced by combining the positive electrode capacity measurement sample and a Li foil. As the non-aqueous electrolyte for this model cell, the same non-aqueous electrolyte as used in each battery was used. Next, this model cell is charged at a constant current of 0.25 mA to 4.15 V, which is the initial charging voltage of 3.8 V for each battery plus 0.35 V. Constant voltage charging was performed until the current dropped to 0.025 mA. Thereafter, the battery was discharged at a constant current of 0.25 mA until it reached 3 V, and the capacity at that time was taken as the capacity of the positive electrode.

<Tensile strength of negative electrode>
Each battery of Examples and Comparative Examples was subjected to initial charging (formation) at a constant current (100 mA)/constant voltage (3.8 V), and when the charging current decreased to 10 mA, charging was stopped and the battery was fully charged. did. Each fully charged battery was disassembled, the negative electrode was taken out, and the negative electrode was cut into a rectangular shape of 10 mm×50 mm to obtain a test piece. This test piece was attached to a tensile tester "SDT-52 type" (product name) manufactured by Imada Seisakusho Co., Ltd. with a chuck-to-chuck distance of 30 mm, and a tensile test was performed at a crosshead speed of 10 mm / min to measure the tensile strength. .

<High temperature storage characteristics>
Each battery of Examples and Comparative Examples was subjected to initial charging (formation) at a constant current (100 mA)/constant voltage (3.8 V), and when the charging current decreased to 10 mA, charging was stopped and the battery was fully charged. did. Each fully charged battery was discharged at a constant current of 2000 mA to 2.0 V, and the initial discharge capacity was determined.

Next, each battery fully charged under the same conditions as the initial charge was stored at 100° C. for 150 days. After that, the batteries were brought into a fully charged state under the same conditions as those described above, and discharged at a constant current of 2000 mA to 2.0 V in an environment of 20° C., and the post-storage discharge capacity was determined.

Subsequently, the capacity retention rate after storage was calculated by the following formula, and the high-temperature storage characteristics were evaluated according to the following evaluation criteria.
Capacity retention rate (%) = (post-storage discharge capacity/initial discharge capacity) x 100
When the capacity retention rate is 70% or more: Excellent high-temperature storage characteristics (○)
When the capacity retention rate is 50 to 69%: High temperature storage characteristics are good (△)
If the capacity retention rate is 49% or less: Poor high-temperature storage characteristics (x)

Table 2 shows the above evaluation results.

From Table 2, the batteries of Examples 1 to 9 in which the tensile strength of the negative electrode was 4 N/mm or more can be evaluated as excellent or good in high-temperature storage characteristics, and have high long-term reliability in high-temperature environments. It can be seen that the battery has been realized. On the other hand, in the batteries of Comparative Examples 1 to 3, in which the tensile strength of the negative electrode was less than 4 N/mm, the evaluation of the high-temperature storage characteristics was poor, indicating that the high-temperature storage characteristics were poor.

The non-aqueous electrolyte battery disclosed in this application has high long-term reliability in a high-temperature environment. It can be preferably applied to applications that require good retention of capacity over a long period of time in an environment.

REFERENCE SIGNS LIST 1 positive electrode 2 negative electrode 3 separator 4 outer can 5 insulator 6 wound electrode member 7 positive electrode lead member 8 negative electrode lead member 9 cover plate 10 insulating packing 11 terminal 12 insulator 13 lead plate 14 non-aqueous electrolyte inlet 15 cleavage vent 100 Al base material (negative electrode precursor)
200 negative electrode 201 Al layer 202 Li—Al alloy layer

Claims (10)

A non-aqueous electrolyte battery comprising a positive electrode, a negative electrode, a non-aqueous electrolyte and a separator,
The positive electrode includes a positive electrode current collector and a positive electrode mixture layer formed on the positive electrode current collector,
The positive electrode mixture layer is capable of intercalating and deintercalating Li ions,
The area of the negative electrode is larger than the area of the positive electrode mixture layer of the positive electrode, and the negative electrode is arranged to cover the entire surface of the positive electrode mixture layer with the separator interposed therebetween,
The negative electrode includes an Al layer and a Li—Al alloy layer formed on the surface of the Al layer,
The tensile strength of the negative electrode is 4 N / mm or more,
The maximum thickness of the Al layer is 30 μm or more and 150 μm or less,
the capacity of the positive electrode is 0.68 mAh/cm ² or more and 4.87 mAh/cm ² or less;
The positive electrode mixture layer contains, as a positive electrode active material, at least one selected from the group consisting of lithium cobalt oxide, lithium manganese oxide and lithium-containing composite oxides having an olivine structure. liquid battery. The positive electrode mixture layer is formed on at least one side of the positive electrode current collector,
2. The non-aqueous electrolyte battery according to claim 1, wherein the mass of said positive electrode mixture layer per one side of said positive electrode current collector is 7 mg/cm< ² > or more and 30 mg/cm< ² > or less. the positive electrode, the negative electrode and the separator form a wound electrode body;
3. The non-aqueous electrolyte battery according to claim 1, wherein the wound electrode body is enclosed in a square outer package. The non-aqueous electrolytic solution according to any one of claims 1 to 3, wherein the non-aqueous electrolytic solution further contains a phosphoric acid compound or a boric acid compound having a group represented by the following general formula (2) in the molecule. battery.

In the general formula (2), X is Si, Ge or Sn, and R ¹ , R ² and R ³ are each independently an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms or It represents an aryl group having 6 to 10 carbon atoms, and some or all of the hydrogen atoms may be substituted with fluorine. 5. The non-aqueous electrolyte battery according to claim 4, wherein the non-aqueous electrolyte contains tris(trimethylsilyl) phosphate as the phosphoric acid compound having the group represented by the general formula (2) in the molecule. 5. The non-aqueous electrolyte battery according to claim 4, wherein the non-aqueous electrolyte contains tris(trimethylsilyl) borate as the boric acid compound having the group represented by the general formula (2) in the molecule. 7. The non-aqueous electrolyte battery according to claim 1, wherein the non-aqueous electrolyte contains LiBF ₄ as a lithium salt, propylene carbonate as an organic solvent, and a nitrile compound. 8. The non-aqueous electrolyte battery according to claim 7, wherein said non-aqueous electrolyte contains at least one selected from the group consisting of suberonitrile, pimelonitrile and adiponitrile as said nitrile compound. 9. The non-aqueous electrolyte battery according to claim 7, wherein the content of said nitrile compound in said non-aqueous electrolyte is 0.1% by mass or more and 10% by mass or less. A method for manufacturing the non-aqueous electrolyte battery according to any one of claims 1 to 9,
preparing a positive electrode having a positive electrode mixture layer formed on at least one side of a positive electrode current collector and having a capacity of 0.68 mAh/cm ² or more and 4.87 mAh/cm ² or less;
preparing a negative electrode precursor made of an aluminum base material having an area larger than that of the positive electrode mixture layer of the positive electrode and having a thickness of 30 μm or more and 150 μm or less;
disposing the negative electrode precursor so as to cover the entire surface of the positive electrode mixture layer of the positive electrode with a separator interposed therebetween to produce an electrode assembly;
A method for manufacturing a non-aqueous electrolyte battery, comprising the step of charging the battery after the electrode body and the non-aqueous electrolyte are enclosed in an outer package.

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