JP7069189B2 - Non-water secondary battery, non-water electrolyte used for it, and method for manufacturing the non-water secondary battery. - Google Patents

Description

The present invention relates to a non-aqueous secondary battery, a non-aqueous electrolytic solution used thereof, and a method for manufacturing the non-aqueous secondary battery.

In recent years, with the development of portable electronic devices such as mobile phones and notebook personal computers and the practical application of electric vehicles, small and lightweight secondary batteries with high capacity and high energy density have been required. It's coming.

Currently, in non-aqueous secondary batteries that can meet this demand, especially lithium ion batteries, the positive electrode active materials are lithium cobaltate (Li _x CoO ₂ ), lithium nickelate (Li _x NiO ₂ ), and nickel-cobalt-lithium manganate. Using a lithium-containing composite oxide such as (Li _x Ni _y1 Co _y2 Mn _y3 O ₂ : 0.9 <x <1.1, 0 <y1 to 3 <1, y1 + y2 + y3 = 1) or a composite or mixture thereof. , Graphite or the like is used as the negative electrode active material. With the further development of equipment to which non-water secondary batteries are applied, further increase in capacity and energy density of non-water secondary batteries is required.

One of the methods for increasing the capacity and energy density of the non-aqueous secondary battery is to charge the positive electrode active material at a high voltage and use it. However, with the increase in energy density and voltage of non-aqueous secondary batteries, the deterioration of the charge / discharge cycle characteristics of the batteries has become remarkable.

Conventionally, in order to suppress deterioration of charge / discharge cycle characteristics under high voltage, it has been proposed to dissolve a dissimilar metal in a positive electrode active material and coat the surface of the positive electrode with a metal oxide. There is a problem that the stability is poor and the coating is deteriorated due to the interaction between the coating and the electrolytic solution. Further, for the same purpose, various studies have been made on coating the surface of the positive electrode with an organic substance, an alkali metal salt, or an alkaline earth salt. However, in the case of a film made of an organic compound, in general, it cannot be used as a film for high voltage unless the film is formed by using a high voltage resistant material such as a fluorine compound. Further, since the film made of an organic compound is easily swollen by the electrolytic solution, it is considered that the film effect of blocking the electrolytic solution and the positive electrode is low. Further, when the coating is formed of an alkali metal salt or an alkaline earth salt, the coating film easily dissolves in the electrolytic solution, and the coating film easily absorbs the electrolytic solution, both of which have a problem that the coating effect is deteriorated.

For example, Non-Patent Document 1 describes an example in which a positive electrode active material is coated with an inorganic oxide. As a result, side reactions of the active material can be suppressed, but the electron conductivity on the surface of the active material may be impaired. Patent Document 1 describes an example in which the surface of an active material is coated with a polyvalent fluorine-containing organic lithium salt, and by coating with a fluorine compound resistant to a high voltage, the surface of the active material is coated under a high voltage of an electrolytic solution. Although the reaction is suppressed, it is not a simple method and there is concern about an increase in resistance. Patent Document 2 proposes adding a protective film material to the positive electrode paint to form a heat-operated protective film on the surface of the positive electrode material to improve the safety of the battery. Since it is added, there is a concern that the resistance of the electrode will increase. Patent Document 3 proposes to form a porous protective film on the surface of the electrode (particularly the negative electrode), but it is considered that the porous protective film is less effective in suppressing the reaction between the electrolytic solution and the positive electrode. Further, Patent Document 3 does not describe a specific example of forming a protective film on the surface of the positive electrode.

In addition, various electrolytic solution additives have been studied in order to ensure safety. Cyclohexylbenzene, biphenyl, etc. are typical examples, but in the type of battery that can be charged up to a high voltage of about 4.35V, the additive reacts even in the normal state of charge, and in practice, they are used. In many cases, additives cannot be used. Further, even in the normal 4.2 V charge, a part of the additive reacts and affects the battery performance. Therefore, there is a need for an electrolytic solution additive that can be used even under high voltage and can ensure safety.

Patent Document 4 proposes a non-aqueous secondary battery that can be used even under a high voltage, and describes that a compound having two or more nitrile groups in the molecule is used as an electrolyte solution additive for the battery. Specifically, it is described that a dinitrile such as succinonitrile is used. On the other hand, in Patent Document 4, the addition amount of the compound having two or more nitrile groups in the molecule is preferably 1% by mass or less in consideration of the reactivity of the electrode.

Further, Patent Document 5 proposes a non-aqueous electrolytic solution secondary battery using dinitrile such as glutaronitrile as an electrolytic solution additive at a high concentration. Although Patent Document 5 describes the improvement of charge / discharge cycle characteristics, the charge / discharge cycle characteristics are evaluated using lithium metal as a counter electrode, and there is a problem in the reaction of the negative electrode. In general, nitriles have the effect of suppressing battery swelling, but there is a problem with the reactivity of the negative electrode, and our study also shows that there is a problem with the charge / discharge cycle characteristics.

Japanese Unexamined Patent Publication No. 2012-243696 Japanese Unexamined Patent Publication No. 2010-157512 Japanese Unexamined Patent Publication No. 2009-301765 Japanese Unexamined Patent Publication No. 2008-108586 Japanese Unexamined Patent Publication No. 9-161845

Y. J. Kim et al., Journal of The Electrical Society, 150 (12), A1723-A1725 (2003)

The present invention solves the above problems and provides a non-aqueous secondary battery having excellent charge / discharge cycle characteristics at a high voltage, a non-aqueous electrolytic solution used thereof, and a method for manufacturing the non-aqueous secondary battery. Is.

The first non-aqueous secondary battery of the present invention is a non-aqueous secondary battery containing a positive electrode, a negative electrode and a non-aqueous electrolytic solution, and the surface of the positive electrode is at least selected from component 1, component 2 and component 3. It is coated with one component, wherein the component 1 is a sugar-like compound, the component 2 is a metal salt, and the component 3 is a nitrogen-containing compound.

The second non-aqueous secondary battery of the present invention is a non-aqueous secondary battery containing a positive electrode, a negative electrode and a non-aqueous electrolytic solution, wherein the non-aqueous electrolytic solution or the positive electrode contains a fluorine-containing compound or a carbonic acid compound. The non-aqueous electrolytic solution contains an additive other than vinylene carbonate, and the concentration of the additive in the non-aqueous electrolytic solution is 0.05% by mass or more and 3% by mass or less.

Further, the non-aqueous electrolytic solution of the present invention is the non-aqueous electrolytic solution used for the non-aqueous secondary battery of the present invention, and is characterized by containing at least one selected from a fluorine-containing compound and a carbon dioxide compound.

Further, the method for producing the first non-aqueous secondary battery of the present invention is the method for producing the non-aqueous secondary battery of the present invention, and at least one component selected from the component 1, the component 2 and the component 3 is used. Including a step of preparing a treatment liquid containing the above, and a step of applying the treatment liquid to the surface of the positive electrode, the component 1 is a sugar-like compound, the component 2 is a metal salt, and the component 3 is. , A nitrogen-containing compound, wherein the positive electrode is a positive electrode after a press treatment.

Further, the method for manufacturing the second non-aqueous secondary battery of the present invention is the method for manufacturing the non-aqueous secondary battery of the present invention, and at least one component selected from the component 1, the component 2 and the component 3 is used. A step of preparing a non-aqueous electrolytic solution containing the above, a step of assembling a battery using the positive electrode, a negative electrode and the non-aqueous electrolytic solution, and a step of charging and discharging the assembled battery, wherein the component 1 is similar to sugar. It is a compound, wherein the component 2 is a metal salt, and the component 3 is a nitrogen-containing compound.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a non-aqueous secondary battery having excellent charge / discharge cycle characteristics at a high voltage, a non-aqueous electrolytic solution used thereof, and a method for manufacturing the non-aqueous secondary battery.

FIG. 1 is a plan view showing an example of a non-aqueous secondary battery.

(First Embodiment of Non-Water Secondary Battery)
A first embodiment of the non-aqueous secondary battery of the present invention comprises a positive electrode, a negative electrode and a non-aqueous electrolytic solution, and the surface of the positive electrode is coated with at least one component selected from component 1, component 2 and component 3. The above component 1 is a sugar-like compound, the above component 2 is a metal salt, and the above component 3 is a nitrogen-containing compound.

By coating the surface of the positive electrode with the above components, a stable film can be formed on the surface of the positive electrode even under high voltage, the contact between the positive electrode and the non-aqueous electrolyte solution is reduced, and the charge / discharge cycle under high voltage is performed. The characteristics can be improved.

Further, while considering coating the surface of the positive electrode with the above components, the present inventors can further improve the additive effect of the electrolytic solution by making the surface of the positive electrode a specific surface state, which is highly effective. It was confirmed that the charge / discharge cycle characteristics under voltage can be reliably improved. Specifically, the positive electrode after charging the battery to 4.5 V with a current of 1 / 3C and then discharging to 3 V with a current of 1 / 3C is washed with methyl ethyl carbonate and then vacuum-dried. When the surface of the positive electrode is analyzed by X-ray photoelectron spectroscopic analysis, the content ratio of oxygen atoms on the surface of the positive electrode is Ro (atomic%), the content ratio of fluorine atoms is Rf (atomic%), and the bond energy of 1s orbitals. When the content ratio of carbon atoms of 289 to 291 eV is Rc (atomic%), Rf / Ro is 0.05 or more and 1.3 or less, or Rc / Ro is 0.05 or more and 0.75 or less. It turned out that the surface condition was preferable.

Hereinafter, each element of the present embodiment will be described in detail.

<Ingredient 1, Ingredient 2 and Ingredient 3>
When the charging voltage of a battery exceeds 4.2 V based on lithium, a high voltage resistant fluorine-based compound or the like, which is difficult to react under high voltage, has been often used as a substance to be contained in an electrolytic solution or an electrode. .. On the other hand, as a result of the studies by the present inventors, compounds containing nitrogen atoms that easily react at high voltage and polymers having OH groups, which have been considered undesired to be used in batteries, are also under high voltage. It was found that it is highly effective in improving the charge / discharge cycle characteristics in. Specifically, it is a sugar-like compound (component 1), a metal salt (component 2), and a nitrogen-containing compound (component 3). In particular, many sugar-like compounds (component 1) have an OH group, and nitrogen-containing compounds (component 3) have a nitrogen atom portion that is vulnerable to oxidation, and are conventionally used under high voltage. It is not normally used with a positive electrode. However, as a result of deliberately examining substances that are not normally used in high-voltage rechargeable batteries, the present inventors have confirmed that they are effective in improving charge / discharge cycle characteristics under high voltage. The above components 1 to 3 are effective when they are contained in the positive electrode as other than the binder, but are particularly effective when they are present in a large amount on the surface of the positive electrode, and the surface of the positive electrode is selected from component 1, component 2 and component 3. It is most effective to cover with at least one component. Further, the specific substances corresponding to the components 1 to 3 are preferably one substance classified into a plurality of components. For example, magnesium lignin sulfonate is a sugar-like compound (component 1) and is classified into a plurality of components. Since it is also a metal salt (component 2), it is a preferable component.

[Ingredient 1]
The above component 1 is a sugar-like compound. The sugar analogs include sugars and related substances. The saccharides include monosaccharides such as glucose, polysaccharides such as sucrose, starch, amylose, amylopectin, glycogen, cellulose, pectin, glucomannan and the like. In addition, α-, β-, γ-cyclodextrin, deoxyribose, fucose, rhamnose, glucuronic acid, galacturonic acid, glucosamine, galactosamine, glycerin, xylitol, sorbitol, ascorbic acid (vitamin C), glucuronolactone, gluconolactone. Etc. are also included in sugars. Further, the substances related to the saccharide include lignin, a lignin derivative, alginate, alginate and the like which are compounds having a plurality of OH groups, and the compound having a plurality of OH groups also includes carboxymethyl cellulose, hydroxymethyl cellulose and the like. ..

As the saccharide, a polysaccharide such as sucrose is desirable, and as the compound having a plurality of OH groups, carboxymethyl cellulose, hydroxymethyl cellulose, lignin compound (lignin, lignin derivative), alginate, and alginate are desirable.

The molecular weight of the sugar-like compound is preferably 200 or more, more preferably 500 or more, and most preferably 1000 or more so that it is difficult to dissolve in the electrolytic solution.

It is not clear why a compound having an originally unstable OH group is effective at a high voltage as the above component, but it is said that the change in the molecular state due to the high voltage and the hydrogen bond between the molecules are acting. Conceivable. Further, it is desirable that the above components do not contain a fluorine atom. This is because if a fluorine atom is contained in the above-mentioned component, the coating material tends to dissolve or swell, and the protective effect of the positive electrode tends to decrease.

[Ingredient 2]
The component 2 is a metal salt, preferably an alkali metal salt or an alkaline earth metal salt, and more preferably a magnesium salt or a sodium salt. In addition, phosphorus-based salts, sulfates, and carboxylates are desirable, and phosphorus-based salts are particularly desirable. Examples of the phosphorus-based salt include monofluorophosphate ( _MA2 PO _{3 F} ), metaphosphate ((MA PO ₃ ) _n ), and pyrophosphate ( _MA4 P ₂ O ₇ ). .. _MA in the above chemical formula indicates a metal element and has a valence of 1 to 3.

Further, as the component 2, a polyate salt is also desirable. The above-mentioned polyate is a name indicating a salt containing a molecule whose chemical formula is represented by [M _x O _y ] ^n- (M is Mo, V, W, Ti, Al, Nb, etc.). Examples thereof include salts such as tungstic acid, molybdic acid, vanadic acid and manganese acid. It is considered that the above-mentioned phosphorus-based salts and polypeptides are desirable because they are stable even at high voltage and are difficult to dissolve in the electrolytic solution.

[Ingredient 3]
The component 3 is a nitrogen-containing compound. It is desirable that the nitrogen-containing compound is partially salted. This makes the nitrogen-containing compound water-soluble and facilitates electrode treatment. Normally, nitrogen-containing compounds are thought to be vulnerable to high voltages and prone to battery deterioration. However, although many nitrogen-containing compounds are likely to react at high voltages, they often exhibit a good coating effect after the reaction.

Examples of the nitrogen-containing compound include amines, amides, imides, amino acids, proteins and the like. On the other hand, the nitrogen-containing compound may not have a sufficient coating effect when dissolved in a non-aqueous electrolyte solution. Therefore, the compound may be salted so as to be difficult to dissolve or have a molecular weight of 200 or more. Desirable, more preferably salt. The anionic portion of the nitrogen-containing compound salt is preferably a carboxylic acid group, a sulfonic acid group, or a phosphoric acid group. Examples of the nitrogen-containing compound salt include diethylenetriamine pentaacetic acid salts such as diethylenetriamine pentaacetic acid pentaacetate, ethylenediamine tetraacetate salts such as ethylenediamine tetraacetate tetraacetic acid, other magnesium salts, and polypeptides such as polyglutamate sodium and the like. Examples thereof include salts, proteins, asparagates, sodium hyaluronate (derived from chicken crown), polyimide salts, polyamide salts, polyallylamine and the like. It is desirable that the compound has a plurality of salt portions in one molecule, more preferably four or more salt portions, and most preferably five or more. The nitrogen-containing compound salt is more preferably an acetate of an amine.

Further, it is desirable that the above components do not contain a fluorine atom. This is because if a fluorine atom is contained in the above-mentioned component, the coating material tends to dissolve or swell, and the protective effect of the positive electrode tends to decrease.

[Covering of positive electrode]
It is desirable that the positive electrode is coated with at least the components 1 to 3 as the main components. An insulating material such as alumina or an additive can be added as a sub-component, but if the amount of the sub-component increases, the electrolytic solution may infiltrate from the sub-component portion and the protective effect of the coating may be impaired. A specific method for coating the positive electrode can be performed by applying a treatment liquid containing at least the above components 1 to 3 to the surface of the positive electrode. In that case, the ratio of the components 1 to 3 in the solid content in the treatment liquid is preferably 50% by mass or more, more preferably 70% by mass or more, and most preferably 90% by mass or more.

Further, as another coating method for the positive electrode, the above components 1 to 3 are contained in the positive electrode active material, or the above components 1 to 3 are contained in the non-aqueous electrolyte solution to assemble the battery, and then the battery is assembled. There is a method of charging and discharging.

Regardless of the method for coating the positive electrode, it is desirable to form the film on the positive electrode after the press treatment from the viewpoint of ensuring the electron conduction of the positive electrode and preventing the film from being destroyed.

<Surface condition of positive electrode>
As described above, the surface condition of the positive electrode is that the positive electrode is charged with a current of 1 / 3C to 4.5V and then discharged to 3V with a current of 1 / 3C, and then the positive electrode is washed with methyl ethyl carbonate. After vacuum drying, when the surface of the positive electrode is then analyzed by X-ray photoelectron spectroscopy (XPS), the content of oxygen atoms on the surface of the positive electrode is Ro (atomic%), and the content of fluorine atoms is determined. Assuming that the content ratio of carbon atoms with Rf (atomic%) and 1s orbital bond energy of 289 to 291 eV is Rc (atomic%), Rf / Ro is 0.05 or more and 1.3 or less, or Rc / Ro. Refers to the surface condition of the positive electrode in which is 0.05 or more and 0.75 or less. In the surface state of the positive electrode, it is considered that some kind of film is formed on the surface of the positive electrode. The film may be formed by the action of coating the positive electrode with the above-mentioned components 1 to 3, or may be formed by the action of a specific component or a specific additive contained in the non-aqueous electrolytic solution described later.

The Rf / Ro is preferably 0.05 or more, more preferably 0.1 or more, preferably 1.3 or less, more preferably 1.0 or less, and most preferably 0.5 or less. The Rc / Ro is preferably 0.05 or more, more preferably 0.1 or more, preferably 0.75 or less, more preferably 0.6 or less, and most preferably 0.5 or less. If these values are too large, the electrode protection performance of the formed film tends to be low, and if they are too small, the electrode protection performance tends to be high, but the electrical characteristics tend to deteriorate due to the increase in resistance.

It is under consideration why the Rf / Ro and the Rc / Ro should be within the above range, but the surface of the positive electrode is formed in a state containing various oxygen-containing compounds (for example, active). Oxygen of substances, oxygen of electrolyte decomposition products, etc.). Oxygen content is also the second highest after carbon, while oxygen is an important element for ion movement and electrode protection. For example, in the case of a metal oxide positive electrode, oxygen is a constituent element of the active material and is involved in ion transport and reactivity. The product formed on the surface of the positive electrode is also an important component for film formation and its formation reaction of carbonic acid compounds (carbonates, carbonic acid esters, etc.), phosphoric acid compounds, sulfuric acid compounds, alcoholates, ether compounds and the like.

Here, the fact that the Rf / Ro and the Rc / Ro are within the above ranges means that a good protective film is formed on the surface of the positive electrode in a specific state, and carbon atoms having a 1s orbital bonding energy of 289 to 291 eV are formed. It is considered to mean that it is possible to suppress the formation of products on the surface of the positive electrode due to the decomposition of the electrolytic solution such as the carbon-containing compound or the fluorine compound contained therein. That is, the carbon-containing compound is considered to be mainly a carbonic acid compound, and CO ₂ may be generated under a high voltage, so it is not desirable if the amount is too large. Further, the fluorine present on the surface of the positive electrode is derived from the fluorine compound component such as LiPF ₆ in the electrolytic solution and the fluorine compound component contained in the positive electrode, but if this fluorine is abundant on the surface of the positive electrode, Li ions enter and exit. It becomes difficult to do so, the battery characteristics are deteriorated, a non-uniform reaction occurs, and the high voltage cycle characteristics may be deteriorated. On the other hand, since the carbon-containing compound and the fluorine compound are involved in electrode protection and ion transport, it is presumed that the absence of a small amount affects the electrical characteristics.

When the positive electrode is in the surface state, the total content of cobalt (Co), nickel (Ni), manganese (Mn) and iron (Fe) on the surface of the positive electrode is reduced by the formation of the film. If it drops too much, the electrical characteristics will be impaired. Therefore, when the surface of the positive electrode is analyzed by XPS, the total content of Co, Ni, Mn and Fe on the surface of the positive electrode is preferably 0.1 atomic% or more, more preferably 0.2 atomic% or more. , 0.5 atomic% or more is most preferable, 15 atomic% or less is preferable, 5 atomic% or less is more preferable, and 3 atomic% or less is most preferable.

When the positive electrode is coated with the above-mentioned phosphorus-based salt, sulfate, polypeptide, nitrogen-containing compound, etc., phosphorus (P), sulfur (S), and metal components (Mo, V, W) on the surface of the positive electrode are used. , Ti, Al, Nb, etc.), and nitrogen (N) are preferably in a specific range.

Specifically, when the surface of the positive electrode is analyzed by XPS, the content ratios of S, metal components (Mo, V, W, Ti, Al, Nb, etc.) and N are preferably 0.1 atomic% or more. 0.2 atomic% or more is more desirable, 0.5 atomic% or more is most desirable, 1 atomic% or less is desirable, and 0.5 atomic% or less is more desirable. Similarly, the content ratio of P atom is preferably 0.5 atom% or more, more preferably 1 atom% or more, most preferably 2% atom or more, and preferably 10 atom% or less, and 5 atom% or less. More desirable. If these values are too large, the electrode protection performance of the formed film tends to be low, and if they are too small, the electrode protection performance tends to be high, but the electrical characteristics tend to deteriorate due to the increase in resistance.

As described above, in the XPS analysis of the surface of the positive electrode, the positive electrode after charging the battery to 4.5 V with a current of 1 / 3C and then discharging to 3 V with a current of 1 / 3C was washed with methyl ethyl carbonate. Although it is performed after vacuum drying later, the cleaning of the positive electrode is usually performed in an inert atmosphere. As the XPS measuring device, for example, an XPS measuring device "AXIS-NOVA" manufactured by Kratos is used, and monochromatic AlKα (1486.6 eV) is used as an X-ray source, and observation is performed in an analysis area of 700 μm × 300 μm. When setting the sample in the above device, it is preferable to use a transfer vessel so that the sample is kept out of contact with water as much as possible.

Next, each element of the non-aqueous secondary battery of the present embodiment will be described by exemplifying a typical lithium ion battery. The lithium ion battery includes a positive electrode, a negative electrode, a non-aqueous electrolytic solution, and a separator.

<Positive electrode>
As the positive electrode, for example, a structure having a positive electrode mixture layer containing a positive electrode active material, a conductive auxiliary agent, a binder and the like on one or both sides of a current collector can be used.

As the positive electrode active material, a lithium-containing transition metal oxide or the like that can occlude and release lithium ions is used. Examples of the lithium-containing transition metal oxide include those used in conventionally known lithium ion batteries. Specifically, Li _y CoO ₂ (where 0 ≦ y ≦ 1.1), Li _z NiO ₂ (where 0 ≦ z ≦ 1.1), Li _p MnO ₂ (where 0 ≦ z ≦ 1.1). 0 ≦ p ≦ 1.1), Li _q Cor M ² _{1-r O 2} (However, M ² is derived from Mg, Mn, Fe, Ni, Cu, Zn, Al, Ti, Ge and Cr. It is at least one metal element selected from the group consisting of 0 ≦ q ≦ 1.1 and 0 <r <1.0), Li _s Ni _1-t M ³ _t O ₂ (where M). Reference numeral ³ is at least one metal element selected from the group consisting of Mg, Mn, Fe, Co, Cu, Zn, Al, Ti, Ge and Cr, and 0 ≦ s ≦ 1.1, 0 <t <. 1.0), Li _f Mn _v Ni _w Co _1-vw O ₂ (However, 0 ≦ f ≦ 1.1, 0 <v <1.0, 0 <w <1.0). Examples thereof include lithium-containing transition metal oxides having a layered structure such as, and only one of these may be used, or two or more thereof may be used in combination.

As the binder, for example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylic acid salt, polyimide, polyamideimide and the like are preferably used. ..

The conductive auxiliary agent includes, for example, natural graphite (scaly graphite, etc.), graphite such as artificial graphite (graphitic carbon material); acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black. Carbon black such as; carbon fiber; carbon material such as, etc. may be mentioned.

For the positive electrode, for example, a paste-like or slurry-like positive electrode mixture-containing paint in which the positive electrode active material, the binder, and the conductive auxiliary agent are dispersed in a solvent such as N-methyl-2-pyrrolidone (NMP) is prepared. Then, this is applied to one side or both sides of the current collector, dried, and then pressed if necessary. However, the positive electrode is not limited to the one manufactured by the above manufacturing method, and may be manufactured by another manufacturing method.

The thickness of the positive electrode mixture layer is preferably, for example, 10 to 100 μm per one side of the current collector. The density of the positive electrode mixture layer is calculated from the mass and thickness of the positive electrode mixture layer per unit area laminated on the current collector, and is preferably 3.0 to 4.5 g / cm ³ . The composition of the positive electrode mixture layer is, for example, preferably 60 to 95% by mass of the positive electrode active material, preferably 1 to 15% by mass of the binder, and the amount of the conductive auxiliary agent. It is preferably 3 to 20% by mass.

When the surface of the positive electrode is coated with a treatment liquid containing at least the above-mentioned components 1 to 3, the porosity of the positive electrode mixture layer is preferably 22% or more, and 25% or more. More desirable, 28% or more is most desirable, 35% or less is desirable, 32% or less is more desirable, and 29% or less is most desirable. This is because if the porosity of the positive electrode mixture layer is too large, most of the treatment liquid infiltrates into the inside of the positive electrode and the coating effect on the surface is lowered, and if it is too small, the coating formed by the components is formed. Is limited to the surface, and the coating strength is lowered.

As the current collector of the positive electrode, the same one as that used for the positive electrode of a conventionally known lithium ion battery can be used, and it is made of, for example, aluminum, stainless steel, nickel, titanium or an alloy thereof. Examples thereof include foils, punched metals, expanded metals, nets and the like, and aluminum foils having a thickness of 10 to 30 μm are usually preferably used.

<Negative electrode>
As the negative electrode, for example, a structure having a negative electrode mixture layer containing a negative electrode active material, a binder and the like on one side or both sides of a current collector can be used.

As the negative electrode active material contained in the negative electrode mixture layer, a compound capable of deinserting lithium or a material containing an element capable of alloying with lithium can be used, but it is preferable to use a graphitic carbon material. As the graphitic carbon material, those used in conventionally known lithium ion batteries are suitable, for example, natural graphite such as scaly graphite; thermally decomposed carbons, mesophase carbon microbeads (MCMB), and the like. Examples thereof include artificial graphite obtained by graphitizing easily graphitized carbon such as carbon fiber at 2800 ° C. or higher. Examples of the material containing an element that can be alloyed with silicon include a metal (Si, Sn, etc.) that can be alloyed with silicon or an alloy thereof, and the general composition formula SiO _x (however, the atomic ratio of O to Si). As x, a material containing Si and O represented by (0.5 ≦ x ≦ 1.5) as constituent elements can also be used.

As the binder used for the negative electrode mixture layer, the same binder as that exemplified as the above-mentioned positive electrode binder can be used.

Further, a conductive material may be further added to the negative electrode mixture layer as a conductive auxiliary agent. The conductive material is not particularly limited as long as it does not cause a chemical change in the lithium ion battery, and for example, various carbon blacks such as acetylene black and ketjen black, carbon nanotubes, carbon fibers and the like are used. Species or two or more species can be used.

For the negative electrode, for example, a paste-like or slurry-like negative electrode mixture-containing paint in which a negative electrode active material and a binder and, if necessary, a conductive auxiliary agent are dispersed in a solvent such as NMP or water is prepared and collected. It is manufactured by applying it to one or both sides of an electric body, drying it, and then pressing it if necessary. However, the negative electrode is not limited to the one manufactured by the above manufacturing method, and may be manufactured by another manufacturing method.

The thickness of the negative electrode mixture layer is preferably, for example, 10 to 100 μm per one side of the current collector. The density of the negative electrode mixture layer is preferably 1.0 to 1.9 g / cm ³ . The composition of the negative electrode mixture layer is preferably such that the amount of the negative electrode active material is 80 to 99% by mass, the amount of the binder is preferably 1 to 20% by mass, and when a conductive auxiliary agent is used. The conductive auxiliary agent is preferably used within a range in which the amount of the negative electrode active material and the amount of the binder satisfy the above-mentioned suitable values.

As the current collector of the negative electrode, a copper or nickel foil, a punching metal, a net, an expanded metal or the like can be used, but a copper foil is usually used. When the thickness of the entire negative electrode of this negative electrode current collector is reduced in order to obtain a battery having a high energy density, the upper limit of the thickness is preferably 30 μm, and the lower limit of the thickness is 5 μm in order to secure mechanical strength. Is preferable.

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

Examples of the organic solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (MEC). , Γ-Butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formic acid, methyl acetate, phosphate triester , Trimethoxymethane, dioxolane derivative, sulfolane, 3-methyl-2-oxazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, diethyl ether, 1,3-propanesartone and other aproton organic solvents. It may be used alone or in combination of two or more.

Examples of the inorganic lithium salt include LiClO ₄ , LiBF ₄ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiB ₁₀ Cl ₁₀ , lower aliphatic carboxylic acid Li, LiAlCl ₄ , LiCl, and LiBr. , LiI, chloroborane Li, Li tetraphenylborate and the like, and these may be used alone or in combination of two or more.

Examples of the organolithium salts include LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , Li ₂ C ₂ F ₄ (SO ₃ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , and LiC _n1 F. _{2n1 + 1} SO ₃ (2≤n1≤7), LiN (Rf ₁ OSO ₂ ) ₂ [However, Rf ₁ is a fluoroalkyl group. ] And the like, and these may be used alone or in combination of two or more.

The concentration of the electrolyte salt in the non-aqueous electrolyte solution is, for example, preferably 0.2 to 3.0 mol / dm ³ , more preferably 0.5 to 1.5 mol / dm ³ , and 0. It is more preferably 9 to 1.3 mol / dm ³ .

As described above, the positive electrode after charging the battery to 4.5 V with a current of 1 / 3C and then discharging to 3 V with a current of 1 / 3C is washed with methyl ethyl carbonate and then vacuum dried, and then the positive electrode is described above. When the surface of the above-mentioned surface is analyzed by X-ray photoelectron spectroscopy (XPS), the content ratio of oxygen atoms on the surface of the positive electrode is Ro (atomic%), the content ratio of fluorine atoms is Rf (atom%), and the 1s orbital. Assuming that the content ratio of carbon atoms having a bond energy of 289 to 291 eV is Rc (atomic%), Rf / Ro is 0.05 or more and 1.3 or less, or Rc / Ro is 0.05 or more and 0.75 or less. In order to obtain the surface state of the positive electrode, the non-aqueous electrolytic solution preferably contains a fluorine-containing compound as the lithium salt, and preferably contains a carbon dioxide compound as the organic solvent. The non-aqueous electrolytic solution may contain at least one of the fluorine-containing compound and the carbonic acid compound, but preferably contains both the fluorine-containing compound and the carbonic acid compound. However, the fluorine-containing compound and the carbonic acid compound may be contained in the positive electrode.

As the non-aqueous electrolyte solution for obtaining the surface state of the positive electrode, at least one chain carbonate selected from dimethyl carbonate, diethyl carbonate and methyl ethyl carbonate, and at least one cyclic carbonate selected from ethylene carbonate and propylene carbonate. It is particularly preferable to use a non-aqueous electrolyte solution in which LiPF ₆ (lithium hexafluorophosphate) is dissolved in a solvent containing carbonate.

Further, the non-aqueous electrolytic solution may appropriately contain the following additives for the purpose of improving the charge / discharge cycle characteristics, high temperature storage characteristics, prevention of overcharging and the like. Examples of the additive include anhydrous acid, sulfonic acid ester, dinitrile, 1,3-propanesaltone, diphenyldisulfide, cyclohexylbenzene, vinylene carbonate (VC), biphenyl, fluorobenzene, t-butylbenzene, and cyclic fluorination. Esters [trifluoropropylene carbonate (TFPC), fluoroethylene carbonate (FEC), etc.] or chain fluorinated carbonates [trifluorodimethyl carbonate (TFDMC), trifluorodiethyl carbonate (TFDEC), trifluoroethylmethyl carbonate (TFEMC) ), Etc.], Fluorinated ether [Rf ₂ -OR ₄ (where Rf ₂ is a fluorine-containing alkyl group and R ₄ is an organic group which may contain hydrogen]], phosphate ester [ethyl. Diethylphosphonoacetate (EDPA): (C ₂ H ₅ O) ₂ (P = O) -CH ₂ (C = O) OC ₂ H ₅ ], Tris (trifluoroethyl) phosphate (TFEP): (CF ₃ ) CH ₂ O) ₃ P = O, triphenyl phosphate (TPP): (C ₆ H ₅ O) ₃ P = O and the like (including derivatives of each of the above compounds).

An additive that is highly effective in improving charge / discharge cycle characteristics under high voltage when used in combination with the above-mentioned positive electrode coating is a compound having two or more nitrile groups in the molecule. Examples of the compound having two or more nitrile groups in the molecule include succinonitrile, glutaronitrile, adiponitrile, 1,5-dicyanopentane, 1,6-dicyanohexane, 1,7-dicyanoheptane, and 1, 8-dicyanooctane, 1,9-dicyanononane, 1,10-dicyanodecane, 1,12-dicyanododecane, tetramethylsuccinonitrile, 2-methylglutaronitrile, 4-dicyanopentane, 2,6-dicyanoheptane, Examples thereof include dinitriles such as 2,7-dicyanooctane, 2,8-dicyanononane, 1,6-dicyanodecane and 1,2-dicyanobenzene. Further, some of these dinitriles and the like may be fluorinated.

The concentration of the compound having two or more nitrile groups in the molecule in the non-aqueous electrolytic solution is preferably 0.1% by mass or more, more preferably 2% by mass or more, most preferably 10% by mass or more, and 50. It is preferably 3% by mass or less, more preferably 30% by mass or less, and most preferably 20% by mass or less.

<Separator>
The separator preferably has sufficient strength and can hold a large amount of non-aqueous electrolytic solution. For example, polyethylene (PE) or polypropylene (PP) having a thickness of 5 to 50 μm and an aperture ratio of 30 to 70%. Etc., a microporous film made of polyolefin can be used. The microporous film constituting the separator may be, for example, one using only PE or only one using PP, may contain an ethylene-propylene copolymer, or may be made of PE. It may be a laminate of a porous film and a microporous film made of PP.

Further, as the separator, a porous layer (A) mainly composed of a resin having a melting point of 140 ° C. or lower and a porous layer mainly containing a resin having a melting point of 150 ° C. or higher or an inorganic filler having a heat resistant temperature of 150 ° C. or higher ( A laminated separator composed of B) and can also be used. The porous layer (A) is mainly for ensuring a shutdown function, and when the internal temperature of the lithium ion battery reaches the melting point or higher of the resin which is the main component of the porous layer (A). , The resin related to the porous layer (A) melts and closes the pores of the separator, resulting in a shutdown that suppresses the progress of the electrochemical reaction. On the other hand, the porous layer (B) has a function of preventing a short circuit due to direct contact between the positive electrode and the negative electrode even when the internal temperature of the lithium ion battery rises, and has a melting point of 150 ° C. or higher. Its function is ensured by a resin or an inorganic filler having a heat resistant temperature of 150 ° C. or higher. That is, when the battery becomes hot, even if the porous layer (A) shrinks, the porous layer (B) that does not easily shrink causes the separator to heat shrink, which can occur directly on the positive and negative electrodes. It is possible to prevent a short circuit due to contact. Further, since the heat-resistant porous layer (B) acts as a skeleton of the separator, the heat shrinkage of the porous layer (A), that is, the heat shrinkage of the entire separator can be suppressed. Here, the "melting point" means the melting temperature measured by a differential scanning calorimeter (DSC) in accordance with the provisions of Japanese Industrial Standards (JIS) K7121, and "heat resistant temperature is 150 ° C. or higher". Means that no deformation such as softening is observed at least at 150 ° C.

The thickness of the separator (separator made of a microporous film made of polyolefin or the laminated separator) is more preferably 10 to 30 μm.

<Electrode body>
As the electrode body used in the non-aqueous secondary battery of the present embodiment, a laminated electrode body in which the positive electrode and the negative electrode are laminated via the separator, or a winding in which the laminated electrode body is further wound in a spiral shape. An electrode body can be mentioned.

<Battery form>
The form of the lithium ion battery is not particularly limited, and may be, for example, any of a coin type, a button type, a sheet type, a laminated type, a cylindrical type, a flat type, a square type, a large one used for an electric vehicle, and the like. good.

<Characteristics of non-water secondary battery>
The charging voltage of the non-aqueous secondary battery of the present embodiment is preferably 4.35 V or higher, more preferably 4.45 V or higher, and most preferably 4.55 V or higher based on lithium. This is because the higher the charging voltage, the more effectively the electrode protection action of the positive electrode coating of the present embodiment works. Further, the charging voltage is preferably 5.5 V or less. This is because if the charging voltage is too high, the protective film itself may be decomposed. Further, when the charging voltage of the lithium ion battery is preferably 4.4 V or more, more preferably 4.55 V or more based on lithium, the continuous heat generation state of the battery starts from a lower temperature, and thus the above-mentioned electrolysis containing dinitrile. The combination with the liquid is more optimal.

In the non-aqueous secondary battery of the present embodiment, one cycle is one cycle in which the battery is charged to 4.35 V with a current of 1 / 3C and then discharged to 3 V with a current of 1 / 3C, and 100 cycles with respect to the discharge capacity at the time of one cycle. The ratio (%) of the discharge capacity at the time is 4.35V capacity retention rate: RL, and after charging to 4.5V with a current of 1 / 3C, discharging to 3V with a current of 1 / 3C is defined as one cycle. When the ratio (%) of the discharge capacity at 100 cycles to the discharge capacity at 1 cycle is 4.5 V capacity retention rate: RH, the capacity retention rate ratio: RH / RL can be 0.75 or more. The capacity retention ratio: RH / RL is more preferably 0.8 or more, and most preferably 0.9 or more. That is, in the non-aqueous secondary battery of the present embodiment, the deterioration of the charge / discharge cycle characteristics can be suppressed to a low level even under a high voltage. When the charge voltage is different from that of the present embodiment, the capacity retention rate in the charge / discharge cycle test at the charge voltage is set to RH', and the same charge / discharge cycle test is performed at a voltage 0.15 V lower than the charge voltage. When the capacity retention rate is RL', RH'/ RL'is more preferably 0.8 or more, and most preferably 0.9 or more.

Further, in the conventional non-aqueous secondary battery manufactured in the same manner as the non-aqueous secondary battery of the present embodiment except that the positive electrode is not coated, after charging to 4.35 V with a current of 1/3 C, 1 Discharging to 3V with a current of / 3C is one cycle, and the ratio (%) of the discharge capacity at 100 cycles to the discharge capacity at one cycle is 4.35V. Capacity retention rate: RLC, with a current of 1 / 3C. After charging to 4.5V, discharging to 3V with a current of 1 / 3C is defined as one cycle, and the ratio (%) of the discharge capacity at 100 cycles to the discharge capacity at 1 cycle is 4.5V capacity retention rate: In the case of RHC, the RL of the present embodiment and the conventional RLC at 4.35V have a 4.35V capacity retention rate improvement rate A calculated by the following formula (1), and the RH of the present embodiment and the conventional one at 4.5V. Comparing the 4.5V capacity retention rate improvement rate B calculated by the following formula (2) from the RHC of the above, in the present embodiment, contrary to the initial expectation, the 4.5V capacity retention rate improvement rate B is 4. It can be made larger than the 35V capacity maintenance rate improvement rate A.
A = [(RL-RLC) / RLC] x 100 (1)
B = [(RH-RHC) / RHC] x 100 (2)

Further, if the B / A value obtained from the 4.5V capacity retention rate improvement rate B and the 4.35V capacity maintenance rate improvement rate A is 1 or more, it indicates that the charge / discharge cycle characteristics at high voltage are high. .. Therefore, the B / A is preferably 1 or more, more preferably 5 or more, and most preferably 10 or more.

Further, even when the charging voltage is different from that of the present embodiment, the capacity retention rate improvement rate at the charging voltage is set to B', and the capacity retention rate improvement rate at the charging voltage 0.15V lower than the charging voltage is set to A'. Even when, B'/ A'is preferably 1 or more, more preferably 5 or more, and most preferably 10 or more.

(Second Embodiment of Non-Water Secondary Battery)
A second embodiment of the non-aqueous secondary battery of the present invention comprises a positive electrode, a negative electrode and a non-aqueous electrolytic solution, wherein the non-aqueous electrolytic solution or the positive electrode contains a fluorine-containing compound or a carbonic acid compound, and the non-aqueous electrolysis solution is provided. The liquid contains an additive other than vinylene carbonate, and the concentration of the additive in the non-aqueous electrolytic solution is 0.05% by mass or more and 3% by mass or less.

By using a non-aqueous secondary battery having the above configuration, the positive electrode after charging the battery to 4.5 V with a current of 1 / 3C and then discharging to 3 V with a current of 1 / 3C is washed with methyl ethyl carbonate. Then, when the surface of the positive electrode is analyzed by X-ray photoelectron spectroscopy (XPS), the content of oxygen atoms on the surface of the positive electrode is Ro (atomic%) and the content of fluorine atoms. When Rf (atomic%) and the content ratio of carbon atoms having a 1s orbital bond energy of 289 to 291 eV are Rc (atomic%), Rf / Ro is 0.05 or more and 1.3 or less, or Rc /. Ro can be 0.05 or more and 0.75 or less. This makes it possible to improve the charge / discharge cycle characteristics under high voltage.

As the fluorine-containing compound and the carbonic acid compound, the same compounds as those used in the non-aqueous secondary battery of the first embodiment can be used.

Further, as the additive other than the vinylene carbonate, a nitrogen-containing compound is desirable, and a non-fluorine-based (fluorine-free) nitrogen-containing compound is more preferable. Further, in the nitrogen-containing compound, it is desirable that at least one H atom is bonded to the nitrogen atom, and it is more desirable that two H atoms are bonded to the nitrogen atom. Examples of the nitrogen-containing compound include amines and amides, but amines are particularly desirable. More specifically, diethylene glycol bisaminopropyl ether, diethylene oxide bishexamethylenetriamine, dicyclohexylamine and the like can be used as the nitrogen-containing compound.

The concentration of the additive in the non-aqueous electrolytic solution is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, preferably 3% by mass or less, and more preferably 1% by mass or less. This is because the additive reacts with the positive electrode to form a film, and if it is too small, a sufficient film is not formed, and if it is too large, the resistance increases.

Further, the configuration of the non-aqueous secondary battery of the present embodiment other than the above configuration can be the same as the configuration of the non-aqueous secondary battery of the first embodiment described above.

(Embodiment of Manufacturing Method of Non-Water Secondary Battery)
The first embodiment of the method for manufacturing a non-aqueous secondary battery of the present invention is the method for manufacturing a non-aqueous secondary battery according to the first embodiment described above, and is selected from the components 1, the component 2 and the component 3. Including a step of preparing a treatment liquid containing at least one component and a step of applying the treatment liquid to the surface of the positive electrode, the component 1 is a sugar-like compound, and the component 2 is a metal salt. The component 3 is a nitrogen-containing compound, and the positive electrode is a positive electrode after a press treatment.

As the components 1 to 3, the same components as those used in the non-aqueous secondary battery of the first embodiment described above can be used.

The positive electrode after the press treatment is used as the positive electrode in order to adjust the porosity of the positive electrode mixture layer of the positive electrode. Further, in the positive electrode after the press treatment, a conductive network has already been formed, and by performing the coating treatment in that state, the influence on the conductivity is small and the coating on the conductive material can also be performed. It is possible and suitable for battery characteristics.

The porosity of the positive electrode mixture layer is preferably 22% or more, more preferably 25% or more, most desirablely 28% or more, preferably 35% or less, more preferably 32% or less, and most preferably 29% or less. desirable. This is because if the porosity of the positive electrode mixture layer is too large, most of the treatment liquid infiltrates into the inside of the positive electrode and the coating effect on the surface is lowered, and if it is too small, the coating formed by the components is formed. Is limited to the surface, and the coating strength is lowered.

In the present embodiment, when the positive electrode is immersed in the treatment liquid for 10 seconds, then taken out and left for 5 seconds, and then the mass of the positive electrode is measured, the mass increase rate of the positive electrode before and after the immersion treatment is 3. % Or more is desirable, 20% or more is more desirable, and 50% or less is desirable. When the mass increase rate is within the above range, the surface of the positive electrode can be appropriately wetted with the treatment liquid.

The concentration of the above components in the treatment liquid is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, most preferably 0.1% by mass or more, and preferably 20% by mass or less, and 10% by mass. % Or less is more desirable, and 2% by mass or less is most desirable. This is because if the concentration is too low, the coating effect is lowered, and if the concentration is too high, it becomes difficult to adjust the coating amount and the resistance of the electrode increases.

The amount of the treatment liquid applied to the surface of the positive electrode is preferably 0.0002 mg / cm ^{2 or more, more preferably 0.002 mg / cm 2 or} more, and 0.008 mg in terms of the dry component mass of the treatment liquid. More than / cm ² is most desirable, 0.5 mg / cm ² or less is desirable, 0.15 mg / cm ² or less is more desirable, and 0.1 mg / cm ² or less is most desirable. This is because if the coating amount is too small, the coating effect is lowered, and if the coating amount is too large, the resistance of the electrode is increased.

Further, the second embodiment of the method for manufacturing a non-aqueous secondary battery of the present invention is the method for manufacturing a non-aqueous secondary battery according to the first embodiment described above, wherein the component 1, the component 2, and the component 3 are manufactured. A step of preparing a non-aqueous electrolyte solution containing at least one component selected from the above, a step of assembling a battery using the positive electrode, the negative electrode and the above-mentioned non-aqueous electrolyte solution, and a step of charging and discharging the assembled battery are included. The component 1 is a sugar-like compound, the component 2 is a metal salt, and the component 3 is a nitrogen-containing compound.

As the components 1 to 3, the same components as those used in the non-aqueous secondary battery of the first embodiment described above can be used.

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

(Example 1)
The laminated lithium-ion battery shown in FIG. 1 was manufactured as follows.

[Preparation of positive electrode]
First, 100 parts by mass of LiCoO ₂ (manufactured by Nippon Kagaku Kogyo Co., Ltd., "C20F"), which is a positive electrode active material, 3 parts by mass of acetylene black, which is a conductive auxiliary agent, and 3 parts by mass of PVDF, which is a binder (solid content as an NMP solution). (Supply) was mixed with NMP as a solvent so as to be uniform to prepare a positive electrode mixture-containing paste. Next, the obtained positive electrode mixture-containing paste was applied to one side of a current collector made of an aluminum foil having a thickness of 20 μm so that the coating amount was 18.0 mg / cm ² as the solid content of the positive electrode mixture-containing paste. After applying and drying, a calendar treatment is performed to adjust the thickness of the positive electrode mixture layer so that the total thickness is 75 μm, and the tab welded portion is left and cut to a length of 30 mm and a width of 30 mm. To prepare a positive electrode. Further, the active material of the tab welded portion of the positive electrode was removed, and the tab was welded to the tab welded portion to form a lead portion.

After measuring the mass of the positive electrode, the positive electrode was immersed in ion-exchanged water for 10 seconds, then taken out, left for 5 seconds, and then the mass of the positive electrode was measured. Was 35%.

[Covering treatment of positive electrode]
Diethylenetriamine pentaacetic acid pentasodium (corresponding to about 40% by mass aqueous solution, component 2 and component 3) manufactured by Tokyo Kasei Co., Ltd. is diluted with ion-exchanged water to obtain a 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium in this example. Was prepared as a treatment solution for. Next, the treatment liquid was applied to the surface of the positive electrode prepared above at a coating amount of about 1 mg / cm ² using a coating rod wrapped with cellulose, and then the positive electrode was dried at 120 ° C. to surface the surface. A treated positive electrode was prepared.

[Manufacturing of negative electrode]
100 parts by mass of graphite (manufactured by Hitachi Chemical Co., Ltd., "MAGE") as a negative electrode active material, 1 part by mass of CMC as a binder (providing a solid content as a 1% by mass aqueous solution), and 1.5 parts by mass of SBR with a solvent. A paste containing a negative electrode mixture was prepared by mixing with a certain ion-exchanged water. Next, the obtained negative electrode mixture-containing paste was applied to one side of a copper foil having a thickness of 16.5 μm so that the coating amount was 12.7 mg / cm ² as the solid content of the negative electrode mixture-containing paste and dried. After that, a calendar process is performed to adjust the thickness of the negative electrode mixture layer so that the total thickness is 113 μm, and the negative electrode is manufactured by cutting to a length of 32 mm and a width of 32 mm, leaving the tab welded portion. bottom. Further, a tab was welded to the tab welded portion of the negative electrode to form a lead portion.

[Preparation of separator]
As a separator, a polyethylene microporous membrane having a thickness of 25 μm cut into a length of 45 mm and a width of 40 mm was prepared.

[Preparation of non-aqueous electrolyte solution]
A mixed solution was prepared by dissolving 1.0 mol of LiPF ₆ in 1 kg of a mixed solvent having a volume ratio of ethylene carbonate (EC) and methyl ethyl carbonate (MEC) of 1: 3, and further added to 100 parts by mass of the mixed solution. A non-aqueous electrolyte solution was prepared by adding 2 parts by mass of vinylene carbonate (VC) and 3 parts by mass of succinonitrile.

[Battery assembly and charging]
The positive electrode and the negative electrode were overlapped with the separator interposed therebetween to prepare a laminated electrode body having a three-sheet structure of positive electrode / separator / negative electrode. The obtained laminated electrode body was housed in an exterior body made of an aluminum laminated film, and the non-aqueous electrolytic solution was injected and then sealed. Finally, the laminated lithium-ion battery is charged and discharged 5 times at 10 mA (rate equivalent to 1 / 3C), an upper limit voltage of 4.35 V (4.45 V based on Li), and a lower limit voltage of 3 V. It was a laminated lithium-ion battery.

FIG. 1 shows a plan view of the laminated lithium ion battery produced. In FIG. 1, in the laminated lithium ion battery 10, the laminated electrode body and the non-aqueous electrolytic solution are housed in an exterior body 11 made of a rectangular aluminum laminated film in a plan view. Then, the positive electrode external terminal 12 and the negative electrode external terminal 13 are pulled out from the same side of the exterior body 11.

(Example 2)
A laminated lithium-ion battery of Example 2 was produced in the same manner as in Example 1 except that the concentration of diethylenetriamine pentaacetic acid pentasodium was 2% by mass in the treatment liquid used for the positive electrode coating treatment.

(Example 3)
A laminated lithium-ion battery of Example 3 was produced in the same manner as in Example 1 except that the concentration of diethylenetriamine pentaacetic acid pentasodium was 5% by mass in the treatment liquid used for the positive electrode coating treatment.

(Example 4)
A laminated lithium-ion battery of Example 4 was produced in the same manner as in Example 1 except that succinonitrile was not added to the non-aqueous electrolytic solution.

(Example 5)
A laminated lithium-ion battery of Example 5 was produced in the same manner as in Example 1 except that the amount of succinonitrile added to the non-aqueous electrolytic solution was 20 parts by mass.

(Example 6)
In the treatment liquid used for the coating treatment of the positive electrode, a 1% by mass aqueous solution of ethylenediamine tetraacetate (corresponding to component 2 and component 3) was used instead of the 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium, and non-aqueous electrolysis was performed. A laminated lithium ion battery of Example 6 was produced in the same manner as in Example 1 except that succinonitrile was not added to the liquid.

(Example 7)
In the treatment liquid used for the coating treatment of the positive electrode, 1% by mass of fractane (corresponding to component 1) and 0.9% by mass of gamma glutamate (corresponding to component 3) were used instead of the 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium. A laminated lithium ion battery of Example 7 was produced in the same manner as in Example 1 except that succinonitrile was not added to the non-aqueous electrolyte solution using a mixed aqueous solution.

(Example 8)
In the treatment liquid used for the coating treatment of the positive electrode, a 1% by mass aqueous solution of Li ₂ MoO ₄ (corresponding to component 2) was used instead of the 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium. In the same manner, the laminated lithium ion battery of Example 8 was produced.

(Example 9)
In the treatment liquid used for the coating treatment of the positive electrode, a 1% by mass aqueous solution of Li ₂ MoO ₄ (corresponding to component 2) was used instead of the 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium, and succino was used as the non-aqueous electrolyte solution. The laminated lithium ion battery of Example 9 was produced in the same manner as in Example 1 except that nitrile was not added.

(Example 10)
In the treatment liquid used for the coating treatment of the positive electrode, a 1% by mass aqueous solution of Li ₂ WO ₄ (corresponding to component 2) was used instead of the 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium, and the non-aqueous electrolyte solution was succino. The laminated lithium ion battery of Example 10 was produced in the same manner as in Example 1 except that nitrile was not added.

(Example 11)
In the treatment liquid used for the coating treatment of the positive electrode, 5 of sodium lignin sulfonate (corresponding to "Sun Extract P252" manufactured by Nippon Paper Co., Ltd., component 1 and component 2) instead of a 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium. The laminated lithium ion battery of Example 11 was produced in the same manner as in Example 1 except that succinonitrile was not added to the non-aqueous electrolyte solution using a mass% aqueous solution.

(Example 12)
In the treatment liquid used for the coating treatment of the positive electrode, instead of a 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium, 1 of sodium lignin sulfonate (corresponding to "Sun Extract P321" manufactured by Nippon Paper Co., Ltd., component 1 and component 2). A laminated lithium ion battery of Example 12 was produced in the same manner as in Example 1 except that a mass% aqueous solution was used and the amount of succinonitrile added to the non-aqueous electrolyte solution was 20 parts by mass.

(Example 13)
In the treatment liquid used for the coating treatment of the positive electrode, a 1% by mass aqueous solution of sucrose (corresponding to component 1) was used instead of the 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium, and succinonitrile as a non-aqueous electrolyte solution was added. The laminated lithium ion battery of Example 13 was produced in the same manner as in Example 1 except that the amount was 20 parts by mass.

(Example 14)
Examples except that a 0.1% by mass aqueous solution of carboxymethyl cellulose (CMC, corresponding to component 1) was used in place of the 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium in the treatment liquid used for the positive electrode coating treatment. The laminated lithium ion battery of Example 14 was produced in the same manner as in 1.

(Example 15)
In the treatment liquid used for the coating treatment of the positive electrode, a 0.1% by mass aqueous solution of carboxymethyl cellulose (CMC, corresponding to component 1) was used in place of the 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium, and the non-aqueous electrolytic solution was used. A laminated lithium ion battery of Example 15 was produced in the same manner as in Example 1 except that succinonitrile was not added.

(Example 16)
In the treatment liquid used for the coating treatment of the positive electrode, a 1% by mass aqueous solution of sodium alginate (corresponding to component 1 and component 2) was used instead of the 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium, and the non-aqueous electrolyte solution was squeezed. A laminated lithium ion battery of Example 16 was produced in the same manner as in Example 1 except that the amount of shinonitrile added was 20 parts by mass.

(Example 17)
In the treatment liquid used for the coating treatment of the positive electrode, a 1% by mass aqueous solution of sodium monofluorophosphate (Na ₂ PO _3F , corresponding to component 2) was used instead of the 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium. A laminated lithium ion battery of Example 17 was produced in the same manner as in Example 1 except that succinonitrile was not added to the non-aqueous electrolyte solution.

(Example 18)
In the treatment liquid used for the coating treatment of the positive electrode, a 1% by mass aqueous solution of Na ₃ PO ₄ (corresponding to component 2) was used instead of the 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium, and succino was used as the non-aqueous electrolyte solution. The laminated lithium ion battery of Example 18 was produced in the same manner as in Example 1 except that nitrile was not added.

(Example 19)
In the treatment liquid used for the coating treatment of the positive electrode, a 1% by mass aqueous solution of sodium metaphosphate [(NaPO ₃ ) _n , corresponding to component 2] was used instead of the 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium, and non-water was used. A laminated lithium ion battery of Example 19 was produced in the same manner as in Example 1 except that succinonitrile was not added to the electrolytic solution.

(Example 20)
In the treatment liquid used for the positive electrode coating treatment, a 1% by mass aqueous solution of sodium pyrophosphate (Na ₄ P ₂ O ₇ , corresponding to component 2) was used instead of the 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium, and the solution was not used. A laminated lithium ion battery of Example 20 was produced in the same manner as in Example 1 except that succinonitrile was not added to the aqueous electrolytic solution.

(Example 21)
In the treatment liquid used for the coating treatment of the positive electrode, a 1% by mass aqueous solution of 3-sulfopropyl potassium methacrylate (corresponding to component 2) was used instead of the 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium, and a non-aqueous electrolytic solution was used. The laminated lithium ion battery of Example 21 was produced in the same manner as in Example 1 except that succinonitrile was not added to the mixture.

(Example 22)
In the treatment liquid used for the coating treatment of the positive electrode, a 1% by mass aqueous solution of imidelithium dibenzenesulfonate (corresponding to component 2 and component 3) was used instead of the 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium, and non-water was used. The laminated lithium ion battery of Example 22 was produced in the same manner as in Example 1 except that succinonitrile was not added to the electrolytic solution.

(Example 23)
In the treatment liquid used for the coating treatment of the positive electrode, a 1% by mass aqueous solution of β-cyclodextrin (corresponding to component 1) was used instead of the 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium, and succino was used as the non-aqueous electrolytic solution. The laminated lithium ion battery of Example 23 was produced in the same manner as in Example 1 except that nitrile was not added.

(Example 24)
In the treatment liquid used for the coating treatment of the positive electrode, a 1% by mass aqueous solution of α-cyclodextrin (corresponding to component 1) was used instead of the 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium, and succino was used as the non-aqueous electrolytic solution. The laminated lithium ion battery of Example 24 was produced in the same manner as in Example 1 except that nitrile was not added.

(Example 25)
In the treatment liquid used for the coating treatment of the positive electrode, a 1% by mass aqueous solution of sodium alginate (corresponding to component 1 and component 2) was used instead of the 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium, and the non-aqueous electrolytic solution was used as a scoop. The laminated lithium ion battery of Example 25 was produced in the same manner as in Example 1 except that shinonitrile was not added.

(Example 26)
In the treatment liquid used for the coating treatment of the positive electrode, 1 mass of alginate and sodium alginate (corresponding to 50% partially neutralized product of alginate, component 1 and component 2) instead of 1 mass% aqueous solution of diethylenetriamine pentaacetate pentasodium. A laminated lithium ion battery of Example 26 was produced in the same manner as in Example 1 except that succinonitrile was not added to the non-aqueous electrolyte solution using a% aqueous solution.

(Example 27)
In the treatment liquid used for the coating treatment of the positive electrode, 0.3 mass of sodium polyacrylate (molecular weight: 30,000 to 40,000, corresponding to component 1 and component 2) instead of a 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium. A laminated lithium ion battery of Example 27 was produced in the same manner as in Example 1 except that succinonitrile was not added to the non-aqueous electrolyte solution using a% aqueous solution.

(Example 28)
In the treatment liquid used for the coating treatment of the positive electrode, a 0.3% by mass aqueous solution of polyacrylic acid (molecular weight: 250,000, corresponding to component 1) was used instead of the 1% by mass aqueous solution of diethylenetriamine pentaacetic acid pentasodium. The laminated lithium ion battery of Example 28 was produced in the same manner as in Example 1 except that succinonitrile was not added to the aqueous electrolytic solution.

(Example 29)
1.0 mol of LiPF ₆ is dissolved in 1 kg of a mixed solvent having a volume ratio of ethylene carbonate (EC) and methyl ethyl carbonate (MEC) of 1: 3 without coating the positive electrode by applying the treatment liquid. To 100 parts by volume of the mixed solution, 2 parts by volume of vinylene carbonate (VC), 3 parts by volume of succinonitrile, and 0.3 parts by volume of diethylene glycol bisaminopropyl ether were added to prepare a non-aqueous electrolyte solution. A laminated lithium ion battery of Example 29 was prepared in the same manner as in Example 1 except that the non-aqueous electrolyte solution was used.

(Comparative Example 1)
A laminated lithium-ion battery of Comparative Example 1 was produced in the same manner as in Example 1 except that the positive electrode was not coated by applying the treatment liquid and succinonitrile was not added to the non-aqueous electrolytic solution.

(Comparative Example 2)
A laminated lithium-ion battery of Comparative Example 2 was produced in the same manner as in Example 1 except that the positive electrode was not coated by applying the treatment liquid.

Next, the following evaluation tests were performed on the batteries of Examples 1 to 29 and Comparative Examples 1 and 2, and the positive electrode surfaces of Examples 1, 5, 11, 12, 19, 20, 29 and Comparative Examples 1 and 2 were performed. XPS analysis was performed.

<Charge / discharge cycle test>
[4.35V charge / discharge cycle test]
Charging and discharging were repeated 100 times under the conditions of a current of 10 mA (corresponding to a current value of 1 / 3C), an upper limit voltage of 4.35 V, and a lower limit voltage of 3 V. Based on this, the ratio (%) of the discharge capacity at 100 cycles to the discharge capacity at 1 cycle was calculated as 4.35 V capacity retention rate: RL for Examples 1 to 29, and 4. for Comparative Example 1. It was calculated as 35V capacity retention rate: RLC1, and for Comparative Example 2, it was calculated as 4.35V capacity retention rate: RLC2.

[4.5V charge / discharge cycle test]
Charging and discharging were repeated 100 times under the conditions of a current of 10 mA (corresponding to a current value of 1 / 3C), an upper limit voltage of 4.5 V, and a lower limit voltage of 3 V. Based on this, the ratio (%) of the discharge capacity at 100 cycles to the discharge capacity at 1 cycle was calculated as 4.5 V capacity retention rate: RH for Examples 1 to 29, and 4. for Comparative Example 1. It was calculated as 5V capacity retention rate: RHC1, and for Comparative Example 2, it was calculated as 4.5V capacity retention rate: RHC2.

[Calculation of 4.35V capacity maintenance rate improvement rate A]
For Examples 1 to 29 and Comparative Example 2, the 4.35 V capacity retention rate improvement rate A was calculated by the following formula A.
A = [(RL-RLC1) / RLC1] × 100

[Calculation of 4.5V capacity maintenance rate improvement rate B]
For Examples 1 to 29 and Comparative Example 2, the 4.5V capacity retention rate improvement rate B was calculated by the following formula B.
B = [(RH-RHC1) / RHC1] × 100

[Calculation of B / A]
B / A was calculated from the 4.35V capacity maintenance rate improvement rate A and the 4.5V capacity maintenance rate improvement rate B.

<Heating test>
The external terminal of the laminated lithium-ion battery was cut, and while maintaining the battery configuration, the cut portion was wrapped with imide tape to insulate it, and the cut portion was wrapped with aluminum foil to prepare a measurement sample. After that, the measurement sample is inserted into a 100-atmosphere pressure-resistant stainless steel sample container of a calorimeter "C80" manufactured by Setaram, and the sample container is further inserted into the main body of "C80" to be from 40 ° C to 300 ° C. A temperature rise test was performed at ° C./min, the heat generation of the battery was measured, and the temperature of the heat generation peak of the battery observed at 200 ° C. or higher was measured.

<XPS analysis>
After charging and discharging once under the conditions of a current of 10 mA (corresponding to a current value of 1 / 3C), an upper limit voltage of 4.5 V, and a lower limit voltage of 3 V, the battery is disassembled and the positive electrode is taken out, and the positive electrode is placed in an inert atmosphere. Then, it was washed with methyl ethyl carbonate and then vacuum dried. After that, using the XPS measuring device "AXIS-NOVA" manufactured by Kratos, monochromatic AlKα (1486.6 eV) was used as the X-ray source, and the analysis area was 700 μm × 300 μm, and the Pass Energy was 20 eV from the inert atmosphere. Evacuation was performed and XPS analysis of the surface of the positive electrode was performed. Further, in the above XPS analysis, the peak position is corrected at the peak position (binding energy of 1s orbit: 284.4 eV) of the conductive auxiliary agent (carbon black) contained in the positive electrode, and the position peak and the peak width are used for the peak division. Was separated.

As a result of the XPS analysis, the oxygen atom content is Ro (atom%), the fluorine atom content is Rf (atom%), and the carbon atom having a 1s orbital bond energy of 289 to 291 eV is contained on the surface of the positive electrode. Rf / Ro and Rc / Ro were calculated with the ratio as Rc (atomic%). The content of other atoms on the surface of the positive electrode was also measured.

Tables 1 and 2 show the presence or absence of the nitrile compound in the positive electrode surface treatment agent and the non-aqueous electrolytic solution used in Examples 1 to 29 and Comparative Examples 1 and 2 above. The results of the above evaluation test and XPS analysis of the positive electrode surface are shown in Tables 3 and 4. In addition, in Tables 3 and 4, as other atomic ratios, the content ratios of N: nitrogen atom, P: phosphorus atom, S: sulfur atom, and M: active material metal component are also shown.

From Tables 1 to 4, a battery using a positive electrode coated with at least one of a sugar-like compound (component 1), a metal salt (component 2), and a nitrogen-containing compound (component 3), or a positive electrode having a specific surface condition is used. It can be seen that excellent charge / discharge cycle characteristics can be obtained under high voltage. Further, it can be seen that the safety can be improved and the charge / discharge cycle characteristics can be improved by using the dinitrile compound which originally has poor charge / discharge cycle characteristics in the electrolytic solution.

According to the present invention, it is possible to provide a non-aqueous secondary battery having excellent charge / discharge cycle characteristics at a high voltage, and the non-aqueous secondary battery of the present invention is compact and lightweight, and has a high capacity and a high energy density. It can be used as a battery for portable electronic devices such as mobile phones and notebook personal computers that require a battery, and a battery for an electric vehicle.

10 Laminated lithium-ion battery 11 Exterior 12 Positive electrode external terminal 13 Negative electrode external terminal

Claims (9)

A non-aqueous secondary battery containing a positive electrode, a negative electrode and a non-aqueous electrolyte solution.
The positive electrode contains a positive electrode mixture layer and contains a positive electrode mixture layer.
The porosity of the positive electrode mixture layer is 22% or more and 35% or less.
After charging to 4.5V with a current of 1 / 3C and discharging to 3V with a current of 1 / 3C, the positive electrode is washed with methyl ethyl carbonate and then vacuum dried, and then the surface of the positive electrode is X-rayed. When analyzed by photoelectron spectroscopy
On the surface of the positive electrode, the content ratio of oxygen atom is Ro (atom%), the content ratio of fluorine atom is Rf (atom%), and the content ratio of carbon atom whose bond energy of 1s orbital is 289 to 291 eV is Rc (atom%). ) Then
A non-aqueous secondary battery characterized in that Rf / Ro is 0.05 or more and 1.3 or less, or Rc / Ro is 0.05 or more and 0.75 or less. The non-aqueous secondary battery according to claim 1, which satisfies any of the following (1) to (3) in the analysis of the surface of the positive electrode by the X-ray photoelectron spectroscopy.
(1) The content ratio of nitrogen atoms on the surface of the positive electrode is 0.1 atomic% or more and 1 atomic% or less (2) The content ratio of phosphorus atoms on the surface of the positive electrode is 0.5 atomic% or more and 10 atomic% or less (3). ) The total content of cobalt, nickel, manganese and iron on the surface of the positive electrode is 0.1 atomic% or more and 15 atomic% or less. A group in which the surface of the positive electrode is composed of a lignin compound, a polypeptide, a monofluorophosphate, a metaphosphate, a pyrophosphate, a diethylenetriamine pentaacetate, an ethylenediaminetetraacetate, polypeptides or salts thereof, and polyallylamine. The non-aqueous secondary battery according to claim 1, which is coated with at least one component selected from. The non-aqueous secondary battery according to claim 1, wherein the positive electrode contains at least one selected from a fluorine-containing compound and a carbonic acid compound. A method for manufacturing a non-aqueous secondary battery containing a positive electrode, a negative electrode and a non-aqueous electrolyte solution.
The process of preparing the treatment liquid to be applied to the surface of the positive electrode and
The step of applying the treatment liquid to the surface of the positive electrode is included.
The treatment liquid consists of a group consisting of a lignin compound, a polypeptide, a monofluorophosphate, a metaphosphate, a pyrophosphate, a diethylenetriamine pentaacetate, an ethylenediaminetetraacetate, polypeptides or salts thereof, and polyallylamine. Contains at least one ingredient selected
After charging the battery to 4.5V with a current of 1 / 3C and discharging to 3V with a current of 1 / 3C, the positive electrode was washed with methyl ethyl carbonate and then vacuum dried, and then the surface of the positive electrode was dried. When analyzed by X-ray photoelectron spectroscopy
On the surface of the positive electrode, the content ratio of oxygen atom is Ro (atom%), the content ratio of fluorine atom is Rf (atom%), and the content ratio of carbon atom whose bond energy of 1s orbital is 289 to 291 eV is Rc (atom%). ) Then
A method for producing a non-aqueous secondary battery, wherein Rf / Ro is 0.05 or more and 1.3 or less, or Rc / Ro is 0.05 or more and 0.75 or less. The positive electrode contains a positive electrode mixture layer and contains a positive electrode mixture layer.
The method for manufacturing a non-aqueous secondary battery according to claim 5, further comprising a step of pressing the positive electrode mixture layer and a step of applying the treatment liquid to the surface of the pressed positive electrode mixture layer. The method for manufacturing a non-aqueous secondary battery according to claim 6, wherein in the step of pressing the positive electrode mixture layer, the porosity of the positive electrode mixture layer is 22% or more and 35% or less. The concentration of the component in the treatment liquid is 0.01% by mass or more and 20% by mass or less.
The non-aqueous secondary according to claim 5, wherein the amount of the treatment liquid applied to the surface of the positive electrode is 0.0002 mg / cm ² or more and 0.5 mg / cm ² or less in terms of the mass of the dry component of the treatment liquid. How to make a battery. A method for manufacturing a non-aqueous secondary battery containing a positive electrode, a negative electrode and a non-aqueous electrolyte solution.
At least one selected from the group consisting of lignin compounds, polypeptides, monofluorophosphates, metaphosphates, pyrophosphates, diethylenetriaminepentaacetates, ethylenediaminetetraacetates, polypeptides or salts thereof, and polyallylamines. The process of preparing a non-aqueous electrolyte solution containing seed components,
The process of assembling a battery using the positive electrode, the negative electrode and the non-aqueous electrolytic solution, and
It includes a step of charging the assembled battery to a voltage of 4.35 V or higher and then discharging the assembled battery.
After charging the battery to 4.5V with a current of 1 / 3C and discharging to 3V with a current of 1 / 3C, the positive electrode was washed with methyl ethyl carbonate and then vacuum dried, and then the surface of the positive electrode was dried. When analyzed by X-ray photoelectron spectroscopy
On the surface of the positive electrode, the content ratio of oxygen atom is Ro (atom%), the content ratio of fluorine atom is Rf (atom%), and the content ratio of carbon atom whose bond energy of 1s orbital is 289 to 291 eV is Rc (atom%). ) Then
A method for producing a non-aqueous secondary battery, wherein Rf / Ro is 0.05 or more and 1.3 or less, or Rc / Ro is 0.05 or more and 0.75 or less.

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