JPWO2015141852A1 - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

An object of the present invention is to provide a nonaqueous electrolyte secondary battery excellent in long-term cycle characteristics. The object is represented by (I) (a) a positive electrode containing a positive electrode active material containing an excess of lithium represented by the general formula (1), or (b) represented by the general formula (2). A positive electrode including a positive electrode active material, and a lithium-containing oxide having a charge / discharge potential with respect to the counter lithium of 3.3 V or less and an average discharge voltage exceeding 3.3 V of 3.4 to 5.0 V; II) Calculated by X-ray diffraction method (002) Average layer surface distance d002 is 0.345 to 0.400 nm, crystallite size Lc (002) in the c-axis direction is 1.0 to 20.0 nm, and specific surface area is A negative electrode comprising an easily graphitizable or non-graphitizable carbonaceous material having 1 to 50 g / m 2, butanol true density ρBtOH of 1.45 to 2.20 g / cm 3, and a sulfur element content of 75 to 3500 μg / g Nonaqueous electrolyte secondary battery including electrode Can be solved by.

Description

  The present invention relates to a non-aqueous electrolyte secondary battery. ADVANTAGE OF THE INVENTION According to this invention, the resistance at the time of discharge becomes low, and the nonaqueous electrolyte secondary battery excellent in cycle capacity retention can be obtained.

  In recent years, due to increasing interest in environmental problems, mounting of large-sized lithium ion secondary batteries with high energy density and excellent output characteristics to electric vehicles has been studied. In small portable devices such as mobile phones and notebook computers, capacity per volume is important, and thus a graphite material having a high density has been mainly used as a negative electrode active material. However, in-vehicle lithium ion secondary batteries are large and expensive, and are difficult to replace in the middle. Accordingly, at least the same durability as that of an automobile is required, and realization of a life performance of 10 years or more (high durability) is required. Graphite materials or carbonaceous materials with a developed graphite structure are prone to breakage due to expansion and contraction of crystals due to repeated lithium doping and undoping, and inferior repeated charge / discharge performance, so high cycle durability is required It is not suitable as a negative electrode material for lithium ion secondary batteries. In contrast, graphitizable carbon varies depending on the development rate of the crystal structure, but the expansion and contraction of particles due to lithium doping and dedoping reactions are relatively small compared to graphitic materials. These carbonaceous materials are suitable for use in automobile applications from the viewpoint of having high cycle durability since they are smaller than carbonizable carbon. However, easily graphitizable carbon and non-graphitizable carbon are not discharged (reaction of dedoping lithium from carbonaceous material) even when charged (reaction of doping carbonaceous material with lithium) in the initial charge / discharge, so-called There are many irreversible capacities (capacity obtained by subtracting discharge capacity from charge capacity), and a corresponding positive electrode active material is required, which has the problem of lowering energy density. There is a need for improved battery performance.

Attempts have been made to reduce the irreversible capacity in order to improve the performance of lithium ion secondary batteries. Lithium desorbed from the positive electrode active material in the first charging process is taken into the carbonaceous material (negative electrode active material) of the negative electrode. The lithium taken into the carbonaceous material of the negative electrode is desorbed from the carbonaceous material in the discharge process and taken into the positive electrode active material. A part of the lithium taken into the carbonaceous material cannot be desorbed from the negative electrode active material and remains in the carbonaceous material. Since the lithium remaining in the carbonaceous material cannot participate in charging / discharging, the discharge capacity decreases.
In order to prevent this reduction in discharge capacity, a method is disclosed in which an amount of lithium corresponding to lithium remaining in the carbonaceous material is excessively contained in advance in a positive electrode active material to compensate for loss due to irreversible capacity (Patent Document 1). . In addition, it is disclosed that a reduction in discharge capacity is prevented by containing a lithium compound that desorbs lithium at a lower voltage than in a positive electrode active material (Patent Document 2).

JP-A-4-181660 JP-A-6-342673

An initial battery capacity has been improved by a secondary battery including a positive electrode including a positive electrode active material containing a large amount (excess) of lithium and a negative electrode including a carbon negative electrode material as a negative electrode active material. However, the positive electrode active material containing excessive lithium has a problem that the electrochemical stability is poor in the charge / discharge cycle, and the battery capacity decreases in the long-term charge / discharge cycle. Furthermore, not only the positive electrode is deteriorated, but also the transition metal of the positive electrode active material is eluted into the electrolyte during charge / discharge, and moves to the negative electrode side to cause side reactions, leading to a decrease in battery capacity and a decrease in safety. There was a problem.
An object of the present invention is to provide a nonaqueous electrolyte secondary battery excellent in long-term cycle characteristics.

As a result of earnest research on a secondary battery having excellent initial battery capacity and excellent long-term cycle characteristics, the inventor has surprisingly found a positive electrode including a positive electrode active material containing a large amount of lithium, Alternatively, by combining a positive electrode including a positive electrode active material added with a lithium compound that desorbs lithium at a low voltage and a negative electrode including a carbonaceous material containing a certain amount of sulfur as a negative electrode active material, It has been found that by reducing the irreversible capacity, the battery has a high charge / discharge capacity, and can further suppress a decrease in battery capacity in a charge / discharge cycle (a high capacity retention rate can be achieved).
The present invention is based on these findings.
Therefore, the present invention
[1] (I) (a) General formula (1):
_{A x + α M y B β} O z-γ (1)
(Wherein A is Li ⁺ , x is 1, 2 or 3, and α is 0 <α ≦ 1, M is selected from the group consisting of transition metals, alkali metals, alkaline earth metals, and aluminum. One or more elements, and y is 1 or 2, B is P or Si, β is 0 ≦ β ≦ 1, z is 2, 3, or 4, and γ is 0 ≦ γ ≦ 0. 05)
Or a positive electrode containing a positive electrode active material represented by (b) General formula (2):
_{A x M y B β O z} (2)
Wherein A is Li ⁺ , and x is 1, 2, or 3, M is one or more elements selected from the group consisting of transition metals, alkali metals, alkaline earth metals, and aluminum, and y is 1 or 2, B is P or Si, β is 0 ≦ β ≦ 1, z is 2, 3, or 4), and the charge / discharge potential with respect to the counter lithium is A positive electrode including a lithium-containing oxide that is present at 3.3 V or lower and an average discharge voltage exceeding 3.3 V is 3.4 to 5.0 V, and (II) determined by an X-ray diffraction method (002) Average layer spacing d ₀₀₂ is 0.345 to 0.400 nm, crystallite size Lc ₍₀₀₂₎ in the c-axis direction is 1.0 to 20.0 nm, specific surface area is 1 to 50 g / m ² , butanol true density ρ _BtOH is 1.45~2.20g / ^cm 3, Fine sulfur element content of 75~3500μg / g, a negative electrode containing a graphitizable or non-graphitizable carbonaceous material,
Non-aqueous electrolyte secondary battery, including
[2] The non-aqueous electrolyte secondary battery according to [1], wherein the graphitizable carbonaceous material or non-graphitizable carbonaceous material is a carbonaceous material produced using pitch as a carbon source, or [ 3] A vehicle equipped with the nonaqueous electrolyte secondary battery according to [1] or [2],
About.

  According to the nonaqueous electrolyte secondary battery of the present invention, it is possible to obtain a nonaqueous electrolyte secondary battery having excellent initial battery capacity and further excellent long-term cycle characteristics. Since the nonaqueous electrolyte secondary battery of the present invention has excellent cycle characteristics, it requires a long life and high input / output characteristics, such as a car (for example, a hybrid vehicle (HEV), a plug-in hybrid vehicle (PHEV), and an electric vehicle). (EV)) It can be effectively used as a mounting power source.

The reason why the nonaqueous electrolyte secondary battery of the present invention is excellent in the initial battery capacity and in the long-term cycle characteristics is not completely elucidated, but can be considered as follows. However, the present invention is not limited by the following description.
A negative electrode made of a negative electrode active material (carbonaceous material) having the above-mentioned physical properties, a positive electrode containing a positive electrode active material containing excess lithium, or a positive electrode added with a lithium compound or the like that releases lithium at a low voltage By combining with a positive electrode containing an active material, the battery voltage at the time of forming a SEI (Solid Electrolyte Interface) film formed on the negative electrode surface is lowered. Then, the reaction rate and activation energy of electrons or ions change, and the properties of SEI on the negative electrode surface change. Therefore, the SEI in the nonaqueous electrolyte secondary battery of the present invention has a low resistance, and an increase in the average discharge voltage of the battery and a decrease in the battery capacity during the charge / discharge cycle are suppressed.
The positive electrode containing a positive electrode active material containing excessive lithium has an unstable structure, and the transition metal oxide elutes into the electrolyte during charge and discharge, and further moves to the negative electrode to cause a side reaction. There is. However, when the negative electrode active material contains a certain amount of sulfur element, sulfur acts as a catalyst, suppresses this side reaction, and suppresses a decrease in battery capacity during the charge / discharge cycle.

It is the figure which showed the charging / discharging electric potential of the lithium ion secondary battery (A) using the positive electrode to which the lithium containing oxide of this invention was added, and the lithium ion secondary battery (B) using the conventional positive electrode.

《Nonaqueous electrolyte secondary battery》
The nonaqueous electrolyte secondary battery of the present invention comprises (I) (a) general formula (1):
_{A x + α M y B β} O z-γ (1)
(Wherein A is Li ⁺ , x is 1, 2 or 3, and α is 0 <α ≦ 1, M is selected from the group consisting of transition metals, alkali metals, alkaline earth metals, and aluminum. 1 or more elements, and y is 1 or 2, B is P or Si, β is 0 ≦ β ≦ 1, z is 2, 3, or 4, and γ is 0 ≦ γ ≦ 0.05. Or a positive electrode containing a positive electrode active material represented by formula (2):
_{A x M y B β O z} (2)
Wherein A is Li ⁺ , and x is 1, 2, or 3, M is one or more elements selected from the group consisting of transition metals, alkali metals, alkaline earth metals, and aluminum, and y is 1 or 2, B is P or Si, β is 0 ≦ β ≦ 1, z is 2, 3, or 4), and the charge / discharge potential for the counter electrode lithium is 3. A lithium-containing oxide which is present at 3 V or less and whose average discharge voltage exceeds 3.3 V is 3.4 to 5.0 V;
(002) The average layer surface distance d ₀₀₂ obtained by X-ray diffraction method is 0.345 to 0.400 nm, and the crystallite size Lc _{(002) in} the c-axis direction is 1.0. ˜20.0 nm, specific surface area of 1 to 50 g / m ² , butanol true density ρ _BtOH of 1.45 to 2.20 g / cm ³ , sulfur element content of 75 to 3500 μg / g, graphitizable or A negative electrode containing a non-graphitizable carbonaceous material.

<< Positive electrode >>
As one aspect of the positive electrode, a lithium chalcogen compound containing excess lithium represented by the general formula (1) (hereinafter sometimes referred to as a lithium-excess chalcogen compound), a binder (binder), a conductive material And a current collector.
Moreover, as another aspect of a positive electrode, the lithium chalcogen compound represented by General formula (2), the said lithium containing oxide, a electrically conductive material, and an electrical power collector are included.

(Lithium-rich chalcogen compound)
The lithium-excess chalcogen compound used in the present invention is not limited as long as lithium is excessively contained, but a lithium chalcogen compound having a layered structure, a lithium chalcogen compound having an olivine structure, or lithium having a spinel structure Examples thereof include a chalcogen compound in which lithium is excessively contained.
The lithium chalcogen compound having a layered structure has a layered structure and is expressed as LiMO _2, and M is a transition metal and a part of the transition metal substituted with a different transition metal, an alkaline earth metal, or aluminum Means. _{Specifically, LiCoO 2, LiNiO 2, LiMnO} 2 or _{LiNi x Co y Mn z O 2} ( where x, y, z represent the composition ratio, x + y + z = 1 ) different portions of the transition metals as The thing substituted with the element can be mentioned.
Further, the lithium chalcogen compound having an olivine structure has an olivine structure and is represented as LiMPO ₄ or Li ₂ MSiO ₄ , where M is a transition metal and a part of the transition metal as a heterogeneous transition metal or an alkaline earth metal. Or substituted with aluminum. Specifically _{LiFePO 4, LiCoPO 4, LiVPO 4} , LiVPO 4 F, LiMnPO 4, LiMn 7/8 Fe 1/8 PO 4, LiNiVO 4, LiCoPO 4, Li 3 V 2 (PO 4) 3, LiFeP 2 O _{7, Li 3 Fe 2 (PO} 4) 3, Li 2 CoSiO 4, Li 2 MnSiO 4, Li 2 FeSiO 4, LiNi x Co y Mn z PO 4, or _{Li 2 Ni x Co y Mn z} SiO 4 ( wherein x, y, and z represent a composition ratio, and examples include x, y, z = 1) in which a part of the transition metal is substituted with a different element.
Further, a lithium chalcogen compound having a spinel structure has a spinel structure and is expressed as LiM ₂ O ₄ , where M is a transition metal and a part of the transition metal is a different transition metal, alkaline earth metal, or aluminum. Means a replacement. _{Specifically, LiMn 2 O 4, LiCo 2} O 4, LiFe 2 O 4, or _{LiNi x Co y Mn z O 4} ( wherein x, y, z represent the composition ratio, x + y + z = 2 ) as Examples thereof include a transition metal partially substituted with a different element.
The lithium-excess chalcogen compound is not limited, but is preferably a lithium-excess chalcogen compound having a layered structure or a lithium-excess chalcogen compound having a spinel structure, more preferably a lithium-excess chalcogen compound having a spinel structure. is there. This is because the structural stability is high and the reversible reaction can be maintained for a long time.

  The lithium-excess chalcogen compound used in the present invention is a lithium chalcogen compound having a layered structure, a lithium chalcogen compound having an olivine structure, or a lithium chalcogen compound having a spinel structure doped with lithium ions. The doping of lithium ions can be performed by a known method, but an electrochemical method or a chemical method can be used.

  Although it does not limit as an electrochemical method, the following methods can be used. A conductive material and a binder are added to the lithium chalcogen compound having a layered structure, the lithium chalcogen compound having an olivine structure, or the lithium chalcogen compound having a spinel structure to manufacture a positive electrode. Using metallic lithium as a counter electrode, an energization treatment is performed in a non-aqueous solvent, and the positive electrode is doped with lithium. By this method, a lithium-excess chalcogen compound containing excessive lithium ions can be obtained.

Although it does not limit as a chemical method, the following methods can be used. The lithium chalcogen compound having a layered structure, the lithium chalcogen compound having an olivine structure, or the lithium chalcogen compound having a spinel structure is immersed in a lithium compound solution and doped with lithium ions, and if necessary, 300 to 450 ° C. A lithium-excess chalcogen compound containing an excessive amount of lithium ions can be obtained by performing a heat treatment. Examples of the lithium compound include organic compounds such as n-butyllithium, sec-butyllithium, or tert-butyllithium, and lithium salts such as lithium oxalate, lithium iodide, or lithium nitrate. Doping is performed using an aqueous solution of these lithium organic compounds or lithium salts. When a lithium organic compound is used, for example, LiMO ₂ is immersed in a solution and reacted, and then washed with a solvent, which can be used as a positive electrode active material. When lithium salt is used, LiMO ₂ is immersed in a solution and then heat-treated at 300 to 450 ° C., preferably 300 to 400 ° C. to dope lithium, and lithium excess chalcogen containing excessive lithium ions A compound can be obtained.
Alternatively, the transition metal oxide and lithium hydroxide can be mixed at an arbitrary ratio, and can be obtained by firing at, for example, 680 ° C. in the air atmosphere.

In the lithium-excess chalcogen compound represented by the general formula (1), α is not limited as long as 0 <α ≦ 1, but the lower limit of α is preferably 0.04 or more, more Preferably it is 0.10 or more. The upper limit of α is preferably 0.30 or less, and more preferably 0.20 or less. When α is 0.10 to 0.20, it is preferable in that a sufficient effect can be obtained.
In the lithium-excess chalcogen compound, M is not particularly limited as long as it is a metal selected from the group consisting of transition metals, alkali metals, alkaline earth metals, and aluminum. ), Cobalt (Co), nickel (Ni), magnesium (Mg), aluminum (Al), iron (Fe), vanadium (V), molybdenum (Mo), copper (Cu), titanium (Ti), or chromium ( Cr). y is 1 or 2.
In the lithium-excess chalcogen compound, B is P or Si, and β is 0 ≦ β ≦ 1. When B is P or Si and β is 1, the lithium-excess chalcogen compound is a lithium chalcogen compound having an olivine structure. On the other hand, when β is 0, the lithium-excess chalcogen compound is a lithium chalcogen compound having a layered structure or a lithium chalcogen compound having a spinel structure.
In the lithium-excess chalcogen compound, z is 2, 3, or 4, and γ is 0 ≦ γ ≦ 0.05. When z is 2 or 3, the lithium excess chalcogen compound is a lithium excess chalcogen compound having a layered structure, and when z is 4, the lithium excess chalcogen compound is a lithium excess chalcogen compound having a spinel structure.

(Lithium chalcogen compound)
The lithium chalcogen compound represented by the general formula (2) is not particularly limited. Specifically, the lithium chalcogen compound having the layered structure, the lithium chalcogen compound having the olivine structure, or the spinel structure is used. A lithium chalcogen compound can be mentioned.
In the lithium chalcogen compound, M is not particularly limited as long as it is a metal selected from the group consisting of transition metals, alkali metals, alkaline earth metals, and aluminum, but preferably manganese (Mn) , Cobalt (Co), nickel (Ni), magnesium (Mg), aluminum (Al), iron (Fe), vanadium (V), molybdenum (Mo), copper (Cu), titanium (Ti), or chromium (Cr ). y is 1 or 2.
In the lithium chalcogen compound, B is P or Si, and β is 0 ≦ β ≦ 1. When B is P or Si and β is 1, the lithium chalcogen compound is a lithium chalcogen compound having an olivine structure. On the other hand, when β is 0, the lithium chalcogen compound is a lithium chalcogen compound having a layered structure or a lithium chalcogen compound having a spinel structure.
In the lithium chalcogen compound, z is 2, 3, or 4. When z is 2 or 3, the lithium chalcogen compound is a lithium chalcogen compound having a layered structure, and when z is 4, the lithium chalcogen compound is a lithium chalcogen compound having a spinel structure.

(Lithium-containing oxide)
The lithium-containing oxide has a charge / discharge potential with respect to the counter electrode lithium of 3.3 V or less, and an average discharge voltage exceeding 3.3 V is 3.4 to 5.0 V. That is, it is preferable that lithium be dedoped before the main positive electrode active material (lithium chalcogen compound) contained in the positive electrode and intercalate with the negative electrode. As shown in FIG. 1A, when the positive electrode of the present invention to which a lithium-containing oxide is added is used, the charge / discharge potential exists at 3.3 V or lower, so that lithium ions are present prior to the lithium chalcogen compound. Released and SEI is formed. For this reason, the irreversible capacity | capacitance of a lithium chalcogen compound can be decreased. On the other hand, as shown in FIG. 1B, when a conventional positive electrode is used, the charge / discharge potential does not exist at 3.3 V or lower, and Li of the lithium chalcogen compound is consumed for the formation of SEI. The irreversible capacity of the compound increases.
Examples of the lithium-containing oxide include Li _x MO _y (M is a transition metal such as Mo, Mn, Co, Ni, Fe), TiS ₂ , or lithium manganese composite oxide such as LiMn ₃ O ₆ . Examples include those having a potential of 3 V (vs. Li / Li ⁺ ). Further, Li ₃ FeF ₆ , LiNiOF, or Li ₂ FeO ₂ F containing fluorine can also be used.

Examples of the Li _x MO _y include Li ₂ MoO ₃ , Li ₂ Mn ₂ O ₄ , Li ₂ NiO, Li ₂ NiO _3-a , Li _{1 + a} Ni _1-a O ₂ (LiNiO having a Li / Ni ratio greater than 1). ₂ ), Li ₆ CoO ₄ , Li ₂ CoSiO ₄ , LiCuO, Li ₆ Mo ₂ O, Li ₉ TiN ₃ O ₂ , Li ₈ CoO ₆ , Li ₆ Fe ₂ O ₃ , Li ₅ Fe ₂ O ₃ , Li ₃ Fe ₂ O ₃ , Li ₂ FeO ₂ , or Li ₂ Fe ₂ O ₃ can be mentioned.

The lithium-containing oxide active material preferably has a characteristic that its capacity is larger than that of the lithium chalcogen compound contained in the positive electrode. Since this characteristic is determined by the relationship with the lithium chalcogen compound contained in the positive electrode, the lithium-containing oxide to be used is preferably determined by the relationship with the lithium chalcogen compound.
The amount of the lithium-containing oxide contained in the positive electrode is preferably determined according to the amount of Li uptake in the carbonaceous material of the negative electrode, but is preferably 0.04 to 1.00, for example, in terms of the number of moles of Li. Is from 0.10 to 0.20.

(Current collector)
As the current collector used for the positive electrode, various materials conventionally used or proposed can be used. For example, a metal material such as aluminum, stainless steel, nickel plating, titanium or tantalum, or a carbon material such as carbon cloth or carbon paper is preferable, and a metal material is preferable, and aluminum is particularly preferable.

(Binder (binder))
The binder used in the positive electrode is not particularly limited as long as it does not react with the electrolytic solution. For example, polyvinylidene fluoride (PVdF), polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), polytetrafluoroethylene (PTFE). Styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), ethylene-propylene-diene copolymer (EPDM), fluororubber (FR), acrylonitrile-butadiene rubber (NBR), sodium polyacrylate, propylene or carboxymethylcellulose (CMC). One of these binders may be used alone, or a combination of two or more suitable ratios may be used.

  The content of the binder is not particularly limited, but the lower limit is preferably based on the substance contained in the positive electrode (here, positive electrode active material amount + binder amount + conductive material amount = 100 wt%). It is 0.1 mass% or more, More preferably, it is 0.5 mass% or more, More preferably, it is 1.0 mass% or more, Most preferably, it is 1.5 mass% or more. The upper limit is preferably 8.0% by mass or less, more preferably 6.0% by mass or less, still more preferably 4.0% by mass or less, and most preferably 3% with respect to the substance contained in the positive electrode. 0.0 mass% or less. When the content of the binder is 0.1% by mass to 8.0% by mass, good bonding between the current collector foil and the particles is maintained, and an increase in electronic resistance due to the binder is also suppressed.

(Conductive aid)
As the conductive auxiliary agent used for the positive electrode, various materials conventionally used or proposed can be used. Examples thereof include metal materials such as copper or nickel, graphite materials such as natural graphite or artificial graphite, carbon blacks such as acetylene black, and amorphous carbonaceous materials such as needle coke. One of these conductive aids may be used alone, or a combination of two or more suitable ratios may be used.
The content of the conductive auxiliary agent is not particularly limited, but the lower limit is based on the substance contained in the positive electrode (here, positive electrode active material amount + binder amount + conductive auxiliary agent amount = 100 wt%), Preferably it is 0.01 mass% or more, More preferably, it is 0.05 mass% or more, More preferably, it is 0.1 mass% or more, Most preferably, it is 1 mass% or more. The upper limit is preferably 5.0% by mass or less, more preferably 4.0% by mass or less, still more preferably 3.5% by mass or less, and most preferably 3% by mass with respect to the substance contained in the positive electrode. 0.0 mass% or less. When the content of the conductive auxiliary agent is 0.01% by mass to 5.0% by mass, it is possible to reduce resistance while suppressing a decrease in capacity.

(solvent)
When producing a positive electrode, a solvent is added to the positive electrode active material, the binder, and the conductive additive and kneaded. As the solvent, any solvent that can be used at the time of producing the positive electrode for a non-aqueous electrolyte secondary battery can be used without limitation. Examples thereof include water and a mixed medium of alcohol and water. Examples of the organic medium include aliphatic hydrocarbons such as hexane, aromatic hydrocarbons such as benzene, toluene, xylene, and methylnaphthalene, heterocyclic compounds such as quinoline and pyridine, acetone, methyl ethyl ketone, Or ketones such as cyclohexanone, esters such as methyl acetate or methyl acrylate, amines such as diethylenetriamine, or N, N-dimethylaminopropylamine, and ethers such as diethyl ether, propylene oxide, or tetrahydrofuran (THF) Amides such as N-methylpyrrolidone (NMP), dimethylformamide, or dimethylacetamide, and aprotic polar solvents such as hexamethylphosphalamide, dimethylsulfoxide, etc. It can be.

<Negative electrode>
The negative electrode used in the present invention has a (002) average layer surface distance d ₀₀₂ of 0.345 to 0.400 nm and a crystallite size Lc _{(002) in} the c-axis direction of 1.0 determined by an X-ray diffraction method. ˜20.0 nm, specific surface area of 1 to 50 g / m ² , butanol true density ρ _BtOH of 1.45 to 2.20 g / cm ³ , sulfur element content of 75 to 3500 μg / g, graphitizable or A non-graphitizable carbonaceous material is included as a negative electrode active material. The negative electrode usually contains a binder (binder) and a current collector in addition to the negative electrode active material. Moreover, you may contain a conductive support agent as needed.

(Butanol true density)
The true density of the graphite material having an ideal structure is 2.2 g / cm ³ , and the true density tends to decrease as the crystal structure is disturbed. Therefore, the true density can be used as an index representing the structure of carbon. The butanol true density of the carbonaceous material used in the present invention is 1.45 to 2.15 g / cm ³ , but carbonaceous materials in the range of 1.70 to 2.15 g / cm ³ are graphitizable here. It is called carbon, and 1.45 to 1.70 g / cm ³ is called non-graphitizable carbon. In the case of an easily graphitizable carbonaceous material, the true density is 1.70 to 2.15 g / cm ³ , more preferably 1.90 to 2.15 g / cm ³ . On the other hand, in the case of a non-graphitizable carbonaceous material, the true density is 1.45 to 1.70 g / cm ³ , more preferably 1.45 to 1.65 g / cm ³ . A carbonaceous material having a true density that is too high is not preferred because it has a small number of pores that can store lithium, and the doping and dedoping capacity is small. Further, since the increase in true density is accompanied by selective orientation of the carbon hexagonal plane, it is not preferable because the carbonaceous material often involves expansion and contraction during lithium doping / dedoping. On the other hand, a carbon material of less than 1.45 g / cm ³ is not preferable because closed holes may increase and the doping and dedoping capacity may be reduced. Furthermore, since the electrode density is lowered, the volume energy density is lowered, which is not preferable.

  The average layer spacing of the (002) plane of the carbonaceous material shows a smaller value as the crystal perfection is higher, that of an ideal graphite structure shows a value of 0.3354 nm, and the value increases as the structure is disturbed. Tend. Therefore, the average layer spacing is effective as an index indicating the carbon structure. The carbonaceous material of the present invention is an easily graphitizable carbonaceous material or a hardly graphitizable carbonaceous material, and the average layer spacing of (002) planes measured by X-ray diffraction method is 0.345 nm or more and 0.40 nm or less. More preferably, it is 0.365 nm or more and 0.400 nm or less. Most preferably, it is 0.375 nm or more and 0.400 nm or less. In the case of an easily graphitizable carbonaceous material, the average layer spacing of the (002) plane measured by X-ray diffraction method is 0.345 nm or more and 0.365 nm or less, more preferably 0.345 nm or more and 0.360 nm or less. . On the other hand, in the case of a non-graphitizable carbonaceous material, the average layer spacing of the (002) plane measured by the X-ray diffraction method is 0.365 nm or more and 0.40 nm or less, more preferably 0.370 nm or more and 0.400 nm or less. is there. Most preferably, it is 0.375 nm or more and 0.400 nm or less. A non-graphitizable carbonaceous material having an average layer surface spacing of 0.365 nm or more is preferable because cycle characteristics are improved. That is, when a non-graphitizable carbonaceous material is used as the negative electrode, it is excellent in durability due to lithium doping and dedoping reactions. In other words, the non-graphitizable carbonaceous material is smaller in expansion / contraction during charging / discharging than the graphite and is excellent in repeated performance (so-called durability).

The crystallite size Lc ₍₀₀₂₎ in the c-axis direction of the carbonaceous material used in the present invention is 1.0 to 20.0 nm, preferably 1.0 to 10 nm, and more preferably 1.0 to 5.0 nm. When Lc ₍₀₀₂₎ is too large, the closed pores increase and the doping / dedoping capacity decreases, or the graphite material is easily collapsed or the electrolytic solution is decomposed due to doping / undoping of the active material, which is not preferable. On the other hand, when Lc ₍₀₀₂₎ is too small, the formation of the carbon skeleton is insufficient, which is not preferable.

The BET specific surface area of the carbonaceous material used for this invention is 1-50 m < ² > / g, Preferably it is 1-10 m < ² > / g. When the BET specific surface area exceeds 50 m ² / g, when used as a negative electrode of a non-aqueous electrolyte secondary battery, the decomposition reaction with the electrolytic solution increases, leading to an increase in irreversible capacity, and thus the battery performance decreases. . On the other hand, when the BET specific surface area is less than 1 m ² / g, when used as a negative electrode of a non-aqueous electrolyte secondary battery, the input / output characteristics may be deteriorated due to a decrease in the reaction area with the electrolytic solution. .

  The carbonaceous material used in the present invention contains 75 to 3500 μg / g of elemental sulfur. The lower limit of the sulfur element content of the carbonaceous material is preferably 80 μg / g or more, more preferably 90 μg / g or more, still more preferably 100 μg / g or more, and most preferably 110 μg / g or more. . The upper limit of the sulfur element content of the carbonaceous material is preferably 3000 μg / g or less, more preferably 2500 μg / g or less, still more preferably 2000 μg / g or less, and even more preferably 1500 μg / g or less. Most preferably, it is 1000 μg / g or less. Sulfur catalysis suppresses the problem that the transition metal oxide eluted in the electrolyte during charge / discharge moves to the negative electrode side and causes side reactions when the sulfur element content is 75-3500 μg / g. can do. As a result, long-term cycle characteristics can be improved.

  As a carbon source for producing a carbonaceous material, an easily graphitizable carbonaceous material or a non-graphitizable carbonaceous material produced from a thermosetting resin or thermoplastic resin containing elemental sulfur is used as the negative electrode in the present invention. It can be used as an active material. In addition, when using a thermosetting resin or a thermoplastic resin that does not contain elemental sulfur, an easily graphitizable carbonaceous material manufactured from a resin in which an appropriate amount of sulfur is added or a resin containing elemental sulfur is mixed, or A non-graphitizable carbonaceous material can be used as the negative electrode active material in the present invention. Furthermore, although petroleum or coal, which is a raw material such as petroleum pitch or coal pitch, contains sulfur, the sulfur content varies greatly depending on the production area. Also, since petroleum is desulfurized during its refining process, the sulfur content of petroleum pitch or coal pitch is also greatly different. Therefore, by using petroleum pitch or coal pitch having an optimum sulfur content, an easily graphitizable carbonaceous material or a hardly graphitizable carbonaceous material that can be used in the present invention can be produced. However, when petroleum pitch or the like having a high sulfur content is used, it is possible to obtain a carbonaceous material having an optimal sulfur content by performing desulfurization. Moreover, when using petroleum pitch etc. with small sulfur content, it is possible to obtain the carbonaceous material of the optimal sulfur content by adding a suitable amount of sulfur.

  The Li-NMR of the carbonaceous material used in the present invention is 25 to 130 ppm. In the case of an easily graphitizable carbonaceous material, Li-NMR is 10-40 ppm, More preferably, it is 25-40 ppm. On the other hand, in the case of a non-graphitizable carbonaceous material, Li-NMR is 55-130 ppm, More preferably, it is 80-120 ppm. The rapid charge / discharge performance is excellent when the Li-NMR of the graphitizable carbonaceous material is 10 to 40 ppm and the Li-NMR of the non-graphitizable carbonaceous material is 55 to 130 ppm.

  Although the average particle diameter of the carbonaceous material used for this invention is not specifically limited, Preferably it is 3-50 micrometers, More preferably, it is 3-30 micrometers, Especially preferably, it is 3-10 micrometers. In order to improve the output characteristics in the performance of the nonaqueous electrolyte secondary battery, it is important to reduce the resistance by reducing the thickness of the active material layer of the electrode. Further, when the average particle diameter is 50 μm or less, the lithium diffusion length in the particles is shortened, which is preferable during rapid charging.

  The carbon source of the graphitizable carbonaceous material is not particularly limited, and examples thereof include petroleum pitch or tar, coal pitch or tar, or a thermoplastic resin. Thermoplastic resins include polyacetal, polyacrylonitrile, styrene / divinylbenzene copolymer, polyimide, polycarbonate, modified polyphenylene ether, polybutylene terephthalate, polyarylate, polysulfone, polyphenylene sulfide, fluororesin, polyamideimide, polyetheretherketone, Or a polyvinyl chloride can be mentioned.

  The carbon source of the non-graphitizable carbonaceous material is not particularly limited, and examples thereof include petroleum pitch or tar, coal pitch or tar, thermoplastic resin, or thermosetting resin. Examples of the thermoplastic resin include polyacetal, polyacrylonitrile, styrene / divinylbenzene copolymer, polyimide, polycarbonate, modified polyphenylene ether, polybutylene terephthalate, polyarylate, polysulfone, polyphenylene sulfide, fluororesin, polyamideimide, polyetheretherketone. Or polyvinyl chloride. Furthermore, examples of the thermosetting resin include polyimide, phenol resin, amino resin, unsaturated polyester resin, diallyl phthalate resin, alkyd resin, epoxy resin, and urethane resin. In addition, when using petroleum pitch or tar, etc. and a thermoplastic resin as a carbon source, it is necessary to make those carbon sources infusible by oxidation treatment.

(Manufacture of carbonaceous material from tar or pitch)
An example of the method for producing the non-graphitizable carbonaceous material of the present invention from tar or pitch will be described below.
First, the crosslinking treatment (infusibilization) for tar or pitch is intended to make the carbonaceous material obtained by carbonizing the tar or pitch subjected to crosslinking treatment non-graphitizable. In addition, when a crosslinking process is not performed or when a crosslinking process is weak, an easily graphitizable carbonaceous material can be obtained. Tar or pitch includes petroleum tar or pitch replicated during ethylene production, coal tar produced during coal carbonization, heavy component or pitch obtained by distilling off low boiling components of coal tar, tar or pitch obtained by liquefaction of coal Oil or coal tar or pitch can be used. Two or more of these tars and pitches may be mixed.
As described above, petroleum and coal differ greatly in sulfur content depending on their production areas. Therefore, when pitches with a high sulfur content are used, desulfurization treatment is performed, and when pitches with a low sulfur content are used, a carbonaceous material with an appropriate sulfur content can be obtained by adding a sulfur compound. Can be obtained.

  Specifically, as a method for infusibilization, there are a method using a crosslinking agent, a method of treating with an oxidizing agent such as air, and the like. When using a cross-linking agent, a carbon precursor is obtained by adding a cross-linking agent to petroleum tar or pitch, or coal tar or pitch and heating and mixing to proceed with a cross-linking reaction. For example, as the crosslinking agent, polyfunctional vinyl monomers such as divinylbenzene, trivinylbenzene, diallyl phthalate, ethylene glycol dimethacrylate, or N, N-methylenebisacrylamide that undergo a crosslinking reaction by radical reaction can be used. The crosslinking reaction with the polyfunctional vinyl monomer is started by adding a radical initiator. As a radical initiator, α, α ′ azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), lauroyl peroxide, cumene hydroperoxide, 1-butyl hydroperoxide, hydrogen peroxide, or the like can be used. .

  Moreover, when a crosslinking reaction is advanced by treating with an oxidizing agent such as air, it is preferable to obtain a carbon precursor by the following method. That is, after adding a 2- or 3-ring aromatic compound having a boiling point of 200 ° C. or higher or a mixture thereof to an oil-based or coal-based pitch and heating and mixing, it is molded to obtain a pitch molded body. Next, the additive is extracted and removed from the pitch molded body with a solvent having low solubility with respect to pitch and high solubility with respect to the additive to form a porous pitch, which is then oxidized with an oxidizing agent, and then carbon precursor. Get the body. The purpose of the aromatic additive is to extract and remove the additive from the molded pitch molded body to make the molded body porous, to facilitate crosslinking treatment by oxidation, and to obtain a carbonaceous material obtained after carbonization. To make it porous. As said additive, it can select from 1 type, or 2 or more types of mixtures, such as naphthalene, methyl naphthalene, phenyl naphthalene, benzyl naphthalene, methyl anthracene, phenanthrene, or biphenyl, for example. The amount of the aromatic additive added to the pitch is preferably in the range of 30 to 70 parts by weight with respect to 100 parts by weight of the pitch.

  The pitch and additive are mixed in a molten state by heating in order to achieve uniform mixing. The mixture of the pitch and the additive is preferably performed after being formed into particles having a particle diameter of 1 mm or less so that the additive can be easily extracted from the mixture. Molding may be performed in a molten state, or may be performed by a method such as pulverizing the mixture after cooling. Solvents for extracting and removing the additive from the mixture of pitch and additive include aliphatic hydrocarbons such as butane, pentane, hexane, or heptane, mixtures mainly composed of aliphatic hydrocarbons such as naphtha or kerosene, methanol, Aliphatic alcohols such as ethanol, propanol or butanol are preferred. By extracting the additive from the pitch and additive mixture molded body with such a solvent, the additive can be removed from the molded body while maintaining the shape of the molded body. At this time, it is presumed that a through hole for the additive is formed in the molded body, and a pitch molded body having uniform porosity is obtained.

In order to crosslink the resulting porous pitch, it is then oxidized using an oxidizing agent, preferably at a temperature of 120-400 ° C. As the oxidizing agent, O ₂ , O ₃ , NO ₂ , a mixed gas obtained by diluting these with air, nitrogen, or the like, or an oxidizing gas such as air, or an oxidizing liquid such as sulfuric acid, nitric acid, or hydrogen peroxide water is used. be able to. It is simple and economical to oxidize at 120 to 400 ° C. and carry out a crosslinking treatment using a gas containing oxygen such as air or a mixed gas of air and other gas such as combustion gas as an oxidizing agent. Is also advantageous. In this case, if the pitch has a low softening point, the pitch melts during oxidation, making it difficult to oxidize. Therefore, the pitch used preferably has a softening point of 150 ° C. or higher.
The carbon precursor subjected to the crosslinking treatment as described above is pre-fired and then carbonized at 900 ° C. to 1600 ° C. in a non-oxidizing gas atmosphere to obtain the carbonaceous material of the present invention. Can do.

(Manufacture of carbonaceous material from resin)
A method for producing a non-graphitizable carbonaceous material from a thermosetting resin will be described below with an example.
The carbonaceous material used in the present invention can also be obtained by carbonizing at 900 ° C. to 1600 ° C. using a sulfur-containing resin as a precursor. In the case of a resin not containing sulfur, it is preferable to add a sulfur compound (for example, polyphenylene sulfide resin or polysulfone) in order to obtain a carbonaceous material having an appropriate sulfur content.
As the resin, a phenol resin, a furan resin, or the like, or a thermosetting resin obtained by partially modifying the functional group of these resins can be used. It can also be obtained by pre-baking the thermosetting resin at a temperature of 900 ° C. or lower, if necessary, and then pulverizing and carbonizing at 900 ° C. to 1600 ° C. Oxidation treatment (infusibilization treatment) may be performed at a temperature of 120 to 400 ° C. as necessary for the purpose of promoting curing of the thermosetting resin, promoting the degree of crosslinking, or improving the carbonization yield. As the oxidizing agent, O ₂ , O ₃ , NO ₂ , a mixed gas obtained by diluting these with air, nitrogen, or the like, or an oxidizing gas such as air, or an oxidizing liquid such as sulfuric acid, nitric acid, or hydrogen peroxide water is used. be able to. Although the pulverization step can be performed after carbonization, since the carbon precursor becomes hard as the carbonization reaction proceeds, it becomes difficult to control the particle size distribution by pulverization. It is preferable before the main baking later.
Furthermore, a carbon precursor obtained by subjecting a thermoplastic resin such as polyacrylonitrile or a styrene / divinylbenzene copolymer to infusibilization treatment can also be used. In these resins, for example, a monomer mixture obtained by mixing a radically polymerizable vinyl monomer and a polymerization initiator is added to an aqueous dispersion medium containing a dispersion stabilizer and suspended by stirring to suspend the monomer mixture into fine droplets. Then, it can be obtained by proceeding radical polymerization by raising the temperature. The obtained resin can be made into a spherical carbon precursor by developing a crosslinked structure by infusibilization treatment. The oxidation treatment can be performed in a temperature range of 120 to 400 ° C., particularly preferably 170 to 350 ° C., more preferably 220 to 350 ° C. As the oxidizing agent, O ₂ , O ₃ , SO ₃ , NO ₂ , a mixed gas obtained by diluting these with air, nitrogen, or the like, or an oxidizing gas such as air, or an oxidizing property such as sulfuric acid, nitric acid, hydrogen peroxide water, or the like Liquid can be used. Thereafter, the carbon precursor that is infusible to heat as described above is pre-fired as necessary, and then pulverized and carbonized at 900 ° C. to 1600 ° C. in a non-oxidizing gas atmosphere. The carbonaceous material of the present invention can be obtained. Although the pulverization step can be performed after carbonization, since the carbon precursor becomes hard as the carbonization reaction proceeds, it becomes difficult to control the particle size distribution by pulverization. It is preferable before the main baking later.

(Current collector)
As the current collector used for the negative electrode, various materials conventionally used or proposed can be used. For example, although metal materials, such as copper, nickel, stainless steel, nickel plating steel, can be mentioned, copper is preferable from the viewpoint of ease of processing and cost.

(Binder (binder))
The binder that can be used for the negative electrode is not particularly limited as long as it does not react with the electrolytic solution. For example, polyvinylidene fluoride (PVdF), polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), polytetrafluoroethylene ( PTFE), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), ethylene-propylene-diene copolymer (EPDM), fluororubber (FR), acrylonitrile-butadiene rubber (NBR), sodium polyacrylate, propylene or Examples thereof include carboxymethyl cellulose (CMC).

(solvent)
When producing the negative electrode for a non-aqueous electrolyte secondary battery of the present invention, a solvent is added to the non-graphitizable carbonaceous material, a binder, and the like and kneaded. As the solvent, any solvent that can be used at the time of producing the negative electrode for a nonaqueous electrolyte secondary battery can be used without limitation. Specific examples include N-methylpyrrolidone (NMP). For example, in the case of polyvinylidene fluoride, a polar solvent such as N-methylpyrrolidone (NMP) is preferably used, but an aqueous emulsion such as SBR can also be used.

《Nonaqueous solvent electrolyte》
As the non-aqueous solvent electrolyte, various materials that are conventionally used or have been proposed can be used. Examples of the non-aqueous solvent include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, dimethoxyethane, diethoxyethane, γ-butyllactone, tetrahydrofuran, 2-methyltetrahydrofuran, sulfolane, and 1,3-dioxolane. These can be used alone or in combination of two or more. As the electrolyte, LiClO ₄ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiAsF ₆ , LiCl, LiBr, LiBOB, LiB (C ₆ H ₅ ) ₄ , or LiN (SO ₃ CF ₃ ) ₂ is used. It is done. The secondary battery is generally formed by immersing the positive electrode and the negative electrode in an electrolytic solution so that the positive electrode and the negative electrode are opposed to each other through a liquid-permeable separator made of a nonwoven fabric or other porous material as necessary.

<< Separator >>
As the separator, a non-woven fabric usually used for a secondary battery or a permeable separator made of another porous material can be used. Alternatively, a solid electrolyte made of a polymer gel impregnated with an electrolytic solution can be used instead of or together with the separator.

<Manufacture of non-aqueous electrolyte secondary batteries>
Below, an example of the manufacturing method of a nonaqueous electrolyte secondary battery is described.
The positive electrode uses the lithium-excess chalcogen compound, or the lithium chalcogen compound and the lithium-containing oxide as a positive electrode active material. A layer is formed on a conductive current collector by molding together with a suitable binder and a conductive aid for imparting conductivity to the electrode. Specifically, an appropriate amount of a binder (binder) and a suitable solvent are added to the positive electrode active material and kneaded to obtain an electrode mixture paste. It is applied to a conductive current collector made of a circular or rectangular metal plate, dried, and then pressure-molded. Alternatively, an electrode mixture paste may be applied to a conductive current collector and dried, and then press-molded, and punched into a circle or a rectangle. In this way, a layer having a thickness of 10 to 200 μm is formed to form a positive electrode.

For the negative electrode, the carbonaceous material is used as it is, or it is used together with a conductive auxiliary such as 1 to 10% by weight of acetylene black or conductive carbon black. An appropriate amount of a binder (binder) and an appropriate solvent are added and kneaded to obtain an electrode mixture paste. Then, for example, after applying and drying to a conductive current collector made of a circular or rectangular metal plate or the like, pressure molding is performed. A layer having a thickness of 10 to 200 μm is formed and used as an anode for electrode production.
By reversing the positive electrode and the negative electrode formed as described above through a liquid-permeable separator made of a nonwoven fabric or other porous material, if necessary, and immersing them in an electrolytic solution, To do.

[2] Vehicle The nonaqueous electrolyte secondary battery of the present invention is suitable as a battery (typically a nonaqueous electrolyte secondary battery for driving a vehicle) mounted on a vehicle such as an automobile.
The vehicle according to the present invention can be targeted without particular limitation, such as a vehicle normally known as an electric vehicle, a hybrid vehicle with a fuel cell or an internal combustion engine, and at least a power supply device including the battery, An electric drive mechanism that is driven by power supply from the power supply device and a control device that controls the electric drive mechanism are provided. Further, a power generation brake or a regenerative brake may be provided to convert the energy generated by braking into electricity and charge the nonaqueous electrolyte secondary battery.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but these do not limit the scope of the present invention.

<< Positive electrode active material production example 1 >>
In this production example, spinel type LiMn ₂ O ₄ was synthesized.
Lithium hydroxide (LiOH) and manganese oxide (Mn ₃ O ₄ ) were mixed so that the lithium: manganese atomic ratio was 1: 2. This mixture was heat-treated at 750 ° C. for 24 hours in an electric furnace. The obtained fired product was cooled and then pulverized again, followed by heat treatment at 850 ° C. for 6 hours to obtain a positive electrode active material 1.

<< Production Example of Positive Electrode Active Material 2 >>
In this production example, LiCoO ₂ was synthesized.
Lithium hydroxide (LiOH) and cobalt oxide (Co ₃ O ₄ ) were mixed so that the lithium: cobalt atomic ratio was 1: 1. This mixture was heat-treated at 750 ° C. for 24 hours in an electric furnace. The obtained fired product was cooled and then pulverized again, followed by heat treatment at 850 ° C. for 6 hours to obtain a positive electrode active material 2.

<< Catalyst Active Material Production Example 3 >>
In this production example, Li ₂ Mn ₂ O ₄ was synthesized.
Lithium hydroxide (LiOH) and manganese dioxide (MnO ₂ ) were mixed so that the lithium: manganese atomic ratio was 1: 1. This mixture was heat-treated at 680 ° C. for 48 hours in an electric furnace to obtain a positive electrode active material 3.

<< Catalyst Active Material Production Example 4 >>
In this production example, Li _1.2 Mn ₂ O ₄ was obtained.
A positive electrode active material 4 was obtained by mixing the positive electrode active material 1 obtained in the positive electrode active material production example 1 and the positive electrode active material 3 obtained in the positive electrode active material production example 3 at a ratio of 4: 1.

<< Catalyst Active Material Production Example 5 >>
In this production example, Li _1.2 Mn ₂ O ₄ was produced by an electrochemical synthesis method.
A positive electrode prepared using a lithium metal electrode and the positive electrode active material 1 was immersed in an electrolytic solution and discharged at about 0.78 mAh to obtain a positive electrode active material 5.

<< Catalyst Active Material Production Example 6 >>
In this production example, Li _1.2 CoO ₂ was produced by an electrochemical synthesis method.
A positive electrode prepared using a lithium metal electrode and the positive electrode active material 2 was immersed in an electrolytic solution and discharged at about 0.75 mAh to obtain a positive electrode active material 6.

<Negative electrode active material 1>
An easily graphitizable carbonaceous material having a sulfur content of 2480 μg / g was produced. Coal tar pitch was used as the carbon source.
Coal tar pitch was charged into a separable flask and air oxidation was performed at 180 ° C. for 2 hours while flowing 2 L / min of air. Subsequently, it was pulverized using a jet mill and classified to obtain a fine pulverization pitch. The finely pulverized pitch thus obtained was oxidized at a temperature of 280 ° C. for 1 hour while passing heated air to obtain a porous pitch that was infusible to heat. The obtained heat infusible porous pitch was pre-fired at 600 ° C. for 1 hour in a nitrogen gas atmosphere to obtain carbon precursor fine particles. Next, this carbon precursor was subjected to main firing at 1200 ° C. for 1 hour to obtain a carbonaceous material (negative electrode active material 1) having an average particle diameter of 15 μm. The characteristics of the obtained negative electrode active material 1 are shown in Table 1.

<Negative electrode active material 2>
An easily graphitizable carbonaceous material having a sulfur content of 97 μg / g was produced. As the carbon source, petroleum pitch that was desulfurized with a catalyst was used.
Charge a petroleum-based pitch of 68 kg with a softening point of 210 ° C., a quinoline insoluble content of 1%, and an H / C atomic ratio of 0.63 and naphthalene of 32 kg into a pressure-resistant vessel with an internal volume of 300 L with stirring blades, and heat-melt at 190 ° C. After mixing, the mixture was cooled to 80 to 90 ° C. and extruded to obtain a string-like molded body having a diameter of about 500 μm. Next, this string-like molded body was crushed so that the ratio of diameter to length was about 1.5, and the obtained crushed product was heated to 93 ° C. to 0.53% polyvinyl alcohol (saponification degree: 88% ) It was put into an aqueous solution, stirred and dispersed, and cooled to obtain a spherical pitch formed body. After most of the water was removed by filtration, naphthalene in the pitch molded body was extracted and removed with about 6 times the amount of n-hexane as the spherical pitch molded body.
The porous spherical pitch porous body thus obtained was subjected to an oxidation treatment by holding it at 180 ° C. for 1 hour while passing heated air to obtain a porous pitch that was infusible to heat. The obtained heat infusible porous pitch molded body was pre-fired at 600 ° C. for 1 hour in a nitrogen gas atmosphere, pulverized using a jet mill, and classified to obtain carbon precursor fine particles. Next, this carbon precursor was subjected to main firing at 1200 ° C. for 1 hour to obtain a carbonaceous material (negative electrode active material 2) having an average particle size of 10.2 μm. The characteristics of the obtained negative electrode active material 2 are shown in Table 1.

<Negative electrode active material 3>
A non-graphitizable carbonaceous material having a sulfur content of 121 μg / g was produced. Except that the temperature of the oxidation treatment at 180 ° C. was 210 ° C., the operation of the negative electrode active material 2 was repeated to obtain a carbonaceous material (negative electrode active material 3). The characteristics of the obtained negative electrode active material 3 are shown in Table 1.

<Negative electrode active material 4>
A non-graphitizable carbonaceous material having a sulfur content of 121 μg / g was produced. Except that the temperature of the oxidation treatment at 180 ° C. was 230 ° C., the operation of the negative electrode active material 2 was repeated to obtain a carbonaceous material (negative electrode active material 4). The characteristics of the obtained negative electrode active material 4 are shown in Table 1.

<Negative electrode active material 5>
A non-graphitizable carbonaceous material having a sulfur content of 121 μg / g was produced. Except that the temperature of the oxidation treatment at 180 ° C. was 260 ° C., the operation of the negative electrode active material 2 was repeated to obtain a carbonaceous material (negative electrode active material 5). The characteristics of the obtained negative electrode active material 5 are shown in Table 1.

<Negative electrode active material 6>
A non-graphitizable carbonaceous material having a sulfur content of 121 μg / g was produced. Except that the temperature of the oxidation treatment at 180 ° C. was 290 ° C., the operation of the negative electrode active material 2 was repeated to obtain a carbonaceous material (negative electrode active material 6). The characteristics of the obtained negative electrode active material 6 are shown in Table 1.

<Negative electrode active material 7>
Using a phenol resin as a carbon material, non-graphitizable carbon having a sulfur content of 300 μg / g was produced. To 108 g of orthocresol, 32 g of paraformaldehyde, 242 g of ethyl cellosolve and 10 g of sulfuric acid were added and reacted at 115 ° C. for 3 hours, and then 17 g of sodium bicarbonate and 30 g of water were added to neutralize the reaction solution. The obtained reaction solution was poured into 2 liters of water stirred at high speed to obtain a novolak resin. Next, 17.3 g of novolak resin and 2.0 g of hexamine were kneaded at 120 ° C. and heated at 250 ° C. for 2 hours in a nitrogen gas atmosphere to obtain a cured resin. After coarsely pulverizing the obtained cured resin, 0.5 wt% polyphenylene sulfide was mixed. The carbonaceous material was then calcined at 600 ° C. for 1 hour in a nitrogen atmosphere (normal pressure) and further heat treated at 1900 ° C. for 1 hour in an argon gas atmosphere (normal pressure). The obtained carbonaceous material was further pulverized and adjusted to an average particle size of 15 μm to obtain a negative electrode active material 7. The characteristics of the obtained negative electrode active material 7 are shown in Table 1.

<Negative electrode active material 8>
As the negative electrode active material 8, graphite derived from natural products (made in China) was used. Table 1 shows the characteristics of the negative electrode active material 8.

<Negative electrode active material 9>
A carbonaceous material was produced using petroleum pitch mixed with 3.3 wt% polyphenylene sulfide as a carbon source.
Except that the temperature of the oxidation treatment at 180 ° C. was 260 ° C., the operation of the negative electrode active material 2 was repeated to obtain a carbonaceous material (negative electrode active material 9). The characteristics of the obtained negative electrode active material 9 are shown in Table 1.

<Negative electrode active material 10>
Using a phenol resin as a carbon material, a non-graphitizable carbonaceous material having a sulfur content of 30 μg / g was produced. The negative electrode active material 10 was obtained by repeating the operation of the negative electrode active material 7 except that no polyphenylene sulfide was added. Table 1 shows the characteristics of the negative electrode active material 10.

<Negative electrode active material 11>
A phenol resin (Kanebo Co., Ltd.) was used as the negative electrode active material 11. Table 1 shows the characteristics of the negative electrode active material 11.

<Negative electrode active material 12>
As the negative electrode active material 12, petroleum-derived graphite (Shenzhen Shell Special Energy Materials Co., Ltd.) was used. Table 1 shows the characteristics of the negative electrode active material 12.

The physical properties of the carbonaceous materials described in the negative electrode active materials 1 to 12 (“average particle diameter by laser diffraction method”, “average layer plane spacing d ₀₀₂ by X-ray diffraction method”, “crystallite thickness L _c ” are given below. ”,“ Specific surface area ”,“ butanol true density ”,“ helium true density ”,“ Li-NMR ”and“ sulfur content ”) are described herein, including examples. The physical property values to be described are based on values obtained by the following method.

(Evaluation test items)
<Particle size distribution>
Three drops of a dispersing agent (cationic surfactant “SN Wet 366” (manufactured by San Nopco)) are added to about 0.1 g of the sample, and the sample is made to conform to the dispersing agent. Next, after adding 30 mL of pure water and dispersing for about 2 minutes with an ultrasonic cleaner, particles having a particle size in the range of 0.5 to 3000 μm are measured with a particle size distribution measuring instrument (“SALD-3000J” manufactured by Shimadzu Corporation). The diameter distribution was determined.
From the obtained particle size distribution, the average particle size Dv ₅₀ (μm) was defined as the particle size with a cumulative volume of 50%. The particle size at which the cumulative volume is 90% is Dv _90, and the particle size at which the cumulative volume is 10% is Dv ₁₀ . A value obtained by dividing Dv ₉₀ by Dv ₁₀ was defined as Dv ₉₀ / Dv ₁₀ , which was used as an index of the particle size distribution.

_<< Average Layer Surface Interval d ₀₀₂ and Crystallite Thickness L _{c (002) of} Carbonaceous Material >>
The carbonaceous material powder was filled in the sample holder and measured by a symmetrical reflection method using X'Pert PRO manufactured by PANalytical. The scanning range was 8 <2θ <50 °, and the applied current / applied voltage was 45 kV / 40 mA. An X-ray diffraction pattern was obtained using a CuKα ray (λ = 1.5418Å) monochromated by a Ni filter as a radiation source. . The diffraction pattern was corrected using the diffraction line on the (111) plane of the high-purity silicon powder for the standard substance without correcting the Lorentz changing factor, absorption factor, atomic scattering factor, and the like. The wavelength of the CuKα ray was 0.15418 nm, and d ₀₀₂ was calculated according to the Bragg formula. In addition, the crystallite thickness L _{c (002) in the} c-axis direction is calculated by the Scherrer equation from the value β obtained by subtracting the half width of the (111) diffraction line of the silicon powder from the half width obtained by the integration method of the 002 diffraction line. Was calculated. Here, the calculation was performed with the shape factor K = 0.9.

"Specific surface area"
The specific surface area was measured according to the method defined in JIS Z8830. The outline is described below.
Using an approximate expression derived from equation _{BET v m = 1 / (v} (1-x)) at the liquid nitrogen temperature, determine the _{v m} by 1-point method by nitrogen adsorption (relative pressure x = 0.3) The specific surface area of the sample was calculated by the following formula: Specific surface area = 4.35 × v _m (m ² / g)
(Here, v _m is the amount of adsorption (cm ³ / g) required to form a monomolecular layer on the sample surface, v is the amount of adsorption actually measured (cm ³ / g), and x is the relative pressure.)
Specifically, using a “Flow Sorb II2300” manufactured by MICROMERITICS, the amount of nitrogen adsorbed on the carbonaceous material at the liquid nitrogen temperature was measured as follows.
The sample tube is filled with the carbon material, and the sample tube is cooled to −196 ° C. while flowing a helium gas containing nitrogen gas at a concentration of 30 mol%, and nitrogen is adsorbed on the carbon material. The test tube is then returned to room temperature. At this time, the amount of nitrogen desorbed from the sample was measured with a thermal conductivity detector, and the amount of adsorbed gas v was obtained.

《Butanol true density》
In accordance with the method defined in JIS R7212, measurement was performed using butanol. The outline is described below.
The mass (m ₁ ) of a specific gravity bottle with a side tube having an internal volume of about 40 mL is accurately measured. Next, the sample is put flat on the bottom so as to have a thickness of about 10 mm, and then its mass (m ₂ ) is accurately measured. Gently add 1-butanol to this to a depth of about 20 mm from the bottom. Next, light vibration is applied to the specific gravity bottle, and it is confirmed that large bubbles are not generated. Then, the bottle is placed in a vacuum desiccator and gradually evacuated to 2.0 to 2.7 kPa. Keep at that pressure for 20 minutes or more, take out after bubble generation stops, fill with 1-butanol, plug and immerse in a constant temperature water bath (adjusted to 30 ± 0.03 ° C) for 15 minutes or more. Align the liquid level of 1-butanol with the marked line. Next, this is taken out, the outside is well wiped off and cooled to room temperature, and then the mass (m ₄ ) is accurately measured. Next, the same specific gravity bottle is filled with only 1-butanol, immersed in a constant temperature water bath in the same manner as described above, and after aligning the marked lines, the mass (m ₃ ) is measured. Moreover, distilled water excluding the gas that has been boiled and dissolved immediately before use is placed in a specific gravity bottle, immersed in a constant temperature water bath as before, and the mass (m ₅ ) is measured after aligning the marked lines. The true density (ρ _B ) is calculated by the following formula.
(Where d is the specific gravity of water at 30 ° C. (0.9946))

《Helium true density》
The measurement of the true density ρ _H using helium as a substitution medium was performed after a sample was vacuum-dried at 200 ° C. for 12 hours using a multi-volume pycnometer (Accumic 1330) manufactured by Micromeritics. The ambient temperature during measurement was constant at 25 ° C. The pressures in this measurement method are all gauge pressures and are the pressures obtained by subtracting the ambient pressure from the absolute pressure.
A multi-volume pycnometer manufactured by Micromerix, Inc. has a sample chamber and an expansion chamber, and the sample chamber has a pressure gauge for measuring the pressure in the chamber. The sample chamber and the expansion chamber are connected by a connecting pipe having a valve. A helium gas introduction pipe having a stop valve is connected to the sample chamber, and a helium gas distribution pipe having a stop valve is connected to the expansion chamber.
The measurement was performed as follows. The volume of the sample chamber (V _CELL ) and the volume of the expansion chamber (V _EXP ) were measured in advance using a standard sphere. A sample was put into the sample chamber, and helium gas was passed through the helium gas inlet tube, the connecting tube in the sample chamber, and the helium gas discharge tube in the expansion chamber for 2 hours to replace the inside of the apparatus with helium gas. Next, the valve between the sample chamber and the expansion chamber and the valve of the helium gas discharge pipe from the expansion chamber are closed (helium gas having the same pressure as the ambient pressure remains in the expansion chamber), and helium is introduced from the helium gas introduction tube of the sample chamber. After introducing the gas to 134 kPa, the stop valve of the helium gas introduction pipe was closed. The pressure (P ₁ ) in the sample chamber was measured 5 minutes after closing the stop valve. Next, the valve between the sample chamber and the expansion chamber was opened, and helium gas was transferred to the expansion chamber, and the pressure (P ₂ ) at that time was measured.
The volume of the sample (V _SAMP ) was calculated by the following formula.
V _SAMP = V _CELL −V _EXP / [(P ₁ / P ₂ ) −1]
Therefore, if the weight of the sample is W _SAMP , the true helium density is ρ _H = W _SAMP / V _SAMP
It becomes.

<< Li-NMR >>
Using the produced carbon electrode (positive electrode) and lithium negative electrode, as the electrolytic solution, a mixture of diethyl carbonate and ethylene carbonate in a volume ratio of 1: 1 was added to LiPF ₆ at a rate of 1 mol / L. Then, a non-aqueous solvent type lithium secondary battery was configured using a polypropylene microporous membrane as a separator. Energized with a constant current of current density of 0.2 mA / cm ² until the terminal voltage reaches to 0V, and continues charging until after the terminal voltage reaches to 0V, and the current value constant voltage charge was performed at a terminal voltage 0V reaches 4μA The carbonaceous material was doped with lithium. After the end of the doping, the carbon electrode was taken out under an argon atmosphere for 2 hours, and the carbon electrode (positive electrode) from which the electrolytic solution had been wiped was filled in a sample tube for NMR measurement. In NMR analysis, MAS- ⁷ Li-NMR was measured by JNMEX270 manufactured by JEOL Ltd. In the measurement, LiCl was measured as a reference substance, and this was set to 0 ppm.

《Sulfur content》
The sulfur content was measured according to the method defined in JIS K0103. The outline is described below.
10 mL of 30% hydrogen peroxide solution was diluted with 990 mL of distilled water to obtain an absorbing solution. 50 mL of absorption liquid was put into two absorption bottles with a volume of 250 mL, and the two were connected. The suction pump was activated and the sample combustion gas was passed through the absorption bottle. At this time, the flow rate was adjusted to 1 L / min.
The contents of the absorption bottle were transferred to a beaker, the absorption bottle was further washed with distilled water, and the washing liquid was also added to the beaker. This content solution was diluted so as to be within the quantification range to obtain a sample solution for analysis. The sulfur concentration in the sample solution for analysis was measured using an ion chromatography method. The ion chromatograph used was a suppressor type with an electric conductivity detector, and the column used was AS-4A SC manufactured by Dionex. As an eluent, a mixed aqueous solution of sodium hydrogen carbonate (1.7 mM) and sodium carbonate (1.8 mM) was prepared. The ion chromatogram was made measurable, and the eluent was passed through the separation column at a constant flow rate. A certain amount of the sample solution for analysis was introduced into the ion chromatogram, and the chromatogram was recorded. The sulfate ion concentration (a) (mg / mL) was determined from a calibration curve prepared in advance. The same operation was repeated for the absorbing solution to obtain a blank test value (b) (mg / mL) of sulfate ions. The volume fraction (Cv) (vol ppm) of sulfur oxide in the sample gas was determined from the following equation using the total amount v of the flask and the sample gas sampling amount Vs.
Cv = 0.233 × (ab) × v × 1000 / Vs
Furthermore, the mass concentration (Cw) (mg / m ³ ) when the sulfur oxide in the sample gas was expressed as sulfur dioxide was determined from the following equation.
Cw = Cv × 2.86

Example 1
In this example, a lithium ion secondary battery was produced by combining the positive electrode active material 4 (Li _1.2 Mn ₂ O ₄ ) and the carbonaceous material 1.
The positive electrode was produced as follows. NMP was added to 94 parts by weight of the positive electrode active material 4 obtained in Production Example 4 of positive electrode active material and 6 parts by weight of polyvinylidene fluoride (“KF # 1100” manufactured by Kureha Co., Ltd.) to form a paste, which was then placed on an aluminum foil. It was applied evenly. After drying, it was punched out into a disk shape having a diameter of 14 mm from an aluminum foil and pressed with a pressing pressure of 392 MPa (4.0 tf / cm ² ) to obtain a positive electrode.
The negative electrode was produced as follows.
NMP is added to 90 parts by weight of the carbonaceous material 1 obtained in Production Example 1 and 10 parts by weight of polyvinylidene fluoride (“KF # 9100” manufactured by Kureha Co., Ltd.) to form a paste, which is uniformly applied on the copper foil. did. After drying, it was punched out from a copper foil into a disk shape having a diameter of 15 mm, and pressed with a pressing pressure of 392 MPa (4.0 tf / cm ² ) to obtain a negative electrode. The amount of the carbon material in the electrode was adjusted to be about 10 mg.
The electrode pair thus produced was used, and as the electrolyte, LiPF ₆ was mixed at a rate of 1.5 mol / L in a mixed solvent in which ethylene carbonate, dimethyl carbonate, and methyl ethyl carbonate were mixed at a volume ratio of 1: 2: 2. And a 2032 size coin-type non-aqueous electrolyte lithium ion in an Ar glove box using a polyethylene gasket as a separator of a borosilicate glass fiber fine pore membrane having a diameter of 19 mm. A secondary battery 1 was assembled.

Example 2
In this example, a lithium ion secondary battery was produced by combining the positive electrode active material 4 (Li _1.2 Mn ₂ O ₄ ) and the carbonaceous material 2. The lithium ion secondary battery 2 was obtained by repeating the operation of Example 1 except that the carbonaceous material 2 was used instead of the carbonaceous material 1.

Example 3
In this example, a lithium ion secondary battery was produced by combining the positive electrode active material 4 (Li _1.2 Mn ₂ O ₄ ) and the carbonaceous material 3. The lithium ion secondary battery 3 was obtained by repeating the operation of Example 1 except that the carbonaceous material 3 was used instead of the carbonaceous material 1.

Example 4
In this example, a lithium ion secondary battery was produced by combining the positive electrode active material 4 (Li _1.2 Mn ₂ O ₄ ) and the carbonaceous material 4. A lithium ion secondary battery 4 was obtained by repeating the operation of Example 1 except that the carbonaceous material 4 was used instead of the carbonaceous material 1.

Example 5
In this example, a lithium ion secondary battery was produced by combining the positive electrode active material 4 (Li _1.2 Mn ₂ O ₄ ) and the carbonaceous material 5. The lithium ion secondary battery 5 was obtained by repeating the operation of Example 1 except that the carbonaceous material 5 was used instead of the carbonaceous material 1.

Example 6
In this example, a lithium ion secondary battery was produced by combining the positive electrode active material 4 (Li _1.2 Mn ₂ O ₄ ) and the carbonaceous material 6. A lithium ion secondary battery 6 was obtained by repeating the operation of Example 1 except that the carbonaceous material 6 was used instead of the carbonaceous material 1.

Example 7
In this comparative example, a lithium ion secondary battery was produced by combining the positive electrode active material 4 (Li _1.2 Mn ₂ O ₄ ) and the carbonaceous material 7. The lithium ion secondary battery 7 was obtained by repeating the operation of Example 1 except that the carbonaceous material 7 was used instead of the carbonaceous material 1.

Example 8
In this example, a lithium ion secondary battery was produced by combining the positive electrode active material 3 (Li ₂ Mn ₂ O ₄ ) and the carbonaceous material 5. The procedure of Example 1 was repeated except that the positive electrode active material 3 was used in place of the positive electrode active material 4 and the carbonaceous material 5 was used in place of the carbonaceous material 1 to obtain a lithium ion secondary. Battery 8 was obtained.

Example 9
In this example, a lithium ion secondary battery was produced by combining the positive electrode active material 5 (Li _1.2 Mn ₂ O ₄ ) and the carbonaceous material 5. The procedure of Example 1 was repeated except that the positive electrode active material 5 was used in place of the positive electrode active material 4 and the carbonaceous material 5 was used in place of the carbonaceous material 1 to obtain a lithium ion secondary. Battery 9 was obtained. In addition, what was manufactured by the said positive electrode active material manufacture example 5 was used as a positive electrode.

Example 10
In this example, a lithium ion secondary battery was produced by combining the positive electrode active material 6 (Li _1.2 CoO ₂ ) and the carbonaceous material 5. The procedure of Example 1 was repeated except that the positive electrode active material 6 was used in place of the positive electrode active material 4 and the carbonaceous material 5 was used in place of the carbonaceous material 1 to repeat the lithium ion secondary. Battery 10 was obtained. In addition, what was manufactured by the said positive electrode active material manufacture example 6 was used as a positive electrode.

<< Comparative Example 1 >>
In this comparative example, a lithium ion secondary battery was produced by combining the positive electrode active material 4 (Li _1.2 Mn ₂ O ₄ ) and the carbonaceous material 8. A comparative lithium ion secondary battery 1 was obtained by repeating the operation of Example 1 except that the carbonaceous material 8 was used instead of the carbonaceous material 1.

<< Comparative Example 2 >>
In this comparative example, a lithium ion secondary battery was produced by combining the positive electrode active material 4 (Li _1.2 Mn ₂ O ₄ ) and the carbonaceous material 9. A comparative lithium ion secondary battery 2 was obtained by repeating the operation of Example 1 except that the carbonaceous material 9 was used instead of the carbonaceous material 1.

<< Comparative Example 3 >>
In this comparative example, a lithium ion secondary battery was produced by combining the positive electrode active material 4 (Li _1.2 Mn ₂ O ₄ ) and the carbonaceous material 10. A comparative lithium ion secondary battery 3 was obtained by repeating the operation of Example 1 except that the carbonaceous material 10 was used instead of the carbonaceous material 1.

<< Comparative Example 4 >>
In this comparative example, a lithium ion secondary battery was produced by combining the positive electrode active material 4 (Li _1.2 Mn ₂ O ₄ ) and the carbonaceous material 11. A comparative lithium ion secondary battery 4 was obtained by repeating the operation of Example 1 except that the carbonaceous material 11 was used instead of the carbonaceous material 1.

<< Comparative Example 5 >>
In this comparative example, a lithium ion secondary battery was produced by combining the positive electrode active material 4 (Li _1.2 Mn ₂ O ₄ ) and the carbonaceous material 12. A comparative lithium ion secondary battery 5 was obtained by repeating the operation of Example 1 except that the carbonaceous material 12 was used instead of the carbonaceous material 1.

<< Comparative Example 6 >>
In this comparative example, a lithium ion secondary battery was fabricated by combining the positive electrode active material 1 (LiMn ₂ O ₄ ) and the carbonaceous material 5. The procedure of Example 1 was repeated except that the positive electrode active material 1 was used in place of the positive electrode active material 4 and the carbonaceous material 5 was used in place of the carbonaceous material 1. A secondary battery 6 was obtained.

<< Comparative Example 7 >>
In this comparative example, a lithium ion secondary battery was produced by combining the positive electrode active material 2 (LiCoO ₂ ) and the carbonaceous material 5. The procedure of Example 1 was repeated except that the positive electrode active material 2 was used in place of the positive electrode active material 4 and the carbonaceous material 5 was used in place of the carbonaceous material 1. A secondary battery 7 was obtained.

<Characteristics of lithium ion secondary battery>
(A) Measurement of battery capacity The above lithium secondary battery was subjected to a charge / discharge test using a charge / discharge test apparatus ("TOSCAT" manufactured by Toyo System). Lithium doping reaction on the carbon electrode was performed by the constant current constant voltage method, and dedoping reaction was performed by the constant current method. Here, in a battery using a lithium chalcogen compound as the positive electrode, the lithium doping reaction to the carbon electrode is “charging”, and the lithium dedoping reaction from the carbon electrode is “discharging”. The charging method employed here is a constant current constant voltage method. Specifically, the charging current value is 1 C (that is, one voltage) until the terminal voltage reaches 4.3 V (4.2 V for Example 10 and Comparative Example 7). Constant current charging is performed at a current value necessary for charging in time, and after the terminal voltage reaches 4.3 V (4.2 V for Example 10 and Comparative Example 7), the terminal voltage is 4.3 V (implemented). Regarding Example 10 and Comparative Example 7, constant voltage charging was performed at 4.2 V), and charging was continued until the current value reached 1 / 100C. At this time, the value obtained by dividing the supplied amount of electricity by the weight of the positive electrode material of the electrode was defined as the charge capacity (mAh / g) per unit weight of the positive electrode material. After completion of charging, the battery circuit was opened for 30 minutes and then discharged. Discharging was performed at a current value of 1 C, and the end voltage was 3 V (2.75 V for Example 10 and Comparative Example 7). A value obtained by dividing the amount of electricity discharged at this time by the weight of the positive electrode material of the electrode is defined as a discharge capacity (mAh / g) per unit weight of the positive electrode material. The irreversible capacity is calculated as charge capacity-discharge capacity.
The charge / discharge capacity and efficiency were determined by averaging the measured values of n = 3 for the test batteries prepared using the same sample.

(B) Cycle test The cycle test was done about the lithium ion secondary battery obtained by the said Example or the comparative example.
First, charge / discharge was repeated three times, and after aging, a cycle test was started. The constant current and constant voltage conditions adopted in the cycle test were that charging was performed at a charging current value of 1 C until the battery voltage reached 4.3 V (4.2 V for Example 10 and Comparative Example 7), and then the voltage was 4 .3 V (4.2 V for Example 10 and Comparative Example 7) (continue to keep constant voltage) and continuously change the current value until the current value reaches 1 / 100C. To do. After completion of charging, the battery circuit was opened for 30 minutes and then discharged. Discharging was performed at a current value of 1 C until the battery voltage reached 3 V (2.75 V for Example 10 and Comparative Example 7). This charge and discharge was repeated at 25 ° C. for 5 cycles, and the discharge capacity at the 5th cycle was divided by the discharge capacity at the 1st cycle to obtain cycle characteristics (cycle capacity retention) (%). Table 2 shows the characteristics of the obtained lithium secondary battery.

  As shown in Table 2, in an example in which a lithium-excess chalcogen compound or a combination of a lithium chalcogen compound and a Li-containing oxide was used for the positive electrode and a carbonaceous material containing 75 to 3500 μg / g of sulfur was used for the negative electrode, 98 Excellent cycle capacity maintenance ratio of 0.0 to 100% was exhibited. On the other hand, in the comparative example of the combination of the positive electrode and the negative electrode other than those described above, the cycle capacity retention rate was 94.9% to 97.1%. Furthermore, in Comparative Examples 6 and 7, in which a lithium chalcogen compound is used for the positive electrode and a carbonaceous material containing sulfur is used for the negative electrode, the efficiency is 78.3% and 85.0%, respectively, which is lower than the examples. It was.

Since the non-aqueous electrolyte secondary battery of the present invention has excellent cycle characteristics, it can be effectively used in hybrid vehicles (HEV) and electric vehicles (EV) that require long life and high input / output characteristics.
As mentioned above, although this invention was demonstrated along the specific aspect, the deformation | transformation and improvement obvious to those skilled in the art are included in the scope of the present invention.

Claims (3)

(I) (a) General formula (1):
_{A x + α M y B β} O z-γ (1)
(Wherein A is Li ⁺ , x is 1, 2 or 3, and α is 0 <α ≦ 1, M is selected from the group consisting of transition metals, alkali metals, alkaline earth metals, and aluminum. One or more elements, and y is 1 or 2, B is P or Si, β is 0 ≦ β ≦ 1, z is 2, 3, or 4, and γ is 0 ≦ γ ≦ 0. 05)
Or a positive electrode containing a positive electrode active material represented by (b) General formula (2):
_{A x M y B β O z} (2)
Wherein A is Li ⁺ , and x is 1, 2, or 3, M is one or more elements selected from the group consisting of transition metals, alkali metals, alkaline earth metals, and aluminum, and y is 1 or 2, B is P or Si, β is 0 ≦ β ≦ 1, z is 2, 3, or 4), and the charge / discharge potential with respect to the counter lithium is A positive electrode including a lithium-containing oxide that is present at 3.3 V or lower and an average discharge voltage exceeding 3.3 V is 3.4 to 5.0 V, and (II) determined by an X-ray diffraction method (002) Average layer spacing d002 is 0.345 to 0.400 nm, crystallite size Lc ₍₀₀₂₎ in the c-axis direction is 1.0 to 20.0 nm, specific surface area is 1 to 50 g / m ² , butanol true density ρ _BtOH There 1.45~2.20g / ^cm 3, Fine sulfur element content of 75~3500μg / g, a negative electrode containing a graphitizable or non-graphitizable carbonaceous material,
Non-aqueous electrolyte secondary battery.   The non-aqueous electrolyte secondary battery according to claim 1, wherein the graphitizable carbonaceous material or the hardly graphitizable carbonaceous material is a carbonaceous material produced using pitch as a carbon source.   A vehicle equipped with the nonaqueous electrolyte secondary battery according to claim 1.