JP2009224323A - Nonaqueous electrolyte secondary battery negative electrode active material, and manufacturing method of nonaqueous electrolyte secondary battery negative electrode active material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active material for a nonaqueous electrolyte secondary battery negative electrode excellent in charge and discharge characteristics, and to provide a manufacturing method thereof. <P>SOLUTION: The nonaqueous electrolyte secondary battery negative electrode active material includes a carbon material using at least one of either petroleum-based heavy oil and coal-based heavy oil as a raw material and a phosphorus compound, and is manufactured with a distance d<SB>002</SB>between crystal planes to be 0.340 nm or larger, a crystallite size Lc (110) in the direction of the C axis to be 5 nm or smaller, the intensity ratio (R1=I<SB>1,360</SB>/I<SB>1,580</SB>) of the diffraction peak near 1,360 cm<SP>-1</SP>to that of near 1,580 cm<SP>-1</SP>measured by the Raman spectroscopy to be increased in the range of 1% to 40% compared with the intensity ratio (R0=I<SB>1,360</SB>/I<SB>1,580</SB>) in a material that is the same intensity ratio without containing the phosphorus compound. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a non-aqueous electrolyte secondary battery negative electrode active material and a method for producing a non-aqueous electrolyte secondary battery negative electrode active material.

  A lithium ion secondary battery, which is a kind of non-aqueous electrolyte secondary battery, is a kind of secondary battery excellent in high energy density, storage characteristics, and reliability, and has attracted attention in recent years. However, when lithium metal is used as the negative electrode active material of the secondary battery, acicular crystal lithium called dentite is deposited on the negative electrode surface during charging, and the acicular crystal breaks through the separator to form a contact between the positive electrode and the negative electrode. There was an internal short circuit. For this reason, the negative electrode material comprised so that lithium may be inserted in a carbon material at the time of charge is used. It is known that the discharge capacity and charge / discharge efficiency of the carbon material used in this case are determined to some extent by the firing temperature.

  Among the carbon materials, the graphite material is an excellent material having a high energy density, which is obtained at a high temperature of at least about 2,000 ° C., usually about 2,600 to 3,000 ° C., but has high input / output characteristics. And has problems with cycle characteristics. For this reason, for example, for high input / output applications such as power storage and electric vehicles, the use of a low-crystalline carbon material that is fired at a temperature lower than that of the graphite material and has a low degree of graphitization is mainly studied.

  For example, it has been reported that a high-performance carbon material for a lithium battery for HEV can be produced by using an inexpensive pitch that is graphitizable carbon as a raw material (see Patent Document 1). According to this report, as a negative electrode active material for a lithium secondary battery, a carbonaceous powder having a predetermined crystal structure and pore structure obtained by firing a carbon precursor is used as a negative electrode active material for a lithium secondary battery. The lithium secondary battery is capable of rapid charge and discharge and is said to be excellent in high output characteristics.

  On the other hand, what is obtained by firing the above carbon precursor is generally obtained by precarbonizing the resin composition or its cured product, assuming that characteristics such as charge / discharge capacity and cycleability are not sufficient. After a phosphorus-containing compound is supported on the surface of the precursor to form a phosphorus-supported precursor, this is carbonized, and the phosphorus component is substantially removed by washing with water to obtain an active material for a negative electrode material for a secondary battery. A method has been proposed (see Patent Document 2).

  And it is supposed that the secondary battery excellent in charging / discharging characteristic can be obtained by using the active material obtained by this method for the negative electrode material for secondary batteries.

JP 2007-311322 A JP 2006-89349 A

  However, the charge / discharge characteristics of the secondary battery using the active material obtained by the method of Patent Document 2 as the negative electrode material for the secondary battery are not always excellent. Moreover, the raw material of the non-graphitizable carbon using a resin is expensive. Further, the process is complicated, such as using a crosslinking agent at the time of production, and it is difficult to reduce the cost. In addition, the low-temperature fired material (negative electrode material) is a material that is difficult to reduce the size and weight of the lithium secondary battery because of its low true density.

  This invention is made | formed in view of said subject, and it aims at providing the active material for nonaqueous electrolyte secondary battery negative electrodes which is excellent in charging / discharging characteristics, and its manufacturing method.

In order to achieve the above object, the present invention provides:
A carbon material and a phosphorus compound made from at least one of petroleum heavy oil and coal heavy oil;
The distance d ₀₀₂ between crystal planes by X-ray diffraction is 0.340 nm or more, the crystallite size Lc (110) in the C-axis direction is 5 nm or less,
The intensity ratio when the intensity ratio diffraction peaks 1,580Cm ^-1 vicinity of the diffraction peak of 1,360Cm ^-1 vicinity by Raman spectroscopy _{(R1 = I 1360 / I 1580} ) is, not including the phosphorus compound (R0 = I ₁₃₆₀ / I ₁₅₈₀ ), and relates to a non-aqueous electrolyte secondary battery negative electrode active material characterized by an increase in the range of 1% to 40%.

The present invention also provides:
A method for producing a non-aqueous electrolyte secondary battery negative electrode active material comprising:
Obtaining a carbon material from at least one raw material of petroleum heavy oil and coal heavy oil;
Including a step of attaching a phosphorus compound to the carbon material and firing to obtain a fired body,
The distance d ₀₀₂ between crystal planes by X-ray diffraction is 0.340 nm or more, the crystallite size Lc (110) in the C-axis direction is 5 nm or less,
The intensity ratio when the intensity ratio diffraction peaks 1,580Cm ^-1 vicinity of the diffraction peak of 1,360Cm ^-1 vicinity by Raman spectroscopy _{(R1 = I 1360 / I 1580} ) is, not including the phosphorus compound (R0 = I ₁₃₆₀ / I ₁₅₈₀ ), and relates to a method for producing a non-aqueous electrolyte secondary battery negative electrode active material that increases in the range of 1% to 40%.

The negative electrode active material of the nonaqueous electrolyte secondary battery of the present invention includes a carbon material and a phosphorus compound that are made from at least one of petroleum heavy oil and coal heavy oil, and has a crystal plane by X-ray diffraction. spacing _{d 002} is more than 0.340 nm, or less C-axis crystallite size Lc (110) is 5 nm, for the diffraction peak of 1,580Cm ^-1 vicinity of the diffraction peak of 1,360Cm ^-1 vicinity by Raman spectroscopy The intensity ratio (R1 = I ₁₃₆₀ / I ₁₅₈₀ ) increases in the range of 1% to 40% compared to the intensity ratio (R0 = I ₁₃₆₀ / I ₁₅₈₀ ) when no phosphorus compound is contained. .

  This means that when the non-aqueous electrolyte secondary battery negative electrode active material contains a phosphorus compound, the active material is composed of microcrystalline particles, and the overall crystallinity is reduced to some extent. In the past, it has been known that it is desirable to reduce the crystallinity to some extent in order to improve various characteristics of the negative electrode active material of the nonaqueous electrolyte secondary battery, but the above conditions satisfy the requirements. .

  As shown in the manufacturing method of the present invention described above, when the non-aqueous electrolyte secondary battery negative electrode active material is manufactured, firing is performed in a state where a phosphorus compound is attached to the carbon material constituting the skeleton. Due to that. That is, it is estimated that the phosphorus component functions as a catalyst, the carbocyclic condensation of the carbon material is suppressed, and the crystallinity gradually decreases from the center of the carbon material toward the outer surface. The

  Therefore, according to the non-aqueous electrolyte secondary battery negative electrode active material of the present invention, the charge / discharge characteristics can be improved, and the non-aqueous electrolyte secondary battery negative electrode active material is used as the negative electrode active material of a lithium secondary battery. As a result, the charge / discharge characteristics can be improved.

  As mentioned above, according to this invention, the active material for nonaqueous electrolyte secondary battery negative electrodes which is excellent in charging / discharging characteristics, and its manufacturing method can be provided.

It is a figure which shows the schematic structure about an example of the lithium secondary battery which concerns on this Embodiment.

  Hereinafter, details of the present invention and other features and advantages will be described based on embodiments.

  First, the water electrolyte secondary battery negative electrode active material according to the present embodiment will be described.

The non-aqueous electrolyte secondary battery negative electrode active material according to the present embodiment includes a carbon material and a phosphorus compound that are made from at least one of petroleum heavy oil and coal heavy oil, and is obtained by X-ray diffraction. spacing _{d 002} of the crystal plane than 0.340 nm, C-axis crystallite size Lc (110) is 5nm or less, and Raman spectroscopy diffraction 1,580Cm ^-1 vicinity of the diffraction peak of 1,360Cm ^-1 vicinity by The intensity ratio to the peak (R1 = I ₁₃₆₀ / I ₁₅₈₀ ) is increased in the range of 1% to 40% compared to the intensity ratio (R0 = I ₁₃₆₀ / I ₁₅₈₀ ) when the phosphorus compound is not included. It is characterized by.

  The raw material of the carbon powder used in the present embodiment is any one of petroleum heavy oil-derived petroleum pitch, crude oil cracking pitch or petroleum sludge pitch, and coal-based heavy oil-derived coal tar pitch. Or two or more are used in combination. At this time, those pitches subjected to hydrogenation treatment or the like may be used. The carbon material obtained from this raw material is preferably coal-based raw coke. Coal-based raw coke is inexpensive and relatively soft, so the work process in the manufacturing method described below can be simplified. In addition, the calcination coke obtained by calcining the said raw coke can also be used.

The distance d ₀₀₂ between crystal planes is a value obtained by X-ray diffraction based on the Gakushin method, and is 0.340 nm or more (first feature). If the distance d ₀₀₂ between the crystal planes is less than 0.340, the crystallinity is improved, and the charge / discharge capacity and the input / output characteristics may be deteriorated. There is no particular upper limit on the distance d ₀₀₂ between crystal planes, but it is preferably about 0.350 or less from the viewpoint of energy efficiency when used in a secondary battery.

  The crystallite size Lc (110) in the C-axis direction showing the crystal structure growth on the carbon laminate surface is a value obtained by X-ray diffraction based on the Gakushin method, and is 5 nm or less (second characteristic) ). If the crystallite size Lc (110) in the C-axis direction exceeds 5 nm, the crystallinity may be improved and the charge / discharge characteristics may be deteriorated. Although there is no particular lower limit on the crystallite size Lc (110) in the C-axis direction, it is preferably about 2 nm or more from the viewpoint of energy efficiency when used in a secondary battery.

The intensity ratio (R1 = I ₁₃₆₀ / I ₁₅₈₀ ) of the diffraction peak in the vicinity of 1,360 cm ^{−1, which is} obtained by Raman spectroscopy using an argon laser, to the diffraction peak in the vicinity of 1,580 cm ⁻¹ is Compared to the same strength ratio (R0 = I ₁₃₆₀ / I ₁₅₈₀ ) when not included, it is required to increase in the range of 1% to 40%, preferably in the range of 2% to 35%. 3 features).

  The first to third features described above are characterized in that when the non-aqueous electrolyte secondary battery negative electrode active material is manufactured, a phosphorous compound is attached to the carbon material, so that the whole of the negative electrode active material can be obtained. It means that the crystallinity is lowered to some extent. In the past, it has been known that it is desirable to reduce the crystallinity to some extent in order to improve various characteristics of the negative electrode active material of the nonaqueous electrolyte secondary battery, but the above conditions satisfy the requirements. .

  This is because, in the production method of the present invention described below, when the non-aqueous electrolyte secondary battery negative electrode active material is produced, firing is performed in a state where a phosphorus compound is attached to the carbon material constituting the skeleton. caused by. That is, it is estimated that the phosphorus component functions as a catalyst, the carbocyclic condensation of the carbon material is suppressed, and the crystallinity gradually decreases from the center of the carbon material toward the outer surface. The

  In addition, the phosphorus compound contained in the said nonaqueous electrolyte secondary battery negative electrode active material is 0.1-6.0 weight part in conversion of phosphorus with respect to 100 weight part of a carbon material, Preferably it is 0.1-4.0 weight. Parts, particularly 0.1 to 3.5 parts by weight. If the amount of addition is less than 0.1 parts by weight, the effect of attaching the phosphorus compound may not be sufficiently obtained. On the other hand, if the amount of addition exceeds 6.0 parts by weight, carbonization of raw coke may be excessively promoted. Because there is.

  The content of the phosphorus compound in the present embodiment is a value calculated from the amount of phosphoric acid used, assuming that all phosphorus components in the phosphoric acid aqueous solution are attached to the carbon surface.

  The phosphorus compound used in the present embodiment is not particularly limited. However, phosphoric acids are preferable from the viewpoint of easily preparing an aqueous solution and having high safety. Phosphoric acid (orthophosphoric acid) is more preferably used as the phosphoric acid, but is not limited thereto, and can be appropriately selected from linear polyphosphoric acid, cyclic polyphosphoric acid, various phosphoric ester compounds, and the like. Any one of these phosphoric acids may be used alone, or two or more thereof may be used in combination.

  Next, the manufacturing method of the non-aqueous electrolyte secondary battery negative electrode active material according to the present embodiment will be described.

In the non-aqueous electrolyte secondary battery negative electrode active material according to the present embodiment, first, at least one raw material of petroleum heavy oil or coal heavy oil is prepared, and a predetermined carbon material is prepared therefrom. To manufacture. The carbon material is not particularly limited in particle diameter, but the average particle diameter calculated as the median diameter is more preferably 5 to 15 μm, and in this case, the BET specific surface area is 5 m ² / g or less. preferable.

If the average particle diameter is less than 5 μm, the specific surface area may be excessively increased. On the other hand, if the average particle diameter is more than 15 μm, the charge / discharge characteristics may be deteriorated. If the BET specific surface area exceeds 5 m ² / g, the energy efficiency when used in a secondary battery may be reduced. The BET specific surface area is desirably about 2 m ² / g or more from the viewpoint of forming fine pores.

  When the carbon material is coal-based raw coke, petroleum coke heavy oil or coal heavy oil is used as a raw material, for example, a suitable coking facility such as a delayed coker, It can be obtained by advancing the thermal decomposition / polycondensation reaction at a temperature of about 24 hours. In addition, since raw coke is comparatively soft, the following grinding | pulverization can be easily performed by making the said carbon material into the said raw coke.

  The obtained raw coke is pulverized to a predetermined size so as to enter a mold used in the subsequent firing. An industrially used pulverizer can be used for the pulverization. Specific examples include an atomizer, a Raymond mill, an impeller mill, a ball mill, a cutter mill, a jet mill, and a hybridizer, but are not particularly limited thereto.

  Instead of the above-mentioned raw coke, calcined coke obtained by calcining this raw coke at about 1400 ° C. can also be used as the carbon material.

  For firing raw coke, equipment such as lead hammer furnace, shuttle furnace, tunnel furnace, rotary kiln, roller hearth kiln or microwave capable of mass heat treatment can be used, especially if the atmosphere can be controlled. It is not limited. Further, these firing facilities may be either a continuous type or a batch type.

  Next, the firing step is performed in a state where a phosphorus compound is attached to the carbon material described above. For example, the temperature is raised to 900 ° C. or higher, more preferably 1,000 ° C. or higher, and then the temperature is lowered to near room temperature after cooling. In addition, since the graphitization of carbon powder will advance when a calcination temperature exceeds 2,000 degreeC, it is preferable to avoid. Thereby, the crystal structure of the carbon powder obtained is controlled moderately. The holding time at the maximum temperature is not particularly limited, but is preferably 30 minutes or more. The firing atmosphere is an inert gas atmosphere such as argon or nitrogen.

  Moreover, as above-mentioned, it is preferable that the said phosphorus compound is 0.1-6.0 weight part in conversion of phosphorus with respect to 100 weight part of a carbon material. If the amount of addition is less than 0.1 parts by weight, the effect of attaching the phosphorus compound may not be sufficiently obtained. On the other hand, if the amount of addition exceeds 6.0 parts by weight, carbonization of raw coke may be excessively promoted. Because there is.

  In addition, the content of the phosphorus compound in the present embodiment is a value calculated from the amount of phosphoric acid used, assuming that all phosphorus components in the phosphoric acid aqueous solution are attached to the carbon surface.

  Similarly to the above, as the above-mentioned phosphorus compound, phosphoric acids are preferable from the viewpoint of easily preparing an aqueous solution and having high safety. Phosphoric acid (orthophosphoric acid) is more preferably used as the phosphoric acid, but is not limited thereto, and can be appropriately selected from linear polyphosphoric acid, cyclic polyphosphoric acid, various phosphoric ester compounds, and the like. Any one of these phosphoric acids may be used alone, or two or more thereof may be used in combination.

  The non-aqueous electrolyte secondary battery negative electrode active material obtained by the method for producing a non-aqueous electrolyte secondary battery negative electrode active material according to the present embodiment has excellent charge / discharge characteristics when used in a non-aqueous electrolyte secondary battery. A water electrolyte secondary battery can be obtained.

  In addition, the manufacturing cost is low compared to the case where non-graphitizable carbon using a resin is used for the negative electrode material. Further, graphitizable carbon can be easily densified by increasing the heat treatment temperature. Therefore, it is easy to reduce the size and weight of the lithium secondary battery.

  Next, the nonaqueous electrolyte secondary battery according to the present embodiment will be described. This secondary battery is manufactured using the non-aqueous electrolyte secondary battery negative electrode active material obtained by the method for manufacturing a non-aqueous electrolyte secondary battery negative electrode active material according to the present embodiment. At this time, preferably, a lithium ion secondary battery is manufactured.

  The non-aqueous electrolyte secondary battery according to the present embodiment is one in which the negative electrode material is filled with the electrolytic solution in the interior of the negative electrode material facing the positive electrode material with a separator interposed therebetween.

  The method of forming a negative electrode using the non-aqueous electrolyte secondary battery negative electrode active material should sufficiently draw out the performance of the lithium secondary battery used, have high formability, and be chemically and electrochemically stable. There is no particular limitation. For example, the non-aqueous electrolyte secondary battery negative electrode active material according to the present embodiment is a fluorine resin powder such as polyvinylidene fluoride (PVDF) or a water-soluble binder such as styrene butadiene rubber (SBR) or carboxymethyl cellulose (CMC). A carbonaceous binder is used to form a slurry by mixing with N-methylpyrrolidone (NMP), dimethylformamide, or a solvent such as water, alcohol, etc., and coating and drying on a current collector. Can do.

The positive electrode active material constituting the positive electrode material is not particularly limited as long as it can be normally used for a lithium secondary battery. As the positive electrode active material, for example, a lithium-containing transition metal oxide LiM (1) _X O ₂ (wherein x is a numerical value in the range of 0 ≦ x ≦ 1, where M (1) represents a transition metal, Co, Ni, Mn, Ti, Cr, V, Fe, Zn, Al, Sn, In), or LiM (1) _Y M (2) _2-Y O ₄ (where y is 0 ≦ y ≦ 1, where M (1) and M (2) represent transition metals, Co, Ni, Mn, Ti, Cr, V, Fe, Zn, Al, Sn, In), transition metal chalcogenides (Ti, S ₂ , NbSe, etc.), vanadium oxides (V ₂ O _5, V ₆ O ₁₃ , V ₂ O _4, V ₃ O _6, etc.) And lithium compound, general formula M _x Mo ₆ Ch _6-y (wherein x is a value in the range of 0 ≦ x ≦ 4, y is in a range of 0 ≦ y ≦ 1, where M includes transition metals, etc.) A metal, Ch represents a chalcogen metal), a activated carbon fiber, activated carbon fiber, or the like.

  The non-aqueous electrolyte is not particularly limited as long as it can be normally used for a lithium secondary battery.

As the electrolyte, any known ones can be used, for example _{LiClO 4, LiBF 4, LiPF 6} , LiAsF 6, LiB (C 6 H 5), LiCl, LiBr, Li 3 SO 3, Li (CF ₃ SO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) ₃ C, Li) CF ₃ CH ₂ OSO ₂ ) ₂ N, Li (CF ₃ CF ₂ CH ₂ OSO ₂ ) ₂ N, Li (HCF ₂ CF ₂ CH ₂ OSO ₂ ) ₂ N, Li ((CF ₃ ) ₂ CHOSO ₂ ) ₂ N, LiB [C ₆ H ₃ (CF ₃ ) ₂ ] _4, or a mixture of two or more thereof can be given.

  On the other hand, as an organic solvent in a non-aqueous electrolyte, for example, an organic solvent-based electrolyte, for example, propylene carbonate, ethylene carbonate, butylene carbonate, chloroethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 1,1-dimethoxyethane, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, anisole, diethyl ether, sulfolane, methyl Sulfolane, acetonitrile, chloronitrile, propionitrile, trimethyl borate, tetramethyl silicate, nitromethane, dimethylformamide, N-methylpyrrolidone, ethyl acetate, A single solvent such as limethyl orthoformate, nitrobenzene, benzoyl chloride, benzoyl bromide, tetrahydrothiophene, dimethyl sulfoxide, 3-methyl-2-oxazolidone, ethylene glycol, sulfite, dimethyl sulfite, etc. Can be used.

An example of the lithium secondary battery for high input characteristics according to this embodiment is shown in FIG.
The simple cell shown in FIG. 1 has the same structure as a commercially available CR2032-type coin battery. Reference numeral 10 denotes a positive electrode can, reference numeral 12 denotes an insulating packing, reference numeral 14 denotes a positive electrode current collector, and reference numeral 16 denotes a positive electrode current collector. Reference numeral 18 indicates a separator, reference numeral 20 indicates a negative electrode, reference numeral 22 indicates a negative electrode current collector, and reference numeral 24 indicates a negative electrode can.

  In the lithium secondary battery shown in FIG. 1, charging / discharging is performed by passing a current between the positive electrode 16 and the negative electrode 20 or discharging a current from between the positive electrode 16 and the negative electrode 20 as in the conventional case.

  Examples of the present invention and comparative examples will be described below. However, the contents of the present invention are not limited by these examples and comparative examples.

A carbon material for negative electrode material (active material for nonaqueous electrolyte secondary battery negative electrode) was prepared under the following conditions.

Example 1
Using a refined pitch from which heavy quinoline insolubles have been removed from heavy coal-based oil, bulk coke produced by heat treatment at a temperature of 500 ° C. for 24 hours by a delayed coking method (raw coke) is pulverized and conditioned with a jet mill. The carbon material powder (fine pulverized raw coke) having an average particle diameter of 9.9 μm was obtained.

  Subsequently, 15 parts by weight of the obtained carbon material powder was charged with 3.11 parts by weight (phosphorus conversion: 0.82 parts by weight) of phosphoric acid (85 mass% aqueous solution) and 5 parts by weight of a surfactant with respect to 150 parts of water. It was immersed in the dissolved phosphoric acid aqueous solution. Thereafter, only water was removed by heating and stirring at 150 ° C. using a hot stirrer to obtain a phosphorus-supported precursor (finely pulverized raw coke to which a phosphorus compound was added).

  Further, the obtained phosphorus-carrying precursor is heated from room temperature at a rate of 600 ° C./hour, and after reaching 1000 ° C., it is further maintained for 2 hours for carbonization treatment (firing) to be used for the negative electrode material A carbon material (active material for nonaqueous electrolyte secondary battery negative electrode) was obtained.

(Comparative Example 1)
A carbon material for a negative electrode material was obtained in the same manner as in Example 1 except that phosphorus was not supported.

(Example 2)
Phosphoric acid (85 mass% aqueous solution) 1.77 parts by weight (phosphorus conversion: 0.47 parts by weight) with respect to 150 parts by weight of water during the preparation of the phosphorus-supporting precursor, and the carbonization temperature during the preparation of the carbon material for the negative electrode material A carbon material for a negative electrode material was obtained in the same manner as in Example 1 except that the temperature was 1,100 ° C.

(Comparative Example 2)
A carbon material for a negative electrode material was obtained in the same manner as in Example 2 except that phosphorus was not supported.

(Example 3)
Phosphoric acid (85 mass% aqueous solution) 0.93 parts by weight (phosphorus conversion: 0.25 parts by weight) is used for 150 parts by weight of water when preparing the phosphorus-supporting precursor, and the carbonization temperature is set when preparing the carbon material for the negative electrode material. A carbon material for a negative electrode material was obtained in the same manner as in Example 1 except that the temperature was 1,300 ° C.

(Comparative Example 3)
A carbon material for a negative electrode material was obtained in the same manner as in Example 3 except that phosphorus was not supported.

Example 4
Phosphoric acid ester (14% by mass active phosphorus solid resin: trade name HCA manufactured by Sanko Co., Ltd., chemical name: 9,10-dihydro-9-oxa-10-osfa with respect to 100 parts by weight of raw coke at the time of preparing phosphorus-carrying precursor Phenanthrene-10-oxide) 22.3 parts by weight (phosphorus equivalent: 3.1 parts by weight) and the carbonization temperature at the time of preparing the carbon material for the negative electrode material was changed to 1,100 ° C. Thus, a carbon material for a negative electrode material was obtained.

(Comparative Example 4)
A carbon material for a negative electrode material was obtained in the same manner as in Example 4 except that phosphorus was not supported.

(Example 5)
Phosphoric acid ester (POD: 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) 22.3 parts by weight (phosphorus conversion: 3) with respect to 100 parts by weight of raw coke at the time of preparing the phosphorus-carrying precursor 0.1 parts by weight) and a carbon material for a negative electrode material was obtained in the same manner as in Example 1 except that the carbonization temperature was set to 800 ° C. during the preparation of the carbon material for a negative electrode material.

(Comparative Example 5)
A carbon material for a negative electrode material was obtained in the same manner as in Example 5 except that phosphorus was not supported.

(Example 6)
Phosphate ester (POD) 22.3 parts by weight (phosphorus equivalent: 3.1 parts by weight) is used for 100 parts by weight of raw coke at the time of preparing the phosphorus-carrying precursor, and the carbonization temperature is 900 at the time of preparing the carbon material for the negative electrode material. A carbon material for a negative electrode material was obtained in the same manner as in Example 1 except that the temperature was changed to ° C.

(Comparative Example 6)
A carbon material for a negative electrode material was obtained in the same manner as in Example 6 except that phosphorus was not supported.

(Example 7)
Phosphoric acid ester (POD) 22.3 parts by weight (phosphorus conversion: 3.1 parts by weight) is used with respect to 100 parts by weight of raw coke at the time of preparing the phosphorus-carrying precursor, and the carbonization temperature is set to 1 at the time of preparing the carbon material for the negative electrode material. A carbon material for a negative electrode material was obtained in the same manner as in Example 1 except that the temperature was 1,000 ° C.

(Comparative Example 7)
A carbon material for a negative electrode material was obtained in the same manner as in Example 7 except that phosphorus was not supported.

(Example 8)
Phosphoric acid ester (POD) 22.3 parts by weight (phosphorus conversion: 3.1 parts by weight) is used with respect to 100 parts by weight of raw coke at the time of preparing the phosphorus-carrying precursor, and the carbonization temperature is set to 1 at the time of preparing the carbon material for the negative electrode material. A carbon material for a negative electrode material was obtained in the same manner as in Example 1 except that the temperature was 200 ° C.

(Comparative Example 8)
A carbon material for a negative electrode material was obtained in the same manner as in Example 8 except that phosphorus was not supported.

  Using the carbon materials for negative electrode materials prepared in Examples 1 to 8 and Comparative Examples 1 to 8, secondary batteries were produced in the following manner and performance was evaluated.

  5% by mass of polyvinylidene fluoride (PVDF) as a binder is added to the carbon material for the negative electrode material, and N-methylpyrrolidone (NMP) is kneaded as a solvent to prepare a slurry, which is uniformly formed on a copper foil having a thickness of 18 μm. In this way, a negative electrode foil was obtained. This negative electrode foil was dried and pressed to a predetermined electrode density to prepare an electrode sheet, and a negative electrode was prepared by cutting out from this sheet into a circle having a diameter of 15 mmΦ. In order to evaluate the electrode characteristics of the single electrode of the negative electrode, metallic lithium cut into about 15.5 mmΦ was used for the counter electrode.

A coin cell was prepared by using a solution of LiPF ₆ dissolved in a mixed solvent of ethylene carbonate and diethyl carbonate (volume ratio 1: 1 mixture) as an electrolyte solution at a concentration of 1 mol / l, and using a porous membrane of propylene as a separator. Charge / discharge test under constant current and constant voltage charge of 0.4 mA / cm ^{2 at} a constant voltage of 25 ° C, with a terminal voltage lower limit voltage of 0V and a discharge upper limit voltage of 1.5V. I did it.

These evaluation results are shown in Table 1 together with the characteristics of the carbon material for a negative electrode material.

  As is apparent from Table 1, in the secondary battery according to the example manufactured using the carbon material for negative electrode material containing the phosphorus compound according to the present invention, particularly when the carbon material for negative electrode material contains the phosphorus compound, Raman is used. It can be seen that the intensity by the spectroscopic method is reduced and the crystallinity is lowered.

  Moreover, due to the low crystallinity of such a carbon material for negative electrode materials, a carbon material for negative electrode materials was manufactured under the same conditions except that a phosphorus compound was included or not included, and a secondary battery was manufactured. When Example 1 and Comparative Example 1 are compared, in an example including a phosphorus compound, the charge capacity (mAh / g), the discharge capacity (mAh / g), and the charge / discharge efficiency (%) may be excellent. I understand.

  While the present invention has been described in detail based on the above specific examples, the present invention is not limited to the above specific examples, and various modifications and changes can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Positive electrode can 12 Insulation packing 14 Positive electrode collector 16 Positive electrode 18 Separator 20 Negative electrode 22 Negative electrode collector 24 Negative electrode can

Claims (9)

A carbon material and a phosphorus compound made from at least one of petroleum heavy oil and coal heavy oil;
The distance d ₀₀₂ between crystal planes is 0.340 nm or more, the crystallite size Lc (110) in the C-axis direction is 5 nm or less,
The intensity ratio when the intensity ratio diffraction peaks 1,580Cm ^-1 vicinity of the diffraction peak of 1,360Cm ^-1 vicinity by Raman spectroscopy _{(R1 = I 1360 / I 1580} ) is, not including the phosphorus compound (R0 = I ₁₃₆₀ / I ₁₅₈₀ ), a non-aqueous electrolyte secondary battery negative electrode active material characterized by increasing in the range of 1% to 40%. The intensity ratio (R1 = I ₁₃₆₀ / I ₁₅₈₀ ) is increased in a range of 2% to 35% compared to the intensity ratio (R 0 = I ₁₃₆₀ / I ₁₅₈₀ ), Item 2. The negative electrode active material for nonaqueous electrolyte secondary batteries according to Item 1.   The non-water according to claim 1 or 2, wherein the phosphorus compound is contained in a proportion of 0.1 to 6.0 parts by weight in terms of phosphorus with respect to 100 parts by weight of the carbon material. Electrode secondary battery negative electrode active material.   The non-aqueous electrolyte secondary battery negative electrode active material according to claim 1, wherein the raw material is coal-based raw coke. A method for producing a non-aqueous electrolyte secondary battery negative electrode active material comprising:
Obtaining a carbon material from at least one raw material of petroleum heavy oil and coal heavy oil;
Including a step of attaching a phosphorus compound to the carbon material and firing to obtain a fired body,
The distance d ₀₀₂ between crystal planes is 0.340 nm or more, the crystallite size Lc (110) in the C-axis direction is 5 nm or less,
The intensity ratio when the intensity ratio diffraction peaks 1,580Cm ^-1 vicinity of the diffraction peak of 1,360Cm ^-1 vicinity by Raman spectroscopy _{(R1 = I 1360 / I 1580} ) is, not including the phosphorus compound (R0 = I ₁₃₆₀ / I ₁₅₈₀ ), a method for producing a non-aqueous electrolyte secondary battery negative electrode active material that increases in the range of 1% to 40%. The intensity ratio (R1 = I ₁₃₆₀ / I ₁₅₈₀ ) is increased in a range of 2% to 35% compared to the intensity ratio (R 0 = I ₁₃₆₀ / I ₁₅₈₀ ), Item 6. A method for producing a non-aqueous electrolyte secondary battery negative electrode active material according to Item 5.   7. The non-aqueous composition according to claim 5, wherein the phosphorus compound is attached at a ratio of 0.1 to 6.0 parts by weight in terms of phosphorus with respect to 100 parts by weight of the carbon material. A method for producing an electrolyte secondary battery negative electrode active material.   The said baking is implemented at the temperature of 900 to 2000 degreeC, The manufacturing method of the nonaqueous electrolyte secondary battery negative electrode active material as described in any one of Claims 5-7 characterized by the above-mentioned.   The method for producing a non-aqueous electrolyte secondary battery negative electrode active material according to any one of claims 5 to 8, wherein the raw material is coal-based raw coke.

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