JP2010010082A - Negative electrode for nonaqueous secondary battery, negative electrode material for nonaqueous secondary battery, and nonaqueous secondary battery - Google Patents

Abstract

Disclosed is a negative electrode for a non-aqueous secondary battery in which lithium metal deposition on an electrode surface is suppressed and a non-aqueous secondary battery excellent in safety can be obtained.
A negative electrode for a non-aqueous secondary battery, characterized in that an electrode active material density is 1.70 g / cm ³ or more and satisfies the following (1) and / or (2): And a non-aqueous secondary battery comprising the negative electrode.
(1) When the Raman spectrum of the electrode surface active material and the current collector contact surface active material is measured by a predetermined method, and the half-widths of the maximum peaks near 1580 cm ⁻¹ are Hs and Hc, respectively, The indicated index Th is 0.3 or less.
Th = Hc- Hs- 3.75 × D + 6
(2) the electrode surface active Raman spectrum of the maximum peak intensity Ib_s maximum peak around intensity Ia_s and 1360 cm ^-1 in the vicinity of 1580 cm ^-1 in the measured intensity ratio Ib_s / Ia_s substances when the Rs, with Rs 0.13 or more is there.
[Selection figure] None

Description

  The present invention relates to a negative electrode used for a non-aqueous secondary battery, a negative electrode material used for the negative electrode, and a non-aqueous secondary battery including the negative electrode.

  In recent years, demand for high-capacity secondary batteries has increased with the downsizing of electronic devices. In particular, non-aqueous secondary batteries with higher energy density have attracted attention as compared to nickel-cadmium batteries and nickel-hydrogen batteries. As negative electrode active materials for non-aqueous secondary batteries, metals and graphite have been studied so far. However, when the metal electrode is repeatedly charged and discharged, lithium is deposited in a dendrite shape on the electrode, and eventually both electrodes are short-circuited. Therefore, in the charge / discharge process, a carbon material, particularly graphite, which is less liable to deposit lithium metal than the metal electrode has attracted attention.

However, since graphite is a flat crystal, it tends to be oriented in parallel with the current collector in the electrode, so that the rapid charge / discharge characteristics are likely to deteriorate; the expansion of the electrode in the charge / discharge cycle is significant, and the cycle characteristics are There is a problem that it tends to decrease.
In Patent Document 1, by using graphite granulated particles in which a plurality of graphite particles are bonded so that their orientation planes are not parallel to each other, expansion in the thickness direction of the electrode is suppressed, and rapid charge / discharge is performed. It has been proposed to improve characteristics and cycle characteristics.

  However, the graphite granulated particles described in this patent document have a problem that performance as a negative electrode material of a lithium ion secondary battery, in particular, reduction in irreversible capacity and improvement in cycle characteristics are not always sufficient. Although the cause of this problem is not clear, the graphite granulated particles described in the above-mentioned patent document have few amorphous parts, the binding force between the graphite particles is too weak, and during the pressing in the electrode plate making process This is thought to be because the surface of the electrode plate is in a state without gaps. If the graphitized granulated particles are excessively graphitized, the characteristics at the time of producing a lithium ion secondary battery, in particular, the immersion property tends to be insufficient.

In addition, there is no gap on the surface of the electrode plate, and the lithium acceptability is insufficient, so that Li metal tends to be deposited on the electrode surface due to charge / discharge.
Patent Document 2 proposes graphite particles in which the surface roughness of the electrode when prepared by a predetermined method satisfies a specific value. Even if such particles are used, lithium on the electrode plate surface is proposed. The metal precipitation suppression effect was not sufficient.
Japanese Patent Laid-Open No. 10-188959 WO2006 / 25377 Publication

  It is an object of the present invention to provide a negative electrode with improved performance, a negative electrode material composed of graphite particles for realizing them, and a non-aqueous secondary battery including the negative electrode.

As a result of intensive studies to solve the above problems, the present inventors have found that when a specific electrode plate is used, lithium metal deposition on the electrode surface is suppressed, and a non-aqueous secondary battery excellent in safety can be provided. The headline and the present invention were completed.
That is, the gist of the present invention is as follows.
1. A negative electrode for a non-aqueous secondary battery having an electrode active material density of 1.70 g / cm ³ or more and satisfying the following (1) and / or (2).
(1) When the Raman spectrum of the electrode surface active material and the current collector contact surface active material is measured by a predetermined method, and the half-widths of the maximum peaks near 1580 cm ⁻¹ are Hs and Hc, respectively, The indicated index Th is 0.3 or less.
Th = Hc- Hs- 3.75 × D + 6
(2) the electrode surface active Raman spectrum of the maximum peak intensity Ib_s maximum peak around intensity Ia_s and 1360 cm ^-1 in the vicinity of 1580 cm ^-1 in the measured intensity ratio Ib_s / Ia_s substances when the Rs, with Rs 0.13 or more is there.
2. A negative electrode for a non-aqueous secondary battery having an electrode active material density of 1.70 g / cm ³ or more and satisfying the following (2) and / or (3).
(2) the electrode surface active Raman spectrum of the maximum peak intensity Ib_s maximum peak around intensity Ia_s and 1360 cm ^-1 in the vicinity of 1580 cm ^-1 in the measured intensity ratio Ib_s / Ia_s substances when the Rs, with Rs 0.13 or more is there.
(3) is in contact with the intensity of the maximum peak in the vicinity of 1580 cm ^-1 in the Raman spectrum measurement of the electrode surface active material Ia_s, the intensity ratio Ib_s / Ia_s of the intensity of the largest peak in the vicinity of 1360cm ^-1 Ib_s Rs, the collector 1580 cm ^{−1 in the} measurement of the Raman spectrum of the active material surface
When the intensity ratio Ib_c / Ia_c between the intensity Ia_c of the maximum peak near and the intensity Ib_c of the maximum peak near 1360 cm ⁻¹ is Rc, the index Tr expressed by the following formula is less than 0.
Tr = Rs- Rc- 0.04 × D + 0.06
3. 3. The negative electrode for a non-aqueous secondary battery according to 1 or 2, further satisfying the following.
(4) When the irreversible capacity is L (mAh / g) and the active material density is D (g / cm ³ ), the index Ld expressed by the following formula
Is 0 or less.
Ld = L-16.7 × D-6.6
4). Intensity Ia of the maximum peak in the vicinity of 1580 cm ⁻¹ in the Raman spectrum measurement,
Graphite particles for non-aqueous secondary batteries having a Raman R value of 0.13 or more when the intensity ratio Ib / Ia of the maximum peak intensity Ib in the vicinity of 1360 cm ⁻¹ is taken as the Raman R value. A graphite particle for a non-aqueous secondary battery that becomes the electrode according to any one of 1 to 3 above when the is produced.

[Plate production method]
Negative electrode material 20.00 ± 0.02 g, 1 mass% carboxymethylcellulose aqueous solution 20.00 ± 0.02 g (0.200 g in terms of solid content), and styrene-butadiene rubber aqueous dispersion 0.50 having a weight average molecular weight of 270,000 ± 0.02 g (0.2 g in terms of solid content) is stirred with a KEYENCE hybrid mixer for 5 minutes and defoamed for 30 seconds to obtain a slurry.

This slurry was applied to a width of 5 cm by a doctor blade method so that the negative electrode material was 11.0 ± 0.1 mg / cm ² on a 18 μm thick copper foil as a current collector, and air-dried at room temperature. Do. Further, after drying at 110 ° C. for 30 minutes, roll pressing is performed using a roller having a diameter of 20 cm to adjust the density of the active material layer to 1.70 g / cm ³ to obtain a negative electrode sheet.
5). In the nonaqueous secondary battery provided with the positive electrode which can occlude / release lithium ion, the negative electrode which can occlude / release lithium ion, and the electrolyte, the nonaqueous secondary battery according to any one of 1 to 3 above is used as the negative electrode. A non-aqueous secondary battery using a negative electrode for a secondary battery.
6). 5. A non-aqueous secondary battery comprising a positive electrode capable of inserting and extracting lithium ions, a negative electrode capable of inserting and extracting lithium ions, and an electrolyte. A non-aqueous secondary battery using particles.

  When the negative electrode for a non-aqueous secondary battery of the present invention (hereinafter sometimes referred to as “the negative electrode of the present invention”) is used, lithium metal deposition on the electrode surface is suppressed, and the non-aqueous secondary excellent in safety. A battery is provided.

Although the preferable form of this invention is demonstrated in detail below, the following description is an example of this invention and this invention is not limited to these content.
[1] Negative electrode material for non-aqueous secondary battery (1) Graphite particles in negative electrode material The negative electrode material of the present invention contains graphite particles as a main component. It is preferable that the carbonaceous particles are bonded and / or coated with a graphitized binder that is usually heat treated from a graphitizable binder and / or that the carbonaceous particles are attached.

  The carbonaceous particles constituting the graphite particles are not particularly limited as long as they are carbon particles that can be graphitized by firing, but natural graphite, artificial graphite, spheroidized graphite, coke powder, needle coke powder, resin Examples thereof include carbide powder. Among these, it is preferable to use natural graphite because it is easy to increase the density of the active material layer when the active material layer is formed. Among them, spheroidized graphite obtained by spheroidizing graphite is particularly preferable. The spherical graphite particles of the present invention are preferably composed of a plurality of curved or bent scaly or scaly graphites.

  The graphitizable binder is not particularly limited as long as it is carbonaceous that can be graphitized by firing, and petroleum-based and coal-based condensed polycyclic aromatics from tar, soft pitch to hard pitch are preferably used. . Specifically, petroleum heavy oil such as impregnated pitch, coal tar pitch, coal heavy oil such as coal liquefied oil, straight run heavy oil such as asphalten, cracked heavy oil such as ethylene heavy end tar, etc. Oil etc. are mentioned.

  In the process of producing the graphite particles according to the manufacturing method described later, usually, the bonding of a plurality of graphite particles by the binder, that is, the granulation is difficult to proceed, so that one particle of the carbonaceous particles is simply covered or attached by the binder. The layer structure particles that have only been formed are the main structure, but the particles other than the graphite particles such as particles bound by the binder and particles that do not include the carbonaceous particles and are merely carbonized and graphitized by the binder itself. Particles are also generated.

(2) Physical properties of negative electrode material Median diameter <Median diameter measurement method>
In the negative electrode material of the present invention, the median diameter of the graphite particles based on the volume-based particle size distribution measured by laser diffraction / scattering particle size distribution is 5 μm or more, preferably 8 μm or more, and more preferably 10 μm or more. If the median diameter is too small, the specific surface area becomes large, and the strength when made into an electrode plate tends to be weak.

<range>
The median diameter of the graphite particles is 40 μm or less, preferably 35 μm or less, more preferably 30 μm or less. When the median diameter exceeds this upper limit, when used as a negative electrode material, irregularities are generated on the electrode surface, which tends to damage the separator used in the battery.
Tap density In the present invention, the tap density is measured by the following method.

<Tap density measurement method>
Using a powder density meter (“Tap Denser KYT-4000” manufactured by Seishin Enterprise Co., Ltd.), the negative electrode material is dropped through a 20 cm ³ cylindrical tap cell through a 300 μm sieve and filled to fill the cell. Then, a tap with a stroke length of 10 mm is performed 1000 times, and the tap density at that time is measured.

<range>
The tap density of the negative electrode material of the present invention is 0.7 g / cm ³ or more. Preferably, the tap density is 0.75 g / cm ³ or more, further 0.8 g / cm ³ or more, particularly 0.9 g / cm ³ or more. The tap density is preferably 1.3 g / cm ³ or less.
If the tap density is too low, it is necessary to reduce the concentration of the slurry of the negative electrode material applied to the current collector during the production of the negative electrode, the density of the coating film becomes small, and the graphite particles are liable to be destroyed when pressed. Decreases. Conversely, a high tap density is preferable in terms of battery performance, but further steps are required to adjust the shape and particle size distribution of the graphite particles, resulting in a decrease in yield and an increase in cost.

Specific surface area by BET method In the present invention, the specific surface area is measured, for example, by the following method.
<Specific surface area measurement method>
Using a specific surface area measuring device “AMS8000” manufactured by Okura Riken Co., Ltd., the BET one-point method is measured by a nitrogen gas adsorption flow method. Specifically, about 0.4 g of sample (negative electrode material) is filled in a cell, heated to 350 ° C. and pretreated, then cooled to liquid nitrogen temperature and saturated adsorption of 30% nitrogen and 70% He gas. After that, the amount of gas desorbed by heating to room temperature is measured, and the specific surface area is calculated by the usual BET method from the obtained results.

<range>
Negative electrode material, the specific surface area measured by the BET method of the present invention, 0.5 m ² / g or more, preferably 0.8 m ² / g or more, more preferably 1.0 m ² / g or more, ^8m 2 / g or less, preferably 7 m ² / g or less, more preferably 6 m ² / g or less. When the value of the specific surface area is less than this range, the output characteristics when used as a negative electrode material tend to deteriorate. When the specific surface area exceeds this range, the initial irreversible capacity increases, and the cycle characteristics tend to deteriorate.

Raman R value <Definition of Raman R value>
In the Raman spectrum obtained in the Raman measurement as described later, the intensity _{I A} of the maximum peak around 1580 cm ^-1, the intensity ratio _I B / _{I A} Raman R value of the intensity _{I B} of the maximum peak in the vicinity of 1360 cm ^-1 It is defined as

<Method of measuring Raman R value>
Raman measurement uses a Raman spectrometer “Raman Spectrometer manufactured by JASCO Corporation”. Samples are filled by letting the particles to be measured fall naturally into the measurement cell, and the measurement cell is irradiated with an argon ion laser beam. Measurement is performed while rotating the cell in a plane perpendicular to the laser beam. The measurement conditions are as follows.

Argon ion laser light wavelength: 514.5 nm
Laser power on sample: 15-25mW
Resolution: 4cm ^-1
Measurement range: 1100 cm ^{−1 to} 1730 cm ⁻¹
Peak intensity measurement, peak half-width measurement: background processing, smoothing processing
(Simple average, 5 points of convolution)
Maximum peak around 1580 cm ^-1 is a peak derived from a graphite crystalline structure, the maximum peak in the vicinity of 1360 cm ^-1 is a peak derived from reduced carbon atoms symmetry by structural defects.

<range>
The Raman R value of the graphite particles of the present invention is 0.05 or more, preferably 0.08 or more, and particularly preferably 0.10 or more. When the Raman R value is below this lower limit, the amount of lithium metal deposited on the negative electrode surface accompanying charge / discharge tends to increase.
[2] Negative electrode for non-aqueous secondary battery (1) Structure of negative electrode The negative electrode for a non-aqueous secondary battery of the present invention contains a negative electrode active material, a binder for forming an electrode plate, a thickener, and a conductive material as necessary. An active material layer is formed on the current collector. The active material layer is usually prepared by preparing a slurry containing a negative electrode active material, a binder for forming an electrode plate, a thickener, a conductive material and a solvent as required, and applying, drying and pressing the slurry on a current collector. Is obtained.

(2) Electrode plate preparation method Examples of electrode plate preparation methods are given.
Negative electrode material 20.00 ± 0.02 g, 1 mass% carboxymethylcellulose aqueous solution 20.00 ± 0.02 g (0.200 g in terms of solid content), and styrene-butadiene rubber aqueous dispersion 0.50 having a weight average molecular weight of 270,000 ± 0.02 g (0.2 g in terms of solid content) is stirred with a KEYENCE hybrid mixer for 5 minutes and defoamed for 30 seconds to obtain a slurry.

This slurry was applied to a width of 5 cm by a doctor blade method so that the negative electrode material was 11.0 ± 0.1 mg / cm ² on a 18 μm thick copper foil as a current collector, and air-dried at room temperature. Do. Further, after drying at 110 ° C. for 30 minutes, roll pressing is performed using a roller having a diameter of 20 cm to adjust the density of the active material layer to 1.70 g / cm ³ to obtain a negative electrode sheet.
(3) Physical properties of electrode plate Measurement of Raman spectrum of electrode plate surface and current collector contact surface <Active material peeling method from current collector>
After applying the negative electrode material obtained above (hereinafter also referred to as “active material”) to a current collector, cutting the dried and pressed negative electrode into 1 cm square, and sticking it to the bottom of a petri dish with double-sided tape Then, the petri dish is subjected to ultrasonic treatment for 40 minutes in an ultrasonic cleaner having a transmission frequency of 42 kW and an output of 125 watts to peel off the active material.

<Measurement of Raman half-width>
Instead of using powder as a sample, the Raman spectrum is measured in the same manner as described above except that the negative electrode or the peeled active material film is fixed to the sample stage with double-sided tape. Measured in advance the maximum peak of the Raman half-value width of the near 1580 cm ^-1 in the Raman spectrum of the surface of the negative electrode Hs (cm ^-1) prior to peeling from the current collector, also applies to the current collector contact surface of the peeled anode determination of the performed measurements 1580cm maximum peak around ^-1 Raman half-value width Hc (cm ^-1).

<Raman half-value width Hs, Hc range>
Hs and Hc (cm-1) determined by the above method are usually 10 or more, preferably 12 or more, more preferably 15 or more, and usually 40 or less, preferably 38 or less, more preferably 35 or less.
<Range of index Th>
The index Th indicating the degree of deformation of the electrode plate surface obtained from the following equation using Hs, Hc and electrode plate active material density D (g / cm ³ ) obtained by the above method is usually 0.3 or less, preferably 0.1 Hereinafter, it is more preferably −0.1 or less.
Th = Hc- Hs-3.75 × D + 6
If the index Th exceeds this upper limit, the deformation of the graphite particles existing on the negative electrode surface becomes large, the pores through which lithium ions move are blocked, and the acceptability deteriorates. There is a tendency to precipitate easily.
<Measurement of indicator Tr>
And strength Ia_s maximum peak around 1580 cm ^-1 in the Raman spectrum measurement of the electrode plate surface, the intensity ratio Ib_s / Ia_s of the intensity of the largest peak in the vicinity of 1360cm ^-1 Ib_s Rs, Raman spectrum of the surface in contact with the current collector when the intensity of the maximum peak in the vicinity of 1580cm ^-1 Ia_c in the measurement, the intensity ratio Ib_c / Ia_c of the intensity of the largest peak in the vicinity of 1360cm ^-1 Ib_c was Rc, indicators Tr of the following formula is usually less than 0 .
Tr = Rs- Rc- 0.04 × D + 0.06
If the index Tr exceeds this upper limit, the deformation of the graphite particles existing on the negative electrode surface becomes large, the pores through which lithium ions move are blocked and the acceptability deteriorates. Li metal is deposited on the electrode surface during charging. It tends to be easy to do.
<Range of indicators Rs and Rc>
Rs and Rc determined by the above method are usually 0.05 or more, preferably 0.08 or more, more preferably 0.10 or more. When Hs falls below this lower limit, lithium acceptability tends to decrease, and Li metal tends to precipitate on the electrode surface during charging.

Range of index Ld When L (mAh / g) is the irreversible capacity measured by the method described later and D (g / cm ³ ) is the active material density, the index Ld represented by the following formula is usually 0 or less.
Ld = L-16.7 × D-6.6
If the index Ld exceeds this upper limit, the irreversible capacity increases with respect to the reversible capacity, making it unsuitable as an electrode plate for a high capacity battery.

(3) Production method of negative electrode material The negative electrode material of the present invention comprising graphite particles as a main component is mixed with carbonaceous particles as a raw material, a binder, etc., and molded, devolatilized component fired, graphitized as necessary. Manufactured by pulverization and classification.
In order to produce the negative electrode material of the present invention satisfying the aforementioned physical properties, needle coke or natural graphite is preferably used as the main component of the carbonaceous particles. In the step of graphitizing by kneading the carbonaceous particles and the binder, the type and amount of the catalyst at the time of graphitization are optimized (for example, in the case of SiC generally used as a graphitization catalyst, the addition amount is set to the base material 100). It is preferable to maintain an appropriate amorphous amount by a method such as 30 parts or less with respect to parts.

In the production of the graphite particles as defined in the present invention, the intensity Ia of the maximum peak around 1580 cm ^-1 in the Raman spectrum measurement of the electrode plate surface, the intensity ratio Ib / Ia of the intensity Ib of the maximum peak in the vicinity of 1360 cm ^-1 When the Raman R value is set, it is preferable to optimize the type and amount of the pitch as a binder and the temperature at which graphitization is performed so that the Raman R value is 0.13 or more.

The total time is preferably within 2 hours.
The suitable manufacturing method of the negative electrode material of this invention is demonstrated in detail below.
First, the carbonaceous particles and the binder are mixed while being heated. At this time, a graphitization catalyst may be added if desired. Suitable carbonaceous particles, binders, and graphitization catalysts are as follows.
Carbonaceous particles As a main component of carbonaceous particles that are primary particles as raw materials, natural graphite, needle coke, and volatile components that volatilize during heat treatment (hereinafter sometimes referred to as “VM”).
Fresh coke containing is used. As raw coke, it is preferable to use carbonaceous particles containing 2 to 10 wt% of volatile components that volatilize during heat treatment. These may be used alone or in combination.

The median diameter of the volume-based particle size distribution measured by laser diffraction / scattering type particle size distribution measurement of carbonaceous particles is not particularly limited, but is 5 μm or more, especially 6 μm or more, particularly 8 μm or more, 40 μm or less, especially 35 μm or less, especially 30 μm or less is preferable.
If the median diameter of the carbonaceous particles is below this lower limit, the cost required for pulverizing the carbonaceous particles is not economical, and if it exceeds the upper limit, the median diameter of the graphite particles tends to increase, resulting in the above-mentioned problems. The median diameter of the carbonaceous particles can be measured in the same manner as the median diameter of the negative electrode material described above.

The average particle size of the carbonaceous particles is 2 times or less, preferably 1.5 times or less, more preferably 1.2 times or less, and 0.2 times the average particle size. It is more than twice, more preferably more than 0.4 times, more preferably more than 0.6 times.
Specific examples of the binder include impregnated pitch, coal tar pitch, coal-based heavy oil such as coal liquefied oil, straight-run heavy oil such as asphalten, cracked heavy oil such as ethylene heavy end tar, etc. And other heavy petroleum oils.

  The quinoline insoluble component contained in the binder is usually 0 to 10 wt%, but the smaller the amount, the more preferable in terms of the hardness of the graphite particles and the capacity of the battery. If the content of the quinoline-insoluble component in the binder is too high, the resulting graphite particles are hard, and even when the active material layer applied to the current collector is pressed, the particles are not easily deformed, making it difficult to increase the density. In addition, the capacity tends to decrease.

In the production of the graphite particles as defined in the present invention, the intensity Ia of the maximum peak around 1580 cm ^-1 in the Raman spectrum measurement of the electrode plate surface, the intensity ratio Ib / Ia of the intensity Ib of the maximum peak in the vicinity of 1360 cm ^-1 When the Raman R value is used, it is desirable to adjust the binder amount so that the Raman R value is 0.13 or more. When the amount of the binder is too large, the amorphous part derived from the binder is increased in the final product, so that the battery capacity may be reduced when the battery is used. Moreover, since the obtained graphite particles are hardened, when the active material layer applied to the current collector is pressed, the carbonaceous particles themselves are liable to be destroyed rather than the binder portion.

  On the other hand, the battery properties are better when the amount of the binder is smaller, but when the amount is too small, the electrode plate is a pressing step which is one of the steps for processing a negative electrode material mainly composed of graphite particles into a negative electrode plate. Because the graphite particles existing on the surface of the battery are fragile, the communication hole, which is the lithium ion diffusion path, is blocked, and the rapid charge / discharge characteristics are degraded. There is a tendency for metals to be easily deposited.

The amount of the binder in the negative electrode material is controlled by the amount of the binder added at the stage before the combination. For example, when the residual carbon ratio of the binder obtained by the method described in JIS K2270 is X%, a desired amount of binder is added 100 / X times the desired amount.
As a device for adding a binder such as pitch and tar, it is preferable to uniformly disperse as much as possible at a low temperature and in a short time to reduce the initial irreversible capacity and the press load. In order to perform dispersion at a low temperature and in a short time, stirring should be strengthened to such an extent that the carbonaceous particles are not broken.

Graphitization catalyst In order to increase the charge / discharge capacity and improve the pressability, a graphitization catalyst may be added when mixing the carbonaceous particles and the binder. Examples of the graphitization catalyst include metals such as iron, nickel, titanium, silicon, and boron, and compounds such as carbides, oxides, and nitrides thereof. Of these, silicon, silicon compounds, iron, and iron compounds are preferable, and silicon carbide is particularly preferable among silicon compounds, and iron oxide is particularly preferable among iron compounds.

  When silicon or a silicon compound is used as the graphitization catalyst, all of the silicon carbide produced by heating is pyrolyzed at a temperature of 2800 ° C. or higher to grow graphite with extremely good crystallinity, and when silicon is volatilized, graphite crystals Since pores are formed between them, the charge transfer reaction and diffusion of lithium ions inside the particles can be promoted, and the battery performance can be improved. Further, when iron or a compound thereof is used as the graphitization catalyst, graphite having good crystallinity can be grown by the mechanism of dissolution and precipitation of carbon in the catalyst, and the same effect as silicon can be exhibited.

  The addition amount of these graphitization catalysts is 30 wt% or less, preferably 20 wt% or less, more preferably 10 wt% or less, and particularly preferably 5 wt% or less with respect to the carbonaceous primary particles as a raw material. If there is too much graphitization catalyst, graphitization proceeds too much, and the graphite present on the surface of the electrode plate is a pressing step that is one of the steps of processing a negative electrode material mainly composed of graphite particles into a negative electrode plate. Lithium particles tend to break down, and the charge acceptability deteriorates by closing the communication hole, which is a lithium ion diffusion path, or Li metal tends to deposit on the electrode surface during charging.

Combined
The raw materials such as carbonaceous particles, binder, and optionally added graphitization catalyst are first combined under heating. As a result, a liquid binder is attached to the carbonaceous particles and the raw material that does not melt at the compounding temperature.

In this case, all raw materials may be charged into the compounding machine and mixing and heating may be performed simultaneously, or components other than the binder may be charged into the compounding machine and heated with stirring, and after the temperature has risen to the compounding temperature, the room temperature or melting A state binder may be charged.
The heating temperature is equal to or higher than the softening point of the binder. If the heating temperature is too low, the viscosity of the binder increases and uniform mixing becomes difficult. It is performed at a temperature 20 ° C. or higher. If the heating temperature is too high, the viscosity of the combined system becomes too high due to the volatilization and polycondensation of the binder, and is usually 300 ° C. or lower, preferably 250 ° C. or lower.

  The combination machine is preferably a model having a stirring blade, and the stirring blade may be a general-purpose one such as a Z type or a gusset type. The amount of the raw material charged into the compounding machine is usually 10 vol% or more, preferably 15 vol% or more, and 50 vol% or less, preferably 30 vol% or less of the compounding machine volume. The mixing time is 5 minutes or more, and is the time until the maximum viscosity change due to the volatilization of the volatile matter at the longest, usually 30 to 120 minutes. The compounding machine is preferably preheated to the compounding temperature prior to compounding.

Molding The obtained compound may be used as it is in a de-VM firing step for the purpose of removing volatile components (VM) and carbonization, or after being molded for easy handling, it is used in a de-VM firing step. May be.
The molding method is not particularly limited as long as the shape can be maintained, and extrusion molding, mold molding, isostatic pressing, and the like can be employed. Of these, extrusion is easy to orient the particles in the molded body, and hydrostatic pressure molding that keeps the particle orientation random but difficult to increase productivity, and is relatively easy to operate. Mold molding that can obtain a molded body without destroying the resulting structure is preferred.

  The molding temperature may be either room temperature (cold) or under heating (hot, temperature above the softening point of the binder). In the case of cold molding, in order to improve the moldability and obtain uniformity of the molded body, it is desirable to preliminarily crush the compound that has been cooled after compounding to a maximum dimension of 1 mm or less. The shape and size of the molded body are not particularly limited. However, in hot forming, if the molded body is too large, there is a problem that it takes time to perform uniform preheating prior to molding. Therefore, the maximum size is preferably about 150 cm. The size is as follows.

If the molding pressure is too high, it is difficult to remove devolatilized components (de-VM) through the pores of the molded body, and carbon particles that are not perfect circles are oriented, making it difficult to grind in the subsequent process. Therefore, the molding pressure is preferably 3 tf / cm ² (294 MPa) or less, more preferably 500 kgf / cm ² (49 MPa) or less, and even more preferably 10 kgf / cm ² (0.98 MPa) or less. The lower limit pressure is not particularly limited, but is preferably set to such an extent that the shape of the molded body can be maintained in the VM removal step.

De-VM firing The resulting mixture or molded body is necessary to remove carbonaceous particles and binder volatile components (VM) and prevent contamination of the filler during graphitization and sticking of the filler to the molded body. Accordingly, VM removal is performed. An inert container such as a crucible may be filled and fired, or in the case of a molded body, the container may not be used and may be put into the furnace as it is. The de-VM firing is usually performed at a temperature of 500 ° C. or higher, preferably 600 ° C. or higher, preferably 1700 ° C. or lower, more preferably 1400 ° C. or lower, preferably for 0.1 to 10 hours. In order to prevent oxidation, heating is usually performed in a non-oxidizing atmosphere in which an inert gas such as nitrogen or argon is circulated or a granular carbon material such as breeze or packing coke is filled in the gap.

The equipment used for the de-VM firing is not particularly limited as long as it can be fired in a non-oxidizing atmosphere such as an electric furnace, a gas furnace, or a lead hammer furnace for electrode materials. The heating rate during heating is desirably a low speed for removing volatile components. Usually, from about 200 ° C. where low-boiling components start to volatilize to about 700 ° C. where only hydrogen is generated, 3-100 ° C. The temperature is raised at / hr.
Graphitization The carbonized mixture or molded product obtained as a result of de-VM firing as necessary is then graphitized by heating at a high temperature. As the heating temperature during graphitization decreases, graphitization does not progress, so the obtained negative electrode material becomes harder, and high pressure is required when the active material layer applied to the current collector is pressed to a predetermined bulk density. In the production of graphitic particles as defined in the present invention, the intensity Ia of the maximum peak near 1580 cm ⁻¹ in the Raman spectrum measurement of the electrode plate surface, and 1360 cm ⁻ It is desirable to adjust the graphitization temperature so that the Raman R value> 0.13 when the intensity ratio Ib / Ia of the maximum peak intensity Ib near ¹ is the Raman R value.
The heating time may be performed until the binder and the carbonaceous particles become graphite, and is usually 1 to 24 hours.

In order to prevent oxidation, the atmosphere during graphitization is performed under a non-oxidizing atmosphere in which an inert gas such as nitrogen or argon is circulated or a granular carbon material such as breeze or packing coke is filled in the gap.
The equipment used for graphitization is not particularly limited as long as it meets the above-mentioned purpose, such as an electric furnace, a gas furnace, an electrode material Atchison furnace, and the heating rate, cooling rate, heat treatment time, etc. are acceptable for the equipment used. It can be set arbitrarily within the range.

Pulverization The graphitized product thus obtained is adjusted to a desired particle size distribution by pulverization and sieving as necessary.
The method of pulverizing the graphitized product is not particularly limited, but as a pulverizing unit, mechanically pulverizing units such as a ball mill, a hammer mill, a CF mill, an atomizer mill, a pulverizer, etc., and pulverization using wind force are used. Means such as a jet mill can be exemplified. For coarse pulverization and intermediate pulverization, a pulverization method using an impact force such as a jaw crusher, a hammer mill, or a roller mill may be used.

Here, the timing of pulverization may be between firing and graphitization, or after graphitization. When de-VM firing is not performed, after graphitization is preferable.
Classification The large sized granular material and the small sized granular material (fine powder) are removed from the obtained pulverized material. By removing the large-diameter granular material, occurrence of a short circuit can be prevented and unevenness during application can be eliminated. By removing large particles and fine particles, the volume standard particle size distribution by laser diffraction / scattering particle size measurement is 3% or less of the total particle size of 100 μm or more and 1 μm or less of the total particle size. It is desirable to adjust the particle size to be 1% or less.

There are various methods for removing large-diameter granular materials and small-diameter granular materials, but it is preferable to remove them by sieving or classification in terms of simplicity of equipment, operability and cost. Further, sieving or classification has the advantage that the particle size distribution and average particle size of the graphitic particles can be readjusted as needed by subsequent graphitization and removal of the particulates.
For sieving for removing large-diameter granular materials, there are a mesh surface fixed type, an in-plane motion type, a rotary sieve type, etc., but from the viewpoint of processing capacity, a mesh surface fixed type blow-through type sieve is particularly preferable. . The size of the sieve mesh used can be any if it is 150 μm or less and 30 μm or more, and the production status (particularly the amount and particle size) of the granular material to be removed, the particle size distribution and average of the graphite particles Select and use as appropriate according to the particle size adjustment requirements. If the size exceeds 150 μm, the removal of the particulate matter becomes insufficient, and if it is less than 30 μm, it leads to excessive removal of graphite particles, resulting in a lot of product loss and difficulty in adjusting the particle size distribution. It is not preferable. In addition, sieves with a mesh size of 45 μm and 38 μm that are commercially available as general-purpose sizes can be preferably used.

  Classification can be performed by methods such as wind classification, wet classification, and specific gravity classification, and is not particularly limited for removing particulates of 150 μm or more. However, the influence on the properties of the graphite particles and the particle size distribution of the graphite particles are not limited. In consideration of adjusting the average particle size, it is preferable to use an air classifier such as a swirling flow classifier. In this case, by controlling the air volume and the wind speed, it is possible to adjust the removal of the particulate matter, the particle size distribution of the graphite particles, and the average particle size in the same manner as the size of the mesh opening is adjusted. .

[2] Negative electrode for non-aqueous secondary battery The negative electrode and graphite particles of the present invention can be suitably used as a negative electrode or a negative electrode active material for a non-aqueous secondary battery, particularly a lithium secondary battery.
The negative electrode constituting the nonaqueous secondary battery is formed by forming, on a current collector, an active material layer containing a negative electrode active material, an electrode plate forming binder, a thickener, and, if necessary, a conductive material. The active material layer is usually prepared by preparing a slurry containing a negative electrode active material, a binder for forming an electrode plate, a thickener, a conductive material and a solvent as required, and applying, drying and pressing the slurry on a current collector. Is obtained.

  The graphite particles for non-aqueous secondary batteries of the present invention (hereinafter sometimes abbreviated as “graphitic particles (A)”) can be used alone as a negative electrode material for non-aqueous secondary batteries. The one or more graphite particles selected from the group consisting of graphite, artificial graphite, vapor-grown carbon fiber, conductive carbon black, amorphous-coated graphite, resin-coated graphite, and amorphous carbon are shapes or It is also preferable to further contain carbonaceous particles having different physical properties (hereinafter abbreviated as “carbonaceous particles (B)”) to obtain a negative electrode material for a non-aqueous secondary battery.

  By appropriately selecting and mixing the carbonaceous particles (B), it becomes possible to improve cycle characteristics by improving conductivity, improve charge acceptability, reduce irreversible capacity, and improve pressability.

Among the carbonaceous particles (B), as the natural graphite, for example, highly purified flaky graphite or spheroidized graphite can be used. The volume-based average particle diameter of natural graphite is usually 8 μm or more, preferably 10 μm or more, and usually 60 μm or less, preferably 40 μm or less. Natural graphite has a BET specific surface area of usually 4 m ² / g or more, preferably 4.5 m ² / g or more, usually 9 m ² / g or less, preferably 7.5 m ² / g or less.

As the artificial graphite, for example, particles obtained by combining coke powder or natural graphite with a binder, particles obtained by firing and graphitizing single graphite precursor particles in a powder state, and the like can be used.
As amorphous carbon-coated graphite, for example, natural graphite or artificial graphite coated with an amorphous carbon precursor and fired, or natural graphite or artificial graphite coated with amorphous carbon on the surface are used. Can do.
As the resin-coated graphite, for example, particles obtained by coating and drying a polymer material on natural graphite or artificial graphite can be used, and as amorphous carbon, for example, particles obtained by firing bulk mesophase, Particles obtained by infusibilizing and firing a carbon precursor can be used.

Among these, when blended with the graphite particles of the present invention as carbonaceous particles (B), natural graphite is particularly preferable because a high capacity is maintained.
When the carbonaceous particles (B) are mixed with the graphite particles (A) to form the negative electrode material, the mixing ratio of the carbonaceous particles (B) is such that the carbonaceous particles of less than 5 μm are mixed with the whole negative electrode material. In this case, it is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, and when mixing carbonaceous particles of 5 μm or more, preferably 5% by mass or more. Especially preferably, it is 15% or more. Moreover, it is 95 mass% or less normally, Preferably it is the range of 80 mass% or less. When the mixing ratio of the carbonaceous particles (B) is less than the above range, the above effect of adding the carbonaceous particles (B) may be difficult to appear. On the other hand, if the above range is exceeded, it may be difficult to obtain the characteristics of the graphite particles (A).

  There are no particular restrictions on the apparatus used for mixing. For example, as a rotary mixer, a cylindrical mixer, a twin cylindrical mixer, a double cone mixer, a regular cubic mixer, a vertical mixer, etc. Examples of the fixed mixer include a spiral mixer, a ribbon mixer, a Muller mixer, a Helical Flight mixer, a Pugmill mixer, and a fluidized mixer.

  As the electrode plate forming binder, any material can be used as long as it is a material that is stable with respect to a solvent and an electrolytic solution used during electrode production. Examples thereof include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, styrene / butadiene rubber, isoprene rubber, butadiene rubber, ethylene-acrylic acid copolymer, and ethylene-methacrylic acid copolymer. The weight ratio of the active material / electrode plate forming binder in the electrode plate forming binder is preferably 90/10 or more, more preferably 95/5 or more, and preferably 99.9 / 0.1 or less, preferably Is in the range of 99.5 / 0.5 or less.

Examples of the thickener include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, and casein.
Examples of the conductive material include carbon materials such as graphite and carbon black; metal materials such as copper and nickel.

Examples of the material for the current collector include copper, nickel, and stainless steel. Among these, a copper foil is preferable from the viewpoint of easy processing into a thin film and cost.
The density of the active material layer is 1.70 g / cm ³ or more, preferably 1.73 g / cm ³ or more, more preferably 1.75 g / cm ³ in applications where capacity is important. If the density is too low, the capacity of the battery per unit volume is not always sufficient. Moreover, since a rate characteristic will fall when a density is too high, 1.9 g / cm < ³ > or less is preferable.

Here, the active material layer means a mixture layer made of an active material on a current collector, an electrode plate forming binder, a thickener, a conductive material, etc., and the density means a bulk density at the time of assembling the battery. .
[3] Non-aqueous secondary battery The negative electrode for a non-aqueous secondary battery of the present invention produced using the negative electrode material of the present invention is extremely useful as a negative electrode for a non-aqueous secondary battery such as a lithium secondary battery. .

There is no particular limitation on the selection of members necessary for the battery configuration such as the positive electrode and the electrolytic solution constituting such a non-aqueous secondary battery. Although the material of the member which comprises a non-aqueous secondary battery etc. is illustrated below, the material which can be used is not limited to these specific examples.
The non-aqueous secondary battery of the present invention usually comprises the above-described negative electrode, positive electrode and electrolyte of the present invention.

The positive electrode is formed by forming an active material layer containing a positive electrode active material, a conductive agent, and an electrode plate forming binder on a positive electrode current collector. The active material layer is usually obtained by preparing a slurry containing a positive electrode active material, a conductive agent and an electrode plate forming binder, and applying and drying the slurry on a current collector.
Examples of the positive electrode active material include lithium transition metal composite oxide materials such as lithium cobalt oxide, lithium nickel oxide, and lithium manganese oxide; transition metal oxide materials such as manganese dioxide; carbonaceous materials such as graphite fluoride A material capable of inserting and extracting lithium, such as, can be used. Specifically, LiFeO ₂ , LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ and their non-stoichiometric compounds, MnO ₂ , TiS ₂ , FeS ₂ , Nb ₃ S ₄ , Mo ₃ S ₄ , CoS ₂ , V ₂ O ₅ , P ₂ O ₅ , CrO ₃ , V ₃ O ₃ , TeO ₂ , GeO ₂ or the like can be used.

As the positive electrode current collector, it is preferable to use a metal or an alloy thereof that forms a passive film on the surface by anodic oxidation in an electrolytic solution, and belongs to IIIa, IVa, Va group (3B, 4B, 5B group). And their alloys. Specifically, Al, Ti, Zr, Hf, Nb, Ta and alloys containing these metals can be exemplified, and Al, Ti, Ta and alloys containing these metals can be preferably used. . In particular, Al and its alloys are desirable because of their light weight and high energy density.

Examples of the electrolyte include an electrolytic solution, a solid electrolyte, and a gel electrolyte. Among them, an electrolytic solution, particularly a nonaqueous electrolytic solution is preferable. As the non-aqueous electrolyte solution, a solution obtained by dissolving a solute in a non-aqueous solvent can be used.
As the solute, an alkali metal salt, a quaternary ammonium salt, or the like can be used. Specifically, LiClO ₄ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F _It is preferable to use one or more compounds selected from the group consisting of ₉ SO ₂ ) and LiC (CF ₃ SO ₂ ) ₃ .

  Examples of non-aqueous solvents include cyclic carbonates such as ethylene carbonate, butylene carbonate, and vinylene carbonate; cyclic ester compounds such as γ-butyrolactone; chain ethers such as 1,2-dimethoxyethane; crown ether, 2-methyltetrahydrofuran, 1, Cyclic ethers such as 2-dimethyltetrahydrofuran, 1,3-dioxolane, and tetrahydrofuran; chain carbonates such as diethyl carbonate, ethyl methyl carbonate, and dimethyl carbonate can be used. One kind of solute and solvent may be selected and used, or two or more kinds may be mixed and used. Among these, the non-aqueous solvent preferably contains a cyclic carbonate and a chain carbonate.

The content of these solutes in the electrolytic solution is preferably 0.2 mol / l or more, particularly 0.5 mol / l or more, and 2 mol / l or less, particularly 1.5 mol / l or less.
Among these, the non-aqueous secondary battery prepared by combining the negative electrode according to the present invention, a metal chalcogenide-based positive electrode for a commonly used lithium ion battery and an organic electrolyte mainly composed of a carbonate-based solvent has a large capacity, Low irreversible capacity observed in the initial cycle, high rapid charge / discharge capacity (good rate characteristics), excellent cycle characteristics, high battery storage and reliability when left at high temperature, high efficiency discharge characteristics and It has excellent discharge characteristics at low temperatures.

  The nonaqueous electrolytic solution may contain a film forming agent. Examples of the film forming agent include carbonate compounds such as vinylene carbonate, vinyl ethyl carbonate, and methylphenyl carbonate, alken sulfides such as ethylene sulfide and propylene sulfide, sultone compounds such as 1,3-propane sultone and 1,4-butane sultone, and maleic acid. Acid anhydrides such as anhydride and succinic anhydride are listed. The content of the film forming agent is usually 10% by weight or less, preferably 8% by weight or less, more preferably 5% by weight or less, and most preferably 2% by weight or less. If the content of the film forming agent is too large, other battery characteristics such as an increase in initial irreversible capacity, low temperature characteristics, and rate characteristics may be adversely affected.

  A separator is usually provided between the positive electrode and the negative electrode so that the positive electrode and the negative electrode are not in physical contact. The separator preferably has high ion permeability and low electrical resistance. The material and shape of the separator are not particularly limited, but those that are stable with respect to the electrolyte and excellent in liquid retention are preferable. Specifically, a porous sheet or a non-woven fabric made of a polyolefin such as polyethylene or polypropylene is used.

  The shape of the non-aqueous secondary battery of the present invention is not particularly limited, and a cylinder type in which a sheet electrode and a separator are spiral, a cylinder type having an inside-out structure in which a pellet electrode and a separator are combined, a coin in which a pellet electrode and a separator are stacked Type.

EXAMPLES Next, specific embodiments of the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
[Example 1]
Spherical graphite particles having an average particle diameter of 17.3 μm were obtained by subjecting graphite having an average particle diameter of 100 μm to spheroidization using a hybridization system NHS-3 manufactured by Nara Machinery Co., Ltd. for 7 minutes at a rotor peripheral speed of 60 m / sec.

The spherical graphite particles and a binder pitch having a softening point of 88 ° C. as a graphitizable binder were mixed, put into a kneader having a machiskater type stirring blade preheated to 128 ° C., and mixed for 20 minutes.
The sufficiently combined mixture was placed in a graphite crucible and heated until the Raman R value after subsequent pulverization and classification was 0.21.

The obtained graphite fired body was finely pulverized by a mill with a pulverization blade rotation speed set to 7800 rotations / minute, and coarse particles were removed with a 45 μm sieve to obtain graphite particles. Table 1 shows the Raman R value, median diameter, tap density, and BET specific surface area of the obtained graphite particles.
(I) Production method of electrode plate (negative electrode sheet) and measurement of press load Using this composite graphite particle as a negative electrode material, an active material layer having an active material layer density of 1.70 ± 0.03 g / cm ³ by the above-described method. An electrode plate was prepared. Specifically, 20.00 ± 0.02 g of the negative electrode material, 20.00 ± 0.02 g of a 1% by mass carboxymethylcellulose aqueous solution (0.200 g in terms of solid content), and a styrene / polysiloxane having a weight average molecular weight of 270,000. Aqueous dispersion of butadiene rubber 0.50 ± 0.02 g (0.2 g in terms of solid content) was stirred for 5 minutes with a hybrid mixer manufactured by Keyence and defoamed for 30 seconds to obtain a slurry.

This slurry was applied to a width of 5 cm by a doctor blade method so that the negative electrode material was 11.0 ± 0.1 mg / cm ² on a 18 μm thick copper foil as a current collector, and air-dried at room temperature. went. Further, after drying at 110 ° C. for 30 minutes, roll pressing was performed using a roller having a diameter of 20 cm to adjust the density of the active material layer to 1.70 g / cm ³ to obtain a negative electrode sheet.
<Creating a coin battery>
The prepared negative electrode sheet was punched into a disk shape with a diameter of 12.5 mm to make a negative electrode, and a lithium metal foil was punched into a disk shape with a diameter of 12.5 mm to make a positive electrode. Between the negative electrode and the positive electrode, 1 m of LiPF ₆ was added to a mixed solvent of ethylene carbonate and ethyl methyl carbonate (volume ratio = 1: 1).
A separator (made of a porous polyethylene film) impregnated with an electrolytic solution dissolved so as to be ol / l was placed to produce a 2016 coin-type battery.

<Initial charge irreversible capacity>
The prepared 2016 coin-type battery was left for 24 hours, and then charged at a current density of 0.16 mA / cm ² until the potential difference between both electrodes was 0 V, and then 0.33 mA / cm ² until 1.5 V was reached. A discharge was performed. The reference charge / discharge test was performed, and the average value of the discharge capacity at the first cycle was defined as the initial charge / discharge capacity. Moreover, the irreversible capacity | capacitance (initial charge capacity-initial discharge capacity) which generate | occur | produces in the 1st cycle was made into the initial charge irreversible capacity | capacitance. For the three coin-type batteries, the initial charge irreversible capacity was measured, and the average value was obtained. After measuring the irreversible capacity of the initial charge, the coin-type battery was disassembled and the state of lithium metal deposition on the negative electrode surface was visually observed. The results are shown in Table 1.

Comparative Example 1
Spherical graphite particles having an average particle diameter of 21.7 μm are obtained by subjecting graphite particles having an average particle diameter of 100 μm to spheroidizing treatment using a hybrid system NHS-3 manufactured by Nara Machinery Co., Ltd. for 9 minutes at a rotor peripheral speed of 70 m / sec. It was. Firing, pulverization, and classification were performed in the same manner as in Example 1 to obtain graphite particles having a Raman R value of 0.13. The results of evaluation in the same manner as in Example 1 are shown in Table 1.

From Table 1, it is clear that the battery using the negative electrode or the negative electrode material of the present invention has no lithium metal deposition on the negative electrode surface during charge and discharge and is excellent in safety.

By using the negative electrode material of the present invention, there is little lithium metal deposition during charging and discharging when a non-aqueous secondary battery is made, and the negative electrode for non-aqueous secondary batteries and non-aqueous secondary batteries that are excellent in safety are stable. Therefore, the present invention is very useful industrially in the field of various non-aqueous secondary batteries.
Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention.

Claims (6)

A negative electrode for a non-aqueous secondary battery having an electrode active material density of 1.70 g / cm ³ or more and satisfying the following (1) and / or (2).
(1) When the Raman spectrum of the electrode surface active material and the current collector contact surface active material is measured by a predetermined method, and the half-widths of the maximum peaks near 1580 cm ⁻¹ are Hs and Hc, respectively, The indicated index Th is 0.3 or less.
Th = Hc- Hs- 3.75 × D + 6
(2) the electrode surface active Raman spectrum of the maximum peak intensity Ib_s maximum peak around intensity Ia_s and 1360 cm ^-1 in the vicinity of 1580 cm ^-1 in the measured intensity ratio Ib_s / Ia_s substances when the Rs, with Rs 0.13 or more is there. A negative electrode for a non-aqueous secondary battery having an electrode active material density of 1.70 g / cm ³ or more and satisfying the following (2) and / or (3).
(2) the electrode surface active Raman spectrum of the maximum peak intensity Ib_s maximum peak around intensity Ia_s and 1360 cm ^-1 in the vicinity of 1580 cm ^-1 in the measured intensity ratio Ib_s / Ia_s substances when the Rs, with Rs 0.13 or more is there.
(3) is in contact with the intensity of the maximum peak in the vicinity of 1580 cm ^-1 in the Raman spectrum measurement of the electrode surface active material Ia_s, the intensity ratio Ib_s / Ia_s of the intensity of the largest peak in the vicinity of 1360cm ^-1 Ib_s Rs, the collector 1580 cm ^{−1 in the} measurement of the Raman spectrum of the active material surface
When the intensity ratio Ib_c / Ia_c between the intensity Ia_c of the maximum peak near and the intensity Ib_c of the maximum peak near 1360 cm ⁻¹ is Rc, the index Tr expressed by the following formula is less than 0.
Tr = Rs- Rc- 0.04 × D + 0.06 The negative electrode for a non-aqueous secondary battery according to claim 1, further satisfying the following.
(4) When the irreversible capacity is L (mAh / g) and the active material density is D (g / cm ³ ), the index Ld expressed by the following formula
Is 0 or less.
Ld = L-16.7 × D-6.6 The intensity Ia of the maximum peak near 1580 cm ⁻¹ in the Raman spectrum measurement, and 13
Graphite particles for non-aqueous secondary batteries having a Raman R value of 0.13 or more when the intensity ratio Ib / Ia of the maximum peak intensity Ib in the vicinity of 60 cm ⁻¹ is taken as the Raman R value. A graphite particle for a non-aqueous secondary battery that becomes the electrode according to any one of claims 1 to 3.
[Plate production method]
Negative electrode material 20.00 ± 0.02 g, 1 mass% carboxymethylcellulose aqueous solution 20.00 ± 0.02 g (0.200 g in terms of solid content), and styrene-butadiene rubber aqueous dispersion 0.50 having a weight average molecular weight of 270,000 ± 0.02 g (0.1 g in terms of solid content) is stirred with a KEYENCE hybrid mixer for 5 minutes and defoamed for 30 seconds to obtain a slurry.
This slurry was applied to a width of 5 cm by a doctor blade method so that the negative electrode material was attached to 11.0 ± 0.1 mg / cm ² on a 18 μm thick copper foil as a current collector, and air-dried at room temperature. Do. Further, after drying at 110 ° C. for 30 minutes, roll pressing is performed using a roller having a diameter of 20 cm to adjust the density of the active material layer to 1.70 g / cm ³ to obtain a negative electrode sheet.   The nonaqueous system according to any one of claims 1 to 3, wherein a nonaqueous secondary battery including a positive electrode capable of inserting and extracting lithium ions, a negative electrode capable of inserting and extracting lithium ions, and an electrolyte is used as the negative electrode. A non-aqueous secondary battery using a negative electrode for a secondary battery.   5. A nonaqueous secondary battery comprising a positive electrode capable of inserting and extracting lithium ions, a negative electrode capable of inserting and extracting lithium ions, and an electrolyte. A non-aqueous secondary battery characterized by using particulate particles.