JP3399015B2 - Negative electrode material and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negative electrode material for use in a non-aqueous electrolyte secondary battery, in which lithium is doped and dedoped, and a method for producing the same.

[0002]

2. Description of the Related Art With the miniaturization of electronic devices, higher energy density of batteries is required, and various non-aqueous electrolyte batteries such as so-called lithium batteries have been proposed to meet such demand. However, for example, a battery using lithium metal for the negative electrode has the following drawbacks especially when it is used as a secondary battery. That is, (1) charging usually requires 5 to 10 hours, inferior quick charging property, and (2) short cycle life.

All of these are caused by the lithium metal itself, and are attributed to changes in the lithium form that occur with repeated charging and discharging, formation of dendrite-like lithium, and irreversible changes of lithium. .

Therefore, as one method for solving these problems, it has been proposed to use a carbonaceous material for the negative electrode. This utilizes the fact that a lithium-carbon intercalation compound can be easily formed electrochemically. For example, when carbon is used as a negative electrode and a compound containing lithium as a positive electrode is charged in a non-aqueous electrolyte, The lithium is electrochemically doped between the layers of the negative carbon. The carbon thus doped with lithium functions as a lithium electrode, and the lithium in the negative electrode is dedoped from the carbon layers with discharge and returns to the positive electrode.

As such a carbonaceous material, we have disclosed in Japanese Unexamined Patent Publication No. 3-252053 that the (002) plane spacing d ₀₀₂ is 3.70 Å or more and the true density is 1.70 g / cm 3.
Less than ³ , 70 in differential thermal analysis (DTA) in air
It was shown that the non-graphitizable carbon material having no exothermic peak above 0 ° C. is excellent in the amount of lithium doping / dedoping.

[0006]

In the non-aqueous electrolyte secondary battery using the above carbonaceous material, the current capacity (mAh / g) per unit weight of the negative electrode depends on the lithium doping amount of the carbonaceous material. Decided. Therefore, it is desirable that the carbonaceous material have as large a doping amount of lithium as possible (theoretically, the ratio of 1 Li atom to 6 carbon atoms is the upper limit). From this point of view, the above-mentioned carbonaceous material is not sufficient although a large lithium doping amount can be obtained as compared with the conventional carbonaceous material.

Therefore, the present invention has been proposed in view of such conventional circumstances, and an object thereof is to provide a negative electrode material having a large lithium doping amount and a sufficient current capacity and a method for producing the same. To do.

[0008]

In order to achieve the above object, the inventors of the present invention have conducted a long-term study, and as a result, in the non-graphitizable carbon material, the weight ratio Ps of carbon atoms having a laminated structure and the stacking By controlling the index SI and the average number of laminated layers n _ave of the laminated structure portion so that the proportion of the laminated structure portion becomes small, the half-value half width H of the peak near 1340 cm ^{−1 in the} Raman spectrum is further suppressed.
We have come to the knowledge that a negative electrode material having an extremely large capacity can be obtained by regulating W. Furthermore, it has been found that such a carbonaceous material is produced by firing a carbon precursor in an atmosphere in which volatile components generated during carbonization are removed to the outside of the reaction system.

The negative electrode material of the present invention was completed on the basis of such findings, is a non-graphitizable carbon material obtained by firing a carbon precursor, and has an X-ray diffraction spectrum of (002 ) Diffraction peaks derived from crystal lattice planes and (0
02) The weight ratio Ps of carbon having a laminated structure obtained from the X-ray diffraction spectrum on the lower angle side from the diffraction peak derived from the crystal lattice plane is smaller than 0.59 or the stacking index SI is smaller than 0.76. It is what

Of the X-ray diffraction spectrum, (00
2) The average number of laminated layers n _ave of the laminated structure portion obtained from the X-ray diffraction spectrum on the lower angle side of the diffraction peaks derived from the crystal lattice planes and the diffraction peak derived from the (002) crystal lattice planes is smaller than 2.46 It is what Furthermore, it is a non-graphitizable carbon material obtained by firing a carbon precursor, the firing temperature being T ° C., and the Raman spectrum being 1
When the full width at half maximum of the peak appearing in the vicinity of 340 cm ⁻¹ is HW, the condition is HW> 138-0.06 · T.

Further, in the method for producing a negative electrode material of the present invention, a carbon precursor which becomes non-graphitizable carbon when fired is carbon precursor 1
The heat treatment is performed at a temperature of 600 ° C. or higher in an inert gas atmosphere having a flow rate of 0.1 ml / min or more per gram. Further, the present invention is characterized in that a carbon precursor which becomes non-graphitizable carbon by firing is heat-treated at a temperature of 600 ° C. or higher in an atmosphere of a pressure of 50 kPa or lower.

Further, when heat treating the carbon precursor,
The contact area of the carbon precursor with the atmosphere is 10 per kg.
It is characterized in that they are placed in layers so as to have a size of cm ² or more. On the other hand, the non-aqueous electrolyte secondary battery of the present invention,
The non-graphitizable carbon comprises a negative electrode containing non-graphitizable carbon that can be doped or dedoped with lithium ions, a positive electrode containing a lithium composite oxide as a positive electrode active material, and a non-aqueous electrolyte. It is a non-graphitizable carbon obtained by calcination of, from the X-ray diffraction spectrum of the (002) crystal lattice plane-derived diffraction peak and the X-ray diffraction spectrum at a lower angle side than the (002) crystal lattice plane-derived diffraction peak. The weight ratio Ps of the carbon having the required laminated structure is smaller than 0.59 or the stacking index SI is smaller than 0.76. Further, the non-graphitizable carbon is a laminated structure obtained from the X-ray diffraction spectrum of the diffraction peak derived from the (002) crystal lattice plane and the X-ray diffraction spectrum at a lower angle side than the diffraction peak derived from the (002) crystal lattice plane. The average stacking number n _{ave of the part} is 2.46.
It is characterized by being smaller. Furthermore, the negative electrode is a non-aqueous electrolyte secondary battery containing non-graphitizable carbon obtained by firing a carbon precursor, wherein the non-graphitizable carbon has a firing temperature of T ° C. and a Raman spectrum of 1340 cm.
It is characterized by satisfying the condition of HW> 138-0.06 · T, where HW is the full width at half maximum of the peak appearing near ^-1 .

In the present invention, in order to obtain a negative electrode material having a large lithium doping amount, a carbon having a laminated structure, which is a parameter reflecting the ratio of a portion where carbon atoms have a laminated structure in the non-graphitizable carbon material, is used. A non-graphitizable carbon material in which the atomic weight ratio Ps, the stacking index SI, and the average number of stacked layers n _ave satisfy the following conditions is used as the negative electrode material.

Ps <0.59 SI <0.76 n _ave <2.46

That is, the non-graphitizable carbon material is 300
It means a carbon material which does not easily graphitize even after heat treatment at a high temperature such as 0 ° C. Here, the carbon material having a d ₀₀₂ value of 3.40 Å or more after the heat treatment at 2600 ° C. is meant.

Such a non-graphitizable carbon material is composed of a laminated structure portion in which carbon atoms have a laminated structure and a non-laminated structure portion. Here, when the non-graphitizable carbon material is used as the negative electrode material, lithium is doped not only between the carbon layers of the laminated structure portion but also in the minute voids of the disordered carbon layer of the non-laminated structure portion. It is considered to be one. If the volume is too large among the minute voids, lithium will not be able to stay in it and will not contribute to the doping of lithium. Contribute. Then, in the case where many such minute voids are present, a lithium doping amount far exceeding the theoretical lithium doping amount of 372 mAh / g obtained assuming that lithium is doped only between the carbon layers is obtained. You can

Such micro voids in the non-laminated structure portion are
Assuming that the density of the non-graphitizable carbon material is substantially constant,
The larger the proportion of the non-laminated structure portion, in other words, the smaller the proportion of the laminated structure portion, the larger the number of them.

Parameters, Ps, SI, which reflect the ratio of the laminated structure portion proposed as the negative electrode material in the present invention,
The non-graphitizable carbon material in which n _ave satisfies the above conditions is a non-graphitizable carbon material having a small proportion of the laminated structure portion, and has many fine voids in the non-laminated structure portion. Therefore, the large number of minute voids effectively contributes to the doping of lithium, and a large lithium doping amount can be obtained.

Here, the parameters reflecting the proportion of the laminated structure portion, Ps, SI, and n _ave are the diffraction peaks derived from the (002) crystal lattice plane and (of the X-ray diffraction spectrum of the non-graphitizable carbon material. 002) It is determined by processing the data obtained from the spectrum on the lower angle side of the diffraction peak derived from the crystal lattice plane by a predetermined procedure.

As a data processing method for obtaining the above parameters, the R. E, Franklin [Acta
Cryst. , 3, 107 (1950)], and H. P. Klug and L.K. E. Alexande
r, X-ray diffraction Proce
dures, p. 793 (John Wiley an
d Sons, Inc) has a method partially described in detail. This method is described in Shiraishi, Sanada, The Chemical Society of Japan 197
6, No. 1, p. 153, Ogawa, Kobayashi, Carbon 198
5, No. 120, p. 28, M.M. Shirash
i, K. Kobayashi, Bulletin of
Chemical Society of Japan
n, 46, 2575, (1973), etc., and is widely recognized.

In the present invention, SI, Ps and _nave are
The method is based on the method described in the above-mentioned document, but is obtained by a simplified method which is partially simplified so that it can be performed more easily. The data processing procedure of the above simple method will be described below.

(1) First, the X-ray diffraction spectrum of the non-graphitizable carbon material sample for which SI, Ps, and _nave are to be determined is observed. For this X-ray diffraction spectrum, the diffraction intensity I
The correction is performed by dividing (θ) by the square of the deflection factor, the absorption factor, and the atomic scattering factor obtained by the equations 1 and 2. The atomic scattering factor is a function of sin θ / λ,
international Tables for X
-Ray Crystallography, vol.
IV, p71 (The Kynoch Press, 1
The approximation for carbon atoms not in the valence state described in 974) is used. The diffraction intensity I (θ) is
Either the X-ray count number per second or the X-ray count number may be used, and the intensity is arbitrary.

[0023]

[Equation 1]

[0024]

[Equation 2]

(2) The curve Icorr (θ) obtained by correcting the X-ray diffraction spectrum is shown in FIG. As can be seen from FIG. 1, the curve Icorr (θ) has a minimum value near 2θ = about 36 °. This minimum value is Ia, (00
2) The peak intensity of the peak derived from the crystal lattice plane is defined as Im. Before obtaining Im and Ia, in order to avoid the influence of noise in the signal, it is preferable to perform smoothing processing in advance for about 15 to 35 points in the range of 2θ = 15 ° to 38 °. Then, the SI value is obtained by substituting the thus obtained Im and Ia into the equation shown in Formula 3.

[0026]

[Equation 3]

(3) On the other hand, the minimum value Ia is subtracted from the curve Icorr (θ) which has not been subjected to smoothing processing, and sin θ is further multiplied to obtain the intensity F (θ). The curve F (θ) thus obtained is shown in FIG.

(4) The Patterson function is obtained by substituting the obtained curve F (θ) into the equation shown in Formula 4.

[0029]

[Equation 4]

The equation (4) is an ordinary Fourier transform equation ∫Fcos (2 · π · u · s) · ds (where S = 2 ·
sin θ / λ) is replaced by the summation formula for θ. The obtained Patterson function curve is shown in FIG. In this way, the conversion range of the Patterson function to the real space is wide until the reference is sufficiently attenuated. Then, the point u giving the minimum value of this Patterson function curve is set to T ₁ , T ₂ from the smaller one.
.... defined as _{T n,} obtains _{T n,} T n _{+ 1} between the straight line and the Patterson function surround area P a (n), respectively.

(5) The weight ratio of the carbon atoms constituting the laminated structure composed of n carbon layers among the carbon atoms having the laminated structure in the non-graphitizable carbon material is set to several by using this P (n). It is calculated by the formula shown below.

[0032]

[Equation 5]

The calculation of f (n) shown in Equation 5 is
The process is performed up to n, which is one smaller than n when the f (n) value first becomes 0 or becomes negative. Then, using the obtained f (n), n _ave is obtained by the equation shown in Expression 6.

[0034]

[Equation 6]

(6) Next, the interplanar spacing d ₀₀₂ of the (002) crystal lattice planes is obtained as follows. That is, about 15 to 35 points of smoothing treatment are applied to the diffraction peaks derived from the (002) crystal lattice plane of the X-ray diffraction spectrum observed in (1). The curve I (θ) obtained by smoothing the X-ray diffraction spectrum is shown in FIG. Then, as shown in FIG. 4, a baseline is drawn to the diffraction peak of this curve I (θ), and the portion between the diffraction peak and the contact point between the baseline and the portion surrounded by the baseline and the diffraction peak is integrated. 2θ that divides this integrated intensity into two is Br
Substituting into the agg equation yields d ₀₀₂ .

(7) Using the values of n _ave , SI and d ₀₀₂ obtained as described above, the weight ratio Ps of the carbon atoms having the laminated structure in the carbon material is obtained from the equation shown in Formula 7. To be

[0037]

[Equation 7]

The data processing procedure for _obtaining SI, n _ave and Ps has been described above. Of these, SI is
In the above-mentioned data processing procedure, it is obtained by a method called transmission method, but it is not always necessary to obtain it by this method, and it is also possible to obtain it by correcting it with an appropriate absorption factor using a reflection method that is usually used. it can. Further, it is possible to derive a parameter that correlates with SI even though it includes many errors from the values corresponding to Im and Ia of the I (θ) curve before correction.

SI, n _ave , obtained in this way,
The non-graphitizable carbon material in which Ps satisfies a predetermined condition exhibits a high lithium doping amount. Further, in the present invention,
A non-graphitizable carbon material satisfying the condition that the half-value full width HW of the peak appearing near 1340 cm ^{−1 in} Raman spectrum is HW> 138-0.06 · T is also used as the negative electrode material.

That is, when the Raman spectrum of the non-graphitizable carbon material was observed, it was around 1340 cm ⁻¹ and 15
A peak is seen near 80 cm ^-1 . The peak near 1580 cm ^-1 is derived from the graphite structure in which carbon atoms are strongly bonded to each other, that is, the above-mentioned laminated structure portion. On the other hand, 1
The peak near 340 cm ⁻¹ is derived from the above-mentioned non-laminated structure portion, which is a phase having less symmetry than the graphite structure in which carbon atoms are weakly bonded to each other. This 1340 cm ^-1
The half-value half-width HW of the nearby peak reflects the variation in the bonding state between carbon atoms in the non-stacked structure portion.

Then, this half-value half-width HW is 138-0.
When it is larger than 06 · T, it is presumed that the carbon atoms in the non-laminated structure part have a reasonably large variation, and have many fine pores that contribute to lithium doping.
A large lithium doping amount can be obtained.

The full width at half maximum of the peak near 1340 cm ^-1 is half the value usually called the full width at half maximum. That is, a baseline is drawn on the peak waveform of the fitted Raman spectrum, and a straight line is drawn parallel to the baseline at a point of 1/2 of the intensity from the peak top to this baseline. The intersections of this peak waveform and the straight line are defined as points A and B, and the horizontal axis corresponding to these points A and B is read. The difference between the readings on the horizontal axis corresponding to the points A and B is the half-value width, and a half value of this half-value width is the half-value half-width.

Such a non-graphitizable carbon material can be obtained by firing the carbon precursors exemplified below.

That is, as the precursor of the above-mentioned non-graphitizable carbon, one in which a functional group containing oxygen is introduced into petroleum pitch,
Alternatively, a carbon material or the like in which solid-phase carbonization progresses via a thermosetting resin may be used.

For example, the petroleum pitch is distilled (vacuum distillation, atmospheric distillation, steam distillation), thermal polycondensation, extraction from tars, asphalt and the like obtained by high temperature pyrolysis of coal tar, ethylene bottom oil, crude oil and the like. , Chemical polycondensation and the like. At this time, the H / C atomic ratio of the petroleum pitch needs to be 0.6 to 0.8 in order to make the non-graphitizable carbon.

The specific means for introducing a functional group containing oxygen into these petroleum pitches is not limited, but for example, a wet method using an aqueous solution of nitric acid, mixed acid, sulfuric acid or hypochlorous acid, or an oxidizing gas (air, oxygen). ), A reaction with a solid reagent such as sulfur, ammonium nitrate, ammonium persulfate, ferric chloride and the like.

The oxygen content is not particularly limited, but is preferably 3 as shown in JP-A-3-252053.
% Or more, more preferably 5% or more. This oxygen content affects the crystal structure of the finally produced carbonaceous material, and when the oxygen content is in this range (002)
The interplanar spacing d ₀₀₂ is 3.70 Å or more, the exothermic peak does not occur at 700 ° C. or more in the differential thermal analysis (DTA) in the air flow, and the negative electrode capacity becomes large.

On the other hand, as the organic material serving as the precursor, phenol resin, acrylic resin, vinyl halide resin,
A conjugated resin such as a polyimide resin, a polyamide-imide resin, a polyamide resin, polyacetylene, or poly (p-phenylene), cellulose, a derivative thereof, or any organic polymer compound can be used. In addition, naphthalene, phenanthrene, anthracene, triphenylene,
Fused polycyclic hydrocarbon compounds such as pyrene, perylene, pentaphene, and pentacene, other derivatives (for example, carboxylic acids, carboxylic acid anhydrides, carboxylic acid imides, etc.), various pitches and acenes containing a mixture of each compound as a main component. Fused heterocyclic compounds such as naphthalene, indole, isoindole, quinoline, isoquinoline, quinoxaline, phthalazine, carbazole, acridine, phenazine and phenanthridine, and their derivatives can also be used. Furan resins composed of furfuryl alcohol or furfural homopolymers and copolymers are also particularly preferable.

Among the above organic materials, those which undergo liquid phase carbonization with heat treatment give easily graphitized carbon. Such an organic material may be infusibilized so as to undergo solid-phase carbonization. In other words, it is sufficient to devise such that intermolecular crosslinking reaction starts at a temperature lower than the start of melting, and for example, introducing an oxygen-containing group in the same manner as in the above petroleum pitch, adding chlorine gas or sulfur. Or a catalyst that accelerates the crosslinking reaction is present.

Although the carbonaceous material can be obtained by firing the carbon precursors exemplified above, the firing atmosphere for firing the carbon precursor is important for obtaining the carbonaceous material having a large lithium doping amount. .

That is, in the present invention, the firing of the carbon precursor is performed in an inert gas atmosphere having a flow rate of 0.1 ml / min or more per 1 g of the carbon precursor, or in an atmosphere having a pressure of 50 kPa or less. When the firing of the carbon precursor is performed in an inert gas atmosphere with a flow rate of 0.1 ml / min or more per 1 g of the carbon precursor, the volatile components are removed by the flow of the inert gas. On the other hand, if the firing of the carbon precursor is performed in a low pressure atmosphere having a pressure of 50 kPa or less, diffusion and desorption of volatile components from the carbon precursor are promoted, and the volatile components are efficiently removed.
Thus, when the carbon precursor is fired in an atmosphere in which volatile components generated by carbonization are removed from the outside of the reaction system, carbonization proceeds smoothly and a carbonaceous material having a large lithium doping amount is obtained. Will be done.

First, when the carbon precursor is fired in an inert gas atmosphere at a flow rate of 0.1 ml / min or more per 1 g of the carbon precursor, the inert gas means 900 ° C. to 150 ° C.
It is a gas that does not react with carbonaceous materials at a carbonization temperature of 0 ° C. For example, a gas containing nitrogen, argon, or a mixed gas thereof as a main component is used.

At this time, the ease with which the volatile components escape is dependent not only on the flow rate of the atmosphere but also on the amount of carbon precursor used for carbonization. Therefore, here, the flow rate of the atmosphere is
It is defined as the flow rate per unit weight of carbon precursor. The capacity of the negative electrode is improved when the flow rate per 1 g of the carbon precursor is 0.1 ml / min or more.

The amount of the carbon precursor is the total amount in the furnace in the case of a batch type carbonization furnace, and preferably 800 ° C. in the case of a continuous type carbonization furnace in which the carbonaceous material is taken out over time.
The above more preferably refers to the amount of the carbon precursor heated to a temperature of 700 ° C. or more.

The flow rate of the inert atmosphere is preferably 8
The amount is set so that the carbon precursor heated to 00 ° C. or higher, more preferably 700 ° C. or higher is touched and discharged to the outside of the carbonization furnace.
Therefore, the flow of an inert atmosphere for the purpose of replacing the atmosphere in the system before the temperature of the carbonization furnace or the carbon precursor is raised to preferably 800 ° C. or higher, more preferably 700 ° C. or higher is not included in the present invention. .

In this case, if the contact area with the atmosphere per 1 kg of the carbon precursor is 10 cm ² or more in the rough surface shape, the carbon precursor is likely to come into contact with the inert gas and the volatile component is more efficient. It is removed well, and the progress of carbonization becomes smoother. However, the contact area in the rough surface shape here does not include minute irregularities due to disorder of the material surface or minute specific surface area in the particles.

The contact area of the carbon precursor is widened, for example, by dividing the carbon precursor and placing it on multiple stages, or by stirring (in this case, the specific surface area of the carbon precursor becomes the area in contact with the atmosphere). be able to.

On the other hand, when the carbon precursor is fired in a low pressure atmosphere having a pressure of 50 kPa or less, the pressure in the atmosphere is maintained at 50 kPa or less at the ultimate temperature of carbonization or at one point during the temperature raising process. Just go. The exhaust in the carbonization furnace may be performed before the carbonization furnace or the carbon precursor is heated, during the temperature rising process thereof, or the reached temperature holding time.

In any of the above atmospheres, the heating method of the carbonization furnace is not particularly limited, and induction heating, resistance heating or the like may be used.

The ultimate temperature and the rate of temperature rise during carbonization are not particularly limited. For example, in an inert atmosphere, 300-70
After calcination at 0 ° C, the temperature rising rate is 1 ° C / in an inert atmosphere.
The main calcination may be performed under conditions such that the ultimate temperature is 900 to 1500 ° C. and the holding temperature is 0 to 5 hours. Of course, the calcination operation may be omitted in some cases.

Further, the carbonaceous material thus obtained is crushed and classified to be used as a negative electrode material, but this crushing may be performed before carbonization, after carbonization, or after firing.

The negative electrode made of the negative electrode material prepared as described above is housed in the battery can together with the positive electrode and the electrolytic solution and functions as the negative electrode of the battery.

Here, the non-aqueous electrolyte secondary battery of the present invention is
Since the aim is to achieve a high capacity, as the positive electrode, Li in a steady state (for example, after repeating charging / discharging about 5 times) is equivalent to 250 mAh or more of Li corresponding to the charging / discharging capacity per 1 g of the negative electrode carbonaceous material. Required to include, 300mA
It is preferable to include Li in a charge / discharge capacity equivalent to h or more, and more preferably to include a charge / discharge capacity equivalent to 350 mAh or more.

It is not always necessary that Li is entirely supplied from the positive electrode material, and the point is that the Li carbon material 1 is contained in the battery system.
It suffices that Li corresponding to a charge / discharge capacity of 250 mAh or more exists per g. Further, the amount of Li will be determined by measuring the discharge capacity of the battery.

As the positive electrode material constituting the above positive electrode, for example, a composite metal oxide represented by the general formula LiMO ₂ (where M represents at least one of Co and Ni) and Li
An intercalation compound containing is preferable, and particularly when LiCoO ₂ is used, good characteristics can be obtained.

The non-aqueous electrolytic solution is prepared by appropriately combining an organic solvent and an electrolyte, and any of these organic solvents and electrolytes can be used as long as they are used in this type of battery. For example, propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, 1,2-
Dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-
1,3-dioxolane, diethyl ether, sulfolane, methylsulfolane, acetonitrile, propionitrile, anisole, acetic acid ester, butyric acid ester, propionic acid ester and the like.

As the electrolyte, LiClO ₄ , LiAs
F ₆ , LiPF ₆ , LiBF ₄ , LiB (C
₆ H ₅ ) ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, L
iCl, LiBr, etc.

[0068]

[Function] The weight ratio Ps of the carbon atoms having the laminated structure, the stacking index SI, and the average lamination of the laminated structures, which are parameters reflecting the ratio of the portion where the carbon atoms have the laminated structure in the non-graphitizable carbon material. The non-graphitizable carbon material whose number n _ave satisfies a predetermined condition is assumed to be doped with lithium only between the carbon layers of the laminated structure portion when used as a negative electrode material of a lithium non-aqueous electrolyte battery. It has a lithium doping amount far exceeding the required theoretical lithium doping amount of 372 mAh / g. It is considered that this is because the non-graphitizable carbon material having the above-mentioned parameters satisfying a predetermined condition has a large number of minute voids as sites to be doped with lithium in addition to the carbon layer of the laminated structure portion.

Such a non-graphitizable carbon material is prepared by firing a carbon precursor which becomes non-graphitizable carbon in an inert gas atmosphere at a flow rate of 0.1 ml / min or more per 1 g of carbon precursor, or at a pressure of 50 kPa. Temperature 60 in the following atmosphere
It is obtained by carbonization in an atmosphere in which volatile components generated during carbonization such as heat treatment at 0 ° C. or higher are removed outside the reaction system. This is for the following reason.

That is, when the carbon precursor is fired,
Low-molecular paraffin, olefins, and low-molecular aromatics volatilize from around 00 ° C, and carbon dioxide, methane, and
Carbon monoxide and hydrogen at higher temperatures volatilize. Volatilization of low molecular weight compounds at low temperatures is due to carbon-carbon single bond in carbonaceous materials,
Alternatively, due to the cleavage of carbon-oxygen bond, the carbonaceous material forms an olefin or aromatic ring having a more stable double bond. At higher temperatures, hydrogen is desorbed along with the cleavage of carbon-hydrogen bonds, the polymerization proceeds, and the aromatic ring grows.

Removal of the volatile components from the reaction system during the carbonization process promotes the formation of voids along the diffusion path of the volatile components in the carbon material particles. It is unclear whether such voids form open pores or closed pores, but it is assumed that the voids due to the diffusion of molecules have a minute volume, and contribute to the capacity appropriately. It is thought to have a structure that

[0072]

EXAMPLES The present invention will be described below based on specific experimental results.

Example 1 First, a carbonaceous material is manufactured as follows.

Petroleum pitch (H / C atomic ratio 0.6-0.
8) was oxidized to prepare a carbon precursor having an oxygen content of 15.4%. Then, the carbon precursor was added to
Carbonized at 0 ° C for 5 hours. Then, the beads obtained by carbonization were crushed by a mill to obtain a carbonization raw material, and about 10 g of this was charged into a crucible. 10 prepared in this crucible
g of carbonized raw material in an electric furnace under a nitrogen stream of 10 l / min,
Firing was performed under the conditions that the temperature rising rate was 5 ° C./min, the ultimate temperature was 1100 ° C., and the holding time was 1 hour to obtain a carbonaceous material. At this time, the layer thickness of the carbonization raw material in the crucible was about 30 mm, and the contact area with the nitrogen stream was -7 cm ² .

After cooling the obtained carbonaceous material, it was ground in a mortar and classified to 38 μm or less with a mesh.

Raman scattering spectrum and X-ray diffraction spectrum of this carbonaceous material were measured. Then, the half-value half-width of the peak appearing near 1340 cm ⁻¹ in the Raman scattering spectrum is obtained, and the data obtained from the X-ray diffraction spectrum is subjected to data processing by a predetermined procedure to obtain a weight ratio Ps of carbon atoms having a laminated structure, Stacking index SI, average number of stacked layers n
I asked for _ave .

In the Raman scattering spectrum, 13
The full width at half maximum of the peak appearing in the vicinity of 40 cm ^-1 was determined as follows.

First, a carbonaceous material powder sample was irradiated with an Ar ⁺ laser having a wavelength of 514.5 nm and an irradiation power of 200 mW with an incident beam diameter of 1 mmφ to collect pseudo backscattered scattered light and collect this. Raman spectra are measured by splitting the light with a spectrometer. In this method, the beam diameter of the Ar ⁺ laser for obtaining scattered light is 1 m.
Since it is as large as mφ, the measured Raman scattering spectrum is a scattering average of many carbon material particles existing within the beam diameter. Therefore, the Raman spectrum can be measured with high reproducibility and accuracy.

The spectroscope is equipped with JOBIN-YVON.
A U-1000 double monochromator manufactured by the company was used. Slit width is 400-800-800-400μ
m.

Then, the Raman scattering spectrum is measured a total of four times in the same manner except that the irradiation position is shifted, and the fitting processing is performed for each Raman scattering spectrum. Then, the half-value half-width of the peak near 1340 cm ^{−1 was} obtained for each spectrum, and the average value of the four half-value half-width data was calculated.

The X-ray diffraction spectrum was measured under the following conditions. X-ray diffraction measurement condition X-ray: CuKα ray (wavelength λ = 1.54
18Å) Measuring device: manufactured by Rigaku Co., Ltd., trade name RAD-II
IB Applied current and applied voltage: 40kV, 30mA Solar slit width: 0.5 ° Divergence slit width: 0.5 ° Reference slit width: 0.15 ° Sampling interval: 0.05 ° Scanning speed: 1 ° / min Scanning width : 1 ° to 38 ° at 2θ Using a graphite monochromator (diffraction angle 2α of monochromator: about 26.6 °) Sample filling method: 5 mm × 18 mm punched on a SUS plate having a thickness of 0.5 mm Sample thickness 0.5 mm in the opening
Filled with

HW, P obtained by the above method and conditions
Table 1 shows s, SI and n _ave .

A negative electrode of a coin-type battery was prepared using the above carbonaceous material as a negative electrode material, and the negative electrode capacity of the carbonaceous material was measured.

First, in order to form a negative electrode, the carbonaceous material was preheated in an argon atmosphere under the conditions of a temperature rising rate of about 30 ° C./minute, an ultimate temperature of 600 ° C., and an ultimate temperature holding time of 1 hour. (Note that this heat treatment was performed immediately before the adjustment of the negative electrode mix shown below.) Next, polyvinylidene fluoride in an amount equivalent to 10% by weight was added to this carbonaceous material,
A negative electrode mix was prepared by mixing and drying dimethylformamide as a solvent.

Negative electrode mix 37 thus prepared
1 mg diameter by kneading mg with nickel mesh which is a current collector
A negative electrode was formed by molding into a pellet of 5.5 mm. Then, the produced negative electrode was incorporated into a coin-type battery having the following structure, and charged and discharged at 1 mA (current density 0.53 mA / cm ² ) to measure the discharge capacity per 1 g of the negative electrode carbonaceous material. The structure and charge / discharge conditions of the coin-type battery are shown below.

Structure of coin-type battery Coin-type battery Dimensions: diameter 20 mm, thickness 2.5 mm Positive electrode: Li metal separator: Porous membrane (polypropylene) Electrolyte: Mixed solvent of propylene carbonate and dimethoxyethane (volume ratio: 1 1) to LiClO ₄
Dissolved at a ratio of 1 mol / 1. Current collector: Copper foil

Charging / Discharging Conditions Charging: 1 hour of energization and 2 hours of rest are repeated, and the plot of the minus half power of the rest time at each rest versus rest voltage is swept to infinity to find the equilibrium potential by the charging capacity. Estimated (intermittent charge / discharge method). Charging was completed when this equilibrium potential reached 2 mV against lithium.

Discharge: Similar to charging, 1 hour of energization and 2 hours of rest were repeated, and discharging was terminated when the battery voltage fell below 1.5 V in the energized state. Since the charge / discharge capacity estimated by this method is based on the equilibrium potential, it reflects the characteristics peculiar to the material.

Negative electrode of carbonaceous material measured in this way
The capacity is the above HW, SI, Ps, n _aveTable 1 together with
Show.

[0090]

[Table 1]

Comparative Example 1 A carbonaceous material was produced in the same manner as in Example 1 except that the carbonization raw material was not fired in a nitrogen stream. The temperatures reached during firing are 1100 ° C, 1200 ° C, 1300 ° C.
I changed it.

Then, the Raman spectrum and the X-ray diffraction spectrum of the obtained carbonaceous material are measured, the half width at half maximum of the peak appearing near 1340 cm ⁻¹ in the Raman scattering spectrum is obtained, and further obtained from the X-ray diffraction spectrum. By subjecting the data to predetermined data processing, the weight ratio Ps of carbon atoms having a laminated structure, the stacking index SI, and the average number of laminated layers n _ave in the laminated structure portion were obtained. Further, a coin-type battery was produced using the obtained carbonaceous material as a negative electrode material, and the produced coin-type battery was charged and discharged under an energization condition of 1 mA, and the discharge capacity per 1 g of the negative electrode carbonaceous material was measured. Table 2 shows the measurement results of HW, Ps, SI, _nave and the negative electrode capacity.

[0093]

[Table 2]

As can be seen by comparing Table 1 and Table 2, the carbonaceous material produced in Example 1 was HW, Ps, SI, n.
_ave is a predetermined condition (HW> 138-0.06 · T, Ps
<0.59, SI <0.76, n _ave <2.46) are satisfied, and a large negative electrode capacity of 378 mAh is obtained. In contrast, the carbonaceous material produced in Comparative Example 1 Both HW, Ps, SI, n _ave does not satisfy the predetermined condition, the negative electrode capacity is smaller than that of the carbonaceous material of Example 1 It has become a thing.

Therefore, from this fact, it is recommended to perform the firing of the carbon precursor in the atmosphere of inert gas such as HW, Ps and S.
It was found that I and n _ave are effective in obtaining a carbonaceous material satisfying predetermined conditions and having a large negative electrode capacity.

Example 2 A carbonaceous material was produced in the same manner as in Example 1 except that the amount of the carbonization raw material charged into the crucible was 1 g when the carbonization raw material was fired.

Then, Raman spectrum and X-ray diffraction spectrum of the obtained carbonaceous material are measured, a half-value half width of a peak appearing in the vicinity of 1340 cm ^{-1 in} Raman scattering spectrum is obtained, and further obtained from the X-ray diffraction spectrum. By subjecting the data to predetermined data processing, the weight ratio Ps of carbon atoms having a laminated structure, the stacking index SI, and the average number of laminated layers n _ave in the laminated structure portion were obtained. Further, a coin-type battery was produced using the obtained carbonaceous material as a negative electrode material, and the produced coin-type battery was charged and discharged under an energization condition of 1 mA, and the discharge capacity per 1 g of the negative electrode carbonaceous material was measured. Table 3 shows the measurement results of HW, Ps, SI, _nave and the negative electrode capacity.

[0098]

[Table 3]

As can be seen from Table 3, in the carbonaceous material produced by the above method, HW, Ps, SI and n _ave all satisfy the predetermined conditions, and the negative electrode capacity is 442 mAh.
/ G, which is a larger value than in the case of the carbonaceous material of Example 1.

From the above, in the carbonaceous material obtained by firing the carbon precursor in the atmosphere of the inert gas, the negative electrode capacity is the carbon precursor which is fired together with the flow rate of the inert gas when firing the carbon precursor. Carbon precursor 1 depending on the amount of
It was found that the larger the flow rate of inert gas per g, the larger the negative electrode capacity.

Example 3 A carbonaceous material was produced in the same manner as in Example 1 except that an alumina boat was used instead of the crucible and the carbonization raw material was placed on the alumina boat when the carbonization raw material was fired. did. The layer thickness of the carbonization raw material on the alumina boat was about 10 mm, and the contact area with the nitrogen stream was about 300.
It was cm ² .

Then, Raman spectrum and X-ray diffraction spectrum of the obtained carbonaceous material are measured, the half-width at half maximum of the peak appearing near 1340 cm ^-1 in the Raman scattering spectrum is obtained, and further obtained from the X-ray diffraction spectrum. By subjecting the data to predetermined data processing, the weight ratio Ps of carbon atoms having a laminated structure, the stacking index SI, and the average number of laminated layers n _ave in the laminated structure portion were obtained. Further, a coin-type battery was produced using the obtained carbonaceous material as a negative electrode material, and the produced coin-type battery was charged and discharged under an energization condition of 1 mA, and the discharge capacity per 1 g of the negative electrode carbonaceous material was measured. Table 4 shows the measurement results of HW, Ps, SI, _nave and the negative electrode capacity.

[0103]

[Table 4]

As can be seen from Table 4, the carbonaceous material produced by the above method has HW, Ps, SI and n _ave all satisfying predetermined conditions, and has a negative electrode capacity of 432 mAh.
/ G, which is a larger value than the case of the carbonaceous material of Example 1.

From the above, in the carbonaceous material obtained by firing the carbon precursor in an inert gas atmosphere, the negative electrode capacity is the layer thickness of the carbon precursor when firing the carbon precursor,
That is, depending on the contact area, it was found that the smaller the layer thickness of the carbon precursor and the larger the contact area, the larger the negative electrode capacity. This is because the thinner the carbon precursor layer is, the better the volatile component escapes.

Example 4 When firing a carbonized raw material, about 10 g of the carbonized raw material was charged into a crucible, and while maintaining the pressure in the electric furnace at about 20 kPa, the temperature rising rate was 5 ° C./min, the reached temperature was 1100 ° C. 1
A carbonaceous material was produced in the same manner as in Example 1 except that firing was carried out under the conditions of 200 ° C., 1300 ° C., and a holding time of 1 hour.

Then, Raman spectrum and X-ray diffraction spectrum of the obtained carbonaceous material are measured, the half width at half maximum of the peak appearing at around 1340 cm ^{-1 in} Raman scattering spectrum is obtained, and further obtained from the X-ray diffraction spectrum. By subjecting the data to predetermined data processing, the weight ratio Ps of carbon atoms having a laminated structure, the stacking index SI, and the average number of laminated layers n _ave in the laminated structure portion were obtained. Further, a coin-type battery was produced using the obtained carbonaceous material as a negative electrode material, and the produced coin-type battery was charged and discharged under an energization condition of 1 mA, and the discharge capacity per 1 g of the negative electrode carbonaceous material was measured. Table 5 shows the measurement results of HW, Ps, SI, _nave and the negative electrode capacity.

[0108]

[Table 5]

Comparative Example 2 When firing the carbonized raw material, the pressure in the electric furnace was set to 60 k.
A carbonaceous material was produced in the same manner as in Example 4 except that Pa was used.

Then, the Raman spectrum and the X-ray diffraction spectrum of the obtained carbonaceous material are measured, the half-width at half maximum of the peak appearing near 1340 cm ^-1 in the Raman scattering spectrum is obtained, and further obtained from the X-ray diffraction spectrum. By subjecting the data to predetermined data processing, the weight ratio Ps of carbon atoms having a laminated structure, the stacking index SI, and the average number of laminated layers n _ave in the laminated structure portion were obtained. Further, a coin-type battery was produced using the obtained carbonaceous material as a negative electrode material, and the produced coin-type battery was charged and discharged under an energization condition of 1 mA, and the discharge capacity per 1 g of the negative electrode carbonaceous material was measured.

As a result, HW of the carbonaceous material of Comparative Example 2,
The Ps, SI, _nave and the negative electrode capacity are about the same as those in Comparative Example 1, the above parameters do not satisfy the predetermined condition, and the negative electrode capacity is also small. On the other hand, in the carbonaceous material of Example 4, as can be seen from Table 4, HW, Ps, SI, and _nave satisfy the predetermined conditions, and compared with the carbonaceous material of Comparative Example 2. It has a much larger negative electrode capacity.

Therefore, from this fact, it is recommended to perform the firing of the carbon precursor under a low pressure atmosphere in HW, Ps, SI, n.
It was found that _ave is effective in obtaining a carbonaceous material satisfying predetermined conditions and having a large negative electrode capacity.

Example 5 A carbonaceous material was produced in the same manner as in Example 1 except that the carbonization raw material was fired as follows.

That is, about 10 g of the carbonized raw material was charged into a crucible and fired at 900 ° C. in a closed electric furnace. After cooling, about 10 g was charged again into the crucible, and the temperature in the electric furnace was maintained at about 20 kPa, and the temperature was raised at 5 ° C./min, the reached temperature was 1100 ° C., and the firing time was 1 hour. A carbonaceous material was obtained.

Then, the Raman spectrum and the X-ray diffraction spectrum of the obtained carbonaceous material are measured, the half-width at half maximum of the peak appearing near 1340 cm ^-1 in the Raman scattering spectrum is obtained, and further obtained from the X-ray diffraction spectrum. By subjecting the data to predetermined data processing, the weight ratio Ps of carbon atoms having a laminated structure, the stacking index SI, and the average number of laminated layers n _ave in the laminated structure portion were obtained. Further, a coin-type battery was produced using the obtained carbonaceous material as a negative electrode material, and the produced coin-type battery was charged and discharged under an energization condition of 1 mA, and the discharge capacity per 1 g of the negative electrode carbonaceous material was measured.

As a result, HW, Ps, S of carbonaceous material
The I, n _ave and negative electrode capacities were similar to those of the carbonaceous material of Example 4. From this, when obtaining a carbonaceous material by firing the carbon precursor in a low-pressure atmosphere, the exhaust operation should be carried out before the carbonization furnace or the carbon precursor is heated, or their temperature raising process and the reached temperature holding time. Similarly HW, Ps, SI, n _ave be carried out either is found to carbonaceous materials with Komakekyoku capacity satisfies a predetermined condition is obtained.

Comparative Example 3 First, a carbonized raw material was produced in the same manner as in Example 1. About 10 g of the obtained carbonized raw material was charged into a crucible and fired at 900 ° C. in a closed electric furnace. After cooling, about 10 g was charged again into the crucible, and the temperature rising rate was 5 ° C./min in the closed electric furnace.
The carbonaceous material was obtained by firing at the ultimate temperature of 1100 ° C. and the holding time at the ultimate temperature of 1 hour.

For this carbonaceous material, the Raman spectrum and the X-ray diffraction spectrum were measured, the half-width at half maximum of the peak appearing near 1340 cm ⁻¹ in the Raman scattering spectrum was determined, and the data obtained from the X-ray diffraction spectrum was given a predetermined value. Weight ratio Ps of stacking carbon atoms and stacking index S
I, the average number of stacked layers n _ave of the stacked structure portion was determined. In addition, a coin-type battery was produced using the obtained carbonaceous material as a negative electrode material, and the produced coin-type battery was subjected to an energization condition 1
Charge / discharge was performed at mA, and the discharge capacity per 1 g of the negative electrode carbonaceous material was measured.

As a result, the carbonaceous materials HW, Ps, S
The I, _nave and the negative electrode capacity were similar to those of the carbonaceous material of Comparative Example 1. From this, it was found that when the carbon precursor is fired in a low pressure atmosphere to obtain a carbonaceous material, it is important that the pressure of the atmosphere is low at the ultimate temperature.

Example 6 Furfuryl alcohol resin was applied in an electric furnace at a pressure of 20 kP.
Temperature rising rate of 5 ° C / min and ultimate temperature of 12
The carbonaceous material was obtained by firing at a temperature of 00 ° C. and a holding time of 1 hour. After cooling the obtained carbonaceous material, it was pulverized with a mill and classified to 38 μm or less with a mesh.

The Raman spectrum and X-ray diffraction spectrum of this carbonaceous material were measured, and the half-width at half maximum of the peak appearing at around 1340 cm ^-1 in the Raman scattering spectrum was obtained, and the data obtained from the X-ray diffraction spectrum was used. By performing predetermined data processing, the weight ratio Ps of carbon atoms having a laminated structure, the stacking index SI, and the average number of laminated layers n _ave of the laminated structure portion were obtained. Further, a coin-type battery was produced using the obtained carbonaceous material as a negative electrode material, and the produced coin-type battery was charged and discharged under an energization condition of 1 mA, and the discharge capacity per 1 g of the negative electrode carbonaceous material was measured. Table 6 shows the measurement results of HW, Ps, SI, _nave and the negative electrode capacity.

[0122]

[Table 6]

Comparative Example 4 A carbonaceous material was produced in the same manner as in Example 6 except that the furfuryl alcohol resin was fired in a closed electric furnace.

Then, Raman spectrum and X-ray diffraction spectrum of the obtained carbonaceous material are measured, the half-width at half maximum of the peak appearing near 1340 cm ^{-1 in} Raman scattering spectrum is obtained, and further obtained from the X-ray diffraction spectrum. By subjecting the data to predetermined data processing, the weight ratio Ps of carbon atoms having a laminated structure, the stacking index SI, and the average number of laminated layers n _ave in the laminated structure portion were obtained. Further, a coin-type battery was produced using the obtained carbonaceous material as a negative electrode material, and the produced coin-type battery was charged and discharged under an energization condition of 1 mA, and the discharge capacity per 1 g of the negative electrode carbonaceous material was measured. Table 7 shows the measurement results of HW, Ps, SI, _nave and the negative electrode capacity.

[0125]

[Table 7]

As can be seen by comparing Tables 6 and 7, the carbonaceous material of Example 6 satisfies the predetermined conditions of HW, Ps, SI and n _{ave, and} is higher than that of the carbonaceous material of Comparative Example 4. Also has a large negative electrode capacity. On the other hand, in the carbonaceous material of Comparative Example 4, HW, Ps, SI, and _nave do not satisfy the predetermined conditions, and the negative electrode capacity is small.

From this, it is found that the present production method is effective also when an organic material which becomes non-graphitizable carbon by firing is used as the carbon precursor, as in the case of petroleum pitch into which a functional group containing oxygen is introduced. It was

[0128]

As is apparent from the above description, the negative electrode material of the present invention is a non-graphitizable carbon material obtained by firing a carbon precursor, and has an X-ray diffraction spectrum of (00
2) Weight ratio Ps of carbon having a laminated structure determined from the X-ray diffraction spectrum on the lower angle side of the diffraction peaks derived from the crystal lattice plane and the diffraction peak derived from the (002) crystal lattice plane, the stacking index SI, and the laminated structure portion Average stacking number n _ave and 1340c in Raman spectrum
Since the half-value half-width HW of the peak appearing in the vicinity of m ⁻¹ is regulated, when used as a negative electrode material of a lithium non-aqueous electrolyte battery, a high lithium doping amount far exceeding the theoretical value can be obtained.

Such a negative electrode material is prepared by firing a carbon precursor which becomes non-graphitizable carbon in an inert gas atmosphere at a flow rate of 0.1 ml / min or more per 1 g of the carbon precursor or at a pressure of 50 kPa or less. It is obtained by heat-treating at a temperature of 600 ° C. or higher in the above atmosphere, and does not require additional operations other than the conventional manufacturing operations such as addition of additives to the raw materials.
Therefore, it is advantageous in simplifying the manufacturing operation and reducing the cost, and its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing a curve Icorr (θ) obtained by correcting an X-ray diffraction spectrum of a non-graphitizable carbon material.

FIG. 2 is a characteristic diagram showing a curve F (θ) obtained by subtracting the minimum value Ia from the curve Icorr (θ) and then multiplying it by sin (θ).

FIG. 3 is a characteristic diagram showing a Patterson function curve obtained by Fourier transforming a curve F (θ).

FIG. 4 is a characteristic diagram showing a curve I (θ) obtained by smoothing an X-ray diffraction spectrum.

Front page continuation (72) Inventor Mio Nishi 6-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) Yoshihisa Gonno 6-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Incorporated (72) Inventor Masayuki Nagamine 2-22-3 Shibuya, Shibuya-ku, Tokyo Inside Sony Energy Tech Co., Ltd. (56) Reference JP-A-3-137010 (JP, A) JP-A-2- 66856 (JP, A) JP-A-58-93176 (JP, A) JP-A-62-76155 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01M 4/58 H01M 4 / 02-4/04 H01M 10/40

Claims (9)

(57) [Claims] 1. A non-graphitizable carbon material obtained by heat-treating a carbon precursor at a temperature of 600 ° C. or higher in an inert gas atmosphere at a flow rate of 0.1 ml / min or more per 1 g, which has an X-ray diffraction spectrum Among them, the weight ratio Ps of carbon having a laminated structure obtained from the X-ray diffraction spectrum on the lower side of the diffraction peak derived from the (002) crystal lattice plane and the diffraction peak derived from the (002) crystal lattice plane is smaller than 0.59. Alternatively, a negative electrode material having a stacking index SI smaller than 0.76. 2. The average lamination of the laminated structure part obtained from the diffraction peak derived from the (002) crystal lattice plane and the X-ray diffraction spectrum lower than the diffraction peak derived from the (002) crystal lattice plane in the X-ray diffraction spectrum. The number n _ave is 2.4
The negative electrode material according to claim 1, which is smaller than 6. 3. A non-graphitizable carbon material obtained by heat-treating a carbon precursor at a temperature of 600 ° C. or higher in an inert gas atmosphere with a flow rate of 0.1 ml / min or higher per 1 g, and a firing temperature of T ° C. , In Raman spectrum 1340 cm ⁻¹
A negative electrode material, which satisfies a condition of HW> 138-0.06 · T, where HW is a half width at half maximum of a peak appearing in the vicinity. 4. A carbon precursor, which becomes non-graphitizable carbon by firing, is heat-treated at a temperature of 600 ° C. or higher in an inert gas atmosphere at a flow rate of 0.1 ml / min or more per 1 g of the carbon precursor. Method for producing negative electrode material. 5. The method for producing a negative electrode material according to claim 4 , wherein the carbon precursor that becomes non-graphitizable carbon by firing is heat-treated in an atmosphere at a pressure of 50 kPa or less. 6. When the carbon precursor is heat-treated, the contact area of the carbon precursor with the atmosphere is 10 cm ² per 1 kg.
The method for producing a negative electrode material according to claim 4, wherein the layers are placed in a layered manner as described above. 7. A non-graphitizable carbon material comprising a negative electrode containing non-graphitizable carbon capable of being doped / dedoped with lithium ions, a positive electrode containing a lithium composite oxide as a positive electrode active material, and a non-aqueous electrolyte solution. Carbon is 0.1 ml per gram of carbon precursor
A non-graphitizable carbon obtained by heat treatment at a temperature of 600 ° C. or higher in an inert gas atmosphere with a flow rate of not less than 1 minute / minute, and a diffraction peak derived from a (002) crystal lattice plane and a (002) crystal in an X-ray diffraction spectrum. Non-characterized in that the weight ratio Ps of carbon having a laminated structure obtained from the X-ray diffraction spectrum on the lower angle side from the diffraction peak derived from the lattice plane is smaller than 0.59 or the stacking index SI is smaller than 0.76. Water electrolyte secondary battery. 8. The non-graphitizable carbon is obtained from an X-ray diffraction spectrum, which is derived from a diffraction peak derived from a (002) crystal lattice plane and an X-ray diffraction spectrum lower than a diffraction peak derived from a (002) crystal lattice plane. Average of laminated structure parts
The non-aqueous electrolyte secondary battery according to claim 7, wherein the number of stacked layers n _ave is smaller than 2.46. 9. The negative electrode contains 0.1 m of carbon precursor per 1 g of carbon precursor.
Temperature 600 ° C in an inert gas atmosphere with a flow rate of 1 / min or more
A non-aqueous electrolyte secondary battery containing non-graphitizable carbon obtained by the above heat treatment, wherein the non-graphitizable carbon has a half-value of a peak appearing in the vicinity of 1340 cm ^{−1 in} a Raman spectrum at a firing temperature of T ° C. A non-aqueous electrolyte secondary battery which satisfies the condition of HW> 138-0.06 · T when the half width is HW.