JP2019053960A - Carbon black and method for manufacturing the same - Google Patents

Abstract

To provide carbon black which can be as a conductive assistant of a nonaqueous electrolyte secondary battery having good cycle characteristics without increasing an internal resistance.SOLUTION: The carbon black is to be used as a conductive assistant of a nonaqueous electrolyte secondary battery having a positive electrode, a negative electrode and an electrolyte, of which the BET specific surface area is 300 m/g or more and 1500 m/g or less, the ratio of fluorine atoms to carbon atoms, namely F/C ratio is no less than 0.001 and less than 0.025, and the ratio of oxygen atoms to the carbon atoms, namely O/C ratio is no less than 0.1 and less than 0.2, where those are measured by XPS analysis.SELECTED DRAWING: None

Description

  The present invention relates to a carbon black used as a conductive aid for an electrode of a non-aqueous electrolyte secondary battery represented by a lithium battery and a production method thereof, a non-aqueous electrolyte secondary battery electrode containing the carbon black, a production method thereof, The present invention relates to a non-aqueous electrolyte secondary battery including an electrode.

  For electrodes such as a positive electrode and a negative electrode of a lithium battery, a composite electrode including a composite oxide as an active material, carbon black as a conductive additive, and a binder is used.

  In recent years, the number of electric vehicles employing lithium batteries has increased. One of the important characteristics of an automobile battery is an output characteristic indicating the amount of current that can be passed per unit time. If the output characteristics are inferior, the acceleration performance such as EV becomes poor and the vehicle is not used.

  One technique for improving the output characteristics is to reduce the electrode resistance by highly dispersing the conductive additive in the positive electrode throughout the positive electrode. Patent Document 1 discloses a method of dispersing a conductive additive by using a nitrogen-based surfactant. Patent Document 2 discloses a technique using a triazine derivative or the like as a dispersant.

  On the other hand, Patent Document 3 discloses a method for improving affinity with a matrix by subjecting carbon as a conductive additive to fluorine treatment. Patent Document 4 discloses a method of performing an oxidation treatment of carbon black by coexisting fluorine and oxygen in a predetermined ratio in order to improve the dispersibility of carbon black. Patent Document 5 discloses a method for producing a high-power and high-energy density lithium battery by using an electrode material in which a fluorine-treated carbon-based conductive material and an electrode active material are combined. Yes.

JP 2011-14457 A JP 2013-73724 A JP-A-60-191011 Japanese Patent Laid-Open No. 9-40881 Japanese Patent Laying-Open No. 2015-228290 JP-A-2006-9564

  However, according to Patent Document 6, the surfactant described in Patent Document 1 has a problem in that when lithium cobaltate used as a general positive electrode active material is used, decomposition occurs during battery reaction, resulting in poor cycle characteristics. It has been pointed out. In addition, it has been pointed out that the compound described in Patent Document 2 also has a problem in cycle characteristics because the dispersibility is insufficient and the oxidation stability is not always excellent.

  Patent Documents 3 and 4 describe that the dispersion state is improved by fluorination of a carbon-based material. However, the present inventors have described the method described in Patent Document 4, that is, fluorine and oxygen. When the carbon black was processed using the mixed gas and the electrode was produced using the resulting carbon black, the dispersibility of the carbon black was improved, but the internal resistance value of the electrode material increased and the output / energy increased. In both density and cycle characteristics, there were some cases where there was no change or performance degradation. This result is considered to indicate that, when carbon black is used as a conductive additive, only the dispersibility does not affect the battery performance.

From such a background, there has been a demand for an appropriate fluorine treatment method for obtaining carbon black suitable as a conductive aid for an electrode for a lithium ion battery.
Accordingly, an object of the present invention is to provide a carbon black that can be used as a conductive aid for a nonaqueous electrolyte secondary battery having good cycle characteristics without increasing internal resistance.
Another object of the present invention is to provide an electrode for a non-aqueous electrolyte secondary battery containing the carbon black.
Another object of the present invention is to provide a non-aqueous electrolyte secondary battery including the non-aqueous electrolyte secondary battery electrode.
Another object of the present invention is to provide a method for producing the carbon black.
Another object of the present invention is to provide a method for producing an electrode for a nonaqueous electrolyte secondary battery including the electrode for a nonaqueous electrolyte secondary battery.

  As a result of various studies to achieve the above-mentioned object, the present inventors have obtained the elements of fluorine and oxygen on the surface of fluorinated carbon black in order to obtain carbon black suitable as a conductive aid for the electrode for lithium ion batteries. It was found that the ratio needs to be managed within an appropriate range. The element ratio can be controlled by setting a fluorine concentration in a specific range and using a processing gas with the balance being an inert gas, and performing a post-treatment that makes contact with gaseous water after a fluorination treatment at a specific temperature. It has been found that the use of the electrode using carbon black can lower the internal resistance of the battery and improve the cycle characteristics of the battery.

That is, the present invention provides the following inventions.
1. A carbon black used as a conductive aid for a non-aqueous electrolyte secondary battery having a positive electrode, a negative electrode, and an electrolyte,
The BET specific surface area is 300 m ² / g or more and 1500 m ² / g or less,
The ratio of fluorine atoms to carbon atoms, that is, the F / C ratio is 0.001 or more and less than 0.025, and the ratio of oxygen atoms to carbon atoms, that is, the O / C ratio, is measured by XPS analysis. The carbon black which is 0.1 or more and less than 0.2.
2. 2. The carbon black as described in 1 above, wherein the F / C ratio is 0.01 or more and less than 0.025, and the O / C ratio is 0.12 or more and less than 0.19.
3. A current collector made of metal foil;
An electrode layer formed on the current collector and including the carbon black according to the item 1 or 2, and an electrode active material;
An electrode for a non-aqueous electrolyte secondary battery.
4). Having a positive electrode, a negative electrode, and an electrolyte;
4. A nonaqueous electrolyte secondary battery, wherein either or both of the positive electrode and the negative electrode are electrodes for a nonaqueous electrolyte secondary battery described in the above item 3.
5. A fluorination treatment step in which a carbon black having a BET specific surface area of 350 m ² / g or more and 1400 m ² / g or less is brought into contact with a treatment gas comprising a fluorine gas and an inert gas at 10 to 50 ° C., The concentration of fluorine gas in the processing gas is 0.01 to 5% by volume,
A post-treatment step of contacting the carbon black after the fluorination treatment with gaseous water;
The manufacturing method of the carbon black of said 1 or 2 containing these.
6). 6. The method for producing carbon black as described in 5 above, comprising a step of performing a degassing step by placing the carbon black in a reduced pressure environment after the fluorination treatment step and before the post-treatment step.
7). 7. The method for producing carbon black according to 5 or 6 above, comprising a step of performing a degassing step by placing the carbon black in a reduced pressure environment after the post-treatment step.
8). A step of creating a paste by dispersing the carbon black and the electrode active material according to 1 or 2 in a dispersion medium;
Applying the paste to a current collector and drying;
The manufacturing method of the electrode for nonaqueous electrolyte secondary batteries containing.
9. 9. The method for producing an electrode for a nonaqueous electrolyte secondary battery as described in 8 above, further comprising a binder and a viscosity modifier in the paste.

  According to the present invention, it is possible to produce a non-aqueous electrolyte secondary battery having good cycle characteristics without increasing the internal resistance, and carbon black used as a conductive aid. According to the present invention, it is also possible to improve the dispersibility of carbon black in an electrode preparation paste.

  Hereinafter, embodiments of the present invention will be described. It should be noted that the scope of the present invention is not limited by these descriptions, and can be changed and implemented as appropriate without departing from the spirit of the present invention other than the following examples.

In the present invention, the carbon black is subjected to a fluorination treatment and further subjected to a post-treatment process. BET specific surface area before the carbon black performing fluorination treatment is at 300 meters ² / g or more 1500 m ² / g or less, preferably 350 meters ² / g or more 1450 m ² / g or less, 700 meters ² / g or more 1400m More preferably, it is ² / g or less. Examples of such carbon black include furnace black, ketjen black, and lamp black. For example, it is commercially available on Ketjen Black from Lion Specialty Chemicals. It should be noted that the BET specific surface area does not change greatly before and after the fluorination treatment, and usually remains within ± 10%. Therefore, the BET specific surface area of the carbon black after the post-treatment by the method of the present invention is 300 to 1500 m ² / g, preferably 350 to 1450 m ² / g. The BET specific surface area of carbon black is measured by a method based on ASTM D 3037.

  First, in the present invention, it is preferable to remove moisture adsorbed on the carbon black by heating or vacuum degassing before performing the fluorination treatment. This is because if moisture remains, it reacts with fluorine to generate hydrogen fluoride, which may adversely affect the production apparatus and the like.

  In the fluorination treatment method of the present invention, carbon black is usually charged into a cylindrical container. Here, the process gas adjusted so that the fluorine concentration falls within a predetermined range is circulated to cause fluorination. The container material can be safely processed as long as it is a metal material, but stainless steel such as SUS304 and SUS316 or nickel is desirable from the viewpoint of corrosion resistance in continuous processing.

  The treatment gas in the fluorination treatment consists of a fluorine gas and an inert gas. The concentration of the fluorine gas in the processing gas is 0.01 to 5% by volume, and preferably 0.05 to 4% by volume. When the fluorine gas concentration is within this range, the F / C ratio and O / C ratio of the carbon black can be controlled to a desired range, and the non-aqueous electrolyte battery has good cycle characteristics without increasing the internal resistance value. Is obtained. It is preferable that a gas other than fluorine and an inert gas, such as oxygen, is not mixed in the processing gas, and even if mixed, the concentration of the mixed gas is preferably 1% by volume or less. For example, when oxygen is mixed in the processing gas, it becomes difficult to control the O / C ratio to a desired value, and the reaction with carbon black proceeds rapidly, and in some cases there is a possibility of dust explosion. When the processing temperature is higher than 50 ° C, there is a risk of explosion due to the progress of fluorination more than expected, and when the processing temperature is lower than 10 ° C, cooling equipment and energy are required to create a cooling state. Since the cost becomes a problem, it is desirable to perform the treatment near room temperature. However, in the case where heat is generated at the time of contact between carbon black and fluorine, the apparatus may be cooled using cooling water or the like for controlling the reaction. Regarding the treatment time, sufficient time is required for the carbon black and fluorine to uniformly contact each other, and it is desirable to ensure 10 minutes or more, and more desirably 30 minutes or more. If it is too long, there is no effect on the performance as a conductive additive, but the production efficiency is lowered, so that it is preferably within 2 hours. Further, after the fluorination treatment, in order to remove as much as possible the fluorine adsorbed on the carbon black, that is, fluorine not contributing to the surface modification, it is preferable to deaerate in a vacuum state. The processing pressure is not particularly limited, but is preferably 700 Torr or less and more preferably 500 Torr or less from the viewpoint of safety. In order to obtain a sufficient reaction rate, it is preferably 10 Torr or more, and more preferably 50 Torr or more. Since the preferable flow rate of the processing gas varies depending on the size and structure of the reaction apparatus, it may be appropriately adjusted.

  After the fluorination treatment, the carbon black is exposed to air containing a predetermined humidity or water vapor to perform a post-treatment process. The post-treatment step can be performed at 10 to 30 ° C., but can be performed at ambient temperature or normal temperature without heating. Further, when exposed to the atmosphere of 30 to 80% at a relative humidity, the treatment may be performed for 2 hours to 48 hours, and when exposed to water vapor, the treatment may be performed for 10 minutes to 2 hours. .

On the surface of carbon black, C—F groups and the like are generated by fluorination treatment. In the post-treatment step, the C—F group on the surface of the carbon black is converted into a C—OF group, a C—OH group, a COOH group, or the like by the action of H ₂ O, and the surface is modified. It is considered that the carbon black whose surface is modified has improved dispersibility in the paste for electrode preparation as compared with that before the modification. This conversion is estimated to be completed in about one hour after the end of the post-processing step. However, in some C—F groups, F is firmly bonded to C due to a difference in the crystallinity of carbon black, and remains without reacting with H ₂ O. In addition, it is preferable to remove HF produced | generated simultaneously by vacuum deaeration after that.

  At this time, the ratio of fluorine atoms to carbon atoms measured by XPS (X-ray photoelectron spectroscopy) analysis of the surface of carbon black after the post-treatment step, that is, the F / C ratio is 0.001 or more and less than 0.025, 0.01 or more and 0.02 or less are desirable. In addition, the ratio of oxygen atoms to carbon atoms, that is, the O / C ratio is 0.1 or more and less than 0.2, and preferably 0.14 or more and less than 0.17. If the F / C ratio and the O / C ratio are within the above ranges, the dispersibility in the paste for electrode preparation is improved while suppressing the increase in resistance derived from fluorine and carbon, and carbon black is a network. It becomes easy to form.

  When the F / C ratio and O / C ratio of the carbon black after the post-treatment process are high, and there are too many fluorine atoms and oxygen atoms on the surface of the carbon black, the internal resistance of the battery increases and the cycle characteristics of the battery deteriorate. . Although the cause is not clear, the present inventors presume as follows. For example, it is conceivable that fluorine atoms and oxygen atoms on the surface of carbon black become impurities, and in the network formed by carbon black, the contact resistance between carbon black and carbon black increases. In addition, when there are too many fluorine atoms or oxygen atoms, the condensed benzene ring of carbon black is destroyed by excessive fluorination reaction. As a result, the movement of π electrons on carbon black is inhibited, and the conductivity of carbon black itself is reduced. It is possible to get worse.

  Next, a non-aqueous electrolyte battery using the carbon black of the present invention will be described. Non-aqueous electrolyte battery electrolyte, negative electrode material capable of reversibly inserting and removing alkali metal ions such as lithium ions and sodium ions, or alkaline earth metal ions, lithium ions and sodium ions An electrochemical device using a positive electrode material into which alkali metal ions or alkaline earth metal ions can be reversibly inserted and removed is called a non-aqueous electrolyte battery.

  The non-aqueous electrolyte battery of the present invention is characterized by using the fluorinated carbon black of the present invention, and the other components used in general non-aqueous electrolyte batteries are used. That is, it comprises a positive electrode and a negative electrode capable of inserting and extracting lithium, a current collector, a separator, a container, and the like.

  The negative electrode is not particularly limited, but a material capable of reversibly inserting and desorbing alkali metal ions such as lithium ions and sodium ions or alkaline earth metal ions is used, and the positive electrode is not particularly limited. However, materials in which alkali metal ions such as lithium ions and sodium ions or alkaline earth metal ions can be reversibly inserted and removed are used.

  When the carbon black of the present invention is used as a conductive additive for a negative electrode, a negative electrode active material capable of occluding and releasing lithium, a binder, carbon black and a solvent are mixed and slurried, and then applied to the electrode. To do. Various materials capable of inserting and extracting lithium include, for example, when the cation is lithium, lithium metal as an anode material, alloys and intermetallic compounds of lithium and other metals, artificial graphite and natural graphite, Carbon materials such as activated carbon, metal oxides, metal nitrides, and the like are used.

When the carbon black of the present invention is used as a conductive additive for the positive electrode, a positive electrode active material capable of occluding and releasing lithium, a binder, and a solvent are mixed and slurried and then applied to the electrode. . In the case of a lithium battery and a lithium ion battery, examples of the active material include lithium-containing transition metal composite oxides such as LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , and Co of the lithium-containing transition metal composite oxides. , A mixture of a plurality of transition metals such as Mn, Ni, etc., a part of the transition metal of the lithium-containing transition metal composite oxide substituted with a metal other than the transition metal, LiFePO ₄ , LiCoPO called olivine _4, LiMnPO phosphate compound of a transition metal such as _{4, TiO 2, V 2 O} 5, an oxide such as MoO _3, is used to TiS _2, sulfides such as FeS or the like. Alternatively, conductive polymers such as polyacetylene, polyparaphenylene, polyaniline, and polypyrrole, activated carbon, polymers that generate radicals, carbon materials, and the like are used.

  As a binder used for the positive electrode or the negative electrode material, polytetrafluoroethylene, polyvinylidene fluoride, SBR resin, or the like is used. As the solvent, N-methyl-2-pyrrolidone (hereinafter “NMP”) or the like is used.

  Examples of the present invention are listed below together with comparative examples, but the present invention is not limited to the following examples.

[Example 1]
<Production of fluorinated carbon black>
Carbon black with a BET specific surface area of 1350 m ² / g (Ketjen Black EC600JD, manufactured by Lion Specialty Chemicals Co., Ltd.) is enclosed in a 5 L SUS304 container, and the inside is evacuated to carbon black. The adsorbed moisture was removed. Here, 200 Torr of fluorine diluted to 0.05% by volume with nitrogen was sealed, and then allowed to flow at a total flow rate of 0.5 SLM for 30 minutes. In addition, said reaction was performed at room temperature (25 degreeC). After the end of distribution, the inside of the container was sufficiently replaced with nitrogen. Thereafter, the inside of the container was again depressurized to a vacuum state and deaerated overnight to remove as much as possible the fluorine adsorbed on the carbon black. Subsequently, the inside of the container was restored to atmospheric pressure and exposed to the atmosphere (temperature 25 ° C., relative humidity 45-50%) for 24 hours. The fluorinated carbon black obtained by these operations is XPS (“PHI VersaProbe II”, ULVAC-PHI, X-ray source: Al, X-ray: AlKα ray (1486.6 eV), output: 23.8 W, beam The surface composition was measured at a diameter of 100 μm). Further, the BET specific surface area was measured by a method based on ASTM D 3037.

<Preparation of positive electrode>
As the positive electrode active material, LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (NCM) powder and the fluorinated carbon black produced in Example 1 were dry-mixed to form a binder, polyvinylidene fluoride (hereinafter “ PVDF ") was uniformly dispersed in pre-dissolved NMP, mixed, and NMP for viscosity adjustment was further added to prepare an NCM mixture paste. This paste was applied on an aluminum foil (current collector), dried and pressurized, and then a test NMC positive electrode processed into a predetermined size was obtained. The solid content ratio in the positive electrode was NCM: fluorinated carbon black: PVDF = 85: 5: 10 (mass ratio).

<Preparation of graphite negative electrode>
As a negative electrode active material, graphite powder was uniformly dispersed and mixed in NMP in which PVDF as a binder was previously dissolved, and NMP for viscosity adjustment was further added to prepare a graphite mixture paste. This paste was applied on a copper foil (current collector), dried and pressurized, and then a test graphite negative electrode processed into a predetermined size was obtained. The solid content ratio in the negative electrode was graphite powder: PVDF = 90: 10 (mass ratio).

<Preparation of non-aqueous electrolyte battery>
A nonaqueous solvent battery was obtained by impregnating an aluminum laminate outer cell (capacity 30 mAh) comprising the above test NCM positive electrode, a test graphite negative electrode, and a cellulose separator, with a nonaqueous solvent. The volume ratio of ethylene carbonate (hereinafter “EC”), propylene carbonate (hereinafter “PC”), dimethyl carbonate (hereinafter “DMC”), and ethyl methyl carbonate (hereinafter “EMC”) as the non-aqueous solvent is 2: 1: 3. : 4 was used, and lithium hexafluorophosphate (hereinafter referred to as “LiPF ₆ ”) was dissolved as a solute in the solvent so as to have a concentration of 1.0 mol / L to prepare an electrolytic solution. In addition, said preparation was performed maintaining a liquid temperature at 25 degreeC.

<Battery evaluation>
<Evaluation 1: Measurement of battery internal resistance>
The following evaluation was implemented about each of the non-aqueous electrolyte battery which concerns on an Example and a comparative example.
First, conditioning was performed using the fabricated cell at an environmental temperature of 25 ° C. under the following conditions. That is, as the first charge / discharge, the battery is charged at a constant current and constant voltage at a charging upper limit voltage of 4.3 V and a 0.1 C rate (3 mA), and discharged at a 0.2 C rate (6 mA) constant current up to a discharge end voltage of 3.0 V. Thereafter, charging / discharging cycle is performed three times by charging at a constant current / constant voltage at a charging upper limit voltage of 4.3V and a 0.2C rate (6 mA) and discharging at a constant current of 0.2C (6 mA) to a discharge end voltage of 3.0V. Repeated. Thereafter, the internal resistance of the battery was measured. Table 1 shows the measurement results of the internal resistance in each example and comparative example. In addition, the numerical value of the internal resistance described in Table 1 is a relative value when the internal resistance of Comparative Example 1 is 100.

<Evaluation 2: Measurement of high-temperature cycle characteristics>
After performing the above conditioning, after charging at a constant current and constant voltage at an upper limit voltage of 4.3 V and a 3 C rate (90 mA) at an environmental temperature of 55 ° C., the battery is discharged at a constant current of 3 C (90 mA) to a discharge end voltage of 3.0 V. This charging / discharging was repeated 100 cycles. The ratio of the discharge capacity at the 100th cycle to the initial (first cycle) discharge capacity was defined as the cycle capacity retention rate, and the high temperature cycle characteristics of the cell were evaluated. In addition, the numerical value of the cycle characteristic after 100 cycles described in Table 1 is a relative value when the discharge capacity retention rate after 100 cycles of Comparative Example 1 is 100.

[Example 2]
The same test as in Example 1 was performed except that the concentration of diluted fluorine used was 2% by volume and the contact time with fluorine was 10 minutes when producing fluorinated carbon black.

Example 3
The same test as in Example 1 was performed, except that the concentration of diluted fluorine used was changed to 0.5% by volume when producing the fluorinated carbon black.

Example 4
The same test as in Example 1 was performed except that the concentration of diluted fluorine used was 2% by volume in the production of fluorinated carbon black.

Example 5
The same test as in Example 1 was performed except that the concentration of diluted fluorine used was changed to 4% by volume in the production of fluorinated carbon black.

Example 6
The same test as in Example 1 was performed, except that the pressure when contacting with diluted fluorine was 50 Torr in the production of fluorinated carbon black.

Example 7
In producing the fluorinated carbon black, the same test as in Example 1 was performed, except that the pressure when contacting with diluted fluorine was 500 Torr.

Example 8
In producing fluorinated carbon black, the same test as in Example 4 was performed except that the concentration of diluted fluorine used was 4% by volume and the pressure when contacting with diluted fluorine was 500 Torr.

Example 9
The same test as in Example 1 was performed except that carbon black having a BET specific surface area of 800 m ² / g (Ketjen Black EC300J, manufactured by Lion Specialty Chemicals Co., Ltd.) was used in the production of fluorinated carbon black.

Example 10
The same test as in Example 9 was performed except that the treatment time for contacting with diluted fluorine was set to 90 minutes when producing the fluorinated carbon black.

Example 11
In producing the fluorinated carbon black, the same test as in Example 1 was performed except that the treatment temperature was 40 ° C. and the treatment time was 10 minutes.

Example 12
In producing the fluorinated carbon black, the treatment temperature was set to 40 ° C., the treatment time was set to 10 minutes, and normal temperature water vapor (relative humidity 100%) was supplied for 30 minutes in the post-treatment process. A test was conducted.

[Comparative Example 1]
Instead of the fluorination treatment step, the same test as in Example 1 was performed except that nitrogen gas not containing fluorine was circulated.

[Comparative Example 2]
The same test as in Example 1 was performed except that the concentration of diluted fluorine used was 0.005% by volume in the production of fluorinated carbon black.

[Comparative Example 3]
The same test as in Example 1 was performed, except that the concentration of diluted fluorine used was changed to 7% by volume when producing the fluorinated carbon black.

[Comparative Example 4]
In producing the fluorinated carbon black, the same test as in Example 1 was performed, except that the fluorine concentration was 4% by volume, the oxygen concentration was 10% by volume, and a gas diluted with nitrogen was circulated.

[Comparative Example 5]
In producing the fluorinated carbon black, the same test as in Example 1 was conducted except that the treatment temperature when contacting with diluted fluorine was 80 ° C.

[Comparative Example 6]
When producing fluorinated carbon black, the same test as in Example 1 was performed except that oxygen gas was supplied in the post-treatment process.

[Comparative Example 7]
When producing fluorinated carbon black, the same test as in Example 1 was performed except that nitrogen gas was supplied in the post-treatment process.

[Comparative Example 8]
In producing the fluorinated carbon black, the same test as in Example 1 was performed except that carbon black having a BET specific surface area of 800 m ² / g was used and nitrogen gas not containing fluorine was circulated in the fluorination treatment step. .

  From the results of Examples 1 to 12 and the results of Comparative Examples 1 to 8, a post-treatment step of bringing diluted fluorine gas in a range of 0.05 to 5% by volume of fluorine and carbon black into contact with gaseous water is performed. By performing the XPS analysis, the ratio of fluorine atoms to carbon atoms, that is, the F / C ratio is 0.001 or more and less than 0.025, and the ratio of oxygen atoms to carbon atoms, that is, the O / C ratio. It can be seen that a fluorinated carbon black can be obtained, wherein In addition, the non-aqueous electrolyte battery produced using the fluorinated carbon black in these ranges has a fluorine concentration outside the above range or compared with carbon black treated with diluted fluorine containing oxygen gas, It can be seen that the internal resistance value is reduced and a high discharge capacity retention rate is maintained.

  On the other hand, from the result of Comparative Example 2, when the fluorine concentration was 0.005 vol%, the surface modification hardly progressed, and the F / C ratio and the O / C value hardly changed, and the internal resistance value was There was no change in the cycle characteristics. From the results of Comparative Example 3, when the fluorine concentration was 7% by volume, the F / C ratio and the O / C value increased greatly, but the internal resistance value increased and the cycle characteristics deteriorated. This is presumably because the fluorine concentration was too high, the surface of the carbon black was extremely rough, and charge transport was inhibited.

  In Comparative Example 4, since carbon black was treated with a gas obtained by diluting fluorine and oxygen with nitrogen, the O / C value of the treated carbon black increased, the internal resistance value increased, and the cycle characteristics deteriorated. This is probably because the fluorination treatment with fluorine and oxygen changed the cross-linked structure of carbon black and hindered the conductive path between carbon and carbon, so that the internal resistance value increased.

  In Comparative Example 5, since the treatment temperature was 80 ° C., the fluorination treatment proceeded strongly, and the F / C ratio of the treated carbon black was greatly increased. During the fluorination treatment, it was considered that the surface of the carbon black was roughened, the internal resistance value increased, and the cycle characteristics deteriorated.

  In Comparative Example 6, it was exposed with oxygen gas in the post-treatment step after the fluorination treatment, but it had a high F / C ratio equivalent to that of Comparative Example 7, and the CF group was changed to a COF group or the like. An increase in the O / C ratio, which was considered to be due to oxidation of the terminal substituent that was in an unstable bond state, was observed. In Comparative Example 6, the internal resistance value was high, and the cycle characteristics deteriorated.

  In Comparative Example 7, since the carbon black was subjected to a post-treatment step with an inert gas after the fluorination treatment, a large amount of fluorine components remained in the carbon black after the treatment, and the O / C was compared with the carbon black before the treatment. Since the ratio was hardly increased, it was considered that no COH group or COOH group was generated, and the internal resistance value was high and the cycle characteristics were low.

Claims (9)

A carbon black used as a conductive aid for a non-aqueous electrolyte secondary battery having a positive electrode, a negative electrode, and an electrolyte,
The BET specific surface area is 300 m ² / g or more and 1500 m ² / g or less,
The ratio of fluorine atoms to carbon atoms, that is, the F / C ratio is 0.001 or more and less than 0.025, and the ratio of oxygen atoms to carbon atoms, that is, the O / C ratio, is measured by XPS analysis. The carbon black which is 0.1 or more and less than 0.2.   The carbon black according to claim 1, wherein the F / C ratio is 0.01 or more and less than 0.025, and the O / C ratio is 0.12 or more and less than 0.19. A current collector made of metal foil;
An electrode layer formed on the current collector and containing the carbon black according to claim 1 or 2 and an electrode active material,
An electrode for a non-aqueous electrolyte secondary battery. Having a positive electrode, a negative electrode, and an electrolyte;
The nonaqueous electrolyte secondary battery in which any one or both of the said positive electrode and the said negative electrode are the electrodes for nonaqueous electrolyte secondary batteries of Claim 3. Carbon black having a BET specific surface area of 1450 m ² / g or less be at 350 meters ² / g or more, at 50 ° C. from 10 ° C., and the fluorination treatment step of contacting a process gas consisting of fluorine gas and inert gas, wherein The concentration of fluorine gas in the processing gas is 0.01 to 5% by volume,
A post-treatment step of contacting the carbon black after the fluorination treatment with gaseous water;
The manufacturing method of the carbon black of Claim 1 or 2 containing this.   The method for producing carbon black according to claim 5, comprising a step of performing a deaeration step by placing the carbon black in a reduced pressure environment after the fluorination treatment step and before the post-treatment step.   The method for producing carbon black according to claim 5 or 6, comprising a step of performing a deaeration step by placing the carbon black in a reduced pressure environment after the post-treatment step. A step of creating a paste by dispersing the carbon black according to claim 1 or 2 and an electrode active material in a dispersion medium;
Applying the paste to a current collector and drying;
The manufacturing method of the electrode for nonaqueous electrolyte secondary batteries containing.   The method for producing an electrode for a nonaqueous electrolyte secondary battery according to claim 8, further comprising a binder and a viscosity modifier in the paste.