JP6908435B2 - Method for producing sulfur-modified polyacrylonitrile - Google Patents

Description

The present invention relates to a method for producing sulfur-modified polyacrylonitrile and the use of the sulfur-modified polyacrylonitrile obtained by the production method.

With the spread of portable electronic devices such as portable personal computers, handy video cameras, and information terminals in recent years, non-aqueous electrolyte secondary batteries having high voltage and high energy density have come to be widely used as a power source. In addition, from the viewpoint of environmental problems, battery vehicles and hybrid vehicles that use electric power as a part of power are being put into practical use.

The characteristics of a non-aqueous electrolyte secondary battery depend on its constituent members such as electrodes, separators, and electrolytes, and research and development of each constituent member is being actively carried out. In electrodes, electrode active materials are important together with binders, current collectors, etc., and research and development of electrode active materials are being actively carried out.

In recent years, research has been conducted on using sulfur, which is a substance having the theoretically maximum electric capacity among known materials, as a material for an electrode active material. For example, Patent Document 1 proposes the use of sulfur-modified polyacrylonitrile as an active material for a secondary battery. Sulfur-modified polyacrylonitrile is obtained by heat-treating a mixture of polyacrylonitrile powder and sulfur powder in a non-oxidizing atmosphere. Patent Document 1 states that a sulfur-modified polyacrylonitrile can be produced by heating a mixture of sulfur powder and polyacrylonitrile powder in a non-oxidizing atmosphere while preventing the outflow of sulfur vapor while refluxing the sulfur vapor. Has been described.

As described above, sulfur-modified polyacrylonitrile is obtained by heat-treating a mixture of polyacrylonitrile powder and sulfur powder. Patent Document 2 describes a drop-type powder treatment device as an apparatus for heat-treating the powder. Has been done. The drop-type powder processing apparatus described in Patent Document 2 includes a raw material supply unit 30 that supplies the raw material powder W, a heating unit 40 that heat-treats the powder W that is supplied from the raw material supply unit 30 and drops. It is provided with a cooling unit 50 for cooling the heat-treated powder W. The drop-type powder processing apparatus described in Patent Document 2 controls the falling speed of powder falling in the heating unit 40 by supplying gas from the lower side and / or the upper side of the heating unit 40. The drop-type powder processing apparatus described in Patent Document 2 is supplied from the lower side and / or the upper side of the heating unit 40 according to the type, specific gravity, particle size, etc. of the powder W falling in the heating unit 40. By adjusting the amount of gas supplied, the falling speed of the powder W can be controlled. Therefore, even if the type, specific gravity, particle size, etc. of the powder W are different, the time for heat-treating the powder W can be increased. It can be adjusted easily and appropriately.

International Release 2010/0444437 Japanese Unexamined Patent Publication No. 2012-228631

However, the production method described in Patent Document 1 is uneconomical because the obtained sulfur-modified polyacrylonitrile contains a sulfur solid and therefore requires a heat treatment step for removing the sulfur solid from the sulfur-modified polyacrylonitrile. In addition, since the average particle size of the obtained sulfur-modified polyacrylonitrile varies greatly, it is not sufficiently satisfactory as an active material for electrodes of secondary batteries. Therefore, there has been a demand for a method for producing a sulfur-modified polyacrylonite having characteristics that are sufficiently satisfactory as an active material for an electrode of a secondary battery.

Further, Patent Document 2 does not describe the use of a drop-type powder processing apparatus for producing sulfur-modified polyacrylonitrile.

Therefore, an object of the present invention is to provide a production method for obtaining high quality sulfur-modified polyacrylonitrile. Further, the present invention provides a method for producing an electrode for a secondary battery using the sulfur-modified polyacrylonitrile obtained by the production method of the present invention.

As a result of diligent studies, the present inventors have found that high-quality sulfur-modified polyacrylonitrile can be efficiently produced by using a drop-type powder processing apparatus, and have completed the present invention.

The present invention comprises a raw material supply unit that supplies powder of a raw material containing polyacrylonitrile powder and sulfur powder, a heating unit that heat-treats the powder supplied from the raw material supply unit and dropped, and a heat-treated powder. A method for producing sulfur-modified polyacrylonitrile using a drop-type powder processing apparatus equipped with a cooling unit for cooling the body.
The present invention provides a method for producing a sulfur-modified polyacrylonitrile, which comprises a step of supplying gas from the lower side and / or the upper side of the heating portion to control the falling speed of the powder falling in the heating portion.

Further, in the present invention, the drop-type powder is provided with an exhaust gas unit for discharging the exhaust gas in the heating unit to the outside on the upper side of the heating unit, and an exhaust gas treatment device for detoxifying the exhaust gas is provided in the exhaust gas unit. The present invention provides a method for producing the above-mentioned sulfur-modified polyacrylonitrile using a treatment apparatus.

Further, the present invention uses the drop-type powder processing apparatus having a mechanism for controlling the falling speed of the powder falling in the heating portion by the gas supplied from the lower side and / or the upper side of the heating portion. It provides a method for producing sulfur-modified polyacrylonitrile.

Further, the present invention relates to the exhaust gas unit having a pressure measuring device for measuring the pressure in the heating unit, and the gas guided into the heating unit according to the pressure in the heating unit measured by the pressure measuring device. The present invention provides a method for producing the sulfur-modified polyacrylonitrile by using the drop-type powder processing apparatus having a control device for adjusting the amount.

The present invention also provides the above-mentioned method for producing sulfur-modified polyacrylonitrile, wherein the raw material further contains a conductive auxiliary agent.

The present invention also provides a method for producing an electrode for a secondary battery, which comprises a step of producing sulfur-modified polyacrylonitrile by the above-mentioned method for producing sulfur-modified polyacrylonitrile.

The present invention also provides a method for manufacturing a secondary battery, which comprises a step of manufacturing the electrode for the secondary battery by the method for manufacturing the electrode for the secondary battery described above.

In the production method of the present invention, since the obtained sulfur-modified polyacrylonitrile does not contain sulfur solids, a heat treatment step for removing the sulfur solids from the obtained sulfur-modified polyacrylonitrile is not required, and the sulfur-modified poly in the apparatus. Since the adhesion of acrylonitrile is small, the recovery rate of sulfur-modified polyacrylonitrile is high and maintenance is easy, which is economical. Further, since the sulfur-modified polyacrylonitrile obtained by the production method of the present invention has a small particle size and is homogeneous, it can be used as an active material for an electrode for a secondary battery to have a high electric capacity and a high charge. A secondary battery with a capacity retention rate can be realized.

FIG. 1 is a vertical cross-sectional view schematically showing an example of a drop-type powder processing apparatus used in the method for producing sulfur-modified polyacrylonitrile of the present invention. FIG. 2 is a vertical sectional view schematically showing an example of the structure of a coin-type battery of a secondary battery having an electrode containing a sulfur-modified polyacrylonitrile obtained by the production method of the present invention. FIG. 3 is a schematic view showing a basic configuration of a cylindrical battery of a secondary battery having an electrode containing a sulfur-modified polyacrylonitrile obtained by the production method of the present invention. FIG. 4 is a perspective view showing the internal structure of a cylindrical battery of a secondary battery having an electrode containing a sulfur-modified polyacrylonitrile obtained by the production method of the present invention as a cross section.

The method for producing the sulfur-modified polyacrylonitrile of the present invention will be described.

First, the raw material used in the method for producing sulfur-modified polyacrylonitrile of the present invention contains polyacrylonitrile and sulfur, and may also contain other materials.

The raw material powder used in the production method of the present invention contains polyacrylonitrile powder. The average particle size of the polyacrylonitrile powder is preferably 1 to 150 μm, more preferably 1 to 50 μm. If the average particle size of the polyacrylonitrile powder is smaller than 1 μm, the polyacrylonitrile powder does not fall and is discharged together with the exhaust gas in the drop-type powder processing apparatus, which is not preferable because the yield may decrease. If it is larger than 150 μm, it may pass through the heating part before the reaction is completed and the quality may be deteriorated, or the reaction time may be lengthened and the productivity may be lowered. Further, the weight average molecular weight of the polyacrylonitrile powder is in the range of about 10,000 to 1,000,000 because it is difficult to obtain the polyacrylonitrile powder if it is low, and it is difficult to increase the bound sulfur content if it is too large. Those in the range of about 10,000 to 300,000 are preferable, and those in the range of about 10,000 to 300,000 are more preferable. For the weight average molecular weight, a measurement value converted into polystyrene by a GPC (gel permeation chromatography) method is used. In the present invention, the bound sulfur means sulfur existing by being chemically bonded to modified polyacrylonitrile.

The raw material powder used in the production method of the present invention contains sulfur powder. The average particle size of the sulfur powder is preferably in the range of 1 to 100 μm, preferably in the range of 1 to 50 μm. The reason why the average particle size of the sulfur powder is in the above range is the same as the reason why the average particle size of the polyacrylonitrile powder is in the above range. Regarding the content of sulfur powder in the raw material used in the production method of the present invention, when the ratio of sulfur powder to polyacrylonitrile powder is small, the bound sulfur content of sulfur-modified polyacrylonitrile is small and the ratio of sulfur powder to polyacrylonitrile powder is large. Since the effect of increasing the amount is small and the amount of solid sulfur that is unreacted and needs to be recovered increases, the amount is preferably 100 to 500 parts by mass, more preferably 200 to 400 parts by mass with respect to 100 parts by mass of the polyacrylonitrile powder. And.

The raw material powder used in the production method of the present invention may contain other materials. Examples of the other materials include those used as a conductive auxiliary agent for electrodes for secondary batteries. Specific examples thereof include carbon materials, metal powders, and conductive metal oxides. Carbon materials include natural graphite, artificial graphite, carbon black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon nanotubes, graphene, needle coke, etc., and metal powders include aluminum powder and nickel. It is a powder or the like, and examples of the conductive metal oxide are zinc oxide, titanium oxide and the like. The other materials are preferably in the form of powder. The average particle size of the other materials is preferably 0.01 to 50 μm, more preferably 0.1 to 20 μm. The content of the other materials in the raw material used in the production method of the present invention is preferably 1 to 30 parts by mass, more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the polyacrylonitrile powder.

The average particle size of the polyacrylonitrile powder, sulfur powder, and other material powders contained in the raw materials used in the production method of the present invention can be measured by, for example, a laser diffraction / scattering method.

Next, an apparatus for producing sulfur-modified polyacrylonitrile, which is preferably used in the production method of the present invention, will be described. The manufacturing apparatus shown in FIG. 1 (hereinafter, also simply referred to as manufacturing apparatus 10A) is a drop-type powder processing apparatus, which is supplied from a raw material supply unit 30 for supplying raw material powder W and a raw material supply unit 30. A tubular heating unit 40 that heat-treats the dropped powder W, a cooling unit 50 that cools the heat-treated powder W, a gas supply device 60 that supplies an inert gas to the heating unit 40, and heating. It is provided with an exhaust gas unit 70 that discharges the exhaust gas in the unit 40 to the outside. The manufacturing apparatus shown in FIG. 1 controls the falling speed of the powder W that drops in the heating unit 40 by supplying gas from the lower side and / or the upper side of the heating unit 40.

As shown in FIG. 1, the raw material supply unit 30 includes a raw material supply device 31, a sieving device 32, and a guide pipe 33. The raw material supply device 31 supplies the heat-treated raw material to the heating unit 40. The sieving device 32 is located below the raw material supply device 31 in the vertical direction X, sifts the agglomerated powder W guided from the raw material supply device 31, and adjusts the average particle size of the powder W. do. The guide pipe 33 is located directly below the sieving device 32 in the vertical direction X, is inserted into the heating unit 40, and guides the powder W dispersed by the sieving device 32 to the tubular heating unit 40. As the raw material, those that have been sifted in advance can be used.

As shown in FIG. 1, the heating unit 40 is located directly below the guide pipe 33 in the vertical direction X. The heating unit 40 is heated by a heating device 41 arranged on the outer peripheral side of the heating unit 40, and heat-treats the powder W that falls in the heating unit 40. The heating portion 40 has an extension portion 40A that hangs vertically downward from the lower end of the heat insulating material D, and the extension portion 40A is inserted into the cooling portion 50.

The cooling unit 50 is located directly below the heating unit 40 in the vertical direction X. The cooling unit 50 has an umbrella-shaped guide member 51 inside. The guide member 51 comes into contact with the heat-treated powder W in the heating unit 40, which is guided from the heating unit 40 to the cooling unit 50, cools the powder W, and cools the powder W in the cooling unit 50. Lead to the wall. The powder W guided to the inner wall surface of the cooling unit 50 by the guide member 51 is cooled by coming into contact with the inner wall surface of the cooling unit 50. The cooling unit 50 does not have to have the guide member 51.

The gas supply device 60 supplies an inert gas such as nitrogen or argon to the heating unit 40. As shown in FIG. 1, the gas supply device 60 has a first supply path 61a and a second supply path 61b. The first supply path 61a communicates with the cooling unit 50, and guides the inert gas supplied from the gas supply device 60 into the cooling unit 50. The inert gas guided into the cooling unit 50 through the first supply path 61a is guided into the heating unit 40 from directly below the heating unit 40 in the vertical direction X. The second supply path 61b communicates with the raw material supply unit 30 and guides the inert gas supplied from the gas supply device 60 into the raw material supply unit 30. The inert gas guided by the second supply path 61b is dispersed by the sieving device 32, and the powder W guided to the guide pipe 33 is sent out into the heating unit 40.

Further, the gas supply device 60 includes a first flow rate adjusting valve 62a arranged in the first supply path 61a, a second flow rate adjusting valve 62b arranged in the second supply path 61b, a first flow rate adjusting valve 62a, and a first flow rate adjusting valve 62a. It has a control device 63 for controlling the flow rate adjusting valve 62b. The control device 63 controls the first flow rate adjusting valve 62a, adjusts the amount of the inert gas guided from the cooling unit 50 into the heating unit 40 through the first supply path 61a, and adjusts the second flow rate adjusting valve 62b. It controls and adjusts the amount of the inert gas guided to the guide pipe 33 in the raw material supply unit 30 through the second supply path 61b.

The exhaust gas unit 70 is arranged above the heating unit 40 in the vertical direction X. The exhaust gas unit 70 includes an exhaust gas treatment device 71 that removes harmful components contained in the exhaust gas to detoxify the exhaust gas.

Further, the exhaust gas unit 70 is provided with a pressure measuring device 72 for measuring the pressure in the heating unit 40. The pressure measuring device 72 measures the pressure in the heating unit 40 and outputs the measured pressure in the heating unit 40 to the control device 63. The control device 63 controls the first flow rate adjusting valve 62a according to the pressure of the heating unit 40 output from the pressure measuring device 72, and enters the heating unit 40 from the cooling unit 50 through the first supply path 61a. The amount of the inert gas to be guided is adjusted, and the second flow rate adjusting valve 62b is controlled by the control device 63 to adjust the amount of gas guided to the guide pipe 33 in the raw material supply unit 30 through the second supply path 61b. do.
Here, it is very difficult to actually measure the falling speed and the falling time of the powder W in the heating unit 40 during heating, but as described above, the control device is based on the pressure in the heating unit 40. By adjusting the amount of gas guided from the cooling unit 50 and the guide pipe 33 into the heating unit 40 by the 63, the manufacturing apparatus 10A can adjust and reproduce the heat treatment conditions of the powder W.

Further, it is preferable that the manufacturing apparatus 10A is provided with the heat insulating material D around the heating unit 40 and the exhaust gas unit 70.

In the manufacturing apparatus 10A, when the powder W is heat-treated, if it is desired to lengthen the time for heat-treating the powder W in the heating unit 40, the control device 63 controls the first flow rate adjusting valve 62a and the second flow rate adjusting valve. While controlling 62b and increasing the amount of inert gas guided from the cooling unit 50 into the heating unit 40 through the first supply passage 61a, it is guided to the guide pipe 33 in the raw material supply unit 30 through the second supply passage 61b. It is configured to reduce the amount of inert gas to be taken or to prevent the gas from being guided to the guide pipe 33 in the raw material supply unit 30. According to the manufacturing apparatus 10A having such a configuration, even if the powder W has a large specific gravity and particle size and has a high free-falling speed in the heating unit 40, the heating unit 40 can be removed from the cooling unit 50. The falling speed of the gas can be slowed down by the gas guided into the inside, and as a result, the time for heat-treating the powder W in the heating unit 40 can be lengthened. Further, when the powder W having a slow free fall speed is used, the falling speed of the powder W can be slowed down.

Further, in the manufacturing apparatus 10A, when the powder W is to be heat-treated, if it is desired to shorten the time for heat-treating the powder W in the heating unit 40, the control device 63 controls the first flow rate adjusting valve 62a and the second flow rate. By controlling the regulating valve 62b, the amount of the inert gas guided from the cooling unit 50 into the heating unit 40 through the first supply path 61a is reduced, or the inert gas is introduced from the cooling unit 50 into the heating unit 40. On the other hand, it is configured to increase the amount of the inert gas guided to the guide pipe 33 in the raw material supply unit 30 through the second supply path 61b. According to the manufacturing apparatus 10A having such a configuration, even if the powder W has a small specific gravity and particle size and has a slow free fall speed in the heating unit 40, the inert gas guided to the guide tube 33 causes the powder W to fall freely. It is possible to increase the falling speed in the heating unit 40, and as a result, it is possible to shorten the time for heat treatment of the powder W in the heating unit 40. Further, when the powder W having a high free fall speed is used, the falling speed of the powder W can be further increased.

That is, the manufacturing apparatus 10A has a mechanism for controlling the falling speed of the powder W falling in the heating unit 40 by the gas supplied from the lower side and / or the upper side of the heating unit 40.

Next, the method for producing the sulfur-modified polyacrylonitrile of the present invention will be described step by step. The production method of the present invention can be suitably carried out by using, for example, the sulfur-modified polyacrylonitrile production apparatus 10A shown in FIG.

In the manufacturing method of the present invention, first, the powder W of the raw material to be heat-treated is guided to the sieving device 32 from the raw material supply device 31 provided in the raw material supply section 30 of the manufacturing device 10A, and is aggregated by the sieving device 32. The powder W is sieved and the average particle size of the powder W is adjusted. In the production method of the present invention, the powder W is crushed so that its average particle size is preferably 1 to 100 μm, more preferably 1 to 50 μm.

Then, the powder W dispersed by the sieving device 32 is guided into the tubular heating unit 40 through the guide pipe 33 in the raw material supply unit 30, and is dropped in the heating unit 40.

In the manufacturing method of the present invention, the inside of the heating section 40 is heated by the heating device 41 provided on the outer peripheral side of the heating section 40 of the manufacturing device 10A, and the powder W falling in the heating section 40 is heat-treated.

In the production method of the present invention, when the powder W is heat-treated in the heating unit 40, an inert gas such as nitrogen or argon is introduced from the gas supply device 60 of the production device 10A through the first supply path 61a as described above. The inert gas guided into the cooling unit 50 and guided into the cooling unit 50 is guided into the heating unit 40 from the vertically lower side of the heating unit 40, and the inert gas is secondly supplied from the gas supply device 60. The powder W, which is guided to the raw material supply unit 30 through the passage 61b, dispersed by the sieving device 32 and guided to the guide pipe 33, is sent out into the heating unit 40 by this inert gas.

Further, in the manufacturing method of the present invention, the first flow rate adjusting valve 62a provided in the first supply path 61a and the second flow rate adjusting valve 62b provided in the second supply path 61b are controlled by the control device 63. The amount of gas guided from the cooling section 50 to the heating section 40 through the first supply path 61a is adjusted, and the amount of gas guided to the guide pipe 33 in the raw material supply section 30 through the second supply path 61b is adjusted. adjust.

Specifically, in the manufacturing method of the present invention, the pressure in the heating unit 40 measured by the pressure measuring device 72 is output to the control device 63, and the first is performed by the control device 63 according to the pressure of the heating unit 40. The flow rate adjusting valve 62a is controlled, the amount of gas guided from the cooling unit 50 to the heating unit 40 through the first supply path 61a is adjusted, and the second flow rate adjusting valve 62b is controlled by the control device 63. The amount of gas guided to the guide pipe 33 in the raw material supply unit 30 is adjusted through the second supply path 61b.

Here, it is very difficult to actually measure the falling speed and the falling time of the powder W during heating. However, in the production method of the present invention, the powder is powdered by adjusting the amount of gas guided from the cooling unit 50 and the guide pipe 33 into the heating unit 40 by the control device 63 based on the pressure in the heating unit 40. It makes it possible to adjust and reproduce the heat treatment conditions of the body W.

In the production method of the present invention, when the powder W is heat-treated, when the time for heat-treating the powder W in the heating unit 40 is lengthened, the control device 63 controls the first flow rate adjusting valve 62a and the second. The flow control valve 62b is controlled to increase the amount of inert gas guided from the cooling unit 50 into the heating unit 40 through the first supply path 61a, while the guide pipe in the raw material supply unit 30 passes through the second supply path 61b. The amount of the inert gas guided to the 33 is reduced, or the inert gas is not guided to the guide pipe 33 in the raw material supply unit 30. In the production method of the present invention, by controlling the supply amount of the inert gas supplied to the heating unit 40 as described above, the powder has a large specific gravity and particle size and has a high free falling speed in the heating unit 40. Even in the body W, the falling speed is slowed by the inert gas guided from the cooling unit 50 into the heating unit 40, and the time for heat-treating the powder W in the heating unit 40 can be lengthened. Further, when the powder W having a slow free fall speed is used, the falling speed of the powder W can be further reduced.

On the other hand, when shortening the heat treatment time in the heating unit 40 of the powder W, the control device 63 controls the first flow rate adjusting valve 62a and the second flow rate adjusting valve 62b, and passes through the first supply path 61a. The amount of gas guided from the cooling unit 50 into the heating unit 40 is reduced, or the inert gas is not guided from the cooling unit 50 into the heating unit 40, while the raw material supply unit is passed through the second supply path 61b. The amount of gas guided to the guide pipe 33 in 30 is increased. In the production method of the present invention, by controlling the supply amount of the inert gas supplied to the heating unit 40 as described above, the powder has a small specific gravity and particle size and has a slow free falling speed in the heating unit 40. Even in the body W, the inert gas guided to the guide tube 33 increases the falling speed in the heating unit 40, and the time for heat-treating the powder W in the heating unit 40 can be shortened. Further, when the powder W having a high free fall speed is used, the falling speed of the powder W can be further increased.

In the production method of the present invention, the temperature inside the heating unit 40 is usually 300 to 1000 ° C., preferably 400 to 700 ° C., from the amount of gas supplied from the first supply path 61a and from the second supply path 61b. It is preferable to adjust the amount of gas to be supplied so that the powder W drops in the heating unit 40 at a rate of heating for 1 to 120 seconds, particularly 5 to 60 seconds.

Then, in the production method of the present invention, the falling heat-treated powder W is guided from the inside of the heating unit 40 into the cooling unit 50 provided vertically below the heating unit 40 to be cooled. In the production method of the present invention, the powder W is preferably cooled to 10 to 100 ° C., more preferably 20 to 50 ° C. in the cooling unit 50.

Specifically, in the manufacturing method of the present invention, the umbrella-shaped guide member 51 provided in the cooling unit 50 is brought into contact with the powder W falling in the cooling unit 50 to cool it, and the guide member 51 is cooled. The powder W is guided to the inner wall surface of the cooling unit 50, and the powder W is efficiently cooled by contact with the inner wall surface.

Further, in the manufacturing method of the present invention, the exhaust gas generated in the heating unit 40 is taken into the exhaust gas unit 70, detoxified by the exhaust gas treatment device 71, and then discharged to the outside by the exhaust gas unit 70.

The sulfur-modified polyacrylonitrile obtained by the production method of the present invention is characterized in that it does not contain a sulfur solid, has a small particle size and is homogeneous, and is useful as an active material for a secondary battery electrode. In the present invention, the sulfur solid means sulfur existing as a simple substance that is not chemically bonded to the modified polyacrylonitrile. Specifically, the sulfur-modified polyacrylonitrile obtained by the production method of the present invention preferably has an average particle size of 1 to 100 μm, more preferably 1 to 50 μm. The average particle size of sulfur-modified polyacrylonitrile can be measured by laser diffraction / scattering methods. Further, the fact that the sulfur-modified polyacrylonitrile does not contain a sulfur solid means that the content of the sulfur solid in the sulfur-modified polyacrylonitrile is less than 5% by mass, preferably less than 2% by mass, and more preferably 0% by mass. The content of bound sulfur in the sulfur-modified polyacrylonitrile is preferably 25 to 60% by mass, more preferably 30 to 55% by mass. The content of solid sulfur and bound sulfur in sulfur-modified polyacrylonitrile can be measured by thermogravimetric analysis and elemental analysis. In the following, a method for manufacturing a secondary battery electrode having a step of manufacturing a sulfur-modified polyacrylonitrile by the manufacturing method of the present invention, and a step of manufacturing a secondary battery electrode by the method for manufacturing the secondary battery electrode. The method of manufacturing the secondary battery having the above will be described. The sulfur-modified polyacrylonitrile obtained by the production method of the present invention can be used as an active material for both positive and negative electrodes. When the sulfur-modified polyacrylonitrile obtained by the production method of the present invention is used as the negative electrode active material, the positive electrode active material used is usually used as the positive electrode active material of a lithium secondary battery or a lithium ion secondary battery. can. When the sulfur-modified polyacrylonitrile obtained by the production method of the present invention is used as the positive electrode active material, the negative electrode active material used is usually used as the negative electrode active material of a lithium secondary battery or a lithium ion secondary battery. be able to.

The electrode for the secondary battery is manufactured by the following steps (1) to (3).
(1) Step of mixing an electrode mixture containing an electrode active material containing a sulfur-modified polyacrylonitrile obtained by the production method of the present invention into a slurry (2) Collecting a slurry electrode mixture (3) Step of heating the current collector after applying the electrode mixture

Hereinafter, the steps (1) to (3) above will be described in more detail.
(1) A step of mixing an electrode active material containing a sulfur-modified polyacrylonitrile obtained by the production method of the present invention and an electrode mixture containing a binder to form a slurry. An electrode containing an electrode active material and a binder. In the compounding agent, known materials can be used other than using the sulfur-modified polyacrylonitrile obtained by the production method of the present invention as the electrode active material. In addition to the electrode active material and the binder, other components (binding agent, conductive auxiliary agent, lithium salt, polymerization initiator, filler, solvent, etc.) can be added to the electrode mixture, if necessary.

The blending amount of each component contained in the electrode mixture is not particularly limited and can be adjusted based on the conventionally known technique for the active material layer of the battery, but is preferably as follows.
The content of sulfur-modified polyacrylonitrile in the electrode mixture is usually 10 to 99.9% by mass in the electrode mixture.
The amount of the binder is preferably 0.1 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the electrode active material.

The method of mixing the electrode mixture to form a slurry is not particularly limited, but an ordinary ball mill, a disperser such as a sand mill, an ultrasonic disperser, a homogenizer, or the like can be used.

(2) Step of Applying Slurry Electrode Mixture to Current Collector Examples of the method of applying the slurry electrode mixture to the current collector include a die coater method, a curtain coater method, and a spray coater method. Each method such as the gravure coater method, the flexo coater method, the knife coater method, the doctor blade method, and the reverse roll method can be used. Further, in the coating process, a plurality of coating methods may be used in combination. In the present invention, the density of the active material present on the current collector is preferably 1 g · cm ^{-3 to} 2.2 g · cm ^-3 , more preferably 1.3 g · cm ^-3 to 1. It is 9 g · cm ^-3 .

(3) Step of heating and drying the current collector after applying the electrode mixture The temperature for heating the electrode mixture applied on the current collector is usually 80 to 180 ° C. Further, the heating conditions such as the heating time can be appropriately set according to the coating amount and the volatilization rate of the electrode mixture. This heating is for volatilizing and drying the solvent in the electrode mixture. When the binder is polymerized by heating, a thermal polymerization initiator may be included in the electrode mixture. When the electrode mixture does not contain a solvent, it may be irradiated with energy rays such as ultraviolet light without heating in order to polymerize the binder. In this case, it is preferable to include a photopolymerization initiator in the electrode mixture.

Further, in the electrode manufacturing process of the present invention, following the above-mentioned operation, the electrode composed of the coating film and the current collector can be pressed under arbitrary conditions.

Hereinafter, each member used in the electrode manufacturing process will be described in more detail.

<Binder>
As the binder used in the present invention, known binders can be used. Specific examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), ethylene-propylene-diene copolymer (EPDM), styrene-butadiene rubber (SBR), and acrylonitrile butadiene rubber (NBR). , Styrene-isoprene copolymer, polymethylmethacrylate, polyacrylate, polyvinyl alcohol (PVA), carboxymethylcellulose (CMC), methylcellulose (MC), starch, polyvinylpyrrolidone, polyethylene (PE), polypropylene (PP), polyimide (PI) ), Polyacrylic acid and the like.

<Conductive aid>
The conductive auxiliary agent used in the present invention includes carbon materials such as natural graphite, artificial graphite, carbon black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon nanotubes, graphene, and needle coke; aluminum powder, Metal powders such as nickel powder; conductive metal oxides such as zinc oxide and titanium oxide can be mentioned. As described in the above-mentioned production method, this conductive auxiliary agent can also be mixed during the production of sulfur-modified polyacrylonitrile. The content of the conductive auxiliary agent in the electrode mixture is usually 0.01 to 50 parts by mass with respect to 100 parts by mass of the electrode active material.

<Lithium salt>
The lithium salt used in the present _{invention, LiClO 4, LiPF 6, LiBF} 4, LiCF 3 SO 3, LiSbF 6, LiAsF 6, LiAlCl 4, LiN (CF 3 SO 3) 2, LiC (CF 3 SO 3) 3, Examples thereof include LiC ₄ F ₄ SO ₃ and Li (C ₂ F ₅ SO ₂ ) ₂ N.

<Polymerization initiator>
The polymerization initiator used in the present invention is a thermal polymerization initiator or a photopolymerization initiator, and examples of the thermal polymerization initiator include AIBN, sodium persulfate, potassium persulfate, ammonium persulfate, lauroyl peroxide, and di-. 2-Ethylhexyl peroxydicarbonate, diisopropylbenzene hydroperoxide, cumene hydroperoxide, etc. Examples of photopolymerization initiators are α-carbonyl compounds, acidoin ethers, acidoin compounds, polynuclear quinone compounds, and triarylimidazoles. Dimer / p-aminophenylketone combination, aclysine and phenazine compounds, oxadiazole compounds and the like.

<Filler>
Examples of the filler used in the present invention include olefin polymers such as polyethylene and polypropylene; fiber materials such as glass fiber and carbon fiber; zeolite; Aerosil and the like.

<Solvent>
Examples of the solvent used in the present invention include propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, acetonitrile, propionitrile, tetrahydrofuran, 2-. Methyl tetrahydrofuran, dioxane, 1,3-dioxolane, nitromethane, N-methylpyrrolidone, N, N-dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N, N-dimethylaminopropylamine , Polyethylene oxide, tetrahydrofuran, dimethyl sulfoxide, sulfolane, γ-butyrolactone water, alcohol and the like. The amount of the solvent used is preferably 30 to 300 parts by mass, more preferably 50 to 200 parts by mass with respect to 100 parts by mass of the electrode active material.

<Current collector>
As the current collector, conductive materials such as titanium, titanium alloy, aluminum, aluminum alloy, copper, nickel, stainless steel, and nickel-plated steel are used. Examples of the shape of the current collector include a foil shape, a plate shape, a net shape, and the like, and the current collector may be either porous or non-porous. In addition, these conductive materials may be surface-treated in order to improve adhesion and electrical properties. The thickness of the current collector is not particularly limited, but is usually 1 to 100 μm.

The electrode for a secondary battery manufactured by the production method of the present invention is usually used as an electrode for a non-aqueous electrolyte secondary battery, but can also be used as an electrode for a primary battery. Examples of the non-aqueous electrolyte secondary battery include, but are not limited to, a lithium secondary battery and a lithium ion secondary battery.

Next, the method for manufacturing the secondary battery of the present invention using the electrodes manufactured by the manufacturing method of the present invention will be described in detail based on a preferred embodiment. Specifically, the non-aqueous electrolyte, the separator, and the exterior member excluding the above electrodes constituting the non-aqueous electrolyte secondary battery will be described. In the method for manufacturing a secondary battery of the present invention, the electrode for a secondary battery, the non-aqueous electrolyte, the separator, and the exterior member obtained by the method for manufacturing the electrode for a secondary battery of the present invention are assembled by a known method. The shape of the secondary battery is not particularly limited, and examples thereof include a coin-type secondary battery, a cylindrical secondary battery, a square-type secondary battery, and a laminated secondary battery.

<opposite pole>
The electrode for a secondary battery manufactured by the manufacturing method of the present invention can be used as a positive electrode and can also be used as a negative electrode. When the electrode for a secondary battery manufactured by the production method of the present invention is used as a positive electrode of a lithium ion secondary battery, an electrode having a known negative electrode active material as a negative electrode can be used. When the electrode for a secondary battery manufactured by the production method of the present invention is used as a negative electrode of a lithium ion secondary battery, an electrode having a positive electrode active material known as a positive electrode may be used as a positive electrode or a negative electrode.

Known negative electrode active materials include natural graphite, artificial graphite, non-graphitized carbon, easily graphitized carbon, lithium, lithium alloy, tin alloy, silicon alloy, silicon oxide, silicon, titanium oxide, iron oxide, manganese oxide, and oxidation. In addition to cobalt, nickel oxide, lead oxide, ruthenium oxide, tungsten oxide, and zinc oxide, composite oxides such as _{LiVO 2} , Li ₂ VO ₄ , and Li ₄ Ti ₅ O _{12 can be mentioned.}

Examples of known positive electrode active materials include lithium transition metal composite oxides, lithium-containing transition metal phosphoric acid compounds, and the like, and these may be mixed and used. As the transition metal of the lithium transition metal composite oxide, vanadium, titanium, chromium, manganese, iron, cobalt, nickel, copper and the like are preferable. Specific examples of the lithium transition metal composite oxide include a lithium cobalt composite oxide such _{as LiCoO 2} , a lithium nickel composite oxide such as _{LiNiO 2} , and a lithium manganese composite oxide such as _{LiMnO 2} , LiMn ₂ O ₄ , and Li ₂ MnO _3. Some of the transition metal atoms that are the main constituents of these lithium transition metal composite oxides are aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, lithium, nickel, copper, zinc, magnesium, gallium, zirconium, etc. Examples thereof include those substituted with other metals. Specific examples of the substituted ones include, for example, Li _1.1 Mn _1.8 Mg _0.1 O ₄ , Li _1.1 Mn _1.85 Al _0.05 O ₄ , LiNi _0.5 Co _0.2 Mn. _0.3 O ₂ , LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.80 Co _0.17 Al _0.03 O ₂ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiMn _{1. 8} Al _0.2 O ₄ , LiMn _1.5 Ni _0.5 O _{4, and the} like can be mentioned. The transition metal of the lithium-containing transition metal phosphoric acid compound is preferably vanadium, titanium, manganese, iron, cobalt, nickel or the like, and specific examples thereof include iron _{phosphates such as LiFePO 4} and phosphorus such as LiCoPO _4. Cobalt acids, some of the transition metal atoms that are the main constituents of these lithium transition metal phosphate compounds are aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, lithium, nickel, copper, zinc, magnesium, gallium, zirconium. , Niob, etc. replaced with other metals.

<Non-aqueous electrolyte>
Examples of the non-aqueous electrolyte include a liquid non-aqueous electrolyte prepared by dissolving the electrolyte in an organic solvent, a gel-like non-aqueous electrolyte in which a liquid electrolyte and a polymer material are combined, and the like.

As the electrolyte used for preparing the liquid non-aqueous electrolyte, for example, conventionally known lithium salts are used, for example, LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiN (CF ₃ SO _2). ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiB (CF ₃ SO ₃ ) ₄ , LiB (C ₂ O ₄ ) ₂ , LiBF ₂ (C ₂ O ₄ ), LiSbF ₆ , LiSiF _{5 , LiAlF 4} , LiSCN, Examples thereof include LiClO ₄ , LiCl, LiF, LiBr, LiI, _{LiAlF 4 , LiAlCl 4} , and derivatives thereof. Among these, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , and LiC ( CF ₃ SO _{2) 3} and LiCF ₃ derivatives of SO _3, and _LiC (CF 3 _{SO 2)} is preferably used at least one member selected from the group consisting of ₃ derivatives.

As the organic solvent used for preparing the liquid non-aqueous electrolyte used in the present invention, one or a combination of two or more of those usually used for non-aqueous electrolytes can be used. Specific examples thereof include saturated cyclic carbonate compounds, saturated cyclic ester compounds, sulfoxide compounds, sulfone compounds, amide compounds, saturated chain carbonate compounds, chain ether compounds, cyclic ether compounds, and saturated chain ester compounds.

Among the above organic solvents, saturated cyclic carbonate compounds, saturated cyclic ester compounds, sulfoxide compounds, sulfone compounds and amide compounds play a role of increasing the dielectric constant of non-aqueous electrolytes because of their high relative dielectric constants, and in particular, saturated cyclic carbonate compounds. Is preferable. Examples of such saturated cyclic carbonate compounds include ethylene carbonate, 1,2-propylene carbonate, 1,3-propylene carbonate, 1,2-butylene carbonate, 1,3-butylene carbonate, and 1,1,-dimethylethylene carbonate. And so on. Examples of the saturated cyclic ester compound include γ-butyrolactone, γ-valerolactone, γ-caprolactone, δ-hexanolactone, and δ-octanolactone. Examples of the sulfoxide compound include dimethyl sulfoxide, diethyl sulfoxide, dipropyl sulfoxide, diphenyl sulfoxide, thiophene and the like. Examples of the sulfone compound include dimethyl sulfone, diethyl sulfone, dipropyl sulfone, diphenyl sulfone, sulfolane (also referred to as tetramethylene sulfone), 3-methyl sulfolane, 3,4-dimethyl sulfolane, 3,4-diphenylmethyl sulfolane, and sulfolene. , 3-Methylsulfone, 3-Ethylsulforen, 3-Bromomethylsulfone and the like, and sulfolane and tetramethylsulfolane are preferable. Examples of the amide compound include N-methylpyrrolidone, dimethylformamide, dimethylacetamide and the like.
Among the above organic solvents, the saturated chain carbonate compound, the chain ether compound, the cyclic ether compound and the saturated chain ester compound can lower the viscosity of the non-aqueous electrolyte and increase the mobility of the electrolyte ions. It is possible to improve the battery characteristics such as output density. Further, since the viscosity is low, the performance of the non-aqueous electrolyte at low temperature can be improved, and among them, the saturated chain carbonate compound is preferable. Examples of such saturated chain carbonate compounds include dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), ethyl butyl carbonate, methyl-t-butyl carbonate, diisopropyl carbonate, and t-butyl propyl carbonate. And so on. Examples of the above-mentioned chain ether compound or cyclic ether compound include dimethoxyethane (DME), ethoxymethoxy ethane, diethoxy ethane, tetrahydrofuran, dioxolane, dioxane, 1,2-bis (methoxycarbonyloxy) ethane, 1,2. -Bis (ethoxycarbonyloxy) ethane, 1,2-bis (ethoxycarbonyloxy) propane, ethylene glycol bis (trifluoroethyl) ether, propylene glycol bis (trifluoroethyl) ether, ethylene glycol bis (trifluoromethyl) ether , Diethylene glycol bis (trifluoroethyl) ether and the like, and among these, dioxolane is preferable.
The saturated chain ester compound is preferably a monoester compound or a diester compound having a total of 2 to 8 carbon atoms in the molecule, and specific compounds include methyl formate, ethyl formate, methyl acetate, ethyl acetate, and the like. Propyl acetate, isobutyl acetate, butyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethyl acetate, ethyl trimethyl acetate, methyl malate, ethyl malonate, methyl succinate, ethyl succinate, 3- Methyl methoxypropionate, ethyl 3-methoxypropionate, ethylene glycol diacetyl, propylene glycol diacetyl and the like include methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, isobutyl acetate, butyl acetate, methyl propionate, and Ethyl propionate is preferred.

In addition, acetonitrile, propionitrile, nitromethane and derivatives thereof can also be used as the organic solvent used for preparing the liquid non-aqueous electrolyte.
The content of the electrolyte in the liquid non-aqueous electrolyte is preferably 0.5 to 3 mol / L, more preferably 0.8 to 1.8 mol / L in the organic solvent of the electrolyte.

In the gel-like non-aqueous electrolyte, the above-mentioned organic solvent can be used as the liquid electrolyte to be composited with the polymer material.
Can be mentioned.
Examples of the polymer material compounded with the liquid electrolyte include polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyethylene, polyethylene oxide (PEO) and the like.
The amount of the liquid electrolyte and the polymer compound used and the method of compounding are not particularly limited, and the amount of the liquid electrolyte and the polymer compound used and the method known in the art may be adopted.

As the non-aqueous electrolyte, an ionic liquid, a polymer solid electrolyte, an inorganic solid electrolyte, or the like may be used.

An ionic liquid is an organic salt that exists as a liquid at room temperature, and includes a compound that becomes a liquid by itself, a liquid that becomes a liquid when mixed with an electrolyte, and a liquid that becomes a liquid when dissolved in an organic solvent. ..
The polymer solid electrolyte is a solidified polymer material containing an electrolyte.
An inorganic solid electrolyte is a solid substance having ionic conductivity.

An electrolyte additive can be added to the non-aqueous electrolyte used in the method for producing a secondary battery of the present invention in order to improve the characteristics (improve battery life and safety). Examples of the type of electrolyte additive include siloxane-based compounds and organic compounds having an unsaturated bond. When the electrolyte additive is used, it is usually 0.01 to 10% by mass, preferably 0.1 to 5% by mass, based on the total amount of the non-aqueous electrolyte.

Further, a halogen-based, phosphorus-based, or other flame retardant can be appropriately added to the non-aqueous electrolyte used in the method for producing a secondary battery of the present invention in order to impart flame retardancy. If the amount of the flame retardant added is too small, a sufficient flame retardant effect cannot be exhibited, and if it is too large, not only the amount increasing effect commensurate with the blended amount cannot be obtained, but also the characteristics of the non-aqueous electrolyte are adversely affected. 1 to 50% by mass, preferably 3 to 10% by mass, based on the organic solvent constituting the non-aqueous electrolyte used in the method for producing a secondary battery of the present invention. Is even more preferable.

<Separator>
In the secondary battery manufactured by the method for manufacturing a secondary battery of the present invention, it is preferable to use a separator between the positive electrode and the negative electrode. As the separator, a polymer microporous or non-woven film usually used as a separator for a secondary battery can be used without particular limitation. Examples of the film include polyethylene, polypropylene, polyvinylidene fluoride, polyvinylidene chloride, polyacrylonitrile, polyacrylamide, polytetrafluoroethylene, polysulfone, polyethersulfone, polycarbonate, polyamide, polyimide, and poly such as polyethylene oxide and polypropylene oxide. A film composed of ethers, various celluloses such as carboxymethyl cellulose and hydroxypropyl cellulose, polymer compounds and derivatives thereof mainly composed of poly (meth) acrylic acid and various esters thereof, and copolymers and mixtures thereof. And so on. These films may be used alone, or these films may be laminated and used as a multi-layer film. Further, various additives may be used in these films, and the type and content thereof are not particularly limited. Among these films, a film made of polyethylene, polypropylene, polyvinylidene fluoride, or polysulfone is preferably used for the secondary battery manufactured by the method for manufacturing a secondary battery.

As these films, a non-woven fabric-like film or a microporous film is used so that the electrolyte permeates and ions easily permeate. The microporous method includes a "phase separation method" in which a solution of a polymer compound and a solvent is microphase-separated while forming a film, and the solvent is extracted and removed to make the solvent porous, and a high draft of the molten polymer compound. The "stretching method", in which the crystals are extruded and then heat-treated to arrange the crystals in one direction and further stretched to form gaps between the crystals to make them porous, is appropriately selected depending on the film to be used.

<Exterior member>
As the exterior member, a laminated film or a metal container can be used. The thickness of the exterior member is usually 0.5 mm or less, preferably 0.2 mm or less. Examples of the shape of the exterior member include a flat type (thin type), a square type, a cylindrical type, a coin type, and a button type.

As the laminated film, a multilayer film having a metal layer between resin films can also be used. The metal layer is preferably an aluminum foil or an aluminum alloy foil for weight reduction. As the resin film, for example, a polymer material such as polypropylene (PP), polyethylene (PE), nylon, or polyethylene terephthalate (PET) can be used. The laminated film can be sealed in the shape of an exterior member by heat fusion.

The metal container can be formed from, for example, aluminum or an aluminum alloy. As the aluminum alloy, an alloy containing elements such as magnesium, zinc, and silicon is preferable. By reducing the content of transition metals such as iron, copper, nickel, and chromium to 1% or less in aluminum or aluminum alloy, long-term reliability and heat dissipation in a high temperature environment can be dramatically improved.

In the secondary battery manufactured by the method for manufacturing the secondary battery, the positive electrode material, the non-aqueous electrolyte and the separator are subjected to a phenol-based antioxidant, a phosphorus-based antioxidant, and a thioether-based oxidation for the purpose of further improving safety. Inhibitors, hindered amine compounds and the like may be added.

As described in the description of the exterior member, the secondary battery manufactured by the method for manufacturing a secondary battery having the above configuration is not particularly limited in its shape, and may have various shapes such as a coin type, a cylindrical type, and a square type. Can be in the shape of. FIG. 2 shows an example of a coin-type battery of the non-aqueous electrolyte secondary battery of the present invention, and FIGS. 3 and 4 show an example of a cylindrical battery.

In the coin-type non-aqueous electrolyte secondary battery 10 shown in FIG. 2, 1 is a positive electrode capable of emitting lithium ions, 1a is a positive electrode current collector, and 2 is a carbonaceous material capable of storing and releasing lithium ions released from the positive electrode. Negative electrode, 2a is a negative electrode current collector, 3 is a non-aqueous electrolyte, 4 is a stainless steel positive electrode case, 5 is a stainless steel negative electrode case, 6 is a polypropylene gasket, and 7 is a polyethylene separator.

Further, in the cylindrical non-aqueous electrolyte secondary battery 10'shown in FIGS. 3 and 4, 11 is a negative electrode, 12 is a negative electrode current collector, 13 is a positive electrode, 14 is a positive electrode current collector, and 15 is a non-aqueous electrolyte. 16 is a separator, 17 is a positive electrode terminal, 18 is a negative electrode terminal, 19 is a negative electrode plate, 20 is a negative electrode lead, 21 is a positive electrode plate, 22 is a positive electrode lead, 23 is a case, 24 is an insulating plate, 25 is a gasket, and 26 is a safety valve. , 27 are PTC elements.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited in any way by the following examples and the like. _{The average particle size in the examples indicates D 50} (median diameter) measured by a laser diffraction / light scattering method.

Example 1
<Preparation of raw material powder>
Polyacrylonitrile powder (manufactured by Sigma-Aldrich) and sulfur powder (manufactured by Kanto Chemical Co., Inc.) were mixed in a mass ratio of 1: 3 between the former and the latter to prepare a raw material powder W. The average particle size of the polyacrylonitrile powder was 10 μm, and the average particle size of the sulfur powder was 10 μm.

<Manufacturing of sulfur-modified polyacrylonitrile>
Sulfur-modified polyacrylonitrile was produced using the production apparatus 10A of FIG.
From the raw material supply device 31 provided in the raw material supply unit 30, 20 g of the powder W was guided to the sieving device 32, and the powder W was sieved by the sieving device 32 so that the average particle size thereof was 10 μm. The sieved powder W was sent out into the heating unit 40 heated to 400 ° C. by the nitrogen gas supplied from the gas supply device 60 through the second supply passage 61b and heated. When the sieved powder W is heated by the heating unit 40, the amount of nitrogen gas guided from the gas supply device 60 of the manufacturing apparatus 10A through the first supply passage 61a into the heating unit 40 from the cooling unit 50, and the gas. The amount of nitrogen gas guided from the supply device 60 to the guide pipe 33 in the raw material supply section 30 through the second supply path 61b was adjusted, and the powder W was heated in the heating section 40 at 400 ° C. for 30 seconds. Then, the powder W heated by the heating unit 40 was guided into the cooling unit 50 and cooled to 40 ° C. to obtain the sulfur-modified polyacrylonitrile of Example 1. The sulfur-modified polyacrylonitrile of Example 1 had an average particle size of 12 μm and contained 39% by mass of bound sulfur. The sulfur-modified polyacrylonitrile of Example 1 had a sulfur solid content of 0.5% by mass. No adhesion of sulfur-modified polyacrylonitrile was observed inside the device. The sulfur content in sulfur-modified polyacrylonitrile was measured by elemental analysis. The content of the sulfur solid in the sulfur-modified polyacrylonitrile was measured by thermogravimetric analysis. The thermogravimetric analysis was performed in a nitrogen gas atmosphere in a temperature range of 50 ° C. to 900 ° C. at a sweep rate of 10 ° C. per minute.

Example 2
A sulfur-modified polyacrylonitrile was obtained in the same manner as in Example 1 except that a sulfur powder having an average particle size of 20 μm and a polyacrylonitrile powder having an average particle size of 20 μm were used as the raw material powder W.

The obtained sulfur-modified polyacrylonitrile had an average particle size of 24 μm and contained 39% by mass of bound sulfur. The sulfur-modified polyacrylonitrile of Example 2 had a sulfur solid content of 0.5% by mass. No adhesion of sulfur-modified polyacrylonitrile was observed inside the device. The sulfur content in sulfur-modified polyacrylonitrile was measured by elemental analysis. The content of the sulfur solid in the sulfur-modified polyacrylonitrile was measured by thermogravimetric analysis. The thermogravimetric analysis was performed in a nitrogen gas atmosphere in a temperature range of 50 ° C. to 900 ° C. at a sweep rate of 10 ° C. per minute.

Comparative Example 1
Sulfur-modified polyacrylonitrile was produced using the production apparatus of FIG. 1 of Patent Document 1.
The same powder W used in Example 1 was used as a raw material. 20 g of powder W was placed in a reaction vessel. Then, the reaction vessel was heated with a heater, and the powder W was reacted at 400 ° C. for 10 minutes to obtain a sulfur-modified polyacrylonitrile. The heating was performed while discharging the hydrogen sulfide generated by the reaction from the opening for discharging the hydrogen sulfide. Further, at the initial stage of heating, nitrogen gas was introduced from the opening for introducing the inert gas into the reaction vessel to create a non-oxidizing atmosphere in the reaction vessel, and then the temperature of the powder W became 100 ° C. At that point, the opening for introducing the inert gas was closed. As a result, nitrogen gas was discharged together with the generated hydrogen sulfide, and the inside of the reaction vessel became a sulfur vapor atmosphere. That is, when the powder W was reacted at 400 ° C. for 10 minutes, the inside of the reaction vessel had a sulfur vapor atmosphere. Since the obtained sulfur-modified polyacrylonitrile contained a sulfur solid, it was further heat-treated at 450 ° C. to obtain the sulfur-modified polyacrylonitrile of Comparative Example 1. The sulfur-modified polyacrylonitrile of Comparative Example 1 had an average particle size of 1 mm or more and contained 38% by mass of bound sulfur. The sulfur-modified polyacrylonitrile of Comparative Example 1 had a sulfur solid content of 1% by mass. A part of sulfur-modified polyacrylonitrile was attached to the inside of the apparatus. The sulfur content in sulfur-modified polyacrylonitrile was measured by elemental analysis. The content of the sulfur solid in the sulfur-modified polyacrylonitrile was measured by thermogravimetric analysis. The thermogravimetric analysis was performed in a nitrogen gas atmosphere in a temperature range of 50 ° C. to 900 ° C. at a sweep rate of 10 ° C. per minute.

Comparative Example 2
Using the same raw material powder W as in Example 2, a sulfur-modified polyacrylonitrile was produced in the same manner as in Comparative Example 1 using the production apparatus of FIG. 1 of Patent Document 1. Since the obtained sulfur-modified polyacrylonitrile contained a sulfur solid, it was further heat-treated at 450 ° C. to obtain the sulfur-modified polyacrylonitrile of Comparative Example 2. The sulfur-modified polyacrylonitrile of Comparative Example 2 had an average particle size of 1 mm or more and contained 37% by mass of bound sulfur. The sulfur-modified polyacrylonitrile of Comparative Example 2 had a sulfur solid content of 1% by mass. A part of sulfur-modified polyacrylonitrile was attached to the inside of the apparatus. The sulfur content in sulfur-modified polyacrylonitrile was measured by elemental analysis. The content of the sulfur solid in the sulfur-modified polyacrylonitrile was measured by thermogravimetric analysis. The thermogravimetric analysis was carried out in a nitrogen gas atmosphere in a temperature range of 50 ° C. to 900 ° C. at a sweep heating rate of 10 ° C. per minute.

Example 3
<Manufacturing of non-aqueous electrolyte secondary batteries>
<Manufacturing of electrodes>
79.0 parts by mass of sulfur-modified polyacrylonitrile obtained in Example 1 as an active material, 1.5 parts by mass of acetylene black (manufactured by Denki Kagaku Kogyo) as a conductive auxiliary agent, carbon nanotubes (manufactured by Showa Denko, trade name VGCF) 1.5 parts by mass and 18.0 parts by mass of polyimide (manufactured by IST) as a binder were mixed with 113 parts by mass of NMP and dispersed to form a slurry. This slurry was applied to a stainless steel current collector, dried at 120 ° C., and further heat-treated at 350 ° C. Then, this electrode was cut to a predetermined size to prepare a disk-shaped electrode.

<Preparation of non-aqueous electrolyte solution>
_{An electrolyte solution was prepared by dissolving LiPF 6} at a concentration of 1 mol / L in a mixed solvent consisting of 30% by volume of ethylene carbonate, 30% by volume of dimethyl carbonate and 40% by volume of ethylmethyl carbonate.

<Battery assembly>
The obtained disc-shaped electrode and lithium metal as its counter electrode were used, and a glass filter was sandwiched as a separator and held in the case. After that, the non-aqueous electrolyte solution prepared above is injected into the case, and the case is sealed and sealed to manufacture the non-aqueous electrolyte secondary battery (φ20 mm, thickness 3.2 mm, coin type) of Example 2. did.

Example 4
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 3 except that an electrode was produced using the sulfur-modified polyacrylonitrile obtained in Example 2.

Comparative Example 3
79.0 parts by mass of sulfur-modified polyacrylonitrile obtained in Comparative Example 1 as an active material, 1.5 parts by mass of acetylene black (manufactured by Denki Kagaku Kogyo) as a conductive auxiliary agent, carbon nanotube (manufactured by Showa Denko, trade name VGCF) 1 5.5 parts by mass and 18.0 parts by mass of polyimide (manufactured by IST) as a binder were mixed with 113 parts by mass of NMP, but the sulfur-modified polyacrylonitrile had a large particle size and did not form a slurry. ..
Therefore, the sulfur-modified polyacrylonitrile obtained in Comparative Example 1 was pulverized using a pulverizer so that its average particle size was 12 μm, and used as an active material. A non-aqueous electrolyte secondary battery of Comparative Example 3 was obtained in the same manner as in Example 3 except that the crushed sulfur-modified polyacrylonitrile was used.

Comparative Example 4
A non-aqueous electrolyte secondary battery was produced in the same manner as in Comparative Example 3 except that an electrode was produced using the sulfur-modified polyacrylonitrile obtained in Comparative Example 2. The sulfur-modified polyacrylonitrile obtained in Comparative Example 2 did not form a slurry as it was, and was pulverized using a pulverizer to an average particle size of 12 μm and used as an active material.

Comparative Example 5
A non-aqueous electrolyte secondary battery was produced in the same manner as in Comparative Example 3 except that the sulfur-modified polyacrylonitrile obtained in Comparative Example 1 was used without heat treatment at 450 ° C. The sulfur-modified polyacrylonitrile before heat treatment at 450 ° C. obtained in Comparative Example 1 did not form a slurry as it was, and was pulverized using a pulverizer so that the average particle size was 12 μm, and used as an active material. ..

The cycle capacity retention rate of the non-aqueous electrolyte secondary batteries of Examples 3 and 4 and Comparative Examples 3, 4 and 5 was evaluated by the following test method.

<Cycle capacity maintenance rate test method>
The non-aqueous electrolyte secondary battery was placed in a constant temperature bath at 25 ° C., discharged to 1.0 V at a discharge current of 60 mA / g, and charged to 3.0 V at a charging current of 60 mA / g. After that, the operation of constant current discharging to 1.0 V at a discharge current of 600 mA / g and constant current charging to 3.0 V at a charging current of 600 mA / g was performed 10 times, and the eleventh operation was performed up to 1.0 V at a discharge current of 60 mA / g. It was discharged with a constant current and charged with a constant current of up to 3.0 V at a charging current of 60 mA / g. The 11th charge capacity was defined as the charge capacity after the cycle test, and the charge capacity retention rate (%) was determined as the ratio of the charge capacity after the cycle test when the initial charge capacity was 100, as shown in the following formula. ..
Charge capacity retention rate (%) = [(Charge capacity after cycle test) / (Initial charge capacity)] x 100

The non-aqueous electrolyte secondary batteries of Examples 3 and 4 had a charge capacity retention rate of 89% and 91%, respectively. On the other hand, the non-aqueous electrolyte secondary batteries of Comparative Examples 3, 4 and 5 had charge capacity retention rates of 85%, 85% and 71%, respectively. From the above results, it was clarified that the sulfur-modified polyacrylonitrile obtained by the production method of the present invention is useful as an active material for electrodes.

1 Positive electrode 1a Positive electrode current collector 2 Negative electrode 2a Negative electrode current collector 3 Electrode 4 Positive electrode case 5 Negative electrode case 6 Gasket 7 Separator 10 Coin-type non-aqueous electrolyte secondary battery 10'Cylindrical non-aqueous electrolyte secondary battery 11 Negative electrode 12 Negative electrode current collector 13 Positive electrode 14 Positive electrode current collector 15 Electrode 16 Separator 17 Positive electrode terminal 18 Negative electrode terminal 19 Negative electrode plate 20 Negative electrode lead 21 Positive electrode plate 22 Positive electrode lead 23 Case 24 Insulation plate 25 Gasket 26 Safety valve 27 PTC element 10A Sulfur-modified polyacrylonitrile Manufacturing equipment 30 Raw material supply unit 31 Raw material supply equipment 32 Sifting device 33 Guide tube 40 Heating unit 40A Extension unit 41 Heating device 50 Cooling unit 51 Guide member 60 Gas supply device 61a First supply path 61b Second supply path 62a First Flow control valve 62b Second flow control valve 63 Control device 70 Exhaust gas unit 71 Exhaust gas treatment device 72 Pressure measuring device D Insulation material W Powder

Claims (7)

The raw material supply unit that supplies the powder of the raw material containing the polyacrylonitrile powder and the sulfur powder, the heating unit that heat-treats the powder supplied from the raw material supply unit and dropped, and the heat-treated powder are cooled. A method for producing sulfur-modified polyacrylonitrile using a drop-type powder processing apparatus equipped with a cooling unit.
The step of sieving the raw material powder in the raw material supply unit and adjusting the average particle size of the raw material powder supplied to the heating unit, and supplying gas from the lower side and / or the upper side of the heating unit in the heating unit. A method for producing a sulfur-modified polyacrylonitrile, which comprises a step of controlling the falling speed of the falling powder. A claim for using the drop-type powder treatment device, which is provided on the upper side of the heating section with an exhaust gas section for discharging the exhaust gas in the heating section to the outside, and the exhaust gas section is provided with an exhaust gas treatment device for detoxifying the exhaust gas. Item 3. The method for producing a sulfur-modified polyacrylonitrile according to Item 1. The invention according to claim 1 or 2, wherein the falling powder processing apparatus is used, which has a mechanism for controlling the falling speed of the powder falling in the heating portion by the gas supplied from the lower side and / or the upper side of the heating portion. Method for producing sulfur-modified polyacrylonitrile. Control that adjusts the amount of gas guided into the heating unit according to the exhaust gas unit having a pressure measuring device for measuring the pressure in the heating unit and the pressure in the heating unit measured by the pressure measuring device. The method for producing a sulfur-modified polyacrylonitrile according to claim 2, wherein the drop-type powder processing apparatus having the apparatus is used. The method for producing sulfur-modified polyacrylonitrile according to any one of claims 1 to 4, wherein the raw material further contains a conductive auxiliary agent. A method for producing an electrode for a secondary battery, which comprises a step of producing sulfur-modified polyacrylonitrile by the method for producing sulfur-modified polyacrylonitrile according to any one of claims 1 to 5. A method for manufacturing a secondary battery, which comprises a step of manufacturing an electrode for a secondary battery by the method for manufacturing an electrode for a secondary battery according to claim 6.

Images