KR20230038990A - Manufacturing system of electrode dry coating for lithium secondary battery and method for manufacturing electrode dry coating using the same - Google Patents

Abstract

The present invention relates to an electrode dry coating material for a lithium secondary battery, a system for continuously manufacturing the electrode dry coating material for a lithium secondary battery, and a manufacturing method thereof. The electrode dry coating material for a lithium secondary battery is manufactured by using coal-based or petroleum-based pitch as a raw material. A softening point of the electrode dry coating material is in the range of 230 to 280℃, a toluene insoluble content is in the range of 45 to 55%, and a carbonization yield is in the range of 65 to 75%.

Description

Manufacturing system of electrode dry coating material for lithium secondary battery and manufacturing method of electrode dry coating material using the same

The present invention relates to an electrode dry coating material for a lithium secondary battery manufactured using coal-based or petroleum-based pitch as a raw material, and a system and manufacturing method for continuously manufacturing the electrode dry coating material for a lithium secondary battery. More specifically, it relates to a manufacturing device capable of continuously manufacturing an electrode dry coating material for a lithium secondary battery by using coal-based or petroleum-based solid pitch as a raw material and going through a multi-stage low-temperature heat treatment process, and a method of manufacturing an electrode dry coating material using the same .

Lithium secondary batteries are an essential element in small devices such as cell phones and laptop computers, and demand for lithium secondary batteries has recently increased as a power source for hybrid vehicles and electric vehicles.

A lithium secondary battery consists of a positive electrode, a negative electrode, an electrolyte and a separator that provide a path for lithium ions to move between the positive electrode and the negative electrode, and generates electricity by oxidation and reduction reactions when lithium ions are inserted/deintercalated from the positive electrode and the negative electrode. generate energy Since most graphite raw materials used as negative electrode materials for lithium secondary batteries are in the form of powder and most of the natural graphite particles are in the form of plate-like particles, they cause deterioration in battery performance due to low packing density and high specific surface area. In particular, since the laminated structure is exposed at the corner of the particle, when graphite is used as an anode material for a secondary battery, dendrites are formed on the surface of the anode material, resulting in damage during charging and discharging.

In order to overcome this problem, a method of coating an electrode of a lithium secondary battery has been proposed as an alternative.

On the other hand, Patent Document 1 discloses a method of manufacturing an anode material including a carbon coating layer on the surface of graphite by coating an amorphous carbon precursor with a diluted organic solvent and then heat-treating it at about 400 ° C. in an inert atmosphere. there is. Specifically, a manufacturing method of forming a carbon coating layer by wet coating using an ethanol solution diluted with 6% by weight of coal-based pitch and then heat-treating at a temperature of 400 ° C. for 5 hours or more in an argon atmosphere was disclosed.

In addition, Patent Document 2 discloses a negative electrode in which a carbon-based thin film is formed on at least one surface of a lithium metal layer and a manufacturing method thereof. Specifically, a method for manufacturing a negative electrode in which a carbon-based thin film is coated on the surface of a lithium metal layer using a dry deposition method is disclosed, and hard carbon with amorphous carbon forming a carbon-based thin film, mesocarbon microbeads fired at 1500 ° C or less, and mesophase Pitch-based carbon fibers are disclosed.

Patent Document 1 uses relatively inexpensive coal-based pitch as a coating material, but there are problems with environmental pollution due to the use of a large amount of organic solvent in the coating process and complicated processes such as heat treatment in an inert atmosphere for a long time, Patent Document 1 2 discloses a dry coating method that can reduce environmental pollution without using an organic solvent, but has a problem in that the production cost is very high because the carbon layer in the form of a thin film must be coated by thermally decomposing hydrocarbon gas at a high temperature of 1000 ° C or higher. .

Therefore, there is an urgent need to research a manufacturing device and manufacturing method capable of continuously producing an electrode dry coating material for a lithium secondary battery at low cost.

Korean Registered Patent Publication No. 10-1557559 (2015.09.25) Korean Patent Publication No. 2018-0103725 (2018.09.19)

The present invention is to provide an eco-friendly lithium secondary battery electrode dry coating material manufacturing system that can continuously and inexpensively produce an electrode dry coating material for a lithium secondary battery using coal-based or petroleum-based solid pitch as a raw material, and has excellent production efficiency.

In addition, the present invention is to provide a method for manufacturing an electrode dry coating material for a lithium secondary battery capable of continuously manufacturing the electrode dry coating material using the manufacturing system.

The present invention, produced using coal-based or petroleum-based pitch as a raw material, has a softening point in the range of 230 to 280 ° C, a toluene insoluble content in the range of 45 to 55%, and a carbonization yield of 65 to 75% For lithium secondary batteries It relates to a system and manufacturing method for continuously manufacturing an electrode dry coating material for a lithium secondary battery using an electrode dry coating material and coal-based or petroleum-based pitch as raw materials.

According to the present invention, the manufacturing system of electrode dry coating material for lithium secondary battery can continuously and stably produce high-quality electrode dry coating material under temperature conditions of 500 ℃ or less using low-cost pitch raw materials, thereby lowering the overall production cost. It has the advantage of increasing economic efficiency.

According to the present invention, the manufacturing system of the electrode dry coating material for a lithium secondary battery has a configuration using gas circulation, and is an eco-friendly system capable of minimizing external discharge of pollutants.

1 is a schematic diagram of a manufacturing system for a dry coating material for an electrode for a lithium secondary battery according to the present invention.
2 is a schematic diagram of a method for manufacturing an electrode dry coating material for a lithium secondary battery according to the present invention.
3 shows the results of SEM analysis of the negative electrode material not coated with the coating material.
Figure 4a shows the results of SEM analysis of the negative electrode material coated with a dry coating material having an average particle diameter D (50) of 3 μm or less.
Figure 4b shows the results of SEM analysis of the negative electrode material coated with a dry coating material having an average particle diameter D (50) of 5 μm or less.

Terms such as first, second and third are used to describe, but are not limited to, various parts, components, regions, layers and/or sections. These terms are only used to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Accordingly, a first part, component, region, layer or section described below may be referred to as a second part, component, region, layer or section without departing from the scope of the present invention.

The terminology used herein is only for referring to specific embodiments and is not intended to limit the present invention. As used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite. The meaning of "comprising" as used herein specifies particular characteristics, regions, integers, steps, operations, elements and/or components, and the presence or absence of other characteristics, regions, integers, steps, operations, elements and/or components. Additions are not excluded.

When a part is referred to as being “on” or “on” another part, it may be directly on or on the other part or may be followed by another part therebetween. In contrast, when a part is said to be “directly on” another part, there is no intervening part between them.

Although not defined differently, all terms including technical terms and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Terms defined in commonly used dictionaries are additionally interpreted as having meanings consistent with related technical literature and currently disclosed content, and are not interpreted in ideal or very formal meanings unless defined.

1 is a schematic diagram of a manufacturing system for a dry coating material for a lithium secondary battery according to the present invention, and a manufacturing system for a dry coating material for a lithium secondary battery according to an embodiment of the present invention will be described with reference to FIG. 1 .

The manufacturing system of a dry coating material for an electrode according to an embodiment of the present invention includes a raw material supply unit 100, a preheating unit 200, a reaction unit 300, a forming unit 400, a tar bath 500, and a refining unit 600 ) may be included.

First, the raw material supply unit 100 will be described in detail.

The raw material supply unit 100 may mainly include a raw material storage tank and a raw material transfer device. The raw material storage tank can accommodate a predetermined amount of carbon-containing solid powder, may have a closed structure in the form of a hopper, and the shape is not particularly limited as long as it can stably accommodate the raw material. In the present invention, the carbon-containing solid powder stored in the raw material storage tank may be coal-based or petroleum-based solid pitch, specifically, has a softening point of 105 to 125 ° C, a toluene insoluble content of 1% or less, and a carbonization yield of 45 ~ 55%, an H / C atomic ratio of 0.7 to 1.0, a total aromatic proportion of 50 to 55%, and a sulfur component content of 0.3% or less. Here, the carbonization yield means the yield of residual material when heat treatment is performed under the condition of 1000° C. in an inert atmosphere.

Meanwhile, a raw material transfer device is provided at the bottom of the raw material storage tank to supply the raw material stored in the raw material storage tank to the preheating unit 200 described later. Here, the raw material conveying device may be a vacuum conveying device, and a quantitative storage tank capable of storing a certain amount of raw material is attached to the top of the vacuum conveying device. The raw material in a powder state is transferred to the storage tank through the suction port of the storage tank by a suction device. When a certain amount of raw material is transferred into the storage tank, the inlet is closed, and a valve located at the bottom of the storage tank is opened to supply the raw material to the downstream equipment.

In addition, the raw material transfer device may be a lock-hopper type, a screw type or a conveyor type, and is not particularly limited as long as it can stably supply the powdered raw material to the preheating unit 200 described later.

On the other hand, in order to solve the problem of non-uniform supply of raw materials due to phenomena such as agglomeration of raw materials during the transfer process, a vibrating member such as vibration may be additionally provided. Here, the raw material transfer device may be configured in a closed structure between the raw material storage tank and the preheating unit 200 to be described later. This is advantageous in preventing secondary environmental pollution caused by dust scattering during the raw material transfer process.

Next, the preheating unit 200 will be described.

The preheating unit 200 according to an embodiment of the present invention may include a preheating tank and a temperature controller. Here, the preheating tank may be a batch reactor or a continuous-stirred tank reactor (CSTR), and the material contained therein may be retained for a predetermined time. A temperature controller is provided at the lower part of the preheating tank to heat the preheating tank at a predetermined temperature increase rate and maintain a constant temperature. In this case, the temperature controller may include a heater and a temperature controller. The rate of temperature increase inside the preheating tank by the temperature controller may be 1 °C/min to 20 °C/min, and specifically 5 °C/min to 15 °C/min. When the temperature increase rate is greater than 20° C./min, it is difficult to control the internal temperature of the preheating tank, and a temperature gradient may occur inside the preheating tank, and the temperature gradient increases as the capacity of the preheating tank increases. On the other hand, if the heating rate is less than 1 ° C./min, the heating time becomes longer, resulting in poor economic feasibility.

Meanwhile, the temperature deviation inside the preheating tank may be controlled to be 20° C. or less. This is advantageous for obtaining a molten raw material of uniform quality.

In addition, a stirrer is provided inside the preheating tank to uniformly stir the raw material accommodated in the preheating tank. Here, the stirring speed of the stirrer may be 50 rpm to 300 rpm, specifically 100 rpm to 200 rpm. Here, when the stirring speed is less than 50 rpm, sufficient stirring of the internal material may not be achieved, and thus, uneven quality may occur due to a temperature gradient. In addition, when the stirring speed is greater than 300 rpm, there is a problem in that the liquid level of the molten material inside the preheating tank rises and can be discharged to the outside through the discharge port of the preheating tank.

Meanwhile, the linear speed of the agitator of the preheating tank may be 250 m/s to 1500 m/s, specifically 500 m/s to 1000 m/s.

In addition, a high voltage transformer may be included to shield the high voltage applied to the preheating tank from being transmitted to the temperature controller. The high voltage transformer can prevent operation interruption, which is advantageous for the entire manufacturing system to stably and continuously operate.

Here, a sliding valve is provided at the rear end of the preheating tank, and materials generated in the preheating tank can be discharged to a downstream facility through opening and closing of the sliding valve. Specifically, when the sliding valve is opened, a high-temperature liquid pump located behind the sliding valve may be operated by a control unit. Liquid material generated in the preheating tank is supplied to a downstream facility through the high-temperature liquid pump, and gaseous material such as VOC is supplied to a downstream purification unit through a pipe communicating with the preheating tank.

In addition, in the present invention, a high-temperature liquid pump may be positioned between the preheating tank of the preheating unit 200 and the high-temperature reactor 310 of the reaction unit 300 described later. Although not shown in FIG. 1, the high-temperature liquid pump is provided with a heater to maintain a temperature of 300° C. or higher. The high-temperature liquid pump is electrically connected to a control unit, and the control unit can control operation start and stop and molten raw material supply amount. When the molten raw material supplied to the first reactor 311, which will be described later, reaches a predetermined height, the control unit controls the high-temperature liquid pump to control the high-temperature liquid pump by sending an electrical signal from the level sensor provided inside the first reactor 311. 1 The supply of the molten raw material to the reactor 311 may be stopped. In addition, the control unit may operate the high-temperature liquid pump to supply the molten raw material to the second reactor 312 described later. Here, a three-way control valve may be located in the molten raw material transfer pipe connected to the rear end of the high-temperature liquid pump. The control unit may control opening and closing of the control valve for each position to alternately supply the molten raw material discharged from the high-temperature liquid pump to the first reactor 311 or the second reactor 312 .

Next, the reaction unit 300 will be described.

The reaction unit 300 according to an embodiment of the present invention may include a high-temperature reactor 310 and a stabilization tank 320.

The molten raw material generated in the preheating tank is supplied to the reaction tank 310, and a polycondensation reaction may be performed under a predetermined temperature condition. Although not shown in FIG. 1, the high-temperature reactor 310 is provided with a reactor heater and a reactor temperature controller to heat the inside of the high-temperature reactor 310 at a predetermined temperature increase rate, and also, the inside of the high-temperature reactor 310 It can be maintained at a predetermined temperature. In the present invention, the reactor heater may be an electrical heating method, and may include a power supply transformer for supplying electricity to the reactor heater. The supply voltage of the transformer for power supply may be in the range of 5 to 33 Kv.

The heating rate of the high-temperature reactor 310 by the reactor heater may be 0.5°C/min to 5°C/min or less, specifically 0.5°C/min to 2°C/min, and more specifically 1°C/min. can be min. Stable polycondensation reaction proceeds in the above temperature increase rate range to efficiently produce high-quality products. However, if the temperature increase rate is less than 1 ° C./min, the temperature increase time becomes longer, which may cause overreaction of the reactants and lower overall productivity. There is a problem, and if the temperature increase rate is higher than 5 ° C./min, there is a problem that overheating may occur.

Here, one or more temperature sensors for measuring the internal temperature of the high-temperature reactor 310 may be provided, and the temperature sensors may be electrically connected to the controller. The control unit receiving measurement data from the temperature sensor controls the reactor heater to maintain the inside of the high-temperature reactor 310 at a constant temperature.

On the other hand, when the internal temperature of the high-temperature reactor 310 is higher than 500°C, it is important to set the temperature below 500°C because solidification of the reactants may occur rapidly.

In addition, the reactants accommodated in the high-temperature reactor 310 may stay within 6 hours, including the temperature raising process, and may specifically stay for 4 to 6 hours. When the temperature of the high-temperature reactor 310 is less than 350° C., it is difficult to efficiently perform the polycondensation reaction, and when it is greater than 500° C., a non-uniform product may be produced due to rapid reaction at high temperature. In addition, when the residence time is less than 4 hours, sufficient polycondensation reaction is difficult to proceed, which is disadvantageous to product quality control, and when the residence time is longer than 6 hours, it is difficult to manufacture a product having an appropriate softening point and toluene insoluble content.

Meanwhile, a discharging means is provided at the rear end of the high-temperature reactor 310 to discharge the generated material to the outside and also to adjust the residence time inside. The discharge unit is electrically connected to a control unit, and the control unit can control the amount of generated material by adjusting the degree of opening and closing of the discharge unit. Here, the discharge means may be a sliding valve or a control valve.

In addition, although not shown in FIG. 1 , a stirrer is provided inside the high-temperature reactor 310 to uniformly stir the material accommodated in the high-temperature reactor 310 under high-temperature conditions.

Here, the stirring speed of the stirrer may be 50 rpm to 300 rpm, specifically 100 rpm to 200 rpm. Here, if the stirring speed is less than 50 rpm, uniform mixing of the internal materials may not be achieved, and thus the temperature gradient inside the high-temperature reactor 310 may increase. In addition, when the stirring speed is greater than 300 rpm, there is a problem in that the liquid level of the product material inside the high-temperature reactor 310 rises and is discharged to the outside through the outlet of the high-temperature reactor 310.

Meanwhile, the shape of the stirrer of the high-temperature reactor 310 may be a paddle type, and the diameter may be 80% to 90% of the inner diameter of the high-temperature reactor 310, and may be specifically about 85%. At this time, the linear speed of the stirrer may be 250m/s to 1500m/s, specifically 500m/s to 1000m/s.

In addition, in order to efficiently discharge low-molecular gaseous hydrocarbon materials such as volatile organic compounds (VOCs) that may be generated during the polycondensation reaction in the high-temperature reactor 310 to the outside of the high-temperature reactor 310, the high-temperature reactor 310 ) The internal pressure may be in the range of 0.090 MPa to 0.110 MPa, and more specifically in the range of 0.098 MPa to 0.107 MPa. This is to prevent the residual of low molecular weight components and/or gaseous components generated during the reaction of materials accommodated in the high-temperature reactor 310 .

In addition, oxidizing substances such as oxygen are introduced into the high-temperature reactor 310 to prevent participation in the polycondensation reaction, and gaseous hydrocarbon substances such as volatile organic compounds (VOCs) are mixed with oxygen at high temperature to cause explosion due to rapid reaction. In order to prevent accidents, etc., an inert atmosphere may be maintained by supplying an inert gas into the high-temperature reactor 310 . Here, the injected inert gas may be high-purity nitrogen gas, and is not particularly limited as long as the inside of the high-temperature reactor 310 can be maintained in an inert atmosphere. At this time, the entire amount of the inert gas flowing into the high-temperature reactor 310 may be supplied with high purity nitrogen gas through a separate supply device, or the inert gas from which contaminants are removed in the purification unit 600 described later may be circulated and supplied. According to demand, high-purity nitrogen gas can be additionally supplied. This is advantageous in reducing overall production costs as it can reduce the supply of high-purity nitrogen gas and thus reduce operating costs.

The inert gas may also be supplied to the stabilization tank 320 described later or the extruder 410 described later, and may be applied in various ways during the operation of the manufacturing system.

In the present invention, gaseous substances generated in the reaction unit 300 and the molding unit 400 may be discharged to the rear through a gas transfer facility having a closed structure. Such a closed structure is advantageous in preventing secondary environmental pollution by preventing pollutants generated in the manufacturing system from being discharged to the outside.

The capacity of the high-temperature reactor 310 may be 1/2 or less of the capacity of the preheating tank of the preheating unit 200, and may be specifically 1/3 to 1/2. In this case, the high-temperature reactor 310 may include a first reactor 311 and a second reactor 312 connected in parallel. Here, the first reactor 311 and the second reactor 312 may alternately receive the molten raw material discharged from the preheating tank. That is, the high-temperature molten raw material discharged from the preheating tank is first supplied to the first reaction tank 311, and during the polycondensation reaction in the first reactor 311, the molten raw material in the preheating tank is supplied to the second reactor ( 312) can be supplied. Here, the first reactor 311 and the second reactor 312 are separated for convenience of explanation, and the first reactor 311 and the second reactor 312 may be the same, and two or more may be disposed. . Meanwhile, a receiver may be provided under the high-temperature reactor 310 . This is advantageous for stable operation of the entire system.

Here, the residence time of the molten raw material in the high-temperature reactor 310 may be adjusted to about twice the residence time of the raw material in the preheating tank. Therefore, by correspondingly arranging two high-temperature reactors 310 located in parallel in one preheating tank, the molten raw material generated in the preheating tank 210 is continuously fed to the first reactor 311 or the second reactor 312. can supply This is advantageous for continuous production of the entire system. 1 shows one preheating tank and two high-temperature reactors 310, it is obvious that the number and arrangement of the preheating tank 210 and the high-temperature reactors 310 can be changed depending on the production scale and production operating conditions. .

Also, although not shown in FIG. 1 , a level sensor may be provided inside the high-temperature reactor 310 , and the level sensor may be electrically connected to the control unit. When the molten raw material accommodated in the high-temperature reactor 310 reaches a predetermined height and contacts the level sensor, the level sensor sends an electrical signal to the controller. The control unit may control the high-temperature liquid pump to be described later by the received electrical signal to stop supplying the material.

In the present invention, a stabilization tank 320 may be disposed at a rear end of the high-temperature reactor 310 .

The stabilization tank 320 may stabilize the product generated in the high-temperature reactor 310 under a predetermined temperature condition for a predetermined time. The stabilization tank 320 can control the continuous reaction of the high-temperature product generated in the high-temperature reactor 310 by residual heat. The stabilization bath 320 may include a stabilization bath heater and a stabilization bath temperature controller for maintaining a constant internal temperature. The internal temperature of the stabilization bath 320 may be stably maintained by the operation of the stabilization bath heater and the stabilization bath temperature controller. Here, the internal temperature of the stabilization bath 320 may be in the range of 300 °C to 400 °C. When the internal temperature of the stabilization tank 320 is lower than 300 ° C, there is a problem that solidification of the internal material occurs, and when the internal temperature is higher than 400 ° C, an additional reaction proceeds, resulting in a decrease in product quality and production volume. there is

The liquid material stabilized in the stabilization tank 320, that is, the liquid coating material produced is supplied to the molding unit 400 described later, and the generated gas and tar are supplied to the tar bath 500 described later through an outlet provided at the top of the stabilization tank 320. ) is supplied.

Next, the molding part 400 will be described.

In the present invention, the molding unit 400 may include an extruder 410 and a grinder 420.

The extruder 410 may be located at the rear end of the stabilization tank 320. Here, the extruder 410 may include an extruder temperature controller and a speed controller.

A liquid coating material transfer unit is connected to the liquid coating material discharge port of the stabilization tank 320 to supply the liquid coating material produced in the stabilization tank 320 to the rear extruder. In addition, the temperature controller may be located in the transfer part of the liquid coating material to cool the liquid coating material discharged from the stabilization tank 320 into a semi-solid coating material and supply it to the extruder 410 . Here, the temperature controller may be configured in the form of a water cooling jacket. The water cooling jacket may be located outside the extrusion part of the extruder 410 .

The semi-solid coating material is molded into a pellet coating material in an extruder 410. The diameter of the pellet coating material may be 2mm to 4mm, may be specifically 2.5mm to 3.5mm, and more specifically may be 3mm. In addition, the length of the pellet coating material may be 4mm to 6mm, may be specifically 4.5mm to 5.5mm, more specifically may be 5mm. On the other hand, the speed controller provided in the extruder 410 can control the production speed of the pellet coating material.

The crusher 420 may be located at the rear end of the extruder 410. The pulverizer 420 may produce a powder coating material by pulverizing the pallet coating material produced in the extruder 410 . The powder coating material may have an average particle diameter D (50) of 0.5 μm to 6 μm, specifically, 1 μm to 5 μm. Here, the mill 420 is not particularly limited as long as it can be used in combination with the pin mill mill 421 and the jet mill mill 422, and can stably produce the powder coating material using the pellet coating material.

Next, the tarzo 500 will be described.

The tar bath 500 may collect tar while passing exhaust gas and tar discharged from the heating bath, the high-temperature reactor 310 and the stabilization bath 320 . In the present invention, the tar tank 500 may be configured in a cylindrical shape, and the capacity may be 1000L to 5000L, specifically 3000L, but depending on the scale of the manufacturing system according to the present invention and the arrangement of the configuration equipment, the tar It is apparent that the capacity size of the bath 500 can be varied.

Next, the purification unit 600 will be described.

In the present invention, the purification unit 600 may include a dust collector 610 and an adsorption tower 620. The purification unit 600 may purify and deodorize the exhaust gas discharged from the tar bath 500 while passing it therethrough. Here, the dust collector 610 may be a dry type electrostatic precipitator, and may have a gas treatment capacity of 10 m ³ or more. While the exhaust gas discharged from the grinder 420 passes through the dust collector 610, particulate matter and/or contaminants in the exhaust gas may be removed. An adsorption tower 620 is positioned at the rear end of the dust collector 610 to remove odors in the gas discharged from the dust collector 610 . Here, the adsorption tower 620 may be filled with an adsorbent such as activated carbon, and the capacity of the adsorption tower 620 may be 3 m ³ or more.

The purified gas discharged from the adsorption tower 520 is supplied to the high-temperature reactor 310, the stabilization tank 320 or the extruder 410, and may be used to maintain an inert atmosphere.

2 is a schematic diagram of a method for manufacturing an electrode dry coating material for a lithium secondary battery according to the present invention.

Referring to Figure 2, the manufacturing method of the electrode dry coating material for a lithium secondary battery according to an embodiment of the present invention is a raw material pitch supply step (S100); melting step (S200); Reaction step (S300); stabilization step (S400); molding step (S500); And crushing step (S600); may include.

In the present invention, the raw pitch may include any one of petroleum pitch, coal tar pitch, and coke oil, and may be petroleum pitch or coal pitch. At this time, the raw material pitch may have a softening point of 100 ° C to 150 ° C, specifically 105 ° C to 125 ° C; the toluene insoluble content is 2% or less, specifically 1% or less; The carbonization yield is 45 to 55%; H/C atomic ratio is 0.6 to 1.0, specifically 0.7 to 1.0; Total aromatic proportion is 45% to 60%, specifically 50% to 55%; The sulfur component content may be 0.5% or less, and specifically 0.3% or less. By using the pitch having the above characteristics as a raw material of the present invention, it is easy to control operating conditions in the subsequent process, which is advantageous in improving overall productivity.

In the pitch melting step (S200), the pitch raw material is melted in a preheating tank under a predetermined temperature condition to prepare a molten pitch. Here, the temperature may be 300°C or less, and may be 250°C or less. At this time, if it is higher than 300 ℃, there is a problem that it is difficult to maintain the same viscosity for a long time in a stable molten state. Here, the heating rate for heating to the above temperature may be 1 °C/min to 20 °C/min, and in detail, 5 °C/min to 15 °C/min. When the temperature increase rate is greater than 20 °C/min, temperature control is difficult and additional side reactions may occur. If the temperature increase rate is less than 1 ° C./min, the temperature increase time becomes long, and there is a problem in that the production efficiency of the entire product is lowered.

In addition, while stirring the molten pitch with a stirrer in the above temperature range, it can be maintained within 2 hours. This is advantageous not only for sufficiently melting the raw material, but also for stably and continuously supplying the molten material to the reaction step (S300) described later.

At this time, the stirring speed of the stirrer may be 50 rpm to 300 rpm, specifically 100 rpm to 200 rpm. On the other hand, the viscosity of the produced molten pitch is maintained at 1,000 cp or less. This is advantageous in improving the overall production efficiency by smoothly transferring the molten pitch to the subsequent process using the liquid pump. In addition, the change in weight of the molten pitch produced compared to the pitch of the raw material introduced into the preheating tank may be maintained within 5%. When the weight change is greater than 5%, there is a problem that affects the quality and yield of products produced in the subsequent process.

In the molten pitch reaction step (S300), a liquid coating material may be produced by reacting the molten pitch at a temperature of 500 ° C or less. Here, the heating rate may be 0.5 °C/min to 5 °C/min or less, specifically 0.5 °C/min to 2 °C/min, and more specifically 1 °C/min. A stable polycondensation reaction proceeds when the temperature is raised within the above range, so that high-quality products can be efficiently produced. If the heating rate is less than 1 ℃ / min, there is a problem that the temperature raising time is long and the overall productivity is lowered, and if the heating rate is higher than 5 ℃ / min, there is a problem that the quality of the product is reduced or the production volume is reduced due to overheating. there is.

In the molten pitch reaction step (S300), it may be maintained for 2 hours to 4 hours at the temperature condition of 500 ° C. or less, and specifically, it may be maintained for 2.5 hours to 3.5 hours. At this time, the molten pitch can be reacted within 6 hours, including the temperature increase time until the temperature is raised to 500 ° C. or less by the temperature increase rate. When the reaction time is longer than 6 hours, the softening point and toluene insoluble content of the dry coating agent for electrodes may be out of the quality standard range.

In the melt pitch reaction step (S300), the reaction pressure of the melt pitch may be in the range of 0.090 MPa to 0.110 MPa, and more specifically may be in the range of 0.098 MPa to 0.107 MPa. At this time, the reaction stirring speed may be 50 rpm to 300 rpm, and in detail, may be 100 rpm to 200 rpm. In addition, the linear speed of the agitator may be 250 m/s to 1500 m/s, specifically 500 m/s to 1000 m/s. Meanwhile, the inside of the reactor may be made into an inert atmosphere by injecting an inert gas.

In the product stabilization step (S400), the liquid coating material prepared in the reaction step (S300) may be stabilized at a predetermined temperature. Here, the temperature of the stabilization bath may be in the range of 250° C. to 350° C. In addition, the stabilization temperature may be maintained for 1 hour to 3 hours, and specifically, may be maintained for about 2 hours.

In the product molding step (S500), a pellet coating material may be produced by extruding the liquid coating material supplied in the stabilization step (S400). In addition, a temperature controller is provided so that the liquid coating material is transferred from the product stabilization step (S400) to the product molding step (S500) and then cooled in the extruder of the molding machine. On the other hand, it is possible to adjust the cooling rate and transfer rate of the liquid coating material by providing a speed controller. Here, the diameter of the pellet coating material may be 2mm to 4mm, may be specifically 2.5mm to 3.5mm, may be more specifically 3mm. In addition, the length of the pellet coating material may be 4mm to 6mm, may be specifically 4.5mm to 5.5mm, more specifically may be 5mm.

In the pulverization step (S600), the pellet coating material is pulverized. A combination of a pin mill mill and a jet mill mill may be used, and a powder coating material may be produced by pulverizing the pellet coating agent. The powder coating material may have an average particle diameter D (50) of 0.5 μm to 5 μm, specifically 1 μm to 4 μm, and more specifically 1 μm to 3 μm. Here, if the average particle diameter D (50) of the powder coating material is larger than 6 μm, there is a problem of non-uniform coating when forming a coating layer on the electrode for a lithium secondary battery, and if it is smaller than 0.5 μm, it takes a long time to pulverize and increases production cost. There are increasing problems. Here, the configuration of the crushing device is not limited to a pin mill and a jet mill, and is not particularly limited as long as it can satisfy the particle diameter of the powder.

The softening point of the electrode dry coating material for a lithium secondary battery, which is the final product manufactured in the present invention, may range from 230 °C to 280 °C, specifically from 240 °C to 260 °C. In addition, the toluene insoluble content may be in the range of 45% to 55%, specifically 40% to 50%. Here, the toluene insoluble content refers to a specific range of components that are not soluble in toluene among the solvent insoluble content. The toluene insoluble content is a factor determining the presence or absence of the characteristics of the dry coating material. The toluene insoluble component has adhesive strength and is a highly efficient component that is converted into solid carbon by reacting during the heat treatment process. Therefore, in order to use it as a dry coating material, an appropriate amount of toluene insoluble content is required. If the content is too small, the coating layer has a low residual carbon ratio during the carbonization process, making it impossible to obtain an effective surface coating layer. Since melting is not possible, many defects are generated in the coating layer.

Hereinafter, preferred embodiments of the present invention and experimental examples according thereto will be described. However, the following example is only a preferred embodiment of the present invention, but the present invention is not limited to the following example.

Example 1

In the present invention, the electrode dry coating material is prepared from petroleum-based pitch or/and coal-based pitch.

In the present invention, pitch having a softening point of 118 ° C and an H / C ratio of 0.98 was introduced into a continuous first-stage reactor made of SUS as a raw material, and then the temperature of the first-stage reactor was raised to 250 ° C and maintained for 5 hours. In the heat treatment process, stirring was performed at a speed of 50 rpm so that the inside of the reactor could be uniformly heated, and nitrogen gas was supplied to maintain an inert atmosphere. The internal pressure was maintained at 0.098 MPa in order to prevent the residual of gas components generated in the reaction process. The preheated and molten pitch in the first-stage reactor is transferred to the second-stage high-temperature reactor, and the temperature of the second-stage reactor is raised to 350° C. and reacted for 4 hours. The product is transferred to a post stabilization tank and subjected to a stabilization step at 350° C. for 2 hours to prepare a dry coating material for an electrode for a lithium secondary battery. Here, the dry coating material for the electrode may be preferably a dry coating material for the negative electrode.

At this time, the manufacturing yield is 75%. The production yield is a value converted by the weight ratio of the reactants obtained with respect to the weight of the input molten raw material, and as the reaction conditions change, the production yield and product characteristics may vary. The input molten raw material means liquid molten pitch produced by preheating solid raw material pitch, and the production yield is the input amount of the liquid molten pitch (A) and the weight of the liquid coating material discharged from the stabilization step after the high temperature reaction (B ), that is, (B/A)*100.

Examples 2 to 4

An electrode coating material for a lithium secondary battery was prepared in the same manner as in Example 1 according to the operating conditions shown in Table 1 below.

Comparative Examples 1 to 3

It is the same as in Example 1 except that pitch having a softening point of 115° C. and an H/C ratio of 0.57 was used as a raw material.

Examples 1 to 4, the pitch raw material properties used in Comparative Example 3 in Example 1 and the operating conditions in each reaction step are shown in [Table 1] below.

division Raw material melting reaction stabilization softening point
(℃) H/C Preheating temperature (℃) Preheat
hour
(h) stirring
speed
(rpm) reaction
temperature
(℃) reaction
time (h) stirring
speed
(rpm) stabilization
temperature
(℃) stabilization
hour
(h) Example 1 118 0.98 250 5 50 350 4 150 350 2 Example 2 118 0.98 250 One 50 350 4 150 350 2 Example 3 118 0.98 250 2 50 350 4 150 350 2 Example 4 118 0.98 200 2 50 300 4 150 350 2 Comparative Example 1 115 0.57 300 2 50 300 3 150 350 2 Comparative Example 2 115 0.57 300 2 50 450 2 150 350 2 Comparative Example 3 115 0.57 300 2 50 600 One 150 350 2

Experimental example 1 - Viscosity analysis of molten pitch

The viscosity of the molten pitch produced after completion of the preheating step in Examples 1 to 4 was analyzed using a viscometer.

The viscosity analysis results are shown in [Table 2] below.

Preheating temperature (℃) Preheating time (h) Stirring speed (rpm) Viscosity (cP) Example 1 150 5 50 2500cp Example 2 200 One 50 2000cp Example 3 250 2 50 1000cp Example 4 300 2 50 950cp

As shown in [Table 2], it can be seen that the viscosity of the molten pitch decreases as the preheating temperature increases. It was confirmed that when the preheating temperature is 250 ° C. or more and the preheating time is 2 hours, a melted pitch having a viscosity of 1000 cP or less that meets the requirements of the present invention can be produced.

Experimental Example 2 - Analysis of toluene insoluble content of coating material

The toluene insoluble content (TI%) of the coating materials prepared in Examples 1 to 12 and Comparative Example 1 was analyzed. TI% was analyzed using the Soxhlet measurement method.

TI% analysis results are shown in [Table 3] below.

Experimental Example 3 - Analysis of softening point of coating material

The softening points of the coating materials prepared in Examples 1 to 12 and Comparative Example 1 were analyzed.

Softening point analysis was measured using a melting point system MP-70 (Mettler Co.).

The softening point analysis results are shown in [Table 3] below.

Preheating temperature (℃) Reaction temperature (℃) TI (%) Softening point (℃) Example 1 250 350 43.5 250 Comparative Example 1 300 300 32 213 Comparative Example 2 300 450 72 289 Comparative Example 3 300 600 92 insoluble

As shown in [Table 3], it can be seen that the higher the reaction temperature, the higher the TI% and softening point of the prepared coating material.

Experimental Example 4 - Analysis of Surface Characteristics

(cathode material)

Surface analysis of uncoated anode materials

A scanning electron microscope (SEM) analysis result of the negative electrode material without a coating material on the surface is shown in FIG. 3 .

(Cathode material coated with dry coating material)

The scanning electron microscope (SEM) analysis results of the negative electrode material coated with the dry coating material having an average particle diameter D (50) of 6 μm and the negative electrode material coated with a dry coating material having an average particle diameter D (50) of 3 μm according to the present invention are shown in FIG. 4A and 4b.

Referring to FIGS. 3 , 4A and 4B , it can be seen that the surface of the non-coated negative electrode material, which is not coated with the coating material, has an irregularly rough surface. It can be seen that the negative electrode material coated with the dry coating material having an average particle diameter D (50) of 6 μm has a mixture of particles with a relatively smooth surface and plate-shaped particles compared to the non-coated negative electrode material. In addition, it can be seen that most of the negative electrode material coated with the dry coating material having an average particle diameter D (50) of 3 μm is a mixture of particles having a smooth surface.

Experimental Example 5 - Secondary Battery Charge/Discharge Characteristics Test

After manufacturing a secondary battery using the negative electrode material coated with the dry coating material according to the present invention, the charge and discharge characteristics were evaluated.

The charge/discharge characteristic test results are shown in [Table 4], and the reference example in [Table 4] is the case of a secondary battery to which an uncoated negative electrode material is applied.

division ^1st cycle
(mAh/g) Initial efficiency (%) Example 2 366 95 Comparative Example 2 350 92 reference example 345 90

As shown in [Table 4], in the case of the secondary battery to which the dry coating material manufactured according to Example 2 of the present invention was applied, the discharge capacity increased by about 6% compared to the secondary battery to which the non-coated negative electrode material was applied, and in Comparative Example 2 It can be confirmed that the secondary battery with the coating material according to the application increased by about 3%. In addition, the initial efficiency of the secondary battery to which the dry coating material manufactured according to Example 2 was applied was 95%, and it could be confirmed that the initial efficiency of the secondary battery to which the non-coated negative electrode material was applied and the secondary battery to which a different coating material was applied to Comparative Example 2 increased compared to the initial efficiency. there is.

The present invention is not limited to the above embodiments, but can be implemented in a variety of different forms, and those skilled in the art to which the present invention pertains may take other specific forms without changing the technical spirit or essential features of the present invention. It will be understood that it can be implemented as. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting.

Claims (15)

The softening point is in the range of 230 ~ 280 ℃, toluene insoluble content is in the range of 45 ~ 55%, electrode dry coating material for a lithium secondary battery.
According to claim 1,
The average particle diameter D (50) of the electrode dry coating material for a lithium secondary battery is in the range of 0.5 μm to 3 μm, the electrode dry coating material for a lithium secondary battery.
According to claim 1,
The carbonization yield of the electrode dry coating material for a lithium secondary battery is in the range of 65 to 75%, the electrode dry coating material for a lithium secondary battery.
A raw material supply unit for continuously supplying raw material pitch;
A pre-heating unit for converting the raw material pitch into a molten pitch having a viscosity of 1000 cp or less;
a reaction unit for converting the molten pitch into a liquid coating material;
a molding unit to convert the liquid coating material into a powder coating material;
Tar Joe for separating the tar generated in the reaction unit; and
A purification unit for removing contaminants from the gas generated in the reaction unit and/or the molding unit;
The reaction unit includes a high-temperature reactor for polycondensation of the molten pitch and a stabilization tank for stabilizing the product produced in the high-temperature reactor.
According to claim 4,
The reaction unit includes two or more high-temperature reactors arranged in parallel,
The high-temperature reactors are alternately supplied with the molten pitch generated in the preheating tank and continuously operate the electrode dry coating material manufacturing system for a lithium secondary battery.
According to claim 5,
A high-temperature liquid pump is located between the preheating unit and the two or more high-temperature reactors disposed in parallel,
The high-temperature liquid pump is equipped with a heating device to maintain the temperature of the molten pitch supplied,
The high-temperature liquid pump alternately supplies the molten pitch generated in the preheating unit to the two or more high-temperature reactors for continuous operation.
According to claim 4,
The purification unit,
Including a dust collector and an adsorption tower through which the gas sequentially passes,
An electrode dry coating material manufacturing system for a lithium secondary battery that supplies purified gas purified through the adsorption tower to the high-temperature reactor to maintain the inside of the high-temperature reactor and the stabilization tank in an inert atmosphere.
According to claim 4,
The pre-heating unit includes a pre-heating tank for receiving and melting the raw material pitch therein; and
Including; a heater and a temperature controller for heating the inside of the preheating tank,
An electrode dry coating material manufacturing system for a lithium secondary battery comprising a high voltage transformer that shields the high voltage applied to the preheating tank from being transmitted to the heater and the temperature controller.
According to claim 4,
The raw material supply unit,
A raw material storage tank for accommodating pitch raw materials; and
Including; raw material transfer device connected to the lower part of the raw material storage tank,
The raw material conveying device is a vacuum conveying device,
The vacuum transfer device is a lithium secondary battery electrode dry coating material manufacturing system for adjusting the supply amount of the raw material pitch by the control unit.
According to claim 4,
The molding unit includes an extruder and a grinder sequentially disposed,
Between the extruder and the stabilization tank, a liquid coating material conveying unit is located,
The electrode dry coating material manufacturing system for a lithium secondary battery is provided with a temperature controller in the liquid coating material transfer unit to cool the liquid coating material.
Continuously supplying raw material pitch;
Melting the raw material pitch into molten pitch;
Polycondensation reaction of the molten pitch;
obtaining a liquid coating material by stabilizing a product produced in the polycondensation reaction;
extruding the liquid coating material into a pellet coating material; and
Grinding the pellet coating material into a powder coating material; Including,
The powder coating material has a softening point in the range of 220 ~ 280 ℃, toluene insoluble content is in the range of 35 ~ 55%, a method for producing a dry coating material for a lithium secondary battery electrode.
According to claim 11,
The step of melting the raw material pitch into molten pitch,
Melting the raw material pitch at a melting temperature of 300 ° C. or less,
Method for producing an electrode dry coating material for a lithium secondary battery, which is heated at the temperature increase rate of 20 ° C / min.
According to claim 11,
The step of polycondensation reaction of the molten pitch,
Polycondensation reaction of molten pitch at a polycondensation reaction temperature of 500 ° C. or less,
Heating at a heating rate of 5 ° C./min or less to the polycondensation reaction temperature,
The polycondensation half pressure is a method for producing an electrode dry coating material for a lithium secondary battery that is in the range of 0.098 to 0.107 MPa.
According to claim 11,
The step of melting the raw material pitch into molten pitch,
Method for producing an electrode dry coating material for a lithium secondary battery that controls the weight change of the raw material pitch to within 5%.
According to claim 11,
The raw material pitch,
a softening point of 100 to 150°C; Toluene insoluble content is 2% or less; carbonization yield of 45 to 55%;
H/C atomic ratio of 0.6 to 1.0; The total aromatics ratio is 45 to 60%; Method for producing an electrode dry coating material for a lithium secondary battery having a sulfur component content of 0.5% or less.

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