TW200915638A - Composite graphite for lithium secondary cell and manufacturing method thereof - Google Patents

Abstract

The present invention provides a composite graphite for lithium (Li) secondary cell and manufacturing method thereof. The method includes steps: using spherical graphite as the matrix, preheat it to the powder temperature of 55-85 DEG C by a heating-type muller, and dropping the coating material (a mixed solution composed of coal tar, mineral tar (maltha), and liquid-state resin group) for mixing, then mixing them sufficiently, fill the mixture into the graphite container for polymer processing, and then sending it into the straight-firing sintering retorts for carbonization processing and performing screening or air-stream classification to obtain the composite graphite powder. This invention therefore is able to reduce manufacturing cost by simplifying the manufacturing process, in addition, the derived product is used as the negative electrode material of the lithium (Li) secondary cell, so that the lithium (Li) secondary cell has the high initial- charging/discharging efficiency and large discharging volume.

Description

200915638 IX. Description of the Invention: [Technical Field] The present invention relates to a composite graphite for a lithium secondary battery and a method for producing the same, and more particularly to a simplified manufacturing process, which saves manufacturing costs and obtains a negative electrode of a lithium secondary battery The material, which is made of a battery, has a higher discharge capacity' and has a south discharge efficiency. [Prior Art] With the rapid development and maturity of electronic technology, people have put forward new requirements for power supplies with light weight, high energy and strong adaptability. The well-known lithium-ion battery has large potential difference between positive and negative materials. It can increase its energy density and achieve the characteristics of small size and high electric quantity, and can meet the needs of electronic products. According to the lithium-ion battery, the anode material is generally made of graphite. In the case of graphite, most of the graphite is made of natural graphite, coke-based high-temperature treated artificial graphite and dipco-type carbon fiber. Among them, 5 is most convenient to obtain natural graphite. However, due to the removal of impurities and the limitation of purification method, natural graphite is generally considered to be flake graphite, but flake graphite is used as a negative electrode material for lithium batteries, although high discharge capacity can be achieved. However, due to its specific shape, contact with the electrolyte in the battery is not as safe as a ball, and the high-speed charge and discharge characteristics are low. At the same time, when natural flake graphite is used as the negative electrode material of the lithium battery, the lithium-discriminated compound generated by the reaction between the lithium ion and the electrolyte is easily attached to the surface due to its crystallinity during the initial charge and discharge process, and a solid electrolyte SEI film is formed. , resulting in a low efficiency of initial charge and discharge. 5 200915638 In view of this, the relevant industry and researchers at home and abroad have invested in the research of the topic, such as the special issue of China Patent Publication No. 58735, which has a manufacturing method for three-layer composite graphite, but Manufacturing: c·French two is cumbersome, requires a variety of equipment to carry out each step, resulting in manufacturing costs s ang 0. In addition, as disclosed in China Patent Publication No. 262617, the liquid resin is mainly coated on spherical graphite by liquid-gas mixing method. And heat treatment to 80 (M200 °c, the resin is cracked into amorphous carbon, to inhibit the peeling of graphite in the battery charging process, in order to improve the initial charge and discharge efficiency. It is simpler than the above patents, but it is still complicated. Firstly, it is required to uniformly open y graphite, liquid resin and organic solvent, and then remove the organic solvent by vacuum drying. After heat treatment, the mixture is 800~120 (TC is re-crushed. It is worthwhile to think about the necessity of adding and removing organic solvents, the cost of minus 1 and the environmental load caused by removing organic solvents. At the same time, it is made of a single liquid resin. When the material is coated, after the heat treatment, because the carbon mesh layer has too many holes, and the heat treatment is performed at 8 〇〇 to 12 〇 (rc, the table 'non-曰曰=3⁄4 is melted and agglomerated, and is chopped. In the process, the carbon material is prone to fall and the V-induced specific surface area is too large to affect the characteristics of the battery. However, if the temperature and time are insufficient, the material may be deformed during charging and discharging. In addition, the peeling phenomenon between the substrate and the covering material is caused, and the discharge capacity and the charging and discharging efficiency of the battery are also lowered. [Invention] The main purpose of the present invention is to provide a lithium secondary battery. The composite graphite and the manufacturing method thereof can effectively simplify the flow and reduce the production cost. The second object of the present invention is to provide a composite graphite for a lithium secondary battery and a manufacturing method thereof. Further, the reduction of the agglomeration rate is achieved, and the material peeling caused by the deformation of the material during the charging and discharging process is avoided. To achieve the above purpose, the present invention is a lithium secondary battery. Composite graphite and a manufacturing method thereof, comprising the following steps: 1. selecting spherical graphite as a substrate, preheating the substrate by a heating and kneading machine for a set time to a preset temperature, inputting the material and thoroughly mixing it, The above mixture is filled into the graphite container; 2. The graphite container is sent to a hot air constant temperature circulating furnace at a preset temperature for macromolecular treatment; 3. After being transferred into a direct fire sintering carbonization furnace, after high temperature carbonization treatment, the temperature is raised. To a preset temperature and maintained for a preset time and cooled to room temperature; 4. Finally, the composite graphite is obtained by sieving or gas flow classification. Among them, the graphite system selects 299.9% of fixed carbon and the interval of crystal layer is d. 〇2 S 0 33 7nm high-purity spherical graphite as a substrate. In a feasible embodiment, the substrate preheating set time is 2 30 minutes, the preset preheating temperature is 55~85 ° C, and the covering material is put into heating and kneading. The inside of the machine is stirred and mixed with the substrate for 10 to 40 minutes, and the above-mentioned coating material is coal tar or soft asphalt having a softening point of 65 ° C or lower, or a mixture of the above two materials and the liquid resin, and the mixing ratio (coal tar or soft asphalt) / liquid resin = 100/0~50/50, the ratio of the material used is about 10~40% (the ratio of adding to the substrate). Further, the filling rate of the mixture filled in the graphite container was 70 to 90%; the upper 200915638 min, the material density g, the porosity of the graphite container material - 3 cc / cm 2 1.65 g / cc 'thermal conductivity ^ ^ (10) / pool. In the case where it is feasible to carry out the injection, the above-mentioned substrate is subjected to a macromolecular treatment process. The calcination condition in the furnace is set to be 15% oxygen content in the furnace, and the furnace pressure is -1 〇 1 to 1 〇 coffee water column pressure, in the furnace. The temperature is maintained at 210. (: When the above-mentioned stone container passes through the polymer furnace, the graphite container is heated at 1 〇 to 3 per hour (rc is heated to S210 ° C, and the total processing time is $15 hours. #者'Carbonization process towel, direct fire sintering carbonization furnace Roasting conditions, the furnace pressure is set to 〇. Bu 1 〇 surface water column pressure, air-fuel ratio 〇 8 〇 99, oxygen content 〇 _, to 2 per hour (M2 (rc heating to Celsius surface ~ turn. c, holding temperature time) After 22 hours, it was cooled to room temperature. The negative electrode material produced by the above production method had the following physical properties, and obtained a particle size distribution of 5 % by volume of '25/zm [d (0.5) < 25 " mi

, 2/ & + — # m], specific surface area S vibration density grog/cc, graphitization 〇%; (〇-344000-d〇〇2)/(〇.344〇〇^〇_33538)x= 〇〇t length 514.4nm 4 laser light Raman spectrum ^ exists in the range 1 3 5 0 ~ 1 3 70cnrl in the range of 1 5 70~163 〇 c ^ guide strength 1 ϊ / τ < η ςΑΑ + 耵绎The surface of the ratio of the intensity IG is coated with a composite graphite powder of carbon material. [Embodiment] In order to further understand the bridge depth-layer of the present invention, a clear and detailed understanding and understanding 1 and its features are more closely illustrated as follows: Example of the cattle car father, 200915638 1 shows that the present invention is a composite graphite for a lithium secondary battery and a method for producing the same, which comprises the following steps: firstly, a fixed carbon fixing carbon g 99.9%, a crystal layer spacing dmS 0. 337 nm High-purity spherical graphite is used as a substrate, preheated to a preset temperature by a heating kneader, and the coated material is placed in a substrate and stirred and mixed. Then the mixture is loaded into a graphite container and sent to a hot air temperature cycle. The furnace polymerizes the mixture, and the internal calcination setting condition of the hot air constant temperature circulating furnace is that the oxygen content in the furnace is 丨5%, the furnace pressure is -10~ΙΟ·water column pressure, and the furnace constant temperature is maintained at 21〇^2 When the graphite container passes through the polymer furnace, the graphite container is heated to 10 丨〇t Celsius at 10 to 30 ° C per hour. Then, it is transferred into a direct-fire sintering carbonization furnace for carbonization treatment, and the calcination conditions of the carbonization furnace are set in the above carbonization process, and the furnace pressure is 0. Bu 10·water column pressure, air-fuel ratio 〇8 to 〇99, oxygen content S 3 0 0 ppm, 2 〇 to 12 每小时 per hour: warm up to Celsius ^ 1 000 to 1 600 ° C, keep the temperature for $ 2 hours and then cool to room temperature. Finally, it is classified by airflow or sieve to obtain a particle size distribution of 50% by volume, s25"m[d(〇.5)g25//m], specific surface area g 5m2/g, tap density, 丨.〇g /cc, degree of graphitization 2 go % [( 0. 344000-d0 02 ) / ( 0. 3440 0-0^ 33538 ) xl 〇〇 200915638 % ], and in the argon laser Raman spectroscopy at a wavelength of 511.4 nm , there is a peak intensity Id in the range of 1350 to 1370 cm_1, and a composite graphite powder of a surface-coated carbonaceous material having a ratio of the peak intensity U in the range of 1 5 70 to 1 63 0 cm-1, Id/IgS0.5 The anode material of the lithium secondary battery. In a feasible embodiment, the substrate is preheated for 260 minutes, the preset preheating temperature is 5 5~8 5 ° C, and the coated material is put into the heating and kneading machine and the substrate. The internal mixing and mixing time is 10 to 40 minutes, and the above-mentioned other covering material is coal tar or soft asphalt having a softening point of 65 ° C or less, or a mixture of the above two materials and a liquid resin, and the mixing ratio is (coal tar) Or soft asphalt) / liquid resin = 1 0 0 / 0~5 0 / 5 0, the ratio of the coating material is about 10 to 40% (the ratio of adding to the substrate). In the example, the mixture filled in the graphite container has a filling rate of 70 to 90%; the graphite container has a porosity of 2 3 cc/cm 2 · min, a material density of 2 1.65 g/cc, and a thermal conductivity of 2 120 W/mk. Application Analysis Comparative Example-1 Example-1 Example-2 Comparative Example-2 Raw Material Graphite Material Spherical Graphite Spherical Graphite Spherical Graphite Spherical Graphite Covering Material Coal Tar / Resin Coal Tar / Resin Coal Tar / Resin Covered Material Mix Proportion 100/0 50/ 50 0/ 100 200915638 Experimental condition material hot ink pre-stone material after powder hot ink degree pre-stone temperature material ratio plus addition case mixing time carbonization sintering container container filling rate polymerization temperature treatment time oxygenation Volume carbonization Southernmost temperature 13⁄4 Temperature holding time Heating rate Filling gas Air-fuel ratio Oxygen content Carbonization After appearance Disintegration 4 5m 1 η 4 5m l η 4 5m l η

7 (TC

6 9〇C

7 0°C % ο % ο % ο 1 Om i η Graphite container 1 0 m i η Graphite container 1 0 m i η Graphite container 80% 80% 80%

25-210 °C

25-210 °C 7. 5Hr 7. 5Hr

25 °C —> 210 7. 5Hr 17.1% 16. 8% 15. 3%

1 4 5 0 °C

1 0 0 0 °C

1 0 0 0 °C 2hr 2hr 2hr

4 0 ～1 0 0 〇C

4 0 ～1 0 0 〇C

4 0 ～1 0 0 〇C 0.85-0 0.85-0. 9 0·85~0 1 5 0 ppm 19 5 ppm 1 9 0 ppm There are loose blocks with loose blocks and blocks 11 200915638 270# Screen yield 91. 3% 90. 8% 63. 3% Analytical content Average particle size 15. 0 9 /zm 17. 11// m 16. 92 um 16. 5 3 um Specific surface area 6. 63m2/g 1.48 M2/g 2.73m2/g 18.41m2/g True density 2. 24g/cc 2. 2 2g/cc 2.27g/cc 2. 32g/cc X-ray diffraction analysis (d002) 0.33558η m 0.335710 nm 0.33595η m 0.33657 η m 石化化97. 68% 96. 29% 93. 39% 86. 19% Raman R = ID/IG 0.1875 0.40 99 0.2732 0.250 0 Initial discharge capacity 3 6 0. 9mAh /g 3 6 5.2mAh /g 3 6 3. 8mAh /g ※ Because the specific surface area is too large, the solid content of the electrode is too low, and the analysis is stopped. Initial charge and discharge efficiency 86. 1% 92. 2% 91. 8% buckle battery cycle life (20 times) ---J 50.2% ----- 82. 8% BO. 4% The above chart is the invention Experimental data of composite graphite powder, in the example of the implementation and analysis of the chart _丨 data shows that the high-purity spherical graphite with fixed carbon 2 99.9% and crystal layer spacing 〇 · 3 3 7 nm is selected as the substrate. After preheating for 4 minutes, the powder temperature reaches 7 〇, and then the batch of cladding (coal tar) is added to 20%. After mixing and mixing for 丨〇 minutes, 12 200915638, the mixture is filled in a graphite container. The mixture filling rate is 80. %. During the process of the macromolecularization, the temperature was raised from room temperature to 21 0 C 'the treatment time of 7.5 hours, and the oxygen content was =1 7. 1%. During the carbonization process, the maximum temperature is set to 1 4 5 0 〇C, the heating rate is 40~l〇〇t:, the air-fuel ratio is set at ο.”~0.95, and the oxygen content is measured as 1 50ppm. It has a loose mass. Finally, it is sieved with a 270 mesh screen, and the sieve yield is 9丨.3 %. The obtained composite graphite powder has an average particle diameter of 1. 7.丨丨# m, and the specific surface area is 1. 48m2/g, true density value is 2·22g/cc ' X-ray diffraction analysis (d〇〇2) is 〇. 3 3 5 7〇nm, degree of graphitization 9 6. 2 9%, initial discharge capacity 3 6 5. 2 mAh / g, initial charge and discharge efficiency 92.2%. In a preferred embodiment, Example _2 is formed into composite graphite by the above-mentioned production steps, the following data is experimental data, selected The high-purity spherical graphite with a fixed carbon g of 99.9% and a crystal layer spacing d〇〇2 $0·337ηιη is used as a substrate. After preheating for 45 minutes, the powder temperature reaches (4), and then the batch coating material (coal tar and resin mixture) The ratio is 5〇/5〇) 2〇%, and the mixture is filled in a graphite container after mixing for 10 minutes, and the mixture filling rate is 80%. During the process, the temperature is raised from room temperature to 2 j 〇C, the treatment time is 7.5 hours, and the oxygen content is =1 6.8%. 13 200915638 During the carbonization process, the maximum temperature is set to 1 0 0 t: The rate is 40~100 °c 'the air-fuel ratio is set at 0.85~0.95, the oxygen content is measured to be 95 ppm, and the appearance after carbonization is powdery with loose mass. Finally, the sieve is sieved with 270 mesh, the sieve The yield is 9 〇. 8 % 'The obtained composite graphite powder has an average particle diameter of 6.9 2 2 m, a specific surface area of 2.73 m 2 /g, and a true density value of 2.27 g / cc ' X-ray diffraction Analysis ((1〇〇2) is 〇. 3 35 9 5nm, graphitization degree 93·39% 'initial discharge capacity 3 6 3. 8 mAh/g, initial charge and discharge efficiency 9 1. 8 %. Comparative Example-1 The cell was made directly from a spherical graphite material with an average particle size of 15.5 〇9 /zm, a specific surface area of 6.6 m / g, a true density of 2.24 g / cc, and a diffracting analysis (d0 0 2 3355 8nm, graphitization degree 97. 68° /, initial discharge capacity 360. 9mAh / g, initial charge and discharge efficiency 86. 1 % ° Comparative Example-2 is a composite made of resin as a batch material Graphite powder' The calcination conditions and the process steps were the same as those in Example-2, and the sieve was sieved through a 270 mesh screen, the sieve yield was 6 3.3%, and the average particle diameter of the composite graphite powder was 16.53 v ^. The specific surface area is 18·41m2/g, and the true density value is 2.32g/cc'. X-ray diffraction analysis (d〇〇2) is 〇.33657nm, the degree of graphitization is 8 6 · 19%, due to the excessive surface area of the electrode. When the solid content is too low 'battery production failure' can not be evaluated by the electrical evaluation 200915638, so the analysis is suspended. According to the comparison of the chart data, the specific surface area of the negative electrode material produced by the present invention is much smaller than that of Comparative Example-1 and Comparative-2, and the mesh yield is higher than that of Comparative Example-2, and the initial stage of the negative electrode material of the buckle type is made. The discharge capacity, the initial charge and discharge rate, and the cycle life were higher than those of Comparative Example-1, which was made of spherical graphite as a negative electrode material, and the graphite produced by Comparative Example-2 was caused by excessive surface area. The content is too low to complete the manufacture of the pole piece. Please refer to Figures 2 to 5 for the buckle type battery made of the above graphite powder as the negative electrode material. After cyclic charging and charging for 20 times, the discharge capacitance of Example-1 and Example-2 is still maintained at 80. % or higher is higher than other comparative examples, and after comparing -1 after cyclic charging and discharging for 20 times, the degree of battery decay can be shown in FIG. 5, and after the above-mentioned cyclic charge and discharge test, it is apparent that the composite generated by the steps of the present invention is obtained. The battery of graphite has high discharge capacity and excellent cycle discharge efficiency. By the steps of the invention, the manufacturing method of the material of the secondary battery is simplified, the production cost is reduced, the processing is not required, and the investment and manpower of the equipment for the mashing process are saved; and the charging and discharging efficiency of the battery is improved through the selection of the covering material. Improve the reduction of the agglomeration rate, avoid the battery in the charge and discharge process, the material pool is connected to the power supply, and the charge and discharge of the material stripping pool caused by the electric deformation is effectively improved. capacity. And p = upper: the description is only a preferred embodiment of the present invention, which is to limit the scope of implementation of the present invention, and the scope of the patent application and the content of the invention are as follows: Modifications are still included in the scope of the patent application of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 2 is a schematic flow chart showing a method for manufacturing a negative electrode material for a lithium ion secondary battery of the present invention; FIG. 2 is a comparison of test cycle life of a battery produced by the present invention and a comparative example. Figure 3; Figure 3 is a cycle charge and discharge curve of the embodiment of the present invention; Figure 4 is a cycle charge and discharge curve of Example 2 of the present invention; Figure 5 is a cycle of Comparative Example-1 Charge and discharge graph. Main component symbol description] None.

Claims (1)

200915638 X. Patent application scope: 1. A composite graphite for a lithium secondary battery and a manufacturing method thereof, the manufacturing method comprising the following steps: 1) selecting spherical graphite as a substrate, and using the substrate at a preset temperature Preheating for a set time, then adding the covering material and mixing it thoroughly, and filling the mixture into the graphite container; 2). Polymerizing the graphite container; 3) After the above has been treated by macromolecularization The graphite container is further subjected to high-temperature carbonization treatment, and is heated to a preset temperature for a predetermined time and cooled to room temperature; 4) Finally, the composite graphite is obtained by sieving or gas flow classification. 2. The composite graphite for a lithium secondary battery according to claim 1, wherein the substrate is preheated for a set time of 230 minutes, and the preset preheating temperature is 55 to 85. °C. 3. The composite graphite for a lithium secondary battery and the method for producing the same according to claim 1, wherein the batch material is (coal tar or soft pitch having a softening point of 65 ° C or less) / liquid resin Mixture = 1 0 0 / 0~5 0 / 5 0, the ratio of the covering material is about 10 to 40% [the ratio of the material used for the material = the weight of the cladding material / (weight of the substrate + weight of the batch of cladding material) ]. 4. The composite graphite for lithium secondary electricity 17 200915638 according to claim 1, wherein the graphite container has a porosity of 23 cc/cm 2 ·min, a material density of 2.65 g/cc, and heat conduction. The rate is 2120W/mk. 5. The composite graphite for a lithium secondary battery according to the first aspect of the invention, wherein the oxygen content is set to 21.5 % in the furnace during the above-mentioned high molecular weight treatment. 6. The composite graphite for a lithium secondary battery according to the first aspect of the invention, wherein the pressure in the furnace during the above-mentioned polymerization treatment is a water column pressure of -10 to 10 mm. 7. The composite graphite for a lithium secondary battery according to the first aspect of the invention, wherein the graphite container is passed through a polymer furnace, and the graphite container is at an hourly rate of 10 per hour. Heat up to 3 0 °C to Celsius S 2 1 0 X:. 8. The composite graphite for a lithium secondary battery according to claim 1, wherein the oxygen content S 3 0 0 ppm is set in the furnace during the carbonization treatment, and the air-fuel ratio is zero. 8~0. 9 9. The first embodiment of the present invention, wherein the pressure in the furnace is from 0. 1 to 1 0 mm. The composite graphite for a lithium secondary battery and the method for producing the same according to the first aspect of the invention, wherein the carbon 18 200915638 is heated at a temperature of 2 〇 丨 丨 2 每小时 per hour. The preset temperature is between 1 〇〇〇 and 1 6 〇〇 °c, and the preset time for maintaining the high temperature is g 2 hours. 11. A composite graphite produced by the method of the first method of the patent range has the following physical properties: a particle size distribution of 50% by volume of $25/zm [d(0.5)S25/zm], specific surface area S 5m2/ g, tap density: 1. 〇g/cc, degree of graphitization g 9 0% [(0.344000-d002)/(0.34400-0.33538)xl〇0 % ] 'and its argon laser Raman at a wavelength of 514.4 nm In the spectrum, there is a peak intensity Id in the range of 1350 to 1370 cm-1, and a composite graphite powder having a ratio Id / I g S 0 · 5 of peak intensity ic in the range of 1570 to 1630 (111-1).