Lithium battery negative electrode graphite and carbon fiber integrated graphitization device and method

Abstract

The invention discloses a lithium battery negative electrode graphite and carbon fiber integrated graphitization device and method.The device comprises a furnace body and an impurity blowing mechanism, the furnace body comprises a brick wall layer, a heat preservation layer, a heating layer and a blocking block, the heat preservation layer is embedded in the brick wall layer, the heating layer is embedded in the heat preservation layer, and the blocking block is arranged in the heating layer; a closed heating cavity is formed in the heating layer; and the impurity blowing mechanism is used for introducing inert gas into the air duct. The device has the beneficial effects that lithium battery negative electrode graphite and carbon fibers can be subjected to integrated graphitization, so that the equipment cost and energy consumption are reduced, meanwhile, inert gas is introduced into the air duct through the impurity blowing mechanism, is discharged from the air outlet holes and is blown to the surface of the carbon fiber felt, so that ash impurities generated in the heating process of the carbon fiber felt are removed, and the carbon fiber felt heating efficiency is improved. Ash impurities on the surface of the carbon fiber felt can be effectively discharged, and the influence of saturation of the ash impurities on the graphitization effect is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of graphitization, and in particular to a device and method for graphitizing integrated graphite and carbon fiber for negative electrodes of lithium batteries. Background Art

[0002] Graphitization of lithium battery negative electrode refers to the process of heating the negative electrode material of lithium battery to above 2000℃ in a graphitization furnace to transform it into a graphite structure. Graphitization of carbon fiber refers to the process of forming a layer of graphite film on the surface of carbon fiber material by reacting with inert gas at high temperature. This process is usually achieved by ultra-high temperature heating or high-energy material radiation, so that the internal structure of carbon fiber is transformed from the chaotic layer graphite sheet structure to a regular three-dimensional graphite crystal structure.

[0003] Usually, the graphitization of lithium battery negative electrode and carbon fiber is completed in different graphitization furnaces, which not only increases the equipment cost but also increases the energy consumption of the graphitization process. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned technical deficiencies and propose an integrated graphitization device and method for lithium battery negative electrode graphite and carbon fiber, so as to solve the technical problem that the graphitization of lithium battery negative electrode and carbon fiber are completed in different graphitization furnaces in the prior art, which not only increases the equipment cost but also increases the energy consumption of the graphitization process.

[0005] In order to achieve the above technical objectives, the present invention adopts the following technical solutions: The present invention provides a lithium battery negative electrode graphite and carbon fiber integrated graphitization device, comprising: A furnace body, the furnace body comprising a brick wall layer, a heat-insulating layer, a heating layer and a barrier block, the heat-insulating layer is embedded in the brick wall layer, the heating layer is embedded in the heat-insulating layer, the heating layer has a closed heating chamber, the barrier block is built in the heating chamber, and the heating chamber is divided into a first heating chamber and a second heating chamber, the first heating chamber is used for graphitizing the negative electrode graphite of the lithium battery, the second heating chamber is used for graphitizing the carbon fiber felt, an air duct is formed in the barrier block, and a side wall of the barrier block close to the second heating chamber is densely covered with air outlet holes connected to the air duct; and, A blowing mechanism is used to introduce inert gas into the air duct.

[0006] In some embodiments, the heating layer is a resistive material layer.

[0007] In some embodiments, the heating layer includes an upper heating layer and a lower heating layer, the upper heating layer is located above the heating chamber, the lower heating layer is located below the heating chamber, a first air inlet is opened on the upper heating layer, and the lower end of the first air inlet is connected to the air duct; The insulation layer includes an upper insulation layer, a lower insulation layer and a side insulation layer. The upper insulation layer is located above the upper heating layer. A second air inlet hole is opened on the upper insulation layer. The lower end of the second air inlet hole is connected to the upper end of the first air inlet hole, and the upper end of the second air inlet hole is connected to the air outlet end of the blowing mechanism.

[0008] In some embodiments, a material receiving trough located below the second heating cavity is provided on the upper end surface of the lower heating layer.

[0009] In some embodiments, the blowing mechanism includes a fixed seat, an air pump and an air inlet pipe, the fixed seat is fixed above the upper insulation layer, the air pump is fixed to the fixed seat, the inlet of the air pump is used to connect with an inert gas source, the outlet of the air pump is connected to one end of the air inlet pipe, the other end of the air inlet pipe is connected to the upper end of the second air inlet hole, and the air inlet pipe is provided with an air inlet valve.

[0010] In some embodiments, the blowing mechanism also includes a vacuum pump and an exhaust pipe. The vacuum pump is fixed to the fixed seat. The inlet of the vacuum pump is connected to one end of the exhaust pipe. The other end of the exhaust pipe is connected to the upper end of the second air inlet hole. An exhaust valve is provided on the exhaust pipe.

[0011] In some embodiments, a first vent hole communicating with the second heating chamber is formed in the side insulation layer, a second vent hole communicating with the first vent hole is formed in the brick wall layer, and a vent valve is provided at the outlet end of the second vent hole.

[0012] In some embodiments, the upper heating layer is provided with a first through hole, and the upper insulation layer is provided with a second through hole; The integrated graphitization device for lithium battery negative electrode graphite and carbon fiber also includes a material shaking mechanism, which includes a material frame, a lifting rod and a lifting drive component. The material frame is located in the second heating chamber and is used to be fixed to the outer edge of the carbon fiber felt. The lower end of the lifting rod is fixedly connected to the material frame, and the upper end of the lifting rod passes through the first through hole and the second through hole and is connected to the lifting drive component.

[0013] In some embodiments, the lifting drive component includes a base plate, a guide rod, a lifting plate and a lifting drive cylinder. The base plate is fixed above the upper insulation layer, the guide rod is fixed to the base plate, a guide hole is provided on the lifting plate to cooperate with the guide rod, the lifting plate can move up and down along the guide rod, the lifting plate is fixedly connected to the upper end of the lifting rod, the cylinder body of the lifting drive cylinder is fixed to the base plate, the output shaft of the lifting drive cylinder is connected to the lifting plate, and is used to drive the lifting plate to move up and down.

[0014] The present invention also provides a method for integrated graphitization of negative electrode graphite and carbon fiber of a lithium battery, which is applicable to the integrated graphitization device of negative electrode graphite and carbon fiber of a lithium battery, and comprises the following steps: S1, putting the negative electrode graphite of the lithium battery into a crucible, then putting the crucible into a first heating chamber, and putting the carbon fiber felt into a second heating chamber; S2, energizing the heating layer to heat the negative electrode graphite and carbon fiber felt of the lithium battery; S3. During heating, an inert gas is introduced into the air duct through the blowing mechanism, and the inert gas is discharged from the air outlet and blown onto the surface of the carbon fiber felt to remove ash impurities generated during the heating process of the carbon fiber felt; S4, completing the graphitization of lithium battery negative electrode graphite and carbon fiber felt.

[0015] Compared with the prior art, the device and method for integrated graphitization of lithium battery negative electrode graphite and carbon fiber provided by the present invention have the following beneficial effects: the heating chamber is divided into a first heating chamber and a second heating chamber by a barrier block, the lithium battery negative electrode graphite is loaded into a crucible, and then the crucible is loaded into the first heating chamber, and the carbon fiber felt is placed in the second heating chamber, thereby enabling integrated graphitization of the lithium battery negative electrode graphite and the carbon fiber to reduce equipment cost and energy consumption, and at the same time, an inert gas is introduced into the air duct through a blowing mechanism, and the inert gas is discharged from the air outlet and blown onto the surface of the carbon fiber felt to remove ash impurities generated during the heating process of the carbon fiber felt, and the ash impurities on the surface of the carbon fiber felt can be effectively discharged to avoid ash impurities saturation affecting the graphitization effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of a lithium battery negative electrode graphite and carbon fiber integrated graphitization device provided by one embodiment of the present invention; Figure 2 yes Figure 1 A schematic diagram of the structure of the furnace body; Figure 3 yes Figure 1 A partial enlarged view of the middle area A; Figure 4 yes Figure 1 A partial enlarged view of the middle area B; Description of the accompanying drawings: 1-furnace body, 11-brick wall layer, 111-second vent hole, 12-insulation layer, 121-upper insulation layer, 1211-second air inlet hole, 1212-second through hole, 122-lower insulation layer, 123-side insulation layer, 1231-first vent hole, 13-heating layer, 131-first heating chamber, 132-second heating chamber, 1321-receiving trough, 133-upper heating layer, 1331-first air inlet hole, 1332-first through hole, 134 -lower heating layer, 14-blocking block, 141-air duct, 142-air outlet, 2-blowing mechanism, 21-fixed seat, 22-air pump, 23-inlet pipe, 24-inlet valve, 25-vacuum pump, 26-exhaust pipe, 27-exhaust valve, 28-vent valve, 3-carbon fiber felt, 4-crucible, 5-shaking material mechanism, 51-material frame, 52-lifting rod, 53-lifting drive member, 531-bottom plate, 532-guide rod, 533-lifting plate, 534-lifting drive cylinder. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0018] In order to solve the technical problem that the graphitization of lithium battery negative electrode and carbon fiber are completed in different graphitization furnaces, which not only increases the equipment cost but also increases the energy consumption of the graphitization process, the present invention provides a lithium battery negative electrode graphite and carbon fiber integrated graphitization device and method, which can realize the integrated graphitization of lithium battery negative electrode graphite and carbon fiber to reduce equipment cost and energy consumption.

[0019] See also Figure 1 , Figure 1 It is a structural schematic diagram of an integrated graphitization device and method for negative electrode graphite and carbon fiber of a lithium battery in one embodiment of the present invention. The integrated graphitization device for negative electrode graphite and carbon fiber of a lithium battery comprises a furnace body 1 and a blowing mechanism 2.

[0020] See also Figure 1-Figure 3The furnace body 1 includes a brick wall layer 11, a heat-insulating layer 12, a heating layer 13 and a barrier block 14. The heat-insulating layer 12 is embedded in the brick wall layer 11, and the heating layer 13 is embedded in the heat-insulating layer 12. The heating layer 13 has a closed heating chamber. The barrier block 14 is built in the heating chamber and divides the heating chamber into a first heating chamber 131 and a second heating chamber 132. The first heating chamber 131 is used for graphitizing the negative electrode graphite of the lithium battery, and the second heating chamber 132 is used for graphitizing the carbon fiber felt 3. An air duct 141 is formed in the barrier block 14, and a side wall of the barrier block 14 close to the second heating chamber 132 is densely covered with air outlet holes 142 connected to the air duct 141; The impurity blowing mechanism 2 is used to introduce inert gas into the air duct 141 .

[0021] When in use, the negative electrode graphite of the lithium battery is loaded into the crucible 4, and then the crucible 4 is loaded into the first heating chamber 131, and the carbon fiber felt 3 is placed in the second heating chamber 132; the heating layer 13 is energized to heat the negative electrode graphite of the lithium battery and the carbon fiber felt 3; during heating, an inert gas is introduced into the air duct 141 through the blowing mechanism 2, and the inert gas is discharged from the air outlet 142 and blown onto the surface of the carbon fiber felt 3 to remove ash impurities generated during the heating process of the carbon fiber felt 3 until the graphitization of the negative electrode graphite of the lithium battery and the carbon fiber felt 3 is completed.

[0022] The present invention divides the heating chamber into a first heating chamber 131 and a second heating chamber 132 by a barrier block 14, loads the negative electrode graphite of the lithium battery into a crucible 4, and then loads the crucible 4 into the first heating chamber 131, and places the carbon fiber felt 3 into the second heating chamber 132, so that the negative electrode graphite of the lithium battery and the carbon fiber can be graphitized in an integrated manner to reduce equipment cost and energy consumption, and at the same time, an inert gas is introduced into the air duct 141 through the blowing mechanism 2, and the inert gas is discharged from the air outlet 142 and blown onto the surface of the carbon fiber felt 3 to remove ash impurities generated during the heating process of the carbon fiber felt 3, and the ash impurities on the surface of the carbon fiber felt 3 can be effectively discharged to avoid the saturation of ash impurities affecting the graphitization effect.

[0023] In one embodiment, see Figure 1 The heating layer 13 is a resistor material layer, and heating is achieved by energizing the resistor material layer.

[0024] In one embodiment, see Figure 1-Figure 4The heating layer 13 includes an upper heating layer 133 and a lower heating layer 134, the upper heating layer 133 is located above the heating chamber, and the lower heating layer 134 is located below the heating chamber, and a first air inlet hole 1331 is opened on the upper heating layer 133, and the lower end of the first air inlet hole 1331 is communicated with the air duct 141; the thermal insulation layer 12 includes an upper thermal insulation layer 121, a lower thermal insulation layer 122 and a side thermal insulation layer 123, the upper thermal insulation layer 121 is located above the upper heating layer 133, and a second air inlet hole 1211 is opened on the upper thermal insulation layer 121, and the lower end of the second air inlet hole 1211 is communicated with the upper end of the first air inlet hole 1331, and the upper end of the second air inlet hole 1211 is communicated with the air outlet end of the blowing mechanism 2.

[0025] In one embodiment, see Figure 1 and Figure 2 A material receiving trough 1321 located below the second heating chamber 132 is provided on the upper end surface of the lower heating layer 134. The ash blown off from the carbon fiber felt 3 in the second heating chamber 132 will fall into the material receiving trough 1321 under the action of gravity. The material receiving trough 1321 needs to be cleaned regularly.

[0026] In one embodiment, see Figure 1-Figure 4 The blowing mechanism 2 includes a fixed seat 21, an air pump 22 and an air inlet pipe 23. The fixed seat 21 is fixed above the upper insulation layer 121. The air pump 22 is fixed to the fixed seat 21. The inlet of the air pump 22 is used to communicate with an inert gas source. The outlet of the air pump 22 is connected to one end of the air inlet pipe 23. The other end of the air inlet pipe 23 is connected to the upper end of the second air inlet hole 1211. The air inlet pipe 23 is provided with an air inlet valve 24.

[0027] In one embodiment, see Figure 1-Figure 4 The blowing mechanism 2 also includes a vacuum pump 25 and an exhaust pipe 26. The vacuum pump 25 is fixed to the fixing seat 21. The inlet of the vacuum pump 25 is connected to one end of the exhaust pipe 26. The other end of the exhaust pipe 26 is connected to the upper end of the second air inlet hole 1211. The exhaust pipe 26 is provided with an exhaust valve 27.

[0028] In one embodiment, see Figure 1-Figure 4 A first vent hole 1231 communicating with the second heating chamber 132 is formed in the side insulation layer 123, a second vent hole 111 communicating with the first vent hole 1231 is formed in the brick wall layer 11, and a vent valve 28 is provided at the outlet end of the second vent hole 111.

[0029] In this embodiment, when in use, vacuum is first performed. The specific method is to first close the vent valve 28 and the air inlet valve 24, open the exhaust valve 27, and then open the vacuum pump 25. The air in the second heating chamber 132 is discharged through the first air inlet hole 1331, the second air inlet hole 1211 and the exhaust pipe 26, thereby evacuating the second heating chamber 132. Then the exhaust valve 27 and the vacuum pump 25 are closed, and the air inlet valve 24 and the air pump 22 are opened. The inert gas enters the air duct 141 through the air pump 22, the air inlet pipe 23, the second air inlet hole 1211 and the first air inlet hole 1331. The inert gas is discharged from the air outlet 142 and blown onto the surface of the carbon fiber felt 3 to remove ash impurities generated during the heating process of the carbon fiber felt 3. The inert gas is finally discharged through the first vent hole 1231, the second vent hole 111 and the vent valve 28.

[0030] In one embodiment, see Figure 1-Figure 4 The upper heating layer 133 is provided with a first through hole 1332, and the upper insulation layer 121 is provided with a second through hole 1212; the lithium battery negative electrode graphite and carbon fiber integrated graphitization device also includes a material shaking mechanism 5, the material shaking mechanism 5 includes a material frame 51, a lifting rod 52 and a lifting drive member 53, the material frame 51 is located in the second heating chamber 132, and is used to be fixed to the outer edge of the carbon fiber felt 3, the lower end of the lifting rod 52 is fixedly connected to the material frame 51, and the upper end of the lifting rod 52 passes through The first perforation 1332 and the second perforation 1212 are connected to the lifting drive member 53. When in use, the lifting drive member 53 drives the material frame 51 to reciprocate up and down via the lifting rod 52, thereby shaking the carbon fiber felt 3 back and forth up and down. On the one hand, this can shake off ash impurities, and on the other hand, it can also make various parts of the carbon fiber felt 3 face the air outlet 142 in turn, so that various parts of the carbon fiber felt 3 can face the air outlet 142 and be blown by the inert gas, thereby improving the ash impurity removal effect.

[0031] In one embodiment, see Figure 1-Figure 4 The lifting drive member 53 includes a bottom plate 531, a guide rod 532, a lifting plate 533 and a lifting drive cylinder 534. The bottom plate 531 is fixed above the upper insulation layer 121. The guide rod 532 is fixed to the bottom plate 531. A guide hole matching the guide rod 532 is provided on the lifting plate 533. The lifting plate 533 can move up and down along the guide rod 532. The lifting plate 533 is fixedly connected to the upper end of the lifting rod 52. The cylinder body of the lifting drive cylinder 534 is fixed to the bottom plate 531. The output shaft of the lifting drive cylinder 534 is connected to the lifting plate 533 and is used to drive the lifting plate 533 to move up and down, thereby driving the lifting rod 52 to move up and down, and then driving the material frame 51 to move up and down.

[0032] The present invention also provides a method for integrated graphitization of negative electrode graphite and carbon fiber of a lithium battery, which is applicable to the integrated graphitization device of negative electrode graphite and carbon fiber of a lithium battery, and comprises the following steps: S1, loading the negative electrode graphite of the lithium battery into the crucible 4, then loading the crucible 4 into the first heating chamber 131, and placing the carbon fiber felt 3 into the second heating chamber 132; S2, energizing the heating layer 13, thereby heating the negative electrode graphite of the lithium battery and the carbon fiber felt 3; S3, during heating, an inert gas is introduced into the air duct 141 through the impurity blowing mechanism 2, and the inert gas is discharged from the air outlet 142 and blown toward the surface of the carbon fiber felt 3 to remove ash impurities generated during the heating process of the carbon fiber felt 3; S4, completing the graphitization of the lithium battery negative electrode graphite and the carbon fiber felt 3.

[0033] The present invention divides the heating chamber into a first heating chamber 131 and a second heating chamber 132 by a barrier block 14, loads the negative electrode graphite of the lithium battery into a crucible 4, and then loads the crucible 4 into the first heating chamber 131, and places the carbon fiber felt 3 into the second heating chamber 132, so that the negative electrode graphite of the lithium battery and the carbon fiber can be graphitized in an integrated manner to reduce equipment cost and energy consumption, and at the same time, an inert gas is introduced into the air duct 141 through the blowing mechanism 2, and the inert gas is discharged from the air outlet 142 and blown onto the surface of the carbon fiber felt 3 to remove ash impurities generated during the heating process of the carbon fiber felt 3, and the ash impurities on the surface of the carbon fiber felt 3 can be effectively discharged to avoid the saturation of ash impurities affecting the graphitization effect.

[0034] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A lithium battery negative electrode graphite and carbon fiber integrated graphitization device, characterized in that: include: A furnace body, the furnace body comprising a brick wall layer, a heat-insulating layer, a heating layer and a barrier block, the heat-insulating layer is embedded in the brick wall layer, the heating layer is embedded in the heat-insulating layer, the heating layer has a closed heating chamber, the barrier block is built in the heating chamber, and the heating chamber is divided into a first heating chamber and a second heating chamber, the first heating chamber is used for graphitizing the negative electrode graphite of the lithium battery, the second heating chamber is used for graphitizing the carbon fiber felt, an air duct is formed in the barrier block, and a side wall of the barrier block close to the second heating chamber is densely covered with air outlet holes connected to the air duct; and, A blowing mechanism is used to introduce inert gas into the air duct.

2. The integrated graphitization device for negative electrode graphite and carbon fiber of lithium battery according to claim 1, characterized in that: The heating layer is a resistor material layer.

3. The integrated graphitization device for negative electrode graphite and carbon fiber of lithium battery according to claim 1, characterized in that: The heating layer comprises an upper heating layer and a lower heating layer, the upper heating layer is located above the heating chamber, the lower heating layer is located below the heating chamber, a first air inlet hole is opened on the upper heating layer, and the lower end of the first air inlet hole is connected to the air duct; The insulation layer includes an upper insulation layer, a lower insulation layer and a side insulation layer. The upper insulation layer is located above the upper heating layer. A second air inlet hole is opened on the upper insulation layer. The lower end of the second air inlet hole is connected to the upper end of the first air inlet hole, and the upper end of the second air inlet hole is connected to the air outlet end of the blowing mechanism.

4. The lithium battery negative electrode graphite and carbon fiber integrated graphitization device according to claim 3, characterized in that: A material receiving groove located below the second heating cavity is provided on the upper end surface of the lower heating layer.

5. The lithium battery negative electrode graphite and carbon fiber integrated graphitization device according to claim 3, characterized in that: The impurity blowing mechanism includes a fixed seat, an air pump and an air inlet pipe. The fixed seat is fixed above the upper insulation layer, the air pump is fixed to the fixed seat, the inlet of the air pump is used to communicate with an inert gas source, the outlet of the air pump is connected to one end of the air inlet pipe, the other end of the air inlet pipe is connected to the upper end of the second air inlet hole, and the air inlet pipe is provided with an air inlet valve.

6. The lithium battery negative electrode graphite and carbon fiber integrated graphitization device according to claim 5, characterized in that: The blowing mechanism also includes a vacuum pump and an exhaust pipe. The vacuum pump is fixed to the fixing seat. The inlet of the vacuum pump is connected to one end of the exhaust pipe. The other end of the exhaust pipe is connected to the upper end of the second air inlet hole. The exhaust pipe is provided with an exhaust valve.

7. The lithium battery negative electrode graphite and carbon fiber integrated graphitization device according to claim 3, characterized in that: A first vent hole communicating with the second heating chamber is formed in the side insulation layer, a second vent hole communicating with the first vent hole is formed in the brick wall layer, and a vent valve is provided at the outlet end of the second vent hole.

8. The lithium battery negative electrode graphite and carbon fiber integrated graphitization device according to claim 3, characterized in that: The upper heating layer is provided with a first through hole, and the upper insulation layer is provided with a second through hole; The integrated graphitization device for lithium battery negative electrode graphite and carbon fiber also includes a material shaking mechanism, which includes a material frame, a lifting rod and a lifting drive component. The material frame is located in the second heating chamber and is used to be fixed to the outer edge of the carbon fiber felt. The lower end of the lifting rod is fixedly connected to the material frame, and the upper end of the lifting rod passes through the first through hole and the second through hole and is connected to the lifting drive component.

9. The lithium battery negative electrode graphite and carbon fiber integrated graphitization device according to claim 1, characterized in that: The lifting drive component includes a base plate, a guide rod, a lifting plate and a lifting drive cylinder. The base plate is fixed above the upper insulation layer, the guide rod is fixed to the base plate, a guide hole matching the guide rod is provided on the lifting plate, the lifting plate can move up and down along the guide rod, the lifting plate is fixedly connected to the upper end of the lifting rod, the cylinder body of the lifting drive cylinder is fixed to the base plate, the output shaft of the lifting drive cylinder is connected to the lifting plate, and is used to drive the lifting plate to move up and down.

10. A method for integrated graphitization of lithium battery negative electrode graphite and carbon fiber, characterized in that: The device is applicable to the lithium battery negative electrode graphite and carbon fiber integrated graphitization device as claimed in any one of claims 1 to 9, and comprises the following steps: S1, putting the negative electrode graphite of the lithium battery into a crucible, then putting the crucible into a first heating chamber, and putting the carbon fiber felt into a second heating chamber; S2, energizing the heating layer to heat the negative electrode graphite and carbon fiber felt of the lithium battery; S3. During heating, an inert gas is introduced into the air duct through the blowing mechanism, and the inert gas is discharged from the air outlet and blown onto the surface of the carbon fiber felt to remove ash impurities generated during the heating process of the carbon fiber felt; S4, completing the graphitization of lithium battery negative electrode graphite and carbon fiber felt.

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