Vacuum furnace, method for preparing silicon-based negative electrode material by using vacuum furnace, obtained material and application

Abstract

The embodiment of the invention relates to a vacuum furnace which comprises a furnace body, a heating reactor, a reaction cooling device, a cooling collector, a collecting cooling device, a temperature control device, a conveying pipeline, a first temperature sensor, a second temperature sensor and a vacuumizing device. According to the equipment, electrolyte doping can be achieved while materials are prepared, compared with the prior art, the improved equipment is utilized, a temperature control device and a conveying pipeline are additionally arranged in a cooling collection area, the temperature control device can control the temperature of a cooling collector, and an electronic valve is installed on the conveying pipeline so that the input mass can be adjusted; the material is more fully contacted with the solid electrolyte in the deposition process; the material conductivity is improved, and the fast charging performance is improved.

Description

Technical Field

[0001] The present invention relates to the field of preparation of battery anode materials, and in particular to a vacuum furnace, a method for preparing a silicon-based anode material using the same, the obtained material and its application. Background Art

[0002] Silicon oxide is a wide-bandgap semiconductor optical material and an important raw material for preparing optical coatings and anode materials for lithium-ion batteries. Silicon has characteristics such as a high theoretical capacity, a suitable working voltage, and a high natural abundance, and is a typical anode material for lithium-ion batteries. At present, the production equipment for silicon oxide is mostly a monomeric vacuum furnace, which is only used for simply producing silicon oxide, such as silicon monoxide, and the fast charging performance of silicon monoxide needs to be continuously optimized.

[0003] Therefore, there is a need for a vacuum furnace that can solve the above problems, which can achieve the deposition and modification of silicon oxide while preparing, and at the same time improve the fast charging performance of silicon oxide. Summary of the Invention

[0004] The object of the present invention is to address the deficiencies of the prior art by providing a vacuum furnace, a method for preparing a silicon-based anode material using the same, the obtained material and its application, which can achieve the doping of the electrolyte while preparing the material. Compared with the prior art, by using the improved equipment, a temperature control device and a conveying pipeline are added in the cooling and collection area. The temperature control device can control the temperature of the cooling collector, and the solid electrolyte is conveyed to the inside of the cooling collector through the conveying pipeline. An electronic valve is installed on the pipeline to adjust the required mass, so that the material can be in more sufficient contact with the solid electrolyte during the deposition process, improve the conductivity of the material, and improve the fast charging performance.

[0005] In view of this, in a first aspect, an embodiment of the present invention provides a vacuum furnace, which includes a furnace body, a heating reactor, a reaction cooling device, a cooling collector, a collection cooling device, a temperature control device, a conveying pipeline, a first temperature sensor, a second temperature sensor, and a vacuum pumping device; wherein,

[0006] The furnace body includes a fixed half furnace body and a movable half furnace body; the end of the fixed half furnace body is connected to the movable half furnace body through a mechanical buckle;

[0007] The heating reactor is arranged in the fixed half furnace body and is used for placing raw materials;

[0008] The reaction cooling device is arranged in the furnace wall of the furnace body to cool down the furnace wall of the furnace body;

[0009] The cooling collector is arranged in the movable half furnace body to collect the cooled material;

[0010] The described collection and cooling device is arranged inside the furnace wall of the movable semi-furnace body to cool down the movable semi-furnace body and the cooling collector.

[0011] The temperature control device is connected to the cooling collector and is used to control the temperature of the cooling collector.

[0012] The described conveying pipeline transports the electrolyte to the cooling collector through the pipeline; an electronic valve is arranged above the conveying pipeline to control the mass of the electrolyte introduced.

[0013] The described first temperature sensor is used to detect the internal temperature of the heating reactor.

[0014] The described second temperature sensor is used to detect the internal temperature of the cooling collector.

[0015] The described vacuum pumping device is connected to the furnace body to evacuate the interior of the furnace body.

[0016] Preferably, the conveying pipeline is made of stainless steel, with an outer diameter of 1 - 3 cm. The length of the conveying pipeline inside the cooling collector is 5 - 30 cm, and the diameter is 0.5 - 1 cm. There are multiple openings on it. The number of the openings is 2 - 20, and the diameter is 0.1 - 2 mm.

[0017] Preferably, the diameter of the heating reactor is 20 - 30 cm, the thickness is 2 - 5 cm, and the length is 50 - 100 cm; the diameter of the cooling collector is 30 - 50 cm, the thickness is 0.2 - 0.5 cm, and the length is 50 - 80 cm; the ultimate vacuum of the vacuum pumping device is 0.01 pa; the reaction cooling device maintains the outer surface temperature of the furnace wall in the range of 15 - 40 °C; the temperature measurement ranges of the first temperature sensor and the second temperature sensor are 0 - 1600 °C; the controllable temperature range of the temperature control device is 50 - 500 °C.

[0018] Preferably, the heating reactor includes a heating reaction tank body, a heating device, and a heat preservation device.

[0019] The heating reaction tank body is used to hold raw materials.

[0020] The heating device is arranged around the outer surface of the heating reaction tank body to heat the raw materials in the heating reaction tank body.

[0021] The heat preservation device is arranged between the heating reaction tank body and the heating device.

[0022] Second, the embodiment of the present invention provides a method for preparing a silicon-based anode material by using the vacuum furnace in the first aspect above. The method includes:

[0023] Open the furnace body, place the silicon oxide raw material in the heating reaction tank, close the furnace door, and evacuate the air.

[0024] Control the heating of the heating reactor. After the temperature of the heating reactor reaches the first preset temperature, turn on the temperature control device to control the temperature of the cooling collector; wherein, the first preset temperature is 280 - 300 °C.

[0025] After the temperature of the heating reactor reaches the second preset temperature, introduce the solid electrolyte into the cooling collector through the conveying pipeline. Thus, the silicon oxide mixed vapor generated by the heating reactor enters the cooling collector and is fully mixed with the solid electrolyte ejected through the conveying pipeline, so that the electrolyte and the silicon oxide mixed vapor are co-deposited to form a modified silicon-based composite doped with the electrolyte; wherein, the second preset temperature is 280 - 850 °C.

[0026] Cool down and discharge the material. After discharging, through crushing, demagnetization, and sieving, the silicon-based anode material containing the electrolyte is obtained.

[0027] Preferably, the silicon oxide raw material includes a mixture of silicon powder and silicon dioxide; the solid electrolyte includes: one of garnet-type solid electrolyte materials, NASCION-type solid electrolyte materials, LISICON-type solid electrolytes, halide electrolytes, perovskite-type solid electrolyte materials and their derivatives.

[0028] The garnet-type solid electrolyte is specifically: Li7A3B2O12, where A is one or more of La, Ca, Sr, Ba, K, etc., and B is one or more of Zr, Ta, Nb, Hf.

[0029] The LISICON-type solid electrolyte is specifically: Li14A(BO4)4, where A is one or more of Zr, Cr, Sn, and B is one or more of Si, S, P.

[0030] The NASICON-type solid electrolyte is specifically: Li1+xAxB2+x(PO4)3, where the range of x is 0.01 - 0.5, A is one or more of Al, Y, Ga, Cr, In, Fe, Se, La, and B is one or more of Ti, Ge, Ta, Zr, Sn, Fe, V, Hf.

[0031] The halide electrolyte is specifically: one or more of chlorides, bromides, and iodides.

[0032] The perovskite solid electrolyte is specifically: Li3xA2 / 3-xBO3, wherein the range of x is 0.01-0.5, A is one or more of La, Al, Mg, Fe, Ta, B is one or more of Ti, Nb, Sr, Pr, and the particle size is between 0.1-20 μm.

[0033] Preferably, the particle size Dv50 of the silicon-based negative electrode material is 0.5nm-10μm, and the tap density is 0.8-1.3g / cm 3 .

[0034] In a third aspect, an embodiment of the present invention provides a silicon-based negative electrode material, wherein the silicon-based negative electrode material includes the silicon-based negative electrode material prepared by the preparation method of the second aspect.

[0035] In a fourth aspect, an embodiment of the present invention provides a negative electrode plate, wherein the negative electrode plate comprises the silicon-based negative electrode material according to the second aspect.

[0036] In a fifth aspect, an embodiment of the present invention provides a lithium battery comprising the negative electrode plate of the fourth aspect.

[0037] The embodiments of the present invention provide a vacuum furnace and a method for preparing silicon-based negative electrode materials using the same, the obtained materials and applications. The fixed half furnace body and the movable half furnace body can be quickly installed and disassembled by mechanical clips. The silicon-oxygen mixed vapor generated by the heating reactor enters the cooling collector and is fully mixed with the electrolyte sprayed through the delivery pipe, so that the electrolyte and the silicon-oxygen mixed vapor are deposited together; a modified silicon-based composite doped with electrolyte is formed; and the conduction rate of lithium ions inside the particles can be accelerated, so that the prepared battery has fast charging performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram of the structure of a vacuum furnace provided in an embodiment of the present invention;

[0039] Figure 2 A schematic diagram of the structure of a fixed half furnace body of a vacuum furnace provided in an embodiment of the present invention;

[0040] Figure 3 A schematic diagram of the structure of a movable half furnace body of a vacuum furnace provided in an embodiment of the present invention;

[0041] Figure 4 A flow chart of a method for preparing silicon-based negative electrode materials using a vacuum furnace is provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments.

[0043] Figure 1 The structural schematic diagram of a vacuum furnace provided by an embodiment of the present invention Figure 2 The structural schematic diagram of the fixed half furnace body of a vacuum furnace provided by an embodiment of the present invention Figure 3 The structural schematic diagram of the movable half furnace body of a vacuum furnace provided by an embodiment of the present invention. As Figures 1 to 3 shown, the vacuum furnace includes a furnace body 1, a heating reactor 2, a reaction cooling device 3, a cooling collector 4, a collection cooling device 5, a temperature control device 6, a conveying pipeline 7, a first temperature sensor 81, a second temperature sensor 82, and a vacuum pumping device 9. The following will introduce the structures of each part of the vacuum furnace in combination with Figures 1 to 3 introduce the structures of each part of the vacuum furnace

[0044] The furnace body 1 specifically includes a fixed half furnace body 11 and a movable half furnace body 12. The end of the fixed half furnace body 11 is preferably connected to the movable half furnace body 12 through a mechanical buckle 13. The mechanical buckle 13 can be used to quickly install and disassemble the fixed half furnace body 11 and the movable half furnace body 12

[0045] The heating reactor 2 is arranged in the fixed half furnace body 11 and is used to place raw materials. The raw materials in the heating reaction tank body 21 are heated by the heating device 22 of the heating reactor 2, so that the raw materials react to generate vapor. In a specific example, the heating reactor 2 includes a heating reaction tank body 21, a heating device 22, and a heat preservation device 23. Among them, the heating reaction tank body 21 is used to hold raw materials, and high temperature resistant materials such as corundum, graphite, alumina, and ceramics can be selected; the heating device 22 is arranged on the outer surface of the heating reaction tank body 21 to heat the raw materials in the heating reaction tank body 21, and induction heating or resistance heating can be selected; the heat preservation device 23 is arranged between the heating reaction tank body 21 and the heating device 22, and heat preservation cotton or felt can be selected. The diameter of the heating reactor 2 is preferably 20 - 30 cm, the thickness is preferably 2 - 5 cm, and the length is preferably 50 - 100 cm. Preferably, a flow controller 140 is further included in the furnace body to monitor the flow rate of the gas in the furnace body

[0046] The reaction cooling device 3 is arranged in the furnace wall of the furnace body 1 to cool down the furnace wall of the furnace body 1 and keep the outer surface temperature of the furnace wall in the range of 15 - 40 °C. Preferably, it is a water circulation cooling device, which has a simple structure and can effectively reduce the cooling cost of this multi-chamber horizontal vacuum furnace

[0047] The cooling collector 4 is arranged in the movable half furnace body 12 to collect the cooled materials. The diameter here is preferably 30 - 50 cm, the thickness is preferably 0.2 - 0.5 cm, and the length is preferably 50 - 80 cm

[0048] The collection and cooling device 5 is arranged inside the furnace wall of the movable half furnace body 12 and is used to cool down the movable half furnace body 12 and the cooling and collection device 4. Preferably, it is a water circulation cooling device, which has a simple structure and can effectively reduce the cooling cost of this multi-chamber horizontal vacuum furnace. In a specific process, to accelerate the condensation of the vapor in the collection part, the collection and cooling device 5 of the cooling and collection device 4 cools the cooling and collection device 4, that is, heat exchange is carried out on the vapor in the collection tank body. After reaching a certain temperature, the collection part is cooled by the cooling medium and the collection and cooling device 5 to prepare for the next separation work of the heating reactor 2 and the cooling and collection device 4.

[0049] The temperature control device 6 is connected to the cooling and collection device 4 and is used to control the temperature of the cooling and collection device 4. The material is stainless steel. The temperature is measured by an external temperature sensor, and the temperature is controlled by the circulating water flow. The controllable temperature range is preferably 50 - 500 °C.

[0050] The conveying pipeline 7 conveys the solid electrolyte to the cooling and collection device 4 through the pipeline; an electronic valve 71 is arranged above the conveying pipeline 7 to control the quality of the introduced electrolyte, and the electrolyte can be continuously introduced quantitatively. In a preferred embodiment, the conveying pipeline 7 is made of stainless steel, with an outer diameter of 1 - 3 cm. The length of the conveying pipeline 7 inside the cooling and collection device 4 is 5 - 30 cm, and the diameter is 0.5 - 1 cm. There are multiple openings on it, the number of openings is 2 - 20, and the diameter is 0.1 - 2 mm.

[0051] The first temperature sensor 81 is arranged inside the heating reactor 2 and is used to detect the temperature inside the heating reactor 2.

[0052] The second temperature sensor 82 is arranged inside the cooling and collection device 4 and is used to detect the temperature inside the cooling and collection device 4; here, the temperature measurement ranges of the first temperature sensor 81 and the second temperature sensor 82 are preferably 0 - 1600 °C.

[0053] The vacuum pumping device 9 is connected to the furnace body 1 and is used to pump the inside of the furnace body 1 into a vacuum. The ultimate vacuum is preferably 0.01 Pa.

[0054] In a preferred embodiment, a plurality of fixed support columns 110 are arranged at the lower part of the fixed half furnace body 11 to fix and support the fixed half furnace body 11; a plurality of sliding support columns 120 are evenly arranged at the lower part of the movable half furnace body 12 for sliding on the ground track 130.

[0055] On the basis of understanding the structure of the integrated vacuum furnace provided in this embodiment, the method for preparing the silicon-based anode material by applying this vacuum furnace is introduced below. Specifically, it is a method for preparing a high-performance anode material for a secondary lithium-ion battery by using a new type of vacuum furnace, and it is also a method for silicon oxide deposition and modification doping. Figure 4The following is a flowchart of a method for preparing a silicon-based anode material using a vacuum furnace provided by an embodiment of the present invention. Combining Figure 4 as shown, the preparation method of the silicon-based anode material specifically includes the following steps.

[0056] Step 101: Open the furnace body, place the silicon-oxygen raw material in the heating reaction tank, close the furnace door, and evacuate.

[0057] The silicon-oxygen raw material here includes a mixture of silicon powder and silicon dioxide.

[0058] The solid electrolyte here includes: one of garnet-type solid electrolyte materials, NASCION-type solid electrolyte materials, LISICON-type solid electrolytes, halide electrolytes, perovskite-type solid electrolyte materials and their derivative materials.

[0059] The above-mentioned garnet-type solid electrolyte is specifically: Li7A3B2O12, where A is one or more of La, Ca, Sr, Ba, K, etc., and B is one or more of Zr, Ta, Nb, Hf, etc.

[0060] The above-mentioned LISICON-type solid electrolyte is specifically: Li14A(BO4)4, where A is one or more of Zr, Cr, Sn, and B is one or more of Si, S, P.

[0061] The above-mentioned NASICON-type solid electrolyte is specifically: Li1+xAxB2+x(PO4)3, where the range of x is 0.01 - 0.5, A is one or more of Al, Y, Ga, Cr, In, Fe, Se, La, etc., and B is one or more of Ti, Ge, Ta, Zr, Sn, Fe, V, Hf, etc.

[0062] The above-mentioned halide electrolyte is specifically one or more of chlorides, bromides, and iodides.

[0063] The above-mentioned perovskite-type solid electrolyte is specifically: Li3xA2 / 3-xBO3, where the range of x is 0.01 - 0.5, A is one or more of La, Al, Mg, Fe, Ta, etc., B is one or more of Ti, Nb, Sr, Pr, etc., and the particle size is between 0.1 - 20 μm.

[0064] Preferably, the above-mentioned solid electrolyte is preferably LiCl, sodium oxide, lithium sulfide, sodium sulfide or yttrium LiCl.

[0065] Step 102: Control the heating reactor to heat. When the temperature of the heating reactor reaches the first preset temperature, turn on the temperature control device to control the temperature of the cooling collector.

[0066] Among them, the first preset temperature is 280 - 300 °C.

[0067] Specifically, after the evacuation device evacuates the interior of the furnace body to 0.1 Pa, heating is started. After the temperature of the heating reactor reaches the first preset temperature, the temperature control device is turned on to control the temperature of the cooling collector, and the controllable temperature range is preferably 50 - 500 °C.

[0068] Step 103: When the temperature of the heating reactor reaches the second preset temperature, solid electrolyte is introduced into the cooling collector through the conveying pipeline. Thus, the silicon-oxygen mixed vapor generated by the heating reactor enters the cooling collector and is fully mixed with the electrolyte ejected through the conveying pipeline, so that the electrolyte and the silicon-oxygen mixed vapor are co-deposited to form a modified silicon-based composite doped with electrolyte.

[0069] Among them, the second preset temperature is 280 - 850 °C.

[0070] Step 104: Cool down and discharge the material. After discharging, through crushing, demagnetization, and sieving, the silicon-based anode material containing the electrolyte is obtained.

[0071] Specifically, after the temperature at the crucible end reaches 80 °C - 100 °C, the furnace door is opened for discharging. After discharging, through crushing, demagnetization, and sieving, the silicon-based anode material containing the electrolyte is obtained.

[0072] Finally, the particle size Dv50 of the prepared silicon-based anode material is 0.5 nm - 10 μm, and the tapped density is 0.8 - 1.3 g / cm 3 。

[0073] The embodiment of the present invention also provides a silicon-based anode material, which is a silicon-based material with high first-cycle efficiency for secondary lithium-ion batteries prepared by using the above preparation method. Preferably, the silicon-based material with high first-cycle efficiency for secondary lithium-ion batteries includes conventional silicon oxide, pre-magnesium silicon oxide, pre-lithium silicon oxide, silicon-carbon, doped and modified silicon-based materials, etc.

[0074] Furthermore, the embodiment of the present invention also provides a negative electrode sheet using the silicon-based anode material in the above embodiment.

[0075] Even further, the embodiment of the present invention also provides a lithium battery including the negative electrode sheet in the above embodiment.

[0076] To better understand the technical solution provided by the present invention, the following uses specific examples to illustrate the specific process of preparing a high-performance negative electrode material for secondary lithium-ion batteries by using the method provided in the above embodiment of the present invention, as well as the method of applying it to a lithium-ion battery and the battery characteristics.

[0077] Example 1

[0078] This embodiment provides a method for preparing a high-performance anode material for a secondary lithium-ion battery using an integrated vacuum furnace, including:

[0079] Step 1: Open the furnace body, place 2.5 kg of silicon and 2.5 kg of silica raw materials in the heating reaction tank, close the furnace door, and evacuate the air.

[0080] Step 2: After the vacuum reaches 0.1 Pa, increase the temperature at a rate of 50 °C every 20 minutes until it reaches 900 °C and hold for 1 hour.

[0081] Step 3: After the temperature of the heating reactor reaches 300 °C, turn on the temperature control device to control the temperature of the collection area at 200 °C.

[0082] Step 4: After the temperature reaches 850 °C, introduce LiCl into the cooling collector through the conveying device at a rate of 2 g / min. After stopping heating, continue to introduce it for another 20 minutes and then close the electronic valve to stop inputting LiCl.

[0083] Step 5: After the temperature at the crucible end reaches 80 °C, open the furnace door to discharge the material.

[0084] Step 6: Finally, after discharging, the material is crushed, demagnetized, and sieved to obtain a silicon monoxide material containing the electrolyte.

[0085] The silicon monoxide material containing LiCl prepared in this embodiment is used to prepare a battery for testing.

[0086] Preparation method and testing of the full battery: Preparation of the negative electrode sheet: A composite body with a specific capacity of 450 mAh / g is configured by mixing a low-expansion silicon-based composite material containing a solid electrolyte and graphite, and a conductive additive and a binder are weighed and mixed in a ratio of 95%:2%:3%. At room temperature, the mixed material and deionized water as the solvent are put into a pulper to prepare a slurry. The prepared slurry is evenly coated on a copper foil at a coating speed between 2.2 m / min and 3.5 m / min, and the drying oven temperature of the coater is between 70 °C and 100 °C. After double-sided drying by the coater, a negative electrode sheet is obtained.

[0087] Preparation of the positive electrode sheet: Lithium nickel cobalt manganese oxide (NMC) ternary positive electrode material, a conductive additive, and a binder are weighed and mixed in a ratio of 96%:2%:2%. At room temperature, the mixed material and N-methylpyrrolidone as the solvent are put into a pulper to prepare a slurry. The prepared slurry is evenly coated on an aluminum foil at a coating speed between 2.0 m / min and 3.0 m / min, and the baking track temperature of the coater is between 90 °C and 120 °C. After double-sided coating and drying by the coater, a positive electrode sheet is obtained.

[0088] Preparation of the battery: For the positive electrode of the positive electrode sheet, an aluminum tab is used as the exposed tab, and for the negative electrode of the negative electrode sheet, a nickel-plated copper tab is used as the exposed tab. The prepared positive and negative electrode sheets and the separator are wound into a bare cell, and then the cell is encapsulated with an aluminum-plastic film through a heat-sealing process. The battery is baked at high temperature in vacuum to remove moisture, and then 1 mole of solid electrolyte is injected. The solid electrolyte is a mixed solution of LiPF6 and ethylene carbonate / dimethyl carbonate (EC / DMC). After making the cell and vacuum-sealing it, the battery is prepared.

[0089] Testing: The constant current charge-discharge mode test is carried out using a charge-discharge instrument. The discharge cut-off voltage is 2.75V, and the charge cut-off voltage is 4.2V. The charge-discharge test after the first week is carried out at a current density of 1C and 3C.

[0090] Example 2

[0091] This example provides a method for preparing a high-performance negative electrode material for a secondary lithium-ion battery using an integrated vacuum furnace, including:

[0092] Step 1: Open the furnace body, place 2.5 kg of silicon and 2.5 kg of silicon dioxide raw materials in the heating reaction tank body, close the furnace door, and evacuate.

[0093] Step 2: After the vacuum reaches 0.1 Pa, the heating rate is 50 °C / 20 minutes, and it is heated to 900 °C and held for 1 hour.

[0094] Step 3: After the temperature of the heating reactor reaches 300 °C, turn on the temperature control device to control the temperature of the collection area at 200 °C.

[0095] Step 4: After the temperature reaches 850 °C, LiCl is introduced into the cooling collector through the conveying device at a rate of 2.5 g / min; after stopping heating, it is continuously introduced for another 20 minutes and then the electronic valve is closed to stop the input of LiCl.

[0096] Step 5: After the temperature at the crucible end reaches 100 °C, open the furnace door to discharge the material.

[0097] Step 6: Finally, after discharging, it is pulverized, demagnetized, and sieved to obtain a silicon monoxide material containing an electrolyte.

[0098] The battery is prepared using the silicon monoxide material containing LiCl prepared in this example for testing. The specific process is the same as that in Example 1. The test data are shown in Table 1.

[0099] Example 3

[0100] This example provides a method for preparing a high-performance negative electrode material for a secondary lithium-ion battery using an integrated vacuum furnace, including:

[0101] Step 1: Open the furnace body, place 2.5 kg of silicon and 2.5 kg of silica raw materials in the heating reaction tank, close the furnace door, and evacuate.

[0102] Step 2: After the vacuum reaches 0.1 Pa, increase the temperature at a rate of 50 °C every 20 minutes until it reaches 900 °C and hold for 1 hour.

[0103] Step 3: After the temperature of the heating reactor reaches 300 °C, turn on the temperature control device to control the temperature of the collection area at 200 °C.

[0104] Step 4: After the temperature reaches 850 °C, introduce LiCl into the cooling collector through the conveying device at a rate of 3 g / min; after stopping heating, continue to introduce it for another 20 minutes and then close the electronic valve to stop inputting LiCl.

[0105] Step 5: After the temperature at the crucible end reaches 100 °C, open the furnace door to discharge the material.

[0106] Step 6: Finally, after discharging, through crushing, demagnetization, and sieving, the silicon monoxide material containing the electrolyte is obtained.

[0107] Use the silicon monoxide material containing LiCl prepared in this example to prepare a battery for testing. The specific process is the same as that in Example 1. The test data are shown in Table 1.

[0108] Example 4

[0109] This example provides a method for preparing a high-performance anode material for a secondary lithium-ion battery using an integrated vacuum furnace, including:

[0110] Step 1: Open the furnace body, place 2.5 kg of silicon and 2.5 kg of silica raw materials in the heating reaction tank, close the furnace door, and evacuate.

[0111] Step 2: After the vacuum reaches 0.1 Pa, increase the temperature at a rate of 50 °C every 20 minutes until it reaches 900 °C and hold for 1 hour.

[0112] Step 3: After the temperature of the heating reactor reaches 300 °C, turn on the temperature control device to control the temperature of the collection area at 200 °C.

[0113] Step 4: After the temperature reaches 850 °C, introduce LiCl into the cooling collector through the conveying device at a rate of 3.5 g / min; after stopping heating, continue to introduce it for another 20 minutes and then close the electronic valve to stop inputting LiCl.

[0114] Step 5: After the temperature at the crucible end reaches 100 °C, open the furnace door to discharge the material.

[0115] Step 6: Finally, after discharging, through crushing, demagnetization, and sieving, the silicon monoxide material containing the electrolyte is obtained.

[0116] The battery was prepared and tested using the silicon monoxide material containing LiCl prepared in this example. The specific process was the same as that in Example 1. The test data are shown in Table 1 in detail.

[0117] Example 5

[0118] This example provides a method for preparing a high-performance anode material for a secondary lithium-ion battery using an integrated vacuum furnace, including:

[0119] Step 1: Open the furnace body, place 2.5 kg of silicon and 2.5 kg of silicon dioxide raw materials in the heating reaction tank body, close the furnace door, and evacuate.

[0120] Step 2: After the vacuum reaches 0.1 Pa, the heating rate is 50 °C / 20 minutes, and the temperature is raised to 900 °C and held for 1 h.

[0121] Step 3: After the temperature of the heating reactor reaches 300 °C, turn on the temperature control device to control the temperature of the collection area at 200 °C.

[0122] Step 4: After the temperature reaches 850 °C, pass LiCl into the cooling collector through the conveying device at a rate of 4 g / min; after stopping heating, continue to pass it for 20 minutes and then close the electronic valve to stop inputting LiCl.

[0123] Step 5: After the temperature at the crucible end reaches 100 °C, open the furnace door to discharge the material.

[0124] Step 6: Finally, after discharging, the material is pulverized, demagnetized, and sieved to obtain the silicon monoxide material containing the electrolyte.

[0125] The battery was prepared and tested using the silicon monoxide material containing LiCl prepared in this example. The specific process was the same as that in Example 1. The test data are shown in Table 1 in detail.

[0126] Example 6

[0127] This example provides a method for preparing a high-performance anode material for a secondary lithium-ion battery using an integrated vacuum furnace, including:

[0128] Step 1: Open the furnace body, place 2.5 kg of silicon and 2.5 kg of silicon dioxide raw materials in the heating reaction tank body, close the furnace door, and evacuate.

[0129] Step 2: After the vacuum reaches 0.1 Pa, the heating rate is 50 °C / 20 minutes, and the temperature is raised to 900 °C and held for 1 h.

[0130] Step 3: After the temperature of the heating reactor reaches 300 °C, turn on the temperature control device to control the temperature of the collection area at 200 °C.

[0131] Step 4: After the temperature reaches 850°C, LiCl is introduced into the cooling collector through the conveying device at a rate of 4.5 g / min. After stopping heating, continue to introduce it for another 20 minutes and then close the electronic valve to stop the input of LiCl.

[0132] Step 5: After the temperature at the crucible end reaches 100°C, open the furnace door to discharge the material.

[0133] Step 6: Finally, after discharging, through crushing, demagnetization, and sieving, the silicon monoxide material containing the electrolyte is obtained.

[0134] The battery is prepared and tested using the silicon monoxide material containing LiCl prepared in this example. The specific process is the same as that in Example 1. The test data are shown in Table 1.

[0135] Example 7

[0136] This example provides a method for preparing a high-performance negative electrode material for a secondary lithium-ion battery using an integrated vacuum furnace, including:

[0137] Step 1: Open the furnace body, place 2.5 kg of silicon and 2.5 kg of silicon dioxide raw materials in the heating reaction tank body, close the furnace door, and evacuate.

[0138] Step 2: After the vacuum reaches 0.1 Pa, the heating rate is 50°C / 20 minutes, and heat up to 900°C and hold for 1 h.

[0139] Step 3: After the temperature of the heating reactor reaches 300°C, turn on the temperature control device to control the temperature in the collection area at 200°C.

[0140] Step 4: After the temperature reaches 850°C, LiCl is introduced into the cooling collector through the conveying device at a rate of 5 g / min. After stopping heating, continue to introduce it for another 20 minutes and then close the electronic valve to stop the input of LiCl.

[0141] Step 5: After the temperature at the crucible end reaches 100°C, open the furnace door to discharge the material.

[0142] Step 6: Finally, after discharging, through crushing, demagnetization, and sieving, the silicon monoxide material containing the electrolyte is obtained.

[0143] The battery is prepared and tested using the silicon monoxide material containing LiCl prepared in this example. The specific process is the same as that in Example 1. The test data are shown in Table 1.

[0144] Example 8

[0145] This example provides a method for preparing a high-performance negative electrode material for a secondary lithium-ion battery using an integrated vacuum furnace, including:

[0146] Step 1: Open the furnace body, place 2.5 kg of silicon and 2.5 kg of silica raw materials in the heating reaction tank, close the furnace door, and evacuate the air.

[0147] Step 2: After the vacuum reaches 0.1 Pa, increase the temperature at a rate of 50 °C every 20 minutes until it reaches 900 °C and hold for 1 hour.

[0148] Step 3: After the temperature of the heating reactor reaches 300 °C, turn on the temperature control device to control the temperature of the collection area at 200 °C.

[0149] Step 4: After the temperature reaches 850 °C, introduce LiCl into the cooling collector through the conveying device at a rate of 5.5 g / min. After stopping heating, continue to introduce it for another 20 minutes and then close the electronic valve to stop inputting LiCl.

[0150] Step 5: After the temperature at the crucible end reaches 100 °C, open the furnace door to discharge the material.

[0151] Step 6: Finally, after discharging, through crushing, demagnetization, and sieving, the silicon monoxide material containing the electrolyte is obtained.

[0152] Use the silicon monoxide material containing LiCl prepared in this example to prepare a battery for testing. The specific process is the same as that in Example 1. The test data are shown in Table 1.

[0153] Example 9

[0154] This example provides a method for preparing a high-performance anode material for a secondary lithium-ion battery using an integrated vacuum furnace, including:

[0155] Step 1: Open the furnace body, place 2.5 kg of silicon and 2.5 kg of silica raw materials in the heating reaction tank, close the furnace door, and evacuate the air.

[0156] Step 2: After the vacuum reaches 0.1 Pa, increase the temperature at a rate of 50 °C every 20 minutes until it reaches 900 °C and hold for 1 hour.

[0157] Step 3: After the temperature of the heating reactor reaches 300 °C, turn on the temperature control device to control the temperature of the collection area at 200 °C.

[0158] Step 4: After the temperature reaches 850 °C, introduce LiCl into the cooling collector through the conveying device at a rate of 6 g / min. After stopping heating, continue to introduce it for another 20 minutes and then close the electronic valve to stop inputting LiCl.

[0159] Step 5: After the temperature at the crucible end reaches 100 °C, open the furnace door to discharge the material.

[0160] Step 6: Finally, after discharging, through crushing, demagnetization, and sieving, the silicon monoxide material containing LiCl is obtained.

[0161] The battery was prepared and tested using the silicon monoxide material containing LiCl prepared in this example. The specific process was the same as that in Example 1. The test data are shown in Table 1 in detail.

[0162] Example 10

[0163] This example provides a method for preparing a high-performance negative electrode material for a secondary lithium-ion battery using an integrated vacuum furnace, including:

[0164] Step 1: Open the furnace body, place 2.5 kg of silicon and 2.5 kg of silicon dioxide raw materials in the heating reaction tank body, close the furnace door, and evacuate.

[0165] Step 2: After the vacuum reaches 0.1 Pa, the heating rate is 50 °C / 20 minutes, and it is heated to 900 °C and held for 1 h.

[0166] Step 3: After the temperature of the heating reactor reaches 300 °C, turn on the temperature control device to control the temperature of the collection area, and the temperature is 200 °C.

[0167] Step 4: After the temperature reaches 850 °C, LiCl is introduced into the cooling collector through the conveying device at a rate of 7 g / min; after stopping heating, continue to introduce it for another 20 minutes and then close the electronic valve to stop inputting the solid electrolyte.

[0168] Step 5: After the temperature at the crucible end reaches 100 °C, open the furnace door to discharge the material.

[0169] Step 6: Finally, after discharging, it is pulverized, demagnetized, and sieved to obtain the silicon monoxide material containing LiCl.

[0170] The battery was prepared and tested using the silicon monoxide material containing LiCl prepared in this example. The specific process was the same as that in Example 1. The test data are shown in Table 1 in detail.

[0171] Comparative Example 1

[0172] This comparative example provides the preparation process and performance test of a traditional silicon-based negative electrode material. The specific preparation process is as follows.

[0173] Step 1: Open the furnace body, place 2.5 kg of silicon and 2.5 kg of silicon dioxide raw materials in the heating reaction tank body, close the furnace door, and evacuate.

[0174] Step 2: After the vacuum reaches 0.1 Pa, start heating to 900 °C, and the heating rate is 50 °C / 20 minutes. Hold at 900 °C for 1 h.

[0175] Step 3: After the temperature of the heating reactor reaches 300 °C, turn on the temperature control device to control the temperature of the collection area, and the temperature is 200 °C.

[0176] Step 5: After the temperature at the crucible end reaches 80 °C, open the furnace door for discharging.

[0177] Step 6: Finally, after discharging, through processes of crushing, demagnetizing, and sieving, the silicon monoxide material is obtained.

[0178] Use the silicon monoxide material prepared in this example to prepare a battery for testing. The specific process is the same as that in Example 1. The test data are shown in Table 1 for details.

[0179] Perform full-electricity tests on the anode materials in Examples 1-10 and the comparative examples respectively. After 500 cycles under the charge-discharge rates of 1C and 3C, the initial efficiency results are shown in Table 1:

[0180]

[0181] It can be known from the comparison of the test data in Table 1 that under the same test conditions, during the charge-discharge process at the rates of 1C and 3C for Examples 1-10, the initial efficiency of Examples 1-10 is better than that of the comparative examples. This is because in Examples 1-10, a new type of vacuum furnace is used, and during the deposition process, a solid electrolyte is introduced into it. The solid electrolyte will be doped in the silicon monoxide during the deposition process to increase the fast-charging performance. From the test data of Example 7 and Comparative Example 1, after 500 cycles of charge-discharge at the rate of 3C, the initial efficiency of Example 7 is higher than that of Comparative Example 1.

[0182] A vacuum furnace provided by an embodiment of the present invention, a method for preparing a silicon-based anode material using the same, the obtained material and its application realize the doping of the electrolyte while preparing the material. Compared with the prior art, by using the improved equipment, a temperature control device and a conveying pipeline are added in the cooling and collection area. The temperature control device can control the temperature of the cooling collector, and an electronic valve is installed on the conveying pipeline to adjust the input amount; so that the material can be in more sufficient contact with the solid electrolyte during the deposition process; improving the conductivity of the material and the fast-charging performance.

[0183] In the present invention, the term "plurality" means two or more, unless otherwise clearly defined. Terms such as "install", "connect", "join", "fix" and the like should be understood in a broad sense. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "join" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0184] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "rear", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or unit referred to must have a specific direction, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0185] In the description of this specification, the description of terms such as "a specific embodiment", "some embodiments", "an embodiment", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or instance. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0186] The specific embodiments described above further elaborate on the purpose, technical solution and beneficial effects of the present invention. It should be understood that the above is only the specific embodiment of the present invention and is not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A vacuum furnace, characterized in that, The vacuum furnace includes a furnace body, a heating reactor, a reaction cooling device, a cooling collector, a collection cooling device, a temperature control device, a conveying pipeline, a first temperature sensor, a second temperature sensor, and a vacuum pumping device; among them, the furnace body includes a fixed half furnace body and a movable half furnace body; the end of the fixed half furnace body is connected to the movable half furnace body through a mechanical buckle; the heating reactor is arranged inside the fixed half furnace body and is used for placing raw materials; the reaction cooling device is arranged inside the furnace wall of the furnace body to cool down the furnace wall of the furnace body; the cooling collector is arranged inside the movable half furnace body to collect the cooled materials; the collection cooling device is arranged inside the furnace wall of the movable half furnace body to cool down the movable half furnace body and the cooling collector; the temperature control device is connected to the cooling collector and is used for controlling the temperature of the cooling collector; the conveying pipeline conveys the electrolyte to the cooling collector through the pipeline; an electronic valve is arranged above the conveying pipeline to control the quality of the introduced electrolyte; the first temperature sensor is used for detecting the internal temperature of the heating reactor; the second temperature sensor is used for detecting the internal temperature of the cooling collector; the vacuum pumping device is communicated with the furnace body to evacuate the inside of the furnace body.

2. The vacuum furnace according to claim 1, characterized in that, The conveying pipeline is made of stainless steel, with an outer diameter of 1 - 3 cm. The length of the conveying pipeline inside the cooling collector is 5 - 30 cm, and the diameter is 0.5 - 1 cm. There are multiple openings on it. The number of the openings is 2 - 20, and the diameter is 0.1 - 2 mm.

3. The vacuum furnace according to claim 1, characterized in that, The diameter of the heating reactor is 20 - 30 cm, the thickness is 2 - 5 cm, and the length is 50 - 100 cm; the diameter of the cooling collector is 30 - 50 cm, the thickness is 0.2 - 0.5 cm, and the length is 50 - 80 cm; the ultimate vacuum of the vacuum pumping device is 0.01 pa; the reaction cooling device keeps the outer surface temperature of the furnace wall in the range of 15 - 40 °C; the temperature measurement range of the first temperature sensor and the second temperature sensor is 0 - 1600 °C; the controllable temperature range of the temperature control device is 50 - 500 °C.

4. The vacuum furnace according to claim 1, characterized in that, The heating reactor includes a heating reaction tank body, a heating device, and a heat preservation device; the heating reaction tank body is used for containing raw materials; the heating device is arranged on the outer surface of the heating reaction tank body in a ring shape to heat the raw materials in the heating reaction tank body; the heat preservation device is arranged between the heating reaction tank body and the heating device.

5. A method for preparing a silicon-based anode material using any one of the vacuum furnaces according to claims 1 to 4 above, characterized in that, The method includes: opening the furnace body, placing the silicon-oxygen raw materials in the heating reaction tank body, closing the furnace door, and evacuating; controlling the heating of the heating reactor, and when the temperature of the heating reactor reaches the first preset temperature, starting the temperature control device to control the temperature of the cooling collector; among them, the first preset temperature is 280 - 300 °C; After the temperature of the heating reactor reaches the second preset temperature, solid electrolyte is introduced into the cooling collector through a delivery pipeline. Thus, the silicon-oxygen mixed vapor generated by the heating reactor enters the cooling collector and is fully mixed with the solid electrolyte ejected through the delivery pipeline, so that the electrolyte and the silicon-oxygen mixed vapor are co-deposited to form a modified silicon-based composite doped with the electrolyte. Among them, the second preset temperature is 280-850 °C; Cool down and discharge. After discharging, through pulverizing, demagnetizing, and sieving, a silicon-based anode material containing the electrolyte is obtained.

6. The vacuum furnace according to claim 5, characterized in that, The silicon-oxygen raw material includes a mixture of silicon powder and silicon dioxide; the solid electrolyte includes: a garnet-type solid electrolyte material, a NASCION-type solid electrolyte material, a LISICON-type solid electrolyte, a halide electrolyte, a perovskite-type solid electrolyte material, and one of its derivative materials; The garnet-type solid electrolyte is specifically: Li7A3B2O12, where A is one or more of La, Ca, Sr, Ba, K, etc., and B is one or more of Zr, Ta, Nb, Hf; The LISICON-type solid electrolyte is specifically: Li14A(BO4)4, where A is one or more of Zr, Cr, Sn, and B is one or more of Si, S, P; The NASICON-type solid electrolyte is specifically: Li1+xAxB2+x(PO4)3, where the range of x is 0.01-0.5, A is one or more of Al, Y, Ga, Cr, In, Fe, Se, La, etc., and B is one or more of Ti, Ge, Ta, Zr, Sn, Fe, V, Hf; The halide electrolyte is specifically: one or more of chlorides, bromides, iodides; The perovskite-type solid electrolyte is specifically: Li3xA2 / 3-xBO3, where the range of x is 0.01-0.5, A is one or more of La, Al, Mg, Fe, Ta, etc., B is one or more of Ti, Nb, Sr, Pr, etc., and the particle size is between 0.1-20 μm.

7. The vacuum furnace according to claim 5, characterized in that, The particle size Dv50 of the silicon-based anode material is 0.5 nm-10 μm, and the tap density is 0.8-1.3 g / cm3.

8. A silicon-based anode material, characterized in that, The silicon-based anode material includes the silicon-based anode material prepared by the preparation method described in any one of claims 5-7 above.

9. A negative electrode sheet, characterized in that, The negative electrode sheet includes the silicon-based anode material described in claim 8 above.

10. A lithium battery, characterized in that, The lithium battery includes the negative electrode sheet described in claim 9 above.

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