A method and apparatus for preparing prelithiated silicon monoxide powder

Abstract

The application discloses a method and device for preparing pre-lithiated silicon monoxide powder, wherein silane gas passes through different temperature zones in the ascending process in the inner cavity of a fluidized bed, first forms a nanoscale nucleus, is combined with atomized silicon source, forms stable nanoscale silicon monoxide particles, then passes through atomized pre-lithium solution, completes pre-lithiation, and then passes through secondary granulation to form micron-level silicon monoxide particles with stable structure; in the descending process, the particle surface uniformly adsorbs the pre-lithium solution when passing through the pre-lithium solution atomization zone, completes the pre-lithiation of the secondary particles, and thus the pre-lithiated silicon monoxide powder is obtained. The method and device can synchronously complete the preparation and pre-lithiation of the silicon monoxide material, the prepared particles have stable structure and uniform internal lithium ion distribution, do not need secondary processing as a negative electrode material of a lithium ion battery, and the material has the characteristics of high initial efficiency and long cycle.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicon monoxide powder preparation, and particularly relates to a method and device for preparing pre-lithiated silicon monoxide powder. BACKGROUND

[0002] Silicon monoxide is widely concerned as a lithium ion negative electrode material with high capacity. At present, with the popularity of electric vehicles, the demand for high energy density lithium ion batteries is increasing, and the use of silicon monoxide negative electrode material is also increasing. However, a large amount of lithium silicate phase is formed in the first lithium intercalation process of the cycle of silicon monoxide, which is irreversible in the subsequent cycle process, resulting in low first coulomb efficiency. Therefore, as a lithium ion battery negative electrode material, silicon monoxide material generally needs to be pre-magnesium or pre-lithium first to generate magnesium silicate or lithium silicate in advance, reduce the generation of irreversible capacity in the first lithium intercalation process, and improve the first efficiency of the material. However, due to the high diffusion energy barrier of magnesium ions or lithium ions in the structure-stable solid silicon monoxide, the process needs to be completed at high temperature, which will damage the stable structure of silicon monoxide and lead to the decline of its cycle performance. SUMMARY

[0003] Based on the technical problems existing in the background technology, the present application provides a method and device for preparing pre-lithiated silicon monoxide powder. The silicon source and pre-lithium solution are atomized and combined with silane gas to synchronize the preparation of silicon monoxide and pre-lithium, so as to obtain silicon monoxide powder with stable structure and high first efficiency.

[0004] The device for preparing pre-lithiated silicon monoxide powder provided by the present application comprises a fluidized bed, a first atomizer and a second atomizer.

[0005] The inner cavity of the fluidized bed is sequentially provided with a first heat insulation plate and a second heat insulation plate from top to bottom, and the first heat insulation plate and the second heat insulation plate divide the inner cavity of the fluidized bed into a heating cavity, an upper reaction cavity and a lower reaction cavity from top to bottom, and the heating cavity, the upper reaction cavity and the lower reaction cavity are respectively provided with a first heating member, a second heating member and a third heating member.

[0006] The first heat insulation plate is provided with a gas outlet communicated with the outside through the heating cavity, and the gas outlet is provided with a guide plate; and the second heat insulation plate is provided with a through hole communicating the upper reaction cavity and the lower reaction cavity.

[0007] The first atomizer and the second atomizer are both installed on the fluidized bed and respectively communicated with the upper reaction cavity and the lower reaction cavity.

[0008] The bottom of the fluidized bed is provided with a gas inlet communicated with the lower reaction cavity and a discharge port.

[0009] Preferably, the second heating element and the first atomizer are arranged oppositely, and the third heating element and the second atomizer are arranged oppositely.

[0010] Preferably, the second heating element and the third heating element are located on the same side.

[0011] Preferably, the air inlet is connected to the gas mixing chamber through a pipeline, and the bottom of the gas mixing chamber is connected to the first air inlet pipe and the second air inlet pipe, respectively.

[0012] Preferably, the heating temperature range of the first heating element is 800-900℃, the heating temperature range of the second heating element is 750-1000℃, and the heating temperature range of the third heating element is 600-800℃.

[0013] Preferably, the first atomizer and the second atomizer each consist of an inner atomizer and an atomizer shell.

[0014] A method for preparing pre-lithiated silicon monoxide powder by using the device, comprising the following steps:

[0015] S1, start the first heating element, the second heating element and the third heating element of the device to heat sufficiently, and continuously introduce inert gas through the air inlet to maintain an inert atmosphere in the fluidized bed inner cavity;

[0016] S2, continuously atomize the organosilicon source solution into the lower reaction cavity of the fluidized bed through the second atomizer to form an organosilicon source solution atomization zone, continuously atomize the pre-lithium solution into the upper reaction cavity of the fluidized bed through the first atomizer to form a pre-lithium solution atomization zone, and then continuously introduce silane gas through the air inlet, and collect the pre-lithiated silicon monoxide powder at the discharge port.

[0017] In S2, after the silane gas is introduced, nano-sized silicon monoxide particles are first formed in the lower reaction cavity of the fluidized bed, then pre-lithiation is carried out in the upper reaction cavity of the fluidized bed, and then secondary granulation is carried out in the heating cavity of the fluidized bed to form micron-sized secondary particles, and then sink, and in the sinking process, pre-lithiation of the secondary particles is carried out in the upper reaction cavity of the fluidized bed, and then sink to the discharge port, and the pre-lithiated silicon monoxide powder is collected at the discharge port.

[0018] Preferably, the organosilicon source solution comprises an organosilicon source and a solvent, the molar ratio of the organosilicon source to the solvent is 1:(1-10), the organosilicon source is at least one of tetraethyl orthosilicate and tetra-n-butyl orthosilicate, and the solvent is diethyl ether.

[0019] Preferably, the pre-lithiation solution comprises a lithium source, a complexing agent and a solvent, the molar ratio of the lithium source to the complexing agent is (0.5-2):1, the molar ratio of the complexing agent to the solvent is 1:(1-10); the lithium source is at least one of lithium powder and lithium sheet; the complexing agent is at least one of dimethyl naphthalene, 1-methyl naphthalene, 2-methyl naphthalene, 1,7-dimethyl naphthalene and 2,3-dimethyl naphthalene; and the solvent is at least one of dimethyl ether, diphenyl ether and tetrahydrofuran.

[0020] Preferably, the silane gas is at least one of monosilane and disilane.

[0021] Preferably, the flow rate of the inert gas is 200-800 ml / min, the flow rate of the silane gas is 200-800 ml / min, the flow rate of the first atomizer is 150-300 m / s, and the flow rate of the second atomizer is 150-300 m / s.

[0022] Preferably, in S2, the pre-lithiated silicon monoxide powder is taken out from the discharge port by sedimentation or under the combined action of sedimentation and a guide plate.

[0023] Preferably, in S1, the first heating member, the second heating member and the third heating member of the starting device are heated sufficiently, so that the temperature in the heating cavity is 800-900℃, the temperature in the upper reaction cavity is 750-1000℃, and the temperature in the lower reaction cavity is 600-800℃.

[0024] Preferably, the organic silicon source solution, the pre-lithiation solution and the silane gas are continuously fed for 1-2 h.

[0025] Preferably, the inert gas and the silane gas are fed through the first gas inlet pipe and the second gas inlet pipe, respectively.

[0026] The present application has the following advantages:

[0027] The present application can efficiently utilize silane and organic silicon source to prepare high first efficiency silicon monoxide material with stable structure and complete prelithiation through special device and preparation method. The conversion degree of silane gas is controlled by controlling the temperature of different parts of the fluidized bed. The silane gas rises in the inner cavity of the fluidized bed and passes through different temperature zones. Firstly, it passes through the organic silicon source solution atomization zone of the lower reaction cavity to form nanoscale core, which is combined with the atomized silicon source to form stable nanoscale silicon monoxide particles at high temperature. Then, the particles pass through the prelithiation solution atomization zone of the upper reaction cavity. After the particles rise through the atomized prelithiation solution, the prelithiation solution is uniformly adsorbed on the surface of the particles. Lithium ions rapidly diffuse in the nanoscale silicon monoxide particles at high temperature to complete prelithiation. Then, the particles pass through the heating cavity located at the top of the inner cavity of the fluidized bed. When the particles reach the top of the fluidized bed, the silane gas is completely converted and deposited on the surface of the nanoscale silicon monoxide to complete secondary granulation and form micron-sized silicon monoxide particles with stable structure. The micron-sized silicon monoxide particles sink to the discharge port. When the particles pass through the prelithiation solution atomization zone during the descending process, the prelithiation solution is uniformly adsorbed on the surface of the particles. Lithium ion diffusion is completed by the internal temperature of the fluidized bed to complete the prelithiation of the secondary particles. Finally, the prelithiated silicon monoxide powder is collected at the discharge port. The preparation and prelithiation of silicon monoxide material can be completed simultaneously using the method and device of the present application. The prepared particles have stable structure and uniform distribution of lithium ions inside. As a negative electrode material for lithium ion batteries, the material does not need secondary processing and has the characteristics of high first efficiency and long cycle. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The structure diagram of the device for preparing prelithiated silicon monoxide powder proposed in the present application is shown.

[0029] Figure 2 The structure diagram of the atomizer in the device for preparing prelithiated silicon monoxide powder proposed in the present application is shown. DETAILED DESCRIPTION

[0030] The technical solutions of the present application will be described in detail below through specific embodiments.

[0031] Example 1

[0032] As shown in the structure diagram of the device for preparing prelithiated silicon monoxide powder proposed in the present application. Figure 1 Figure 1 The structure diagram of the device for preparing prelithiated silicon monoxide powder proposed in the present application is shown.

[0033] Figure 1 In the structure diagram, 1: first gas inlet pipe, 2: second gas inlet pipe, 3: gas mixing chamber, 4: gas inlet, 5: fluidized bed, 6: second atomizer, 7: first atomizer, 8: first heat insulation plate, 9: second heating element, 10: first heating element, 11: third heating element, 12: gas outlet, 13: guide plate, 14: discharge port, 15: second heat insulation plate. ​

[0034] Referring to Figure 1 The application provides a device for preparing pre-lithiated silicon monoxide powder, which comprises a fluidized bed 5, a first atomizer 7 and a second atomizer 6.

[0035] The inner cavity of the fluidized bed 5 is sequentially provided with a first heat insulation plate 8 and a second heat insulation plate 15 from top to bottom, and the inner cavity of the fluidized bed 5 is divided into a heating cavity, an upper reaction cavity and a lower reaction cavity from top to bottom by the first heat insulation plate 8 and the second heat insulation plate 15; and the heating cavity, the upper reaction cavity and the lower reaction cavity are respectively provided with a first heating member 10, a second heating member 9 and a third heating member 11.

[0036] The first heat insulation plate 8 is provided with a gas outlet 12 penetrating through the heating cavity and communicating with the outside; and the second heat insulation plate 15 is provided with a through hole communicating the upper reaction cavity and the lower reaction cavity.

[0037] The first atomizer 7 and the second atomizer 6 are both mounted on the fluidized bed 5 and respectively communicate with the upper reaction cavity and the lower reaction cavity.

[0038] The bottom of the fluidized bed 5 is provided with a gas inlet 4 and a discharge port 14, which respectively communicate with the lower reaction cavity.

[0039] In use, the third heating member 11 heats the lower reaction cavity of the inner cavity of the fluidized bed 5 to 600-800 DEG C, the second heating member 9 heats the upper reaction cavity of the inner cavity of the fluidized bed to 750-1000 DEG C, the first heating member 10 heats the heating cavity of the inner cavity of the fluidized bed 5 to 800-900 DEG C, the silane gas enters the lower reaction cavity of the inner cavity of the fluidized bed 5 through the gas inlet 4 to start decomposition to form nanometer silicon, the organic silicon source is atomized in the lower reaction cavity by the second atomizer 6 to form an organic silicon source solution atomization area, the organic silicon source is decomposed to form silicon dioxide gas at high temperature, and the silicon dioxide gas and the silicon steam decomposed from the silane form nanometer silicon monoxide particles, the pre-lithium solution is atomized in the upper reaction cavity by the first atomizer 7 to form a pre-lithium solution atomization area, the nanometer silicon monoxide particles pass through the upper reaction cavity to adsorb a large amount of the atomized pre-lithium solution, lithium ions rapidly diffuse into the nanometer silicon monoxide particles at high temperature to be uniformly distributed, the low-boiling-point solvent and part of the complexing agent in the pre-lithium solution are removed by the gas outlet 12, then pass through the heating cavity, at this time, the remaining silane in the upward gas is further decomposed to form nanometer silicon to deposit on the surface of the nanometer silicon monoxide particles and connect multiple particles to complete secondary granulation to form secondary particles with stable structure, the silane in the gas is completely decomposed at the high temperature of the heating cavity to form nanometer silicon to deposit on the surface of the secondary particles to further reduce the specific surface area and form micron-level stable structure, the silicon and oxygen mutually diffuse at high temperature to form micron-level silicon monoxide particles with uniform distribution of silicon and oxygen, and the particles sink to the discharge port 14, when passing through the pre-lithium solution atomization area in the sinking process, the particles uniformly adsorb the pre-lithium solution, and the lithium ion diffusion process is completed by the aid of the internal temperature of the fluidized bed, the pre-lithiation of the secondary particles is completed, and thus the pre-lithiated silicon monoxide powder is obtained. The present application realizes the synchronous completion of the preparation of silicon monoxide and pre-lithiation, pre-lithiates the material in nanometer size, the lithium ion transport distance is short, the uniform distribution of lithium ions in the material can be realized, then the secondary particles with stable structure are formed, and the material with stable structure does not need to be subjected to secondary pre-lithiation treatment in the later period.

[0040] In specific embodiments, the second heating member 9 and the first atomizer 7 are oppositely arranged, and the third heating member 11 and the second atomizer 6 are oppositely arranged.

[0041] In specific embodiments, the second heating member and the third heating member are located on the same side.

[0042] In specific embodiments, the gas outlet 12 is provided with a guide plate 13. The guide plate 13 guides the pre-lithiated silicon monoxide powder to the discharge port 14.

[0043] In specific embodiments, the gas inlet 4 is connected with the gas mixing chamber 3 through a pipeline, and the bottom of the gas mixing chamber 3 is respectively connected with the first gas inlet pipe 1 and the second gas inlet pipe 2 in communication. In which, the inert gas and the silane gas are respectively introduced through the first gas inlet pipe 1 and the second gas inlet pipe 2, pass through the gas mixing chamber 3 to enter the gas inlet 4, and then enter the lower reaction cavity of the fluidized bed 5.

[0044] In a specific embodiment, the heating temperature range of the first heating element 10 is 800-900°C, the heating temperature range of the second heating element 9 is 750-1000°C, and the heating temperature range of the third heating element 11 is 600-800°C.

[0045] like Figure 2 As shown, Figure 2 This is a schematic diagram of the atomizer in the apparatus for preparing pre-lithiated silicon suboxide powder proposed in this invention. Figure 2 In the diagram, 16 represents the inner atomizing element, and 17 represents the atomizer housing. In a specific embodiment, both the first atomizer 7 and the second atomizer 6 are composed of the inner atomizing element 16 and the atomizer housing 17.

[0046] Example 2

[0047] A method for preparing pre-lithiated silicon suboxide powder, using the apparatus described in Example 1, includes the following steps:

[0048] S1. The first heating element 10, the second heating element 9 and the third heating element 11 of the starting device are fully heated to make the temperature in the heating chamber 800℃, the temperature in the upper reaction chamber 750℃ and the temperature in the lower reaction chamber 600℃. Argon gas is continuously introduced into the first gas inlet pipe 1 at a flow rate of 200ml / min, so that the argon gas enters the inner cavity of the fluidized bed 5 and maintains the inert atmosphere in the inner cavity of the fluidized bed 5.

[0049] S2. The organosilicon source solution is continuously atomized through the second atomizer 6 at a flow rate of 150 m / s and enters the lower reaction chamber of the fluidized bed 5 for 1 hour, forming an organosilicon source solution atomization zone in the lower reaction chamber of the fluidized bed 5. The pre-lithiation solution is continuously atomized through the first atomizer 7 at a flow rate of 150 m / s and enters the upper reaction chamber of the fluidized bed 5 for 1 hour, forming a pre-lithiation solution atomization zone in the upper reaction chamber of the fluidized bed 5. Silane gas is continuously introduced into the second air inlet pipe 2 at a flow rate of 200 ml / min for 1 hour. Pre-lithiated silicon suboxide powder is collected at the discharge port 14.

[0050] The organosilicon source solution is composed of tetraethyl orthosilicate and diethyl ether in a molar ratio of 1:1; the pre-lithiation solution is composed of lithium powder, dimethylnaphthalene and dimethyl ether, wherein the molar ratio of lithium powder to dimethylnaphthalene is 0.5:1 and the molar ratio of dimethylnaphthalene to dimethyl ether is 1:1.

[0051] The obtained pre-lithiated silicon suboxide powder and lithium metal were used to assemble a half-cell for electrochemical performance testing. The test rate was 0.1C (initial) + 0.5C (cycle), and the charge / discharge voltage was 0.005–0.8V. The discharge specific capacity of the negative electrode reached 1252 mAh / g, with an initial efficiency of 82.3%, and after 20 cycles, it still retained 86.2% of its capacity.

[0052] Example 3

[0053] A method for preparing pre-lithiated silicon monoxide powder, which is prepared by using the device described in Example 1, comprising the following steps:

[0054] S1, fully heat the first heating element 10, the second heating element 9 and the third heating element 11 of the device, so that the temperature in the heating cavity is 840℃, the temperature in the upper reaction cavity is 780℃, and the temperature in the lower reaction cavity is 650℃, continuously introduce argon into the first gas inlet pipe 1 at a flow rate of 300ml / min, so that the argon enters the inner cavity of the fluidized bed 5, and maintain the inert atmosphere in the inner cavity of the fluidized bed 5;

[0055] S2, continuously atomize the organosilicon source solution into the lower reaction cavity 1.2h of the fluidized bed 5 at a flow rate of 180m / s through the second atomizer 6, form an atomization area of the organosilicon source solution in the lower reaction cavity of the fluidized bed 5, continuously atomize the pre-lithium solution into the upper reaction cavity 1.2h of the fluidized bed 5 at a flow rate of 180m / s through the first atomizer 7, form an atomization area of the pre-lithium solution in the upper reaction cavity of the fluidized bed 5, continuously introduce silane gas into the second gas inlet pipe 2 at a flow rate of 400ml / min for 1h, and collect the pre-lithiated silicon monoxide powder at the discharge port 14.

[0056] The organosilicon source solution is composed of tetraethyl orthosilicate and diethyl ether at a molar ratio of 1:3; the pre-lithium solution is composed of lithium sheet, 1-methylnaphthalene and dimethyl ether, wherein the molar ratio of lithium sheet to 1-methylnaphthalene is 1:1, and the molar ratio of dimethylnaphthalene to dimethyl ether is 1:3.

[0057] The obtained pre-lithiated silicon monoxide powder and metal lithium are used to form a half-cell for electrochemical performance test, the test rate is 0.1C (first time) + 0.5C (cycle), and the charge and discharge voltage is 0.005-0.8V. The discharge specific capacity of the negative electrode sheet can reach 1150mAh / g, the first efficiency is 86.6%, and after 20 cycles, the capacity can still be maintained at 88.1%.

[0058] Example 4

[0059] A method for preparing pre-lithiated silicon monoxide powder, which is prepared by using the device described in Example 1, comprising the following steps:

[0060] S1, fully heat the first heating element 10, the second heating element 9 and the third heating element 11 of the device, so that the temperature in the heating cavity is 840℃, the temperature in the upper reaction cavity is 850℃, and the temperature in the lower reaction cavity is 750℃, continuously introduce argon into the first gas inlet pipe 1 at a flow rate of 400ml / min, so that the argon enters the inner cavity of the fluidized bed 5, and maintain the inert atmosphere in the inner cavity of the fluidized bed 5;

[0061] S2, continuously atomize the organosilicon source solution into the lower reaction chamber 1 of the fluidized bed 5 through the second atomizer 6 at a flow rate of 250 m / s for 1.5 h, form an atomized zone of the organosilicon source solution in the lower reaction chamber 5, continuously atomize the pre-lithium solution into the upper reaction chamber 1 of the fluidized bed 5 through the first atomizer 7 at a flow rate of 180 m / s for 1.2 h, form an atomized zone of the pre-lithium solution in the upper reaction chamber 5, continuously introduce the silane gas into the second gas inlet pipe 2 at a flow rate of 600 ml / min for 1.2 h, and collect the pre-lithiated silicon monoxide powder at the discharge port 14.

[0062] The organosilicon source solution is composed of tetra-n-butyl orthosilicate and diethyl ether at a molar ratio of 1:5; the pre-lithium solution is composed of lithium powder, 1,7-dimethylnaphthalene and diphenyl ether, wherein the molar ratio of lithium powder to 1,7-dimethylnaphthalene is 1:1, and the molar ratio of 1,7-dimethylnaphthalene to diphenyl ether is 1:5.

[0063] The obtained pre-lithiated silicon monoxide powder and metal lithium are combined to form a half-cell for electrochemical performance testing, the test rate is 0.1C (first time) + 0.5C (circulation), and the charge and discharge voltage is 0.005-0.8 V. The discharge specific capacity of the negative electrode sheet can reach 1150 mAh / g, the first efficiency is 90.6%, and after 20 cycles, the capacity can still be maintained at 87.1%.

[0064] Example 5

[0065] A method for preparing a pre-lithiated silicon monoxide powder, which is prepared by using the device described in Example 1, and the method comprises the following steps:

[0066] S1, start the first heating member 10, the second heating member 9 and the third heating member 11 of the device to fully heat, so that the temperature in the heating chamber is 840℃, the temperature in the upper reaction chamber is 900℃, and the temperature in the lower reaction chamber is 750℃, continuously introduce argon into the first gas inlet pipe 1 at a flow rate of 600 ml / min, so that the argon enters the inner cavity of the fluidized bed 5 and maintains the inert atmosphere in the inner cavity of the fluidized bed 5;

[0067] S2, continuously atomize the organosilicon source solution into the lower reaction chamber 1 of the fluidized bed 5 through the second atomizer 6 at a flow rate of 270 m / s for 1.5 h, form an atomized zone of the organosilicon source solution in the lower reaction chamber 5, continuously atomize the pre-lithium solution into the upper reaction chamber 1 of the fluidized bed 5 through the first atomizer 7 at a flow rate of 220 m / s for 1.2 h, form an atomized zone of the pre-lithium solution in the upper reaction chamber 5, continuously introduce the silane gas into the second gas inlet pipe 2 at a flow rate of 700 ml / min for 1.2 h, and collect the pre-lithiated silicon monoxide powder at the discharge port 14.

[0068] The organic silicon source solution is composed of n-butyl silicate and diethyl ether with a molar ratio of 1:8; the pre-lithium solution is composed of lithium powder, 2,3-dimethylnaphthalene and diphenyl ether, wherein the molar ratio of lithium powder to 1-methylnaphthalene is 1:0.5, and the molar ratio of 2,3-dimethylnaphthalene to diphenyl ether is 1:5.

[0069] The obtained pre-lithiated silicon monoxide powder and metal lithium are combined to form a half battery for electrochemical performance testing, the test rate is 0.1C (first) + 0.5C (cycle), and the charge and discharge voltage is 0.005-0.8V. The discharge specific capacity of the negative electrode sheet can reach 1230mAh / g, the first efficiency is 91.6%, and after 20 cycles, the capacity can still be maintained at 88.1%.

[0070] Example 6

[0071] A method for preparing pre-lithiated silicon monoxide powder, which is prepared by using the device described in Example 1, and the method comprises the following steps:

[0072] S1, the first heating part 10, the second heating part 9 and the third heating part 11 of the device are fully heated, the temperature in the heating cavity is 900℃, the temperature in the upper reaction cavity is 1000℃, and the temperature in the lower reaction cavity is 800℃, argon gas is continuously introduced into the first gas inlet pipe 1 at a flow rate of 800ml / min, so that the argon gas enters the inner cavity of the fluidized bed 5, and the inert atmosphere in the inner cavity of the fluidized bed 5 is maintained;

[0073] S2, the organic silicon source solution is continuously atomized into the lower reaction cavity 2h of the fluidized bed 5 at a flow rate of 300m / s through the second atomizer 6, forming an organic silicon source solution atomization zone in the lower reaction cavity of the fluidized bed 5, the pre-lithium solution is continuously atomized into the upper reaction cavity 2h of the fluidized bed 5 at a flow rate of 300m / s through the first atomizer 7, forming a pre-lithium solution atomization zone in the upper reaction cavity of the fluidized bed 5, and the silane gas is continuously introduced into the second gas inlet pipe 2 at a flow rate of 800ml / min for 2h, and the pre-lithiated silicon monoxide powder is collected at the discharge port 14.

[0074] The organic silicon source solution is composed of n-butyl silicate and diethyl ether with a molar ratio of 1:10; the pre-lithium solution is composed of lithium sheet, dimethylnaphthalene and dimethyl ether, wherein the molar ratio of lithium sheet to dimethylnaphthalene is 1:0.5, and the molar ratio of 2,3-dimethylnaphthalene to diphenyl ether is 1:10.

[0075] The obtained pre-lithiated silicon monoxide powder and metal lithium are combined to form a half battery for electrochemical performance testing, the test rate is 0.1C (first) + 0.5C (cycle), and the charge and discharge voltage is 0.005-0.8V. The discharge specific capacity of the negative electrode sheet can reach 1150mAh / g, the first efficiency is 89.6%, and after 20 cycles, the capacity can still be maintained at 84.1%.

[0076] Comparative Example 1

[0077] Silicon monoxide with an average particle size of 3 μm and lithium powder were placed in a mass ratio of 88:12 in a vapor deposition furnace, argon was introduced at a flow rate of 200 ml / min, calcined at 900℃ for 3h, to obtain lithium-doped silicon monoxide material.

[0078] The obtained lithium-doped silicon monoxide material and metal lithium were placed in a half-cell for electrochemical performance test, the test rate was 0.1C (first) + 0.5C (cycle), and the charge and discharge voltage was 0.005-0.8V. The discharge specific capacity of the negative electrode sheet can reach 1200mAh / g, the first efficiency is 79.3%, and after 20 cycles, the capacity retention rate is only 56.2%.

[0079] The performance results in the comparative examples and the comparative example show that the technical solution can efficiently utilize silane and an organic silicon source to prepare high first efficiency silicon monoxide material with stable structure and complete pre-lithiation through a specially designed device and a preparation method. The conversion degree of silane gas is controlled by controlling the temperature of different parts of the fluidized bed, a nanoscale core is first formed, is combined with the atomized silicon source, and is formed into stable nanoscale silicon monoxide particles at high temperature. The pre-lithiation solution is uniformly adsorbed on the surface of the particles after the particles rise through the atomized pre-lithiation solution, and the lithium ions rapidly diffuse to be uniformly distributed in the nanoscale silicon monoxide particles at high temperature to complete the pre-lithiation. When the particles reach the top of the fluidized bed, they are completely converted and deposited on the surface of the nanoscale silicon monoxide to complete the secondary granulation to form micron-sized silicon monoxide particles with stable structure. The particles uniformly adsorb the pre-lithiation solution when passing through the pre-lithiation solution atomization area in the descending process, and the lithium ion diffusion process is completed by the temperature inside the fluidized bed to complete the pre-lithiation of the secondary particles. Therefore, the preparation and pre-lithiation of the silicon monoxide material can be completed simultaneously by using the method and device, the prepared particles have stable structure and uniform distribution of lithium ions inside, and do not need secondary processing as the negative electrode material of a lithium ion battery. The material has the characteristics of high first efficiency and long cycle.

[0080] The above only describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can make equivalent substitutions or changes to the technical solutions and the inventive concept of the present application within the technical scope disclosed by the present application, which should be covered by the protection scope of the present application.

Claims

1. An apparatus for preparing a pre-lithiated silicon monoxide powder, characterized by, The device comprises a fluidized bed (5), a first atomizer (7) and a second atomizer (6); The inner cavity of the fluidized bed (5) is sequentially provided with a first heat insulation plate (8) and a second heat insulation plate (15) from top to bottom, the first heat insulation plate (8) and the second heat insulation plate (15) divide the inner cavity of the fluidized bed (5) into a heating cavity, an upper reaction cavity and a lower reaction cavity from top to bottom, and the heating cavity, the upper reaction cavity and the lower reaction cavity are respectively provided with a first heating member (10), a second heating member (9) and a third heating member (11); the heating temperature range of the first heating member (10) is 800-900℃, the heating temperature range of the second heating member (9) is 750-1000℃, and the heating temperature range of the third heating member (11) is 600-800℃; The first heat insulation plate (8) is provided with an air outlet (12) penetrating through the heating cavity and communicating with the outside; the air outlet (12) is provided with a guide plate (13); the guide plate (13) is used for guiding the pre-lithiated silicon monoxide powder to the discharge port (14); the second heat insulation plate (15) is provided with a through hole communicating the upper reaction cavity and the lower reaction cavity; The first atomizer (7) and the second atomizer (6) are both mounted on the fluidized bed (5) and respectively communicate with the upper reaction cavity and the lower reaction cavity; The bottom of the fluidized bed (5) is provided with an air inlet (4) and a discharge port (14) which communicate with the lower reaction cavity.

2. The device for preparing pre-lithiated silicon monoxide powder according to claim 1, characterized in that, The second heating member (9) and the first atomizer (7) are oppositely arranged, and the third heating member (11) and the second atomizer (6) are oppositely arranged.

3. The apparatus for preparing pre-lithiated silicon monoxide powder according to claim 1, wherein The air inlet (4) is connected with a gas mixing chamber (3) through a pipeline, and the bottom of the gas mixing chamber (3) respectively communicates with a first air inlet pipe (1) and a second air inlet pipe (2).

4. A method for preparing a pre-lithiated silicon monoxide powder using the apparatus according to any one of claims 1 to 3, characterized in that, The device comprises the following steps: S1, start the first heating member (10), the second heating member (9) and the third heating member (11) of the device to fully heat, and continuously introduce inert gas through the air inlet (4) to maintain an inert atmosphere in the inner cavity of the fluidized bed (5); S2, continuously atomize the organosilicon source solution into the lower reaction cavity of the fluidized bed (5) through the second atomizer (6) to form an organosilicon source solution atomization zone, continuously atomize the pre-lithium solution into the upper reaction cavity of the fluidized bed (5) through the first atomizer (7) to form a pre-lithium solution atomization zone, and then continuously introduce silane gas through the air inlet (4) to collect the pre-lithiated silicon monoxide powder at the discharge port (14).

5. The method of preparing prelithiated silicon monoxide powder according to claim 4, characterized in that, The organosilicon source solution comprises an organosilicon source and a solvent, the molar ratio of the organosilicon source to the solvent is 1:(1-10); the organosilicon source is at least one of tetraethyl orthosilicate and tetra-n-butyl orthosilicate; and the solvent is diethyl ether.

6. The method of preparing prelithiated silicon monoxide powder according to claim 4, characterized by, The pre-lithium solution comprises a lithium source, a complexing agent and a solvent, the molar ratio of the lithium source to the complexing agent is (0.5-2):1, the molar ratio of the complexing agent to the solvent is 1:(1-10); the lithium source is at least one of lithium powder and lithium sheet; the complexing agent is at least one of dimethyl naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, 1,7-dimethylnaphthalene and 2,3-dimethylnaphthalene; and the solvent is at least one of dimethyl ether, diphenyl ether and tetrahydrofuran.

7. The method of preparing prelithiated silicon monoxide powder according to claim 4, characterized by, The silane gas is at least one of monosilane and disilane.

8. The method of preparing prelithiated silicon monoxide powder according to claim 4, wherein The flow rate of the inert gas is 200-800 ml / min, the flow rate of the silane gas is 200-800 ml / min, the flow rate of the first atomizer (7) is 150-300 m / s, and the flow rate of the second atomizer (6) is 150-300 m / s.

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