Negative electrode material, preparation method and application thereof, and manufacturing equipment of negative electrode material

Abstract

The invention provides a negative electrode material, a preparation method and application thereof, and manufacturing equipment of the negative electrode material. According to the present invention, the negative electrode material has characteristics of high capacity, low volume expansion rate during the charge-discharge cycle process so as to provide good cycle performance, and low powder resistivity so as to easily achieve the rate performance of the final battery.

Description

Technical Field

[0001] This application relates to the technical field of batteries, and particularly to a negative electrode material, a preparation method thereof, an application thereof, and a manufacturing device for the negative electrode material. Background Art

[0002] Silicon negative electrode materials have gradually attracted attention due to their high specific capacity. However, when silicon is used alone as a negative electrode material, its expansion rate during charge and discharge cycles is extremely large. In order to suppress its expansion, generally, silicon is deposited in porous carbon, or carbon materials are used to coat silicon particles. Moreover, the silicon in the silicon-carbon composite materials in related technologies is generally in a crystalline state, and the expansion rate of silicon crystals during charge and discharge cycles is significantly higher than that of amorphous silicon. Therefore, ultimately, the expansion rate of the silicon-carbon composite material during charge and discharge cycles is still relatively large, which is not conducive to the cycle performance of the battery.

[0003] In addition, the process of depositing silicon in porous carbon is relatively difficult, which involves various dangerous gases such as silane, acetylene, and hydrogen, and there are many potential safety hazards, making it difficult to achieve large-scale industrial applications. When using carbon materials to coat nano-silicon, during the coating process, nano-silicon particles are extremely prone to agglomeration, resulting in poor structural uniformity of the finally obtained silicon-carbon composite material, which is still not conducive to the exertion of electrochemical performance. Summary of the Invention

[0004] In view of this, the embodiments of this application provide a negative electrode material, a preparation method thereof, an application thereof, and a manufacturing device for the negative electrode material. This negative electrode material has a high capacity, and its volume expansion rate during charge and discharge cycles is small, thus having good cycle performance. Moreover, the powder resistivity of this negative electrode material is low, which is conducive to the rate performance of the final battery.

[0005] The first aspect of the embodiments of this application provides a negative electrode material, including silicon-carbon particles. Each of the silicon-carbon particles includes a carbon material and a plurality of primary amorphous silicon nanoparticles dispersed inside the carbon material.

[0006] Silicon is embedded inside the carbon material in the form of primary nanoparticles, which can reduce the difference in particle size uniformity of silicon particles caused by agglomeration of silicon nanoparticles, and reduce the risk of fragmentation due to uneven internal stress distribution of silicon-carbon particles during charge and discharge cycles, thereby improving its cycle performance. At the same time, the volume change rate of amorphous silicon during charge and discharge cycles is much smaller than that of crystalline silicon, so the cycle performance of silicon-carbon particles can be further improved. Moreover, compared with the transition-state silicon particles from crystalline to amorphous, amorphous silicon can reduce the powder resistivity of silicon-carbon particles, so that the final battery can still exhibit good rate performance at high rates.

[0007] The second aspect of the embodiments of this application provides a manufacturing device for a negative electrode material, including:

[0008] Feeding bin, plasma generating device and enlarged-section reaction device; the feeding bin is communicated with one end of the plasma generating device, the enlarged-section reaction device is connected to the other end of the plasma generating device, and a plurality of atomizing nozzles are arranged on the side wall of the enlarged-section reaction device close to one end of the plasma generating device;

[0009] The feeding bin is used to convey a silicon source to the plasma generating device, the plasma generating device is used to heat the silicon source to turn it into a gaseous or liquid state and convey it to the enlarged-section reaction device, and the atomizing nozzles are used to spray a carbon source so that the carbon source contacts and reacts with the gaseous or liquid-phase silicon source in the enlarged reaction device to form silicon-carbon particles and obtain a negative electrode material.

[0010] A third aspect of the embodiments of the present application provides a method for preparing a negative electrode material, including:

[0011] Feeding a first raw material into the cavity of the plasma generating device, the plasma generating device heating the first raw material and turning the first raw material into a liquid or gaseous state; wherein, the first raw material includes a silicon source;

[0012] Making the liquid or gaseous first raw material contact and react with the liquid carbon source to form silicon-carbon particles and obtain a negative electrode material; each of the silicon-carbon particles includes a carbon material and a plurality of amorphous silicon primary nanoparticles dispersed inside the carbon material.

[0013] The above preparation method has strong process reliability, high production efficiency and is easy to realize large-scale industrial production.

[0014] A third aspect of the embodiments of the present application provides a negative electrode sheet, including the negative electrode material provided in the first aspect of the embodiments of the present application, or a negative electrode material prepared by using the manufacturing equipment for the negative electrode material provided in the second aspect of the embodiments of the present application. Due to the negative electrode material provided in the embodiments of the present application, the negative electrode sheet can be used to provide a secondary battery with better cycle performance.

[0015] A fifth aspect of the embodiments of the present application provides a secondary battery, including a positive electrode sheet, the negative electrode sheet provided in the embodiments of the present application, and an electrolyte located between the positive electrode sheet and the negative electrode sheet. Due to the negative electrode sheet provided in the embodiments of the present application, the secondary battery has better cycle stability.

[0016] A sixth aspect of the embodiments of the present application provides an electrical device, including the secondary battery provided in the embodiments of the present application. Due to being powered by the secondary battery provided in the embodiments of the present application, the electrical device has better market competitiveness. Description of the Drawings

[0017] Figure 1Schematic cross-sectional structure diagram of the silicon-carbon particles of the negative electrode material provided by an embodiment of the present application;

[0018] Figure 2 Schematic structure diagram of the manufacturing equipment of the negative electrode material provided by an embodiment of the present application;

[0019] Figure 3 Schematic diagram of preparing the negative electrode material by using the manufacturing equipment provided by an embodiment of the present application according to an embodiment of the present application.

[0020] Explanation of the reference numerals in the drawings: 100 - silicon-carbon particles; 10 - carbon material; 20 - amorphous silicon primary nanoparticles; 1 - feed bin; 2 - plasma generating device; 3 - enlarged section reaction device; 4 - atomizing nozzle; 5 - exhaust pipe; 6 - product receiving tank. Detailed implementation manners

[0021] An embodiment of the present application provides a negative electrode material. Please refer to Figure 1 , which includes silicon-carbon particles 100. The silicon-carbon particles 100 include a carbon material 10 and a plurality of amorphous silicon primary nanoparticles 20 dispersed inside the carbon material 10.

[0022] In the embodiment of the present application, silicon is embedded inside the carbon material in the form of primary nanoparticles, which can reduce the risk that the non-uniformity of the particle size of silicon particles caused by the agglomeration of silicon nanoparticles leads to uneven internal stress distribution in the silicon-carbon particles during the charge and discharge cycle and thus easy fragmentation, thereby improving the cycle performance of the silicon-carbon particles. At the same time, the volume change rate of amorphous silicon during the charge and discharge cycle is much smaller than that of crystalline silicon, so the cycle performance of the silicon-carbon particles can be further improved. Also based on the intrinsic electrochemical performance of silicon, the silicon-carbon particles can also have a high capacity, which is beneficial to improving the energy density of the final battery.

[0023] Therefore, the negative electrode material provided by the embodiment of the present application can have both a high capacity and excellent cycle performance and rate performance.

[0024] In the embodiment of the present application, the amorphous silicon includes a silicon material without characteristic derivative peaks of silicon crystals in the X-Ray Diffraction (XRD) test.

[0025] In some embodiments of the present application, D90 of the silicon-carbon particles ≤ 20 μm. In some specific embodiments, D90 of the silicon-carbon particles is between 5 μm and 15 μm. In this way, firstly, it is beneficial to control the length of the deintercalation / insertion path of the active ions within a suitable range, which is beneficial to the rate performance of the battery; secondly, it is also beneficial to control the specific surface area of the silicon-carbon particles within a suitable range, thereby facilitating the guarantee of the cycle performance of the battery. In addition, considering the application of the anode material, it is often necessary to mix it with a binder and a solvent to prepare an anode slurry. Controlling D90 of the silicon-carbon particles within the above range is also beneficial to improving the uniformity of the final anode slurry, thereby facilitating the obtaining of a high-quality anode sheet and also facilitating the performance of the battery. In the embodiments of the present application, D90 of the silicon-carbon particles can be measured by a laser particle size analyzer. Specifically, D90 of the silicon-carbon particles can be, but is not limited to, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm.

[0026] In some embodiments of the present application, D90 of the amorphous silicon primary nanoparticles ≤ 100 nm. Specifically, D90 of the amorphous silicon primary particles can be, but is not limited to, 5 nm, 8 nm, 10 nm, 12 nm, 15 nm, 20 nm, 25 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm.

[0027] In the embodiments of the present application, the agglomeration phenomenon of the primary particles of the silicon-carbon particles is less or almost non-existent. Therefore, in some embodiments of the present application, Dspn of the silicon-carbon particles ≤ 1.5, where Dspn = (D90 - D10) / D50. In this way, it is beneficial to the application of the anode material in subsequent processes. For example, an anode material with good particle size uniformity is more likely to produce a uniform anode slurry, thereby easily obtaining a uniform anode material layer, which can improve the electrochemical performance of the final battery. In the embodiments of the present application, D90, D10, and D50 can all be measured by a laser particle size analyzer. Specifically, Dspn of the silicon-carbon particles can be, but is not limited to, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5.

[0028] In some embodiments of the present application, the surface of the amorphous silicon primary nanoparticles has an amorphous SiC layer. SiC has covalent bonds and is not easily broken, and can withstand the stress generated by the volume change of the internal amorphous silicon during charge and discharge, effectively avoiding the situation where the amorphous silicon primary nanoparticles rupture and the contact risk with the electrolyte increases, thereby facilitating the improvement of the cycle performance of the battery; in addition, the amorphous SiC layer can also provide a part of the capacity. In some specific embodiments, the thickness of the amorphous SiC layer ≤ 20 nm. Controlling the thickness of the amorphous SiC layer within the above range can avoid the capacity decline caused by excessive occupation of silicon carbide, and can effectively avoid the situation where the resistance increases due to the excessive thickness of the amorphous SiC layer and even the lithium ions cannot penetrate, resulting in the ineffectiveness of the active site. Specifically, the thickness of the amorphous SiC layer can be but is not limited to 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, etc.

[0029] In some embodiments of the present application, the specific surface area of the negative electrode material ≤ 10 m 2 / g. In this way, it can be reflected from the side that the structure of the carbon material is relatively dense. When the negative electrode material is applied to the battery, the risk of contact between the amorphous silicon primary particles embedded in the carbon material and the electrolyte can be significantly reduced, thereby reducing the side reaction between silicon and the electrolyte, and further improving the cycle performance of the battery. Specifically, the specific surface area of the negative electrode material can be but is not limited to 1 m 2 / g, 2 m 2 / g, 3 m 2 / g, 4 m 2 / g, 5 m 2 / g, 6 m 2 / g, 7 m 2 / g, 8 m 2 / g, 9 m 2 / g, 10 m 2 / g, etc. In the embodiments of the present application, the specific surface area of the negative electrode material is the BET specific surface area of the negative electrode material measured by gas adsorption and desorption. During the test, the degassing temperature is 300 °C and the degassing time is 6 h.

[0030] In some embodiments of the present application, the amorphous silicon primary nanoparticles are further doped with element M, and the element M includes but is not limited to at least one of N, B, P, Ge, and Sn. Thus, the electrochemical performance of the anode material can be further optimized. In some specific embodiments, the mass content of element M in the amorphous silicon primary nanoparticles is ≤1%. Specifically, the mass content of element M in the amorphous silicon primary nanoparticles can be but is not limited to 0.1%, 0.2%, 0.5%, 0.8%, 1.0%, etc. In some other embodiments, the amorphous silicon primary nanoparticles are doped with N element, and the mass content of N element in the amorphous silicon primary nanoparticles can be greater than 1%.

[0031] In some embodiments of the present application, the mass content of silicon element in the silicon-carbon particles is 5%-70%. Those of ordinary skill in the art can select according to actual needs.

[0032] In some embodiments of the present application, the anode material further includes other anode active materials; the other anode active materials include but are not limited to at least one of graphite, graphene, carbon nanotubes, and carbon black. That is, in some embodiments of the present application, the anode material is a composite material of at least one of graphite, graphene, carbon nanotubes, and carbon black and silicon-carbon particles. In the embodiments of the present application, the mass ratio of the silicon-carbon particles in the anode material is not limited, and those skilled in the art can select according to actual production needs.

[0033] In the embodiments of the present application, the particle size of the other anode active materials is not limited either. The anode material with uniform particle size can be obtained by mixing, and the electrochemical performance of the two can be optimized as much as possible. In some specific embodiments, even if other anode active materials are contained, the Dspn of the anode material is ≤1.5, and D90≤20μm.

[0034] Correspondingly, please refer to Figure 2 , the embodiments of the present application also provide a manufacturing device for the anode material, which can be used to prepare the aforementioned anode material provided by the embodiments of the present application. Specifically, the manufacturing device for the anode material includes:

[0035] A feed bin 1, a plasma generating device 2, and an expanding section reaction device 3; the feed bin 1 is communicated with one end of the plasma generating device 2, the expanding section reaction device 3 is connected to the other end of the plasma generating device 2, and a plurality of atomizing nozzles 4 are provided on the side wall of the expanding section reaction device 3 close to one end of the plasma generating device 2; it can be understood that, in order to provide sufficient reaction space, in some embodiments of the present application, the expanding section reaction device is generally in a cavity shape, including a first end and a second end arranged oppositely, the first end is connected to the plasma generating device, and the second end is used to output the product formed in the expanding section reaction device.

[0036] The feeding bin 1 is used to convey a silicon source to the plasma generating device 2, and the plasma generating device 2 is used to heat the silicon source to transform it into a gaseous or liquid state and convey it to the expansion section reaction device 3; the atomizing nozzle 4 is used to spray a carbon source, so that the carbon source contacts and reacts with the gaseous or liquid-phase silicon source in the expansion reaction device 3 to form silicon carbide particles and obtain the anode material.

[0037] For the manufacturing equipment provided by the embodiments of the present application, one end of the plasma generating device is connected to the feeding bin, and the other end is connected to the expansion section reaction device. The feeding bin conveys the silicon source to the plasma generating device. The silicon source instantaneously melts or vaporizes in the plasma generating device to generate a liquid or gaseous silicon source, which is heated to form silicon gas or liquid silicon and is sprayed into the expansion section reaction device. At this time, the atomizing nozzle on the side wall of the expansion section reaction device can spray the carbon source towards the gaseous / liquid silicon source, and the carbon source directly contacts the liquid or gaseous silicon. It can also be understood that when silicon is in a liquid or gaseous state, the ambient temperature is relatively high, which can cause the carbon source to crack and coat on the surface of the silicon source. At the same time, under the monodisperse state, carbon coating forms primary silicon nanoparticles and carbon coated on the surface of the silicon particles. In addition, carbon coating is carried out in the state where silicon is in a liquid or gaseous state, which can inhibit the crystallization of silicon, so that amorphous silicon primary nanoparticles can be obtained.

[0038] The above-mentioned manufacturing equipment is easy to obtain and has high production efficiency, and is suitable for large-scale industrial production.

[0039] In some embodiments of the present application, the atomizing nozzle is arranged near the end of the plasma generating device, so that the carbon source contacts and reacts with the gaseous or liquid silicon source at the end of the plasma generating device. The temperature at the end of the plasma generating device can reach 3000K, and the high temperature is conducive to the cracking and coating of the carbon source. Those skilled in the art can determine the distance between the atomizing nozzle and the end of the plasma generating device according to actual production needs.

[0040] In some embodiments of the present application, a plurality of atomizing nozzles are annularly arranged on the side wall of the expansion section reaction device. In some specific embodiments, multiple rows of atomizing nozzles are annularly arranged on the side wall of the expansion section reaction device. In other specific embodiments, a single row of atomizing nozzles is annularly arranged on the side wall of the expansion section reaction device. Those skilled in the art can determine the number of atomizing nozzles and the distance between two adjacent atomizing nozzles according to actual production needs.

[0041] In some embodiments of the present application, the atomizing nozzle is used to spray a liquid carbon source.

[0042] In some cases, based on production needs, it is also necessary to dope the amorphous silicon primary nanoparticles. At this time, the feeding bin can be used to convey the silicon source and the doping element source to the plasma generating device at the same time. The plasma generating device can also transform the doping element source into a gaseous or liquid state and uniformly disperse the doping element source in the carbon source.

[0043] In some specific embodiments, please refer to Figure 3 , an exhaust duct 5 is further provided on the side wall of the end of the expansion section reaction device away from the plasma reaction device (i.e., the aforementioned second end), and the exhaust duct 5 can be used to discharge the tail gas generated during the reaction.

[0044] In some embodiments of the present application, the plasma generating device is a thermal plasma generating device, preferably an inductively coupled plasma generating device.

[0045] In some specific embodiments, the manufacturing equipment further includes a product receiving tank 6, and the product receiving tank 6 is arranged at the end of the expansion section reaction device away from the plasma generating device (i.e., the aforementioned second end) for collecting the negative electrode material formed in the expansion section reaction device.

[0046] The embodiment of the present application also provides a method for preparing a negative electrode material, including:

[0047] S01. Feeding the first raw material into the cavity of the plasma generating device, and the plasma generating device heats the first raw material and converts the first raw material into a liquid state or a gaseous state; wherein, the first raw material includes a silicon source;

[0048] S02. Making the liquid or gaseous first raw material contact and react with the liquid carbon source to form silicon-carbon particles and obtain the negative electrode material; each of the silicon-carbon particles includes a carbon material and a plurality of amorphous silicon primary nanoparticles embedded inside the carbon material.

[0049] The plasma generating device can instantaneously melt or vaporize the first raw material (including the silicon source) to generate a liquid or gaseous silicon source. The liquid carbon source has a large heat enthalpy value and latent heat of vaporization, and can rapidly cool the gaseous or liquid silicon source to inhibit its crystallization when forming silicon nanoparticles. Also, because the ambient temperature must be relatively high when the silicon source can be maintained in a liquid or gaseous state, while the silicon source is rapidly cooled, the carbon source can be cracked and coated on the surface of the silicon source to achieve monodisperse coating of the silicon source. Thus, amorphous silicon primary nanoparticles and the carbon material coated on their surfaces can be obtained. Also, because of the merging between adjacent carbon materials or the continuous growth of the carbon material during the carbon cracking and coating process, finally, the obtained silicon-carbon particles include a carbon material and a plurality of amorphous silicon primary nanoparticles embedded inside the carbon material.

[0050] In addition, by using the above preparation method, during the process of product collection, the primary particles of the prepared silicon-carbon particles are not likely to agglomerate. Therefore, the particle size distribution of the finally obtained negative electrode material is uniform. Using the above preparation method is beneficial to the full collection of the final negative electrode material, and can also avoid problems such as material waste and equipment blockage caused by the entry of nanoscale powders (such as silicon nanoparticles) formed in the related art into the backend of the manufacturing equipment.

[0051] The above preparation method has strong process reliability, high production efficiency, and is easy to realize large-scale industrial production.

[0052] In some embodiments of the present application, the preparation method provided by the embodiments of the present application is realized by using the aforementioned manufacturing equipment provided by the embodiments of the present application.

[0053] In some embodiments of the present application, the carbon source is a liquid carbon source spray. In this way, it is more conducive to the uniform coating of carbon and is conducive to improving the uniformity of the structure of the anode material.

[0054] In some embodiments of the present application, the liquid or gaseous first raw material is brought into contact and reacted with the liquid carbon source at the end of the plasma generating device. The ambient temperature at the end of the plasma generating device is generally above 3000K. The high temperature is more conducive to the rapid cracking and coating of the carbon source, thereby facilitating further reduction of the particle size of the amorphous silicon primary nanoparticles.

[0055] In some embodiments of the present application, the carbon source is a liquid carbon source with a boiling point ≥ 100°C. Specifically, the boiling point of the carbon source can be, but is not limited to, 100°C, 150°C, 200°C, 300°C, 400°C, 500°C, 600°C, etc. The high-boiling liquid carbon source has a relatively large heat enthalpy value and latent heat of vaporization, which is more conducive to rapid cooling of the silicon source, thereby better inhibiting the crystallization of silicon.

[0056] In some embodiments of the present application, the carbon source is selected from organic compounds having oxygen-containing functional groups. Specifically, the oxygen-containing functional groups include, but are not limited to, ether oxygen atoms, hydroxyl groups, carboxyl groups, ester groups, carbonyl groups, aldehyde groups, etc., as long as they have oxygen atoms. Specifically, the organic compounds having oxygen-containing functional groups include, but are not limited to, polyols, polyaldehydes, polyacids, etc.

[0057] In some embodiments of the present application, the carbon source is selected from organic compounds having at least two branched chains or multiple substituents. For example, polysubstituted aromatic hydrocarbon organic compounds. Specifically, it includes, but is not limited to, p-xylene, terephthalic acid, etc. In this way, it is more conducive to the cracking to produce hard carbon, thereby facilitating the improvement of the rate performance of the final anode material.

[0058] In some specific embodiments of the present application, the carbon source is a carbon source with a boiling point ≥ 100°C that has oxygen-containing functional groups and at least two branched chains or substituents. In this way, the carbon source can have both a relatively high heat enthalpy value and latent heat of vaporization, and is easy to crack to produce hard carbon. Moreover, it is also conducive to achieving a more ideal carbon coating effect. For example, it can make the carbon material in the silicon-carbon particles have a higher density, avoid the generation of some pores, thereby reducing the specific surface area of the silicon-carbon particles (for example, the specific surface area is less than or equal to 10m 2 / g), reducing the risk of amorphous silicon primary nanoparticles in the silicon-carbon particles directly contacting the electrolyte, thereby facilitating the acquisition of a negative electrode material with excellent cycle performance and rate performance.

[0059] In some other embodiments of the present application, the carbon source is selected from organic amines with a boiling point ≥ 100°C. At this time, the carbon source can not only be cracked and the carbon material can be coated on the surface of the amorphous silicon primary particles, but the N atoms in the organic amine can also be doped into the amorphous silicon primary particles. At this time, the N element can be doped into the amorphous silicon primary nanoparticles without the need to add a doping element source. In some specific embodiments, the organic amine is preferably an organic amine containing a primary amino group, and there is no large group occupying the N atom around it, which is conducive to forming a weak bond with silicon first, thereby facilitating the doping of the N atom; more preferably, the organic amine is an organic amine containing only one primary amino group, and the unit amine is more volatile, which is conducive to subsequent drying and separation.

[0060] Understandably, it is necessary to use a carrier gas to transport the first raw material to the plasma generating device. In some embodiments of the present application, the carrier gas can be a gas commonly used in the field, including but not limited to at least one of hydrogen and argon. In some specific embodiments, the carrier gas is a mixture of hydrogen and argon. Further, increasing the content of hydrogen in the carrier gas is conducive to increasing the production capacity of the negative electrode material.

[0061] In some embodiments of the present application, while the carbon source is cracked and coated, it can also react with silicon to generate amorphous silicon carbide, so that in the obtained negative electrode material, the surface of the amorphous silicon nano primary particles has an amorphous SiC layer.

[0062] In some embodiments of the present application, the silicon source includes but is not limited to silicon. In some specific embodiments, the silicon source is silicon powder, which has low cost, high safety, and does not generate by-products. Of course, the present application embodiment does not limit the material of the silicon source. If a technician in the field wants to use a silicon source such as silane, chlorosilane, etc. and use the manufacturing equipment and preparation method provided in the present application embodiment to prepare silicon-carbon particles, it is also feasible.

[0063] In some embodiments of the present application, the first raw material also includes a doping element source, wherein the doping element includes but is not limited to at least one of B, P, Ge, and Sn. In this way, the above elements can be doped into the amorphous silicon primary nanoparticles to improve the electrochemical performance of the silicon-carbon particles (i.e., the negative electrode material). Specifically, the boron element source includes but is not limited to boron powder. The tin element source includes but is not limited to metal tin powder. The germanium element source includes but is not limited to metal germanium powder. The phosphorus element source includes but is not limited to red phosphorus.

[0064] In the embodiments of the present application, the feeding speed of the first raw material is not limited, and those skilled in the art can select it according to actual production needs. Exemplarily, the feeding speed of the first raw material to the plasma generating device can be 0.01 g / s - 1000 g / s.

[0065] In the embodiments of the present application, the power of the plasma generating device is not limited, and those skilled in the art can select it according to actual production needs. Exemplarily, the power of the plasma generating device can be 0.1 KW - 1000 KW.

[0066] In the embodiments of the present application, the feeding speed of the carbon source is not limited, and those skilled in the art can adjust it according to the feeding speed of the first raw material and the content of silicon element in the expected anode material.

[0067] In some embodiments of the present application, the anode material is prepared by using the aforementioned manufacturing equipment provided in the embodiments of the present application. Please refer to Figure 3 , the silicon source enters the plasma generating device 2 through the feeding bin 1, and at the same time, the discharge gas also enters the plasma generating device 2. The silicon source is converted into a gaseous or liquid state and is transported to the expansion section reaction device 3. At this time, the liquid carbon source is sent into the expansion section reaction device 3 through a plurality of atomizing nozzles 4 to contact and react with the gaseous or liquid silicon source to generate silicon-carbon particles, which are collected into the product receiving tank 6.

[0068] In some embodiments of the present application, it further includes drying the product collected in step S02 to obtain the anode material. The drying process well-known to those skilled in the art can be adopted. For example, the product is placed in a dryer and dried at 200 °C under a pressure lower than 20 kPa for 2 h.

[0069] In some embodiments of the present application, it further includes mixing the prepared silicon-carbon particles with other anode active materials to obtain the anode material. In some embodiments of the present application, the above-mentioned other anode active materials include but are not limited to at least one of graphite, graphene, carbon nanotubes, and carbon black. In the embodiments of the present application, the above mixing can be carried out by using any process and equipment well-known to those skilled in the art, and the present application does not limit this.

[0070] The embodiments of the present application also provide an anode plate, including the anode material provided in the embodiments of the present application, or the anode material prepared by using the manufacturing equipment for the anode material provided in the embodiments of the present application. Due to the anode material provided in the embodiments of the present application, this anode plate can be used to provide a secondary battery with good cycle performance, and it can also exhibit excellent cycle performance under the working conditions of high-rate charge and discharge. In addition, based on the inherent properties of the silicon-carbon particles, this secondary battery can also achieve a high energy density.

[0071] In some embodiments of the present application, the above-mentioned negative electrode plate includes a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector. The negative electrode active material layer includes the aforementioned silicon-carbon negative electrode material, a binder, and an optional conductive agent. Among them, the above-mentioned negative electrode current collector is any negative electrode current collector well-known in the art suitable for the negative electrode of a battery, and the binder and the conductive agent can also be selected from materials well-known to those skilled in the art.

[0072] The embodiment of the present application also provides a secondary battery, including a positive electrode plate and the negative electrode plate provided in the embodiment of the present application, and an electrolyte located between the above-mentioned positive electrode plate and the negative electrode plate. Due to the negative electrode plate provided in the embodiment of the present application, the secondary battery has good cycle stability and a high energy density.

[0073] In the embodiment of the present application, the above-mentioned secondary battery can be any one of a liquid battery, a solid battery, or a semi-solid battery. In some specific embodiments, the above-mentioned secondary battery includes a positive electrode plate, a negative electrode plate, and a separator and an electrolyte located between the above-mentioned positive electrode plate and the negative electrode plate.

[0074] In the embodiment of the present application, the above-mentioned secondary battery can be an alkali metal ion battery such as a lithium-ion battery or a sodium-ion battery.

[0075] The embodiment of the present application also provides an electrical device, including the secondary battery provided in the embodiment of the present application. Due to being powered by the secondary battery provided in the embodiment of the present application, the electrical device has good market competitiveness.

[0076] The technical solution of the present application will be further described in detail in the following multiple embodiments.

[0077] Example 1

[0078] An inductively coupled plasma generating device with a power of 40 kW is used. The carrier gas is a mixture of 50% hydrogen and 50% argon, the pressure is atmospheric pressure, and the flow rate is 15 L / min. Industrial silicon powder with a purity of 99.5% and a mesh size of 60 is carried into the reaction zone of the plasma generating device at a feeding speed of 5 g / s and passes through the entire plasma generating device. Eight atomizing nozzles are symmetrically arranged in sequence on the side wall of the enlarged section reaction device at the end of the plasma generating device. Each nozzle sprays atomized p-xylene at a flow rate of 3 g / s. After continuous operation for one hour, the collected product is placed in a dryer, heated to 200 °C, and evacuated to a pressure lower than 20 kPa, and dried for two hours to obtain about 25.2 kg of the product.

[0079] Example 2

[0080] An inductively coupled plasma generating device with a power of 40 kW is used. The carrier gas is a mixture of 80% hydrogen and 20% argon, at atmospheric pressure, with a flow rate of 20 L / min. Industrial silicon powder with a purity of 99.5% and a mesh size of 60 is carried into the reaction zone of the plasma generating device at a feeding rate of 8 g / s and passes through the entire plasma generating device. Eight atomizing nozzles are symmetrically arranged in sequence on the side wall of the enlarged section reaction device at the end of the plasma generating device, and each nozzle sprays atomized terephthalic acid at a flow rate of 6 g / s. After continuous operation for one hour, the collected product is placed in a dryer, heated to 300 °C, and evacuated to a pressure lower than 20 kPa, and dried for two hours to obtain about 37.4 kg of product.

[0081] Example 3

[0082] An inductively coupled plasma generating device with a power of 40 kW is used. The carrier gas is a mixture of 80% hydrogen and 20% argon, at atmospheric pressure, with a flow rate of 20 L / min. Industrial silicon powder with a purity of 99.5% and a mesh size of 60 is carried into the reaction zone of the plasma generating device at a feeding rate of 7 g / s and passes through the entire plasma generating device. Eight atomizing nozzles are symmetrically arranged in sequence on the side wall of the enlarged section reaction device at the end of the plasma generating device, and each nozzle sprays atomized glycerol at a flow rate of 5 g / s. After continuous operation for one hour, the collected product is placed in a dryer, heated to 300 °C, and evacuated to a pressure lower than 20 kPa, and dried for two hours to obtain about 34.1 kg of product.

[0083] Example 4

[0084] An inductively coupled plasma generating device with a power of 40 kW is used. The carrier gas is a mixture of 60% hydrogen and 40% argon, at atmospheric pressure, with a flow rate of 10 L / min. Industrial silicon powder with a purity of 99.5% and a mesh size of 60 is carried into the reaction zone of the plasma generating device at a feeding rate of 4 g / s and passes through the entire plasma generating device. Eight atomizing nozzles are symmetrically arranged in sequence on the side wall of the enlarged section reaction device at the end of the plasma generating device, and each nozzle sprays atomized ethylene glycol at a flow rate of 4 g / s. After continuous operation for one hour, the collected product is placed in a dryer, heated to 200 °C, and evacuated to a pressure lower than 20 kPa, and dried for two hours to obtain about 18.7 kg of product.

[0085] Example 5

[0086] An inductively coupled plasma generating device with a power of 40 kW is used. The carrier gas is a mixture of 60% hydrogen and 40% argon at atmospheric pressure with a flow rate of 10 L / min. Industrial silicon powder with a purity of 99.5% and 60 mesh and red phosphorus with a purity of 97% and 60 mesh are mixed at a mass ratio of 99:1, and then carried into the reaction zone of the plasma generating device at a feeding speed of 4 g / s and passed through the entire plasma generating device. Eight atomizing nozzles are symmetrically arranged in sequence on the side wall of the enlarged section reaction device at the end of the plasma generating device. Each nozzle sprays atomized ethylene glycol at a flow rate of 4 g / s. After continuous operation for one hour, the collected product is placed in a dryer, heated to 200 °C and evacuated to a pressure lower than 20 kPa, and dried for two hours to obtain about 18.5 kg of product.

[0087] Example 6

[0088] An inductively coupled plasma generating device with a power of 40 kW is used. The carrier gas is a mixture of 50% hydrogen and 50% argon at atmospheric pressure with a flow rate of 15 L / min. Industrial silicon powder with a purity of 99.5% and 60 mesh is carried into the reaction zone of the plasma generating device at a feeding speed of 5 g / s and passed through the entire plasma generating device. Eight atomizing nozzles are symmetrically arranged in sequence on the side wall of the enlarged section reaction device at the end of the plasma generating device. Each nozzle sprays atomized aniline at a flow rate of 3 g / s. After continuous operation for one hour, the collected product is placed in a dryer, heated to 200 °C and evacuated to a pressure lower than 20 kPa, and dried for two hours to obtain about 27.3 kg of product.

[0089] Example 7

[0090] An inductively coupled plasma generating device with a power of 40 kW is used. The carrier gas is a mixture of 80% hydrogen and 20% argon at atmospheric pressure with a flow rate of 20 L / min. Industrial silicon powder with a purity of 99.5% and 60 mesh is carried into the reaction zone of the plasma generating device at a feeding speed of 7 g / s and passed through the entire plasma generating device. Eight atomizing nozzles are symmetrically arranged in sequence on the side wall of the enlarged section reaction device at the end of the plasma generating device. Each nozzle sprays atomized hexamethylenediamine at a flow rate of 5 g / s. After continuous operation for one hour, the collected product is placed in a dryer, heated to 300 °C and evacuated to a pressure lower than 20 kPa, and dried for two hours to obtain about 37.5 kg of product.

[0091] To highlight the beneficial effects of the embodiments of the present application, the following comparative examples are set.

[0092] Comparative Example 1

[0093] This comparative example is the most advanced silicon-carbon anode preparation process by silane chemical vapor deposition (CVD) method in the current lithium battery industry. The specific preparation steps are as follows:

[0094] (1) Take 1 kg of the porous carbon support, use silane as the silicon source, with a flow rate of 3 L / min, deposit for 4 h in the silicon deposition unit 11 under normal pressure at 440 °C to obtain composite material particles;

[0095] (2) Use acetylene as the carbon source, with a flow rate of 1 L / min, and perform carbon coating on the above composite material particles in the carbon coating unit under normal pressure at 600 °C for 1 h to obtain 1.9 kg of the silicon-carbon negative electrode material.

[0096] Product parameter characterization: (1) Use a laser particle size analyzer to measure Dspn and D90 of the negative electrode materials of each example and comparative example, and the results are summarized in Table 1.

[0097] (2) Use N2 adsorption and desorption to measure the BET specific surface area of the negative electrode material. During the test, the degassing temperature is 300 °C and the degassing time is 6 h, and the results are summarized in Table 1.

[0098] Table 1

[0099] Case Dspn D90 (μm) of the negative electrode material <![CDATA[Specific surface area (m 2 / g)]]> Example 1 1.1 12 9.6 Example 2 1.8 22 7.8 Example 3 1.5 18 10.5 Example 4 1.6 19 19.1 Example 5 1.4 18 16.4 Example 6 1.2 21 14.7 Example 7 1.7 24 18.3 Comparative Example 1 3.1 26 3.2

[0100] Performance test:

[0101] (1) Powder resistivity test:

[0102] Use a resistivity tester for testing. Place 1 g of the negative electrode materials of each example and comparative example between the electrodes of the resistivity tester, and use an electronic press to keep the pressure constant at the test pressure of 30 Mpa for 15 s - 25 s to obtain sheet samples. Calculate the powder resistivity δ of the material according to the formula δ=(S×R) / h, with the unit of Ω·cm. Among them, h is the height of the sheet sample, with the unit of cm; R is the resistance, with the unit of Ω; S is the area of the sheet sample, with the unit of cm 2 .

[0103] (2) Use a coin cell to test the specific capacity and the first Coulomb efficiency:

[0104] 1): Preparation of coin cells: Weigh the anode materials, conductive additive carbon black, and binder (sodium carboxymethyl cellulose and styrene-butadiene rubber with a mass ratio of 1:1) of each example and comparative example according to the mass ratio of 94:2:4, and use a pulper to prepare the slurry. Coat the slurry on a coater at 30 mm / s with a 250 μm blade and bake at 80 °C for 2 h to obtain the anode. Use a Celgard 2400 type polypropylene separator, select a lithium metal sheet as the cathode, and use a LiPF6-based electrolyte (a 1 mol / L LiPF6 solution with ethylene carbonate (EC) / dimethyl carbonate (DMC) as a 1:1 (volume ratio) mixture as the solvent), and assemble it with the above-prepared anode into a CR2032 coin cell in a glove box.

[0105] Perform constant current charge-discharge tests on the prepared CR2032 coin cells using a charge-discharge instrument. The discharge cut-off voltage is 0.005 V, and the charge cut-off voltage is 2 V to measure the specific capacity. The first week of charge-discharge tests is carried out at a current density of 1C / 10C to test the initial Coulomb efficiency, and the results are summarized in Table 2.

[0106] (3) Use a full-electric test method to test the cycling performance of each anode material

[0107] 1) Preparation of full cells: Take the silicon-carbon particles prepared in each example and comparative example and configure them into a composite material with a specific capacity of 450 mAg / h with graphite. Weigh the composite material, conductive additive carbon black, and binder (sodium carboxymethyl cellulose and styrene-butadiene rubber with a mass ratio of 1:1) according to the mass ratio of 94:2:4, prepare the slurry, coat the slurry on the current collector, and obtain the anode electrode sheet for standby. Stir and mix the cathode active material LiCoO2, conductive carbon black, and binder polyvinylidene fluoride (PVDF) evenly in an N-methylpyrrolidone solvent system according to the weight ratio of 96.7:1.7:1.6, coat it on an Al foil, dry it, and cold press it to obtain the cathode electrode sheet for standby. Use a polyethylene porous polymer film as the separator, stack the above cathode electrode sheet, separator, and anode electrode sheet in sequence, make the separator play a role in isolation between the cathode electrode sheet and the anode electrode sheet, and wind it to obtain a bare battery core. Place the bare battery core in the outer package, inject the electrolyte, prepare a 404865 model battery core (the cathode surface density is 17.9 g / cm 2 , and the anode surface density is 7.0 g / cm 2 , use the electrolyte of Shinzo LBC421B10) and encapsulate it, and obtain a full battery core through processes such as formation, degassing, and trimming.

[0108] Perform constant current charge-discharge tests on the prepared full battery cores using a charge-discharge instrument. The discharge cut-off voltage is 2.75 V, and the charge cut-off voltage is 4.2 V. The charge-discharge tests are all carried out at a current density of 1C to test the capacity retention rate of the full battery for 300 cycles, and the results are summarized in Table 2.

[0109] Table 2

[0110]

[0111] Furthermore, the production costs and production capacities of the silicon-carbon particles in the embodiments and comparative examples of the present application are summarized in Table 3.

[0112] Table 3

[0113] Raw material cost (10,000 yuan / ton) Power cost (10,000 yuan / ton) Annual production capacity of a single device (ton / year) Examples of the present application 4～6 2～3 >500, continuous process Comparative Example 1 25～30 1～1.5 <100, batch process

[0114] Currently, the silicon-carbon particles prepared by the silane chemical vapor deposition process are the process route of the silicon-carbon particle products with the best recognized performance in the industry. Combining the data in Table 2 and Table 3, it can be found that when the specific capacity and initial efficiency of the silicon-carbon particles in the embodiments of the present application are comparable to those of Comparative Example 1, the powder resistivity of the silicon-carbon particles in the embodiments of the present application is lower, thereby improving the rate performance of the anode material, and the cycle performance is also significantly improved compared with Comparative Example 1. Furthermore, the technical solution of the embodiments of the present application can produce silicon-carbon particles without using silane as a raw material, with good safety performance, significant cost reduction, and the monomer production capacity scale being significantly dozens of times higher than the existing chemical vapor deposition process.

[0115] The above is the exemplary embodiment of the present application. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present application, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present application.

Claims

1. A negative electrode material, characterized in that, It includes silicon-carbon particles, and each of the silicon-carbon particles includes a carbon material and a plurality of amorphous silicon primary nanoparticles dispersed inside the carbon material.

2. The negative electrode material according to claim 1, wherein The Dspn of the silicon-carbon particles ≤ 1.5, where Dspn = (D90 - D10) / D50.

3. The negative electrode material according to claim 1 or 2, characterized in that, The surface of the amorphous silicon primary nanoparticles has an amorphous SiC layer; the thickness of the amorphous SiC layer ≤ 20 nm.

4. The negative electrode material according to any one of claims 1-3, characterized in that, The negative electrode material further satisfies at least one of the following (1)-(7): (1) The specific surface area of the silicon carbide particles ≤ 10 m 2 / g; (2) The mass content of silicon element in the silicon-carbon particles is 5% - 70%; (3) The amorphous silicon primary nanoparticles are further doped with element M, and the element M includes at least one of N, B, P, Ge, and Sn; preferably, the mass content of the element M in the silicon-carbon particles ≤ 1%; (4) The amorphous silicon primary nanoparticles are doped with N; preferably, the mass content of N in the silicon-carbon particles > 1%; (5) The D90 of the silicon-carbon particles ≤ 20 μm; preferably, the D90 of the silicon-carbon particles is 5 μm - 15 μm; (6) The D90 of the amorphous primary nanoparticles ≤ 100 nm; (7) The negative electrode material further includes at least one of graphite, graphene, carbon nanotubes, and carbon black; preferably, the Dspn of the negative electrode material ≤ 1.5, D90 ≤ 20 μm.

5. A manufacturing device for a negative electrode material, characterized in that, It includes: A feed bin, a plasma generating device, and an enlarged-section reaction device; the feed bin is communicated with one end of the plasma generating device, the enlarged-section reaction device is connected to the other end of the plasma generating device, and a plurality of atomizing nozzles are provided on the side wall of the enlarged-section reaction device near one end of the plasma generating device; The feed bin is used to convey a silicon source to the plasma generating device, the plasma generating device is used to heat the silicon source to turn it into a gaseous or liquid state and convey it to the enlarged-section reaction device, and the atomizing nozzles are used to spray a carbon source so that the carbon source contacts and reacts with the gaseous or liquid-phase silicon source in the enlarged reaction device to form silicon-carbon particles and obtain a negative electrode material.

6. The manufacturing apparatus according to claim 5, wherein, It further includes at least one of the following features (1)-(4): (1) The atomizing nozzles are arranged near the end of the plasma generating device; (2) A plurality of the atomizing nozzles are arranged in a ring on the side wall of the enlarged-section reaction device; (3) An exhaust pipe is further provided on the side wall of the enlarged-section reaction device far from the plasma reaction device; (4) The manufacturing equipment further includes a product receiving tank, and the product receiving tank is arranged at the end of the enlarged-section reaction device far from the plasma generating device.

7. A method for preparing a negative electrode material, characterized in that, It includes: Sending a first raw material into the cavity of the plasma generating device, and the plasma generating device heats the first raw material and turns the first raw material into a liquid or gaseous state; wherein, the first raw material includes a silicon source; Making the liquid or gaseous first raw material contact and react with the liquid carbon source to form silicon-carbon particles and obtain a negative electrode material; each of the silicon-carbon particles includes a carbon material and a plurality of amorphous silicon primary nanoparticles dispersed inside the carbon material.

8. The preparation method according to claim 7, wherein The boiling point of the carbon source ≥ 100 °C.

9. The preparation method according to claim 7 or 8, characterized in that, The carbon source is selected from organic matter having oxygen-containing functional groups; Preferably, the organic matter containing oxygen functional groups includes at least one of ether oxygen atoms, hydroxyl groups, carboxyl groups, ester groups, carbonyl groups and aldehyde groups; More preferably, the organic substance containing oxygen functional groups includes at least one of polyols, polyaldehydes, and polyacids; And / or, the carbon source is selected from organic amines.

10. The preparation method according to any one of claims 7-9, characterized in that, The carbon source is selected from organic matter having at least two branches or multiple substituents; Preferably, the carbon source is selected from aromatic hydrocarbons having multiple substituents; More preferably, the carbon source is selected from at least one of p-xylene and terephthalic acid; and / or, the carbon source is selected from organic amines having primary amino groups; Preferably, the organic amine is an organic amine containing only one primary amino group.

11. The preparation method according to any one of claims 7-10, characterized in that, The preparation method further comprises at least one of (1) to (8): (1) the liquid or gaseous first raw material contacts and reacts with the liquid carbon source at the end of the plasma generating device; (2) using a carrier gas to transport the first raw material to the plasma device, wherein the carrier gas includes at least one of hydrogen and argon; (3) The silicon source includes silicon; preferably, the silicon source is silicon powder; (4) The first raw material further includes a doping element source, wherein the doping element includes at least one of B, P, Ge and Sn; preferably, the doping element source includes at least one of red phosphorus, boron powder, metal tin powder and metal germanium powder; (5) The feeding rate of the first raw material to the plasma generating device is 0.01 g / s-1000 g / s; (6) The power of the plasma generator is 0.1KW-1000KW; (7) further comprising drying a product obtained by contacting and reacting the liquid or gaseous first raw material with a liquid carbon source; (8) Before obtaining the negative electrode material, the method further includes mixing the silicon-carbon particles with at least one of graphite, graphene, carbon nanotubes and carbon black.

12. A negative electrode plate, characterized in that, The negative electrode plate includes the negative electrode material as described in any one of claims 1-4, or includes the negative electrode material produced by the negative electrode material manufacturing equipment as described in claim 5 or 6, or includes the negative electrode material produced by the preparation method as described in any one of claims 7-11.

13. A secondary battery, characterized in that, Comprising the negative electrode sheet as described in claim 12.

14. An electrical device, characterized in that, Comprising the secondary battery as claimed in claim 13.

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