Method for stabilizing carbon-coated silicon monoxide particles and preparation method of electrode slurry

Abstract

The invention provides a method for stabilizing carbon-coated silicon monoxide particles, an iCVD device, a preparation method of electrode slurry and a battery, the carbon-coated silicon monoxide particles are placed in an iCVD chamber, and protective gas is introduced to remove air in the iCVD chamber; the iCVD chamber is rotated, so that the carbon-coated silicon monoxide particles can be uniformly coated with the polymer in the subsequent steps, the chamber and the lamp filament are respectively heated in the process of rotating the iCVD chamber, and the GMA monomer and the TBPO initiator are vaporized and introduced into the iCVD chamber, so that the TBPO initiator is influenced by the heated lamp filament to internally initiate the GMA monomer to generate polymerization reaction, and the carbon-coated silicon monoxide particles are obtained. The PGMA polymer coating layer is uniformly and flexibly formed on the surface of the carbon-coated silicon monoxide particle, so that the shape-preserving coating of the carbon-coated silicon monoxide particle is realized, the problem that the carbon-coated layer is broken and falls off is avoided, and the cycle performance of the carbon-coated silicon monoxide particle is further improved.

Description

Technical Field

[0001] The present invention relates to the field of lithium batteries, and particularly to a method for stably encapsulating carbon-coated silicon monoxide particles, an iCVD device, a preparation method of electrode paste, and a battery. Background Art

[0002] Silicon monoxide (SiO x ) has attracted much attention as the anode material of lithium-ion batteries due to its high theoretical specific capacity. However, silicon monoxide reacts with lithium during charge and discharge, resulting in a large volume change of silicon monoxide particles, which will cause the active material to fall off from the conductive network, and problems such as cracks and pulverization of silicon monoxide particles, seriously affecting the cycle performance of the battery.

[0003] To alleviate this problem, the prior art often coats a carbon layer on the surface of silicon monoxide particles to enhance the conductivity of the surface of silicon monoxide particles and buffer their volume change. However, the carbon-coated layer is a brittle material and is prone to cracking and falling off when the volume of silicon monoxide particles expands, unable to effectively protect the material structure, resulting in poor cycle performance of the material.

[0004] Therefore, how to perform conformal coating on carbon-coated silicon monoxide particles, avoid the cracking and falling off of the carbon-coated layer, and improve the cycle performance of carbon-coated silicon monoxide particles has become a technical problem that the industry urgently needs to solve at present. Summary of the Invention

[0005] The present invention provides a method for stably encapsulating carbon-coated silicon monoxide particles, an iCVD device, a preparation method of electrode paste, and a battery, which solves the technical problem of how to perform conformal coating on carbon-coated silicon monoxide particles, avoid the cracking and falling off of the carbon-coated layer, and improve the cycle performance of carbon-coated silicon monoxide particles.

[0006] According to the first aspect of the present invention, an embodiment of the present invention provides a method for stably encapsulating carbon-coated silicon monoxide particles, including:

[0007] Putting the carbon-coated silicon monoxide particles into an iCVD chamber, the iCVD chamber including a cavity and a filament disposed in the cavity;

[0008] Introducing a protective gas into the iCVD chamber to exclude the air in the iCVD chamber;

[0009] After putting the carbon-coated silicon monoxide particles into the iCVD chamber, rotating the iCVD chamber;

[0010] During the rotation of the iCVD chamber, heating the cavity;

[0011] During the rotation of the iCVD chamber, heating the filament;

[0012] The vaporized GMA monomer and the TBPO initiator are introduced into the iCVD chamber, such that the heated filament affects the TBPO initiator to initiate the polymerization reaction of the GMA monomer, so as to form a PGMA polymer coating layer on the surface of the carbon-coated silicon monoxide particles.

[0013] Optionally, the method for heating the chamber includes heating the temperature of the chamber to a range between 50°C and 80°C.

[0014] Optionally, the method for heating the chamber includes heating the chamber by an oil bath heating method.

[0015] Optionally, the method for heating the filament includes heating the temperature of the filament to a range between 140°C and 300°C.

[0016] Optionally, the protective gas is an inert gas.

[0017] Optionally, the protective gas is nitrogen, and the method for introducing the protective gas includes introducing the nitrogen into the iCVD chamber at a flow rate between 3 sccm and 5 sccm.

[0018] Optionally, the method for vaporizing the GMA monomer and the TBPO initiator and introducing them into the iCVD chamber includes:

[0019] introducing the vaporized GMA monomer into the iCVD chamber at a flow rate between 0.3 sccm and 0.7 sccm;

[0020] introducing the vaporized TBPO initiator into the iCVD chamber at a flow rate between 0.8 sccm and 1.2 sccm.

[0021] Optionally, the thickness of the PGMA polymer coating layer is between 21 nm and 36 nm.

[0022] Optionally, the reaction chamber pressure of the iCVD chamber is between 600 mTorr and 800 mTorr.

[0023] Optionally, the reaction time for introducing the vaporized GMA monomer and the TBPO initiator into the iCVD chamber, such that the heated filament affects the TBPO initiator to initiate the polymerization reaction of the GMA monomer, is between 5 minutes and 20 minutes.

[0024] According to a second aspect of the present invention, an embodiment of the present invention provides an iCVD device for implementing the method for stably coating carbon-coated silicon monoxide particles as described in any one of the first aspects of the present invention, including:

[0025] an iCVD chamber including a chamber body and a filament disposed in the chamber body, the filament being electrically conductive;

[0026] A rotating motor, coupled to the iCVD chamber, for controlling the rotation of the iCVD chamber;

[0027] A heating module for heating the chamber;

[0028] A protective gas introduction module for introducing a protective gas into the iCVD chamber;

[0029] A GMA monomer introduction module for introducing the vaporized GMA monomer into the iCVD chamber;

[0030] A TBPO initiator introduction module for introducing the vaporized TBPO initiator into the iCVD chamber;

[0031] A flow rate control module, respectively coupled to the control ends of the protective gas introduction module, the GMA monomer introduction module, and the TBPO initiator introduction module, for respectively controlling the flow rates of the gases in the protective gas introduction module, the GMA monomer introduction module, and the TBPO initiator introduction module.

[0032] Optionally, the heating module includes:

[0033] An oil bath heating pan for heating the temperature of the chamber to between 50°C and 80°C.

[0034] Optionally, the GMA monomer introduction module includes a GMA monomer container, a first valve, and a first conduit;

[0035] The GMA monomer container is sequentially coupled to the iCVD chamber through the first valve and the first conduit, and the GMA monomer container is used for vaporizing the GMA monomer and introducing the vaporized GMA monomer into the iCVD chamber through the first conduit;

[0036] The flow rate control module is further coupled to the first valve and is further configured to:

[0037] Control the opening amount of the first valve to control the flow rate of the vaporized GMA monomer introduced into the iCVD chamber.

[0038] Optionally, the flow rate control module is further configured to: control the opening amount of the first valve to control the air pressure in the GMA monomer container so that the GMA monomer vaporizes.

[0039] Optionally, the TBPO initiator introduction module may also include a TBPO initiator container, a second valve, and a second conduit;

[0040] The TBPO initiator container is sequentially coupled to the iCVD chamber through the second valve and the second conduit. The TBPO initiator container is configured to vaporize the TBPO initiator and introduce the vaporized TBPO initiator into the iCVD chamber through the second conduit;

[0041] The flow rate control module is further coupled to the second valve and is further configured to:

[0042] Control the opening amount of the second valve to control the flow rate of the vaporized TBPO initiator introduced into the iCVD chamber.

[0043] Optionally, the flow rate control module is further configured to: control the opening amount of the second valve to control the air pressure in the TBPO initiator container so that the TBPO initiator is vaporized.

[0044] According to a third aspect of the present invention, an embodiment of the present invention provides a method for preparing an electrode paste, including:

[0045] Mixing a PAA binder, a modifying material, a conductive agent, and deionized water to form the electrode paste;

[0046] Wherein, the modifying material is prepared by using the method for stabilizing carbon-coated silicon monoxide particles according to any one of the first aspects of the present invention, and the modifying material is the carbon-coated silicon monoxide particles with a PGMA polymer coating layer formed on the surface.

[0047] Optionally, the conductive agent is an acetylene black conductive agent.

[0048] According to a fourth aspect of the present invention, an embodiment of the present invention provides a battery, including an electrode paste, and the electrode paste is prepared by using the method for preparing an electrode paste according to any one of the third aspects of the present invention.

[0049] Compared with the prior art, the technical solutions of the embodiments of the present invention have the following beneficial effects:

[0050] In the method for stably encapsulating carbon-coated silicon monoxide particles and the iCVD device according to the technical solution of the present invention, the carbon-coated silicon monoxide particles are placed in the iCVD chamber, and a protective gas is introduced to remove the air in the iCVD chamber; the iCVD chamber is rotated so that the carbon-coated silicon monoxide particles can be uniformly coated with a polymer in subsequent steps. During the rotation of the iCVD chamber, the chamber and the filament are heated respectively, and the GMA monomer and the TBPO initiator are vaporized and introduced into the iCVD chamber, so that the TBPO initiator is affected by the heated filament to initiate the polymerization reaction of the GMA monomer inside, so as to form a uniform and flexible PGMA polymer coating layer on the surface of the carbon-coated silicon monoxide particles, realizing the conformal coating of the carbon-coated silicon monoxide particles, avoiding the problem of cracking and shedding of the carbon coating layer, and further improving the cycle performance of the carbon-coated silicon monoxide particles.

[0051] In the method for preparing the electrode paste and the battery according to the technical solution of the present invention, the method includes: mixing a PAA binder, the material, a conductive agent, and deionized water to form an electrode paste, wherein the modified material is carbon-coated silicon monoxide particles with a PGMA polymer coating layer formed on the surface. The present invention utilizes the ring-opening reaction of the PGMA polymer coating layer and the PAA binder to avoid the carbon-coated silicon monoxide particles from detaching from the conductive network and improve the cycle performance of the carbon-coated silicon monoxide particles.

[0052] Furthermore, the conductive agent is an acetylene black conductive agent. Since a PGMA polymer coating layer is formed on the surface of the carbon-coated silicon monoxide particles in the present invention, the acetylene black conductive agent is more likely to adhere to the surface of the modified carbon-coated silicon monoxide particles, further improving the cycle performance of the carbon-coated silicon monoxide particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0054] Figure 1 is a schematic flow chart of a method for stably encapsulating carbon-coated silicon monoxide particles provided by an embodiment of the present invention;

[0055] Figure 2 is a TEM image of carbon-coated silicon monoxide particles with a PGMA polymer coating layer formed on the surface provided by an embodiment of the present invention;

[0056] Figure 3 is a schematic diagram of the working principle of the PGMA polymer coating layer provided by an embodiment of the present invention;

[0057] Figure 4 It is a comparative graph of the battery cycle performance provided by an embodiment of the present invention;

[0058] Figure 5 It is a schematic structural diagram of an iCVD device provided by an embodiment of the present invention;

[0059] Figure 6 It is a schematic structural diagram of an iCVD device provided by another embodiment of the present invention;

[0060] Figure 7 It is a schematic diagram of the process of an open-loop reaction provided by an embodiment of the present invention;

[0061] Figure 8 It is a TEM comparative graph of the adhesion situation with a conductive agent provided by an embodiment of the present invention. Detailed Embodiments

[0062] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0063] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order different from those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0064] Next, the technical solutions of the present invention will be described in detail with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments.

[0065] As described in the background art, it is difficult for the prior art to perform conformal coating on carbon-coated silicon monoxide particles, avoid the rupture and shedding of the carbon coating layer, and improve the cycle performance of the carbon-coated silicon monoxide particles.

[0066] Specifically, silicon monoxide (SiO x)As a negative electrode material for lithium-ion batteries, it has a high theoretical specific capacity, but it will experience a volume expansion of about 100% during the charge and discharge process. This significant volume change easily causes the silicon suboxide particles to detach from the conductive network, reducing the battery performance.

[0067] Moreover, due to the low intrinsic conductivity of silicon suboxide, it is usually necessary to coat a carbon layer to improve its conductivity. However, the connection between the carbon-coated silicon suboxide particles themselves and the conductive network is very poor. Moreover, the carbon layer may crack or peel off in the face of the volume expansion of silicon suboxide, further weakening the stability of the conductive network.

[0068] In addition, traditional polymer coating methods (such as solution methods) have problems of uneven coating thickness and difficulty in achieving nanoscale thickness control. An overly thick polymer layer will reduce the energy density of the material and affect the battery performance.

[0069] Therefore, how to perform conformal coating on the carbon-coated silicon suboxide particles, avoid the cracking and peeling off of the carbon coating layer, and improve the cycling performance of the carbon-coated silicon suboxide particles has become a technical problem that the industry urgently needs to solve at present.

[0070] To solve the above problems, the embodiments of the present invention provide a method for stabilizing carbon-coated silicon suboxide particles. The carbon-coated silicon suboxide particles are placed in an iCVD chamber, and a protective gas is introduced to exclude the air in the iCVD chamber; the iCVD chamber is rotated so that the carbon-coated silicon suboxide particles can be uniformly coated with a polymer in subsequent steps. During the rotation of the iCVD chamber, the chamber body and the filament are heated respectively, and the GMA monomer and the TBPO initiator are vaporized and introduced into the iCVD chamber, so that the TBPO initiator is affected by the heated filament to initiate the polymerization reaction of the GMA monomer, forming a uniform and flexible PGMA polymer coating layer on the surface of the carbon-coated silicon suboxide particles, realizing the conformal coating of the carbon-coated silicon suboxide particles, avoiding the problem of cracking and peeling off of the carbon coating layer, and further improving the cycling performance of the carbon-coated silicon suboxide particles.

[0071] To make the above objects, features, and beneficial effects of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention will be given with reference to the accompanying drawings.

[0072] In a specific embodiment, please refer to Figure 1 , the method for stabilizing carbon-coated silicon suboxide particles according to the embodiments of the present invention includes:

[0073] S11: Place the carbon-coated silicon suboxide particles in an iCVD chamber, and the iCVD chamber includes a chamber body and a filament placed in the chamber body.

[0074] The iCVD chamber herein can be understood as a chamber for implementing initiated chemical vapor deposition.

[0075] S12: Introduce a protective gas into the iCVD chamber to expel the air in the iCVD chamber.

[0076] In a specific embodiment, the protective gas is an inert gas.

[0077] As an example, the protective gas can be nitrogen (N2), and the method of introducing the protective gas includes:

[0078] Introduce the nitrogen into the iCVD chamber at a flow rate between 3 sccm (standard cubic centimeters per minute) and 5 sccm (standard cubic centimeters per minute).

[0079] In other embodiments, the protective gas can also be argon (Ar2), etc. The present invention does not limit this, as long as the gas can expel the air in the iCVD chamber and does not affect the reaction of initiated chemical vapor deposition, it is within the protection scope of the present invention.

[0080] S13: After putting the carbon-coated silicon oxycarbide particles into the iCVD chamber, rotate the iCVD chamber.

[0081] Specifically, rotating the iCVD chamber can make the carbon-coated silicon oxycarbide particles evenly distributed in the iCVD chamber, so that the carbon-coated silicon oxycarbide particles can be evenly coated with polymers in subsequent steps.

[0082] S14: During the process of rotating the iCVD chamber, heat the chamber.

[0083] In one embodiment, the method of heating the chamber in step S14 includes: heating the temperature of the chamber to between 50 °C and 80 °C.

[0084] It can be seen that the modification temperature of the present invention is relatively low (i.e., the chamber temperature is between 50 °C and 80 °C), which will not affect the structure of the carbon-coated silicon oxycarbide. This avoids the disproportionation of silicon oxycarbide during the high-temperature modification process, and finally prevents the problem that silicon oxycarbide becomes silicon oxycarbide and silicon.

[0085] To heat the chamber evenly, in a specific embodiment, the method of heating the chamber in step S14 includes: heating the chamber by an oil bath heating method.

[0086] It should be understood that the present invention does not limit the method of heating the chamber, and other media can also be used to indirectly heat the chamber, such as water bath heating, sand bath heating, etc.

[0087] S15: During the process of rotating the iCVD chamber, heat the filament.

[0088] In one embodiment, the method of heating the filament in step S15 includes heating the temperature of the filament to a range between 140 °C and 300 °C.

[0089] This is because temperature is the key for the initiator to initiate the polymerization of the polymer. In the embodiments of the present invention, the reaction can only occur at a temperature above 140 °C. At the same time, the finally formed polymer in the embodiments of the present invention is not resistant to high temperatures. Therefore, the temperature of the filament needs to be lower than 300 °C.

[0090] In actual work, the cavity can be heated first and then the filament. This is because the temperature of the filament is very high and the cavity needs to be preheated to eliminate potential safety hazards.

[0091] S16: Introduce the vaporized GMA monomer and the TBPO initiator into the iCVD chamber, so that the TBPO initiator is affected by the heated filament to initiate the polymerization reaction of the GMA monomer, and a PGMA polymer coating layer is formed on the surface of the carbon-coated silicon oxide particles.

[0092] Among them, GMA can be understood as glycidyl methacrylate;

[0093] TBPO can be understood as tert-butyl peroxy-2-ethylhexanoate;

[0094] PGMA polymer can be understood as polyglycidyl methacrylate.

[0095] In a specific embodiment, the method of vaporizing the GMA monomer and the TBPO initiator and introducing them into the iCVD chamber in step S16 includes:

[0096] Introduce the vaporized GMA monomer into the iCVD chamber at a flow rate between 0.3 sccm and 0.7 sccm;

[0097] Introduce the vaporized TBPO initiator into the iCVD chamber at a flow rate between 0.8 sccm and 1.2 sccm.

[0098] It should be understood that in actual work, the parameters of each iCVD chamber are different. The present invention only needs to ensure that there is no problem of pipe blockage due to too slow flow rate when introducing gas, and no problem of insufficient reaction time and poor coating effect due to too fast flow rate.

[0099] It can be seen that the embodiments of the present invention have completed the conformal coating of the carbon-coated silicon oxide, and the coated PGMA polymer coating layer is soft, uniform, has a consistent thickness, and is a nanoscale coating. The PGMA polymer coating layer can also be regarded as a protective layer that can adapt to the volume change of the carbon-coated silicon oxide.

[0100] Now, the effect of stabilizing carbon-coated silicon monoxide particles provided by the embodiments of the present invention will be described. In the following description, the modified material is the carbon-coated silicon monoxide particles with the PGMA polymer coating layer formed on the surface in the embodiments of the present invention.

[0101] In a specific embodiment, please refer to Figure 2 , Figure 2 which shows the TEM image (electron microscopy image) of the carbon-coated silicon monoxide particles with the PGMA polymer coating layer formed on the surface. Among them, the thickness d1 of the carbon coating layer is 35.5 nm, and the thickness d2 of the PGMA polymer coating layer is between 21 nm and 36 nm.

[0102] It can be seen that the coating layer of the present invention is relatively thin, ensuring the energy density of the material.

[0103] At the same time, the epoxy groups carried by the PGMA polymer can form strong hydrogen bonds with the hydroxyl groups (-OH) on the surface of the silicon monoxide particles when the carbon coating layer is broken by the volume expansion of the silicon monoxide, effectively protecting the silicon monoxide from being exposed in the electrolyte, reducing the growth of the solid electrolyte interface (SEI) on the surface of the silicon monoxide particles, and reducing the capacity attenuation of the silicon monoxide during the cycling process.

[0104] Please refer to Figure 3 , Figure 3 which shows the working principle of the PGMA polymer coating layer. This figure shows the dynamic process of the expansion and contraction of the silicon monoxide during the charge and discharge cycles, and the outer PGMA polymer coating layer adopts a "squeezing - rebounding" method to cope with this change and protect the internal material structure.

[0105] Among them:

[0106] The innermost sphere can be understood as the silicon monoxide matrix (SiO x MP, micron-sized silicon monoxide particles);

[0107] The middle brown shell layer can be understood as the carbon coating layer (carbon shell) for improving the conductivity of the silicon monoxide matrix;

[0108] The outermost green layer can be understood as the PGMA polymer coating layer.

[0109] It can be seen that when the modified material undergoes lithiation, that is, when lithium ions enter the silicon monoxide, the volume of the silicon monoxide matrix particles will expand. At this time, the outer PGMA polymer coating layer will be squeezed;

[0110] During the delithiation of the modified material, that is, when lithium ions are removed from silicon monoxide, the volume of the silicon monoxide matrix particles will shrink. At this time, the outer PGMA polymer coating layer will rebound and closely adhere to the surface of the carbon-coated layer.

[0111] Obviously, the PGMA polymer coating layer can buffer the volume change of the internal material, prevent the carbon layer from cracking or falling off, and enable the material to better adapt to large-scale volume changes during repeated charge and discharge (lithiation / delithiation) processes. This not only protects the carbon-coated layer from being damaged but also reduces the risk of particle separation from the conductive network, thereby improving the battery cycle performance and capacity retention rate.

[0112] Now, in combination with Figure 4 the battery cycle performance of the modified material will be described. Figure 4 A battery cycle performance comparison chart is shown, where:

[0113] The abscissa (X-axis) is the cycle number;

[0114] The ordinate (Y-axis) is the specific capacity (mAh / g);

[0115] SC can be understood as SiO x @C, that is, the specific capacity measured for carbon-coated silicon monoxide at different cycle numbers;

[0116] SCP can be understood as SiO x @C@PGMA, that is, the specific capacity measured for the modified material at different cycle numbers.

[0117] Among them, the current density used in the cycles from 0 to 3 is 70 mA / g, and a higher current density (750 mA / g) is adopted in the cycles from 4 to 200.

[0118] It can be seen that as the cycle number increases, both materials show a capacity decay phenomenon. However, the capacity decline rate of the modified material (SCP) is significantly slower than that of carbon-coated silicon monoxide (SC). And after 200 cycles, the modified material (SCP) still maintains a relatively high specific capacity, while the capacity of carbon-coated silicon monoxide (SC) has decreased significantly.

[0119] Table 1 Battery cycle performance comparison table

[0120]

[0121] Please continue to refer to Table 1. Table 1 corresponds to Figure 4Battery cycle performance comparison table. Among them, ICE is the initial Coulomb efficiency, which represents the ratio between the lithium ions released from the battery anode material (lithium deintercalation capacity) and the lithium ions initially embedded in the material (lithium intercalation capacity) during the first charge-discharge cycle.

[0122] Obviously, the capacity of the unmodified material (SC) decays rapidly as the number of cycles increases, indicating that it is more prone to problems such as structural rupture, particle shedding, or decreased conductivity during repeated charge and discharge processes.

[0123] However, the modified material (SCP) can still maintain a high capacity after long-term cycling, indicating that during the charge-discharge process, its structure is more stable, its connection with the conductive network is stronger, and the expansion stress is better buffered.

[0124] It can be seen that the modified material (SCP) is significantly superior to the unmodified material (SC) in terms of cycle stability and capacity retention rate.

[0125] In addition, please refer to Figure 5 , the present invention also provides an iCVD device for implementing the method for stabilizing carbon-coated silicon monoxide particles described in any one of the above, including:

[0126] An iCVD chamber, including a cavity 21 and a filament 22 placed in the cavity 21, and the filament 22 can be energized;

[0127] A rotation motor 3, coupled to the iCVD chamber, and the rotation motor 3 is used to control the rotation of the iCVD chamber;

[0128] A heating module 4 for heating the cavity 21;

[0129] A protective gas introduction module 5, and the protective gas introduction module 5 is used to introduce a protective gas into the iCVD chamber;

[0130] A GMA monomer introduction module 6, and the GMA monomer introduction module 6 is used to introduce the vaporized GMA monomer into the iCVD chamber;

[0131] A TBPO initiator introduction module 7, and the TBPO initiator heating module 4 is used to introduce the vaporized TBPO initiator into the iCVD chamber;

[0132] A flow rate control module 8, respectively coupled to the control ends of the protective gas introduction module 5, the GMA monomer introduction module 6, and the TBPO initiator introduction module 7, and the flow rate control module 8 is used to respectively control the flow rates of the gases in the protective gas introduction module 5, the GMA monomer introduction module 6, and the TBPO initiator introduction module 7.

[0133] It should be understood that the rotary motor 3 is only used to rotate the iCVD chamber and does not come into contact with the protective gas introduction module, the GMA monomer introduction module 6, and the TBPO initiator introduction module 7.

[0134] As an example, the reaction chamber pressure of the iCVD chamber in the embodiment of the present invention can be 600 to 800 millitorr (mTorr), and the reaction time can be 5 to 20 minutes. Of course, the present invention is not limited thereto, and those skilled in the art can select appropriate pressure values and reaction times according to needs.

[0135] As an example, the heating module 4 may include: an oil bath heating pan for heating the temperature of the cavity 21 to between 50 °C and 80 °C.

[0136] Of course, the present invention is not limited to this, and it can also be a dry thermostat, a water bath heating pan, etc. Those skilled in the art can select appropriate equipment for uniform heating according to needs.

[0137] In the embodiment of the present invention, the filament is heated by being energized. Of course, the filament can also be heated by other means, such as microwave heating, etc.

[0138] In practical applications, please refer to Figure 6 , the above-mentioned GMA monomer introduction module 6 may include a GMA monomer container 61, a first valve 62, and a first conduit 63;

[0139] The GMA monomer container 61 is sequentially coupled to the iCVD chamber through the first valve 62 and the first conduit 63. The GMA monomer container 61 is used to vaporize the GMA monomer and introduce the vaporized GMA monomer into the iCVD chamber through the first conduit 63.

[0140] In this case, the flow rate control module 8 is also coupled to the first valve 62, and the flow rate control module 8 is further configured to:

[0141] Control the opening amount of the first valve 62 to control the flow rate of the vaporized GMA monomer introduced into the iCVD chamber.

[0142] In a preferred embodiment, the flow rate control module 8 is further configured to:

[0143] Control the opening amount of the first valve 62 to control the air pressure in the GMA monomer container so that the GMA monomer is vaporized.

[0144] Correspondingly, the above-mentioned TBPO initiator introduction module 7 may also include a TBPO initiator container 71, a second valve 62, and a second conduit 73;

[0145] The TBPO initiator container 71 is coupled to the iCVD chamber through a second valve 62 and a second conduit 73 in sequence. The TBPO initiator container 71 is configured to vaporize the TBPO initiator and introduce the vaporized TBPO initiator into the iCVD chamber through the second conduit 73.

[0146] In this case, the flow rate control module 8 is further coupled to the second valve 72, and the flow rate control module 8 is further configured to:

[0147] Control the opening amount of the second valve 72 to control the flow rate of the vaporized TBPO initiator introduced into the iCVD chamber.

[0148] In a preferred embodiment, the flow rate control module 8 is further configured to: control the opening amount of the second valve 72 to control the air pressure in the TBPO initiator container, so that the TBPO initiator is vaporized.

[0149] In actual operation, the filament can be hollow, and the output ends of the first conduit 63 and the second conduit 73 are both located in the hollow part of the filament 22, so that both the TBPO initiator and the GMA monomer can be affected by the heated filament 22 and are evenly heated.

[0150] In other embodiments, the protective gas introduction module 5 may also include a protective gas container 51, a third valve 52, and a third conduit 53;

[0151] The protective gas container 51 is coupled to the iCVD chamber through the third valve 52 and the third conduit 53 in sequence.

[0152] On this basis, the flow rate control module 8 may also be coupled to the third valve 52, and the flow rate control module 8 is further configured to: control the opening amount of the third valve 52 to control the flow rate of the protective gas introduced into the iCVD chamber.

[0153] Of course, in other embodiments, the GMA monomer container 61 and the TBPO initiator container 71 may also be used to heat the GMA monomer and the TBPO initiator respectively to vaporize the GMA monomer and the TBPO initiator.

[0154] In Figure 6In the example, the iCVD chamber in the embodiment of the present invention is a single-neck round-bottom flask. The round-bottom flask has a first interface for connecting to a rotating motor 3, a second interface for connecting to a protective gas introduction module 5, a third interface for connecting to a GMA monomer introduction module 6, a fourth interface for connecting to a TBPO initiator introduction module 7, and a vacuum outlet. Among them, the above interfaces are all connected to the mouth of the round-bottom flask.

[0155] The vacuum outlet is usually connected to a vacuum pump 9 or an exhaust gas treatment system to discharge the air and excess gas in the chamber and maintain the required working pressure. This structure is the prior art in the field and will not be elaborated here.

[0156] In Figure 6 the example, a pressure detector 100 is further included in the iCVD chamber. The pressure monitor 100 is coupled to the flow rate control module 8, and the pressure monitor 100 is used to monitor the reaction chamber pressure of the iCVD chamber.

[0157] On this basis, the flow rate control module 8 is further configured to:

[0158] Based on the reaction chamber pressure, respectively control the opening amounts of the first valve 62, the second valve 62, and the third valve 52 to respectively control the flow rates of the protective gas, the vaporized GMA monomer, and the vaporized TBPO initiator introduced into the iCVD chamber.

[0159] Of course, the present invention does not limit this. Those skilled in the art can select a suitable setting method for the iCVD chamber according to needs.

[0160] Of course, the present invention is not limited thereto. Those skilled in the art can select a suitable method to introduce the vaporized GMA monomer and the vaporized TBPO initiator.

[0161] In summary, in the embodiment of the present invention, carbon-coated silicon monoxide particles are placed in an iCVD chamber, and a protective gas is introduced to exclude the air in the iCVD chamber. The iCVD chamber is rotated so that the carbon-coated silicon monoxide particles can be uniformly coated with a polymer in subsequent steps. During the rotation of the iCVD chamber, the chamber and the filament are heated respectively, and GMA monomer and TBPO initiator are vaporized and introduced into the iCVD chamber, so that the TBPO initiator is activated at the filament to generate highly reactive free radicals. These free radicals will initiate the polymerization of GMA monomer into PGMA polymer, and the PGMA polymer will adhere to the surface of the silicon monoxide particles by physical adsorption. At the same time, the excess GMA monomer and free radicals in the chamber will continue to react with the PGMA polymer on the surface of the silicon monoxide, so as to form a uniform and flexible PGMA polymer coating layer on the surface of the carbon-coated silicon monoxide particles, realizing the conformal coating of the carbon-coated silicon monoxide particles, avoiding the problem of cracking and shedding of the carbon coating layer, and further improving the cycle performance of the carbon-coated silicon monoxide particles.

[0162] In addition, the embodiment of the present invention also provides a method for preparing an electrode paste, including:

[0163] Mixing a PAA binder, a modified material, a conductive agent, and deionized water to form the electrode paste;

[0164] Wherein, the modified material is prepared by using the method for stabilizing carbon-coated silicon monoxide particles as described in any one of the above, and the modified material is the carbon-coated silicon monoxide particles with a PGMA polymer coating layer formed on the surface.

[0165] PAA herein can be understood as polyacrylic acid.

[0166] Now in combination with Figure 7 the preparation effect of the electrode paste provided by the embodiment of the present invention is described. Figure 7 The process of the ring-opening reaction between the modified material (SiO x @C@PGMA) particles and PAA (polyacrylic acid) and the finally formed connection network are shown. Among them:

[0167] The green particles can be understood as the modified material (SiO x @C@PGMA) particles;

[0168] The small bottle can be understood as the above particles existing as materials;

[0169] PAA can be understood as the PAA binder;

[0170] PGMA can be understood as the material of the PGMA polymer coating layer;

[0171] AB can be understood as a conductive agent.

[0172] Among them, the PAA molecule has multiple carboxyl groups (-COOH), and the PGMA molecule has epoxy groups (epoxy ethyl groups, Epoxy group). During the ring-opening reaction, the epoxy group of PGMA is ring-opened by the carboxyl group of PAA to form new chemical bonds (such as hydroxyl groups and ester / ether bonds). It can be seen that this reaction will form a strong chemical connection between the PGMA chain and the PAA chain, making the active material particles tightly connected to each other and to the conductive network, preventing the material particles from detaching from the conductive network during the electrochemical cycle and improving the continuity of the conductive network.

[0173] In Figure 7 the example of, the structure after the connection of PGMA and PAA provides more bonding sites on the surface of the material particles, laying a foundation for the subsequent firm combination with the conductive agent, constructing a uniformly dispersed conductive network, and thus improving the cycling performance and stability of applications such as batteries.

[0174] It can be seen that the invention utilizes the ring-opening reaction of the PGMA polymer coating layer and the PAA binder to generate a conductive-linking network, making the carbon-coated silicon monoxide particles not easily detached from the conductive network and improving the cycling performance of the carbon-coated silicon monoxide particles.

[0175] In a preferred embodiment, the conductive agent is an acetylene black (AB, Acetylene Black) conductive agent.

[0176] Now in combination with Figure 8 the bonding situation of the conductive agent will be described. Figure 8 The TEM images showing the adhesion of the modified material (SCP) and the unmodified material (SC) to the conductive agent AB are presented.

[0177] Since the PGMA polymer coating layer is formed on the surface of the carbon-coated silicon monoxide particles in the present invention, the acetylene black conductive agent is more likely to adhere to the surface of the modified carbon-coated silicon monoxide particles, while the conductive agent AB cannot adhere to the surface of the unmodified carbon-coated silicon monoxide particles. Obviously, the present invention further improves the cycling performance of the carbon-coated silicon monoxide particles.

[0178] In addition, the present invention also provides a battery, including an electrode paste, which is prepared by the preparation method of the electrode paste described above. By way of example, the battery can be a lithium-ion battery, and the present invention does not limit this, and it can also be other batteries.

[0179] In summary, in the embodiment of the present invention, an electrode paste is formed by mixing a PAA binder, the material, a conductive agent, and deionized water. Among them, the modified material is carbon-coated silicon monoxide particles with a PGMA polymer coating layer formed on the surface. The present invention utilizes the ring-opening reaction between the PGMA polymer coating layer and the PAA binder to prevent the carbon-coated silicon monoxide particles from detaching from the conductive network and improve the cycling performance of the carbon-coated silicon monoxide particles.

[0180] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope defined by the claims.

Claims

1. A method for stabilizing carbon-coated silicon oxide particles, characterized in that: include: Placing the carbon-coated silicon oxide particles into an iCVD chamber, wherein the iCVD chamber comprises a cavity and a filament placed in the cavity; Introducing a protective gas into the iCVD chamber to remove air from the iCVD chamber; After placing carbon-coated silicon oxide particles into the iCVD chamber, rotating the iCVD chamber; During the rotation of the iCVD chamber, heating the chamber; During the rotation of the iCVD chamber, heating the filament; The vaporized GMA monomer and TBPO initiator are introduced into the iCVD chamber, so that the TBPO initiator is affected by the heated filament to initiate a polymerization reaction of the GMA monomer, so as to form a PGMA polymer coating layer on the surface of the carbon-coated silicon oxide particles.

2. The method for stabilizing carbon-coated silicon oxide particles according to claim 1, characterized in that: The method for heating the cavity comprises: heating the temperature of the cavity to between 50°C and 80°C.

3. The method for stabilizing carbon-coated silicon oxide particles according to claim 2, characterized in that: A method for heating the cavity, comprising: The cavity is heated by an oil bath heating method.

4. The method for stabilizing carbon-coated silicon oxide particles according to claim 1, characterized in that: The method for heating the filament comprises: heating the filament to a temperature between 140°C and 300°C.

5. The method for stabilizing carbon-coated silicon oxide particles according to claim 1, characterized in that: The protective gas is an inert gas.

6. The method for stabilizing carbon-coated silicon oxide particles according to claim 5, characterized in that: When the protective gas is nitrogen, the method for introducing the protective gas comprises: The nitrogen gas is introduced into the iCVD chamber at a flow rate between 3 sccm and 5 sccm.

7. The method for stabilizing carbon-coated silicon oxide particles according to claim 1, characterized in that: The method of vaporizing the GMA monomer and the TBPO initiator and introducing them into the iCVD chamber comprises: Passing the vaporized GMA monomer into the iCVD chamber at a flow rate between 0.3 sccm and 0.7 sccm; The vaporized TBPO initiator is introduced into the iCVD chamber at a flow rate between 0.8 sccm and 1.2 sccm.

8. The method for stabilizing carbon-coated silicon oxide particles according to claim 1, characterized in that: The thickness of the PGMA polymer coating layer is between 21 nm and 36 nm.

9. The method for stabilizing carbon-coated silicon oxide particles according to claim 1, characterized in that: The reaction chamber pressure of the iCVD chamber is between 600mTorr and 800mTorr.

10. The method for stabilizing carbon-coated silicon oxide particles according to claim 1, characterized in that: The vaporized GMA monomer and TBPO initiator are introduced into the iCVD chamber, so that the TBPO initiator is affected by the heated filament to initiate the polymerization reaction of the GMA monomer for a reaction time of 5 minutes to 20 minutes.

11. An iCVD device, characterized in that: The method for realizing the stable carbon-coated silicon oxide particles according to any one of claims 1 to 10 comprises: An iCVD chamber comprises a chamber and a filament disposed in the chamber, wherein the filament can be energized; A rotary motor, coupled to the iCVD chamber, the rotary motor is used to control the iCVD chamber to rotate; A heating module, used for heating the cavity; A protective gas introduction module, wherein the protective gas introduction module is used to introduce protective gas into the iCVD chamber; A GMA monomer introduction module, the GMA monomer introduction module is used to introduce the vaporized GMA monomer into the iCVD chamber; A TBPO initiator introduction module, wherein the TBPO initiator heating module is used to introduce the vaporized TBPO initiator into the iCVD chamber; The flow rate control module is respectively coupled to the control end of the protective gas introduction module, the control end of the GMA monomer introduction module and the control end of the TBPO initiator introduction module, and is used to control the flow rate of the gas in the protective gas introduction module, the GMA monomer introduction module and the TBPO initiator introduction module respectively.

12. The iCVD device according to claim 11, wherein: The heating module comprises: The oil bath heating pot is used to heat the temperature of the cavity to between 50°C and 80°C.

13. The iCVD device according to claim 11, wherein: The GMA monomer introduction module includes a GMA monomer container, a first valve and a first conduit; The GMA monomer container is coupled to the iCVD chamber through the first valve and the first conduit in sequence, and the GMA monomer container is used to vaporize the GMA monomer and introduce the vaporized GMA monomer into the iCVD chamber through the first conduit; The flow rate control module is also coupled to the first valve, and the flow rate control module is further configured to: The opening amount of the first valve is controlled to control the flow rate of the vaporized GMA monomer into the iCVD chamber.

14. The iCVD device according to claim 13, wherein: The flow rate control module is further configured to: control the opening amount of the first valve to control the gas pressure in the GMA monomer container so as to vaporize the GMA monomer.

15. The iCVD device according to claim 11, wherein: The TBPO initiator introduction module may also include a TBPO initiator container, a second valve, and a second conduit; The TBPO initiator container is coupled to the iCVD chamber through the second valve and the second conduit in sequence, and the TBPO initiator container is used to vaporize the TBPO initiator and introduce the vaporized TBPO initiator into the iCVD chamber through the second conduit; The flow rate control module is also coupled to the second valve, and the flow rate control module is further configured to: The opening amount of the second valve is controlled to control the flow rate of the vaporized TBPO initiator into the iCVD chamber.

16. The iCVD device according to claim 15, wherein: The flow rate control module is further configured to: control the opening amount of the second valve to control the gas pressure in the TBPO initiator container so as to vaporize the TBPO initiator.

17. A method for preparing an electrode slurry, characterized in that: include: Mixing a PAA binder, a modifying material, a conductive agent and deionized water to form the electrode slurry; The modified material is prepared by the method for stabilizing carbon-coated silicon oxide particles according to any one of claims 1 to 10, and the modified material is the carbon-coated silicon oxide particles with a PGMA polymer coating layer formed on the surface.

18. The method for preparing an electrode slurry according to claim 17, characterized in that: The conductive agent is acetylene black conductive agent.

19. A battery, characterized in that: It comprises an electrode slurry, and the electrode slurry is prepared by the method for preparing the electrode slurry according to claim 17 or 18.

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