Negative electrode material

Abstract

The present application provides a negative electrode material. The negative electrode material comprises a carbon matrix and a silicon material, wherein at least part of the silicon material is located in the carbon matrix. N positions are randomly selected on the particles of the negative electrode material to perform Raman spectra measurement, and it is measured that the negative electrode material has a first characteristic peak at 1342±10 cm-1, a second characteristic peak at 1595±10 cm-1, a third characteristic peak at 480±10 cm-1, and a fourth characteristic peak at 517±10 cm-1, wherein the average value of the peak intensity ratio I1 / I2 of the first characteristic peak to the second characteristic peak measured at the N positions is P, the average value of the peak intensity ratio I3 / I4 of the third characteristic peak to the fourth characteristic peak measured at the N positions is S, and the negative electrode material satisfies: 0.9<P<1.2, 1.05<S<1.25, and N≥10. The negative electrode material provided in the present application can have a high capacity, a low expansibility, and an excellent initial coulombic efficiency.

Description

Anode material

[0001] This application claims priority to Chinese patent application No. 202510177634.2, filed with the State Intellectual Property Office of China on February 18, 2025, entitled “Anode Material”, the contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of negative electrode materials technology, and more particularly to negative electrode materials. Background Technology

[0003] Anode materials are one of the key materials for achieving high capacity and long cycle life in lithium-ion batteries. However, traditional graphite anode materials often have low capacity, while silicon anode materials have high specific capacity and are suitable for future lithium-ion batteries with higher energy density. However, silicon anode materials experience a volume expansion of over 300% during lithium intercalation; at the same time, silicon has poor conductivity, resulting in high internal resistance, which hinders the widespread application of silicon anode materials.

[0004] Porous carbon materials possess abundant pore structures, providing ample embedding space for nano-silicon materials, suppressing the expansion effect of silicon anode materials, and mitigating their pulverization problem. Simultaneously, the carbon framework of porous carbon exhibits excellent electronic conductivity, providing a well-developed conductive network for silicon anode materials, improving their conductivity and enhancing their initial efficiency. However, to achieve high conductivity in porous carbon, it is often necessary to subject it to high-level graphitization, which may lead to the collapse of some pores and a decrease in capacity.

[0005] Therefore, a balance needs to be found between the graphitization degree of porous carbon and the capacity of silicon-carbon anode materials, so that silicon-carbon anode materials can have high capacity, low expansion and better first coulomb efficiency.

[0006] Application content

[0007] This application provides a negative electrode material in which the carbon matrix has a suitable degree of graphitization, which can reduce the pore collapse of the carbon matrix. After being combined with silicon material, the negative electrode material can have high capacity, low expansion and better first coulomb efficiency.

[0008] In a first aspect, this application provides a negative electrode material, the negative electrode material comprising a carbon matrix and a silicon material, wherein at least a portion of the silicon material is located within the carbon matrix;

[0009] Raman spectroscopy was performed on N randomly selected sites on the particles of the negative electrode material. The results showed that the negative electrode material exhibited Raman spectroscopy at a depth of 1342±10 cm⁻¹. -1 It has the first characteristic peak at 1595±10 cm. -1 It has a second characteristic peak at 480±10 cm.-1 It has a third characteristic peak at 517±10 cm. -1 The location has a fourth characteristic peak; wherein, the average value of the peak intensity ratio I1 / I2 of the first characteristic peak and the second characteristic peak measured at N sites is P, and the average value of the peak intensity ratio I3 / I4 of the third characteristic peak and the fourth characteristic peak measured at N sites is S.

[0010] The negative electrode material satisfies the following conditions: 0.9 < P < 1.2, 1.05 < S < 1.25, N ≥ 10.

[0011] Compared with the prior art, the technical solution of this application has at least the following beneficial effects:

[0012] The negative electrode material provided in this application, I1 is the negative electrode material at 1342±10cm. -1 The Raman peak intensity at [location] is 1595 ± 10 cm⁻¹ for I₂ as the negative electrode material. -1 The Raman peak intensity at 480±10 cm⁻¹ is observed for I₃ as the negative electrode material. -1 The Raman peak intensity at [location] is 517 ± 10 cm⁻¹ for I₄ as the negative electrode material. -1 The Raman peak intensity at the specified location; controlling the average value P of I1 / I2 within the above range, the carbon matrix in the negative electrode material can maintain a suitable degree of graphitization, reducing pore collapse and capacity decay caused by high graphitization of the carbon matrix, resulting in good conductivity of the carbon matrix and excellent powder conductivity of the negative electrode material; and under suitable graphitization conditions, the carbon matrix has a larger graphite interlayer spacing, which increases the lithium intercalation capacity of the carbon matrix. Silicon material is located within the carbon matrix, which provides structural support for the silicon material, reducing the aggravation of side reactions caused by direct contact between the silicon material and the electrolyte. Furthermore, controlling the average value S of I3 / I4 within the above range, the silicon material in the negative electrode material achieves a balance between crystalline silicon and amorphous silicon content. This allows for the utilization of the high capacity and low expansion performance of amorphous silicon to reduce the expansion rate of the negative electrode material, and also utilizes the high particle strength characteristics of crystalline silicon to improve the structural strength of the negative electrode material. This application controls the anode material to satisfy: 0.9 < P < 1.2, 1.05 < S < 1.25, so that the anode material can have high capacity, low expansion and better first coulomb efficiency. Attached Figure Description

[0013] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0014] Figure 1 is a schematic flowchart of the preparation method of the negative electrode material provided in the embodiment of this application;

[0015] Figure 2 shows the Raman spectra of the negative electrode materials prepared in the embodiments and comparative examples of this application;

[0016] Figure 3 is a schematic diagram of the discharge state of the battery provided in the embodiment of this application. Detailed Implementation

[0017] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0018] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0019] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0020] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0021] In a first aspect, this application provides a negative electrode material, the negative electrode material comprising a carbon matrix and a silicon material, wherein at least a portion of the silicon material is located within the carbon matrix;

[0022] Raman spectroscopy was performed on N randomly selected sites on the particles of the negative electrode material. The results showed that the negative electrode material was at a wavelength of 1342±10 cm⁻¹. - 1 It has the first characteristic peak at 1595±10 cm. -1 It has a second characteristic peak at 480±10 cm. -1 It has a third characteristic peak at 517±10 cm. -1 The fourth characteristic peak is present at the location; among which, the average value of the peak intensity ratio I1 / I2 of the first characteristic peak measured at N sites to the second characteristic peak is P, and the average value of the peak intensity ratio I3 / I4 of the third characteristic peak measured at N sites to the fourth characteristic peak is S.

[0023] The negative electrode material satisfies the following conditions: 0.9 < P < 1.2, 1.05 < S < 1.25, N ≥ 10.

[0024] The negative electrode material provided in this application, I1 is the negative electrode material at 1342±10cm. -1 The Raman peak intensity at [location] is 1595 ± 10 cm⁻¹ for I₂ as the negative electrode material.-1 The Raman peak intensity at 480±10 cm⁻¹ is observed for I₃ as the negative electrode material. -1 The Raman peak intensity at [location] is 517 ± 10 cm⁻¹ for I₄ as the negative electrode material. -1 The Raman peak intensity at the specified location is controlled. By keeping the average value P of I1 / I2 within the above range, the carbon matrix in the anode material can maintain a suitable degree of graphitization, reducing pore collapse and capacity decay caused by high graphitization of the carbon matrix. Simultaneously, the carbon matrix exhibits good electrical conductivity, and the anode material also possesses excellent powder conductivity. Furthermore, under suitable graphitization conditions, the carbon matrix will have a larger interlayer spacing, increasing the lithium intercalation capacity of the carbon matrix. Silicon material is located within the carbon matrix, which provides structural support, reducing the exacerbation of side reactions caused by direct contact between silicon material and the electrolyte. Furthermore, by controlling the average value S of I3 / I4 within the above range, the silicon material in the anode material achieves a balance between crystalline and amorphous silicon content. This allows for the utilization of the high capacity and low expansion properties of amorphous silicon to reduce the expansion rate of the anode material, while also leveraging the high particle strength characteristics of crystalline silicon to enhance the structural strength of the anode material. This application controls the anode material to satisfy: 0.9 < P < 1.2, 1.05 < S < 1.25, so that the anode material can have high capacity, low expansion and better first coulomb efficiency.

[0025] In some embodiments, the average value P of the I1 / I2 ratio can specifically be 0.91, 0.92, 0.95, 1.0, 1.05, 1.08, 1.09, 1.1, 1.15, 1.16, 1.18, 1.19, or 1.195, etc., or other values ​​within the above range, which are not limited here. When the P value of the negative electrode material is too large, the graphitization degree of the carbon matrix in the negative electrode material is too low, and the powder conductivity of the negative electrode material decreases. When the P value of the negative electrode material is too small, the graphitization degree of the carbon matrix in the negative electrode material is too high, leading to the collapse of carbon matrix pores and a decrease in the capacity of the negative electrode material. When the P-value is controlled within the above range, the carbon matrix in the anode material can maintain a suitable degree of graphitization, reducing pore collapse and capacity decay caused by high graphitization of the carbon matrix, resulting in good electrical conductivity of the carbon matrix and excellent powder conductivity of the anode material. The silicon material is located in the carbon matrix, which can provide structural support for the silicon material, reduce the side reactions caused by direct contact between the silicon material and the electrolyte, and under suitable graphitization conditions, the carbon matrix has a large interlayer spacing of graphite, which increases the lithium intercalation capacity of the carbon matrix.

[0026] In some implementations, the average value S of the I3 / I4 ratio can be 1.051, 1.06, 1.07, 1.08, 1.09, 1.1, 1.15, 1.2, 1.21, 1.22, 1.23, or 1.249, or other values ​​within the above range, which are not limited here. When the S value of the negative electrode material is too large, the mass content of amorphous silicon in the negative electrode material is too high. Excessive amorphous silicon may deposit on the outer surface of the carbon matrix, leading to an increase in side reactions of the negative electrode material, affecting the cycle stability of the negative electrode material, and affecting the controllability of the growth position and content of subsequent crystalline silicon, resulting in an increase in the expansion rate of the negative electrode material and a decrease in the initial coulombic efficiency. When the S value of the negative electrode material is too small, the mass content of crystalline silicon in the negative electrode material is too high, the high expansion effect of crystalline silicon is aggravated, the expansion rate of the negative electrode material increases, the number of vacancies left by the removal of amorphous silicon increases, the specific surface area of ​​the negative electrode material increases, side reactions are aggravated, and the initial coulombic efficiency of the negative electrode material decreases. When the S-value is controlled within the above range, the silicon material in the negative electrode material reaches a balance in terms of the content of crystalline silicon and amorphous silicon. This allows the high capacity and low expansion performance of amorphous silicon to be utilized to reduce the expansion rate of the negative electrode material, and also allows the high particle strength characteristics of crystalline silicon to be utilized to improve the structural strength of the negative electrode material.

[0027] In some embodiments, the average particle size of the silicon material is 1 nm to 100 nm, specifically 1 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm, etc., and of course, other values ​​within the above range are also possible, without limitation. The expansion stress of the silicon material decreases as the particle size decreases, and the smaller size shortens the electron and ion transport path. Simultaneously, the smaller particle size increases the gap between adjacent silicon particles, reserving space for expansion. An average particle size within the above range ensures the battery capacity of the lithium-ion battery and reduces irreversible capacity loss. Preferably, the average particle size of the silicon material is 1 nm to 50 nm, more preferably, it is 1 nm to 20 nm.

[0028] In some embodiments, the silicon material comprises composite particles of crystalline and amorphous silicon. The amorphous silicon expands isotropically during lithium intercalation, reducing the collapse of the pore structure in the negative electrode material, suppressing rapid capacity decay, and improving the lithium intercalation cycle performance. An appropriate amount of crystalline silicon can increase the particle strength of the negative electrode material, reducing particle breakage during electrode fabrication or rolling, minimizing side reactions between the silicon material and the electrolyte, and improving the initial coulombic efficiency of the negative electrode material.

[0029] In some embodiments, the carbon matrix includes amorphous carbon and graphitized carbon. Choosing either of these materials as the carbon matrix can provide pore distribution sites for the active material and form a conductive network.

[0030] In some embodiments, at least a portion of the silicon material is located within the carbon matrix. The silicon material filling the carbon matrix ensures a dispersed distribution of silicon within the carbon matrix, which on the one hand increases the specific capacity of the anode material, and on the other hand increases the density of the anode material, effectively reducing the occurrence of side reactions and further improving the cycle performance of the material.

[0031] In some embodiments, the specific surface area of ​​the negative electrode material is ≤10m². 2 / g; specifically, the specific surface area of ​​the negative electrode material can be 1m². 2 / g、2m 2 / g、3m 2 / g、4m 2 / g、5m 2 / g、6m 2 / g、7m 2 / g、8m 2 / g、9m 2 / g or 10m 2 / g, etc., can also be other values ​​within the above range, and are not limited here. Controlling the specific surface area of ​​the negative electrode material within the above range is beneficial to suppressing the volume expansion of the negative electrode material and improving its cycle performance.

[0032] In some embodiments, the powder conductivity of the negative electrode material at a pressure of 20 kN is 0.1 S / cm to 3 S / cm, specifically 0.1 S / cm, 0.2 S / cm, 0.3 S / cm, 0.5 S / cm, 0.7 S / cm, 0.9 S / cm, 1.0 S / cm, 1.5 S / cm, 1.8 S / cm, 2 S / cm, 2.5 S / cm, or 3 S / cm, etc., and is not limited here. Because silicon has poor conductivity, the conductivity of the negative electrode material is generally lower. Controlling the powder conductivity of the negative electrode material within the above range shows that very little silicon material is exposed on the surface of the negative electrode material, and the silicon material is embedded in the carbon matrix, which can effectively improve the electrochemical performance of the negative electrode material. Preferably, the powder conductivity of the negative electrode material at a pressure of 20 kN is 1.0 S / cm to 2.5 S / cm.

[0033] In some embodiments, the relative particle strength of the negative electrode material is 110 MPa to 150 MPa, specifically 110 MPa, 120 MPa, 125 MPa, 130 MPa, 135 MPa, 140 MPa, 145 MPa, or 150 MPa, etc., or other values ​​within the above range, which are not limited here. Controlling the relative particle strength of the negative electrode material within the above range provides strong rigidity and structural stability, enabling it to withstand certain volume expansion stress and improving the cycle stability of the negative electrode material.

[0034] In some implementations, the median particle size D50 of the negative electrode material satisfies: 5 μm < D 50 <20μm, the median particle size D50 of specific anode materials can be 5.1μm, 5.5μm, 6μm, 7.5μm, 8μm, 9μm, 10μm, 12μm, 14μm, 15μm, 18μm, or 19.9μm, etc., without limitation. The median particle size D50 of the anode material directly affects the specific surface area and electron transport path of the anode material. Smaller particle size usually means a larger specific surface area, which is conducive to the electrochemical reaction and the rapid charge transport, thereby improving the power density and energy density of the battery; smaller particle size can reduce the volume change of the material during lithium-ion insertion / extraction cycles, which helps to reduce structural stress and deformation, thereby extending the cycle life of the battery; the range of median particle size can also further affect the pore structure and pore volume of the anode material, affecting the particle space collapse ratio of the anode material. Furthermore, the median particle size D50 of the anode material can be 1μm to 10μm.

[0035] In some embodiments, the silicon content in the negative electrode material is 35% to 65% by mass. Specifically, the silicon content can be 35%, 38%, 40%, 42%, 45%, 50%, 55%, 58%, 60%, or 65%, or other values ​​within the aforementioned range, which are not limited here. When the silicon content in the negative electrode material falls within this range, the resulting lithium battery can store a higher amount of electricity, i.e., it has a higher initial discharge specific capacity.

[0036] In some embodiments, the carbon content in the negative electrode material is 30% to 63% by mass. Specifically, the carbon content can be 30%, 33%, 40%, 50%, 53%, 55%, 58%, 60%, 62%, or 63%, or other values ​​within the aforementioned range, which are not limited here. The carbon content includes a carbon matrix and a carbon layer on the surface of the negative electrode material. When the carbon content is within this range, a sufficient carbon-based substrate can be established, providing ample distribution sites for the active material, which is beneficial for forming an effective conductive network and improving conductivity and cycle stability.

[0037] In some embodiments, the oxygen content in the negative electrode material is 0.05% to 2.0% by mass. Specifically, the oxygen content can be 0.05%, 0.06%, 0.08%, 1.0%, 1.2%, 1.5%, 1.6%, 1.8%, or 2.0%, or other values ​​within the above range, which are not limited here. If the oxygen content is too high, the silicon material in the negative electrode material will be partially oxidized. Controlling the oxygen content in the negative electrode material within the above range is beneficial for improving the specific capacity of the negative electrode material and reducing the formation of inactive silicon dioxide.

[0038] In some embodiments, the mass content of hydrogen in the negative electrode material is <1%. The specific mass content of hydrogen can be 0.05%, 0.06%, 0.08%, 0.09%, 0.1%, 0.2%, 0.5%, 0.6%, 0.7%, 0.8%, or 0.99%, etc., or other values ​​within the above range, which are not limited here.

[0039] In some embodiments, the pore volume of the negative electrode material is ≤0.1 cm³. 3 / g; the pore volume of the negative electrode material can specifically be 0.001cm³. 3 / g, 0.002cm 3 / g, 0.005cm 3 / g, 0.008cm 3 / g, 0.01cm 3 / g, 0.02cm 3 / g, 0.03cm 3 / g, 0.04cm 3 / g, 0.05cm 3 / g, 0.06cm 3 / g, 0.07cm 3 / g, 0.08cm 3 / g, 0.09cm 3 / g or 0.1cm 3 / g, etc., can also be other values ​​within the above range, and are not limited here. Controlling the pore volume of the negative electrode material within the above range is beneficial to mitigating the volume expansion of the silicon material and improving the cycle stability of the negative electrode material.

[0040] In some embodiments, the specific capacity of the negative electrode material is 1800mAh / g to 2500mAh / g, specifically 1800mAh / g, 1900mAh / g, 2000mAh / g, 2100mAh / g, 2200mAh / g, 2300mAh / g, 2400mAh / g or 2500mAh / g, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0041] Secondly, this application provides a method for preparing a negative electrode material, as shown in Figure 1, including the following steps:

[0042] Step S100: Prepare a porous carbon matrix;

[0043] In step S200, silicon material is composited with carbon matrix under inert gas to obtain anode material.

[0044] The following is a detailed introduction to this plan:

[0045] Step S100: Prepare carbon material and activate the carbon material to obtain a porous carbon matrix.

[0046] In some embodiments, the carbon source for preparing the carbon material includes at least one selected from polyvinyl chloride, polyvinyl butyral, polyacrylonitrile, polyacrylic acid, polyethylene glycol, polypyrrole, polyaniline, sucrose, glucose, maltose, citric acid, asphalt, furfural resin, epoxy resin, and phenolic resin.

[0047] In some embodiments, carbon materials are prepared by carbonizing a carbon source. The carbonization temperature is 700℃ to 950℃, specifically 700℃, 720℃, 750℃, 780℃, 800℃, 820℃, 830℃, 850℃, 900℃, or 950℃, etc. Of course, other values ​​within the above range are also possible and are not limited here.

[0048] In some embodiments, the carbonization treatment time is 1h to 5h, specifically 1h, 2h, 3h, 4h, 4.5h or 5h, etc., and of course other values ​​within the above range are also possible, which are not limited here.

[0049] In some embodiments, the carbonization process is carried out under a protective atmosphere, which includes at least one of nitrogen, helium, neon, argon, and krypton.

[0050] In some embodiments, the method further includes: shaping the carbonization product, the shaping process including at least one of crushing, grinding, ball milling and air crushing.

[0051] In some embodiments, the median particle size of the shaping product satisfies 15μm < D50 < 35μm, specifically it can be 15.5μm, 16μm, 18μm, 20μm, 25μm, 28μm, 30μm, 32μm, 33μm or 34.9μm, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0052] In some implementations, the shaping product is a carbon matrix.

[0053] In some embodiments, the shaped product is heated to 600°C to 950°C, and activated by passing steam at a flow rate of 1 to 30 L / min for 1 to 12 hours. After activation, it is shaped again to obtain a carbon matrix.

[0054] In some embodiments, the activation treatment temperature is 600℃ to 950℃, specifically 600℃, 650℃, 680℃, 700℃, 720℃, 750℃, 780℃, 800℃, 820℃, 830℃, 850℃, 900℃ or 950℃, etc., and of course, other values ​​within the above range are also possible, which are not limited here.

[0055] In some implementations, the activation treatment time is 1h to 12h, specifically 1h, 2h, 3h, 4h, 5h, 8h, 10h, 11h or 12h, etc. Of course, other values ​​within the above range are also possible, and no limitation is made here.

[0056] In some embodiments, the steam flow rate is 1 to 30 L / min, specifically 1 L / min, 5 L / min, 10 L / min, 15 L / min, 20 L / min, 25 L / min or 30 L / min, etc., and of course other values ​​within the above range are also possible, which are not limited here.

[0057] In some embodiments, the activated carbon material is mechanically pulverized or air jet pulverized, that is, the carbon matrix particles are made to reach a preset particle size by using gas to impact the carbon material.

[0058] In some embodiments, the particle size of the carbon matrix satisfies: 5μm < D50 < 15μm, specifically it can be 5.1μm, 5.5μm, 6μm, 6.5μm, 8μm, 10μm, 12μm, 13μm, 14μm or 14.9μm, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0059] In this application, carbon materials are activated. After activation, the carbon matrix has abundant pores, which can provide a large amount of space for silicon materials. During the process of carbon matrix composite silicon materials, space can be provided for silicon materials. The composite anode material can have high capacity, low expansion and better first coulomb efficiency.

[0060] In step S200, silicon material is composited with carbon matrix under inert gas to obtain anode material.

[0061] In some embodiments, step S200 includes performing vapor deposition on a carbon substrate using a vapor-phase silicon source to obtain a negative electrode material. The vapor deposition includes a first stage and a second stage, wherein the first stage is an amorphous silicon deposition stage, and the second stage is a crystalline silicon growth stage.

[0062] In some embodiments, in the first stage, amorphous silicon is deposited at 450°C to 650°C for 2 to 12 hours using a vapor-phase silicon source, and then the vapor-phase silicon source is turned off.

[0063] In some embodiments, in the second stage, the temperature is raised to 680°C to 750°C, and hydrogen gas at a flow rate of 5 sccm to 50 sccm is introduced to grow crystalline silicon for 0.5 h to 2 h.

[0064] In some embodiments, the temperature for amorphous silicon deposition is 450°C to 650°C, and the deposition time is 2 hours to 12 hours. Specifically, the temperature can be 450°C, 500°C, 520°C, 550°C, 600°C, 620°C, or 650°C, and the deposition time can be 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 10 hours, or 12 hours, or other values ​​within the above ranges, which are not limited here.

[0065] In some implementations, the flow rate of the silicon source gas is 200 sccm to 800 sccm, specifically 200 sccm, 300 sccm, 400 sccm, 450 sccm, 500 sccm, 650 sccm, 700 sccm, 750 sccm or 800 sccm, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0066] In some implementations, the flow rate of the inert gas in the first stage is 200 sccm to 800 sccm, specifically 200 sccm, 300 sccm, 400 sccm, 450 sccm, 500 sccm, 650 sccm, 700 sccm, 750 sccm or 800 sccm, etc. Of course, other values ​​within the above range are also possible, and no limitation is made here.

[0067] In some embodiments, the inert gas includes at least one of nitrogen, helium, argon, and neon.

[0068] In some implementations, the flow rate ratio of inert gas to silicon source gas is (1 to 1.5):1.

[0069] In some embodiments, the raw materials for the silicon source gas include at least one of silane, silane, monochlorosilane, dichlorosilane, trichlorosilane, tetrachlorosilane, and methylsiloxane.

[0070] By controlling the reaction parameters of amorphous silicon deposition, the gaseous silicon source can penetrate into the carbon matrix and decompose within the pores of the carbon matrix, depositing silicon materials with suitable particle size.

[0071] During amorphous silicon deposition, the cracking of silane produces hydrogen atoms. These hydrogen atoms carry away a small amount of amorphous carbon from the carbon matrix, leading to an increased degree of graphitization of the carbon matrix in the anode material. However, due to the relatively low deposition temperature (450℃~650℃) during amorphous silicon deposition, the pore structure of the carbon matrix remains stable. As the silicon source gas flow rate increases, more hydrogen atoms are generated, and the degree of graphitization of the porous carbon also increases.

[0072] In some implementations, the hydrogen flow rate in the second stage is 5 sccm to 50 sccm, specifically 5 sccm, 15 sccm, 20 sccm, 25 sccm, 30 sccm, 35 sccm, 40 sccm, 45 sccm or 50 sccm, etc. Of course, other values ​​within the above range are also possible, and no limitation is made here.

[0073] In some embodiments, the growth temperature of crystalline silicon is 680℃~750℃, and the growth time is 0.5h~2h. Specifically, the growth temperature can be 680℃, 690℃, 700℃, 720℃, 730℃, 740℃, or 750℃, and the growth time can be 0.5h, 0.6h, 0.8h, 1h, 1.2h, 1.5h, 1.8h, or 2h, or other values ​​within the above ranges are also possible and are not limited here.

[0074] In some embodiments, the flow rate of the inert gas in the second stage is 1000 sccm to 1500 sccm, specifically 1000 sccm, 1100 sccm, 1200 sccm, 1300 sccm, 1400 sccm or 1500 sccm, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0075] In some embodiments, the step of vapor deposition on a carbon substrate using a vapor-phase silicon source includes: placing the carbon substrate in a furnace, introducing 500 sccm of nitrogen and 500 sccm of silicon source, depositing amorphous silicon at 480°C for 10 hours, then turning off the silicon source, adjusting the nitrogen flow rate to 1200 sccm, raising the temperature to 750°C, introducing 10 sccm of hydrogen to grow crystalline silicon for 1 hour, and obtaining the anode material.

[0076] In some embodiments, step S200 specifically includes: preparing a silicon material precursor; and then grinding and combining the silicon material precursor with a carbon matrix to obtain a negative electrode material.

[0077] In some embodiments, the step of preparing the silicon material precursor specifically includes preparing a mixture of silicon-containing material and dispersant, adding flocculant to the mixture for mixing treatment, and then separating the solid and liquid to obtain the precursor.

[0078] In some implementations, the silicon material includes crystalline silicon and amorphous silicon.

[0079] In some cases, the silicon material includes amorphous silicon and silicon alloys. Preferably, the silicon material includes amorphous silicon, which expands isotropically during lithium intercalation, reducing the collapse of the pore structure, suppressing rapid capacity decay, and improving lithium intercalation cycle performance.

[0080] In some embodiments, the average particle size of the silicon material particles is 1nm to 50nm, specifically 1nm, 2nm, 5nm, 8nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm or 50nm, etc., which are not limited here.

[0081] In some embodiments, the dispersant includes at least one selected from stearic acid, sodium stearate, zinc stearate, magnesium stearate, calcium stearate, polyvinylpyrrolidone, carboxymethyl cellulose, and polyacrylic acid.

[0082] In some embodiments, the mass ratio of silicon material to dispersant is 100:(20-100), specifically 100:20, 100:30, 100:40, 100:50, 100:60, 100:70, 100:80, 100:90, or 100:100, etc., or other values ​​within the above range, which are not limited here. A suitable dispersant can improve the dispersion of silicon material in the mixture, reduce silicon material agglomeration, and thus improve the dispersion of silicon material in the precursor.

[0083] In some embodiments, the mixture further includes a solvent, which includes at least one selected from water, methanol, ethanol, ethylene glycol, propanol, isopropanol, glycerol, n-butanol, isobutanol, pentanol, and ethyl acetate.

[0084] In some implementations, the mixing process is carried out under stirring conditions.

[0085] In some implementations, the mixing time is 0.5h to 3h, specifically 0.5h, 1h, 1.5h, 2h, 2.5h or 3h, etc., or other values ​​within the above range, which are not limited here.

[0086] In some embodiments, the solid-liquid separation step includes filtering the mixture after adding the flocculant and freeze-drying it to obtain the precursor.

[0087] In some embodiments, the mass ratio of silicon material to flocculant is 1:(1 to 1.3), specifically 1:1, 1:1.05, 1:1.08, 1:1.1, 1:1.2, 1:1.25 or 1:1.3, etc. Of course, other values ​​within the above range are also possible and are not limited here.

[0088] In some embodiments, the solid content of the flocculant is 0.1% to 0.5%, specifically 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%, etc., and of course, other values ​​within the above range are also possible, which are not limited here.

[0089] In some embodiments, the flocculant includes a flocculant, which includes at least one of inorganic and organic flocculants.

[0090] In some embodiments, the inorganic flocculant includes at least one of aluminum sulfate, aluminum chloride, ferric sulfate, and ferric chloride.

[0091] In some embodiments, the organic flocculant includes at least one of polyaluminum chloride, polyaluminum sulfate, and polyacrylamide.

[0092] In this application, adding flocculant to the mixture allows the dispersed nanoscale silicon material to precipitate in a flocculated manner. However, because the silicon material surface contains dispersant, the silicon material in the flocculated product remains independently dispersed.

[0093] In some embodiments, the freeze-drying temperature is -20°C to -30°C, specifically -20°C, -22°C, -24°C, -25°C, -27°C, -28°C, or -30°C, etc., and is not limited here.

[0094] In some embodiments, the freeze-drying time is 10h to 24h, specifically 10h, 12h, 15h, 18h, 20h, 22h, or 24h, etc., and is not limited here. Freeze-drying allows the nanoscale silicon material to be uniformly dispersed in the dispersant. The second stage uses a composite process of milled silicon and a carbon matrix. The average particle size of the milled silicon is 1nm to 100nm, exemplarily, the average particle size can be 1nm, 10nm, 25nm, 50nm, 70nm, or 100nm, etc., and is not limited here.

[0095] In some embodiments, the silicon material precursor and the carbon matrix are mixed and ground at a mass ratio of 10:100 to 90:100. The mass ratio of the silicon material precursor and the carbon matrix can be 90:100, 50:100, 30:100 or 10:100, etc., and is not limited here.

[0096] In some implementations, the grinding time is 2 hours to 8 hours, specifically 2 hours, 4 hours, 6 hours or 8 hours, etc., and is not limited here.

[0097] In some embodiments, the ground mixture is heated to 680°C to 750°C under a protective atmosphere and sintered for 2 to 8 hours, and then hydrogen gas at 5 sccm to 50 sccm is introduced to grow crystalline silicon for 0.5 to 2 hours.

[0098] In some embodiments, the carbon matrix after being filled with active material is pulverized and sieved through a 500-mesh sieve to obtain anode material with a suitable particle size.

[0099] Step S300: The mixture is coated with gaseous carbon using a gaseous carbon source to obtain the negative electrode material.

[0100] In some embodiments, the raw materials for the gaseous carbon source include at least one selected from methane, ethane, ethylene, acetylene, propyne, propylene, propane, formaldehyde, acetaldehyde, methanol, toluene, benzene, styrene, and phenol.

[0101] In some embodiments, the temperature for gas-phase carbon coating treatment is 550°C to 1000°C; specifically, it can be 550°C, 600°C, 650°C, 700°C, 820°C, 850°C, 900°C, 950°C, or 1000°C. The above temperatures are not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0102] In some embodiments, the gas phase carbon coating treatment time is 1h to 6h, specifically 1h, 2h, 3h, 4h, 5h or 6h, etc., and of course other values ​​within the above range are also possible, which are not limited here.

[0103] In some embodiments, the gas-phase carbon coating process is carried out under a protective atmosphere.

[0104] In some embodiments, the protective atmosphere includes at least one of nitrogen, helium, neon, and argon.

[0105] This application also provides a battery. Figure 3 is a schematic diagram of the discharge state of the battery provided in this application embodiment. As shown in Figure 3, the battery includes a casing and an electrode assembly. The electrode assembly includes a positive electrode 1, a negative electrode 2, and a separator 3, with the separator 3 disposed between the positive electrode 1 and the negative electrode 2. The electrode assembly can be a stacked structure, formed by alternately stacking the positive electrode 1, the separator 3, and the negative electrode 2. In other embodiments, the electrode assembly can also be a wound structure, formed by sequentially stacking and winding the positive electrode, the separator, and the negative electrode.

[0106] In some embodiments, the positive electrode 1 includes a positive current collector 101 and a positive active layer 102 disposed on at least one surface of the positive current collector 101.

[0107] In some embodiments, the positive current collector 101 may be made of aluminum foil or nickel foil, or any composite current collector disclosed in the prior art, such as, but not limited to, current collectors formed by combining the aforementioned conductive foil (aluminum foil or nickel foil, etc.) with a polymer substrate. The positive active layer 102 comprises a positive active material, which includes compounds that reversibly insert and deintercalate metal ions.

[0108] In some embodiments, the positive electrode active material may include lithium transition metal composite oxides, sodium transition metal composite oxides, etc. The lithium transition metal composite oxide contains lithium and at least one element selected from cobalt, manganese, and nickel.

[0109] In some embodiments, the positive electrode active material may include, but is not limited to, lithium cobalt oxide (LiCoO2), lithium nickel manganese cobalt ternary materials (NCM), and lithium manganese oxide (LiMn2O3). 4) Lithium nickel manganese oxide (LiNi) 0.5 Mn 1.5 At least one of lithium iron phosphate (LiFePO4) or lithium iron phosphate (LiFePO4).

[0110] In some embodiments, the negative electrode 2 includes a negative electrode current collector 201 and a negative electrode active material layer 202 disposed on at least one surface of the negative electrode current collector.

[0111] In some embodiments, the negative electrode current collector 201 can be at least one of copper foil, nickel foil, stainless steel foil, titanium foil, or carbon-based current collector, or any composite current collector disclosed in the prior art, such as, but not limited to, current collectors formed by combining the aforementioned conductive foil and polymer substrate. The negative electrode active material layer 202 includes a negative electrode material, which is the negative electrode material described in the first aspect or the negative electrode material prepared by the aforementioned preparation method. The battery provided in this application embodiment has the advantages of high capacity, high initial efficiency, long cycle life, excellent rate performance, and low expansion. The battery can be a lithium-ion battery, a sodium-ion battery, a solid electrolyte battery, etc., and is not limited thereto.

[0112] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

[0113] Example

[0114] Example 1

[0115] (1) Phenolic resin and asphalt were mechanically mixed at a mass ratio of 100:5, then heated to 850℃ for high-temperature carbonization for 4 hours, and mechanically pulverized to obtain carbon precursor (D). 50 =30μm).

[0116] (2) The carbon precursor was activated for 4 hours at a steam flow rate of 25 L / min and an activation temperature of 800 °C. After activation, it was subjected to air jet milling to obtain the carbon matrix (D). 50 =8μm).

[0117] (3) Place the carbon substrate in a kiln, introduce 500 sccm of nitrogen and 200 sccm of silicon source, and deposit amorphous silicon at 500°C for 2 hours. Then turn off the silicon source, adjust the nitrogen flow rate to 1200 sccm, raise the temperature to 700°C, and introduce 5 sccm of hydrogen to grow microcrystalline silicon for 0.5 hours to obtain the anode material.

[0118] The negative electrode material obtained in this application includes a carbon matrix and a silicon material, with at least a portion of the silicon material located within the carbon matrix. Other parameters of the negative electrode material are detailed in Table 1.

[0119] In addition, this application prepared Examples 2 to 14 by adjusting the relevant parameters according to the preparation process of Example 1. The specific process parameters are detailed in Table 1.

[0120] Example 15

[0121] The difference from Example 1 is that:

[0122] (3) A silicon material precursor with an average particle size of 5 nm was mixed and ground with a carbon matrix at a mass ratio of 90:100 for 4 hours. The resulting composite was placed in a nitrogen atmosphere and sintered at 700°C for 5 hours. Then, 5 sccm of hydrogen was introduced to grow microcrystalline silicon for 0.5 hours to obtain the anode material.

[0123] Example 16

[0124] The difference from Example 15 is that:

[0125] (3) A silicon material precursor with an average particle size of 5 nm was mixed and ground with a carbon matrix at a mass ratio of 30:100 for 5 h. The resulting composite was placed in a nitrogen atmosphere and sintered at 700 °C for 5 h. Then, 5 sccm of hydrogen was introduced to grow microcrystalline silicon for 0.5 h to obtain the anode material.

[0126] Furthermore, this application prepared comparative examples 1 to 6 by adjusting relevant parameters according to the preparation process of Example 1. The specific process parameters are detailed in Table 1.

[0127] Table 1. Preparation process parameters of negative electrode materials

[0128] The anode materials prepared in the examples and comparative examples underwent the following performance tests:

[0129] Test methods

[0130] (1) Particle size of negative electrode material:

[0131] The particle size testing method refers to GB / T 19077-2016. The particle size distribution range of the negative electrode material is tested using a Malvern laser particle size analyzer (Mastersizer 3000). The cumulative particle size distribution based on volume is determined by laser diffraction. D50 represents the particle size corresponding to a cumulative particle size distribution percentage of 50%.

[0132] (2) Test method for specific surface area of ​​negative electrode material:

[0133] The specific surface area was measured using a McTriStar3000 specific surface area and pore size analyzer from the USA.

[0134] (3) Test method for pore volume of negative electrode material:

[0135] The tests were conducted using an ASAP2460 instrument from Micron Technology, USA. The pore volume V was determined using the BJH Desorption Cumulative Volume of Pores model. Calculated within the aperture range.

[0136] Micropore and mesopore analyses were performed using Micromeretics ASAP 2460. At liquid nitrogen temperature, the equilibrium adsorption amount of nitrogen on an object's surface is related to its pore size and other characteristics. By combining the relationship between adsorption amount and relative pressure during the adsorption process, various models can be fitted to calculate the pore size. The software report uses density functional theory (DFT) to calculate the pore size distribution, total pore volume, and pore volume within a certain range.

[0137] (4) Powder conductivity test of negative electrode material

[0138] The powder conductivity of the material was tested according to the equipment and methods specified in BTRTC / ZY / 02-093 "Operating Instructions for Powder Conductivity Testing". The testing equipment was a Mitsubishi Chemical MCP-PD51 powder conductivity meter from Japan. Test parameters: initial resistance (selectable to the order of -3), voltage limit (selectable to 10V), and sample quality ensuring a thickness of 3–5 mm under 20 kN pressure. Electrode radius was 0.7 mm, and sample radius was 10 mm.

[0139] (5) Raman testing of negative electrode materials:

[0140] The Raman spectra of the powder were tested using a Renishaw In Via confocal micro-Raman spectrometer (Japan). The test parameters were: laser wavelength 532 nm, 1% filter, 20 μm slit opening, 1800 gr / mm grating, 10 s exposure time, 2 accumulations, 50X Lwd microscope objective, and spectral range 100–2400 cm⁻¹. -1 The sample particles of the negative electrode material were tested. Ten points were randomly selected on the particles for Raman spectroscopy scanning to obtain the average Raman intensity at specific wavenumber positions. Here, intensity refers to the height of the peak.

[0141] (6) Relative particle strength test of negative electrode material

[0142] Using a Shimadzu DUH-211S dynamic microhardness tester, under the influence of electromagnetic force, the force on the indenter gradually increases at a certain rate. When the particle's fracture point is reached, the particle fractures. At this point, the resistance on the indenter disappears, causing it to rapidly displace downwards. The instrument determines the fracture point (rapid increase in displacement) by recording the displacement of the indenter in real time and records the pressure exerted on the particle at this time. The relative particle strength of the material is obtained based on the relationship between pressure, particle size, and relative particle strength (Cx = 2480 × Force / (πD^2)). Here, Force is the pressure when the particle diameter is compressed by 10%, x is 10%, D is the initial particle diameter, and Cx is the relative particle strength when the particle diameter is compressed by 10%. Ten single particles were randomly tested, and the relative strength values ​​of the ten particles were obtained. The average value was taken as the relative particle strength of the sample.

[0143] (7) Test of carbon content in negative electrode material:

[0144] Using a Bruker / Elter G4 ICARUS HF / CS-i infrared carbon-sulfur analyzer, the sample was burned in a high-temperature, oxygen-rich environment. The carbon contained in the sample was oxidized into carbon dioxide, which then entered the infrared detector along with the carrier gas. The carbon content was quantitatively calculated by statistically analyzing the changes in the intensity of the infrared absorption wavelength of the carbon dioxide signal.

[0145] (8) Test of silicon content in anode materials:

[0146] The sample was burned in an oxygen atmosphere using a Nanyang Xinyu box-type atmosphere furnace (model: SA2-9-17TP) to allow silicon and silicon suboxide in the sample to react and become silicon dioxide. After carbon combustion, it was converted into carbon dioxide and discharged. The mass content of silicon in the negative electrode material was then calculated by weighing.

[0147] (9) Test of the mass content of hydrogen and oxygen in the negative electrode material:

[0148] Hydrogen content testing method: The German Fold ONH 2000 oxygen, nitrogen and hydrogen elemental analyzer was used, and the determination of hydrogen content in steel - inert gas pulse melting thermal conductivity method GB / T223.82-2007 was adopted. The sample was wrapped in flux and melted in an inert atmosphere. The hydrogen and oxygen elements contained in the sample decomposed to form stable elemental hydrogen and oxygen. The generated hydrogen and oxygen entered the thermal conductivity detector with the carrier gas. The content of hydrogen and oxygen elements can be calculated by quantitatively statistically analyzing the change of heat in the thermal conductivity cell.

[0149] (10) Test method for the average particle size of silicon material in negative electrode material:

[0150] Nanoscale silicon materials are observed using field emission scanning electron microscopy or transmission electron microscopy. The particle size of 5-10 nanoscale silicon materials is directly measured using a scale bar, and the average particle size is taken as the final average particle size of the silicon material.

[0151] (11) Electrochemical performance testing:

[0152] A negative electrode slurry was prepared by dissolving a mixture of negative electrode material, conductive carbon black (super P), and binder (LA133) in N-methylpyrrolidone at a mass ratio of 70:15:15. This slurry was then coated onto copper foil with a thickness of d0. After drying, the copper foil was used to prepare a negative electrode sheet with a thickness of d1. A coin cell was assembled using a lithium metal sheet as the counter electrode in an argon-filled glove box. The coin cell was then charged and discharged at a current density of 0.1C within a charge-discharge range of 0.01V-5V to obtain its initial discharge specific capacity and initial coulombic efficiency (ICE).

[0153] The button cell was subjected to 50 repeated charge-discharge cycles at a current density of 1C within the charge-discharge range of 0.01V-5V. The electrode thickness d2 after 50 cycles was obtained, and the electrode expansion rate was calculated as (d2-d0) / (d1-d0)*100%.

[0154] The test results are detailed in Tables 2 and 3.

[0155] Table 2. Test results of the physicochemical properties of the negative electrode material.

[0156] Table 3. Electrochemical performance test results of the examples and comparative examples

[0157] According to the data in Tables 1 to 3, in the negative electrode materials of Examples 1 to 4, as the silicon source flux increases, the number of hydrogen atoms generated by the decomposition of the silicon source gas increases. These hydrogen atoms carry away a small amount of amorphous carbon from the carbon matrix, thus increasing the graphitization degree of the negative electrode material and decreasing its P-value. With further increases in silicon source flux, the mass content of amorphous silicon in the negative electrode material also increases, leading to a higher S-value, a gradually increasing specific capacity, and a gradual increase in expansion.

[0158] The negative electrode materials prepared in Examples 4 to 7, with a constant silicon source flux, showed an increase in hydrogen atoms generated by silicon source gas decomposition with increasing deposition time. These hydrogen atoms carried away a small amount of amorphous carbon from the carbon matrix, leading to an increase in the graphitization degree of the negative electrode material and a decrease in its P-value. With increasing deposition time, the silicon content of the negative electrode material also increased, resulting in a higher S-value, a gradually increasing specific capacity, and a gradually increasing expansion.

[0159] The anode materials prepared in Examples 7 to 10, with constant silicon source flux and deposition time, show improved performance with increasing hydrogen flux. High-temperature hydrogen flux removes weak bonds and unbonded silicon atoms from amorphous silicon, retaining stronger Si-Si bonds, which facilitates crystalline silicon nucleation and formation. This results in increased crystalline silicon content, decreased S-value, and improved relative particle strength in the anode material. Consequently, the specific capacity and initial coulombic efficiency of the anode material remain at a relatively high level.

[0160] The anode materials prepared in Examples 10 to 12, with constant silicon source flow rate, deposition time, and hydrogen flow rate, show that as the crystalline silicon growth time increases, the high temperature of hydrogen can remove weak bonds and unbonded silicon atoms in amorphous silicon, retaining stronger Si-Si bonds, which is beneficial for crystalline silicon nucleation and formation. Furthermore, since the growth temperature of crystalline silicon is higher than that of amorphous silicon, the graphitization degree of the carbon matrix is ​​increased under higher growth temperature conditions, further reducing the P-value of the anode material. The crystalline silicon content in the silicon material of the anode material is further increased, the S-value decreases, the relative particle strength of the anode material increases, and the expansion effect of the anode material decreases. Due to the decrease in the P-value, the graphitization degree of the anode material increases, and the powder conductivity of the anode material increases, which is beneficial for reducing the expansion rate of the anode material and improving the initial coulombic efficiency.

[0161] Examples 15 and 16 use silicon precursor and carbon matrix to composite. The resulting anode material can meet the following conditions: 0.9 < P < 1.2, 1.05 < S < 1.25. The anode material can have high capacity, low expansion and better first coulomb efficiency.

[0162] Compared to Comparative Example 1 and Example 1, the negative electrode material was not prepared without the introduction of hydrogen gas and the growth of crystalline silicon. This resulted in the negative electrode material not undergoing a high-temperature treatment process for crystalline silicon, leading to insufficient graphitization of the carbon matrix. The excessively high P value further resulted in insufficient conductivity of the negative electrode material and a decrease in the initial coulombic efficiency. Additionally, the silicon material in the negative electrode material was mostly amorphous silicon, and the excessively high S value resulted in a loose amorphous silicon structure, reducing the relative particle strength of the negative electrode material and leading to a higher expansion rate. This loose structure also caused the formation of more solid electrolyte interphase (SEI), increasing the consumption of active lithium ions and further decreasing the initial coulombic efficiency of the battery.

[0163] Compared with Example 7, the anode material of Comparative Example 2, under the conditions of large silicon source injection and long deposition time during the preparation process, has a higher proportion of amorphous silicon in the anode material. Although the specific capacity of the anode material is higher, the proportion of crystalline silicon is small, the S value is too large, the amorphous silicon structure in the anode material is loose, the relative particle strength of the anode material decreases, resulting in a higher expansion rate. The loose structure also causes more solid electrolyte membrane (SEI) to be formed, increasing the consumption of active lithium ions and decreasing the first coulombic efficiency of the battery.

[0164] Similarly, compared with Example 10, in the preparation process of the negative electrode material of Comparative Example 3, when the silicon source deposition time is too long, the proportion of amorphous silicon in the negative electrode material is higher. Although the specific capacity of the negative electrode material is higher, the proportion of crystalline silicon is less, the S value is too large, the amorphous silicon structure in the negative electrode material is loose, the P value is too small, the relative particle strength of the negative electrode material decreases, resulting in a higher expansion rate. The loose structure also causes more solid electrolyte membrane (SEI) to be generated, the consumption of active lithium ions increases, and the first coulombic efficiency of the battery decreases.

[0165] Compared to Example 1, Comparative Example 4's anode material underwent excessive hydrogen injection and prolonged crystalline silicon growth during preparation. This resulted in an increased content of crystalline silicon relative to amorphous silicon in the silicon material, a low S-value, and the removal of highly active amorphous silicon by hydrogen, leading to a decrease in the anode material's capacity. Although the relative particle strength of the anode material was significantly improved, the high expansion effect of crystalline silicon increased the expansion rate of the anode sheet. Excessive removal of amorphous silicon by hydrogen left vacancies, resulting in a larger specific surface area, exacerbated side reactions, and increased consumption of active lithium ions. Furthermore, the prolonged crystalline silicon growth time led to excessive graphitization of the carbon matrix, a low P-value, and pore collapse of the carbon matrix, resulting in a decrease in the anode material's capacity and initial coulombic efficiency.

[0166] Compared to Example 12, in Comparative Example 5, the excessive hydrogen injection and prolonged crystalline silicon growth time during the preparation of the anode material resulted in a further increase in the crystalline silicon content, a low S-value, and the removal of highly active amorphous silicon by hydrogen, leading to a decrease in the anode material's capacity. Although the relative particle strength of the anode material was significantly improved, the high expansion effect of crystalline silicon increased the expansion rate of the anode sheet. Excessive removal of amorphous silicon by hydrogen left vacancies, resulting in a larger specific surface area, exacerbated side reactions, and increased consumption of active lithium ions. Furthermore, the prolonged crystalline silicon growth time led to excessive graphitization of the carbon matrix, a low P-value, and pore collapse of the carbon matrix, resulting in a decrease in the anode material's capacity and initial coulombic efficiency.

[0167] Compared with Example 7, in Comparative Example 6, the carbonization temperature of the carbon precursor was too high during the preparation process, resulting in a decrease in the oxygen and hydrogen content in the prepared anode material. The carbon precursor was not easily activated, and the silicon content deposited in the carbon matrix decreased during silicon deposition. When less silicon was reduced, the proportion of crystalline silicon formed increased. Although the relative particle strength of the anode material increased, the excessively high proportion of crystalline silicon led to an increase in the expansion rate of the anode material, a decrease in the initial coulombic efficiency, and a decrease in the specific capacity.

[0168] Figure 2 shows the Raman spectra of the anode materials prepared in some embodiments and comparative examples. As shown in Figure 2, Comparative Example 1 has an excessively high amorphous silicon content, resulting in a high S value; Comparative Example 4 has an excessively high crystalline silicon content, resulting in a low S value. Example 7 has a suitable S value, and the silicon material in the anode material achieves a balance between the content of crystalline silicon and amorphous silicon. This allows for the utilization of the high capacity and low expansion properties of amorphous silicon to reduce the expansion rate of the anode material, while also utilizing the high particle strength characteristics of crystalline silicon to improve the structural strength of the anode material.

[0169] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A negative electrode material, characterized in that, The negative electrode material includes a carbon matrix and a silicon material, with at least a portion of the silicon material located within the carbon matrix; Raman spectroscopy was performed on N randomly selected sites on the particles of the negative electrode material. The results showed that the negative electrode material exhibited Raman spectroscopy at a depth of 1342±10 cm⁻¹. -1 It has the first characteristic peak at 1595±10 cm. -1 It has a second characteristic peak at 480±10 cm. -1 It has a third characteristic peak at 517±10 cm. -1 The location has a fourth characteristic peak; wherein, the average value of the peak intensity ratio I1 / I2 of the first characteristic peak and the second characteristic peak measured at N sites is P, and the average value of the peak intensity ratio I3 / I4 of the third characteristic peak and the fourth characteristic peak measured at N sites is S. The negative electrode material satisfies the following conditions: 0.9 < P < 1.2, 1.05 < S < 1.25, N ≥ 10.

2. The negative electrode material according to claim 1, characterized in that, The negative electrode material satisfies at least one of the following conditions: (1) P is 0.91, 0.92, 0.95, 1.0, 1.05, 1.08, 1.09, 1.1, 1.15, 1.16, 1.18, 1.19, 1.195 or any value within the range of any two of the above values; (2)0.91≤P≤1.18； (3) S can be 1.051, 1.06, 1.07, 1.08, 1.09, 1.1, 1.15, 1.2, 1.21, 1.22, 1.23, 1.249 or any value within the range of any two of the above values; (4)1.06≤S≤1.24。 3. The negative electrode material according to claim 1, characterized in that, The relative particle strength of the negative electrode material is 110 MPa to 150 MPa.

4. The negative electrode material according to claim 1, characterized in that, The average particle size of the silicon material is 1 nm to 100 nm; and / or, the silicon material includes crystalline silicon and amorphous silicon.

5. The negative electrode material according to claim 1, characterized in that, The carbon matrix includes amorphous carbon and graphitized carbon.

6. The negative electrode material according to any one of claims 1 to 4, characterized in that, The negative electrode material has a powder conductivity of 0.1 S / cm to 3 S / cm under a pressure of 20 kN.

7. The negative electrode material according to any one of claims 1 to 4, characterized in that, The pore volume of the negative electrode material is ≤0.1cm. 3 / g.

8. The negative electrode material according to any one of claims 1 to 4, characterized in that, The silicon content in the negative electrode material is 35% to 65% by mass.

9. The negative electrode material according to any one of claims 1 to 4, characterized in that, The mass content of hydrogen in the negative electrode material is <1%; and / or, the mass content of oxygen in the negative electrode material is 0.05% to 2.0%.

10. The negative electrode material according to any one of claims 1 to 4, characterized in that, The carbon content in the negative electrode material is 30% to 63% by mass.

11. The negative electrode material according to any one of claims 1 to 4, characterized in that, The specific surface area of ​​the negative electrode material is ≤10m² 2 / g.

12. The negative electrode material according to any one of claims 1 to 4, characterized in that, The specific capacity of the negative electrode material is 1800mAh / g to 2500mAh / g.

13. The negative electrode material according to any one of claims 1 to 4, characterized in that, The median particle size D50 of the negative electrode material satisfies: 5μm < D 50 <20μm.

Images