Negative electrode material, manufacturing method thereof, and lithium ion battery

Abstract

The present application relates to the technical field of negative electrode materials, and in particular to a negative electrode material and a manufacturing method thereof, and a lithium ion battery. The present application relates to an anode material, a manufacturing method thereof, and a lithium ion battery, the anode material including a silicon-based material core and a first coating layer coated on at least a part of the surface of the silicon-based material core, the first coating layer having a waviness y in the range of 1≧y≧0.10, the waviness y of the first coating layer being represented by formula (I): [0010] TIFF2024517543000008.tif14157, of which R max is the maximum thickness (nm) of the first coating layer, Rmin is the minimum thickness (nm) of the first coating layer, D50 is the median diameter (μm) of the negative electrode material, and C is the mass ratio (%) of the first coating layer to the negative electrode material. The negative electrode material of the present application has excellent conductivity, cycling performance, and magnification performance, and can suppress the occurrence of irreversible expansion.

Description

[Technical Field]

[0001] This application claims priority from a Chinese patent application filed with the China Patent Office on April 22, 2022, bearing application number 2022104320997 and entitled "Negative electrode material and manufacturing method thereof, and lithium ion battery," the entire contents of which are incorporated herein by reference. The present application relates to the technical field of negative electrode materials, and in particular to a negative electrode material and a method for producing the same, and to a lithium ion battery. [Background technology]

[0002] As an anode material for lithium-ion batteries, silicon oxide materials have several problems to solve, including swelling and low expansion rate due to the natural defects of silicon-based materials. The expansion problem of silicon oxide materials is mainly due to the following: the silicon oxide material's large amount of lithium absorption causes volume expansion, and the lithium absorption and release causes a huge volume change difference, destroying the SEI film on the surface of the silicon oxide material, exposing the active surface to the electrolyte again, resulting in the decomposition and consumption of the electrolyte, the re-deposition of the SEI, and the gradual expansion of the electrode. The expansion problem is due to the lithium ions entering the silicon oxide system, where the internal migration efficiency is much lower than that of graphite interlayer migration. At the same time, lithium absorption and internal migration in the silicon oxide system causes internal migration, which changes the lithium content, resulting in a change in the crystalline phase and a low lithium diffusion ability.

[0003] Therefore, there is currently an urgent need for a negative electrode material that has low expansion and high expansion capacity. Summary of the Invention [Problem to be solved by the invention]

[0004] The present application aims to provide a negative electrode material, a manufacturing method thereof, and a lithium-ion battery, which can effectively suppress expansion and improve the lithium absorption efficiency and depth, thereby significantly improving the powder conductivity, rechargeability, and cycling performance of the negative electrode material. [Means for solving the problem]

[0005] In a first aspect, an embodiment of the present application provides a negative electrode material, the negative electrode material including a core made of a silicon-based material and a first coating layer coated on at least a surface of the core, wherein the range of a waviness y of the first coating layer is 1≧y≧0.10, and the waviness y of the first coating layer is represented by formula (I):

number

[0006] In some embodiments, the negative electrode material has at least one of the following characteristics (1) to (7): (1) The silicon-based material core includes crystalline silicon and silicide, and the silicide includes at least one of SiOx, silica, silicate, and silicon alloy, where 1.5≧x≧0.5. (2) The silicon-based material core includes crystalline silicon and silicide, and the silicide includes at least one of SiOx, silica, silicate, and silicon alloy, among which 1.5≧x≧0.5, and the grain size D of the crystalline silicon Si is 2.5 nm to 15 nm. (3) The silicon-based material core includes crystalline silicon and silicide, and the silicide includes at least one of SiOx, silica, silicate, and silicon alloy, where 1.5≧x≧0.5, and the grain size of the crystalline silicon is D Si The crystal grain size of the silicate is D silicate, and D silicate / D Si =0.3~5.0. (4) The silicon-based material core includes crystalline silicon and silicide, and the silicide includes at least one of SiOx, silica, silicate, and silicon alloy, where 1.5≧x≧0.5, and the grain size of the crystalline silicon is D Si The crystal grain size of the silicon alloy is D silicon alloy, and D silicon alloy / D Si =0~2.0. (5) The silicon-based material core comprises crystalline silicon and a silicide, the silicide comprising at least one of SiOx, silica, silicate and silicon alloy, wherein 1.5≧x≧0.5, and the silicon alloy comprising at least one of silicon-iron alloy, silicon-silver alloy, silicon-nickel alloy, silicon-cobalt alloy, silicon-manganese alloy, silicon-indium alloy, silicon-rhodium alloy, silicon-ruthenium alloy, silicon-iridium alloy, silicon-platinum alloy, silicon-titanium alloy and silicon-molybdenum alloy. (6) The silicon-based material core comprises crystalline silicon and a silicide, the silicide comprising at least one of SiOx, silica, silicate and silicon alloy, wherein 1.5≧x≧0.5, and the cation of the silicate comprises a metal element. (7) The median diameter of the core of the silicon-based material is 1 μm to 13 μm.

[0007] In some embodiments, the negative electrode material includes at least one of the following characteristics (1) to (8): (1) The first coating layer includes a carbon layer, and the material of the carbon layer includes at least one of amorphous carbon, graphite, soft carbon, and hard carbon. (2) The material of the organic polymer material layer includes at least one of a polyamine compound, a polyester compound, and a polyene compound. (3) The surface shape of the first coating layer includes at least one of a petal shape, a stripe shape, a tapered shape, and a particulate shape. (4) The thickness of the first coating layer is 10 nm to 500 nm. (5) The first coating layer has pores, and the pore diameter of the pores is 10 nm to 60 nm. (6) The porosity of the first coating layer is 0.5% to 15%. (7) The silicon-based material core includes a first doping element, and the first doping element includes at least one of lithium, magnesium, sodium, copper, platinum, iron, manganese, cobalt, nickel, indium, silver, gold, titanium, molybdenum, aluminum, palladium, calcium, iridium, chromium, gallium, rhodium, and ruthenium. (8) The first coating layer contains a second doping element, and the second doping element contains at least one of nitrogen, fluorine, phosphorus, sulfur, and boron.

[0008] In some embodiments, a second coating layer is further provided between the silicon-based material core and the first coating layer.

[0009] In some embodiments, the second coating layer has at least one of the following characteristics (1) to (3). (1) The material of the second coating layer includes a silicon alloy. (2) The material of the second coating layer contains a silicon alloy, and the silicon alloy contains at least one of a ferrosilicon alloy, a silver-silicon alloy, a nickel-silicon alloy, a cobalt-silicon alloy, a manganese-silicon alloy, an indium-silicon alloy, a rhodium-silicon alloy, a ruthenium-silicon alloy, an iridium-silicon alloy, a platinum-silicon alloy, a titanium-silicon alloy, and a molybdenum-silicon alloy. (3) The thickness of the second coating layer is 0 nm to 10 nm (excluding 0).

[0010] In some embodiments, the negative electrode material includes at least one of the following features (1) to (5). (1) In the Raman imaging measured by the Raman spectrum of the negative electrode material, the ratio of the maximum peak intensity I1 at 1300 cm -1 ~1400 cm -1 of the negative electrode material to the maximum peak intensity I2 at 1550 cm -1 ~1650 cm -1 of the negative electrode material satisfies 0 < I1 / I2 < 3, and the ratio of the maximum peak intensity I3 at 480 cm -1 ~540 cm -1 of the negative electrode material to the maximum peak intensity I1 at 1300 cm -1 ~1400 cm -1 of the negative electrode material satisfies 1 < I3 / I1 < 4.5. (2) The median diameter D50 of the negative electrode material is 1.5 μm to 15 μm. (3) The carbon content of the negative electrode material is 0.5% to 10%. (4) The powder conductivity of the negative electrode material is 0.1 S / m to 100 S / m.​​​​​​​​​​​​​​

[0012] In some embodiments, the manufacturing method includes at least one of the following features (1) to (7). (1) The organic carbon source contains at least one organic substance selected from the group consisting of alkenes, alkynes, alkanes, alcohols, carboxylic acids, esters, aromatic rings, ketones, and ethers. (2) The organic carbon source includes at least one of p-dimethylbiphenyl, polyacrylic acid, phthalocyanine, diphenyl ether, polyvinyl acetate, ethyl stearate, and dopamine. (3) The organic carbon source includes at least one organic substance selected from the group consisting of nitriles, amines, nitro compounds, sulfides, fluorides, borides, and phosphides, which contain at least one of a hydroxyl group, a carboxyl group, an aromatic ring, a branched alkyl group, and a carbonyl group. (4) The organic carbon source includes at least one of 5-chloro-2-ethoxybenzeneboronic acid, phenyl sulfide, dopamine, and phthalocyanine. (5) The organic carbon source includes an organic polymer material, and the organic polymer material includes at least one of a polyamine compound, a polyester compound, and a polyene compound. (6) The organic carbon source includes a metal complex. (7) The organic carbon source includes a metal complex, and the metal complex includes at least one of copper phthalocyanine, aluminum acetylacetonate, cyhexatin, and cobalt isopropoxide.

[0013] In some embodiments, the organic carbon source comprises a metal complex, and the metal complex is obtained by complexing an organic carbon material with a metal source.

[0014] In some embodiments, the method includes at least one of the following features (1) to (3): (1) The metal source includes at least one of a lithium source, a magnesium source, a sodium source, a copper source, an iron source, a manganese source, a cobalt source, a nickel source, an indium source, a silver source, a gold source, a titanium source, a molybdenum source, an aluminum source, a palladium source, a calcium source, an iridium source, a platinum source, a gallium source, a chromium source, a rhodium source, and a ruthenium source. (2) The organic carbon material includes at least one of alcohol, ether, aromatic compound, pyrrole, pyridine, alkane, ketone, carboxylic acid, nitrile, organic amine, nitro organic substance, sulfur-containing organic substance, and phosphorus-containing organic substance. (3) The molar ratio of the metal source to the organic carbon material is (0 to 1):1 (excluding 0).

[0015] In some embodiments, the method includes at least one of the following features (1) to (6): (1) The silicon-based material includes at least one of Si, SiOx, and SiO2, where 1.5≧x≧0.5. (2) The mass ratio of the silicon-based material to the organic carbon source is 1:(0.05 to 0.3). (3) The mass ratio of the silicon-based material to the organic solvent is 1:(1 to 2.5). (4) The organic solvent includes at least one of dimethyl carbonate, tetrahydrofuran, a carbonate ester, toluene, benzene, ethyl ether, propylene oxide, a ketone, and ethylene glycol dimethyl ether. (5) The organic carbon source, silicon-based material, and organic solvent are mixed under stirring conditions. (6) The organic carbon source, silicon-based material, and organic solvent are mixed for 3 hours to 24 hours.

[0016] In some embodiments, after the organic carbon source, silicon-based material, and organic solvent are mixed, the method further comprises the step of evaporating and crystallizing the mixed materials.

[0017] In some embodiments, the method includes at least one of the following features (1) to (4): (1) The temperature of the evaporated crystals is 30°C to 80°C. (2) The evaporation and crystallization time is 3 to 10 hours. (3) The evaporation and crystallization is carried out in a first protective atmosphere. (4) The evaporation and crystallization is carried out in a first protective atmosphere, and the first protective atmosphere contains at least one of argon gas and nitrogen gas.

[0018] In some embodiments, the method includes at least one of the following features (1) to (5): (1) The temperature of the heat treatment is 400°C to 1200°C. (2) The temperature rise rate in the heat treatment is 1° C. / min to 5° C. / min. (3) The heat-retaining time for the heat treatment is 3 to 12 hours. (4) The heat treatment is performed in a second protective atmosphere, and the second protective atmosphere contains argon gas. (5) The pressure of the heat treatment is 0.11 MPa to 0.25 MPa.

[0019] In a third aspect, embodiments of the present application provide a lithium-ion battery, the lithium-ion battery comprising the anode material according to the first aspect or produced by the method according to the second aspect. [Effects of the Invention]

[0020] Compared with the prior art, the present application can achieve the following beneficial effects: The first coating layer of the negative electrode material according to the present application has a certain degree of waviness, which indicates the range and space within which the conductive network in the first coating layer can expand. When the negative electrode material is made into a slurry or electrode pieces during the expansion and contraction process, the contact area between the negative electrode material and the conductive agent can be increased, maintaining the connection between the silicon-based material core and the electronic path of the conductive agent, which is helpful in improving the conductivity, cycling performance and multiplication performance of the negative electrode material, and stabilizing the SEI interface, thereby reducing pulverization, reducing the occurrence of side reactions and suppressing the occurrence of irreversible expansion.

[0021] The present application employs a method of mixing an organic carbon source, a silicon-based material, and an organic solvent. The organic carbon source is uniformly deposited on the surface of the silicon-based material in a liquid environment, followed by heat treatment to form a first coating layer with a certain degree of waviness on the surface of the core silicon-based material. This first coating layer with a certain degree of waviness provides the range and space within which the conductive network in the first coating layer can expand. This increases the contact area between the negative electrode material and the conductive agent when preparing the slurry or electrode pieces during the expansion and contraction of the negative electrode material, thereby effectively improving the conductivity, cycling performance, and expansion performance of the negative electrode material. Furthermore, the first coating layer maintains the area of influence of the first coating layer during the expansion of the negative electrode material, thereby reducing SEI breakdown and suppressing the expansion of the negative electrode material. The manufacturing method of the present application is simple, has high product consistency, and is suitable for large-scale production. Compared to negative electrode materials formed using simple carbon material coating processes, the negative electrode material of the present application has higher expansion performance, is simpler, and is less expensive. [Brief explanation of the drawings]

[0022] In order to more clearly describe the technical solutions of the embodiments of the present application or the prior art, the following briefly introduces drawings necessary for describing the embodiments or the prior art. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without any creative efforts.

[0023] [Figure 1]1 is a flowchart showing the production of a negative electrode material according to the present application. [Figure 2] 1 is an EDS map of the negative electrode material produced in Comparative Example 1. [Figure 3] 1 is an EDS map of the negative electrode material prepared in Example 1 of the present application. [Figure 4] 1 shows SEM maps of the carbon layers of the negative electrode materials produced in Examples 1, 2, 3, and 4 and Comparative Example 2. [Figure 5] 1 is an XRD chart of the negative electrode material produced in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0024] In order to better understand the technical solutions of the present application, the following detailed description of the embodiments of the present application is given with reference to the drawings.

[0025] It should be clear that the described embodiments are only some of the embodiments of the present application, but not all of the embodiments. Based on the embodiments in the present application, any other embodiments that can be made by a person skilled in the art without any creative effort fall within the scope of protection of the present application.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features, whereby a feature qualified by "first" or "second" may explicitly or implicitly include one or more of the said features.

[0027] To facilitate understanding of this application, certain terms are defined herein where appropriate. Unless otherwise defined herein, scientific and technical terms used herein have the meanings commonly understood by those skilled in the art.

[0028] The present application provides a negative electrode material, the negative electrode material including a silicon-based material core and a first coating layer coated on at least a part of the surface of the silicon-based material core, wherein the range of the waviness y of the first coating layer is 1≧y≧0.10, and the waviness y of the first coating layer is represented by formula (I).

number

[0029] In the above solution, the first coating layer of the present application has a certain degree of waviness, which indicates the range and space within which the conductive network in the first coating layer can expand. When the negative electrode material is made into a slurry or electrode piece during the expansion and contraction process, the contact area between the negative electrode material and the conductive agent can be increased, maintaining the connection between the silicon-based material core and the electronic path of the conductive agent, which is helpful in improving the conductivity, cycling performance and multiplication performance of the negative electrode material, and stabilizing the SEI interface, thereby reducing pulverization, reducing the occurrence of side reactions and suppressing the occurrence of irreversible expansion.

[0030] As can be understood, the waviness of the first coating layer refers to the ratio between the maximum thickness of the first coating layer on the surface of the negative electrode material powder and the minimum thickness of the first coating layer, after taking into account the particle size of the negative electrode material and the mass ratio of the first coating layer in the negative electrode material. The maximum thickness and the minimum thickness of the first coating layer, after taking into account the particle size of the negative electrode material and the mass ratio of the first coating layer, indicate that the larger the ratio, the greater the growth range and space of the conductive network in the first coating layer.

[0031] The value of y ranges from 0.10 to 1. As can be seen, the greater the difference in the surface morphology of the first coating layer and the more expanded spaces there are, the closer y is to 1; the smoother the surface of the first coating layer, the closer y is to 0. Specifically, the waviness y of the first coating layer may be 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 1, etc., and of course, other values within the above range are also possible and are not limited thereto. The present application controls the waviness of the first coating layer within the above range, which forms a first coating layer with a special shape that can maintain a 3D expanded shape during charging and discharging, maintain the shape during cycling, and maintain an extremely large conductive contact area, thereby improving the conductivity and multiplier performance of the negative electrode material. Preferably, the range of the waviness y is 1≧y≧0.15, more preferably 1≧y≧0.227, within the above range, the negative electrode material can achieve a very obvious improvement in the multiplier performance due to the differentiated form.

[0032] In some embodiments, the silicon-based material core comprises crystalline silicon and a silicide, wherein the silicide comprises at least one of SiOx, silica, silicates, and silicon alloys, where 1.5≧x≧0.5.

[0033] In some embodiments, the grain size D of the crystalline silicon Siis 2.5 nm to 15 nm, specifically, may be 2.5 nm, 5 nm, 7 nm, 9 nm, 10 nm, 12 nm, 15 nm, etc., and may of course be other values within the above range, and is not limited thereto. Controlling the crystal grain size of crystalline silicon within the above range helps to improve the capacity and cycling performance of the negative electrode material.

[0034] In some embodiments, the silicate grain size is D silicate, D silicate / D Si =0.3~5.0, and D silicate / D Si Specifically, it may be 0.3, 0.5, 1, 2, 3, 4, 5, etc., and may of course be other values within the above range, and is not limited thereto. Si If the ratio is greater than 5.0, the content of inactive components in the material will be high, which is unfavorable for improving the capacity. Si If is smaller than 0.3, it is disadvantageous to improve the initial efficiency of the material.

[0035] In some embodiments, the grain size of the silicon alloy is D silicon alloy, D silicon alloy / D Si = 0 to 2.0, and D silicon alloy / D Si Specifically, the ratio may be 0, 0.5, 1, 1.5, 2.0, etc., and may of course be other values within the above range, and is not limited thereto. Controlling the grain size of the silicon alloy and crystalline silicon within the above range helps to improve the material circulation performance, and the ratio of the D silicon alloy / D Si When the value is greater than 2.0, the capacity of the material decreases. Si When is 0, it indicates that the silicon-based material core does not contain silicon alloy.

[0036] In some embodiments, the silicon alloy includes at least one of a silicon-iron alloy, a silicon-silver alloy, a silicon-nickel alloy, a silicon-cobalt alloy, a silicon-manganese alloy, a silicon-indium alloy, a silicon-rhodium alloy, a silicon-ruthenium alloy, a silicon-iridium alloy, a silicon-platinum alloy, a silicon-titanium alloy, and a silicon-molybdenum alloy. The presence of the silicon alloy increases the number of phases in the core of the silicon-based material, increasing the area of the interface between each phase, reducing the diffusion resistance of lithium ions and thereby improving the material's multiplication performance. The presence of the silicon alloy can also inhibit the expansion of the core of the silicon-based material to a certain extent, thereby improving the material's cycling performance.

[0037] In some embodiments, the cation of the silicate includes a metal element, and specifically, the silicate may be, for example, lithium silicate, magnesium silicate, sodium silicate, etc. The silicate core containing a metal element can reduce the effect of oxygen on lithium in the finished battery, reduce the generation of dead lithium, and improve the initial efficiency of the material.

[0038] In some embodiments, the median diameter of the silicon-based material core is 1 μm to 13 μm, and the median diameter of the silicon-based material core may be, for example, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, etc., and of course may be other values within the above range and is not limited thereto.

[0039] In some embodiments, the first coating layer includes a carbon layer, and the material of the carbon layer includes at least one of amorphous carbon, graphite, soft carbon, and hard carbon.

[0040] In some embodiments, the surface morphology of the first coating layer includes at least one of petal-like, striped, tapered, and particulate, and the irregular morphology of the first coating layer can extend the working range of the conductive carbon and maintain connection with the conductive network during cycling as a negative electrode material, thereby improving the cycling performance of the material.

[0041] In some embodiments, the thickness of the first coating layer is 10 nm to 500 nm, and the thickness of the first coating layer may be, for example, 10 nm, 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, etc., and of course, may be other values within the above range and is not limited thereto.

[0042] In some embodiments, the first coating layer has voids, and the presence of voids can improve the penetration depth of the electrolyte and shorten the diffusion path of lithium ions, thereby improving the multiplier performance of the material.

[0043] In some embodiments, the pore size of the voids is 10 nm to 60 nm, and the pore size of the voids may be specifically 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, etc., and of course may be other values within the above range and is not limited here.

[0044] In some embodiments, the porosity of the first coating layer is 0.5% to 15%, and the porosity of the first coating layer may be 0.5%, 1%, 2%, 5%, 8%, 10%, 12%, and 15%, etc., and of course may be other values within the above range and is not limited thereto.

[0045] In some embodiments, the core of the silicon-based material comprises a first doping element, the first doping element comprising at least one of lithium, magnesium, sodium, copper, iron, manganese, cobalt, nickel, indium, silver, gold, titanium, molybdenum, aluminum, palladium, calcium, iridium, platinum, chromium, gallium, rhodium, and ruthenium, and the presence of the doping element can improve the electronic structure of the core of the silicon-based material, improve the electrical conductivity of the core of the silicon-based material, improve the multiplication performance of the negative electrode material, and improve the deep lithium storage capacity of the negative electrode material.

[0046] In some embodiments, the first coating layer comprises a second doping element, which comprises at least one of nitrogen, fluorine, phosphorus, sulfur, and boron. The addition of the second doping element can further improve the conductivity of the first coating layer, improve the contact area between the material and the conductive network, and further improve the cyclability of the material.

[0047] As can be seen, the negative electrode material contains the first doping element and / or the second doping element, which helps the first coating layer to have a higher content and a larger residue amount, and the silicon-based material core to be enveloped by the first coating layer.

[0048] In some embodiments, a second coating layer is further provided between the silicon-based material core and the first coating layer.

[0049] In some embodiments, the material of the second coating layer includes a silicon alloy. The second coating layer has high conductivity and is coated on the surface of the silicon-based material core to achieve a bridging effect with the silicon-based material core, and becomes the end of the conductive network of the silicon-based material core, improving the conductivity of the silicon-based material core, further improving the conductivity of the negative electrode material, and ultimately improving the rate performance and lithium intercalation depth of the negative electrode material. Also, the presence of the second coating layer can restrain the expansion of the silicon-based core material to a certain extent, thereby further limiting the expansion of the lithium intercalated, and improving the cycle performance of the material.

[0050] In some embodiments, the silicon alloy includes at least one of silicon-iron alloy, silicon-silver alloy, silicon-nickel alloy, silicon-cobalt alloy, silicon-manganese alloy, silicon-indium alloy, silicon-rhodium alloy, silicon-ruthenium alloy, silicon-iridium alloy, silicon-platinum alloy, silicon-titanium alloy, and silicon-molybdenum alloy.

[0051] In some embodiments, the thickness of the second coating layer is 0 to 10 nm (excluding 0), and the specific thickness of the second coating layer may be 0.1 nm, 0.5 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, etc., and of course other values within the above range are also possible and are not limited here.

[0052] In some embodiments, in the Raman imaging measured by the Raman spectrum of the negative electrode material, the ratio of the maximum peak intensity I1 of the negative electrode material at 1300 cm -1 ~1400 cm -1 to the maximum peak intensity I2 of the negative electrode material at 1550 cm -1 ~1650 cm -1 satisfies 0 < I1 / I2 < 3. Specifically, I1 / I2 may be, for example, 0.05, 0.1, 0.5, 1, 2, and 2.5, etc., and of course other values within the above range are also possible and are not limited here. And the negative electrode material at 480 cm -1 ~540 cm-1 The maximum peak intensity I3 and 1300 cm of the negative electrode material -1 ~1400 cm -1 The ratio of the maximum peak intensity I1 satisfies 1 < I3 / I1 < 4.5, and I3 / I1 may be, for example, 1.2, 1.5, 1.8, 2, 2.5, 2.8, 3.2, 3.5, 3.8, 4.0, and 4.3, etc., and of course other values within the above range may also be possible and are not limited here. The above peak intensity relational expression is used to determine the distribution of the carbon component in the material. By controlling I1 / I2 and I3 / I1 within the above range, a preferable carbon coating effect can be obtained, which helps to improve the conductivity of the material.

[0053] In some embodiments, in the Raman imaging measured by the Raman spectrum of the negative electrode material, at 1350 cm of the negative electrode material -1 The peak intensity I 1350 And at 1580 cm -1 The intensity I of the peak 1580 The ratio with is 0 < I 1350 / I 1580 < 3 is satisfied, and at 510 cm of the negative electrode material -1 The peak intensity I 510 And at 1350 cm -1 The peak intensity I 1350 The ratio with is 1 < I 510 / I 1350 < 4.5 is satisfied.

[0054] In some embodiments, the median diameter D50 of the negative electrode material is 1.5 μm to 15 μm, and the median diameter of the negative electrode material may be, for example, 1.5 μm, 3 μm, 5 μm, 10 μm, 12 μm, 13 μm, 14 μm, and 15 μm, etc., and of course other values within the above range may also be possible and are not limited here. Controlling the median diameter D50 of the negative electrode material within the above range indicates that the coating layer of the negative electrode material is complete, has high reproducibility, and has high conductivity of the coating layer.

[0055] In some embodiments, the carbon content of the negative electrode material is 0.5% to 10%, and the carbon content of the negative electrode material may be, for example, 0.5%, 1%, 2%, 3%, 5%, 7%, 8%, 10%, etc., and of course, other values within the above ranges are also possible and are not limited thereto.

[0056] In some embodiments, the powder conductivity of the negative electrode material is 0.1 S / m to 100 S / m, and the powder conductivity of the negative electrode material may be, for example, 0.1 S / m, 1 S / m, 5 S / m, 10 S / m, 20 S / m, 30 S / m, 50 S / m, 60 S / m, 70 S / m, 80 S / m, 90 S / m, and 100 S / m, and of course, other values within the above ranges may also be used and are not limited thereto.

[0057] In some embodiments, the specific surface area of the negative electrode material is 0.8 m 2 / g~10m 2 / g, and the specific surface area of the negative electrode material is, for example, 0.8 m 2 / g, 1m 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 and 10m 2 / g, etc., and of course other values within the above ranges are also possible, and are not limited thereto.

[0058] The embodiments of the present application further provide a method for producing a negative electrode material, Step S100: Mixing an organic carbon source, a silicon-based material, and an organic solvent to obtain a precursor; and step S200 of heat-treating the precursor to obtain a negative electrode material.

[0059] In the above technical solution, the present application employs a method of mixing an organic carbon source, a silicon-based material, and an organic solvent. The organic carbon source is uniformly deposited on the surface of the silicon-based material in a liquid environment, followed by heat treatment to form a first coating layer with a certain degree of waviness on the surface of the core silicon-based material. This first coating layer with a certain degree of waviness provides the range and space within which the conductive network in the first coating layer can expand. This ensures an increased contact area between the negative electrode material and the conductive agent when producing the slurry or electrode pieces during the expansion and contraction of the negative electrode material, thereby effectively improving the conductivity, cycling performance, and expansion performance of the negative electrode material. Furthermore, the first coating layer maintains the area of influence of the first coating layer during the expansion of the negative electrode material, thereby reducing SEI breakdown and suppressing the expansion of the negative electrode material. The manufacturing method of the present application is simple, has high product consistency, and is suitable for large-scale production. Compared to negative electrode materials formed using a simple carbon material coating process, the negative electrode material of the present application has higher expansion performance, is simpler, and is less expensive.

[0060] The manufacturing method of the present application will be specifically described below with reference to examples. As shown in FIG. 2, the manufacturing method of the negative electrode material of the present application includes the following steps: In step S100, an organic carbon source, a silicon-based material, and an organic solvent are mixed to obtain a precursor.

[0061] In some embodiments, the organic carbon source can be first dispersed in an organic solvent, and then the silicon-based material can be added, which helps in uniform dispersion of the organic carbon source.

[0062] In some embodiments, the organic carbon source comprises at least one organic substance selected from the group consisting of alkenes, alkynes, alkanes, alcohols, carboxylic acids, esters, aromatic rings, ketones, and ethers, which not only have a certain crystalline form but also can be dissolved in an organic solvent. The present application uses organic carbon sources with different organic terminal functional groups, which adsorb onto the surface of the silicon-based material and deposit on the surface of the silicon-based material to form the original carbon layer skeleton of the surface coating layer. The organic carbon source may be, for example, p-dimethylbiphenyl, polyacrylic acid, phthalocyanine, diphenyl ether, polyvinyl acetate, ethyl stearate, dopamine, etc.

[0063] In some embodiments, the organic carbon source includes at least one organic compound selected from the group consisting of nitriles, amines, nitro compounds, sulfides, fluorides, borides, and phosphides containing at least one of a hydroxyl group, a carboxyl group, an aromatic ring, an alkyl branched chain, and a carbonyl group, and the presence of the organic compound can improve the electrical conductivity of the material. Examples of the organic carbon source include 5-chloro-2-ethoxybenzeneboronic acid, phenyl sulfide, dopamine, and phthalocyanine.

[0064] In some embodiments, the organic carbon source comprises an organic polymer material, the organic polymer material comprising at least one of a polyamine-based compound, a polyester-based compound, and a polyene-based compound. Exemplary organic polymer materials include polyvinyl chloride, polydopamine, and polyethylene terephthalate, and the presence of the organic matter can improve the electrical conductivity of the material.

[0065] In some embodiments, the organic carbon source includes a metal complex, the metal complex including at least one of copper phthalocyanine, aluminum acetylacetonate, cyclohexatin, and cobalt isopropoxide; of course, other metal complexes can be selected. As can be understood, in organic carbon sources employing metal complexes, the produced negative electrode material is doped with the metal element, which can effectively prevent material particles from being pulverized.

[0066] In some embodiments, the metal complex can be obtained by further complexing the organic carbon material with a metal source.

[0067] The special morphology of the first coating layer of the present application can be better formed by combining and stacking appropriate metal-organic carbon sources (metal moieties-organic moieties) during the synthesis process, and the applicant has determined that y=1-exp(-(R max -R min We discovered that the above-mentioned lamination level can be explained using the formula (D50 / D50*C) and the extent to which it can have the effect of expanding the conductive area.

[0068] In some embodiments, the metal source includes at least one of a lithium source, a magnesium source, a sodium source, a copper source, an iron source, a manganese source, a cobalt source, a nickel source, an indium source, a silver source, a gold source, a titanium source, a molybdenum source, an aluminum source, a palladium source, a calcium source, an iridium source, a platinum source, a gallium source, a chromium source, a rhodium source, and a ruthenium source, and the metal source may be, for example, metallic lithium, metallic magnesium, metallic copper, etc. As can be seen, metals with different activities have different effects on the waviness y of the first coating layer, and the applicant has discovered that the greater the activity of the metal and the greater the waviness y value of the first coating layer, the more the conductivity, cycling performance, and multiplication performance of the negative electrode material can be improved.

[0069] In some embodiments, the organic carbon material comprises at least one of an alcohol, an ether, an aromatic compound, a pyrrole, a pyridine, an alkane, a ketone, a carboxylic acid, a nitrile, an organic amine, a nitroorganic, a sulfur-containing organic, and a phosphorus-containing organic. As can be appreciated, the organic carbon material may be the same as the organic carbon source described above.

[0070] In some embodiments, the molar ratio of the metal source to the organic carbon material is (0-1):1 (not including 0). Specifically, the molar ratio of the metal source to the organic carbon material may be 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, etc., and may be other values within the above range, without limitation. Controlling the molar ratio of the metal source to the organic carbon material within the above range helps to ensure sufficient complexation of the metal with the organic carbon material, thereby improving the deposition yield of the organic carbon material and preventing excessive metal impurities from remaining in the organic carbon material.

[0071] In some embodiments, the silicon-based material includes at least one of Si, SiOx, and SiO2, where 1.5≧x≧0.5.

[0072] In some embodiments, the mass ratio of the silicon-based material to the organic carbon source is 1:(0.05-0.3), and the mass ratio of the silicon-based material to the organic carbon source may be, for example, 1:0.05, 1:0.1, 1:0.2, 1:0.3, etc., and of course may be other values within the above range, and is not limited thereto.

[0073] In some embodiments, the mass ratio of the silicon-based material to the organic solvent is 1:(1 to 2.5), and the mass ratio of the silicon-based material to the organic solvent may be, for example, 1:1, 1:1.5, 1:2, 1:2.5, etc., and of course, other values within the above range may also be used, and are not limited thereto.

[0074] In some embodiments, the organic solvent comprises at least one of dimethyl carbonate, tetrahydrofuran, a carbonate ester, toluene, benzene, ethyl ether, propylene oxide, a ketone, and ethylene glycol dimethyl ether.

[0075] In some embodiments, the mixing time of the organic carbon source, the silicon-based material, and the organic solvent is 3 hours to 24 hours, and specifically, the mixing time may be, for example, 3 hours, 4 hours, 5 hours, 7 hours, 8 hours, 10 hours, 12 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, etc., and of course, other values within the above range may also be used, and are not limited thereto. Within the above mixing time, the organic carbon source can be saturated and adsorbed onto the surface of the silicon-based material.

[0076] In some embodiments, the organic carbon source, the silicon-based material, and the organic solvent are mixed under stirring, and the purpose of the stirring is to uniformly disperse the silicon-based material and prevent it from depositing at the bottom of the organic solvent. The present application does not limit the stirring method, and may be, for example, magnetic stirring, stirring paddle stirring, etc.

[0077] In some embodiments, the method further comprises the step of evaporative crystallization of the mixed material after mixing the organic carbon source, silicon-based material, and organic solvent. Specifically, the organic carbon source, silicon-based material, and organic solvent are mixed and reacted under stirring for 3 to 24 hours, and then evaporative crystallization is performed after the reaction to obtain the precursor. The purpose of evaporative crystallization is to remove the remaining organic solvent, and the evaporative crystallization process is performed based on different organic solvents.

[0078] In some embodiments, the evaporative crystallization temperature is 30°C to 80°C, and may be, for example, 30°C, 40°C, 50°C, 60°C, 70°C, or 80°C, and may naturally be other values within the above range and is not limited thereto. Preferably, the evaporative crystallization is achieved by employing a segmented heating method, which evaporates a portion of the solvent and deposits the organic carbon source regularly on the material surface, which helps to form the surface morphology of the first coating layer in the subsequent heat treatment process.

[0079] In some embodiments, the time for evaporative crystallization is 3 hours to 10 hours, and the time for evaporative crystallization may be, for example, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, and 10 hours, and of course, may be other values within the above range and is not limited thereto.

[0080] In some embodiments, the evaporative crystallization is performed in a first protective atmosphere, and the first protective atmosphere includes at least one of argon gas and nitrogen gas.

[0081] In some embodiments, evaporative crystallization is carried out under agitation, and continuous agitation during the evaporative crystallization process aids in uniform deposition adsorption of the solute.

[0082] In this application, an organic carbon source, a silicon-based material, and an organic solvent are mixed together, and through an effective crystallization and stirring process, a crystalline skeleton is formed on the organic surface, thereby obtaining a precursor of the target material.

[0083] Step S200: heat-treating the precursor to obtain a negative electrode material.

[0084] In the above step, during the heat treatment process, the organic carbon source is deposited on the surface of the silicon-based material, and after heat treatment, a first coating layer is formed. Depending on the selection of raw materials and heat treatment, the first coating layer after heat treatment can have a special shape (petal-like, striped, tapered, particulate, etc.) and a porous structure, which can increase the contact area between the core of the silicon-based material and the conductive network, and further improve the conductivity.

[0085] In some embodiments, the heat treatment of the present application can form a coating layer with a special morphology, and compared to the flat surface produced by conventional chemical vapor deposition coatings, the present application is a carbon layer grown from an organic carbon source, whose surface morphology is not regular, and may be at least one of petal-like, striped, tapered, and granular.

[0086] In some embodiments, the heat treatment temperature is 400°C to 1200°C, and the heat treatment temperature may be, for example, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C, or 1200°C, and may be other values within the above range, and is not limited thereto. If the heat treatment temperature is lower than 400°C, the heat treatment will be incomplete, the bonding strength between the organic molecules will be weak, and the carbon layer will be fragile and easily destroyed. If the heat treatment temperature is higher than 1200°C, the core will change, the uniformity of each component of the core will be destroyed, the conductivity of the core will decrease, and the initial efficiency will decrease.

[0087] In some embodiments, the temperature rise rate of the heat treatment is 1°C / min to 5°C / min, and the temperature rise rate of the heat treatment may be, for example, 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, etc., and may of course be other values within the above range and is not limited thereto.

[0088] In some embodiments, the incubation time for the heat treatment is 3 hours to 12 hours, and may be, for example, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, and 12 hours, etc., and of course, may be other values within the above range and is not limited thereto.

[0089] In some embodiments, the heat treatment is performed under pressure, and the pressure of the heat treatment is 0.11 MPa to 0.25 MPa. Specifically, the pressure of the heat treatment may be 0.11 MPa, 0.15 MPa, 0.17 MPa, 0.2 MPa, 0.23 MPa, 0.25 MPa, etc., and of course, may be other values within the above range, and is not limited thereto.

[0090] In some embodiments, the second protective atmosphere is selected as a protective gas that does not react with the organic carbon source, the heat treatment is performed in the second protective atmosphere, and the second protective atmosphere includes argon gas.

[0091] In the present application, the structures of the negative electrode materials obtained by heat treating different raw materials are different, specifically, When the selected organic carbon source contains at least one organic substance selected from the group consisting of alkenes, alkynes, alkanes, alcohols, carboxylic acids, esters, aromatic rings, ketones, and ethers, the negative electrode material obtained by the heat treatment process includes a silicon-based material core and a carbon layer coated on the silicon-based material core.

[0092] The selected organic carbon source includes at least one organic substance selected from the group consisting of nitriles, amines, nitro compounds, sulfides, fluorides, borides, and phosphides, which contain at least one of a hydroxyl group, a carboxyl group, an aromatic ring, an alkyl branched chain, and a carbonyl group, or at least one organic substance selected from the group consisting of polyamine compounds, polyester compounds, and polyene compounds. The carbon ends of the organic substances contain elements such as N, S, B, and P, which are doped into the carbon layer by heat treatment. The negative electrode material includes a silicon-based core and a carbon layer coated on the silicon-based core. The carbon layer contains a second doping element, which can improve the conductivity of the carbon coating layer.

[0093] When a metal complex is selected as the organic carbon source, the metal complex may be a conventional organic metal complex directly selected, or may be obtained by complexing an organic carbon material with a metal source. The structures of the negative electrode materials obtained by heat-treating complexes of different metal species are different, specifically as follows:

[0094] When the metal complex contains a highly active reducing metal element, it is likely to enter the core of the silicon-based material during the heat treatment process and form a corresponding metal silicate. The resulting negative electrode material includes a silicon-based material core and a carbon coating layer coated on the silicon-based material core, and the silicon-based material core contains a silicate formed of at least one of Si, SiOx (1.5≧x≧0.5), and SiO2.

[0095] When the metal complex contains a weakly reducing metal element, the metal element reacts with the nanosilicon in the silicon-oxygen mixture during the heat treatment process to form a silicon alloy. The resulting anode material has a two-layer coating. Specifically, the anode material includes a silicon-based material core, at least a portion of the surface of which is coated with an alloy layer, and at least a portion of the surface of the alloy layer is coated with a carbon layer. The presence of the alloy layer can improve the conductivity of the silicon-based material core and enhance the material's multi-layer performance. For example, when the metal source is Cu, the metal complex is a Cu complex, which forms a "petal-like" multi-layer porous structure on the surface carbon layer. The sheet layer structure increases the contact area of the conductive carbon layer and improves the extension distance and influence range of the carbon layer. On the other hand, the porous structure allows the electrolyte to penetrate the carbon layer, shortening the distance lithium ions travel. Furthermore, the carbon layer SEI is formed within the porous structure, and the extended carbon sheet layer is not covered by the SEI, but can still maintain contact with the conductive agent in the cell, thereby ensuring battery performance. When the metal source is Al, the metal complex is an Al complex, which can provide a certain coarse fibrous structure in the surface carbon layer, which also serves as protruding points for the conductive layer during the formation of the SEI layer, helping to maintain contact points for the conductive layer when the particles expand and contract.

[0096] In summary, this application employs an organic carbon source deposited on the surface of a solid powder (silicon-based material) to form a special crystalline framework, followed by high-temperature heat treatment to achieve a special morphology for the surrounding coating layer. The doping element can penetrate and be distributed throughout the particles during the organic heat treatment process, including the core of the silicon-based material, the silicon-based material core-first coating layer interface, and the first coating layer itself. This process optimizes the morphology of the coating layer, allowing the doping element to penetrate the interior of the material, resulting in a significant improvement in the performance of the anode material through a simple process. The special morphology of the organic carbon source after heat treatment can increase the contact area with the conductive carbon, thereby improving cycling performance and conductivity. It can also preserve the influence of the coating layer during the expansion process of the material, thereby reducing SEI breakdown and suppressing expansion. The doping element can also modify and improve the electrochemical properties of the material from within. This manufacturing method has a mild synthesis environment, high product yield, shortens the synthesis process, and ensures high electrochemical performance. It effectively reduces production costs and is suitable for large-scale industrial production, providing exceptional economic value.

[0097] In a third aspect, the present application provides a lithium ion battery, the lithium ion battery including a negative electrode material produced by the above-described production method.

[0098] Examples of the present application will be described below, but the present application is not limited to these examples unless it goes beyond the gist of the present application.

[0099] Example 1 p-Dimethylbiphenyl (2 g), SiO (10 g), and metallic lithium (1 g) were added to ethylene glycol dimethyl ether (10 g), and the mixture was stirred magnetically for 12 hours, heated in a water bath at a constant temperature of 50°C for 3 hours, heated at 70°C for 3 hours, and heated at 85°C for 3 hours. The mixture was then stirred at room temperature to evaporate the solvent, and then carbonized at 800°C for 6 hours in an argon gas protective atmosphere to obtain the negative electrode material.

[0100] The obtained negative electrode material includes a silicon-based core of Si, SiOx (1.5≧x≧0.5), and lithium silicate, and a carbon layer coated on the surface of the silicon-based core. As shown in FIG. 4(a), the carbon layer has a tapered structure. The median diameter of the negative electrode material is 5.0 μm, the powder conductivity is 10.9 S / m, and the I 1350 / I 1580 = 1.3, and I 510 / I 1350 =4.12.

[0101] Example 2 SiO (10 g) and copper phthalocyanine (1 g) were added to ethylene glycol dimethyl ether (10 g), and the mixture was stirred magnetically for 12 hours. The mixture was then heated in a water bath at a constant temperature of 50°C for 3 hours, 70°C for 3 hours, and 85°C for 3 hours. The mixture was then suction filtered, purged with dry Ar gas until completely dry, and carbonized in protective gas at 800°C for 6 hours to obtain the negative electrode material.

[0102] The obtained negative electrode material includes a silicon-based core of Si, SiOx (1.5≧x≧0.5), and a Si-Cu alloy, and a carbon layer coated on the surface of the silicon-based core. As shown in FIG. 4(b), the carbon layer has a petal-like structure. The median diameter of the negative electrode material is 5.0 μm, the powder conductivity is 13.7 S / m, and the I 1350 / I 1580 = 1.9, and I 510 / I 1350 =3.99.

[0103] Example 3 SiO (10 g) and aluminum acetylacetonate (1 g) were added to ethylene glycol dimethyl ether (10 g), and the mixture was stirred magnetically for 12 hours, heated in a water bath at a constant temperature of 50°C for 3 hours, heated at 70°C for 3 hours, and heated at 85°C for 3 hours. The mixture was then suction filtered, purged with dry Ar gas until completely dry, and carbonized in protective gas at 800°C for 6 hours to obtain the negative electrode material.

[0104] The obtained negative electrode material includes a silicon-based core of Si, SiOx (1.5≧x≧0.5), and aluminum silicate, and a carbon layer coated on the surface of the silicon-based core. As shown in FIG. 4(c), the carbon layer has a striped structure. The median diameter of the negative electrode material is 5.0 μm, the powder conductivity is 10.9 S / m, and the I 1350 / I 1580 = 1.4, and I 510 / I 1350 =4.32.

[0105] Example 4 SiO (10 g) and polyacrylic acid (1 g) were added to water (10 g), and the mixture was stirred magnetically for 12 hours, heated in a water bath at a constant temperature of 50°C for 3 hours, heated at 70°C for 3 hours, and heated at 85°C for 3 hours. The mixture was then suction filtered, purged with dry Ar gas until completely dry, and carbonized in protective gas at 800°C for 6 hours to obtain the negative electrode material.

[0106] The obtained negative electrode material includes a silicon-based core of Si and SiOx (1.5≧x≧0.5) and a carbon layer coated on the surface of the silicon-based core. As shown in FIG. 4(d), the carbon layer has a particulate structure. The median diameter of the negative electrode material is 5.0 μm, the powder conductivity is 11.0 S / m, and the I 1350 / I 1580 = 1.4, and I 510 / I 1350 =4.32.

[0107] Example 5 SiO (10 g) and 5-chloro-2-ethoxybenzeneboronic acid (2 g) were added to water (10 g), and the mixture was stirred magnetically for 12 hours, heated in a water bath at a constant temperature of 50°C for 3 hours, heated at 70°C for 3 hours, and heated at 85°C for 3 hours. The mixture was then suction filtered, purged with dry Ar gas until completely dry, and carbonized in protective gas at 800°C for 6 hours to obtain the negative electrode material.

[0108] The obtained negative electrode material includes a silicon-based core of Si, SiOx (1.5≧x≧0.5), and B2O3-SiO2, and a carbon layer coated on the surface of the silicon-based core. The carbon layer contains boron element and has a fine particle distribution structure. The median diameter of the negative electrode material is 5.0 μm, the powder conductivity is 10.6 S / m, and the I 1350 / I 1580 = 1.2, and I 510 / I 1350 =3.92.

[0109] Example 6 SiO (10 g) and phenyl sulfide (2 g) were added to ethylene glycol dimethyl ether (10 g), and the mixture was stirred magnetically for 12 hours, heated in a water bath at a constant temperature of 50°C for 3 hours, heated at 70°C for 3 hours, and heated at 85°C for 3 hours. The mixture was then suction filtered, purged with dry Ar gas until completely dry, and carbonized in protective gas at 800°C for 6 hours to obtain the negative electrode material.

[0110] The obtained negative electrode material includes a silicon-based core material such as Si, SiOx (1.5≧x≧0.5), silicate, or composite silicate, and a carbon layer coated on the surface of the silicon-based core material. The carbon layer contains sulfur element and has a planarized structure. The median diameter of the negative electrode material is 5.0 μm, the powder conductivity is 10.3 S / m, and the I 1350 / I 1580 = 1.3, and I 510 / I 1350 =3.82.

[0111] Example 7 p-Dimethylbiphenyl (2 g), SiO (10 g), and metallic sodium (1 g) were added to ethylene glycol dimethyl ether (10 g), and the mixture was stirred magnetically for 12 hours. The mixture was then stirred and dried at room temperature to evaporate the solvent, and the mixture was then carbonized at 800°C for 6 hours in an argon gas protective atmosphere to obtain the negative electrode material.

[0112] The obtained negative electrode material includes a silicon-based core of Si, SiOx (1.5≧x≧0.5), and sodium silicate, and a carbon layer coated on the surface of the silicon-based core. The carbon layer has a hilly large particle structure. The median diameter of the negative electrode material is 5.0 μm, the powder conductivity is 10.1 S / m, and the I 1350 / I 1580 = 1.1, and I 510 / I 1350 =4.41.

[0113] Example 8 SiO (10 g), copper phthalocyanine (1 g), and nickel phthalocyanine (1 g) were added to ethylene glycol dimethyl ether (10 g), and the mixture was stirred magnetically for 12 hours. The mixture was then stirred and dried at room temperature to evaporate the solvent, and the mixture was then carbonized at 800°C for 6 hours in an argon gas protective atmosphere to obtain the negative electrode material.

[0114] The obtained negative electrode material includes a silicon-based material core of Si and SiOx (1.5≧x≧0.5), and the surface of the silicon-based material core is coated with a mixed layer of silicon-copper alloy and silicon-nickel alloy and a carbon layer coated on the surface of the mixed layer, and the carbon layer has a striped structure, and the median diameter of the negative electrode material is 5.0 μm, the powder conductivity is 11.9 S / m, and the I 1350 / I 1580 = 1.5, and I 510 / I 1350 =3.81.

[0115] Example 9 Unlike Example 5, the carbonization temperature was 350°C.

[0116] The obtained negative electrode material includes a silicon-based core of Si, SiOx (1.5≧x≧0.5), and B2O3-SiO2, and a carbon layer coated on the surface of the silicon-based core. The carbon layer contains boron element and has a planarized morphology. The median diameter of the negative electrode material is 5.0 μm, the powder conductivity is 9.3 S / m, and the I 1350 / I 1580= 1.1, and I 510 / I 1350 =4.12.

[0117] Example 10 Unlike Example 5, the carbonization temperature was 400°C.

[0118] The obtained negative electrode material includes a silicon-based core of Si, SiOx (1.5≧x≧0.5), and B2O3-SiO2, and a carbon layer coated on the surface of the silicon-based core. The carbon layer contains boron element and has a planarized structure. The median diameter of the negative electrode material is 5.0 μm, the powder conductivity is 9.6 S / m, and the I 1350 / I 1580 = 1.21, and I 510 / I 1350 =4.19.

[0119] Example 11 Unlike Example 5, the carbonization temperature was 1000°C.

[0120] The obtained negative electrode material includes a silicon-based core of Si, SiOx (1.5≧x≧0.5), and B2O3-SiO2, and a carbon layer coated on the surface of the silicon-based core. The carbon layer contains boron element and has a small particle structure. The median diameter of the negative electrode material is 5.0 μm, the powder conductivity is 9.9 S / m, and the I 1350 / I 1580 =1.0, I 510 / I 1350 =3.98.

[0121] Example 12 Unlike Example 5, the carbonization temperature was 1200°C.

[0122] The obtained negative electrode material includes a silicon-based core of Si, SiOx, and B2O3-SiO2, and a carbon layer coated on the surface of the silicon-based core. The carbon layer contains boron element and has a small particle structure. The median diameter of the negative electrode material is 5.0 μm, the powder conductivity is 10.3 S / m, and the I 1350 / I 1580 = 1.2, and I 510 / I 1350 =3.7.

[0123] Example 13 Unlike Example 5, the carbonization temperature was 1300°C.

[0124] The obtained negative electrode material includes a silicon-based core of Si, SiOx (1.5≧x≧0.5), and B2O3-SiO2, and a carbon layer coated on the surface of the silicon-based core. The carbon layer contains boron element and has a fine particle structure. The median diameter of the negative electrode material is 5.0 μm, the powder conductivity is 9.5 S / m, and the I 1350 / I 1580 = 1.2, and I 510 / I 1350 =4.22.

[0125] Example 14 Unlike Example 5, 0.5 g of magnesium powder is added to the raw material.

[0126] The resulting negative electrode material comprises a silicon-based core of Si, SiOx (1.5≧x≧0.5), and B2O3-SiO2, and a carbon layer coated on the surface of the silicon-based core. The carbon layer contains boron element, and magnesium oxide, magnesium hydroxide, and a small amount of magnesium carbonate are vapor-deposited on it. The carbon layer has a fine particle structure, and magnesium salt particles can also be observed. The median diameter of the negative electrode material is 5.0 μm, the powder conductivity is 7.3 S / m, and the I of the negative electrode material is 1.0 μm. 1350 / I 1580 =0.9, and I 510 / I 1350 =4.10.

[0127] Example 15 Unlike Example 1, "heat in a water bath at a constant temperature of 50°C for 3 hours, then at 70°C for 3 hours, and then at 85°C for 3 hours" is replaced with "heat in a water bath at a constant temperature of 85°C for 9 hours."

[0128] The obtained negative electrode material includes a silicon-based core of Si, SiOx (1.5≧x≧0.5), and lithium silicate, and a carbon layer coated on the surface of the silicon-based core. The carbon layer has a tapered structure. The median diameter of the negative electrode material is 5.0 μm, the powder conductivity is 10.5 S / m, and the I 1350 / I 1580 = 1.3, and I 510 / I 1350 =3.27.

[0129] Example 16 Unlike Example 1, the amount of metallic lithium added is 2.0 g.

[0130] The obtained negative electrode material includes a silicon-based core of Si, SiOx (1.5≧x≧0.5), and lithium silicate, and a carbon layer coated on the surface of the silicon-based core. The carbon layer has a tapered structure. The median diameter of the negative electrode material is 5.0 μm, the powder conductivity is 6.3 S / m, and the I 1350 / I 1580 = 1.3, and I 510 / I 1350 =3.57.

[0131] Example 17 Unlike Example 2, the amount of copper phthalocyanine added was 4.0 g.

[0132] The obtained negative electrode material includes a silicon-based core of Si, SiOx (1.5≧x≧0.5), and a Si—Cu alloy, and a carbon layer coated on the surface of the silicon-based core. The carbon layer has a petal-like structure. The median diameter of the negative electrode material is 5.0 μm, the powder conductivity is 15.3 S / m, and the I 1350 / I1580 = 1.93, and I 510 / I 1350 =3.61.

[0133] Comparative Example 1 As the negative electrode material, silicon-oxygen raw material SiO (10 g) was used as it was.

[0134] Comparative Example 2 The silicon-oxygen raw material SiO (10 g) is vapor-deposited to form a carbon coating of a hydrocarbon organic carbon source, an alkene organic carbon source, or an alkyne organic carbon source, while simultaneously reducing the metal. After natural cooling, the negative electrode material is obtained.

[0135] The obtained negative electrode material includes a silicon-based core of Si and SiOx and a carbon coating layer coated on the surface of the silicon-based core. As shown in FIG. 4(e), the surface of the carbon coating layer is flat.

[0136] Comparative Example 3 Add 1g of CuCl2 to 10g of deionized water and dissolve completely. Then add 10g of silicon-oxygen raw material SiO2, stir magnetically for 12 hours, heat and stir in a water bath at 60℃ for 2 hours, then suction filter and dry. Then, use gas-phase deposition to coat the hydrocarbon organic carbon source, alkene organic carbon source, or alkyne organic carbon source with carbon, while simultaneously reducing the metal. After natural cooling, the negative electrode material is obtained.

[0137] Comparative Example 4 Add 1g of FeCl2 to 10g of deionized water and dissolve completely. Then add 10g of silicon-oxygen raw material SiO2. Stir magnetically for 12 hours, then heat and stir in a water bath at 60℃ for 2 hours. Then, filter and dry with suction. Then, use vapor deposition to coat the hydrocarbon organic carbon source, alkene organic carbon source, or alkyne organic carbon source with carbon, while simultaneously reducing the metal. After natural cooling, the negative electrode material is obtained.

[0138] Performance test: 1. SEM was employed to characterize the microstructure of the negative electrode material. 2. EDS is used to characterize the elemental components in the negative electrode material. 3. Malvern particle size analyzer is used to measure the particle size of the material. min and D max In contrast, the particle size of the core of the silicon-based material can be measured after removing the first coating layer. For example, if the first coating layer is a carbon layer, the carbon layer can be removed by ignition, and the particle size obtained by testing after removing the first coating layer can be considered to be equivalent to the particle size of the particle before coating. 4. Using CO2 spectrum, measure the carbon content of the anode material after calcining it. 5. XRD is used to calculate the grain size of crystalline silicon, silicates and silicon alloys. 6. Use pore distribution analysis to measure the pore volume of the negative electrode material, where pore volume is ΔV. Measure the true density P of the negative electrode material and calculate the porosity of the negative electrode material = ΔV / (ΔV+1 / P). 7. Use a Micro Tristar 3020 specific surface area and pore size analyzer to test the specific surface area of the negative electrode material. Weigh out a certain mass of powder, completely degas it under vacuum heating, remove the surface adsorbates, and then use the nitrogen gas adsorption method to calculate the specific surface area of the particles based on the amount of nitrogen gas adsorbed. 8. The powder conductivity is measured using a Mitsubishi Chemical MCP-PD51 powder resistivity tester. The test conditions are as follows: a certain amount of powder material is placed in the sample cell, and the powder conductivity is measured at a certain pressure, and the unit is S / cm. 9. Raman spectrum measurement using Raman spectrometer, test range is 800cm -1 ~2000cm -1 is. 10. Test the electrochemical performance using the following method: The negative electrode pieces of the button battery were manufactured using methods known in the art and the BTRTC / ZY / 01-020 button battery method. The manufactured button battery was tested in a LAND battery tester, charging and discharging at a constant current of 0.2C at room temperature, with the charge and discharge voltage limited to 2.75 to 4.2V. The initial reversible capacity, initial charge capacity, and initial discharge capacity were measured.

[0139] Initial coulombic efficiency = Initial discharge capacity / Initial charge capacity

[0140] Repeat the cycle 50 times, record the discharge capacity, and use it as the remaining capacity of the lithium-ion battery. Capacity retention rate = remaining capacity / initial capacity * 100%.

[0141] 50-cycle electrode expansion rate (%) measurement: The negative electrode material is mixed with graphite, adjusted to a fixed capacity (450mAh / g), and coated to form an electrode. The electrode thickness d1 is measured, and then assembled into a button cell battery. After 50 cycles, the battery is removed and the electrode thickness d2 is measured again. The electrode expansion rate = (d2-d1) / d1*100%.

[0142] Due to the difference in capacity of each material, there is a slight difference in the ratio, and the capacity of the mixture is set to the standard capacity of 480mAh / g, and tests are carried out at magnifications of 0.5C, 1.0C and 2.0C, respectively. The test results are shown in Tables 1 to 3.

[0143] [Table 1]

[0144] [Table 2]

[0145] [Table 3]

[0146] From the data in Tables 1 to 3, which are the test results of the comparative examples and examples, the following can be found: The negative electrode material of the present application comprises a silicon-based core and a first coating layer coated on at least a portion of the surface of the silicon-based core, the coating layer having a waviness y between 0.1 and 1, which indicates the range and space within which the conductive carbon in the first coating layer can expand, and during the expansion and contraction process of the negative electrode material when processed into a slurry or electrode piece, the contact area between the negative electrode material and the conductive agent can be increased, maintaining the connection between the silicon-based core and the electron path of the conductive agent, which is helpful in improving the conductivity, cycling performance, and multiplication performance of the negative electrode material, and stabilizing the SEI interface, thereby reducing pulverization, reducing the occurrence of side reactions, and suppressing the occurrence of irreversible expansion.

[0147] As shown in FIG. 2, the anode material of Comparative Example 1 has no carbon layer, and no carbon layer was found from the SEM and EDS element distribution. The carbon content of the anode material of Comparative Example 1 is very low, much lower than that of the other comparative examples. In Example 1, the carbon content of the finished product is improved to 1.21% by using a metallized organic carbon source. As shown in FIG. 3, as can be seen from the EDS map of Example 1, a carbon layer has already been coated on the core surface of the silicon-based material at this time, indicating that the carbon layer has been successfully synthesized.

[0148] The reversible capacity and initial coulombic efficiency of the sample in Example 1 reached 1381.7 mAh / g and 86.71%, respectively, which is far superior to the electrochemical performance of the common carbon-coated material SiO@C (Comparative Example 2, initial efficiency 76.4%). The manufacturing method of this application contributes to improving the performance of the synthesized negative electrode material, metal source, and carbon layer. This application not only simplifies the process but also improves the initial efficiency of the material, achieving process improvement.

[0149] In Comparative Examples 3 and 4, samples doped with some less reducible metals (Cu and Fe) were selected, and compared to Example 1, the improvement in the initial efficiency and multiplication performance of the less reducible metal materials was weak (Table 2). Furthermore, in Comparative Examples 3 and 4, chemical vapor deposition (CVD) was used to coat the carbon, reducing the metal and achieving a high carbon content coating layer. Chemical vapor deposition uses an exogenous organic carbon source to form carbon radicals at high temperatures, and the carbon content is much higher than in the spontaneously adsorbed crystal samples.

[0150] Based on the carbon content, it was found that metal doping was possible using either the metal complex method or the precipitation method. When doping using an organometallic complex, the organic carbon edge was subjected to high-temperature heat treatment, thereby completing the doping and carbon coating process. As can be seen from the EDS map in Figure 3, in Example 1, the presence of a carbon layer was observed when metal was doped via an organometallic complex. In Example 2, where a similar metal complex was used to dope the core and coat it with a carbon layer, the activity of the Cu element was low, so silicate could not be formed. Therefore, during the heat treatment process, Cu was reduced to metallic zero-valent copper by carbon, and the copper portion and the silicon-based portion formed a silicon-copper alloy. During the deposition of the Cu-based metal-organic material, the deposited crystals of the organometallic complex form a special hilly honeycomb-like structure. After heat treatment and sintering, the resulting carbon layer morphology, as shown in Figure 4(b), significantly increases the contact area between the conductive carbon and the conductive network, increasing the effective contact area. During the expansion and contraction process, the carbon layer maintains the connection between the active silicon and the conductive material's electron path through Si-metal and metal-C chemical bonds, improving the material's recyclability and stabilizing the SEI interface, thereby reducing pulverization, reducing side reactions, and suppressing irreversible expansion. Furthermore, the carbon-coated anode material of the present application has a large surface contact area. Unlike carbon fiber, the anode material of the present application has a vertical layered carbon coating (carbon nanotubes can be grown on the surface of the carbon coating), which allows it to maintain a 3D expanded morphology during charging and discharging, and maintains its carbon morphology during cycling, thereby maintaining an extremely large conductive contact area. The porous periphery can improve the infiltration depth of the electrolyte, shorten the diffusion path of lithium ions, and improve the power performance.

[0151] As shown in FIG. 5, the XRD pattern of the negative electrode material of Example 1 reveals the presence of copper-silicon alloy. Even when Cu is doped, it enters the core and successfully changes the core composition. After the surrounding copper is reduced, it penetrates the entire electron transport pathway, improving electronic and electrical conductivity.

[0152] In summary, the negative electrode material prepared in this application achieves breakthroughs in improving the foldability and expansion performance.

[0153] As can be seen from Table 3, the cycling expansion data for button battery cells reveals significant differences in the change trends of several different metals. In terms of cycling capacity retention, there is little difference between the strongly reducing materials and the comparative samples. While highly reducing metals have certain advantages due to their enhanced efficiency, their contribution to cycling retention is small, and the carbon coating layer does not achieve excellent optimization. The capacity retention rates of Comparative Examples 1, 2, and 3 are 80.9%, 78.7%, and 78.1%, respectively, indicating that silicate has little effect on capacity retention. However, from another perspective, the carbon coating layer formed with organic carbon exhibits good conductivity. Based on this, the capacity retention rates of the multilayer-coated anode materials in Examples 1, 2, and 3 are 91.7%, 93.1%, and 92.6%, respectively. The capacity retention rate is significantly improved, and in terms of expansion, the alloy layer has a certain effect of restricting the expansion of the material, reducing cyclic expansion. When the electrode expansion data for Example 2 after 50 cycles is compared with that of the conventional sample (Comparative Example 2), the expansion of the button battery electrode pieces is reduced from 44.2% to 36.1%.

[0154] The above is only a preferred embodiment of the present application, and does not limit the present application. Those skilled in the art may have various modifications and variations to the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. The present invention relates to a silicon-based core and a first coating layer coated on at least a surface of the core, wherein the range of the waviness y of the first coating layer is 1≧y≧0.10, and the waviness y of the first coating layer is represented by formula (I): the first coating layer includes a carbon layer or an organic polymer material layer, the material of the carbon layer includes at least one of amorphous carbon, graphite, soft carbon, and hard carbon, and the material of the organic polymer material layer includes at least one of a polyamine-based compound, a polyester-based compound, and a polyene-based compound. [Equation 1] (In formula (I), R max is the maximum thickness (nm) of the first coating layer, and R min is the minimum thickness (nm) of the first coating layer, D50 is the median diameter (μm) of the negative electrode material, and C is the mass percentage (%) of the first coating layer in the negative electrode material. Among these, maximum thickness R max = D min after coating with the first coating layer - D min before coating with the first coating layer, and minimum thickness R min = D max after coating with the first coating layer - D max before coating with the first coating layer, where D min and D max are the minimum and maximum particle sizes in the particle size test, respectively.

2. The silicon-based material core comprises crystalline silicon and a silicide, the silicide comprising at least one of SiOx, silica, silicate, and silicon alloy, wherein 1.5≧x≧0.5; and / or The silicon-based material core includes crystalline silicon and silicide, and the silicide includes at least one of SiOx, silica, silicate, and silicon alloy, where 1.5≧x≧0.5, and the grain size D of the crystalline silicon Si is between 2.5 nm and 15 nm, and / or 2. The anode material of claim 1, wherein the silicon-based core comprises crystalline silicon and silicide, the silicide comprising at least one of SiOx, silica, silicate, and silicon alloy, wherein 1.5≧x≧0.5, and the silicate cation comprises a metal element.

3. The negative electrode material described in claim 1, characterized in that the median diameter of the core of the silicon-based material is 1 μm to 13 μm.

4. The thickness of the first coating layer is 10 nm to 500 nm, and / or The first coating layer has pores, and the pore diameter of the pores is 10 nm to 60 nm; and / or 2. The negative electrode material according to claim 1, wherein the porosity of the first coating layer is 0.5% to 15%.

5. The core of said silicon-based material comprises a first doping element, said first doping element comprising at least one of lithium, magnesium, sodium, copper, platinum, iron, manganese, cobalt, nickel, indium, silver, gold, titanium, molybdenum, aluminum, palladium, calcium, iridium, chromium, gallium, rhodium and ruthenium; and / or 2. The negative electrode material according to claim 1, wherein the first coating layer contains a second doping element, and the second doping element contains at least one of nitrogen, fluorine, phosphorus, sulfur, and boron.

6. 2. The negative electrode material according to claim 1, further comprising a second coating layer between the silicon-based material core and the first coating layer.

7. 7. The negative electrode material according to claim 6, wherein the material of the second coating layer includes a silicon alloy.

8. In Raman imaging measured by Raman spectroscopy of the negative electrode material, -1 ~1400cm -1 The maximum peak intensity I 1 and 1550 cm of the negative electrode material -1 ~1650cm -1 The maximum peak intensity I 2 The ratio of 1 / I 2 <3 and 480 cm of the negative electrode material -1 ~540cm -1 The maximum peak intensity I 3 and 1300 cm of the negative electrode material -1 ~1400cm -1 The maximum peak intensity I 1 The ratio of 3 / I 1 The negative electrode material according to claim 1, characterized in that it satisfies the following condition:

9. The negative electrode material according to claim 1, characterized in that the median diameter D50 of the negative electrode material is 1.5 μm to 15 μm.

10. The negative electrode material according to claim 1, characterized in that the carbon content of the negative electrode material is 0.5% to 10%.

11. The negative electrode material according to claim 1, wherein the powder conductivity of the negative electrode material is 0.1 S / m to 100 S / m.

12. The negative electrode material according to claim 1, wherein the specific surface area of the negative electrode material is 0.8 m 2 / g to 10 m 2 / g.

13. A method for producing the negative electrode material according to any one of claims 1 to 12, comprising: Mixing an organic carbon source, a silicon-based material, and an organic solvent to obtain a precursor; heat-treating the precursor to obtain a negative electrode material; The method further includes a step of evaporating and crystallizing the mixed material after mixing the organic carbon source, the silicon-based material, and the organic solvent; The temperature of the evaporation crystallization is 30°C to 80°C, the organic carbon source includes at least one of p-dimethylbiphenyl, polyacrylic acid, phthalocyanine, diphenyl ether, polyvinyl acetate, ethyl stearate, dopamine, 5-chloro-2-ethoxybenzeneboronic acid, phenyl sulfide, and a metal complex; the metal complex includes at least one of copper phthalocyanine, aluminum acetylacetonate, cyhexatin, and cobalt isopropoxide; The silicon-based material includes at least one of Si, SiOx, and SiO2, where 1.5≧x≧0.5; 10. A method for producing a negative electrode material, wherein the organic solvent contains at least one of dimethyl carbonate, tetrahydrofuran, a carbonate ester, toluene, benzene, ethyl ether, propylene oxide, a ketone, and ethylene glycol dimethyl ether.

14. 14. The method of claim 13, wherein the organic carbon source comprises a metal complex, and the metal complex is obtained by complexing an organic carbon material with a metal source.

15. The manufacturing method described in Claim 14, characterized in that the metal source includes at least one of a lithium source, a magnesium source, a sodium source, a copper source, an iron source, a manganese source, a cobalt source, a nickel source, an indium source, a silver source, a gold source, a titanium source, a molybdenum source, an aluminum source, a palladium source, a calcium source, an iridium source, a platinum source, a gallium source, a chromium source, a rhodium source, and a ruthenium source.

16. A lithium ion battery, comprising the negative electrode material according to any one of claims 1 to 12.

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