Negative electrode material, secondary battery, and electric device

Abstract

The application provides a negative electrode material, a secondary battery and an electric device, so as to improve the energy density of the secondary battery in which the negative electrode material is located by improving the gravimetric capacity and the true density of the negative electrode material. The negative electrode material is a porous carbon particle; wherein the XRD pattern of the negative electrode material includes a first diffraction peak and a second diffraction peak located at 10°-30°, the half-peak width of the first diffraction peak is greater than the half-peak width of the second diffraction peak, and the ratio of the peak intensity of the second diffraction peak to the peak intensity of the first diffraction peak is A, 0.8≤A≤20.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of secondary batteries, in particular to a negative electrode material, a secondary battery and an electric device. BACKGROUND

[0002] As a clean energy, secondary batteries have gradually been popularized from electronic products to large electric devices such as electric vehicles. Therefore, the energy density of secondary batteries needs to be further improved.

[0003] Since graphite has the advantages of high conductivity and high stability, the negative active material of the secondary battery is mainly graphite. However, the actual gram capacity of the graphite currently applied to the negative active material of the secondary battery has approached its upper limit: the theoretical gram capacity is 372 mAh / g. Therefore, the gram capacity of the graphite as the negative active material is difficult to be further improved, which leads to the difficulty in further improving the energy density of the secondary battery with graphite as the negative active material. SUMMARY

[0004] The present application provides a negative electrode material, a secondary battery and an electric device, which can improve the energy density of the secondary battery with the negative electrode material by improving the gram capacity and true density of the negative electrode material.

[0005] In a first aspect, the embodiments of the present application provide a negative electrode material, which is a porous carbon particle; wherein,

[0006] The XRD pattern of the negative electrode material includes a first diffraction peak and a second diffraction peak located at 10°-30°, the half-peak width of the first diffraction peak is greater than that of the second diffraction peak, and the ratio of the peak intensity of the second diffraction peak to the peak intensity of the first diffraction peak is A, 0.8≤A≤20.

[0007] In one of the embodiments, the negative electrode material includes a disordered carbon structure and an ordered carbon structure.

[0008] In one of the embodiments, the Raman spectrum of the negative electrode material includes a D peak and a G peak, and the ratio of the peak intensity I D of the D peak to the peak intensity I G of the G peak satisfies 0.30≤I D / I G ≤1.40. D G

[0009] In one of the embodiments, the ratio of the peak intensity I D of the D peak to the peak intensity I G of the G peak in the Raman spectrum of the negative electrode material satisfies 0.75≤I D / I G ≤1.40. D ​​ / I G ≤1.15.

[0010] In one of the embodiments, the element M in the negative electrode material is at least one of Ti, Si, Zr, Al, Nb, Cr, Sr, Ba and Ca.

[0011] The mass content of the element M is m, m≤6.5%, based on the mass of the negative electrode material.

[0012] In one of the embodiments, A≤6.

[0013] In one of the embodiments, the XRD pattern of the negative electrode material satisfies at least one of the following conditions:

[0014] (1) the half-peak width of the first diffraction peak is 5°-9°;

[0015] (2) the diffraction angle of the first diffraction peak is 20°-24°;

[0016] (3) the half-peak width of the second diffraction peak is 0.5°-1.5°;

[0017] (4) the diffraction angle of the second diffraction peak is 25.9°-26.9°.

[0018] In one of the embodiments, the half-peak width of the first diffraction peak in the XRD pattern of the negative electrode material is 5°-9°.

[0019] In one of the embodiments, the diffraction angle of the first diffraction peak in the XRD pattern of the negative electrode material is 20°-24°.

[0020] In one of the embodiments, the half-peak width of the second diffraction peak in the XRD pattern of the negative electrode material is 0.5°-1.5°.

[0021] In one of the embodiments, the diffraction angle of the second diffraction peak in the XRD pattern of the negative electrode material is 25.9°-26.9°.

[0022] In one of the embodiments, the negative electrode material comprises a carbon skeleton and a carbon layer arranged on the surface of the carbon skeleton.

[0023] In one of the embodiments, the negative electrode material satisfies at least one of the following conditions:

[0024] (1) the pore volume of the negative electrode material is less than or equal to 0.05 cm 3 / g;

[0025] (2) the specific surface area of the negative electrode material is 0.5-50 m2 / g;

[0026] (3) the pore volume of the negative electrode material after crushing is 0.1-0.9 cm 3 / g;

[0027] (4) the specific surface area of the negative electrode material after crushing is 150-1500 m 2 / g;

[0028] (5) the pore size of the negative electrode material after crushing is 0.3-2.0 nm;

[0029] (6) the apparent density of the negative electrode material is 0.5-1.7 g / cm 3 .

[0030] In one embodiment, the pore volume of the negative electrode material is less than or equal to 0.05 cm 3 / g;

[0031] In one embodiment, the specific surface area of the negative electrode material is 0.5-50 m 2 / g;

[0032] In one embodiment, the pore volume of the negative electrode material after crushing is 0.1-0.9 cm 3 / g;

[0033] In one embodiment, the specific surface area of the negative electrode material after crushing is 150-1500 m 2 / g;

[0034] In one embodiment, the pore size of the negative electrode material after crushing is 0.3-2.0 nm;

[0035] In one embodiment, the apparent density of the negative electrode material is 0.5-1.7 g / cm 3 .

[0036] In one embodiment, the Dv50 of the negative electrode material is 3-12 μm.

[0037] In one embodiment, the negative electrode material is obtained by sintering a source of element M at a first temperature condition and then sintering at a second temperature condition under a halogen atmosphere.

[0038] In a second aspect, the embodiments of the present application provide a secondary battery, comprising a positive electrode sheet, a negative electrode sheet and an electrolyte, the negative electrode sheet comprising a current collector and a negative electrode active material attached to at least one side surface of the current collector, wherein,

[0039] The negative active material comprises the negative electrode material of the first aspect and any possible implementation.

[0040] In a third aspect, the embodiments of the present application provide a power consumption device, comprising:

[0041] The secondary battery of the second aspect.

[0042] The one or more technical solutions provided in the embodiments of the present application have at least the following beneficial effects:

[0043] The embodiments of the present application provide a negative electrode material with a ratio A of the diffraction peak intensity of the ordered carbon structure to the diffraction peak intensity of the disordered carbon structure being between 0.8 and 20, so as to improve the specific capacity and true density of the negative electrode material, thereby improving the energy density of the secondary battery in which the negative electrode material is located.

[0044] Other features and advantages of the present application will be described in the following description and, in part, will become apparent from the description or will be learned by practice of the present application. The objects and other advantages of the present application will be realized and attained by the structure particularly pointed out in the written description and claims, and the appended drawings. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only the embodiments of the present application, and those skilled in the art can also obtain other drawings according to the provided drawings without creative labor.

[0046] Figure 1 The XRD test graph of Example 2 provided by the embodiments of the present application;

[0047] Figure 2 The XRD graph after fitting processing of the XRD graph of Example 2 provided by the embodiments of the present application. DETAILED DESCRIPTION

[0048] In order to solve the problem of insufficient gram capacity of the negative electrode material, the embodiment of the present application provides a negative electrode material. The negative electrode material is a porous carbon particle, and the XRD (X-ray Diffraction) spectrum of the negative electrode material includes a first diffraction peak and a second diffraction peak located at 10°-20°. The first diffraction peak corresponding to the disordered carbon structure is a wide peak, and the second diffraction peak corresponding to the ordered carbon structure is a sharp peak. The peak intensity ratio of the second diffraction peak to the first diffraction peak is 0.8-20. The negative electrode material has appropriate relative content of ordered carbon structure and disordered carbon structure, thereby improving its true density and effectively improving its gram capacity. Therefore, when the negative electrode material is applied to a secondary battery, the energy density of the secondary battery can be improved.

[0049] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described clearly and completely below in conjunction with embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. The embodiments described herein are illustrative in nature and are used to provide a basic understanding of the present application. The embodiments of the present application should not be interpreted as a limitation of the present application.

[0050] The terms "first" and "second" in the specification and claims of the present application and the above-described drawings are used to distinguish different objects, rather than to describe a specific order.

[0051] For the sake of brevity, only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form a range not explicitly recited; and any lower limit can be combined with other lower limits to form a range not explicitly recited, as can any upper limit with any other upper limit to form a range not explicitly recited. Further, each individual disclosed point or single numerical value can itself serve as a lower limit or upper limit to combine with any other point or single numerical value or with other lower limits or upper limits to form a range not explicitly recited.

[0052] In the description herein, "above", "below" include the number itself unless otherwise stated.

[0053] Unless otherwise defined, the terms used in the present application have the commonly understood meanings as understood by those skilled in the art. Unless otherwise stated, the values of the parameters mentioned in the present application can be measured by various measurement methods commonly used in the art (for example, tests can be performed according to the methods given in the embodiments of the present application).

[0054] The list of items connected by “at least one of,” “at least one,” “at least one of the items,” or other similar phrases is meant not to be a single item from the list, but rather a disjunctive list of items. For example, the phrase “at least one of A and B” means only A; only B; or A and B. In another example, the phrase “at least one of A, B, and C” means only A; only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or A, B, and C. Item A can include a single component or multiple components. Item B can include a single component or multiple components. Item C can include a single component or multiple components.

[0055] The embodiment of the present application first provides a negative electrode material, which is a porous carbon particle. In the XRD pattern of the negative electrode material, a first diffraction peak and a second diffraction peak are included, both of which are located between 10° and 30°.

[0056] The first diffraction peak is a wide peak, and the second diffraction peak is a sharp peak, so the half-peak width of the first diffraction peak is greater than the half-peak width of the second diffraction peak. Exemplarily, the ratio f1 / f2 of the half-peak width f1 of the first diffraction peak to the half-peak width f2 of the second diffraction peak is greater than 4.

[0057] In the formula, A is the ratio of the peak intensity of the second diffraction peak to the peak intensity of the first diffraction peak, and satisfies 0.8≤A≤20.

[0058] Specifically, since the second diffraction peak corresponds to an ordered carbon structure in the negative electrode material, and the first diffraction peak corresponds to a disordered carbon structure in the negative electrode material, when 0.8≤A≤20, the relative content of the ordered carbon structure and the disordered carbon structure in the negative electrode material is appropriate, which can improve the true density and the gram capacity of the negative electrode material, and effectively improve the cycle performance and safety performance of the secondary battery in which the negative electrode material is used.

[0059] On this basis, the ordered carbon in the negative electrode material is distributed in the disordered carbon, which can further improve the stability of the crystal phase structure of the material, and promote the high-rate (for example, 5C) capacity retention rate and the low-temperature capacity retention rate of the secondary battery using the negative electrode material.

[0060] The first diffraction peak is a characteristic peak corresponding to the (002) crystal face corresponding to the disordered carbon structure. The second diffraction peak is a characteristic peak of the (002) crystal face corresponding to the ordered carbon structure.

[0061] Exemplarily, the value of A can be 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.5, 1.7, 1.9, 2.3, 2.8, 3.2, 3.8, 4.2, 4.6, 5.0, 5.5, 5.6, 5.8, 6.0, 7.0, 8.0, 10.0, 12.0, 14.0, 16.0, 18.0, 20.0, or a range between any two of them. Preferably, A≤6.

[0062] In one embodiment, the XRD pattern of the above negative electrode material can satisfy: the half-peak width of the first diffraction peak is 5°-9°.

[0063] Exemplarily, the half-peak width of the first diffraction peak can be 5°, 6°, 7°, 8°, 9°, or a range between any two of them.

[0064] In one embodiment, the XRD pattern of the above negative electrode material can satisfy: the diffraction angle of the first diffraction peak is 20°-24°.

[0065] Exemplarily, the diffraction angle of the first diffraction peak can be 20.0°, 20.5°, 21.0°, 21.5°, 22.0°, 22.5°, 23.0°, 23.5°, 24.0°, or a range between any two of them.

[0066] In one embodiment, the XRD pattern of the above negative electrode material can satisfy: the half-peak width of the second diffraction peak is 0.5°-1.5°.

[0067] Exemplarily, the half-peak width of the second diffraction peak can be 0.5°, 0.7°, 0.9°, 1.1°, 1.3°, 1.5°, or a range between any two of them.

[0068] In one embodiment, the XRD pattern of the above negative electrode material can satisfy: the diffraction angle of the second diffraction peak is 25.9°-26.9°. For example, the diffraction angle of the second diffraction peak is 26.0°, 26.1°, 26.2°, 26.3°, 26.4°, 26.5°, 26.6°, 26.7°, 26.8°, 26.9°, or a range between any two of them.

[0069] In one embodiment, the ratio of the peak intensity I D of the D peak to the peak intensity I G of the G peak in the Raman spectrum of the above negative electrode material satisfies, 0.30≤I D / I G ≤1.40. D / I G ≤1.40.

[0070] The Ramn spectrum is obtained by Raman Spectroscopy.

[0071] wherein the D peak is a characteristic peak in the Raman spectrum at 1300 cm -1 to 1400 cm -1 ; and the G peak is a characteristic peak in the Raman spectrum at 1530 cm -1 to 1630 cm -1 .

[0072] In one embodiment, 0.75≤I D / I G ≤1.15.

[0073] Exemplarily, the value of I D / I G may be 0.75, 0.80, 0.83, 0.85, 0.88, 0.90, 0.92, 0.95, 0.97, 1.00, 1.05, 1.08, 1.10, 1.15, or a range between any two of them.

[0074] To further improve the strength of the negative electrode material, so as to avoid the rapid attenuation of the lithium storage activity and specific capacity of the negative electrode material due to mechanical failure when the negative electrode material is applied to a secondary battery, in one embodiment, the negative electrode material described above further comprises a small amount of element M in addition to the element C. The element M is at least one of Ti, Si, Zr, Al, Nb, Cr, Sr, Ba and Ca.

[0075] The mass content of the element M is m, m≤6.5%, based on the mass of the negative electrode material. Exemplarily, m can be 0.01%, 0.02%, 0.03%, 0.1%, 0.2%, 0.5%, 1.0%, 1.5%, 1.8%, 2.1%, 2.3%, 2.8%, 3.2%, 3.7%, 4.1%, 4.5%, 4.7%, 5.2%, 6.5%, or a range between any two of them.

[0076] In this case, the element M is distributed in the form of small particle carbide inside the carbon skeleton.

[0077] Further, the apparent density of the negative electrode material is 0.5-1.7 g / cm 3 , so that when it is applied to a secondary battery, a large number of active ion (e.g., Li + ) storage sites can be provided.

[0078] To further reduce the amount of SEI film generated, to avoid loss of active lithium, and to reduce the contact area between the electrolyte and the negative electrode material, in one embodiment, the negative electrode material described above can further include a carbon layer, which can be disposed on the surface of the carbon framework.

[0079] Since the carbon layer is located on the surface of the negative electrode material, the carbon layer can be regarded as forming a coating structure on the surface of the carbon framework. Therefore, the carbon layer on the surface of the carbon framework can convert the pores of the porous structure into internal pores, thereby reducing the amount of SEI film generated and reducing the contact area between the electrolyte and the negative electrode material.

[0080] It should be understood that the thickness of the carbon layer in the coating structure described above on the surface of the carbon framework is not equal everywhere. Moreover, the coating area of the carbon layer on the surface of the carbon framework is at least more than 50%, but in some areas on the surface of the carbon framework, there can be no carbon layer.

[0081] In one embodiment, the thickness of the carbon layer is at least 5 nm. For example, the thickness of the carbon layer is 5-200 nm.

[0082] In one embodiment, the negative electrode material described above satisfies: the pore volume of the negative electrode material is less than or equal to 0.05 cm 3 / g.

[0083] In one embodiment, the specific surface area of the negative electrode material described above is 0.5-50 m 2 / g;

[0084] In one embodiment, the pore volume of the negative electrode material subjected to the crushing treatment is 0.1-0.9 cm 3 / g;

[0085] In one embodiment, the negative electrode material described above satisfies: the specific surface area of the negative electrode material subjected to the crushing treatment is 150-1500 m 2 / g;

[0086] In one embodiment, the negative electrode material described above satisfies: the pore size of the negative electrode material subjected to the crushing treatment is 0.3-2.0 nm.

[0087] In one embodiment, the crushing treatment of the negative electrode material can be obtained by crushing a small amount of negative electrode material by a grinder.

[0088] In one embodiment, the negative electrode material described above satisfies: the pore volume of the negative electrode material is less than or equal to 0.05 cm 3 / g, and the pore volume of the negative electrode material subjected to the crushing treatment is 0.1-0.9 cm 3 / g.

[0089] In one embodiment, the negative electrode material described above satisfies: the specific surface area of the negative electrode material is 0.5-50 m 2 / g, and the specific surface area of the crushed negative electrode material is 150-1500 m 2 / g.

[0090] To further improve the bulk density of the negative electrode material, in one embodiment, the volume median particle size Dv50 of the negative electrode material is 3-12 μm.

[0091] To promote the random distribution of ordered carbon structures in disordered carbon structures, in one embodiment, the negative electrode material is obtained by sintering the source of element M in a halogen atmosphere at a first temperature condition, and then cooling to a second temperature condition for further sintering.

[0092] Based on the same inventive concept, the present application provides a preparation method of the above negative electrode material, which comprises the following steps:

[0093] In an inert atmosphere with a halogen atmosphere content greater than or equal to 5wt%, the halogen atmosphere and the precursor are subjected to an etching reaction at a first temperature condition for 0.5-2 hours to generate a first intermediate product.

[0094] After cooling to a second temperature condition, the halogen atmosphere and the first intermediate product are subjected to an etching reaction for 0.5-10 hours to obtain a second intermediate product.

[0095] Without changing the temperature, the atmosphere condition is changed to an inert atmosphere or an inert atmosphere containing hydrogen to further remove impurities, thereby obtaining the above negative electrode material. The negative electrode material has a porous structure.

[0096] The precursor comprises a source of element M. The source may, for example, be a carbide of element M.

[0097] In one embodiment, the precursor is a source of element M.

[0098] If element M corresponds to Si, the source may, for example, be at least one of SiC, TiC, ZrC, NbC, Cr3C2, BaC2, CaC2, SrC2, Al4C3, Ti3AlC2, Ti2AlC, Ti3AlCN, Nb2AlC, and Ti3C2.

[0099] Specifically, the volume median particle size Dv50 of the precursor is 3-12 μm.

[0100] Exemplarily, the halogen atmosphere may, but is not limited to, include F2, Cl2, Br2, I2, HF, CCl4, CHCl3, Cl2-H2, Cl2-HCl, and HCl.

[0101] The first temperature condition is greater than the second temperature condition. Specifically, the first temperature condition may, for example, be selected from 400-1500℃. The second temperature condition may, for example, be selected from 200-1300℃.

[0102] Further, the negative electrode material can be subjected to a vapor deposition reaction in an inert atmosphere containing an organic gas at a temperature of 400-1000°C to form a carbon layer on the surface of the negative electrode material.

[0103] The organic gas includes at least one of an alkane, an alkene, and an alkyne. The content of the organic gas in the inert atmosphere is greater than or equal to 5 wt%.

[0104] Exemplarily, the organic gas includes at least one of methane, ethylene, acetylene, and propane.

[0105] Based on the same inventive concept, the embodiments of the present application also provide a secondary battery, which includes a positive electrode sheet, a negative electrode sheet, and an electrolyte.

[0106] The negative electrode sheet includes a current collector and a negative electrode active material attached to at least one side surface of the current collector.

[0107] The negative electrode active material includes the aforementioned negative electrode material.

[0108] To improve the compaction density of the negative electrode active material, in one embodiment, the negative electrode active material can further include graphite.

[0109] In one embodiment, the negative electrode active material layer can further include a thickening agent, which can include, but is not limited to, sodium carboxymethyl cellulose.

[0110] The negative electrode active material layer can be arranged on one surface in the thickness direction of the current collector of the negative electrode, or on both surfaces in the thickness direction.

[0111] The surface of the current collector of the negative electrode can further include other additional functional layers in addition to the negative electrode active material. In one embodiment, a conductive coating layer is further included.

[0112] The conductive coating layer can be located between the negative electrode active material layer and the surface of the current collector of the negative electrode.

[0113] The conductive coating layer can be composed of a conductive agent and a negative electrode binder.

[0114] For example, the conductive agent can include, but is not limited to, a carbon material, a metal, or a conductive polymer, etc. Among them, the carbon material can include at least one of natural graphite, artificial graphite, superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The metal can include metal powder or metal fiber of copper, iron, aluminum, etc. The conductive polymer can include polyphenylene derivatives. The negative electrode binder can include, but is not limited to, at least one of polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, butadiene styrene rubber, acrylated butadiene styrene rubber, epoxy resin, or nylon.

[0115] In one embodiment, the negative electrode tab can further include a protective layer on a side surface of the negative electrode active material layer facing the air.

[0116] The negative electrode current collector according to embodiments of the present application is not particularly limited as long as the purpose of the present application can be achieved. For example, the negative electrode current collector can include a metal foil, a porous metal plate, or a composite current collector.

[0117] The metal foil can be a copper foil, a copper alloy foil, a nickel foil, a stainless steel foil, or a titanium foil. The porous metal plate can be a nickel foam or a copper foam, etc. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be obtained by forming a metal material (for example, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material base layer (for example, a base layer of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0118] The thickness of the negative electrode current collector can be, for example, 4 to 12 μm, and the thickness of the single-sided negative electrode active material layer can be 30 to 200 μm.

[0119] It should be noted that the aforementioned "surface" can be the entire area of the negative electrode current collector, or can be a partial area of the negative electrode current collector, and the present application is not particularly limited as long as the purpose of the present application can be achieved.

[0120] In one embodiment, the positive electrode tab can include a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector.

[0121] Among them, the positive electrode current collector can be, for example, a metal foil or a composite current collector, etc. The metal foil can be, for example, an aluminum foil.

[0122] The composite current collector can include a polymeric material base layer and a metal material layer disposed on at least one surface of the polymeric material base layer. For example, the metal material layer can include at least one of aluminum, an aluminum alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, or a silver alloy. The polymeric material base layer can include at least one of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, or polyethylene.

[0123] The positive electrode active material layer can include a positive electrode active material.

[0124] In one embodiment, the positive electrode active material layer can further include a conductive agent and a positive electrode binder. The conductive agent can be, for example, the same as the conductive agent described above in the negative electrode active material layer. The positive electrode binder can be, for example, the same as the negative electrode binder described above in the negative electrode active material layer.

[0125] In one embodiment, the positive electrode tab can further include a conductive coating layer disposed between the surface of the positive electrode current collector and the positive electrode active material layer. The conductive coating layer can be composed of, for example, a conductive agent and a binder.

[0126] In one embodiment, the positive electrode tab can further include a protective layer covering the surface of the positive electrode active material layer.

[0127] The electrolyte can include an organic solvent, an electrolyte salt. The electrolyte salt is determined according to active ions in the secondary battery.

[0128] The organic solvent can include, for example, at least one of a carbonate compound, a carboxylic acid ester compound, an ether compound, or other non-aqueous organic solvents. The carbonate compound can include, but is not limited to, at least one of a chain carbonate compound, a cyclic carbonate compound, or a fluoro-carbonate compound. The chain carbonate compound can include, but is not limited to, at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), or methyl ethyl carbonate (MEC). The cyclic carbonate can include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), or vinyl ethylene carbonate (VEC). The fluoro-carbonate compound can include, but is not limited to, at least one of fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methyl ethylene carbonate, 1-fluoro-1-methyl ethylene carbonate, 1,2-difluoro-1-methyl ethylene carbonate, 1,1,2-trifluoro-2-methyl ethylene carbonate, or trifluoromethyl ethylene carbonate. The carboxylic acid ester compound can include, but is not limited to, at least one of methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), n-propyl acetate, t-butyl acetate, methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), ethyl butyrate (EB), 1,4-butyrolactone (GBL), decanolactone, valerolactone, or caprolactone. The ether compound can include, but is not limited to, at least one of dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1-ethoxy-1-methoxyethane, 2-methyltetrahydrofuran, or tetrahydrofuran. The other non-aqueous organic solvents can include, but is not limited to, at least one of dimethylsulfoxide (MSM), methyl ethyl sulfoxide (EMS), diethyl sulfoxide (ESE), sulfolane (SF), 1,2-dioxolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidinone, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, or trioctyl phosphate.

[0129] Further, the electrolyte solution can further include an additive. The additive can include at least one of a negative electrode film-forming additive, a positive electrode film-forming additive, or an additive capable of improving certain properties of the battery. For example, an additive to improve overcharge properties of the battery, an additive to improve high-temperature or low-temperature properties of the battery, etc.

[0130] The additives can include, for example, but are not limited to, at least one of fluoroethylene carbonate (FEC), vinylene carbonate (VC), vinyl ethylene carbonate (VEC), divinyl sulfite (DTD), propylene sulfite, ethylene sulfite (ES), 1,3-propane sultone (PS), 1,3-propene sultone (PST), sulfonate cyclic quaternary ammonium salt, succinic anhydride, succinonitrile (SN), adiponitrile (AND), tris(trimethylsilyl)phosphate (TMSP), tris(trimethylsilyl)borate (TMSB).

[0131] In one embodiment, the secondary battery is a lithium ion battery, and the positive active material can include a lithium transition metal oxide, which can include, but is not limited to, at least one of lithium nickel cobalt manganese oxide (LiNi 0.90 Co 0.05 Mn 0.05 O2, LiNi 0.80 Co 0.10 Mn 0.10 O2, LiNi 0.60 Co 0.20 Mn 0.20 O2, LiNi 0.50 Co 0.20 Mn 0.30 O2, LiNi 0.33 Co 0.33 Mn 0.33 O2), lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium-rich manganese-based material, lithium cobaltate, lithium manganate, lithium manganese iron phosphate, or lithium titanate, etc.

[0132] Accordingly, the electrolyte salt in the electrolyte can include a lithium salt. The lithium salt can include, but is not limited to, at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium bisfluorosulfonylimide (LiFSI), lithium bis-trifluoromethanesulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoro-oxalato-borate (LiODFB), lithium difluoro-oxalato-borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluoro-dioxalato-phosphate (LiDFOP), and lithium tetrafluoro-oxalato-phosphate (LiTFOP).

[0133] In one embodiment, the secondary battery is a sodium ion battery, and the positive active material can include at least one of a sodium transition metal oxide, a polyanion compound, and a Prussian blue compound. The sodium transition metal oxide can include Na 1-x Cu h Fe k Mn l M 1 m O 2-y , Na0.67 Mn 0.7 Ni z M 2 0.3-z O2, Na a Li b Ni c Mn d Fe e O2, wherein M 1 is at least one of Li, Be, B, Mg, Al, K, Ca, Ti, Co, Ni, Zn, Ga, Sr, Y, Nb, Mo, In, Sn, or Ba, 0 < x < 0.33, 0 < h < 0.24, 0 < k < 0.32, 0 < l < 0.68, 0 < m < 0.1, h + k + l + m = 1, 0 < y < 0.2; M 2 is at least one of Li, Mg, Al, Ca, Ti, Fe, Cu, Zn, or Ba, 0 < z < 0.1; 0.67 < a < 1, 0 < b < 0.2, 0 < c < 0.3, 0.67 < d + e < 0.8, b + c + d + e = 1. The polyanionic compound can include, but is not limited to: A 1 f M 3 g (PO4) i O j X 1 3-j , Na n M 4 PO4X 2 , Na p M 5 q (SO4)3, Na s Mn t Fe 3-t (PO4)2(P2O7), wherein A 1 is at least one of H, Li, Na, K, or NH4, M 3 is at least one of Ti, Cr, Mn, Fe, Co, Ni, V, Cu, or Zn, X 1 is at least one of F, Cl, or Br, 0 < f < 4, 0 < g < 2, 1 < i < 3, 0 < j < 2; M 4 is at least one of Mn, Fe, Co, Ni, Cu, or Zn, X 2 is at least one of F, Cl, or Br, 0 < n < 2; M 5 is at least one of Mn, Fe, Co, Ni, Cu, or Zn, 0 < p < 2, 0 < q < 2; 0 < s < 4, 0 < t < 3. The Prussian blue type compound can include, but is not limited to: A 2 μm6 v [M 7 (CN)6] w ·xH2O, wherein A 2 is H + , NH4 + , one or several of an alkali metal cation and an alkaline earth metal cation, M 6 and M 7 are each independently at least one of a transition metal cation, 0 2 is H + , Li + , Na + , K + , NH4 + , Rb + , Cs + , Fr + , Be 2+ , Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ and Ra 2 + , M 6 and M 7 are each independently a cation of at least one of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn and W. Preferably, A 2 is at least one of Li + , Na + and K + , M 6 is a cation of at least one of Mn, Fe, Co, Ni and Cu, and M 7 is a cation of at least one of Mn, Fe, Co, Ni and Cu.

[0134] Correspondingly, the electrolyte salt can include a sodium salt, which can include, but is not limited to, at least one of NaPF6, NaClO4, NaBCl4, NaSO3CF3and Na(CH3)C6H4SO3.

[0135] In one embodiment, the thickness of the positive current collector is 5-20 μm; preferably 6-18 μm.

[0136] The thickness of the single-sided positive active material layer is 30-400 μm.

[0137] In one embodiment, the positive electrode active material layer can be provided on one surface in the thickness direction of the positive electrode current collector, or on both surfaces in the thickness direction of the positive electrode current collector.

[0138] It should be noted that the "surface" described above can be the entire area of the positive electrode current collector, or a partial area of the positive electrode current collector, and the present application does not make a specific limitation.

[0139] The secondary battery described above further includes a separator for separating the positive electrode tab and the negative electrode tab, preventing internal short circuit of the secondary battery, allowing free passage of electrolyte ions, and not affecting electrochemical charging and discharging. The material of the separator can include, but is not limited to, at least one of polyethylene (PE), polyolefin (PO) based on polypropylene (PP), polyester (such as polyethylene terephthalate (PET) film), cellulose, polyimide (PI), polyamide (PA), spandex, or aramid.

[0140] The type of the separator can include at least one of a woven film, a non-woven film, a microporous film, a composite film, a calendered film, or a spunlaced film.

[0141] The separator can have a porous structure, and the present application does not make a limitation on the pore size of the porous structure. For example, the size of the pore can be 0.01 μm to 1 μm.

[0142] The present application does not make a limitation on the thickness of the separator. For example, the thickness of the separator can be 3 μm to 20 μm.

[0143] The secondary battery of the present application can further include an outer package for packaging the positive electrode tab, the separator, the negative electrode tab, and the electrolyte, and other components known in the art, and the present application does not make a limitation on the other components.

[0144] The outer package can be a hard shell. For example, a hard plastic shell, an aluminum shell, a steel shell, etc.

[0145] The outer package can also be a soft package. For example, a bag-type soft package. The material of the soft package can be plastic. For example, the plastic can include, but is not limited to, at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0146] Based on the same inventive concept, the present application provides a power utilization device, which includes the secondary battery described above.

[0147] The electric device can include, but is not limited to, a notebook computer, a pen input computer, a mobile computer, an electronic book player, a portable telephone, a portable facsimile, a portable copying machine, a portable printer, a headphone, a video recorder, a liquid crystal television, a portable cleaner, a portable CD player, a mini disc, a transceiver, an electronic notebook, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, an automobile, a motorcycle, a power-assisted bicycle, a bicycle, a lighting appliance, a toy, a game machine, a clock, a power tool, a flashlight, a camera, a household large storage battery, and a lithium ion capacitor.

[0148] The present application is described in detail below by way of examples and comparative examples:

[0149] The present application is described in detail below by way of examples and comparative examples:

[0150] (I) Test method and equipment

[0151] (1) Sampling method of negative electrode tab and negative electrode active material

[0152] A lithium ion battery discharged at 0.2C to 2.0V was disassembled, and the negative electrode tab was taken out. After being soaked in dimethyl carbonate (DMC) for 20 min, the negative electrode tab was rinsed with DMC and acetone in turn. Then the negative electrode tab was placed in an oven and baked at 80°C for 12 hours to obtain a treated negative electrode tab sample. The negative electrode tab sample used in the following tests of the compaction density PD of the negative electrode active material layer and the porosity P of the negative electrode active material layer was sampled by the above method.

[0153] The negative electrode active material layer on the negative electrode tab was scraped off with a doctor blade, and the scraped powder was heat-treated at 400°C for 4 hours in a tube furnace under argon protection to obtain a negative electrode active material powder sample. The negative electrode active material sample used in the following tests of X-ray diffraction (XRD), the gravimetric capacity and the first efficiency of the negative electrode active material, the maximum inscribed circle diameter D of the internal pore structure, the pore volume V of the external pore structure, the true density p of the negative electrode active material, the Dv50 of the negative electrode active material, the specific surface area S of the negative electrode active material, and the elemental analysis was sampled by the above method.

[0154] (2) Test of apparent density of negative electrode material

[0155] According to the GB / T 26930.3-2011 standard, the apparent density of the negative electrode material is tested by using butanol as the impregnation solvent.

[0156] (3) External force crushing method of negative electrode material

[0157] The negative electrode material is crushed by using an IKA grinder (Model MultiDrive control MT Package). The specific parameters are as follows: 20 g of negative electrode material powder is taken, the grinder speed is 10,000 rpm, and the crushed powder is taken out after 30 s of crushing for testing.

[0158] (4) Negative electrode material adsorption test:

[0159] The pore volume of the external pore structure of the negative electrode material is tested by using an ASAP2460-physical adsorption analyzer. Specifically, after the measured powder material is dried and degassed for pretreatment, the adsorption amount of the material to the test gas nitrogen under different pressures is tested by using the ASAP2460-physical adsorption analyzer, and the adsorption and desorption isotherms are drawn. According to the shape of the hysteresis loop, the shape of the pores is determined, the DFT model is used to fit the pore size distribution curve of the micropores, and then the pore size and pore volume information of the negative electrode material are obtained.

[0160] (5) Dv50 test of negative electrode active material:

[0161] The negative electrode active material is taken, and the particle size distribution of the negative electrode active material is determined according to the GB / T 19077-2016 standard by using a laser particle size analyzer (Malvern, UK, Model: Mastersizer2000E).

[0162] (6) Specific surface area test of negative electrode active material:

[0163] After the measured negative electrode active material is dried in a vacuum drying box, it is loaded into a sample tube, and the specific surface area S of the measured negative electrode active material is tested by using a specific surface area analyzer (Tristar II 3020M) through nitrogen adsorption / desorption method. Specifically, the test is performed according to the GB / T 19587-2017 standard.

[0164] (7) Elemental analysis test:

[0165] The mass ratio a of the element with relatively large atomic mass to carbon in the negative electrode material is tested by using an inductively coupled plasma emission spectrometer (ICP-OES). 0.5 g of the negative electrode active material to be tested is weighed, mixed with 10 mL of concentrated HNO3, and subjected to microwave digestion. The digested solution is introduced into an inductively coupled plasma (ICP) light source. The ICP-OES device detects the content of different elements according to the characteristic radiation energy emitted by the outer electrons of the gaseous atoms in the sample material when they return from the excited state to the ground state after being excited.

[0166] (8) X-ray diffraction (XRD) test:

[0167] The test method of the diffraction peak of the crystal face of the negative electrode material: the graphite of the negative electrode active material is tested by using an X-ray powder diffractometer (XRD, instrument model: Bruker D8 ADVANCE), and the target is Cu Kα; the voltage and current are 40 KV / 40 mA, the scanning angle range is 5° to 80°, the scanning step is 0.00836°, and the time for each step is 0.3 s. In the obtained XRD spectrum, the characteristic peak of disordered carbon (i.e., the first diffraction peak) and the characteristic peak of ordered carbon (i.e., the second diffraction peak) are determined, the peak intensity of the disordered carbon characteristic peak and the peak intensity of the ordered carbon characteristic peak are read, and the ratio A of the peak intensity of the ordered carbon characteristic peak to the peak intensity of the disordered carbon characteristic peak is calculated.

[0168] (9) Raman test:

[0169] The test method of the Raman of the negative electrode material: the particles in the area are scanned by using a laser microscopic confocal Raman spectrometer (Raman, HREvolution, HORIBA Scientific Instrument Division), and the D peak and the G peak of all the particles in the area range are obtained. The data are processed by using LabSpec software to obtain the peak intensity of the D peak and the G peak of each particle, which are I D and I G respectively. The wavelength of the laser of the Raman spectrometer can be in the range of 532 nm to 785 nm. The value of ID / IG in the present application is the average value of the ratio of I D and I G of all the particles measured in the range. The D peak: generally near 1350±50 cm -1 , caused by the radial breathing mode of the symmetric stretching vibration of sp 2 carbon atoms in the aromatic ring (structural defect); the G peak: appears near 1580±50 cm cm -1 , caused by the stretching vibration between sp 2 carbon atoms, which corresponds to the vibration of the E2g optical phonon at the center of the Brillouin zone (carbon atom in-plane vibration).

[0170] (10) Test of the specific capacity and the first efficiency of the negative electrode active material:

[0171] The negative active material, the binder styrene-butadiene rubber, and sodium carboxymethyl cellulose (CMC-Na) were mixed in a mass ratio of 97:1.5:1.5, then deionized water was added as a solvent and stirred uniformly to prepare a negative electrode slurry with a solid content of 40 wt%. The negative electrode slurry was uniformly coated on one surface of a negative current collector copper foil with a thickness of 10 μm, and the single-sided coating thickness was 60 microns. The negative electrode sheet was dried at 85°C to obtain a negative electrode sheet. The negative electrode sheet was cut into a circular sheet with a diameter of 14 mm and used as a working electrode. A lithium sheet was used as a counter electrode, a polyethylene (PE) film with a thickness of 7 μm was used as a separator, and a test electrolyte was injected to assemble a coin-type battery.

[0172] The coin-type battery was subjected to charge-discharge cycling. The coin-type battery was first discharged at 0.05C to 0 mV, then discharged at 0 mV to 20 μA, and the first discharge specific capacity of the coin-type battery was recorded. Then the coin-type battery was charged at 0.05C to 2.5V, and the first charge specific capacity of the coin-type battery was recorded. The mass of the negative active material in the negative electrode sheet was calculated according to the coating weight and area of the negative electrode slurry in the above sheet preparation process. The first efficiency and the gram capacity were calculated by the following expressions:

[0173] First efficiency = first charge specific capacity / first discharge specific capacity x 100%; negative active material gram capacity Q = first charge specific capacity / mass of negative active material, unit: mAh / g.

[0174] (11) Test energy density

[0175] The energy density was tested by the lithium ion battery prepared by the preparation method of the lithium ion battery provided in Example 1. Five lithium ion batteries were taken from each group of tested lithium ion batteries, and the lithium ion batteries were repeatedly charged and discharged by the following steps, and the discharge capacity retention rate of the lithium ion battery was calculated.

[0176] The first charge and discharge were carried out in an environment of 25°C, the constant current charging was carried out at a charging current of 1C until the charging cutoff voltage was reached, then the constant voltage charging was carried out, and then the constant current discharging was carried out at a discharging current of 1C until the discharging cutoff voltage was reached, and the discharge capacity of the first cycle was recorded. The discharge capacity of the 800th cycle was recorded after 800 cycles of charging and discharging. The charging cutoff voltage of the lithium ion battery using the negative active material in the present application was 4.53V, and the discharging cutoff voltage was 2.0V.

[0177] The cycle performance was calculated by the following expression:

[0178] Cycle capacity retention rate (%) = (discharge capacity of the 1000th cycle / discharge capacity of the first cycle) x 100%.

[0179] Cycling expansion rate (%) = (thickness of lithium ion battery at 1000th cycle / thickness of lithium ion battery at first cycle) x 100%.

[0180] (12) Test the rate discharge capacity retention rate:

[0181] Take 5 lithium ion batteries from each group of tested lithium ion batteries, and perform the first charge and discharge in an environment of 25°C. Perform constant current charging under a charge current of 0.2C until the charge cut-off voltage of 4.53V, and then perform constant voltage charging under the charge cut-off voltage to 0.02C, and then perform constant current discharging under a discharge current of 0.2C to the discharge cut-off voltage of 2.0V to obtain the 0.2C average discharge capacity of the lithium ion battery. Then repeat the above charging process, and then perform constant current discharging under a discharge current of 5C to the discharge cut-off voltage to obtain the 5C average discharge capacity of the lithium ion battery.

[0182] The rate discharge capacity retention rate is calculated by the following expression:

[0183] 5C discharge capacity retention rate = (5C average discharge capacity / 0.2C average discharge capacity) x 100%

[0184] (12) Test the low-temperature capacity retention rate

[0185] Take 5 lithium ion batteries from each group of tested lithium ion batteries, and perform the first charge and discharge in an environment of 25°C. Perform constant current charging under a charge current of 0.2C until the charge cut-off voltage of 4.53V, and then perform constant voltage charging under the charge cut-off voltage to 0.02C, and then perform constant current discharging under a discharge current of 0.2C to the discharge cut-off voltage of 2.0V to obtain the 0.2C average discharge capacity of the lithium ion battery at 25°C. Perform constant current charging under a charge current of 0.2C until the charge cut-off voltage, and then perform constant voltage charging under the charge cut-off voltage to 0.02C, and then lower the environment temperature to -20°C and stand for 3h, and then perform constant current discharging under a discharge current of 0.2C to the discharge cut-off voltage in an environment of -20°C to obtain the 0.2C average discharge capacity of the lithium ion battery at -20°C.

[0186] The low-temperature capacity retention rate is calculated according to the following expression:

[0187] Low-temperature capacity retention rate = (-20°C average discharge capacity / 25°C average discharge capacity) x 100%.

[0188] (II) Preparation

[0189] Example 1

[0190] <Preparation of the negative electrode material>

[0191] S1, take 20g of SiC (Dv 50 = 13 pm) powder was placed in a rotary furnace and heated to 900 °C (first temperature condition) under a nitrogen atmosphere, and held at the first temperature condition. A chlorine gas atmosphere with a chlorine content of 50 wt% was introduced for 3 h (first time) at the first temperature condition. The temperature was then lowered to 750 °C (second temperature condition), and a chlorine gas atmosphere was introduced for 10 h (second time) at the second temperature condition. A hydrogen gas atmosphere with a hydrogen content of 5 wt% and argon was introduced for 5 h at the second temperature condition to further remove impurities. Finally, the temperature was lowered under a nitrogen atmosphere to obtain the negative electrode material.

[0192] S2, the negative electrode material was placed in a rotary furnace and heated to 850 °C (third temperature condition) under a nitrogen atmosphere, and held at the third temperature condition. A methane gas atmosphere with a methane content of 20 wt% and argon was introduced for 6 h at the third temperature condition. Finally, the temperature was lowered under a nitrogen atmosphere to obtain the negative electrode material containing a carbon layer.

[0193] <Manufacture of a lithium ion battery>

[0194] The positive electrode sheet, the separator, and the negative electrode sheet were sequentially stacked in order with the separator between the positive electrode sheet and the negative electrode sheet to act as a barrier, and then wound to obtain an electrode assembly. After welding the tabs, the electrode assembly was placed in an aluminum plastic film packaging bag and dried in a vacuum oven at 80 °C for 12 hours to remove water. The above prepared electrolyte solution was injected, and the lithium ion battery was obtained after vacuum packaging, standing, formation, degassing, and edge cutting processes. The design potential interval of the lithium ion battery was 2.0-4.53 V.

[0195] The above negative electrode sheet was prepared as follows: the negative electrode active material, the binder styrene-butadiene rubber, and carboxymethyl cellulose sodium (CMC-Na) were mixed in a mass ratio of 97:1.5:1.5, and then deionized water was added as a solvent and stirred uniformly to prepare a negative electrode slurry with a solid content of 40 wt%. The negative electrode slurry was uniformly coated on one surface of a negative electrode current collector copper foil with a thickness of 6 pm, and dried at 85 °C to obtain a negative electrode sheet with a single-side coated negative electrode active material layer with a thickness of 80 pm. The above steps were repeated on the other surface of the negative electrode current collector copper foil to obtain a negative electrode sheet with a double-side coated negative electrode active material layer. After cold pressing, sheet cutting, and slitting, the negative electrode sheet was obtained.

[0196] The positive electrode tab is prepared by the following method: the positive electrode active material lithium cobaltate, conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 97:1.4:1.6, N-methyl pyrrolidone (NMP) is added as a solvent and stirred uniformly to prepare a positive electrode slurry with a solid content of 72 wt%. The positive electrode slurry is uniformly coated on one surface of a positive electrode current collector aluminum foil with a thickness of 10 μm, dried at 85°C to obtain a positive electrode tab with a single-sided coated positive electrode active material layer; the above steps are repeated on the other surface of the positive electrode current collector aluminum foil to obtain a positive electrode tab with a double-sided coated positive electrode active material layer. Then, after cold pressing, cutting, and slitting, the positive electrode tab is obtained, and the N / P ratio of the positive and negative electrodes is set to 1.0, i.e., the ratio of the capacity per unit area of the negative electrode to the capacity per unit area of the positive electrode is 1.0.

[0197] The electrolyte is prepared by the following method: in a dry argon glove box, ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) are mixed in a mass ratio of 1:1:1 to obtain an organic solvent; LiPF6 is dissolved in the above organic solvent, and fluoroethylene carbonate (FEC) is added and mixed uniformly to obtain the electrolyte. Based on the total mass of the electrolyte, the mass percentage of LiPF6 is 12.5%, the mass percentage of FEC is 5%, and the balance is the organic solvent.

[0198] The above-mentioned separator uses a polyethylene (PE) film with a thickness of 7 μm as the separator.

[0199] Example 2

[0200] The same steps and parameters as in Example 1, except that the first temperature condition in step S1 is different; the first temperature condition is 950°C.

[0201] The XRD test pattern of Example 2 is shown in Figure 1 To facilitate accurate determination of the ratio A of the peak intensity of the second diffraction peak to the peak intensity of the first diffraction peak in the XRD, the Figure 1 is fitted to obtain Figure 2 .

[0202] Example 3

[0203] The same steps and parameters as in Example 1, except that the first temperature condition in step S1 is different; the first temperature condition is 1000°C.

[0204] Example 4

[0205] The same steps and parameters as in Example 1, except that the first temperature condition in step S1 is different; the first temperature condition is 1100°C.

[0206] Example 5

[0207] The same steps and parameters as in example 1, except in step S1 ; the first temperature condition is 1200°C.

[0208] Example 6

[0209] The same steps and parameters as in example 1, except in step S1 ; the first temperature condition is 700°C, the second temperature condition is 700°C, the second time is 24 hours.

[0210] Example 7

[0211] The same steps and parameters as in example 1, except in step S1 ; the second time is 20 hours.

[0212] Example 8

[0213] The same steps and parameters as in example 1, except in step S1 ; the second time is 7 hours.

[0214] Example 9

[0215] The same steps and parameters as in example 1, except in step S1 ; the second time is 5 hours.

[0216] Example 10

[0217] The same steps and parameters as in example 1, except in step S1 ; the second time is 3 hours.

[0218] Example 11

[0219] The same steps and parameters as in example 1, except in step S1 ; the second time is 2.5 hours.

[0220] Example 11

[0221] The same steps and parameters as in example 1, except in step S1 ; the second time is 2.5 hours.

[0222] Example 12

[0223] The same steps and parameters as in example 1, except in step S1 ; SiC is replaced by TiC powder (Dv5013 μm), the first temperature condition is replaced by 600°C, the first time is 1.5 hours, the second temperature condition is 500°C, the second time is 10 hours.

[0224] Example 13

[0225] The same steps and parameters as in example 1, except in step S1 ; SiC is replaced by ZrC powder (Dv5013 μm), the first temperature condition is replaced by 600°C, the first time is 1.5 hours, the second temperature condition is 500°C, the second time is 10 hours. v5013 μm), the first temperature condition is changed to 700°C, the first time is 2 hours, the second temperature condition is 400°C, and the second time is 10 hours.

[0226] Comparative Example 1

[0227] Without using the preparation steps of S1-S2 provided in Example 1, directly using graphite as the negative active material to prepare a lithium ion battery.

[0228] And the N / P ratio of the positive and negative electrodes in the lithium ion battery is set to 1.04, and the potential interval is adjusted to 3.0V to 4.48V (i.e. the charge cut-off voltage is adjusted to 4.48V, and the discharge cut-off voltage is adjusted to 3.0V).

[0229] Comparative Example 2

[0230] The same steps and parameters as in Example 1, except that the first temperature condition in step S1 is different; the first temperature condition is 1600°C.

[0231] Comparative Example 3

[0232] The same steps and parameters as in Example 1, except that the first temperature condition in step S1 is 400°C, the first heat treatment time is 1.5 hours, the second heat treatment temperature is 500°C, and the second heat treatment time is 24 hours.

[0233] The peak intensity ratio A of the XRD obtained in each example and comparative example, the I D / I G , the element M and its content m, the apparent density, the pore size, the pore volume, the specific surface area, the D v 50See Table 1 below.

[0234] Table 1

[0235]

[0236]

[0237] The test results of the specific capacity, the initial coulombic efficiency ICE, the energy density ratio of Comparative Example 1, the capacity retention rate after 1000 cycles, the expansion rate after 1000 cycles, the 5C rate discharge capacity retention rate, and the low-temperature capacity retention rate of each example and comparative example are shown in Table 2 below.

[0238] Table 2

[0239]

[0240] As can be seen from Tables 1-2, when the peak intensity ratio A of the second diffraction peak to the first diffraction peak in the XRD spectrum is between 0.8-20, the specific capacity is improved, and the cycle performance is also improved.

[0241] Obviously, many modifications and variations of the present application are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims and their equivalents, the application can be practiced otherwise than as specifically described.

Claims

1. A negative electrode material, characterized by, The negative electrode material is a porous carbon particle; wherein The XRD pattern of the negative electrode material comprises a first diffraction peak and a second diffraction peak at 10°-30°, the half-peak width of the first diffraction peak is greater than that of the second diffraction peak, and the ratio of the peak intensity of the second diffraction peak to that of the first diffraction peak is A, 0.8≤A≤20.

2. The negative electrode material of claim 1, wherein, The Raman spectrum of the negative electrode material includes a D peak and a G peak, a ratio I D / I G of a peak intensity I D of the D peak to a peak intensity I G of the G peak satisfies 0.30≤I D / I G ≤1.

40.

3. The negative electrode material of claim 1, wherein The ratio I D / I G of the peak intensity I D of the D peak to the peak intensity I G of the G peak in the Raman spectrum of the negative electrode material satisfies 0.75≤I D / I G ≤1.

15.

4. The anode material of claim 1, wherein the carbon-based material is selected from the group consisting of graphite, carbon black, and carbon nanotubes. The element M in the negative electrode material is at least one of Ti, Si, Zr, Al, Nb, Cr, Sr, Ba and Ca; The mass content of the element M is m, m≤6.5%, based on the mass of the negative electrode material.

5. The negative electrode material according to any one of claims 1 to 4, wherein A≤6。 6. The negative electrode material of claim 1, wherein, The XRD pattern of the negative electrode material satisfies at least one of the following conditions: (1) the half-peak width of the first diffraction peak is 5°-9°; (2) the diffraction angle of the first diffraction peak is 20°-24°; (3) the half-peak width of the second diffraction peak is 0.5°-1.5°; (4) the diffraction angle of the second diffraction peak is 25.9°-26.9°.

7. The negative electrode material of claim 1, wherein, The negative electrode material comprises a porous carbon skeleton and a carbon layer arranged on the surface of the carbon skeleton.

8. The negative electrode material according to any one of claims 1 to 4, 6 to 7, wherein The negative electrode material satisfies at least one of the following conditions: (1) the pore volume of the negative electrode material is less than or equal to 0.05 cm3 / g 3 / g; (2) the specific surface area of the negative electrode material is 0.5-50 m 2 / g; (3) the pore volume of the negative electrode material after crushing is 0.1-0.9 cm3 / g 3 / g; (4) the specific surface area of the negative electrode material after the crushing treatment is 150-1500 m 2 / g; (5) the pore size of the negative electrode material after crushing treatment is 0.3-2.0 nm; (6) the apparent density of the negative electrode material is 0.5-1.7 g / cm 3 .

9. A secondary battery characterized by comprising: The secondary battery comprises a positive electrode sheet, a negative electrode sheet and an electrolyte, the negative electrode sheet comprises a current collector and a negative electrode active material attached to at least one side surface of the current collector, wherein The negative electrode active material comprises the negative electrode material according to any one of claims 1-8.

10. An electrical device, characterized by The secondary battery comprises: The secondary battery according to claim 9.

Images