CN115818637B - Modified graphite material and preparation method thereof, negative plate, battery and power utilization device - Google Patents
Modified graphite material and preparation method thereof, negative plate, battery and power utilization device Download PDFInfo
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- CN115818637B CN115818637B CN202211475189.0A CN202211475189A CN115818637B CN 115818637 B CN115818637 B CN 115818637B CN 202211475189 A CN202211475189 A CN 202211475189A CN 115818637 B CN115818637 B CN 115818637B
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- 238000002360 preparation method Methods 0.000 title abstract description 14
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- 239000011591 potassium Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 229910001414 potassium ion Inorganic materials 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 235000015424 sodium Nutrition 0.000 description 1
- WBHQBSYUUJJSRZ-UHFFFAOYSA-M sodium bisulfate Chemical compound [Na+].OS([O-])(=O)=O WBHQBSYUUJJSRZ-UHFFFAOYSA-M 0.000 description 1
- 229910000342 sodium bisulfate Inorganic materials 0.000 description 1
- MNWBNISUBARLIT-UHFFFAOYSA-N sodium cyanide Chemical compound [Na+].N#[C-] MNWBNISUBARLIT-UHFFFAOYSA-N 0.000 description 1
- 229910001545 sodium hexafluoroantimonate(V) Inorganic materials 0.000 description 1
- 229910001542 sodium hexafluoroarsenate(V) Inorganic materials 0.000 description 1
- BAZAXWOYCMUHIX-UHFFFAOYSA-M sodium perchlorate Chemical compound [Na+].[O-]Cl(=O)(=O)=O BAZAXWOYCMUHIX-UHFFFAOYSA-M 0.000 description 1
- 229910001488 sodium perchlorate Inorganic materials 0.000 description 1
- NNMHYFLPFNGQFZ-UHFFFAOYSA-M sodium polyacrylate Chemical compound [Na+].[O-]C(=O)C=C NNMHYFLPFNGQFZ-UHFFFAOYSA-M 0.000 description 1
- 229910001495 sodium tetrafluoroborate Inorganic materials 0.000 description 1
- VGTPCRGMBIAPIM-UHFFFAOYSA-M sodium thiocyanate Chemical compound [Na+].[S-]C#N VGTPCRGMBIAPIM-UHFFFAOYSA-M 0.000 description 1
- 241000894007 species Species 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
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Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention relates to a modified graphite material and a preparation method thereof, a negative plate, a battery and an electric device, wherein the water contact angle theta of the modified graphite material is less than or equal to 140 degrees at 25+/-5 ℃; the mass ratio of oxygen elements contained on the surface of the modified graphite material to the surface of the modified graphite material is T, and the T satisfies the following conditions: t is more than or equal to 3wt%. When the modified graphite material is applied to the preparation of batteries, good cohesiveness can be kept between the modified graphite materials and the binder, so that the compaction density of the negative plate is improved, and the overall energy density of the batteries can be improved.
Description
Technical Field
The invention relates to the technical field of batteries, in particular to a modified graphite material and a preparation method thereof, a negative plate, a battery and an electric device.
Background
Secondary batteries such as lithium ion batteries are increasingly widely used due to the characteristics of cleanliness and reproducibility, and mainly rely on the transmission and movement of active ions such as lithium ions between a positive electrode and a negative electrode to generate electric energy.
In recent years, with the rapid development of new energy industries, the requirements of people on new energy vehicles such as electric automobiles, electric bicycles and the like are larger, the performance requirements of the new energy vehicles are higher, and the secondary batteries are important power sources of the electric automobiles, so that the requirements of people on the energy density of the secondary batteries are higher.
With the increase of demand, the energy density of conventional secondary batteries is increasingly difficult to meet the demands of people, and needs to be further improved.
Disclosure of Invention
Based on this, it is necessary to provide a modified graphite material, a method for producing the same, a negative electrode sheet, a battery, and an electric device, in order to increase the energy density of the secondary battery.
The application is realized by the following technical scheme.
In a first aspect of the present application, there is provided a modified graphite material characterized in that the modified graphite material has a water contact angle θ of 140 ° or less at 25±5 ℃;
the mass ratio of oxygen elements contained on the surface of the modified graphite material to the surface of the modified graphite material is T, and the T satisfies the following conditions: t is more than or equal to 3wt%.
In the modified graphite material, on one hand, the mass ratio of oxygen elements on the surface of the modified graphite material is more than or equal to 3wt%, and the oxygen elements can increase the bonding capacity among graphite particles, and on the other hand, the water contact angle theta is less than or equal to 140 degrees, so that the modified graphite material maintains good bonding capacity with a binder, and when the modified graphite material is applied to the preparation of a secondary battery, good bonding property can be maintained between the modified graphite materials and the binder, thereby improving the compaction density of a negative plate, and further improving the overall energy density of the battery.
In some of these embodiments, the modified graphite material has a water contact angle θ at 25±5 ℃ that satisfies: theta is more than or equal to 130 degrees and less than or equal to 140 degrees;
alternatively, 130℃or more and θ or less than 135 ℃.
The water contact angle theta of the modified graphite material at 25+/-5 ℃ is further regulated and controlled to be kept in a specific range, so that the wettability of the modified graphite material in electrolyte is effectively improved while the excellent bonding capability with a binder is maintained, the compatibility of a negative electrode plate and the electrolyte is improved, the transmission capability of active ions such as lithium ions in a negative electrode is improved, and the energy density of a battery is further improved.
In some of these embodiments, T satisfies: t is more than or equal to 3% and less than or equal to 5%;
Alternatively, T is 3% or more and 4% or less.
In some of these embodiments, on the surface of the modified graphite material, the mass ratio of oxygen element to carbon element is O/C, where O/C satisfies: O/C is more than or equal to 0.03, and is optionally more than or equal to 0.03 and less than or equal to 0.06.
The oxygen element content on the surface of the modified graphite material can improve the hydrophilicity of the modified graphite material, the mass ratio of the surface of the modified graphite material is further adjusted, the bonding capacity between graphite particles is further increased, the water contact angle of the modified graphite material is reduced, and the bonding capacity between the modified graphite material and the binder is further improved.
In some embodiments, the surface of the modified graphite material is an interface layer of the modified graphite material and gas or vacuum, and the thickness of the interface layer is 0.1 nm-10 nm;
Optionally, the thickness of the interface layer is 5 nm-10 nm.
In some embodiments, the mass ratio of oxygen element contained on the surface of the modified graphite material to the surface of the modified graphite material is tested by using an X-ray photoelectron spectrometer.
In some of these embodiments, the oxygen element bonds with a carbon element of the modified graphite material surface at the modified graphite material surface to form a functional group, the functional group comprising at least one of C-O and c=o.
In some of these embodiments, the modified graphite material satisfies at least one of the following conditions (a) - (c):
(a) The specific surface area of the modified graphite material is 1.4m 2/g～2.2m2/g;
Optionally, the specific surface area of the modified graphite material is 1.5m 2/g～2.1m2/g;
(b) The true density of the modified graphite material is 2.08g/cm 3～2.39g/cm3;
Optionally, the modified graphite material has a true density of 2.13g/cm 3～2.36g/cm3;
(c) The compaction density of the modified graphite material under 5000kg pressure is 1.78 g/cc-2.08 g/cc;
Optionally, the modified graphite material has a compacted density of from 1.82g/cc to 2.03g/cc at a pressure of 5000 kg.
In some of these embodiments, the modified graphite material satisfies at least one of the following conditions (d) to (e):
(d) The gram capacity of the modified graphite material is 340 mAh/g-367 mAh/g;
Optionally, the gram capacity of the modified graphite material is 347 mAh/g-365 mAh/g;
(e) The graphitization degree of the modified graphite material is 91% -96%;
Optionally, the graphitization degree of the modified graphite material is 92% -95%.
In some of these embodiments, the particle size of the modified graphite material satisfies at least one of the following conditions (f) - (g):
(f) The volume average particle diameter Dv50 of the modified graphite material satisfies the following conditions: dv50 is less than or equal to 8.0 mu m and less than or equal to 25.0 mu m; alternatively, 10.0 μm.ltoreq.Dv50.ltoreq.20.0 μm;
(g) The particle size distribution of the modified graphite material meets the following conditions: (Dv 90-Dv 10)/Dv 50 is more than or equal to 0.9 and less than or equal to 1.4;
alternatively, 0.9.ltoreq.Dv 90-Dv 10)/Dv 50.ltoreq.1.2.
In some embodiments, the modified graphite material is obtained by modifying artificial graphite;
optionally, the artificial graphite is prepared from needle coke precursors.
In a second aspect of the present application, there is provided a method for producing a modified graphite material of the first aspect, comprising the steps of:
Providing graphite;
Oxidizing etching treatment is carried out on graphite by adopting oxidizing gas to prepare a modified graphite material; the oxidizing gas contains an oxygen element.
In some of these embodiments, the etching process satisfies at least one of the following conditions (h) to (k):
(h) The temperature of the oxidation etching treatment is 500-1000 ℃ and the time is 0.5-3 h;
(i) The flow rate of the oxidizing gas is 18m 3/h～8m3/h;
(j) The oxidizing gas includes one or more of air, oxygen, and carbon dioxide.
According to a third aspect of the application, there is provided a negative electrode sheet comprising a current collector and a negative electrode active layer provided on the surface of the current collector, wherein the negative electrode active layer comprises the modified graphite material according to the first aspect.
In a fourth aspect of the present application, there is provided a battery including the negative electrode sheet of the third aspect.
In a fifth aspect of the present application, there is provided an electric device comprising the battery of the fourth aspect.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like reference numerals are used to designate like parts throughout the accompanying drawings. In the drawings:
FIG. 1 is a schematic diagram of an embodiment of a battery;
FIG. 2 is an exploded view of FIG. 1;
FIG. 3 is a schematic diagram of an embodiment of a battery pack;
FIG. 4 is an exploded view of FIG. 3;
Fig. 5 is a schematic diagram of an embodiment of an electrical device with a battery as a power source.
Reference numerals illustrate:
1. a battery pack; 2. an upper case; 3. a lower box body; 4. a battery; 41. a housing; 42. an electrode assembly; 43. a cover plate; 5. and (5) an electric device.
Detailed Description
The following detailed description of the present invention will provide further details in order to make the above-mentioned objects, features and advantages of the present invention more comprehensible. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit of the invention, whereby the invention is not limited to the specific embodiments disclosed below.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
In view of the background, it is becoming increasingly difficult for the energy density of conventional secondary batteries to meet the needs of people. In the conventional art, the skilled person is mainly focused on developing new active materials or improving battery structures, but no particular breakthrough and progress has been made so far.
The present inventors have studied to find that: the oxygen-containing functional groups on the surface of the graphite material can increase the bonding capacity among graphite particles, and meanwhile, the overall hydrophobicity of the surface of the graphite material can influence the bonding performance between the graphite particles and the binder, so that the compaction density of the negative electrode plate and the energy density of the battery are influenced.
Based on the above, after a great deal of creative research by the technicians of the application, the modified graphite material capable of improving the energy density of the battery is obtained.
One embodiment of the application provides a modified graphite material, and the water contact angle theta of the modified graphite material at 25+/-5 ℃ is less than or equal to 140 degrees;
the mass ratio of oxygen elements contained on the surface of the modified graphite material to the surface of the modified graphite material is T, and T satisfies the following conditions: t is more than or equal to 3wt%.
In the modified graphite material, on one hand, the mass ratio of oxygen elements on the surface of the modified graphite material is more than or equal to 3wt%, and the oxygen elements can increase the bonding capacity among graphite particles, and on the other hand, the water contact angle theta is less than or equal to 140 degrees, so that the modified graphite material maintains good bonding capacity with a binder, and when the modified graphite material is applied to the preparation of a secondary battery, good bonding property can be maintained between the modified graphite materials and the binder, thereby improving the compaction density of a negative plate, and further improving the overall energy density of the battery.
It should be noted that, unlike the "surface" which is abstract in mathematical geometry, in the field of physical and chemical engineering, the "surface" of an object is a physical layer with entities, where the surface of a solid refers to a solid-gas interface or a solid-liquid interface layer, which is actually a physical layer composed of one or several atomic layers of condensed substances near a gas or vacuum.
In some embodiments, the mass ratio of oxygen element contained on the surface of the modified graphite material to the surface of the modified graphite material is tested by using an X-ray photoelectron spectrometer.
It can be understood that the mass ratio of the oxygen element contained on the surface of the modified graphite material to the surface of the modified graphite material is tested by adopting an X-ray photoelectron spectrometer, namely, the result detected by the X-ray photoelectron spectrometer is the content of the oxygen element on the surface of the modified graphite material, and the surface of the modified graphite material is the part of the X-ray passing through the detection part when the X-ray photoelectron spectrometer detects.
Specifically, the X-ray photoelectron spectroscopy test, also called XPS test, is a technology for analyzing chemical properties of a surface of a substance, and specifically, a technology for detecting an internal structure of an object by using absorption and scattering characteristics of X-rays when the X-rays pass through the surface of the object. XPS can measure element composition, empirical formula, element chemical state and electron state in the material, uses a beam of X-ray to excite solid surface, at the same time measures the kinetic energy of electron emitted from 1-10 nm of analyzed material surface so as to obtain XPS spectrum. The photoelectron spectrum records electrons exceeding a certain kinetic energy, the spectrum peak appears in the photoelectron spectrum as the emission of electrons with a certain characteristic energy in atoms, and the energy and intensity of the photoelectron spectrum peak can be used for qualitatively and quantitatively analyzing the elements contained on the solid surface.
In some embodiments, the surface of the modified graphite material is an interface layer of the modified graphite material and a gas or vacuum, and the thickness of the interface layer is 0.1 nm-10 nm.
Alternatively, the thickness of the interface layer is 5nm to 10nm.
It is understood that the thickness of the interface layer is 0.1nm to 10nm, i.e., the thickness of the portion through which X-rays pass when detected by an X-ray photoelectron spectrometer is 0.1nm to 10nm; further, the wavelength is 5nm to 10nm.
The water contact angle theta of the modified graphite material at 25+/-5 ℃ meets the following conditions: theta is more than or equal to 130 degrees and less than or equal to 140 degrees;
alternatively, 130℃or more and θ or less than 135 ℃.
Further alternatively, 132 θ is less than or equal to 135 °, or 130 θ is less than or equal to 134 °.
The water contact angle theta of the modified graphite material at 25+/-5 ℃ is further regulated and controlled to be kept in a specific range, so that the wettability of the modified graphite material in electrolyte is effectively improved while the excellent bonding capability with a binder is maintained, the compatibility of a negative electrode plate and the electrolyte is improved, the transmission capability of active ions such as lithium ions in a negative electrode is improved, and the energy density of a battery is further improved.
In the above-mentioned "130 ° - θ -140 °," the values include the minimum value and the maximum value of the range, and each value between such minimum value and maximum value, and specific examples include, but are not limited to, the point values and the following point values ：130°、131°、132°、133°、134°、135°、136°、137°、138°、139°、130.5°、131.5°、132.5°、133.5°、134.5°、135.5°、136.5°、137.5°、138.5°、139.5°; or the range composed of any two values, for example, may be 130°～139.5°、130°～138.5°、130°～137.5°、130°～136°、130°～135°、131°～135°、131°～136°、131°～138°、131°～139.5°、132°～139.5°、132°～138°、132°～136°、132°～135°、132°～134°、132°～133°、133°～139°、133°～138°、133°～137°、133°～136°、133°～135°.
In some of these embodiments, T satisfies: t is more than or equal to 3% and less than or equal to 5%.
Further, T is more than or equal to 3% and less than or equal to 4%.
In the above "3% T5%", values include the minimum value and the maximum value of the range, and each value between such minimum value and maximum value, specific examples include, but are not limited to, the point values in the examples and the point values below: 5%, 4%, 3%, 4.5%, 3.5%; or any two values, for example, may be 3.5% to 5%, 4% to 5%, 4.5% to 5%, 3.5% to 4.5%, 3.5% to 4%.
In some of these embodiments, on the surface of the modified graphite material, the mass ratio of oxygen element to carbon element is O/C, where O/C satisfies: O/C is more than or equal to 0.03, and is optionally more than or equal to 0.03 and less than or equal to 0.06.
The oxygen element on the surface of the modified graphite material can promote the hydrophilicity of the modified graphite material, further adjust the mass ratio of the surface of the modified graphite material, further increase the bonding capacity between graphite particles, reduce the water contact angle of the modified graphite material, and further promote the bonding capacity between the modified graphite material and the binder.
In the above "0.03.ltoreq.O/C.ltoreq.0.06", values include the minimum value and the maximum value of the range, and each value between such minimum value and maximum value, and specific examples include, but are not limited to, the dot values in the examples and the dot values below: 0.03, 0.04, 0.05, 0.06; or any two values, for example, may be 0.03 to 0.05, 0.03 to 0.04, 0.04 to 0.06, 0.05 to 0.06.
In some of these embodiments, the oxygen element bonds with the carbon element on the surface of the modified graphite material to form a functional group, the functional group comprising at least one of C-O and c=o.
In some of these embodiments, the modified graphite material has a specific surface area of 1.4m 2/g～2.2m2/g.
Optionally, the modified graphite material has a specific surface area of 1.5m 2/g～2.1m2/g;
in some of these embodiments, the true density of the modified graphite material described above is 2.08g/cm 3～2.39g/cm3.
Optionally, the modified graphite material has a true density of 2.13g/cm 3～2.36g/cm3.
In some of these embodiments, the modified graphite material has a compacted density of from 1.78g/cc to 2.08g/cc at a pressure of 5000 kg.
Alternatively, the modified graphite material has a compacted density of from 1.82g/cc to 2.03g/cc at a pressure of 5000 kg.
In some embodiments, the gram capacity of the modified graphite material is 340mAh/g to 367mAh/g.
Alternatively, the gram capacity of the modified graphite material is 347mAh/g to 365mAh/g.
In some embodiments, the modified graphite material has a graphitization degree of 91% to 96%.
Optionally, the graphitization degree of the modified graphite material is 92% -95%.
In some of these embodiments, the volume average particle diameter Dv50 of the modified graphite material described above satisfies: dv50 is less than or equal to 8.0 mu m and less than or equal to 25.0 mu m; alternatively, 10.0 μm.ltoreq.Dv50.ltoreq.20.0 μm.
In some embodiments, the particle size distribution of the modified graphite material described above satisfies: the ratio of (Dv 90-Dv 10)/Dv 50 is more than or equal to 0.9 and less than or equal to 1.4.
Alternatively, 0.9.ltoreq.Dv 90-Dv 10)/Dv 50.ltoreq.1.2.
In the present application, dv10, dv50 or Dv90 represents: the particle size corresponding to a cumulative volume distribution percentage of material of 10%, 50% or 90%, respectively, can be determined using instruments and methods known in the art. For example, the particle size distribution can be measured by a laser particle size analyzer by referring to GB/T19077-2016 laser diffraction method. The test instrument may be a Mastersizer 2000E laser particle size analyzer, malvern instruments, uk.
Specific surface area of the above materials was measured by measuring specific surface area of solid matters by referring to GB/T19587-2004 gas adsorption BET method.
The True Density (True Density) refers to the actual mass of a solid substance per unit volume of a material in an absolutely dense state, i.e., the Density after removing internal pores or inter-particle voids, can be tested by using detection methods commonly used in the art, such as a gas-volumetric method and an immersion method (pycnometer method), wherein the gas-volumetric method is to determine the volume of a sample to be measured according to the law of conservation of mass of gas in a closed container by using the measured pressure, and finally measure the Density of the sample by using the mass of the sample; the immersion method is to measure the true volume of a sample according to the archimedes principle, and calculate the true density of the sample from the mass of powder, and the immersion method is specifically exemplified by the measurement according to the standard GB/T24586-2009.
The graphitization degree of the modified graphite material was measured using methods known in the art. Specific graphitization degree can be measured using an X-ray diffractometer (Bruker D8 Discover), the measurement can be made with reference to JIS K0131-1996, JB/T4220-2011, the size of D002, and then graphitization degree can be calculated according to the formula g= (0.344-D002)/(0.344-0.3354) ×100%, where D002 is the interlayer spacing in the crystalline structure of artificial graphite expressed in nanometers (nm).
In some embodiments, the modified graphite material is obtained by modifying artificial graphite.
Optionally, the artificial graphite is prepared from needle coke precursors.
The artificial graphite can avoid the surface defects of natural graphite, and further, the needle coke precursor is adopted to prepare the artificial graphite, so that the graphite has lower grain orientation degree (OI value) and can avoid the problems of poor rate performance and poor low-temperature performance caused by crystal anisotropy.
The application also provides a preparation method of the modified graphite material, which comprises the following steps S10-S20.
And step S10, providing graphite.
In some embodiments, the graphite is synthetic graphite.
Optionally, the artificial graphite is prepared from needle coke precursors.
Step S20, introducing oxidizing gas to perform oxidation etching treatment on graphite to prepare a modified graphite material; the oxidizing gas contains an oxygen element.
In some embodiments, the temperature of the oxidation etching treatment is 500-1000 ℃ and the time is 0.5-3 h.
In some embodiments, the flow rate of the oxidizing gas is 18m 3/h～8m3/h.
The water contact angle and the oxygen content of the surface of the modified graphite material can be regulated and controlled by regulating and controlling the technological conditions of the oxidation etching treatment.
In some of these embodiments, the oxidizing gas includes one or more of air, oxygen, and carbon dioxide.
The application further provides a negative plate, the negative plate comprises a current collector and a negative active layer arranged on the surface of the current collector, and the components of the negative active layer comprise the modified graphite material.
In the modified graphite material, on one hand, the mass ratio of oxygen elements on the surface of the modified graphite material is more than or equal to 3wt%, and the oxygen elements can increase the bonding capacity among graphite particles, and on the other hand, the water contact angle theta is less than or equal to 140 degrees, so that the modified graphite material maintains good bonding capacity with a binder, and when the modified graphite material is applied to the preparation of a secondary battery, good bonding property can be maintained between the modified graphite materials and the binder, thereby improving the compaction density of a negative plate, and further improving the overall energy density of the battery.
In some of these embodiments, the modified graphite material is present in the negative electrode active layer at a mass ratio of 55% to 99%.
Optionally, the mass ratio of the modified graphite material in the anode active layer is 80% -99%.
Optionally, the mass ratio of the modified graphite material in the anode active layer is 85% -99%.
In some embodiments, the composition of the negative electrode active layer further includes a negative electrode conductive agent and a negative electrode binder.
In some embodiments, the negative electrode conductive agent may be a conductive material commonly used in the art, including but not limited to: at least one of graphite, carbon nanotubes, nanofibers, carbon black, and graphene. Specifically, the conductive material is at least one selected from SP, KS-6, acetylene black, ketjen black ECP with branched structure, SFG-6, vapor grown carbon fiber VGCF, carbon nanotube CNTs, graphene and composite conductive agent thereof.
The weight ratio of the anode conductive agent in the anode film layer is 0 to 20wt% based on the total weight of the anode active layer.
The negative electrode binder may be at least one binder commonly used in the art, and may be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium Polyacrylate (PAAs), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium Alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).
The weight ratio of the anode binder in the anode active layer is 0 to 30wt% based on the total weight of the anode active layer.
In some of these embodiments, the components of the anode active layer may also optionally include other adjuvants, such as thickening agents, e.g., sodium carboxymethyl cellulose (CMC-Na), and the like. The weight ratio of the other auxiliary agent in the anode active layer is 0 to 15wt% based on the total weight of the anode active layer.
In any embodiment of the present application, the current collector in the negative electrode tab may be a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
In any embodiment of the present application, the negative electrode sheet may be prepared by: dispersing the components for preparing the negative plate in a solvent (such as water) to form negative electrode slurry; and (3) coating the negative electrode slurry on a current collector, and drying, cold pressing and the like to obtain the negative electrode plate.
The application further provides a battery, which comprises the negative plate.
Further, the battery is a secondary battery, and further comprises a positive plate, a diaphragm and electrolyte. The positive electrode sheet, separator and electrolyte are exemplified herein.
[ Positive electrode sheet ]
The positive plate comprises a positive current collector and a positive active layer loaded on the surface of the positive current collector.
The composition of the positive electrode active layer includes a positive electrode active material.
In some of these embodiments, the mass ratio of the positive electrode active material in the positive electrode active layer is 70% to 100%.
In some embodiments, the positive electrode active material may employ a positive electrode active material for a secondary battery, which is well known in the art.
In any embodiment of the present application, the positive electrode active material includes any one of a sodium ion positive electrode active material and a potassium ion positive electrode active material.
As an example, the sodium ion positive electrode active material may include at least one of the following materials: at least one of sodium transition metal oxide, polyanion compound and Prussian blue compound. However, the present application is not limited to these materials, and other conventionally known materials that can be used as a positive electrode active material of a sodium ion battery may be used.
In any embodiment of the present application, the positive electrode active material includes at least one of a sodium transition metal oxide, a polyanionic compound, and a prussian blue-based compound;
Optionally, the positive electrode active material includes at least one of a sodium transition metal oxide and a polyanion compound.
The sodium transition metal oxide has a layered transition metal structure, and in theory, the thickness rebound rate of the layered transition metal structure is larger compared with the rhombic phase of the Prussian blue compound, but in practical application, the Prussian blue compound is easy to absorb water to form crystal water and vacancy defects, so that the thickness rebound rate is increased, and even the structure collapses. Therefore, when the sodium transition metal oxide is used as the positive electrode active material, the thickness rebound rate of the positive electrode sheet is rather smaller.
The anionic structural unit in the polyanion compound is connected into a three-dimensional structure through a covalent bond, so that the structural stability is good, and the thickness rebound rate of the positive plate is lower when the polyanion compound is a positive electrode active material.
As an alternative embodiment of the present application, the transition metal in the sodium transition metal oxide includes at least one of Mn, fe, ni, co, cr, cu, ti, zn, V, zr and Ce. The sodium transition metal oxide is Na xMO2, for example, wherein M at least comprises one or more of Ti, V, mn, co, ni, fe, cr and Cu, and x is more than 0 and less than or equal to 1.
As an alternative embodiment of the present application, the polyanion compound may be a compound having sodium ion, transition metal ion and tetrahedral type (YO 4)n- anion unit, wherein the transition metal includes at least one of Mn, fe, ni, co, cr, cu, ti, zn, V, zr and Ce, Y includes at least one of P, S and Si, and n represents (YO 4)n- valence state).
The polyanionic compound may also be a compound having sodium ion, transition metal ion, tetrahedral type (YO 4)n- anion unit and halogen anion, transition metal includes at least one of Mn, fe, ni, co, cr, cu, ti, zn, V, zr and Ce, Y includes at least one of P, S and Si, n represents (YO 4)n- valence state; halogen may be at least one of F, cl and Br).
The polyanionic compound may also be a compound of the type having sodium ions, tetrahedral (YO 4)n- anion units, polyhedral units (ZO y)m+ and optionally halogen anions. Y comprises at least one of P, S and Si, n represents (YO 4)n- valence; Z represents transition metal, comprises at least one of Mn, fe, ni, co, cr, cu, ti, zn, V, zr and Ce), m represents (ZO y)m+ valence; halogen may be at least one of F, cl and Br).
The polyanion compound is at least one of NaFePO 4、Na3V2(PO4)3 (sodium vanadium phosphate, NVP for short), na 4Fe3(PO4)2(P2O7)、NaM'PO4 F (M' is one or more of V, fe, mn and Ni) and Na 3(VOy)2(PO4)2F3-2y (y is more than or equal to 0 and less than or equal to 1).
Prussian blue compounds may be a class of compounds having sodium ions, transition metal ions, and cyanide ions (CN -). The transition metal includes at least one of Mn, fe, ni, co, cr, cu, ti, zn, V, zr and Ce. Prussian blue compounds are, for example, na aMebMe'c(CN)6, where Me and Me' each independently include at least one of Ni, cu, fe, mn, co and Zn, 0 < a.ltoreq.2, 0 < b < 1,0 < c < 1.
In any embodiment of the present application, the components of the positive electrode active layer further include a positive electrode binder, wherein the mass ratio of the positive electrode binder in the positive electrode active layer is 0.05% -10%.
Optionally, the mass ratio of the positive electrode binder in the positive electrode active layer is 0.1% -8%.
The positive electrode binder may be any of various binders commonly used in the art. As an example, the positive electrode binder includes at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, a fluoroacrylate resin, sodium carboxymethyl cellulose, hydroxypropyl cellulose, sodium hydroxymethyl cellulose, potassium hydroxymethyl cellulose, diacetyl cellulose, polyacrylic acid, sodium alginate, styrene butadiene rubber, acrylic butadiene rubber, polypyrrole, polyaniline, and epoxy resin, and guar gum.
In any embodiment of the present application, the components of the positive electrode active layer further include a positive electrode conductive agent, wherein the mass ratio of the positive electrode conductive agent in the positive electrode active layer is 0.05% -8%.
Optionally, the mass ratio of the positive electrode conductive agent in the positive electrode active layer is 0.1% -6%.
As an example, the positive electrode conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
The positive current collector may be a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
In some embodiments, the positive electrode sheet may be prepared by: dispersing the above components for preparing the positive electrode sheet, such as the positive electrode active material, the positive electrode conductive agent, the positive electrode binder and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; and (3) coating the positive electrode slurry on a positive electrode current collector, and obtaining the positive electrode plate after the procedures of drying, cold pressing and the like.
The positive electrode sheet, the negative electrode sheet and the separator may be manufactured into an electrode assembly through a winding process or a lamination process. The electrolyte serves to conduct ions between the positive electrode and the negative electrode.
[ Electrolyte ]
The electrolyte comprises electrolyte salt and solvent
In some embodiments, the electrolyte salt may be selected from electrolyte salts commonly used in the art, including lithium ion electrolyte salts and sodium ion electrolyte salts.
As an example, the lithium ion electrolyte salt is selected from: one or more of lithium hexafluorophosphate (LiPF 6), lithium tetrafluoroborate (LiBF 4), lithium perchlorate (LiClO 4), lithium hexafluoroarsenate (LiAsF 6), lithium bis (fluorosulfonyl) imide (LiFSI), lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalato borate (LIDFOB), lithium dioxaato borate (LiBOB), lithium difluorophosphate (LiPO 2F2), lithium difluorodioxaato phosphate (LIDFOP), li (FSO 2)2N、LiCF3SO3) and lithium tetrafluorooxalato phosphate (LiTFOP).
As an example, the sodium ion electrolyte salt is selected from: one or more of sodium hexafluorophosphate (NaPF6)、NaClO4,NaAIClh,NaFeClh,NaBF4,NaBClh,NaNO3,NaPOFA,NaSCN,NaCN,NaAsF6,NaCF3CO2,NaSbF6,NaC6HsCO2,Na(CH3)C6H4SO3,NaHSO4,NaB(C6Hs)4.
In any embodiment of the present application, the solvent may be selected from one or more of fluoroethylene carbonate (FEC), ethylene Carbonate (EC), propylene Carbonate (PC), ethylmethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), butylene Carbonate (BC), methyl Formate (MF), methyl Acetate (MA), ethyl Acetate (EA), propyl Acetate (PA), methyl Propionate (MP), ethyl Propionate (EP), propyl Propionate (PP), methyl Butyrate (MB), ethyl Butyrate (EB), 1, 4-butyrolactone (GBL), sulfolane (SF), dimethylsulfone (MSM), methylsulfone (EMS) and diethylsulfone (ESE).
In any embodiment of the present application, the concentration of the electrolyte salt is generally 0.5mol/L to 15mol/L.
In any embodiment of the application, the electrolyte further optionally includes an additive. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives capable of improving certain properties of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high or low temperature performance of the battery, and the like.
[ Isolation Membrane ]
The isolating film is arranged between the positive pole piece and the negative pole piece.
The type of the separator is not particularly limited, and any known porous separator having good chemical stability and mechanical stability can be used.
In some embodiments, the material of the isolating film may be at least one selected from glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of the respective layers may be the same or different, and are not particularly limited.
In some embodiments, the battery is a lithium ion battery.
In some embodiments, the battery further comprises a housing for packaging the positive electrode sheet, the negative electrode sheet, the separator and the electrolyte.
In some embodiments, the housing may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, or the like. But may also be a flexible bag, such as a bag-type flexible bag. The material of the flexible bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.
The shape of the battery is not particularly limited in the present application, and may be cylindrical, square, or any other shape. For example, fig. 1 is a battery 4 of a square structure as one example.
In some embodiments, referring to fig. 2, the housing may include a shell 41 and a cover plate 43. The housing 41 may include a bottom plate and a side plate connected to the bottom plate, where the bottom plate and the side plate enclose a receiving chamber. The housing 41 has an opening communicating with the accommodation chamber, and the cover plate 43 can be provided to cover the opening to close the accommodation chamber.
The positive electrode tab, the negative electrode tab, and the separator may be formed into the electrode assembly 42 through a winding process or a lamination process. The electrode assembly 42 is packaged in the receiving chamber. The electrolyte is impregnated in the electrode assembly 42. The number of electrode assemblies 42 included in the battery 4 may be one or more and may be adjusted as desired.
The application also provides an electric device which comprises the battery.
Further, in the above-mentioned power consumption device, the battery may exist in the form of a battery cell or may exist in the form of a battery pack further assembled.
Fig. 3 and 4 are battery packs 1 as an example. The battery pack 1 includes a battery case and one or more batteries 4 provided in the battery case. The battery box comprises an upper box body 2 and a lower box body 3, wherein the upper box body 2 can be covered on the lower box body 3, and a closed space for a battery 4 is formed.
The plurality of batteries 4 may be arranged in the battery box in any manner.
The battery or the battery pack assembled by the battery can be used as a power source of an electric device and also can be used as an energy storage unit of the electric device.
The electric device may be, but is not limited to, a mobile device (e.g., a cellular phone, a notebook computer, etc.), an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc.
Fig. 5 is an electric device 5 as an example. The electric device 5 is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle or the like. To meet the high power and high energy density requirements of the battery of the power consumer 5, a battery pack may be used.
As another example, the power consumption device may be a mobile phone, a tablet computer, a notebook computer, or the like. The device is generally required to be light and thin, and a battery can be used as a power source.
The invention will be described in connection with specific embodiments, but the invention is not limited thereto, and it will be appreciated that the appended claims outline the scope of the invention, and those skilled in the art, guided by the inventive concept, will appreciate that certain changes made to the embodiments of the invention will be covered by the spirit and scope of the appended claims.
The following are specific examples.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
Example 1
1. The preparation of the modified artificial graphite material comprises the following specific steps:
s1: coarsely crushing needle coke raw materials by a jaw crusher, mechanically grinding and finely crushing, and grading and shaping to obtain precursor particles with the Dv50 particle size of 12 mu m;
S2: mixing the precursor particles with binder asphalt (Dv 50 is 5-8 mu m), stirring at 1200r/min, heating to 560 ℃ for granulating to obtain an intermediate 1 with the particle size Dv50 of 16 mu m; wherein the mass of the pitch is 10% of the mass of the precursor.
S3: and (3) graphitizing the intermediate 1 obtained in the step (S2) at 3000 ℃, and screening to obtain the artificial graphite.
S4: and (3) oxidation etching treatment: the rotary kiln is heated to 600 ℃, the rotating speed of the furnace tube is 3r/min, and the air flow is 3m 3/h. The artificial graphite enters the rotary kiln cavity from the rotary kiln feed inlet at a constant speed through the rotary feeder, oxidation etching treatment is carried out in the cavity for 1.5h, and the modified artificial graphite is obtained after cooling.
S5: testing
(1) Water contact angle test: adding the modified artificial graphite powder into a pre-mold, and pressing and forming, wherein the formed artificial graphite powder can keep liquid drops;
Water contact angle measurements were carried out at 25 c±5 ℃ using a contact angle tester (e.g., SDC-200S): the water drop is dripped on the surface of the formed artificial graphite powder, the quantity of the water drop is 10 mu L+/-1 mu L, the water contact angle is tested 3-5 seconds after the water drop is dripped, specifically, the average value of the angles of the left side and the right side of the water drop is adopted for measuring the water contact angle, and the specific value is automatically fit and read by an instrument.
(2) Gram Capacity test of modified Artificial graphite: after the modified artificial graphite powder is manufactured into a pole piece according to a certain formula, the pole piece-lithium piece semi-button battery is assembled, the button capacitance is obtained through small-rate charge and discharge, and then the gram-capacity parameter is obtained by dividing the capacity by the mass of the pole piece active substance.
(3) The oxygen content and the carbon content of the surface of the modified artificial graphite can be measured by adopting an X-ray photoelectron spectrometer according to the general rule GB/T19500-2004 of the standard X-ray photoelectron spectroscopy analysis method; and further measuring the O/C value and analyzing the main oxygen-containing functional group. The surface depth of the modified artificial graphite obtained by the test in the XPS test is 5-10 nm, and the functional group type can be tested through fitting analysis of software.
XPS can obtain the kind and content of functional groups through fitting analysis of software.
(4) The Specific Surface Area (SSA) of the modified artificial graphite may be tested using methods known in the art. For example, reference may be made to GB/T19587-2017, which is performed by a nitrogen adsorption specific surface area analytical test method, which may be performed by a Tri-Star3020 type specific surface area pore size analytical tester from Micromeritics, inc., U.S.A., and calculated by the BET (Brunauer EMMETT TELLER) method.
(5) The particle sizes Dv10, dv50, dv90 of the modified artificial graphite are the definitions well known in the art, and are respectively as follows: the particle Size of 10%, 50% and 90% of the volume distribution is measured by a laser particle Size analyzer (e.g., MALVERN MASTER Size 3000) with reference to standard GB/T19077.1-2016.
(6) The graphitization degree of the modified artificial graphite was measured using a method known in the art. Specific graphitization degree can be measured using an X-ray diffractometer (Bruker D8 Discover), the measurement can be made with reference to JIS K0131-1996, JB/T4220-2011, the size of D002, and then graphitization degree can be calculated according to the formula g= (0.344-D002)/(0.344-0.3354) ×100%, where D002 is the interlayer spacing in the crystalline structure of artificial graphite expressed in nanometers (nm).
(7) The compacted density of the modified artificial graphite may be tested using methods known in the art. With specific reference to GB/T24533-2009, testing was performed using an electronic pressure tester (e.g. UTM 7305): and placing a certain amount of powder on a special compacting die, setting 5000kg pressure, reading the thickness of the powder under the 5000kg pressure on equipment, and calculating to obtain the compacting density under the 5000kg pressure.
The specific test results are shown in Table 1.
2. The preparation of the negative electrode plate comprises the following specific steps:
Fully stirring and mixing the prepared modified artificial graphite, a conductive agent (Super P), a binder (SBR) and a thickening agent (CMC-Na) in a mass ratio of 96.2:0.8:1.8:1.2 in a proper amount of deionized water to form uniform negative electrode slurry; and (3) coating the negative electrode slurry on the surface of a negative electrode current collector copper foil, and drying and cold pressing to obtain a negative electrode plate.
The compacted density of the negative electrode plate is 1.72g/cm 3, and the areal density is 11.6mg/cm 2.
3. Preparation of positive electrode plate
Fully stirring and mixing a positive electrode active material LiNi 0.5Co0.2Mn0.3O2 (NCM 523), a conductive agent (Super P) and a binder PVDF in a weight ratio of 96.2:2.7:1.1 in a proper amount of NMP to form uniform positive electrode slurry; and (3) coating the positive electrode slurry on the surface of a positive electrode current collector aluminum foil, and drying and cold pressing to obtain a positive electrode plate. The compaction density of the positive electrode plate is 3.45g/cm 3.
The compacted density and the areal density of the pole piece are the meanings known in the art, and the areal density of the pole piece refers to: the weight of the active layer loaded by the pole piece in unit area, and the area density formula: weight of active layer/area of active layer. Wherein the weight of the active layer can be obtained by subtracting the weight of the current collector from the weight of the pole piece.
The compaction of the pole piece refers to the ratio of the pole piece surface density to the active layer thickness, and is one of the reference indexes of the material energy density. The testing method comprises the following steps: the surface density of the pole piece is determined according to the method, the vernier caliper is used for measuring the total thickness of the pole piece, and the thickness of the active layer can be calculated by deducting the thickness of the current collector. And according to the two parameters of the surface density and the thickness, calculating the compaction density of the pole piece.
5. Preparation of electrolyte: ethylene Carbonate (EC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1, and then LiPF 6 is uniformly dissolved in the solution to obtain an electrolyte, wherein the concentration of LiPF 6 is 1mol/L.
6. Isolation film: polyethylene (PE) films are used.
7. Preparation of secondary battery: and sequentially stacking the positive electrode plate, the isolating film and the negative electrode plate, winding to obtain a battery core, loading the battery core into an outer package, adding the electrolyte, and carrying out the procedures of packaging, standing, formation, aging and the like to obtain the secondary battery.
8. Performance test:
(1) The energy density of the secondary battery was tested: charging to 4.2V at normal temperature with 0.33C standard, charging to 0.05C at constant voltage of 4.2V, standing for 10min, discharging to 2.8V at 0.33C, recording discharge capacity, and calculating energy density at discharge.
Energy density (Wh/kg) =discharge capacity (Wh)/mass of lithium ion secondary battery (kg)
The specific results are shown in Table 1.
Examples 2 to 10
Examples 2 to 10 are basically the same as example 1, except that: the temperature or time of the oxidation etching treatment in the step S4 is regulated and controlled to obtain different modified artificial graphite materials, and specific conditions are shown in Table 1.
Other steps and conditions were the same as in example 1, and the test results are shown in Table 1.
Examples 11 to 12
Examples 11 to 12 are basically the same as example 1, except that: the specific conditions for changing the type of the oxidizing gas used in the oxidizing etching process in step S4 are shown in table 1.
Other steps and conditions were the same as in example 1, and the test results are shown in Table 1.
Comparative example 1
Comparative example 1 is substantially the same as example 1 except that step 1 in comparative example 1 is as follows:
s1: coarsely crushing needle coke raw materials by a jaw crusher, mechanically grinding and finely crushing, and grading and shaping to obtain precursor particles with the Dv50 particle size of 12 mu m;
S2: mixing the precursor particles with binder asphalt (Dv 50 is 5-8 mu m), stirring at 1200r/min, heating to 560 ℃ for granulating to obtain an intermediate 1 with the particle size Dv50 of 16 mu m; wherein the mass of the pitch is 10% of the mass of the precursor.
S3: and (3) graphitizing the intermediate 1 obtained in the step (S2) at 3000 ℃, and screening to obtain the artificial graphite.
The remaining steps were the same as in example 1.
Comparative example 2
Comparative example 2 is substantially the same as example 1 except that: the oxidizing gas species of the oxidizing etching process in step S4 were changed to replace air with CF 4, and specific conditions are set forth in table 1.
The remaining steps were the same as in example 1.
The physical parameters and test results related to each example and comparative example are shown in Table 1.
TABLE 1
The letter "/" indicates that this step process is absent.
As shown by the experimental results in the table, the modified graphite material has good bonding capability among graphite particles, improves the bonding capability between the modified graphite material and a binder, and can improve the energy density of a battery when used for preparing the battery.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. The scope of the invention is therefore intended to be covered by the appended claims, and the description and drawings may be interpreted in accordance with the contents of the claims.
Claims (16)
1. The modified graphite material is characterized in that the water contact angle theta of the modified graphite material at 25+/-5 ℃ meets the following conditions: theta is more than or equal to 130 degrees and less than 140 degrees;
The mass ratio of oxygen elements contained on the surface of the modified graphite material to the surface of the modified graphite material is T, and the T satisfies the following conditions: t is more than or equal to 3% and less than 5%;
And on the surface of the modified graphite material, the oxygen element is bonded with the carbon element on the surface of the modified graphite material to form a functional group, and the functional group comprises at least one of C-O and C=O.
2. The modified graphite material of claim 1, wherein the modified graphite material has a water contact angle θ at 25 ℃ ± 5 ℃ that satisfies: θ is more than or equal to 130 degrees and less than or equal to 135 degrees.
3. The modified graphite material of claim 1, wherein T satisfies: t is more than or equal to 3% and less than or equal to 4%.
4. The modified graphite material as set forth in claim 1, wherein the mass ratio of oxygen element to carbon element at the surface of the modified graphite material is O/C, the O/C satisfying: O/C is more than or equal to 0.03.
5. The modified graphite material as set forth in any one of claims 1 to 4, wherein, on the surface of the modified graphite material, the mass ratio of oxygen element to carbon element is O/C, the O/C satisfying: O/C is more than or equal to 0.03 and less than or equal to 0.06.
6. The modified graphite material as claimed in any one of claims 1 to 4, wherein the surface of the modified graphite material is an interface layer of the modified graphite material and a gas or vacuum, and the thickness of the interface layer is 0.1nm to 10nm.
7. The modified graphite material as claimed in any one of claims 1 to 4, wherein the mass ratio of oxygen element contained in the surface of the modified graphite material to the surface of the modified graphite material is measured by an X-ray photoelectron spectrometer.
8. The modified graphite material as set forth in any one of claims 1 to 4, wherein the modified graphite material satisfies at least one of the following conditions (a) to (c):
(a) The specific surface area of the modified graphite material is 1.4m 2/g～2.2m2/g;
(b) The true density of the modified graphite material is 2.08g/cm 3～2.39g/cm3;
(c) The modified graphite material has a compacted density of 1.78g/cc to 2.08g/cc under a pressure of 5000 kg.
9. The modified graphite material as set forth in any one of claims 1 to 4, wherein the modified graphite material satisfies at least one of the following conditions (d) to (e):
(d) The gram capacity of the modified graphite material is 340 mAh/g-367 mAh/g;
(e) The graphitization degree of the modified graphite material is 91% -96%.
10. The modified graphite material as set forth in any one of claims 1 to 4, wherein the modified graphite material has a particle diameter satisfying at least one of the following conditions (f) to (g):
(f) The volume average particle diameter Dv50 of the modified graphite material satisfies the following conditions: dv50 is less than or equal to 8.0 mu m and less than or equal to 25.0 mu m;
(g) The particle size distribution of the modified graphite material meets the following conditions: the ratio of (Dv 90-Dv 10)/Dv 50 is more than or equal to 0.9 and less than or equal to 1.4.
11. The modified graphite material as claimed in any one of claims 1 to 4, wherein the modified graphite material is obtained by modifying artificial graphite.
12. The method for producing a modified graphite material as claimed in any one of claims 1 to 11, comprising the steps of:
Providing graphite;
oxidizing gas is adopted to carry out oxidation etching treatment on the graphite to prepare a modified graphite material;
The oxidizing gas contains an oxygen element.
13. The method of producing a modified graphite material as claimed in claim 12, wherein said etching treatment satisfies at least one of the following conditions (h) to (j):
(h) The temperature of the oxidation etching treatment is 500-1000 ℃ and the time is 0.5-3 h;
(i) The flow rate of the oxidizing gas is 18m 3/h～8m3/h;
(j) The oxidizing gas includes one or more of air, oxygen, and carbon dioxide.
14. A negative electrode sheet, characterized in that the negative electrode sheet comprises a current collector and a negative electrode active layer provided on the surface of the current collector, and the composition of the negative electrode active layer comprises the modified graphite material as defined in any one of claims 1 to 11.
15. A battery comprising the negative electrode sheet according to claim 14.
16. An electrical device comprising the battery of claim 15.
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| JP2009110972A (en) * | 2001-08-10 | 2009-05-21 | Jfe Chemical Corp | Negative electrode material for lithium ion secondary battery and its manufacturing method |
| CN106660798A (en) * | 2014-07-15 | 2017-05-10 | 英默里斯石墨及活性炭瑞士有限公司 | Hydrophilic surface-modified carbonaceous particulate material |
| KR20180012999A (en) * | 2016-07-28 | 2018-02-07 | 에스케이씨 주식회사 | Composite sheet, antenna module and preparation thereof |
| JP2018154548A (en) * | 2017-03-16 | 2018-10-04 | Ｊｆｅスチール株式会社 | Graphite-containing castable refractory and method for producing the same |
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| KR20180118602A (en) * | 2016-01-21 | 2018-10-31 | 이머리스 그래파이트 앤드 카본 스위춰랜드 리미티드 | Carbonaceous materials and methods for their use |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2009110972A (en) * | 2001-08-10 | 2009-05-21 | Jfe Chemical Corp | Negative electrode material for lithium ion secondary battery and its manufacturing method |
| CN106660798A (en) * | 2014-07-15 | 2017-05-10 | 英默里斯石墨及活性炭瑞士有限公司 | Hydrophilic surface-modified carbonaceous particulate material |
| KR20180012999A (en) * | 2016-07-28 | 2018-02-07 | 에스케이씨 주식회사 | Composite sheet, antenna module and preparation thereof |
| JP2018154548A (en) * | 2017-03-16 | 2018-10-04 | Ｊｆｅスチール株式会社 | Graphite-containing castable refractory and method for producing the same |
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