CN111834615B - Composite negative electrode material, preparation method and lithium ion battery - Google Patents
Composite negative electrode material, preparation method and lithium ion battery Download PDFInfo
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- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
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Abstract
The invention discloses a composite cathode material, a preparation method and a lithium ion battery, and relates to the technical field of lithium ion batteries. The composite negative electrode material provided by the invention takes graphite as a main material, takes the cobalt vanadate lithium nanowire bonded with the graphite as a high-capacity provider, and further coats a carbon coating layer on the outer parts of the graphite and the cobalt vanadate lithium nanowire, so that the composite negative electrode material has the characteristics of high specific capacity, long cycle life, good rate capability, strong processability and good safety performance, the specific capacity of the composite negative electrode material can easily reach more than 1000mAh/g, and the requirement of a lithium ion battery on the composite negative electrode material is met.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a composite negative electrode material, a preparation method and a lithium ion battery.
Background
With the advancement of science and technology, the demand of consumers on the performance of electric vehicles and electronic products is higher, and meanwhile, the demand of lithium ion batteries as power providers of electric vehicles and electronic products is higher in terms of capacity.
The cathode material is used as one of the core components of the lithium ion battery, and plays a key role in improving the comprehensive performance of the lithium ion battery. The problem that the capacity of a graphite cathode serving as a cathode material of a conventional lithium ion battery sold in the market is difficult to increase at present is solved, and the capacity of the lithium ion battery is limited to be further increased.
In view of the above-mentioned drawbacks, the inventors of the present invention have finally obtained the present invention through a long period of research and practice.
Disclosure of Invention
In order to solve the technical defects, the technical scheme adopted by the invention is to provide a composite cathode material, which comprises graphite, a lithium cobalt vanadate nanowire and a carbon coating layer, wherein the graphite is a main material of the composite cathode material, the lithium cobalt vanadate nanowire is bonded with the graphite, and the carbon coating layer is coated outside the graphite and the lithium cobalt vanadate nanowire.
Another object of the present invention is to provide a method for preparing the composite anode material, including:
s1: mixing citric acid and ethylene glycol to prepare a solution A;
s2: weighing vanadium salt, cobalt salt and lithium salt to prepare a raw material B;
s3: mixing the raw material B with the solution A, stirring, heating to 120-150 ℃, and preserving heat to obtain sol C;
s4: weighing an alumina molecular sieve, adding the alumina molecular sieve into the sol C, stirring at the temperature of 80-120 ℃, and filtering to obtain particles D;
s5: heating the particles D to 400-700 ℃ in an oxidizing atmosphere, and preserving heat to obtain particles E;
s6: dipping the particle E in an alkali solution, separating insoluble substances, and washing the insoluble substances to be neutral to obtain a lithium cobalt vanadate nanowire;
s7: mixing graphite with the lithium cobalt vanadate nanowire to obtain powder F;
s8: and (3) introducing organic gas into the powder F at the temperature of 800-1200 ℃ to perform chemical vapor deposition to obtain the composite cathode material.
Optionally, the mass ratio of the citric acid to the ethylene glycol in the step S1 ranges from 1:8 to 1: 4.
Optionally, in step S2, the vanadium salt includes at least one of vanadium chloride, ammonium metavanadate, sodium metavanadate, potassium metavanadate, sodium orthovanadate, sodium pyrovanadate, vanadyl sulfate, vanadyl oxalate, and vanadium tetrachloride; the cobalt salt comprises at least one of cobalt chloride, cobaltous chloride, cobalt sulfate, cobaltous sulfate, cobalt nitrate and cobalt acetate; the lithium salt comprises at least one of lithium hydroxide, lithium nitrate, lithium sulfate, lithium chloride, lithium acetate and lithium oxalate; the molar ratio of the vanadium element, the cobalt element and the lithium element in the raw material B is 1:1: 1-1: 1.15.
Optionally, the step of mixing the raw material B with the solution A, stirring and heating to 120-150 ℃, and preserving heat to obtain the sol C comprises: mixing the raw material B with the solution A, stirring and heating to 120-150 ℃, and preserving heat for 1-5 hours to obtain sol C; the mass of the solution A is 10-50 times of that of the raw material B.
Optionally, the step of weighing the alumina molecular sieve, adding the alumina molecular sieve into the sol C, stirring at a temperature of 80-120 ℃, and filtering to obtain particles D includes: weighing an alumina molecular sieve, adding the alumina molecular sieve into the sol C, stirring for 1-10 hours at the temperature of 80-120 ℃, and filtering to obtain particles D; wherein the mass of the sol C is 2-10 times of that of the alumina molecular sieve.
Optionally, heating the particles D to 400-700 ℃ in an oxidizing atmosphere, and preserving heat to obtain particles E includes: heating the particles D to 400-700 ℃ in an oxidizing atmosphere, and preserving heat for 1-5 hours to obtain particles E; wherein the oxidizing atmosphere comprises at least one of an oxygen atmosphere and an air atmosphere.
Optionally, in the step S7, the mass ratio of the graphite to the lithium cobalt vanadate nanowire ranges from 2:1 to 10: 1; the particle size range of the graphite is 5-30 microns.
Optionally, introducing an organic gas into the powder F at a temperature of 800-1200 ℃ to perform chemical vapor deposition, so as to obtain a composite anode material, wherein the composite anode material comprises: introducing organic gas into the powder F at the temperature of 800-1200 ℃, and performing chemical vapor deposition for 5-60 minutes to obtain a composite anode material; wherein the organic gas comprises at least one of methane, ethane, acetylene, acetone, benzene, toluene, and xylene.
The invention further aims to provide a lithium ion battery which comprises the composite anode material.
Compared with the prior art, the invention has the beneficial effects that:
the composite negative electrode material provided by the invention has the advantages that graphite is used as a main material, the cobalt lithium vanadate nanowire bonded with the graphite is used as a high-capacity provider, and a carbon coating layer is further coated outside the graphite and the cobalt lithium vanadate nanowire, so that the composite negative electrode material provided by the invention has the characteristics of high specific capacity, long cycle life, good rate capability, strong processability and good safety performance, the specific capacity of the composite negative electrode material can easily reach more than 1000mAh/g, and the requirement of a lithium ion battery on the composite negative electrode material is met;
2, according to the preparation method of the composite negative electrode material, the cobalt lithium vanadate nanowire is prepared by taking vanadium salt, cobalt salt and lithium salt as raw materials and taking an alumina molecular sieve as a template method, then graphite and the cobalt lithium vanadate nanowire are mixed, and a carbon coating layer is prepared outside the graphite and the cobalt lithium vanadate nanowire, so that the preparation method is simple and low in cost; the prepared composite negative electrode material has the characteristics of high specific capacity, long cycle life, good rate capability, strong processability and good safety performance, and meets the requirements of the lithium ion battery on the composite negative electrode material.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below.
FIG. 1 is a scanning electron micrograph of a composite anode material of the present invention;
FIG. 2 is a graph of the 0.5C cycle life of the composite anode material of the present invention;
fig. 3 is a schematic flow chart of a method for preparing the composite anode material of the present invention.
Detailed Description
The above and further features and advantages of the present invention are described in more detail below with reference to the accompanying drawings.
The graphite cathode material is a traditional cathode material, and the cathode material of the current lithium ion battery is mainly the graphite cathode material; the graphite cathode material has the advantages of high conductivity, excellent processing performance, good electrolyte compatibility and the like, but the capacity of the graphite cathode material is close to the theoretical capacity of the graphite cathode material at present, so the graphite cathode material has the problem of difficult capacity improvement; in order to enable the capacity of the cathode material to meet the requirement of a lithium ion battery, the invention provides a composite cathode material which comprises graphite, a cobalt lithium vanadate nanowire and a carbon coating layer, wherein the graphite is a main material of the composite cathode material, the cobalt lithium vanadate nanowire is bonded with the graphite, and the carbon coating layer is coated outside the graphite and the cobalt lithium vanadate nanowire.
The composite cathode material provided by the invention takes graphite with low cost, high conductivity, excellent processing performance and good electrolyte compatibility as a main material, and on the basis of the traditional graphite cathode material, the graphite and lithium cobalt vanadate (Li) with the specific capacity of 1000mAh/g2Co2V2O8) The nanowires are bonded, so that the cobalt lithium vanadate nanowires are used as a capacity provider of the composite negative electrode material to improve the capacity of the composite negative electrode material; the graphite cathode material is a mature cathode material at present, and the graphite is used as a main material, so that the capacity of the composite cathode material can be improved, and the stability of the performance of the composite cathode material can be ensured; in order to reduce adverse effects caused by volume expansion in the charge and discharge processes of the cobalt lithium vanadate and shorten the migration path of lithium ions, the cobalt lithium vanadate is further subjected to nanocrystallization, the cobalt lithium vanadate is introduced in a nanowire form, namely, the cobalt lithium vanadate nanowire is bonded with hard carbon, and the conductivity of the composite cathode material is improved while the adverse effects caused by the volume expansion in the charge and discharge processes of the cobalt lithium vanadate are reduced, so that the comprehensive performance of the composite cathode material is improved. In addition, the composite negative electrode material provided by the invention improves the diffusion coefficient of lithium ions in the charge and discharge process of the lithium ion battery by introducing the lithium ions, thereby achieving the purpose of improving the electrochemical performance of the composite negative electrode material.
Although the cobalt lithium vanadate has higher specific capacity and the existence of lithium ions can improve the diffusion coefficient of the lithium ions in the charging and discharging processes of the lithium ion battery, but the volume change of the lithium cobalt vanadate is large in the charging and discharging processes, the cycle life of the lithium ion battery is influenced, therefore, the invention introduces the lithium cobalt vanadate into the main graphite material, combines the lithium cobalt vanadate nanowire with the main graphite material, takes the lithium cobalt vanadate nanowire as a capacity provider of the composite cathode material, on the basis of ensuring the cycle life of the lithium ion battery, the capacity and the electrochemical performance of the composite cathode material are improved, so that the graphite main material and the lithium cobalt vanadate act synergistically in the charge and discharge processes of the composite cathode material provided by the invention, the composite negative electrode material provided by the invention has the characteristics of high specific capacity, long cycle life and excellent electrochemical performance.
In order to further increase the stability of the performance of the composite cathode material, a carbon coating layer is coated outside the graphite and the cobalt lithium vanadate, so that on one hand, the connection strength between the graphite and the cobalt lithium vanadate is increased, the processability of the composite cathode material is improved, the stability and the consistency of the performance of the composite cathode material are improved, and the graphite and the cobalt lithium vanadate have respective advantages, and on the other hand, the conductivity of the cobalt lithium vanadate is further improved, so that the conductivity of the composite cathode material is improved.
In order to improve the comprehensive performance of the composite cathode material, the mass ratio range of the graphite, the lithium cobalt vanadate nanowire and the carbon coating layer in the composite cathode material is preferably 20: 10: 1; by setting the mass ratio range of the three components in the range, the composite negative electrode material has the characteristics of stable performance, improved capacity and small lithium desorption expansion in the charging and discharging processes, thereby improving the comprehensive performance of the composite negative electrode material.
The composite negative electrode material provided by the invention takes graphite as a main material, takes the cobalt vanadate lithium nanowire bonded with the graphite as a high-capacity provider, and further coats a carbon coating layer on the outer parts of the graphite and the cobalt vanadate lithium nanowire, so that the composite negative electrode material provided by the invention has the characteristics of high specific capacity, long cycle life, good rate capability, strong processability and good safety performance, the specific capacity of the composite negative electrode material can easily reach more than 1000mAh/g, and the requirement of a lithium ion battery on the composite negative electrode material is met.
In addition, the composite cathode material provided by the invention takes graphite as a main material, is relatively close to the traditional cathode material, and has smaller technical risk when the existing product is replaced.
According to the composite negative electrode material provided by the invention, by introducing lithium ions, the diffusion coefficient of the lithium ions when the composite negative electrode material is used for a lithium ion battery is obviously improved, so that the electrochemical performance of the composite negative electrode material is improved.
Another object of the present invention is to provide a method for preparing a composite anode material, as shown in fig. 3, the method comprising:
s1: mixing citric acid and ethylene glycol to prepare a solution A;
s2: weighing vanadium salt, cobalt salt and lithium salt to prepare a raw material B;
s3: mixing the raw material B with the solution A, stirring, heating to 120-150 ℃, and preserving heat to obtain sol C;
s4: weighing an alumina molecular sieve, adding the alumina molecular sieve into the sol C, stirring at the temperature of 80-120 ℃, and filtering to obtain particles D;
s5: heating the particles D to 400-700 ℃ in an oxidizing atmosphere, and preserving heat to obtain particles E;
s6: dipping the particles E in an alkali solution, separating insoluble substances, and washing the insoluble substances to be neutral to obtain cobalt lithium vanadate nanowires;
s7: mixing graphite and lithium cobalt vanadate nanowires to obtain powder F;
s8: and (3) introducing organic gas into the powder F at the temperature of 800-1200 ℃ to perform chemical vapor deposition to obtain the composite cathode material.
Firstly, processing raw materials by a sol-gel method, preparing a solution A from citric acid and ethylene glycol, preparing a raw material B from a vanadium salt, a cobalt salt and a lithium salt, mixing the prepared solution A with the raw material B, heating to 120-150 ℃, and carrying out an esterification reaction on the citric acid and the ethylene glycol in the process to form a sol C; citric acid and ethylene glycol are used as raw materials, and vanadium salt, cobalt salt and lithium salt are uniformly dispersed in the sol C through the complexation of the citric acid and the dispersion of the ethylene glycol, so that the uniformity and the stability of the performance of the composite negative electrode material are improved.
In order to improve the comprehensive performance of the prepared composite negative electrode material, the mass ratio of citric acid to ethylene glycol in the solution A is preferably 1: 8-1: 4; the vanadium salt in the raw material B comprises at least one of vanadium chloride, ammonium metavanadate, sodium metavanadate, potassium metavanadate, sodium orthovanadate, sodium pyrovanadate, vanadyl sulfate, vanadyl oxalate and vanadium tetrachloride; the cobalt salt comprises at least one of cobalt chloride, cobaltous chloride, cobalt sulfate, cobaltous sulfate, cobalt nitrate and cobalt acetate; the lithium salt comprises at least one of lithium hydroxide, lithium nitrate, lithium sulfate, lithium chloride, lithium acetate and lithium oxalate; the molar ratio of the vanadium element, the cobalt element and the lithium element in the raw material B is 1:1: 1-1: 1.15.
In order to fully mix and react the solution A and the raw material B, the raw material B and the solution A are mixed, stirred and heated to 120-150 ℃, and the temperature is kept, so that the sol C is obtained and comprises the following components: mixing the raw material B with the solution A, stirring, heating to 120-150 ℃, and preserving heat for 1-5 hours to obtain sol C; wherein the mass of the solution A is 10-50 times of that of the raw material B.
In order to control the size of the prepared lithium cobalt vanadate nanowire, the lithium cobalt vanadate nanowire is prepared by a template method, an alumina molecular sieve is weighed, the alumina molecular sieve is added into sol C, the sol C is fully added into pores of the alumina molecular sieve by stirring at the temperature of 80-120 ℃, the alumina molecular sieve is used as a template for filtering, the alumina molecular sieve is separated, and particles D are obtained, wherein the particles D are the alumina molecular sieve filled with the sol C in the pores.
In order to make the sol C fully enter the pores of the alumina molecular sieve, the alumina molecular sieve is added into the sol C, and the mixture is stirred and filtered at the temperature of 80-120 ℃ to obtain particles D, wherein the particles D comprise: adding an alumina molecular sieve into the sol C, stirring for 1-10 hours at the temperature of 80-120 ℃, and filtering to obtain particles D; wherein the mass of the sol C is 2-10 times of that of the alumina molecular sieve. The alumina molecular sieves of the present invention are preferably commercial alumina molecular sieves.
The lithium cobalt vanadate nanowire is prepared by taking the alumina molecular sieve as a template, so that on one hand, the prepared lithium cobalt vanadate nanowire is controllable and uniform in size by utilizing the characteristics of uniform and controllable pore size and good consistency of the alumina molecular sieve, and the uniformity of the performance of the composite cathode material is improved; on the other hand, the prepared cobalt lithium vanadate is subjected to nanocrystallization by taking the alumina molecular sieve as a template, so that adverse effects caused by volume expansion of the cobalt lithium vanadate in the charging and discharging processes can be overcome, the path of lithium ion migration is shortened, the conductivity of the composite cathode material is improved, and the comprehensive performance of the composite cathode material is improved.
In order to further react the vanadium salt, the cobalt salt and the lithium salt in the pores of the alumina molecular sieve to generate lithium cobalt vanadate, adding the particles D into a heating furnace, heating to 400-700 ℃ in an oxidizing atmosphere, preserving the temperature, allowing the vanadium salt, the cobalt salt and the lithium salt to generate lithium cobalt vanadate in the pores of the alumina molecular sieve in the oxidizing atmosphere, and allowing the size and the shape of the generated lithium cobalt vanadate to be consistent with those of the pores of the alumina molecular sieve to obtain lithium cobalt vanadate nanowires with uniform size, so as to obtain particles E filled with the lithium cobalt vanadate nanowires in the pores of the alumina molecular sieve; wherein, the particle D is heated to 400-700 ℃ in an oxidizing atmosphere, and the temperature is preserved, so that the obtained particle E comprises: heating the particles D to 400-700 ℃ in an oxidizing atmosphere, and preserving heat for 1-5 hours to obtain particles E; wherein the oxidizing atmosphere comprises an oxygen atmosphere or an air atmosphere. The heating furnace comprises at least one of a tube furnace, a box furnace, a rotary furnace, a roller furnace, a push plate furnace and a mesh belt furnace.
In order to separate the prepared lithium cobalt vanadate nanowire from the alumina molecular sieve, the particles E are further soaked by an alkali solution, so that the alumina is dissolved under the action of the alkali solution, insoluble substances are separated from the solution, the insoluble substances are taken out, and the insoluble substances are washed to be neutral, so that the lithium cobalt vanadate nanowire is obtained.
In order to fully dissolve the alumina, the alkali solution is preferably a strong alkali solution, such as one or a mixture of sodium hydroxide solution and potassium hydroxide solution.
According to the invention, the cobalt lithium vanadate nanowire is generated by taking the alumina molecular sieve as a template, and then the alumina is dissolved and separated to obtain the cobalt lithium vanadate nanowire with uniform and controllable size, so that the influence on the cycle performance and the rate capability of the composite cathode material due to the agglomeration phenomenon in the preparation process of the cobalt lithium vanadate nanowire can be avoided.
In order to facilitate combination of graphite and the lithium cobalt vanadate nanowire, a composite negative electrode material taking the graphite as a main material and the lithium cobalt vanadate nanowire as a high-capacity provider is formed, and the graphite and the prepared lithium cobalt vanadate nanowire are mixed to obtain powder F; in order to uniformly mix the graphite and the lithium cobalt vanadate nanowires, the graphite and the lithium cobalt vanadate nanowires are preferably added into a high-speed mixer and mixed for 10-60 min. Wherein the mass ratio of the graphite to the lithium cobalt vanadate nanowire ranges from 2:1 to 10: 1; the particle size range of the graphite is 5-30 microns, and the graphite is natural graphite or artificial graphite.
In order to increase the connection strength between the graphite and the lithium cobalt vanadate nanowire, introducing organic gas into the powder F at the temperature of 800-1200 ℃ to perform chemical vapor deposition; in the chemical vapor deposition process, organic gas is pyrolyzed and carbonized, generated carbon is deposited outside the graphite and the cobalt vanadate lithium nanowire, namely a carbon coating layer is coated outside the graphite and the cobalt vanadate lithium nanowire, the graphite and the cobalt vanadate lithium nanowire are bonded in the process, and the composite cathode material taking the graphite as a main material, the cobalt vanadate lithium nanowire as a high-capacity provider and the carbon as a coating layer is obtained.
Wherein, the powder F is introduced with organic gas at the temperature of 800-1200 ℃ to carry out chemical vapor deposition, and the obtained composite cathode material comprises: introducing organic gas into the powder F at the temperature of 800-1200 ℃, and performing chemical vapor deposition for 5-60 minutes to obtain a composite anode material; wherein the organic gas comprises at least one of methane, ethane, acetylene, acetone, benzene, toluene and xylene.
According to the preparation method of the composite cathode material, the cobalt lithium vanadate nanowire is prepared by taking vanadium salt, cobalt salt and lithium salt as raw materials and taking an alumina molecular sieve as a template method, then the graphite and the cobalt lithium vanadate nanowire are mixed, and the carbon coating layer is prepared outside the graphite and the cobalt lithium vanadate nanowire, so that the preparation method is simple and the cost is low; the prepared composite negative electrode material has the characteristics of high specific capacity, long cycle life, good rate capability, strong processability and good safety performance, and meets the requirements of the lithium ion battery on the composite negative electrode material.
Still another object of the present invention is to provide a lithium ion battery, which comprises the above composite anode material; the advantages of the lithium ion battery are the same as those of the composite cathode material, and are not described in detail herein.
Example one
The embodiment provides a preparation method of a composite anode material, which comprises the following steps:
s1: mixing citric acid and ethylene glycol in a mass ratio of 1:8 to prepare a solution A;
s2: weighing vanadium chloride, cobalt chloride and lithium hydroxide with the molar ratio of vanadium element, cobalt element and lithium element being 1:1:1, and mixing to obtain a raw material B;
s3: mixing the raw material B with the solution A, stirring to fully dissolve the raw material B, heating to 120 ℃, and preserving heat for 1 hour to obtain sol C, wherein the mass of the solution A is 10 times that of the raw material B;
s4: weighing an alumina molecular sieve, adding the alumina molecular sieve into sol C, stirring for 1 hour at the temperature of 80 ℃, and filtering to obtain particles D, wherein the mass of the sol C is 2 times that of the alumina molecular sieve;
s5: putting the particles D into a tube furnace, heating to 400 ℃ in an air atmosphere, and preserving heat for 1 hour to obtain particles E;
s6: dipping the particles E in a sodium hydroxide solution to dissolve an alumina molecular sieve, separating insoluble substances, and washing the insoluble substances to be neutral by using deionized water to obtain cobalt lithium vanadate nanowires;
s7: mixing artificial graphite with the particle size of 5 microns and the lithium cobalt vanadate nanowire according to the mass ratio of 2:1, adding the mixture into a high-speed mixer, and mixing for 10 minutes to obtain powder F;
s8: and (3) introducing methane gas into the powder F at the temperature of 800 ℃, and carrying out chemical vapor deposition for 5 minutes to obtain the composite cathode material.
The preparation method of the composite anode material provided by the embodiment has the advantages of easily obtained raw materials, low price, simple preparation process and easy realization.
Referring to fig. 1, the composite negative electrode material prepared in this embodiment is analyzed, and the graphite serving as the main material and the cobalt lithium vanadate nanowire serving as the high-capacity provider are coated with the carbon coating layer, so that the composite negative electrode material provided by the invention has the characteristics of high specific capacity, long cycle life, good rate capability, strong processability and good safety, and meets the requirements of the lithium ion battery on the composite negative electrode material.
Referring to fig. 2, the cycle life of the composite negative electrode material provided in this embodiment is further analyzed, the 0.5C discharge capacity of the composite negative electrode material reaches 480-.
Example two
The embodiment provides a preparation method of a composite anode material, which comprises the following steps:
s1: mixing citric acid and ethylene glycol in a mass ratio of 1:6 to prepare a solution A;
s2: weighing ammonium metavanadate, cobaltous chloride and lithium nitrate with the molar ratio of vanadium element, cobalt element and lithium element being 1:1:1.12, and mixing to obtain a raw material B;
s3: mixing the raw material B with the solution A, stirring to fully dissolve the raw material B, heating to 140 ℃, and preserving heat for 3 hours to obtain sol C, wherein the mass of the solution A is 30 times that of the raw material B;
s4: weighing an alumina molecular sieve, adding the alumina molecular sieve into sol C, stirring for 5 hours at the temperature of 100 ℃, and filtering to obtain particles D, wherein the mass of the sol C is 6 times that of the alumina molecular sieve;
s5: putting the particles D into a box furnace, heating to 500 ℃ in an oxygen atmosphere, and preserving heat for 3 hours to obtain particles E;
s6: dipping the particles E in a potassium hydroxide solution to dissolve an alumina molecular sieve, separating insoluble substances, and washing the insoluble substances to be neutral by deionized water to obtain cobalt lithium vanadate nanowires;
s7: mixing natural graphite with the particle size of 20 microns and the lithium cobalt vanadate nanowire according to the mass ratio of 6:1, adding the mixture into a high-speed mixer, and mixing for 30 minutes to obtain powder F;
s8: and introducing ethane gas into the powder F at the temperature of 1000 ℃, and performing chemical vapor deposition for 30 minutes to obtain the composite cathode material.
The preparation method of the composite anode material provided by the embodiment has the advantages of easily obtained raw materials, low price, simple preparation process and easy realization.
The advantages of the composite anode material prepared in this embodiment are the same as those in the first embodiment, and are not described herein again.
EXAMPLE III
The embodiment provides a preparation method of a composite anode material, which comprises the following steps:
s1: mixing citric acid and ethylene glycol in a mass ratio of 1:4 to prepare a solution A;
s2: weighing sodium metavanadate, cobalt sulfate and lithium sulfate with the molar ratio of vanadium element, cobalt element and lithium element being 1:1:1.15, and mixing to obtain a raw material B;
s3: mixing the raw material B with the solution A, stirring to fully dissolve the raw material B, heating to 150 ℃, and preserving heat for 5 hours to obtain sol C, wherein the mass of the solution A is 30 times that of the raw material B;
s4: weighing an alumina molecular sieve, adding the alumina molecular sieve into sol C, stirring for 10 hours at 120 ℃ and filtering to obtain particles D, wherein the mass of the sol C is 10 times that of the alumina molecular sieve;
s5: putting the particles D into a rotary furnace, heating to 700 ℃ in an oxygen atmosphere, and preserving heat for 5 hours to obtain particles E;
s6: dipping the particles E in a potassium hydroxide solution to dissolve an alumina molecular sieve, separating insoluble substances, and washing the insoluble substances to be neutral by deionized water to obtain cobalt lithium vanadate nanowires;
s7: mixing artificial graphite with the particle size of 30 micrometers and the lithium cobalt vanadate nanowire according to the mass ratio of 10:1, adding the mixture into a high-speed mixer, and mixing for 60 minutes to obtain powder F;
s8: and introducing acetylene gas into the powder F at the temperature of 1200 ℃, and performing chemical vapor deposition for 60 minutes to obtain the composite cathode material.
The preparation method of the composite anode material provided by the embodiment has the advantages of easily obtained raw materials, low price, simple preparation process and easy realization.
The foregoing is merely a preferred embodiment of the invention, which is intended to be illustrative and not limiting. It will be understood by those skilled in the art that various changes, modifications and equivalents may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (9)
1. A preparation method of the composite anode material is characterized by comprising the following steps:
s1: mixing citric acid and ethylene glycol to prepare a solution A;
s2: weighing vanadium salt, cobalt salt and lithium salt to prepare a raw material B;
s3: mixing the raw material B with the solution A, stirring, heating to 120-150 ℃, and preserving heat to obtain sol C;
s4: weighing an alumina molecular sieve, adding the alumina molecular sieve into the sol C, stirring at the temperature of 80-120 ℃, and filtering to obtain particles D;
s5: heating the particles D to 400-700 ℃ in an oxidizing atmosphere, and preserving heat to obtain particles E;
s6: dipping the particle E in an alkali solution, separating insoluble substances, and washing the insoluble substances to be neutral to obtain a lithium cobalt vanadate nanowire;
s7: mixing graphite with the lithium cobalt vanadate nanowire to obtain powder F;
s8: introducing organic gas into the powder F at the temperature of 800-1200 ℃ to perform chemical vapor deposition to obtain a composite cathode material;
the composite cathode material comprises graphite, a lithium cobalt vanadate nanowire and a carbon coating layer, wherein the graphite is a main material of the composite cathode material, the lithium cobalt vanadate nanowire is bonded with the graphite, and the carbon coating layer is coated outside the graphite and the lithium cobalt vanadate nanowire.
2. The method for preparing the composite anode material according to claim 1, wherein the mass ratio of the citric acid to the ethylene glycol in the step S1 is 1:8 to 1: 4.
3. The method of claim 1, wherein the vanadium salt in step S2 includes at least one of vanadium chloride, ammonium metavanadate, sodium metavanadate, potassium metavanadate, sodium orthovanadate, sodium pyrovanadate, vanadyl sulfate, vanadyl oxalate, and vanadium tetrachloride; the cobalt salt comprises at least one of cobalt chloride, cobaltous chloride, cobalt sulfate, cobaltous sulfate, cobalt nitrate and cobalt acetate; the lithium salt comprises at least one of lithium hydroxide, lithium nitrate, lithium sulfate, lithium chloride, lithium acetate and lithium oxalate; the molar ratio of the vanadium element, the cobalt element and the lithium element in the raw material B is 1:1: 1-1: 1.15.
4. The preparation method of the composite anode material of claim 1, wherein the step of mixing the raw material B with the solution A, stirring and heating to 120-150 ℃, and the step of keeping the temperature to obtain the sol C comprises the following steps: mixing the raw material B with the solution A, stirring and heating to 120-150 ℃, and preserving heat for 1-5 hours to obtain sol C; the mass of the solution A is 10-50 times of that of the raw material B.
5. The preparation method of the composite negative electrode material of claim 1, wherein the weighing of the alumina molecular sieve, the adding of the alumina molecular sieve to the sol C, the stirring at a temperature of 80-120 ℃, and the filtering to obtain particles D comprises: weighing an alumina molecular sieve, adding the alumina molecular sieve into the sol C, stirring for 1-10 hours at the temperature of 80-120 ℃, and filtering to obtain particles D; wherein the mass of the sol C is 2-10 times of that of the alumina molecular sieve.
6. The preparation method of the composite anode material of claim 1, wherein the step of heating the particles D to 400-700 ℃ in an oxidizing atmosphere and preserving heat to obtain the particles E comprises the following steps: heating the particles D to 400-700 ℃ in an oxidizing atmosphere, and preserving heat for 1-5 hours to obtain particles E; wherein the oxidizing atmosphere comprises at least one of an oxygen atmosphere and an air atmosphere.
7. The method for preparing the composite anode material according to claim 2, wherein the mass ratio of the graphite to the lithium cobalt vanadate nanowire in the step S7 is 2: 1-10: 1; the particle size range of the graphite is 5-30 microns.
8. The preparation method of the composite anode material of claim 1, wherein the step of introducing organic gas into the powder F at a temperature of 800-1200 ℃ to perform chemical vapor deposition to obtain the composite anode material comprises the following steps: introducing organic gas into the powder F at the temperature of 800-1200 ℃, and performing chemical vapor deposition for 5-60 minutes to obtain a composite anode material; wherein the organic gas comprises at least one of methane, ethane, acetylene, acetone, benzene, toluene, and xylene.
9. A lithium ion battery comprising the composite anode material produced by the method for producing a composite anode material according to any one of claims 1 to 8.
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