CN115810721A - Preparation method of hard carbon active material negative plate - Google Patents
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Abstract
The invention relates to the technical field of battery materials, and discloses a preparation method of a hard carbon active material negative plate, which comprises a negative plate, wherein the negative plate comprises a negative current collector and a negative active material layer coated on the negative current collector, the negative active material layer is prepared by coating negative slurry, and the preparation method comprises the following steps: step one, preparing cathode slurry; step two, uniformly coating the negative electrode slurry on a negative electrode current collector, and drying, rolling and slicing to obtain a negative electrode sheet; according to the invention, graphite and graphene are adopted in the negative plate to jointly construct a uniform three-dimensional electron transmission and ion transmission network, and in the lithium supplement process, lithium ions can be rapidly and uniformly conducted in a three-dimensional conductive and ion-conducting network, so that the high-efficiency and uniform lithium supplement process is realized.
Description
Technical Field
The invention relates to the technical field of battery materials, in particular to a preparation method of a hard carbon active material negative plate.
Background
Secondary batteries represented by lithium ion batteries have outstanding characteristics of high energy density, long cycle life, no pollution, no memory effect and the like. As a clean energy source, the application of secondary batteries has been gradually popularized from electronic products to the field of large-scale devices such as electric vehicles and the like to adapt to the sustainable development strategy of environment and energy. Thus, higher demands are also made on the energy density of the secondary battery.
At present, the commercial lithium ion battery negative electrode material is mainly graphite. Graphite has the advantages of high conductivity, high stability and the like. However, the theoretical capacity of graphite is about 372mAh/g, and in recent years, almost the theoretical capacity has been developed to the upper limit, and it is difficult to further increase the energy density of a lithium ion battery using graphite as a negative electrode material.
In addition, because of the scarcity of the related active material resources of the lithium ion battery, the battery cost is always high, and the battery faces the severe problems of the exhaustion of the related resources, and the like, the development of other low-cost metal ion secondary battery systems is urgently needed. Sodium ion batteries have become the popular research direction in recent years due to their advantages of low cost, abundant resources, and being similar to lithium ion battery manufacturing process. However, the energy density of the sodium ion battery is always different from that of the lithium ion battery due to the lower gram capacity and voltage platform of the current sodium ion battery cathode material, and thus the commercial application cannot be really realized. Therefore, a preparation method of the hard carbon active material negative plate is provided.
Disclosure of Invention
Technical problem to be solved
In view of the defects of the prior art, the present invention aims to provide a method for preparing a hard carbon active material negative electrode plate, so as to solve the problems in the background art.
(II) technical scheme
In order to achieve the purpose, the invention provides the following technical scheme:
the preparation method of the hard carbon active material negative plate comprises a negative plate, wherein the negative plate comprises a negative current collector and a negative active material layer coated on the negative current collector, and the negative active material layer is prepared by coating negative slurry;
the preparation method of the hard carbon active material negative plate comprises the following steps:
step one, preparing cathode slurry;
and step two, uniformly coating the negative electrode slurry on a negative electrode current collector, and drying, rolling and slicing to obtain a negative electrode sheet.
Preferably, the negative electrode slurry comprises a negative electrode active material, a conductive agent and a binder, and the mass ratio of the negative electrode active material to the conductive agent to the binder is (85-95): 1, (1-4), the current collector is any one of metal copper, aluminum and titanium.
Preferably, the viscosity of the negative electrode slurry is 3000-4000mPa · s, the conductive agent is one or a mixture of several of conductive carbon black, graphite and carbon nanotubes, and the binder is any one of sodium carboxymethylcellulose, styrene butadiene rubber and polyvinylidene fluoride.
Preferably, the drying process in the second step is drying at 85-105 ℃ for 10-12h.
Preferably, the preparation method of the anode slurry comprises the following steps:
s1, adding deionized water into a stirrer;
s2, adding a binder, and stirring until the binder is completely dissolved;
s3, adding a conductive agent and an inorganic solid electrolyte, and stirring to obtain a negative conductive colloid;
and S4, adding a negative electrode active material into the negative electrode conductive colloid, and stirring to obtain negative electrode slurry.
Preferably, the inorganic solid electrolyte is one or more of lithium aluminum titanium phosphate, lithium lanthanum zirconium oxygen and aluminum lithium germanium phosphorus.
Preferably, the negative active material includes graphite and hard carbon, the hard carbon includes hard carbon particles having micropores with a maximum diameter of 0.01 μm or more and d μm or less and 5.0 μm or less, and a ratio of a mass content ω H of hydrogen to a mass content ω C of carbon in the hard carbon is 0.02 or more and ω H/ω C or less and 0.2.
Preferably, the graphite particles have a D1V50 of 7 μm to 14 μm, and the hard carbon particles have a particle diameter D2V50 of 3 μm to 15 μm.
Preferably, the method for preparing the anode active material includes the steps of:
a1, uniformly mixing amylase and aqueous dispersion of starch to enable the starch to carry out enzymolysis reaction at an enzymolysis temperature and an enzymolysis pH value, so as to obtain a precursor of the negative active material;
a2, placing the dried anode active material precursor in an inert atmosphere, calcining for 90-150min at 400-700 ℃, and crushing to obtain first particles;
a3, calcining the first particles in an inert atmosphere at 900-1300 ℃ for 90-150min to obtain second particles;
and A4, placing the second particles in a methane atmosphere to carry out vapor deposition at 850-950 ℃ so as to obtain the negative active material.
(III) advantageous effects
Compared with the prior art, the invention provides a preparation method of a hard carbon active material negative plate, which has the following beneficial effects:
according to the invention, graphite and graphene are adopted in the negative plate to jointly construct a uniform three-dimensional electron transmission and ion transmission network, and in the lithium supplement process, lithium ions can be rapidly and uniformly conducted in a three-dimensional conductive and ion-conducting network, so that the high-efficiency and uniform lithium supplement process is realized.
According to the invention, the inorganic solid electrolyte is added in the preparation of the negative electrode slurry, the inorganic solid electrolyte and the negative electrode active material are mixed together, and the porous negative electrode dressing area is prepared by mixing materials with different particle sizes, so that the problems of low porosity of a pole piece, high migration resistance of a battery cell at low temperature and low ionic conductivity of the battery cell at low temperature after the traditional graphite negative electrode is rolled are solved. The hard carbon material is a porous material, the porosity is further increased by combining the inorganic solid electrolyte, the porosity of the pole piece is improved, and the injected electrolyte can greatly increase the liquid retention amount, so that the ionic conductivity of the surface density negative dressing area can be improved by adding a small amount of the inorganic solid electrolyte.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to specific embodiments, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The invention provides a preparation method of a hard carbon active material negative plate, which comprises a negative plate and is characterized in that the negative plate comprises a negative current collector and a negative active material layer coated on the negative current collector, and the negative active material layer is prepared by coating negative slurry;
the preparation method of the hard carbon active material negative plate comprises the following steps:
step one, preparing cathode slurry;
and step two, uniformly coating the negative electrode slurry on a negative electrode current collector, and drying, rolling and slicing to obtain a negative electrode sheet.
The negative electrode slurry of the embodiment includes a negative electrode active material, a conductive agent, and a binder, and the mass ratio of the negative electrode active material, the conductive agent, and the binder is 85:1:1 and the current collector is copper.
The viscosity of the negative electrode slurry in this example was 3000mPa · s, the conductive agent was conductive carbon black, and the binder was sodium carboxymethylcellulose.
The drying process in step two of this example is drying at 85 ℃ for 10h.
The preparation method of the anode slurry of the embodiment includes the following steps:
s1, adding deionized water into a stirrer;
s2, adding a binder, and stirring until the binder is completely dissolved;
s3, adding a conductive agent and an inorganic solid electrolyte, and stirring to obtain a negative conductive colloid;
and S4, adding a negative electrode active material into the negative electrode conductive colloid, and stirring to obtain negative electrode slurry.
The inorganic solid electrolyte of this example was lithium aluminum titanium phosphate.
The negative active material of the present embodiment includes graphite and hard carbon, the hard carbon including hard carbon particles having micropores with a maximum diameter d μm of 0.01 μm d μm 5.0. Mu.m, for example, the maximum diameter d μm of the micropores may be 0.01 μm,0.05 μm,0.1 μm,0.5 μm,1.0 μm,1.5 μm,2.0 μm,3.0 μm,4.0 μm,5.0 μm or in a range consisting of any of the above; the ratio of the mass content omega H of hydrogen to the mass content omega C of carbon in the hard carbon is not less than 0.09 and not more than omega H/omega C and not more than 0.14;
according to the invention, the ratio of the mass contents of hydrogen and carbon in the hard carbon is controlled within the range, so that the rate capability and the high-temperature cycle performance of the electrochemical device are improved. Without intending to be bound by any theory, the inventors have found during the research that, in the mixed system of graphite and the above hard carbon, the potential interval of the negative electrode during charging and discharging is completely provided by the high potential interval of graphite, and in this potential interval, the lithium storage sites formed by hydrogen in the hard carbon do not participate in the charging and discharging reaction, i.e., hydrogen does not undergo a bonding reaction with lithium to store lithium. However, although the lithium storage reaction does not occur due to the presence of hydrogen, it is presumed that the lithium storage site can absorb heat transferred from the graphite charge-discharge reaction process, thereby reducing the temperature rise of the negative electrode during high-rate charge-discharge and improving the high-temperature cycle performance of the electrochemical device. And the more the mass content of hydrogen in the hard carbon is, the more lithium storage sites provided by the hydrogen are, the more the improvement of the high-temperature cycle performance of the electrochemical device is obvious; however, when the mass content of hydrogen is too large, the content of defects in the hard carbon is also high, and more defects may cause the content of irreversible lithium absorbed by the negative electrode during the first charge to be also high, thereby causing a decrease in the first coulombic efficiency and energy density. Therefore, the ratio of the mass contents of hydrogen and carbon in the hard carbon needs to be controlled within the above-mentioned suitable range, and the rate capability and the high-temperature cycle performance of the electrochemical device are improved by the synergistic effect between the hard carbon and the graphite.
The graphite particles of this example had a D1V50 of 7 μm and the hard carbon particles had a particle diameter D2V50 of 3 μm.
The method for preparing the anode active material of the present embodiment includes the steps of:
a1, uniformly mixing amylase and aqueous dispersion of starch to enable the starch to have an enzymolysis reaction at an enzymolysis temperature and an enzymolysis pH value, so as to obtain a precursor of the negative active material;
in step A1, the amylase may be selected from amylases well known in the art, for example, alpha-amylase, beta-amylase; the starch may be selected from starches known in the art, for example, sweet potato starch among plant starches.
A2, placing the dried anode active material precursor in an inert atmosphere, calcining for 90min at 400 ℃, and crushing to obtain first particles;
in step A2, the inert atmosphere may mean an atmosphere that does not substantially undergo a side reaction with the anode active material precursor, for example, a nitrogen atmosphere, an argon atmosphere, or the like; the above-mentioned crushing treatment may include crushing and classifying the calcined anode active material precursor by a classifying crusher so that the first particles have a particle diameter of an appropriate size.
A3, calcining the first particles in an inert atmosphere at 900 ℃ for 90min to obtain second particles;
in step A3, the inert atmosphere may mean an atmosphere substantially free from side reactions with the first particles, and for example, may be a nitrogen atmosphere, an argon atmosphere, or the like.
And A4, placing the second particles in a methane atmosphere to carry out vapor deposition at 850 ℃ so as to obtain the negative electrode active material.
According to the invention, starch is subjected to enzymolysis by amylase, and the branched chains in starch molecules can be dissolved, so that pores are generated in the interior of the precursor of the negative active material, and the connectivity of micropores in the negative active material is improved. Thus, the negative electrode active material precursor can be calcined and vapor-deposited to form the negative electrode active material of the first aspect of the present application. The content of the hard carbon particles having the micropores in the anode active material prepared according to the method of the present application is within an appropriate range, and the maximum diameter of the micropores in the hard carbon particles is within an appropriate range, and when applied to a secondary battery, the anode active material can not only allow the secondary battery to have a high energy density, but also improve the first coulombic efficiency of the secondary battery.
Example 2
The invention provides a preparation method of a hard carbon active material negative plate, which comprises a negative plate and is characterized in that the negative plate comprises a negative current collector and a negative active material layer coated on the negative current collector, and the negative active material layer is prepared by coating negative slurry;
the preparation method of the hard carbon active material negative plate comprises the following steps:
step one, preparing cathode slurry;
and step two, uniformly coating the negative electrode slurry on a negative electrode current collector, and drying, rolling and slicing to obtain a negative electrode sheet.
The negative electrode slurry of the embodiment includes a negative electrode active material, a conductive agent, and a binder, and the mass ratio of the negative electrode active material, the conductive agent, and the binder is 95:1:4, the current collector is aluminum metal.
The viscosity of the negative electrode slurry of this example was 4000mPa · s, the conductive agent was graphite, and the binder was carboxystyrene-butadiene rubber.
The drying process in step two of this example was drying at 105 ℃ for 12h.
The preparation method of the anode slurry of the embodiment includes the following steps:
s1, adding deionized water into a stirrer;
s2, adding a binder, and stirring until the binder is completely dissolved;
s3, adding a conductive agent and an inorganic solid electrolyte, and stirring to obtain a negative conductive colloid;
and S4, adding a negative electrode active material into the negative electrode conductive colloid, and stirring to obtain negative electrode slurry.
The inorganic solid electrolyte of this example was lithium aluminum titanium phosphate.
The negative active material of the present embodiment includes graphite and hard carbon, the hard carbon including hard carbon particles having micropores with a maximum diameter d μm of 0.01 μm or more and d μm or less and 5.0 μm or less, for example, the maximum diameter d μm of the micropores may be 0.01 μm,0.05 μm,0.1 μm,0.5 μm,1.0 μm,1.5 μm,2.0 μm,3.0 μm,4.0 μm,5.0 μm or in a range consisting of any of the above values; the ratio of the mass content omega H of hydrogen to the mass content omega C of carbon in the hard carbon is not less than 0.11 and not more than omega H/omega C and not more than 0.12;
according to the invention, the ratio of the mass contents of hydrogen and carbon in the hard carbon is controlled within the range, so that the rate capability and the high-temperature cycle performance of the electrochemical device are improved. Without intending to be bound by any theory, the inventors have found during the research that, in the mixed system of graphite and the above hard carbon, the potential interval of the negative electrode during charging and discharging is completely provided by the high potential interval of graphite, and in this potential interval, the lithium storage sites formed by hydrogen in the hard carbon do not participate in the charging and discharging reaction, i.e., hydrogen does not undergo a bonding reaction with lithium to store lithium. However, although the lithium storage reaction does not occur due to the presence of hydrogen, it is presumed that the lithium storage site can absorb heat transferred from the graphite charge-discharge reaction process, thereby reducing the temperature rise of the negative electrode during high-rate charge-discharge and improving the high-temperature cycle performance of the electrochemical device. Moreover, the more the mass content of hydrogen in the hard carbon is, the more lithium storage sites are provided by the hydrogen, and the more the high-temperature cycle performance of the electrochemical device is obviously improved; however, when the mass content of hydrogen is too large, the content of defects in the hard carbon is also high, and more defects may cause the content of irreversible lithium absorbed by the negative electrode during the first charge to be also high, thereby causing a decrease in the first coulombic efficiency and energy density. Therefore, the ratio of the mass contents of hydrogen and carbon in the hard carbon needs to be controlled within the above-mentioned suitable range, and the rate capability and the high-temperature cycle performance of the electrochemical device are improved by the synergistic effect between the hard carbon and the graphite.
The graphite particles of this example had a D1V50 of 14 μm and the hard carbon particles had a particle diameter D2V50 of 15 μm.
The method for preparing the anode active material of the present embodiment includes the steps of:
a1, uniformly mixing amylase and aqueous dispersion of starch to enable the starch to have an enzymolysis reaction at an enzymolysis temperature and an enzymolysis pH value, so as to obtain a precursor of the negative active material;
in step A1, the amylase may be selected from amylases well known in the art, for example, β -amylase, γ -amylase; the starch may be selected from the group of starches known in the art, for example, pea starch, among legume starches.
A2, calcining the dried anode active material precursor in an inert atmosphere at 700 ℃ for 150min, and crushing to obtain first particles;
in step A2, the inert atmosphere may mean an atmosphere that does not substantially undergo a side reaction with the anode active material precursor, for example, a nitrogen atmosphere, an argon atmosphere, or the like; the above-mentioned crushing treatment may include crushing and classifying the calcined anode active material precursor by a classifying crusher so that the first particles have a particle diameter of an appropriate size.
A3, calcining the first particles in an inert atmosphere at 1300 ℃ for 150min to obtain second particles;
in step A3, the inert atmosphere may represent an atmosphere that does not substantially cause a side reaction with the first particles, and may be, for example, a nitrogen atmosphere, an argon atmosphere, or the like.
And A4, placing the second particles in a methane atmosphere to carry out vapor deposition at 950 ℃ so as to obtain the negative electrode active material.
According to the invention, starch is subjected to enzymolysis by amylase, and the branched chains in starch molecules can be dissolved, so that pores are generated in the interior of the precursor of the negative active material, and the connectivity of micropores in the negative active material is improved. Thus, the negative electrode active material precursor can be calcined and vapor-deposited to form the negative electrode active material of the first aspect of the present application. The content of the hard carbon particles having the micropores in the anode active material prepared according to the method of the present application is within an appropriate range, and the maximum diameter of the micropores in the hard carbon particles is within an appropriate range, and when applied to a secondary battery, the anode active material can not only allow the secondary battery to have a high energy density, but also improve the first coulombic efficiency of the secondary battery.
Example 3
The invention provides a preparation method of a hard carbon active material negative plate, which comprises a negative plate and is characterized in that the negative plate comprises a negative current collector and a negative active material layer coated on the negative current collector, and the negative active material layer is prepared by coating negative slurry;
the preparation method of the hard carbon active material negative plate comprises the following steps:
step one, preparing cathode slurry;
and step two, uniformly coating the negative electrode slurry on a negative electrode current collector, and drying, rolling and slicing to obtain a negative electrode sheet.
The negative electrode slurry of the embodiment comprises a negative electrode active material, a conductive agent and a binder, wherein the mass ratio of the negative electrode active material to the conductive agent to the binder is 90:1:3, the current collector is titanium metal.
The viscosity of the negative electrode slurry of this example was 3500mPa · s, the conductive agent was carbon nanotubes, and the binder was polyvinylidene fluoride.
The drying process in step two of this example was drying at 95 ℃ for 11h.
The preparation method of the anode slurry of the embodiment includes the following steps:
s1, adding deionized water into a stirrer;
s2, adding a binder, and stirring until the binder is completely dissolved;
s3, adding a conductive agent and an inorganic solid electrolyte, and stirring to obtain a negative conductive colloid;
and S4, adding a negative electrode active material into the negative electrode conductive colloid, and stirring to obtain negative electrode slurry.
The inorganic solid electrolyte of this example was lithium aluminum titanium phosphate.
The negative active material of the present embodiment includes graphite and hard carbon, the hard carbon including hard carbon particles having micropores with a maximum diameter d μm of 0.01 μm or more and d μm or less and 5.0 μm or less, for example, the maximum diameter d μm of the micropores may be 0.01 μm,0.05 μm,0.1 μm,0.5 μm,1.0 μm,1.5 μm,2.0 μm,3.0 μm,4.0 μm,5.0 μm or in a range consisting of any of the above values; the ratio of the mass content omega H of hydrogen to the mass content omega C of carbon in the hard carbon is not less than 0.10 and not more than omega H/omega C and not more than 0.13;
according to the invention, the ratio of the mass contents of hydrogen and carbon in the hard carbon is controlled within the range, so that the rate capability and the high-temperature cycle performance of the electrochemical device are improved. Without intending to be bound by any theory, the inventors have found during the research that, in the mixed system of graphite and the above hard carbon, the potential interval of the negative electrode during charging and discharging is completely provided by the high potential interval of graphite, and in this potential interval, the lithium storage sites formed by hydrogen in the hard carbon do not participate in the charging and discharging reaction, i.e., hydrogen does not undergo a bonding reaction with lithium to store lithium. However, although the lithium storage reaction does not occur due to the presence of hydrogen, it is presumed that the lithium storage site can absorb heat transferred from the graphite charge-discharge reaction process, thereby reducing the temperature rise of the negative electrode during high-rate charge-discharge and improving the high-temperature cycle performance of the electrochemical device. And the more the mass content of hydrogen in the hard carbon is, the more lithium storage sites provided by the hydrogen are, the more the improvement of the high-temperature cycle performance of the electrochemical device is obvious; however, when the mass content of hydrogen is too large, the content of defects in the hard carbon is also high, and more defects may cause the content of irreversible lithium absorbed by the negative electrode during the first charge to be also high, thereby causing a decrease in the first coulombic efficiency and energy density. Therefore, the ratio of the mass contents of hydrogen and carbon in the hard carbon needs to be controlled within the above-mentioned suitable range, and the rate capability and the high-temperature cycle performance of the electrochemical device are improved by the synergistic effect between the hard carbon and the graphite.
The graphite particles of this example had a D1V50 of 10 μm and the hard carbon particles had a particle diameter D2V50 of 9 μm.
The method for preparing the anode active material of the present embodiment includes the steps of:
a1, uniformly mixing amylase and aqueous dispersion of starch to enable the starch to have an enzymolysis reaction at an enzymolysis temperature and an enzymolysis pH value, so as to obtain a precursor of the negative active material;
in step A1, the amylase may be selected from amylases well known in the art, for example, alpha-amylase, gamma-amylase; the starch may be selected from starches known in the art, for example, corn starch among cereal starches.
A2, placing the dried anode active material precursor in an inert atmosphere, calcining for 120min at 550 ℃, and crushing to obtain first particles;
in step A2, the inert atmosphere may mean an atmosphere that does not substantially undergo a side reaction with the anode active material precursor, for example, a nitrogen atmosphere, an argon atmosphere, or the like; the above-mentioned crushing treatment may include crushing and classifying the calcined anode active material precursor by a classifying crusher so that the first particles have a particle diameter of an appropriate size.
A3, calcining the first particles in an inert atmosphere at 1100 ℃ for 120min to obtain second particles;
in step A3, the inert atmosphere may mean an atmosphere substantially free from side reactions with the first particles, and for example, may be a nitrogen atmosphere, an argon atmosphere, or the like.
And A4, placing the second particles in a methane atmosphere to carry out vapor deposition at 900 ℃ so as to obtain the negative electrode active material.
According to the invention, starch is subjected to enzymolysis by amylase, and the branched chains in starch molecules can be dissolved, so that pores are generated in the interior of the precursor of the negative active material, and the connectivity of micropores in the negative active material is improved. Thus, the negative electrode active material precursor can be calcined and vapor-deposited to form the negative electrode active material of the first aspect of the present application. The content of the hard carbon particles having the micropores in the anode active material prepared according to the method of the present application is within an appropriate range, and the maximum diameter of the micropores in the hard carbon particles is within an appropriate range, and when applied to a secondary battery, the anode active material can not only allow the secondary battery to have a high energy density, but also improve the first coulombic efficiency of the secondary battery.
It is to be understood that the present invention has been described with reference to certain embodiments, and that various changes in the features and embodiments, or equivalent substitutions may be made therein by those skilled in the art without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
Claims (9)
1. The preparation method of the hard carbon active material negative plate comprises a negative plate, and is characterized in that the negative plate comprises a negative current collector and a negative active material layer coated on the negative current collector, wherein the negative active material layer is prepared by coating negative slurry;
the preparation method of the hard carbon active material negative plate comprises the following steps:
step one, preparing cathode slurry;
and step two, uniformly coating the negative electrode slurry on a negative electrode current collector, and drying, rolling and slicing to obtain a negative electrode sheet.
2. The method for preparing the negative electrode sheet of the hard carbon active material according to claim 1, wherein the method comprises the following steps: the negative electrode slurry comprises a negative electrode active material, a conductive agent and a binder, wherein the mass ratio of the negative electrode active material to the conductive agent to the binder is (85-95): 1, (1-4), the current collector is any one of metal copper, aluminum and titanium.
3. The method for preparing the negative electrode sheet of the hard carbon active material according to claim 1, wherein the method comprises the following steps: the viscosity of the negative electrode slurry is 3000-4000 mPa.s, the conductive agent is one or a mixture of more of conductive carbon black, graphite and carbon nano tubes, and the binder is any one of sodium carboxymethylcellulose, styrene butadiene rubber and polyvinylidene fluoride.
4. The method for preparing the negative electrode sheet of the hard carbon active material according to claim 1, wherein the method comprises the following steps: and in the second step, the drying process is drying at 85-105 ℃ for 10-12h.
5. The method for preparing the negative electrode sheet of the hard carbon active material according to claim 1, wherein the method comprises the following steps: the preparation method of the negative electrode slurry comprises the following steps:
s1, adding deionized water into a stirrer;
s2, adding a binder, and stirring until the binder is completely dissolved;
s3, adding a conductive agent and an inorganic solid electrolyte, and stirring to obtain a negative conductive colloid;
and S4, adding a negative electrode active material into the negative electrode conductive colloid, and stirring to obtain negative electrode slurry.
6. The method for preparing the negative electrode sheet made of the hard carbon active material according to claim 5, wherein the method comprises the following steps: the inorganic solid electrolyte is one or more of lithium aluminum titanium phosphate, lithium lanthanum zirconium oxygen and aluminum lithium germanium phosphorus.
7. The method for preparing the negative electrode sheet of the hard carbon active material according to claim 5, wherein the method comprises the following steps: the negative electrode active material includes graphite and hard carbon, the hard carbon includes hard carbon particles having micropores, a maximum diameter of the micropores is 0.01 [ mu ] m or more and d [ mu ] m or less and 5.0 [ mu ] m or less, and a ratio of a mass content of hydrogen ω H to a mass content of carbon ω C in the hard carbon is 0.02 or more and ω H/ω C or less and 0.2.
8. The method for preparing the negative electrode sheet of the hard carbon active material according to claim 7, wherein the method comprises the following steps: the graphite particles have a D1V50 of 7 to 14 μm, and the hard carbon particles have a particle diameter D2V50 of 3 to 15 μm.
9. The method for preparing the negative electrode sheet of the hard carbon active material according to claim 5, wherein the method comprises the following steps: the preparation method of the negative active material comprises the following steps:
a1, uniformly mixing amylase and aqueous dispersion of starch to enable the starch to carry out enzymolysis reaction at an enzymolysis temperature and an enzymolysis pH value, so as to obtain a precursor of the negative active material;
a2, placing the dried anode active material precursor in an inert atmosphere, calcining for 90-150min at 400-700 ℃, and crushing to obtain first particles;
a3, calcining the first particles in an inert atmosphere at 900-1300 ℃ for 90-150min to obtain second particles;
and A4, placing the second particles in a methane atmosphere to carry out vapor deposition at 850-950 ℃ so as to obtain the negative active material.
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| CN116093316A (en) * | 2023-04-07 | 2023-05-09 | 宁德新能源科技有限公司 | Negative electrode active material, preparation method thereof, negative electrode plate and secondary battery |
| CN116093316B (en) * | 2023-04-07 | 2023-08-18 | 宁德新能源科技有限公司 | Negative electrode active material, preparation method thereof, negative electrode plate and secondary battery |
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