CN117423919A - Modified lithium metal battery negative electrode and preparation method thereof - Google Patents
Modified lithium metal battery negative electrode and preparation method thereof Download PDFInfo
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- CN117423919A CN117423919A CN202311747288.4A CN202311747288A CN117423919A CN 117423919 A CN117423919 A CN 117423919A CN 202311747288 A CN202311747288 A CN 202311747288A CN 117423919 A CN117423919 A CN 117423919A
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- 150000002641 lithium Chemical class 0.000 title claims abstract description 41
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- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 18
- 239000002994 raw material Substances 0.000 claims description 18
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Abstract
The invention discloses a modified lithium metal battery cathode and a preparation method thereof, and belongs to the technical field of lithium metal batteries. The modified lithium metal battery negative electrode comprises a negative electrode plate and a modified layer, wherein the modified layer is arranged on the surface of the negative electrode plate and comprises 5-90% by mass of modified main material and 5-80% by mass of dispersion solvent. The preparation method of the modified lithium metal battery cathode comprises the following steps of S1, preparing a two-dimensional flaky modified main material; s2, drying the modified main material, the dispersion solvent, the binder or the additive, and uniformly mixing to obtain modified slurry; and S3, coating the modified slurry on a cathode of the lithium metal battery. According to the modified lithium metal battery cathode and the preparation method thereof, the two-dimensional nanosheet material is used for coating and modifying the surface of the lithium metal cathode, so that stable SEI film is formed on the lithium metal cathode, and the performance of the lithium ion battery is improved.
Description
Technical Field
The invention relates to the technical field of lithium metal batteries, in particular to a modified lithium metal battery negative electrode and a preparation method thereof.
Background
The lithium metal battery formed by the nickel-cobalt-manganese ternary material anode and the lithium metal cathode has ultrahigh energy density, so that the lithium metal battery becomes a research hot spot of the next generation of high specific energy batteries. However, the interface (SEI) of an electrolyte with a lithium metal anode is not completely stable during cycling, and the SEI film is continuously destroyed and reconstituted during battery cycling, resulting in continuous consumption of the electrolyte and generation of inactive lithium. In addition, the lithium metal battery can also cause growth of lithium dendrite under the conditions of high-rate and deep charge and discharge, so that the separator is punctured, and the safety risk of short circuit in the battery is brought. Therefore, forming a stable SEI film is important for suppressing consumption of liquid electrolyte and growth of lithium dendrites.
Disclosure of Invention
The invention aims to provide a modified lithium metal battery cathode and a preparation method thereof, wherein the surface of the lithium metal cathode is coated and modified by a two-dimensional nano sheet material, so that a stable SEI film is formed on the lithium metal cathode, and the performance of a lithium ion battery is improved.
In order to achieve the above purpose, the invention provides a modified lithium metal battery cathode which comprises a cathode plate and a modified layer, wherein the modified layer is arranged on the surface of the cathode plate and comprises 5-90% by mass of modified main material and a dispersion solvent with the solid content of 5-80%.
Preferably, the negative electrode sheet is a lithium foil, a copper-lithium composite tape or a copper foil. Copper foil is selected for coating the non-negative electrode lithium metal battery.
Preferably, the modified main material is boron nitride, carbon nitride, fluorinated graphene, tin sulfide or zeolite, and the thickness of the modified main material is 0.1-20 μm. The modified main material of boron nitride, carbon nitride, fluorinated graphene, tin sulfide or zeolite has chemical inertness and higher mechanical strength, has certain lithium ion conductivity, can inhibit the growth of lithium dendrite, stabilizes an SEI layer, and is favorable for uniformly covering a lithium metal battery cathode and forming a uniform and stable SEI layer on the cathode.
Preferably, the dispersion solvent is acetonitrile or NMP.
Preferably, the modified layer comprises a binder, and the mass percentage of the binder is 1% -50%; the binder is PEO or PVDF.
Preferably, the modified layer comprises an additive, wherein the mass percentage of the additive is 1% -20%; the additive is lithium salt.
The preparation method of the modified lithium metal battery cathode comprises the following steps:
s1, preparing a two-dimensional flaky modified main material;
s2, drying the modified main material, the dispersion solvent, the binder or the additive, and uniformly mixing to obtain modified slurry;
and S3, coating the modified slurry on a cathode of the lithium metal battery.
Preferably, in the step S1, a two-dimensional flaky modified main material is prepared by a stripping method or a sintering method;
the exfoliation method is to use commercial boron nitride, carbon nitride, graphite fluoride and other crystals, and to obtain two-dimensional boron nitride, carbon nitride, graphene fluoride and other nano-sheet powder through cleaning and filtering under the actions of mechanical exfoliation (ultrasonic, strong stirring, ball milling and the like) and chemical exfoliation (solvent exfoliation, electrochemical exfoliation and the like).
The sintering method specifically comprises the following steps:
s11, mixing the raw materials of the modified main material and the template component to obtain a mixture;
s12, placing the mixture into a sintering furnace (a box furnace, a bell jar furnace, a roller kiln and the like), sintering in the atmosphere of air, argon, nitrogen or ammonia, and naturally cooling to obtain a two-dimensional nano sheet-shaped modified main material crude product;
s13, placing the two-dimensional nano sheet-shaped modified main material crude product into water for cleaning, removing soluble impurities, and obtaining the two-dimensional sheet-shaped modified main material through ultrasonic treatment, filtration and drying.
Preferably, the raw materials of the modified main material comprise 2-50% of boron source and 2-50% of nitrogen source by mass percent; the template comprises 20-80% of sodium chloride by mass percent; the boron source is boric acid, and the nitrogen source is ammonia, dicyandiamide or melamine. The sodium chloride is used for regulating and controlling the flaky morphology of the modified main material.
Or, the raw materials of the modified main material are nitrogen sources with the mass percentage of 2% -50%; the template component is sodium chloride with the mass percentage of 50-98 percent. The nitrogen source is dicyandiamide or melamine.
The mode of mixing may be such that the raw materials and the template component are put into a mixer (ball mill, inclined mixer, high-speed mixer, etc.) to be mixed. Or, the raw materials and the template component are completely dissolved in water to obtain an aqueous solution with the solid content of 5% -30%, and a spray dryer or a freeze dryer is used for removing the water component to obtain the uniformly mixed mixture.
Preferably, when the raw materials of the modified main material are boron source and nitrogen source, the sintering temperature is 400-1000 ℃; when the raw material of the modified main material is a nitrogen source, the sintering temperature is 300-700 ℃; the temperature rising rate is 2-30 ℃/min, and the heat preservation time is 0.1-10h.
The modified lithium metal battery negative electrode and the preparation method thereof have the advantages and positive effects that:
1. the appearance of the nano sheet of the modified main material is favorable for uniformly covering the negative electrode of the lithium metal battery, and the power assisting is used for forming a uniform and stable SEI layer.
2. The modified main material has good mechanical strength and chemical stability, has certain lithium ion conductivity, and meets the functional requirement of inhibiting the growth of lithium dendrite and stabilizing the SEI layer.
3. The modified main material modifies the lithium metal battery of the negative electrode to obviously improve the cycle performance of the battery and the performance under high discharge multiplying power.
4. The modified main material modified copper foil cathode-free lithium metal battery obviously improves the coulomb efficiency and the capacity retention rate of the battery in the circulation process.
The technical scheme of the invention is further described in detail through the drawings and the embodiments.
Drawings
FIG. 1 is an SEM image of a modified lithium metal battery anode and a preparation method thereof the boron nitride nanosheets prepared in example 1;
FIG. 2 is an SEM image of a modified lithium metal battery anode and a method for preparing the same according to example 2;
FIG. 3 is a SEM (scanning electron microscope) coated negative electrode of a modified lithium metal battery and a preparation method thereof in example 1;
FIG. 4 is a SEM image of lithium uniform deposition after modification of the negative electrode of example 1, which is a modified lithium metal battery negative electrode according to the present invention;
FIG. 5 is an SEM image of lithium dendrite growth after cycling of a modified lithium metal battery anode and a modified anode prepared in comparative example 1;
FIG. 6 is a graph of cycle data of a modified lithium metal battery negative electrode and a preparation method thereof according to example 1 of the boron nitride modified lithium metal soft-pack battery of the present invention;
FIG. 7 is a graph showing cycle data of a modified lithium metal battery negative electrode and a method for preparing the same according to the invention, wherein the carbon nitride modified lithium metal soft-pack battery is in example 2;
fig. 8 is a cycle data diagram of a modified lithium metal battery negative electrode and a preparation method thereof according to comparative example 1, wherein the modified lithium metal battery soft package battery is not modified.
Detailed Description
Example 1
The modified lithium metal battery cathode comprises a cathode plate and a modified layer, wherein the modified layer is arranged on the surface of the cathode plate. The modified layer comprises 80% of modified main material, 10% of binder, 10% of additive and 50% of solid content by adding dispersion solvent.
The modified main material is boron nitride, the dispersing solvent is acetonitrile, the binder is PVDF, the additive is LITFSI, and the negative plate is lithium foil.
The thickness of the modified host material was 5. Mu.m.
The preparation method of the modified lithium metal battery cathode comprises the following steps:
s1, preparing a two-dimensional flaky modified main material. And preparing the two-dimensional flaky modified main material by adopting a sintering method.
The sintering method specifically comprises the following steps:
s11, placing the raw materials of the modified main material and the template component into a mixer for mixing to obtain a mixture.
The raw materials of the modified main material comprise 2-50% of boron source and 2-50% of nitrogen source by mass percent. The template component is sodium chloride with the mass percentage of 20-80%. The boron source is boric acid and the nitrogen source is dicyandiamide.
S12, placing the mixture into a sintering furnace, and sintering under a nitrogen atmosphere, wherein the sintering temperature is 800 ℃, the heating rate is 5 ℃/min, and the heat preservation time is 1h. Naturally cooling to obtain a two-dimensional nano flaky boron nitride crude product.
And S13, placing the two-dimensional nano flaky boron nitride crude product into water for stirring and cleaning, removing soluble impurities, and obtaining the two-dimensional nano flaky boron nitride after ultrasonic treatment, filtration and drying.
S2, drying the two-dimensional nano sheet boron nitride, acetonitrile dispersion solvent, PVDF binder and LITFSI additive, and uniformly mixing in a sand mill to obtain modified slurry. The water content of the two-dimensional nano flaky boron nitride, acetonitrile dispersion solvent, PVDF binder and LITFSI additive is controlled below 100 ppm.
And S3, coating the modified slurry on the cathode of the lithium metal battery in a spray coating, blade coating or transfer printing mode.
Fig. 1 is an SEM image of a modified lithium metal battery anode and a preparation method thereof according to the boron nitride nanosheets prepared in example 1 of the present invention. As shown in fig. 1, a two-dimensional sheet-like boron nitride nanosheet was obtained using the method described in this example.
Fig. 3 is a modified lithium metal battery negative electrode and a preparation method thereof according to an SEM image coated with the boron nitride nanosheet negative electrode of example 1. As shown in fig. 3, a uniform modified layer of boron nitride nanoplatelets was obtained on the surface of the negative electrode of the lithium metal battery.
Fig. 4 is an SEM image of lithium uniform deposition after modification of the negative electrode of example 1, which is a modified lithium metal battery negative electrode according to the present invention. As shown in fig. 4, after the negative electrode of the lithium metal battery is modified by adopting boron nitride, lithium is uniformly deposited on the negative electrode, so that the growth of lithium dendrites is reduced.
Example 2
The modified layer comprises 90% of carbon nitride, 6% of binder, 4% of additive and adding a dispersion solvent to make the solid content to 50%.
The modified main material is carbon nitride, the dispersing solvent is acetonitrile, the binder is PVDF, the additive is LITFSI, and the negative plate is lithium foil.
The thickness of the modified host material was 3. Mu.m.
The preparation method of the modified lithium metal battery cathode comprises the following steps:
s1, preparing a two-dimensional flaky modified main material. And preparing the two-dimensional flaky modified main material by adopting a sintering method.
The sintering method specifically comprises the following steps:
s11, placing the raw materials of the modified main material and the template component into a mixer for mixing to obtain a mixture.
The raw materials of the modified main material are carbon sources and nitrogen sources, wherein the mass percentage of the carbon sources and the nitrogen sources is 5%. The template component is 95% sodium chloride by mass. The carbon source and the nitrogen source are dicyandiamide.
S12, placing the mixture into a sintering furnace, and sintering under a nitrogen atmosphere, wherein the sintering temperature is 750 ℃, the heating rate is 3 ℃/min, and the heat preservation time is 1h. Naturally cooling to obtain a two-dimensional nano flaky carbon nitride crude product.
And S13, placing the two-dimensional nano sheet carbon nitride crude product into water for stirring and cleaning, removing soluble impurities, and obtaining the two-dimensional nano sheet carbon nitride after ultrasonic treatment, filtration and drying.
S2, drying the two-dimensional nano sheet carbon nitride, acetonitrile dispersion solvent, PVDF binder and LITFSI additive, and uniformly mixing in a sand mill to obtain modified slurry. The water content of the two-dimensional nano flaky carbon nitride, acetonitrile dispersion solvent, PVDF binder and LITFSI additive is controlled below 100 ppm.
And S3, coating the modified slurry on the cathode of the lithium metal battery in a spray coating, blade coating or transfer printing mode.
Fig. 2 is an SEM image of a modified lithium metal battery anode and a preparation method thereof according to the carbon nitride nanosheets prepared in example 2 of the present invention. As shown in fig. 2, a two-dimensional sheet-like carbon nitride nanosheet was obtained by the method described in this example.
Example 3
The modified layer comprises 45% of carbon nitride, 40% of binder, 15% of additive and adding a dispersion solvent to make the solid content reach 50%.
The modified main material is carbon nitride, the dispersing solvent is acetonitrile, the binder is PVDF, the additive is LITFSI, and the negative plate is lithium foil.
The thickness of the modified host material was 5. Mu.m.
The preparation method of the modified lithium metal battery cathode comprises the following steps:
s1, preparing a two-dimensional flaky modified main material. And preparing the two-dimensional flaky modified main material by adopting a sintering method.
The sintering method specifically comprises the following steps:
s11, placing the raw materials of the modified main material and the template component into a mixer for mixing to obtain a mixture.
The raw materials of the modified main material are carbon sources and nitrogen sources, wherein the mass percentage of the carbon sources and the nitrogen sources is 5%. The template component is 95% sodium chloride by mass. The carbon source and the nitrogen source are dicyandiamide.
S12, placing the mixture into a sintering furnace, and sintering under a nitrogen atmosphere, wherein the sintering temperature is 750 ℃, the heating rate is 3 ℃/min, and the heat preservation time is 1h. Naturally cooling to obtain a two-dimensional nano flaky carbon nitride crude product.
And S13, placing the two-dimensional nano sheet carbon nitride crude product into water for stirring and cleaning, removing soluble impurities, and obtaining the two-dimensional nano sheet carbon nitride after ultrasonic treatment, filtration and drying.
S2, drying the two-dimensional nano sheet carbon nitride, acetonitrile dispersion solvent, PVDF binder and LITFSI additive, and uniformly mixing in a sand mill to obtain modified slurry. The water content of the two-dimensional nano flaky carbon nitride, acetonitrile dispersion solvent, PVDF binder and LITFSI additive is controlled below 100 ppm.
And S3, coating the modified slurry on the cathode of the lithium metal battery in a spray coating, blade coating or transfer printing mode.
Example 4
The modified layer comprises 5% of fluorinated graphene, 80% of binder, 15% of additive and adding a dispersion solvent to enable the solid content to be 50%.
The modified main material is fluorinated graphene, the dispersing solvent is acetonitrile, the binder is PVDF, the additive is LITFSI, and the negative plate is lithium foil.
The thickness of the modified host material was 3. Mu.m.
The preparation method of the modified lithium metal battery cathode comprises the following steps:
s1, preparing a two-dimensional flaky modified main material. And preparing the two-dimensional flaky modified main material by adopting an ultrasonic stripping method. Commercial graphite fluoride was exfoliated into graphene fluoride using sonication, followed by drying.
S2, drying the two-dimensional nano flaky fluorinated graphene, acetonitrile dispersion solvent, PVDF binder and LITFSI additive, and uniformly mixing in a sand mill to obtain modified slurry. The water content of the two-dimensional nano flaky fluorinated graphene, acetonitrile dispersion solvent, PVDF binder and LITFSI additive is controlled below 100 ppm.
And S3, coating the modified slurry on the cathode of the lithium metal battery in a spray coating, blade coating or transfer printing mode.
Comparative example 1
The negative electrode of the lithium metal battery is not coated with the modified layer.
Fig. 5 is an SEM image of lithium dendrite growth after cycling of a modified lithium metal battery anode and a modified anode prepared in comparative example 1 according to a preparation method of the present invention. As shown in fig. 5, lithium dendrite growth was severe after cycling of the negative electrode of the lithium metal battery without the modified layer.
The negative electrode, positive electrode plate, electrolyte and separator of the lithium metal batteries of example 1, example 2 and comparative example 1 were assembled into lithium metal pouch batteries, respectively, and the performance of the lithium metal pouch batteries was tested. As shown in fig. 6, 7 and 8, after the negative electrode of the lithium metal battery is coated by adopting boron nitride and carbon nitride, the cycle life of the lithium metal soft-pack battery is prolonged, the cycle performance of the lithium metal soft-pack battery is improved, and the coulomb efficiency and the capacity retention rate of the lithium metal soft-pack battery in the cycle process are obviously improved.
Therefore, the modified lithium metal battery cathode and the preparation method thereof are adopted, the surface of the lithium metal cathode is coated and modified by the two-dimensional nano sheet material, so that stable SEI film is promoted to be formed on the lithium metal cathode, and the performance of the lithium ion battery is improved.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention and not for limiting it, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that: the technical scheme of the invention can be modified or replaced by the same, and the modified technical scheme cannot deviate from the spirit and scope of the technical scheme of the invention.
Claims (10)
1. The modified lithium metal battery cathode is characterized in that: the modified material comprises a negative plate and a modified layer, wherein the modified layer is arranged on the surface of the negative plate and comprises a modified main material with the mass percentage of 5-90% and a dispersion solvent with the solid content of 5-80%.
2. The modified lithium metal battery negative electrode of claim 1, wherein: the negative plate is a lithium foil, a copper-lithium composite belt or a copper foil.
3. The modified lithium metal battery negative electrode of claim 1, wherein: the modified main material is boron nitride, carbon nitride, fluorinated graphene, tin sulfide or zeolite with a two-dimensional nano sheet structure, and the thickness of the modified main material is 0.1-20 mu m.
4. The modified lithium metal battery negative electrode of claim 1, wherein: the dispersion solvent is acetonitrile or NMP.
5. The modified lithium metal battery negative electrode of claim 1, wherein: the modified layer comprises a binder, wherein the mass percentage of the binder is 1% -50%; the binder is PEO or PVDF.
6. The modified lithium metal battery negative electrode of claim 1, wherein: the modified layer comprises an additive, wherein the mass percentage of the additive is 1% -20%; the additive is lithium salt.
7. A method for preparing the modified lithium metal battery anode as claimed in any one of claims 1 to 6, comprising the steps of:
s1, preparing a two-dimensional flaky modified main material;
s2, drying the modified main material, the dispersion solvent, the binder or the additive, and uniformly mixing to obtain modified slurry;
and S3, coating the modified slurry on a cathode of the lithium metal battery.
8. The method for preparing the modified lithium metal battery anode according to claim 7, wherein the method comprises the following steps: in the step S1, a two-dimensional flaky modified main material is prepared by adopting a stripping method or a sintering method;
the sintering method specifically comprises the following steps:
s11, mixing the raw materials of the modified main material and the template component to obtain a mixture;
s12, placing the mixture into a sintering furnace, sintering in an atmosphere of air, argon, nitrogen or ammonia, and naturally cooling to obtain a two-dimensional nano sheet-shaped modified main material crude product;
and S13, cleaning and drying the coarse product of the two-dimensional nano sheet-shaped modified main material to obtain the two-dimensional sheet-shaped modified main material.
9. The method for preparing the modified lithium metal battery anode according to claim 8, wherein the method comprises the following steps: in the step S11, the raw materials of the modified main material comprise 2-50% of boron source and 2-50% of nitrogen source by mass percent; the template comprises 20-80% of sodium chloride by mass percent;
or, the raw materials of the modified main material are nitrogen sources with the mass percentage of 2% -50%; the template component is sodium chloride with the mass percentage of 50-98 percent.
10. The method for preparing the modified lithium metal battery anode according to claim 9, wherein the method comprises the following steps: in the step S12, when the raw materials of the modified main material are boron sources and nitrogen sources, the sintering temperature is 400-1000 ℃; when the raw material of the modified main material is a nitrogen source, the sintering temperature is 300-700 ℃; the temperature rising rate is 2-30 ℃/min, and the heat preservation time is 0.1-10h.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202311747288.4A CN117423919A (en) | 2023-12-19 | 2023-12-19 | Modified lithium metal battery negative electrode and preparation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311747288.4A CN117423919A (en) | 2023-12-19 | 2023-12-19 | Modified lithium metal battery negative electrode and preparation method thereof |
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