CN115692634A - Double-doped silicon-based lithium ion negative electrode material and preparation method and application thereof - Google Patents
Double-doped silicon-based lithium ion negative electrode material and preparation method and application thereof Download PDFInfo
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 53
- 239000010703 silicon Substances 0.000 title claims abstract description 44
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 41
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 41
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 40
- 239000007773 negative electrode material Substances 0.000 title claims abstract description 35
- 238000002360 preparation method Methods 0.000 title claims abstract description 26
- 239000000463 material Substances 0.000 claims abstract description 78
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 63
- 239000007789 gas Substances 0.000 claims abstract description 45
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- 239000000377 silicon dioxide Substances 0.000 claims abstract description 29
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 26
- 239000000758 substrate Substances 0.000 claims abstract description 25
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- 238000007599 discharging Methods 0.000 claims abstract description 13
- 238000012216 screening Methods 0.000 claims abstract description 13
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- 238000000151 deposition Methods 0.000 claims abstract description 4
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- 229910052744 lithium Inorganic materials 0.000 claims description 14
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- 238000005229 chemical vapour deposition Methods 0.000 claims description 12
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- 239000001294 propane Substances 0.000 claims description 6
- 239000000126 substance Substances 0.000 claims description 5
- 229910052718 tin Inorganic materials 0.000 claims description 5
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- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 claims description 4
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- 238000004519 manufacturing process Methods 0.000 claims 1
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- 239000010406 cathode material Substances 0.000 description 16
- 229910052786 argon Inorganic materials 0.000 description 9
- 239000012300 argon atmosphere Substances 0.000 description 9
- 239000011863 silicon-based powder Substances 0.000 description 9
- 238000010998 test method Methods 0.000 description 8
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 7
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- 229910052749 magnesium Inorganic materials 0.000 description 4
- 239000011777 magnesium Substances 0.000 description 4
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 description 4
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
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- PAZHGORSDKKUPI-UHFFFAOYSA-N lithium metasilicate Chemical compound [Li+].[Li+].[O-][Si]([O-])=O PAZHGORSDKKUPI-UHFFFAOYSA-N 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 239000010405 anode material Substances 0.000 description 2
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- 238000009792 diffusion process Methods 0.000 description 2
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- FUJCRWPEOMXPAD-UHFFFAOYSA-N lithium oxide Chemical compound [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 description 2
- 229910001947 lithium oxide Inorganic materials 0.000 description 2
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- 229910052708 sodium Inorganic materials 0.000 description 2
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- 229920003048 styrene butadiene rubber Polymers 0.000 description 2
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- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
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- 238000007605 air drying Methods 0.000 description 1
- 229910000905 alloy phase Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
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- JKWMSGQKBLHBQQ-UHFFFAOYSA-N diboron trioxide Chemical compound O=BOB=O JKWMSGQKBLHBQQ-UHFFFAOYSA-N 0.000 description 1
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
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- HCWCAKKEBCNQJP-UHFFFAOYSA-N magnesium orthosilicate Chemical compound [Mg+2].[Mg+2].[O-][Si]([O-])([O-])[O-] HCWCAKKEBCNQJP-UHFFFAOYSA-N 0.000 description 1
- 239000000391 magnesium silicate Substances 0.000 description 1
- 229910052919 magnesium silicate Inorganic materials 0.000 description 1
- 235000019792 magnesium silicate Nutrition 0.000 description 1
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- 229910044991 metal oxide Inorganic materials 0.000 description 1
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- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 150000003376 silicon Chemical class 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
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Images
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention relates to a double-doped silicon-based lithium ion negative electrode material and a preparation method and application thereof. The method comprises the following steps: mixing a nitrogen-containing gas source or a high-boiling-point nitrogen-containing compound serving as a first doping material and a metal or metal composite phase material serving as a second doping material in proportion, processing the second doping material and silicon and/or silicon dioxide into gas, mixing the gas with vapor of the first doping material, and depositing the gas on a substrate to obtain a silicon-oxygen composite material; cooling the silicon-oxygen composite material to room temperature, discharging, crushing and screening; and (4) carrying out carbon coating on the crushed and sieved material to obtain the double-doped silicon-based lithium ion negative electrode material.
Description
Technical Field
The invention relates to the technical field of material preparation, in particular to a double-doped silicon-based lithium ion negative electrode material and a preparation method and application thereof.
Background
With the rapid development of new energy automobiles, higher requirements are put forward on the performance of power batteries in the industry. The cathode material is one of the most critical materials of the lithium ion battery technology. The graphite negative electrodes currently on the market have reached their technical bottleneck due to their low gram capacity. And silicon-based materials are among the most promising lithium ion negative electrode materials to replace. The silicon-based anode material with the specific capacity of up to 4200mAh/g gradually shows the advantage of high energy density.
Amorphous silica consists of silicon clusters of 5nm or less uniformly dispersed in a silica matrix. The better cycling stability and high specific capacity (1200-1900 mAh/g) make it an alternative cathode material. The strong siloxane bond and the buffering of volume expansion by the lithium silicate and lithium oxide formed during cycling give them excellent cycling performance. However, the formation of lithium silicate and lithium oxide also leads to a higher first-cycle irreversible capacity of the silicon monoxide, resulting in a lower energy density of the lithium ion battery. The conductivity and the first-cycle coulombic efficiency can be improved by coating a carbon material, a metal oxide or a composite material on the surface of the silicon oxide.
In patent CN109286012A, researchers prepare a silica-carbon/graphene material with electrochemical activity by using a sol-gel method and a carbothermic method, and then prepare dispersed lithium silicate, which is a fast ion conductor, on the surface of the silica-carbon material by spin coating and heat treatment, to finally obtain the silica-carbon @ lithium silicate/graphene material. Although the ionic conductance and the electronic conductance are increased simultaneously in the work, the gram specific capacity of the lithium ion battery is lower and is only less than 800mAh/g, and the lower capacity also indicates that the quality of the prepared silicon monoxide composite material is poorer. In patent CN 107946568A, a hard carbon slurry/graphite and silica particles are compounded and carbonized at high temperature to obtain a hard carbon/graphite/silica composite material. The silica composite material has the advantages of both hard carbon and silica, but does not show excellent rate performance.
Disclosure of Invention
The embodiment of the invention provides a double-doped silicon-based lithium ion negative electrode material and a preparation method and application thereof.
In a first aspect, an embodiment of the present invention provides a preparation method of a double-doped silicon-based lithium ion anode material, including:
taking a nitrogen-containing gas source or a high-boiling-point nitrogen-containing compound as a first doping material, taking a metal or metal composite phase material as a second doping material, mixing the second doping material with silicon and/or silicon dioxide in proportion, then processing the mixture into gas, mixing the gas with the vapor of the first doping material, and depositing the gas on a substrate to obtain a silicon-oxygen composite material;
cooling the silicon-oxygen composite material to room temperature, discharging, crushing and screening;
and (4) carrying out carbon coating on the crushed and sieved material to obtain the double-doped silicon-based lithium ion negative electrode material.
Preferably, the nitrogen-containing gas source specifically comprises: one or more of nitrogen, ammonia, nitrous oxide, or dimethylamine;
the high-boiling nitrogen-containing compound specifically includes: carbonamides or melamines;
the metal or metal composite phase material specifically comprises: B. simple substances or alloy or composite oxide of one or more of Al, na, mg, ca, ba, ti, mn, fe, co, ni, cu, zn, zr, mo, ge and Sn.
Preferably, the vapor of the first doping material is obtained by heating the first doping material to 25 ℃ to 800 ℃.
Preferably, the mass of the first doping material accounts for 0.01-3% of the total mass of the silicon-oxygen composite material; the mass of the second doping material accounts for 2% -40% of the total mass of the silicon and the silicon dioxide.
Preferably, the molar ratio of silicon to silicon dioxide is silicon: silica =1:1.
preferably, the temperature of the substrate is 50 to 800 ℃.
Preferably, the carbon coating specifically comprises: placing the crushed and screened material in a rotary furnace, heating to 800-1000 ℃ under protective atmosphere, introducing an organic gas source for chemical vapor deposition, keeping the temperature for 2-4 hours, and then closing the organic gas source for cooling; wherein the organic gas source specifically comprises: one or more of methane, acetylene, propylene or propane; the mass of the carbon coating formed by carbon coating accounts for 1-10% of the mass of the silicon-oxygen composite material.
In a second aspect, an embodiment of the present invention provides a lithium ion battery negative electrode material, including the double-doped silicon-based lithium ion negative electrode material prepared by the preparation method in the first aspect.
In a third aspect, an embodiment of the present invention provides a lithium battery pole piece, where the lithium battery pole piece includes the lithium ion battery negative electrode material described in the second aspect.
In a fourth aspect, an embodiment of the present invention provides a lithium battery, where the lithium battery includes the lithium battery pole piece of the third aspect.
According to the preparation method of the double-doped silicon-based lithium ion cathode material, the introduced first doped material can be subjected to internal diffusion under the action of high temperature, so that the rate capability of the material is remarkably improved; the introduced second doping material can form a silicon-oxygen complex with the silicon oxide material, consume the inert substance silicon dioxide, generate a buffer area, slow down the volume expansion effect, improve the first-cycle efficiency and simultaneously increase the cycle stability. The carbon coating process can further increase the coating integrity and the electrical conductivity of the material.
Drawings
The technical solutions of the embodiments of the present invention are further described in detail below with reference to the accompanying drawings and embodiments.
Fig. 1 is a flow chart of a preparation method of a double-doped silicon-based lithium ion negative electrode material according to an embodiment of the invention;
fig. 2 is a scanning electron microscope image of the doped silicon-based lithium ion battery negative electrode material provided in embodiment 1 of the present invention.
Detailed Description
The invention is further illustrated by the following figures and specific examples, but it should be understood that these examples are for the purpose of illustration only and are not to be construed as in any way limiting the present invention, i.e., as in no way limiting its scope.
The preparation method of the double-doped silicon-based lithium ion negative electrode material comprises the following steps as shown in figure 1:
wherein the vapor of the first doping material is obtained by heating said first doping material to 25 ℃ -800 ℃.
In the first doping material, the nitrogen-containing gas source is a nitrogen-containing compound which is gaseous at normal temperature, and specifically can comprise one or more of nitrogen, ammonia, nitrous oxide or dimethylamine; the high-boiling point nitrogen-containing compound is a nitrogen-containing compound which is liquid or solid at normal temperature, and specifically may include one or more of carbamide or melamine.
The mass of the first doping material accounts for 0.01-3% of the total mass of the silicon-oxygen composite material; the mass of the second doping material accounts for 2% -40% of the total mass of the silicon and the silicon dioxide. The molar ratio of silicon to silicon dioxide is preferably silicon: silica =1:1.
the metal or metal composite phase material specifically includes: B. simple substances or alloy or composite oxide of one or more of Al, na, mg, ca, ba, ti, mn, fe, co, ni, cu, zn, zr, mo, ge and Sn.
The substrate is a carrier for vapor deposition, such as stainless steel, graphite or alumina, and the temperature of the substrate is 50-800 ℃.
and step 130, performing carbon coating on the crushed and sieved material to obtain the double-doped silicon-based lithium ion negative electrode material.
The carbon coating specifically comprises the following steps: placing the crushed and screened material in a rotary furnace, heating to 800-1000 ℃ under protective atmosphere, introducing an organic gas source for chemical vapor deposition, keeping the temperature for 2-4 hours, and then closing the organic gas source for cooling;
wherein, the organic gas source specifically comprises: one or more of methane, acetylene, propylene or propane; the mass of the carbon coating formed by carbon coating accounts for 1-10% of the mass of the silicon-oxygen composite material.
According to the preparation method, the introduced first doping material can perform internal diffusion under the action of high temperature, so that the rate capability of the material is remarkably improved; the introduced second doping material can form a silicon-oxygen complex with the silicon oxide material, consume the inert substance silicon dioxide, generate a buffer area, slow down the volume expansion effect, improve the first-cycle efficiency and simultaneously increase the cycle stability. The carbon coating process can further increase the coating integrity and the electrical conductivity of the material.
The double-doped silicon-based lithium ion negative electrode material prepared by the preparation method can be used as a lithium ion battery negative electrode material and applied to a lithium battery pole piece and a lithium battery.
In order to better understand the technical solutions provided by the present invention, the following description will respectively illustrate specific processes for preparing a negative electrode material of a lithium battery by using the methods provided by the above embodiments of the present invention, and methods for applying the negative electrode material to a lithium battery and battery characteristics.
Example 1
1.4kg of silicon powder, 3kg of silicon dioxide and 220g of magnesium metal are uniformly mixed and heated to form steam, 60g of melamine is heated to 320 ℃ to form steam, and the steam is uniformly mixed and then deposited on a substrate, wherein the substrate temperature is 500 ℃. And discharging, crushing and screening.
Placing 2kg of the sieved material in a rotary furnace, heating to 1000 ℃ under the protective argon atmosphere, and mixing the materials according to a volume ratio of 1:1, introducing argon and propane to carry out chemical vapor deposition, keeping the temperature for 2 hours, closing an organic gas source, and cooling to obtain the silicon-based lithium ion battery doped cathode material, wherein the magnesium content, the nitrogen content and the carbon content in the material are respectively 4.7%, 0.87% and 3%. And (3) a scanning electron microscope image of the double-doped silicon-based lithium ion battery cathode material.
Mixing the obtained silicon-based doped lithium ion battery negative electrode material, conductive additive carbon black and adhesive 1:1, sodium cellulose and styrene butadiene rubber, wherein the mass ratio of the sodium cellulose to the styrene butadiene rubber is 95%:2%:3% are weighed. And (5) placing the mixture into a beater to prepare the pulp at room temperature. And uniformly coating the prepared slurry on a copper foil. Drying in a forced air drying oven at 50 deg.C for 2 hr, cutting into 8 × 8mm pole pieces, and vacuum drying in a vacuum drying oven at 100 deg.C for 10 hr. And transferring the dried pole piece into a glove box for standby use to assemble a battery.
The simulated cell was assembled in a glove box containing a high purity Ar atmosphere using lithium metal as the counter electrode and 1 mole of LiPF 6 The solution in Ethylene Carbonate (EC)/dimethyl carbonate (DMC) was used as an electrolyte to assemble a battery. And (3) carrying out a constant-current charge-discharge mode test by using a charge-discharge instrument, wherein the discharge cutoff voltage is 0.005V, the charge cutoff voltage is 1.5V, the first-week charge-discharge test is carried out at a current density of C/10, and the second-week discharge test is carried out at a current density of C/10. The test data are shown in table 1.
Example 2
2.8kg of silicon powder, 6kg of silicon dioxide and 5kg of magnesium silicate are uniformly mixed and heated to be steam, 20g of nitrogen is introduced at the same time, the steam is mixed and deposited on a substrate, and the temperature of the substrate is 400 ℃. And (5) discharging, crushing and screening.
Placing 2kg of sieved materials in a rotary furnace, heating to 950 ℃ under the protective argon atmosphere, and mixing the materials according to a volume ratio of 1:1, introducing argon and propylene to carry out chemical vapor deposition, keeping the temperature for 4 hours, closing an organic gas source, and naturally cooling to obtain the double-doped silicon-based lithium ion battery cathode material.
The obtained negative electrode material had a magnesium content of 8.7%, a nitrogen content of 0.145%, and a carbon content of 6%.
The preparation process of the negative electrode plate, the battery assembly and the battery test method are the same as those in example 1.
Example 3
2.8kg of silicon powder, 6kg of silicon dioxide and 704g of magnesium metal are uniformly mixed and heated to form steam, at the same time 225g of carbamide is heated to 400 ℃ to form steam, and the steam is mixed and deposited on a substrate, wherein the temperature of the substrate is 500 ℃. And (5) discharging, crushing and screening.
Placing 2kg of sieved materials in a rotary furnace, heating to 800 ℃ under the protective argon atmosphere, and mixing the materials according to a volume ratio of 1: and 2, introducing argon and acetylene to carry out chemical vapor deposition, keeping the temperature for 1 hour, closing an organic gas source, and naturally cooling to obtain the double-doped silicon-based lithium ion battery cathode material.
The obtained negative electrode material had a magnesium content of 7.4%, a nitrogen content of 1.2%, and a carbon content of 3%.
The preparation process of the negative electrode plate, the battery assembly and the battery test method are the same as those in example 1.
Example 4
1.4kg of silicon powder, 3kg of silicon dioxide and 1.02kg of aluminum oxide are uniformly mixed and heated to be steam, 17g of ammonia gas is introduced at the same time, the steam is mixed and then deposited on a substrate, and the temperature of the substrate is 600 ℃. And (5) discharging, crushing and screening.
Placing 2kg of the sieved material in a rotary furnace, heating to 950 ℃ under the protective argon atmosphere, and mixing the materials according to the volume ratio of 1:2 introducing argon and mixed gas for chemical vapor deposition, wherein the mixed gas is prepared by mixing the components in a volume ratio of 1:1, preserving the heat for 1 hour, closing an organic gas source, and naturally cooling to obtain the double-doped silicon-based lithium ion battery cathode material.
The obtained cathode material contains 10% of aluminum, 0.25% of nitrogen and 3.5% of carbon.
The preparation process of the negative electrode plate, the battery assembly and the battery test method are the same as those in example 1.
Example 5
1.4kg of silicon powder, 3kg of silicon dioxide and 700g of boron oxide are uniformly mixed and heated to form steam, 126g of melamine is heated to 600 ℃ to form steam, the steam is mixed and deposited on a substrate, and the temperature of the substrate is 300 ℃. And (5) discharging, crushing and screening.
Placing 2kg of sieved materials in a rotary furnace, heating to 1000 ℃ under the protective argon atmosphere, and mixing the materials according to the volume ratio of 2: and 3, introducing argon and mixed gas for chemical vapor deposition, wherein the mixed gas is prepared by mixing the following components in a volume ratio of 2:1, preserving the heat for 2 hours, closing an organic gas source, and naturally cooling to obtain the double-doped silicon-based lithium ion battery cathode material.
The obtained cathode material contains 4.5% of boron, 1.65% of nitrogen and 8% of carbon.
The preparation process of the negative electrode plate, the battery assembly and the battery test method are the same as those in example 1.
Example 6
1.4kg of silicon powder, 3kg of silicon dioxide and 500g of tin are uniformly mixed and heated to be steam, 20g of nitrogen is simultaneously introduced, and the steam is mixed and deposited on a substrate at the temperature of 400 ℃. And (5) discharging, crushing and screening.
Placing 2kg of the sieved material in a rotary furnace, heating to 1000 ℃ under the protective argon atmosphere, and mixing the materials according to a volume ratio of 1:2 introducing argon and mixed gas for chemical vapor deposition, wherein the mixed gas is prepared by mixing the components in a volume ratio of 1:1, preserving the heat for 1 hour, closing an organic gas source, and naturally cooling to obtain the double-doped silicon-based lithium ion battery cathode material.
The obtained negative electrode material had a tin content of 10.2%, a nitrogen content of 0.41%, and a carbon content of 3%.
The preparation process of the negative electrode plate, the battery assembly and the battery test method are the same as those in example 1.
Example 7
1.4kg of silicon powder, 3kg of silicon dioxide and 400g of copper are uniformly mixed and heated to be steam, 20g of nitrogen is introduced at the same time, the steam is mixed and then deposited on a substrate, and the temperature of the substrate is 400 ℃. And discharging, crushing and screening.
Placing 2kg of sieved materials in a rotary furnace, heating to 950 ℃ under the protective argon atmosphere, and mixing the materials according to a volume ratio of 1:2 introducing argon and mixed gas for chemical vapor deposition, wherein the mixed gas is prepared by mixing the components in a volume ratio of 1:1, preserving the heat for 2 hours, closing an organic gas source, and naturally cooling to obtain the double-doped silicon-based lithium ion battery cathode material.
The obtained negative electrode material had a copper content of 8.3%, a nitrogen content of 0.41%, and a carbon content of 4%.
The preparation process of the negative electrode plate, the battery assembly and the battery test method are the same as those in example 1.
Comparative example 1
The present comparative example provides a lithium ion battery negative electrode material compared to example 1.
1.4kg of silicon powder and 3kg of silicon dioxide are placed in a high-temperature reaction furnace and heated to steam, 60g of melamine is heated to 320 ℃ to steam, the steam is mixed and deposited on a substrate, and the substrate temperature is 500 ℃. And (5) discharging, crushing and screening.
Placing 2kg of the sieved material in a rotary furnace, heating to 1000 ℃ under the protective argon atmosphere, and mixing the materials according to a volume ratio of 1:1, introducing argon and propane to carry out chemical vapor deposition, preserving the heat for 2 hours, closing an organic gas source, and naturally cooling to obtain the double-doped silicon-based lithium ion battery cathode material.
The nitrogen content in the obtained cathode material is 0.9%, and the carbon content is 3%.
The preparation process of the negative electrode plate, the battery assembly and the battery test method are the same as those in example 1.
Comparative example 2
Comparative example 2 provides a negative electrode material for a lithium ion battery, compared to example 1.
1.4kg of silicon powder, 3kg of silicon dioxide and 220g of magnesium metal are uniformly mixed and heated to be steam, and the steam is mixed and deposited on a substrate, wherein the temperature of the substrate is 500 ℃. And (5) discharging, crushing and screening.
Placing 2kg of the sieved material in a rotary furnace, heating to 1000 ℃ under the protective argon atmosphere, and mixing the materials according to a volume ratio of 1:1, introducing argon and propane to carry out chemical vapor deposition, preserving the heat for 2 hours, closing an organic gas source, and naturally cooling to obtain the double-doped silicon-based lithium ion battery cathode material.
The obtained negative electrode material has a magnesium content of 5% and a carbon content of 3%.
The preparation process of the negative electrode plate, the battery assembly and the battery test method are the same as those in example 1.
The above negative electrode materials of examples 1 to 7 and comparative examples 1 to 2 were subjected to the initial efficiency, 0.1C reversible capacity, and full-cell cycle retention rate (450 mAh/g using graphite) index tests, and the results are shown in table 1.
TABLE 1
As can be seen from the data in Table 1, under the same conditions, the first cycle efficiency is obviously improved by adopting a double-doped system in examples 1 to 7. The material of comparative example 1 lacks a metal composite phase and is inefficient for the first week. Although the capacity was high, the cycle stability was poor after 100 and 500 cycles, indicating that the long term cycle retention was low in the absence of buffer regions created by the alloy phase. Comparative example 2 is not doped with nitrogen, and its rate performance is not good under high rate conditions.
The preparation method of the double-doped silicon-based lithium ion negative electrode material provided by the invention has the advantages that the obtained material has higher first-cycle efficiency and better cycle stability.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A preparation method of a double-doped silicon-based lithium ion negative electrode material is characterized by comprising the following steps:
mixing a nitrogen-containing gas source or a high-boiling-point nitrogen-containing compound serving as a first doping material and a metal or metal composite phase material serving as a second doping material in proportion, processing the second doping material and silicon and/or silicon dioxide into gas, mixing the gas with vapor of the first doping material, and depositing the gas on a substrate to obtain a silicon-oxygen composite material;
cooling the silica composite material to room temperature, discharging, crushing and screening;
and (3) carrying out carbon coating on the crushed and sieved material to obtain the double-doped silicon-based lithium ion negative electrode material.
2. The method according to claim 1, wherein the nitrogen-containing gas source specifically comprises: one or more of nitrogen, ammonia, nitrous oxide or dimethylamine;
the high-boiling nitrogen-containing compound specifically includes: carbonamides or melamines;
the metal or metal composite phase material specifically comprises: B. simple substances or alloy or composite oxide of one or more of Al, na, mg, ca, ba, ti, mn, fe, co, ni, cu, zn, zr, mo, ge and Sn.
3. The production method according to claim 1, wherein the vapor of the first doping material is obtained by heating the first doping material to 25 ℃ -800 ℃.
4. The preparation method according to claim 1, wherein the mass of the first doping material accounts for 0.01% -3% of the total mass of the silicon-oxygen composite material; the mass of the second doping material accounts for 2% -40% of the total mass of the silicon and the silicon dioxide.
5. The method according to claim 1, wherein the molar ratio of silicon to silicon dioxide is silicon: silica =1:1.
6. the method of claim 1, wherein the substrate has a temperature of 50-800 ℃.
7. The preparation method according to claim 1, wherein the carbon coating is specifically: placing the crushed and screened materials in a rotary furnace, heating to 800-1000 ℃ under a protective atmosphere, introducing an organic gas source for chemical vapor deposition, keeping the temperature for 2-4 hours, and then closing the organic gas source for cooling; wherein the organic gas source specifically comprises: one or more of methane, acetylene, propylene or propane; the mass of the carbon coating formed by carbon coating accounts for 1-10% of the mass of the silicon-oxygen composite material.
8. The lithium ion battery negative electrode material is characterized in that the negative electrode material is the double-doped silicon-based lithium ion negative electrode material prepared by the preparation method of any one of claims 1 to 7.
9. A lithium battery pole piece, characterized in that, the lithium battery pole piece comprises the lithium ion battery negative electrode material of claim 8.
10. A lithium battery comprising a lithium battery electrode sheet according to claim 9.
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