CN111342030B - Multi-element composite high-first-efficiency lithium battery negative electrode material and preparation method thereof - Google Patents
Multi-element composite high-first-efficiency lithium battery negative electrode material and preparation method thereof Download PDFInfo
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Abstract
The invention relates to a multi-element composite high-first-efficiency lithium battery cathode material and a preparation method thereof, wherein the cathode material is formed by co-doping Li and Mg to form SiOx-lithium silicate-magnesium silicate multi-component composite system. The negative electrode material comprises silicon compound particles and a conducting layer coated on the surfaces of the silicon compound particles, and further comprises lithium silicate and magnesium silicate, wherein the molar ratio of lithium atoms in the lithium silicate to magnesium atoms in the magnesium silicate is 0.01: 1-100: 1. The invention combines the characteristics of high ionic conductivity of lithium silicate and high bonding strength of magnesium silicate, further improves the first coulombic efficiency of the material and prolongs the cycle life.
Description
Technical Field
The invention relates to the field of lithium battery materials, in particular to a multi-element composite lithium battery negative electrode material and a preparation method thereof.
Background
The silicon negative electrode material is considered to be a next generation high energy density lithium ion battery negative electrode material with great potential due to the advantages of higher theoretical specific capacity (4200 mA.h/g at high temperature and 3580 mA.h/g at room temperature), low delithiation potential (< 0.5V), environmental friendliness, abundant reserves, lower cost and the like. However, the electrical conductivity of silicon is low, and the volume change is large (about 300%) in the lithium intercalation and deintercalation process, so that the material is easy to gradually pulverize, the structure is collapsed, and finally, the electrode active substance is separated from the current collector, the electric contact is lost, and the cycle performance of the battery is greatly reduced; in addition, due to such a volume effect, silicon has difficulty in forming a stable Solid Electrolyte Interface (SEI) film in an electrolyte solution; with the destruction of the electrode structure, new SEI films are continuously formed on the exposed silicon surface, which aggravates silicon corrosion and capacity fade.
Silicon oxide (SiO)x) The carbon-based composite material has a capacity (about 1500mAh/g) which is smaller than that of silicon but is several times higher than that of a carbon-based negative electrode (about 350mAh/g), and has a structure in which silicon nanocrystals are uniformly dispersed in a silicon dioxide matrix, thereby having a greater application value than other silicon-based materials. However, in silicon oxide, lithium reacts with silicon oxide during initial charge to generate lithium oxide (including lithium oxide, lithium silicate, and the like), and the generated lithium oxide cannot reversibly return to the positive electrode during discharge, so that irreversible capacity increases and initial charge/discharge efficiency (ICE) greatly decreases.
To improve the initial charge/discharge efficiency of silicon oxide (SiOx), patent CN201480059867.2 produced Li-doped Si/SiO by electrochemical methodsxThe material improves the first charge-discharge efficiency, but still has the problems of capacity reduction, unstable slurry and the like; patent application CN201710193442.6 by mixing SiOxReacting with metallic magnesium to prepare Mg-doped Si/SiOxThe first efficiency of the material is greatly improved, but the silicon crystal grain size is overlarge due to the addition of Mg, and the process is not easy to control, so that the cycle performance of the material is poor.
Disclosure of Invention
In view of the above, the present invention provides a multi-component composite high-first-efficiency lithium battery negative electrode material and a preparation method thereof, wherein the first coulombic efficiency and the cycle life of the material are improved by multi-component co-doping of lithium silicate and magnesium silicate.
In a first aspect, the invention provides a multi-element composite high-first-efficiency lithium battery negative electrode material, which comprises silicon compound particles and a conducting layer coated on the surfaces of the silicon compound particles, and further comprises lithium silicate and magnesium silicate, wherein the molar ratio of lithium atoms in the lithium silicate to magnesium atoms in the magnesium silicate is [ z1] 0.01: 1-100: 1.
Further, the total mass of the silicon compound particles and the conductive layer is 100%, wherein the mass percentage of the lithium silicate and the magnesium silicate is 3-83%.
Further, the silicon compound particles have a chemical formula of SiOxWherein, 0<x<2; the conductive layer is a carbon layer.
Further, the conducting layer also contains one or more combinations of metal oxide, non-metal oxide, phosphate and fluoride.
Further, the particle diameter of the silicon compound particles is 1 to 20 μm, preferably 2 to 10 μm.
Further, the carbon layer comprises one or more of soft carbon, hard carbon, carbon black, graphite, graphene, carbon nanotubes, carbon fibers and mesocarbon microbeads; the carbon layer has a thickness of 2 to 1000nm, preferably 5 to 200 nm.
Further, the lithium silicate includes Li2SiO3、Li2Si2O5、Li4SiO4、Li6Si2O7One or more combinations of (a); the magnesium silicate comprises MgSiO3、Mg2SiO4、Mg4SiO6One or more combinations thereof.
The molar ratio of lithium atoms in the lithium silicate to magnesium atoms in the magnesium silicate is [ z2] 0.01: 1-100: 1, preferably 0.02: 1-50: 1, more preferably 0.04: 1-25: 1, and most preferably 0.1: 1-10: 1. If the ratio is lower than 0.01:1, excessive magnesium atom doping can cause the size of silicon crystal grains to be increased, and the first coulombic efficiency is low; above 100:1 results in unstable slurry and poor cycle stability.
The mass percentage of the lithium silicate and the magnesium silicate is 3-83%, preferably 13-73%, based on the total mass of the silicon compound and the conductive layer as 100%. If the content is less than 3 percent, the volume expansion effect of the buffer material is poor, the first coulombic efficiency is low, the circulation stability is poor, and if the content is more than 83 percent, the capacity is obviously reduced, and the processability of the material is poor. Preferably 13-73%, and the best effect among first effect, circulation and capacity can be obtained.
The silicon compound particles have a particle size of 1 to 20 μm, preferably 2 to 10 μm. Too small a grain size results in too low a packing density, thereby reducing charge and discharge capacity per unit volume; too large a grain size leads to an increased volume expansion effect and reduced cyclability.
The carbon layer has a thickness of 2 to 1000nm, preferably 5 to 200 nm. If the thickness of the carbon layer is too small, the buffering volume expansion effect is not obvious, the conductivity is not improved to a large extent, and the cycle performance is poor; too large a carbon layer thickness indicates that too high a carbon content will decrease the anode capacity and make the bulk density too low, thereby decreasing the charge and discharge capacity per unit volume.
In a second aspect, the invention provides a preparation method of the above multi-element composite lithium battery negative electrode material, and the first preparation method comprises the following steps:
mixing silicon powder and SiO2Uniformly mixing the powder and magnesium powder, heating for sublimation, cooling to obtain a precursor with modified magnesium doping, coating the precursor with a conducting layer, and then carrying out pre-lithiation treatment to obtain the multi-element composite negative electrode material. According to the method, the conductive material is coated and then doped with lithium, so that SiC generated at the interface of the silicon-oxygen material and the conductive layer is reduced as much as possible, and the volume expansion of the silicon crystal can be inhibited, so that the material has better electrochemical performance.
The second preparation method comprises the following steps:
mixing silicon powder and SiO2The powder, the lithium source and the magnesium powder are placed in three chambers with different temperatures, the three chambers are collected in a collection chamber together, silicon monoxide vapor, lithium vapor and magnesium vapor are subjected to co-sublimation deposition to obtain a lithium-magnesium co-doped modified precursor, and the precursor is subjected to conductive layer coating; the lithium source includes metallic lithium, lithium oxide, lithium hydroxide, lithium carbonate, lithium hydride, lithium nitride, lithium fluoride, lithium chloride, lithium bromide, and the like. According to the method, the silicon source, the lithium source and the magnesium source are respectively arranged in the three chambers, so that the precise control of the doping amount can be realized.
According to the preparation method of the multi-element composite lithium battery cathode material provided by the invention, the precursor of magnesium doping modification is prepared by leading silicon powder and SiO to be mixed under the conditions of high temperature and high vacuum2Mixing the powder and magnesium powder, evaporating or evaporating separately, reacting in gas phase, condensing and depositing; the silicon powder, the silicon dioxide powder and the magnesium powderThe particle size of (A) is 0.1 to 20 μm.
The precursor is also subjected to crushing and screening steps, and finally the silicon monoxide precursor with the granularity of 1-20 mu m is obtained.
The coating is that the conductive layer is coated on the surface of the precursor by one or more of liquid phase coating, solid phase coating, vapor deposition coating or mechanical coating.
The pre-lithiation treatment is to achieve the purpose of doping lithium silicate by one or more methods of a gas phase CVD method, a thermal doping method, a redox method or an electrochemical method.
Compared with the prior art, the multi-element composite high-first-efficiency lithium battery cathode material and the preparation method thereof provided by the invention have the following beneficial effects:
(1) the high bonding strength of the magnesium silicate provides powerful structural protection for the whole body, the lithium silicate has the characteristics of high ion conductivity and ultrahigh first efficiency, and the first coulombic efficiency and the cycle performance of the material are greatly improved by the multi-component compounding of the lithium silicate and the magnesium silicate;
(2) in the process, the structural foundation is provided by pre-magnesiation, and then pre-lithiation is carried out to provide the first effect guarantee.
Drawings
FIG. 1 is a schematic structural diagram of a multi-component high-efficiency lithium battery composite material of the present invention;
FIG. 2 is an XRD pattern of example 1 of the present invention;
figure 3 is an XRD pattern of example 2 of the invention.
Detailed Description
The present invention will be further described with reference to the following examples, but the present invention is not limited to the following examples.
In order to solve the problems of low first efficiency and poor cycle of the existing silicon-based material caused by high volume expansion, an embodiment of the invention provides a multi-element composite lithium battery negative electrode material, as shown in fig. 1, the negative electrode material comprises silicon compound particles 1 and a conductive layer 2 coated on the surfaces of the silicon compound particles, the negative electrode material further comprises lithium silicate 3 and magnesium silicate 4, and the molar ratio of lithium atoms in the lithium silicate 3 to magnesium atoms in the magnesium silicate 4 is 0.01: 1-100: 1, preferably 0.02: 1-50: 1, more preferably 0.04: 1-25: 1, and most preferably 0.1: 1-10: 1.
The mass percentage of the lithium silicate 3 and the magnesium silicate 4 is 3-83%, preferably 13-73%, based on 100% of the total mass of the silicon compound 1 and the conductive layer 2.
Lithium silicate 3 includes Li2SiO3、Li2Si2O5、Li4SiO4、Li6Si2O7One or more combinations of (a); magnesium silicate 4 comprises MgSiO3、Mg2SiO4、Mg4SiO6One or more combinations thereof.
According to the multi-element composite high-first-efficiency lithium battery cathode material provided by the invention, the magnesium silicate is dispersed in the inner core, so that the volume expansion of the silicon material can be effectively buffered, the structural stability is improved, and meanwhile, the lithium salt is codoped, so that the Li is ensured in the first charge-discharge process+The two doping elements are matched with each other, so that the high first-efficiency and long-cycle performance of the material is realized.
The embodiment of the invention correspondingly provides a preparation method of the material, and in order to better understand the preparation process and the performance characteristics of the material provided by the invention, the following description is combined with specific embodiments. The experimental methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials are commercially available, unless otherwise specified.
In the examples, the contents of lithium silicate and magnesium silicate in the multi-element composite negative electrode material were measured by inductively coupled plasma atomic emission spectrometry (ICP-AES) to determine the contents of metal elements.
Example 1
Mixing Si powder and SiO powder with a certain amount of medium diameter D50=5 μm2The powder and the metal magnesium powder are mixed evenly and added into a vacuum furnace for heat treatment. Heating to 1100 deg.C under 500Pa vacuum degree, and heat treating for 1 h. Sublimating the powder under the conditions of high temperature and vacuum, and condensing steam to obtain the magnesium-uniformly-doped silicon monoxide precursor. And then crushing and screening to obtain particles with the particle size of 1-10 um.
The particles obtained above were charged into a CVD furnace, and propylene at a flow rate of 9L/min and argon at a flow rate of 18L/min were introduced for a deposition time of 1 hour. Cracking propylene at high temperature, coating pyrolytic carbon on the particle surface to obtain carbon-coated magnesium-doped SiO composite powder, wherein the thickness of the carbon coating layer is 80 nm. The composite powder obtained above is mixed with a certain amount of Li3N powder uniformly, and simultaneously added into a high-temperature furnace for heat treatment. Heating to 800 ℃ under the protection of argon, and the heat treatment time is 2 h. And (3) pyrolyzing Li3N at high temperature, inserting active lithium into the silicon protoxide to complete prelithiation, and obtaining the multi-element composite negative electrode material, wherein the molar ratio of lithium atoms to magnesium atoms is 1:1, and the content of lithium silicate and magnesium silicate is 40%.
When the X-ray diffraction peak of the multi-composite anode material was analyzed by the X-ray diffraction analyzer, and fig. 2 is the XRD diffraction pattern of the multi-composite anode material obtained in example 1, it can be seen that Li appears at the positions of 2 θ =18.9 °, 27 °, 33.1 °, 38.6 ° and 43.4 °2SiO3A peak of (a); at positions of 2 θ =23.86 ° and 24.6 °, Li appears2Si2O5A peak of (a); at positions 2 θ =22.9 °, 35.7 °, 36.5 ° and 39.7 °, Mg appears2SiO4A peak of (a); at the position of 2 θ =31.1 °, MgSiO appears3The peak of (a) indicates that Li and Mg are successfully doped in the form of silicate.
Example 2
And co-doping lithium and magnesium simultaneously by using a CVD furnace with a plurality of deposition chambers. Respectively putting certain amount of Si powder and SiO with uniform mixing and medium diameter D50=5 μm into the deposition chamber 12Powder, a certain amount of magnesium powder is put into the deposition chamber 2, and a certain amount of LiCl powder is put into the deposition chamber 3. The deposition chamber 1 is heated to 1100 deg.C to cause Si and SiO2And (4) sublimating. The deposition chamber 2 was heated to 1100 deg.c to sublimate the Mg powder. The deposition chamber 3 was heated to 950 ℃ to vaporize LiCl. Vacuumizing 3 deposition chambers, controlling the vacuum degree at 100Pa, controlling the reaction time at 1h, and then co-depositing gasified LiCl steam, SiO steam and Mg steam in a collection chamber to obtain the magnesium and lithium co-doped SiO composite powder. And then crushing and screening to obtain particles with the particle size of 1-10 um.
The particles obtained above were charged into a CVD furnace, and propylene at a flow rate of 9L/min and argon at a flow rate of 18L/min were introduced for a deposition time of 1 hour. Cracking propylene at high temperature, coating pyrolytic carbon on the surfaces of the particles to obtain carbon-coated magnesium and lithium co-doped SiO composite powder, wherein the thickness of the carbon coating layer is 80 nm. Wherein the molar ratio of lithium atoms to magnesium atoms is 1:1, and the content of lithium silicate and magnesium silicate is 40%.
An X-ray diffraction peak of the multi-component composite anode material was analyzed by an X-ray diffraction analyzer, and fig. 3 is an XRD diffraction pattern of the multi-component composite anode material obtained in example 2, and it can be seen that Li appears at positions of 2 θ =18.9 °, 27 °, 33.1 °, and 38.6 °2SiO3A peak of (a); at positions of 2 θ =23.86 ° and 24.6 °, Li appears2Si2O5A peak of (a); at the position of 2 θ =36.5 °, Mg appears2SiO4A peak of (a); at the position of 2 θ =31.1 °, MgSiO appears3The peak of (a) indicates that Li and Mg are successfully doped in the form of silicate.
Examples 3 to 10
The other steps and process parameters are the same as those in example 1, except that Si powder and SiO are added2The powders, metal magnesium powders and Li3N powders were varied in mass by varying the molar ratio of lithium atoms to magnesium atoms and the content of lithium silicate and magnesium silicate.
Comparative example 1
Mixing Si powder and SiO powder with a certain amount of medium diameter D50=5 μm2Mixing the powders, heating to 1100 deg.C under 500Pa vacuum degree for 1 hr, sublimating the powder at high temperature under vacuum condition, and condensing the vaporObtaining the precursor of the silicon monoxide. And then crushing and screening to obtain particles with the particle size of 1-10 um. The particles obtained above were charged into a CVD furnace, and propylene at a flow rate of 9L/min and argon at a flow rate of 18L/min were introduced for a deposition time of 1 hour. Cracking propylene at high temperature, coating pyrolytic carbon on the surface of the particles to obtain carbon-coated SiO powder, wherein the thickness of the carbon coating layer is 80 nm.
The SiO powder obtained above is uniformly mixed with a certain amount of Li3N powder, and simultaneously, the mixture is added into a high-temperature furnace for heat treatment. Heating to 800 ℃ under the protection of argon, and the heat treatment time is 2 h. And (3) pyrolyzing Li3N at high temperature, inserting active lithium into the silicon protoxide to complete prelithiation, and preparing the lithium-doped silicon-carbon negative electrode material, wherein the content of lithium silicate is 46%.
Comparative example 2
Mixing Si powder and SiO powder with a certain amount of medium diameter D50=5 μm2The powder and the metal magnesium powder are mixed evenly and added into a vacuum furnace for heat treatment. Heating to 1100 deg.C under 500Pa vacuum degree, and heat treating for 1 h. Sublimating the powder under the conditions of high temperature and vacuum, and condensing steam to obtain a magnesium-uniformly-doped silicon monoxide precursor, wherein the content of magnesium silicate is 2%. And then crushing and screening to obtain particles with the particle size of 1-10 um.
The particles obtained above were charged into a CVD furnace, and propylene at a flow rate of 9L/min and argon at a flow rate of 18L/min were introduced for a deposition time of 1 hour. Cracking propylene at high temperature, and coating pyrolytic carbon on the surface of the particles to obtain the carbon-coated magnesium-doped silicon-carbon cathode material, wherein the thickness of the carbon coating layer is 80 nm.
Comparative example 3
Mixing Si powder and SiO powder with a certain amount of medium diameter D50=5 μm2The powder is uniformly mixed, heated to 1100 ℃ under the condition of 500Pa vacuum degree, the heat treatment time is 1h, the powder is sublimated under the conditions of high temperature and vacuum, and the precursor of the silicon monoxide is obtained after the steam is condensed. And then crushing and screening to obtain particles with the particle size of 1-10 um. The particles obtained above were charged into a CVD furnace, and propylene at a flow rate of 9L/min and argon at a flow rate of 18L/min were introduced for a deposition time of 1 hour. Cracking propylene at high temperature, coating pyrolytic carbon on the surface of the particles to obtain carbon-coated pure SiO negativeThe electrode material and the carbon coating layer are 80nm thick.
The lithium battery negative electrode materials prepared in the examples and the comparative examples were assembled into lithium batteries, respectively, and the chemical properties thereof were tested.
First, the first efficiency of the material is obtained in the following manner. According to the mass ratio of 80: 9: 1: 10 mixing the prepared anode material powder: SP (carbon black): CNT (carbon nanotube): PAA (polyacrylic acid) is mixed, a proper amount of deionized water is added as a solvent, and the mixture is continuously stirred for 8 hours to be pasty by a magnetic stirrer. And pouring the stirred slurry onto a copper foil with the thickness of 9 mu m, coating the copper foil by using an experimental coater, and drying the coated copper foil for 6 hours at the temperature of 85 ℃ under the vacuum (-0.1 MPa) condition to obtain the negative electrode slice. Rolling the electrode sheet to 100 μm on a manual double-roller machine, making into 12mm diameter wafer with a sheet punching machine, drying at 85 deg.C under vacuum (-0.1 MPa) for 8 hr, weighing, and calculating active substance weight. A CR2032 button cell is assembled in a glove box, a metal lithium sheet is taken as a counter electrode, a polypropylene microporous membrane is taken as a diaphragm, and 1mol/L LiPF6 in EC: DEC =1:1 Vol% with 5.0% FEC as electrolyte. And standing the prepared button cell for 12h at room temperature, performing constant-current charge-discharge test on a blue-ray test system, performing charge-discharge at a current of 0.1C, and obtaining the first efficiency of the cathode material at a delithiation cut-off voltage of 1.5V.
Further, the capacity retention rate was calculated in the following manner. Mixing the prepared negative electrode material powder with a graphite negative electrode (mass ratio of 20: 80) to obtain mixed negative electrode powder, and mixing the mixed negative electrode powder with the graphite negative electrode powder according to a mass ratio of 95.2: 0.85: 0.15: 1.2: 2.6 mixing the mixed negative electrode powder, SP, CNT, CMC (sodium carboxymethylcellulose) and SBR (styrene butadiene rubber), and continuously stirring for 8h to be pasty by using a magnetic stirrer. And pouring the stirred slurry onto a copper foil with the thickness of 9 mu m, coating the copper foil by using an experimental coater, and drying the coated copper foil for 6 hours at the temperature of 85 ℃ under the vacuum (-0.1 MPa) condition to obtain the negative electrode slice. Then, according to the mass ratio of 90: 2: 1: 7 mixing 811 positive electrode material, SP, CNT, PVDF (polyvinylidene fluoride), adding appropriate amount of NMP (N-methyl pyrrolidone) as solvent, and continuously stirring with magnetic stirrer for 8h to paste. And pouring the stirred slurry onto an aluminum foil with the thickness of 16 mu m, coating the aluminum foil by using an experimental coater, and drying the aluminum foil for 6 hours at the temperature of 85 ℃ under the vacuum (-0.1 MPa) condition to obtain the positive electrode sheet. Rolling the positive and negative electrode plates to 100 μm in sequence on a manual double-roller machine, preparing a wafer with a diameter of 12mm by using a sheet punching machine, drying for 8h at 85 ℃ under a vacuum (-0.1 MPa), weighing, and calculating the weight of the active substance. The CR2032 button full cell is assembled in a glove box, a polypropylene microporous membrane is taken as a diaphragm, 1mol/L LiPF6 in EC: DEC =1:1 Vol% with 5.0% FEC as electrolyte. And standing the prepared button full cell at room temperature for 12h, performing constant-current charge-discharge test on a blue-ray test system, and performing charge-discharge at a current of 0.25C with a charge-discharge cutoff voltage of 3.0-4.25V. The capacity retention rate was calculated by multiplying the discharge capacity at the 100 th cycle/the discharge capacity at the 1 st cycle by 100%.
The test results are shown in table 1.
TABLE 1 lithium cell negative electrode Material withholding test results
As can be seen from Table 1, the battery assembled by the multi-element composite lithium battery negative electrode material provided by the invention has excellent performance, high first coulombic efficiency and good cycle performance, and the obtained material can be used as the lithium battery negative electrode material by adjusting the doping ratio of lithium salt and magnesium salt, so that the comprehensive performance of the battery can reach the optimal level. Comparative example 1 is not doped with magnesium, and although the first effect is high, the structural strength is reduced, so that the capacity retention rate is obviously reduced compared with that of the embodiment; comparative example 2 is not pre-lithiated, and a large amount of active lithium is consumed during the first lithium intercalation, so the first effect is obviously reduced compared with the example; comparative example 3 shows the lowest first efficiency and capacity retention.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (8)
1. A multi-element composite high-efficiency lithium battery cathode material comprises core silicon compound particles and a conductive layer coated on the surfaces of the silicon compound particles,
lithium silicate and magnesium silicate are dispersed in the inner core, and the molar ratio of lithium atoms in the lithium silicate to magnesium atoms in the magnesium silicate is 0.01: 1-100: 1;
the negative electrode material is prepared by mixing silicon powder and SiO2Uniformly mixing the powder and magnesium powder, heating for sublimation, cooling to obtain a precursor modified by doping magnesium, coating the precursor with a conductive layer, and then carrying out pre-lithiation treatment to obtain the magnesium-doped modified magnesium-doped magnesium alloy;
the silicon compound particles have the chemical formula SiOx, wherein 0< x < 2; the conductive layer is a carbon layer.
2. The negative electrode material for a multi-element composite high-first-efficiency lithium battery as claimed in claim 1,
and the total mass of the silicon compound particles and the conductive layer is 100%, wherein the mass percentage of the lithium silicate and the magnesium silicate is 3-83%.
3. The negative electrode material for a multi-element composite high-first-efficiency lithium battery as claimed in claim 1,
the silicon compound particles have a particle size of 1 to 20 μm.
4. The negative electrode material for a multi-element composite high-efficiency lithium battery as claimed in claim 3, wherein the silicon compound particles have a particle size of 2 to 10 μm.
5. The method for preparing the negative electrode material of the multi-element composite high-first-efficiency lithium battery as claimed in claim 1,
the carbon of the carbon layer comprises one or more of soft carbon, hard carbon, carbon black, graphite, graphene, carbon nanotubes and carbon fibers; the carbon layer has a thickness of 2-1000 nm.
6. The method for preparing the anode material for the multi-element composite high-first-efficiency lithium battery as claimed in claim 5, wherein the carbon layer has a thickness of 5-200 nm.
7. The negative electrode material for a multi-element composite high-first-efficiency lithium battery as claimed in claim 1,
the lithium silicate includes Li2SiO3、Li2Si2O5、Li4SiO4、Li6Si2O7One or more combinations of (a); the magnesium silicate comprises MgSiO3、Mg2SiO4One or more combinations thereof.
8. A method for preparing the negative electrode material of the multi-element composite high-first-efficiency lithium battery as claimed in any one of the claims 1 to 7,
the method comprises the following steps:
mixing silicon powder and SiO2Uniformly mixing the powder and magnesium powder, heating for sublimation, cooling to obtain a precursor with modified magnesium doping, coating the precursor with a conducting layer, and then carrying out pre-lithiation treatment to obtain the multi-element composite negative electrode material.
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| CN111969191B (en) * | 2020-08-26 | 2021-12-10 | 山东兴丰新能源科技有限公司 | Lithium ion battery cathode material based on metal oxide and preparation method thereof |
| CN112310368B (en) * | 2020-10-16 | 2023-09-12 | 欣旺达电动汽车电池有限公司 | Negative electrode active material, preparation method and application thereof, and lithium ion battery |
| CN112331854A (en) * | 2020-10-30 | 2021-02-05 | 浙江锂宸新材料科技有限公司 | Lithium magnesium silicate pre-lithiated silicon monoxide negative electrode material and preparation method and application thereof |
| CN113380997B (en) * | 2021-05-25 | 2022-07-29 | 万向一二三股份公司 | Silicon-based negative electrode material of lithium ion battery and preparation method thereof |
| CN113381024B (en) * | 2021-06-30 | 2023-03-31 | 惠州亿纬锂能股份有限公司 | Silica negative electrode material, preparation method thereof and lithium ion battery |
| CN113594444B (en) * | 2021-07-29 | 2022-06-14 | 溧阳紫宸新材料科技有限公司 | Silicon-oxygen negative electrode material with mixed crystal phase and preparation method and application thereof |
| CN114014325B (en) * | 2021-10-18 | 2023-08-29 | 长沙矿冶研究院有限责任公司 | Method and reaction device for preparing porous silicon anode material by magnesia reduction |
| CN114400310A (en) * | 2022-01-14 | 2022-04-26 | 中国科学院宁波材料技术与工程研究所 | High-first-efficiency graphene composite silicon-carbon negative electrode material, preparation method thereof and battery |
| CN114672713B (en) * | 2022-04-21 | 2022-09-16 | 胜华新能源科技(东营)有限公司 | Preparation method of lithium-containing metal silicon, lithium-containing SiO and application thereof |
| CN115385342A (en) * | 2022-07-20 | 2022-11-25 | 长沙矿冶研究院有限责任公司 | Silicon protoxide material, preparation method, application and device thereof |
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