CN111682204A - Rare earth element doped silicate positive electrode material, and preparation method and application thereof - Google Patents

Rare earth element doped silicate positive electrode material, and preparation method and application thereof Download PDF

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CN111682204A
CN111682204A CN202010567407.8A CN202010567407A CN111682204A CN 111682204 A CN111682204 A CN 111682204A CN 202010567407 A CN202010567407 A CN 202010567407A CN 111682204 A CN111682204 A CN 111682204A
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lithium
rare earth
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doped silicate
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屈龙
李明涛
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XI'AN JIAOTONG UNIVERSITY SUZHOU ACADEMY
Suzhou Academy of Xian Jiaotong University
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Abstract

The invention discloses a rare earth element doped silicate anode material, a preparation method and application thereof, wherein the rare earth element doped silicate anode material comprises an active component Li2M1‑3/2xRxSiO4And wrapping in active component Li2M1‑3/ 2xRxSiO4An outer conductive agent coating layer; wherein M isOne or the combination of Fe and Mn, R is one or the combination of more of La, Ce, Nd, Sm and Yb, x is more than 0 and less than or equal to 2/3, the anode material has the characteristics of high ionic conductivity and good cycle performance, and the preparation method is simple.

Description

Rare earth element doped silicate positive electrode material, and preparation method and application thereof
Technical Field
The invention belongs to the field of energy chemical industry and material science, and relates to a rare earth element doped silicate anode material, and a preparation method and application thereof.
Background
In the face of increasing shortage of traditional petrochemical energy, new energy technologies such as solar energy, wind energy, geothermal energy, tidal energy and the like are rapidly developed in the last decade. The key link for the efficient utilization of the new energy is an energy storage and conversion device. Among many energy storage devices, lithium ion batteries have attracted much attention because of their advantages such as low self-discharge rate, high energy conversion efficiency, and long cycle life. In order to meet the needs of large-scale energy storage technologies, researchers have not been able to develop high-capacity lithium ion batteries. Under the guidance of pioneering work by mr. goodnovery, who is a nobel prize winner of chemistry, a great deal of research has focused on polyanionic positive electrode materials. Among these, lithium transition metal orthosilicate (Li)2FeSiO4And Li2MnSiO4) The method is made by the advantages of high theoretical capacity (about 330mAh g-1), low manufacturing cost and environmental protection.
In view of the low conductivity and slow lithium ion diffusion of the silicate cathode material, the reduction of the active material particle size and the coating of highly conductive materials (inorganic carbon materials or conductive polymers) are the main means for improving the electrochemical performance. To date, various techniques have been used to synthesize silicate positive electrode materials. The solid phase method needs to be sintered for a long time at a higher temperature, and the particle size of the obtained material is micron-sized, so that the method is not favorable for exerting the advantage of high theoretical capacity. The particle size obtained by the hydrothermal process is small, but it is difficult to obtain a product of high purity and high crystallinity for silicates. The sol-gel method can obtain the atomic-level dispersion degree of Li, Fe and Si elements in a dry glue precursor, so that the method is commonly used for preparing high-purity nano silicate anode materials. The material synthesized by adopting a hydrothermal-assisted or microwave-assisted sol-gel method has better rate capability. By combining with the in-situ carbon coating technology, the sol-gel method can prevent the silicate active substance particles from growing in the sintering process, and is beneficial to shortening the lithium ion diffusion path.
Cation doping is also one of the effective methods for increasing lithium ion diffusion of the polyanionic positive electrode material. Heretofore, polyanionic cathode materials doped with Mg, V, Cr, Co, Ni, Cu and Zn were successively synthesized. V, Cr, Ni and Co doping can improve discharge capacity and rate capability, but forThe cycle performance is disadvantageous. Mg, Cu and Zn doping can improve the cycling performance but does not help with the discharge capacity. The root of the method lies in the high conductivity and SiO of the silicate material4The stability of the frame structure is not compatible. Therefore, the development of a silicate cathode material having high ionic conductivity and good cycle performance has been the direction in which researchers pursue and strive.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a rare earth element doped silicate positive electrode material, a preparation method and application thereof.
In order to achieve the purpose, the rare earth element doped silicate cathode material comprises an active component Li2M1-3/2xRxSiO4And wrapping in active component Li2M1-3/2xRxSiO4An outer conductive agent coating layer;
wherein M is one or the combination of Fe and Mn, R is one or the combination of La, Ce, Nd, Sm and Yb, and x is more than 0 and less than or equal to 2/3.
Active component Li2M1-3/2xRxSiO4The size of (A) is 10nm-1 μm.
The thickness of the conductive agent coating layer is 5-20 nm.
The conductive agent coating layer is made of carbon.
The preparation method of the rare earth element doped silicate cathode material comprises the following steps:
1) selecting carbon source materials according to active components Li2M1-3/2xRxSiO4Preparing a suspension;
2) drying the suspension to form dry glue, wherein the mass ratio of the dry glue to the carbon source material is (1-5) to 1;
3) mixing the dry glue and a carbon source material, adding a grinding aid, and performing ball milling uniformly to obtain a mixture;
4) drying the mixture obtained in the step 3) to completely volatilize the grinding aid to obtain dry powder;
5) and (3) placing the dried powder obtained in the step (4) in an inert gas atmosphere for calcining to obtain the rare earth element doped silicate cathode material.
The suspension consists of a solvent, a transition metal source material, a rare earth doping element source material, an M source material, a lithium source material, a silicon source material and a sol-gel catalyst source material, wherein the M source material is one or the combination of an iron source material and a manganese source material.
The solvent is one or a mixture of more of deionized water, ethanol and glycol;
the lithium source material is one or a mixture of more of lithium acetate, lithium oxalate, lithium nitrate, lithium sulfate, lithium chloride and lithium hydroxide;
the silicon source material is one or a mixture of more of silicon dioxide, tetraethyl orthosilicate, tetramethyl orthosilicate, lithium metasilicate and organic silicon;
the iron source material is one or a mixture of more of ferrous acetate, ferrous sulfate, ferric chloride, ferric nitrate, ferrous oxalate, ferric citrate, ferric oxide and ferroferric oxide;
the manganese source material is one or a mixture of more of manganese acetate, manganese sulfate, manganese chloride, manganese nitrate, manganese oxide, manganous oxide and manganous manganic oxide;
the R source material is one or a mixture of more of nitrate of R, sulfate of R, hydrochloride of R and oxide of R;
the carbon source material is one or a mixture of more of glucose, sucrose, citric acid, chitosan, cellulose, phytic acid and sorbitol.
The lithium source material is lithium acetate;
the silicon source material is tetraethyl orthosilicate;
the iron source material is ferric oxide;
the manganese source material is mangano-manganic oxide;
the R source material is an oxide of R;
the carbon source material is sucrose;
the solvent is formed by mixing deionized water and ethanol, wherein the volume ratio of the deionized water to the ethanol is 1/10.
The rare earth element doped silicate cathode material is applied to the anode of a lithium ion battery.
The invention has the following beneficial effects:
the rare earth element doped silicate cathode material, the preparation method and the application thereof are characterized in that the rare earth element is added into the active component aiming at Li during the specific operation2MSiO4The problems of low bulk conductivity and lattice distortion in the process of lithium removal/lithium insertion (M ═ Fe, Mn) are solved, and the Li is increased by utilizing the larger ionic radius of rare earth elements2MSiO4(M ═ Fe, Mn) lattice volume, widening Li + diffusion paths; the 3d electrons of the rare earth elements and the transition metal iron or manganese 2p electrons form p-d hybrid pi bonds, the M-O bond binding energy is enhanced, and the lattice stability of Li2MSiO4(M ═ Fe, Mn) is improved, so that the ionic conductivity and the cycling stability are improved.
Drawings
FIG. 1 shows Li obtained in example one2FeSiO4XRD pattern of/C.
FIG. 2 shows Li obtained in example one2FeSiO4SEM photograph of/C.
FIG. 3 shows Li obtained in the first example2FeSiO4TEM photograph of/C.
FIG. 4 shows Li obtained in the first example2FeSiO4and/C is a charge-discharge test result chart of the lithium ion battery with the positive electrode active material.
FIG. 5 shows Li obtained in example II2MnSiO4XRD pattern of/C;
FIG. 6 shows Li obtained in example II2MnSiO4SEM photograph of/C;
FIG. 7 shows Li obtained in example two2MnSiO4TEM photograph of/C;
FIG. 8 shows Li obtained in example II2MnSiO4the/C is a charge-discharge test result chart of the lithium ion battery with the positive electrode active material;
FIG. 9 shows a third embodimentObtained Li2Fe0.985La0.03SiO4XRD pattern of/C;
FIG. 10 shows Li obtained in example III2Fe0.985La0.03SiO4SEM photograph of/C;
FIG. 11 shows Li obtained in example III2Fe0.985La0.03SiO4TEM photograph of/C;
FIG. 12 shows Li obtained in example III2Fe0.985La0.03SiO4the/C is a charge-discharge test result chart of the lithium ion battery with the positive electrode active material;
FIG. 13 shows Li obtained in example four2Fe0.975Sm0.05SiO4XRD pattern of/C;
FIG. 14 shows Li obtained in example four2Fe0.975Sm0.05SiO4SEM photograph of/C;
FIG. 15 shows Li obtained in example IV2Fe0.975Sm0.05SiO4TEM photograph of/C;
FIG. 16 shows Li obtained in example IV2Fe0.975Sm0.05SiO4and/C is a charge-discharge test result chart of the lithium ion battery with the positive electrode active material.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings:
the rare earth element doped silicate cathode material comprises an active component Li2M1-3/2xRxSiO4And wrapping in active component Li2M1-3/2xRxSiO4An outer conductive agent coating layer; wherein M is one or the combination of Fe and Mn, R is one or the combination of La, Ce, Nd, Sm and Yb, and x is more than 0 and less than or equal to 2/3.
Active component Li2M1-3/2xRxSiO4The size of (A) is 10nm-1 μm.
The thickness of the conductive agent coating layer is 5-20 nm.
The conductive agent coating layer is made of carbon.
The lithium ion battery prepared by taking the rare earth element doped silicate as the anode active material is 16mA g-1Under the current density, the reversible discharge specific capacity is higher than 160mAh g-1(ii) a At 160mA g-1At current density higher than 120mAhg-1(ii) a The lithium ion battery prepared by taking the rare earth element doped silicate as the anode active material is 16mA g-1Under the current density, the capacity retention rate of 100 times of circulation is not lower than 80 percent; at 160mA g-1Under the current density, the circulation capacity retention rate of 100 is not less than 90%, so that the lithium ion battery anode can be used.
The preparation method of the rare earth element doped silicate cathode material comprises the following steps:
1) selecting carbon source materials according to active components Li2M1-3/2xRxSiO4Preparing a suspension;
the suspension consists of a solvent, a transition metal source material, a rare earth doping element source material, an M source material, a lithium source material, a silicon source material and a sol-gel catalyst source material, wherein the M source material is one or the combination of an iron source material and a manganese source material, and the active component Li is used as the active component in the step 1)2M1-3/2xRxSiO4The specific process for preparing the suspension is as follows:
11) under the condition of stirring, mixing a transition metal source material, a rare earth doping element source material, an M source material, a lithium source material and a silicon source material to completely dissolve the lithium source material and the silicon source material;
12) under the condition of ultrasonic-assisted water bath heating and the stirring speed of v 1rpm, a sol-gel catalyst source material is added dropwise, the mixture is reacted at a first temperature of T1 for T1 time until flocculent precipitate is formed, and then the mixture is reacted at a stirring speed of v2rpm and the reaction temperature of T2 for T2 time to obtain a suspension.
2) Drying the suspension to form dry glue, wherein the mass ratio of the dry glue to the carbon source material is (1-5) to 1, preferably (2-3.5) to 1; more preferably 3: 1; specifically, the suspension is placed in a flat-bottom culture dish, horizontally placed in a blast oven, and dried at a third temperature T3 for a time T3 until a dry gel is formed;
3) mixing the dry glue and a carbon source material, adding a grinding aid, and performing ball milling uniformly, wherein the rotating speed of a ball mill in the ball milling process is v3 rpm, so as to obtain a mixture;
4) drying the mixture obtained in the step 3) to enable the grinding aid to be completely volatilized to obtain dry powder, specifically, placing the mixture obtained in the step 3) in a blast oven, and drying at a fourth temperature T4 for a time T4 to enable the grinding aid to be completely volatilized;
5) and (3) placing the dried powder obtained in the step (4) in an inert gas atmosphere for calcining to obtain the rare earth element doped silicate cathode material, specifically, placing the dried powder in a quartz boat, horizontally placing the quartz boat in a tubular furnace, introducing inert gas into the tubular furnace, and calcining at a fifth temperature T5 for T5 time to obtain the rare earth element doped silicate cathode material.
The solvent is one or a mixture of more of deionized water, ethanol and glycol;
the lithium source material is one or a mixture of more of lithium acetate, lithium oxalate, lithium nitrate, lithium sulfate, lithium chloride and lithium hydroxide;
the silicon source material is one or a mixture of more of silicon dioxide, tetraethyl orthosilicate, tetramethyl orthosilicate, lithium metasilicate and organic silicon;
the iron source material is one or a mixture of more of ferrous acetate, ferrous sulfate, ferric chloride, ferric nitrate, ferrous oxalate, ferric citrate, ferric oxide and ferroferric oxide;
the manganese source material is one or a mixture of more of manganese acetate, manganese sulfate, manganese chloride, manganese nitrate, manganese oxide, manganous oxide and manganous manganic oxide;
the R source material is one or a mixture of more of nitrate of R, sulfate of R, hydrochloride of R and oxide of R;
the carbon source material is one or a mixture of more of glucose, sucrose, citric acid, chitosan, cellulose, phytic acid and sorbitol.
Preferably, the lithium source material is lithium acetate; the silicon source material is tetraethyl orthosilicate; the iron source material is ferric oxide; the manganese source material is mangano-manganic oxide; the R source material is an oxide of R; the carbon source material is sucrose; the solvent is formed by mixing deionized water and ethanol, wherein the volume ratio of the deionized water to the ethanol is 1/10.
T1 is 40-80 ℃, preferably 60 ℃; t1 is 1-150min, preferably 120 min; v1 is 1-1200rpm, preferably 300-600rpm, more preferably 500 rpm;
v2 is 1-1200rpm, preferably 100-600rpm, more preferably 350 rpm; t2 is 80-100 ℃, preferably 80 ℃; t2 is 1-72h, preferably 12-24h, more preferably 20 h;
t3 is 40-100 deg.C, preferably 60-80 deg.C, more preferably 80 deg.C; t3 is 4-24h, preferably 6-12h, more preferably 8 h;
v3 is 100-600rpm, preferably 200-400rpm, more preferably 300 rpm; t4 is 40-100 deg.C, preferably 60-80 deg.C, more preferably 60 deg.C; t4 is 1-12h, preferably 4-10h, more preferably 6 h;
t5 is 500-800 ℃, preferably 600-700 ℃, more preferably 700 ℃; t5 is 6-24h, preferably 10-12h, more preferably 10 h.
Example one
This example was used to prepare lithium iron silicate cathode material (Li)2FeSiO4The preparation process comprises the following steps:
1) weighing and mixing 2.040g of lithium acetate dihydrate, 0.798g of ferric oxide and 1.042g of tetraethyl orthosilicate according to a molar ratio of 2:1:1, adding 100mL of ethanol and 10mL of deionized water, fully stirring to prepare a suspension, then placing the suspension in a water bath ultrasonic device at 80 ℃, and carrying out ultrasonic treatment for 1h to obtain a mixture with flocculent precipitates;
2) transferring the mixture with the flocculent precipitate to a reflux condensing device with mechanical stirring, and continuously reacting for 24 hours at 80 ℃;
3) removing the reflux condensing device, and completely volatilizing the solvent at the temperature of 100 ℃ under the action of mechanical stirring;
4) mixing 1.5g of the product obtained in the step 3) with 0.5g of cane sugar, adding a proper amount of acetone, and carrying out ball milling for 2 hours at the rotating speed of 300 rpm;
5) drying the product obtained in the step 4) in a blast oven, then transferring the product to a horizontally placed tube furnace, and carrying out treatment at 2 ℃ for min in an argon atmosphere-1The temperature is increased to 600 ℃, the mixture is calcined for 10 hours, and then the mixture is naturally cooled to the room temperature, so that the lithium iron silicate anode material is obtained.
And carrying out XRD, SEM, TEM and constant current charge and discharge tests on the lithium iron silicate cathode material.
FIG. 1 shows Li obtained in example one2FeSiO4XRD pattern of/C, it can be seen that Li2FeSiO4Has a monoclinic crystal structure, P21The diffraction peaks of lithium oxide, iron oxide, lithium silicate and other impurities are not found in the/n space point group, which indicates that the product phase purity is high, and the diffraction peaks of carbon are not found, which indicates that the product is in an amorphous state.
FIG. 2 shows Li obtained in example one2FeSiO4SEM photograph of/C shows that the product particles are uniform and have a size of about 50 nm.
FIG. 3 shows Li obtained in the first example2FeSiO4TEM photograph of/C with a carbon coating thickness of about 5 nm.
FIG. 4 shows Li obtained in the first example2FeSiO4Charge and discharge curve at 16mA g/C-1The first discharge capacity is 146mAh g under the current density-1After several times of cyclic activation, the capacity can reach 160mAh g-1The first discharge curve plateau is slightly higher than the discharge plateau of the later cycle due to Li during the first charge-discharge process2FeSiO4The crystal structure is reformed.
Example two
This example was used to prepare a lithium manganese silicate cathode material (Li)2MnSiO4The preparation process comprises the following steps:
1) weighing 2.040g of lithium acetate dihydrate, 0.763g of manganous oxide and 1.042g of tetraethyl orthosilicate according to the molar ratio of 2:1:1 of Li, Mn and Si, adding 100mL of ethanol and 10mL of deionized water, fully stirring to prepare a suspension, then placing the suspension in a water bath ultrasonic device at 80 ℃, and carrying out ultrasonic treatment for 1h to obtain a mixture with flocculent precipitates;
2) transferring the mixture with the flocculent precipitate to a reflux condensing device with mechanical stirring, and continuously reacting for 24 hours at the temperature of 80 ℃;
3) removing the reflux condensing device, and volatilizing the solvent at the temperature of 100 ℃ under the action of mechanical stirring;
4) mixing 1.5g of the product obtained in the step 3) with 0.5g of cane sugar, adding a proper amount of acetone, and then carrying out ball milling for 2 hours at the rotating speed of 300 rpm;
5) placing the product obtained in the step 4) in a blast oven for drying, then transferring the product to a horizontally placed tube furnace, and carrying out argon atmosphere at the temperature of 2 ℃ for min-1The temperature is raised to 600 ℃, the mixture is calcined for 10 hours, and then the mixture is naturally cooled to the room temperature, so that the lithium manganese silicate anode material is obtained.
XRD, SEM, TEM and constant current charge and discharge tests are carried out on the lithium iron silicate cathode material prepared in the embodiment.
FIG. 5 shows Li obtained in example II2MnSiO4XRD pattern of/C, as shown in FIG. 5, Li2MnSiO4Has a crystal structure of orthorhombic system Pmn21The spatial point group shows no diffraction peaks of lithium oxide, manganese oxide, lithium silicate, manganese silicate and other impurities, which indicates that the product has high phase purity, and shows no diffraction peak of carbon, which indicates that the product is amorphous.
FIG. 6 shows Li obtained in example II2MnSiO4SEM photograph of/C shows that the product particles are uniform and have a size of about 30nm, as shown in FIG. 6.
FIG. 7 shows Li obtained in example two2MnSiO4TEM photograph of/C with a carbon coating thickness of about 5 nm.
FIG. 8 shows Li obtained in example II2MnSiO4The charge/discharge curve of/C is shown in FIG. 8 at 8mA g-1The first discharge capacity is 240mAh g under the current density-1At 16mA g-1Discharge capacity at current density of 200mAh g-1。
EXAMPLE III
The embodiment is used for preparing the lanthanum-doped lithium iron silicate cathode material (Li)2Fe0.985La0.03SiO4The preparation process comprises the following steps:
1) weighing and mixing 2.040g of lithium acetate dihydrate, 0.786g of ferric oxide, 0.013g of lanthanum nitrate hexahydrate and 1.042g of tetraethyl orthosilicate according to a molar ratio of 2:0.985:0.03:1, adding 100mL of ethanol and 10mL of deionized water, fully stirring to prepare a suspension, then placing the suspension in a water bath ultrasonic device at 80 ℃, and carrying out ultrasonic treatment for 1h to obtain a mixture with flocculent precipitates;
2) transferring the mixture with the flocculent precipitate to a reflux condensing device with mechanical stirring, and continuously reacting for 24 hours at the temperature of 80 ℃;
3) removing the reflux condensing device, and volatilizing the solvent at the temperature of 100 ℃ under the action of mechanical stirring;
4) mixing 1.5g of the product obtained from the step 3) with 0.5g of sucrose, adding a proper amount of acetone, and then carrying out ball milling for 2h at the rotating speed of 300 rpm;
5) placing the product obtained in the step 4) in a blast oven for drying, then transferring the product to a horizontally placed tube furnace, and then carrying out secondary drying at 2 ℃ for min in an argon atmosphere-1The temperature is raised to 600 ℃, the mixture is calcined for 10 hours, and then the mixture is naturally cooled to the room temperature, so as to obtain the lanthanum-doped lithium iron silicate anode material.
ICP detection is carried out on the lanthanum-doped lithium iron silicate positive electrode material, and the molar ratio of Li to Fe to La is 2.001:0.984:0.030, which is consistent with the designed element metering ratio.
And carrying out XRD, SEM, TEM and constant current charge and discharge tests on the lanthanum-doped lithium iron silicate anode material.
FIG. 9 shows Li obtained in example III2Fe0.985La0.03SiO4XRD pattern of/C, Li, as can be seen from FIG. 92Fe0.985La0.03SiO4Has a monoclinic crystal structure, P21The diffraction peaks of lithium oxide, iron oxide, lithium silicate, lanthanum oxide and other impurities are not found in the/n space point group, which shows that the phase purity of the product is higher, and the diffraction peaks of carbon are not foundAnd is illustrated as amorphous.
FIG. 10 shows Li obtained in example III2Fe0.985La0.03SiO4SEM photograph of/C shows that the product particles are uniform and have a size of about 50nm, as shown in FIG. 10.
FIG. 11 shows Li obtained in example III2Fe0.985La0.03SiO4TEM photograph of/C with a carbon coating thickness of about 5 nm.
FIG. 12 shows Li obtained in example III2Fe0.985La0.03SiO4The charge/discharge curve at 16mA g/C as shown in FIG. 12-1The first discharge capacity is 160mAh g under the current density-1After several times of cyclic activation, the capacity can reach 166mAh g-1Break through the reversible deintercalation and disintercalation of 1mol Li in each structural unit+. The first discharge curve plateau is slightly higher than the discharge plateau of the later cycle due to Li during the first charge-discharge process2FeSiO4The crystal structure is reformed.
Example four
The embodiment is used for preparing samarium-doped lithium iron silicate cathode material (Li)2Fe0.975Sm0.05SiO4The preparation process comprises the following steps:
1) weighing and mixing 2.040g of lithium acetate dihydrate, 0.786g of ferric oxide, 0.017g of samarium nitrate and 1.042g of tetraethyl orthosilicate according to the molar ratio of 2:0.975:0.05:1, adding 100mL of ethanol and 10mL of deionized water, fully stirring to prepare a suspension, then placing the suspension in a water bath ultrasonic device at 80 ℃, and carrying out ultrasonic treatment for 1h to obtain a mixture with flocculent precipitates;
2) transferring the mixture with the flocculent precipitate to a reflux condensing device with mechanical stirring, and continuously reacting for 24h at 80 ℃;
3) removing the reflux condensing device, and volatilizing the solvent at the temperature of 100 ℃ under the action of mechanical stirring;
4) mixing 1.5g of the product obtained in the step 3) with 0.5g of cane sugar, adding a proper amount of acetone, and carrying out ball milling for 2 hours at the rotating speed of 300 rpm;
5) subjecting the product obtained in step 4) toDrying in a forced air oven, transferring to a horizontally arranged tube furnace, and heating at 2 deg.C for 2 min under argon atmosphere-1The temperature is raised to 600 ℃, the mixture is calcined for 10 hours, and then the mixture is naturally cooled to the room temperature, so that the samarium-doped lithium iron silicate anode material is obtained.
ICP detection is carried out on the samarium-doped lithium iron silicate anode material, and the molar ratio of Li to Fe to Sm is 1.999:0.976:0.051 which is consistent with the designed element metering ratio.
And carrying out XRD (X-ray diffraction), SEM (scanning Electron microscope), TEM (transverse electric microscope) and constant-current charge and discharge tests on the samarium-doped lithium iron silicate positive electrode material.
FIG. 13 shows Li obtained in example four2Fe0.985La0.03SiO4XRD pattern of/C, Li, as can be seen from FIG. 132Fe0.985La0.03SiO4Has a monoclinic crystal structure, P21The/n space point group does not find diffraction peaks of lithium oxide, iron oxide, lithium silicate, samarium oxide and other impurities, which indicates that the phase purity of the product is higher, and does not find diffraction peaks of carbon, which indicates that the product is in an amorphous state.
FIG. 14 shows Li obtained in example four2Fe0.985La0.03SiO4SEM photograph of/C shows that the product particles are uniform and have a size of about 50 nm.
FIG. 15 shows Li obtained in example IV2Fe0.985La0.03SiO4TEM photograph of/C with a carbon coating thickness of about 5 nm.
FIG. 16 shows Li obtained in example IV2Fe0.985La0.03SiO4Charge and discharge curves for/C, refer to FIG. 16, at 16mAg-1The first discharge capacity is 190mAh g under the current density-1Corresponding to the reversible deintercalation of 1.5mol of Li per structural unit+。
EXAMPLE five
The rare earth element doped silicate cathode material comprises an active component Li2M1-3/2xRxSiO4And wrapping in active component Li2M1-3/2xRxSiO4An outer conductive agent coating layer; wherein M is the combination of Fe and Mn, R is La, and x is 1/3。
Active component Li2M1-3/2xRxSiO4Has a size of 10 nm.
The thickness of the conductive agent coating layer is 5 nm.
The conductive agent coating layer is made of carbon.
The preparation method of the rare earth element doped silicate cathode material comprises the following steps:
1) selecting carbon source materials according to active components Li2M1-3/2xRxSiO4Preparing a suspension;
the suspension consists of a solvent, a transition metal source material, a rare earth doping element source material, an iron source material, a manganese source material, a lithium source material, a silicon source material and a sol-gel catalyst source material, and the active component Li is used as the active component in the step 1)2M1-3/2xRxSiO4The specific process for preparing the suspension is as follows:
11) under the condition of stirring, mixing a transition metal source material, a rare earth doping element source material, a lithium source material and a silicon source material to completely dissolve the lithium source material and the silicon source material;
12) under the condition of ultrasonic-assisted water bath heating and the stirring speed of v 1rpm, a sol-gel catalyst source material is added dropwise, the mixture is reacted at a first temperature of T1 for T1 time until flocculent precipitate is formed, and then the mixture is reacted at a stirring speed of v2rpm and the reaction temperature of T2 for T2 time to obtain a suspension.
2) Drying the suspension to form dry glue, wherein the mass ratio of the dry glue to the carbon source material is 3: 1; specifically, the suspension is placed in a flat-bottom culture dish, horizontally placed in a blast oven, and dried at a third temperature T3 for a time T3 until a dry gel is formed;
3) mixing the dry glue and a carbon source material, adding a grinding aid, and performing ball milling uniformly, wherein the rotating speed of a ball mill in the ball milling process is v3 rpm, so as to obtain a mixture;
4) drying the mixture obtained in the step 3) to enable the grinding aid to be completely volatilized to obtain dry powder, specifically, placing the mixture obtained in the step 3) in a blast oven, and drying at a fourth temperature T4 for a time T4 to enable the grinding aid to be completely volatilized;
5) and (3) placing the dried powder obtained in the step (4) in an inert gas atmosphere for calcining to obtain the rare earth element doped silicate cathode material, specifically, placing the dried powder in a quartz boat, horizontally placing the quartz boat in a tubular furnace, introducing inert gas into the tubular furnace, and calcining at a fifth temperature T5 for T5 time to obtain the rare earth element doped silicate cathode material.
The solvent is deionized water;
the lithium source material is lithium acetate;
the silicon source material is silicon dioxide;
the iron source material is ferrous acetate;
the manganese source material is manganese acetate;
the R source material is nitrate of R;
the carbon source material is glucose.
T1 is 60 ℃; t1 is 120 min; v1 at 500 rpm;
v2 at 350 rpm; t2 is 80 ℃; t2 is 20 h;
t3 is 80 ℃; t3 is 8 h;
v3 at 300 rpm; t4 is 60 ℃; t4 is 6 h;
t5 is 700 ℃; t5 is 10 h.
EXAMPLE six
The rare earth element doped silicate cathode material comprises an active component Li2M1-3/2xRxSiO4And wrapping in active component Li2M1-3/2xRxSiO4An outer conductive agent coating layer; wherein M is Mn, R is Ce, and x is 2/3.
Active component Li2M1-3/2xRxSiO4Has a size of 1 μm.
The thickness of the conductive agent coating layer was 20 nm.
The conductive agent coating layer is made of carbon.
The preparation method of the rare earth element doped silicate cathode material comprises the following steps:
1) selecting carbon source materials according to active components Li2M1-3/2xRxSiO4Preparing a suspension;
the suspension liquid is composed of solvent, transition metal source material, rare earth doping element source material, manganese source material, lithium source material, silicon source material and sol-gel catalyst source material, and the active component Li is used as the active component in the step 1)2M1-3/2xRxSiO4The specific process for preparing the suspension is as follows:
11) under the condition of stirring, mixing a transition metal source material, a rare earth doping element source material, a lithium source material and a silicon source material to completely dissolve the lithium source material and the silicon source material;
12) under the condition of ultrasonic-assisted water bath heating and the stirring speed of v 1rpm, a sol-gel catalyst source material is added dropwise, the mixture is reacted at a first temperature of T1 for T1 time until flocculent precipitate is formed, and then the mixture is reacted at a stirring speed of v2rpm and the reaction temperature of T2 for T2 time to obtain a suspension.
2) Drying the suspension to form dry glue, wherein the mass ratio of the dry glue to the carbon source material is 2: 1; specifically, the suspension is placed in a flat-bottom culture dish, horizontally placed in a blast oven, and dried at a third temperature T3 for a time T3 until a dry gel is formed;
3) mixing the dry glue and a carbon source material, adding a grinding aid, and performing ball milling uniformly, wherein the rotating speed of a ball mill in the ball milling process is v3 rpm, so as to obtain a mixture;
4) drying the mixture obtained in the step 3) to enable the grinding aid to be completely volatilized to obtain dry powder, specifically, placing the mixture obtained in the step 3) in a blast oven, and drying at a fourth temperature T4 for a time T4 to enable the grinding aid to be completely volatilized;
5) and (3) placing the dried powder obtained in the step (4) in an inert gas atmosphere for calcining to obtain the rare earth element doped silicate cathode material, specifically, placing the dried powder in a quartz boat, horizontally placing the quartz boat in a tubular furnace, introducing inert gas into the tubular furnace, and calcining at a fifth temperature T5 for T5 time to obtain the rare earth element doped silicate cathode material.
The solvent is ethanol;
the lithium source material is lithium oxalate;
the silicon source material is tetraethyl orthosilicate;
the manganese source material is manganese sulfate;
the R source material is sulfate of R;
the carbon source material is sucrose.
T1 is 40 ℃; t1 is 1 min; v1 at 300 rpm;
v2 at 100 rpm; t2 is 80; t2 is 12;
t3 is 60; t3 is 6;
v3 is 200; t4 is 60; t4 is 4 h;
t5 is 600; t5 is 10 h.
EXAMPLE seven
The rare earth element doped silicate cathode material comprises an active component Li2M1-3/2xRxSiO4And wrapping in active component Li2M1-3/2xRxSiO4An outer conductive agent coating layer; wherein M is a combination of Fe, R is Nd, and x is 0.01.
Active component Li2M1-3/2xRxSiO4Has a size of 100 μm.
The thickness of the conductive agent coating layer is 12 nm.
The conductive agent coating layer is made of carbon.
The preparation method of the rare earth element doped silicate cathode material comprises the following steps:
1) selecting carbon source materials according to active components Li2M1-3/2xRxSiO4Preparing a suspension;
the suspension liquid is composed of solvent, transition metal source material, rare earth doping element source material, iron source material, lithium source material, silicon source material and sol-gel catalyst source material, and in the step 1), according to the active component Li2M1-3/2xRxSiO4The specific process for preparing the suspension is as follows:
11) under the condition of stirring, mixing a transition metal source material, a rare earth doping element source material, a lithium source material and a silicon source material to completely dissolve the lithium source material and the silicon source material;
12) under the condition of ultrasonic-assisted water bath heating and the stirring speed of v 1rpm, a sol-gel catalyst source material is added dropwise, the mixture is reacted at a first temperature of T1 for T1 time until flocculent precipitate is formed, and then the mixture is reacted at a stirring speed of v2rpm and the reaction temperature of T2 for T2 time to obtain a suspension.
2) Drying the suspension to form dry glue, wherein the mass ratio of the dry glue to the carbon source material is 3.5: 1; specifically, the suspension is placed in a flat-bottom culture dish, horizontally placed in a blast oven, and dried at a third temperature T3 for a time T3 until a dry gel is formed;
3) mixing the dry glue and a carbon source material, adding a grinding aid, and performing ball milling uniformly, wherein the rotating speed of a ball mill in the ball milling process is v3 rpm, so as to obtain a mixture;
4) drying the mixture obtained in the step 3) to enable the grinding aid to be completely volatilized to obtain dry powder, specifically, placing the mixture obtained in the step 3) in a blast oven, and drying at a fourth temperature T4 for a time T4 to enable the grinding aid to be completely volatilized;
5) and (3) placing the dried powder obtained in the step (4) in an inert gas atmosphere for calcining to obtain the rare earth element doped silicate cathode material, specifically, placing the dried powder in a quartz boat, horizontally placing the quartz boat in a tubular furnace, introducing inert gas into the tubular furnace, and calcining at a fifth temperature T5 for T5 time to obtain the rare earth element doped silicate cathode material.
The solvent is ethylene glycol;
the lithium source material is lithium nitrate;
the silicon source material is tetramethyl orthosilicate;
the iron source material is ferric chloride;
the R source material is a hydrochloride salt of R;
the carbon source material is citric acid.
T1 is 80 ℃; t1 is 150 min; v1 at 600 rpm;
v2 at 600 rpm; t2 is 100 ℃; t2 is 24 h;
t3 is 80 ℃; t3 is 12 h;
v3 at 400 rpm; t4 is 80 ℃; t4 is 10 h;
t5 is 700 ℃; t5 is 12 h.
Example eight
The rare earth element doped silicate cathode material comprises an active component Li2M1-3/2xRxSiO4And wrapping in active component Li2M1-3/2xRxSiO4An outer conductive agent coating layer; wherein M is the combination of Fe and Mn, R is Sm, and x is 0.5.
Active component Li2M1-3/2xRxSiO4Has a size of 50 μm.
The thickness of the conductive agent coating layer is 8 nm.
The conductive agent coating layer is made of carbon.
The preparation method of the rare earth element doped silicate cathode material comprises the following steps:
1) selecting carbon source materials according to active components Li2M1-3/2xRxSiO4Preparing a suspension;
the suspension consists of a solvent, a transition metal source material, a rare earth doping element source material, an iron source material, a manganese source material, a lithium source material, a silicon source material and a sol-gel catalyst source material, and the active component Li is used as the active component in the step 1)2M1-3/2xRxSiO4The specific process for preparing the suspension is as follows:
11) under the condition of stirring, mixing a transition metal source material, a rare earth doping element source material, a lithium source material and a silicon source material to completely dissolve the lithium source material and the silicon source material;
12) under the condition of ultrasonic-assisted water bath heating and the stirring speed of v 1rpm, a sol-gel catalyst source material is added dropwise, the mixture is reacted at a first temperature of T1 for T1 time until flocculent precipitate is formed, and then the mixture is reacted at a stirring speed of v2rpm and the reaction temperature of T2 for T2 time to obtain a suspension.
2) Drying the suspension to form dry glue, wherein the mass ratio of the dry glue to the carbon source material is 3: 1; specifically, the suspension is placed in a flat-bottom culture dish, horizontally placed in a blast oven, and dried at a third temperature T3 for a time T3 until a dry gel is formed;
3) mixing the dry glue and a carbon source material, adding a grinding aid, and performing ball milling uniformly, wherein the rotating speed of a ball mill in the ball milling process is v3 rpm, so as to obtain a mixture;
4) drying the mixture obtained in the step 3) to enable the grinding aid to be completely volatilized to obtain dry powder, specifically, placing the mixture obtained in the step 3) in a blast oven, and drying at a fourth temperature T4 for a time T4 to enable the grinding aid to be completely volatilized;
5) and (3) placing the dried powder obtained in the step (4) in an inert gas atmosphere for calcining to obtain the rare earth element doped silicate cathode material, specifically, placing the dried powder in a quartz boat, horizontally placing the quartz boat in a tubular furnace, introducing inert gas into the tubular furnace, and calcining at a fifth temperature T5 for T5 time to obtain the rare earth element doped silicate cathode material.
The lithium source material is lithium sulfate;
the silicon source material is lithium metasilicate;
the iron source material is ferric nitrate;
the manganese source material is manganese nitrate;
the R source material is an oxide of R;
the carbon source material is chitosan.
The solvent is formed by mixing deionized water and ethanol, wherein the volume ratio of the deionized water to the ethanol is 1/10.
T1 is 50 ℃; t1 is 100 min; v1 is 1 rpm;
v2 is 1 rpm; t2 is 90 ℃; t2 is 1 h;
t3 is 40 ℃; t3 is 4 h;
v3 at 100 rpm; t4 is 40 ℃; t4 is 1 h;
t5 is 500 ℃; t5 is 6 h.
Example nine
The rare earth element doped silicate cathode material comprises an active component Li2M1-3/2xRxSiO4And wrapping in active component Li2M1-3/2xRxSiO4An outer conductive agent coating layer; wherein M is the combination of Fe and Mn, R is Yb, and x is 0.2.
Active component Li2M1-3/2xRxSiO4Has a size of 100 μm.
The thickness of the conductive agent coating layer is 8 nm.
The conductive agent coating layer is made of carbon.
The preparation method of the rare earth element doped silicate cathode material comprises the following steps:
1) selecting carbon source materials according to active components Li2M1-3/2xRxSiO4Preparing a suspension;
the suspension consists of a solvent, a transition metal source material, a rare earth doping element source material, an iron source material, a manganese source material, a lithium source material, a silicon source material and a sol-gel catalyst source material, and the active component Li is used as the active component in the step 1)2M1-3/2xRxSiO4The specific process for preparing the suspension is as follows:
11) under the condition of stirring, mixing a transition metal source material, a rare earth doping element source material, a lithium source material and a silicon source material to completely dissolve the lithium source material and the silicon source material;
12) under the condition of ultrasonic-assisted water bath heating and the stirring speed of v 1rpm, a sol-gel catalyst source material is added dropwise, the mixture is reacted at a first temperature of T1 for T1 time until flocculent precipitate is formed, and then the mixture is reacted at a stirring speed of v2rpm and the reaction temperature of T2 for T2 time to obtain a suspension.
2) Drying the suspension to form dry glue, wherein the mass ratio of the dry glue to the carbon source material is 5: 1; specifically, the suspension is placed in a flat-bottom culture dish, horizontally placed in a blast oven, and dried at a third temperature T3 for a time T3 until a dry gel is formed;
3) mixing the dry glue and a carbon source material, adding a grinding aid, and performing ball milling uniformly, wherein the rotating speed of a ball mill in the ball milling process is v3 rpm, so as to obtain a mixture;
4) drying the mixture obtained in the step 3) to enable the grinding aid to be completely volatilized to obtain dry powder, specifically, placing the mixture obtained in the step 3) in a blast oven, and drying at a fourth temperature T4 for a time T4 to enable the grinding aid to be completely volatilized;
5) and (3) placing the dried powder obtained in the step (4) in an inert gas atmosphere for calcining to obtain the rare earth element doped silicate cathode material, specifically, placing the dried powder in a quartz boat, horizontally placing the quartz boat in a tubular furnace, introducing inert gas into the tubular furnace, and calcining at a fifth temperature T5 for T5 time to obtain the rare earth element doped silicate cathode material.
The solvent is a mixture of deionized water, ethanol and glycol;
the lithium source material is lithium chloride;
the silicon source material is organic silicon;
the iron source material is ferrous oxalate;
the manganese source material is manganese oxide;
the R source material is an oxide of R;
the carbon source material is cellulose.
T1 is 80 ℃; t1 is 150 min; v1 at 1200 rpm;
v2 at 1200 rpm; t2 is 8100 ℃; t2 is 72 h;
t3 is 100 ℃; t3 is 24 h;
v3 at 600 rpm; t4 is 100 ℃; t4 is 12 h;
t5 is 800 ℃; t5 is 24 h.
Example ten
The rare earth element doped silicate cathode material comprises an active component Li2M1-3/2xRxSiO4And is wrapped inActive component Li2M1-3/2xRxSiO4An outer conductive agent coating layer; wherein M is the combination of Fe and Mn, R is Yb, and x is 2/3.
Active component Li2M1-3/2xRxSiO4Has a size of 1 μm.
The thickness of the conductive agent coating layer is 5 nm.
The conductive agent coating layer is made of carbon.
The preparation method of the rare earth element doped silicate cathode material comprises the following steps:
1) selecting carbon source materials according to active components Li2M1-3/2xRxSiO4Preparing a suspension;
the suspension consists of a solvent, a transition metal source material, a rare earth doping element source material, an iron source material, a manganese source material, a lithium source material, a silicon source material and a sol-gel catalyst source material, and the active component Li is used as the active component in the step 1)2M1-3/2xRxSiO4The specific process for preparing the suspension is as follows:
11) under the condition of stirring, mixing a transition metal source material, a rare earth doping element source material, a lithium source material and a silicon source material to completely dissolve the lithium source material and the silicon source material;
12) under the condition of ultrasonic-assisted water bath heating and the stirring speed of v 1rpm, a sol-gel catalyst source material is added dropwise, the mixture is reacted at a first temperature of T1 for T1 time until flocculent precipitate is formed, and then the mixture is reacted at a stirring speed of v2rpm and the reaction temperature of T2 for T2 time to obtain a suspension.
2) Drying the suspension to form dry glue, wherein the mass ratio of the dry glue to the carbon source material is 3: 1; specifically, the suspension is placed in a flat-bottom culture dish, horizontally placed in a blast oven, and dried at a third temperature T3 for a time T3 until a dry gel is formed;
3) mixing the dry glue and a carbon source material, adding a grinding aid, and performing ball milling uniformly, wherein the rotating speed of a ball mill in the ball milling process is v3 rpm, so as to obtain a mixture;
4) drying the mixture obtained in the step 3) to enable the grinding aid to be completely volatilized to obtain dry powder, specifically, placing the mixture obtained in the step 3) in a blast oven, and drying at a fourth temperature T4 for a time T4 to enable the grinding aid to be completely volatilized;
5) and (3) placing the dried powder obtained in the step (4) in an inert gas atmosphere for calcining to obtain the rare earth element doped silicate cathode material, specifically, placing the dried powder in a quartz boat, horizontally placing the quartz boat in a tubular furnace, introducing inert gas into the tubular furnace, and calcining at a fifth temperature T5 for T5 time to obtain the rare earth element doped silicate cathode material.
The solvent is deionized water;
the lithium source material is lithium hydroxide;
the silicon source material is silicon dioxide;
the iron source material is ferrous sulfate;
the manganese source material is manganese chloride;
the R source material is an oxide of R;
the carbon source material is phytic acid.
T1 is 40 ℃; t1 is 1 min; v1 at 600 rpm;
v2 at 500 rpm; t2 is 85 ℃; t2 is 50 h;
t3 is 50 ℃; t3 is 10 h;
v3 at 500 rpm; t4 is 50 ℃; t4 is 5 h;
t5 is 650 ℃; t5 is 8 h.
EXAMPLE eleven
The rare earth element doped silicate cathode material comprises an active component Li2M1-3/2xRxSiO4And wrapping in active component Li2M1-3/2xRxSiO4An outer conductive agent coating layer; wherein M is the combination of Fe and Mn, R is Yb, and x is 1/3.
Active component Li2M1-3/2xRxSiO4Has a size of 500. mu.m.
The thickness of the conductive agent coating layer is 15 nm.
The conductive agent coating layer is made of carbon.
The preparation method of the rare earth element doped silicate cathode material comprises the following steps:
1) selecting carbon source materials according to active components Li2M1-3/2xRxSiO4Preparing a suspension;
the suspension consists of a solvent, a transition metal source material, a rare earth doping element source material, an iron source material, a manganese source material, a lithium source material, a silicon source material and a sol-gel catalyst source material, and the active component Li is used as the active component in the step 1)2M1-3/2xRxSiO4The specific process for preparing the suspension is as follows:
11) under the condition of stirring, mixing a transition metal source material, a rare earth doping element source material, a lithium source material and a silicon source material to completely dissolve the lithium source material and the silicon source material;
12) under the condition of ultrasonic-assisted water bath heating and the stirring speed of v 1rpm, a sol-gel catalyst source material is added dropwise, the mixture is reacted at a first temperature of T1 for T1 time until flocculent precipitate is formed, and then the mixture is reacted at a stirring speed of v2rpm and the reaction temperature of T2 for T2 time to obtain a suspension.
2) Drying the suspension to form dry glue, wherein the mass ratio of the dry glue to the carbon source material is 4: 1; specifically, the suspension is placed in a flat-bottom culture dish, horizontally placed in a blast oven, and dried at a third temperature T3 for a time T3 until a dry gel is formed;
3) mixing the dry glue and a carbon source material, adding a grinding aid, and performing ball milling uniformly, wherein the rotating speed of a ball mill in the ball milling process is v3 rpm, so as to obtain a mixture;
4) drying the mixture obtained in the step 3) to enable the grinding aid to be completely volatilized to obtain dry powder, specifically, placing the mixture obtained in the step 3) in a blast oven, and drying at a fourth temperature T4 for a time T4 to enable the grinding aid to be completely volatilized;
5) and (3) placing the dried powder obtained in the step (4) in an inert gas atmosphere for calcining to obtain the rare earth element doped silicate cathode material, specifically, placing the dried powder in a quartz boat, horizontally placing the quartz boat in a tubular furnace, introducing inert gas into the tubular furnace, and calcining at a fifth temperature T5 for T5 time to obtain the rare earth element doped silicate cathode material.
The solvent is deionized water;
the lithium source material is lithium hydroxide;
the silicon source material is organic silicon;
the iron source material is ferric oxide;
the manganese source material is mangano-manganic oxide;
the R source material is an oxide of R;
the carbon source material is sorbitol.
T1 is 80 ℃; t1 is 150 min; v1 is 1200 rpmm;
v2 at 1200 rpm; t2 is 100 ℃; t2 is 72 h;
t3 is 100 ℃; t3 is 24 h;
v3 at 300 rpm; t4 is 60 ℃; t4 is 6 h;
t5 is 700 ℃; t5 is 10 h.
Example twelve
The rare earth element doped silicate cathode material comprises an active component Li2M1-3/2xRxSiO4And wrapping in active component Li2M1-3/2xRxSiO4An outer conductive agent coating layer; wherein M is the combination of Fe and Mn, R is Yb, and x is 2/3.
Active component Li2M1-3/2xRxSiO4Has a size of 1 μm.
The thickness of the conductive agent coating layer was 20 nm.
The conductive agent coating layer is made of carbon.
The preparation method of the rare earth element doped silicate cathode material comprises the following steps:
1) selecting carbon source materials according to active components Li2M1-3/2xRxSiO4Transformation ofPreparing a suspension by a chemical formula;
the suspension consists of a solvent, a transition metal source material, a rare earth doping element source material, an iron source material, a manganese source material, a lithium source material, a silicon source material and a sol-gel catalyst source material, and the active component Li is used as the active component in the step 1)2M1-3/2xRxSiO4The specific process for preparing the suspension is as follows:
11) under the condition of stirring, mixing a transition metal source material, a rare earth doping element source material, a lithium source material and a silicon source material to completely dissolve the lithium source material and the silicon source material;
12) under the condition of ultrasonic-assisted water bath heating and the stirring speed of v 1rpm, a sol-gel catalyst source material is added dropwise, the mixture is reacted at a first temperature of T1 for T1 time until flocculent precipitate is formed, and then the mixture is reacted at a stirring speed of v2rpm and the reaction temperature of T2 for T2 time to obtain a suspension.
2) Drying the suspension to form dry glue, wherein the mass ratio of the dry glue to the carbon source material is 3: 1; specifically, the suspension is placed in a flat-bottom culture dish, horizontally placed in a blast oven, and dried at a third temperature T3 for a time T3 until a dry gel is formed;
3) mixing the dry glue and a carbon source material, adding a grinding aid, and performing ball milling uniformly, wherein the rotating speed of a ball mill in the ball milling process is v3 rpm, so as to obtain a mixture;
4) drying the mixture obtained in the step 3) to enable the grinding aid to be completely volatilized to obtain dry powder, specifically, placing the mixture obtained in the step 3) in a blast oven, and drying at a fourth temperature T4 for a time T4 to enable the grinding aid to be completely volatilized;
5) and (3) placing the dried powder obtained in the step (4) in an inert gas atmosphere for calcining to obtain the rare earth element doped silicate cathode material, specifically, placing the dried powder in a quartz boat, horizontally placing the quartz boat in a tubular furnace, introducing inert gas into the tubular furnace, and calcining at a fifth temperature T5 for T5 time to obtain the rare earth element doped silicate cathode material.
The solvent is a mixture of deionized water, ethanol and glycol;
the lithium source material is lithium hydroxide;
the silicon source material is organic silicon;
the iron source material is ferroferric oxide;
the manganese source material is mangano-manganic oxide;
the R source material is an oxide of R;
the carbon source material is sorbitol.
T1 is 60 ℃; t1 is 120 min; v1 at 500 rpm;
v2 at 350 rpm; t2 is 80 ℃; t2 is 20 h;
t3 is 80 ℃; t3 is 8 h;
v3 at 400rpm, T4 at 80 ℃; t4 is 10 h;
t5 is 700 ℃; t5 is 12 h.
EXAMPLE thirteen
The rare earth element doped silicate cathode material comprises an active component Li2M1-3/2xRxSiO4And wrapping in active component Li2M1-3/2xRxSiO4An outer conductive agent coating layer; wherein M is the combination of Fe and Mn, R is La, and x is 2/3.
Active component Li2M1-3/2xRxSiO4Has a size of 10 nm.
The thickness of the conductive agent coating layer is 50 nm.
The conductive agent coating layer is made of carbon.
The preparation method of the rare earth element doped silicate cathode material comprises the following steps:
1) selecting carbon source materials according to active components Li2M1-3/2xRxSiO4Preparing a suspension;
the suspension liquid is composed of solvent, transition metal source material, rare earth doping element source material, iron source material, lithium source material, silicon source material and sol-gel catalyst source material, and in the step 1), according to the active component Li2M1-3/2xRxSiO4The specific process for preparing the suspension is as follows:
11) under the condition of stirring, mixing a transition metal source material, a rare earth doping element source material, a lithium source material and a silicon source material to completely dissolve the lithium source material and the silicon source material;
12) under the condition of ultrasonic-assisted water bath heating and the stirring speed of v 1rpm, a sol-gel catalyst source material is added dropwise, the mixture is reacted at a first temperature of T1 for T1 time until flocculent precipitate is formed, and then the mixture is reacted at a stirring speed of v2rpm and the reaction temperature of T2 for T2 time to obtain a suspension.
2) Drying the suspension to form dry glue, wherein the mass ratio of the dry glue to the carbon source material is 3: 1; specifically, the suspension is placed in a flat-bottom culture dish, horizontally placed in a blast oven, and dried at a third temperature T3 for a time T3 until a dry gel is formed;
3) mixing the dry glue and a carbon source material, adding a grinding aid, and performing ball milling uniformly, wherein the rotating speed of a ball mill in the ball milling process is v3 rpm, so as to obtain a mixture;
4) drying the mixture obtained in the step 3) to enable the grinding aid to be completely volatilized to obtain dry powder, specifically, placing the mixture obtained in the step 3) in a blast oven, and drying at a fourth temperature T4 for a time T4 to enable the grinding aid to be completely volatilized;
5) and (3) placing the dried powder obtained in the step (4) in an inert gas atmosphere for calcining to obtain the rare earth element doped silicate cathode material, specifically, placing the dried powder in a quartz boat, horizontally placing the quartz boat in a tubular furnace, introducing inert gas into the tubular furnace, and calcining at a fifth temperature T5 for T5 time to obtain the rare earth element doped silicate cathode material.
The lithium source material is lithium acetate; the silicon source material is tetraethyl orthosilicate; the iron source material is ferric oxide; the manganese source material is mangano-manganic oxide; the R source material is an oxide of R; the carbon source material is sucrose; the solvent is formed by mixing deionized water and ethanol, wherein the volume ratio of the deionized water to the ethanol is 1/10.
T1 is 60 ℃; t1 is 120 min; v1 at 500 rpm;
v2 at 350 rpm; t2 is 80 ℃; t2 is 20 h;
t3 is 80 ℃; t3 is 8 h;
v3 at 300 rpm; t4 is 60 ℃; t4 is 6 h;
t5 is 700 ℃; t5 is 10 h.
The solvent can also be a mixture of several of deionized water, ethanol and glycol; the lithium source material can also be a mixture of several of lithium acetate, lithium oxalate, lithium nitrate, lithium sulfate, lithium chloride and lithium hydroxide; the silicon source material can also be a mixture of several of silicon dioxide, tetraethyl orthosilicate, tetramethyl orthosilicate, lithium metasilicate and organic silicon; the iron source material can also be a mixture of several of ferrous acetate, ferrous sulfate, ferric chloride, ferric nitrate, ferrous oxalate, ferric citrate, ferric oxide and ferroferric oxide; the manganese source material can also be a mixture of manganese acetate, manganese sulfate, manganese chloride, manganese nitrate, manganese oxide, manganous oxide and manganous manganic oxide; the R source material can also be a mixture of several of nitrate of R, sulfate of R, hydrochloride of R and oxide of R; the carbon source material can also be a mixture of several of glucose, sucrose, citric acid, chitosan, cellulose, phytic acid and sorbitol.

Claims (9)

1. The rare earth element doped silicate cathode material is characterized by comprising an active component Li2M1-3/2xRxSiO4And wrapping in active component Li2M1-3/2xRxSiO4An outer conductive agent coating layer;
wherein M is one or the combination of Fe and Mn, R is one or the combination of La, Ce, Nd, Sm and Yb, and x is more than 0 and less than or equal to 2/3.
2. The rare earth element-doped silicate positive electrode material according to claim 1, wherein the active component Li2M1-3/2xRxSiO4The size of (A) is 10nm-1 μm.
3. The rare-earth-doped silicate positive electrode material according to claim 1, wherein the thickness of the conductive agent coating layer is 5 to 20 nm.
4. The rare-earth-doped silicate positive electrode material according to claim 1, wherein the conductive coating layer is made of carbon.
5. A method for preparing the rare earth element-doped silicate positive electrode material according to claim 1, comprising the steps of:
1) selecting carbon source materials according to active components Li2M1-3/2xRxSiO4Preparing a suspension;
2) drying the suspension to form dry glue, wherein the mass ratio of the dry glue to the carbon source material is (1-5) to 1;
3) mixing the dry glue and a carbon source material, adding a grinding aid, and performing ball milling uniformly to obtain a mixture;
4) drying the mixture obtained in the step 3) to completely volatilize the grinding aid to obtain dry powder;
5) and (3) placing the dried powder obtained in the step (4) in an inert gas atmosphere for calcining to obtain the rare earth element doped silicate cathode material.
6. The method according to claim 5, wherein the suspension comprises a solvent, a transition metal source material, a rare earth doping element source material, an M source material, a lithium source material, a silicon source material, and a sol-gel catalyst source material, wherein the M source material is one or a combination of an iron source material and a manganese source material.
7. The method for preparing the rare earth element doped silicate cathode material according to claim 6, wherein the solvent is one or a mixture of deionized water, ethanol and ethylene glycol;
the lithium source material is one or a mixture of more of lithium acetate, lithium oxalate, lithium nitrate, lithium sulfate, lithium chloride and lithium hydroxide;
the silicon source material is one or a mixture of more of silicon dioxide, tetraethyl orthosilicate, tetramethyl orthosilicate, lithium metasilicate and organic silicon;
the iron source material is one or a mixture of more of ferrous acetate, ferrous sulfate, ferric chloride, ferric nitrate, ferrous oxalate, ferric citrate, ferric oxide and ferroferric oxide;
the manganese source material is one or a mixture of more of manganese acetate, manganese sulfate, manganese chloride, manganese nitrate, manganese oxide, manganous oxide and manganous manganic oxide;
the R source material is one or a mixture of more of nitrate of R, sulfate of R, hydrochloride of R and oxide of R;
the carbon source material is one or a mixture of more of glucose, sucrose, citric acid, chitosan, cellulose, phytic acid and sorbitol.
8. The method according to claim 7, wherein the rare earth element-doped silicate positive electrode material is prepared by mixing the rare earth element-doped silicate positive electrode material with the rare earth element-doped silicate positive electrode material,
the lithium source material is lithium acetate;
the silicon source material is tetraethyl orthosilicate;
the iron source material is ferric oxide;
the manganese source material is mangano-manganic oxide;
the R source material is an oxide of R;
the carbon source material is sucrose;
the solvent is formed by mixing deionized water and ethanol, wherein the volume ratio of the deionized water to the ethanol is 1/10.
9. The use of the rare earth element-doped silicate positive electrode material of claim 1 in a lithium ion battery positive electrode.
CN202010567407.8A 2020-06-19 2020-06-19 Rare earth element doped silicate positive electrode material, and preparation method and application thereof Pending CN111682204A (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102088074A (en) * 2009-12-02 2011-06-08 深圳市贝特瑞新能源材料股份有限公司 Anode material of composite silicate and preparation method thereof
CN105375029A (en) * 2015-12-09 2016-03-02 三峡大学 Ternary silicate composite cathode material and preparation method therefor
CN108054381A (en) * 2017-12-29 2018-05-18 济南大学 A kind of rear-earth-doped type lithium manganese silicate anode material and its microwave radiation technology preparation method

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102088074A (en) * 2009-12-02 2011-06-08 深圳市贝特瑞新能源材料股份有限公司 Anode material of composite silicate and preparation method thereof
CN105375029A (en) * 2015-12-09 2016-03-02 三峡大学 Ternary silicate composite cathode material and preparation method therefor
CN108054381A (en) * 2017-12-29 2018-05-18 济南大学 A kind of rear-earth-doped type lithium manganese silicate anode material and its microwave radiation technology preparation method

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