Scandium-based negative electrode material, and preparation method and application thereof

Abstract

The embodiment of the present application relates to a kind of scandium negative electrode material and its preparation method and application.The preparation method includes: the homogeneous solution obtained by dissolving the ion-free aqueous solution of scandium-containing compound, first solution is obtained by adding coagulation agent and stirring mixing;First solution is placed in heating device, the molecular chain of coagulation agent is broken and dissolved, and the sol of cross-linked scandium ion-containing solution is formed;The solid gel is obtained by the sol at room temperature;Solid gel is heat-pressed and cured to obtain the solidified sample of scandium ion uniform dispersion;The carbon matrix containing scandium nitride is obtained by heat treatment of solidified sample in tube furnace, and the carbon matrix containing scandium nitride is modified by soaking in surface oxidizing agent solution, the modified sample is washed with water and suction filtered, and the modified scandium-based carbon matrix is obtained after drying;Or the carbon matrix containing scandium nitride is directly washed with water and suction filtered, and the unmodified scandium-based carbon matrix is obtained after drying;Finally, under oxidizing atmosphere, the residual carbon is removed to obtain scandium oxide nanoparticles.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy battery negative electrode materials, and particularly relates to a scandium-based negative electrode material and a preparation method and application thereof. BACKGROUND

[0002] It is of practical significance to develop green and environmentally friendly lithium ion secondary batteries with high energy density for the development of new energy technology. As a core material, the negative electrode material can affect the capacity, cycle and charge-discharge performance of the lithium ion battery. Scandium oxide nanoparticles exhibit a cubic structure of rare earth sesquioxide, have good mechanical properties, optical properties, electrical properties and thermal conductivity, and have broad application prospects in the fields of ceramic materials, high-temperature superconducting materials, high-performance magnetic materials and catalytic materials. In addition, due to the excellent thermal stability, chemical stability, high dielectric constant and low dielectric loss of scandium oxide, it becomes a potential functional material for preparing high-performance lithium ion secondary battery negative electrode materials.

[0003] The current commonly used method for preparing scandium oxide in industry is to react a strong base with a scandium salt to generate scandium hydroxide by precipitation, and then to form scandium oxide by thermal decomposition of the scandium hydroxide. However, this reaction is not easy to control, has high risk, and residual alkali is not easy to remove, which can easily introduce additional metal ions during preparation. The scandium oxide material prepared by this method cannot be well applied to lithium ion secondary battery negative electrode materials. The method for obtaining scandium oxide by relying on the thermal decomposition reaction of the existing scandium salt is not easy to control, and impurities cannot be effectively removed, often failing to meet the requirements of negative electrode materials application, affecting the electrochemical performance. Therefore, it is necessary to develop a safer and more convenient preparation method of scandium-based negative electrode materials for industrial application, so as to obtain a lithium battery negative electrode material with high capacity, high stability and commercial application. SUMMARY

[0004] The purpose of the present application is to provide a scandium-based negative electrode material and a preparation method and application thereof. The method prepares scandium oxide nanoparticles by gel-thermal pressure limited solidification. When the scandium-containing compound and the coagulant are mutually soluble and form a gel at room temperature, the overall dispersibility and uniformity of the scandium-containing compound molecules are significantly improved. During the evaporation process of the solvent molecules, the intermolecular forces and pressure generated during the thermal pressure solidification make the material improve the dispersion degree of scandium ions while being solidified, and form a material with a dense structure. The scandium-based negative electrode material synthesized by the technical scheme of the present application is uniformly dispersed and has high purity. The preparation method has simple synthesis process, high safety, and can be used for large-scale production by using the existing equipment.

[0005] To this end, in a first aspect, the embodiments of the present application provide a preparation method of a scandium-based negative electrode material, comprising:

[0006] Dissolving the scandium-containing compound in deionized water to prepare a homogeneous solution with a mass concentration of 10%-40%, and adding a coagulant to the homogeneous solution, stirring and mixing uniformly to obtain a first solution;

[0007] Placing the first solution in a heating device, heating to 80-100℃, and keeping the temperature for 0.5-1h, so that the molecular chains of the coagulant are broken and dissolved, and the first solution forms a sol of cross-linked scandium ion solution; placing the sol at room temperature to obtain a solid gel;

[0008] Hot-pressing the solid gel to obtain a solidified sample with uniform dispersion of scandium ions;

[0009] Placing the solidified sample in a tube furnace, heating to 700-1000℃ at a rate of 2-10℃ / min under a nitrogen atmosphere, and keeping the temperature for 2-6h to obtain a scandium nitride-containing carbon matrix;

[0010] Soaking the scandium nitride-containing carbon matrix in a surface oxidizing agent solution with a concentration of 60%-80% at 20-60℃ for 1-6h to modify the scandium nitride-containing carbon matrix, and then washing the modified sample with water, filtering to neutral pH, and drying to obtain a modified scandium-based carbon matrix; or directly washing the scandium nitride-containing carbon matrix with water, filtering to neutral pH, and drying to obtain an unmodified scandium-based carbon matrix; wherein the modified scandium-based carbon matrix has oxygen-containing functional groups on the carbon matrix;

[0011] Sintering the modified scandium-based carbon matrix or the unmodified scandium-based carbon matrix in an oxidizing atmosphere at a rate of 2-10℃ / min to a set temperature, and keeping the temperature for 2-6h to remove residual carbon in the modified scandium-based carbon matrix, to obtain scandium oxide nanoparticles.

[0012] Preferably, the scandium-containing compound includes one or more of scandium chloride, scandium nitrate, scandium sulfate, scandium oxalate, and their hydrates;

[0013] The coagulant includes one or more of agar, carrageenan, gelatin, gum arabic, or pectin;

[0014] The mass ratio of scandium in the scandium-containing compound to the coagulant is 1:2-1:10.

[0015] Preferably, the standing time is 8-20 hours;

[0016] The hot-pressing pressure is 10-30MPa, the temperature is 150-250℃, and the hot-pressing time is 0.5-2h.

[0017] Preferably, the surface oxidant solution specifically comprises one or more of a potassium permanganate solution, a nitric acid solution, and a sulfuric acid solution.

[0018] The chemical reactions that occur during the modification of the nitrogen-containing scandium carbide carbon matrix include: a redox reaction between the scandium nitride in the nitrogen-containing scandium carbide carbon matrix and the surface oxidant solution, to generate one or more of Sc2(SO4)3, Sc(NO3)3, and Sc2O3; and the generation of oxygen-containing functional groups on the surface of the carbon matrix.

[0019] Further preferably, when the surface oxidant solution used comprises a sulfuric acid solution, the set temperature during sintering of the modified scandium-based carbon matrix is 800-1000°C.

[0020] When the surface oxidant solution used is a potassium permanganate solution and / or a nitric acid solution, the set temperature is 600-800°C.

[0021] The oxidizing atmosphere comprises air or oxygen.

[0022] In the oxidizing atmosphere, the residual carbon on the carbon matrix in the modified scandium-based carbon matrix is oxidized by oxygen to generate carbon dioxide, and at the same time, the Sc2(SO4)3 or Sc(NO3)3 present in the modified scandium-based carbon matrix is decomposed by heat to form the scandium oxide nanoparticles.

[0023] Further preferably, when the surface oxidant solution used is a potassium permanganate solution, the byproduct of the redox reaction also comprises MnO2, which is present on the surface of the scandium-based negative electrode material after the sintering as a negative electrode coating layer of the scandium oxide nanoparticles and / or is present in the scandium-based negative electrode material as an additive.

[0024] Preferably, during sintering of the unmodified scandium-based carbon matrix, in the oxidizing atmosphere, the residual carbon on the carbon matrix in the unmodified scandium-based carbon matrix is oxidized by oxygen to generate carbon dioxide, and at the same time, the ScN present in the unmodified scandium-based carbon matrix is oxidized to form the scandium oxide nanoparticles.

[0025] In a second aspect, an embodiment of the present application provides a scandium-based negative electrode material prepared by the preparation method of the first aspect.

[0026] In a third aspect, an embodiment of the present application provides a lithium battery negative electrode sheet comprising the scandium-based negative electrode material of the second aspect.

[0027] In a fourth aspect, an embodiment of the present application provides a lithium battery comprising the lithium battery negative electrode sheet of the third aspect.

[0028] The preparation method of the scandium-based negative electrode material provided by the embodiment of the present application prepares scandium oxide nanoparticles through gel-thermal compression limited solidification. When the scandium-containing compound and the coagulant are mutually soluble and form a gel at room temperature, the overall dispersibility and uniformity of the scandium-containing compound molecules are significantly improved. During the evaporation of solvent molecules, intermolecular forces and pressure are generated, so that the scandium ion dispersity is improved while the material is solidified, and a material with a compact structure is formed. Through modification by a surface oxidant solution, oxygen-containing functional groups are generated on the carbon matrix of the modified scandium-based carbon matrix, so that carbon elements and impurities in the material can be more easily and fully removed during the subsequent carbon removal process of oxidation sintering, so that the obtained material has higher purity. The scandium-based negative electrode material synthesized through the technical solution of the present application is uniformly dispersed and has high purity. The preparation method has simple synthesis process and high safety, and can be used for large-scale production by using the existing equipment. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 A preparation method of a scandium-based negative electrode material provided by the embodiment of the present application is shown in a flowchart.

[0030] Figure 2 A preparation method of a scandium-based negative electrode material provided by the embodiment of the present application is shown in a flowchart. DETAILED DESCRIPTION

[0031] The technical solution of the present application will be described in further detail below by means of the drawings and embodiments.

[0032] The embodiment of the present application provides a preparation method of a scandium-based negative electrode material, as shown in the figure, the preparation method comprises the following steps. Figure 1

[0033] In step 110, a scandium-containing compound is dissolved in deionized water to prepare a homogeneous solution with a mass concentration of 10%-40%, and a coagulant is added to the homogeneous solution, stirred and uniformly mixed to obtain a first solution.

[0034] The scandium-containing compound includes one or more of scandium chloride, scandium nitrate, scandium sulfate, scandium oxalate and their hydrates.

[0035] The coagulant includes one or more of agar, carrageenan, gelatin, gum arabic or pectin.

[0036] The mass ratio of scandium in the scandium-containing compound to the coagulant is 1:2-1:10.

[0037] In step 120, the first solution is placed in a heating device and heated to 80-100℃ for 0.5-1h to make the molecular chains of the coagulant break and dissolve, so that the first solution forms a sol of cross-linked scandium ion solution. The sol is left to stand at room temperature to obtain a solid gel.​

[0038] The standing time is 8-20 hours.

[0039] In step 130, the solid gel is hot-pressed to obtain a solidified sample with uniformly dispersed scandium ions.

[0040] The hot-pressing pressure is 10-30 MPa, the temperature is 150-250℃, and the hot-pressing time is 0.5-2 hours.

[0041] In step 140, the solidified sample is placed in a tube furnace and heated to 700-1000℃ at a rate of 2-10℃ / min under a nitrogen atmosphere, and held for 2-6 hours to obtain a carbon matrix containing scandium nitride.

[0042] In this process, the organic components in the gel are carbonized at high temperature to form a carbon matrix.

[0043] In step 150, the carbon matrix containing scandium nitride is immersed in a surface oxidizing agent solution with a concentration of 60-80% at 20-60℃ for 1-6 hours to modify the carbon matrix containing scandium nitride. The modified sample is washed with water, filtered to neutral pH, and dried to obtain a modified scandium-based carbon matrix.

[0044] Specifically, the surface oxidizing agent solution specifically includes one or more of potassium permanganate solution, nitric acid solution, and sulfuric acid solution.

[0045] The chemical reactions that occur during the modification of the carbon matrix containing scandium nitride include: the scandium nitride in the carbon matrix containing scandium nitride undergoes a redox reaction with the surface oxidizing agent solution to generate one or more of Sc2(SO4)3, Sc(NO3)3, and Sc2O3.

[0046] The specific reaction process can include but is not limited to the following reactions:

[0047] 2ScN + 5H2SO4→ Sc2(SO4)3 + 2NH4HSO4;

[0048] 2ScN + 2KMnO4 + 5H2O→ Sc2O3 + 2MnO2 + 2KNO3 + 10H + ;

[0049] ScN + 4HNO3→ Sc(NO3)3 + NH4NO, or one or more of the above.

[0050] At the same time, oxygen-containing functional groups are generated on the carbon matrix.

[0051] Step 160, the modified scandium-based carbon matrix is sintered in an oxidizing atmosphere at a temperature increasing at 2-10℃ / min to a set temperature for 2-6h to remove residual carbon in the modified scandium-based carbon matrix, and to obtain scandium oxide nanoparticles.

[0052] When the surface oxidizing agent solution used in the sintering of the modified scandium-based carbon matrix includes sulfuric acid solution, the preferred set temperature is 800-1000℃; when the surface oxidizing agent solution used includes potassium permanganate solution and / or nitric acid solution, the preferred set temperature is 600-800℃.

[0053] The oxidizing atmosphere includes air or oxygen.

[0054] In the oxidizing atmosphere, the residual carbon on the carbon matrix in the modified scandium-based carbon matrix is oxidized by oxygen to generate carbon dioxide, and at the same time, Sc2(SO4)3 or Sc(NO3)3 in the modified scandium-based carbon matrix is decomposed by heat to form scandium oxide nanoparticles. The decomposition products of Sc(NO3)3 include scandium oxide (Sc2O3), gaseous nitrogen oxides and oxygen; the decomposition products of Sc2(SO4)3 include scandium oxide (Sc2O3), gaseous sulfur oxides and oxygen.

[0055] Because the modification of the surface oxidizing agent solution in the previous step generates oxygen-containing functional groups on the carbon matrix of the modified scandium-based carbon matrix, the carbon removal process in the oxidation sintering of this step can more easily and fully react, removing carbon elements while also carrying away impurities in the material, resulting in a higher purity of the obtained material.

[0056] Further, when the surface oxidizing agent solution used is potassium permanganate solution, the byproduct of the oxidation-reduction reaction also includes MnO2, which exists on the surface of the scandium-based negative electrode material after sintering as a negative electrode coating layer of scandium oxide nanoparticles, helping to improve the safety and stability of the battery, and / or exists in the scandium-based negative electrode material as an additive, helping to stabilize the cycle performance of the battery, prolong the service life of the battery, and improve the capacity retention rate of the battery.

[0057] The embodiments of the present application also provide another method for preparing a scandium-based negative electrode material, as shown in Figure 2 The preparation method includes:

[0058] Step 210, a scandium-containing compound is dissolved in deionized water to prepare a homogeneous solution with a mass concentration of 10-40%, and a coagulant is added to the homogeneous solution and stirred and mixed uniformly to obtain a first solution;

[0059] The scandium-containing compound includes one or more of scandium chloride, scandium nitrate, scandium sulfate, scandium oxalate and their hydrates.

[0060] The coagulant includes one or more of agar, carrageenan, gelatin, gum arabic, or pectin.

[0061] The mass ratio of scandium in the scandium-containing compound to the coagulant is 1:2-1:10.

[0062] In step 220, the first solution is placed in a heating device and heated to 80-100°C for 0.5-1 h, so that the molecular chains of the coagulant are broken and dissolved, and the first solution forms a sol of cross-linked scandium ion-containing solution. The sol is left to stand at room temperature to obtain a solid gel.

[0063] The standing time is 8-20 h.

[0064] In step 230, the solid gel is hot-pressed to obtain a solidified sample in which scandium ions are uniformly dispersed.

[0065] The hot-pressing pressure is 10-30 MPa, the temperature is 150-250°C, and the hot-pressing time is 0.5-2 h.

[0066] In step 240, the solidified sample is placed in a tube furnace and heated to 700-1000°C at a rate of 2-10°C / min under a nitrogen atmosphere, and held for 2-6 h to obtain a carbon matrix containing scandium nitride.

[0067] In this process, the organic components in the gel are carbonized at high temperature to form a carbon matrix.

[0068] In step 250, the carbon matrix containing scandium nitride is directly washed with water, filtered to neutral pH, and dried to obtain an unmodified scandium-based carbon matrix.

[0069] In step 260, the unmodified scandium-based carbon matrix is heated to a set temperature at a rate of 2-10°C / min in an oxidizing atmosphere and sintered for 2-6 h to remove residual carbon in the modified scandium-based carbon matrix to obtain scandia nanoparticles.

[0070] The preferred set temperature is 600-800°C.

[0071] The oxidizing atmosphere includes air or oxygen.

[0072] In the oxidizing atmosphere, the residual carbon on the carbon matrix in the unmodified scandium-based carbon matrix is oxidized by oxygen to generate carbon dioxide, and the ScN present in the unmodified scandium-based carbon matrix is oxidized to form the scandia nanoparticles.

[0073] 4ScN + 3O2→ 2Sc2O3 + N2.

[0074] In the above preparation methods of the scandium-based negative electrode material of the present application, the scandium oxide nanoparticles are prepared by using the gel-thermal compression limited solidification method. The scandium-containing compound is dispersed in the sol, and when the gel is formed, the dispersion force and mixing uniformity between the molecules are significantly improved. The thermal solidification is accompanied by the evaporation of solvent molecules, and the intermolecular forces and pressures generated make the material solidify while the scandium ions are uniformly dispersed and the structure is dense. The preparation method provided by the present application optimizes the dispersion uniformity of the scandium-based material, has high purity of the synthesized material, is simple in preparation process, and can be mass-produced by using the existing equipment.

[0075] The scandium oxide nanoparticles prepared in the embodiments of the present application have a cubic structure, and have obvious advantages in physical and chemical properties. Due to the excellent thermal stability, chemical stability, high dielectric constant and low dielectric loss, the material has high reversible charge and discharge specific capacity and cycle stability, and can exhibit excellent electrochemical performance, and has wide application prospects in the preparation of high-performance negative electrode materials.

[0076] The scandium-based negative electrode material prepared by the preparation method of the embodiments of the present application can be used as a lithium ion battery negative electrode material and applied to lithium battery pole pieces and lithium batteries.

[0077] In order to more clearly illustrate the purposes and advantages of the present application, the present application will be further described below in combination with embodiments. In addition, the embodiments described in the present application are only part of the embodiments, and all other embodiments obtained by those skilled in the art on the basis of the embodiments described in the present application without creative labor are within the protection scope of the present application. In addition, it should be understood that these embodiments are only used for more detailed description, and should not be understood as limiting the present application in any form, i.e. not intended to limit the protection scope of the present application.

[0078] Embodiment 1

[0079] The present embodiment provides a preparation method and performance test of a scandium-based negative electrode material, and the specific preparation process is as follows.

[0080] Take 200 g of scandium nitrate and dissolve it in 300 ml of deionized water to prepare a homogeneous solution with a concentration of 40%. Add 389.3 g of agar powder and mix until uniform. Place the solution in a constant-temperature water bath and heat to 80°C for 1 h to allow the molecular chains of the coagulant to break and dissolve, forming a sol of cross-linked scandium ion-containing solution. Then, place the sol at room temperature for 12 h to form a solid gel. Place the gel in a hot press and maintain a hot-pressing curing pressure of 20 MPa, a hot-pressing temperature of 200°C, and a hot-pressing time of 1 h. Place the scandium-containing sample after hot pressing in a tube furnace and heat to 700°C at a rate of 2°C / min under a nitrogen atmosphere, and maintain the temperature for 6 h to obtain a carbon matrix containing scandium nitride. Oxidize the carbon matrix containing scandium nitride in an 80% sulfuric acid solution at a temperature of 60°C for 1 h, wash the sample with water, and filter to neutral pH. Dry the modified scandium-based carbon matrix to obtain scandium oxide nanoparticles by heating the matrix to 600°C at a rate of 2°C / min in an air atmosphere and maintaining the temperature for 6 h to remove residual carbon in the modified scandium-based carbon matrix.

[0081] The prepared negative electrode material is used to prepare a negative electrode sheet and assemble a coin-type half-cell for testing, as follows.

[0082] The prepared scandium-based lithium-ion battery negative electrode material is mixed with conductive carbon black, sodium carboxymethyl cellulose, and butadiene-styrene rubber in a mass ratio of 94%:2%:3%:3% in an aqueous solvent using a beater to obtain a battery slurry. The slurry is coated on a copper foil, dried, cut, and assembled into a coin-type half-cell in a glove box, and the electrochemical performance is evaluated.

[0083] The electrochemical test mode is as follows: discharge at 0.1C to 0.005V, discharge at 0.05C to 0.005V, and discharge at 0.02C to 0.005V in the first week. Charge at 0.1C to 1V cutoff after 5 s, and subsequent cycles are discharged at 0.5C to 0.005V, discharged at 0.2C to 0.005V, discharged at 0.05C to 0.005V, discharged at 0.02C to 0.005V, and charged at 0.5C to 1V cutoff after 5 s.

[0084] In the above electrochemical test, discharge is the lithium intercalation process, corresponding to charging in a full cell. In the above electrochemical test, charging is the lithium extraction process, corresponding to discharging in a full cell.

[0085] The prepared negative electrode material is coated on a copper foil in the above proportions, and a 1 Ah soft-pack battery is assembled using lithium cobalt oxide as the positive electrode to test its cycle performance at 0.5C.

[0086] The test results of the first cycle efficiency and 100-week capacity retention rate of the half-cell prepared in this example are shown in Table 1.

[0087] Example 2

[0088] The embodiment provides a preparation method and performance test of a scandium-based negative electrode material. The specific preparation process is as follows.

[0089] 200g of scandium nitrate is weighed and dissolved in 1800ml of deionized water to prepare a homogeneous solution with a concentration of 10%, and 77.9g of agar powder is added and stirred and mixed uniformly. The above solution is placed in a constant temperature water bath, heated to 100℃, and maintained for 0.5h, so that the molecular chain of the coagulant is broken and dissolved to form a sol of cross-linked scandium ion-containing solution. Then, the sol is placed at room temperature for 12h to form a solid gel. The gel is placed under a hot press, and the hot press solidification pressure is 30MPa, the hot press temperature is 150℃, and the hot press time is 1h. The scandium-containing sample after hot pressing is placed in a tube furnace, heated to 1000℃ at a rate of 10℃ / min under a nitrogen atmosphere, and maintained for 2h to obtain a carbon matrix containing scandium nitride. The above carbon matrix containing scandium nitride is treated in a 60% concentration nitric acid solution at a temperature of 20℃ for 6h, and the sample is washed with water, suction filtered to a neutral pH, and dried to obtain a modified scandium-based carbon matrix. The modified scandium-based carbon matrix is heated to 800℃ at a rate of 10℃ / min in an air atmosphere, and maintained for 2h to remove residual carbon in the modified scandium-based carbon matrix, to obtain scandium oxide nanoparticles.

[0090] The prepared negative electrode material is prepared into a negative electrode sheet and assembled into a button-type half battery for testing. The assembly and testing method are the same as in Embodiment 1.

[0091] The test results of the first cycle efficiency and 100-week capacity retention rate of the half battery prepared in this embodiment are shown in Table 1.

[0092] Embodiment 3

[0093] The embodiment provides a preparation method and performance test of a scandium-based negative electrode material. The specific preparation process is as follows.

[0094] Take 200g of scandium chloride and dissolve it in 1133ml of deionized water to prepare a homogeneous solution with a concentration of 15%, add 237.5g of agar powder, and stir until well mixed. Place the above solution in a constant temperature water bath and heat to 80°C for 1h, so that the molecular chains of the solidifying agent are broken and dissolved, forming a cross-linked sol of scandium ion-containing solution. Then, place the sol at room temperature for 12h to form a solid gel. Place the gel under a hot press and maintain a hot press curing pressure of 15MPa, a hot press temperature of 180°C, and a hot press time of 2h. Place the hot-pressed scandium-containing sample in a tube furnace and heat to 900°C at a rate of 3°C / min under a nitrogen atmosphere, and maintain for 3h to obtain a carbon matrix containing scandium nitride. Place the above carbon matrix containing scandium nitride in a 60% concentration potassium permanganate solution, treat at a temperature of 50°C for 4h, wash the sample with water, filter to neutral pH, and dry to obtain a modified scandium-based carbon matrix. Heat the modified scandium-based carbon matrix in an air atmosphere to 750°C at a rate of 5°C / min and maintain for 3h to remove residual carbon in the modified scandium-based carbon matrix, and obtain scandium oxide nanoparticles.

[0095] The prepared negative electrode material is prepared into a negative electrode sheet and assembled into a coin-type half-cell for testing. The assembly and testing methods are the same as in Example 1.

[0096] The test results of the first cycle efficiency and 100th cycle capacity retention rate of the half-cell prepared in this example are shown in Table 1.

[0097] Example 4

[0098] This example provides a preparation method and performance test of a scandium-based negative electrode material. The specific preparation process is as follows.

[0099] Take 200g of scandium chloride and dissolve it in 1133ml of deionized water to prepare a homogeneous solution with a concentration of 15%, add 237.5g of agar powder, and stir until well mixed. Place the above solution in a constant temperature water bath and heat to 80°C for 1h, so that the molecular chains of the solidifying agent are broken and dissolved, forming a cross-linked sol of scandium ion-containing solution. Then, place the sol at room temperature for 12h to form a solid gel. Place the gel under a hot press and maintain a hot press curing pressure of 15MPa, a hot press temperature of 180°C, and a hot press time of 2h. Place the hot-pressed scandium-containing sample in a tube furnace and heat to 900°C at a rate of 3°C / min under a nitrogen atmosphere, and maintain for 3h to obtain a carbon matrix containing scandium nitride. Place the above carbon matrix containing scandium nitride in a 60% concentration potassium permanganate solution, treat at a temperature of 50°C for 4h, wash the sample with water, filter to neutral pH, and dry to obtain a modified scandium-based carbon matrix. Heat the modified scandium-based carbon matrix in an air atmosphere to 750°C at a rate of 5°C / min and maintain for 3h to remove residual carbon in the modified scandium-based carbon matrix, and obtain scandium oxide nanoparticles.

[0100] The prepared negative electrode material was used to prepare a negative electrode sheet and assemble a button-type half battery for testing. The assembly and testing methods were the same as in Example 1.

[0101] The test results of the first cycle efficiency and 100 cycle capacity retention of the half battery prepared in this example are recorded in Table 1.

[0102] Example 5

[0103] This example provides a preparation method and performance test of a scandium-based negative electrode material. The specific preparation process is as follows.

[0104] 200 g of scandium chloride was dissolved in 600 ml of deionized water to prepare a homogeneous solution with a concentration of 25%, and 356.2 g of carrageenan powder was added and stirred until uniformly mixed. The above solution was placed in a constant temperature water bath and heated to 80°C for 1 h to cause the molecular chains of the coagulant to break and dissolve, forming a sol of cross-linked scandium ion-containing solution. Then, the sol was placed at room temperature for 12 h to form a solid gel. The gel was placed in a hot press, and the hot press solidification pressure was maintained at 12 MPa, the hot press temperature was 190°C, and the hot press time was 1.5 h. The scandium-containing sample after hot pressing was placed in a tube furnace and heated to 900°C at a rate of 3°C / min under a nitrogen atmosphere, and maintained for 3 h to obtain a carbon matrix containing scandium nitride. The above carbon matrix containing scandium nitride was treated in a 60% potassium permanganate solution at a temperature of 50°C for 3 h of oxidation modification, and the sample was washed with water, suction filtered to a neutral pH, and dried to obtain a modified scandium-based carbon matrix. The modified scandium-based carbon matrix was heated to 750°C at a rate of 5°C / min in an air atmosphere and maintained for 3 h to remove residual carbon in the modified scandium-based carbon matrix, obtaining scandium oxide nanoparticles.

[0105] The prepared negative electrode material was used to prepare a negative electrode sheet and assemble a button-type half battery for testing. The assembly and testing methods were the same as in Example 1.

[0106] The test results of the first cycle efficiency and 100 cycle capacity retention of the half battery prepared in this example are recorded in Table 1.

[0107] Example 6

[0108] This example provides a preparation method and performance test of a scandium-based negative electrode material. The specific preparation process is as follows.

[0109] Take 200g of scandium chloride dissolved in 1133ml of deionized water to prepare a homogeneous solution with a concentration of 15%, add 474.9g of carrageenan powder, and mix well. Place the above solution in a constant temperature water bath, heat to 80℃, and maintain for 1h to allow the molecular chain of the coagulant to break and dissolve, forming a cross-linked sol containing scandium ion solution. Then, place the sol at room temperature for 12h to form a solid gel. Place the gel under a hot press, maintain a hot pressing and curing pressure of 20MPa, a hot pressing temperature of 200℃, and a hot pressing time of 1.5h. Place the scandium-containing sample after hot pressing in a tube furnace, heat to 700℃ at 2℃ / min under a nitrogen atmosphere, and maintain for 6h to obtain a carbon matrix containing scandium nitride. Treat the above carbon matrix containing scandium nitride in a 80% concentration potassium permanganate solution at a treatment temperature of 50℃ for 4h, wash the sample with water, filter to neutral pH, and dry to obtain a modified scandium-based carbon matrix. Heat the modified scandium-based carbon matrix in an air atmosphere to 800℃ at 5℃ / min and maintain for 4h to remove residual carbon in the modified scandium-based carbon matrix, and obtain scandium oxide nanoparticles.

[0110] The prepared negative electrode material is prepared into a negative electrode sheet and assembled into a coin-type half-cell for testing. The assembly and testing methods are the same as in Example 1.

[0111] The test results of the first cycle efficiency and 100th cycle capacity retention rate of the half-cell prepared in this example are shown in Table 1.

[0112] Example 7

[0113] This example provides a preparation method and performance test of a scandium-based negative electrode material. The specific preparation process is as follows.

[0114] Take 200g of scandium chloride dissolved in 400ml of deionized water to prepare a homogeneous solution with a concentration of 33.3%, add 415.5g of carrageenan powder, and mix well. Place the above solution in a constant temperature water bath, heat to 95℃, and maintain for 0.5h to allow the molecular chain of the coagulant to break and dissolve, forming a cross-linked sol containing scandium ion solution. Then, place the sol at room temperature for 12h to form a solid gel. Place the gel under a hot press, maintain a hot pressing and curing pressure of 30MPa, a hot pressing temperature of 150℃, and a hot pressing time of 2h. Place the scandium-containing sample after hot pressing in a tube furnace, heat to 800℃ at 2℃ / min under a nitrogen atmosphere, and maintain for 5h to obtain a carbon matrix containing scandium nitride. Treat the above carbon matrix containing scandium nitride in a 80% concentration potassium permanganate solution at a treatment temperature of 80℃ for 2h, wash the sample with water, filter to neutral pH, and dry to obtain a modified scandium-based carbon matrix. Heat the modified scandium-based carbon matrix in an air atmosphere to 750℃ at 5℃ / min and maintain for 6h to remove residual carbon in the modified scandium-based carbon matrix, and obtain scandium oxide nanoparticles.

[0115] The prepared negative electrode material was used to prepare a negative electrode sheet and assemble a coin-type half battery for testing. The assembly and testing methods were the same as in Example 1.

[0116] The test results of the first cycle efficiency and the 100 cycle capacity retention of the half battery prepared in this example are recorded in Table 1.

[0117] Example 8

[0118] This example provides a preparation method and performance test of a scandium-based negative electrode material. The specific preparation process is as follows.

[0119] 200 g of scandium sulfate pentahydrate was weighed and dissolved in 800 ml of deionized water to prepare a homogeneous solution with a concentration of 20%, and 384.1 g of agar powder was added and stirred until uniformly mixed. The above solution was placed in a constant temperature water bath and heated to 80°C for 1 h to allow the molecular chains of the coagulant to break and dissolve, forming a sol of cross-linked scandium ion-containing solution. Then, the sol was placed at room temperature for 12 h to form a solid gel. The gel was placed in a hot press and maintained at a hot-pressing solidification pressure of 30 MPa, a hot-pressing temperature of 250°C, and a hot-pressing time of 0.5 h. The scandium-containing sample after hot-pressing was placed in a tube furnace and heated to 1000°C at a rate of 10°C / min under a nitrogen atmosphere, and maintained for 3 h to obtain a carbon matrix containing scandium nitride. The above carbon matrix containing scandium nitride was treated in a 80% concentrated sulfuric acid solution at a temperature of 60°C for 2 h of oxidation modification, and the sample was washed with water, suction filtered to a neutral pH, and dried to obtain a modified scandium-based carbon matrix. The modified scandium-based carbon matrix was heated to 650°C at a rate of 2°C / min in an air atmosphere and maintained for 5 h to remove residual carbon in the modified scandium-based carbon matrix, thereby obtaining scandium oxide nanoparticles.

[0120] The prepared negative electrode material was used to prepare a negative electrode sheet and assemble a coin-type half battery for testing. The assembly and testing methods were the same as in Example 1.

[0121] The test results of the first cycle efficiency and the 100 cycle capacity retention of the half battery prepared in this example are recorded in Table 1.

[0122] Example 9

[0123] This example provides a preparation method and performance test of a scandium-based negative electrode material. The specific preparation process is as follows.

[0124] Take 200g of scandium sulfate pentahydrate and dissolve it in 1000ml of deionized water to prepare a homogeneous solution with a concentration of 16.7%. Add 268.9g of gelatin powder and mix well. Place the solution in a constant temperature water bath and heat it to 90°C for 0.75h to break the molecular chains of the coagulant and dissolve it, forming a sol of cross-linked scandium ion-containing solution. Then, place the sol at room temperature for 12h to form a solid gel. Place the gel in a hot press and maintain a hot pressing and curing pressure of 25MPa and a hot pressing temperature of 220°C for 1.5h. Place the hot-pressed scandium-containing sample in a tube furnace and heat it to 800°C at a rate of 4°C / min under a nitrogen atmosphere, and maintain the temperature for 3h to obtain a carbon matrix containing scandium nitride. Oxidize the carbon matrix containing scandium nitride in a 80% concentration nitric acid solution at a temperature of 50°C for 5h. Wash the sample with water, filter it to neutral pH, and dry it to obtain a modified scandium-based carbon matrix. Heat the modified scandium-based carbon matrix in an air atmosphere to 800°C at a rate of 4°C / min and maintain the temperature for 3h to remove residual carbon in the modified scandium-based carbon matrix, obtaining scandium oxide nanoparticles.

[0125] The prepared negative electrode material is used to prepare a negative electrode sheet and assemble a coin-type half-cell for testing. The assembly and testing methods are the same as those in Example 1.

[0126] The test results of the first cycle efficiency and 100th cycle capacity retention rate of the half-cell prepared in this example are shown in Table 1.

[0127] Example 10

[0128] This example provides a preparation method and performance test of a scandium-based negative electrode material. The specific preparation process is as follows.

[0129] Take 200g of scandium oxide and dissolve it in 1800ml of deionized water to prepare a homogeneous solution with a concentration of 10%. Add 532.9g of pectin powder and mix well. Place the solution in a constant temperature water bath and heat it to 100°C for 1h to break the molecular chains of the coagulant and dissolve it, forming a sol of cross-linked scandium ion-containing solution. Then, place the sol at room temperature for 12h to form a solid gel. Place the gel in a hot press and maintain a hot pressing and curing pressure of 30MPa and a hot pressing temperature of 220°C for 1h. Place the hot-pressed scandium-containing sample in a tube furnace and heat it to 900°C at a rate of 2°C / min under a nitrogen atmosphere, and maintain the temperature for 4h to obtain a carbon matrix containing scandium nitride. Oxidize the carbon matrix containing scandium nitride in a 75% concentration sulfuric acid solution at a temperature of 20°C for 1.5h. Wash the sample with water, filter it to neutral pH, and dry it to obtain a modified scandium-based carbon matrix. Heat the modified scandium-based carbon matrix in an air atmosphere to 600°C at a rate of 2°C / min and maintain the temperature for 2h to remove residual carbon in the modified scandium-based carbon matrix, obtaining scandium oxide nanoparticles.

[0130] The prepared negative electrode material was used to prepare a negative electrode sheet and assemble a button-type half-cell for testing. The assembly and testing methods were the same as in Example 1.

[0131] The test results of the first cycle efficiency and the 100-cycle capacity retention rate of the half-cell prepared in this example are shown in Table 1.

[0132] Example 11

[0133] This example provides a preparation process and performance test of a negative electrode material. The specific preparation process is as follows.

[0134] 200 g of scandium nitrate was weighed and placed in a tube furnace, and heated to 700°C at a rate of 2°C / min under a nitrogen atmosphere, and maintained for 6 h to obtain a precursor containing scandium nitride. The above-mentioned precursor containing scandium nitride was placed in a 80% sulfuric acid solution, and treated at a temperature of 60°C for 1 h of oxidation modification. The sample was washed with water, suction filtered to a neutral pH, and dried to obtain a precursor containing scandium oxide. The modified scandium-based carbon matrix was heated to 600°C at a rate of 2°C / min under an air atmosphere, and maintained for 6 h to obtain scandium oxide nanoparticles.

[0135] The prepared negative electrode material was used to prepare a negative electrode sheet and assemble a button-type half-cell for testing. The assembly and testing methods were the same as in Example 1.

[0136] The test results of the first cycle efficiency and the 100-cycle capacity retention rate of the half-cell prepared in this example are shown in Table 1.

[0137] To better illustrate the effect of the embodiments of the present application, the comparative examples are compared with the above examples.

[0138] Comparative Example 1

[0139] The comparative example uses traditional nano-silicon oxide particles as a negative electrode material.

[0140] The negative electrode material of the comparative example was used to prepare a negative electrode sheet and assemble a button-type half-cell for testing. The assembly and testing methods were the same as in Example 1.

[0141] The test results of the first cycle efficiency and the 100-cycle capacity retention rate of the half-cell prepared in this example are shown in Table 1.

[0142] The following Table 1 shows the comparison data of the electrochemical performance tests of the negative electrode materials prepared in Examples 1-11 and Comparative Example 1.

[0143]

[0144]

[0145] Table 1

[0146] It can be seen from the test data in Table 1 that the first week coulomb efficiency and cycle capacity retention of examples 1-11 are better than those of comparative example 1, which is due to the fact that the preparation method of the scandium-based negative electrode material provided by the application is easy to control, safe and efficient. The scandium oxide nanoparticles have a cubic structure and obvious advantages in physical and chemical properties. The excellent thermal stability, chemical stability, high dielectric constant and low dielectric loss of the material make it have a high reversible charge-discharge specific capacity and cycle stability, and can exhibit excellent electrochemical performance. The scandium oxide nanoparticles are prepared by the gel-heat pressing limited solidification method. When the scandium-containing compound and the coagulant are mutually soluble at room temperature to form a gel, the overall dispersibility and uniformity of the scandium-containing compound molecules are significantly improved. The intermolecular forces and pressure generated during the evaporation process of the solvent molecules during heat pressing solidification make the material solidify while improving the dispersion degree of scandium ions, forming a material with a dense structure. Through the modification of the surface oxidant solution, oxygen-containing functional groups are generated on the carbon matrix of the modified scandium-based carbon matrix, which can more easily remove carbon elements and carry away impurities in the material during the subsequent carbon removal process step of oxidation sintering. Therefore, the scandium-based negative electrode material synthesized by the technical scheme of the application is uniformly dispersed and has high purity.

[0147] The above specific embodiments further illustrate the purpose, technical scheme and beneficial effects of the application. It should be understood that the above description is only a specific embodiment of the application and is not used to limit the protection scope of the application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the application should be included in the protection scope of the application.

Claims

1. A method for preparing a scandium-based negative electrode material, characterized in that, The preparation method includes: A scandium-containing compound is dissolved in deionized water to prepare a homogeneous solution with a mass concentration of 10%-40%. A coagulant is added to the homogeneous solution and stirred until homogeneous to obtain a first solution. The first solution is placed in a heating device and heated to 80℃-100℃, and kept at that temperature for 0.5h-1h, so that the molecular chains of the coagulant break and dissolve, and the first solution forms a cross-linked sol containing scandium ions; the sol is then allowed to stand at room temperature to obtain a solid gel. The solid gel was hot-pressed to obtain a solidified sample with scandium ions uniformly dispersed. The cured sample was placed in a tube furnace and heated to 700℃-1000℃ at a rate of 2℃ / min-10℃ / min under a nitrogen atmosphere, and held for 2h-6h to obtain a carbon matrix containing scandium nitride. The scandium nitride-containing carbon matrix is ​​modified by immersing it in a 60%-80% surface oxidant solution at 20℃-60℃ for 1-6 hours. The modified sample is then washed with water, filtered until the pH is neutral, and dried to obtain a modified scandium-based carbon matrix. Alternatively, the scandium nitride-containing carbon matrix can be directly washed with water, filtered until the pH is neutral, and dried to obtain an unmodified scandium-based carbon matrix. Oxygen-containing functional groups are generated on the carbon matrix of the modified scandium-based carbon matrix. The modified scandium-based carbon matrix or the unmodified scandium-based carbon matrix is ​​heated to a set temperature in an oxidizing atmosphere at a rate of 2℃ / min-10℃ / min and sintered for 2h-6h to remove residual carbon in the modified scandium-based carbon matrix, thereby obtaining scandium oxide nanoparticles. The coagulant includes one or more of agar, carrageenan, gelatin, gum arabic, or pectin; The mass ratio of scandium in the scandium-containing compound to the coagulant is 1:2 to 1:

10.

2. The preparation method according to claim 1, characterized in that, The scandium-containing compounds include one or more of scandium chloride, scandium nitrate, scandium sulfate, scandium oxalate, and their hydrates.

3. The preparation method according to claim 1, characterized in that, The settling time is 8-20 hours; The hot pressing pressure is 10MPa-30MPa, the temperature is 150℃-250℃, and the hot pressing time is 0.5h-2h.

4. The preparation method according to claim 1, characterized in that, The surface oxidant solution specifically includes one or more of potassium permanganate solution, nitric acid solution, and sulfuric acid solution; The chemical reactions that occur during the modification of the scandium nitride-containing carbon matrix include: the scandium nitride in the scandium nitride-containing carbon matrix undergoes a redox reaction with the surface oxidant solution to generate one or more of Sc2(SO4)3, Sc(NO3)3, and Sc2O3; and oxygen-containing functional groups are generated on the surface of the carbon matrix.

5. The preparation method according to claim 4, characterized in that, When sintering the modified scandium-based carbon matrix, if the surface oxidant solution used includes sulfuric acid solution, the set temperature is 800℃-1000℃; When the surface oxidant solution used is potassium permanganate solution and / or nitric acid solution, the set temperature is 600℃-800℃; The oxidizing atmosphere includes air or oxygen; In an oxidizing atmosphere, residual carbon on the modified scandium-based carbon matrix is ​​oxidized by oxygen to generate carbon dioxide. At the same time, Sc2(SO4)3 or Sc(NO3)3 present in the modified scandium-based carbon matrix is ​​thermally decomposed to form scandium oxide nanoparticles.

6. The preparation method according to claim 5, characterized in that, When the surface oxidant solution used is potassium permanganate solution, the byproduct of the redox reaction also includes MnO2. The MnO2 exists on the surface of the scandium-based anode material after sintering as an anode coating layer of scandium oxide nanoparticles and / or exists in the scandium-based anode material as an additive.

7. The preparation method according to claim 1, characterized in that, When the unmodified scandium-based carbon matrix is ​​sintered in an oxidizing atmosphere, the residual carbon on the carbon matrix is ​​oxidized by oxygen to generate carbon dioxide. At the same time, the ScN present in the unmodified scandium-based carbon matrix is ​​oxidized to form the scandium oxide nanoparticles.

8. A scandium-based anode material prepared by any one of the preparation methods according to claims 1-7.

9. A lithium battery negative electrode sheet, characterized in that, The lithium battery negative electrode sheet includes the scandium-based negative electrode material as described in claim 8.

10. A lithium battery, characterized in that, The lithium battery includes the lithium battery negative electrode sheet as described in claim 9.

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