VOx nanoring for lithium ion battery negative electrode material, preparation method of VOx nanoring, lithium battery negative electrode material and lithium battery

Abstract

The invention relates to a VOx nanoring for a lithium ion battery negative electrode material, a preparation method of the VOx nanoring, the lithium battery negative electrode material and a lithium battery. The preparation method comprises the following steps: S100, preparing raw materials: preparing sodium orthovanadate and thioacetamide; s200, mixing the raw materials to obtain a mixed solution; s300, carrying out heating reaction to generate turbid liquid with a stable nanometer annular structure; and S400, cooling and separating, namely taking out the turbid liquid in the high-pressure kettle, cooling to room temperature, separating by a centrifugal machine, cleaning and drying to obtain the dry nanoring capable of being used for the lithium battery negative electrode material. The preparation method disclosed by the invention is convenient, simple, good in repeatability, high in yield and capable of realizing large-scale production and industrialization. The prepared nanoring structure can be kept stable for a long time, the size and morphology of the nanoring are controllable, and the morphology can be regulated and controlled through the reaction time, the reaction temperature, the reactant ratio and the like.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of negative electrode materials for lithium-ion batteries, and specifically relates to VOx nanorings for negative electrode materials for lithium-ion batteries and a preparation method thereof, negative electrode materials for lithium batteries, and lithium batteries. Background Art

[0002] Among various secondary batteries, lithium-ion batteries have unique application advantages such as high energy density and long cycle life, and are therefore widely favored by people. Further improving the energy density and power density of lithium-ion batteries and reducing production costs have also become current research hotspots.

[0003] As a typical layered crystal structure material, vanadium oxide is considered to be a very competitive next-generation advanced energy storage material due to its advantages such as large discharge capacity, high energy density, abundant reserves and low cost. Vanadium oxide can be divided into vanadium oxide (such as V2O5, V6O13, V3O7·H2O, VO2(B), V2O3, etc.) and vanadate (such as Li3VO4, NaVO2, NaV2O5, etc.). Vanadium oxide has been widely used in LIBs (lithium-ion batteries) as an electrode material.

[0004] Low-dimensional nanomaterials, due to their high surface energy and high activity, are prone to self-agglomeration during the cycle, thus losing the advantages of nanomaterials and causing the electrode film to pulverize, ultimately affecting the cycle stability and rate performance. The construction of 3D micro-nanostructure electrode materials and self-supporting electrodes is considered to be a very effective way to solve the above problems. However, in the process of solving the above problems, the applicant found that in the preparation field of 3D micro-nanostructure electrode materials, there are at least the following technical problems: 1. The constructed 3D micro-nanostructure is unstable. As the battery charge and discharge cycles reach a certain number of times, the 3D micro-nanostructure becomes loose and separated, and thus cannot be stably applied; 2. The energy utilization efficiency and life are unstable. Since the constructed 3D micro-nanostructure is unstable, the energy utilization efficiency and life of the battery are also unstable, and the coulomb efficiency, one of the main parameters for judging the battery efficiency, is not high; 3. The output is unstable. The generation of 3D micro-nanostructures requires strict preparation processes to support it. The output of conventional 3D micro-nanostructures is unstable and at a low level, resulting in low yield and high production cost.

[0005] In view of this, how to solve the problems of instability of 3D micro-nanostructure electrode materials, poor battery performance, low yield, high production cost, etc. in existing lithium-ion battery negative electrode materials has become the subject to be studied and solved by the present invention. Summary of the invention

[0006] The purpose of the present invention is to provide VOx nanorings for lithium-ion battery negative electrode materials and a preparation method thereof, a lithium battery negative electrode material, and a lithium battery.

[0007] To achieve the above objectives, the first aspect of the present invention provides a method for preparing VOx nanorings for lithium-ion battery negative electrode materials, the innovation of which is:

[0008] The preparation method comprises the following steps:

[0009] S100, preparing raw materials, in terms of volume molar concentration, preparing 0.01-6.8 mM / L sodium orthovanadate and 0.01-15 mM / L thioacetamide;

[0010] S200, mixing the raw materials, adding the prepared sodium orthovanadate and thioacetamide to a unit volume of pure water, and stirring thoroughly for 3 to 8 minutes to obtain a mixed solution;

[0011] S300, heating the reaction, quickly transferring the mixed solution to an autoclave, sealing and heating the autoclave, heating the temperature to 150-230° C. at a rate of 3-6° C. per minute, and maintaining the temperature for 3-24 hours to generate a suspension having a stable nano-ring structure;

[0012] S400, cooling and separating, taking out the suspension in the autoclave, cooling it to room temperature, separating it by a centrifuge, washing it and drying it to obtain dry nanorings that can be used as negative electrode materials for lithium batteries.

[0013] To achieve the above object, the second aspect of the present invention provides a VOx nanoring for lithium-ion battery negative electrode material, wherein the nanoring is prepared by the preparation method described in the first aspect of the present invention.

[0014] To achieve the above object, the third aspect of the present invention provides a lithium battery negative electrode material, wherein the lithium battery negative electrode material uses the VOx nanoring for lithium ion battery negative electrode material as described in the second aspect of the present invention.

[0015] To achieve the above-mentioned purpose, the fourth aspect of the present invention provides a lithium battery, which comprises the lithium battery negative electrode material as described in the third aspect of the present invention. In the process of assembling the lithium battery, the lithium battery negative electrode material is used as the negative electrode, polypropylene or polyethylene is used as the separator, and 1 mol / L LiPF6 (a mixture of ethylene carbonate and dimethyl carbonate in a volume ratio of 1:1) is used as the electrolyte.

[0016] The relevant contents of the present invention are explained as follows:

[0017] 1. In the above technical scheme of the present invention, in view of the problems of instability of 3D micro-nanostructure electrode materials, poor battery performance, low yield, high production cost, etc. in existing negative electrode materials of lithium-ion batteries, a method for preparing VOx nanorings for negative electrode materials of lithium-ion batteries, a VOx nanoring for negative electrode materials of lithium-ion batteries, a negative electrode material of lithium batteries, and a lithium battery are innovatively developed. Using the preparation method of VOx nanorings for negative electrode materials of lithium-ion batteries, the prepared nanoring structure can remain stable for a long time, the size and morphology of the nanorings can be controlled, and the morphology can be regulated by reaction time, reaction temperature, reactant ratio, etc., and the stable nanoring structure can buffer the stress changes caused by volume contraction / expansion during charge and discharge, thereby showing excellent charge and discharge cycle performance, and the coulomb efficiency is close to 100%. After multiple cycles, the capacity remains at a high level. It is a very potential commercial carbon negative electrode alternative material. The preparation method is convenient, simple, reproducible, high in yield, and can be mass-produced to achieve industrialization.

[0018] 2. In the technical solution of the first aspect, in the implementation process of preparing the raw materials in step S100, 4-6.8 mM / L sodium orthovanadate and 8-15 mM / L thioacetamide are prepared in terms of volume molar concentration. With this more preferred reactant ratio, a more excellent nanoring size and morphology are prepared, further improving the performance of the prepared lithium-ion battery.

[0019] 3. In the technical solution of the first aspect above, in the implementation process of preparing the raw materials in step S200, a unit volume of pure water is 100 ml, so as to further control the yield of the nanorings and make the industrialization more controllable.

[0020] 4. In the technical solution of the first aspect above, during the implementation of step S100 of preparing the raw materials, the stirring time is 5 minutes, so as to achieve sufficient stirring with an appropriate stirring time and control the preparation time.

[0021] 5. In the technical solution of the first aspect above, during the implementation of the temperature heating reaction in step S300, the temperature is raised to 200°C at a rate of 5°C per minute and maintained at this temperature for 4 hours. By using such process parameters of reaction time and reaction temperature, the size and morphology of the formed nanorings can be made more suitable for lithium battery negative electrode materials.

[0022] 6. In the technical solution of the first aspect, during the implementation of the temperature-raising reaction in step S300, the autoclave used is a stainless steel autoclave lined with polytetrafluoroethylene and having a volume of 130 to 1030 ml, so as to ensure that the reaction process of the reactants is more stable and reliable, and to avoid contamination of the reaction process by other substances.

[0023] 7. In the technical solution of the first aspect above, during the implementation of the temperature-raising reaction in step S300, the suspension having a stable nano-ring structure is generated, and the outer diameter of the nano-ring structure is 300 to 500 nm, and the inner diameter is 200 to 400 nm.

[0024] 8. In the technical solution of the second aspect above, the nanoring is a nanoring structure with an outer diameter of 300 to 500 nm and an inner diameter of 200 to 400 nm. Nanorings of this size and morphology are more suitable for lithium battery negative electrode materials, can remain stable for a long time, and can remain stable after multiple cycles.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1. In view of the problems of instability of 3D micro-nanostructure electrode materials, poor battery performance, low yield, high production cost, etc. in existing lithium-ion battery negative electrode materials, the present invention innovatively develops a method for preparing VOx nanorings for lithium-ion battery negative electrode materials, a VOx nanoring for lithium-ion battery negative electrode materials, a lithium battery negative electrode material, and a lithium battery, so as to improve the cycle stability and rate performance of the battery.

[0027] 2. The preparation method adopted in the present invention is convenient, simple, has good repeatability, high yield, can be mass-produced, and can be industrialized.

[0028] 3. The present invention uses the method for preparing VOx nanorings for lithium-ion battery negative electrode materials. The prepared nanoring structure can remain stable for a long time, and the size and morphology of the nanorings are controllable. The morphology can be regulated by reaction time, reaction temperature, reactant ratio, etc.

[0029] 4. The stable nano-ring structure can buffer the stress changes caused by volume shrinkage / expansion during charging and discharging, thereby showing excellent charge and discharge cycle performance. The coulomb efficiency is close to 100%. After multiple cycles, the capacity remains at a high level. It is a very potential commercial carbon negative electrode alternative material. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is an electron microscope image of a nanoring structure prepared according to an embodiment of the present invention;

[0031] Figure 2 Schematic diagram of the morphology evolution of the nanoring structure at different reaction times;

[0032] Figure 3 Schematic diagram of the morphology evolution of the nanoring structure under different reaction stabilization conditions;

[0033] Figure 4 Schematic diagram of the morphology evolution of the nanoring structure at various dilution factors;

[0034] Figure 5 This is the electrochemical cycle performance curve of the negative electrode material of the lithium battery of the embodiment of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0036] Embodiment: The present invention will be clearly described below with diagrams and detailed descriptions. After understanding the embodiments of the present invention, any person skilled in the art can make changes and modifications based on the techniques taught by the present invention without departing from the spirit and scope of the present invention.

[0037] The terms used herein are only for describing specific embodiments and are not intended to be limiting of the present invention. Singular forms such as "a", "this", "here", "this" and "the" as used herein also include plural forms.

[0038] The terms “include,” “including,” “have,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0039] The terms used herein generally have the ordinary meanings of each term used in the art, in the context of the present invention, and in the specific context, unless otherwise noted. Certain terms used to describe the present invention will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art regarding the description of the present invention.

[0040] The present invention aims to solve the problems of instability of 3D micro-nanostructure electrode materials, poor battery performance, low yield, high production cost, etc. in existing lithium-ion battery negative electrode materials, and innovatively develops a method for preparing VOx nanorings for lithium-ion battery negative electrode materials, a VOx nanoring for lithium-ion battery negative electrode materials, a lithium battery negative electrode material, and a lithium battery, so as to improve the battery's cycle stability and rate performance.

[0041] In a first aspect, the present invention provides a method for preparing VOx nanorings for lithium-ion battery negative electrode materials, the preparation method comprising the following steps:

[0042] S100, preparing raw materials, in terms of volume molar concentration, preparing 0.01-6.8 mM / L sodium orthovanadate and 0.01-15 mM / L thioacetamide;

[0043] S200, mixing the raw materials, adding the prepared sodium orthovanadate and thioacetamide to a unit volume of pure water, and stirring thoroughly for 3 to 8 minutes to obtain a mixed solution;

[0044] S300, heating the reaction, quickly transferring the mixed solution to an autoclave, sealing and heating the autoclave, heating the temperature to 150-230° C. at a rate of 3-6° C. per minute, and maintaining the temperature for 3-24 hours to generate a suspension having a stable nano-ring structure;

[0045] S400, cooling and separating, taking out the suspension in the autoclave, cooling it to room temperature, separating it by a centrifuge, washing it and drying it to obtain dry nanorings that can be used as negative electrode materials for lithium batteries.

[0046] In one embodiment of the first aspect of the present invention, in the implementation process of preparing the raw materials in step S100, 4 to 6.8 mM / L sodium orthovanadate and 8 to 15 mM / L thioacetamide are prepared in terms of volume molar concentration. With this more preferred reactant ratio, a more excellent nanoring size and morphology are prepared, further improving the performance of the prepared lithium ion battery.

[0047] In another embodiment of the first aspect of the present invention, in the implementation process of preparing raw materials in step S200, one unit volume of pure water is 100 ml, and pure water can be selected as one unit volume, or 2 unit volumes, 3 unit volumes to 10 unit volumes can be selected for dilution. In this way, the yield of the nanorings can be further controlled, making the realization of industrialization more controllable.

[0048] In another embodiment of the first aspect of the present invention, during the implementation of step S100 of preparing the raw materials, the stirring time is 5 minutes, so as to achieve sufficient stirring with an appropriate stirring time and control the preparation time.

[0049] In one embodiment of the first aspect of the present invention, during the implementation of the temperature heating reaction in step S300, the temperature is raised to 200°C at a rate of 5°C per minute and maintained at this temperature for 4 hours. By using such process parameters of reaction time and reaction temperature, the size and morphology of the formed nanorings can be made more suitable for lithium battery negative electrode materials.

[0050] In another embodiment of the first aspect of the present invention, during the step S300 of heating the reaction, the autoclave used is a stainless steel autoclave lined with polytetrafluoroethylene and having a volume of 130 to 1030 ml, so as to ensure that the reaction process of the reactants is more stable and reliable, and to avoid contamination of the reaction process by other substances.

[0051] In another embodiment of the first aspect of the present invention, during the temperature rising reaction in step S300, the generated suspension having a stable nano-ring structure has an outer diameter of 300 to 500 nm and an inner diameter of 200 to 400 nm.

[0052] Through the implementation of the preparation method of VOx nanorings for lithium ion battery negative electrode materials of the present invention, the electron microscope images of the prepared nanoring structures can be referred to Figure 1 The nano-ring structure can remain stable for a long time, the preparation method can control the size and morphology of the nano-ring, and the morphology can be regulated by reaction time, reaction temperature, reactant ratio, etc. The stable nano-ring structure can buffer the stress changes caused by volume contraction / expansion during charging and discharging, thereby showing excellent charge and discharge cycle performance, and the coulomb efficiency is close to 100%. After multiple cycles, the capacity remains at a high level. It is a very potential commercial carbon negative electrode alternative material. The preparation method is convenient, simple, reproducible, and has high yield, and can be mass-produced to achieve industrialization.

[0053] In a second aspect, the present invention further proposes a VOx nanoring for a negative electrode material of a lithium-ion battery, wherein the nanoring is prepared by the preparation method described in Example 1 of the present invention.

[0054] In the second aspect of the present invention, the nanoring is a nanoring structure with an outer diameter of 300 to 500 nm and an inner diameter of 200 to 400 nm. Nanorings of this size and morphology are more suitable for lithium battery negative electrode materials, can remain stable for a long time, and can remain stable after multiple cycles.

[0055] In a third aspect, the present invention further proposes a negative electrode material for a lithium battery, wherein the negative electrode material for a lithium battery uses the VOx nanoring for the negative electrode material for a lithium ion battery as described in the second aspect of the present invention.

[0056] In a fourth aspect, the present invention further proposes a lithium battery, which comprises the lithium battery negative electrode material as described in the third aspect of the present invention. In the process of assembling the lithium battery, the lithium battery negative electrode material is used as the negative electrode, polypropylene or polyethylene is used as the separator, and 1 mol / L LiPF6 (a mixture of ethylene carbonate and dimethyl carbonate in a volume ratio of 1:1) is used as the electrolyte.

[0057] The present invention is described in detail below in conjunction with specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0058] Example 1

[0059] Embodiment 1 of the present invention provides a method for preparing VOx nanorings for lithium-ion battery negative electrode materials, the preparation method comprising the following steps:

[0060] S100, equipped with raw materials, based on volume molar concentration, equipped with 6.8mM / L high-purity sodium orthovanadate (NaVO3 ) and 15 mM / L thioacetamide (TAA);

[0061] S200, mixing the raw materials, adding the prepared sodium orthovanadate and thioacetamide to 100 ml of pure water, stirring for 5 minutes to obtain a mixed solution;

[0062] S300, heating the reaction, quickly transferring the mixed solution into an autoclave, sealing and heating the autoclave, heating it to 200° C. at a rate of 5° C. per minute, and maintaining it at this temperature for 4 hours to generate a suspension having a stable nano-ring structure;

[0063] S400, cooling and separating, taking out the suspension in the autoclave, cooling it to room temperature, separating it by a centrifuge, washing it and drying it to obtain dry nanorings that can be used as negative electrode materials for lithium batteries.

[0064] Example 2

[0065] Compared with Example 1, Example 2 is mostly the same, except that in Example 2 the temperature is maintained at 200° C. for 6 hours.

[0066] Example 3

[0067] Compared with Example 1, Example 3 is mostly the same, except that in Example 3 the temperature is maintained at 200° C. for 8 hours.

[0068] Example 4

[0069] Embodiment 4 of the present invention provides a method for preparing VOx nanorings for negative electrode materials of lithium-ion batteries, the preparation method comprising the following steps:

[0070] S100, equipped with raw materials, based on volume molar concentration, equipped with 6.8mM / L high-purity sodium orthovanadate (NaVO 3 ) and 15 mM / L thioacetamide (TAA);

[0071] S200, mixing the raw materials, adding the prepared sodium orthovanadate and thioacetamide to 100 ml of pure water, stirring for 5 minutes to obtain a mixed solution;

[0072] S300, heating the reaction, quickly transferring the mixed solution into an autoclave, sealing and heating the autoclave, heating it to 180°C at a rate of 5°C per minute, and maintaining it at this temperature for 8 hours to generate a suspension having a stable nano-ring structure;

[0073] S400, cooling and separating, taking out the suspension in the autoclave, cooling it to room temperature, separating it by a centrifuge, washing it and drying it to obtain dry nanorings that can be used as negative electrode materials for lithium batteries.

[0074] Example 5

[0075] Compared with Example 1, most of the above are the same, except that sodium vanadate (NaVO 3 ) and 15 mM / L thioacetamide (TAA) were diluted 2-fold.

[0076] Example 6

[0077] Compared with Example 1, most of the above are the same, except that sodium vanadate (NaVO 3 ) and 15 mM / L thioacetamide (TAA) were diluted 3 times.

[0078] Example 7

[0079] Compared with Example 1, most of the above are the same, except that sodium vanadate (NaVO 3 ) and 15 mM / L thioacetamide (TAA) were diluted 10 times.

[0080] Examples 8-12

[0081] Compared with Example 1, most of them are the same, except that in Examples 8-12, the stirring time when implementing S200 raw material mixing is 3 minutes, 4 minutes, 6 minutes, 7 minutes, and 8 minutes, respectively.

[0082] Examples 13-15

[0083] Compared with Example 1, most of them are the same, except that the heating rates used in Examples 13-15 when implementing the S300 heating reaction are 3°C, 4°C, and 6°C per minute, respectively.

[0084] Examples 16-18

[0085] Compared with Example 1, most of them are the same, except that the heating temperatures used in Examples 16-18 when implementing the S300 heating reaction are 210°C, 220°C, and 230°C, respectively.

[0086] Examples 19-26

[0087] Compared with Example 1, most of them are the same, except that the temperature holding time used in Examples 19-26 when implementing the S300 temperature rising reaction is 10h, 12h, 14h, 16h, 18h, 20h, 22h, and 24h, respectively.

[0088] Comparative Example 1

[0089] The preparation method of Comparative Example 1 comprises the following steps:

[0090] S100, equipped with raw materials, based on volume molar concentration, equipped with 6.8mM / L high-purity sodium orthovanadate (NaVO 3 ) and 15 mM / L thioacetamide (TAA);

[0091] S200, mixing the raw materials, adding the prepared sodium orthovanadate and thioacetamide to 100 ml of pure water, stirring for 5 minutes to obtain a mixed solution;

[0092] S300, heating the reaction, quickly transferring the mixed solution into an autoclave, sealing and heating the autoclave, heating it to 200°C at a rate of 5°C per minute, and maintaining it at this temperature for 1 hour;

[0093] S400, cooling and separating, taking out the suspension in the autoclave, cooling it to room temperature, separating it by a centrifuge, washing it and drying it to obtain dry nanorings that can be used as negative electrode materials for lithium batteries.

[0094] Comparative Example 2

[0095] Compared with Example 1, most of the conditions are the same, except that in Comparative Example 2, the temperature was kept at 200° C. for 2 h.

[0096] Comparative Example 3

[0097] Compared with Example 1, most of the conditions are the same, except that in Comparative Example 3 the temperature was kept at 200° C. for 3 h.

[0098] Evaluation of Examples 1 to 3 and Comparative Examples 1 to 3:

[0099] In Examples 1 to 3 and Comparative Examples 1 to 3, the other conditions are the same, except that the temperature holding time is different. The main differences between Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 1:

[0100]

[0101] Table 1

[0102] The morphology evolution of the nanorings produced in the above Examples 1 to 3 and Comparative Examples 1 to 3 was experimentally studied by changing the hydrothermal reaction time, such as Figure 2 As shown in the figure, where a) <2h, b) 2h, c) 3h, d) 4h, e) 6h, f) 8h, the shape evolution of the VOx nanorings prepared in this way was studied. At the beginning of the synthesis process (<2h), nanoparticles with thick centers and diameters of 300-500nm were observed. As the reaction time increases, under etching conditions (<4h), the interior of the nanoparticles becomes thinner and forms holes. When the reaction is carried out for more than 4 hours, nanorings with an outer diameter of 300-500nm are formed and remain stable for a long time.

[0103] We also prepared Comparative Example 4, and the preparation method of Comparative Example 4 comprises the following steps:

[0104] S100, equipped with raw materials, based on volume molar concentration, equipped with 6.8mM / L high-purity sodium orthovanadate (NaVO 3 ) and 15 mM / L thioacetamide (TAA);

[0105] S200, mixing the raw materials, adding the prepared sodium orthovanadate and thioacetamide to 100 ml of pure water, stirring for 5 minutes to obtain a mixed solution;

[0106] S300, heating the reaction, quickly transferring the mixed solution into an autoclave, sealing and heating the autoclave, heating it to 160°C at a rate of 5°C per minute, and maintaining it at this temperature for 8h;

[0107] S400, cooling and separating, taking out the suspension in the autoclave, cooling it to room temperature, separating it by a centrifuge, washing it and drying it to obtain dry nanorings that can be used as negative electrode materials for lithium batteries.

[0108] Evaluation of Example 3, Example 4 and Comparative Example 4:

[0109] In Example 3, Example 4 and Comparative Example 4, the other conditions are the same, and the difference is that the heating temperatures are different. The main differences between Example 3, Example 4 and Comparative Example 4 are shown in Table 2:

[0110]

[0111] Table 2

[0112] The morphology of the nanorings produced in the above Example 3, Example 4 and Comparative Example 4 was experimentally studied. The experimental results show that the morphology is sensitive to temperature. Figure 3 As shown. (a) 160℃, (b) 180℃, (c) 200℃. Scale bar: 100nm. When the temperature is lower than 200℃, a flower-like structure is formed instead of a ring; when the temperature is lower than 200℃ and higher than 160℃, both structures exist, which is in a transitional stage.

[0113] Evaluation of Examples 5 to 8:

[0114] Evaluation of Examples 5 to 7:

[0115] In Examples 5 to 7, the other conditions are the same, except that the temperature holding time is different. The main differences between Examples 5 to 7 are shown in Table 3:

[0116]

[0117] Table 3

[0118] The following is a morphology study of the lithium ion battery negative electrode material prepared in Examples 5-8 of the present invention using VOx nanorings. The morphology of the etching-induced nanoparticles changes with the solution concentration as shown in FIG. Figure 4 When the solution is diluted, the effect on the morphology of nanodiscs is not significant, but it will affect the yield of nanorings, which is directly related to the reduction of raw materials.

[0119] Next, the VOx nanorings prepared in Example 1 are used as the negative electrode materials for lithium-ion batteries, and the electrochemical properties of the VOx nanoring structured lithium battery negative electrode materials are studied. -1 The cycle performance curve below can be referred to Figure 5 As shown, at 0.1A g -1 After 40 cycles of the battery under the current, the specific capacity is still maintained at 650mAh g -1 The above is nearly twice that of commercial graphite negative electrodes, and the coulombic efficiency is close to 100%.

[0120] In summary, using the preparation method of VOx nanorings for lithium-ion battery negative electrode materials, the prepared nanoring structure can remain stable for a long time, the size and morphology of the nanorings can be controlled, and the morphology can be regulated by reaction time, reaction temperature, reactant ratio, etc. The stable nanoring structure can buffer the stress changes caused by volume shrinkage / expansion during charging and discharging, thereby showing excellent charge and discharge cycle performance, with a coulombic efficiency close to 100%. After multiple cycles, the capacity remains at a high level, which is a very potential commercial carbon negative electrode alternative material. Therefore, the above embodiments achieve the purpose of the present invention.

[0121] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0122] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing VOx nanorings for lithium-ion battery negative electrode materials, characterized in that: The preparation method comprises the following steps: S100, preparing raw materials, in terms of volume molar concentration, preparing 0.01-6.8 mM / L sodium orthovanadate and 0.01-15 mM / L thioacetamide; S200, mixing the raw materials, adding the prepared sodium orthovanadate and thioacetamide to a unit volume of pure water, and stirring thoroughly for 3-8 minutes to obtain a mixed solution; S300, heating the reaction, quickly transferring the mixed solution to an autoclave, sealing and heating the autoclave, heating the temperature to 150-230° C. at a rate of 3-6° C. per minute, and maintaining the temperature for 3-24 hours to generate a suspension having a stable nano-ring structure; S400, cooling and separating, taking out the suspension in the autoclave, cooling it to room temperature, separating it by a centrifuge, washing it and drying it to obtain dry nanorings that can be used as negative electrode materials for lithium batteries.

2. The method for preparing a VOx nanoring for a negative electrode material of a lithium-ion battery according to claim 1, characterized in that: In the implementation process of preparing raw materials in step S100, 4-6.8 mM / L sodium orthovanadate and 8-15 mM / L thioacetamide are prepared in terms of volume molar concentration.

3. The method for preparing VOx nanorings for lithium-ion battery negative electrode materials according to claim 1, characterized in that: In the implementation process of preparing raw materials in step S200, a unit volume of pure water is 100 ml.

4. The method for preparing VOx nanorings for lithium-ion battery negative electrode materials according to claim 3, characterized in that: During the implementation of step S100 of preparing raw materials, the stirring time is 5 minutes.

5. The method for preparing VOx nanorings for lithium-ion battery negative electrode materials according to claim 1, characterized in that: During the implementation of the temperature-raising reaction in step S300 , the temperature is raised to 200° C. at a rate of 5° C. per minute and maintained at this temperature for 4 hours.

6. The method for preparing VOx nanorings for lithium-ion battery negative electrode materials according to claim 1, characterized in that: During the implementation of the temperature-raising reaction in step S300, the autoclave used is a stainless steel autoclave lined with polytetrafluoroethylene and having a volume of 130-1030 ml.

7. The method for preparing VOx nanorings for lithium-ion battery negative electrode materials according to claim 1, characterized in that: During the implementation of the temperature-raising reaction in step S300, in the generated suspension having a stable nano-ring structure, the outer diameter of the nano-ring structure is 300-500 nm, and the inner diameter is 200-400 nm.

8. A VOx nanoring for lithium-ion battery negative electrode material, characterized in that: The nanoring is prepared by the preparation method according to any one of claims 1 to 7.

9. The VOx nanoring for lithium-ion battery negative electrode material according to claim 8, characterized in that: The nano ring is a nano ring structure with an outer diameter of 300-500nm and an inner diameter of 200-400nm.

10. A negative electrode material for a lithium battery, characterized in that: The lithium battery negative electrode material uses the VOx nanoring for lithium ion battery negative electrode material according to claim 8 or 9.

11. A lithium battery, characterized in that: The lithium battery comprises the lithium battery negative electrode material as described in claim 10. During the process of assembling the lithium battery, the lithium battery negative electrode material is used as the negative electrode, polypropylene or polyethylene is used as the separator, and a mixed solution of ethylene carbonate and dimethyl carbonate in a volume ratio of 1:1 with a volume molar concentration of 1 mol / L LiPF6 is used as the electrolyte.

Images