WO2021104055A1

WO2021104055A1 - Nanomaterial and preparation method therefor, electrode, and secondary battery

Info

Publication number: WO2021104055A1
Application number: PCT/CN2020/128843
Authority: WO
Inventors: 唐永炳; 木赛男; 刘齐荣
Original assignee: 深圳先进技术研究院
Priority date: 2019-11-27
Filing date: 2020-11-13
Publication date: 2021-06-03
Also published as: CN111063870B; CN111063870A

Abstract

The present invention relates to the technical field of batteries, and in particular, to a nanomaterial and a preparation method therefor, an electrode, and a secondary battery. The preparation method provided in the present invention comprises: dissolving a metal precursor, a phosphorus source, and a nitrogen-containing organic matter in a solvent to prepare a mixed solution; carrying out heating reaction on the mixed solution to prepare a precursor; and calcining the precursor in an inert gas atmosphere to prepare a nitrogen-doped carbon-coated pyrophosphate material. A nitrogen-containing organic matter is used as a raw material for synthesizing a nitrogen-doped carbon-coated material, and a carbon source required for synthesis is introduced while a nitrogen source is introduced to promote synthesis of a nitrogen-doped carbon-coated pyrophosphate material having a core-shell structure. The problems of poor cycle stability, low rate performance, and low Coulombic efficiency caused by severe volume expansion and pulverization of an existing tin-based negative electrode material in a charging/discharging process are solved.

Description

纳米材料及其制备方法、电极和二次电池Nano material and its preparation method, electrode and secondary battery

技术领域Technical field

本发明属于电池技术领域，尤其涉及一种纳米材料及其制备方法、电极和二次电池。The invention belongs to the technical field of batteries, and in particular relates to a nano material and a preparation method thereof, an electrode and a secondary battery.

背景技术Background technique

由于锂离子电池广泛应用于智能手机、电动汽车等领域，锂的需求量逐年快速增长，而锂资源的储量有限且分布不均，导致成本逐渐增高，因而难以满足人们对储能器件低成本、高容量的需求。钠、钾元素与锂元素为同一主族的元素，具有相近的物理化学性质，元素储量丰富，成本低廉，且工作机理和锂离子电池相似，因此基于钠离子、钾离子等的新型二次离子电池的开发受到广泛关注，成为替代锂离子电池的潜在新型储能器件。然而，钠、钾离子电池虽然具有诸多的优点，但是其同时也存在一定的问题，例如钠、钾离子的半径（Na ⁺：1.02 Å；K ⁺：1.38 Å）较锂离子的半径（0.76Å）大了很多，这导致钠、钾离子在电解材料中的动力学性能迟缓。近年来的研究发现，选择合适的负极材料能够提高钠、钾离子等新型二次离子电池的循环稳定性、倍率性能、比容量等电化学性能，因而，筛选合适的负极材料对于解决钠、钾离子电池的动力学性能迟缓问题具有重要意义。 As lithium-ion batteries are widely used in smart phones, electric vehicles and other fields, the demand for lithium is growing rapidly year by year, and the limited and uneven distribution of lithium resources leads to gradual increase in costs, which makes it difficult to meet people’s low-cost and low-cost energy storage devices. High capacity demand. Sodium, potassium and lithium are elements of the same main group, with similar physical and chemical properties, abundant element reserves, low cost, and the working mechanism is similar to that of lithium ion batteries, so new secondary ions based on sodium ions, potassium ions, etc. The development of batteries has received widespread attention and has become a potential new energy storage device to replace lithium-ion batteries. However, although sodium and potassium ion batteries have many advantages, they also have certain problems. For example, the radius of sodium and potassium ions (Na ⁺ : 1.02 Å; K ⁺ : 1.38 Å) is compared with that of lithium ions (0.76 Å). ) Is much larger, which results in slower kinetic performance of sodium and potassium ions in electrolytic materials. Research in recent years has found that selecting suitable anode materials can improve the cycle stability, rate performance, specific capacity and other electrochemical properties of new secondary ion batteries such as sodium and potassium ions. Therefore, screening suitable anode materials is important for solving sodium and potassium. The slow kinetic performance of ion batteries is of great significance.

技术问题technical problem

传统的钠离子二次电池负极材料主要为碳材料、硅材料、磷材料以及金属氧化物、硫化物和锡基负极材料等，其中，碳材料的低电压平台容易导致钠枝晶的形成并引起严重的安全问题，且其理论容量较低，不能满足高能量密度和功率密度的要求；硅材料与磷材料的容量虽然高，但是其导电性较差，导致较差倍率性能；金属氧化物、硫化物、磷化物和锡基负极材料等虽然容量高并且导电性好，但是在充放电过程中存在着中间体的溶解以及体积膨胀的问题，容易造成电极粉化现象，从而导致循环性能差、倍率性能低和库伦效率低等问题。Traditional sodium ion secondary battery anode materials are mainly carbon materials, silicon materials, phosphorous materials, and metal oxides, sulfides and tin-based anode materials. Among them, the low voltage platform of carbon materials can easily lead to the formation of sodium dendrites and cause There are serious safety issues, and its theoretical capacity is low, which cannot meet the requirements of high energy density and power density; although the capacity of silicon materials and phosphorus materials is high, their conductivity is poor, resulting in poor rate performance; metal oxides, Although sulfides, phosphides and tin-based anode materials have high capacity and good electrical conductivity, there are problems with the dissolution of intermediates and volume expansion during the charging and discharging process, which easily cause electrode powdering, resulting in poor cycle performance, Problems such as low rate performance and low Coulomb efficiency.

现有技术中，尝试了多种用于改善锡化物负极材料体积膨胀和粉化的方法，一些实施例中，将石墨烯和金属阳离子前驱体加热溶解后于100℃-120℃下水热反应4-6小时以合成前驱体，洗涤、干燥后在氩氢气氛下400℃-550℃高温灼烧4-6小时，制得石墨烯纳米片上均匀生长有SnP ₂O ₇颗粒的终产物。另一些实施例中，采用可溶性淀粉和金属锡粉作为原料，采用微波水热法合成出SnP ₂O ₇/C微球，该微球内部弥散着大量的SnP ₂O ₇颗粒。其他的一些实施例中，以SnCl ₄·5H ₂O、C ₂H ₈O ₇P ₂（依替膦酸）、C ₁₂H ₂₂O ₁₁（蔗糖）为原料，采用溶胶-煅烧法，在600℃下煅烧10h合成碳包覆的SnP ₂O ₇。虽然上述方法合成的材料在一定的程度能够缓解锡的体积膨胀和粉化的现象，但是合成出的材料应用在电池中表现出较差的循环性能与倍率性能。 In the prior art, a variety of methods for improving the volume expansion and pulverization of tin compound anode materials have been tried. In some embodiments, graphene and metal cation precursors are heated and dissolved and then hydrothermally reacted at 100°C-120°C. 4 The precursor is synthesized for -6 hours, washed and dried, and then burned at a high temperature of 400°C-550°C under an argon hydrogen atmosphere for 4-6 hours to obtain a final product _{with SnP 2} O _{7 particles uniformly grown on the graphene nanosheets.} In other embodiments, soluble starch and metal tin powder are used as raw materials to synthesize SnP ₂ O ₇ /C microspheres by a microwave hydrothermal method, and a large number of SnP ₂ O ₇ particles are dispersed in the microspheres. In some other embodiments, SnCl ₄ ·5H ₂ O, C ₂ H ₈ O ₇ P ₂ (etidronic acid), and C ₁₂ H ₂₂ O ₁₁ (sucrose) are used as raw materials, and the sol-calcination method is used at 600 _{The carbon-coated SnP 2} O _{7 was} synthesized by calcining at ℃ for 10 hours. Although the materials synthesized by the above methods can alleviate the volume expansion and pulverization of tin to a certain extent, the synthesized materials exhibit poor cycle performance and rate performance when used in batteries.

技术解决方案Technical solutions

本发明的主要目的在于提供一种纳米材料的制备方法，旨在解决现有锡基负极材料在充放电过程中由于严重的体积膨胀及粉化导致的循环稳定性差、倍率性能低、库伦效率低的问题。The main purpose of the present invention is to provide a method for preparing nanomaterials, which aims to solve the poor cycle stability, low rate performance, and low coulombic efficiency of the existing tin-based anode materials due to severe volume expansion and pulverization during charging and discharging. The problem.

本发明的另一目的在于提供一种由上述制备方法制得的纳米材料。Another object of the present invention is to provide a nanomaterial prepared by the above preparation method.

本发明的又一目的在于提供利用了上述纳米材料的电极和二次电极。Another object of the present invention is to provide an electrode and a secondary electrode using the above-mentioned nano material.

为实现上述发明目的，本发明采用的技术方案如下：In order to achieve the above-mentioned purpose of the invention, the technical solutions adopted by the present invention are as follows:

一方面，本发明提供了一种纳米材料的制备方法，包括以下步骤：In one aspect, the present invention provides a method for preparing nanomaterials, including the following steps:

将金属前驱体、磷源和含氮有机物溶解在溶剂中，制备混合液；Dissolving the metal precursor, phosphorus source and nitrogen-containing organic matter in a solvent to prepare a mixed solution;

将所述混合液进行加热反应，制备前驱体；Subjecting the mixed liquid to a heating reaction to prepare a precursor;

将所述前驱体在惰性气体气氛下进行煅烧处理，制备氮掺杂碳包覆的焦磷酸盐材料。The precursor is calcined in an inert gas atmosphere to prepare a nitrogen-doped carbon-coated pyrophosphate material.

有益效果Beneficial effect

本发明提供的纳米材料的制备方法，采用含氮有机物作为合成氮掺杂碳包覆材料的原料，在引入氮源的同时也引入了合成所需的碳源，促进合成具有核壳结构的氮掺杂碳包覆的焦磷酸盐材料，原料来源广泛且无毒，减少了合成成本；然后，通过依次进行加热反应和煅烧处理，从而制得具有核壳结构的氮掺杂碳包覆的焦磷酸盐材料，方法简单可控，适用于氮掺杂碳包覆的焦磷酸盐材料的规模化制备。本发明通过采用氮掺杂碳材料包覆焦磷酸盐的方法，一方面，使得焦磷酸盐颗粒被包覆并固定在氮掺杂碳材料基体上，使其在充放电过程中可以有效缓解合金化的体积膨胀基粉化导致的循环稳定性差、倍率性能低、库伦效率低的问题；另一方面，由于引入了氮元素，有利于增强材料的电子的传输动力学性能，提高电池的比容量性能；又一方面，焦磷酸盐为一种纳米尺度的球状化合物，能够极大地缩短离子的传输路径，同时，具有独特的三维立体结构，在反应中能够提供快捷的电子通道，提高反应的效率，使得尤其制得的钠、钾、钙离子等二次电池具有优异的电化学性能。The method for preparing nanomaterials provided by the present invention uses nitrogen-containing organic matter as the raw material for synthesizing nitrogen-doped carbon coating materials, and introduces the carbon source required for synthesis while introducing the nitrogen source to promote the synthesis of nitrogen with a core-shell structure. The carbon-doped pyrophosphate material has a wide range of raw materials and is non-toxic, which reduces the synthesis cost; then, the heating reaction and the calcination are carried out in sequence to obtain a nitrogen-doped carbon-coated coke with a core-shell structure. The phosphate material has a simple and controllable method and is suitable for the large-scale preparation of nitrogen-doped carbon-coated pyrophosphate materials. The present invention adopts the method of coating pyrophosphate with nitrogen-doped carbon material. On the one hand, the pyrophosphate particles are coated and fixed on the matrix of nitrogen-doped carbon material, so that it can effectively relieve the alloy during charging and discharging. The problem of poor cycle stability, low rate performance, and low Coulomb efficiency caused by pulverization of the volume expansion of the chemical; on the other hand, due to the introduction of nitrogen, it is beneficial to enhance the electron transport kinetic performance of the material and increase the specific capacity of the battery. Performance; On the other hand, pyrophosphate is a nano-scale spherical compound that can greatly shorten the ion transmission path. At the same time, it has a unique three-dimensional structure, which can provide fast electron channels in the reaction and improve the efficiency of the reaction. , So that the prepared sodium, potassium, calcium ion and other secondary batteries have excellent electrochemical performance.

相应的，一种纳米材料，包括：由上述制备方法制得的氮掺杂碳包覆的焦磷酸盐材料。Correspondingly, a nano material includes: the nitrogen-doped carbon-coated pyrophosphate material prepared by the above-mentioned preparation method.

本发明提供的纳米材料，由上述制备方法制得，以焦磷酸盐为核以氮掺杂碳材料为壳层，解决了现有负极材料在充放电过程中由于严重的体积膨胀及粉化导致的循环稳定性差、倍率性能低、库伦效率低的问题，可作为负极材料应用于制备钠、钾、钙离子等二次电池，以提高电池的电化学性能。The nano material provided by the present invention is prepared by the above-mentioned preparation method, with pyrophosphate as the core and nitrogen-doped carbon material as the shell layer, which solves the problem of severe volume expansion and pulverization caused by the existing negative electrode materials during charging and discharging. It has the problems of poor cycle stability, low rate performance, and low Coulomb efficiency. It can be used as a negative electrode material to prepare secondary batteries such as sodium, potassium, and calcium ions to improve the electrochemical performance of the battery.

相应的，一种负极，所述负极的材料包括：由前述制备方法制得的纳米材料，或上述纳米材料。Correspondingly, a negative electrode, the material of the negative electrode includes: the nano material prepared by the aforementioned preparation method, or the aforementioned nano material.

本发明提供的负极，其材料为由前述制备方法制得的纳米材料或上述纳米材料，可有效解决现有负极材料在充放电过程中由于严重的体积膨胀及粉化导致的循环稳定性差、倍率性能低、库伦效率低的问题，可应用于制备钠、钾、钙离子等二次电池，以提高电池的电化学性能。The negative electrode provided by the present invention, whose material is the nano material prepared by the aforementioned preparation method or the aforementioned nano material, can effectively solve the poor cycle stability and rate of the existing negative electrode material due to the serious volume expansion and powdering during the charge and discharge process. The problems of low performance and low coulombic efficiency can be applied to the preparation of secondary batteries such as sodium, potassium, and calcium ions to improve the electrochemical performance of the battery.

相应的，一种二次电池，所述二次电池的负极为上述负极。Correspondingly, in a secondary battery, the negative electrode of the secondary battery is the above-mentioned negative electrode.

本发明提供的二次电池，其负极为上述负极，具有优异的电化学性能，例如高倍率性能以及高比容量性能等。In the secondary battery provided by the present invention, the negative electrode is the above-mentioned negative electrode and has excellent electrochemical performance, such as high rate performance and high specific capacity performance.

附图说明Description of the drawings

图1为实施例1制得的SnP ₂O ₇@N-C的X射线衍射图（XRD）； Figure 1 is an X-ray diffraction pattern (XRD) _{of SnP 2} O ₇ @NC prepared in Example 1;

图2为实施例1制得的SnP ₂O ₇@N-C的扫描电子显微镜图（SEM）； 2 is a scanning electron microscope image (SEM) _{of SnP 2} O ₇ @NC prepared in Example 1;

图3为实施例1制得的SnP ₂O ₇@N-C的透射电镜图（TEM）； Fig. 3 is a transmission electron microscope image (TEM) _{of SnP 2} O _{7 @NC prepared in Example 1;}

图4为实施例1制得的SnP ₂O ₇@N-C的X射线能谱图（EDS）； Figure 4 is an X-ray energy spectrum (EDS) _{of SnP 2} O ₇ @NC prepared in Example 1;

图5为对比例1制得的SnP ₂O ₇@N-C与实施例1制得的SnP ₂O ₇@N-C作为负极材料的钠离子半电池在1.5A g-1电流密度条件下的长循环性能检测结果； FIG 5 is a Comparative Example 1 was SnP ₂ O ₇ @NC Example 1 was SnP ₂ O ₇ @NC sodium ion as a negative electrode material of long circulation half cell performance at a current density of 1.5A g-1 conditions Test results;

图6为实施例2制得的产物与实施例1制得的SnP ₂O ₇@N-C作为负极材料的钠离子半电池在1.5A g ^-1电流密度条件下的长循环性能检测结果； 6 shows the long-cycle performance test results of the product prepared in Example 2 and the sodium ion half-cell _{with SnP 2} O ₇ ^{@NC prepared in Example 1 as the negative electrode material under the current density of 1.5A g -1;}

图7为实施例3制得的产物与实施例1制得的SnP ₂O ₇@N-C作为负极材料的钠离子半电池在1.5A g ^-1电流密度条件下的长循环性能检测结果。 FIG. 7 shows the long-cycle performance test results of the product prepared in Example 3 and the sodium ion half-cell _{using SnP 2} O ₇ ^{@NC as the negative electrode material prepared in Example 1 under the current density of 1.5A g -1.}

本发明的实施方式Embodiments of the present invention

为了使本发明要解决的技术问题、技术方案及有益效果更加清楚明白，以下结合实施例，对本发明进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。In order to make the technical problems, technical solutions, and beneficial effects to be solved by the present invention clearer and more comprehensible, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, but not used to limit the present invention.

一种纳米材料的制备方法，包括以下步骤：A method for preparing nanomaterials includes the following steps:

S01、将金属前驱体、磷源和含氮有机物溶解在溶剂中，制备混合液；S01. Dissolving the metal precursor, the phosphorus source and the nitrogen-containing organic matter in a solvent to prepare a mixed solution;

S02、将所述混合液进行加热反应，制备前驱体；S02, subjecting the mixed liquid to a heating reaction to prepare a precursor;

S03、将所述前驱体在惰性气体气氛下进行煅烧处理，制备氮掺杂碳包覆的焦磷酸盐材料。S03, calcining the precursor in an inert gas atmosphere to prepare a nitrogen-doped carbon-coated pyrophosphate material.

具体地，步骤S01中，将金属前驱体、磷源和含氮有机物溶解在溶剂中，制备混合液。其中，以金属前驱体和磷源作为合成焦磷酸盐（例如SnP ₂O ₇）的原料，以含氮有机物作为合成氮掺杂碳包覆材料的原料，将金属前驱体、磷源和含氮有机物溶解在溶剂中，以构建后续合成氮掺杂碳包覆的焦磷酸盐材料的反应体系。 Specifically, in step S01, the metal precursor, the phosphorus source, and the nitrogen-containing organic matter are dissolved in a solvent to prepare a mixed solution. Among them, metal precursors and phosphorus sources are used as _{raw materials for synthesizing pyrophosphate (such as SnP 2} O ₇ ), nitrogen-containing organics are used as raw materials for synthesizing nitrogen-doped carbon coating materials, and the metal precursor, phosphorus source and nitrogen-containing The organic matter is dissolved in the solvent to construct a reaction system for the subsequent synthesis of the nitrogen-doped carbon-coated pyrophosphate material.

所述磷源含磷原子，通过反应提供焦磷酸根。作为一种实施方式，所述磷源选自植酸、磷酸、磷酸二氢氨、甲基膦酸和多磷酸中的至少一种，这些磷源溶解性好，且配位能力强。在一些实施例中，所述磷源选自植酸，植酸反应速度快，配位能力较强、价格比较低廉，与此同时，所述植酸既含有磷原子也含有碳原子，可为反应同时提供碳源和磷源，为反应补充足量的碳源，以促进氮掺杂碳包覆的焦磷酸盐材料的合成。The phosphorus source contains phosphorus atoms and provides pyrophosphate through reaction. As an embodiment, the phosphorus source is selected from at least one of phytic acid, phosphoric acid, ammonium dihydrogen phosphate, methylphosphonic acid, and polyphosphoric acid. These phosphorus sources have good solubility and strong coordination ability. In some embodiments, the phosphorus source is selected from phytic acid, which has a fast reaction speed, a strong coordination ability, and a relatively low price. At the same time, the phytic acid contains both phosphorus atoms and carbon atoms, which can be The reaction provides a carbon source and a phosphorus source at the same time to supplement the reaction with a sufficient amount of carbon source to promote the synthesis of nitrogen-doped carbon-coated pyrophosphate materials.

所述金属前驱体用于提供金属原子，通过反应与焦磷酸根结合形成焦磷酸盐。作为一种实施方式，所述金属前驱体选自锡源、铅源、钡源、钙源、锌源、钴源、铋源中的至少一种。在一些实施例中，所述金属前驱体选为锡源，优选为氯化亚锡、氯化锡、硫酸亚锡、硫酸锡和硝酸亚锡中的至少一种，这些锡源在水中的溶解性比较好。在进一步实施例中，所述金属前驱体选为氯化亚锡，氯化亚锡能够迅速的溶解在水中并与磷源发生反应，促进焦磷酸锡的合成。The metal precursor is used to provide metal atoms, which combine with pyrophosphate through a reaction to form pyrophosphate. As an embodiment, the metal precursor is selected from at least one of a tin source, a lead source, a barium source, a calcium source, a zinc source, a cobalt source, and a bismuth source. In some embodiments, the metal precursor is selected as a tin source, preferably at least one of stannous chloride, tin chloride, stannous sulfate, tin sulfate, and stannous nitrate. The dissolution of these tin sources in water Sex is better. In a further embodiment, the metal precursor is selected as stannous chloride, which can quickly dissolve in water and react with the phosphorus source to promote the synthesis of tin pyrophosphate.

所述含氮有机物指的是含有氮元素的有机物，分子中含有氮原子的同时也含有碳原子，可同时为反应提供碳源和氮源，为合成氮掺杂碳包覆材料的来源，促进合成氮掺杂碳包覆的焦磷酸盐材料。作为一种实施方式，所述含氮有机物选自尿素、三聚氰胺、缩二脲、乙二胺四乙酸和六亚甲基四胺中的至少一种，这些含氮有机物与植酸之间具有良好的反应活性。在一些实施例中，所述含氮有机物选为三聚氰胺，三聚氰胺的氮含量比较高，而且价格低廉。The nitrogen-containing organic matter refers to the organic matter containing nitrogen element. The molecule contains nitrogen atoms and carbon atoms at the same time, which can provide carbon source and nitrogen source for the reaction at the same time, and is a source of synthesis of nitrogen-doped carbon-coated materials and promotes Synthesis of nitrogen-doped carbon-coated pyrophosphate material. As an embodiment, the nitrogen-containing organic matter is selected from at least one of urea, melamine, biuret, ethylenediaminetetraacetic acid and hexamethylenetetramine, and these nitrogen-containing organic matter have a good relationship with phytic acid. The reactivity. In some embodiments, the nitrogen-containing organic substance is selected as melamine, which has a relatively high nitrogen content and is inexpensive.

不同于现有引入碳源制备碳材料包覆的焦磷酸盐的技术，本发明实施例采用含氮有机物作为合成氮掺杂碳包覆材料的原料，使得在引入氮源的同时也引入了合成所需的碳源，促进合成具有核壳结构的氮掺杂碳包覆的焦磷酸盐材料，原料来源广泛且无毒，减少了合成成本；与此同时，由于引入了氮元素，进一步提升了材料的电子的传输动力学性能。Different from the existing technology of introducing carbon source to prepare carbon material-coated pyrophosphate, the embodiment of the present invention uses nitrogen-containing organic matter as the raw material for synthesizing nitrogen-doped carbon-coated material, so that the synthesis of nitrogen source is also introduced at the same time. The required carbon source promotes the synthesis of nitrogen-doped carbon-coated pyrophosphate materials with a core-shell structure. The raw material sources are extensive and non-toxic, reducing the synthesis cost; at the same time, due to the introduction of nitrogen, it further improves The electron transport dynamics of the material.

所述溶液作为反应体积的反应介质，选用为能够充分溶解分散金属前驱体、磷源和含氮有机物且不影响反应的水或水-有机溶剂体系。在一些实施例中，所述溶剂选为去离子水和乙醇等体积混合形成的混合物。As the reaction medium of the reaction volume, the solution is selected as water or a water-organic solvent system that can fully dissolve and disperse the metal precursor, the phosphorus source and the nitrogen-containing organic matter without affecting the reaction. In some embodiments, the solvent is selected as a mixture formed by mixing equal volumes of deionized water and ethanol.

作为一种实施方式，将金属前驱体、磷源和含氮有机物溶解在溶剂的步骤中，将金属前驱体、磷源和含氮有机物加入去离子水中，并在40-95℃下搅拌1-8小时，使得金属前驱体、磷源和含氮有机物完全溶解。As an embodiment, in the step of dissolving the metal precursor, the phosphorus source and the nitrogen-containing organic matter in a solvent, the metal precursor, the phosphorus source and the nitrogen-containing organic matter are added to deionized water and stirred at 40-95°C. In 8 hours, the metal precursor, phosphorus source and nitrogen-containing organic matter were completely dissolved.

所述混合液中，金属前驱体、磷源和含氮有机物的用量及其浓度影响着后续氮掺杂碳包覆的焦磷酸盐材料的合成。In the mixed solution, the amount and concentration of the metal precursor, the phosphorus source, and the nitrogen-containing organic matter affect the subsequent synthesis of the nitrogen-doped carbon-coated pyrophosphate material.

所述金属前驱体和所述磷源的用量符合其合成相应的焦磷酸盐的化学剂量比即可。作为一种实施方式，所述磷源与所述金属前驱体的摩尔比为1 : (0.5-10)，以确保合成高纯度的焦磷酸锡。在一些实施例中，所述磷源选自植酸、磷酸、磷酸二氢氨、甲基膦酸和多磷酸中的至少一种，所述金属前驱体选为锡源。在进一步实施例中，所述磷源选自植酸，所述金属前驱体选自氯化亚锡的二水合物，且所述植酸和所述氯化亚锡的二水合物的摩尔比为2:10，此时制得的氮掺杂碳包覆的焦磷酸锡在具有核壳结构的同时循环性能和倍率性能优异，分散度高，材料致密。The amount of the metal precursor and the phosphorus source may be in accordance with the stoichiometric ratio of the corresponding pyrophosphate in the synthesis. As an embodiment, the molar ratio of the phosphorus source to the metal precursor is 1: (0.5-10) to ensure the synthesis of high-purity tin pyrophosphate. In some embodiments, the phosphorus source is selected from at least one of phytic acid, phosphoric acid, ammonium dihydrogen phosphate, methylphosphonic acid, and polyphosphoric acid, and the metal precursor is selected as a tin source. In a further embodiment, the phosphorus source is selected from phytic acid, the metal precursor is selected from stannous chloride dihydrate, and the molar ratio of the phytic acid to the stannous chloride dihydrate The ratio is 2:10. The nitrogen-doped carbon-coated tin pyrophosphate prepared at this time has a core-shell structure and has excellent cycle performance and rate performance, high dispersion, and compact material.

所述含氮有机物的用量应能满足合成氮掺杂碳包覆的焦磷酸盐材料的基本需求即可，作为一种实施方式，所述含氮有机物与所述金属前驱体的摩尔比为(0.1-2) : 1，确保合成具有核壳结构的氮掺杂碳包覆的焦磷酸锡材料。在一些实施例中，所述含氮有机物选自尿素、三聚氰胺、缩二脲、乙二胺四乙酸和六亚甲基四胺中的至少一种，所述金属前驱体选为锡源。在进一步实施例中，所述含氮有机物选为三聚氰胺，所述金属前驱体选自氯化亚锡的二水合物，且所述氯化亚锡的二水合物和所述三聚氰胺的摩尔比为10:8，此时制得的氮掺杂碳包覆的焦磷酸锡在具有核壳结构的同时电化学性能最优。在更进一步的实施例中，所述混合液中所述含氮有机物的浓度为0.05-1mol/L。The amount of the nitrogen-containing organic matter should meet the basic requirements for synthesizing nitrogen-doped carbon-coated pyrophosphate materials. As an embodiment, the molar ratio of the nitrogen-containing organic matter to the metal precursor is ( 0.1-2): 1. Ensure the synthesis of nitrogen-doped carbon-coated tin pyrophosphate material with a core-shell structure. In some embodiments, the nitrogen-containing organic substance is selected from at least one of urea, melamine, biuret, ethylenediaminetetraacetic acid, and hexamethylenetetramine, and the metal precursor is selected as a tin source. In a further embodiment, the nitrogen-containing organic substance is selected from melamine, the metal precursor is selected from stannous chloride dihydrate, and the molar ratio of the stannous chloride dihydrate to the melamine is At 10:8, the prepared nitrogen-doped carbon-coated tin pyrophosphate has the best electrochemical performance while having a core-shell structure. In a further embodiment, the concentration of the nitrogen-containing organic matter in the mixed solution is 0.05-1 mol/L.

进一步地，由上述限定的用量及其浓度的金属前驱体、磷源和含氮有机物合成的氮掺杂碳包覆的焦磷酸盐材料中，碳的重量百分比含量为5%-60％，氮的重量百分比含量为2%-30％。通过在碳材料包覆的焦磷酸盐中掺杂2%-30％的氮源，可明显提高材料的导电性，引入活性位点，进而明显增加材料的比电容量。Further, in the nitrogen-doped carbon-coated pyrophosphate material synthesized from the metal precursor, phosphorus source and nitrogen-containing organic matter in the above-defined amount and concentration, the weight percentage of carbon is 5%-60%, and nitrogen The weight percentage content is 2%-30%. By doping 2%-30% nitrogen source in the carbon material-coated pyrophosphate, the conductivity of the material can be obviously improved, the active sites are introduced, and the specific capacitance of the material is obviously increased.

步骤S02中，将所述混合液进行加热反应，制备前驱体。In step S02, the mixed liquid is subjected to a heating reaction to prepare a precursor.

通过将所述混合液进行加热反应，使得金属前驱体、磷源和含氮有机物能够在溶剂中进行初步反应，以制备前驱体。本发明实施例在反应起始阶段即加入含氮有机物与金属前驱体、磷源混合反应，为反应引入了碱性基团，以促进具有核壳结构的碳材料包覆焦磷酸盐材料的合成。作为示例，磷源选为植酸，含氮有机物选为三聚氰胺，金属前驱体选为氯化亚锡，在进行加热反应的过程中，植酸提供的部分焦磷酸根与氯化亚锡反应生成焦磷酸锡，部分分布在焦磷酸锡表面的焦磷酸根与三聚氰胺的碱性基团结合形成焦磷酸铵壳层材料，通过后续煅烧处理，从而制得氮掺杂碳包覆的焦磷酸锡材料。By subjecting the mixed solution to a heating reaction, the metal precursor, the phosphorus source, and the nitrogen-containing organic matter can undergo a preliminary reaction in the solvent to prepare the precursor. In the embodiment of the present invention, at the initial stage of the reaction, a nitrogen-containing organic substance, a metal precursor, and a phosphorus source are mixed and reacted, and a basic group is introduced for the reaction to promote the synthesis of the carbon material-coated pyrophosphate material with a core-shell structure . As an example, the phosphorus source is phytic acid, the nitrogen-containing organics is melamine, and the metal precursor is stannous chloride. During the heating reaction, part of the pyrophosphate provided by phytic acid reacts with stannous chloride to form Tin pyrophosphate, part of the pyrophosphate distributed on the surface of the tin pyrophosphate combines with the basic groups of melamine to form an ammonium pyrophosphate shell material, which is then calcined to obtain a nitrogen-doped carbon-coated tin pyrophosphate material .

作为一种实施方式，将所述混合液进行加热处理的步骤中，将所述混合液在70℃-95℃下加热回流8-20小时，通过加热回流可确保反应能够充分地进行，在70℃-95℃下反应，可促进焦磷酸锡核的合成以及形成焦磷酸铵壳层材料。在具体的实施例中，所述加热回流的温度为70℃、78℃、83℃、90℃、95℃，所述加热回流的时间为8、9、10、11、12、13、14、15、16、17、18、19、20小时。As an embodiment, in the step of heating the mixed solution, the mixed solution is heated to reflux at 70°C-95°C for 8-20 hours, and the reaction can be fully carried out by heating and refluxing at 70°C to 95°C. Reaction at ℃-95℃ can promote the synthesis of tin pyrophosphate core and the formation of ammonium pyrophosphate shell material. In a specific embodiment, the temperature of the heating and refluxing is 70°C, 78°C, 83°C, 90°C, and 95°C, and the time of the heating and refluxing is 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 hours.

作为一种实施方式，将所述混合液进行加热处理后，静置使得反应制得的前驱体充分沉淀，然后将所述前驱体进行洗涤，然后于真空环境下以40℃-95℃的温度干燥1-20小时，以获得高纯度且干燥的前驱体。As an embodiment, after the mixed solution is heated, it is allowed to stand to fully precipitate the precursor prepared by the reaction, and then the precursor is washed, and then heated at a temperature of 40°C to 95°C in a vacuum environment. Dry for 1-20 hours to obtain a high-purity and dry precursor.

步骤S03中，将所述前驱体在惰性气体气氛下进行煅烧处理，通过煅烧处理，可使得前驱体进一步反应合成氮掺杂碳包覆的焦磷酸盐材料。In step S03, the precursor is calcined under an inert gas atmosphere. Through the calcining process, the precursor can be further reacted to synthesize a nitrogen-doped carbon-coated pyrophosphate material.

由此，制得的氮掺杂碳包覆的焦磷酸盐材料，以焦磷酸盐为核以氮掺杂碳材料为壳层，通过采用氮掺杂碳材料包覆焦磷酸盐，一方面，使得焦磷酸盐颗粒被包覆固定在氮掺杂碳材料基体上，使其在充放电过程中可以有效缓解合金化的体积膨胀基粉化导致的循环稳定性差、倍率性能低、库伦效率低的问题；另一方面，由于引入了氮元素，有利于增强材料的电子的传输动力学性能，提高电池的比容量性能；又一方面，焦磷酸盐为一种纳米尺度的球状化合物，能够极大地缩短离子的传输路径，提高反应的效率，同时，具有独特的三维立体结构，在反应中能够提供快捷的电子通道，使得尤其制得的钠、钾、钙离子等二次电池具有优异的电化学性能。Thus, the prepared nitrogen-doped carbon-coated pyrophosphate material has pyrophosphate as the core and nitrogen-doped carbon material as the shell layer, and the pyrophosphate is coated with the nitrogen-doped carbon material. On the one hand, The pyrophosphate particles are coated and fixed on the nitrogen-doped carbon material matrix, so that it can effectively alleviate the poor cycle stability, low rate performance, and low coulomb efficiency caused by the alloying volume expansion base powder during the charging and discharging process. The problem; on the other hand, due to the introduction of nitrogen, it is beneficial to enhance the electron transport dynamics of the material and improve the specific capacity performance of the battery; on the other hand, pyrophosphate is a nano-scale spherical compound that can greatly Shorten the transmission path of ions and improve the efficiency of the reaction. At the same time, it has a unique three-dimensional structure, which can provide fast electronic channels in the reaction, so that the prepared sodium, potassium, calcium ion and other secondary batteries have excellent electrochemistry. performance.

在惰性气体气氛下进行煅烧处理，以防止环境中的空气对目标产物的合成存在影响。所述惰性气体气氛包括但不限于氮气、氦气、氩气等，在一些实施例中，所述惰性气体气氛为氩气气氛。The calcination process is carried out in an inert gas atmosphere to prevent the air in the environment from affecting the synthesis of the target product. The inert gas atmosphere includes but is not limited to nitrogen, helium, argon, etc. In some embodiments, the inert gas atmosphere is an argon atmosphere.

作为一种实施方式，将所述前驱体在惰性气体气氛下进行煅烧处理，将所述前驱体在惰性气体气氛下于500℃-800℃高温煅烧1-5小时，确保焦磷酸铵壳层材料能够被充分碳化，且有利于氮的掺杂，进而形成以焦磷酸盐为核以氮掺杂碳材料为壳层的材料。在具体的实施例中，所述煅烧温度为500℃、550℃、600℃、640℃、701℃、765℃、800℃，所述煅烧时间为1、2、3、4、5小时。As an embodiment, the precursor is calcined in an inert gas atmosphere, and the precursor is calcined in an inert gas atmosphere at a high temperature of 500°C-800°C for 1-5 hours to ensure the ammonium pyrophosphate shell material It can be fully carbonized and is beneficial to nitrogen doping to form a material with pyrophosphate as the core and nitrogen-doped carbon material as the shell. In a specific embodiment, the calcination temperature is 500°C, 550°C, 600°C, 640°C, 701°C, 765°C, 800°C, and the calcination time is 1, 2, 3, 4, and 5 hours.

经检测，通过上述制备方法制得的氮掺杂碳包覆的焦磷酸盐材料在材料体系中分布均一，且具有纳米尺度的球状结构，其粒径为50-500nm，如此，极大地缩短离子的传输路径，提高反应的效率。After testing, the nitrogen-doped carbon-coated pyrophosphate material prepared by the above preparation method is uniformly distributed in the material system and has a nano-scale spherical structure with a particle size of 50-500nm. This greatly shortens the ion The transmission path improves the efficiency of the reaction.

与现有技术进行对比，本发明实施例提供的制备方法具有以下优点：Compared with the prior art, the preparation method provided by the embodiment of the present invention has the following advantages:

1）采用含氮有机物作为合成氮掺杂碳包覆材料的原料，使得在引入氮源的同时也引入了合成所需的碳源，增强了材料的电荷传输性能，且原料来源广泛且无毒，减少了合成成本；1) Nitrogen-containing organics are used as the raw material for the synthesis of nitrogen-doped carbon coating materials, so that the carbon source required for synthesis is introduced at the same time as the nitrogen source is introduced, which enhances the charge transport performance of the material, and the source of raw materials is wide and non-toxic , Reducing the synthesis cost;

2）在反应起始阶段即加入含氮有机物与金属前驱体、磷源混合反应，例如三聚氰胺为反应引入了碱性基团，促进了具有核壳结构的碳材料包覆焦磷酸盐材料的合成；2) In the initial stage of the reaction, add nitrogen-containing organics, metal precursors, and phosphorus sources to mix and react. For example, melamine introduces basic groups for the reaction, which promotes the synthesis of core-shell carbon materials coated with pyrophosphate materials ；

3）将金属前驱体、磷源和含氮有机物溶解在溶剂中，依次进行加热反应和煅烧处理，即可制得具有核壳结构的氮掺杂碳包覆的焦磷酸盐材料，方法简单可控，适用于氮掺杂碳包覆的焦磷酸盐材料的规模化制备；3) Dissolve the metal precursor, the phosphorus source and the nitrogen-containing organic matter in the solvent, and then carry out the heating reaction and the calcination treatment in sequence to obtain the nitrogen-doped carbon-coated pyrophosphate material with a core-shell structure. The method is simple and can be It is suitable for the large-scale preparation of nitrogen-doped carbon-coated pyrophosphate materials;

4）采用氮掺杂碳材料包覆的方法，提高材料的导电性，而且碳材料包覆的焦磷酸盐在充放电过程可以有效缓解合金化的体积膨胀问题，进而能够改善材料倍率性能、循环稳定性差的问题；4) The method of coating with nitrogen-doped carbon material improves the conductivity of the material, and the pyrophosphate coated with carbon material can effectively alleviate the volume expansion problem of alloying during the charging and discharging process, thereby improving the rate performance and cycle of the material The problem of poor stability;

5）合成的氮掺杂碳包覆的焦磷酸盐材料颗粒分布比较均一，确保材料不会由于局部反应而导致坍塌，进而影响材料的循环性能以及倍率性能；5) The particle distribution of the synthesized nitrogen-doped carbon-coated pyrophosphate material is relatively uniform, ensuring that the material will not collapse due to local reactions, which will affect the cycle performance and rate performance of the material;

6）合成的氮掺杂碳包覆的焦磷酸盐材料在充放电过程中通过转化反应以及合金化反应的过程，有效地发挥焦磷酸盐的潜能，呈现出较高的比容量。6) The synthesized nitrogen-doped carbon-coated pyrophosphate material effectively exerts the potential of pyrophosphate through the conversion reaction and alloying reaction during the charge and discharge process, and exhibits a higher specific capacity.

本发明实施例提供的纳米材料，由上述制备方法制得，以焦磷酸盐为核以氮掺杂碳材料为壳层，解决了现有负极材料在充放电过程中由于严重的体积膨胀及粉化导致的循环稳定性差、倍率性能低、库伦效率低的问题，可作为负极材料应用于制备钠、钾、钙离子等二次电池，以提高电池的电化学性能。The nano material provided by the embodiment of the present invention is prepared by the above-mentioned preparation method, with pyrophosphate as the core and nitrogen-doped carbon material as the shell layer, which solves the problem of severe volume expansion and powdery effects of the existing negative electrode materials during the charge and discharge process. The problems of poor cycle stability, low rate performance, and low coulombic efficiency caused by chemical reaction can be used as a negative electrode material to prepare secondary batteries such as sodium, potassium, and calcium ions to improve the electrochemical performance of the battery.

作为一种实施方式，所述氮掺杂碳包覆的焦磷酸盐材料中，碳的重量百分比含量为5%-60％，氮的重量百分比含量为2%-30％。As an embodiment, in the nitrogen-doped carbon-coated pyrophosphate material, the weight percentage of carbon is 5%-60%, and the weight percentage of nitrogen is 2%-30%.

作为一种实施方式，所述氮掺杂碳包覆的焦磷酸盐材料的粒径为5-500nm，在该尺寸范围下的氮掺杂碳包覆的焦磷酸盐材料，能够极大地缩短离子的传输路径，提高反应的效率，同时也减缓在充放电过程中体积膨胀所导致的循环性能以及倍率性能差的问题。As an embodiment, the particle size of the nitrogen-doped carbon-coated pyrophosphate material is 5-500nm, and the nitrogen-doped carbon-coated pyrophosphate material in this size range can greatly shorten the ion The transmission path improves the efficiency of the reaction, and at the same time alleviates the problem of poor cycle performance and poor rate performance caused by volume expansion during charging and discharging.

基于上述所记载的技术方案，本发明实施例提供给了一种负极和二次电池。Based on the technical solutions described above, the embodiments of the present invention provide a negative electrode and a secondary battery.

本发明实施例提供的负极，其材料为由前述制备方法制得的纳米材料或上述纳米材料，可有效解决现有负极材料在充放电过程中由于严重的体积膨胀及粉化导致的循环稳定性差、倍率性能低、库伦效率低的问题，可应用于制备钠、钾、钙离子等二次电池，以提高电池的电化学性能。The negative electrode provided by the embodiment of the present invention is made of the nano material prepared by the aforementioned preparation method or the aforementioned nano material, which can effectively solve the poor cycle stability caused by the severe volume expansion and pulverization of the existing negative electrode material during the charge and discharge process. , The problems of low rate performance and low coulombic efficiency can be applied to the preparation of secondary batteries such as sodium, potassium, and calcium ions to improve the electrochemical performance of the battery.

现有的负极主要由集流体和涂覆所述集流体上方的材料层组成，在本发明实施例中，所述材料层由导电剂、粘结剂和上述氮掺杂碳包覆的焦磷酸盐材料按质量比在溶剂中混合固化形成。其中，所述集流体可参考本领域常规的集流体，如一些实施例中，所述集流体选为铜箔或铝箔；所述导电剂可参考本领域常规的导电剂，如一些实施例中，所述导电剂为石墨、炭黑、碳纳米管等；所述粘结剂可参考本领域常规的粘结剂，如一些实施例中，所述粘结剂选自聚乙烯醇、聚四氟乙烯和羧甲基纤维素钠中的至少一种。The existing negative electrode is mainly composed of a current collector and a material layer coating the top of the current collector. In the embodiment of the present invention, the material layer is composed of a conductive agent, a binder, and the above-mentioned nitrogen-doped carbon-coated pyrophosphoric acid The salt material is mixed and solidified in the solvent according to the mass ratio. Wherein, the current collector can refer to a conventional current collector in the field, for example, in some embodiments, the current collector is selected as copper foil or aluminum foil; the conductive agent can refer to a conventional conductive agent in the field, such as in some embodiments The conductive agent is graphite, carbon black, carbon nanotubes, etc.; the binder can refer to conventional binders in the art. For example, in some embodiments, the binder is selected from polyvinyl alcohol, polytetrafluoroethylene, etc. At least one of vinyl fluoride and sodium carboxymethyl cellulose.

作为一种实施方式，所述负极的制备包括：将氮掺杂碳包覆的焦磷酸锡、导电剂、粘结剂按质量比7:2:1的比例混合后再加入氮甲基吡咯烷酮，磨成浆料后涂覆于铜箔上，涂覆后于70℃下真空干燥，切割成负极片。As an embodiment, the preparation of the negative electrode includes: mixing tin pyrophosphate coated with nitrogen-doped carbon, a conductive agent, and a binder in a mass ratio of 7:2:1, and then adding nitrogen methyl pyrrolidone. After being ground into slurry, it is coated on copper foil, and after coating, it is vacuum dried at 70° C. and cut into negative electrode sheets.

本发明实施例提供的二次电池，其负极为上述负极，具有优异的电化学性能，例如高倍率性能以及高比容量性能等。In the secondary battery provided by the embodiment of the present invention, the negative electrode is the above-mentioned negative electrode and has excellent electrochemical performance, such as high rate performance and high specific capacity performance.

所述二次电池包括但不限于锂离子电池、钠离子电池、钾离子电池、钙离子电池等。在一些实施例中，所述二次电池优选为钠离子电池或钾离子电池。The secondary batteries include, but are not limited to, lithium ion batteries, sodium ion batteries, potassium ion batteries, calcium ion batteries, and the like. In some embodiments, the secondary battery is preferably a sodium ion battery or a potassium ion battery.

所述二次电池的结构可参考本领域常规的电池，其主要由正极、负极、隔膜、电解液和外壳组成，所述正极、隔膜、电解液和外壳的材料和组成可参考本领域的常规正极、隔膜、电解液和外壳。The structure of the secondary battery can refer to conventional batteries in the field, which are mainly composed of a positive electrode, a negative electrode, a separator, an electrolyte and a casing. The materials and composition of the positive electrode, a separator, an electrolyte and a casing can refer to conventional ones in the field. Positive electrode, separator, electrolyte and casing.

作为一种实施方式，所述二次电池为钠离子电池，所述电解液中的电解质包括钠的有机盐和/或钠的无机盐。在一些实施例中，所述电解质选自六氟磷酸钠、硫酸钠、六氟砷酸钠、四氟硼酸钠、高氯酸钠、三氟甲烷磺酰亚胺钠和三氟甲烷磺酸钠中的至少一种，优选为高氯酸钠。以储量丰富、价格低廉的钠盐作为钠离子半电池的电解质，不仅能够降低电池的成本，且反应过程中不会有枝晶产生刺破隔膜，具有较好安全性能。As an embodiment, the secondary battery is a sodium ion battery, and the electrolyte in the electrolyte includes an organic salt of sodium and/or an inorganic salt of sodium. In some embodiments, the electrolyte is selected from sodium hexafluorophosphate, sodium sulfate, sodium hexafluoroarsenate, sodium tetrafluoroborate, sodium perchlorate, sodium trifluoromethanesulfonimide, and sodium trifluoromethanesulfonate At least one of them is preferably sodium perchlorate. Using sodium salt with abundant reserves and low price as the electrolyte of the sodium ion half-cell can not only reduce the cost of the battery, but also will not produce dendrites to pierce the diaphragm during the reaction, and has better safety performance.

电解液中电解质的离子浓度会影响电解液的离子传输性能，以钠盐为例，当电解液中钠盐浓度过低，Na ⁺和阴离子过少，离子传输性能差，导电率低；当电解液中钠盐浓度过高，Na ⁺和阴离子过多，电解液的粘度和离子缔合的程度也会随钠盐浓度增加而增大，这又会降低电导率。在一些实施例中，电解液中钠盐的浓度优选为0.5-3mol/L，更优选1mol/L。 The ion concentration of the electrolyte in the electrolyte will affect the ion transmission performance of the electrolyte. Take sodium salt as an example. When the concentration of sodium salt in the electrolyte is too low, Na ⁺ and anions are too small, the ion transmission performance is poor, and the conductivity is low; If the sodium salt concentration in the solution is too high, Na ⁺ and anions are too much, the viscosity of the electrolyte and the degree of ion association will increase with the increase of the sodium salt concentration, which will reduce the conductivity. In some embodiments, the concentration of sodium salt in the electrolyte is preferably 0.5-3 mol/L, more preferably 1 mol/L.

电解液主要包括电解质和用于溶解电解质的有机溶剂，所述有机溶剂包括但不限于包括酯类、砜类、醚类、腈类等。在一些实施例中，所述有机溶剂选自碳酸丙烯酯、碳酸乙烯酯、碳酸二乙酯、氟代碳酸乙烯酯、碳酸二甲酯、碳酸甲乙酯、乙二醇二甲醚、二乙二醇二甲醚、二甲基砜、二甲醚中的一种。在进一步实施例中，所述电解液以浓度为1.0mol/L的高氯酸钠为电解质，以碳酸丙烯酯和氟代碳酸乙烯酯为溶剂，该电解液组合与上述负极协同作用，可使得钠离子电池的电化学性能最佳。The electrolyte mainly includes an electrolyte and an organic solvent used to dissolve the electrolyte. The organic solvent includes, but is not limited to, esters, sulfones, ethers, nitriles, and the like. In some embodiments, the organic solvent is selected from propylene carbonate, ethylene carbonate, diethyl carbonate, fluoroethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, ethylene glycol dimethyl ether, diethyl carbonate One of glycol dimethyl ether, dimethyl sulfone, and dimethyl ether. In a further embodiment, the electrolyte uses sodium perchlorate with a concentration of 1.0 mol/L as the electrolyte, and propylene carbonate and fluoroethylene carbonate are used as solvents. The combination of the electrolyte and the above-mentioned negative electrode act synergistically to make The electrochemical performance of the sodium ion battery is the best.

所述隔膜可参考本领域的常规电池隔膜，如在一些实施例中，所述隔膜的材料为玻璃微纤维，该玻璃微纤维隔膜与上述负极以及上述高氯酸钠-碳酸丙烯酯-氟代碳酸乙烯酯电解液组合，可最大限度地发挥钠离子电池的电化学性能。The separator can refer to conventional battery separators in the field. For example, in some embodiments, the material of the separator is glass microfibers, which are connected to the above-mentioned negative electrode and the above-mentioned sodium perchlorate-propylene carbonate-fluoro The combination of ethylene carbonate electrolyte can maximize the electrochemical performance of sodium ion batteries.

为使本发明上述实施细节和操作能清楚地被本领域技术人员理解，以及本发明实施例一种纳米材料及其制备方法、电极和二次电池的进步性能显著地体现，以下通过实施例对本发明的实施进行举例说明。In order to make the above-mentioned implementation details and operations of the present invention clearly understood by those skilled in the art, as well as the improved performance of a nano material and its preparation method, electrodes and secondary batteries in the embodiments of the present invention, the following examples are used to illustrate the present invention. The implementation of the invention is illustrated by examples.

实施例1Example 1

本实施例提供了一种氮掺杂碳包覆的焦磷酸锡材料，其制备方法具体包括以下步骤：This embodiment provides a nitrogen-doped carbon-coated tin pyrophosphate material, and its preparation method specifically includes the following steps:

（1）将10 mmol的SnCl ₂·2H ₂O加入到50 ml的去离子水中，加入2 mmol植酸、8 mmol三聚氰胺，55℃下剧烈搅拌2h，获得混合液； (1) Add 10 mmol of SnCl ₂ ·2H ₂ O to 50 ml of deionized water, add 2 mmol of phytic acid and 8 mmol of melamine, and stir vigorously at 55°C for 2 hours to obtain a mixed solution;

（2）将混合液转移到两口烧瓶中，并加入50ml的无水乙醇，然后在85℃下进行加热回流12h，离心取沉淀，用乙醇、水清洗数次，置于真空干燥箱70℃干燥12h，获得前驱体；(2) Transfer the mixed solution to a two-necked flask, and add 50ml of absolute ethanol, then heat to reflux at 85°C for 12h, centrifuge to collect the precipitate, wash it with ethanol and water several times, and place it in a vacuum drying oven at 70°C to dry 12h, get the precursor;

（3）在氩气气氛下，将前驱体在600℃反应2h，得到氮掺杂碳包覆的焦磷酸锡材料SnP ₂O ₇@N-C。 (3) In an argon atmosphere, the precursor was reacted at 600°C for 2h to obtain a nitrogen-doped carbon-coated tin pyrophosphate material SnP ₂ O ₇ @NC.

实施例2Example 2

本实施例与实施例1的区别在于：步骤（3）中，将前驱体在700℃反应2h；其余地方与实施例1的基本相同，此处不再一一赘述。The difference between this embodiment and embodiment 1 is that in step (3), the precursor is reacted at 700° C. for 2 hours; the rest is basically the same as that of embodiment 1, and will not be repeated here.

实施例3Example 3

本对比例与实施例1的区别在于：步骤（1）中，植酸的用量调为4mmol；其余地方与实施例1的基本相同，此处不再一一赘述。The difference between this comparative example and Example 1 lies in that: in step (1), the amount of phytic acid is adjusted to 4 mmol; the rest is basically the same as that of Example 1, and will not be repeated here.

实施例4Example 4

本实施例提供了一种氮掺杂碳包覆的焦磷酸钴材料，其制备方法具体包括以下步骤：This embodiment provides a nitrogen-doped carbon-coated cobalt pyrophosphate material, and its preparation method specifically includes the following steps:

（1）将10 mmol的CoCl ₂·6H ₂O加入到50 ml的去离子水中，加入4 mmol植酸、10 mmol尿素，60℃下剧烈搅拌1h，获得混合液； (1) Add 10 mmol of CoCl ₂ ·6H ₂ O to 50 ml of deionized water, add 4 mmol of phytic acid and 10 mmol of urea, and stir vigorously at 60°C for 1 hour to obtain a mixed solution;

（2）将混合液转移到两口烧瓶中，并加入50ml的无水乙醇，然后在85℃下进行加热回流12h，离心取沉淀，用乙醇、水清洗数次，置于真空干燥箱70℃干燥10h，获得前驱体；(2) Transfer the mixed solution to a two-necked flask, and add 50ml of absolute ethanol, then heat to reflux at 85°C for 12h, centrifuge to collect the precipitate, wash it with ethanol and water several times, and place it in a vacuum drying oven at 70°C to dry 10h, get the precursor;

（3）在氩气气氛下，将前驱体在700℃反应2h，得到氮掺杂碳包覆的焦磷酸锡材料Co ₂P ₂O ₇@N-C。 (3) In an argon atmosphere, the precursor was reacted at 700°C for 2 hours to obtain a nitrogen-doped carbon-coated tin pyrophosphate material Co ₂ P ₂ O ₇ @NC.

实施例5Example 5

本实施例提供了一种氮掺杂碳包覆的焦磷酸铅材料，其制备方法具体包括以下步骤：This embodiment provides a nitrogen-doped carbon-coated lead pyrophosphate material, and its preparation method specifically includes the following steps:

（1）将5 mmol的PbCl ₂加入到50 ml的去离子水中，加入3 mmol植酸、10 mmol尿素，70℃下剧烈搅拌1h，获得混合液； (1) Add 5 mmol of PbCl ₂ to 50 ml of deionized water, add 3 mmol of phytic acid and 10 mmol of urea, and stir vigorously at 70°C for 1 hour to obtain a mixed solution;

（3）在氩气气氛下，将前驱体在700℃反应2h，得到氮掺杂碳包覆的焦磷酸锡材料Pb ₂P ₂O ₇@N-C。 (3) In an argon atmosphere, the precursor was reacted at 700°C for 2 hours to obtain a nitrogen-doped carbon-coated tin pyrophosphate material Pb ₂ P ₂ O ₇ @NC.

实施例6Example 6

本实施例提供了一种氮掺杂碳包覆的焦磷酸钡材料，其制备方法具体包括以下步骤：This embodiment provides a nitrogen-doped carbon-coated barium pyrophosphate material, and its preparation method specifically includes the following steps:

（1）将8 mmol的BaCl ₂加入到50 ml的去离子水中，加入2mmol植酸、2mmol三聚氰胺，70℃下剧烈搅拌1h，获得混合液； (1) Add 8 mmol of BaCl ₂ to 50 ml of deionized water, add 2 mmol of phytic acid and 2 mmol of melamine, and stir vigorously at 70°C for 1 hour to obtain a mixed solution;

（2）将混合液转移到两口烧瓶中，并加入50ml的无水乙醇，然后在85℃下进行加热回流12h，离心取沉淀，用乙醇、水清洗数次，置于真空干燥箱70℃干燥10h，获得前驱体；(2) Transfer the mixture to a two-necked flask, and add 50ml of absolute ethanol, then heat to reflux at 85°C for 12h, centrifuge to collect the precipitate, wash it with ethanol and water several times, and place it in a vacuum drying oven at 70°C to dry 10h, get the precursor;

（3）在氩气气氛下，将前驱体在500℃反应2h，得到氮掺杂碳包覆的焦磷酸锡材料Ba ₂P ₂O ₇@N-C。 (3) In an argon atmosphere, the precursor was reacted at 500°C for 2h to obtain a nitrogen-doped carbon-coated tin pyrophosphate material Ba ₂ P ₂ O ₇ @NC.

实施例7Example 7

本实施例制备了一种钠离子半电池，其制备方法包括以下步骤：In this embodiment, a sodium ion half-cell is prepared, and the preparation method includes the following steps:

制备负极：取实施例1制得的SnP ₂O ₇@N-C、科琴黑、海藻酸钠按照质量比7:2:1均匀混合在一起，研磨30min，加入适量的水制成糊状浆料，然后，把浆料均匀涂覆在铜箔上，接着在70℃下真空干燥；把干燥过的铜箔滚压后，制成负极，裁切成直径10mm的圆片后作为负极，备用； Preparation of negative electrode: Take the SnP ₂ O ₇ @NC, Ketjen Black, and sodium alginate prepared in Example 1 and mix them evenly according to the mass ratio of 7:2:1, grind for 30 minutes, and add an appropriate amount of water to make a paste slurry , Then, the slurry is evenly coated on the copper foil, and then dried in vacuum at 70°C; the dried copper foil is rolled to form a negative electrode, which is cut into a disc with a diameter of 10mm and used as the negative electrode for use;

制备参比电极和对电极：钠片裁切成直径12mm的圆片后作为参比电极和对电极，备用；Preparation of reference electrode and counter electrode: the sodium sheet is cut into a disc with a diameter of 12 mm and used as the reference electrode and counter electrode for use;

制备隔膜：将玻璃纤维薄膜裁切成直径16mm的圆片后作为隔膜，备用；Preparation of diaphragm: cut the glass fiber film into discs with a diameter of 16mm as a diaphragm for use;

配制电解液：称取0.6122g高氯酸钠加入到5ml的碳酸丙烯酯、5%wt氟代碳酸乙烯酯溶剂中，搅拌至高氯酸钠完全溶解，充分搅拌均匀后作为电解液，备用；Prepare electrolyte: Weigh 0.6122g of sodium perchlorate and add it to 5ml of propylene carbonate and 5%wt fluoroethylene carbonate solvent, stir until the sodium perchlorate is completely dissolved, stir well and use it as electrolyte for later use;

组装：在惰性气体保护的手套箱（氧气与水的含量均小于0.1ppm）中，将上述制备好的正极、隔膜、负极依次紧密堆叠，滴加电解液使隔膜完全浸润，然后将上述堆叠部分封装入扣式壳体，完成钠离子半电池的组装。Assembly: In an inert gas-protected glove box (both oxygen and water content are less than 0.1ppm), the above-prepared positive electrode, separator, and negative electrode are closely stacked in sequence, and electrolyte is added dropwise to completely infiltrate the separator, and then the above-mentioned stacked part Encapsulate it in a button-type casing to complete the assembly of the sodium ion half-cell.

对比例1Comparative example 1

本对比例提供了一种碳包覆的焦磷酸锡材料SnP ₂O ₇@C，其制备方法与实施例1的区别在于：步骤（1）中省略加入三聚氰胺； This comparative example provides a carbon-coated tin pyrophosphate material SnP ₂ O ₇ @C. The preparation method is different from Example 1 in that the addition of melamine is omitted in step (1);

其余地方与实施例1的基本相同，此处不再一一赘述。The other parts are basically the same as those of Embodiment 1, and will not be repeated here.

对比例2Comparative example 2

本对比例与实施例1的区别在于：步骤（3）中，在H ₂/Ar混合气体气氛下，将前驱体在600℃反应2h；其余地方与实施例1的基本相同，此处不再一一赘述。 The difference between this comparative example and Example 1 is that: in step (3) _{, the precursor is reacted at 600°C for 2h in an H 2} /Ar mixed gas atmosphere; the rest is basically the same as in Example 1, and will not be omitted here. Go into details one by one.

本对比例无法制得具有核壳结构的氮掺杂碳包覆的焦磷酸锡材料。In this comparative example, a nitrogen-doped carbon-coated tin pyrophosphate material with a core-shell structure could not be prepared.

测试例1Test case 1

对实施例1制得的SnP ₂O ₇@N-C进行XRD测试，其衍射谱图如图1所示，由图1中可以看出，所有衍射峰均可对应于XRD标准卡片JCPDS No. 29-1352。而且图中有明显的碳包峰，可以看出是一种碳材料包覆焦磷酸锡材料。 The XRD test was performed on the SnP ₂ O ₇ @NC prepared in Example 1. The diffraction spectrum is shown in Figure 1. As can be seen from Figure 1, all diffraction peaks can correspond to the XRD standard card JCPDS No. 29- 1352. And there is an obvious carbon-coated peak in the figure, which can be seen as a carbon material coated tin pyrophosphate material.

对实施例1制得的SnP ₂O ₇@N-C做扫描电镜分析（SEM）和透射电镜分析（TEM），其扫描电镜照片如图2所示，其透射电镜照片如图3所示，由图2和图3可以看出，SnP ₂O ₇@N-C是均匀分布的颗粒。 Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were performed on the SnP ₂ O ₇ @NC prepared in Example 1. The scanning electron microscopy photo is shown in Figure 2 and the transmission electron microscopy photo is shown in Figure 3. It can be seen from Fig. 2 and Fig. 3 that SnP ₂ O ₇ @NC is uniformly distributed particles.

对实施例1制得的SnP ₂O ₇@N-C进行X射线能谱分析，如图4所示，SnP ₂O ₇@N-C中的C、N、Sn、P、O等元素分布非常均匀。 _{X-ray energy spectrum analysis was performed on the SnP 2} O ₇ @NC prepared in Example 1. As shown in FIG. 4, the distribution of C, N, Sn, P, O and other elements _{in SnP 2} O _{7 @NC was very uniform.}

测试例2Test case 2

为了验证本发明实施例制得的SnP ₂O ₇@N-C的电化学性能，对实施例7制得的钠离子半电池进行了电化学性能测试。同时，采用对比例1制得的SnP ₂O ₇@C参考实施例7的步骤制得对照用的钠离子半电池。 _{In order to verify the electrochemical performance of the SnP 2} O ₇ @NC prepared in the example of the present invention, the electrochemical performance test was performed on the sodium ion half-cell prepared in Example 7. _{At the same time, the SnP 2} O ₇ @C prepared in Comparative Example 1 was used with reference to the steps of Example 7 to prepare a sodium ion half-cell for comparison.

在新威测试***上进行电池的充放电测试，电池工作区间为0 .01-3V，图5为对比例1制得的SnP ₂O ₇@N-C与实施例1制得的SnP ₂O ₇@N-C作为负极材料的钠离子半电池在1.5A g ^-1电流密度条件下的长循环性能检测结果，如图所示，SnP ₂O ₇@N-C表现出了很好的循环性能。 The battery charging and discharging test was performed on the Xinwei test system. The battery working range is 0. 01-3V. Figure 5 shows the SnP ₂ O ₇ @NC prepared in Comparative Example 1 and the SnP ₂ O ₇ @ prepared in Example 1. The long-cycle performance test results of the sodium ion half-cell with NC as the negative electrode material ^{under the current density of 1.5A g -1} . As shown in the figure, SnP ₂ O ₇ @NC shows good cycle performance.

图6为实施例2制得的产物与实施例1制得的SnP ₂O ₇@N-C作为负极材料的钠离子半电池在1.5A g ^-1电流密度条件下的长循环性能检测结果。 6 shows the long-cycle performance test results of the product prepared in Example 2 and the SnP ₂ O ₇ @NC prepared in Example 1 as the negative electrode material of the sodium ion half-cell under the ^{current density of 1.5A g -1.}

图7为实施例3制得的产物与实施例1制得的SnP ₂O ₇@N-C作为负极材料的钠离子半电池在1.5A g ^-1电流密度条件下的长循环性能检测结果，如图所示。 Fig. 7 shows the long-cycle performance test results of the product prepared in Example 3 and the SnP ₂ O ₇ @NC prepared in Example 1 as the negative electrode material of the sodium ion half-cell ^{under the condition of 1.5A g -1 current density, as shown in Fig.} Shown.

以上所述仅为本发明的较佳实施例而已，并不用以限制本发明，凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明的保护范围之内。The above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modification, equivalent replacement and improvement made within the spirit and principle of the present invention shall be included in the protection of the present invention. Within range.

Claims

一种纳米材料的制备方法，其特征在于，包括以下步骤：A method for preparing nanomaterials, which is characterized in that it comprises the following steps:

将金属前驱体、磷源和含氮有机物溶解在溶剂中，制备混合液；Dissolving the metal precursor, phosphorus source and nitrogen-containing organic matter in a solvent to prepare a mixed solution;

将所述混合液进行加热反应，制备前驱体；Subjecting the mixed liquid to a heating reaction to prepare a precursor;

将所述前驱体在惰性气体气氛下进行煅烧处理，制备氮掺杂碳包覆的焦磷酸盐材料。The precursor is calcined in an inert gas atmosphere to prepare a nitrogen-doped carbon-coated pyrophosphate material.
根据权利要求1所述的制备方法，其特征在于，所述磷源与所述金属前驱体的比摩尔比为1 : (0.5-10)；和/或 The preparation method according to claim 1, wherein the molar ratio of the phosphorus source to the metal precursor is 1: (0.5-10); and/or

所述磷源选自植酸、磷酸、磷酸二氢氨、甲基膦酸和多磷酸中的至少一种。The phosphorus source is selected from at least one of phytic acid, phosphoric acid, ammonium dihydrogen phosphate, methylphosphonic acid and polyphosphoric acid.
根据权利要求1所述的制备方法，其特征在于，所述含氮有机物与所述金属前驱体的摩尔比为(0.1-2) : 1；和/或 The preparation method according to claim 1, wherein the molar ratio of the nitrogen-containing organic matter to the metal precursor is (0.1-2): 1; and/or

所述混合液中所述含氮有机物的浓度为0.05-1 mol/L。The concentration of the nitrogen-containing organic matter in the mixed solution is 0.05-1 mol/L.
根据权利要求1所述的制备方法，其特征在于，所述含氮有机物选自尿素、三聚氰胺、缩二脲、乙二胺四乙酸和六亚甲基四胺中的至少一种。 The preparation method according to claim 1, wherein the nitrogen-containing organic substance is selected from at least one of urea, melamine, biuret, ethylenediaminetetraacetic acid and hexamethylenetetramine.
根据权利要求1至4中任一项所述的制备方法，其特征在于，将所述混合液进行加热反应的步骤中，将所述混合液在70℃-95℃下加热回流8-20小时。 The preparation method according to any one of claims 1 to 4, characterized in that, in the step of subjecting the mixed solution to a heating reaction, the mixed solution is heated to reflux at 70°C-95°C for 8-20 hours .
根据权利要求1至4中任一项所述的制备方法，其特征在于，将所述前驱体在惰性气体气氛下进行煅烧处理，将所述前驱体在惰性气体气氛下于500℃-800℃高温煅烧1-10小时。 The preparation method according to any one of claims 1 to 4, wherein the precursor is calcined in an inert gas atmosphere, and the precursor is heated at 500°C to 800°C in an inert gas atmosphere. Calcined at high temperature for 1-10 hours.
根据权利要求1至4中任一项所述的制备方法，其特征在于，所述金属前驱体选自锡源、铅源、钡源、钙源、锌源、钴源、铋源中的至少一种。 The preparation method according to any one of claims 1 to 4, wherein the metal precursor is selected from at least a tin source, a lead source, a barium source, a calcium source, a zinc source, a cobalt source, and a bismuth source. One kind.
一种纳米材料，其特征在于，包括：由权利要求1至7中任一项所述的制备方法制得的氮掺杂碳包覆的焦磷酸盐材料。 A nano material, characterized by comprising: a nitrogen-doped carbon-coated pyrophosphate material prepared by the preparation method of any one of claims 1 to 7.
一种负极，其特征在于，所述负极的材料包括：由权利要求1至7中任一项所述的制备方法制得的纳米材料，或权利要求8所述的纳米材料。 A negative electrode, characterized in that the material of the negative electrode comprises: the nano material prepared by the preparation method according to any one of claims 1 to 7, or the nano material according to claim 8.
一种二次电池，其特征在于，所述二次电池的负极为权利要求9所述的负极。 A secondary battery, characterized in that the negative electrode of the secondary battery is the negative electrode of claim 9.