A negative thermal expansion material and a method of making the same

Abstract

The application relates to a negative thermal expansion material and a preparation method thereof, and provides a negative thermal expansion material and a preparation method thereof, and relates to a negative thermal expansion material and a preparation method thereof.Coupling the advantages of different negative thermal expansion materials, Ti is used to replace Zr in Zr2MoP2O 12 to be modified to prepare a novel negative thermal expansion material Zr 2‑x Ti x MoP2O 12 (0<=x<=2), Ti occupies the site of Zr, induces defects of Zr2MoP2O 12 lattice to form interstitial sites suitable for lithium space, so that the material has negative thermal expansion and high ionic conductivity at the same time.The application aims to solve the problems of low ionic conductivity of the existing negative thermal expansion material Zr2MoP2O 12 and small expansion coefficient of LiTi2(PO4)3, develop a novel negative thermal expansion material with high expansion coefficient and high ionic conductivity, and the preparation process method is simple, green, environmentally friendly, low in energy consumption and high in operability.

Description

Technical Field

[0001] This invention relates to the field of special functional materials, and more specifically, to a negative thermal expansion material and its preparation method, which can regulate the expansion coefficient and strain of the material to improve the electrochemical performance and safety of energy devices. Background Technology

[0002] In contrast to the conventional material's "thermal expansion and contraction" property, negative thermal expansion materials shrink in volume when heated, exhibiting a unique "thermal contraction and cold expansion" property. Within a certain temperature range, their average linear or volumetric expansion coefficient is negative, allowing for the control of the material's thermal expansion coefficient. They can be combined with conventional positive thermal expansion materials to prepare low-expansion or zero-expansion materials. As a cutting-edge fundamental material, negative thermal expansion materials are a hot topic in solid-state chemistry and functional materials research, with broad application prospects in areas such as improving the performance and safety of batteries and supercapacitors, catalyst modification, thermal utilization, precision optical instruments, microelectronic devices, aerospace, cryogenic engineering, deep earth, and deep space. Diverse application requirements have driven the development of new negative thermal expansion materials, involving multidisciplinary knowledge, various materials, and multiple process routes. Nevertheless, the design, controllable preparation, and modification of negative thermal expansion materials to meet specific needs still face significant challenges.

[0003] Among many materials with negative thermal expansion, Zr2WP2O 12 Exhibiting prominent negative thermal expansion characteristics, and based on its structural features, an orthorhombic Zr₂MoP₂O system was prepared by replacing W with Mo. 12 It also exhibits good negative thermal expansion characteristics, with a negative thermal expansion coefficient reaching -6.12 × 10⁻⁶ within the temperature range of 25–700 °C. −6 / °C. LiTi2(PO4)3 (LTP) is a fast ion conductor, composed of TiO6 octahedra and PO4 tetrahedra connected by shared oxygen atoms at their vertices. It has a stable structure, lithium storage sites, and high ionic conductivity (3.1 × 10⁻⁶ at 25 °C). −5 The coefficient of thermal expansion (COP) can increase the ion transport rate of the material (S / cm); moreover, LiTi2(PO4)3 is an anisotropic material with negative thermal expansion, with a negative thermal expansion coefficient of -0.11 × 10⁻⁶ COP in the temperature range of 25–1000 °C. −6 / °C. To make Zr2MoP2O 12 It also possesses good negative thermal expansion characteristics and ion diffusion ability, combined with Zr2MoP2O 12 The advantages of LiTi2(PO4)3 are combined with the use of Ti to treat Zr2MoP2O 12 Modification was carried out to form a new negative thermal expansion material Zr. 2-x Ti x MoP2O 12 (0≤x≤2). Zr 2-x Ti x MoP2O 12 In this process, Ti occupies sites in Zr, creating lattice defects and forming interstitial sites suitable for lithium conductivity, thereby improving the ionic conductivity of the material.

[0004] Compared with existing materials, the new negative thermal expansion material Zr 2-x Ti x MoP2O 12 It overcomes the shortcomings of existing materials in terms of negative thermal expansion coefficient and low ionic conductivity, while possessing good negative thermal expansion coefficient and high ionic conductivity, and maintains the properties of Zr2MoP2O. 12 It combines the advantages of LiTi2(PO4)3 and makes up for the shortcomings of both, and is easy to prepare. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing negative thermal expansion materials, which have low coefficients of thermal expansion and low ionic conductivity, and to propose a strategy for designing and developing new negative thermal expansion materials based on the advantages of different negative thermal expansion materials, thereby solving the problems of low coefficients of thermal expansion and low ionic conductivity of existing negative thermal expansion materials.

[0006] In view of this, the present invention provides a novel negative thermal expansion material and its preparation method, aiming to solve the shortcomings of existing negative thermal expansion materials with low coefficient of thermal expansion and ionic conductivity, and to provide ideas for the development of novel negative thermal expansion materials that take into account both high negative thermal expansion and high ionic conductivity.

[0007] To achieve this objective, the present invention mainly adopts the following technical solutions:

[0008] A negative thermal expansion material and its preparation method, characterized in that the method comprises: the negative thermal expansion material containing Zr, Ti, Mo, P, and O, specifically Zr. 2-x Ti x MoP2O 12 (0≤x≤2), the precursor is formed by mixing raw materials containing Zr, Ti, Mo and P, and then synthesized by calcination at a certain temperature for a certain period of time.

[0009] Preferably, the mixing refers to dry mixing without adding solution and wet mixing with adding solvent.

[0010] Preferably, the precursor refers to a substance formed from raw materials containing Zr, Ti, Mo, and P, especially their oxides, hydroxides, oxalates, sulfates, and complexes.

[0011] Preferably, the specified temperature refers to 400~1200ºC, and more particularly 400~800ºC.

[0012] Preferably, the time period refers to 1 to 9 hours, especially 2 to 5 hours.

[0013] The method provided by this invention can combine the advantages of different negative thermal expansion materials to develop novel negative thermal expansion materials with both high thermal expansion coefficient and ionic conductivity, overcoming the shortcomings of existing materials with low negative thermal expansion coefficient and ionic conductivity. The preparation method is simple and highly operable. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 The prepared Zr is shown 1.4 Ti 0.6 MoP2O 12 X-ray diffraction (XRD) pattern of the product;

[0016] Figure 2 The prepared Zr is shown 1.4 Ti 0.6 MoP2O 12 Product morphology diagram. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0018] This embodiment provides a negative thermal expansion material and its preparation method, the method including the following steps: Example

[0019] To synthesize Zr 1.4 Ti 0.6 MoP2O 12 For example, using ZrO2 and (NH4)6Mo7O 24 Using 4H2O, NH4H2PO4, and Ti[OCH(CH3)2]4 as raw materials, and mixing them according to the molar ratio of Zr, Ti, Mo, and P, Zr is synthesized. 1.4 Ti 0.6 MoP2O 12 The specific operating steps are as follows:

[0020] Add Ti[OCH(CH3)2]4 to beaker A containing 25 ml of C2H5OH and stir;

[0021] Weigh out a certain amount of ZrO2, 1.76 g of (NH4)6Mo7O 24 Add 4H2O and 2.3 g NH4H2PO4 to beaker B, and add an appropriate amount of alcohol to disperse them;

[0022] After slowly adding the substance from beaker B to beaker A, stir for 4 hours.

[0023] The above-mentioned well-stirred material was dried to obtain the precursor;

[0024] The precursor was pre-calcined in a muffle furnace at 500 °C for 3 hours, cooled, and ground into powder. The powder was then calcined at 900–1170 °C for 6 hours, cooled, and ground again to obtain the product Zr. 1.4 Ti 0.6 MoP2O 12 .

[0025] Prepared Zr 1.4 Ti 0.6 MoP2O 12 The X-ray diffraction (XRD) curves and scanning electron microscopy (SEM) morphologies of the products are as follows: Figure 1 and 2 As shown, with Zr2MoP2O 12 They have the same crystal form, high purity, small particle size and uniform distribution, but Zr 1.4 Ti 0.6 MoP2O 12 Zr2MoP2O 12 The ionic conductivity ranges from 1.36 × 10⁻⁶. -5 S / cm increased to 1.02×10 -4 S / cm, reducing the negative thermal expansion coefficient of LiTi2(PO4)3 from -0.11×10 −6 / °C increased to -4.6×10 −6 It has a temperature of / °C and also exhibits high negative thermal expansion and ionic conductivity. Example

[0026] Synthesis of ZrTiMoP2O 12 For example, using zirconium carbonate, sodium molybdate, H3PO4, and titanium sulfate as raw materials, and mixing them according to the molar ratio of Zr, Ti, Mo, and P elements, ZrTiMoP2O can be synthesized. 12 The specific operating steps are as follows:

[0027] Add zirconium carbonate, sodium molybdate, and H3PO4 to a beaker containing 500ml of deionized water in the specified proportions and stir.

[0028] Titanium sulfate was slowly added to the above-mentioned stirred solution while stirring continuously and thoroughly. Ammonia was used as a complexing agent, and sodium hydroxide solution was used to adjust the pH value.

[0029] Stirring produces a precipitate, which is then filtered. The filter cake is washed multiple times with deionized water and dried to obtain the precursor.

[0030] The precursor was calcined at 400-650 ℃ for 2 h, cooled and ground to obtain the product ZrTiMoP2O. 12 .

[0031] The above provides a detailed description of a real-time safety status assessment method for batteries and supercapacitors provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for preparing a negative thermal expansion material, characterized in that: Using ZrO2 and (NH4)6Mo7O 24 Using 4H2O, NH4H2PO4, and Ti[OCH(CH3)2]4 as raw materials, and mixing them according to the molar ratio of Zr, Ti, Mo, and P, Zr is synthesized. 1.4 Ti 0.6 MoP2O 12 The specific operating steps are as follows: (1) Add Ti[OCH(CH3)2]4 to beaker A containing 25ml C2H5OH and stir; (2) Weigh out a certain amount of ZrO2, 1.76 g of (NH4)6Mo7O 24 Add 4H2O and 2.3 g NH4H2PO4 to beaker B, and add an appropriate amount of alcohol to disperse them; (3) After slowly adding the substance from beaker B to beaker A, stir for 4 hours; (4) Dry the above-mentioned uniformly stirred material to obtain the precursor; (5) The precursor was pre-calcined in a muffle furnace at 500 °C for 3 h, cooled and ground into powder, and then the powder was calcined at 900~1170 °C for 6 h, cooled and ground to obtain the product Zr. 1.4 Ti 0.6 MoP2O 12 .

2. A method for preparing a negative thermal expansion material, characterized in that: ZrTiMoP2O was synthesized by using zirconium carbonate, sodium molybdate, H3PO4, and titanium sulfate as raw materials, and by mixing them according to the molar ratio of Zr, Ti, Mo, and P. 12 The specific operating steps are as follows: (1) Add zirconium carbonate, sodium molybdate, and H3PO4 to a beaker containing 500ml of deionized water in the specified proportion and stir. (2) Add titanium sulfate slowly to the above-stirred solution and continue stirring thoroughly. Use ammonia water as a complexing agent and adjust the pH value with sodium hydroxide solution. (3) Stirring produces a precipitate, which is then filtered. The filter cake is washed multiple times with deionized water and dried to obtain the precursor. (4) The precursor was calcined at 400~650 °C for 2 h, cooled and ground to obtain the product ZrTiMoP2O. 12 .

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