A two-dimensional germanium-based halide perovskite antiferroelectric material, a preparation method thereof and energy storage applications thereof

Abstract

The present application relates to a kind of two-dimensional germanium-based halide perovskite antiferroelectric material and its preparation method and energy storage applications, the molecular formula of the two-dimensional germanium-based halide perovskite antiferroelectric material is [(CH3)2CHCH2NH3]2 CsGe2I7.The two-dimensional germanium-based halide perovskite antiferroelectric material of the present application, the two-dimensional germanium-based halide perovskite antiferroelectric material is leadless poison, Curie temperature is high, polarization value is large, energy storage density is large, energy storage efficiency is high;And the material can be prepared by solution cooling method, its reaction condition is mild, simple and easy to operate, low in cost;Because its energy storage density is large, energy storage efficiency is high, has bright application prospect in the field such as energy storage device.

Description

Technical Field

[0001] This invention belongs to the field of functional materials, specifically relating to a two-dimensional germanium-based halide perovskite antiferroelectric material, its preparation method, and its energy storage application. Background Technology

[0002] Antiferroelectrics are an important class of functional materials. Within a certain temperature range, the dipoles on the bonding lines of adjacent ions are arranged antiparallel, and the macroscopic polarization is zero. Under the induction of an external electric field, the antiferroelectric phase can transform into a metastable ferroelectric phase. This process is accompanied by changes in volume, polarization, and electrical energy, opening up broad application prospects for antiferroelectrics in energy storage and energy conversion. Researchers have been committed to exploring and discovering high-performance antiferroelectric materials, such as inorganic oxides, hydrogen-bonded organic compounds, and organic-inorganic hybrids. In particular, the emerging two-dimensional halide perovskite antiferroelectrics have attracted widespread research interest. Their synthesis methods are simple, and their structures are flexible and varied, making them a class of functional materials with great development potential, and they are expected to provide new opportunities for the development of electroactive materials. However, the further development and application of these materials are hindered by problems such as lead toxicity, low polarization, and narrow operating temperature range, prompting researchers to explore new alternative materials.

[0003] In recent years, tin-based (Sn) and germanium-based (Ge) hybrid perovskites have gained attention due to their low toxicity and stronger polarizability. 2 The increasingly diverse structures and properties associated with lone-pair electrons have attracted widespread attention from researchers. In particular, Ge... 2+ Up to 6s 2 The strong stereochemical expression of lone pairs of electrons leads to large octahedral distortions, which in turn results in strong second harmonics and high polarization in germanium-based perovskites. For example, ferroelectricity has been demonstrated in three-dimensional inorganic halide perovskites CsGeX3 (X = Cl, Br, and I), with strong spontaneous polarization (up to 20 μC / cm). 2 (Originating from Ge) 2+ Ion shifts resulting from lone-pair stereochemical activity. Simultaneously, two-dimensional multilayer germanium-based halide perovskite ferroelectrics exhibit stronger nonlinear signals compared to Sn-based and Pb-based analogs, thanks to the expression of lone-pair stereochemical activity. Although extensive work has been conducted to investigate the nonlinear optics and ferroelectricity of Ge-based halide perovskites, antiferroelectricity remains to be explored. Summary of the Invention

[0004] This invention provides a two-dimensional germanium-based halide perovskite antiferroelectric material, its preparation method, and its energy storage application. This two-dimensional germanium-based halide perovskite antiferroelectric material is lead-free, has a high Curie temperature, a large polarization value, high energy density, and high energy storage efficiency. Furthermore, this material can be prepared using a solution cooling method, which is mild, simple, and inexpensive. Due to its high energy density and efficiency, it has promising applications in energy storage devices and other fields.

[0005] This invention is achieved through the following technical solution:

[0006] Option 1)

[0007] A two-dimensional germanium-based halide perovskite antiferroelectric material, the molecular formula of which is [(CH3)2CHCH2NH3]2CsGe2I7.

[0008] Furthermore, the two-dimensional germanium-based halide perovskite antiferroelectric material belongs to the orthorhombic crystal system at room temperature, with space group Pmmn and cell parameters of [missing information]. α=90°, β=90°, γ=90°.

[0009] Furthermore, the two-dimensional germanium-based halide perovskite antiferroelectric material undergoes an antiferroelectric-paraelectric phase transition at 402 K. In the paraelectric phase, the space group of the compound changes to Cmmn, and the cell parameters are... α=90°, β=90°, γ=90°.

[0010] Hysteresis loop measurements using the Sawyer-Tower circuit method indicate that the two-dimensional germanium-based halide perovskite antiferroelectric material [(CH3)2CHCH2NH3]2CsGe2I7 exhibits excellent antiferroelectric properties in the antiferroelectric phase, with a polarization intensity of approximately 27 μC / cm. 2 .

[0011] Option 2)

[0012] A method for synthesizing a two-dimensional germanium-based halide perovskite antiferroelectric material includes the following sequential steps:

[0013] (1) Add GeO2 to a mixed solution of hydroiodic acid and hypophosphoric acid, stir and heat to 90-110℃, and then continue stirring for more than 30 minutes;

[0014] (2) Then add isobutylamine and Cs2CO3, and continue heating and stirring until a clear solution is obtained.

[0015] (3) Finally, after cooling to room temperature, the two-dimensional germanium-based halide perovskite antiferroelectric material is obtained.

[0016] The weight percentage of HI in hydroiodic acid is 55-58%.

[0017] The weight percentage of H3PO2 in hypophosphorous acid is 50%.

[0018] The ratio of GeO2, hydroiodic acid and hypophosphite is 2 mmol of GeO2: 5-10 ml of hydroiodic acid: 2-4 ml of hypophosphite;

[0019] The molar ratio of GeO2, isobutylamine and Cs2CO3 is 2:2:0.5.

[0020] Further, the clarified solution obtained in step (2) is cooled from 70-80℃ to 20-30℃ at a rate of 0.5-2℃ / day to obtain a blocky two-dimensional germanium-based halide perovskite antiferroelectric material.

[0021] An energy storage application of a two-dimensional germanium-based halide perovskite antiferroelectric material, wherein the two-dimensional germanium-based halide perovskite antiferroelectric material is used to prepare energy storage devices.

[0022] An energy storage device is made from the aforementioned two-dimensional germanium-based halide perovskite antiferroelectric material.

[0023] Compared with previous technologies, the present invention has the following advantages: The present invention provides a two-dimensional germanium-based halide perovskite antiferroelectric material. The two-dimensional germanium-based halide perovskite antiferroelectric material of the present invention is lead-free, has a high Curie temperature, a large polarization value, a high energy density, and a high energy storage efficiency; moreover, this material can be prepared by a solution cooling method, which has mild reaction conditions, is simple and easy to implement, and is inexpensive; due to its high energy density and high energy storage efficiency, it has bright application prospects in the fields of energy storage devices. Attached Figure Description

[0024] Figure 1 This is a room-temperature crystal photograph of the two-dimensional germanium-based halide perovskite antiferroelectric material of this invention.

[0025] Figure 2 This is a schematic diagram of the antiferroelectric phase structure of the two-dimensional germanium-based halide perovskite antiferroelectric material of the present invention.

[0026] Figure 3 This is a schematic diagram of the paraelectric phase structure of the two-dimensional germanium-based halide perovskite antiferroelectric material of the present invention.

[0027] Figure 4 The differential scanning calorimetry curve of the two-dimensional germanium-based halide perovskite antiferroelectric material of this invention is shown.

[0028] Figure 5 The temperature-dependent dielectric constant of the two-dimensional germanium-based halide perovskite antiferroelectric material of this invention is [not specified].

[0029] Figure 6 This invention relates to the double hysteresis loop of the two-dimensional germanium-based halide perovskite antiferroelectric material.

[0030] Figure 7 This invention relates to the energy storage performance of a two-dimensional germanium-based halide perovskite antiferroelectric material at different temperatures.

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0032] Example 1

[0033] A method for synthesizing a two-dimensional germanium-based halide perovskite antiferroelectric material includes the following sequential steps:

[0034] (1) Add GeO2 to a mixed solution of hydroiodic acid and hypophosphoric acid, stir and heat to 100°C, and then continue stirring for 30 minutes;

[0035] (2) Then add isobutylamine and Cs2CO3, and continue heating and stirring until a clear solution is obtained.

[0036] (3) Finally, after cooling to room temperature, the two-dimensional germanium-based halide perovskite antiferroelectric material is obtained.

[0037] The weight percentage of HI in hydroiodic acid is 55-58%; (57% is used in this embodiment, but other concentrations of 55-58% can also be used to obtain the two-dimensional germanium-based halide perovskite antiferroelectric material of this invention)

[0038] The weight percentage of H3PO2 in hypophosphorous acid is 50%.

[0039] The ratio of GeO2, hydroiodic acid, and hypophosphite is 2 mmol of GeO2: 5-10 ml of hydroiodic acid: 2-4 ml of hypophosphite; (In this embodiment, 2 mmol of GeO2: 5 ml of hydroiodic acid: 2 ml of hypophosphite is used. Other ratios of this invention can also be used to prepare the two-dimensional germanium-based halide perovskite antiferroelectric material of this invention.)

[0040] The molar ratio of GeO2, isobutylamine and Cs2CO3 is 2:2:0.5.

[0041] Specifically, the clarified solution obtained in step (2) is cooled from 75°C (the temperature may vary slightly each time depending on the actual formula and adjustment) at a rate of 1°C / day (other rates between 0.5-2°C can also be used) to 25°C (20-30°C is also acceptable), to obtain a blocky two-dimensional germanium-based halide perovskite antiferroelectric material, such as... Figure 1 As shown.

[0042] This two-dimensional germanium-based halide perovskite antiferroelectric material, such as Figure 2 As shown, at room temperature, it is an antiferroelectric phase, belonging to the orthorhombic crystal system, with space group Pmmn and cell parameters of . α = 90°, β = 90°, γ = 90°. The Ge atom is surrounded by six I atoms, connected and highly twisted [GeI6]. 4- Octahedron, each [GeI6] 4- Octahedrons are connected by common corners to form an inorganic framework. Cs atoms are located in the pores of the octahedron connections. Isobutylamine cations are arranged alternately with the inorganic framework to form a typical Ruddlesden-Popper type perovskite.

[0043] Its phase transition temperature was determined by differential scanning calorimetry (DSC), such as Figure 4 As shown, this compound underwent a structural transformation from antiferroelectric to paraelectric phase at 402 K. Figure 3 As shown, in the paraelectric phase (420 K), the space group of this compound changes to Cmmn, and the cell parameters are... α = 90°, β = 90°, γ = 90°. This paraelectric phase retains the Ruddlesden-Popper perovskite structure of the antiferroelectric phase, but in the paraelectric phase [GeI6]... 4- The octahedral distortion decreases, and the isobutylamine cation is in a disordered state.

[0044] Temperature-dependent dielectric constant tests were performed on the two-dimensional germanium-based halide perovskite antiferroelectric material [(CH3)2CHCH2NH3]2CsGe2I7 obtained in Example 1. A distinct step-type phase transition was observed at the antiferroelectric-ferroelectric structural transition point (402 K), revealing the switchability between low ("off") and high ("on") dielectric states centered around 402 K. Figure 5 As shown, this two-dimensional germanium-based halide perovskite antiferroelectric material has potential applications in fields such as dielectric switches. Furthermore, the significant endothermic and exothermic processes during the phase transition indicate its potential applications in phase change thermal storage technology.

[0045] The hysteresis loop of the two-dimensional germanium-based halide perovskite antiferroelectric [(CH3)2CHCH2NH3]2CsGe2I7 obtained in Example 1 was tested, and the results were as follows: Figure 6 As shown, the saturation polarization intensity is approximately 27 μC / cm at room temperature. 2 The energy storage density was calculated to be approximately 0.27 J / cm³ based on the tested hysteresis loop. 3 With an energy storage efficiency of approximately 79.76%, this material shows promising prospects in energy storage devices and other applications. Simultaneously, it exhibits excellent stability, such as... Figure 7As shown, after being heated to 342K, its energy storage performance did not show significant degradation, demonstrating its huge application potential in the field of energy storage.

[0046] This invention is not limited to the above embodiments. All equivalent substitutions and modifications made based on the principles of this invention are within the scope of protection of this invention.

Claims

1. A two-dimensional germanium-based halide perovskite antiferroelectric material, characterized in that: The molecular formula of the two-dimensional germanium-based halide perovskite antiferroelectric material is [(CH3)2CHCH2NH3]2CsGe2I7; the two-dimensional germanium-based halide perovskite antiferroelectric material belongs to the orthorhombic crystal system at room temperature, with space group Pmmn, and cell parameters a = 8.40310 Å, b = 38.65100 Å, c = 8.72930 Å, α = 90°, β = 90°, γ = 90°.

2. The two-dimensional germanium-based halide perovskite antiferroelectric material according to claim 1, characterized in that: The two-dimensional germanium-based halide perovskite antiferroelectric material undergoes an antiferroelectric-paraelectric phase transition at 402 K. In the paraelectric phase, the space group of the compound changes to Cmmn, and the cell parameters are a = 39.81500 Å, b = 8.74920 Å, c = 8.51250 Å, α = 90°, β = 90°, and γ = 90°.

3. The method for preparing a two-dimensional germanium-based halide perovskite antiferroelectric material according to claim 1 or 2, characterized in that: The steps are as follows: (1) Add GeO2 to a mixed solution of hydroiodic acid and hypophosphoric acid, stir and heat to 90-110℃, and then continue stirring for more than 30 minutes; (2) Then add isobutylamine and Cs2CO3, and continue heating and stirring until a clear solution is obtained. (3) After cooling to room temperature, the two-dimensional germanium-based halide perovskite antiferroelectric material is obtained. The weight percentage of HI in hydroiodic acid is 55-58%. The weight percentage of H3PO2 in hypophosphorous acid is 50%. The ratio of GeO2, hydroiodic acid and hypophosphoric acid is 2 mmol of GeO2: 5-10 ml of hydroiodic acid: 2-4 ml of hypophosphoric acid; The molar ratio of GeO2, isobutylamine and Cs2CO3 is 2:2:0.

5.

4. The method for preparing a two-dimensional germanium-based halide perovskite antiferroelectric material according to claim 3, characterized in that: The clarified solution obtained in step (2) was cooled from 70-80℃ to 20-30℃ at a rate of 0.5-2℃ / day to obtain a bulk two-dimensional germanium-based halide perovskite antiferroelectric material.

5. An application of a two-dimensional germanium-based halide perovskite antiferroelectric material, characterized in that: The two-dimensional germanium-based halide perovskite antiferroelectric material as described in claim 1 or 2 is used to prepare energy storage devices.

6. An energy storage device, characterized in that: It is prepared from the two-dimensional germanium-based halide perovskite antiferroelectric material as described in claim 1 or 2.

7. A dielectric switch, characterized in that: It is prepared from the two-dimensional germanium-based halide perovskite antiferroelectric material as described in claim 1 or 2.

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