Preparation method of flexible porous electrode based on two-dimensional thiophosphate

Abstract

The invention relates to the field of lithium ion batteries, in particular to a preparation method of a flexible porous electrode based on two-dimensional thiophosphate. Two-dimensional thiophosphate (2D MPS3) is used as an active substance, single-walled carbon nanotubes (SWCNTs) are used as a conductive agent, and a melamine porous body is used for providing support for the electrode; the preparation method comprises the following steps: (1) uniformly mixing a 2D MPS3 colloidal solution with SWCNTs slurry; (2) dropwise adding a mixed colloidal solution composed of the 2D MPS3 colloidal solution and the SWCNTs slurry into the melamine porous body; and (3) directly carrying out vacuum drying on the melamine porous body loaded with the mixed colloidal solution at room temperature, wherein the obtained flexible porous electrode shows good electrochemical performance. The preparation method has the advantages of simple process, low cost, easiness in scale amplification and the like, and lays a foundation for application of 2DMPS3 in the flexible lithium ion battery.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion batteries, and specifically to a method for preparing a flexible porous electrode based on two-dimensional thiophosphate (2D MPS3). Background Technology

[0002] Compared to traditional rechargeable batteries, lithium-ion batteries have advantages such as high energy density, long cycle life, low self-discharge, and good safety, leading to their widespread application. In recent years, the rapid development of flexible electronic devices has spurred demand for flexible lithium-ion batteries. Developing high-performance flexible electrodes is a crucial prerequisite for the fabrication of flexible lithium-ion batteries. Currently, mainstream lithium-ion battery electrodes are generally fabricated by coating a slurry containing active materials onto a metal current collector. This method cannot guarantee effective electrical contact between the active material and the current collector during repeated deformation, making it unsuitable for direct application in flexible lithium-ion batteries. Two-dimensional materials, due to their thickness being much smaller than the other two dimensions, can be easily fabricated into various electrode structures such as thin films, porous bodies, and hollow spheres, demonstrating great flexibility in electrode structure design. Two-dimensional thiophosphates, utilizing the alloying reaction between phosphorus (P) and sulfur (S) elements and lithium ions, exhibit high theoretical specific capacity, showing promising application prospects as a negative electrode material for flexible lithium-ion batteries. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing flexible porous electrodes based on two-dimensional thiophosphate, which solves the problem that electrodes prepared by traditional coating processes are difficult to apply to flexible lithium-ion batteries, and realizes the preparation of high-capacity flexible lithium-ion battery anodes.

[0004] The technical solution of this invention:

[0005] A method for preparing a flexible porous electrode based on two-dimensional thiophosphate uses 2D MPS3 as the active material, SWCNTs as the conductive agent, and melamine porous bodies to provide support for the electrode.

[0006] The preparation method includes the following steps:

[0007] (1) Mix the 2D MPS3 colloidal solution with the SWCNTs slurry evenly;

[0008] (2) A mixed colloidal solution consisting of 2D MPS3 colloidal solution and SWCNTs slurry was added dropwise to the melamine porous body;

[0009] (3) The melamine porous body loaded with the mixed colloidal solution was directly vacuum dried at room temperature.

[0010] The method for preparing flexible porous electrodes based on two-dimensional thiophosphates, wherein the element M is one or a combination of two or more of Mn, Fe, Co, Ni, Cu, Zn, Sn, and Cd.

[0011] The method for preparing a flexible porous electrode based on two-dimensional thiophosphate, in step (1), the specific preparation process of the 2D MPS3 colloidal solution is as follows: First, a high-concentration 2D MnPS3 colloidal solution is obtained by controlling the amount of 2D MnPS3 and deionized water used. After determining the required concentration of the 2D MnPS3 colloidal solution, the concentration of the 2D MnPS3 colloidal solution is controlled to the specified concentration by adding deionized water. In the 2D MPS3 colloidal solution, the concentration range of 2D MPS3 is 1-40 mg / mL. -1 The rest is deionized water.

[0012] In the method for preparing flexible porous electrodes based on two-dimensional thiophosphate, in step (1), the SWCNTs slurry is obtained by ultrasonically dispersing SWCNTs in deionized water. The composition of the SWCNTs slurry by mass percentage is as follows: SWCNTs content is 0.1-2%, sodium carboxymethyl cellulose content is 0.4-0.8%, and the remainder is deionized water.

[0013] In the method for preparing flexible porous electrodes based on two-dimensional thiophosphate, in step (1), the SWCNTs content in the SWCNTs slurry is 0.5% to 20% of the mass of the 2D MPS3 colloidal solution. The SWCNTs slurry is dispersed in the 2D MPS3 colloidal solution by ultrasound, with an ultrasound power of 10 to 500W and an ultrasound time of 1 min to 5 h.

[0014] In the method for preparing flexible porous electrodes based on two-dimensional thiophosphate, in step (2), the thickness of the melamine porous body is 0.5-20 mm, the porosity is 99%, and the average pore size is 90 μm.

[0015] In the method for preparing flexible porous electrodes based on two-dimensional thiophosphate, in step (3), after the mixed colloidal solution is added dropwise to the melamine porous body, it is immediately transferred to a vacuum drying device for vacuum drying at room temperature, with a vacuum pressure of 10. -2 ~10 3 Pa.

[0016] In the method for preparing a flexible porous electrode based on two-dimensional thiophosphate, in step (3), after vacuum drying, 2D MPS3 and SWCNTs are loaded onto a melamine porous body. The content of 2D MPS3 in the flexible porous electrode is 10-80 wt%, and the content of SWCNTs in the flexible porous electrode is 0.05-16 wt%.

[0017] The design concept of this invention:

[0018] Using 2D MPS3-type materials with high lithium storage performance and flexibility as active materials, SWCNTs as conductive agents, and melamine porous bodies as electrode support, the flexible electrode prepared by the present invention exhibits high lithium storage performance by using a vigorous vaporization process of vacuum drying in liquid state to aggregate 2D MPS3 and SWCNTs into bundles and form a unique pore structure.

[0019] The advantages and beneficial effects of this invention are:

[0020] This invention uses two-dimensional thiophosphate (2D MPS3) as the active material, single-walled carbon nanotubes (SWCNTs) as the conductive agent, and melamine porous bodies to provide electrode support. A mixed colloidal solution consisting of 2D MPS3 colloidal solution and SWCNTs slurry is dropwise added to the melamine porous body and then directly vacuum-dried at room temperature. The resulting flexible porous electrode exhibits excellent electrochemical performance. This invention features a simple preparation process, low cost, and ease of scalability. The 2D MPS3-based flexible anode prepared using this invention exhibits excellent lithium storage performance. Attached Figure Description

[0021] Figure 1 Image a is an optical photograph of a spread flexible porous electrode, and image b is an optical photograph of a folded flexible porous electrode.

[0022] Figure 2 a) shows the scanning morphology of the flexible porous electrode at low magnification, and b) shows its corresponding energy spectrum elemental distribution.

[0023] Figure 3 The image shows the scanning morphology of the flexible porous electrode under high magnification. In the image, b is a magnified view of a.

[0024] Figure 4 This figure shows the rate performance curves of the flexible porous electrode. In the figure, the horizontal axis represents the cycle number, and the vertical axis (left) represents the specific capacity for charge and discharge (mAh / g). -1 The vertical axis (right) represents Coulombic efficiency (%). Detailed Implementation

[0025] The feasibility of the present invention will be further demonstrated below through examples.

[0026] Example

[0027] This embodiment uses 2D MnPS3 as an example (M = Mn) to introduce the fabrication method of a porous flexible electrode based on 2D MPS3, including the following steps:

[0028] (1) Through K + With Li + Intercalation-assisted ultrasonic exfoliation of layered MnPS3 powder yielded a 2D MnPS3 colloidal solution, with the 2D MnPS3 concentration prepared to 20 mg / mL. -1 The specific preparation process is as follows: First, a high-concentration 2D MnPS3 colloidal solution (20-50 mg / mL) is obtained by controlling the amount of 2D MnPS3 and deionized water used. -1 After determining the required concentration of the 2D MPS3 colloidal solution, deionized water was added to control the concentration to 20 mg / mL. -1 .

[0029] (2) SWCNTs slurry is obtained by ultrasonically dispersing SWCNTs in deionized water. The composition of SWCNTs slurry by mass percentage is as follows: SWCNTs content is 0.4%, sodium carboxymethyl cellulose content is 0.6%, and the remainder is deionized water.

[0030] (3) Mix 3 mL of 2D MnPS3 colloidal solution and 200 mg of SWCNTs slurry by ultrasonic cell disruptor. The ultrasonic power is 50 W and the ultrasonic time is 10 min.

[0031] (4) Cut melamine porous bodies with dimensions of 80mm×40mm×1mm, porosity of 99%, and average pore size of 90μm.

[0032] (5) 3 mL of colloidal solution containing 2D MnPS3 and SWCNTs was added dropwise onto the melamine porous body and immediately transferred to a vacuum dryer for vacuum drying to remove moisture. The vacuum pressure was about 1 Pa. After vacuum drying, 2D MPS3 and SWCNTs were loaded onto the melamine porous body. The content of 2D MPS3 in the flexible porous electrode was 61.7 wt%, and the content of SWCNTs in the flexible porous electrode was 0.8 wt%.

[0033] The obtained 2D MPS3 porous flexible electrode was dried at 60°C to further remove moisture. The electrode was cut into 12mm diameter discs and assembled into button cells in an argon-atmospheric glove box. A lithium sheet was used as the counter electrode, and a Celgard 2500 type battery separator was used, containing 1 mol / L... -1 A solution of ethylene carbonate and diethyl carbonate (volume ratio 1:1) of LiPF6 was used as the electrolyte.

[0034] like Figure 1 As shown in (ab), the prepared 2D MPS3 porous flexible electrode exhibits good flexibility.

[0035] like Figure 2 As shown in Figure a, the low-magnification scanning electron microscope image reveals that the polygonal framework is a porous melamine structure, with the spaces between the framework filled with an active material composed of 2D MnPS3 and SWCNTs. Figure 2 As shown in b, the corresponding energy spectrum elemental distribution diagram shows that Mn, P, and S elements are uniformly distributed in the electrode material. The positions in the electrode where Mn, P, and S elements are scarce but C element content is high correspond to the melamine skeleton.

[0036] like Figure 3 The image shown is a scanning electron microscope image of a flexible porous electrode at high magnification. Figure 3 a indicates that its structure contains abundant micron-sized porous structures, providing channels for ion migration and space for volume expansion during the lithiation process. Figure 3 In b, it can be observed that the SWCNTs bundles are distributed in the electrode material, which improves the electrode conductivity.

[0037] like Figure 4 As shown in the figure, the rate performance curve of the electrode prepared above is shown at 0.1 Ag. -1 At the given current density, the first-cycle discharge specific capacity is 1191.4 mAh g. -1 The charging specific capacity is 1002.4mAh g. -1 The initial coulomb efficiency reached 84.1%. This was achieved at values ​​of 0.2, 0.5, 1, 2, and 5 Ag. -1 At current densities of [specific values], their discharge specific capacities can reach 934.6, 824.1, 653.3, 375.1, and 177.3 mAh g, respectively. -1 This demonstrates a bright future as a negative electrode material for flexible lithium-ion batteries.

Claims

1. A method for preparing a flexible porous electrode based on two-dimensional thiophosphate, characterized in that, 2D MPS3 was used as the active material, SWCNTs were used as the conductive agent, and melamine porous bodies were used to provide support for the electrode. The preparation method includes the following steps: (1) Mix the 2D MPS3 colloidal solution with the SWCNTs slurry evenly; (2) A mixed colloidal solution consisting of 2D MPS3 colloidal solution and SWCNTs slurry was added dropwise to the melamine porous body; (3) The melamine porous body loaded with the mixed colloidal solution was directly vacuum dried at room temperature.

2. The method for preparing a flexible porous electrode based on two-dimensional thiophosphate according to claim 1, characterized in that, The element M is one or more of the following: Mn, Fe, Co, Ni, Cu, Zn, Sn, and Cd.

3. The method for preparing a flexible porous electrode based on two-dimensional thiophosphate according to claim 1, characterized in that, In step (1), the specific preparation process of the 2D MPS3 colloidal solution is as follows: First, a high-concentration 2D MnPS3 colloidal solution is obtained by controlling the amount of 2D MnPS3 and deionized water used. After determining the required concentration of the 2D MPS3 colloidal solution, the concentration of the 2D MnPS3 colloidal solution is controlled to the specified concentration by adding deionized water. In the 2D MPS3 colloidal solution, the concentration range of 2D MPS3 is 1-40 mg / mL. -1 The rest is deionized water.

4. The method for preparing a flexible porous electrode based on two-dimensional thiophosphate according to claim 1, characterized in that, In step (1), the SWCNTs slurry is obtained by ultrasonically dispersing SWCNTs in deionized water. The composition of the SWCNTs slurry by mass percentage is as follows: SWCNTs content is 0.1-2%, sodium carboxymethyl cellulose content is 0.4-0.8%, and the remainder is deionized water.

5. The method for preparing a flexible porous electrode based on two-dimensional thiophosphate according to claim 1, characterized in that, In step (1), the SWCNTs content in the SWCNTs slurry is 0.5% to 20% of the mass of the 2D MPS3 colloidal solution. The SWCNTs slurry is dispersed in the 2D MPS3 colloidal solution by ultrasound, with an ultrasound power of 10 to 500W and an ultrasound time of 1 min to 5 h.

6. The method for preparing a flexible porous electrode based on two-dimensional thiophosphate according to claim 1, characterized in that, In step (2), the thickness of the melamine porous body is 0.5-20 mm, the porosity is 99%, and the average pore size is 90 μm.

7. The method for preparing a flexible porous electrode based on two-dimensional thiophosphate according to claim 1, characterized in that, In step (3), after the mixed colloidal solution is added dropwise to the melamine porous body, it is immediately transferred to a vacuum drying device for vacuum drying at room temperature with a vacuum pressure of 10. -2 ~10 3 Pa.

8. The method for preparing a flexible porous electrode based on two-dimensional thiophosphate according to claim 1, characterized in that, In step (3), after vacuum drying, 2DMPS3 and SWCNTs are loaded onto the melamine porous body. The content of 2DMPS3 in the flexible porous electrode is 10-80 wt%, and the content of SWCNTs in the flexible porous electrode is 0.05-16 wt%.

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