Single-layer niobium carbide-doped polymer solid-state electrolyte, and preparation method and application thereof

Abstract

The present application relates to a kind of single-layer niobium carbide incorporated polymer solid electrolyte and its preparation method and application, single-layer niobium carbide is mixed with polymer solution, single-layer niobium carbide is uniformly dispersed in polymer solution by shear force, mixed solution is prepared into film, and single-layer niobium carbide incorporated polymer solid electrolyte is prepared after one-step drying.The single-layer niobium carbide incorporated polymer solid electrolyte prepared has good ionic conductive performance and mechanical strength, and also has higher chemical stability and high-temperature resistance performance.Application in lithium ion battery shows excellent performance, such as high cycle performance, high specific capacity and the like.The preparation method provided by the present application is simple and easy to operate, and has higher practicality and economy.The preparation method and application of the single-layer niobium carbide incorporated polymer solid electrolyte provided by the present application have wide application prospect, and have important application value in the field of lithium ion battery, supercapacitor and the like.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology, and in particular to a monolayer niobium carbide-doped polymer solid electrolyte, its preparation method, and its application. Background Technology

[0002] With the increasing demand for portable electronic products in modern society, the development of battery technology has become increasingly important. Lithium-ion batteries have become one of the most popular types of batteries due to their high energy density, long lifespan, and good cycle performance. However, the liquid electrolyte in lithium-ion batteries can cause thermal runaway at high temperatures and is prone to leakage, which significantly impacts battery performance and safety. Therefore, researching and developing novel solid-state electrolytes to replace liquid electrolytes has become an important research direction in the field of lithium-ion batteries.

[0003] Solid-state electrolytes are solid materials with high ionic conductivity and chemical stability, as well as certain mechanical strength and thermal stability. Compared to traditional liquid electrolytes, solid-state electrolytes offer higher safety and a longer lifespan, effectively addressing safety issues encountered in lithium-ion battery use. Among them, polymer electrolytes (PEO) are a novel type of solid-state electrolyte for lithium-ion batteries, possessing excellent ionic conductivity and high mechanical strength, and can be used to improve the performance of lithium-ion batteries.

[0004] MXenes are novel two-dimensional materials. Due to their abundant surface functional groups and high specific surface area, they provide rich active sites and exhibit excellent catalytic activity and electrochemical energy storage properties. Niobium carbide MXenes, as members of the MXene family, have become a research hotspot due to their high conductivity, excellent mechanical properties, and high specific surface area. Secondly, batteries are indispensable energy storage and conversion devices in modern life. Traditional lithium-ion batteries have low energy density and limited lifespan, thus necessitating the development of novel electrode materials to improve battery performance.

[0005] Chinese patent CN202111148220.5 discloses a composite solid electrolyte, its preparation method, and its application. The composite solid electrolyte is prepared using niobium carbide nanosheets and polyethylene oxide (PEO) as raw materials, and is used in lithium-sulfur batteries. The composite solid electrolyte of this patent application, through the synergistic effect between niobium carbide nanosheets and polyethylene oxide, can improve the ionic conductivity and mechanical strength of PEO as a solid electrolyte, and can also effectively suppress the shuttle effect in lithium-sulfur batteries. However, the niobium carbide nanosheets in this patent have a multilayer structure. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects of the prior art by providing a single-layer niobium carbide-doped polymer solid electrolyte, its preparation method and application. This electrolyte is low in cost, simple to process, mild under mild conditions, and has high and very good cycle stability and rate performance.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A method for preparing a polymer solid electrolyte with monolayer niobium carbide doping, the specific steps of which are as follows:

[0009] S1. Preparation of monolayer niobium carbide (MXene).

[0010] S2. Prepare a PEO polymer solution;

[0011] S3. Add the monolayer niobium carbide (MXene) obtained in step S1 to the PEO polymer solution obtained in step S2 and sonicate to obtain mixed solution A;

[0012] S4. After drying the mixed solution A obtained in step S3, a single-layer niobium carbide-doped polymer solid electrolyte is obtained.

[0013] Further, in step S2, polyethylene oxide (PEO) is stirred evenly in deionized water, then lithium salt is added and fully dissolved to obtain a PEO polymer solution.

[0014] Furthermore, the lithium salt is lithium bis(trifluoromethanesulfonyl)imide (LiTFSi), and polyethylene oxide (PEO) is the substrate of the polymer solid electrolyte, mainly serving as a substrate. The addition of lithium salt can promote the decomposition of lithium salt, thereby enabling the transport of lithium ions.

[0015] Furthermore, the polyethylene oxide is in powder form.

[0016] Furthermore, the number average molecular weight of the polyethylene oxide is 600,000 to 100,000.

[0017] Furthermore, the concentration of the polyethylene oxide in the PEO polymer solution is 85% to 95%, preferably 90%.

[0018] Furthermore, the mass ratio of the lithium salt to polyethylene oxide is 1 to 1.5:10.

[0019] Furthermore, the stirring time is 12 to 24 hours.

[0020] Further, in step S3, the mass ratio of the monolayer niobium carbide to the polyethylene oxide in the PEO polymer solution is 1~2:10.

[0021] Further, in step S3, the monolayer niobium carbide (MXene) obtained in step S1 is added to the PEO polymer solution obtained in step S2, and the mixture is magnetically stirred and sonicated to obtain a mixed solution A.

[0022] Furthermore, the magnetic stirring time is 12-24 hours.

[0023] Furthermore, the ultrasound duration is 10-15 hours.

[0024] Further, in step S4, the mixed solution A obtained in step S4 is dropped onto a mold and dried to obtain a single layer of niobium carbide-doped polymer solid electrolyte.

[0025] Furthermore, the mold is a square mold made of polytetrafluoroethylene.

[0026] Furthermore, the drying time is 12-24 hours.

[0027] The present invention also provides a polymer solid electrolyte with monolayer niobium carbide incorporation, which is prepared by the above-described method for preparing polymer solid electrolyte with monolayer niobium carbide incorporation.

[0028] Furthermore, the polymer solid electrolyte incorporating the monolayer niobium carbide is a uniformly dispersed, flat, and saturated black film, with the monolayer niobium carbide structure uniformly dispersed within it.

[0029] In addition, the present invention also provides a lithium-ion battery comprising the above-mentioned polymer solid electrolyte incorporating a single layer of niobium carbide.

[0030] The principle of this invention is as follows:

[0031] Niobium carbide (MXene) is an emerging two-dimensional material with excellent electrical conductivity, mechanical strength, and chemical stability. Polyethylene oxide (PEO) is a polymer compound with excellent lithium-ion conductivity. Combining these two materials can produce PEO-based solid electrolytes with good electrochemical performance, showing potential for application in energy storage fields such as lithium-ion batteries. The preparation of PEO-based solid electrolytes requires the composite formation of niobium carbide (MXene) and PEO, and the optimal electrochemical performance is achieved by controlling the composite method and composition. Studies have shown that adding a small amount of niobium carbide (MXene) to PEO-based solid electrolytes can significantly improve the ionic conductivity of the electrolyte, while also enhancing its mechanical strength and chemical stability. Furthermore, niobium carbide (MXene) can also serve as an electrode material for lithium-ion batteries, improving their energy density and cycle performance. Therefore, due to its intrinsic two-dimensional nanolayered structure, good hydrophilicity, excellent electrical conductivity, and mechanical properties, MXene-based materials are widely used in electrode composites for energy storage and conversion, showing broad application prospects in numerous fields such as lithium-ion batteries, supercapacitors, and photocatalyst electrodes.

[0032] This invention provides a composite polymer solid electrolyte material obtained by adding a single layer of niobium carbide (MXene) to a PEO polymer solid with uniform dispersion and no stacking. This material can improve the originally insufficient cycle stability and increase its ionic conductivity, giving it better electrochemical performance.

[0033] Compared to multilayer niobium carbide nanosheets, monolayer niobium carbide exhibits higher electrical conductivity, which can improve ion mobility and conductivity in the electrolyte, thereby enhancing battery performance. Monolayer niobium carbide can also improve the electrochemical stability of the battery; incorporating a small amount of monolayer niobium carbide into PEO-based solid electrolytes can enhance electrochemical stability due to its high chemical stability, preventing electrolyte-electrode reactions and reducing electrode / electrolyte interface resistance. Furthermore, monolayer niobium carbide can improve the mechanical strength of the battery. PEO polymer solid electrolytes are typically fragile and prone to breakage; incorporating monolayer niobium carbide into the electrolyte can increase its mechanical strength, thus improving battery durability and reliability. Monolayer niobium carbide also possesses good thermal stability, protecting the PEO polymer solid electrolyte in the battery from decomposition due to high temperatures and extending battery life. It can also effectively suppress thermal runaway, reducing the risk of spontaneous combustion and explosion, and improving battery safety.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. This invention involves mixing niobium carbide and PEO and then drying the mixture on a mold to obtain a uniformly dispersed single-layer niobium carbide-filled PEO polymer solid electrolyte. The method is simple, and the prepared single-layer niobium carbide-infused polymer solid electrolyte has good ionic conductivity and mechanical strength, as well as high chemical stability and high temperature resistance.

[0036] 2. This invention uses niobium carbide as a filler, which allows for the design of raw materials and has a wide range of applications. Furthermore, monolayer niobium carbide can improve the originally insufficient cycle stability and increase its ionic conductivity, giving it better electrochemical performance.

[0037] 3. The self-assembled composite polymer solid electrolyte material prepared by the method of the present invention, in which monolayer niobium carbide is added as a filler, can significantly improve its electrochemical performance and enhance the ionic conductivity and mechanical strength of the solid electrolyte.

[0038] 4. PEO (polyethylene glycol) is a commonly used solid electrolyte material with advantages such as high ionic conductivity, chemical stability, and thermal stability. Studies have shown that niobium carbide (MXene), as an additive to PEO solid electrolytes, can significantly improve the ionic conductivity and mechanical strength of the electrolyte, and enhance electrochemical stability. Specifically, niobium carbide (MXene) can act as a conductive filler; adding it to PEO electrolytes can increase the electrolyte's conductivity, thereby improving the battery's energy density and power density. Furthermore, niobium carbide (MXene) can also improve the mechanical properties of PEO electrolytes, enhancing their strength and toughness, reducing stress deformation and damage during charge and discharge processes, thus extending battery life and cycle stability.

[0039] 5. Monolayer niobium carbide-doped polymer solid electrolytes have shown excellent performance in lithium-ion battery applications, such as high cycle performance and high specific capacity. Therefore, this electrolyte has broad application prospects and important application value in lithium-ion batteries, supercapacitors and other fields. Attached Figure Description

[0040] Figure 1 SEM image of the surface of pure PEO polymer solid electrolyte;

[0041] Figure 2 SEM image of a monolayer niobium carbide surface;

[0042] Figure 3 This is a SEM image of the polymer solid electrolyte with monolayer niobium carbide doping obtained in Example 1;

[0043] Figure 4 This is a cross-sectional SEM image of the polymer solid electrolyte with monolayer niobium carbide doping obtained in Example 1;

[0044] Figure 5 The XRD comparison diagrams are of the pure PEO film obtained in Comparative Example 1, the pure PEO polymer solid electrolyte containing lithium salt obtained in Comparative Example 2, and the monolayer niobium carbide-doped polymer solid electrolyte obtained in Example 1.

[0045] Figure 6 A comparison diagram of tensile stress between the pure PEO polymer solid electrolyte obtained in Comparative Example 3 and the monolayer niobium carbide-doped polymer solid electrolyte material obtained in Example 1.

[0046] Figure 7 This is a schematic diagram of the structure for testing the ionic conductivity of a multilayer niobium carbide-doped polymer solid electrolyte material.

[0047] Figure 8 This is a schematic diagram of the test structure for the ionic conductivity of a polymer solid electrolyte material doped with monolayer niobium carbide. Detailed Implementation

[0048] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0049] Example 1

[0050] This embodiment provides a method for preparing a polymer solid electrolyte with monolayer niobium carbide incorporation, the specific steps of which are as follows:

[0051] Step 1: Preparation of monolayer niobium carbide (MXene).

[0052] Step 2: Preparation of PEO polymer solution:

[0053] 600 mg of polyethylene oxide (PEO) was mixed and stirred in deionized water for 12 h, then 60 mg of LiTFSi was added, and the mixture was sonicated to dissolve it completely to obtain a PEO polymer solution, wherein the concentration of polyethylene oxide in the PEO polymer solution was 90%.

[0054] Step 3: Preparation of a monolayer niobium carbide-doped polymer solid electrolyte:

[0055] The 60 mg of monolayer niobium carbide obtained in the first step was added to the PEO polymer solution obtained in the second step and sonicated to obtain mixed solution A. Mixed solution A was dropped onto a polytetrafluoroethylene grid mold and dried to obtain surfactant-modified MXene / polymer solid electrolyte, as shown in the morphology image. Figure 3 and Figure 4 As shown.

[0056] Example 2

[0057] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the amount of niobium fluoride added in the first step is 50 mg.

[0058] Example 3

[0059] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the amount of niobium fluoride added in the first step is 70 mg.

[0060] Comparative Example 1

[0061] This comparative example uses pure PEO film.

[0062] Comparative Example 2

[0063] This comparative example uses a pure PEO polymer solid electrolyte containing lithium salt.

[0064] Comparative Example 3

[0065] This comparative example uses a pure PEO polymer solid electrolyte.

[0066] Conclusion Analysis

[0067] Figure 1 The image shows the surface of a pure PEO polymer solid electrolyte, which clearly shows that the surface is uneven and has many pores. Figure 2 The image shows a SEM image of a single-layer niobium carbide surface, from which a standard two-dimensional section can be seen. Figure 3 The image shows a SEM image of the polymer solid electrolyte with monolayer niobium carbide doping obtained in Example 1, which shows that the surface is very smooth and uniform. Figure 4 The image shows a cross-sectional SEM image of the polymer solid electrolyte with monolayer niobium carbide doping obtained in Example 1, which shows that the cross-section is very full.

[0068] Figure 5 The XRD comparison diagrams of the pure PEO film obtained in Comparative Example 1, the pure PEO polymer solid electrolyte containing lithium salt obtained in Comparative Example 2, and the polymer solid electrolyte with monolayer niobium carbide doping obtained in Example 1 show that the crystallinity is significantly reduced after the addition of niobium carbide, which is beneficial to the decomposition of lithium salt and thus improves ionic conductivity and overall performance.

[0069] Figure 6 The tensile stress comparison diagram of the pure PEO polymer solid electrolyte obtained in Comparative Example 3 and the monolayer niobium carbide-doped polymer solid electrolyte material obtained in Example 1 shows that the elasticity and strain capacity are greatly improved after the addition of niobium carbide, which is beneficial to improving the overall safety of lithium batteries.

[0070] Figure 7This is a schematic diagram of the structure for testing the ionic conductivity of a multilayer niobium carbide-doped polymer solid electrolyte material. Figure 8 This is a schematic diagram of the test structure for the ionic conductivity of a monolayer niobium carbide-doped polymer solid electrolyte material, compared with... Figure 7 and Figure 8 It can be seen that the ionic conductivity of polymer solid electrolyte materials doped with monolayer niobium carbide is lower than that of polymer solid electrolyte materials doped with multilayer niobium carbide. Therefore, compared with multilayer niobium carbide nanosheets, monolayer niobium carbide has high conductivity, which can improve the mobility and conductivity of ions in the electrolyte and thus improve the performance of the battery.

[0071] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a polymer solid electrolyte with monolayer niobium carbide doping, characterized in that, The specific steps are as follows: S1. Preparation of monolayer niobium carbide; S2. Prepare a PEO polymer solution; S3. Add the monolayer niobium carbide obtained in step S1 to the PEO polymer solution obtained in step S2 and sonicate to obtain mixed solution A; S4. After drying the mixed solution A obtained in step S3, a single-layer niobium carbide-doped polymer solid electrolyte is obtained.

2. The method for preparing a single-layer niobium carbide-doped polymer solid electrolyte according to claim 1, characterized in that, In step S2, polyethylene oxide is stirred evenly in deionized water, then lithium salt is added and fully dissolved to obtain a PEO polymer solution.

3. The method for preparing a single-layer niobium carbide-doped polymer solid electrolyte according to claim 2, characterized in that, The lithium salt is lithium bis(trifluoromethanesulfonyl)imide. The polyethylene oxide is in powder form. The number-average molecular weight of the polyethylene oxide is 600,000 to 100,000. The concentration of polyethylene oxide in the PEO polymer solution is 85%~95%. The mass ratio of the lithium salt to polyethylene oxide is 1~1.5:

10. The stirring time is 12-24 hours.

4. The method for preparing a single-layer niobium carbide-doped polymer solid electrolyte according to claim 1, characterized in that, In step S3, the mass ratio of the monolayer niobium carbide to the polyethylene oxide in the PEO polymer solution is 1~2:10; The monolayer niobium carbide obtained in step S1 is added to the PEO polymer solution obtained in step S2, and the mixture is magnetically stirred and sonicated to obtain a mixed solution A. The magnetic stirring time is 12-24 hours, and the ultrasonic time is 10-15 hours.

5. The method for preparing a single-layer niobium carbide-doped polymer solid electrolyte according to claim 1, characterized in that, In step S4, the mixed solution A obtained in step S4 is dropped onto a mold and dried to obtain a monolayer niobium carbide-doped polymer solid electrolyte. The mold is a square mold made of polytetrafluoroethylene. The drying time is 12-24 hours.

6. A single-layer niobium carbide-doped polymer solid electrolyte, characterized in that, It was prepared using the method for preparing a single-layer niobium carbide-doped polymer solid electrolyte as described in any one of claims 1-5.

7. The polymer solid electrolyte with monolayer niobium carbide incorporation according to claim 6, characterized in that, The polymer solid electrolyte incorporating the monolayer niobium carbide is a uniformly dispersed, flat, and full black film, with the monolayer niobium carbide structure uniformly dispersed within it.

8. A lithium-ion battery, characterized in that, Including the polymer solid electrolyte with monolayer niobium carbide doping as described in claim 6 or claim 7.

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