Solid electrolyte membrane with shape memory and self-healing functions and preparation method thereof

Abstract

The invention discloses a solid electrolyte membrane with shape memory and self-healing functions and a preparation method thereof. According to the solid electrolyte membrane, an NCO-PEG-NCO precursor generated by reaction of polyethylene glycol and hexamethylene diisocyanate reacts with tetrafluorophenyl carbamate, and polyurethane is prepared to serve as a base material. And then adding a lithium salt into the matrix material to improve the ionic conductivity and form the slurry suitable for ink direct writing printing. The slurry is accurately deposited on a base material through an ink direct-writing printing technology, and the solid electrolyte membrane with the required shape and thickness is prepared. The solid electrolyte membrane has excellent shape memory effect and self-healing capability, can recover to a preset shape under external stimulation, and repairs the structure and function through a self-healing mechanism after being damaged. The novel solid electrolyte membrane has a wide application prospect in a high-performance lithium battery and other electrochemical energy storage devices, and can remarkably improve the safety and prolong the service life of the battery.

Description

Technical Field

[0001] The present invention belongs to the cross - technical field of the design and preparation of intelligent materials and energy storage materials, and particularly relates to a solid electrolyte membrane with shape - memory and self - healing functions and a preparation method thereof. Background Art

[0002] Traditional battery technologies have been facing challenges in terms of safety and reliability. Common liquid electrolytes have serious safety hazards during battery use. The electrolyte is prone to leakage and explosion accidents, thus posing a major threat to personal and property safety. At the same time, liquid electrolytes are also prone to polarization and degradation during charge and discharge processes, resulting in a gradual decline in battery performance and a shortened service life. These key problems severely restrict the further development and wide application of battery technologies. Therefore, solid electrolyte materials with high safety have gradually become a research hotspot. Compared with liquid electrolytes, solid electrolytes have advantages such as high safety, good heat resistance, and flexibility, and these characteristics are expected to significantly improve the safety and service life of batteries. Currently, ceramic solid electrolytes and polymer solid electrolytes are the main research directions. However, these solid electrolytes usually have deficiencies such as low ionic conductivity and complex preparation processes, so it is difficult to meet the requirements of practical applications.

[0003] In addition, batteries are easily affected by external conditions such as mechanical stress and heat during use, resulting in deformation, cracks, and damage. These structural defects will further deteriorate the battery performance and shorten its service life. Therefore, intelligent materials with shape - memory and self - healing functions have attracted wide attention, and they can effectively repair the defects in the battery structure and extend the service life of the battery.

[0004] It is worth noting that traditional battery manufacturing processes have problems such as poor batchability and low manufacturing efficiency. Emerging digital manufacturing technologies, such as ink - jet direct writing printing technology, are expected to achieve precise forming and rapid manufacturing of battery components, improving the production efficiency of batteries. This advanced manufacturing technology provides a new solution for the large - scale development of the battery industry.

[0005] Therefore, developing a solid electrolyte membrane with shape - memory and self - healing functions and a preparation method thereof is undoubtedly a key technical direction for improving battery performance and stability. The cross - combination of this energy storage material and intelligent material, and the use of advanced digital manufacturing processes for mass production can not only effectively prevent battery safety accidents, but also autonomously repair structural defects and maintain the optimal geometric shape of the electrolyte membrane, laying a foundation for the wide application of electrochemical energy storage devices. Summary of the Invention

[0006] In order to solve the above problems, the purpose of the present invention is to provide a solid electrolyte membrane with shape - memory and self - healing functions and a preparation method thereof.

[0007] To achieve the above object, the solid electrolyte membrane with shape memory and self-healing functions provided by the present invention uses polyurethane as the matrix material and lithium salt as the auxiliary material; wherein the polyurethane contains NCO-PEG-NCO precursor and tetrafluorophenyl carbamate; the NCO-PEG-NCO precursor is formed by the polycondensation reaction of polyethylene glycol (PEG) and hexamethylene diisocyanate (HDI); subsequently, the NCO-PEG-NCO precursor and tetrafluorophenyl carbamate (TAPB) are cross-linked to obtain a slurry of polyurethane, and the slurry of polyurethane is then mixed with lithium salt to prepare a printable 3D ink. Finally, through the inkjet printing technology, a solid electrolyte membrane with shape memory and self-healing functions and the required shape and thickness is prepared.

[0008] The molar ratio of the hexamethylene diisocyanate to the polyethylene glycol is 1.1-1.5:0.9-1.1.

[0009] The molar ratio of the NCO-PEG-NCO precursor to the tetrafluorophenyl carbamate is 0.9-1.1:0.9-1.2.

[0010] The mass ratio of the slurry of polyurethane to the lithium salt is 15-20:1, and the lithium salt is selected from any one of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium chlorate (LiClO 4 ).

[0011] The preparation method of the solid electrolyte membrane with shape memory and self-healing functions provided by the present invention includes the following steps carried out in sequence:

[0012] 1) Preparation of NCO-PEG-NCO precursor solution: Dry the polyethylene glycol powder in an oven at 80 °C for at least 24 hours for standby; weigh the polyethylene glycol powder and dissolve it in the hexamethylene diisocyanate solution in small portions multiple times, and then stir well at 60-80 °C for 3-4 hours until the polyethylene glycol powder is completely dissolved to prepare a solution of NCO-PEG-NCO precursor 4, wherein the molar ratio of the hexamethylene diisocyanate to the polyethylene glycol is 1.1-1.5:0.9-1.1, and store it in the dark after sealing with plastic wrap.

[0013] 2) Preparation of polyurethane slurry: Dry the tetrafluorophenyl carbamate powder in an oven at 80 °C for at least 24 hours for later use; Weigh the tetrafluorophenyl carbamate powder and dissolve it in small portions multiple times in the solution of the NCO-PEG-NCO precursor prepared in step 1), and stir well at room temperature for 4 - 8 hours until the tetrafluorophenyl carbamate powder is completely dissolved to prepare the polyurethane slurry, where the molar ratio of the NCO-PEG-NCO precursor to tetrafluorophenyl carbamate is 0.9 - 1.1:0.9 - 1.2. Seal it with plastic wrap and store it away from light and heat;

[0014] 3) Preparation of 3D ink: Dry the lithium salt in an oven at 80 °C for at least 24 hours for later use; Weigh the lithium salt and dissolve it in small portions multiple times in the polyurethane slurry prepared in step 2), and stir well at room temperature for 1 - 2 hours until the lithium salt is evenly mixed to prepare the 3D ink, where the mass ratio of the polyurethane slurry to the lithium salt is 15 - 20:1. Seal it with plastic wrap and store it away from light and heat;

[0015] 4) Inject the 3D ink prepared in step 3) into the injection barrel of an inkjet direct writing printer, and perform inkjet direct writing printing on the printing platform according to the designed pattern and shape to prepare the electrolyte wet film. After printing, adjust the temperature of the printing platform to 60 °C, dry the electrolyte wet film and remove it from the printing platform, thereby preparing a solid electrolyte membrane with shape memory and self-healing functions.

[0016] The printing pressure of the inkjet direct writing printer is 350 psi, and the printing thickness is 50 - 150 μm.

[0017] Compared with the prior art, the solid electrolyte membrane with shape memory and self-healing functions provided by the present invention and its preparation method have the following beneficial effects:

[0018] This solid electrolyte membrane uses a polyurethane matrix and endows excellent shape memory effect through chemical reactions, enabling it to return to the preset shape under external stimuli; at the same time, the polymer segments inside the membrane material also have the ability of self-repair, and can automatically reshape the structure after being damaged to achieve self-healing. In addition, adding lithium salt to the membrane material greatly improves the ionic conductivity. And this membrane adopts the preparation process of inkjet direct writing printing, which can precisely control the shape and thickness, and the process is simple and fast, which is conducive to large-scale production. This solid electrolyte membrane integrating shape memory, self-healing and high ionic conductivity can greatly improve the safety and service life of high-performance lithium batteries and other electrochemical energy storage devices, so it has broad application prospects in related fields. Brief Description of the Drawings

[0019] Figure 1 is a schematic diagram of the solid electrolyte membrane with shape memory and self-healing functions provided by the present invention:

[0020] Figure 2 It is a schematic diagram of the structure of the inkjet printer used in the present invention:

[0021] Figure 3 It is a schematic diagram of the shape memory function of the solid electrolyte membrane provided by the present invention:

[0022] Figure 4 It is a schematic diagram of the self-healing function of the solid electrolyte membrane provided by the present invention: Specific embodiments

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] As Figure 1 shown, the solid electrolyte membrane with shape memory and self-healing functions provided by the present invention uses polyurethane 1 as the matrix material and lithium salt 2 as the auxiliary material; wherein polyurethane 1 contains NCO-PEG-NCO precursor 4 and tetrafluorophenyl carbamate 5; NCO-PEG-NCO precursor 4 is produced by the polycondensation reaction of polyethylene glycol and hexamethylene diisocyanate; subsequently, NCO-PEG-NCO precursor 4 and tetrafluorophenyl carbamate 5 are cross-linked to obtain a slurry of polyurethane 1, and the slurry of polyurethane 1 is then mixed with lithium salt 2 to prepare a printable 3D ink. Through the inkjet printing technology, a solid electrolyte membrane with shape memory and self-healing functions having the required shape and thickness is prepared.

[0025] The molar ratio of the hexamethylene diisocyanate to the polyethylene glycol is 1.1-1.5:0.9-1.1.

[0026] The molar ratio of the NCO-PEG-NCO precursor 4 to the tetrafluorophenyl carbamate 5 is 0.9-1.1:0.9-1.2.

[0027] The mass ratio of the slurry of polyurethane 1 to the lithium salt 2 is 15-20:1, and the lithium salt is selected from any one of lithium bis(trifluoromethanesulfonyl)imide and lithium chlorate.

[0028] The shape memory and self-healing functions are provided by the hydrogen bond 3 formed by the cross-linking of amino groups and ester groups in the polyurethane molecular chain, wherein the ester group comes from the end of the NCO-PEG-NCO precursor, and the amino group comes from the end of the tetrafluorophenyl carbamate (TAPB). The hydrogen bond interaction between the ester group and the amino group endows the polyurethane (PU) matrix with shape memory and self-healing functions.

[0029] AsFigure 3 As shown, the shape memory function is manifested as the solid electrolyte membrane being fixed to its initial shape at 60°C for 10 minutes. When the temperature is changed or stress is applied, the membrane material is forced to deform into a temporary shape. When the condition returns to 60°C, the membrane material returns to its initial shape again.

[0030] As Figure 4 shown, the self-healing function is manifested as the solid electrolyte membrane with cracks or fractures under internal / external forces being repaired within 10 minutes at 60°C, and the self-healing efficiency can reach 85%-95%, greatly improving the working life of the electrolyte membrane. The rich and strong hydrogen bond effect in polyurethane can provide physical cross-linking. When the fractured surfaces come into contact again, this supramolecular cross-linking can repair the damaged interface.

[0031] Example 1:

[0032] The preparation method of the solid electrolyte membrane with shape memory and self-healing functions provided in this example includes the following steps carried out in sequence:

[0033] 1) Preparation of NCO-PEG-NCO precursor 4 solution: Dry polyethylene glycol (PEG) powder in an oven at 80°C for at least 24 hours for later use; weigh the polyethylene glycol powder and dissolve it in hexamethylene diisocyanate (HDI) solution in small portions multiple times, and then stir well at 60°C for 4 hours until the polyethylene glycol powder is completely dissolved. The molar ratio of hexamethylene diisocyanate (HDI) to polyethylene glycol (PEG) is 1.1:0.9. Seal it with plastic wrap and store it away from light.

[0034] 2) Preparation of polyurethane 1 slurry: Dry tetrafluorophenyl carbamate (TAPB) powder in an oven at 80°C for at least 24 hours for later use; weigh the tetrafluorophenyl carbamate (TAPB) powder and dissolve it in the solution of NCO-PEG-NCO precursor 4 prepared in step 1) in small portions multiple times, and stir well at room temperature for 5 hours until the tetrafluorophenyl carbamate powder is completely dissolved. The molar ratio of NCO-PEG-NCO precursor 4 to tetrafluorophenyl carbamate (TAPB) is 0.9:0.9. Seal it with plastic wrap and store it away from light and heat.

[0035] 3) Preparation of 3D ink: Dry lithium bis(trifluoromethanesulfonyl)imide in an oven at 80°C for at least 24 hours for later use; weigh lithium bis(trifluoromethanesulfonyl)imide and dissolve it in the slurry of polyurethane 1 prepared in step 2) in small portions multiple times, and stir well at room temperature for 1 hour until the lithium bis(trifluoromethanesulfonyl)imide is evenly mixed. The mass ratio of the slurry of polyurethane 1 to lithium bis(trifluoromethanesulfonyl)imide is 15:1. Seal it with plastic wrap and store it away from light and heat.

[0036] 4) Inject the 3D ink prepared in step 3) into as Figure 2In the injection barrel of the ink direct writing printer shown, adjust the printing pressure to 350 psi and the printing thickness to 50 μm. Conduct ink direct writing printing on the printing platform according to the designed pattern and shape to form an electrolyte wet film. After printing, adjust the temperature of the printing platform to 60 °C, dry the electrolyte wet film and remove it from the printing platform, thereby forming a solid electrolyte film with shape memory and self-healing functions.

[0037] Example 2:

[0038] The preparation method of the solid electrolyte film with shape memory and self-healing functions provided in this example includes the following steps carried out in sequence:

[0039] 1) Preparation of the NCO-PEG-NCO precursor 4 solution: Dry the polyethylene glycol (PEG) powder in an oven at 80 °C for at least 24 hours for later use; weigh the polyethylene glycol powder and dissolve it in the hexamethylene diisocyanate (HDI) solution in multiple small portions, and then stir well at 70 °C for 3.5 hours until the polyethylene glycol powder is completely dissolved. The molar ratio of hexamethylene diisocyanate (HDI) to polyethylene glycol (PEG) is 1.3:1.0. Seal it with plastic wrap and store it away from light.

[0040] 2) Preparation of the polyurethane 1 slurry: Dry the tetrafluorophenyl carbamate (TAPB) powder in an oven at 80 °C for at least 24 hours for later use; weigh the tetrafluorophenyl carbamate (TAPB) powder and dissolve it in the solution of the NCO-PEG-NCO precursor 4 prepared in step 1) in multiple small portions, and stir well at room temperature for 6 hours until the tetrafluorophenyl carbamate powder is completely dissolved. The molar ratio of the NCO-PEG-NCO precursor 4 to tetrafluorophenyl carbamate (TAPB) is 1.0:1.2. Seal it with plastic wrap and store it away from light and heat.

[0041] 3) Preparation of the 3D ink: Dry the lithium chlorate in an oven at 80 °C for at least 24 hours for later use; weigh the lithium chlorate and dissolve it in the polyurethane 1 slurry prepared in step 2) in multiple small portions, and stir well at room temperature for 1.5 hours until the lithium chlorate is evenly mixed. The mass ratio of the polyurethane 1 slurry to lithium chlorate is 18:1. Seal it with plastic wrap and store it away from light and heat.

[0042] 4) Inject the 3D ink prepared in step 3) into the injection barrel of the ink direct writing printer as Figure 2 shown, adjust the printing pressure to 350 psi and the printing thickness to 50 μm. Conduct ink direct writing printing on the printing platform according to the designed pattern and shape to form an electrolyte wet film. After printing, adjust the temperature of the printing platform to 60 °C, dry the electrolyte wet film and remove it from the printing platform, thereby forming a solid electrolyte film with shape memory and self-healing functions.

[0043] Example 3:

[0044] The preparation method of the solid electrolyte membrane with shape memory and self-healing functions provided in this example includes the following steps carried out in sequence:

[0045] 1) Preparation of the NCO-PEG-NCO precursor 4 solution: Dry the polyethylene glycol (PEG) powder in an oven at 80 °C for at least 24 hours for standby; weigh the polyethylene glycol powder and dissolve it in the hexamethylene diisocyanate (HDI) solution in small portions multiple times, and then stir well at 80 °C for 3 hours until the polyethylene glycol powder is completely dissolved, where the molar ratio of hexamethylene diisocyanate (HDI) to polyethylene glycol (PEG) is 1.5:0.9, seal it with plastic wrap and store it away from light.

[0046] 2) Preparation of the polyurethane 1 slurry: Dry the tetrafluorophenyl carbamate (TAPB) powder in an oven at 80 °C for at least 24 hours for standby; weigh the tetrafluorophenyl carbamate (TAPB) powder and dissolve it in the solution of the NCO-PEG-NCO precursor 4 prepared in step 1) in small portions multiple times, and stir well at room temperature for 8 hours until the tetrafluorophenyl carbamate powder is completely dissolved, where the molar ratio of the NCO-PEG-NCO precursor 4 to tetrafluorophenyl carbamate (TAPB) is 1.1:0.9, seal it with plastic wrap and store it away from light and heat.

[0047] 3) Preparation of the 3D ink: Dry the lithium chlorate in an oven at 80 °C for at least 24 hours for standby; weigh the lithium chlorate and dissolve it in the slurry of polyurethane 1 prepared in step 2) in small portions multiple times, and stir well at room temperature for 2 hours until the lithium chlorate is evenly mixed, where the mass ratio of the polyurethane 1 slurry to lithium chlorate is 20:1, seal it with plastic wrap and store it away from light and heat.

[0048] 4) Inject the 3D ink prepared in step 3) into the injection barrel of the ink direct writing printer as shown in Figure 2 . Adjust the printing pressure to 350 psi and the printing thickness to 50 μm, and perform ink direct writing on the printing platform according to the designed pattern and shape to make the electrolyte wet film. After printing, adjust the temperature of the printing platform to 60 °C, dry the electrolyte wet film and remove it from the printing platform, thereby making the solid electrolyte membrane with shape memory and self-healing functions.

Claims

1. A solid electrolyte membrane with shape memory and self-healing functions, characterized in that: The solid electrolyte membrane with shape memory and self-healing functions uses polyurethane (1) as a matrix material and lithium salt (2) as an auxiliary material; wherein the polyurethane (1) contains NCO-PEG-NCO precursor (4) and tetrafluorophenyl carbamate (5); the NCO-PEG-NCO precursor (4) is generated by polycondensation reaction of polyethylene glycol and hexamethylene diisocyanate; then the NCO-PEG-NCO precursor (4) and tetrafluorophenyl carbamate (5) are cross-linked to obtain a slurry of polyurethane (1); the slurry of polyurethane (1) is then mixed with lithium salt (2) to prepare a 3D ink for printing; finally, a solid electrolyte membrane with shape memory and self-healing functions having a desired shape and thickness is prepared by ink direct writing printing technology.

2. The solid electrolyte membrane with shape memory and self-healing function according to claim 1, characterized in that: The molar ratio of hexamethylene diisocyanate to polyethylene glycol is 1.1-1.5:0.9-1.

1.

3. The solid electrolyte membrane with shape memory and self-healing function according to claim 1, characterized in that: The molar ratio of the NCO-PEG-NCO precursor (4) to the tetrafluorophenyl carbamate (5) is 0.9-1.1:0.9-1.

2.

4. The solid electrolyte membrane with shape memory and self-healing function according to claim 1, characterized in that: The mass ratio of the polyurethane slurry (1) to the lithium salt (2) is 15-20:1, and the lithium salt (2) is selected from any one of lithium bis(trifluoromethylsulfonyl)imide and lithium chlorate.

5. A method for preparing a solid electrolyte membrane with shape memory and self-healing functions as claimed in any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps performed in sequence: 1) Preparation of NCO-PEG-NCO precursor (4) solution: Dry polyethylene glycol powder in an oven at 80° C. for at least 24 hours for later use; Weigh polyethylene glycol powder and dissolve it in a small amount in a hexamethylene diisocyanate solution several times; Then, stir thoroughly at 60-80° C. for 3-4 hours until the polyethylene glycol powder is completely dissolved, to prepare a solution of NCO-PEG-NCO precursor (4), wherein the molar ratio of hexamethylene diisocyanate to polyethylene glycol is 1.1-1.5:0.9-1.1; Seal with plastic wrap and store away from light; 2) Preparation of polyurethane (1) slurry: drying tetrafluorophenyl carbamate powder in an oven at 80° C. for at least 24 hours for later use; weighing tetrafluorophenyl carbamate powder and dissolving it in a small amount in the solution of NCO-PEG-NCO precursor (4) prepared in step 1) several times; stirring at room temperature for 4-8 hours until the tetrafluorophenyl carbamate powder is completely dissolved to prepare polyurethane (1) slurry, wherein the molar ratio of NCO-PEG-NCO precursor (4) to tetrafluorophenyl carbamate is 0.9-1.1:0.9-1.2; sealing with plastic wrap and storing away from light and heat; 3) Preparation of 3D ink: Dry the lithium salt (2) in an oven at 80° C. for at least 24 hours for later use; Weigh the lithium salt and dissolve it in the slurry of the polyurethane (1) prepared in step 2) in small amounts several times; Stir thoroughly at room temperature for 1-2 hours until the lithium salt (2) is evenly mixed to prepare 3D ink, wherein the mass ratio of the slurry of the polyurethane (1) to the lithium salt (2) is 15-20:1; Seal with plastic wrap and store away from light and heat; 4) Injecting the 3D ink prepared in step 3) into the injection barrel of the ink direct writing printer, performing ink direct writing printing on the printing platform according to the designed pattern and shape to form an electrolyte wet film, and after printing, adjusting the temperature of the printing platform to 60°C, drying the electrolyte wet film and removing it from the printing platform, thereby forming a solid electrolyte membrane with shape memory and self-healing functions.

6. The preparation method according to claim 5, characterized in that: The printing pressure of the ink direct writing printer is 350 psi, and the printing thickness is 50-150 μm.

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