Electrolyte with flexible, self-adhesive structure, and preparation method and application thereof

Abstract

This invention discloses an electrolyte with a flexible, self-adhesive structure, its preparation method, and its applications. The electrolyte surface has a specific structure, and this structure is arranged in an array to form a special electrolyte surface. This special surface endows the electrolyte with self-adhesive properties, which, through self-adhesion, allows the electrolyte to adhere tightly and stably to the electrode during assembly, thus simplifying the assembly process. The tight and stable electrolyte-electrode interface ensures uniform deposition of active materials, contributing to improved battery life and safety. Simultaneously, the self-adhesive properties of the electrolyte enable the battery to effectively resist external interference such as bending and stretching, achieving high operational stability and a long service life.

Description

Technical Field

[0001] This invention relates to the field of flexible battery technology, and in particular to an electrolyte with a flexible, self-adhesive structure, its preparation method, and its application. Background Technology

[0002] With the rapid development of wearable electronic products and devices, they have broad application prospects in fields such as healthcare, smart textiles, and communications. The rise of wearable devices has also placed higher demands on their power supply equipment. Traditional battery products are mainly rigid in structure, making them difficult to adapt to the application scenarios of wearable devices. Therefore, flexible batteries, due to their excellent flexibility and stretchable / bending properties, have become one of the current research hotspots.

[0003] Gel polymer electrolytes have broad application prospects in flexible batteries. On the one hand, most gel polymers are hydrophilic, giving gel polymer electrolytes good ionic conductivity. On the other hand, the gel polymer surface has good contact with the electrode interface, which can effectively control the deposition / stripping behavior of zinc.

[0004] However, most flexible batteries currently employ the traditional "sandwich" stacked structure. Due to the simple physical contact between the components in this stacked structure, relative sliding can easily occur between the gel electrolyte and the electrodes under external deformation, especially during bending. In practical applications, repeated bending further exacerbates interface degradation, thereby affecting the battery's electrochemical performance.

[0005] Therefore, there is an urgent need to develop a flexible battery that makes good contact with the electrodes, thereby improving the battery's operational stability and lifespan.

[0006] The literature (In-Situ Spontaneous Electropolymerization Enables Robust Hydrogel Electrolyte Interfaces in Aqueous Batteries) discloses the preparation of the monomer precursor AMPSZn using 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) as a raw material and replacing its protons with zinc ions through a zinc oxide (ZnO) medium. Subsequently, this precursor solution is injected into the battery system (i.e., the precursor solution is injected into the battery as the battery electrolyte). The electrochemical action during the initial charge-discharge cycle of the battery triggers in-situ polymerization—the redox reaction on the electrode surface generates free radicals, promoting the opening of the carbon-carbon double bonds in the AMPSZn monomer and resulting in addition polymerization. Simultaneously, under the action of a crosslinking agent, the monomer spontaneously forms a polyanionic hydrogel (EH) on the electrode surface and inside the porous electrode. During the polymerization process, the electrode directly participates in the reaction, causing the hydrogel to form chemical bonds with the zinc anode and the porous MnO2 cathode. However, this scheme has the following problems: (1) Insufficient universality: It only verified the effectiveness of AMPSZn monomer + Zn-MnO2 aqueous battery. If it is switched to other aqueous battery systems, the appropriate monomer molecules need to be redesigned. (2) The polymerization process depends on the battery conditions and is difficult to control. (3) Operating parameters such as current density, voltage window, and number of cycles directly affect the free radical generation rate and polymerization uniformity. If the battery conditions fluctuate (such as high-rate fast charging and wide voltage range cycling), it may lead to incomplete gel polymerization or local over-crosslinking, which will reduce the interface performance. (4) It is difficult to scale up production and the cost is high. Difficulty in uniform distribution of precursor solution in large batteries: The difference in pore structure of porous electrodes may lead to uneven gel polymerization. In addition, the cost of monomer (AMPS) is higher than that of traditional gel monomer. In the long run, it is necessary to develop a low-cost monomer system that is easy to synthesize on a large scale. Summary of the Invention

[0007] To address the technical problems existing in the prior art, the purpose of this invention is to provide an electrolyte with a flexible, self-adhesive structure, its preparation method, and its application. The gel electrolyte can maintain good interfacial contact with the electrode, while improving the battery's working stability and extending its service life.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] An electrolyte with a flexible, self-adhesive structure, wherein the electrolyte is an electrolyte with a specific surface structure, and the special surface of the electrolyte is formed by an array of such structures. The special surface achieves a certain adhesion through one or more of the following mechanisms: negative pressure adsorption, van der Waals forces, capillary forces, and mechanical adhesion, which enables the electrolyte to adhere tightly and stably to the electrode.

[0010] Furthermore, the specific structure includes, but is not limited to, cylinders, bumps, pits, hexagonal protrusions, bristles, cubes, suction cups, root-like structures, and other complex geometric structures.

[0011] Furthermore, the suction cup-like structure in the specific structure exhibits better adhesion properties and is a preferred structure.

[0012] Furthermore, the specific structure is a microstructure, and the radial dimension of a single structure is not less than 0.05 mm and not more than 1 mm, and the height dimension is not less than 0.05 mm and not more than 1 mm.

[0013] Furthermore, the array arrangement shape can be any planar pattern; And / or, the array arrangement includes, but is not limited to, staggered arrangement, square arrangement, circular arrangement, polygonal arrangement, etc.; And / or, the array spacing is 0.05~5mm.

[0014] The methods for processing specific structures on the electrolyte surface include, but are not limited to, 3D printing, casting, laser processing, electron beam and ion beam processing, photolithography, and chemical etching.

[0015] Furthermore, in the processing method, 3D printing for direct molding is the preferred option.

[0016] Furthermore, the 3D printing direct molding includes the following steps: The polymer monomer, photoinitiator, crosslinking agent, light absorber, and solvent are mixed and stirred evenly to obtain a gel polymer precursor solution; The prepared precursor solution was cured into a gel polymer using a photopolymerization 3D printer. The cured layers were then exposed and stacked one by one to obtain the gel electrolyte with a flexible and self-adhesive structure.

[0017] Furthermore, the polymer monomer is acrylamide (AM) or ethoxylated trimethylolpropane triacrylate (ETPTA). Further, the photoinitiator is diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) or lithium phenyl(2,4,6-trimethylbenzoyl)phosphate (LAP). Furthermore, the crosslinking agent is N,N' Methylene bisacrylamide (MBA), chitosan (CS), polyethylene glycol diacrylate (PEGDA); Furthermore, the light-absorbing agent is lemon yellow; Furthermore, the solvent is zinc sulfate solution or tetraethylene glycol dimethyl ether (G4). Furthermore, the curing parameters of the 3D printer can be set, including exposure time, exposure intensity, layer thickness, and leveling time. Furthermore, the number of stacked layers is 50-150; Furthermore, the electrolyte can be used in any one of lithium-ion batteries, lithium metal batteries, lithium-sulfur batteries, lithium-air batteries, zinc-ion batteries, and zinc-air batteries.

[0018] Furthermore, the battery is assembled as follows: (1) Connect the tab to the electrode plate; (2) Attach the electrode plate connected to the electrode plate to the surface of the electrolyte, and apply a certain load to make the electrode plate and the electrolyte adhere and make close contact; (3) Use a battery encapsulation device to encapsulate the assembled battery structure.

[0019] Compared with the prior art, the present invention has the following advantages: The electrolyte of this invention uses a gel polymer network as its framework and is fabricated by photopolymerization 3D printing. The surface of the gel electrolyte has a specific structure with minute dimensions. This specific structure enables the gel electrolyte to adhere tightly to the electrode surface through one or more of the following mechanisms: negative pressure adsorption, van der Waals forces, capillary forces, and mechanical adhesion. After undergoing bending, stretching, twisting, or even shear deformation, the battery's specific capacity remains essentially unchanged, achieving structural and electrochemical performance stability under dynamic deformation and extending battery life. Attached Figure Description

[0020] Figure 1 This is a surface morphology diagram of the gel polymer electrolyte of the present invention.

[0021] Figure 2 This is a schematic diagram of the battery structure based on the gel polymer electrolyte of the present invention.

[0022] Figure 3 This is a graph showing the adhesion properties of the gel electrolyte with a special suction cup structure array on the surface prepared in Example 2.

[0023] Figure 4 The image shows the CV curve of the pouch cell prepared in Example 3 after 100 bending cycles.

[0024] Figure 5 The gel polymer electrolytes with different surface structures prepared in Example 4 (the left image shows a cylindrical structure, and the right image shows a dotted structure).

[0025] Figure 6 The results of the 180° peel test are for the gel polymer electrolyte prepared in Example 4.

[0026] Figure 7The gel polymer electrolytes with different array arrangements prepared in Example 5 are shown in the left figure (staggered arrangement, square arrangement in the middle, and circular arrangement in the right figure).

[0027] Figure 8 The results of the 180° peel test are for the gel polymer electrolyte prepared in Example 5. Detailed Implementation

[0028] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention. Unless otherwise stated, the raw materials and reagents used in the following embodiments are commercially available products, or can be prepared by known methods.

[0029] Example 1 This embodiment describes the preparation of a lithium-ion battery.

[0030] This embodiment describes a method for preparing an electrolyte with a flexible, self-adhesive structure, comprising the following steps: S1: Mold Preparation (1) Preparation of photopolymer 3D printing mold: Take a 13 cm 13 cm A 1 cm stainless steel metal platform serves as the 3D printing support substrate. Specialized resin is injected into the liquid tank of the digital light processing 3D printer, the 3D model of the mold is imported, relevant printing parameters are set, and the printing program is started to obtain the printed mold. The printed mold is then removed, and the uncured resin on the surface is rinsed with anhydrous ethanol and dried with nitrogen. It is then placed in a thermosetting oven (60℃, 30 min) for complete curing. At room temperature, the mold is immersed in a 2%–5% polyvinyl alcohol (PVA) aqueous solution for 2 hours, then rinsed with deionized water and air-dried for later use.

[0031] (2) PDMS mold preparation: Mix PDMS prepolymer and curing agent at a mass ratio of 10:1 and stir until homogeneous. Place the mixture in a vacuum drying oven and evacuate (-0.1 MPa, 15 min) until no bubbles are generated. Slowly pour the defoamed PDMS solution into the 3D printing mold, ensuring complete filling; let stand at room temperature for 10 min to remove surface bubbles. Place in a thermosetting oven (80℃, 2 h) for curing, and allow to cool naturally to room temperature. Gently peel off the PDMS along the edge of the mold with tweezers to obtain a PDMS mold with a micro-specific structure. Check for any damage and bubbles before use.

[0032] S2: Preparation of precursor solution: (1) Material pretreatment: Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was vacuum dried at 120°C for 24 h, and the solvent tetraethylene glycol dimethyl ether (G4) was dried with molecular sieve in a glove box for 48 h.

[0033] (2) Preparation of solvated ionic liquid: Take a certain amount of dried LiTFSI and G4 into a glass bottle. Pre-stir using a stirring needle. When there are no lithium salt blocks larger than the rotor in the solution, add the rotor, cover the bottle with an acid and alkali resistant silicone gasket, and then seal it with sealing film. At room temperature, place it on a magnetic stirrer and stir at 700 rpm for 24 h to obtain the solvated ionic liquid.

[0034] (3) Preparation of photocurable precursor solution: Weigh a certain amount of photoinitiator phenyl-bis(2,4,6-trimethylbenzoyl)phosphine oxide (IRAGACURE 819) and monomer ethoxylated trimethylolpropane triacrylate (ETPTA), place them in a brown glass bottle, and then transfer them to a black light-shielding box and stir magnetically at 700 rpm for 90 min. Finally, add a certain amount of solvated ionic liquid and stir magnetically at 700 rpm for 3 h to obtain the precursor solution.

[0035] S3: Casting and demolding of gel polymer electrolyte: The precursor solution was slowly dripped into the groove of the PDMS mold, and excess solution was smoothed out with a scraper. The mold was placed under a 32W / 405nm UV curing lamp, and the gel polymer was completely cured after 30 seconds of irradiation. The fully cured SGPE-based gel polymer electrolyte was then removed with tweezers.

[0036] In a glove box, the gel electrolyte prepared above is stacked with electrode sheets that have undergone slurry preparation, coating, rolling, and slicing in an electrode-electrolyte-electrode sandwich structure. The tabs are then welded to the electrode sheets. Lithium iron phosphate is used as the positive electrode active material, lithium titanate as the negative electrode active material, aluminum tabs are used for the positive electrode, and nickel tabs are used for the negative electrode. Finally, the cell is placed in a groove stamped into an aluminum-plastic film and sealed. The cell is then activated on a pouch cell hot-pressing formation machine to form an SEI film. After the gases generated during formation are expelled, it is sealed again to obtain the final pouch cell.

[0037] Example 2 This embodiment prepares a zinc-ion battery.

[0038] This embodiment describes a method for preparing an electrolyte with a flexible, self-adhesive structure, comprising the following steps: S1: Preparation of precursor solution: Weigh out 60 g of acrylamide (AM), N,N' 120 mg of methylene bisacrylamide (MBA), 60 mg of chitosan (CS), 600 mg of polyethylene glycol diacrylate (PEGDA), 60 mg of diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), and 50 mg of tartrazine were added to a 150 mL 1M zinc sulfate solution and placed in a mixing cup of a high-speed mixer. The mixing cup was placed in the high-speed mixer and stirred at 2000 rpm for 15 min to ensure uniform mixing and elimination of air bubbles, thus obtaining the precursor solution.

[0039] S2: Photopolymerized 3D printing fabrication of gel polymer electrolyte: Take 13 cm 13 cm A 1 cm stainless steel metal platform was used as the 3D printing support substrate. The precursor solution prepared in step S1 was injected into the liquid tank of the digital light processing 3D printer. Relevant printing parameters were set, with the first layer exposure time set to 10 s to ensure the gel adheres firmly to the substrate and guarantee printing accuracy. During subsequent curing, the exposure time was 5 s and the exposure intensity was 75 mW / cm². 2 The leveling time was 3 s, and the layers were exposed sequentially. The cured layers were stacked up to 50 layers with a layer thickness of 20 μm to obtain a gel electrolyte with a special structure.

[0040] For details on the preparation method of the soft-pack battery, please refer to Example 1. Figure 2 This is a schematic diagram of the zinc-ion battery structure in this embodiment, as shown below. Figure 2 As shown, the outermost layer of the battery is an aluminum-plastic film 4 for encapsulation. Inside the aluminum-plastic film, the negative electrode 1 and the positive electrode 3 sandwich the gel electrolyte 2 containing electrolyte, forming a "sandwich" structure. The positive and negative electrode tabs 5 are connected to the positive and negative electrodes respectively and extend out of the aluminum-plastic film.

[0041] In this embodiment, vanadium pentoxide is used as the active material for the electrode sheet. During discharge, metallic zinc undergoes oxidation at the negative electrode (made of zinc sheet) to become zinc ions. The electrolyte and negative electrode are tightly bonded. Zinc ions detach from the negative electrode and move directionally towards the electrode through channels within the electrolyte, subsequently contacting the active material on the electrode sheet and undergoing an intercalation reaction. Simultaneously, electrons move from the tab to the tab. Because the tab and electrode sheet are tightly bonded with conductive adhesive, electrons enter the electrode sheet from the tab to neutralize the charge of the zinc ions, completing the discharge process of the zinc-ion battery. During charging, zinc ions first detach from the active material on the electrode sheet and enter the electrolyte, then contact the zinc sheet through ion channels within the electrolyte. Electrons are transferred from the active material on the electrode sheet, passing through the tab and neutralizing the charge of the zinc ions on the zinc sheet, completing the charging process.

[0042] This embodiment uses a biomimetic octopus sucker structure as the microstructure of the gel electrolyte surface. For example... Figure 1 As shown, this structure draws inspiration from the octopus's ability to adhere to surfaces using its suckers. A similar sucker structure was designed and arranged in an array on the gel surface. The sucker diameter is 0.7 mm, and the array spacing is 0.3 mm.

[0043] The electrolyte with a flexible, self-adhesive structure from Example 2 was subjected to a 180° peel test using a universal testing machine. The test was conducted at room temperature. Peel tests were performed on four samples, categorized by suction cup size: an unstructured control group, samples with a diameter of 0.2 mm, 0.3 mm, and 0.5 mm. Figure 3 As shown, all five sets of curves exhibit strong adhesion performance. The 0.2 mm and 0.3 mm diameter samples showed better adhesion performance than the control group, indicating that the microscopic special suction cup structure possesses superior adhesion properties. The 0.5 mm diameter sample, however, showed slightly weaker adhesion performance than the control group. Analysis revealed that, firstly, size affects the adhesion performance of individual structures. Secondly, since all samples used the same array spacing (0.3 mm), a larger structure size resulted in a smaller actual contact area. Therefore, the smaller contact area of ​​the 0.5 mm diameter sample negatively impacted its adhesion performance.

[0044] Example 3 This embodiment prepares a sodium-ion battery.

[0045] The preparation method of the electrolyte used in the sodium-ion battery can be referred to in Example 2, the difference being that the solvent used is a 2M sodium sulfate solution. The preparation method of the pouch battery can be referred to in Example 1. In this example, the battery uses sodium vanadium manganese phosphate as the positive electrode material and sodium metal as the negative electrode material. During battery assembly, due to the special structure of the polymer gel surface, the electrolyte can adhere tightly to the electrode surface. After multiple bending tests, no significant detachment of the electrolyte and electrode was observed, and the pouch battery continued to function normally. Furthermore, the stable and tight interface between the electrolyte and the battery negative electrode can effectively control sodium deposition behavior and reduce the possibility of sodium dendrite formation. This is beneficial for maintaining the battery capacity of the sodium-ion battery and extending its service life. Bending tests were conducted on the pouch battery prepared in Example 3 to test the stability of the battery after multiple bends. Figure 4 As shown, after 100 bends, the battery capacity and peak current changed little compared to before bending, indicating that the electrolyte can stably adhere to the electrode surface, forming a stable interface contact, and will not cause mechanical detachment that would lead to battery failure. This once again proves the strong adhesion of the special surface structure.

[0046] Example 4 This embodiment prepares gel polymer electrolytes with various surface structures.

[0047] The specific method for preparing the electrolyte can be found in Example 2, the difference being the model used in the photopolymerization printing. A DLP photopolymerization 3D printer was used to print gel polymer electrolytes with cylindrical and bumped surface structures, respectively. Figure 5 As shown.

[0048] The electrolyte in Example 4 was subjected to a 180° peel test using a universal testing machine. The test was conducted at room temperature. Peel tests were performed on samples with both structures. For the electrolyte with the bump structure, two sets of samples were prepared, with bump diameters of 0.05 mm and 1 mm. The peel test results are as follows: Figure 6 As shown, the cylindrical structure exhibits the greatest adhesion force among the three sample groups, with a 0.05 mm diameter showing slightly greater adhesion force than a 1 mm diameter.

[0049] Example 5 In this embodiment, gel polymer electrolytes with different array arrangements were prepared.

[0050] The specific method for preparing the electrolyte can be found in Example 2, the difference being the slicing model used for printing. A DLP photopolymer 3D printer was used to print staggered, square, and circular arrangements of gel polymer electrolytes. Figure 7 As shown.

[0051] The electrolyte in Example 5 was subjected to a 180° peel test using a universal testing machine. The test was conducted at room temperature. Peel tests were performed on samples with three different arrangements. The test results are as follows. Figure 8 As shown, among the three groups of samples, the staggered arrangement exhibited the best adhesion performance. The maximum adhesion force of the circular arrangement was higher than that of the square arrangement, but the overall adhesion performance of the square arrangement was better than that of the circular arrangement.

[0052] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An electrolyte with a flexible, self-adhesive structure, characterized in that, The electrolyte is an electrolyte with a specific surface structure, and the special surface of the electrolyte is formed by the array of such structures. The special surface achieves adhesion through one or more of the following mechanisms: negative pressure adsorption, van der Waals force, capillary force, and mechanical adhesion, so that the electrolyte adheres tightly and stably to the electrode. The specific structures include cylinders, bumps, pits, hexagonal protrusions, bristles, cubes, suction cups, root-like structures, and other complex geometric structures. The specific structure is a microstructure, and the radial dimension of a single structure is not less than 0.05 mm and not more than 1 mm, and the height dimension is not less than 0.05 mm and not more than 1 mm.

2. The electrolyte with a flexible, self-adhesive structure according to claim 1, characterized in that, The array arrangement shape can be any planar pattern; And / or, the array arrangement includes, but is not limited to, staggered arrangement, square arrangement, circular arrangement, and polygonal arrangement; And / or, the array spacing is 0.05 to 5 mm.

3. An electrolyte with a flexible, self-adhesive structure according to claim 1, characterized in that, The methods for processing specific structures on the electrolyte surface include 3D printing, casting, laser processing, electron beam and ion beam processing, photolithography, and chemical etching.

4. A method for preparing an electrolyte with a flexible, self-adhesive structure as described in any one of claims 1-3, characterized in that, Includes the following steps: The polymer monomer, photoinitiator, crosslinking agent, light absorber, and solvent are mixed and stirred evenly to obtain a gel polymer precursor solution; The prepared precursor solution was cured into a gel polymer using a photopolymerization 3D printer. The cured layers were then exposed and stacked one by one to obtain the gel electrolyte with a flexible and self-adhesive structure.

5. The preparation method according to claim 4, characterized in that, The polymer monomer is acrylamide or ethoxylated trimethylolpropane triacrylate; The photoinitiator is diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide or lithium phenyl(2,4,6-trimethylbenzoyl)phosphate. The crosslinking agent is N,N' Methylene bisacrylamide, chitosan, or polyethylene glycol diacrylate; The light absorber is lemon yellow; The solvent is zinc sulfate solution or tetraethylene glycol dimethyl ether.

6. The preparation method according to claim 4, characterized in that, Setting the curing parameters for a 3D printer includes exposure time, exposure intensity, layer thickness, and leveling time.

7. The preparation method according to claim 4, characterized in that, The number of stacked layers is 50-150.

8. The application of an electrolyte with a flexible, self-adhesive structure as described in any one of claims 1-3 in a battery.

9. The application according to claim 8, characterized in that, The electrolyte can be used in any of the following: lithium-ion batteries, lithium metal batteries, lithium-sulfur batteries, lithium-air batteries, sodium-ion batteries, zinc-ion batteries, zinc-air batteries, and supercapacitors.

10. The application according to claim 8, characterized in that, The battery is assembled as follows: (1) Connect the tab to the electrode plate; (2) Attach the electrode plate connected to the electrode plate to the surface of the electrolyte, and apply a load to make the electrode plate and the electrolyte adhere and make close contact; (3) Use a battery encapsulation device to encapsulate the assembled battery structure.

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