CN-122000494-A - Preparation method of gradient asymmetric hydrogel electrolyte

CN122000494ACN 122000494 ACN122000494 ACN 122000494ACN-122000494-A

Abstract

The invention belongs to the field of new energy storage materials, and particularly discloses a preparation method of gradient asymmetric hydrogel electrolyte, which is used for rapidly preparing organic-inorganic composite hydrogel electrolyte with a gradient structure at room temperature by controlling electrolyte salt concentration as a main time factor and cooperating with a fine tuning effect of nano inorganic filler and a space factor of gravity sedimentation. The method has universality, can be adapted to various inorganic fillers, and finally forms a gradient structure of 'a negative side filler enrichment layer-an intermediate transition layer-a positive side polymer network layer' by adjusting the salt concentration to match the sedimentation behaviors of different fillers. The electrolyte can realize the stable interface of the cathode, the rapid transmission of positive ions and the enhancement of mechanical properties, and has excellent cycling stability and capacity retention rate in both symmetrical batteries and full batteries. The preparation method is simple, low in energy consumption and high in controllability, and is suitable for large-scale energy storage and flexible electronic equipment.

Inventors

HU YUANYUAN
Luan Yuhan
YANG KAI
Qi Ruzhao
WANG YUXIN

Assignees

山东农业大学

Dates

Publication Date: 20260508
Application Date: 20260227

Claims (10)

1. A preparation method of a gradient asymmetric hydrogel electrolyte is characterized by comprising the following specific steps: (1) The preparation of a dispersion liquid A, namely dispersing nano inorganic filler in electrolyte salt solution, stirring and carrying out ultrasonic treatment to obtain the dispersion liquid A, wherein the mass fraction of the nano inorganic filler in the dispersion liquid A is 5-50 mg mL -1 , and the concentration of the electrolyte salt is 1-5 mol L -1 ; (2) Dissolving unsaturated monomers containing double bonds in the dispersion liquid A prepared in the step (1) to obtain a solution B, wherein the unsaturated monomers containing double bonds are amide type, carboxyl type and hydroxyl type monomers, and account for 3-25 wt% of the total mass of the solution B; (3) And (3) sequentially adding a cross-linking agent and an initiator into the solution B prepared in the step (2), mixing 10-30 s, pouring into a horizontal die, standing at room temperature for 1-20: 20min, settling the nano inorganic filler towards the bottom of the die under the action of gravity, and finally forming the gradient asymmetric hydrogel electrolyte by taking the side corresponding to the bottom of the die as a zinc negative electrode side and the side corresponding to the top of the die as a positive electrode side.
2. The method for preparing a gradient asymmetric hydrogel electrolyte according to claim 1, The method further comprises the step of constructing an acidic layer on the positive side, wherein the positive side of the gradient asymmetric hydrogel electrolyte obtained in the step (3) is coated with an acidic gel precursor solution, the acidic gel precursor solution is subjected to standing at room temperature for 3-10 min m for in-situ polymerization, the thickness of the acidic layer is 10-50 mu m, the pH value is 0.5-3.0, and the acidic gel precursor solution comprises monomers, a cross-linking agent and an initiator, wherein the monomers are selected from amide type, carboxyl type, hydroxyl type unsaturated monomers or acidic unsaturated monomers.
3. The preparation method of the gradient asymmetric hydrogel electrolyte according to claim 1, wherein the nano inorganic filler in the step (1) is one or more of molecular sieve, montmorillonite, hydrotalcite-like compound, halloysite, nanocellulose and titanic acid nanotube, and the nano inorganic filler is a zero-dimensional, one-dimensional or two-dimensional nano material, wherein the size of the zero-dimensional material is 1-100 nm, the diameter of the one-dimensional material is 1-100 nm, the length of the one-dimensional material is more than 1 μm, and the average wafer thickness of the two-dimensional lamellar material is less than 25 nm.
4. The method for preparing the gradient asymmetric hydrogel electrolyte according to claim 1, wherein the electrolyte salt in the step (1) is one or two mixtures selected from zinc sulfate and zinc trifluoromethane sulfonate, and the ultrasonic parameters are power 100-300W, frequency 20-100 KHz and time 0.1-5 h.
5. The method for preparing the gradient asymmetric hydrogel electrolyte according to claim 1, wherein in the step (2), the amide monomer is selected from one or more of sodium 2-acrylamido-2-methylpropanesulfonate, acrylamide, N-2- (hydroxyethyl) -acrylamide and N, N-dimethylacrylamide, the carboxyl monomer is selected from one or more of acrylic acid, methacrylic acid and sodium acrylate, and the hydroxyl monomer is selected from one or more of N-methylolacrylamide, [2- (methacryloyloxy) ethyl ] dimethyl- (3-sulfopropyl) ammonium hydroxide.
6. The method for preparing the gradient asymmetric hydrogel electrolyte according to claim 1, wherein the cross-linking agent in the step (3) is one or more selected from N, N-methylene bisacrylamide and divinylbenzene, the initiator is one or more selected from potassium persulfate, sodium persulfate and ammonium persulfate, the initiator accounts for 0.1-0.6wt% of the total mass of the monomer, and the cross-linking agent accounts for 0.01-0.2wt% of the total mass of the monomer.
7. The method according to claim 2, wherein the amide monomer in the monomer of the acid gel precursor solution in the step (4) is selected from one or more of sodium 2-acrylamido-2-methylpropanesulfonate, acrylamide, N-2- (hydroxyethyl) -acrylamide, N-dimethylacrylamide, the carboxyl monomer is selected from one or more of acrylic acid, methacrylic acid, sodium acrylate, and the hydroxyl monomer is selected from one or more of N-methylolacrylamide, [2- (methacryloyloxy) ethyl ] dimethyl- (3-sulfopropyl) ammonium hydroxide.
8. The method for preparing a gradient asymmetric hydrogel electrolyte according to claim 7, wherein when the monomer of the acid gel precursor in the step (4) is an amide type, carboxyl type or hydroxyl type unsaturated monomer, an acid preparation is required, the acid is selected from one or two of sulfuric acid and hydrochloric acid, the concentration is 0.5-2mol -1 , and the pH value of the acid layer is adjusted to 0.5-3.0 by the acid concentration.
9. The method for preparing the gradient asymmetric hydrogel electrolyte according to claim 2, wherein the acidic unsaturated monomer in the monomer of the acidic gel precursor solution in the step (4) is one or more selected from 2-acrylamido-2-methylpropanesulfonic acid, acrylic acid, methacrylic acid, itaconic acid and styrenesulfonic acid.
10. The method for preparing the gradient asymmetric hydrogel electrolyte according to claim 2, wherein the cross-linking agent in the step (4) is selected from one or more of N, N-methylene bisacrylamide and divinylbenzene, the initiator is selected from one or more of potassium persulfate, sodium persulfate and ammonium persulfate, the initiator is used in an amount of 0.1-0.6wt% based on the total mass of the monomers, and the cross-linking agent is used in an amount of 0.01-0.2wt% based on the total mass of the monomers.

Description

Preparation method of gradient asymmetric hydrogel electrolyte Technical Field The invention belongs to the field of energy storage material preparation, and particularly relates to a preparation method of gradient asymmetric hydrogel electrolyte. Background Under the introduction of a 'double carbon' target, the novel energy storage technology becomes a strategic engine for energy transformation, wherein the water-based zinc ion battery (AZIBs) becomes one of core candidates of the next-generation electrochemical energy storage system by virtue of high theoretical specific capacity (820 mAh g -1), low redox potential (-0.76V vs. SHE), environmental friendliness, abundant resources, low cost and the like. However, the practical application of AZIBs still faces a serious challenge, and the core bottleneck is that there is an intrinsic contradiction between the positive and negative functional requirements of the electrolyte, resulting in the mismatch of the electrolyte-electrode interface, specifically in the following two aspects: On the one hand, the positive and negative electrode pair gel network content and the water activity requirements are mutually conflicting. The zinc cathode side needs a high-density gel network to reduce free water content, inhibit side reactions such as Hydrogen Evolution Reaction (HER), corrosion, dendrite growth and the like, guide Zn 2+ to be deposited uniformly, but the anode side (such as V-base, mn-base oxide and organic anode) depends on sufficient water activity to ensure rapid deintercalation of H +/Zn2+ double ions, and the excessively high gel network content can enhance interaction of groups with water and Zn 2+, prevent ion transmission and limit anode capacity release. Conventional homogeneous hydrogel electrolytes need to be compromised between the two, resulting in a battery with poor overall performance. On the other hand, there is a significant difference in the positive and negative electrode requirements for H + concentration. The high H + content accelerates the chemical corrosion of the zinc cathode and damages the structural stability of the electrode, while a plurality of positive electrode materials (such as NaV 3O8、MnO2 and the like) have an H +/Zn2+ double-ion storage mechanism, and the sufficient H + supply and the strong hydrogen bond network structure are key to improving the energy storage capacity of the positive electrode. How to accurately regulate and control the concentration and the water activity of H + in the anode region and the cathode region through the structural design of the electrolyte becomes a core scientific problem for solving the AZIBs performance bottleneck. In order to overcome the challenges, researchers at home and abroad put forward the design thought of an asymmetric hydrogel electrolyte, the requirements of anode and cathode are adapted through a double-interface differentiated structure, and certain progress is made, a gradient hydrogel network which is fixed by covalent is built by adopting an epitaxial polymerization strategy by a group of Jiang Lei academy of physics and chemistry of China academy of sciences, zn 2+ selective transmission is accelerated by means of asymmetric distribution of negative functional groups, a double-layer structure which is formed by compounding inorganic solid electrolyte and hydrogel is designed by a group of university of hong Kong city Zhi Chunyi, the requirements of anode dendrite-free deposition and anode rapid ion transmission are respectively met, janus hydrogel is prepared by a group of researchers of Dalian institute Yang Weishen through gradient distribution of hydrophilic and hydrophobic monomers, and the activity of water molecules of anode and cathode interfaces is accurately regulated. These studies fully demonstrate the effectiveness of asymmetric structural designs, but the current technology still has a number of limitations: 1. The research of the organic-inorganic composite system is insufficient, the existing asymmetric hydrogel mainly uses a pure organic network, most schemes rely on hydrophilic-hydrophobic monomer gradient distribution, functional group modification or special die induction of an asymmetric structure, inorganic materials (such as inorganic frames and nano multidimensional materials) and polymer networks cannot be cooperatively designed, the unique advantages of the inorganic materials in the aspects of enhancing mechanical properties, regulating Zn 2+ desolvation and uniform deposition are not fully exerted, and the preparation and performance regulation of the organic-inorganic composite asymmetric system still lack systematic research. 2. The interface dynamics problem is outstanding, the prior art mostly adopts a double-layer structure prepared step by step, the surface layer moisture is easy to evaporate due to long-time heating gelation, the interface impedance is easy to generate due to different network layer stacking, the high-rate performanc