阅读说明：本技术 一种可修复的交联固态聚合物电解质及其制备方法和应用 (Repairable cross-linked solid polymer electrolyte and preparation method and application thereof ) 是由 曹晓燕 童永芬 沈恒冰 许秋华 于 2020-06-23 设计创作，主要内容包括：本发明提供了一种可修复的交联固态聚合物电解质及其制备方法和应用,通过以下方法制备得到：将对苯二甲醛、双酚A二缩水甘油醚、聚乙二醇二胺、和锂盐分散溶解在乙腈溶剂中,搅拌2~6h,得到透明均匀的混合液A；将混合液A滴入到聚四氟乙稀模上,在室温条件下使乙腈挥发得到溶胶状物质B；将溶胶状物质B置于真空干燥箱中,先聚合反应使其完全交联固化,再继续加热使其干燥,制备得到聚合物电解质。本发明通过引入动态亚胺共价键到聚合物电解质中形成固态网络状聚合物电解质,在使用过程中发生断裂时能够得到及时修复；所制备的网络状聚合物电解质同时具有很好的热稳定性和无枝晶形貌,离子电导率、锂离子迁移数等电化学性能优良。(The invention provides a repairable cross-linked solid polymer electrolyte and a preparation method and application thereof, wherein the cross-linked solid polymer electrolyte is prepared by the following steps: dispersing and dissolving terephthalaldehyde, bisphenol A diglycidyl ether, polyethylene glycol diamine and lithium salt in an acetonitrile solvent, and stirring for 2-6 h to obtain a transparent and uniform mixed solution A; dripping the mixed solution A onto a polytetrafluoroethylene mold, and volatilizing acetonitrile at room temperature to obtain a sol substance B; and (3) placing the sol substance B in a vacuum drying oven, firstly carrying out polymerization reaction to completely crosslink and solidify the sol substance B, and then continuously heating to dry the sol substance B to prepare the polymer electrolyte. According to the invention, the dynamic imine covalent bond is introduced into the polymer electrolyte to form the solid network polymer electrolyte, so that the solid network polymer electrolyte can be repaired in time when the solid network polymer electrolyte is broken in the using process; the prepared network polymer electrolyte has good thermal stability, no dendrite morphology, excellent ion conductivity, lithium ion migration number and other electrochemical properties.)

1. A method for preparing a repairable crosslinked solid polymer electrolyte, comprising the steps of:

s1: dispersing and dissolving terephthalaldehyde, bisphenol A diglycidyl ether, polyethylene glycol diamine and lithium salt in an acetonitrile solvent, and stirring for 2-6 h to obtain a transparent and uniform mixed solution A;

s2: dripping the mixed solution A prepared in the step S1 on a polytetrafluoroethylene mold, and volatilizing acetonitrile at room temperature to obtain a sol substance B;

s3: and (4) placing the sol substance B prepared in the step (S2) in a vacuum drying oven, firstly carrying out polymerization reaction to completely crosslink and solidify the sol substance B, and then continuously heating to dry the sol substance B to prepare the polymer electrolyte.

2. The method of claim 1, wherein the method further comprises: the lithium salt is bis (trifluoromethane) sulfonyl imide lithium.

3. The method of claim 1, wherein the method further comprises: the molar ratio of the terephthalaldehyde to the bisphenol A diglycidyl ether to the polyethylene glycol diamine is 1:2: 2-4.

4. The method of claim 3, wherein the method further comprises: the amount of the lithium salt is obtained by regulating the molar ratio of oxygen atoms in polyethylene glycol chain segments in the polyethylene glycol diamine to lithium ions to be 8, 16 and 24 respectively.

5. The method of claim 4, wherein the method further comprises the steps of: when the molar ratio of the oxygen atoms to the lithium ions is 16, the mass fractions of terephthalaldehyde, bisphenol a diglycidyl ether, and polyethylene glycol diamine in the mixed solution a are 69.5%, 68.3%, and 67.6%, respectively.

6. The method of claim 4, wherein the method further comprises the steps of: when the molar ratio of the terephthalaldehyde to the bisphenol A diglycidyl ether to the polyethylene glycol diamine is 1:2:3, and the molar ratio of the oxygen atom to the lithium ion is 8, 16 and 24, the mass fractions of the lithium salt in the mixed solution A are 58.2%, 31.7% and 21.8%, respectively.

7. The method for preparing a repairable crosslinked solid polymer electrolyte according to any one of claims 1 to 6, wherein: in the step S3, the temperature of the polymerization reaction is 80-120 ℃ and the time is 6-12 h.

8. The method for preparing a repairable crosslinked solid polymer electrolyte according to any one of claims 1 to 6, wherein: in the step S3, the drying temperature is 80-120 ℃, and the drying time is 36-60 h.

9. A repairable crosslinked solid polymer electrolyte, comprising: the polymer electrolyte is prepared by the method of any one of claims 1 to 8.

10. Use of a repairable crosslinked solid polymer electrolyte, characterized in that: the polymer electrolyte prepared by any one of the methods of claims 1 to 8 can be used in a lithium metal battery.

Technical Field

The invention relates to the field of lithium metal batteries, in particular to a repairable cross-linked solid polymer electrolyte and a preparation method and application thereof.

Background

In order to deal with the energy crisis and increasingly strict environmental protection requirements, governments of various countries have a new energy policy, and new and green energy is encouraged to develop. Meanwhile, along with the higher living standard of people, the demand on energy is rapidly improved, and the rapid development of the energy storage field, particularly the battery technology, is promoted. In the 90 s of the 20 th century, after sony corporation developed a commercial lithium metal battery using a graphite cathode and an intercalation mechanism, the lithium metal battery rapidly occupied high-end electronic devices such as notebook computers, mobile phones and the like. With the development of the technology, the novel intelligent wearable device is not developed to the greatest extent, and the novel intelligent wearable device provides a new challenge for the flexible quick-charging battery. Lithium metal has extremely high capacity, the lowest generation potential and large elastic modulus, and determines that the metal lithium battery has great potential in high-energy and high-power-density flexible batteries.

Due to the high energy density of Lithium Metal Batteries (LMBs), flexible lithium metal batteries are of great importance for the development of portable and wearable electronic devices, etc., where the demand for electrical systems is very high, e.g., flexible lithium metal batteries are able to withstand some deformations such as bending and rolling. Under the prior art, although a thin polymer electrolyte membrane in a flexible lithium metal battery has high flexibility, the thin polymer electrolyte membrane is easy to break and cannot be repaired when being deformed, so that LMBs are failed, and even safety accidents such as leakage of chemical electrolyte and the like can be caused. Therefore, how to effectively solve the problem of cracking of the polymer electrolyte is a technical problem.

Disclosure of Invention

In order to solve the above technical problems, a first aspect of the present invention provides a method for preparing a repairable crosslinked solid polymer electrolyte, comprising the steps of:

s1: dispersing and dissolving terephthalaldehyde, bisphenol A diglycidyl ether, polyethylene glycol diamine and lithium salt in an acetonitrile solvent, and stirring for 2-6 h to obtain a transparent and uniform mixed solution A;

s2: dripping the mixed solution A prepared in the step S1 on a polytetrafluoroethylene mold, and volatilizing acetonitrile at room temperature to obtain a sol substance B;

s3: and (4) placing the sol substance B prepared in the step (S2) in a vacuum drying oven, firstly carrying out polymerization reaction to completely crosslink and solidify the sol substance B, and then continuously heating to dry the sol substance B to prepare the polymer electrolyte.

Wherein the lithium salt is lithium bis (trifluoromethanesulfonyl) imide.

Wherein the molar ratio of the terephthalaldehyde to the bisphenol A diglycidyl ether to the polyethylene glycol diamine is 1:2: 2-4.

Wherein the amount of the lithium salt is obtained by regulating the molar ratio of oxygen atoms in polyethylene glycol chain segments in the polyethylene glycol diamine to lithium ions to be 8, 16 and 24 respectively.

Wherein when the molar ratio of the oxygen atoms to the lithium ions is 16, the mass fractions of terephthalaldehyde, bisphenol a diglycidyl ether, and polyethylene glycol diamine in the mixed solution a are 69.5%, 68.3%, and 67.6%, respectively.

When the molar ratio of the terephthalaldehyde to the bisphenol A diglycidyl ether to the polyethylene glycol diamine is 1:2:3, and the molar ratio of the oxygen atom to the lithium ion is 8, 16 and 24, the mass fractions of the lithium salt in the mixed solution A are 58.2%, 31.7% and 21.8%, respectively.

In the step S3, the temperature of the polymerization reaction is 80-120 ℃ and the time is 6-12 h.

Preferably, the first and second electrodes are formed of a metal,

the polymerization temperature is 85 ℃, 90 ℃, 95 ℃, 100 ℃, 105 ℃, 110 ℃ and 115 ℃;

the polymerization time is 7h, 8h, 9h, 10h and 11 h.

In the step S3, the drying temperature is 80-120 ℃ and the drying time is 36-60 hours.

Preferably, the first and second electrodes are formed of a metal,

the drying temperature is 85 ℃, 90 ℃, 95 ℃, 100 ℃, 105 ℃, 110 ℃ and 115 ℃;

the drying time is 40h, 45h, 50h and 55 h.

The reaction process of the invention is as follows:

in a second aspect, the present invention provides a repairable crosslinked solid polymer electrolyte prepared according to the method of the first aspect of the present invention.

A third aspect of the invention provides the use of a repairable crosslinked solid state polymer electrolyte that is applicable in a lithium metal battery.

The invention has the beneficial effects that: the invention obtains the flexible solid polymer electrolyte by blending straight-chain PEG amine copolymer, aromatic aldehyde compound, epoxy bisphenol thermosetting material and lithium salt and then carrying out thermosetting crosslinking. Because the straight-chain PEG amine high polymer contains more EO units, lithium salt can be effectively locked in a cross-linked network micro area to form a stable and continuous ion transmission channel, and the electrochemical properties of the electrolyte, such as ionic conductivity, lithium ion migration number and the like, are ensured; the PEG amine polymer and the aromatic aldehyde/epoxy thermosetting material are crosslinked to form a dynamic covalent polymer, so that the electrolyte has good flexibility and self-repairability, and a safe and stable flexible solid electrolyte interface layer (SEI layer) is ensured to be formed; and further realizes the control of the dynamic polymer network by changing the content of the crosslinking component. The solid polymer electrolyte membrane with good electrochemical performance, self-repairing performance and good thermal stability can be prepared by the technology of the invention, so that the flexible, efficient, safe and stable lithium metal battery can be obtained.

Poor stability is a long-term problem that hinders lithium metal battery applications, mainly because the fragile solid electrolyte interfacial layer is inherently unable to adapt to changes in dynamic volume, nor to self-heal after failure. The invention introduces dynamic imine covalent bonds into the polymer electrolyte to form a solid self-healing elastomer, the network elastomer can easily adapt to the change of volume, and meanwhile, the electrolyte can be repaired in time when the fracture occurs under complex deformation (such as bending, rolling and twisting) in the using process, and the prepared network polymer electrolyte also has good thermal stability, no dendrite morphology, excellent ionic conductivity, excellent electrochemical properties of lithium ion migration number and the like.

Drawings

In order to more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it should be obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is an infrared spectrum of a polymer electrolyte membrane prepared in example 3 of the present invention;

fig. 2 is an XRD pattern of the polymer electrolyte thin film prepared in example 3 of the present invention;

FIG. 3 is a TGA profile of a polymer electrolyte film prepared according to example 3 of the present invention;

FIG. 4 is a DSC of a polymer electrolyte membrane prepared in example 3 of the present invention;

FIG. 5 is a graph showing the change of the electrical conductivity with temperature of polymer electrolyte films having different crosslinking components and the same oxygen-to-lithium ratio prepared in examples 2 to 4 of the present invention;

FIG. 6 is a graph showing the change of the conductivity with temperature of electrolyte films with different lithium ion ratios and the same crosslinking component prepared in examples 4 to 6 of the present invention;

fig. 7 is an SEM image of a polymer electrolyte thin film prepared in example 3 of the present invention;

fig. 8 is a LSV diagram of a polymer electrolyte thin film prepared in example 3 of the present invention;

FIG. 9 is a graph showing the repairing performance of the polymer electrolyte membrane prepared in example 3 of the present invention;

fig. 10 is a graph showing the mechanical properties of the polymer electrolyte membrane prepared in example 3 of the present invention.

Detailed Description

The following is a preferred embodiment of the present invention, and it should be noted that it is obvious to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and these modifications and improvements are also considered to be within the scope of the present invention.