CN-122011313-A - Polyimide Schiff base polymer containing thiophene structure and application of polyimide Schiff base polymer in lithium ion battery

CN122011313ACN 122011313 ACN122011313 ACN 122011313ACN-122011313-A

Abstract

The invention discloses a polyimide Schiff base polymer containing a thiophene structure and application thereof in a lithium ion battery, and belongs to the technical field of organic electrode materials of lithium ion batteries. The structural general formula of the polyimide Schiff base polymer containing thiophene structure is shown as follows: . According to the invention, by introducing a thiophene ring, the pi conjugated structure of a main chain is obviously expanded, the electron delocalization degree is enhanced, the characteristic that sulfur atoms have high polarization and p orbits participate in conjugation is utilized, the intrinsic electron conductivity and interfacial charge transmission capacity of the material are improved, meanwhile, an imide carbonyl group and a Schiff base C=N bond in the material are used as main lithium storage active sites, and the thiophene conjugated unit is favorable for electron transmission and structural stability, so that the material has higher specific capacity, excellent multiplying power performance and cyclic stability. The material has the advantages of simple and convenient synthesis method, easily available raw materials and stable structure, and is suitable for serving as the organic negative electrode material of the high-performance lithium ion battery.

Inventors

XU YING
ZHANG NAN
CHEN TIANPENG
QIAN JING
LU YAN
CHU CHENGDONG

Assignees

安徽大学

Dates

Publication Date: 20260512
Application Date: 20260324

Claims (10)

1. A polyimide Schiff base polymer containing a thiophene structure is abbreviated as PITD, and is characterized by having the following structural general formula: 。
2. the method for preparing polyimide schiff base polymer containing thiophene structure according to claim 1, which is characterized in that: Firstly, 1,4,5, 8-naphthalene tetracarboxylic dianhydride is used as an initial raw material, and reacts with hydrazine hydrate under the protection of nitrogen to prepare an N, N' -diamino-1, 4,5, 8-naphthalene tetracarboxylic bisimide intermediate, and then the intermediate and thiophene-2, 5-dicarboxaldehyde undergo Schiff base polycondensation reaction to obtain the polyimide Schiff base polymer PITD containing a thiophene bridging structure.
3. The preparation method according to claim 2, characterized by comprising the steps of: Step 1, adding 1,4,5, 8-naphthalene tetracarboxylic dianhydride into absolute ethyl alcohol under the nitrogen atmosphere, slowly dropwise adding hydrazine hydrate under the ice bath condition, stirring and mixing, and heating to reflux reaction to obtain an N, N' -diamino-1, 4,5, 8-naphthalene tetracarboxylic acid bisimide intermediate; Step 2, adding the intermediate obtained in the step1 and thiophene-2, 5-dicarboxaldehyde into N-methylpyrrolidone, dropwise adding acetic acid as a catalyst, heating under the protection of nitrogen to perform polycondensation reaction, and separating and purifying after the reaction is finished to obtain a target polymer PITD; The reaction scheme is as follows: 。
4. the use of the polyimide schiff base polymer containing thiophene structure according to claim 1 in the preparation of lithium ion batteries.
5. The use according to claim 4, characterized in that: The polyimide Schiff base polymer containing the thiophene structure is used as an active substance of a lithium ion battery anode material.
6. The use according to claim 5, characterized in that: And mixing the polyimide Schiff base polymer containing the thiophene structure, the conductive agent and the binder, uniformly coating the mixture on the surface of a copper foil current collector, and carrying out vacuum drying to obtain the negative electrode plate of the lithium ion battery.
7. The use according to claim 6, characterized in that: The mass ratio of the polyimide Schiff base polymer containing the thiophene structure to the conductive agent to the binder is 40-70:20-50:5-15.
8. Use according to claim 6 or 7, characterized in that: The conductive agent is one or more of ketjen black, acetylene black, conductive carbon black and Super P, and the binder is one or more of polyacrylic acid, sodium alginate and carboxymethyl cellulose.
9. The use according to claim 8, characterized in that: The binder is formed by compounding polyacrylic acid and sodium alginate.
10. The use according to claim 9, characterized in that: the mass ratio of polyacrylic acid to sodium alginate is 1-4:1.

Description

Polyimide Schiff base polymer containing thiophene structure and application of polyimide Schiff base polymer in lithium ion battery Technical Field The invention belongs to the technical field of organic electrode materials of lithium ion batteries, and particularly relates to a polyimide Schiff base polymer containing a thiophene structure and application of the polyimide Schiff base polymer in a lithium ion battery. Background With the rapid development of electric vehicles, portable electronic devices, and large-scale energy storage systems, the social demand for high energy density, high power density, and long-life secondary batteries continues to increase. Lithium ion batteries have become one of the most mature and widely used secondary battery systems at present due to the advantages of high working voltage, long cycle life, environmental friendliness and the like. However, the electrode materials of the existing commercial lithium ion battery are mainly inorganic materials, wherein the theoretical specific capacity of the graphite cathode is 372 mAh g -1 only, and the theoretical limit of the graphite cathode is approached, so that the development requirement of the future high-energy-density energy storage device is difficult to meet. The organic electrode material is composed of C, H, N, O, S and other light elements, has the advantages of wide sources, strong designability of molecular structures, high theoretical specific capacity, environmental friendliness and the like, and is widely paid attention in recent years. Organic molecules containing structural units such as carbonyl, imine bonds, conjugated aromatic rings and the like can store lithium ions through a reversible oxidation-reduction process, so that the organic molecules have potential as electrode materials of lithium ion batteries. In particular to a polymer organic electrode material which is not easy to dissolve in electrolyte and has better cycle stability compared with a small molecular organic electrode material. In the prior study, the polyimide material is often used for constructing an organic anode material due to the fact that the polyimide material contains more imide carbonyl groups, has stable structure and high thermal stability, and meanwhile, the Schiff base reaction has the advantages of mild conditions, simple and convenient steps, convenience in constructing a conjugated framework and the like, and the pi conjugated system of the polymer can be further expanded by connecting polyimide units with dialdehyde units, so that the dissolution of active substances is slowed down, and the electron transmission capacity is improved. In the prior art, polyimide Schiff base polymers constructed by aromatic dialdehydes, in particular terephthalaldehyde, have shown certain reversible specific capacity and cycle stability. However, the existing polyimide Schiff base system taking benzene rings as bridging units still has the following problems that firstly, electron cloud distribution of the benzene ring bridging structure is relatively symmetrical, intrinsic conductivity is limited to improve, charge transmission is still limited under high multiplying power, secondly, under the conditions of high current density and long circulation, part of organic polymer electrodes still have the problems of interface impedance increase, slow reaction kinetics and faster capacity attenuation, and thirdly, when only C=O and C=N are used as main active centers, lithium storage active sites of a unit structure still have a further improvement space. Therefore, it is desirable to introduce new conjugated bridging units into polyimide schiff base backbones to further enhance the degree of electron delocalization, improve intrinsic conductivity, optimize interfacial charge transport, and provide more active sites available for participation in lithium storage reactions while maintaining structural stability. Thiophene is a typical sulfur-containing five-membered heterocycle, the lone pair electrons of sulfur atoms can participate in a conjugated system, the sulfur-containing five-membered heterocycle has strong electron donor capability and good polarization characteristics, and the sulfur-containing five-membered heterocycle is introduced into a polyimide Schiff base main chain, so that the conjugated structure is expected to be obviously expanded, the electron migration energy barrier is reduced, and the dynamics performance of an electrode material is improved. Disclosure of Invention The invention aims to provide a polyimide Schiff base polymer containing a thiophene structure and application thereof in a lithium ion battery, so as to solve the problems of insufficient conductivity, poor rate capability and limited long-cycle stability of the conventional organic anode material. The polyimide Schiff base polymer containing thiophene structure is abbreviated as PITD, and has the structural general formula shown in the specification, wherein