High-performance lithium-containing organic sulfur electrode material and preparation method of integrated flexible electrode
阅读说明：本技术 高性能含锂有机硫电极材料及一体化柔性电极的制备方法 (High-performance lithium-containing organic sulfur electrode material and preparation method of integrated flexible electrode ) 是由 郑时有 杨俊和 董飞 庞越鹏 于 2019-11-01 设计创作，主要内容包括：本发明提出了高性能含锂有机硫电极材料及一体化柔性电极的制备方法,本发明以具有双烯烃键的1,3-二异丙烯基苯和Li2S6作为前驱体通过原位聚合的方法,反应生成含锂的有机硫化物Poly(Li<Sub>2</Sub>S<Sub>6</Sub>-r-DIB)。由于合成的含锂有机硫化物Poly(Li<Sub>2</Sub>S<Sub>6</Sub>-r-DIB)加热到一定温度表现出良好的粘性,可直接附着在柔性的导电碳布上,从而制得一体化的柔性电极。得到的柔性电极,具有高容量、高柔韧度、结构稳定等优点。(The invention provides a high-performance lithium-containing organic sulfur electrode material and a preparation method of an integrated flexible electrode, which react to generate lithium-containing organic sulfide Poly (Li) by taking 1, 3-diisopropenyl benzene and Li2S6 with diene bonds as precursors through an in-situ polymerization method 2 S 6 -r-DIB). Due to the synthetic lithium-containing organic sulfide Poly (Li) 2 S 6 r-DIB) exhibit good adhesion when heated to a certain temperatureAnd then attached to a flexible conductive carbon cloth to produce an integrated flexible electrode. The obtained flexible electrode has the advantages of high capacity, high flexibility, stable structure and the like.)
1. The preparation method of the high-performance lithium-containing organic sulfur electrode material is characterized by comprising the following steps:
step one, Li is used2S and sublimed sulfur as raw materials, tetrahydrofuran as a medium, inLi in an inert gas environment at 40-60 DEG C2S and sublimed sulfur react for 24 hours at a molar ratio of 1:5 to obtain Li2S6A THF solution of (1);
step two, adding Li obtained in step one2S6Adding a certain amount of 1, 3-diisopropenyl benzene into the THF solution, reacting at 130-150 deg.C for 30-60min to generate polymerization reaction, and obtaining lithium-containing organic sulfide Poly (Li)2S6-r-DIB)；
Step three, the lithium-containing organic sulfide Poly (Li) obtained in the step two2S6Heating the-r-DIB) solution to 70-80 ℃, evaporating and separating the THF solvent under vacuum condition to finally obtain the pitch-like black lithium-containing organic sulfide Poly (Li)2S6-r-DIB)。
2. The method of claim 1, wherein the mass fraction of 1, 3-diisopropenylbenzene is one of 5%, 10%, 15%, 20%, 25%, 30%, and 50%.
3. The preparation method of the integrated flexible electrode is characterized by comprising the following steps: black lithium-containing organosulfur compound Poly (Li) obtained by the production method according to any one of claims 1 to 22S6-r-DIB) is heated to 50-70 ℃, and is directly and uniformly coated on the flexible conductive cloth by a coating method, thereby manufacturing the integrated organosulfur electrode.
4. The method for preparing the integrated flexible electrode according to claim 4, wherein the conductive cloth is a carbon fiber woven fabric.
5. An integrated flexible electrode, characterized in that it is produced by the production method according to any one of claims 1 to 4.
Technical Field
The invention relates to the technical field of organic polymer materials and integrated electrode devices, in particular to a high-performance lithium-containing organic sulfur electrode material and a preparation method of an integrated flexible electrode.
Background
High capacity, light weight and flexibility are the most important development trends of portable electronic products, and as the times and society continue to develop, the foldable or bendable portable electronic products will affect or even change the life style of human beings in the near future. The energy storage device is a core component of a portable electronic product, and the development of the energy storage device with high performance, flexibility, light weight and other comprehensive properties is one of the keys of the wide application of the flexible electronic product. Therefore, the development and utilization of energy storage devices with high specific capacity, flexibility, light weight and other comprehensive properties are the key points for the wide application of flexible electronic products.
The lithium-sulfur battery is used as a new generation energy storage system and has a theoretical specific capacity (1672mAh g)-1) The lithium ion battery is far higher than the current commercial lithium ion battery, and can meet the requirement of most electronic equipment on energy storage. Lithium-sulfur batteries are a particularly attractive and low-cost energy storage technology due to the abundance and economy of sulfur in the earth's crust. Although sulfur positive electrodes in lithium-sulfur battery systems have advantages of low cost and environmental friendliness, long-term research has revealed that some disadvantages exist in lithium-sulfur systems, which also hinder the commercialization of lithium-sulfur battery systems. During the charge-discharge cycle of a lithium-sulfur battery, the electrochemical process is not completed in one step, but includes a series of conversion reactions and polysulfides (Li)2Sx,2<x.ltoreq.8), which results in a volume expansion of the sulfur and in a shuttling effect. Moreover, sulfur is a poor conductor, particularly a low electrical conductivity, and these defects result in a significant reduction in the cycle life of the battery. However, among the above drawbacks, the shuttle effect of the lithium sulfur battery is the most fatal. During discharge and charge cycles, long-chain polysulfides (Li) soluble in the electrolyte are generated in the positive electrode2Sx,4<x is less than or equal to 8) moves to the negative electrode and reacts with lithium metal to form short-chain polysulfide (Li) insoluble in electrolyte2Sx,2<x is less than or equal to 4) and the short-chain polysulfide diffuses back to the anode and is regenerated againLong-chain polysulfides. This process typically results in irreversible loss of the active material and low coulombic efficiency, which is the main cause of rapid capacity fade, low energy efficiency, severe self-discharge, and poor cycling stability.
In view of the above-mentioned drawbacks, especially the shuttle effect, researchers at home and abroad mainly conduct research on material modification and chemical polymerization. One is the material modification aspect, which can synergistically reduce the shuttling effect of lithium polysulfides by physical confinement of the nanopores and increasing the chemical affinity of sulfur with the carbon matrix. For example, yolk-shell structure composites of sulfur, polysulfide absorber materials, and various nanostructured carbon materials are prepared as sulfur host materials to confine sulfur within its channels, including ordered mesoporous carbon (CMK-3), carbon nanotubes, carbon nanofibers, carbon spheres, graphene oxide, and conductive polymers, among others. Although heteroatom doping and surface functionalization of carbon materials promotes chemical capture of polysulfides and increases the affinity between the porous matrix and polysulfides, the capture efficiency of lithium polysulfides is still unsatisfactory due to the limited surface area and the small number of adsorption sites. In addition, the large pore size and non-uniform distribution of these functional groups present major obstacles to the uniform distribution of sulfur and the preferential deposition of solid products on carbon substrates.
In the aspect of chemical polymerization, a special organic polymer obtained through polymerization reaction is used as a new sulfur anode material. The organic polymer is obtained by crosslinking polymerization using a monomer having a plurality of polymerizable radical groups with a long sulfur chain (the melt-broken sulfur-eight-membered ring molecule has a diradical at a temperature of 100 ℃ to 200 ℃). However, the conventional organic sulfur as the positive electrode material of the lithium sulfur battery still uses the conventional slurry smear method, and the capacity loss of the battery in the initial cycle is not improved well.
Disclosure of Invention
The invention aims to provide a high-performance lithium-containing organic sulfur electrode material and a preparation method of an integrated flexible electrode. On one hand, the traditional method for preparing the electrode by stirring the slurry smear is abandoned, so that the active substance can be directly coated on the carbon cloth without adding a binder and conductive carbon; on the other hand, the lithium-containing organic sulfide prepared by using a chemical polymerization method not only fastens sulfur atoms in a crosslinked polymer in a form of chemical bonds, but also introduces lithium ions into the molecule, so that the capacity loss of the lithium-sulfur battery in the initial cycle can be well inhibited.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a method for preparing a high performance lithium-containing organosulfur electrode material comprising: 1) with Li2S and sublimed sulfur are used as raw materials, Tetrahydrofuran (THF) is used as a medium, and Li is used in an inert gas environment at the temperature of 40-60 DEG C2S and sublimed sulfur react for 24 hours at a molar ratio of 1:5 to obtain Li2S6A THF solution of (1); 2) to Li prepared in step 12S6Adding a certain amount of 1, 3-Diisopropenylbenzene (DIB) into the THF solution, reacting at 130-150 ℃ for 30-60min to perform polymerization reaction to obtain lithium-containing organic sulfide Poly (Li)2S6-r-DIB), wherein the mass fraction of DIB can be adjusted arbitrarily within a certain range; 3) the lithium-containing organic sulfide Poly (Li) prepared in the step 22S6Heating the-r-DIB) solution to 70-80 ℃, evaporating and separating the THF solvent under vacuum condition to finally obtain the pitch-like black lithium-containing organic sulfide Poly (Li)2S6-r-DIB)。
In the preparation method of the high-performance lithium-containing organic sulfur electrode material, the Li in the step 22S6The THF solution of (1) has a concentration of 160mg ml-1. The mass fraction of the 1, 3-diisopropenyl benzene is one of 5%, 10%, 15%, 20%, 25%, 30% and 50%, wherein the mass fraction of the 1, 3-diisopropenyl benzene refers to the mass fractions of the 1, 3-diisopropenyl benzene and Li2S6Polymerization reaction to obtain Poly (Li)2S6r-DIB), the mass of 1, 3-diisopropenylbenzene added is equal to the mass of the
The preparation method of the integrated flexible electrode comprises the following steps: the black lithium-containing organic sulfide Poly (Li) obtained by the preparation method2S6-r-DIB) is heated to 50-70 ℃, and is directly and uniformly coated on the flexible conductive cloth by a coating method, thereby manufacturing the integrated organosulfur electrode.
In the preparation method of the integrated flexible electrode provided by the invention, the conductive cloth is a carbon fiber braided fabric.
The integrated flexible electrode is prepared by adopting the preparation method.
Compared with the prior art, the invention has the advantages that:
1. the lithium-containing organic sulfide prepared by the invention not only solves the problem of low shuttle-threading effect of the traditional S/C composite material, but also solves the problem of poor conductivity of the conventional organic sulfide.
2. The integrated electrode designed by the invention does not need the addition of a binder and extra conductive carbon, improves the sulfur carrying capacity and the volume specific capacity of the battery, and has simple preparation method and low preparation cost.
3. The lithium-containing organic sulfide electrode material and the integrated electrode obtained by the method have the characteristics of good flexibility, high specific capacity and good cycling stability.
Drawings
Fig. 1 is a graph showing the capacity and the charge/discharge efficiency of a battery prepared by using a lithium-containing organosulfide integrated flexible electrode as a positive electrode and a pure lithium sheet as a negative electrode according to an embodiment of the present invention.
FIG. 2 shows a battery prepared by using the lithium-containing organic sulfide integrated flexible electrode of the embodiment of the invention as a positive electrode and a pure lithium sheet as a negative electrode, wherein the battery is 0.1A g-1～2A g-1Discharge capacity curve chart under charge and discharge current density.
Detailed Description
The technical solution adopted by the present invention will be further explained with reference to the schematic drawings.