WO2018187914A1 - Preparation method for polyanthraquinone thioether/ti3c2tx/sulfur composite material - Google Patents

Abstract

A polyanthraquinone thioether/Ti3C2Tx/sulfur composite material. The composite material is composed of sulfur, sheet Ti3C2Tx, and polyanthraquinone thioether; an inner layer is sulfur and a Ti3C2Tx composite material, and an outer layer is polyanthraquinone thioether with which the sulfur and the Ti3C2Tx composite material are coated, wherein the mass ratio of polyanthraquinone thioether to Ti3C2Tx to sulfur is 0.05-0.2:0.05-0.2:1. The polyanthraquinone thioether of the coating layer of the composite material can apply physical protection to a sulfur-based material, and limits polysulfide generated in the process of charging and discharging to be within the polyanthraquinone thioether, thereby reducing a shuttle effect; the composite material simultaneously limits the movement of the polysulfide from the two aspects of physical limit and chemical adsorption, and effectively prolongs the service life of a lithium-sulfur battery.

Description

Preparation method of polyfluorene sulfide/Ti ₃ c ₂ Τ _χ / sulfur composite material

 [0001] The present invention relates to nanomaterial synthesis, and in particular to a method for preparing a lithium sulfur battery cathode material.

 Background technique

 [0002] A lithium-sulfur battery is a battery system in which lithium metal is used as a negative electrode and elemental sulfur is a positive electrode. Lithium-sulfur batteries have two discharge platforms (approximately 2.4 V and 2.1 V), but their electrochemical reaction mechanisms are complex. Lithium-sulfur batteries have the advantages of high specific energy (2600 Wh/kg), high specific capacity (1675 mAh/g), and low cost, and are considered to be promising new generation batteries.

 technical problem

[0003] However, at present, there are problems such as low utilization rate of active materials, low cycle life and poor safety, which seriously restricts the development of lithium-sulfur batteries. The main causes of the above problems are as follows: (1) Elemental sulfur is an electron and ion insulator, and the room temperature conductivity is low (5x10 ^s^m). Since there is no ionic sulfur, it is difficult to activate as a positive electrode material; (2) The highly polylithium polysulfide Li ₂ S _n (8 >n>4) generated during the electrode reaction is easily soluble in the electrolyte, forming a concentration difference between the positive and negative electrodes, under the action of the concentration gradient Upon migration to the negative electrode, the highly polylithium polysulfide is reduced by lithium metal to oligomeric lithium polysulfide. As the above reaction proceeds, the oligomeric lithium polysulfide aggregates at the negative electrode, eventually forming a concentration difference between the two electrodes, and then migrating to the positive electrode to be oxidized to a highly polylithium polysulfide. This phenomenon is known as the shuttle effect, which reduces the utilization of sulfur active substances. The same insoluble Li ₂ 8 and Li ₂ S _{2 are} deposited on the surface of the lithium negative electrode, which further deteriorates the performance of the lithium sulfur battery; (3) The final product of the reaction, Li ₂ S, is also an electronic insulator, which is deposited on the sulfur electrode. Lithium ions migrate slowly in solid lithium sulfide, which slows the electrochemical reaction kinetics. (4) The density of sulfur and the final product Li ₂ S is different. When the sulfur is lithiated, the volume expands by about 79%, which easily leads to ₂ The powdering of 8 causes safety problems of lithium-sulfur batteries. The above-mentioned shortcomings restrict the development of lithium-sulfur batteries, which is also the key issue that needs to be solved in the research of lithium-sulfur batteries.

 Problem solution

 Technical solution

[0004] The technical problem to be solved by the present invention is to provide a polysulfonium sulfide/Ti ₃ C ₂ T _χ / sulfur composite material, the complex The composite material consists of sulfur, flake Ti ₃ C ₂ T _x and outer layer coated polysulfonium sulfide. The coating of polysulfonium sulfide limits the free movement of the sulfur-based material in the outer layer, flake Ti ₃ C ₂ Τ _χ Titanium can adsorb the dissolution of polysulfide in discharge products and improve the electrochemical performance of materials.

[0005] The present invention provides a polysulfonium sulfide / Ti ₃ C ₂ T _x / sulfur composite material, the composite material is composed of sulfur, flake Ti ₃

C ₂ T _X and polysulfonium sulfide, the inner layer is sulfur and Ti ₃ C ₂ T _x composite, and the outer layer is coated with sulfur and Ti ₃ C ₂

Polyfluorene sulfide of T _x composite material, polyfluorene sulfide: Ti ₃ C ₂ T _x

 : The mass ratio of sulfur is 0.05-0.2:0.05-0.2:1.

[0006] The present invention provides a method for preparing a polysulfonium sulfide/Ti ₃ C ₂ T _χ / sulfur composite material as follows:

[0007] (1) The Ti ₃ AlC ₂ ceramic powder is etched in hydrofluoric acid, and the solution is added to deionized water for centrifugation after etching, and then the precipitate is dried to obtain a stacked sheet of Ti ₃ C _{2 .} T _x powder;

[0008] (2) Ti ₃ C ₂ T _χ powder and elemental sulfur are uniformly mixed in a ratio of 1:1, placed in a sealed reaction vessel, and heated to a temperature of 155 ° C in a nitrogen atmosphere, constant temperature

5-12h, after the reaction is completed, it is cooled to room temperature to obtain a Ti ₃ C ₂ T _x / sulfur composite material;

[0009] (3) The obtained Ti ₃ C ₂ T _x / sulfur composite material is added to the N-methylpyrrolidone, stirred, and then added with 1,5-dichloroanthracene, and then the initiator ammonium persulfate is added, stirred, The mixture was allowed to stand, filtered, and vacuum dried to obtain a polysulfide sulfide/Ti ₃ C ₂ Τ _χ / sulfur composite.

[0010] The concentration of hydrofluoric acid in step (1) is 20<3⁄4-50<3⁄4, and the corrugated turn is 4-24 hours;

[0011] Ti ₃ C ₂ T _x in step (2)

 The mass ratio of the powder to the elemental sulfur is 0.05-0.2:1, the heating reaction temperature is 155-165 ° C, and the daytime is 5-12 吋;

 [0012] The ratio of 1,5-dichloroanthracene to elemental sulfur in step (3) is 0.05-0.2:1; the ratio of initiator to 1,5-dichloropurine is 1:0.01-0.1, initiator One of azobisisobutyronitrile, dibenzoyl peroxide, and ammonium persulfate is used.

 Advantageous effects of the invention

 Beneficial effect

[0013] The present invention has the following advantages: Ti Τ on _{χ 3} C ₂ T anthraquinone polyethylene sulfide / Ti ₃ C ₂ T _χ / sulfur composite material is -F group or a -OH group as a strong a polar group capable of forming a strong chemisorption of polysulfides formed during charging and discharging, and effectively preventing polysulfide from passing through the separator to the negative electrode; The coating polysulfonium sulfide can physically protect the sulfur-based material, restricting the polysulfide produced during the charging and discharging process inside the polysulfonium sulfide, thereby reducing the shuttle effect; the composite material from the physical limit and the chemical Adsorption on both sides limits the movement of polysulfides and effectively increases the life of lithium-sulfur batteries.

 Brief description of the drawing

 DRAWINGS

1 is a process flow diagram of the present invention.

2 is a graph showing the charge and discharge performance of the composite material of the present invention.

Embodiments of the invention

[0016] The preferred embodiments of the present invention are further described in detail below with reference to the accompanying drawings:

[0017] Embodiment 1

[0018] (1) Ti ₃ AlC ₂ ceramic powder is placed in a hydrofluoric acid having a mass concentration of 20% for 24 hours, and the solution is added to deionized water for centrifugation after etching, and then the precipitate is dried to obtain a stack. Layered Ti ₃ C ₂ T cliff;

[0019] (2) 0.5g Ti ₃ C ₂ T _x powder and 10g of elemental sulfur are uniformly mixed, placed in a sealed reaction vessel, heated to 155 ° C in a nitrogen atmosphere, constant temperature 12h, cooling after completion of the reaction To room temperature, a Ti ₃ C 2T _X / sulfur composite material is obtained;

[0020] (3) The obtained Ti ₃ C ₂ T _x / sulfur composite material was added to Ν-methylpyrrolidone and stirred, and then 0.5 g of 1,5-dichloroanthracene was added, followed by addition of 0.05 g of initiator azo. Diisobutyronitrile, stirred, stood, filtered, vacuum dried to obtain a polysulfide sulfide/Ti ₃ C ₂ Τ _χ / sulfur composite.

 Embodiment 2

[0022] (1) Ti ₃ AlC ₂ ceramic powder is placed in a hydrofluoric acid having a mass concentration of 50% for 4 hours, and after etching, the solution is added to deionized water for centrifugation, and then the precipitate is dried to obtain a stack. Layered Ti ₃ C ₂ T morning;

[0023] (2) ₂ g of Ti ₃ C ₂ T _x powder and 10 g of elemental sulfur were uniformly mixed, placed in a sealed reaction vessel, heated to 165 ° C in a nitrogen atmosphere, kept at a constant temperature for 5 h, and cooled to after completion of the reaction. At room temperature, Ti ₃ C ₂ T is obtained 1,5-Dichloropurine is stirred, then 0.02 g of initiator dibenzoyl peroxide is added, stirred, allowed to stand, filtered, and vacuum dried to obtain polysulfide sulfide/Ti ₃ C ₂ Τ _χ / sulfur composite material.

Embodiment 3

[0026] (1) The Ti ₃ AlC ₂ ceramic powder is placed in a hydrofluoric acid having a mass concentration of 30% for 20 hours, and the solution is added to deionized water for centrifugation after etching, and then the precipitate is dried to obtain a stack. Layered Ti ₃ C ₂ T morning;

[0027] (2) The lgTi ₃ C ₂ T _x powder is uniformly mixed with 10 g of elemental sulfur, placed in a sealed reaction vessel, heated to 160 ° C in a nitrogen atmosphere, kept at a constant temperature for 10 h, and cooled to after completion of the reaction. At room temperature, a Ti ₃ C ₂ T _x /sulfur composite material is obtained;

[0028] (3) The obtained Ti ₃ C ₂ T _x / sulfur composite material is added to the Ν-methylpyrrolidone, stirred, and then added lg

1,5-Dichlorohydrazine was stirred, then 0.05 g of an initiator ammonium persulfate was added, stirred, allowed to stand, filtered, and vacuum dried to obtain a polysulfide sulfide/Ti ₃ C ₂ Τ _χ / sulfur composite.

 Embodiment 4

[0030] (1) Ti ₃ AlC ₂ ceramic powder is placed in hydrofluoric acid having a mass concentration of 40% for 15 hours, and after etching, the solution is added to deionized water for centrifugation, and then the precipitate is dried to obtain a stack. Layered Ti ₃ C ₂ T cliff;

[0031] (2) 1.5 g of Ti ₃ C ₂ T _x powder was uniformly mixed with 10 g of elemental sulfur, placed in a sealed reaction vessel, and heated to 162 ° C in a nitrogen atmosphere at a constant temperature for 8 h. To room temperature, a Ti ₃ C ₂ T _x /sulfur composite material is obtained;

[0032] (3) The obtained Ti ₃ C ₂ T _x / sulfur composite material was added to the Ν-methylpyrrolidone and stirred, and then 1.5 g of 1,5-dichloroanthracene was added, followed by the addition of 0.08 g of the initiator azo. Diisobutyronitrile, stirred, stood, filtered, vacuum dried to obtain a polysulfide sulfide/Ti ₃ C ₂ Τ _χ / sulfur composite.

 Example 5

[0034] (1) Ti ₃ AlC ₂ ceramic powder is placed in hydrofluoric acid with a concentration of 35% for 13h, after etching, the solution is added to deionized water for centrifugation, and then the precipitate is dried to obtain a stack. Layered Ti ₃ C ₂ T morning;

[0035] (2) 0.8 g of Ti ₃ C ₂ T _x powder was uniformly mixed with 10 g of elemental sulfur, placed in a sealed reaction vessel, and heated to 157 ° C in a nitrogen atmosphere at a constant temperature for 9 hours. To room temperature, Ti ₃ C _{2 is obtained} T _x / sulfur composite material;

[0036] (3) The obtained Ti ₃ C ₂ T _x / sulfur composite material is added to the Ν-methylpyrrolidone and stirred, and then 0.8 g is added.

1,5-Dichloropurine is stirred, then 0.03 g of initiator dibenzoyl peroxide is added, stirred, allowed to stand, filtered, and vacuum dried to obtain polysulfonium sulfide/Ti ₃ C ₂ Τ _χ / sulfur composite material.

[0037] Electrode preparation and performance testing; composite materials, acetylene black and PVDF

 Mixed in a crucible at a mass ratio of 80:10:10, coated on an aluminum foil as an electrode film, and a lithium metal plate as a counter electrode, CELGARD

 2400 is a diaphragm, 1 mol/L of LiTFSI/DOL-DME (volume ratio 1:1) is an electrolyte, and 1 mol/L of LiN03 is an additive. It is assembled into a button-type battery in a filled glove box, and is tested by a Land battery test system. Constant current charge and discharge test. The charge and discharge voltage range is 1-3V, and the current density is 0.2C. The performance is shown in Table 1.

 Table 1

 [] [Table 1]

 [0039]

 2 is a graph showing the charge and discharge performance of a composite material prepared into a lithium-sulfur battery according to Embodiment 1 of the present invention. It can be seen from the figure that the charge and discharge efficiency can reach 98% or more, and the first charge and discharge capacity is 1052.

 mAh/g, charge and discharge efficiency is 98.1%. After 500 charge and discharge cycles, the capacity still retains 65<3⁄4, indicating that the structure of the composite can effectively suppress the shuttle effect and improve the life of the sulfur battery.

[0041] The above is a further detailed description of the present invention in conjunction with the specific preferred embodiments. It is not intended that the specific embodiments of the invention are limited to the description. It will be apparent to those skilled in the art that the present invention may be practiced without departing from the spirit and scope of the invention.

Claims

Claim

[Claim 1] A polysulfonium sulfide/Ti ₃ C ₂ T _x /sulfur composite material, characterized in that the composite material is composed of sulfur, flake Ti ₃ C ₂ T _x and polyfluorene sulfide. The inner layer is sulfur and 11^ ₂ 1\ composite material, and the outer layer is coated with sulfur and Ti ₃ C ₂ T _x

The polythene sulfide of the composite material has a mass ratio of polysulfonium sulfide: Ti ₃ C ₂ T _x : sulfur of 0.05-0.2:0.05-0.2:1.

[Claim 2] A method of preparing a polysulfide sulfide/Ti ₃ C ₂ T _χ / sulfur composite material according to claim 1

, which is characterized by the following steps:

Step (1): Ti ₃ AlC^ _3⁄4 porcelain powder is etched in hydrofluoric acid, and the solution is added to deionized water for centrifugation after etching, and then the precipitate is dried to obtain a stacked sheet of Ti 3C ₂ Τ _χ powder;

Step (2): uniformly mixing Ti ₃ C ₂ T _x powder with elemental sulfur in a sealed reaction vessel, heating the reaction in a nitrogen atmosphere, keeping the temperature constant, and cooling to room temperature after completion of the reaction to obtain Ti _{3 .} C ₂ Τ _χ / sulfur composite material;

Step (3): adding the obtained Ti ₃ C ₂ T _x / sulfur composite material to Ν-methylpyrrolidone, stirring, adding 1,5-dichloroanthracene, and then adding the initiator ammonium persulfate, stirring, and quenching Set, filter, and vacuum dry to obtain a polysulfide sulfide/Ti ₃ C ₂ T _x / sulfur composite.

 [Claim 3] The method according to claim 2, wherein the concentration of hydrofluoric acid in the step (1) is 20 < 3⁄4 - 50 < 3⁄4, and the corrugated turns are 4-24 hours.

[Claim 4] The method according to claim 2, wherein in the step (2), Ti ₃ C ₂ T _{x 3⁄4}

 The mass ratio of the body to the elemental sulfur is 0.05-0.2:1, the heating reaction temperature is 155-165 ° C, and the daytime is 5- 12 hours.

 [Claim 5] The method according to claim 2, wherein the ratio of 1,5-dichloroanthracene to elemental sulfur in the step (3) is 0.05-0.2:1; The ratio of 1,5-dichloropurine is 1:0.1-0.1, and the initiator is one selected from the group consisting of azobisisobutyronitrile, dibenzoyl peroxide, and ammonium persulfate.