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Preparation method and application of graphene-coated sulfur-selenium co-impregnated porous carbon positive electrode material

A graphene coating, cathode material technology, applied in battery electrodes, electrical components, electrochemical generators, etc., can solve the problems of poor compatibility between the coating layer and the electrolyte, low Coulomb efficiency, and rapid capacity decay, and achieve Excellent electrochemical performance, inhibition of flying shuttle reaction, high cycle stability effect

Inactive Publication Date: 2017-04-26
江华中科能源科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0002] Lithium-sulfur and lithium-selenium batteries are two types of lithium-ion secondary battery systems with high energy density that are currently being jointly developed by academia and industry, and are the representative and direction of secondary batteries with high energy density performance; however, lithium-sulfur / Lithium-selenium batteries generally have problems such as fast capacity decay and low Coulombic efficiency in the process of charging and discharging, which seriously hinder the practical application of batteries. Dissolution; At present, more studies are made on the use of carbonaceous porous materials and active materials to improve the electrochemical activity and cycle stability of positive electrode materials.
[0003] CN103825000A discloses a mesoporous carbon-loaded sulfur / selenium flexible electrode based on a three-dimensional graphene self-supporting structure and its preparation method and application; CN103500826A discloses a preparation method of a graphene / lithium battery cathode composite; CN105206799A discloses a porous metal-doped A method for preparing the positive electrode material of lithium heteromanganate / graphene lithium battery. On the one hand, due to the poor compatibility between the coating layer and the electrolyte, the solvent molecules will enter the coating layer during charging and discharging, which will cause the surface layer to peel off. The liquid continues to react with the new surface layer, resulting in a decrease in the cycle performance of the coating layer, and its performance has certain limitations; on the other hand, the use of a porous structure can promote the uniform dispersion of the material on the electrode surface, but the conductivity of the material itself still needs to be further improved. improve

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Embodiment 1

[0022] The preparation method of graphene-coated sulfur-selenium co-impregnated porous carbon positive electrode material comprises the following steps:

[0023] (1) Preparation of porous carbon nanosheets with sandwich structure: Dissolve 140-200mg graphene oxide in 70-120ml deionized water, and disperse evenly by ultrasonication for 1-3h; then 3.5-4.2g colloidal silica microspheres and 2.8- After 3.0 g of glucose was stirred evenly by ultrasonic, it was sealed in a reaction kettle and reacted at 180°C for 16 hours; the obtained brown cylindrical hydrogel was freeze-dried, and pre-carbonized at 800°C for 1.5-3 hours under the protection of argon, and then used 20wt % hydrofluoric acid to remove the colloidal silica microspheres and dry them, then mix them with potassium hydroxide in deionized water according to the mass ratio of 1:2.5-3.0, evaporate the solvent, and carbonize at 850°C for 1-2 hours. The obtained product was washed in deionized water until neutrally dried to o...

Embodiment 2

[0028] The preparation method of graphene-coated sulfur-selenium co-impregnated porous carbon positive electrode material comprises the following steps:

[0029] (1) Preparation of porous carbon nanosheets with a sandwich structure: Dissolve 140mg graphene oxide in 70ml deionized water and disperse evenly by ultrasonication for 1h; then 3.5g colloidal silica microspheres and 2.8g glucose are ultrasonically stirred and sealed in The reactor was reacted at 180°C for 16h; the resulting brown cylindrical hydrogel was freeze-dried, pre-carbonized at 800°C for 1.5h under the protection of argon, and then the colloidal silica microspheres were removed with 20wt% hydrofluoric acid After drying, mix evenly with potassium hydroxide in deionized water according to the mass ratio of 1:2.5, evaporate the solvent and carbonize at 850°C for 1 hour at high temperature, wash the obtained product in deionized water until neutral and dry to obtain a sandwich structure porous carbon nanosheets. ...

Embodiment 3

[0034] The preparation method of graphene-coated sulfur-selenium co-impregnated porous carbon positive electrode material comprises the following steps:

[0035](1) Preparation of porous carbon nanosheets with a sandwich structure: Dissolve 200mg graphene oxide in 120ml deionized water and disperse evenly by ultrasonication for 3h; then 4.2g colloidal silica microspheres and 3.0g glucose are ultrasonically stirred and sealed in The reactor was reacted at 180°C for 16h; the obtained brown cylindrical hydrogel was freeze-dried, pre-carbonized at 800°C for 3h under the protection of argon, and then the colloidal silica microspheres were removed with 20wt% hydrofluoric acid Dry, then mix with potassium hydroxide in deionized water according to the mass ratio of 1:3.0, evaporate the solvent and carbonize at 850°C for 2 hours at a high temperature, wash the obtained product in deionized water until neutral and dry to obtain a sandwich structure Porous carbon nanosheets.

[0036] (2...

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Abstract

The invention discloses a preparation method and an application of a graphene-coated sulfur-selenium co-impregnated porous carbon positive electrode material. By adoption of a sulfur-selenium fusion co-impregnated process, and by virtue of a synergistic effect of sulfur and selenium and a synergistic effect generated by combination of excellent conductivity of selenium and high theoretical capacity of sulfur, generation of a shuttle flying reaction is effectively restrained, and a composite positive electrode material with high rate capability and high cycling stability is obtained; by virtue of a graphene coating layer, the sulfur content in the composite material can be increased while dissolution and dispersion of a polysulfide can be suppressed; due to a synergistic effect of the graphene coating layer and porous carbon, the material obtains excellent electrochemical performance; the reversible capacity can reach 680mAhg<-1> and 560mAhg<-1> at current density of 0.1C and 1C after 100 discharging cycles; and in addition, greater than 96% of coulombic efficiency is constantly maintained.

Description

technical field [0001] The invention belongs to the field of battery material science, and in particular relates to a preparation method and application of a graphene-coated sulfur-selenium co-impregnated porous carbon cathode material. Background technique [0002] Lithium-sulfur and lithium-selenium batteries are two types of lithium-ion secondary battery systems with high energy density that are currently being jointly developed by academia and industry, and are the representative and direction of secondary batteries with high energy density performance; however, lithium-sulfur / Lithium-selenium batteries generally have problems such as fast capacity decay and low Coulombic efficiency in the process of charging and discharging, which seriously hinder the practical application of batteries. Dissolution; At present, more studies are made on the use of carbonaceous porous materials and active materials to improve the electrochemical activity and cycle stability of positive e...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M4/587H01M4/62H01M10/0525
CPCH01M4/364H01M4/366H01M4/38H01M4/587H01M4/624H01M4/628H01M10/0525Y02E60/10
Inventor 向红先
Owner 江华中科能源科技有限公司
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