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Method for preparing carbon quantum dot modified lithium-sulfur battery positive electrode materials

A technology of carbon quantum dots and positive electrode materials is applied in the field of preparation of positive electrode materials of carbon quantum dots modified lithium-sulfur batteries to achieve the effects of good charge and discharge performance, improved capacity and simple process.

Active Publication Date: 2019-03-19
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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  • Description
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  • Application Information

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Problems solved by technology

However, so far, zero-dimensional carbon quantum dots have not been used to design and improve the electrochemical interface of lithium-sulfur batteries. Among them, carbon quantum dots (CDots) are different from two-dimensional graphene and one-dimensional carbon nanotubes. A zero-dimensional carbon nanomaterial with unique properties

Method used

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  • Method for preparing carbon quantum dot modified lithium-sulfur battery positive electrode materials
  • Method for preparing carbon quantum dot modified lithium-sulfur battery positive electrode materials
  • Method for preparing carbon quantum dot modified lithium-sulfur battery positive electrode materials

Examples

Experimental program
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Embodiment 1

[0025] Step 1: preparing carbon quantum dots functionalized on the surface of polyethyleneimine, the specific steps are:

[0026] Place polyethyleneimine in a glass sample vial and place it on a heating platform at 400°C for 50 minutes of carbonization treatment. After the treatment, remove the glass sample vial from the heating platform, let it cool down to room temperature naturally, and then place it on the treated glass sample Add deionized water into the bottle, and perform ultrasonic treatment for 30 minutes to disperse the carbon quantum dots in the deionized water to form carbon quantum dot dispersion, put the carbon quantum dot dispersion into a dialysis bag for dialysis, and remove the unreacted polyethylene sub Amine, the carbon quantum dots with polyethylenimine surface functionalization can be obtained by freeze-drying the carbon quantum dot dispersion after the dialysis treatment;

[0027] Step 2: Mix the carbon quantum dots, sulfur powder, acetylene black and po...

Embodiment 2

[0032] Prepare a lithium-sulfur battery according to the steps in Example 1, only adjust the coating amount of sulfur on the surface of the carbon paper current collector in step 3 to 5.2mg / cm 2 , other steps remain unchanged. The lithium-sulfur battery that embodiment 2 obtains is in 6mA / cm 2 The long-term cycle capacity and Coulombic efficiency performance diagram of constant current charge and discharge under current density Image 6 shown.

Embodiment 3

[0034] Prepare a lithium-sulfur battery according to the steps in Example 1, only adjust the coating amount of sulfur on the surface of the carbon paper current collector in step 3 to 4 mg / cm 2 , other steps remain unchanged. The lithium-sulfur battery that embodiment 3 obtains at 6mA / cm 2 The attenuation rate of 400 cycles of long-cycle constant current charge and discharge under the current density is 0.02% per cycle.

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Abstract

The invention provides a method for preparing carbon quantum dot modified lithium-sulfur battery positive electrode materials, and belongs to the field of preparation of lithium-sulfur battery positive electrode materials. The method has the advantages that carbon quantum dots with functionalized polyethyleneimine surfaces are used for preparing lithium-sulfur battery positive electrodes, shuttling effects in battery charge and discharge procedures can be inhibited under polysulfide adsorption effects of polyethyleneimine, and accordingly the long cycle performance of lithium-sulfur batteriescan be guaranteed; the method for preparing the carbon quantum dot modified lithium-sulfur battery positive electrode materials includes simple and convenient processes, the capacity, the rates and the cycle performance of the lithium-sulfur batteries under working conditions of high load and high current density can be obviously improved, and accordingly the method has a potential application value in the field of lithium-sulfur batteries.

Description

technical field [0001] The invention belongs to the field of preparation of cathode materials for lithium-sulfur batteries, and in particular relates to a method for preparing cathode materials for lithium-sulfur batteries modified by carbon quantum dots. Background technique [0002] Among many lithium-ion electrochemical energy storage systems, lithium-sulfur batteries are considered to be a promising new generation of secondary lithium batteries, with a theoretical specific capacity of 1675mAh / g and a theoretical specific energy of 2600Wh / kg. , has great application potential. In addition, sulfur, as the positive electrode active material of lithium-sulfur batteries, has many advantages such as abundant reserves, wide sources, low toxicity and no pollution. However, during the charging and discharging process of lithium-sulfur batteries, long-chain polysulfides soluble in the electrolyte diffuse from the sulfur cathode to the lithium anode driven by the concentration gra...

Claims

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Application Information

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IPC IPC(8): H01M4/04H01M4/13H01M4/38H01M4/62H01M4/66H01M10/052
CPCH01M4/0404H01M4/13H01M4/38H01M4/625H01M4/663H01M10/052Y02E60/10
Inventor 熊杰胡音雷天宇陈伟闫裔超邬春阳吕晓雪
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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