A conductive lithium-conducting bifunctional graphene oxide material and its preparation method and application in lithium-sulfur or lithium-air batteries

A graphene, dual-function technology, applied in the field of lithium battery preparation, can solve the problems of poor cycle performance and low capacity, and achieve the effects of reducing battery polarization, improving cycle life and speeding up reaction

Active Publication Date: 2019-12-13
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Aiming at the problems of poor cycle performance and low capacity of lithium-sulfur and lithium-air batteries in the prior art, the purpose of the present invention is to provide a lithium-conducting compound with good conductivity and lithium-conducting performance and graphite oxide modified with metal elements vinyl material

Method used

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  • A conductive lithium-conducting bifunctional graphene oxide material and its preparation method and application in lithium-sulfur or lithium-air batteries
  • A conductive lithium-conducting bifunctional graphene oxide material and its preparation method and application in lithium-sulfur or lithium-air batteries

Examples

Experimental program
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Effect test

Embodiment 1

[0038] Preparation of bifunctional graphene oxide / sulfur composite cathode materials with conductive lithium and conductive components:

[0039] Preparation of composite material: Weigh 1g of flake graphite and place it in a 250mL round bottom flask, add 100mL of concentrated sulfuric acid (≧98%) and 13.3mL of concentrated phosphoric acid (≧85%), stir at 50°C at 500r / min for 12h, Pour the mixture into 400mL of ice, add 3mL of hydrogen peroxide dropwise, and after stirring evenly, the solution becomes a yellow-brown suspension, which is centrifuged and washed 5 times with deionized water at a centrifugal rate of 10,000r / min. Disperse in 200mL deionized water, and ultrasonically vibrate for 3 hours to obtain a graphene oxide suspension.

[0040] Measure 10 mL of graphene oxide suspension, add 0.2 mL of single-head PEG to it, and set up a reflux device, protect it with argon, raise the temperature to 50 ° C, and keep stirring the solution at 500 r / min, add 2 mL of concentrated S...

Embodiment 2

[0045] A bifunctional graphene oxide / sulfur composite material with the same material ratio as in Example 1 was prepared, assembled into an all-solid-state lithium-sulfur battery, and subjected to a 0.2C rate charge and discharge test at 80°C, and the first discharge specific capacity was 1234.2mAh / g , after 25 cycles, the discharge specific capacity is 1068.2mAh / g, and the efficiency is 98.9%. Under the condition of 80℃, the charge-discharge test with different rates was carried out. The specific capacity of the discharge at 0.2C in the first cycle was 1245.7mAh / g. After 5 cycles, the discharge specific capacity at 0.5 was 852.5mAh / g. After 10 cycles, the discharge specific capacity at 1C After 15 cycles, the discharge specific capacity at 2C is 422.8mAh / g. When the rate gradually returns to 0.2C, the discharge specific capacity is 985.6mAh / g after 35 cycles, and the efficiency is 98.3%.

Embodiment 3

[0047] Prepare the bifunctional graphene oxide / sulfur composite material and the positive electrode sheet with the same material ratio as in Example 1, and use the positive electrode sheet / lithium sulfide electrolyte / lithium sheet to prepare the positive electrode sheet of the lithium-sulfur battery Assembled into a liquid lithium-sulfur button battery, at 25°C and 0.1C, the specific discharge capacity of the first cycle is 1524mAh / g, and after 20 cycles, the discharge specific capacity is 1269mAh / g, and the efficiency is 98.3%. The 1C rate charge and discharge test was carried out at 25°C. The first discharge specific capacity was 1237.2mAh / g, and after 200 cycles, the discharge specific capacity was 875.2mAh / g, and the efficiency was 98.2%.

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Abstract

The invention discloses a conductive and lithium-conducting bifunctional graphene oxide material and its preparation method and application in lithium-sulfur or lithium-air batteries; the material is doped with metal elements on graphene oxide grafted with a lithium-conducting compound The preparation method is to graft a lithium-conducting compound in graphene oxide, and then further dope metal elements through a liquid phase reaction; the introduction of the lithium-conducting compound improves the lithium-conducting function of the positive electrode material, and in lithium-sulfur batteries It plays the role of fixing polysulfides. In lithium-air batteries, it can speed up the reaction between oxygen and lithium ions and reduce battery polarization; while the embedded metal ions can improve the conductivity of graphene oxide, which can catalyze in lithium-air batteries. Li 2 o 2 The decomposition of the battery reduces the polarization problem during the charging and discharging process of the battery. In the lithium-sulfur battery, polysulfides are bound and the polysulfides are reduced into the electrolyte; from a new perspective, the problems existing in the current lithium-sulfur and lithium-air batteries are solved. It has broad application prospects.

Description

technical field [0001] The invention relates to a conductive lithium-conducting bifunctional graphene oxide material and its application in lithium-sulfur or lithium-air batteries, as well as a preparation method thereof, belonging to the technical field of lithium battery preparation. Background technique [0002] With the rapid development of new energy technology, lithium-ion batteries have been widely used in military defense, electric vehicles, portable digital devices and other fields. At the same time, their performance requirements are getting higher and higher, especially safety performance and energy density. [0003] Lithium-sulfur batteries use high-capacity elemental sulfur (1675mAh / g) as the positive electrode, and the specific energy can reach 2600Wh / kg, which has attracted widespread attention. However, sulfur and its discharge products have poor electronic and ionic conductivity, and the polysulfides produced during the discharge process will dissolve in the...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/62H01M10/052H01M12/08
CPCH01M4/625H01M10/052H01M12/08Y02E60/10
Inventor 刘晋刘业翔杜英林月张诚
Owner CENT SOUTH UNIV
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