Electric-conductive/lithium-conducting bi-functionalized graphene oxide material, preparation method thereof, and application thereof in Li-S battery or Li-air battery

A graphene and 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 reducing polarization problems

Active Publication Date: 2017-12-01
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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  • Electric-conductive/lithium-conducting bi-functionalized graphene oxide material, preparation method thereof, and application thereof in Li-S battery or Li-air battery
  • Electric-conductive/lithium-conducting bi-functionalized graphene oxide material, preparation method thereof, and application thereof in Li-S battery or Li-air battery

Examples

Experimental program
Comparison scheme
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 an electric-conductive / lithium-conducting bi-functionalized graphene oxide material, a preparation method thereof, and an application thereof in a Li-S battery or a Li-air battery. The material is formed by doping metal elements in graphene oxide grafted with a lithium-conducting compound. The preparation method includes the steps of grafting the lithium-conducting compound onto the graphene oxide and doping the metal elements through a liquid-phase reaction. Due to the lithium-conducting compound, the lithium-conducting function of a cathode material is improved, wherein the lithium-conducting compound, in the Li-S battery, is used for immobilizing polysulfides, and in the Li-air battery, can accelerate reaction of oxygen and lithium ions and reduce polarization of the battery; meanwhile, the embedded metal ions can improve electric-conductivity of graphene oxide, catalyzes decomposition of Li2O2 in the Li-air battery for solving a problem of polarization during charging / discharging of the battery, and constraints the polysulfides and inhibits the polysulfides from entering an electrolyte in the Li-S battery. The invention solves problems in Li-S battery and Li-air batteries in the prior art from a new aspect. The material has wide application prospect.

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 Applications(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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