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Hydrothermal preparation method of graphene-coated sulfur/porous carbon composite positive electrode material

A composite cathode material, graphene coating technology, applied in battery electrodes, electrical components, electrochemical generators, etc., can solve problems such as low electrochemical performance, and achieve the effect of inhibiting dissolution loss

Active Publication Date: 2014-09-24
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] The present invention aims to solve the technical problem of low electrochemical performance of existing graphene-coated sulfur-containing composite materials, and provides a hydrothermal preparation method of graphene-coated sulfur / porous carbon composite positive electrode materials

Method used

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  • Hydrothermal preparation method of graphene-coated sulfur/porous carbon composite positive electrode material

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specific Embodiment approach 1

[0058] Embodiment 1: The hydrothermal preparation method of the graphene-coated sulfur / porous carbon composite positive electrode material of the present embodiment is carried out according to the following steps:

[0059] 1. Prepare graphene slurry: the graphene slurry is composed of graphene and water, and the graphene sheets are uniformly dispersed in the slurry; wherein, the water content of the graphene slurry is 90% to 99.99%;

[0060] 2. Preparation of sulfur / porous carbon composite materials, wherein the porous carbon material is one or several of activated carbon, graphene, carbon black, carbon nanotubes, template porous carbon, carbon fiber, carbon aerogel, and carbide-derived carbon Composition, the mass ratio of sulfur and porous carbon in the sulfur / porous carbon composite material is 1:(0.02~20);

[0061] Three, according to the mass ratio of the graphene in the graphene slurry and the sulfur in the sulfur / porous carbon composite material is (0.02~20):1, the sulf...

specific Embodiment approach 2

[0063] Specific embodiment two: what this embodiment is different from specific embodiment one is that the specific preparation method of the graphene slurry in step one is as follows:

[0064] (1) Take graphite and reducing agent; wherein the mass ratio of graphite and reducing agent is 1:(0.1~1000); reducing agent is one or a combination of several in ascorbic acid, KOH, NaOH, LiOH and ammonia;

[0065] (2) the graphite oxidation that step (1) is taken becomes graphite oxide;

[0066] (3) According to the concentration of graphite oxide is 0.01mg mL -1 ~50mg mL -1 , adding the graphite oxide obtained in step (2) into water, stripping and dispersing for 0.5 to 10 hours under ultrasonic conditions with a frequency of 20 to 100 KHz, to obtain a graphene oxide aqueous dispersion;

[0067] (4) under the condition that the temperature is 4° C. to 100° C., add a reducing agent to the graphene oxide aqueous dispersion obtained in step (3), and reduce it for 0.2 h to 24 h under ult...

specific Embodiment approach 3

[0071] Specific embodiment three: what this embodiment is different from specific embodiment one or two is that graphite oxidation becomes the method for graphite oxide in step (2) as follows: in dry beaker, add 120mL mass percent concentration and be 98% H 2 SO 4 , then place the beaker in an ice-water bath, add 5g graphite and 2.5g NaNO 3 , stirring at a speed of 50-500 rpm, while gradually adding 15g of powdered KMnO 4 , continue to react for 2 hours in an ice-water bath and stirring; move the beaker into a constant temperature oil bath at 35±1°C and continue to react for 2 hours; slowly add 360mL of distilled water under stirring at a speed of 50 to 500 rpm, and control the temperature to be constant At 75°C, continue the constant temperature reaction for 1h; add 1000mL of distilled water at a temperature of 40°C, add 50mL of hydrogen peroxide with a concentration of 30% by mass, and then vacuum filter; wash the filter cake with hydrochloric acid with a concentration of 5...

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Abstract

The invention provides a hydrothermal preparation method of a graphene-coated sulfur / porous carbon composite material and relates to a preparation method of the graphene-coated sulfur / porous carbon composite material for a positive electrode material of a lithium-sulfur storage battery. The hydrothermal preparation method is used for solving the technical problem that the electrochemical property of the positive electrode material of an existing lithium-sulfur battery, namely a graphene-coated sulfur-containing composite material, is low. The hydrothermal preparation method comprises the steps of mixing and scattering the sulfur / porous carbon composite material with graphene slurry or oxidized graphene slurry, carrying out hydrothermal synthesis to prepare a hydrogel column, and drying to obtain the graphene-coated sulfur / porous carbon composite material. According to the graphene-coated sulfur / porous carbon composite material prepared by utilizing the hydrothermal preparation method, the outer surfaces of the graphene sheet layers are coated with sulfur / porous carbon composite material particles, a graphene conduction network is generated among the particles, and the obtained graphene-coated sulfur / porous carbon composite material is in a hierarchical core-shell structure; the positive electrode material has the high specific capacity, the long cycle life and the good rate capability; the composite positive electrode material can be used as a positive electrode material in a lithium secondary battery.

Description

technical field [0001] The invention belongs to the field of lithium secondary batteries, in particular to a method for preparing a graphene-coated sulfur / porous carbon composite material through a hydrothermal crosslinking process and its application in lithium-sulfur batteries. Background technique [0002] With the technological revolution in the field of new energy and the rapid development of intelligent and mobile electronic equipment, the research and development of batteries for electric vehicles, energy storage and electronic products has attracted widespread attention. Lithium-ion batteries currently occupying an absolute dominant position in the market cannot meet the requirements of high energy density due to the limited theoretical capacity of lithium-intercalated cathode materials. A new generation of lithium secondary battery cathode materials with high specific capacity, high rate performance, and high safety performance has become the battery industry. The k...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M4/62
CPCH01M4/38H01M4/625H01M4/628H01M10/0525Y02E60/10
Inventor 贾铮李振华韦华宇李程远
Owner HARBIN INST OF TECH
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