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Preparation method for double-layer carbon coated metal sulfide composite electrode material with core-shell structure

A technology of metal sulfide and core-shell structure, applied in nanotechnology for materials and surface science, battery electrodes, structural parts, etc., can solve problems affecting material capacity and performance, increasing irreversible capacity, shortening transmission path, etc. Achieve the effect of improving high rate performance, improving cycle stability, and simple process

Active Publication Date: 2018-11-27
CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

One is to nanosize the metal sulfide material, and reduce the internal stress generated during the charge and discharge process by shortening the transmission path of lithium ions and electrons, thereby improving the cycle stability and rate performance of the material. However, in fact, the nanoparticles directly interact with the electrolytic The contact with the liquid will catalyze the decomposition of the electrolyte, resulting in an increase in the irreversible capacity and low Coulombic efficiency. In addition, due to the large specific surface area and high specific surface energy of the nanoparticles, it is easy to cause the particles to agglomerate into large inactive clusters, which will affect the performance of the material. capacity and performance; the second is to combine the metal sulfide with an inactive matrix such as carbon material, and use the hardness and strength of carbon to suppress the volume change and mechanical stress of the active component during charge and discharge. At the same time, the carbon material itself is good Conductive properties, improve the overall performance of the material
At present, the synthesis of metal sulfide / carbon composite materials usually adopts the method of physical mixing or chemical compounding. Although the above-mentioned method improves the electrochemical performance of the composite material to a certain extent, due to the limitation of the method, it is inevitable that the surface of the carbon material There will be some metal sulfide nanoparticles that are not fully coated, and the direct contact of these active particles with the electrolyte will cause side reactions to occur, and at the same time, they will fall off the surface of the carbon-based material due to the repeated expansion / contraction of its volume during the cycle. resulting in reduced performance

Method used

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  • Preparation method for double-layer carbon coated metal sulfide composite electrode material with core-shell structure
  • Preparation method for double-layer carbon coated metal sulfide composite electrode material with core-shell structure
  • Preparation method for double-layer carbon coated metal sulfide composite electrode material with core-shell structure

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Experimental program
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Effect test

Embodiment 1

[0030] Add cobalt chloride hexahydrate dihydrate and pyrrole monomer into the reaction vessel at a molar ratio of 1:1, stir and mix evenly; slowly add the prepared ammonium persulfate into the step mixed solution at room temperature to initiate the polymer The monomer was polymerized and maintained for 16 h; the resulting mixture was directly kept in a blast oven at 100 °C for 10 h to obtain polypyrrole-coated Co 9 S 8 Precursor; polypyrrole-coated metal Co 9 S 8 The precursor was placed in a tube furnace, and ethanol was evenly loaded into the furnace with protective gas as the carrier gas. The temperature of the furnace was controlled at 800°C, and the catalytic decomposition reaction of ethanol was carried out on the surface of the precursor. After 5 hours, a coating layer with a thickness of about 8nm core-shell structure double-layer carbon-coated Co 9 S 8 composite material.

[0031] The prepared composite electrode material is subjected to XRD diffraction test, and...

Embodiment 2

[0034] The influence of CVD on the electrochemical performance during the preparation of composite electrode materials was compared.

[0035] Add cobalt chloride hexahydrate dihydrate and pyrrole monomer into the reaction vessel at a molar ratio of 1:1, stir and mix evenly; slowly add the prepared ammonium persulfate into the mixed solution at room temperature to trigger polymer monomer Bulk polymerization and maintaining the reaction for 16h; the resulting mixture was directly kept in a blast oven at 100°C for 10h to obtain polypyrrole-coated Co 9 S 8 Precursor; polypyrrole-coated metal Co 9 S 8 The precursors were placed in a tube furnace with N 2 For the protective gas, the furnace temperature was controlled at 800 °C, and after 5 h, a single-layer carbon-coated Co 9 S 8 composite material.

[0036] The obtained composite electrode material was made into a CR2032 button battery, and its charge and discharge performance was tested with a blue electric battery test syst...

Embodiment 3

[0038] The influence of carbon shell thickness on the electrochemical performance during the preparation of composite electrode materials was compared.

[0039] Add cobalt chloride hexahydrate dihydrate and pyrrole monomer into the reaction vessel at a molar ratio of 1:1, stir and mix evenly; slowly add the prepared ammonium persulfate into the mixed solution at room temperature to trigger polymer monomer Bulk polymerization and maintaining the reaction for 16h; the resulting mixture was directly kept in a blast oven at 100°C for 10h to obtain polypyrrole-coated Co 9 S 8 Precursor; polypyrrole-coated metal Co 9 S 8 The precursor was placed in a tube furnace, and ethanol was evenly loaded into the furnace with protective gas as the carrier gas. The temperature of the furnace was controlled at 800°C, and the catalytic decomposition reaction of ethanol was carried out on the surface of the precursor. After 4 hours, a coating layer with a thickness of about 5nm core-shell struc...

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Abstract

The invention discloses a preparation method for a double-layer carbon coated metal sulfide composite electrode material with a core-shell structure. An amorphous carbon material is arranged on an outer layer of the composite electrode material and a nitrogen-doped carbon coated metal sulfide is arranged on an inner layer. The preparation method disclosed by the invention is simple and feasible. The double-layer carbon coated metal sulfide composite electrode material with the core-shell structure is acquired according to the following steps: adopting a room temperature aggregation method foracquiring a polypyrrole coated Co9S8 precursor, and then taking a shielding gas as a carrier gas for uniformly filling ethyl alcohol into a tube furnace, and performing thermal treatment. When the composite material prepared according to the method is used as a cathode material of a lithium ion secondary battery, the outer layer carbon is capable of effectively inhibiting the direct contact between active material metal sulfide and electrolyte, so that the initial coulombic efficiency and cycle performance of the composite material are promoted. Meanwhile, the nitrogen-doped carbon material isintroduced, so that the conductivity of the material is further promoted, the huge volume expansion of the metal sulfide in charging and discharging processes is relieved and the structural stabilityand rate capability of the composite material are greatly improved.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries. Specifically relates to a preparation method of a double-layer carbon-coated metal sulfide composite electrode material with a core-shell structure. Background technique [0002] Due to its high energy density and safety, lithium-ion secondary batteries are attracting more and more attention along with the popularization of electric (hybrid) vehicles. Although graphitic carbon materials are widely used as anode materials for commercial lithium-ion batteries due to their good cycle performance, their low theoretical specific capacity cannot meet the increasing demand for energy, especially power energy, in today's society. Metal sulfides have a high theoretical capacity (such as Co 9 S 8 544mAh / g, CoS589mAh / g, CoS 2 871mAh / g and Ni 2 S609mAh / g), low price, and low pollution have attracted extensive research by researchers, and are considered to be one of the more promising anode...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/58H01M4/62H01M10/0525B82Y30/00
CPCH01M4/366H01M4/5815H01M4/625H01M4/628H01M10/0525B82Y30/00Y02E60/10
Inventor 段军飞吴应泷朱超
Owner CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY
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