High-specific capacity lithium-sulfur secondary battery composite cathode and preparation method thereof

A lithium-sulfur secondary battery and composite cathode technology, applied in the field of electrochemical batteries, can solve the problems of poor cycle performance and high carbon content, and achieve the effects of high electrical conductivity, high sulfur content and excellent electrical conductivity

Inactive Publication Date: 2016-01-13
SHANGHAI INST OF SPACE POWER SOURCES
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The purpose of the present invention is to provide a sulfur / copper sulfide composite positive electrode with high sulfur content, high specific capacity and good cycle stability and its preparation for the problems of high carbon content and poor cycle performance in many current sulfur positive electrodes. method

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  • High-specific capacity lithium-sulfur secondary battery composite cathode and preparation method thereof
  • High-specific capacity lithium-sulfur secondary battery composite cathode and preparation method thereof

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[0025] The preparation method of the lithium-sulfur secondary battery composite positive electrode of the present invention comprises the following steps:

[0026] a) Place the elemental sulfur powder, copper powder and conductive carbon black required for electrode preparation in a vacuum oven to dry and set aside. The conductive carbon black used includes acetylene black, activated carbon, ordered or disordered mesoporous carbon, carbon nanotubes, conductive carbon fiber (VGCF), carbon aerogel, graphene, conductive graphite KS6 or Super-P. Elemental sulfur includes sublimated sulfur, crystalline sulfur, amorphous sulfur, colloidal sulfur and other forms of elemental sulfur. Copper powder particles are required to be micron or nano-sized;

[0027] b) According to the mass ratio of sublimated sulfur: copper powder: conductive agent (one or several kinds of conductive agent in step a): binder=65~85:20~1:5~6:10~8 Preparation of sulfur cathode. The binder used is polyvinyliden...

Embodiment 1

[0032] (1) Weigh the sublimed sulfur according to the mass ratio: Cu:SP:LA132=70:15:5:10, and add four times the solid mass of deionized water (that is, the solid-liquid ratio is 25%) to prepare a high-sulfur content positive pole piece;

[0033] (2) Place the prepared positive electrode piece in a vacuum oven at 80°C for 72h;

[0034] (3) The positive electrode sheet was detected and analyzed by thermogravimetry and elemental analyzer, and the elemental sulfur content in the final sulfur positive electrode was as high as about 63%. It can be seen from the calculation that the copper powder in the electrode is basically completely converted into copper sulfide.

[0035] The obtained electrode pole piece and lithium sheet were assembled into a 2032-type button battery for testing. The discharge curve at room temperature is as figure 1 As shown, the first discharge capacity can be as high as 1400mAh / g-S (milliampere hour / gram-sulfur). It can be seen from the discharge curves ...

Embodiment 2

[0037] (1) Weigh the sublimated sulfur according to the mass ratio: Cu:SP:LA132=70:15:5:10, and add deionized water four times the solid mass (that is, the solid-liquid ratio is 25%) to prepare a high-sulfur content positive pole piece;

[0038] (2) Place the prepared positive pole piece in a vacuum oven at 80°C for 24h;

[0039] (3) The positive electrode was detected and analyzed by thermogravimetry and elemental analyzer. The elemental sulfur content in the final sulfur positive electrode was as high as about 65%, indicating that the copper powder in the electrode was not completely converted into copper sulfide, and there were nearly 5wt% highly conductive particles in the electrode. copper powder.

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Abstract

The invention discloses a high-specific capacity lithium-sulfur secondary battery composite cathode and a preparation method thereof. The method comprises the following steps: (1) weighing elemental sulfur, copper powder, a conductive agent and a binder, and mixing the raw materials to prepare a sulfur cathode; and (2) putting the sulfur cathode prepared in the step (1) into a vacuum oven for drying at the temperature of 40-80 DEG C for 24-72 hours, so as to obtain the lithium-sulfur secondary battery composite cathode containing the elemental sulfur and copper sulphate. According to the composite cathode disclosed by the invention, the first discharge specific capacity reaches 1400mAh / g-S; the discharge capacity is kept at 997.8mAh / g-S after 30 cycles; and the lithium-sulfur secondary battery composite cathode also displays relatively good cycling stability. According to the preparation method disclosed by the invention, the manufacturing process is simplified; the cost is reduced; and the copper sulphate generated by a chemical method has relatively high reaction activity, and is conducive to improvement of the discharge capacity of a lithium-sulfur battery.

Description

technical field [0001] The invention belongs to the field of electrochemical batteries, and relates to a lithium-sulfur battery, in particular to a high specific capacity lithium-sulfur secondary battery composite positive electrode and a preparation method thereof. Background technique [0002] With the rapid development of portable electronic products, electric vehicles, smart grids and energy storage power stations, there is an increasing demand for the energy density of batteries. With the advantages of high theoretical energy density, low cost and abundant resources, lithium-sulfur secondary batteries have become a hot spot in the research of chemical power sources in recent years. [0003] Many researchers at home and abroad have conducted various in-depth studies on the inherent defects and technical difficulties of lithium-sulfur batteries (such as the low conductivity of sulfur leading to reduced activity and the dissolution of reaction intermediates in the electrol...

Claims

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Application Information

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IPC IPC(8): H01M4/139H01M4/1397H01M4/38H01M4/58H01M4/62H01M4/13H01M4/136H01M10/052
CPCH01M4/13H01M4/136H01M4/139H01M4/1397H01M4/38H01M4/5815H01M4/626H01M10/052Y02E60/10
Inventor 李永郭瑞刘雯裴海娟解晶莹
Owner SHANGHAI INST OF SPACE POWER SOURCES
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