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Lithium sulfur battery cathode material and preparation method thereof

A cathode material, lithium-sulfur battery technology, applied in the direction of electrode carrier/current collector, etc., can solve the problems of difficult to control the morphology of sulfur-containing cathode materials, large diffusion path of lithium ions, low first Coulomb efficiency, etc., and achieve good cycle stability , to achieve large-scale industrial production, the effect of high first coulomb efficiency

Active Publication Date: 2015-08-12
CHERY AUTOMOBILE CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the morphology of the obtained sulfur-containing cathode material is difficult to control, resulting in a large diffusion path of lithium ions inside the cathode material during charge and discharge, which affects the performance of the battery.
[0004] In the process of realizing the present invention, the inventors have found that there are at least the following problems in the prior art: the first coulombic efficiency of the existing lithium-sulfur battery anode material is low in charge and discharge at a relatively large current, and the cycle stability is poor

Method used

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Examples

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preparation example Construction

[0023] In the above preparation method, the diameter of the polymer fiber is preferably 500-4000nm, for example, it can be 600nm, 800nm, 1000nm, 1200nm, 1400nm, 1600nm, 1800nm, 2000nm, 2200, 2400nm, 2600nm, 2800nm, 3000nm, 3200nm, 3400nm, 3600nm, 3800nm, 4000nm, etc. Among them, the diameter of the polymer fiber is more preferably 1000-3000nm.

[0024] In the above preparation method, the specific type of the polymer fiber is not strictly limited, as long as it can react with elemental sulfur to form a chemical bond at high temperature. Preference is however given to polymer fibers which are themselves electrically conductive, or which react with sulfur to produce electrically conductive products. For example, polyacrylonitrile fibers, phenolic resin fibers, polyvinyl chloride fibers, polyacetylene fibers, etc. may be used. Among them, polyacetylene fiber itself has conductivity, and polyacrylonitrile fiber can undergo cyanocyclization reaction at high temperature to form a c...

Embodiment 1

[0038] This embodiment provides a lithium-sulfur battery cathode material and a preparation method thereof, wherein the preparation method is as follows:

[0039] Mix phenolic resin fibers with a diameter of 100nm and sublimated sulfur powder at a mass ratio of 1:10, grind them evenly in a mortar, then put them into a ground-mouth weighing bottle protected by nitrogen gas, cover them and put them in a muffle In the furnace, raise the temperature to 500°C in a nitrogen atmosphere, keep it warm for 0.5 hours, and then obtain the positive electrode material for lithium-sulfur batteries after cooling.

[0040] The lithium-sulfur battery positive electrode material obtained in this example has a regular appearance and is fibrous. After the lithium-sulfur battery positive electrode material is assembled into a battery, the first discharge specific capacity of the obtained battery reaches 476mAh / g, the first efficiency is 85%, and 100 cycles The specific capacity after discharge rema...

Embodiment 2

[0042] Mix polyacrylonitrile fibers with a diameter of 1000nm and sublimed sulfur powder in a mass ratio of 1:1, grind them evenly in a mortar, then put them into a ground weighing bottle protected by nitrogen gas, cover them and put them in a horse In a Furnace, raise the temperature to 200°C in a nitrogen atmosphere and keep it warm for 12 hours. After cooling, the positive electrode material for lithium-sulfur batteries is obtained.

[0043] The lithium-sulfur battery positive electrode material obtained in this example has a regular appearance and is fibrous. After the lithium-sulfur battery positive electrode material is assembled into a battery, the first discharge specific capacity of the obtained battery reaches 756mAh / g, and the first-time efficiency is 78%. 100 cycles The specific capacity after discharge is still maintained at 517mAh / g, and the cycle capacity retention rate is 68.4%.

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Abstract

The invention discloses a lithium sulfur battery cathode material and preparation method thereof, and belongs to the technical field of lithium battery cathode material preparation. The preparation method of the lithium sulfur battery cathode is as follows: uniformly mixing polymer fiber and elemental sulfur, placing the mixed polymer fiber and elemental sulfur in a closed reaction container, raising temperature to 200-500 DEG.C in the inert gas atmosphere, keeping temperature for 0.5-12 hours, and performing cooling to obtain the lithium sulfur battery cathode material. The diameter of the polymer fiber is 100-5000nm, and the mass proportion of the polymer fiber to the elemental sulfur is 1: 1-1: 10. The lithium sulfur battery cathode material disclosed by the invention uses the polymer fiber with a quasi-one-dimensional nano-structure as a carrier, the obtained lithium sulfur battery cathode material is regular in feature; in the charging / discharging process of the lithium sulfur battery, a diffusion path of the lithium ion in the cathode material is about the size of the fiber semi-diameter, and the diffusion path is short; therefore, the lithium sulfur battery cathode material has high first coulombic efficiency and good cyclic stability in large current charging / discharging.

Description

technical field [0001] The invention relates to the technical field of preparation of lithium battery positive electrode materials, in particular to a lithium sulfur battery positive electrode material and a preparation method thereof. Background technique [0002] Lithium-sulfur battery is a lithium battery with sulfur as the positive electrode and lithium metal as the negative electrode. It is a newly developed high specific energy battery in recent years. Its theoretical specific energy is 2680Wh / kg, while the theoretical The specific energy is only 400~600Wh / kg. When the lithium-sulfur battery is being discharged, the negative electrode reaction is that lithium loses electrons and becomes lithium ions, and the positive electrode reaction is that sulfur reacts with lithium ions and electrons to form sulfide. But pure sulfur is an insulator of electrons and ions at room temperature (conductivity is 5×10 -30 S / cm), the transport of electrons and ions in the positive elect...

Claims

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Application Information

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IPC IPC(8): H01M4/66
CPCY02E60/10
Inventor 曾绍忠王秀田赵志刚陈效华
Owner CHERY AUTOMOBILE CO LTD
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