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Nitrogen-doped barbed carbon nanosphere/sulfur composite material and preparation method and application thereof

A technology of carbon nanospheres and composite materials, applied in the fields of nanomaterials and electrochemical energy, can solve the problem that it is impossible to determine whether sulfur is outside or inside the hollow sphere, the conductivity of sulfur cannot be greatly improved, and the utilization of active materials can be reduced. rate and other problems, to achieve the effect of low cost of raw materials and equipment, enhanced physical adsorption, and improved electrical activity

Active Publication Date: 2020-02-14
WENZHOU UNIVERSITY
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But such a hollow structure is like a drug capsule, which wraps the active sulfur on the hollow part of the sulfur and the porous spherical shell, and it is impossible to determine whether the sulfur is outside or inside the hollow sphere.
At the same time, due to the single cavity inside the material, the active material sulfur always exists in the form of blocks. However, the electrochemical process of the lithium-sulfur battery is always generated at the interface. Due to the uneven dispersion of sulfur, this will inevitably reduce the utilization of the active material. rate, it is not enough to disperse only by the thin carbon wall of the outer layer, which makes the conductivity of sulfur not greatly improved and seriously weakens the capacity of the battery

Method used

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  • Nitrogen-doped barbed carbon nanosphere/sulfur composite material and preparation method and application thereof
  • Nitrogen-doped barbed carbon nanosphere/sulfur composite material and preparation method and application thereof
  • Nitrogen-doped barbed carbon nanosphere/sulfur composite material and preparation method and application thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] Step 1, preparation of silica nanospheres:

[0035] Weigh 2g of hexadecyl bromide pyridine and 1.2g of urea, mix and dissolve in 60mL of water, and take 5g of tetraethyl orthosilicate, dissolve in a mixed solution of 60mL of cyclohexane and 3mL of n-pentanol, and stir at room temperature 60 minutes, transferred to a reaction kettle, reacted at 120°C for 6 hours, cooled, filtered, washed to obtain a white solid, dried, transferred to a muffle furnace for roasting, and obtained white silica nanospheres.

[0036] Step 2, preparation of nitrogen-doped barbed carbon nanospheres:

[0037] Weigh 4g of glucose and 0.5g of the above-prepared silica nanospheres, mix them, stir and dissolve in 75ml of aqueous solution, then transfer to a 100ml polytetrafluoroethylene hydrothermal reaction kettle, heat and keep at 180°C for 12h, after cooling , filtered, washed with water and ethanol successively, dried, Ar and NH 3 Heat treatment at 800°C for 2 hours at a ratio of 9:1, the obtai...

Embodiment 2

[0048] Take 0.08 g of the nitrogen-doped barbed carbon nanosphere (NCS) sample prepared in step 2 of Example 1, mix with 0.24 g of sulfur powder, seal it, place it in an oven at 165° C. for heating, and take it out after cooling for 12 hours to obtain nitrogen Doped barbed carbon nanospheres / sulfur composites (370nm-CNS / S74%-1:8). According to the method in step 4, prepare electrodes and assemble batteries, and perform routine performance tests, the current density is 0.2C, and the specific capacity of the second cycle discharge is 1087mAh g -1 .

[0049] Summary: The variables in Example 1 and Example 2 are the proportion of sulfur in the composite material, which are 60wt% and 74wt% respectively, the sulfur content of 60% is lower than that of 74%, and the discharge capacity at 1C rate (calculated based on sulfur mass ) is slightly improved, and the remaining capacity of the battery is 413mAh g after 1000 cycles -1 , The Coulombic efficiency of the battery can reach 96%. ...

Embodiment 3

[0051] Using 3.5 g of glucose and 0.5 g of silica nanospheres prepared in step 1 as raw materials, according to the synthesis method of nitrogen-doped barb-shaped carbon nanosphere / sulfur composite material in step 2 and step 3, obtain nitrogen-doped barb carbon nanosphere / sulfur composite (370nm-CNS / S-1:7). According to the method in step 4, prepare the electrodes and assemble the battery, and perform routine performance tests. The initial discharge specific capacity under 1C current is 665mAh g -1 , the capacity remains at 211mAh g after 600 cycles -1 .

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Abstract

The invention discloses a nitrogen-doped barbed carbon nanosphere / sulfur composite material and a preparation method and application thereof. The composite material comprises sulfur and nitrogen-dopedbarbed carbon nanospheres serving as a sulfur host material, wherein the carbon nanosphere is formed by combining a plurality of nitrogen-doped needle-like carbon fibers according to a spherical shape, the lengths of the carbon fibers are different, all the carbon fibers are shot from the spherical edge to the spherical center to form barbed distribution, gaps exist between the carbon fibers, andthe carbon fibers are gathered to the center to form a cavity. Furthermore, 60-75wt% of sulfur supported by the nitrogen-doped barbed carbon nanospheres is applied to a lithium-sulfur battery as a positive electrode. Sufficient space is provided for sulfur volume expansion in the charging and discharging process by utilizing the internal cavity and the carbon fiber gaps; the carbon fibers with different lengths in the spheres can well disperse sulfur and adsorb polysulfide, so that the sulfur utilization rate is increased, and the polysulfide loss is inhibited; and the loss of polysulfide ions can be more effectively inhibited by doping carbon in the outer layer of nitrogen atoms, thereby effectively prolonging the cycle life of the lithium-sulfur battery and improving the capacity of thelithium-sulfur battery.

Description

technical field [0001] The invention belongs to the field of nanometer materials and electrochemical energy, and specifically refers to a nitrogen-doped barbed carbon nanosphere / sulfur composite material and its preparation method and application. Background technique [0002] Lithium-sulfur secondary batteries have shown great application advantages in future electrochemical energy storage devices. However, the insulation of the sulfur cathode, the Li generated during charging and discharging 2 S n The capacity is still lower than the theoretical value due to the easy dissolution, loss and volume expansion of sulfur in the electrolyte, and the poor rate performance and cycle stability limit the development and wide application of lithium-sulfur batteries. A lot of valuable research work has been done to improve the above-mentioned difficult problems. [0003] Among them, carbon-sulfur composites based on nanostructures have been considered as one of the effective methods ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/38H01M4/62H01M4/139H01M10/052H01M10/058C01B32/05C01B17/00B82Y30/00
CPCH01M4/38H01M4/625H01M4/628H01M4/139H01M10/052H01M10/058C01B32/05C01B17/00B82Y30/00Y02E60/10Y02P70/50
Inventor 陈锡安余志升柳孟兰
Owner WENZHOU UNIVERSITY
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