Lithium-sulfur battery flexible electrode material and preparation method and application thereof

Abstract

The invention relates to a lithium-sulfur battery flexible electrode material and preparation method and application thereof. The lithium-sulfur battery flexible electrode material comprises a VOx nanometer hollow sphere wound with a single-walled carbon nanotube, wherein elemental sulfur is coated in the VOx nanometer hollow sphere, and x is equal to 1.5 to 2.5. By means of an absorption effect of VOx on lithium polysulfide and a wrapping effect of a hollow sphere structure on the polysulfide, the VOx nanometer hollow sphere is combined with the single-walled carbon nanotube, the binding capability of the lithium-sulfur battery flexible electrode material on the elemental sulfur and the polysulfide is synergically improved, and the lithium-sulfur battery flexible electrode material has excellent cycle stability and high battery capacity during the charge-discharge process. The initial discharging capacity of a VOx flexible film with a diameter about 200 nanometer under 1C rate currentcan reach 1,069mAh / g or above and still can reach 614mAh / g or above under 20C rate current; the lithium-sulfur battery flexible electrode material is excellent in cycle efficiency, and the capacity still can be maintained at 69% or above after charging and discharging for 300 circles; and after the lithium-sulfur battery flexible electrode material is used as a lithium-sulfur battery positive electrode assembled to form a flexible soft package battery, the voltage stability is high under different bending angles, the cycle property is excellent under different bending angles, and the capacityreduction rate is average less than 0.32% after 20-100 circles.

Description

technical field

[0001] The invention relates to the technical field of lithium-sulfur batteries, in particular to a flexible electrode material for lithium-sulfur batteries and its preparation method and application. Background technique

[0002] With the continuous development of flexible devices and wearable electronic products, independently supported hybrid cathode materials have become one of the development trends of flexible lithium-sulfur batteries, and are also a hot spot in current research.

[0003] At present, single-walled carbon nanotubes are also widely used as current collectors for flexible batteries. However, lithium polysulfides are generated during charging and discharging of lithium-sulfur batteries, and the generated lithium polysulfides can often be dissolved in organic electrolytes. The active material is lost. Therefore, the current research focuses on finding a material that can be used as a carrier to wrap the sulfur element well so that it can bin...

Examples

Embodiment 1

[0062] A flexible electrode material for lithium-sulfur batteries, including single-walled carbon nanotube-wound VO x nano hollow spheres, the VO x The nano hollow sphere is coated with sulfur element.

[0063] Its preparation method is as follows:

[0064] (1) Dissolve 0.05g of vanadyl acetylacetonate into 20mL of N-N dimethylformamide solution, stir at room temperature for 2h, transfer the solution to a polytetrafluoroethylene reactor, then transfer the reactor to a drying oven to raise the temperature To 200 ℃, keep 21h, then naturally cool to room temperature. Take out the suspension in the reaction kettle, centrifuge at 8000r / min for 5min, collect the precipitate, wash with absolute ethanol for 3 times, then dry at 50°C for 10h, and collect VO with a particle size of about 200nm x Hollow balls, such as figure 1 , figure 2 shown.

[0065] (2) will VO x Mix hollow spheres with sulfur powder at a mass ratio of 1:2, put them into a sealed glass container with a cover ...

Embodiment 2

[0068] The only difference from Example 1 is that the mass of vanadyl acetylacetonate is 0.1 g.

[0069] As a result, step (1) collects VO with a particle size of about 400nm x Hollow balls, such as Figure 4 , Figure 5 shown;

[0070] Step (2) to get VO x Solid spheres complexed with sulfur, such as Image 6 As shown, through elemental analysis, it is found that the core of the obtained solid sphere is sulfur element, and the shell is VO x . The resulting flexible film product is denoted VHS-400@S / SWCNT.

Embodiment 3

[0072] The only difference from Example 1 is that the mass of vanadyl acetylacetonate is 0.3g.

[0073] As a result, step (1) collects VO with a particle size of about 900nm x Hollow balls, such as Figure 7 , Figure 8 shown;

[0074] Step (2) to get VO x Solid spheres complexed with sulfur, such as Figure 9 As shown, through elemental analysis, it is found that the core of the obtained solid sphere is sulfur element, and the shell is VO x . The resulting flexible film product is denoted VHS-900@S / SWCNT.

technical field

[0001] The invention relates to the technical field of lithium-sulfur batteries, in particular to a flexible electrode material for lithium-sulfur batteries and its preparation method and application. Background technique

[0002] With the continuous development of flexible devices and wearable electronic products, independently supported hybrid cathode materials have become one of the development trends of flexible lithium-sulfur batteries, and are also a hot spot in current research.

[0003] At present, single-walled carbon nanotubes are also widely used as current collectors for flexible batteries. However, lithium polysulfides are generated during charging and discharging of lithium-sulfur batteries, and the generated lithium polysulfides can often be dissolved in organic electrolytes. The active material is lost. Therefore, the current research focuses on finding a material that can be used as a carrier to wrap the sulfur element well so that it can bin...

Examples

Embodiment 1

[0062] A flexible electrode material for lithium-sulfur batteries, including single-walled carbon nanotube-wound VO x nano hollow spheres, the VO x The nano hollow sphere is coated with sulfur element.

[0063] Its preparation method is as follows:

[0064] (1) Dissolve 0.05g of vanadyl acetylacetonate into 20mL of N-N dimethylformamide solution, stir at room temperature for 2h, transfer the solution to a polytetrafluoroethylene reactor, then transfer the reactor to a drying oven to raise the temperature To 200 ℃, keep 21h, then naturally cool to room temperature. Take out the suspension in the reaction kettle, centrifuge at 8000r / min for 5min, collect the precipitate, wash with absolute ethanol for 3 times, then dry at 50°C for 10h, and collect VO with a particle size of about 200nm x Hollow balls, such as figure 1 , figure 2 shown.

[0065] (2) will VO x Mix hollow spheres with sulfur powder at a mass ratio of 1:2, put them into a sealed glass container with a cover ...

Embodiment 2

[0068] The only difference from Example 1 is that the mass of vanadyl acetylacetonate is 0.1 g.

[0069] As a result, step (1) collects VO with a particle size of about 400nm x Hollow balls, such as Figure 4 , Figure 5 shown;

[0070] Step (2) to get VO x Solid spheres complexed with sulfur, such as Image 6 As shown, through elemental analysis, it is found that the core of the obtained solid sphere is sulfur element, and the shell is VO x . The resulting flexible film product is denoted VHS-400@S / SWCNT.

Embodiment 3

[0072] The only difference from Example 1 is that the mass of vanadyl acetylacetonate is 0.3g.

[0073] As a result, step (1) collects VO with a particle size of about 900nm x Hollow balls, such as Figure 7 , Figure 8 shown;

[0074] Step (2) to get VO x Solid spheres complexed with sulfur, such as Figure 9 As shown, through elemental analysis, it is found that the core of the obtained solid sphere is sulfur element, and the shell is VO x . The resulting flexible film product is denoted VHS-900@S / SWCNT.

Images