Lithium sulfur battery based on modification of graphene oxide thin film

A graphene film, lithium-sulfur battery technology, applied in lithium batteries, battery electrodes, battery pack components, etc., can solve problems such as capacity decline, low energy efficiency, and loss of active material sulfur

Inactive Publication Date: 2015-11-11
CHANGZHOU UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0002] Compared with the mainstream lithium-ion batteries on the market, lithium-sulfur batteries have 2 to 5 times the theoretical energy density of the former, so research on lithium-sulfur batteries continues to deepen. However, lithium-sulfur batteries still suffer from severe capacity decline and low energy efficiency. problem, the main reason is the loss of active substance sulfur; on the one hand, in the charging and discharging process, there is an inevitable "oxidative shuttle effect", that is, the polysulfides generated at the sulfur electrode will diffuse into the electrolyte, resulting in a capacity loss. drop; when polysulfides diffuse to the lithium anode, they react with lithium metal to form Li 2 S x , meanwhile, the partial reduction product Li

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  • Lithium sulfur battery based on modification of graphene oxide thin film
  • Lithium sulfur battery based on modification of graphene oxide thin film
  • Lithium sulfur battery based on modification of graphene oxide thin film

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Embodiment 1 is used for the preparation of the modified sulfur electrode

[0028] The carbon-sulfur composite, binder, and conductive agent were mixed according to a certain ratio and ball-milled for 30 minutes to prepare a sulfur electrode for modification.

[0029] Among them, the binder is polyvinylidene fluoride, and the ratio in the modified sulfur electrode is 5%; the conductive agent is oxidized carbon black, and the ratio in the modified sulfur electrode is 10%.

[0030] The morphology of the modified electrode sheet prepared by the above method was characterized, and the SEM image is as follows figure 1 As shown, (a) is the surface topography, (b) is the topography of the cross section; according to the topography (a), it can be seen that the active material is evenly distributed on the current collector aluminum foil, according to the topography (b) It can be seen that the cross-section of the active material is a porous fluffy structure.

Embodiment 2

[0031] Preparation of the sulfur electrode modified by embodiment 2 graphene oxide film

[0032] The carbon-sulfur compound, binder, and conductive agent were mixed according to a certain ratio and ball-milled for 30 minutes to prepare a modified sulfur electrode; wherein, the binder was polyvinylidene fluoride, and the ratio in the modified sulfur electrode was 5%; the conductive agent is oxidized carbon black, and the proportion in the modified sulfur electrode is 10%.

[0033] Graphene oxide was prepared and dissolved in ethanol at a concentration of 1 mg / mL.

[0034] Evenly drop 10mL of the prepared graphene oxide ethanol solution on the surface of a 10cm2 sulfur electrode for modification, and dry it at 50°C to 120°C.

[0035] Morphological characterization of the graphene oxide film-modified sulfur electrode sheet prepared by the above method, the SEM image is as follows figure 2 As shown, (a) is the topography of the surface, and (b) is the topography of the cross ...

Embodiment 3

[0037] Example 3 Lithium-sulfur battery performance test

[0038] The graphene oxide-modified sulfur electrode prepared in Example 2 and the modified sulfur electrode prepared in Example 1 were assembled into a button battery for charge and discharge tests.

[0039] The test curve of the button battery is as follows image 3 , as shown in 4.

[0040] according to image 3 It can be seen from the cycle number-specific capacity diagram under the test current of 0.5A / g that the initial specific capacity of the unmodified sulfur electrode is about 1050mAh / g, which is slightly higher than the initial specific capacity of the sulfur electrode modified by graphene oxide film 1010mAh / g. g, this may be related to the diffusion rate of lithium ions in the initial state, but it can be seen from the subsequent charge and discharge that the specific capacity of the unmodified sulfur electrode drops sharply. After 100 cycles, the specific capacity is only about 500mAh / g, and the capacit...

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Abstract

The invention discloses a lithium sulfur battery. The lithium sulfur battery comprises a sulfur electrode, a metallic lithium electrode and a diaphragm and an electrolyte which are arranged between the sulfur electrode and the metallic lithium electrode. The lithium sulfur battery is characterized in that the sulfur electrode is modified by a graphene oxide thin film, and the sulfur electrode is prepared according to the following steps of: grinding and mixing a carbon sulfur compound, a conductive agent and an adhesive according to proportions, dissolving the obtained materials in N-methyl pyrrolidone to prepare paste, applying the paste onto a current collector, and drying the current collector to prepare the sulfur electrode for modification; preparing graphene oxide, and dissolving the graphene oxide in ethanol, wherein the concentration is 0.5-5 mg/mL; and uniformly adding the ethanol solution of the graphene oxide onto the surface of the modified sulfur electrode dropwise, and drying the surface of the modified sulfur electrode. By the graphene oxide thin film prepared according to the invention, polysulfide ions can be effectively bound and are greatly prevented from diffusing to the outside of the sulfur electrode, meanwhile, lithium ion transmission cannot be blocked, thus, oxidation shuttle effect in the lithium sulfur battery is suppressed, and the problem that the capacity is reduced dramatically due to the loss of active substance sulfur is solved.

Description

technical field [0001] The invention relates to a lithium-sulfur battery, in particular to a lithium-sulfur battery with a sulfur electrode modified by a graphene oxide film and a preparation method thereof. Background technique [0002] Compared with the mainstream lithium-ion batteries on the market, lithium-sulfur batteries have 2 to 5 times the theoretical energy density of the former, so research on lithium-sulfur batteries continues to deepen. However, lithium-sulfur batteries still suffer from severe capacity decline and low energy efficiency. problem, the main reason is the loss of active substance sulfur; on the one hand, in the charging and discharging process, there is an inevitable "oxidative shuttle effect", that is, the polysulfides generated at the sulfur electrode will diffuse into the electrolyte, resulting in a capacity loss. drop; when polysulfides diffuse to the lithium anode, they react with lithium metal to form Li 2 S x , meanwhile, the partial reduc...

Claims

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Application Information

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IPC IPC(8): H01M10/052H01M2/16H01M4/139
CPCH01M4/139H01M10/052H01M50/431H01M50/46Y02E60/10
Inventor 刘振丁建宁袁宁一仲玉娇郑祥
Owner CHANGZHOU UNIV
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