Preparation method of S/TiO2 composite material for anode of sodium-sulfur battery

Abstract

The invention provides a preparation method of an S/TiO2 composite material for an anode of a sodium-sulfur battery. The preparation method comprises the following steps: dissolving butyl titanate, a template agent and a hydrolysis inhibitor into absolute ethyl alcohol; adding a mixed solution of de-ionized water and the absolute ethyl alcohol to form semi-transparent sol; transferring the sol into a high-pressure reaction kettle to react; calcining a solid product in air to remove the template agent to obtain meso-porous titanium dioxide; dispersing the meso-porous titanium dioxide into a sodium thiosulfate solution dissolved with a surfactant; adding hydrochloric acid to react; washing the solid product by a lot of the de-ionized water and drying; and eating under the protection of an inert atmosphere to obtain the S/TiO2 composite material. The meso-porous titanium dioxide prepared by the preparation method is large in specific surface area, high in porosity and strong in adsorption capability; the electrical conductivity of sulfur can be improved and a lot of nano sulfur and polysulfide can be contained; the polysulfide can be effectively prevented from being dissolved and diffused in electrolyte, and the utilization rate of the sulfur is improved; meanwhile, the structure of the meso-porous titanium dioxide is stable and a pore channel cannot be easily damaged, so as to have buffering effects on volume expansion and retraction in a charging/discharging process of a sulfur electrode.

Description

technical field [0001] The invention belongs to the field of new energy, and relates to a kind of S / TiO for positive electrode of lithium-sulfur battery 2 Methods of preparation of composite materials. Background technique [0002] With the advancement of electronic technology, portable electrical appliances are gradually developing in the direction of light, thin, and small. The commercialization of electric vehicles requires a safe and long-lasting power source. The demand for long-life secondary batteries is increasingly urgent. Compared with secondary batteries such as lead-acid batteries, nickel-cadmium batteries and nickel-hydrogen batteries, lithium-ion batteries have the advantages of high working voltage, high energy density, long cycle life, small self-discharge rate, low pollution and no memory effect. After being transformed, it has developed rapidly. In recent years, major breakthroughs have been made in the research and development of negative electrode mate...

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Problems solved by technology

[0004] However, elemental sulfur has the following problems as a positive electrode: (1) elemental sulfur is an electronic and ion insulator at room temperature; (2) elemental sulfur will be reduced to long-chain polysulfides soluble in the electrolyte during discharge. On the one hand, it causes the loss of active substances, on the other hand, the dissolution of long-chain polysulfides in the electrolyte will increase the viscosity of the electrolyte and deteriorate its ionic conductivity; (3) The long-chain polysulfides dissolved in the electrolyte will diffuse to the metal lithium negative electrode , a self-discharge reaction occurs, which is reduced to short-chain polysulfides and diffuses back to the positive electrode, resulting in severe corrosion of the lithium negative electrode and low Coulombic efficiency. This process is called the shuttle effect; (4) sulfur electrodes will occur during charging and discharging. The shrinkage and expansion of the volume destroys the physical structure of the electrode to a certain extent

The porous materials that researchers pay more attention to are generally carbon materials, but traditional carbon materials have small specific surface area, poor pore structure consistency, and uneven pore size distribution, resulting in small sulfur loading and uneven sulfur distribution in the prepared composite materials; and The active substances in the pore structure will dissolve into the electrolyte to form polysulfides, so the inhibition of the shuttle effect is very limited

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