Lithium-sulfur battery cathode material and preparation method thereof

Abstract

The invention relates to a lithium-sulfur battery positive electrode material and a preparation method thereof, in particular to a fiber carbon-based lithium-sulfur battery cathode material doped withFe3C nanoparticles and having a hollow vesicle structure. The preparation method comprises the following steps: firstly, preparing ferric oxide nanoparticles with regular shapes; uniformly and properly coating the particles into silk threads by using an electrostatic spinning method, pre-oxidizing and carbonizing the silk threads to finish the preparation, pulverizing the Fe2O3 particles with theparticle size of 140-750nm into fine Fe3C nanoparticles with the particle size of 5-10nm in the carbonizing process, and leaving hollow vesicles. According to the materials designed in the invention,the chemical adsorption effect of Fe3C is combined with the physical limitation of the hollow vesicles of the carbon fibers, polysulfide is adsorbed and fixed, a confinement space is provided, a goodion and electron transmission path is guaranteed, charge and discharge volume expansion is relieved, meanwhile, the conductivity of the material is improved through doped N atoms, and the overall electrochemical performance of the Li-S battery is improved.

Description

technical field [0001] The invention belongs to the technical field of battery energy storage materials, and in particular relates to a lithium-sulfur battery cathode material and a preparation method thereof. Background technique [0002] Problems such as global warming and the reduction of traditional energy have caused scientists to pay attention to the efficiency of traditional energy and the development and utilization of new energy. Researchers are not only interested in clean and renewable energy sources, but also in advanced energy storage. Therefore, the development of high-performance electrochemical energy storage devices has become one of the important topics of energy strategy projects established by governments around the world. With social progress and economic development, as well as people's demand for green energy and awareness of ecological environment protection, secondary batteries represented by lithium-ion batteries have been widely used as a convenie...

AI Technical Summary

Problems solved by technology

At present, the theoretical energy density of lithium-ion batteries cannot meet people's needs. There are several factors hindering its development, such as: (1) Elemental sulfur and its products are insulating materials, which in turn affect the conductivity of lithium-sulfur batteries

(2) During the charge-discharge cycle of lithium-sulfur batteries, due to the different densities of elemental sulfur and its product lithium sulfide, serious volume expansion will be caused, which will affect the normal operation of the electrodes, thereby affecting the cycle life of lithium-sulfur batteries.

(3) Since the chemical reaction between metal lithium and elemental sulfur is a multi-step reaction during the discharge process, lithium polysulfide intermediates will be produced during the reaction process, and soluble lithium polysulfide can be dissolved in the organic electrolyte. Under the action, lithium polysulfide leaves the positive electrode, resulting in low utilization of active materials, and when lithium polysulfide moves through the separator to the negative electrode, part of it will react with metal lithium to form lithium sulfide, resulting in self-discharge phenomenon

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