A graphene-like mos 2 /Nitrogen, phosphorus co-doped graphene electrochemical lithium storage composite electrode preparation method

Abstract

The invention discloses a preparation method of a graphene-like MoS2 / nitrogen and phosphorus co-doped graphene electrochemical lithium storage composite electrode. The method comprises the following steps of: S1, dispersing graphene oxide in water, adding quaternary phosphonium salt to carry out uniform mixing, then sequentially adding ammonium thiomolybdate and hydrazine and carrying out uniform mixing; S2, performing a hydrothermal reaction on a mixed disperse system obtained in S1, carrying out cooling, centrifugally collecting a solid product, washing and drying the solid product, and then carrying out heat treatment in the argon or nitrogen atmosphere to prepare and obtain a graphene-like MoS2 / nitrogen and phosphorus co-doped graphene composite nano material; S3, using the composite nano material obtained in S2 as an electrochemical lithium storage active substance to prepare the composite electrode. According to the preparation method, the graphene oxide, the ammonium thiomolybdate and the hydrazine are used as raw materials and by methods of quaternary phosphonium salt assisted hydrothermal, heat treatment and the like, the graphene-like MoS2 / nitrogen and phosphorus co-doped graphene electrochemical lithium storage composite electrode is successfully prepared. The method disclosed by the invention has the advantages of simplicity, convenience and easiness in enlarging industrial application.

Description

technical field [0001] The invention belongs to the technical field of new energy materials and energy storage and conversion, and in particular relates to a graphene-like MoS 2 A method for preparing a composite electrode for electrochemical lithium storage by co-doped graphene / nitrogen and phosphorus. Background technique [0002] Lithium-ion batteries have excellent properties such as high specific energy, no memory effect, and environmental friendliness, and have been widely used in portable mobile appliances such as mobile phones and notebook computers. As power batteries, lithium-ion batteries also have broad application prospects in electric bicycles, electric vehicles, and smart grids. At present, the anode materials of lithium-ion batteries are mainly graphite materials. These graphite materials have good cycle stability, but their capacity is low. The theoretical capacity of graphite is 372 mAh / g. The new generation of lithium-ion batteries puts forward higher re...

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Problems solved by technology

For the liquid-phase synthesis method, the water solubility of inorganic phosphate is very good, but because the phosphate or hydrogen phosphate itself is negatively charged, it is difficult to adsorb on the graphene oxide with the same load; and the phosphorus in the phosphate - The bond energy of the oxygen bond is relatively large, and it needs to be broken at high temperature, so the doping degree of phosphorus in the phosphorus-doped graphene prepared by using phosphate or hydrogen phosphate as the phosphorus source is not high

Although organic phosphine such as butyl phosphate and triphenylphosphine are not strong in phosphorus-carbon bonds and are easy to break, because organic phosphorus has poor solubility in water and does not have a positive charge, it cannot be combined with negatively charged ones in aqueous solution. Graphene oxide and molybdate or thiomolybdate produce strong electrostatic interaction, resulting in poor composite material or uneven doping

If the reaction is carried out in an organic solvent, and the solubility of molybdate or thiomolybdate in organic solvent is relatively poor, it will not only be difficult to react, but also produce more organic waste and pollute the environment

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