4results about How to "Increase intrinsic conductivity" patented technology

This invention discloses a wide-interlayer-spacing molybdenum disulfide catalyst, its preparation method, and its application, belonging to the field of water electrolysis for hydrogen production energy conversion technology. The preparation method includes the following steps: preparing a molybdenum disulfide precursor solution using a molybdenum source and a sulfur source; then subjecting the molybdenum disulfide precursor solution to a hydrothermal reaction with a carbon-containing interlayer-spacing regulator; and obtaining the wide-interlayer-spacing molybdenum disulfide catalyst after centrifugation and washing. The carbon-containing interlayer-spacing regulator is used to insert into the interlayer of molybdenum disulfide during the hydrothermal reaction, increasing the interlayer spacing of the (002) crystal planes of the obtained molybdenum disulfide catalyst. The wide-interlayer-spacing molybdenum disulfide catalyst of this invention facilitates electrolyte penetration and hydrogen bubble release, effectively avoids active site blockage, enhances the intrinsic conductivity of the catalyst, accelerates internal charge transport, increases active sites for hydrogen evolution reaction, and improves the intrinsic hydrogen evolution catalytic activity of the catalyst.

The application belongs to the technical field of sodium-ion battery cathode materials, and discloses a pyrophosphoric acid sodium iron phosphate composite material and a preparation method and application thereof. By regulating the microenvironment of chelation reaction, the chelation state of iron ions is optimized, iron ion precipitation is avoided, and the formation of electrochemically inert impurities is inhibited. Meanwhile, graphene oxide constructs a three-dimensional conductive network to improve the electronic transmission capacity of the material. The pyrophosphoric acid sodium iron phosphate composite material prepared by the application has small particle size, uniform dispersion, no inert impurities and is tightly coated by the conductive network. The material has a discharge specific capacity of 120.9 mAh·g ‑1 at 0.5 C, still maintains a reversible capacity of 78.1 mAh·g ‑1 at 20 C high rate, and has a capacity retention rate of 84.9% after 1000 cycles, and the full battery assembled with the hard carbon negative electrode also exhibits excellent rate and cycle performance.

The application provides a preparation method of a lithium iron phosphate positive electrode material modified by phosphoric acid pretreatment and ion doping. Lithium source, iron source, phosphorus source, carbon source, titanium source and vanadium source are mixed with water as a solvent and then sand milling is performed; the slurry is taken out after sand milling; the slurry is subjected to spray drying to obtain yellow material; the yellow material is subjected to primary calcination under an inert atmosphere to obtain a lithium iron phosphate precursor; the lithium iron phosphate precursor is aged in a phosphoric acid solution and then subjected to suction filtration and drying to obtain black powder; and the black powder is subjected to secondary calcination under an inert atmosphere to obtain the lithium iron phosphate positive electrode material. By dispersing the lithium iron phosphate precursor in a phosphoric acid solution with a certain concentration, defects are generated on the surface of the precursor after acidification, which is beneficial to the growth of particles after secondary calcination, improves the compaction density, and the residual phosphate groups are attached to the surface of the precursor and penetrate into the surface layer, which can promote the diffusion of lithium ions between particles and the transmission of lithium ions and electrons between particles.

This invention discloses a bifunctional three-dimensional porous composite material and its preparation method and application. The method includes the following steps: (1) adding a carbon source to deionized water and stirring to obtain a uniformly dispersed solution; (2) dissolving a rare earth metal source, a transition metal source, and a sulfur source in deionized water and stirring to obtain a precursor solution; (3) mixing the solution obtained in step (1) and the precursor solution to obtain a mixed solution and performing a hydrothermal reaction; (4) repeatedly washing the product obtained in step (3), drying it, and then performing heat treatment to prepare the bifunctional three-dimensional porous composite material. The bifunctional three-dimensional porous composite material can effectively buffer the volume expansion effect of the sulfur cathode during charging and discharging and promote the full wetting of the electrolyte. On the other hand, it also improves the conductivity and catalytic activity of the composite material through the doping of rare earth elements, effectively improving the electrochemical performance of lithium-sulfur batteries.