40 results about "Kirkendall effect" patented technology

The invention discloses a hollow spherical NiMn2O4 lithium ion battery cathode material and a preparation method thereof, and belongs to the field of lithium ion battery electrode material technology. Particle size of the hollow spherical material is 1 to 3 micrometers; the spherical shell is made of NiMn2O4 nanometer crystals, and has a porous structure. The porous spherical shell is in favor of penetration of electrolyte, is capable of shortening diffusion distance of lithium ions, and possesses excellent electrochemistry cycling stability and rate capability. The preparation method is based on ''Kirkendall effect'', and the hollow spherical NiMn2O4 can be obtained directly by performing high temperature solid phase reaction. The preparation method comprises following steps: taking solid spherical MnCO3 as a precursor; roasting at a low temperature to obtain porous solid spherical manganese dioxide; and then roasting the porous solid spherical manganese dioxide with a nickel salt to obtain the hollow spherical spinel-type NiMn2O4 cathode material. The preparation method is simple in technologies, do not need a template, and is suitable for large-scaled production.

The invention discloses a method for preparing a hollow / mesoporous nano structure material by adjusting the Kirkendall effect through a magnetic field. In the process that a hollow / mesoporous nano structure material is prepared through the Kirkendall effect, a hydrothermal reaction step is implemented under an external magnetic field condition. Due to an external magnetic field, the time that a solid nano structure material is transformed into the hollow / mesoporous nano structure material is greatly shortened at a relatively low temperature by virtue of the Kirkendall effect, so that great benefit values are made since the reaction preparation cost is reduced, and current development themes of energy conservation and environment protection are met.

The invention provides a silicon-germanium solid solution and a preparation method and application thereof. According to the silicon-germanium solid solution and the preparation method and application thereof, a composite material containing a silicon precursor and a germanium precursor serves as a cathode, an inert electrode serves as an anode, and a melt containing CaCl2 serves as an electrolyte, so that silicon-germanium solid solution powder is obtained through electrolysis; or, a conductive substrate serves as a cathode, an inert electrode serves as an anode, and a melt containing a silicon precursor, a germanium precursor and CaCl2 serves as an electrolyte, so that a thin film or an array electrode material of the silicon-germanium solid solution on the conductive substrate is obtained through electrolysis. According to the single-step controllable template-free preparation method provided by the invention, the Kirkendall effect is utilized, in the electrolytic process, the diffusion rate of germanium is larger than that of silicon, and a vacancy is formed on one side of the germanium, so that a silicon-germanium solid solution nano hollow structure is obtained; volume change in the charging and discharging processes is effectively relieved, and the cycle performance and rate performance of a battery are significantly improved; and a template is not needed, operation is convenient, and the silicon-germanium solid solution is suitable for large-scale industrial production.

The invention discloses a method for connecting porous inner cores with compact casings, which comprises the following steps: -80-+500 meshes of metal powder A and B are selected and blended in atom ratio 1:1, then are put into a mixer to mix evenly; the mixed powder A, B is directly packaged into a compact tube made of metal A, after 2.5 to 5.0 MPa mould pressing and forming, the mixed powder A, B is sintered in vacuum at 350 to 1200 DEG C for 1 to 2 hours; wherein, the diffusion velocity of metal B in the metal A is quicker than the diffusion velocity of the metal A in the metal B, the porous material is AB alloy, the compact material is metal A. By adopting the powder metallurgy method, the invention takes use of the Kirkendall effect and the sintering grow phenomenon when some alloys is sintered to achieve sintering and diffusion welding of porous material and compact material, so that the porous material and the compact material are connected into an integral part without any air leakage and good air tightness. The invention can realize the integrated molding of the porous material and the compact material, and the process is simple and the production cost is greatly reduced.

The invention belongs to the field of composite materials, and discloses a manganese oxide-FeSiMnTi intermetallic compound-based composite porous electrode material and a preparation method thereof. The manganese oxide-FeSiMnTi intermetallic compound-based composite porous electrode material comprises 5%-15% of MnOx, 40%-50% of Fe, 15%-35% of Si, 5%-15% of Mn and 5%-15% of Ti, wherein x is equal to 1,3 / 4 or 2. According to the manganese oxide-FeSiMnTi intermetallic compound-based composite porous electrode material and the preparation method thereof, a mode of mixing oxide powder and element powder is adopted, a substrate is synthesized and prepared by using reaction between the element powder, and an oxide / intermetallic compound-based composite material is prepared by combining an initially added oxide component; and the mixing mode forms a large number of pores by fully utilizing a Kirkendall effect caused by partial diffusion of a rapid diffusion component in a substrate material component under a high-temperature condition through design of the substrate material component and design of a sintering process, and finally the oxide / intermetallic compound-based composite porous material is prepared. The controllability of a pore structure is relatively good, a pore forming agent does not need to be added, and the manganese oxide-FeSiMnTi intermetallic compound-based composite porous electrode material has the characteristic of short process.