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531results about How to "Improve Capacitive Performance" patented technology

Lithium-sulfur battery cathode material and preparation method thereof

The invention discloses a lithium-sulfur battery cathode material and a preparation method thereof. The cathode material is formed by in-situ compositing of a mesoporous metal-organic framework and elemental sulfur. The mesoporous metal-organic frame is of a laminated pore structure consisting of a macro pore, a meso pore and a micro pore, wherein the pores are communicated with one another. The structure can adsorb more elemental sulfur and can simultaneously inhibit the dissolution of sulfur elementary substance and multi-sulfur compounds in electrolyte, so that the cycle performance of a lithium-sulfur battery is improved and high utilization rate of an active substance of the cathode material is kept. A sulfur and metal-organic framework material composite cathode material is prepared by a two-step process of low-temperature liquid phase composition and sulfur extraction, a composite material precursor with homogeneously dispersed high load sulfur content can be obtained through in-situ compositing at a low temperature with a liquid-phase preparation method, redundant sulfur on the surface of the precursor and in pore passages is extracted by an organic solvent, the aperture of the composite material can be further effectively adjusted and controlled, selective distribution of sulfur is realized, and the composite material with excellent electrochemical performance is obtained. By adopting the preparation method, the distribution of the sulfur in the composite material can be effectively improved, and the electrochemical performance of the composite material is optimized. Meanwhile, the preparation method is simple and is easy to perform industrially, and mass production is facilitated.
Owner:CENT SOUTH UNIV +1

Transmitting antenna selection method for generalized spatial modulation system under correlated channel

The invention discloses a transmitting antenna selection method for a generalized spatial modulation system under a correlated channel. The method comprises the following steps that 1) a receiving terminal performs ideal channel estimation to obtain an NR*MT MIMO (multiple-input and multiple-output) channel matrix H of the generalized spatial modulation system; 2) the receiving terminal calculates an L2 norm measure matrix Fh and a distance measure matrix D, which are used for the antenna selection method, according to the MIMO channel matrix H obtained in the step 1); 3) the receiving terminal selects an effective transmitting antenna set Phi according to the L2 norm measure matrix Fh and the distance measure matrix D, and informs a transmitting terminal of a selection result through a feedback channel; 4) the transmitting terminal performs generalized spatial modulation and transmission according to the effective transmitting antenna set Phi selected in the step 3). According to the method, characteristics of a spatial constellation set are changed by transmitting antenna selection in the generalized spatial modulation system, so that the problem that the bit error rate and capacity performance of the system are greatly reduced due to the fact of spatial constellation distinction difficulty caused by the correlation of transmitting antennae in an actual generalized spatial modulation system is solved.
Owner:XI AN JIAOTONG UNIV

Method for preparing graphene/ nanocarbon particle composite

The invention provides a method for preparing a graphene / nanocarbon particle composite. The method comprises the steps that (1) graphite is oxidized to prepare oxidized graphene, and the acquired oxidized graphene is added to water to prepare suspension liquid; (2) nanocarbon particles are added to water solution with a surface active agent to acquire suspension liquid of the nanocarbon particles; (3) the suspension liquid of the oxidized graphene is mixed with the suspension liquid of the nanocarbon particles, and then mixed suspension liquid is acquired; (4) the uniformly mixed suspension liquid is spray-dried to acquire powder; (5) reduction treatment is conducted on the powder acquired in the step (4), or the powder acquired in the step (4) is placed in an inert gas atmosphere, thermal pretreatment is conducted on the powder acquired in the step (4), then reduction reaction is conducted in a reducing atmosphere, and eventually the graphene composite loading the nanocarbon particles is prepared. The invention further relates to the graphene / nanocarbon particle composite acquired by the method and application of the graphene / nanocarbon particle composite being used as materials of supercapacitors, catalyst carriers and infrared optical materials.
Owner:济南高新财金投资有限公司

A channel estimate method and corresponding communication method and system

The invention provides the channel estimating method used for pilot frequency supplementary estimating system, the corresponding emitting method, the corresponding receiving method and the improved communication system structure. The invention sets the upper limit of information symbol transmitting speed of each group at the emitting end as the lower bound of mutual information between the input operation and the output operation, which the system can reach when the receiving end implements the relative detection for the information symbol of each group. Primarily, the receiving end utilizes the known pilot frequency symbol to implement channel estimation. The channel parameter which is obtained is implemented with initial estimation value. The initial estimation value is utilized to implement the relative detection for information symbol of the first group, and then the information symbol of the group, which is judged, is taken as equivalent pilot frequency symbol and estimates the channel again together with the known pilot frequency. The new channel parameter estimation value is utilized to implement the relative detection for the information symbol of the next group, which is received. The iteration is implemented and the channel is estimated. With the increase of equivalent pilot frequency energy, the estimation difference of the channel is reduced; therefore, the capacity performance of the system is improved.
Owner:PEKING UNIV

Nickel sulfide nanoparticle/nitrogen-doped fiber-based carbon aerogel composite material and preparation method therefor

The invention belongs to the technical field of nanomaterial, and specifically discloses a nickel sulfide nanoparticle/nitrogen-doped fiber-based carbon aerogel composite material and a preparation method therefor. The composite material is prepared by the steps of adopting nickel salt and a sulfur source, and performing in-situ growth of the nickel sulfide nanoparticles on the nitrogen-doped cellulose-based carbon aerogel; the raw materials comprise a biomass material rich in fibers, nickel salt, thiocarbamide, dopamine and aniline monomer; the preparation process comprises the steps of preparing a poly-dopamine-coated fiber-based biomass material or a polyaniline-coated cellulose-based biomass material through a one-step polymerization method; preparing the nitrogen-doped cellulose-based carbon aerogel through a high temperature carbonization method; and performing in-situ growth of the nickel sulfide nanoparticles on the surface of the nitrogen-doped fiber-based carbon aerogel by adopting a one-step solvothermal method. The composite material prepared by the invention has the uniform distribution characteristic of the nickel sulfide nanoparticles on the nitrogen-doped fiber-based carbon aerogel, so that the composite material can be used as the ideal supercapacitor electrode material.
Owner:FUDAN UNIV

Carbon compound cathode material for ultracapacitor battery

InactiveCN101740230AGood lithium ion intercalation/extraction cycle performanceExcellent Capacitive Energy Storage PerformanceElectrolytic capacitorsFiberCapacitance
The invention discloses a carbon compound cathode material for an ultracapacitor battery, comprising a nuclear layer and a shell layer, wherein the shell layer accounts for the total weight of 10-40 percent; the nuclear layer is made of graphite materials subjected to surface nanometer treatment; and the shell layer is made of a porous carbon material. The surface nanometer treatment of the nuclear layer is to form a nano carbon fiber, a cabon nanotube or a nano hole on the surface of natural graphite, artificial graphite or an in intermediate phase carbon microsphere material in situ; and the porous carbon material comprises a three-dimensional structure that millipores are distributed on a carbon organism. Metal elements are doped in the shell layer. The component formula is reasonable; the prepared material has the nuclear and shell structures in which the metal elements are doped; meanwhile, the invention has favorable characteristics of energy accumulation by using double electric layers and lithium ion stripping / embedding, can effectively improve the high multiplying power and the power density of a lithium ion battery, meets the double requirements of the ultracapacitor battery on energy accumulation by using the lithium ion and double electric layers of the cathode material, can be used as a cathode of a high-performance lithium ion battery, and has favorable high multiplying power charge-discharge performances and industrial prospect.
Owner:CENT SOUTH UNIV +1

Graphite/silicon@carbon core-shell structure composite spherical cathode material and preparation method thereof

The invention discloses a graphite/silicon@carbon core-shell structure composite spherical cathode material and a preparation method thereof. By means of the material, the volume expansion effect of silicon in the lithium de-intercalation process can be inhibited, and a high-capacity lithium iron battery silicon/carbon composite cathode material is obtained. By means of the technical scheme, a spherical graphite/silicon framework precursor serves as the core of the composite cathode material, and an amorphous pyrolytic carbon or graphite-like carbon material wrapping layer serves as the shell; nanometer or micrometer silicon is embedded in flake graphite cracks to form a graphite framework, the volume expansion effect of silicon in the lithium de-intercalation process is inhibited through the mechanical characteristics of the graphite framework, then a spherical framework is formed by mixing and granulating 3-20 wt% of nanometer or micrometer silicon, 50-80 wt% of flake graphite and 10-40 wt% of amorphous pyrolytic carbon or graphite-like carbon, and an amorphous pyrolytic carbon or graphite-like carbon spherical composite conductive carbon net structure wrapping a graphite/silicon surface is formed.
Owner:四川聚能仁和新材料有限公司

Lithium ion battery cathode material with variable slope concentration gradient doping structure and preparation thereof

InactiveCN108649205AThe rate of change of concentration increasesGood element doping distributionElectrode thermal treatmentSecondary cellsSurface layerSynthesis methods
The invention discloses a lithium ion battery cathode material with a variable slope concentration gradient doping structure and a synthesis method thereof. For solving the problems of capacity fadingand rate performance degradation which are brought by the conventional doping method, an element with a variable slope concentration gradient structure is doped, thereby obtaining the lithium ion battery cathode material with the concentration of a doping element continuously changed from the center of a material particle to the surface of the material particle; and change rate is gradually increased from inside to outside, so that the concentration of the doped element inside the material is slowly changed, the concentration of the doped element on the surface of the material is rapidly changed, and change of the concentration of the doped element is mainly concentrated on a surface layer. The method improves stability of the internal structure and the surface of the material while sideeffect is not introduced, the problems such as phase change of the material, volume change and dissolution of transition metal elements in a charge-discharge cycle process are reduced, cycle life of the material is greatly prolonged, and safety performance of the material is greatly improved.
Owner:HARBIN INST OF TECH

Lithium iron phosphate electrode material having three-dimensional hierarchical structure, and preparation method thereof

The present invention relates to a lithium iron phosphate electrode material having a three-dimensional hierarchical structure, and a preparation method thereof. The preparation method comprises: 1) sequentially adding a surfactant and a phosphorus source compound to a solvent, and uniformly stirring for use; 2) dispersing an iron source compound in a solvent, and uniformly stirring for use; 3) dispersing a lithium source compound in a solvent, and uniformly stirring for use; 4) mixing and stirring the solutions or suspensions of the phosphorus source compound, the iron source compound and the lithium source compound, and loading into a reaction kettle; 5) carrying out a reaction under a hydrothermal or solvothermal condition, and washing and drying the obtained product to obtain lithium iron phosphate with various hierarchical structures; and 6) calcining to obtain the hierarchical structure lithium iron phosphate material having high crystallinity. According to the present invention, the preparation method is the wet chemical method for preparing the lithium ion battery positive electrode material lithium iron phosphate (LiFePO4) by adopting the precursor directly obtained through the hydrothermal or solvothermal reaction, and the surface activity structure-oriented method is adopted to design and construct the electrode material having high specific surface area and excellent electrochemical property.
Owner:WUHAN UNIV OF TECH

Additive and solvent of lithium secondary battery electrolyte

The invention relates to an additive and a solvent of a lithium secondary battery electrolyte, belonging to the field of lithium battery materials. The structural formula of the additive is shown as the specification, wherein R represents an alkyl group of which the carbon atom number is 1-20 or an alkyl group of which the carbon atom number is 1-20 and hydrogen is replaced by halogen atoms; R' is one selected from the alkyl group of which the carbon atom number is 1-20, the alkyl group of which the carbon atom number is 1-20 and the hydrogen is replaced by the halogen atoms, an alcoxyl ethylof which the carbon atom number is 1-20, an alcoxyl ethyl of which the carbon atom number is 1-20 and hydrogen is replaced by halogen atoms, an aryl group of which the carbon atom number is 6-30 or an aryl group of which the carbon atom number is 6-30 and hydrogen is replaced by halogen atoms; the mass percent of the additive is 1-50%; and preferably the solvent is a solvent which contains isocyanate compounds with the mass percent of 1-50%. The electrolyte containing the additive and the solvent is high in conductivity at a low temperature, can form an SEI (solid electrolyte interface) film on the anode surface of the lithium secondary battery and is high in safety and oxygenolysis potential.
Owner:BEIJING INSTITUTE OF TECHNOLOGYGY
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