11082results about How to "Improve cycle stability" patented technology

A durable electrode material suitable for use in Li ion batteries is provided. The material is comprised of a continuous network of graphite regions integrated with, and in good electrical contact with a composite comprising graphene sheets and an electrically active material, such as silicon, wherein the electrically active material is dispersed between, and supported by, the graphene sheets.

The invention relates to a high-capacity lithium-ion electrolyte, a battery and a preparation method of a battery, in particular to the high-capacity lithium-ion electrolyte and the battery using the high-capacity lithium-ion electrolyte and the preparation method of the battery. The electrolyte disclosed by the invention comprises lithium salt and non-aqueous organic solvent, and also consists of the following components in weight percent in terms of the total weight of the electrolyte: 0.5-7% of film-forming additive, 0-15% of flame-retardant additive, 2-10% of antiovefill additive, 0.01-2% of stabilizer and 0.01-1% of wetting agent; the electrolyte can enable the anode with high Ni content to work stably, and reduce the battery cost; the high-capacity lithium-ion battery can perform high ratio capacity and excellent safety and high temperature property and cyclic life fully due to the addition and synergetic functions of various functional additives.

The invention belongs to the fields of material synthesis and energy technology, and especially relates to a graphene/metal oxide composite cathode material for lithium ion batteries and a preparation method thereof. Grapheme is dispersed into various metal oxide precursor salt solutions; a graphene/metal oxide compound is obtained directly by a hydrothermal method, or an graphene/metal oxide compound is obtained by a liquid in-situ polymerization method or a coprecipitation process; and the graphene/metal oxide compound is obtained by heat treatment or hydrothermal treatment. In the invention, the novel three-dimensional composite cathode material of graphene-coated metal oxide or graphene-anchored metal oxide is prepared by carrying metal oxide particles with graphene as a carrier. The obtained composite material can be used as a lithium ion battery cathode, which has a high specific capacity, excellent cycle stability and rate capability, and is expected to be used as a lithium ion battery cathode material with a high energy density and a high power density.

This invention discloses a silicon carbon compound negative material and its preparation method for Li ionic batteries, which takes silicon and carbon phase compound particles as the base of sphericity or its like covered by a carbon layer. The preparation method includes: crushing the carbon phase particles to be mixed with silicon phase particles and sized to become a compound particle matrix to be covered with the precursor of the organic pyrolyzed carbon then to be carbonized and crushed. Compared with the current technology, this invention takes the compound material of Si and C phase particles as the matrix covered by a compound negative material, in which, the reversible specific volume of which is greater than 450mAh/g, the first circulation coulomb efficiency is greater than 85% and the volume holding rate for 200 times is greater than 80% to greatly reduce the volume effect of the Si activated material when absorbing and discharging Li and improve the diffusion performance of Li in activated materials.

Disclosed in the invention are a silicon-carbon composite anode material for lithium ion batteries and a preparation method thereof The material consists of a porous silicon substrate and a carbon coating layer. The preparation method of the material comprises preparing a porous silicon substrate and a carbon coating layer. The silicon-carbon composite anode material for lithium ion batteries has the advantages of high reversible capacity, good cycle performance and good rate performance. The material respectively shows reversible capacities of 1,556 mAh, 1,290 mAh, 877 mAh and 474 mAh/g at 0.2 C, 1 C, 4 C and 15 C rates; the specific capacity remains above 1,500 mAh after 40 cycles at the rate of 0.2 C and the reversible capacity retention rate is up to 90 percent.

The invention discloses a grapheme/silicon composite material for a lithium ion battery cathode material and a preparation method thereof, belonging to the fields of electrochemistry and new energy materials. The method comprises the following steps of: using graphite as a raw material; oxidizing the graphite into oxidized graphite by adopting oxidants of concentrated sulfuric acid and potassium permanganate; then, ultrasonically stripping the oxidized graphite to prepare oxidized graphene; mixing oxidized graphene in different proportions with nano silicon powder; ultrasonically dispersing, filtering or directly drying into a cake/film; and roasting under a reduction atmosphere to prepare self-support graphene/silicon composite film materials in different proportions. Proved by electrochemistry tests, the graphene/silicon composite film material prepared by the method has higher specific capacity and cycle stability, simple preparation method and easy mass production and consequently is an ideal high-energy lithium ion battery cathode material.

A preparation method of a high power capacity lithium ion battery cathode material uses natural spherical graphite to serve as raw materials, uses concentrated sulfuric acid to serve as an inserting layer agent, uses potassium permanganate to serve as an oxidizing agent, conducts expansion treatment at high temperature to obtain micro-expanded graphite, then enables the micro-expanded graphite in different proportions to be mixed with nanometer ganister sand, conducts ultrasonic dispersion, suction filtration and dying to obtain the micro-expanded graphite with the nanometer ganister sand inserted in layers, enables the micro-expanded graphite to be mixed and coated with carbon source carbon source according to certain proportion, and finally conducts carburizing sintering under inert gas shielding to prepare completely coated silicon carbon composite cathode material with sufficient obligated obligate inside. Electrochemistry shows that the silicon carbon composite material prepared by the preparation method has high specific capacity and cycling stability and is the ideal high power capacity lithium ion battery cathode material.

The invention relates to a graphene-modified lithium iron phosphate positive electrode active material and a method for preparing the same, as well as a lithium-ion secondary cell based on this positive electrode active material. The positive electrode active material is prepared by a method in which graphene or graphene oxide and lithium iron phosphate are dispersed in an aqueous solution, agitated and ultrasonicated to mix homogeneously and for a mixture, dried to obtain a lithium iron phosphate material compounded with graphene or graphene oxide, and annealed at high temperature to obtain finally a graphene-modified lithium iron phosphate positive electrode active material. When compared with conventional modified lithium cells coated with carbon or doped with conductive polymers, the lithium-ion secondary cell based on this positive electrode active material features high cell capacity, good cycling performance of charge and discharge, long life and high cycle stability, and has great utility value.

The invention discloses a doped modified lithium nickel cobalt manganese material, a preparation method thereof and a lithium ion battery. A secondary particle of the doped modified lithium nickel cobalt manganese material is composed of a primary particle and is spherical or spherical-like in shape, and the surface of the primary particle is non-uniformly doped with a nano metal oxide layer. In the preparation method, a precursor of the lithium nickel cobalt manganese material is doped with nano metal oxides during a synthesis stage and undergoes doping modification. Compared with the prior art, the doped modified lithium nickel cobalt manganese material is used as an anode activity material of the lithium ion battery, under a charge/discharge condition of 4.45 V, has good circulation and good thermal stability, and can meet requirements of high energy density, high power density, long service life and high safety of the lithium ion battery.

The invention discloses a silicon-carbon negative electrode material of a lithium ion battery and a preparation method thereof, and solves the technological problem of improving the charge and discharge cycling stability of the electrode material. The silicon-carbon negative electrode material is prepared by mixing a silicon-carbon composite material and a natural graphite material, wherein the weight of the silicon-carbon composite material is 7-20% and the silicon-carbon composite material is prepared by depositing carbon nanotube and/or carbon nanofiber on the surface of nanometer silica fume and/or embedding into the nanometer silica fume to form core, the surface of which is covered with 3-15wt% of a carbon layer. The preparation method provided by the invention comprises steps of: precursor silicon powder preparation; chemical vapor deposition; liquid-coating roasting; crushing; and mixing. In comparison with the prior art, the reversible specific capacity of the silicon-carbon composite negative electrode material is greater than 500mAh/g; the coulombic efficiency for a first cycle is greater than 80%; the capacity conservation rate of cycling for 50 weeks is greater than 95%. The preparation method is simple, is easy to operate, requires low cost and is suitable for a high-volume negative electrode material of lithium ion batteries used for various portable devices.

The invention discloses a hard carbon material for a power and energy-storage battery and a preparation method thereof, and aims to solve the technical problem of improving high-rate charge-discharge performance of lithium-ion batteries. The material is provided with a hard carbon matrix, and a coating is coated outside the hard carbon matrix; and the surface of the hard carbon matrix has a honeycomb opening structure. The preparation method comprises the following steps of: dipping, washing, dewatering and drying, presintering at low temperature, crushing, pyrolyzing, crushing and coating. Compared with the prior art, the hard carbon material has the reversible specific capacity of more than 450mAh/g, the first cycle columbic efficiency of over 81 percent, 0.2C 300-cycles capacity-retaining rate of over 97 percent at the temperature of 60 DEG C, and the 0.2C 300-cycles capacity-retaining rate of over 88 percent at the temperature of -30 DEG C, has the advantages of excellent lithium intercalation and deintercalation capability and cycling stability, and simple preparation process, and is applicable to the lithium ion battery cathode materials for lithium ion power batteries, various portable devices and electric tools.

The present invention discloses a preparation method of a complex lithium negative pole of a solid state battery, and belongs to the technical field of electrochemistry and new energy resources. The preparation method mainly comprises the steps: depositing lithium metal on three-dimensional carbon material or foam porous material gaps by using a heat infusing melting method or an electrodeposition method to obtain the complex lithium negative pole, wherein the application of a three-dimensional framework plays two roles, namely, providing adequate space for pre-storing lithium in the preparation process; providing a carrier for receiving metal lithium in a battery circulation process. The complex lithium negative pole can be widely applied in lithium metal batteries such as lithium ion batteries, lithium-air batteries, lithium-sulfur batteries, and solid state batteries. In the assembled symmetric solid state battery, under large electric current density of 5mA cm-2, a stable voltage decay (200mV) can still be kept after circulation for 100 times, in the battery circulation, the growth of lithium dendrites can be inhibited and the pole volume change can be stabilized, and the advantages of being good in circulation stability, and long service life can be realized; in the present invention, a carrier material is rich, and low in price; the process is controlled, the cost is low, and the batch production can be realized.

The invention discloses a manganese/lithium phosphate of lithium iron battery positive pole material and a production method thereof, the technical issue to be solved is to improve electrochemical performances of the positive pole material. The material of the invention includes substrates of manganese/lithium phosphate which are covered by a carbon material covering layer, the lithium covering the manganese/lithium phosphate behind the carbon material covering layer is spherical and has microscopic characteristics of being near spherical, rhombic, tapered, tabular, layered or/and block-shaped as well as of having 0.5-30 mum long and short axles. The production method comprises the following steps of: production of nanometer particles, liquid phase mixed reaction, production of precursor, sintering treatment, covering organic substances. Compared with the prior art, the invention improves the electron conductivity of the manganese/lithium phosphate by covering with carbon liquid phase, the carbon sufficiently covers active materials to efficiently prevent particle aggregation, the invention has the characteristics of about 4V of discharge voltage, high discharge and charge capacitance, excellent circulation stability, high safety, simple process, low cost and little influence on the environment.

The invention discloses a method for preparing an aluminum oxide coated modified lithium nickel cobalt manganese oxygen cathode material. The method comprises the following steps of: (1) preparation of a precursor: mixing water-soluble metallic nickel salt, cobalt salt and manganese salt into a mixed solution, dripping the mixed solution, a precipitator and a morphological control agent into a reaction container, controlling the pH value and reaction temperature of a system, and performing filtering, washing and vacuum drying after reaction to obtain a (NixCoyMn1-x-y)(OH)2 precursor, wherein x, y and x+y are more than 0 and less than 1; (2) preparation of an aluminum oxide coated precursor: dispersing the (NixCoyMn1-x-y)(OH)2 precursor, water-soluble aluminum salt and a disperser into deionized water, stirring while heating until the disperser is hydrolyzed, filtering to obtain an Al(OH)3-coated (NixCoyMn1-x-y)(OH)2 precursor, roasting the precursor in a sintering furnace to obtain Al2O3-coated (NixCoyMn1-x-y)(OH)2 precursor powder; and (3) uniformly mixing the Al2O3-coated (NixCoyMn1-x-y)(OH)2 precursor powder with lithium salt powder, and calcinating at high temperature to obtain an aluminum oxide coated modified Li(NixCoyMn1-x-y)O2 cathode material with a lamellar crystal structure.

The invention relates to the field of negative electrode materials of lithium ion batteries, and specifically to a nanometer lithium titanate/graphene composite negative electrode material and a preparation process thereof. According to the invention, micron-sized lithium titanate prepared by the solid phase method is subjected to ultrafine ball milling to obtain nanometer powder, and the nanometer lithium titanate powder and graphene are uniformly compounded and subjected to heat treatment so as to obtain a high performance lithium ion battery negative electrode material; the invention is characterized in that uniform distribution of graphene in the nanometer lithium titanate powder is realized through in situ compounding; the weight of graphene in the composite negative electrode material accounts for 0.5 to 20%, and the weight of lithium titanate accounts for 80 to 99.5%. The lithium ion battery negative electrode material has good electrochemical performance, 1C capacity greater than 165 mAh/g, 30C capacity greater than 120 mAh/g and 50C capacity greater than 90 mAh/g. Nanometer lithium titanate in the lithium ion battery negative electrode material prepared in the invention has high phase purity; the preparation process of the material is simple and is easy for industrial production.

The invention discloses a graded high-nickel ternary anode material, and a preparation method and an application thereof. The graded high-nickel ternary anode material is prepared by the following method: 1) mixing a high-nickel polycrystalline precursor with anhydrous LiOH and a doping additive, performing sintering, mixing the obtained product with a coating additive, and performing sintering toobtain a high-nickel polycrystalline material; 2) mixing a ternary monocrystalline silicon precursor with a lithium source and the doping additive, performing sintering, mixing the obtained product with the coating additive, and performing sintering to obtain a ternary monocrystalline silicon material; and 3) mixing the high-nickel polycrystalline material with the ternary monocrystalline siliconmaterial, or mixing the mixed material with the coating additive, and then performing sintering. The invention further discloses an application of the graded high-nickel ternary anode material in lithium batteries. The graded material prepared by the method provided by the invention has higher compaction and cycle stability than the single polycrystalline material, has higher capacity than the single monocrystalline silicon, and the gas production and service life problems of the battery can be effectively improved after the grading modification.

The invention relates to a high polymer-based graphene composite material with positive resistance temperature coefficient, and a preparation method of the material. The composite material comprises a base body and conductive filler; the content of conductive material is 0.01-10wt%; all components are mixed uniformly and are formed through mold-pressing or extrusion/injection molding; and the formed material is irradiated after being dried, so that the high polymer-based graphene composite material with positive resistance temperature coefficient can be obtained. Compared with the prior art, the graphene composite material and the preparation method have the advantages that the manufacturing process is simple, less influence is caused to the performance of base material, oxidation is unlikely to occur, the resistivity is more stable, the circulation stability of the material is better, and NTC (Negative Temperature Coefficient) effect is not generated easily.

The invention relates to a gradient distribution multivariate composite material precursor as well as a preparation method of the gradient distribution multivariate composite material precursor and an application in preparation of a lithium ion battery anode material. The precursor is prepared from the following molecular formula: NixCoyMnzM1-x-y-z(OH)2, wherein x is more than 0.2 and less than 0.8, y is more than 0.1 and less than 0.5, z is more than 0 and less than 0.6, and M is a doped metal ion and comprises one or more of Mg, Ca, Zn, Al, Cr, Zr and Ti; the precursor comprises a core part and an outer layer shell part in which multiple layers are sequentially covered in the core; a molecular formula composition of the core part is NikConMnmM1-k-n-m(OH)2, wherein k is more than 0.5 and less than 1, n is more than 0.05 and less than 0.5, and m is more than 0 and less than 0.6; and the outer layer shell part is used for controlling the proportion of the raw material components and a preparation process to ensure that the material composition of the outer layer shell part is distributed in a gradient mode. Compared with a ternary material with a uniform internal structure, the lithium ion battery anode material has the advantages that the high specific discharge capacity is developed; and meanwhile, the cycling stability, the high-temperature cycling stability and the rate capability of the materials also can be greatly improved.

The invention discloses an MOFs (metal-organic frameworks) based carbon dioxide adsorbent, which includes MOFs and organic amine loaded in the pore channels and on the surface of MOFs. The mass ratio of the MOFs to the organic amine is 0.1-10:1. The MOFs based carbon dioxide adsorbent provided by the invention realizes the combined action of physical adsorption and chemical adsorption and can adsorb and store carbon dioxide at medium and low temperature, and regeneration and reutilization of the adsorbent can be realized under certain condition. The MOFs based carbon dioxide adsorbent has good adsorption capacity, high selectivity and cycling stability on carbon dioxide, and can overcome the disadvantages of easy volatilization and easy corrosion of equipment in organic amine so as to meet the industrial processing requirements. The invention also discloses a preparation method of the MOFs based carbon dioxide adsorbent and application of the adsorbent in adsorption of carbon dioxide in flue gas.

The invention provides a method for preparing a multilevel porous carbon base composite phase change material, and belongs to the field of composite phase change materials. The method comprises the following steps: at first, preparing an organic metal skeleton material by using such methods as a solution method, a solvothermal method or a stirring synthesis method; with the organic metal skeleton material as a template, high temperature carbonizing under the protection of an inert gas, and changing the carbonizing temperature and the post treatment manner to obtain a multilevel porous carbon material with a super-large specific surface area and a super-large pore volume; selecting proper solvents according to different kinds of phase change core materials, preparing the phase change core materials to a solution, dispersing the porous carbon material into the solution, removing the solvent by such manners as heating, and meanwhile the phase change core materials are adsorbed and limited in the porous carbon material. The composite phase change material prepared by the method provided by the invention has good thermal storage property, can effectively avoid the leakage problem of the phase change core material, and has the advantages of excellent heat transfer property, good cycling stability and wide application range, and the process is simple and is suitable for large-scale production.

The invention relates to a method for preparing nitrogen-doped porous carbon nanofiber cloth. The nitrogen-doped porous carbon nanofiber cloth is prepared by adding a nitrogen-rich compound into an organic solution, electrospinning and subsequent carbonizing-activating, has a self-support structure, omits preparation steps of size mixing, coating and the like, needs no conductive agent or binder, and can be directly used as the negative electrode of a lithium ion battery. The electrochemical performance of the negative electrode material of the lithium ion battery is improved by doping nitrogen and activating and forming pores; compared with a commercial graphite lithium ion battery negative electrode material, the nitrogen doping porous carbon nanofiber cloth used as the negative electrode material of the lithium ion battery has simple steps for preparing the electrode, has higher specific capacity, good power performance and circulatory stability. The method also can be used as the electrode material of super capacitors and other novel batteries.

The invention discloses a lithium ion battery silicon carbon composite anode material and a preparation method thereof. The material is prepared by twice spray drying and once sintering. The preparation method comprises the following steps of: 1) dissolving an organic carbon source in an appropriate amount of solvent, adding a silicon source and a dispersing agent for dispersing suspension uniformly, adding graphitized carbon for dispersing the suspension for a certain period of time, and performing primary spray drying on the uniformly dispersed suspension to obtain a spherical nucleus material; and 2) dissolving the organic carbon source in the appropriate amount of the solvent, adding the prepared spherical nucleus material, dispersing the suspension uniformly, performing secondary spray drying on the uniformly dispersed suspension to obtain powder, transferring the powder into a protective atmosphere for sintering, and performing furnace cooling on the powder to obtain the lithium ion battery composite anode material. The preparation method is simple and practicable and has high practicality; and the prepared silicon carbon composite material has the advantages of large reversible capacity, designable capacity, high cycle performance, high rate capability, high tap density and the like.