337results about How to "Improve first-time efficiency" patented technology

The invention discloses a silicon-carbon composite material, a lithium ion battery, and a preparation method and application of the silicon-carbon composite material. The preparation method of the silicon-carbon composite material comprises the steps: uniformly mixing silicon powder and silicon monoxide powder, then mixing with a solution containing an organic carbon source dispersant, and performing wet-process ball milling to obtain a slurry; uniformly mixing the slurry, graphite and a conductive agent, and performing spray drying to obtain spherical-like particles, wherein graphite is synthetic graphite and/or intermediate-phase graphite; mixing the spherical-like particles and asphalt, performing cladding processing under the inert atmosphere to obtain a cladded material; and then performing carbonizing processing to obtain the silicon-carbon composite material, wherein silicon powder, silicon monoxide powder, graphite and asphalt respectively accounts for 5-15%, 3-10%, 45-75% and 5-40% by weight of the sum of the above materials, and the organic carbon source dispersant and the conductive agent both accounts for 0.1-2% by weight of the sum of silicon powder, silicon monoxide powder and graphite. The silicon-carbon composite material has relatively good cycle performance, and can be directly used as a cathode material of the lithium ion battery. The preparation method is simple in technology, low in cost and applicable to industrial production.

The invention belongs to the technical field of lithium-ion battery, and in particular relates to a method for supplementing lithium powder to a lithium-ion battery negative plate. The method comprises the following steps: a first step, putting the cold-pressed negative plate on an unwinding and rewinding mechanism, and putting lithium powder to a feeding mechanism above the negative plate; a second step, adding electric fields and opening the feeding mechanism, so that the lithium powder is adsorbed on the surface of the negative plate under the action of the electric fields; and a third step, rolling the negative plate adsorbed with the lithium powder. Compared with the prior art, the method can control the movement of the lithium powder to overcome the flotation of metal lithium powder in air through electrostatic effect provided by the electric fields, and can simultaneously control the addition of the lithium powder and the dispersion degree of the lithium powder on the negative plate, thereby uniformly, quantitatively and precisely dispersing the lithium powder on the surface of the negative plate. Besides, the whole process provided in the invention is only needed to be carried out in a drying environment without adding the lithium powder in a process of preparing slurry, has a simple manufacture process and low cost, and is suitable for large-scale production.

The invention relates to a high-capacity SiOx based composite negative electrode material, a preparation method and a battery, wherein the negative electrode material comprises a silicon oxide material, a carbon material and an amorphous carbon coating layer; the silicon oxide material is silicon oxide or silicon oxide material modified in a carbon coating manner; surfaces of carbon material particles are coated with the silicon oxide material. A preparation method of the high-capacity SiOx based composite negative electrode material comprises the steps of performing physical processing or carbon coating modification on a silicon oxide raw material, thus obtaining a micron-sized silicon oxide material; and then mechanically fusing, coating with a solid phase and sintering at a high temperature to obtain the high-capacity negative electrode material. Through the high-capacity SiOx based composite negative electrode material, the effect of uniform dispersing and coating of the micron-sized silicon oxide particles on the surfaces of the carbon material particles can be achieved by virtue of the combination of mechanical fusion and solid-phase coating processes. The silicon oxide particles are well dispersed on the surface of the carbon material particle; the strength of bonding between the silicon oxide particles and the carbon material particles is high; the recycling performance of the material can be greatly improved; and meanwhile, the high-capacity SiOx based composite negative electrode material is high in first efficiency (breaking through the theoretical efficiency of SiOx), low in expansion rate, long in service life, environmental-friendly, pollution-free and low in cost.

The invention relates to a high-capacity graphite material and a preparation method as well as application thereof. The high-capacity graphite material comprises artificial graphite and natural graphite, wherein the mass ratio of artificial graphite to natural graphite is 20:1 to 1:1. According to the preparation method, the artificial graphite and the natural graphite are uniformly mixed according to a certain mass ratio, and then surface modification is carried out on the mixture. The prepared graphite material has the advantages of high discharge capacity, high first efficiency, long cycle life, low cost and the like; the discharge capacity of the high-capacity graphite material can reach up to more than 350mAh/g (even reach up to more than 368mAh/g); a half-cell of the high-capacity graphite material charges and discharges at the 1C multiple power; after the high-capacity graphite material cycles for 100 times, the capacity retention ratio of the high-capacity graphite material is still more than 90% (even reaches up to more than 96.3%); the first efficiency reaches up to more than 95.5%; and the manufacturing cost is reduced by about 1-10%. The high-capacity graphite material provided by the invention not only can meet the requirement of a lithium ion power battery for the high multiplying power charge-discharge of the material, but also reduces the manufacturing cost of the cathode material of the lithium ion battery.

The invention discloses a preparation method of a silicon composite anode material for lithium ion batteries and the silicon composite anode material is composed of nc-Si/ packing carbon/ cracking carbon. Packing carbon powder is adopted as scattered matrix, Li-Si alloy powder is adopted as a reducing agent and a liquid silicon halide or a liquid silane halide is chemically deoxidized by the high-energy ball milling; afterwards, heat treatment and solvent washing are conducted over the deoxidized silicon halide or silane halide under the shielding gas so as to obtain an nc-Si/ packing carbon complex, wherein the nc-Si is nanometer porous silicon and nanometer silicon fiber. The nc-Si/ packing carbon complex passes through the high-molecular carbon source cladding and heat treatment under the shielding gas to obtain an nc-Si/ packing carbon/ cracking carbon composite anode material. A charge-discharge test of constant current is conducted at a current density of 0.1 mA/mg to 0.3 mA/mg; the coulombic efficiency of the first circulation of the silicon composite anode material reaches up to 70 percent to 80 percent; and after 30 circulations, the reversible capacity reaches 680 mAh/g and the capacity retention rate reaches more than 95 percent.

The invention discloses a silicon alloy composite anode material and a preparation method thereof as well as a lithium ion battery employing the anode material. An inner core of the anode material comprises graphite and silicon alloy applied to the surface of the graphite, and a shell is a pyrolytic carbon layer. The silicon alloy anode material with a core-shell structure is prepared in combination with nanocomposite, surface modification and coating modification technologies. The silicon alloy composite anode material is high in compaction density, good in processing performance, high in conductivity, high in first efficiency (more than 90%) and excellent in cyclic stability (400-time cyclic capacity retention rate is more than 92%); the preparation process of the anode material provided by the invention is simple, environment-friendly and pollution-free, and raw materials are low in cost.

The invention provides a ternary precursor with a composite hetero-structure. The molecular formula of the ternary precursor is Ni<1-a-b>CoM(OH)2@Ni<1-x-y>Co<x>M<y>O<z>, wherein 0<a<1, 0<b<1, 0<a+b<1, 0<x<1, ,0<y<1, 0<x+y<1, 1<z<1.5, and M represents Mn or Al. The ternary precursor comprises a ternary oxide precursor and a ternary hydroxide precursor. The ternary hydroxide precursor is coated on the surface of the ternary oxide precursor. The molecular formula of the ternary oxide precursor is Ni<1-x-y>Co<x>M<y>O<z>, and the molecular formula of the ternary hydroxide precursor is Ni<1-a-b>CoM(OH)2. The invention further provides a preparation method of the ternary precursor. According to the preparation method, a spray pyrolysis method and a co-precipitation method are combined, the ternary oxide precursor obtained by spray pyrolysis is taken as the seed crystal, then a layer of ternary hydroxide precursor is coated on the surface of the ternary oxide precursor through theco-precipitation method to obtain the ternary precursor, and the ternary precursor and lithium salts are mixed and sintered to prepare the ternary cathode material. The ternary cathode material has the advantages of good layered structure, high initial efficiency, high specific capacity, and excellent circulating ratio performance.