Wacker Chemie Ag

Harald Hertlein

Dirk Weckesser

Rainer Hauswirth

Friedrich Popp

Dieter Weidhaus

Heinz Kraus

Eckhard Hanelt

Gerhard Forstpointner

Karl Hesse

Robert Maurer

Jürgen Pfeiffer

Oliver Kraetzschmar

Benedikt KÖNINGER

Oliver Krätzschmar

An anode active material for lithium ion batteries includes one or more unaggregated silicon particles having a mass-based chlorine content of from 5 to 200 ppm and a volume-weighted particle size distribution having diameter percentiles dof from 0.5 μm to 10.0 μm.

Silicon particles having a specific chlorine content, as active anode material for lithium ion batteries

The invention relates to a process for preparing polycrystalline silicon, comprising introducing a reaction gas containing hydrogen and silane and/or halogen silane into a reactor, wherein the reactor comprises at least one heated carrier body, on which elementary silicon has been deposited by means of pyrolysis, forming the polycrystalline silicon. In a continuous process, waste gas is led out of the reactor and hydrogen recovered from said waste gas is fed to the reactor again as circulating gas. The circulating gas has a nitrogen content of less than 1000 ppmv. The invention further relates to polycrystalline silicon having a nitrogen component of less than 2 ppba.

Process for preparing polycrystalline silicon

The invention relates to a method for producing polycrystalline silicon granulate in a fluidized bed reactor. The method comprises a fluidization of silicon seed particles by means of a fluidizing gas in a fluidized bed, which is heated by a heating device, wherein elemental silicon is deposited by pyrolysis on the silicon seed particles by the addition of a reaction gas containing hydrogen and silane and/or halosilane to form the polycrystalline silicon granulate. In a continuous process, waste gas is discharged from the fluidized bed reactor and hydrogen recovered from said waste to gas is again supplied to the fluidized bed reactor as a circulating gas. The circulating gas has a nitrogen content of less than 1000 ppmv. The invention further relates to polycrystalline silicon granulate having a nitrogen content of less than 2 ppba.

The rate of rod fallover in the production of polycrystalline silicon by the Siemens process is sharply reduced by cleaning the Siemens reactor base plate by at least a two-step procedure comprising suctioning the base plate in one step, and subsequently cleaning with liquid or solid cleaning medium in a second step, between each phase of rod removal and new support body installation.

Method for producing polycrystalline silicon

Assembly of a fluidized bed reactor for the preparation of polycrystalline silicon granules by chemical vapor deposition of silicon onto seed particles and removal of polycrystalline silicon granules is facilitated without breakage and with gas tightness by a specific assembly sequence.

Fluidized bed reactor for producing polycrystalline silicon granules and method for the assembly of such a fluidized bed reactor

The native oxide layer on silicon support rods in the Siemens polysilicon production process is removed by heating the rods to a temperature of 1100-1200&#xb0; C. and contacting the rods with hydrogen at a system pressure of 1.1E5 to 6E6 Pa. Oxide is rapidly removed, reducing overall process time and increasing space time yield. The use of hydrogen, optionally purified from a polysilicon deposition and containing only traces of HCl reduces reactor corrosion and loss of silicon from the support rods.

Granular polysilicon is produced in a fluidized-bed reactor by fluidizing silicon particles by means of a gas flow in a fluidized bed heated to a temperature of 850-1100&#xb0; C., adding a silicon-containing reaction gas by means of a nozzle and depositing of silicon on the silicon particles, wherein, in at least 56% of an axially symmetric region around a nozzle opening of the nozzle,

Fluidized bed reactor and method for producing granular polysilicon

Contamination of surfaces of polysilicon rods removed from a Siemens reactor in a polysilicon production facility is reduced by cleaning the production facility at least every other week with a cleaning liquid containing water, optionally also containing neutral surfactants.

Cleaning of CVD production spaces

Granular polycrystalline silicon includes a compact matrix including radiating acicular crystal aggregates of crystal size from 0.001-200 &#x3bc;m. A process for producing granular polycrystalline silicon includes producing granular silicon in a fluidized bed reactor from a gas mixture containing TCS (20-29 mol %) and hydrogen at a fluidized bed temperature of 900-970&#xb0; C., dividing the granular silicon in a screen system having at least one screen deck into at least two screen fractions, the smallest screen fraction being ground in a grinding system to give seed particles having a size of 100-1500 &#x3bc;m and a mass-based median value from 400 to 900 &#x3bc;m, and these seed particles being supplied to fluidized bed reactor, and a further screen fraction being supplied to a fluidized bed reactor, and being surface-treated with a gas mixture containing TCS (5.1-10 mol %) and hydrogen at a fluidized bed temperature of 870-990&#xb0; C.

Granular polycrystalline silicon and production thereof

High-purity polysilicon granules are prepared by depositing reaction gas on silicon granules in a fluidized bed reactor having:

Process for the continuous production of polycrystalline high-purity silicon granules

Brittle polysilicon rods having a rod cross-section of 80-99% available for electrical conduction and a flexural strength of 0.1 to 80 N/mmare produced by a process wherein the temperature of the bridge of polysilicon rods in the Siemens process is held at a high temperature and the flow rate of chlorosilanes is increased to the maximum within a short time. The rods are easily fragmented with low force, resulting in polysilicon with a low level of metallic impurities.

Polycrystalline silicon and method for the production thereof

A fluidized bed process for the production of polycrystalline silicon granules supplies, in addition to reaction gas, a gas containing 99.5 to 95 mol. percent hydrogen and 0.5 to 5 mol. percent gaseous silicon compounds, and the reactor wall is maintained at the same or a higher temperature than the reaction zone, such that the deposition of silicon on reactor internals is minimized.

Growing community of inventors

Burghausen, Germany

Harald Hertlein