Abstract: A method of controlling the crystallinity of a silicon powder may include heating a reactor to a temperature of no more than 650° C., and flowing a feed gas comprising silane and a carrier gas into the reactor at a molar gas flux of from about 5 mol/min/m2 to about 25 mol/min/m2. The silane decomposes to form a silicon powder having a controlled crystallinity and comprising non-crystalline silicon. According to another embodiment, a method of controlling the crystallinity of a silicon powder may include flowing a feed gas comprising silane and a carrier gas into a heated reactor at a molar gas flux of from about 5 mol/min/m2 to about 25 mol/min/m2, and maintaining an internal reactor pressure of about 2 atm or less during the flowing of the feed gas into the heated reactor. The silane decomposes to form a silicon powder having a controlled crystallinity and comprising non-crystalline silicon.

Abstract: An electrode composition comprises a silicon powder comprising non-crystalline and crystalline silicon, where the crystalline silicon is present in the silicon powder at a concentration of no more than about 20 wt. %. An electrode for an electrochemical cell comprises an electrochemically active material comprising non-crystalline silicon and crystalline silicon, where the non-crystalline silicon and the crystalline silicon are present prior to cycling of the electrode. A method of controlling the crystallinity of a silicon powder includes heating a reactor to a temperature of no more than 650° C. and flowing a feed gas comprising silane and a carrier gas into the reactor while maintaining an internal reactor pressure of about 2 atm or less. The silane decomposes to form a silicon powder having a controlled crystallinity and comprising non-crystalline silicon.

Abstract: The present invention relates to a heat exchange element for use in the direct process. The heat exchange element comprises a heat exchange element with a wear resistant coating on the surface of at least a portion of its surface. The wear resistant coating forms strong bonds to the heat exchange element and has a hardness greater than 50 Rockwell C. Such a coating can survive the physical and chemical environment present in the direct process.