We provide a mesoporous silicon material (PSi) prepared via a template-free and HF-free process. The production process is facile and scalable, and it may be conducted under mild reaction conditions. The silicon may be produced directly by the reduction of a silicon-halogenide precursor (for example, SiCl.sub.4) with an alkaline alloy (for example, NaK alloy). The resulting Si-salt matrix is then annealed for the pore formation and crystallite growth. Final product is obtained by removal of the salt by-products with water.

Shell and tube heat exchangers that include a baffle arrangement that improves the temperature profile and flow pattern throughout the exchanger and/or that are integral with a reaction vessel are disclosed. Methods for using the exchangers including methods that involve use of the exchanger and a reaction vessel to produce a reaction product gas containing trichlorosilane are also disclosed.

Shell and tube heat exchangers that include a baffle arrangement that improves the temperature profile and flow pattern throughout the exchanger and/or that are integral with a reaction vessel are disclosed. Methods for using the exchangers including methods that involve use of the exchanger and a reaction vessel to produce a reaction product gas containing trichlorosilane are also disclosed.

Described herein are electrochemically active-material structures comprising silicon and one or more inert elements, chemically and/or atomically dispersed in these electrochemically active-material structures. Also described are negative battery electrodes and lithium-ion electrochemical cells comprising such electrochemically active-material structures as well as methods of fabricating such structures, electrodes, and lithium-ion electrochemical cells. Some examples of atomically-dispersed inert elements include, but are not limited to, hydrogen (H), carbon (C), nitrogen (N), and chlorine (Cl). Unlike silicon, inert elements do not interact with lithium at an operating voltage of the negative battery electrode and therefore do not contribute to the overall cell capacity. At the same time, these inert elements help to mitigate silicon swelling by operating as a mechanical buffer, support structure, and/or additional conductive pathways. Such electrochemically active-material structures can be formed by reacting (chemically or electrochemically) one or more precursors that include silicon and corresponding inert elements.

Described herein are electrochemically active-material structures comprising silicon and one or more inert elements, chemically and/or atomically dispersed in these electrochemically active-material structures. Also described are negative battery electrodes and lithium-ion electrochemical cells comprising such electrochemically active-material structures as well as methods of fabricating such structures, electrodes, and lithium-ion electrochemical cells. Some examples of atomically-dispersed inert elements include, but are not limited to, hydrogen (H), carbon (C), nitrogen (N), and chlorine (Cl). Unlike silicon, inert elements do not interact with lithium at an operating voltage of the negative battery electrode and therefore do not contribute to the overall cell capacity. At the same time, these inert elements help to mitigate silicon swelling by operating as a mechanical buffer, support structure, and/or additional conductive pathways. Such electrochemically active-material structures can be formed by reacting (chemically or electrochemically) one or more precursors that include silicon and corresponding inert elements.