This disclosure relates to novel lithium ion battery structures and methods of manufacture. One particular method includes a method of coating a porous glass substrate. The method includes: providing a porous glass substrate; flowing gaseous hydrocarbon onto a porous glass substrate in a reaction zone; and exposing the porous glass substrate to a concentrated solar irradiation in the reaction zone such that the porous substrate and gases surrounding the porous substrate absorb the concentrated solar irradiation producing heat. The heat chemically reduces glass fibers in the porous glass substrate into silicon fibers, and the heat decomposes the gaseous hydrocarbon into a carbon coating on the silicon fibers.