Nanostructured battery active materials and methods of producing same
Methods for producing nanostructures from copper-based catalysts on porous substrates, particularly silicon nanowires on carbon-based substrates for use as battery active materials, are provided. Related compositions are also described. In addition, novel methods for production of copper-based catalyst particles are provided. Methods for producing nanostructures from catalyst particles that comprise a gold shell and a core that does not include gold are also provided.
1. A method for producing a carbon-based porous substrate comprising catalyst nanoparticles, comprising:
providing a carbon-based porous substrate comprising a population of particles comprising at least one of natural graphite particles, synthetic graphite particles, graphene particles, or carbon black particles;
mixing deionized water with a copper source and a chelating agent to form a first aqueous solution comprising copper ions, wherein the copper source comprises at least one of copper sulfate, copper nitrate, copper chloride, or copper acetate and wherein the chelating agent comprises at least one of Rochelle salt (i.e. potassium sodium tartrate), EDTA, or polyols, and wherein the copper ions concentration is up to 5 millimolar;
mixing deionized water with a reducing agent and sodium hydroxide to form a second aqueous solution, wherein the reducing agent comprises at least one of sodium ascorbate or ascorbic acid;
mixing the first aqueous solution with the second aqueous solution to form Cu 2 O colloidal nanoparticles in a solution via chemical reduction of the copper ions, wherein the pH of the solution is set between 8 and 11 and wherein the concentrations are adjusted to control the size distribution of the Cu 2 O colloidal nanoparticles and to obtain a stable Cu 2 O hydrosol;
depositing the Cu 2 O colloidal nanoparticles onto a surface of the carbon-based porous substrate by stirring a solution comprising the Cu 2 O colloidal nanoparticles and the carbon-based porous substrate until the solution is substantially completely depleted of the Cu 2 O colloidal nanoparticles; and
recovering the carbon-based porous substrate with the Cu 2 O nanoparticles deposited thereon by filtration.
2. The method of claim 1 , wherein the particles in the population of particles in the carbon-based porous substrate have an average diameter between 0.5 μm and 50 μm.
3. The method of claim 1 , wherein the particles in the population of particles in the carbon-based porous substrate have an average diameter between 2 μm and 10 μm.
4. The method of claim 1 , wherein stirring the solution comprising the Cu 2 O colloidal nanoparticles and the carbon-based porous substrate until the solution is substantially completely depleted of the Cu 2 O colloidal nanoparticles comprises stirring until the concentration of the Cu 2 O colloidal nanoparticles in the solution is less than 1 ppm.
5. The method of claim 1 , wherein the Cu 2 O nanoparticles have an average size between 5 nm and 100 nm as measured by a light scattering measurement or by electron microscopy.
6. The method of claim 1 , wherein the Cu 2 O nanoparticles have an average size between 20 nm and 50 nm as measured by a light scattering measurement or by electron microscopy.
7. The method of claim 1 , wherein the Cu 2 O nanoparticles have an average size between 20 nm and 40 nm as measured by a light scattering measurement or by electron microscopy.
8. The method of claim 1 , further comprising, after recovering, drying the carbon-based porous substrate with the nanoparticles deposited thereon in an oven at 120° C. for at least 12 hours.