Abstract: A method for treating silicon to form pillars, especially for use as the active anode material in Li-ion batteries, is disclosed. The process is simple to operate on a commercial scale since it uses a solution containing only a small number of ingredients whose concentration needs to be controlled and it can be cheaper to operate than previous processes. The solution includes: 0.01 to 5M HF 0.002 to 0.2M of metal ions capable of nucleating on and forming a porous layer comprising regions of elemental metal on the silicon surface; 0.001 to 0.7M of an oxidant selected from the group O2, O3, H2O2, the acid, ammonium or alkali metal salt of NO3?, S2O82?, NO2?, B4O72? and ClO4? or a mixture thereof. The treated silicon is suitably removed from the solution.

Abstract: A method for treating silicon to form pillars, especially for use as the active anode material in Li-ion batteries, is disclosed. The process is simple to operate on a commercial scale since it uses a solution containing only a small number of ingredients whose concentration needs to be controlled and it can be cheaper to operate than previous processes. The solution includes: 0.01 to 5M HF 0.002 to 0.2M of metal ions capable of nucleating on and forming a porous layer comprising regions of elemental metal on the silicon surface; 0.001 to 0.7M of an oxidant selected from the group O2, O3, H2O2, the acid, ammonium or alkali metal salt of NO3?, S2O82?, NO2?, B4O72? and ClO4? or a mixture thereof. The treated silicon is suitably removed from the solution.