Method for Manufacturing Porous Silicon for Lithium Secondary Batteries and Lithium Secondary Battery Using the Same

Porous Silicon for Lithium Batteries with Expanded Pores via HF-Free Two-Step Acid-Base Etching

This technology produces porous silicon by first dissolving the metal component of a silicon-metal alloy compound in an acidic solution to create micro-pores, followed by a secondary etching process with a basic solution to expand the internal pores of the silicon particles.

Conventional methods for manufacturing porous silicon require the use of hydrofluoric acid (HF), which is hazardous to human health. These methods also necessitate expensive precious metal catalysts or costly processing equipment and struggle to control pore size, limiting their ability to suppress anode volume expansion and improve battery lifespan.

This technology utilizes a two-step etching process: first, removing metal from the alloy with a 0.1–0.4M acidic solution to create micro-pores, and second, further etching the silicon around these pores with a 0.05–0.3M basic solution before neutralizing with acid. The resulting internal pores absorb silicon expansion during lithiation, extending electrode life. Applicable to mass production of silicon anode materials, chemical plants with strict safety regulations, and long-life lithium-ion battery anodes, this method allows for pore structure control using only common chemicals like HCl and NaOH.

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Key Features:

• Etching a silicon-metal alloy compound with an acidic solution to form micro-pores in the silicon
• Re-etching the micro-pored silicon with a basic solution to form porous structures
• Adding an acidic solution to the etched mixture to neutralize the basic components
• Extracting the porous silicon from the neutralized solution through filtration and drying

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This invention was developed with support from the Ministry of Trade, Industry and Energy for the development of high-energy-density lithium-ion secondary batteries for electric vehicles.

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