Method for manufacturing anode material for secondary batteries

Low-Cost SiOx Anode Material Using Water Glass Ion Exchange and Mg/NaCl Scavenger Reduction

This technology utilizes inexpensive water glass (alkali silicate) as a raw material, replacing metal ions with hydrogen ions via ion-exchange resin. Through spray drying and a reduction process involving a scavenger (NaCl), it produces SiOx anode active materials with controlled volume expansion.

Silicon-based anodes suffer from rapid degradation due to significant volume changes exceeding 400% during charge and discharge cycles. SiOx-based anode active materials have also been limited by high manufacturing costs and low initial efficiency.

This technology involves exchanging alkali metal ions in water glass with hydrogen ions, creating spherical powders via spray drying, and reacting the dried product with a reducing agent (Mg) and a scavenger (NaCl) in a weight ratio of 1:0.7–1.3:0.5–1.5 to suppress impurities like Mg2SiO4. A carbon coating layer can be added using a dopamine precursor if needed. Applicable as a SiOx additive for graphite anodes or as a high-capacity anode material for entry-level EVs and small electronics, it offers a way to replace expensive SiO deposition processes with sodium silicate, a common chemical raw material.

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Key Features:

• Step of exchanging metal M in the mM2O·nSiO2·yH2O alkali metal silicate compound with hydrogen ions
• Step of performing ion exchange by applying a cation-exchange resin to the silicate compound in an aqueous solution
• Step of drying the ion-exchanged compound using a spray drying method prior to reduction
• Reduction step of forming a SiOx compound using the dried product, a Mg reducing agent, and a NaCl scavenger in a weight ratio of 1:0.7–1.3:0.5–1.5

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This invention was developed with support from the Ministry of Trade, Industry and Energy for the development of manufacturing processes for cathode/anode materials and electrodes to achieve high-rate characteristics in lithium secondary batteries for frequency regulation.

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