CoHCF Cathode Active Material and Manufacturing Method Thereof

CoHCF Cathode Material with Reduced Na Content and Lattice Distortion via Low-Temperature Co-precipitation (0–10℃)

This technology refines particles and lowers Na content by controlling the co-precipitation temperature of cobalt hexacyanoferrate (CoHCF), a Prussian blue analogue, to a low range of 0–10℃. This process reduces lattice distortion, thereby improving rate capability and cycle life.

Conventional cobalt hexacyanoferrate produced at room temperature or higher suffers from high Na content, leading to significant lattice distortion. Furthermore, an increased Co2+ ratio reduces redox activity and increases irreversibility, resulting in poor rate capability and limited long-term cycle life.

This technology involves co-precipitating cobalt and iron cyanide precursors with a citrate chelating agent at 0–10℃, followed by 10–15 hours of aging. This configuration achieves a Co3+ ratio of 0.3 or higher and a Na ratio of less than 1.5. Applicable as a cathode material for aqueous sodium-ion batteries and grid-scale energy storage systems, it offers the benefit of enhanced capacity retention during high-rate discharge simply by managing cooling temperatures.

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Key Features:

• Inducing co-precipitation by adding a second aqueous solution of Na4Fe(CN)6·10H2O to a first aqueous solution of Co(NO3)2·6H2O and trisodium citrate
• Performing the entire addition and aging process within a low-temperature range of 0℃ to 10℃
• Obtaining the cathode active material by performing aging for 10 to 15 hours after co-precipitation
• Cobalt hexacyanoferrate cathode active material with controlled atomic ratios: Co3+ ≥ 0.3, Co2+ ≤ 0.7, Fe < 0.90, and Na < 1.5

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