CR2032 battery

Analysis of the preparation process of ternary materials for CR2032 battery

Ternary materials mainly refer to nickel-cobalt-manganese-lithium materials (NCM), but NCM materials (especially high-nickel 811, 532, etc.) generally have difficulties in synthesis and unstable cycle performance. This requires improvements in the synthesis process and roasting process. Today, the editor will take you to familiarize yourself with the preparation process of NCM precursors.

After more than 20 years of development, CR2032 battery have made great progress in both reliability and battery performance. A variety of positive electrodes have also been developed in this process, such as lithium cobalt oxide, which has the longest history, as well as lithium iron phosphate, lithium manganese oxide, etc. However, with the further improvement of the performance indicators of CR2032 battery, these materials can no longer meet the requirements, and ternary materials are born.

Ternary materials mainly refer to nickel-cobalt-manganese-lithium materials (NCM). Its biggest advantage is high capacity. For example, the capacity of NCM811 material can reach about 220mAh/g, which is significantly improved compared to lithium cobalt oxide (140mAh/g). NCM materials also have high voltage potential and can be charged to 4.35V. At the same time, the addition of manganese also reduces the cost of materials. However, NCM materials (especially high-nickel 811, 532, etc.) generally have problems of difficult synthesis and unstable cycle performance. This requires improvements in the synthesis process and calcination process. Today, the editor will take you to familiarize yourself with the preparation process of NCM precursors.

The electrochemical properties of NCM materials depend to a large extent on the morphology of the precursor and the uniformity of particle distribution. At present, the main method used in industry is the coprecipitation method, and the main raw materials are cobalt sulfate, nickel sulfate, nickel sulfate and sodium bicarbonate. Make ammonium bicarbonate into a solution, dissolve manganese sulfate, cobalt sulfate and nickel sulfate in deionized water at a mass ratio of 0.54:0.13:0.13, and slowly add ammonium bicarbonate solution and stir continuously. The pH value of ammonium bicarbonate solution is 7.78. At this pH value, Ni2+, Co2+, and Mn2+ will all generate carbonates, but no hydroxides and basic carbonates will be generated. The specific reaction equation is as follows:

The precipitate obtained by the reaction is filtered and washed with deionized water until no sulfate residue remains (using BaCl2 solution for detection until no white precipitate appears in the filtrate). The precipitate is placed in a vacuum oven and dried at 80°C to obtain the precursor of the ternary material-ternary carbonate. In actual production, the conversion rate of sulfate is closely related to the concentration of the reactants, the ratio between the reactants and the temperature of the reaction.

When the concentration of ammonium bicarbonate increases from low to high, the color of the solution changes from dark to light, to colorless, and then to dark. The color of the solution represents the residual metal ions in the solution. Therefore, there is an optimal value for the concentration of ammonium bicarbonate. Near this concentration, the metal ion precipitation effect is best. When it is less than or greater than this concentration, the metal ion precipitation will be insufficient, causing waste and environmental pollution. Secondly, the concentration ratio of ternary metal salt and ammonium bicarbonate will also affect the precipitation effect of metal ions. After fixing the concentration of ammonium bicarbonate, the amount of ammonium bicarbonate solution added was adjusted. It was found that with the addition of ammonium bicarbonate solution, the color of the solution gradually became lighter. When the ratio reached 1:5, the solution was basically colorless. The conversion efficiency at this time was calculated to be 91.2%. Increasing the amount of ammonium bicarbonate had little effect on the conversion efficiency. For lithium-ion battery materials, morphology also has a significant influence on electrical properties. In production, the precursor is generally required to be uniform spherical particles. In actual production, it was found that with the increase in the amount of ammonium bicarbonate, the spherical particle size of the precursor increased slightly. Therefore, the size of the precursor can be regulated according to demand and purpose.

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