The testing process of battery grade lithium carbonate includes several links, and the following is a detailed description of these links:
1. Sampling and reception: representative samples are randomly selected from the production batch, and registered and labelled. This step is to ensure that the selected samples can accurately reflect the quality of the whole batch.
2. Appearance inspection: Visual observation of the sample to check its colour, crystalline state and impurities. Qualified lithium carbonate should be white or off-white crystalline powder without visible impurities.
3. Purity test: Determine the purity of lithium carbonate by titration, turbidimetry and other methods. These methods use chemical reactions to determine the content of lithium carbonate. For example, in the titration method, a standard titration solution of hydrochloric acid is used to react with lithium carbonate, and the content of lithium carbonate is calculated by the amount of hydrochloric acid consumed.
Li2CO3 + 2HCl → 2LiCl + CO2 + H2O
4. Detection of impurity elements: Inductively coupled plasma emission spectrometry (ICP-OES) or inductively coupled plasma mass spectrometry (ICP-MS) and other instrumental analytical methods are used to qualitatively and quantitatively analyse the impurity elements in lithium carbonate. These impurity elements may include iron, copper, zinc, etc., and their presence will affect the performance of the battery.
5. Moisture determination: Determine the moisture content in lithium carbonate by methods such as Karl Fischer Moisture Determination. Excessive moisture may affect product stability and battery performance.
6. Particle size distribution detection: using laser particle sizer and other equipment to detect the particle size distribution of lithium carbonate. Particle size distribution directly affects the preparation of cathode materials and battery performance.
7. pH value measurement: Determine the pH value of lithium carbonate solution to determine its acidity or alkalinity. The appropriate pH value is crucial for battery performance.
8 Data Recording and Reporting: Record the test results in detail and analyse and count them. According to the test results, judge whether the product is qualified or not, and issue the corresponding test report.
9. Disposal of substandard products: For products that fail the test, rework, downgrading or scrapping are required to ensure that substandard products do not enter the market.
10.Continuous Improvement: Through the analysis and summary of testing data, continuously optimise the production process and quality control measures to improve product quality and customer satisfaction.