Highly Sensitive Analysis of Trace Components in LiFePO₄ Cathode Material

Introduction

LiFePO₄ cathode active materials contain trace components resulting from raw materials or impurities from the manufacturing process, which may affect battery performance, life, and safety. ICP-AES is generally used for the analysis of trace components, but the challenge is that certain elements, such as fluorine and silicon, are difficult to measure. Standardless FP method can improve the detection limit by adding a fixed angle measurement that extends the integration time for the element of interest.

• Analysis: Cathode material
• Use: Optimizing electrochemical performance
• Analyzed materials: LiFePO₄
• Analysis method: Standardless FP analysis method

Figure 1: XRF qualitative chart of each sample 

Figure 2: F-Kα qualitative chart of each sample 

Table 1: SQX analysis results and theoretical standard deviations of each sample

ppm

ND: less than LLD (detection limit value), LLD: 3 times statistical error in background intensity

Conclusion

For the analysis of trace components, fixed angle measurement can be applied to meet the required quantitation limit. From Figure 1 and Table 1, battery-grade cathode materials (samples B and C) were found to contain impurity on the order of tens to thousands of ppm compared to LiFePO₄ reagent (sample A). This implies that the difference between the material grades is high. Furthermore, fluorine, which is difficult for ICP-AES, can be quantitatively analyzed simultaneously with other elements, as shown in Figure 2.

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