Meaning
Characterization technique that uses small angle X-ray scattering to measure the size, shape and volume of sealed internal pores within carbon anode materials. Performing SAXS closed pore analysis provides a non destructive method to quantify the voids that are inaccessible to gas adsorption techniques. This analysis is critical for evaluating the sodium storage capacity of hard carbon, which represents a crucial step in the raw material qualification process for advanced sodium ion batteries.
Scattering Method
X-rays are scattered by the electron density differences between the carbon skeleton and the empty pores. The scattering method of the analysis yields a continuous intensity curve that is mathematically converted to pore size distributions. This calculation provides a highly accurate volume fraction of the internal voids.
Capacity Correlation
Closed pore volume is directly related to the sodium plateau capacity of the anode material. The capacity correlation of the carbon sample is established by comparing the scattering data with electrochemical testing results. Carbon materials with a high volume of closed pores deliver higher energy densities.
Quality Control
Battery manufacturers use this analysis to verify the consistency of incoming carbon materials from suppliers. The quality control of the anode raw materials ensures that the final cells will perform within the designated specifications. This validation reduces the risk of cell performance variations.
