Precisely identifying the amount of graphitization in carbon-based battery anodes is a vital step in the optimization of electrochemical capabilities as well as their ability to store energy. X-Ray diffraction (XRD) analysis has become an important method to accurately measure the amount of graphitization.
The amount of graphitization can be quantified by ascertaining the location of the (002) reflection. The amount must be >90 %; however, the optimal amount is dependent on the cathode and the anode. Thus, specific battery types should be monitored for graphitization amounts as routine quality control by the operators.
Thermo Scientific™ SolstiX™ Pronto Software automates this analysis procedure, providing quick and dependable results. In addition, compliance with the Chinese norm GB/T 24522-2019 guarantees adherence to industry standards.
Insights from XRD analysis, in combination with automation abilities, allow manufacturers and researchers to optimize analytical workflow and guarantee battery anode performance.
Instrument and Software
The Thermo Scientific™ ARL™ X’TRA Companion (Figure 1) benchtop XRD offers simplified, user-friendly instrumentation for regular phase analysis alongside accommodating more advanced applications.
The ARL X’TRA Companion utilizes a θ/θ goniometer (160 mm radius) in Bragg Brentano geometry combined with a 600 W X-Ray source (Cu or Co).
The beam's radial and axial collimation is managed through divergence and Soller slits, while a variable beam knife minimizes air scattering. Additionally, an integrated water chiller is provided as an added option.
With its advanced solid-state pixel detector (55 x 55 μm pitch), the ARL X’TRA Companion ensures rapid data collection. Moreover, it offers one-click Rietveld quantification capabilities and automated result transmission to a Laboratory Information Management System (LIMS).
Figure 1. ARL X’TRA Companion diffraction system. Image Credit: Thermo Fisher Scientific - Elemental and Phase Analysis
Experimental
Graphite anode material was blended with Silicon at a 2:1 ratio to serve as an internal standard and then measured in reflection mode using Cu Kα (1.541874 Å) radiation for a duration of 10 minutes. Employing a certified internal standard ensures more accurate absolute peak positions during refinements.
The sample was prepared in a zero-background sample holder to minimize penetration depth error, and the acquisition was carried out with a spinning sample. As per the guidelines outlined in GB/T 24522-2019 GB norm and referenced sources,1,2 the degree of graphitization is calculated as follows:
g=(3.4400-d002)/(3.4400-3.3540)
Figure 2. Measurement (10 minutes) of a graphite anode material sample (silicon added as internal standard). Image Credit: Thermo Fisher Scientific - Elemental and Phase Analysis
Results
Upon analyzing the position of the (002) reflection of graphite using automated Rietveld refinement (refer to Figure 2), the degree of graphitization was determined to be 96.396 %, with a corresponding d002 value of 3.3571 Å.
The objective was to enhance cathode/anode interaction by identifying an optimal g value, typically exceeding 90%.
Conclusion
The ARL X’TRA Companion is ideal for determining the amount of graphitization for battery anode material. Results are produced by a one-click analysis in compliance with GB/T 24522-2019 norm.
Acknowledgments
Based on materials originally authored by Dr. Simon Welzmiller, Yu Weicai, Application Specialist XRD.
References and Further Reading
- GB/T 24533-2019 Graphite negative electrode materials for lithium-ion battery (English Version)
- C.N. Barnakov, G.P. Khokhlova, A.N. Popova, S.A: Sozinov, Z.R. Ismagilov, ECTJ 2015, 17, 87-93.
This information has been sourced, reviewed and adapted from materials provided by Thermo Fisher Scientific - Elemental and Phase Analysis.
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