Meaning
Analytical characterization technique utilizes the diffraction of x-rays at high angles to probe the crystalline structure and atomic-scale spacing of battery materials. This method, known as wide angle x-ray scattering, is used to investigate the phase changes, crystalline orientation, and structural degradation of cathode and anode materials during electrochemical cycling. It provides information about structural changes occurring over length scales shorter than several nanometers.
Crystalline Analysis
Scatter patterns collected at large angles correspond to diffraction from atomic planes, yielding precise lattice parameters of the active material. During lithium extraction or insertion, the unit cell of the transition metal oxide expands or contracts, which shifts the scatter peaks. Measuring these shifts using wide angle x-ray scattering allows researchers to track the dynamic phase transitions of the electrode in real time.
This capability is especially important for studying high-nickel cathode materials, which are prone to irreversible structural changes at high state-of-charge limits.
Process Investigation
Operando measurements provide insight into the degradation mechanisms of silicon and graphite composite anodes under fast-charging conditions. If lithium plating occurs, the characteristic peak of metallic lithium can be detected immediately, showing the onset of a safety hazard. This non-destructive observation helps engineers design charging protocols that avoid the formation of hazardous lithium dendrites.
Material Verification
Battery manufacturers employ scattering measurements as a quality control tool to verify the phase purity of synthesized cathode active materials. Batches containing secondary phase impurities like metal oxides or carbonates are identified before being used to formulate electrode slurries. By screening raw materials for crystallographic defects, suppliers maintain the chemical consistency required for high-yield battery cell assembly.
