Battery Characterization Techniques by Component
| Component | Common questions | Techniques |
|---|---|---|
| Active materials (cathode and anode powders) | Is it phase-pure? Is the particle size distribution and surface area in spec? Is the stoichiometry right? Are trace metals present? | XRD, laser diffraction particle size analysis, BET surface area, SEM, ICP-OES / ICP-MS |
| Electrodes | Is the coating uniform? How are porosity, particles and binder distributed? Is there cracking or delamination? | Mercury intrusion porosimetry, BIB polishing + SEM, FIB cross-sections, EDS mapping, Raman, TGA |
| Electrolytes | Are the solvent, salt and additive levels correct? Has it degraded during manufacturing or cycling? | GC-MS, NMR, ICP-OES / ICP-MS, EIS |
| Separators | What is the polymer? Is the ceramic coating on the correct side? Is it strong enough for winding? | FTIR, ATR-FTIR (each face), tensile testing |
| Complete cells | Why is capacity fading? What changed inside after aging? | Cycling, EIS, 2D X-ray, micro-CT, scanning acoustic microscopy (SAM), teardown |
What the Data Shows: Examples From the Guide
- Cathode powder (NMC811): ICP-OES confirmed a stoichiometry of Li₀.₉₉Ni₀.₈₀Mn₀.₁₀Co₀.₁₀, with Al, Fe and Cu impurities all below 0.01 wt%.
- Cathode structure (NMC333): XRD with Rietveld refinement showed a single phase-pure layered oxide, with no impurity phases.
- Cycled cathode: a FIB cross-section revealed cracking between primary particles, caused by repeated lithiation and delithiation.
- Electrolyte: GC-MS detected trace decomposition products, such as methyl formate and ethyl formate, consistent with early-stage solvent oxidation.
- Separator: ATR-FTIR confirmed a polyethylene base with an alumina ceramic coating on the cathode-facing side.
- End-of-life cells: 2D X-ray showed a jelly roll collapsed at the core of a cylindrical cell, and SAM showed gas or delamination in an aged pouch cell that was absent in a new one
Four Situations the Guide Covers
- Material development: linking powder structure, size, surface area and composition to capacity and cycle life.
- Supplier qualification: confirming that a new lot or supplier is truly equivalent, not just matching on the spec sheet.
- Manufacturing troubleshooting: finding coating defects, cracking and delamination in electrode architecture.
- Lithium-ion battery failure analysis: non-destructive inspection first (2D X-ray, micro-CT, SAM), then targeted teardown and analysis of the cathode, anode, separator, electrolyte and gases.
Why Combine Techniques
No single method shows chemistry, structure, porosity and interfaces at once. XRD confirms the phase but not the particle shape; SEM shows cracking but not the electrolyte breakdown behind it. Pairing complementary methods is how degradation and manufacturing defects are traced to a cause.