Lithium-Ion Battery Post-Mortem Analysis: Lab Workflow

A lithium-ion battery post-mortem analysis is a planned teardown: you test the cell electrically, image it without opening it, choose the state of charge on purpose, open it in an inert atmosphere, then sample and characterise each component in a fixed order. Each step protects evidence the next one needs. Skip one, and you may lose the answer you opened the cell to find.

This workflow is for grad students, postdocs and lab engineers doing their first or tenth teardown of aged or failed cells. It does not replace your institution’s safety rules: opening lithium-ion cells carries fire and toxic-gas risks, so agree every step with your safety officer first.

The workflow in six steps 1. Record history and run final electrical tests. 2. Image the cell without opening it (X-ray or CT). 3. Choose and set the state of charge for your question. 4. Open the cell in an inert-atmosphere glovebox. 5. Separate components, map positions and take samples. 6. Characterise, document and report.

 

Before opening: history, electrical tests and imaging

Start with what the cell has been through: cycling history, temperatures, storage and any abuse. Then run final electrical checks while the cell is intact, such as capacity at a low rate and impedance. These numbers tell you what to look for inside. Our guide to the eight causes of capacity fade helps link symptoms to likely mechanisms.

Next, image the cell without opening it. X-ray or CT shows electrode alignment, deformation, tab damage and foreign particles that can be disturbed during disassembly. See our comparison of X-ray vs CT inspection.

Choosing the state of charge

There is no single right state of charge for opening a cell. It is a trade-off between safety and evidence, and it should be decided before the teardown and recorded.

Choice	Why choose it	Watch out for
Lower state of charge	Less stored energy if an internal short happens during opening	Some features, such as the charged state of the electrodes, are no longer visible
Defined charged state	Preserves the charged condition, useful for comparing cells or studying lithium inventory	More stored energy; needs stricter precautions and safety approval

 

A 2025 case study on external short circuits, published in the Journal of Materials Chemistry A, brought all cells to an identical 100% state of charge before opening so that results were comparable. Whatever you choose, use the same state of charge for every cell you plan to compare.

How to open a lithium-ion cell safely for post mortem

Open cells in an inert-atmosphere glovebox so moisture and oxygen do not react with the electrodes, lithium deposits or electrolyte. In the 2025 study, cells were opened in an argon glovebox held below 0.1 ppm oxygen and 0.1 ppm water.

1. Plan the cut lines from the X-ray or CT images, away from the electrode stack.
2. Use insulated or ceramic tools, and keep the two tabs from touching anything conductive.
3. Open the outer case or pouch slowly, cutting only the seal or casing.
4. Watch for heat, smoke or gas; stop and follow your emergency plan if they appear.
5. Photograph each layer as it is exposed, before moving anything.
6. Collect electrolyte and residues into labelled, sealed containers for later analysis or disposal.

Wear the protective equipment your safety office specifies and never work alone on charged or damaged cells.

Separating and sampling components

Isolate the positive electrodes, negative electrodes and separator as you unwind or unstack them, so material from one does not contaminate another. The 2025 study did exactly this, then took samples at intervals of about 10 cm along the layers, so the results describe the whole electrode rather than one spot.

• Draw a sample map: layer number, position along the electrode, and side.
• Photograph each sample before cutting it.
• If needed, rinse samples gently with a suitable solvent to remove salt residue, and record which solvent and how long.
• Store samples in sealed, labelled containers inside the glovebox until analysis.
• Transfer to instruments in air-tight holders where possible.

How to detect lithium plating in post mortem

Lithium plating usually shows first as a visual change on the graphite surface: metallic grey or silvery deposits, often near the edges or in areas that saw high current or low temperature. Photograph these areas before they react further, then confirm with microscopy, for example SEM, and with other methods your lab trusts. Note where plating appears on your sample map, because its pattern often points to the cause. For causes and fixes, read our guide on lithium plating issues and solutions.

Which technique answers which question?

Question	Technique (as used in the 2025 study)
Internal structure, deformation, alignment	X-ray computed tomography
Surface morphology and elements	SEM with EDS
Crystal structure changes in active materials	XRD
Nanoscale structure and interfaces	TEM
Lattice disorder and carbon structure	Raman spectroscopy
Chemical bonds in films and residues	FTIR
Thermal behaviour and stability	DSC

 

Choose techniques that answer your question, not all of them. Start with imaging and microscopy, then add structural or chemical methods where the first results point.

Documenting your lithium-ion battery post-mortem analysis

• Keep a photo log of every step, with time and sample code.
• Link each measurement to a position on the sample map.
• Record the state of charge, glovebox conditions and any deviations.
• Note what you expected to find and what you did find, including nothing.

Common post-mortem mistakes

• Opening before imaging. Once the stack is disturbed, alignment and deformation evidence is gone.
• Changing state of charge between cells. Results from cells opened at different states cannot be compared fairly.
• Brief air exposure “just to look”. Reactive surfaces change quickly; keep samples inside the glovebox until they are sealed.
• One sample per electrode. Ageing is rarely uniform. Sample along the length and across layers, as the 2025 study did.
• No reference cell. Where possible, open a fresh or less-aged cell from the same batch the same way, so you can tell ageing from manufacturing features.
• Unrecorded rinsing. Solvent and rinse time change surface films, so record them for every sample.

Most of these come from rushing. A written plan, agreed before the glovebox is opened, prevents nearly all of them.

When to send cells to a specialist lab

Send cells out when you lack a glovebox, X-ray or CT, or the trained people to run them; when the cell is badly damaged or swollen; or when results must stand up to outside review. Some failures leave no clear evidence, and an honest analysis will say so. Our root cause analysis service handles teardowns for research and industry teams.

This workflow was written by the failure analysis team at Canrd Technology.

Frequently asked questions

At what state of charge should a cell be opened for post-mortem?

It depends on the question. A lower state of charge reduces stored energy if a short happens; a defined charged state preserves evidence such as the charged electrode condition. One 2025 study opened all cells at 100% so results were comparable. Decide in advance, record it and get safety approval.

Do I need a glovebox to open a lithium-ion cell?

For meaningful post-mortem results, yes. Room air lets moisture and oxygen react with electrodes, lithium deposits and electrolyte, changing what you want to observe. Published work uses argon gloveboxes with very low oxygen and water levels. Follow your institution’s safety rules for the opening itself.

How can you tell if lithium plating occurred?

Look first for metallic grey or silvery deposits on the graphite surface, often near edges or high-current areas, and photograph them straight away. Confirm with microscopy such as SEM and other methods your lab uses. Record where plating appears, because its pattern can point to the cause.

Which techniques are used in battery post-mortem analysis?

Common methods include X-ray CT for internal structure, SEM-EDS for morphology and elements, XRD for crystal structure, TEM for nanoscale detail, Raman and FTIR for chemical structure, and DSC for thermal behaviour. Choose the methods that answer your specific question rather than running every test.

 

No glovebox or CT access? Send us your cell history, and we will scope a post-mortem with you: send us your failed cells.