Sodium-Ion Coin Cell Assembly Checklist: Na Metal Tips

To assemble a sodium-ion coin cell with sodium metal, work in an argon glovebox, cut a clean sodium disc as the counter electrode, stack the parts in a fixed order with a separator that suits sodium, add a measured amount of electrolyte, crimp, then rest and check the cell before testing. The steps look like lithium coin cells, but sodium metal and sodium electrolytes bring their own pitfalls. Use this checklist each time so your half-cell data stays comparable.

Before you start: checklist

Check	Done?
Glovebox atmosphere logged (moisture and oxygen readings)
Working electrodes punched and vacuum-dried
Cases, spacers and springs clean and dry
Separator discs cut and dried
Electrolyte bottle date and batch recorded
Sodium metal and tools ready inside the glovebox
Crimper die set for CR2032
Build record sheet ready

 

Example materials from a published method

There is no single standard recipe, but published papers show what a working set-up looks like. One 2025 study of a sodium cathode used:

Item	What the study used
Cell format	CR2032 coin cell
Counter electrode	Thin sodium metal foil
Separator	Glass fibre membrane
Electrolyte	1 M NaClO₄ in EC/PC with 10 wt% FEC
Atmosphere	Argon glovebox, moisture and oxygen about 0.3 ppm
Working electrode area	1.33 cm²
Voltage window	2.0–4.3 V (the paper also reports tests to 4.5 V)

 

Source: arXiv 2505.02201. Treat this as an example, not a rule: match electrolyte, separator and voltage window to your own material and record what you use.

Preparing the sodium metal electrode

Sodium metal reacts strongly with water and air, so all handling happens inside the glovebox, with tools kept only for sodium. Cut or punch a disc slightly larger than the working electrode so it covers the whole electrode face; our guide to coin cell punch diameters lists common sizes. Use a fresh, shiny surface; a dull or crusty disc adds resistance and noise to your data. Collect sodium scraps in a dedicated, labelled container for safe disposal through your safety office.

How to assemble a sodium ion coin cell with sodium metal, step by step

1. Place the working electrode in the bottom case, coated side up.
2. Add a measured drop of electrolyte to wet the electrode.
3. Place the separator, centred, and wet it with a measured amount of electrolyte.
4. Place the sodium disc on the separator, centred over the working electrode.
5. Add the spacer, then the spring.
6. Place the top case with gasket.
7. Crimp once, firmly, with the die set for CR2032.
8. Wipe the outside, label the cell and log it on the build sheet.

Use the same electrolyte amount for every cell in a study and write it down. For the general CR2032 procedure, see our step-by-step CR2032 coin cell assembly guide.

After crimping: checks

• Measure open-circuit voltage and note any cell that looks out of family.
• Let cells rest before testing so the electrolyte wets fully, and keep rest time the same for all cells.
• Set the voltage window and rate for your material, and record them.
• Keep failed or leaking cells separate and dispose of them through your safety office.

Common mistakes assembling sodium-ion coin cells

Mistake	What it does to your data
Oxidised sodium surface	Higher resistance and noisy voltage curves
Sodium disc smaller than or offset from the working electrode	Uneven current and misleading capacity
Different electrolyte amounts between cells	Spread in capacity and cycle life
Separator not suited to sodium or not fully wetted	Poor cycling or early shorts
Wet working electrodes	Side reactions and low first-cycle efficiency
Uneven crimp pressure	Leaks or high internal resistance
No build record	Results cannot be explained or repeated

 

For more fault-finding, our coin cell troubleshooting guide covers shorts, low capacity and high resistance. Half-cell results against sodium metal tell you about the working electrode, not how a full cell will behave.

Our sodium-ion battery materials range covers cathodes, hard carbon and related supplies, and Canrd’s lab team builds sodium-ion test cells every week.

Frequently asked questions

What separator is used in sodium-ion coin cells?

The 2025 study cited here used a glass fibre membrane. Whatever you choose, cut and dry discs before use, wet them fully, and keep the same separator across every cell you plan to compare.

Can I use a lithium-ion electrolyte in a sodium coin cell?

No. Sodium cells need a sodium salt electrolyte. One published example uses 1 M NaClO₄ in EC/PC with 10 wt% FEC. Choose an electrolyte suited to your material and voltage window, and record the batch and amount for every cell.

Why is my sodium half-cell data noisy?

Common causes are an oxidised or uneven sodium surface, a sodium disc that does not cover the working electrode, uneven electrolyte amounts, wet electrodes or poor crimping. Check your build record against the mistakes table and rebuild a few cells with fresh sodium.

 

Need sodium-ion materials or coin cell parts? Tell us what you are testing, and we will suggest materials and hardware: speak with a specialist.