How to Choose Cell Components
Case coating, stack height, gasket material, and crimping. The component choices that show up in your data as chemistry problems.
Cell components are the cheapest part of a research cell and the most common source of results nobody can explain. A case that reacts with your cathode, a stack that never made proper contact, a gasket that crept over three months of cycling: all of these look like materials problems in the data, and none of them are.
Case coating has to match your voltage window
This is the one that costs people the most time. Bare stainless steel is fine for conventional lithium ion chemistry, but it corrodes at high potential and reacts with lithium metal. If you are working above roughly 4.3 V, use aluminium clad cases on the cathode side. If you are running a lithium metal anode, use copper clad on the anode side. Running bare steel outside its window gives you capacity fade that looks exactly like electrolyte decomposition or cathode degradation, and you can spend months chasing it.
- 304 stainless. General purpose, conventional cathodes within a standard voltage window.
- 316L stainless. Better corrosion resistance, worth the difference for longer cycling and more aggressive electrolytes.
- Aluminium clad. High voltage cathodes, nickel rich NMC, lithium rich layered oxides.
- Copper clad. Lithium metal and other reactive anodes.
Stack height decides whether your cell makes contact
Spacers and the spring have to add up to a stack that is compressed but not crushed. Too little and the layers move, giving high and unstable impedance. Too much and you deform the separator or short the cell during crimping. Spacers commonly come in 0.5, 1.0, and 1.5 mm, and you combine them with a wave spring to reach the right total.
The part people miss: changing electrode thickness means recalculating the stack. If you compare a thin electrode and a thick one using the same spacer set, you are also comparing two different stack pressures, and pressure affects capacity and impedance on its own. Fix the stack height, not the spacer count.
Gasket material is an electrolyte compatibility question
Polypropylene is standard and adequate for most carbonate electrolytes at room temperature. PFA is worth the extra cost for aggressive solvents, elevated temperature testing, and any study running long enough that slow creep becomes a leak. A cell that dries out over two months does not fail dramatically; it just drifts, and the drift looks like degradation.
Crimping pressure is a variable, so treat it like one
Manual crimping introduces more spread than most of the formulation changes people are trying to measure. Use the same crimper, the same pressure setting, and the same operator for a study where the comparison has to hold. If your error bars are wide and you cannot explain them, look at assembly before you look at chemistry.
Buy components for a whole study in one lot
Small dimensional differences between production lots shift crimping pressure and stack height slightly. Within a lot this is consistent; across lots it is not. If you are running a comparison that will be published or that will inform a scale up decision, order enough components for the entire study at once, and note the lot in your records.
Which format?
CR2032 is the research default and gives you the most internal space for spacers and thicker electrodes. CR2025 and CR2016 are thinner, which constrains your stack but can be useful when you want to limit electrolyte volume or match an existing test fixture. If you have no reason to prefer otherwise, use CR2032 and keep your data comparable to everyone else's.
Still not sure?
Tell us your chemistry, voltage window, and electrode thickness and we will specify a matched component set.
