How to Read a Battery Material Spec Sheet
Particle size, surface area, capacity, and moisture. Which numbers predict how a powder behaves in your cell, and which ones need context before you trust them.
A spec sheet is a supplier's summary of a material, not the full picture. Two cathode powders with the same headline capacity can behave very differently in your slurry, your coating, and your cycling data. Knowing which numbers to look at, and what to ask when a number is missing, saves you weeks of troubleshooting that looks like a chemistry problem but isn't.
Particle size: look at the spread, not just the D50
D50 is the median particle size, and it's the number most people check first. The D10 and D90 matter just as much. A wide distribution packs differently, coats differently, and can hide a fraction of fines that drives side reactions. If two lots share a D50 but have different spreads, expect them to behave like two different materials.
Tap density and surface area
Tap density tells you how well the powder packs. It affects the electrode density you can reach and your volumetric energy. Specific surface area (BET) tells you how much surface is exposed to the electrolyte. Higher surface area can help rate performance, but it usually costs you first-cycle efficiency and adds side reactions. Read these two numbers together with particle size, because they describe the same particles from different angles.
Capacity and first-cycle efficiency need their test conditions
A capacity value alone doesn't tell you much. Ask for the C-rate, voltage window, temperature, electrode loading, and whether it was measured in a half cell or a full cell. A number measured at a slow rate over a wide voltage window will look better than what you'll see in your own test. First-cycle (initial Coulombic) efficiency deserves the same question, since it tells you how much lithium you lose up front.
Moisture and residual lithium
Moisture is easy to overlook and expensive to ignore. It affects slurry stability and cell performance. For nickel-rich cathodes, also ask about residual lithium on the surface. High levels can make an NMP/PVDF slurry gel and cause gassing later. If the sheet doesn't list either one, ask.
Impurities
Metallic contaminants such as iron and copper, including magnetic impurities, can cause self-discharge and internal shorts even at ppm levels. A good spec sheet lists them with the test method.
The certificate of analysis matters more than the brochure
A spec sheet shows the target range. A certificate of analysis (CoA) shows what was measured on your lot. Ask for the CoA with every order, check that it includes actual values and test methods, and compare lot to lot. Consistency between lots often matters more to your research than any single impressive number.
Before you order, check that you have:
- D10, D50, and D90, not just D50
- Tap density and BET surface area
- Capacity and first-cycle efficiency with full test conditions
- Moisture, and residual lithium for Ni-rich cathodes
- Metallic and magnetic impurity levels
- A lot-specific CoA with test methods
Quick check: 3 questions
1. Two lots of the same cathode have identical D50 values but different D10 and D90. What should you expect?
A) Identical performance B) Different packing and coating behavior C) Only a color difference
Show answer
B. The spread matters as much as the median. A different distribution packs, coats, and reacts differently.
2. A higher BET surface area usually costs you what?
A) First-cycle efficiency B) Tap density only C) Nothing, it is always better
Show answer
A. More exposed surface means more side reactions and more lithium lost in the first cycle.
3. Which document shows what was actually measured on your lot?
A) The product brochure B) The spec sheet C) The certificate of analysis
Show answer
C. The spec sheet shows the target range. The CoA shows your lot's actual values.
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Every battery material we ship from Littleton comes with a certificate of analysis on request. If you're comparing materials and want help reading a spec sheet, request a quote or reach out to our team.
