Cobalt vs Nickel
Cobalt and Nickel are genuine alternatives to one another — a choice somebody actually makes — and differ on 5 measured properties, density most clearly.
Cobalt vs Nickel
Cobalt
Co
A blue pigment for three thousand years, a battery cathode today, and a supply chain concentrated in one country.
| Property | Cobalt | Nickel |
|---|---|---|
| Atomic number | 27 | 28 higher |
| Density | 8.92 g/cm³ higher | 8.9 g/cm³ |
| Electrical conductivity Only one of the two has a figure we can stand behind, so there is nothing to compare. | Not known | 14.3 MS/m |
| Melting point | 1492.8–1495 °C higher | 1455 °C |
| Mohs hardness Mohs hardness is an ordinal scale: values can be ranked, but differences and ratios between them are not meaningful. | about 5 higher | about 4 |
| Molar mass | 58.933194 g/mol higher | 58.6934 g/mol |
Choosing between them
Nickel is recorded as a substitute for Cobalt — cheaper, less supply-constrained, lower environmental impact.
What it gives up: A nickel-rich cathode is less thermally stable, which is a safety engineering problem rather than a free win.
Partial substitute, on the evidence cited above.