Does Cobalt Conduct Electricity?

Cobalt is a transition metal with the symbol Co and atomic number 27. It is a solid at room temperature, with a density of 8.9 g/cm³, a melting point of 1495 °C, and a boiling point of 2927 °C. Cobalt is a conductor, with an electrical conductivity of 1.7×10^7 S/m and a resistivity of 6.000000000002×10^-8 m Ω.

Electrical Conductivity of Cobalt

The electrical conductivity of cobalt can be described by the following equation:

σ = 1/ρ

Where:
– σ is the electrical conductivity (S/m)
– ρ is the electrical resistivity (Ω·m)

Cobalt has a high electrical conductivity due to its electronic configuration. Cobalt has 3d^7 4s^2 valence electron configuration, which allows for the delocalization of electrons in the 3d and 4s orbitals. This delocalization of electrons enables the flow of electric current, making cobalt a good conductor of electricity.

The electrical conductivity of cobalt can be influenced by various factors, such as temperature, impurities, and crystal structure. At room temperature, the electrical conductivity of cobalt is approximately 1.7×10^7 S/m, which is comparable to other transition metals like iron and nickel.

Electrical Conductivity of Tungsten Carbide with Cobalt Binder

Tungsten carbide (WC) is a hard, refractory material that is widely used in cutting tools, wear-resistant parts, and other industrial applications. Cobalt is often added to tungsten carbide as a binder to improve the sintering and mechanical properties of the material.

The electrical conductivity of tungsten carbide with a cobalt binder is influenced by several factors:

1. Cobalt Content: Higher cobalt content in the tungsten carbide mixture increases the electrical conductivity. Cobalt has a higher electrical conductivity compared to tungsten carbide, and the addition of cobalt creates more conductive pathways within the material.

2. Sintering Temperature: Increasing the sintering temperature of the tungsten carbide-cobalt mixture can also enhance the electrical conductivity. Higher sintering temperatures promote better densification and reduce the porosity of the material, leading to improved electrical conductivity.

3. Porosity: Lower porosity in the tungsten carbide-cobalt composite results in higher electrical conductivity. Pores and voids within the material act as barriers to the flow of electric current, reducing the overall conductivity.

4. Grain Size: Smaller grain sizes in the tungsten carbide-cobalt mixture typically lead to higher electrical conductivity. Finer grain structures provide more grain boundaries and interfaces, which can facilitate the movement of electrons and improve the overall conductivity.

The electrical conductivity of tungsten carbide with a cobalt binder can range from 2 to 30 μΩ·cm, depending on the specific composition and processing conditions. This is significantly lower than the electrical conductivity of pure copper, which is around 1.7 μΩ·cm.

Electrical Conductivity of LiNi1-xCoxO2 Positive Electrode Material

LiNi1-xCoxO2 (NCA) is a positive electrode material used in lithium-ion batteries, where x represents the cobalt content. The electrical conductivity of this material is an important parameter that affects the battery’s performance and efficiency.

Studies have shown that the addition of cobalt to the NCA material has a negligible impact on its electrical conductivity. The electrical resistance and conductivity of LiNi1-xCoxO2 samples were measured using a pellet press, with a powder pellet thickness of 0.080 cm and an area of 0.785 cm².

The measured resistance values were converted to conductivity using the following equation:

σ = L / (R × A)

Where:
– σ is the electrical conductivity (S/m)
– L is the thickness of the pellet (m)
– R is the measured resistance (Ω)
– A is the cross-sectional area of the pellet (m²)

The resistance ranking from lowest to highest was found to be:
1. NCA with 80% Ni
2. Co-free Ni-rich core–shell materials
3. Ni-Co materials (90% to 100% Ni)
4. SC NMC811

This indicates that the cobalt content in the NCA material has a minimal effect on its electrical conductivity, and other factors, such as the nickel content and the material’s structure, play a more significant role in determining the overall conductivity.

Numerical Examples and Calculations

1. Calculating the Electrical Conductivity of Cobalt
   Given:
2. Electrical resistivity of cobalt (ρ) = 6.000000000002×10^-8 Ω·m

Electrical conductivity (σ) = 1/ρ
σ = 1 / (6.000000000002×10^-8 Ω·m)
σ = 1.7×10^7 S/m

1. Calculating the Electrical Conductivity of Tungsten Carbide with Cobalt Binder
   Given:
2. Electrical conductivity range of tungsten carbide with cobalt binder: 2 to 30 μΩ·cm

Converting the range to S/m:
2 μΩ·cm = 2×10^-6 Ω·m
Electrical conductivity = 1 / (2×10^-6 Ω·m) = 5×10^5 S/m

30 μΩ·cm = 30×10^-6 Ω·m
Electrical conductivity = 1 / (30×10^-6 Ω·m) = 3.33×10^4 S/m

1. Calculating the Electrical Conductivity of LiNi1-xCoxO2 Positive Electrode Material
   Given:
2. Pellet thickness (L) = 0.080 cm = 0.0008 m
3. Pellet cross-sectional area (A) = 0.785 cm² = 0.000785 m²
4. Measured resistance (R) = 1 Ω

Electrical conductivity (σ) = L / (R × A)
σ = 0.0008 m / (1 Ω × 0.000785 m²)
σ = 1.02 S/m

These examples demonstrate the typical range of electrical conductivity values for cobalt, tungsten carbide with a cobalt binder, and LiNi1-xCoxO2 positive electrode material.

Conclusion

In summary, cobalt is a highly conductive transition metal with an electrical conductivity of 1.7×10^7 S/m and a resistivity of 6.000000000002×10^-8 m Ω. The electrical conductivity of tungsten carbide can be improved by increasing the cobalt content, sintering temperature, and reducing porosity and grain size. However, the addition of cobalt to the LiNi1-xCoxO2 positive electrode material has been shown to have a negligible impact on its electrical conductivity, which is more influenced by other factors such as nickel content and material structure.

References:
– Bonzer Bands – Is Tungsten Carbide Conductive?
– IOP Science – The Impact of Cobalt Content on the Electrical Conductivity of LiNi1−xCoxO2
– Periodic Table – Cobalt