Density of a property of material or device is the property normalised against the volume or area (i.e. dimensions).
Why the unit Wh/kg has been used for energy density in so many literatures on electrochemical energy storage? Similarly, the unit kW/kg is also used for power density by many authors.
Why do they not use specific energy with the unit Wh/kg, and specific power with kW/kg?
You are correct. and they should be mentioned as specific energy or specific power.
Yes it correct to use energy density or power density. The unit of Energy is Joule and it can be converted to Watt-hour using simple conversion factor. When we say density it means the the mass of the material per its volume. So the Energy what we measure for a particular mass of material can be said as energy density. Similarly for the the power density. I think we should not get confused with the specific capacitance or gravimeteric capacitance. Any mistakes please correct me.
To educate electrical working peopleKWh/kg came .electrical engineers started using these.
I agree with Dhrubajyoti Bhattacharjya and Prof V.S Muralidharan.
To me, I also think that specific energy should be used in place of energy density
Yes, it is correct use this term. Because, we know that electric energy is nothing but the capacity to do work. Its unit is Joule. But in practise, the electrical energy is measured by interms of watt hour (Wh) or kilowatt hour (kWh). One kWh is known as one unit of electric energy.
1 kWh = 1000 Wh = 1000 x 3600 J = 3.6 x 10^6 J
Again, we familier with the term 'density is mass per unit volume'
Hence, the energy density is the amount of energy stored in a given system per unit volume (surface). Here in battery or supercapacitor what we mean that surface (m^2) is the mass coated area. So, instead of m^2 we assume kg^2.
therefore,
Energy = Wh; Density = Mass (kg)/(kg^2)
Energy density = Wh/kg
I dont know my way of assumption is correct or not. Correct me if it is wrong
here in the density term the numerator mass may be the mass of the electrode and the denominator denotes the surface area (active mass coated on that area)
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