I have seen the terms "gravimetric capacitance", "volumetric capacitance", "areal capacitance" and "specific capacitance" used severally in different places but I cannot clearly distinguish between them. Please what are the differences between the terms? Also, can I use them interchangeably?
It's all about the following,
Specific capacitance or gravimetric capacitance values are indicated in Farads/gram (F/g)
Areal capacitance values are indicated in Farads/(cm x cm) = F/cm2
Volumetric capacitance values are indicated in Farads/(cm x cm x cm) = F/cm3. It is sometimes indicated in F/litres too.
Depending on the applications these F/g or F/cm2 or F/litres might be important so ideally, all these are important while majority literatures report F/g.
All these refer to capacitance normalized to different parameters: mass (gravimetric capacitance), volume (volumetric capacitance), footprint area (areal capacitance). Specific capacitance is typically the way people call gravimetric capacitance (at least in battery science). Note that for all of these, it is important to know what is the part of the device that is used for normalization (e.g. is it the mass of active electrode material, of the entire electrode or of the entire device).
Yes, gravimetric capacitance is a more clear wording. Still, you can mention in your paper that both therms are often and historically used as interchangeable (although if you look from just the linguistic point of view, "specific capacitance" does not indicate whether the capacitance is specific to mass or volume, which is why gravimetric capacitance is a better way to describe capacitance normalized to mass). Good luck with the writing!
Gravimetric capacitance=specific capacitance=F/mass
Volumetric capacitance=F/volume of active material used
Areal capacitance = F/ area of electrode
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