Fuel cells vs. Batteries

[TheAspiringDoc]

Hi

I’m a bit confused based on the study design and Heinemann textbook as to how fuel cells and batteries relate.
Is one a subset of the other?
Are they both types of galvanic cells?
What is the best way to think about their relationship?

Thanks!

[TheBigC]

Hi

I’m a bit confused based on the study design and Heinemann textbook as to how fuel cells and batteries relate.
Is one a subset of the other?
Are they both types of galvanic cells?
What is the best way to think about their relationship?

Thanks!

Hey there!

Fuel cells and batteries are two separate cell types.

Fuel cells simply require a continuous supply of reactants, whereby acting as a galvanic cell. These cells can, subsequently, provide a continuous supply of electrical energy. They cannot be classified as batteries as a battery is definitively an apparatus consisting of one or more cells (galvanic cells) used for the production of electrical energy from stored reactant.

Digressing, batteries can be categorised into two separate groups:

1. Primary cells
2. Accumulators or secondary cells

1. Primary cells are non-rechargeable galvanic cells with a limited supply of reactant and upon reaching equilibrium are said to go 'flat'. These cells cannot be recharged.

2. Secondary cells or accumulators are rechargeable cells with a limited supply of reactant, however, their products remain in contact with electrodes in a convertible form (which is unlike primary cells). Ultimately, this enables for the cell to undergo recharging: where products in contact with electrodes can be converted back into reactants through electrolysis. Thus, these cells act as both galvanic cells and electrolytic cells. They act as galvanic cells during discharge and electrolytic cells during recharge.

In summary,

All fuels cells are galvanic cells, not all galvanic cells are fuel cells (fuel cells are not batteries).
All primary cells are batteries, not all batteries are primary cells (primary cells are galvanic cells)
All secondary cells are batteries, not all batteries are secondary cells (secondary cells or accumulators can act as both galvanic and electrolytic cells)

I hope this helped.

[TheAspiringDoc]

Absolute legend!!!

One thing I’m not fully clear on is:

[fuel cells] cannot be classified as batteries as a battery is definitively an apparatus consisting of one or more cells (galvanic cells) used for the production of electrical energy from stored reactant.

Fuel cells technically are one galvanic cell used for the production of electrical energy, so is the reason they are not considered batteries because they do not use stored reactant? Or is it because fuel cells are not portable?

Also, do we need to understand much about all the specific examples of cells (button cells, hydrogen-oxygen, alkaline, dry etc?)

Thanks !!!

Edit:

I hope this helped.

Yes oui yep ja si 100%

Edit #2:
Study design:

the comparison of fuel cells and galvanic cells with reference to their definitions, functions, design features,
energy transformations, energy efficiencies (qualitative) and applications.

But aren’t fuel cells a type of galvanic cell?

[TheBigC]

One thing I’m not fully clear on is:
Fuel cells technically are one galvanic cell used for the production of electrical energy, so is the reason they are not considered batteries because they do not use stored reactant? Or is it because fuel cells are not portable?

Fuel cells can, in fact, be portable: though (as far as I am concerned), not to the extent of modern-day batteries. The reason fuel cells cannot be classified as batteries is due to their lack of stored reactant.

Also, do we need to understand much about all the specific examples of cells (button cells, hydrogen-oxygen, alkaline, dry etc?)

No. These are helpful to peruse, though unnecessary in reference to the study design.

But aren’t fuel cells a type of galvanic cell?

Fuel cells act as galvanic cells (as mentioned in the previous comment). The VCAA was likely referring to a comparison between general fuel cells and standard galvanic cells that are constructed with stored reactant (i.e. batteries), though, I must admit, this dotpoint is quite misleading.

[TheAspiringDoc]

Ok this is really starting to make a lot of sense!

Still confused on this though:

Fuel cells are galvanic cells when undergoing discharge.

Don’t fuel cells only ever undergo discharge?

The VCAA was likely referring to a comparison between conventional fuel cells and galvanic cells that are constructed with stored reactant, though, I must admit, this dotpoint is quite misleading.

Do you mean, “ a comparison between fuel cells and conventional _{(I.e., non-fuel)} galvanic cells _{(e.g. batteries)}”

[TheBigC]

Ok this is really starting to make a lot of sense!

Still confused on this though:
Don’t fuel cells only ever undergo discharge?
Do you mean, “ a comparison between fuel cells and conventional _{(I.e., non-fuel)} galvanic cells _{(e.g. batteries)}”

LOL. Sorry for the first point. You're right - fuels cells only ever undergo discharge. Massive typo there. I will edit that out.

For the second point, I meant what I said, though what you said is a better sentence structure (apologies for my poor wording in the subsequent response).

(Note: I will edit my previous response and fix these errors)

EDIT: The best wording for the second point would have been:

"The VCAA was likely referring to a comparison between general fuel cells and standard galvanic cells that are constructed with stored reactant (i.e. batteries)..."

[TheAspiringDoc]

Thanks so much! Super clear now