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Charles2076Chen
New Contributor
‎03-19-2024 08:11 PM

Why is the open circuit voltage of the lithium - carbon fluoride battery rated at 4.57 volts?

I had just recently started doing my research into lithium - carbon fluoride (Li-CFx) batteries. It had just caught my attention because the standard reduction potential of lithium and fluorine are at the very opposite end of the spectrum (-3.04 volts for lithium and +2.87 volts for fluorine). So I expect the lithium fluoride battery to have the highest voltage possible for an electrochemical battery cell (3.04 + 2.87 = 5.91). But I have read on article about the Li-CFx battery saying that the theoretical open-circuit voltage for such a battery is 4.57 volts (1.34 volts less than the voltage difference potential between lithium and fluorine. So, my question is this, if the voltage of the Li-CFx battery depends on the reduction potential difference between lithium and fluorine, why is the theoretical open-circuit voltage for the battery 4.57 volts instead of 5.91 volts?

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ryan1969
New Contributor
a month ago

Re: Why is the open circuit voltage of the lithium - carbon fluoride battery rated at 4.57 volts?

@Charles2076Chengm-socrates wrote:

I had just recently started doing my research into lithium - carbon fluoride (Li-CFx) batteries. It had just caught my attention because the standard reduction potential of lithium and fluorine are at the very opposite end of the spectrum (-3.04 volts for lithium and +2.87 volts for fluorine). So I expect the lithium fluoride battery to have the highest voltage possible for an electrochemical battery cell (3.04 + 2.87 = 5.91). But I have read on article about the Li-CFx battery saying that the theoretical open-circuit voltage for such a battery is 4.57 volts (1.34 volts less than the voltage difference potential between lithium and fluorine. So, my question is this, if the voltage of the Li-CFx battery depends on the reduction potential difference between lithium and fluorine, why is the theoretical open-circuit voltage for the battery 4.57 volts instead of 5.91 volts?

Hello, @Charles2076Chen 

 

I can see your query and I give you the best way to solve your query please see below and follow the step-by-step information.

The open-circuit voltage (OCV) of a lithium-carbon fluoride (Li-CFx) battery is determined not only by the standard reduction potentials of lithium and fluorine but also by the actual electrochemical reactions and the materials used in the battery. The theoretical OCV of 4.57 volts, rather than the sum of the standard reduction potentials (5.91 volts), can be attributed to several factors:

 

  • The carbon fluoride used in the cathode is not pure fluorine; its electrochemical potential is different from elemental fluorine.
  • The actual voltage is influenced by the kinetics of the electrochemical reactions occurring in the battery.
  • The complete reaction in a Li-CFx battery involves the formation of lithium fluoride (LiF) and carbon, and the thermodynamics of this reaction set the OCV.
  • Internal resistance and other inefficiencies within the battery can lower the OCV from the theoretical maximum.

The discrepancy between the expected voltage based on standard reduction potentials and the actual OCV is due to these practical considerations in battery design and operation.

The OCV is a reflection of the energy difference between the reactants and products in the specific battery chemistry, which in the case of Li-CFx, results in a lower voltage than the sum of the individual potentials of lithium and fluorine.

 

 

Best Regard,
ryan1969

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