Stralsund University of Applied Sciences

Question

Asked 12th Apr, 2017

# How to calculate Coulombic efficiency from Lithium-Sulfur battery measurements?

I am measuring charge-discharge capacity of Li-S battery and I need to measure the Coulombic efficiency too.

## Most recent answer

Fakiha Heakal in this formula what is the value of C=rate while calculating the ratio? should it be the same for both cases and if yes then what rate should be chosen?

## Popular answers (1)

Great Wall Motors

(Capacity discharged / capacity charged) x 100.

8 Recommendations

## All Answers (21)

University of Texas at Austin

Coulombic efficiency of any battery is the ratio of charge output to charge input i.e. Discharge capacity/charge capacity.

Due to shuttle effect in Li-S batteries, efficiency can be much less than 100%. This shows severe polysulfide shuttle during charge.

5 Recommendations

J. Heyrovsky Institute of Physical Chemistry

Thank you very much @Claudiu and @Amruth for your kind information.

University College Cork

charge discharge are confusing terms for the community. better use charge obtained in de_lithiation / charge provided in lithiation x 100

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Dr. APJ Abdual Kalam Missile Complex (RCI)/DRDO

Coulombic efficiency of any battery (nC)=Q Discharge/Q Charge x100. General the nC is always less than 100 for any battery, more over for secondary battery nC is decrease as no of cycle increases.

Dear A. Bhargav and C. Bucur, you wrote that Coulombic efficiency of any battery is the ratio of charge output to charge input i.e. Discharge capacity/charge capacity.

and (Capacity discharged / capacity charged) x 100 by you respectively. Both are correct because efficiency is equal to out/input, i agreed to both, my question is that, i saw many paper on Li ion battery in which, during 1st cycle, the discharge capacity is always greater than charge capacity and hence when we calculate the coulombic efficiency by using above equations, the result will be more than 100 % which is not correct, in some papers, the authors used the same equations but their results are according to reverse equations means charge capacity/discharge capacity? what is this, please comments, and solve the problem

Central Electrochemical Research Institute

If you have done first discharge

*vs*lithium metal (anode) to calculate Coulombic efficiency, initial charge capacity/initial discharge capacity X 100. If you have done first charge means (cathode) above equation is reverse.Thanks a lot Mani Vellaisamy, in was also thinking the same but one was replying me, and hence i could not confirm my thinking, today you wet my thinking and confirm it, i am this one can get the same result, Once again thanks

1 Recommendation

University of North Texas

Coulombic Efficiency (CE %) is the ratio of discharge capacity (mAh/g) to charge capacity (mAh/g) multiplied by 100. In Li-S battery based on liquid electrolyte, if CE is above 97%, it is considered acceptable.

The University of Manchester

I want to ask, the 97% is considered acceptable for which cycle, the first? Or after that?

University of North Texas

If the capacity retention is very good, the charge/discharge capacity remains almost same for many cycles. If the retention rate is poor, the capacity decreases on both charge/discharge cycles proportionately and hence the CE would still remain in high 90s.

1 Recommendation

Indian Institute of Technology Bombay

Pashupati R Adhikari How do we find the discharge and charge capacity for a battery? How do these two differ?

McGill University

I have read some articles that discharge capacity is higher than charge capacity. Now, how to calculate CE?

Example:

The University of Manchester

Amir Esfahani It is a half cell configuration in this paper (use a Li metal as the counter electrode). The author mentioned that the discharge capacity of the anode refers to the lithiation in this paper (It is true for anode half cell).

To calculate CE, use (delithiation capacity / lithiation capacity) * 100.

Cairo University

Generally, the Coulombic efficiency (CE)of a battery is the percentage ratio between the (discharging capacity/charging capacity) × 100. If the voltage for both discharging and chrging processes is the same, CE would be equal to the ratio of discharging and charging times * 100. CE values would be acceptable if they are in the range of 90% or higher than 90%.

Stralsund University of Applied Sciences

Fakiha Heakal in this formula what is the value of C=rate while calculating the ratio? should it be the same for both cases and if yes then what rate should be chosen?

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