How do different battery chemistries compare in terms of calendar ageing? When we look at battery lifetime the standard method used by industry has two fundamental test regimes as inputs:
- calendar ageing – where the cells are held at different fixed temperatures and SoC.
- cycle ageing – where the cells are cycled through a complete charge discharge at different fixed temperatures.
This data is then used as inputs to the ageing predictions, a simple summation of these two parts gives the overall ageing model [4].
Here we are focussing on the Calendar Ageing, this is all about how the cell ages just left on a shelf doing nothing.
Dubarry et al [1] have reviewed literature over the last 20 years to piece together the calendar ageing of the most common chemistries to show capacity loss and resistance growth against State of Charge (SoC) and Temperature.
Capacity Loss
- LTO doesn’t suffer capacity loss except at low SOC + high Temperatures.
- LCO shows very high capacity loss at high SOC and above 20°C
- LFP, NCA and NMC all behave similarly with losses being significant above 30°C and increasing with SOC.
Lam et al [2] show calendar ageing that has been acquired over a long term ageing project.
This reinforces the faster ageing of the cells at high SoC and higher temperature.
In this study they held cells at a maximum of 85°C and you can see a very rapid calendar ageing.
Resistance Increase
Increase in the resistance of a cell means an increase in joule heating and a larger voltage drop for a given current demand. Ultimately meaning a lower power capability.
- NMC shows significant increase in resistance with high Temperature and high SOC.
- NCA resistance increase is lower than NMC.
- LFP shows an even lower increase in resistance except at high SOC and high Temperature.
- LTO shows insignificant change in resistance across the SOC and temperature window.
This post has been built based on the support of and sponsorship from: Quarto Technical Services, Eatron Technologies and About:Energy
Lam et al [2] summarise the capacity fade and resistance increase versus chemistry.
Keil et al [3] investigated calendar ageing across the SoC range and the snapshot below shows the results at 10 months and 9 months for the three chemistries.
We see that NMC capacity fades rapidly above 90% SoC and >40°C. NCA resistance increases rapidly above 85% SoC.
All of these studies show similar trends:
- Capacity fade increases with SoC and temperature for NCA, NMC and LFP
- NCA and NMC capacity fade and resistance increases significantly above 85% SoC
However, there are differences:
- Cells used were from different periods in time and cells are on a steep development curve.
- Cells were from a variety of manufacturers.
Hopefully this shows the general trends and also shows the need to gather data on the specific cell that you are working with.
References
- Matthieu Dubarry, Nan Qin, Paul Brooker, Calendar aging of commercial Li-ion cells of different chemistries – A review, Current Opinion in Electrochemistry, Volume 9, 2018, Pages 106-113
- Vivek N. Lam, Xiaofan Cui, Florian Stroebl, Maitri Uppaluri, Simona Onori, William C. Chueh, A decade of insights: Delving into calendar aging trends and implications, Joule, Volume 9, Issue 1, 2025
- Peter Keil, Simon F. Schuster, Jörn Wilhelm, Julian Travi, Andreas Hauser, Ralph C. Karl and Andreas Jossen, Calendar Aging of Lithium-Ion Batteries, 2016 J. Electrochem. Soc. 163 A1872
- T. M. N. Bui, M. Sheikh, T. Q. Dinh, A. Gupta, D. W. Widanalage and J. Marco, “A Study of Reduced Battery Degradation Through State-of-Charge Pre-Conditioning for Vehicle-to-Grid Operations,” in IEEE Access, vol. 9, pp. 155871-155896, 2021