I performed Quasi-OCV measurement at 0.25A and 23°C (with climate chamber) on NCA cell (Manufacturer: EAS Batteries GmbH) using Basytec XCTS test system. The test was performed in the sequence of (necessary pre-steps...), discharge step, relaxation time of 1.5 hrs and charge step, (necessary post-steps...). As you can see in the image attached below, the charge capacity obtained was surprisingly quiet low (almost third to quarter of) compare to discharge capacity. So, I tried to understand it by performing a reference test at 1C-rate (i.e. 10A) to see first if it shows some kind of aging and if so, then further inspection using EIS measurement. However, I found out that the discharge curve at 1C-rate from the reference test is completely identical to the last reference test that I performed before Quasi-OCV test. The curves are over-lapping each other.

So, please can anyone give me a suggestion or a hint what could have gone wrong or a way to find out the cause of the problem?

NOTE: The entire test was done in the single run. There was no interruption during the test or change in connections.

Thank you everyone for your time and suggestions!