Hi everyone,
I have a questions regarding to the CC-CV mode of Lithium ion batteries. Normally, from the other literatures, the formation will be carried out with 0.1C constant current (CC mode) then 0.05C in CV mode. However, if I want to change the formation current to 0.05C in CC mode, how should I change the value of CV mode according to the change in CC mode? In the other words, is there any correlation between the value of CC and CV mode (for example, increasing CC value, then we need to increase the CV value and in contrast).
Thanks in advanced.
As far as I know, full charge is reached when the current decreases to between 3 and 5 percent of the Ah rating. But it is true in case of cycling test. How about formation process?
Hello Hieu,
in CC-CV mode of battery testing you should consider some parameters. As you may know, CC mode need a cut-off to terminate the test. To do so, the cut-off would be the highest potential that material can safely work. In CV you need to determine a minimum for charging current as the cut-off. Here is a relationship between the c-rate that you are working at and the minimum current for cut-off. As far as I know, if you are working in 0.1 C, the current cut-off for CV mode should be in the range of 50% of your current which is exert to the cell in CC mode. so in 1 C, the cut-off for CV mode would be the current in the rang of 0.5 C and so on.
I have to say, based on my knowledge, formation has a fixed process, but the cut-off current will be determined based on above mentioned rule.
Regards
To address this issue, I guess that a higher C-rate results in a greater distance from equilibrium because of multiple reasons (IR drop and polarizations), hence increasing c-rate typically means reaching the upper voltage limit in a lower state of charge. As a result, a greater proportion of charging will occur in CV stage, which is lower than the nominal c-rate. In addition to c-rate, the chemistry of the active material, particle size, the percentage of conductive additive and binder, and thickness can play significant parts in influencing the ratio of CC to CV charging mode.
- Badges
- Science topic
- Similar topics
- Psychology
- Emotional Psychology
- Happiness