The dV/dQ curve

dV/dQ curve is an analytical tool that can analyze the loss of active lithium in lithium ion batteries. The peaks in the dV/dQ curve mainly reflect the phase transition of the active substances in the process of lithium immobilization and lithium removal.

dV/dQ curve mainly reflects the phase change of positive and negative active substances in the charging and discharging process. According to the data, we can find out the phase transition corresponding to different characteristic peaks in the dV/dQ curve, and then according to the variation trend of the dV/dQ curve in the cycle or in the storage process, we can qualitatively infer the cause of the reversible capacity loss of lithium ion battery, providing a reference for the design of lithium ion battery.

The dQ/dV curve

The physical meaning of a dQ/dV curve is the volume of a material per unit voltage. We all know that lithium ion batteries have a voltage platform for both anode and cathode materials. A high negative capacity on the voltage platform means that there is a lot of capacity in a very small voltage fluctuation range, so it is a characteristic peak on the dQ/dV curve. Usually we think of each peak on the dQ/dV curve as representing an electrochemical reaction. Because the reaction potentials of different materials are different, the positions and heights of peaks in the dQ/dV curve will also be different.

How to operate in TOB cell tester system

1. dQ/dV curve setting

2. Select the current display curve

3. View the curve to see if achieved the desired effect

4. Click the record-layer expand/collapse button

5. Data copy

6. Select the cycle range to copy