Ragone plots can be a helpful method to analyze cycling or rate data.
The Ragone plot is a visualization of specific energy vs. specific power. Traditionally, this plot is used to compare across different chemistries, form factors, and designs. However, Ragone plots can also be used to compare the cells across different rates or during cycling.
The above Ragone plot visualizes cells that are charged and discharged at various rates. The advantage of this visualization is that the relationship between energy and power as a function of rate is visually clear, relative to the other cells.
The above Ragone plot visualizes cells as they are cycled 2000 times. The direction of increasing cycling is right to left, because specific energy and power decreases as the cell is cycled. The advantage of this visualization is that it clearly demonstrates the effect of cycling. It also identifies key inflection points where specific power decreases.
Try Plotting It Yourself:
1. Select a test that contains rate data or cycling data
2. Select 'Discharge Energy' on the X axis, and 'Maximum Discharge Power' on the Y axis.
3. Under 'Normalization & Transforms', choose 'Normalize x-Axis' and select your metadata that represents the cell mass. This is likely 'Active Material Mass' or similar.
If you don't have a metadata integration, you can select 'Constant' to represent dividing the energy by mass. For example, to divide by 10kg, you can enter a constant of 0.1.
4. (Optional) Since the sign convention for discharge current is negative, discharge power is reported as a negative value. To see positive values for discharge power, under 'Normalization and Transforms', go to 'Power Transforms', and click 'Invert'.
5. (Optional) Ragone plots are more visually appealing with markers instead of lines. Under 'Formatting', choose 'Element Formatting', then 'Trace Style and Color', and then select 'Marker Only'.
6. Click 'Generate'.
Make Life Easier With Metadata
Instead of entering in a constant numeric value for the cell mass each time, you can conveniently tell Voltaiq to use the cell's mass that is associated with the device.
This is a feature that is enabled by setting up a metadata ingestion so that Voltaiq has each cell's key metadata, such as capacity, active material mass, or loading. Contact us at support@voltaiq.com and we can help you get your metadata ingested!