Comparison of NMC and LFP Cell Technology
In this series we will be discussing the difference between NMC and LFP applications. To start we'll compare the difference between NMC and LFP cells for 12 Volt batteries. E1’s low voltage battery management systems are cell technology agnostic, meaning any type of cell can be used with our BMS.
Let’s go through the differences between the two cell technologies.
Operating Voltage
Typically NMC cells operate in a range from 2.5V up to 4.2V whereas LFP cells operate from 2.5V up to 3.65V. Now, these voltage ranges depend on the individual cell supplier, as this is just a generalization, the voltage ranges vary manufacturer to manufacturer.
| Cell Chemistry | Min Cell Voltage | Max Cell Voltage |
|---|---|---|
| LFP | 2.5V | 3.65V |
| NMC | 2.5V | 4.2V |
Energy Density
NMC cells are more energy dense in comparison to LFP. The specific energy of LFP, ranges from 90 Wh/kg to 120 Wh/kg, whereas NMC ranges from 150 Wh/kg to 220 Wh/kg. Most recently, E1 has used Amprius cells with our High Voltage Battery Pack, which exceed 300 Wh/kg at the cell level. You may think, since NMC cells are more energy dense, why not use them for all applications? It’s not that simple. NMC cells are more costly when compared to LFP and are more dangerous if not handled correctly. This is why cell selection is key, based on the application. For example, Tesla utilizes LFP cells for their Standard Pack configuration for the Model 3, whereas the Long Range version uses NMC.
Voltage Curves
Voltage curves vary between LFP and NMC as LFP cells tend to provide a more flat discharge curve. The following is an example of a 50Ah LFP cell discharged at a 1C (50A) rate at various temperatures:
LFP Voltage Curve
If we look at the 25°C curve, you will see a very narrow operating voltage for most of the curve, with the exception of the opposing ends of the graph. In comparison, here is a graph for a 30Ah NMC cell:
NMC Voltage Curve
As you can see, the operating voltage for the NMC cell is wider than the LFP. Because of these differences, you will see LFP cells used in different applications than NMC, and vice versa. For example, 12V application typically use LFP cells as the voltage range of a 4S configuration closely matches that of lead-acid batteries.
Safety
Another factor to consider when comparing the two is safety. LFP cells are typically more safe than NMC cells. An internal short of LFP results in heat generation and smoke, but usually does not result in a burning flame. In contrast, shorting an NMC cell is explosive and results in tremendous burning. Precaution should be used when using batteries in general, and it is important to use various safety mechanisms to prevent a battery fire in the first place. In our HV-BMS-100, a comprehensive faults and warnings system is used to first alert the external system of a potential hazard, followed by opening the contactors to prevent a potential failure.
If you are interested in evaluating our battery solutions, contact us: info@embeddedone.com
About the Author:
Amir Naqui is President of Embedded One with an extensive background in battery technology and electronic development within the automotive, aerospace, marine and consumer electronics industries. You can follow him on LinkedIn for updates on E1 and the battery industry in general.
