Cell Gravimetric Energy Density with the units Wh/kg is a key cell metric. The optimum metric is a high Wh/kg. Hence:
- High nominal voltage
- High Ah capacity
- Low mass
Perhaps the simplest of the battery metrics as the capacity of the cell is fairly easy to measure and the mass is just a set of scales.
The only note of caution is the discharge rate at which the cell Ah capacity has been measured. For automotive C/5 to C/3 is quite representative for a range test. However, for a phone or laptop C/10 is perhaps closer. Most cell capacities are quoted by manufacturers at C/10.
- 325 Wh/kg Lithium Sulphur (ALISE 2018)
- 271 Wh/kg Panasonic NCR2170‑M
- 263 Wh/kg LG Chem M50 21700
- 260 Wh/kg Panasonic NCA 21700 (Tesla Model 3 2019)
- 241 Wh/kg Murata 18650VTC6 (Formula E 2019-21)
- 240 Wh/kg Panasonic NCA 1
- 169 Wh/kg XALT 53Ah HE NMC (Formula E 2014-18)
- 160 Wh/kg Lithium Iron Phosphate battery
- 100-150 Wh/kg Sodium Ion battery
- 70–100 Wh/kg Nickel Metal Hydride (NiMH) battery
- 90 Wh/kg Sodium Nickel Chloride (Zebra) battery
- 80 Wh/kg Sony first ever production lithium ion cell (1991)
- 50-75 Wh/kg Nickel Cadmium (NiCd) battery
- 35-45 Wh/kg Lead Acid battery
We will gradually add more values to this list. If there is a burning omission please contact us (Nigel)
Cell Energy Density Roadmaps
Wh/kg is a key metric that we look at when comparing cells. Looking at production values and adding roadmaps gives you an interesting view as to the future. Is 900Wh/kg credible when production cells have taken 30 years to move from 80Wh/kg to 300Wh/kg?