Table 1.
Comparison of a few KPIs for a 2032 lab scale Li metal coin cell (1-10 mAh) with a commercial lithium-ion cell used in a Volkswagen ID.3 electric car195
| KPI | Lab-scale Li metal coin cell (1-10 mAh) | Automotive Li-ion pouch cell (78 Ah) |
|---|---|---|
| Pos. el. areal capacity (mAh cm−2) | «2 | 5.02 |
| Neg. el. areal capacity (mAh cm−2) | »20 | 5.23 |
| N/P ratio | >10 | 1.04 |
| Electrolyte loading (g Ah−1) | »30 | 1 |
| Pos. el. coating thickness (µm) | <60 µm | 87.3 |
| Pos. el. porosity | »40% | 22% |
The numbers for the 2032 coin cell are reported as an example, and similar values are discussed in the literature19. For this example, we consider a coin cell with a discharge capacity of up to 4 mAh, uncalendered electrodes’ with a diameter of 1.6 cm, 100 µm thick lithium foil, and 100 µL of electrolyte. The greater/less-than symbols are used to stress that several examples of experiments deviate even more from these values. Values such as electrode coating thickness and porosity are not often reported, but constitute a key metric that can mask battery rate capability and lifetime19. The values reported in the table are for a single automotive cell. Values can vary depending on teardown methodology and actual cell design105,196.