Getting to the bottom of the lithium amount in EV battery is the difference between a whiteboard calculation and current production systems. There are 2 different figures around – about 50 to 60kg per 70kWh battery and 5 to 7kg of elemental Li. Why the differences? This makes a huge impact on the figures used by mining companies of lithium, lithium for Gigafactories and is there enough lithium?
Lithium is in 3 forms.
- Lithium elemental Li with atomic mass of 6.94 u
- Lithium carbonate Li2CO3 or commonly called LCE (99.95% pure lithium carbonate equivalent) and used in lithium nickel ion batteries (with or without cobalt). Li is 18.7% by atomic number
- Lithium hydroxide LiOH – used in Lithium Phosphate batteries (LiFeP04). Molar mass of LiFeP04 is 157.7 and Li molar mass is 4.3%
We have to understand that in the cathode of the battery, the only thing important is that lithium is stripped out of the carbonate/hydroxide and it is only Li that provides the energy.
Lithium amount in EV battery by Type
|Measure||Lithium-Ion (Nickel)||Lithium-Ion Phosphate Battery|
|Normal Battery Size||70kWhr||100kWhr|
|Energy Density||Li2CO3 = 220mAh/g||LiFeP04 = 160mAh/g|
|Energy Capacity Weight||816Wh/kg||512Wh/kg|
|Lithium as %||7%||4.3%|
|Amount of Lithium (kg)||5.6kg||5.7kg|
|Current Amount of LCE||60kg||130kg|
Losses in Production
Efficiencies of the refining process are also less transparent. Lithium is about 1% in rocks, concentrated to 6% spodumene (at a 70% recovery) and then refined to 99.95% purity (unknown) for batteries.
Improvement Over Time
There are multiple steps in the process. The use of excess lithium has not been eliminated in NCA or LFP, then there are yield issues (although these are now being recycled back into new batteries.
Battery Cathodes and Anode Types
Existing LFP, NMC, and NCA batteries all require graphite, but current graphite prices are about $1200, but lithium has reached over $60,000. Batteries require both cathodes and anodes.