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> Li-metal batteries top at around 14 MJ / kg

Do you have a link to back this number? Are these batteries rechargeable? Does the measurement include wiring, cooling, cell connections and overall structure of the battery pack?

For comparison, Tesla's (Li-ion) battery pack energy density is 160 Wh/kg, which is 0.576 MJ/kg:

https://www.pv-magazine.com/2020/02/11/energy-density-advanc...

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At that point you need to consider the whole car. The engine needed to extract energy from that fuel is much bigger in the ICE car. And it also needs cooling, etc.

Comparing just the gas tank to several subsystems of a battery electric vehicle is not really an interesting comparison. The closest comparison at that level is just gas vs just cells.

Overall electric is still lower energy density per weight, but is also far more efficient. The whole Tesla pack has the energy of just a couple gallons of gas but can go 400 miles.

I used that, and actually I may have missed the bit where they explain that "lithium metal as an anode were suggested for future high-energy-density batteries", implying that it's still an immature tech.

https://pubs.rsc.org/en/content/articlelanding/2019/ee/c9ee0...

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