https://en.wikipedia.org/wiki/Superconducting_magnetic_energy_storage https://en.wikipedia.org/wiki/Superconducting_magnetic_energ... https://en.wikipedia.org/

https://en.wikipedia.org/wiki/Superconducting_magnetic_energy_storage https://en.wikipedia.org/wiki/Superconducting_magnetic_energ... https://en.wikipedia.org/wiki/Lithium-ion_battery https://en.wikipedia.org/wiki/Lithium-ion_battery 1–10 Wh/kg for superconductors, 100–265 Wh/kg for batteries.