Twisted carbon nanotubes can store three times more energy per unit mass than advanced lithium-ion batteries

https://phys.org/news/2024-07-carbon-nanotubes-significantly-energy-storage.html

"can also store 15,000X more energy per unit mass than steel springs... 100X stronger than steel... manufactured carbon nanotube ropes by twisting tubes into single thread, then coating them with different substances increasing strength/ flexibility... tested by twisting them up, measuring energy released as ropes unwound, selected the best... stored energy consistent/ accessible at temperatures from -76 to +212 °F... safer for the human body than those used in batteries... medical implants, sensors"