How Carbon Nano-Onions Store Energy

A single nano-onion — smaller than a virus — stores energy four different ways simultaneously. Click each mechanism below, or press Play to watch them all in sequence.

OUTER SHELL MIDDLE SHELL INNER SHELL HOLLOW CORE gap between shells IONS SLIP BETWEEN THE LAYERS CHARGE CLINGS TO THE OUTER SURFACE EXTRA STORAGE INSIDE THE HOLLOW CORE HOLLOW CORE ABSORBS SWELLING — NO CRACKING
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Intercalation
Ions from the battery's liquid electrolyte slide into the tiny gaps between each shell of the nano-onion — like sliding cards between pages of a book. The nano-onion's gaps are slightly wider than graphite's, so it can accept larger ions like sodium and potassium that graphite simply cannot fit.
This is how batteries store energy
Surface Adsorption
Charged particles cling to the outer surface of each shell — like static electricity holding a balloon to a wall. This is extremely fast and is the mechanism that powers supercapacitors. The round shape means every part of the surface is accessible, unlike flat sheets that stack and block each other.
This is how capacitors store energy
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Internal Storage
The hollow centre of the nano-onion provides additional interior surface area where ions can accumulate — bonus storage space that simply doesn't exist in solid particles. It's like having a room inside a room: the outer walls store energy, and the inner walls do too.
Bonus capacity from the hollow design
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Void Buffering
When ions pack in during charging, materials swell — and solid particles crack under the strain. The hollow core acts like a built-in shock absorber: swelling pushes inward into empty space instead of outward against neighbouring material. This is why nano-onions last tens of thousands of cycles without degrading.
This is why the material lasts so long
Intercalation (between shells)
Surface adsorption (outer surface)
Internal storage (inside hollow)
Void buffering (absorbs swelling)