SODIUM-ION

Lithium's cheaper cousin

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Abundant

Sodium comes from salt and soda ash, everywhere and cheap

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Cold-tolerant

Good power at low temperatures

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Lower energy

About 100–160 Wh/kg, similar to LFP's lower end

Sodium-ion trades some energy for cheap, abundant materials.

HOW IT DIFFERS

Same idea, new materials

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Anode Hard carbon: sodium doesn't fit well into graphite

Cathode Layered oxides, Prussian blue analogues or polyanion phosphates

Foils Aluminium on both sides, since sodium doesn't alloy with it

0 V shipping Cells can be fully discharged for safe transport

Swapping copper for aluminium also cuts cost.

MATCH THE JOB

Which chemistry fits?

Cost, weight, lifetime and size decide which chemistry wins each job.

There's no single best battery.

LITHIUM–SULFUR

Light, but leaky

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Sulfur is cheap and stores a lot of charge, about 1,675 mAh/g in theory, so Li–S cells promise very high energy per kilogram. The problem is the polysulfide shuttle: intermediate sulfur compounds dissolve, drift to the anode and eat capacity.

Li–S is promising for drones and aircraft where weight is everything.

FLOW BATTERIES

Energy in tanks

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Tanks

Two liquid electrolytes, often vanadium, stored in tanks

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Stack

Pumped through a cell stack where the reactions happen

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Scales separately

Bigger tanks for more hours, bigger stack for more power

Heavy and bulky, but long-lived: built for the grid, not for cars.

UNIT 19 STUDY COMPLETE

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Ready for the Fab Challenge?

You've met the main challengers to lithium-ion and seen the jobs each one could win.