LIB Cathodes

Operating voltage

average V at which Li is extracted

Specific capacity

energy per unit weight, usually in mAh/g

Energy density

Wh/litre

Specific energy

Wh/kg

What voltages to Li cathodes sit at

v electronegative = high voltage

LiCoO2

LTMO, Li+ extracted oxidising Co from 3+-4+, irreversible structural changes below x=0.5, Li removal causes O2- ions to repel causing c axis expansion, Co is toxic, rare and has immoral supply chain

NMC

replace some Co with Ni and Mn, Ni migrates into vacant Li sites reducing capacity (nanostructuring can help this), Mn rich NMC has shown up to 280mAh/g, layered oxide structure thermally unstable at high T releasing O2 in a self sustaining reaction (worse with more Ni)

LFP

olivine structure with strong PO bond so no O2 release, Li inserts with minimal volume change, 4-5x longer cycle life (due to dimensional stability), lower V (3.3V vs 3.7 of NMC) = less fire risk but lower E density, 170mAh/g, Fe and P abundant, cheap and nontoxic