How close do real batteries, flow cells and hydrogen tanks get to their first-principles ceilings?
research/energy-practical
How close do real batteries, flow cells and hydrogen tanks get to their first-principles ceilings? A Panasonic NCR18650B cell reaches 0.64 of the Li-ion reactant ceiling (243 of 380 Wh/kg), LiFePO4 0.25–0.45, lead-acid 0.21–0.24; DOE's projected 700 bar H2 system is 5.1% hydrogen by mass against 24–41% ideal. Small sourced dataset, primary and secondary rows marked. Second project of track 16.
What it found
A small sourced dataset set beside the ceilings of energy-density. A Panasonic NCR18650B cell (data sheet) stores 243 Wh/kg, 0.64 of the 380 Wh/kg graphite/LiCoO2 reactants could release; commercial LiFePO4 reaches 0.25–0.45 and lead-acid 0.21–0.24. DOE’s projected 700 bar hydrogen system (1.71 kWh/kg) is 5.1% hydrogen by mass against 23.8–41.3% for an ideal carbon-fibre sphere. Round-trip efficiency runs from 50% (compressed air) to 85% (advanced lead-acid). Limited: five families, five of seven data rows read through secondary pages, gap not split into causes.
A figure from its own output
Paper, code and results
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Produced with AI assistance (Claude). Results are from the code in this repository and are simulated or stylised unless the abstract says otherwise; nothing here implies affiliation with or endorsement by any lab, researcher or company cited. MIT licensed.