Nickel–metal hydride battery

Example

Use in Lemonergy

Do not carry lithium-ion assumptions into every chemistry.

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Connected concepts

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Bipolar battery

A battery built from bipolar electrodes: one shared current collector carries positive material on one face and negative material on the other, so stacked layers form cells in series inside one housing. Current flows straight through the stack instead of through tabs and busbars, cutting resistance and parts; Toyota’s 2021 Aqua hybrid used a bipolar nickel–metal hydride pack.

Hybrid and plug-in hybrid vehicle

A hybrid pairs an engine with a small battery, around 1 kWh, that is cycled hard for power rather than energy; a plug-in hybrid adds a 10–25 kWh pack that can be charged from the grid for electric-only driving. Their cells are designed for power and life rather than energy.

Memory effect

A loss of usable capacity in nickel–cadmium cells repeatedly recharged from the same partial state. Lithium-ion cells do not show it in any practical sense, though LFP has a small related voltage memory.

Nickel–hydrogen battery

A cell pairing a nickel oxyhydroxide positive with hydrogen gas on a platinum-catalysed electrode, sealed in a pressure vessel whose pressure tracks state of charge. With no negative electrode to wear out it lasts tens of thousands of cycles, powering satellites, the Hubble Space Telescope and, until lithium-ion replaced it, the International Space Station.

Specific energy

Stored energy per unit mass, in watt-hours per kilogram. Commercial lithium-ion cells range from about 160 Wh/kg for LFP to around 270 Wh/kg for high-nickel chemistries; at pack level the figure drops by a quarter or more.

References & further reading

Further reading on this topic

These sources provide broader context; they are not presented as citations for every statement in this entry.

1. Promise and reality of post-lithium-ion batteries with high energy densities

   Jang Wook Choi, Doron Aurbach · Nature Reviews Materials · 2016

   Topic background · Post-lithium-ion materials and battery concepts, including practical cell-level limitations; historical 2016 perspective.

2. DOE/EPRI 2013 Electricity Storage Handbook in Collaboration with NRECA

   Sandia National Laboratories · 2013

   Topic background · Storage technologies and grid services. The publisher notes that its historical cost and deployment figures are outdated.