Impedance

Example

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Use in Lemonergy

Use consistent units and cell/pack basis.

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Electrochemical impedance spectroscopy

Measuring a cell’s impedance across a range of frequencies, from kilohertz to millihertz, with a small alternating signal. The spectrum separates ohmic, interface and diffusion processes by their time scale and is read on a Nyquist plot.

Internal resistance

The resistance a cell presents to current, from its foils, electrolyte, interfaces and the reactions themselves. It converts part of the delivered energy into heat, sets the voltage drop under load, and rises as the cell ages; a large automotive cell has about a milliohm, a small cylindrical cell tens.

Nyquist plot

The usual display of an impedance spectrum: negative imaginary part against real part, one point per frequency. Reading left to right, the ohmic intercept, one or two semicircles for interfaces and a diffusion tail each tell a different story about the cell.

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. The International System of Units (SI), 9th edition

   Bureau International des Poids et Mesures · 2026

   Topic background · Definitions of SI units and coherent derived units; 2026 revision.