Impedance rise

Example

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Use in Lemonergy

Separate mechanisms, observations and fitted models.

This is a reference concept. No executable Lemonergy block has been verified for this term.

Learn it in Lesson 4 · Battery aging →

Connected concepts

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Cathode–electrolyte interphase

The counterpart of the SEI on the positive electrode: a thin layer of electrolyte oxidation products on the oxide surface. It is thinner and less stable than the SEI, and its growth contributes to impedance rise, especially at high voltage.

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.

Solid–electrolyte interphase

A film of electrolyte reaction products on the negative-electrode particles — graphite, and also silicon or lithium metal. It protects the electrode from further reaction but grows slowly for the whole life of the cell, consuming cyclable lithium.

State of health

A summary of how far a cell has aged, often expressed through remaining capacity or increased resistance compared with when it was new. By convention a cell has reached end of life at 80 % of its rated capacity.

State of power

The maximum charge or discharge power a battery can deliver for the next few seconds without breaking a voltage, current or temperature limit. The BMS recomputes it continuously from SOC, temperature and resistance and sends it to the motor controller.

References & further reading

Technical references

1. Lithium ion battery degradation: what you need to know

   Physical Chemistry Chemical Physics · 2021

   Technical reference · Degradation mechanisms, modes, operational effects and their interactions.