Battery knowledge · Aging and degradation
Cycle aging
Degradation caused by charging and discharging: mechanical strain in the particles, fresh SEI on cracked surfaces and, at high rate or low temperature, lithium plating. It scales with charge throughput and grows with depth of discharge and C-rate. [1]
Example
Capacity loss and resistance growth
At the illustrated endpoint: 80% initial capacity and 140% initial resistance.
Chosen qualitative trends. The exposure axis is not predicted cycles or years.
Explore the graph
Energy capability and power capability can degrade differently.
At the illustrated endpoint: 80% initial capacity and 140% initial resistance.
Capacity ratio = Q_now/Q_initial; resistance ratio = R_now/R_initial
Illustrative model. Chosen qualitative trends. The exposure axis is not predicted cycles or years.
Use in Lemonergy
Design protocol or analysis tool
Repeat charge/discharge
Cycle aging block repeats charge, discharge and rest.
Equation or tool to use
- Repeat
Repeats blocks
Inputs & settings
- count
- Discharge
Removes charge
Inputs & settings
- mode: cc
- a / s
- Rest
Sets zero current
Inputs & settings
- s
- Charge
Adds charge
Inputs & settings
- mode: cc
- a / s
This overview identifies the components to use. Follow the example in Lemonergy for their connections and settings.
- Open Cycle aging block.
- Review currents and rests; compare throughput.
Example. Twenty 50%-depth discharges give ten discharge-equivalent full cycles at fixed nominal capacity.
Observe. Cycle count differs from throughput.
Scheduling cycles does not supply calibrated degradation or physical lifetime evidence.
Open Design → Protocol bench →References & further reading
Technical references
- Lithium ion battery degradation: what you need to know
Physical Chemistry Chemical Physics · 2021
Technical reference · Degradation mechanisms, modes, operational effects and their interactions.