While individual battery cells can charge in under 15 minutes, EV battery packs take much longer to fully charge. There are a number of factors that influence that, including temperature spread across the pack.
Key Factors Limiting Battery Cell Lifetime During Charging
At the cell level, the fastest rate at which a battery cell can charge depends on lithium diffusion and transport processes happening at small scales.
There are two key risk factors when fast charging a cell:
- Temperature:
Heat generated during charging can lead to uneven temperature distributions, causing local degradation within cells. This speeds up capacity loss by accelerating degradation mechanisms. - Lithium Plating:
Fast charging risks the anode voltage falling below 0V, causing lithium plating. This irreversible reaction decreases the battery’s available lithium.
Pack Simulation
Thermal-electrochemical models in Matlab and other simulation software can predict temperature and electrochemical properties to help prevent damage from fast charging in both cells and packs. This enables engineers to get the most value out of battery products.
The simulation shows that at the module and pack level, other variables become important:
- DC charger current limit
- number of cells in parallel
- battery pack nominal voltage (400-volt versus 800-volt)
- intracell and intercell temperature spreads
- intracell and intercell SOC spreads
- non-cell resistance
The full case study walks you through the methods and looks at each of these variables. Specifically temperature differences, can have an important effect in charging rates, so it is paramount that they are considered in battery virtual design and verification workflows.
References:
- Battery Fast Charge with Simscape Battery and About:Energy, Mathworks Technical Articles
About:Energy
A data company that offers software to enhance battery performance throughout its lifetime. Its platform, “The Voltt”, reduces time and costs in developing new electric products for various industries.
Utilizing advanced battery testing methods, this platform facilitates cell selection, benchmarking, and system design.