Cycle Life and Energy Density

Is there a relationship between Cycle Life and Energy Density?

This is a mix of chemistry, age, size and manufacturers. Hence a lot of other information mixed into this, but there is a trend.

plot of cell cycle life versus volumetric energy density

Adding trendlines might be generous, but what we can see is that low energy density cells range in cycle life from 1,000 cycles to 16,000 cycles. However, we don’t see high cycle life and high energy density.

This post has been built based on the support and sponsorship from: Thermo Fisher ScientificEatron TechnologiesAbout:Energy and Quarto Technical Services.

The question is could we think of any reasoning for this?

  • high energy density means thicker active coatings
    • higher resistance => more heating
    • more mechanical stress => more fractures

Power versus Energy Cells

Comparing power versus energy cells we see there are some fundamental differences. A high energy cell will have better volumetric and gravimetric energy density at the expense of the ability to deliver a high current. The power cell will have a low internal resistance and will be optimised to deliver current over energy density.

  • high energy density => increased cell expansion
    • anodes with silicon => increased energy density => increased expansion
  • more compact cells => higher current density
    • possibility of uneven local heating => ageing

Overall, the data shows a trend and thinking through the physics there is a logic that higher energy density leads to lower cycle life. Now we need more data to see if we can extract more features.

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