High energy density requires porous electrode; high power density requires thick electrode.

Also, when a cell is charged slower, the voltage drop due to Cell internal resistance and Cell diffusion voltage component will be lower, thus more energy could be pushed into battery before the charging voltage limit is reached.

One of the Efficiency—performance—safety tradeoffs in batteries.

See also:

• The proportion of cell energy lost to Joule heating is roughly IR/V

References

https://honestenergy.substack.com/p/the-little-ion-that-could