  Two dimensional materials show great potential for use in battery electrodes
and are believed to be particularly promising for high-rate applications.
However, there does not seem to be much hard evidence for the superior
rate-performance of 2D materials compared to non-2D materials. To examine this
point, we have analyzed published rate-performance data for a wide range of 2D
materials as well as non-2D materials for comparison. For each capacity-rate
curve we extract parameters which quantify performance which can then be
analyzed using a simple mechanistic model. Contrary to expectations, by
comparing a previously-proposed figure of merit, we find 2D-based electrodes to
be on average ~40 times poorer in terms of rate performance than non-2D
materials. This is not due to differences in solid-state diffusion times which
were similarly distributed for 2D and non-2D materials. In fact, we found the
main difference between 2D and non-2D materials to be that ion mobility within
the electrolyte-filled pores of the electrodes to be significantly lower for 2D
materials, a situation which we attribute to their high aspect ratios.
