A method for fast estimation of the rate-limiting step in lithium-ion batteries

Transport of charge in electrodes for lithium-ion batteries is complex. For accurate description one needs to use a multilevel approach which addresses processes on different scales - from the ones occurring inside active nanoparticles to those governing the transport in composite electrodes or in separators of sub-millimeter thickness. Here we attempt an approximation that allows for a fast estimation of the rate-limiting step in given electrochemical cell. Despite thoroughly simplified description of transport, the method gives suprisingly good prediction of polarisation resistance as a function of charge/discharge rate and of the electrode thickness. The method might be helpful for fast evaluation of new materials or new electrode designs in everyday laboratory testing.