On the correlation between electrode expansion and cycling stability of graphite/Si electrodes for Li-ion batteries

A comparative study of the expansion/shrinking properties of graphite/Si electrodes with different formulations is carried out by means of electrochemical in situ dilatometry. The dilatometry reveals the impact of graphite particle size and aspect ratio as well as the binder type on the cycle life of the studied electrode formulations. Two binders, polyvinylidene fluoride (PDVF) and crosslinked carboxymethyl cellulose - polyacrylic acid (CMC/PAA) and two graphites of different particle size and aspect ratios, TIMREX® KS6 and SLP30, are used in composite electrodes and are tested in lithium half cells. The specific charge of electrodes containing Si nanoparticles and PVDF binder declines rapidly in the first cycles. The CMC/PAA based electrodes containing Si exhibit improved cycling stability and better management of dimensional changes occurring during graphite and Si (de)lithiation.