Influence of adsorbed species on the electronic transport in nanocomposites materials for lithium batteries

J.-C. Badot, K.A. Seid, O. Dubrunfaut, S. Levasseur, D. Guyomard, B. Lestriez
CNRS, FR

Keywords: nanocomposites, dielectric spectroscopy, electronic transport, lithium batteries

Summary:

The broadband dielectric spectroscopy (BDS) technique (40 to 10 GHz) is used here to measure the electronic transport across all observed size scales of composite materials for lithium batteries containing each an active material (e.g. carbon-coated LiFePO4) and a polymeric binder. Since all the polarizations at different scales are additive owing to their vectorial character, their contributions (relaxations) can thus be evidenced by a decomposition procedure of the Nyquist plots.Data acquisitions as function of temperature were also carried out, in order to determine the activation energies of the conductivity and relaxation frequencies at the different scales of the materials architectures. The influence of the binder (sodium-carboxymethylcellulose) on the coating conductivity and electron hopping has been evidenced. These later parameters rise with the binder volume fraction. This work opens up new prospects for a more fundamental understanding and description of the interactions within nanocomposite materials for lithium batteries. It will permit a more rational optimization of the electronic transport in order to improve the conductivity and thus the rate performance of the composite electrode.