Influence of adsorbed polar molecules on the electronic transport in a composite material Li1.1V3O8–PMMA for lithium batteries

Abstract

The broadband dielectric spectroscopy (BDS) technique (40 to 10(10) Hz) is used here to measure the electronic transport across all observed size scales of a Li(1.1)V(3)O(8)-polymer-gel composite material for lithium batteries. Different electrical relaxations are evidenced, resulting from the polarizations at the different scales of the architecture: (i) atomic lattice (small-polaron hopping), (ii) particles, (iii) clusters of particles, and finally (iv) sample-current collector interface. A very good agreement with dc-conductivity measurements on a single macro-crystal [M. Onoda and I. Amemiya, J. Phys.: Condens. Matter, 2003, 15, 3079.] shows that the BDS technique does allow probing the bulk (intrinsic) electrical properties of a material in the form of a network of particles separated by boundaries in a composite. Moreover, this study highlights a lowering of the surface electronic conductivity of Li(1.1)V(3)O(8) particles upon adsorption of polar ethylene carbonate (EC) and propylene carbonate (PC) that trap surface polarons. This result is meaningful as EC and PC are typical constituents of a liquid electrolyte of lithium batteries. It is thus suggested that interactions between active material particles and the liquid electrolyte play a role in the electronic transport within composite electrodes used in a lithium battery.

Multiscale electronic transport in Li1+xNi1/3−uCo1/3−vMn1/3−wO2: a broadband dielectric study from 40 Hz to 10 GHz

“…1, since they are constituted of clusters (aggregates) of particles and particles separated by resistive and capacitive barriers that limit the charge diffusion in the whole material. [17][18][19][20][21][22] Moreover the electronic connectivity is reduced because the electrode materials are porous, which diminishes contact surface between the clusters and between the particles inside the clusters.…”

“…Moreover the electronic connectivity is reduced because the electrode materials are porous which diminishes contact surface between the clusters and between the particles inside the clusters. [17][18][19][20][21][22] It has been previously shown that Broadband Dielectric Spectroscopy (BDS) is much more suitable to describe the electronic transport in electrode materials for lithium batteries. The response of a material submitted to a timedependent electric field can be described by the time-dependent current density or by the time-dependent polarization.…”

Redirected charge transport arising from diazonium grafting of carbon coated LiFePO4

“…Recently, a similar phenomenon was reported on laminar silica-polymer composite dielectrics 52 and Li 1.1 V 3 O 8 particles. 53 Surprisingly enough, in the case of LFPC-EB-2L (Fig. 6), although the sample conductivity is much lower, it appears nearly independent of temperature.…”

Interest in broadband dielectric spectroscopy to study the electronic transport in materials for lithium batteries

“…The broadband dielectric spectroscopy (hereafter called BDS) allows the study of the electronic conductivity of a composite electrode at all the scales of its architecture (from interatomic distances to macroscopic lengths) as function of the temperature usually between 200 and 400 K [1][2][3][4][5]. This technique thus allows the clarification of the charge transport mechanisms and the origin of the limitations in these mechanisms, depending on the composition, processing and morphology of the composite electrode.…”

“…In the first case, the influence of surface ageing and degradation is considered and in the second one, the influence of a carbon coating is analysed. Moreover, the nature of the electronic transfer in composite electrode based on the Li1.1V3O8 active material is investigated [4]. Permittivity and conductivity measurements have been recorded in a wide frequency range from 10 Hz to 10 GHz in the temperature range 200 to 300 K.…”