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

Abstract

This work is the first detailed study concerning the multiscale electronic transport and its temperature dependence in the LiNi1/3Co1/3Mn1/3O2 (NMC) family, high-capacity electrode materials for lithium ion batteries. Powders with two different mean cluster sizes (3 μm and 10 μm) but the same particle sizes (0.4 to 1.3 μm) were measured. The detailed formula of the studied compound is Li1.04Ni(2+)0.235Ni(3+)0.09Mn(4+)0.315Co(3+)0.32O2. Different electrical relaxations are evidenced, resulting from the polarizations at the different scales of the powder architecture. When the frequency increases, three dielectric relaxations are detected in the following order due to: (a) space-charge polarization (low-frequency range) owing to the interface between the sample and the conductive metallic layer deposited on it; (b) polarization of NMC clusters (micronic scale) induced by the existence of resistive junctions between them; and (c) polarization of NMC particles (at sub-micronic scale) induced by resistive junctions between them. High interatomic level conductivity of about 20 S m(-1) was evidenced and attributed to the contribution of the extended states and to a Brownian motion of the charge carriers with mean free path similar to the lattice constant. The ratio between sample and local conductivity is more than 10(5). The large conductivity drop of 3 to 4 orders of magnitude is observed from the particle to the cluster scale. A very large number of charge carriers are blocked by the interparticle junctions within the clusters. The conductivity drop from the cluster to the sample scale is comparatively very small, owing to the dense architecture of the NMC sample in which the spherical clusters are very piled up on each other.

Characterization of Electronic and Ionic Transport in Li1-xNi0.33Mn0.33Co0.33O2(NMC333) and Li1-xNi0.50Mn0.20Co0.30O2(NMC523) as a Function of Li Content

“…With respect to electronic conductivity, we know of no published measurements for NMC 333 and NMC 523 compositions. Seid et al 22 reported that the electronic conductivity of Li 1 Thus our objective in this work is to systematically characterize and interpret the transport properties of NMC 333 and NMC 523 . We use additive-free, single phase sintered samples in which the extrinsic effects due to binders, conductive additives, and particle microstructures that may be present in composite electrodes are avoided.…”

“…However, there is surprisingly little, and conflicting, data on the basic transport properties of the NMC family of compounds. [19][20][21][22][23] Wu et al, 19 and Hao 20 measured using the GITT technique the chemical diffusivity of NMC 333 based composite electrodes (e.g., NMC powder combined with polymer binder and carbon additive) as a function of lithium content, and reported results differing by two orders of magnitude from each other. Furthermore, whereas Hao 20 reported that the chemical diffusivity of NMC 333 is nearly independent of lithium content, Wu et al 19 found two orders of magnitude variation of lithium diffusivity with lithium content.…”

Kinetic characteristics up to 4.8 V of layered LiNi1/3Co1/3Mn1/3O2 cathode materials for high voltage lithium-ion batteries

“…While , Seid et al have demonstrated that within NCM material, the clusters of particles bring boundaries, junctions and interfaces. [10,11] This will result in various polarizations ranging from interatomic distances to macroscopic sizes, leading to the conductivity is different in multiscale. The multiscale conductivities should be taken in account when exploring the intrinsic kinetic properties.…”

Effects of microstructure on fracture strength and conductivity of sintered NMC333

“…Alternatively, high temperature processing may have induced a change in the properties of the grain boundaries. For example, the formation of an insulating amorphous film on interparticle boundaries has been observed in previous studies on calcined powder clusters, resulting in significant decreases to the electrical conductivity between grains . These changes to the grain boundary properties would also be reflected in the mechanical performance.…”