Percolation–tunneling modeling for the study of the electric conductivity in LiFePO4 based Li-ion battery cathodes

Delithiation kinetics study of carbon coated and carbon free LiFePO4

“…For example, the activation energy (39 kJ/mol) obtained by Takahashi et al using cyclic voltammetry[47] suggests that the thermal activation of phenomena outside the active material particles played a role in their study. These could include the conductivity of lithium into the electrolyte[48] as well as the interconnection between particle[49]. Our calculated activation energy falls within the range proposed by Maxicsh et al who used Ab initio calculations (17-20 kJ/mol )[50].…”

Effects of Particle Size, Electronic Connectivity, and Incoherent Nanoscale Domains on the Sequence of Lithiation in LiFePO4 Porous Electrodes

“…Electrode “C5” employed a technologically relevant, high mass loading of active material: 89 wt% carbon‐coated LiFePO 4 (Mitsui Engineering Shipbuilding Co., Ltd), 5 wt% carbon black (Timcal C65), and 6 wt% poly(vinylidene fluoride) (PVDF) binder. Electrode “C20” contained 74 wt% LiFePO 4 , 20 wt% carbon black, and 6 wt% PVDF; this electrode exhibits better electronic conduction and sufficient carbon black loading to create a fully percolating electronic network . To minimize macroscopic ion transport gradients, we used dilute electrodes with high porosities, ≈60% and ≈70% for the C5 and C20 electrodes, respectively.…”

“…We propose that differences in the sequence of lithiation between the C5 and C20 electrodes arise due to the differing degrees of local electronic connectivity. Awarke et al conducted a percolation‐tunneling model of electrodes containing LiFePO 4 and carbon black, and showed that, for 200 nm spherical LiFePO 4 particles, the carbon black loading must be greater than 10 wt% to achieve critical electronic percolation (assuming that the LiFePO 4 particles are nonconducting) . Since the carbon black loading in the C20 electrode (20 wt%) is significantly above the percolation threshold, most of the carbon black particles belong to the largest, percolated cluster .…”

Discharge Performance of Li–O2 Batteries Using a Multiscale Modeling Approach

“…[32][33] Here, we adopted the particlepacking method [34][35] as an alternative effective approach. We note that this approach also has been used successfully for microstructure reconstruction in modeling SOFC and Li-ion batteries [36][37][38] , but it has not yet been applied to Li-O 2 battery. In this method, the porous structure is modeled as a packed bed of particles with various sizes and shapes, reflecting the fact that Li-O 2 air electrode is fabricated from powder materials.…”