Effects of Nano-Micro Hierarchical Architecture Intraparticle Connectivity and Carbon Black-LiNi_1/3Mn_1/3Co_1/3O₂ Interaction: An Energy-Power Tradeoff In Lithium-Ion Batteries

Abstract

The performance of lithium-ion batteries depends on the morphology and distribution of components in the electrode. LiNi1/3Mn1/3Co1/3O2 (NMC) with nano-micro hierarchical structure is a commercially important cathode material for electric vehicle application. The commonly used slurry preparation method is to dry-mix the active material with a conductive additive and then disperse it in the binder solution. The energy imparted during premixing, while helping in controlling the distribution of CB to establish conducting network, can deteriorate NMC by mechanically dismantling the aggregate structure. Herein, a comprehensive effort is put forward on the understanding of dry-mixing by high-energy ball-milling. It is found that mixing intensity influences the establishment of both long-range and short-range electronic conductive pathways. The sample mixed with very low intensity and high intensity exhibited a capacity of 68 mAh.g-1 and 20 mAh.g-1 respectively, while the sample with optimum mixing exhibited 100 mAh.g-1 at 5C. This study highlights the guidelines for the preparation of electrodes for high-energy and high-power applications. At low C-rates, the capacity depends on the integrity of the microstructure of NMC, while at high C-rate optimum short and long-range electronic conductivity is the deciding factor.

Investigating the Structure and Performance of Electrodes Made by Dry and Wet Slurry Processes

“…Moreover, the distributions of PVDF and CB can strongly affect the mechanical integrity of the electrodes. Although several groups [23][24][25] have investigated various mixing approaches (e.g., mixing equipment, intensity, and duration), creating both short-and long-range ionic and electronic conducting paths throughout the electrode while achieving high mechanical integrity is still more of an art than science.…”

Influence of Mixing Process on the Performance of Electrodes Made by a Dry Coating Method

“…The voids, instead of porous CB agglomerates, reduce the longrange electronic conductivity across multiple particles. 21,23,38 The CB/PVDF layers on AM particles are densified by the molten insulating PVDF, which reduce the electronic conductivity of the CB layers and could block Li ion transportation: (1) through the regions where AM particles are in contact with each other and (2) to the AM particle surfaces from the electrolyte. Both the microscopy images and EIS results are consistent with this proposed mechanism .…”

Multilayer Graphene as a Cathode Conductive Additive in Lithium-Ion Pouch Cells: A Correlation of Changes in Electrolyte Uptake and Composition of the Electrode Electrolyte Interface with Enhanced Cycling Stability

“…The formation of the domains is controlled by the adsorption, shape, and surface energy of the additives. Our previous work shows that the binder is mainly connected to the CB, and CB binds to NMC . In MLG, because of the planer structure, the carbon binder network is weak; hence, 3% CB is added for slurry stability.…”

“…Our previous work shows that the binder is mainly connected to the CB, and CB binds to NMC. 31 In MLG, because of the planer structure, the carbon binder network is weak; hence, 3% CB is added for slurry stability. Both the slurries showed shear thinning behavior (decreased viscosity with increased shear) to facilitate the coating process.…”