Spherically Smooth Cathode Particles by Mechanofusion Processing

Abstract

Surface modification has been shown to be useful for improving the cycling performance of cathode materials. Typically heterocompositional coatings are applied on cathode particle surfaces using methods, such as aqueous deposition and atomic layer deposition (ALD), that can be expensive and inefficient. In this report, a dry mechanofusion method was used to treat cathode particles with no auxiliary coating applied. This resulted in a drastic reduction in surface area and the elimination of surface features on the particles. Furthermore, the processing results in an iso-compositional amorphous shell on the surface of each particle. The resulting particles have improved cycling. We believe the mechanofusion process is an important step toward the goal of improving the cycling performance of cathode materials.

All-Dry Synthesis of Single Crystal NMC Cathode Materials for Li-Ion Batteries

“…24 Further improvements may be made by methods widely used in industry, such as elemental doping, surface coating, electrolyte additives, etc. 22,[25][26][27][28] Nevertheless, it was thought previously, that the particle size of the co-precipitated precursor governs the SC-NMC crystallite size. 29 Here we show that this is not the case.…”

Impact of Aluminum Added to Ni-Based Positive Electrode Materials by Dry Particle Fusion

“…Dry particle fusion or mechanofusion has been used for many years to prepare core particles that are coated with another material. − Recently, the research group of M. Obrovac has been using mechanofusion to prepare engineered particles of advanced materials for Li-ion batteries by coating Al 2 O 3 on LiNi 0.6 Mn 0.2 Co 0.2 O 2 and embedding Si alloy particles into graphite layers. − These materials showed superior charge–discharge cycling performance in all cases. The uniformity of the coating layers on the surface of the core materials and the uniformity of the Si distribution within graphite drew our attention.…”

High Energy Density Large Particle LiFePO4

“…We suggest that this microstructure can be attributed to the DPF process, where the template particles are coated with LFP and graphite particles, while this coating is simultaneously subjected to high shear forces, which causes the shearing and smoothing of the graphite and LFP particles along the template particle surface (as has been previously observed during mechanofusion processing of polycrystalline NMC). 23 If, as suggested from the XRD results, the LFP predominately shears along the (101) planes in this process, then such a mechanism would result in sequential layers of graphite and LFP crystallites oriented parallel to the flake basal plane. During subsequent heating, the LFP particles would crystallize, causing grain growth and partial disruption of the layered structure.…”