Leaching kinetics of fluorine during the aluminum removal from spent Li-ion battery cathode materials

The high content of aluminum(Al)impurity in the recycled cathode powder seriously affects the extraction efficiency of Nickel,Cobalt,Manganese,and Lithium resources and the actual commercial value of recycled materials,so Al removal is crucially important to conform to the industrial standard of spent Li-ion battery cathode materials.In this work,we systematically investigated the leaching process and optimum conditions associated with Al removal from the cathode powder materials collected in a wet cathode-powder peeling and recycling production line of spent Li-ion batteries(LIBs).Moreover,we specifically studied the leaching of fluorine(F)synergistically happened along with the removal process of Al,which was not concerned about in other studies,but one of the key factors affecting pollution prevention in the recovery process.The mechanism of the whole process including the leaching of Al and F from the cathode powder was indicated by using NMR,FTIR,and XPS,and a defluoridation process was preliminarily investigated in this study.The leaching kinetics of Al could be successfully described by the shrinking core model,controlled by the diffusion process and the activation energy was 11.14 kJ/mol.While,the leaching of F was attributed to the dissolution of LiPF6and decomposition of PVDF,and the kinetics associated was described by Avrami model.The interaction of Al and F is advantageous to realize the defluoridation to some degree.It is expected that our investigation will provide theoretical support for the large-scale recycling of spent LIBs.

Effect of polishing parameters on abrasive free chemical mechanical planarization of semi-polar(1122) aluminum nitride surface

An abrasive free chemical mechanical planarization（AFCMP） of semi-polar（1122） Al N surface has been demonstrated. The effect of slurry p H, polishing pressure, and platen velocity on the material removal rate（MRR） and surface quality（RMS roughness） have been studied. The effect of polishing pressure on the AFCMP of the（1122） Al N surface has been compared with that of the（1122） Al Ga N surface. The maximum MRR has been found to be 562 nm/h for the semi-polar（1122） Al N surface, under the experimental conditions of 38 k Pa pressure,90 rpm platen velocity, 30 rpm carrier velocity, slurry p H 3 and 0.4 M oxidizer concentration. The best root mean square（RMS） surface roughness of 1.2 nm and 0.7 nm, over a large scanning area of 0.70×0.96 mm^2, has been achieved on AFCMP processed semi-polar（1122） AlN and（AlGaN） surfaces using optimized slurry chemistry and processing parameters.