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Kinetics study and recycling strategies in different stages of full-component pyrolysis of spent LiNixCoyMnzO2 lithium-ion batteries
No full textFull-component pyrolysis has been proven to be a prospective method for the disposal of organic matters and the cathode material reduction of spent LiNixCoyMnzO2 (NCM) lithium-ion batteries (LIBs). However, the kinetics of the full-component pyrolysis of spent NCM LIBs is still unclear. This work represents the first attempt to study the kinetics of different stages of full-component pyrolysis of NCM LIBs based on isoconversional method to guide the recycling of spent LIBs. Pyrolysis process was divided into four stages in accordance to the main weight loss temperature ranges and the classical Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa kinetics models were employed to calculate the activation energy (E) in each stage. The main physicochemical reactions were clarified though in situ analysis, and the average E in the four stages was determined: (I) The volatilization of electrolytes occurred in the temperature range of 100-200 degrees C with the E of 98.6 kJ/mol. (II) The decomposition of organic matters and the preliminary reduction of cathode material transpired in the temperature range of 400-500 degrees C with the E of 227.2 kJ/mol. (III) The further reduction of NiO and CoO occurred from 650 to 800 degrees C with the E of 258.8 kJ/mol. (IV) The reduction of MnO took place from 850 to 1000 degrees C with the E of 334.9 kJ/mol. The recycling strategies based on full-component pyrolysis of spent NCM LIBs was accordingly proposed. During pyrolysis, the cathode material was gradually reduced and the pyrolytic products can be controlled through temperature regulation
High temperature oxidation behavior and mechanism of SiC-TaB2 composites
No full textIn order to improve the oxidation resistance of SiC in its ceramic matrix composites (CMCs), monolithic SiC ceramics doped with various proportions of TaB2 were prepared, isothermal and non-isothermal oxidation was investigated in detail as well. It was found that even a small proportion addition of TaB2 can effectively alleviate the intense oxidation of SiC between 1200 degrees C to 1600 degrees C, i.e., an oxidation degree of SiC can be reduced by 37% in the case with 10 wt% TaB2 under non-isothermal oxidation from room temperature to 1600 degrees C. The oxidation resistance mechanism was also studied via analyzing the composition and micro-structure of the formed oxide layer, it was found that the transformation of Ta2O5 in the multiphase oxide layer from grainy to flaky shape at about 1500 degrees C plays the most important role in the excellent high temperature oxidation resistance of composites.(c) 2022 Published by Elsevier B.V
