Calorimetric Studies on Chemically Delithiated LiNi<sub>0.4</sub>Mn<sub>0.4</sub>Co<sub>0.2</sub>O<sub>2</sub>: Investigation of Phase Transition, Gas Evolution and Enthalpy of Formation
Wenjiao Zhao,
Julian Gebauer,
Thomas Bergfeldt,
Magnus Rohde,
Carlos Ziebert,
Yong Du,
Hans J. Seifert
Affiliations
Wenjiao Zhao
Volkswagen AG, 38239 Salzgitter, Germany
Julian Gebauer
Karlsruhe Institute of Technology, Institute of Applied Materials-Applied Materials Physics (IAM-AWP), 76344 Eggenstein-Leopoldshafen, Germany
Thomas Bergfeldt
Karlsruhe Institute of Technology, Institute of Applied Materials-Applied Materials Physics (IAM-AWP), 76344 Eggenstein-Leopoldshafen, Germany
Magnus Rohde
Karlsruhe Institute of Technology, Institute of Applied Materials-Applied Materials Physics (IAM-AWP), 76344 Eggenstein-Leopoldshafen, Germany
Carlos Ziebert
Karlsruhe Institute of Technology, Institute of Applied Materials-Applied Materials Physics (IAM-AWP), 76344 Eggenstein-Leopoldshafen, Germany
Yong Du
State Key Lab of Powder Metallurgy, Central South University, Changsha 410083, China
Hans J. Seifert
Karlsruhe Institute of Technology, Institute of Applied Materials-Applied Materials Physics (IAM-AWP), 76344 Eggenstein-Leopoldshafen, Germany
Li1.11(Ni0.4Mn0.4Co0.2)O2 powders were chemically delithiated by (NH4)2S2O8 oxidizer to obtain Lix(Ni0.4Mn0.4Co0.2)O2 powders. The thermal behavior of two delithiated specimens, Li0.76Ni0.41Mn0.42Co0.17O2.10 and Li0.48Ni0.38Mn0.46Co0.16O2.07, was studied compared to the pristine specimen. Phase transitions at elevated temperatures were investigated by simultaneous thermal analysis (STA) and the gas evolution accompanying the phase transitions was analyzed by mass spectroscopy and an oxygen detector. The enthalpy of two delithiated samples and a pristine specimen were measured by a high temperature drop solution calorimeter. Based on these results, the enthalpies of formation were calculated.
