Calorimetric Studies on Chemically Delithiated LiNi0.4Mn0.4Co0.2O2: Investigation of Phase Transition, Gas Evolution and Enthalpy of Formation

Li-1.11(Ni0.4Mn0.4Co0.2)O-2 powders were chemically delithiated by (NH4)(2)S2O8 oxidizer to obtain Li-x(Ni0.4Mn0.4Co0.2)O-2 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.

Automated summary

Li-x(Ni0.4Mn0.4Co0.2)O-2 powders were obtained by chemically delithiating Li-1.11(Ni0.4Mn0.4Co0.2)O-2 powders using (NH4)(2)S2O8 oxidizer. The thermal behavior of two delithiated specimens, Li0.76Ni0.41Mn0.42Co0.17O2.10 and Li0.48Ni0.38Mn0.46Co0.16O2.07, was studied and compared to the pristine specimen. Phase transitions at elevated temperatures were investigated using simultaneous thermal analysis (STA) and the gas evolution during the phase transitions was analyzed. The enthalpies of formation were calculated based on the measured enthalpies of two delithiated samples and a pristine specimen.