Determination of the chemical diffusion coefficient of lithium ions in spherical Li[Ni0.5Mn0.3Co0.2]O2

• DOI: 10.1016/j.electacta.2012.01.061
• Publication Date: 2012-01-24T23:01:07Z
• Authors: Shunyi Yang; Xianyou Wang; Xiukang Yang; Yansong Bai; Ziling Liu; Hongbo Shu; Qiliang Wei
• Keywords: 0202 electrical engineering, electronic engineering, information engineering; 02 engineering and technology; 7. Clean energy

Abstract The chemical diffusion coefficients of lithium ions ( D Li ) in spherical Li[Ni 0.5 Mn 0.3 Co 0.2 ]O 2 are systematically determined by galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS). The D Li obtained from GITT are greatly dependent on the lithium content and cell potential. In the charge process, the D Li values are in the range of 9.0 × 10 −11 to 3.3 × 10 −9 cm 2 s −1 . In the discharge process, the D Li values are in the range of 1.9 × 10 −11 to 3.9 × 10 −9 cm 2 s −1 . In addition, the minimum values in the D Li are observed at the stoichiometry x ≈ 0.25 for Li 1− x [Ni 0.5 Mn 0.3 Co 0.2 ]O 2 , which coincide with the voltage-plateau region at about 3.75 V. The D Li obtained from EIS are in the range of 1.7 × 10 −11 to 6.5 × 10 −9 cm 2 s −1 and the variation tendency with cell potential is consistent with the results obtained from GITT during the charge process.