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Ba‐doping to Improve the Cycling Stability of LiNi 0.5 Mn 0.5 O 2 Cathode Materials for Batteries Operating at High Voltage
Author(s) -
Liu Zeyu,
Zheng Hong,
Tan Li,
Yuan Silan,
Yin Haiyan
Publication year - 2018
Publication title -
energy technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.91
H-Index - 44
eISSN - 2194-4296
pISSN - 2194-4288
DOI - 10.1002/ente.201700855
Subject(s) - x ray photoelectron spectroscopy , analytical chemistry (journal) , materials science , rietveld refinement , doping , dielectric spectroscopy , cathode , electrochemistry , scanning electron microscope , cyclic voltammetry , crystal structure , chemistry , chemical engineering , crystallography , electrode , optoelectronics , chromatography , composite material , engineering
Abstract LiNi 0.5− x Ba x Mn 0.5 O 2 ( x= 0, 0.03, 0.05, 0.08) samples were prepared by using a combination of co‐precipitation and solid‐state methods. All of the cathode materials were analyzed by inductively coupled plasma mass spectrometry (ICP‐MS), X‐ray diffraction (XRD), Rietveld refinement, X‐ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The results of them show that we have successfully prepared the target materials, and Ba‐doping can keep the structure stable and lower Li/Ni cation mixing. In addition, Ba‐doping does not change the structure, the chemical states, or the morphology of LiNi 0.5 Mn 0.5 O 2 . The electrochemical properties of the samples were explored systematically by rate performance and charge–discharge tests at room temperature and high temperature. The performances of the cathode materials indicate that 5 mol % Ba‐doping of LiNi 0.5 Mn 0.5 O 2 can improve the capacity retention at 0.2 C by approximately 41 % and 13 %, at room temperature and 60 °C, respectively. in the range between 2.5 and 4.8 V. In addition, the 5 mol % Ba‐doped material shows better rate performances than that of the un‐doped material, especially at higher current densities. Cyclic voltammetry (CV) and electrochemical impedance spectroscope (EIS) tests were used to analyze the reason for the improved electrochemical properties, which may be attributed to lower Li/Ni cation mixing, higher structural stability, lower polarization, and lower charge transfer resistance.