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Eliminating Voltage Decay of Lithium‐Rich Li 1.14 Mn 0.54 Ni 0.14 Co 0.14 O 2 Cathodes by Controlling the Electrochemical Process
Author(s) -
Wei Zhen,
Zhang Wei,
Wang Feng,
Zhang Qian,
Qiu Bao,
Han Shaojie,
Xia Yonggao,
Zhu Yimei,
Liu Zhaoping
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201406641
Subject(s) - lithium (medication) , cathode , materials science , analytical chemistry (journal) , atomic physics , chemistry , physics , medicine , chromatography , endocrinology
A lithium‐rich cathode material Li 1.14 Mn 0.54 Ni 0.14 Co 0.14 O 2 (LNMCO) is prepared by a co‐precipitation method. The issue of voltage decay in long‐term cycling is largely eliminated by control of the charge–discharge voltage range. The LNMCO material exhibits 9.8 % decay in discharge voltage over 200 cycles between 2.0–4.6 V, during which the working voltage decays significantly, from 3.57 V to 3.22 V. The decay was decelerated by a factor of six by using a voltage window of 2.0–4.4 V, from 3.53 V to 3.47 V. IR and Raman spectra reveal that the transformation of layered structure to spinel is significantly retarded under 2.0–4.4 V cycling conditions. Transmission electron microscopy (TEM) was also applied for examining phase change in an individual particle during cycling, showing that the spinel phase occurs both at 2.0–4.6 V and at 2.0–4.4 V, but is not dominant in the latter. Normalization of Li can remove the additional impact on the voltage decay which is brought by different amounts of Li intercalation. The mechanism of no voltage decay at 2.0–4.4 V cycling is raised and electrochemical impedance spectrum data also support the hypothesis.