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The Influence of Residual Acidic and Sulfate Impurities of Electrolytic Manganese Dioxide on the Electrochemistry of LiMn 2 O 4 Cathode
Author(s) -
Wang Shuangcai,
Hu Huiping,
Wang Lianbang,
Wu Hao,
Guo Ting,
Cai Xinhui,
Xu Wenzhu,
Zhao Suping,
Yu Peifeng
Publication year - 2017
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201701440
Subject(s) - manganese , impurity , electrochemistry , spinel , inorganic chemistry , cyclic voltammetry , dielectric spectroscopy , electrolyte , lithium (medication) , raman spectroscopy , chemistry , materials science , analytical chemistry (journal) , electrode , metallurgy , medicine , physics , organic chemistry , chromatography , optics , endocrinology
We investigated the influence of residual acidic impurities of electrolytic manganese dioxide (EMD) and sulfate impurities of neutralized EMD on the electrochemistry of LiMn 2 O 4 cathode. Via high temperature solid‐phase reactions, spinel lithium manganese oxide (LiMn 2 O 4 ) samples were synthesized using the acidic and neutral EMD as precursor mixed with Li 2 CO 3 for the lithium ion battery cathodes. X‐ray diffraction (XRD) pattern shows that both hexagonal and orthorhombic phases exist in EMD. Inductively coupled plasma optical emission spectrometers (ICP) and FT‐IR results show that there are sulfates impurities in EMD. SEM images show no obvious difference between EMD and four LiMn 2 O 4 samples. The crystallinity of spinel lithium manganese (LiMn 2 O 4 ) synthesized by the EMD precursor is high. The electrochemical tests show that LiMn 2 O 4 synthesized by EMD neutralized by NH 3 ⋅H 2 O (EMD−A, pH is about 7.0) precursor has the greatest discharge capacity and relatively good cycle performance among four LiMn 2 O 4 . The Raman analysis result is consistent with the electrochemical test results, as the average valence of Mn element increased of A‐LMO, cycle performance of the sample has become better. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results indicate that LiMn 2 O 4 synthesized by EMD−A precursor has better electrochemical reaction reversibility, greater peak current and smaller electrochemical resistance.