Electrochemical performances of MgH2 and MgH2-C films for lithium ion battery anode

By Peng, Xiang; Wang, Hui; Hu, Renzong; Ouyang, Liuzhang; Liu, Jiangwen; Zhu, Min
Published in Journal of Alloys and Compounds NULL 2017

Abstract

Abstract As a high-capacity hydrogen storage material, MgH2 also shows specific advantages for {LIB} anode. In this work, MgH2 and MgH2-C films were prepared by magnetron sputtering and hydrogenation treatment, and their microstructural and electrochemical properties were investigated. Through the conversion reaction of MgH2 with lithium (MgH2 + 2Li+ ? Mg + 2LiH), the reversible lithium storage was achieved in the MgH2 and MgH2-C films. The MgH2 film delivers the initial discharge capacity of 313.9 ?Ah cm?2 (?2956 mAh g?1), the discharge and charge capacities related to the conversion process are respectively 150.0 ?Ah cm?2 (?1412 mAh g?1) and 55.0 ?Ah cm?2 (?518 mAh g-1), with the inefficiency of 63.3%. The {GITT} measurement determined the equilibrium potential of this conversion reaction to be 0.55 V vs. Li/Li+, and the voltage hysteresis between discharge and charge is only 10 mV vs. Li/Li+. In comparison with the MgH2 film, the MgH2-C film has smaller crystallite size, lower polarization effect and structural stability, but exhibiting lower capacity and equally poor cyclic performance. The poor cycle life of MgH2-C film electrode is due to the large irreversibility of conversion reaction of MgH2, instead of structural damage of film electrode during cycling.

Read » Back