The Insertion Mechanism of Lithium into Mg2Si Anode Material for Li‐Ion Batteries

The reaction mechanism of lithium insertion into was studied using various analytic techniques including electrochemical measurements, X‐ray diffraction (XRD), and Auger electron spectroscopy (AES). Electrochemical tests demonstrated that 1 mol reacted with 3.9 mol Li from which the initial capacity obtained was approximately 1370 mAh/g. Ex situ XRD and AES data showed that lithium intercalated into the lattice first followed by alloying with Si and Mg. The degradation mechanism of during cycling was investigated because the materials degraded rapidly within ten cycles. The electrode material disintegrated and Li remained within the active material after ten cycles. The XRD and scanning electron microscope data suggested that the degradation mechanism of was due to the volume change during the alloying/dealloying reaction, and the volume expansion/contraction made the electrode materials electrically isolated. © 1999 The Electrochemical Society. All rights reserved.