Ming-Zhe Xue

Lithium Electrochemistry of a Novel SnSe Thin-Film Anode

SnSe thin film prepared by reactive pulsed laser deposition (PLD) method was found to be a novel and promising anode material. Cyclic voltammetry (CV) and discharge and charge behaviors of Li/SnSe cells were examined, andthe reversible discharge capacities in the range from 400 to 681 mAh/g were achieved during the first 40 cycles. A reduction in oxidation peaks at 1.3 and 1.9 V from CV curves of Li/SnSe cell was first observed, indicating the reversible formation and decomposition of reaction of Li 2 Se. This feature is utterly different from those of SnO 2 or SnO and SnS 2 , in which Li 2 O and Li 2 S are inactive. The lithium electrochemical reaction of SnSe thin-film electrode has been investigated by scanning electron microscopy (SEM). X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Both classical alloying process and the selenidation-reduction of nanosized metal tin were revealed in lithium electrochemical reaction of SnSe. SnSe as the starting material for conversion to Li-Sn alloy can improve its electrochemical performance with high reversible capacity and good, stable cyclability, demonstrating a promising anode material for future rechargeable lithium batteries.

LiF ∕ Co Nanocomposite as a New Li Storage Material

A nanocomposite consisting of both LiF and transition metal Co as general inactive electrochemical materials fabricated by pulsed laser deposition exhibits significant electrochemical activity. The charge and discharge measurement indicate that the first charge capacity of 205 mAh/g for the LiF-Co/Li cell is found to release Li. The process of releasing Li from the as-deposited LiF-Co nanocomposite thin films is confirmed by ex situ high resolution transmission electron microscopy and selected area electron diffraction measurements. These results provide direct experimental evidence to support the decomposition of LiF driven by the transition metal Co. LiF-Co nanocomposite electrodes may be found to be a new good candidate for Li storage material.

The reinvestigation on electrochemical reaction mechanism of stannic oxide thin film with lithium

The electrochemical reaction mechanism of SnO 2 with lithium involving both alloying/dealloying processes and oxidation/ reduction processes of metal Sn is clarified. SnO 2 thin film exhibited a high reversible capacity of 6.2 Li per Sn with good cycling performance. Two couples of reduction and oxidation peaks at 0.69 and 0.82 V and at 1.40 and 1.90 V in cyclic voltammetry curves could be attributed to the reversible reduction and oxidation of Sn. Transmission electron microscopy and selected area electron diffraction confirmed the formation of SnO 2 after charging the SnO 2 /Li cell to 3.0 V. Our results demonstrate that the reversible formation and decomposition of Li 2 O could be driven by nanosized metal tin.