A comparative study of polarization during the initial lithiation step in tungsten-oxide negative electrodes for lithium-ion batteries

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>In this study, polarization behavior during initial lithiation step was comparatively investigated using a tungsten oxide (WO<SUB>3</SUB>) and its reduced one (WO<SUB>3− <I>x</I> </SUB>). Ex-situ X-ray diffraction revealed that the overall lithiation process in WO<SUB>3</SUB> was mostly similar to that of WO<SUB>3− <I>x</I> </SUB>, which was associated with the typical conversion reaction of transition-metal oxide. In the WO<SUB>3− <I>x</I> </SUB> anode, however, insertional lithiation was initiated above 2V vs. Li/Li<SUP>+</SUP> and a following conversion reaction was observed, which was different charging behavior from WO<SUB>3</SUB> electrode. The severe polarization related with the conversion reaction was alleviated owing to the high electrical conductivity in the mixed-valance state of WO<SUB>3− <I>x</I> </SUB>. Furthermore, the different initial polarization in WO<SUB>3− <I>x</I> </SUB> anode resulted in the improvement of cycle performance and efficiency.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>