LiY(MoO4)2 nanotubes: Novel zero-strain anode for electrochemical energy storage

Abstract In this work, a novel zero-strain anode, LiY(MoO4)2 nanotubes, is firstly prepared by a simple electrospinning technique, which exhibits outstanding rate performance and stable cycling performance. After 580 cycles, the capacity retention of LiY(MoO4)2 nanotubes is up to 94%, while that of LiY(MoO4)2 bulks is only 30%. The enhancement can be attributed to the hollow structure of nanotubes. More importantly, in situ X-ray diffraction (XRD) technique is used for the first time to explore the mechanism of Li ion insertion/extraction for LiY(MoO4)2 nanotubes. It can be concluded that Li ions initially occupy vacant 8c sites for energy storage through tunnels built by Mo-O tetrahedra. With repeated lithiation, the Y(Li)O8 polyhedra are gradually distorted. The distortion of Y(Li)O8 polyhedra not only relieves the volume expansion caused by lithiation, but also induces the 8d site to be opened to allow more Li ions to be embedded. Moreover, in situ XRD and ex situ transmission electron microscopy (TEM) studies demonstrate that LiY(MoO4)2 nanotubes have outstanding structural stability with the maximum volume expansion of LiY(MoO4)2 nanotubes of only 0.53%, suggesting that LiY(MoO4)2 nanotubes, like Li4Ti5O12, are zero-strain insertion materials. All of these advantages suggest that LiY(MoO4)2 nanotubes are possible anode material for LIBs.