Article Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX
pubs.acs.org/IC
Bi2MoO6 Microsphere with Double-Polyaniline Layers toward Ultrastable Lithium Energy Storage by Reinforced Structure Yang Zhang, Ganggang Zhao, Peng Ge, Tianjing Wu, Lin Li, Peng Cai, Cheng Liu, Guoqiang Zou,* Hongshuai Hou, and Xiaobo Ji College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China
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ABSTRACT: Given its competitive theoretical capacity, Bi2MoO6 is deemed as a promising anode material for the realization of efficient Li storage. Considering the severe capacity attenuation caused by the lithiation-induced expansion, it is essential to introduce effective modification. Remarkably, in this work, Bi2MoO6 microsphere with double-layered spherical shells are successfully prepared, and the polyaniline are coated on both inner and outer surfaces of double-layered spherical shells, working as buffer layers to strain the volume expansion during electrochemical cycling. Inspiringly, when utilized as anode in LIBs, the specific capacity of Bi2MoO6@PANI is maintained at 656.3 mAh g−1 after 200 cycles at 100 mA g−1, corresponding to a high capacity of 82%. However, the counterpart of individual Bi2MoO6 is only 36%. This result confirms that the polyaniline layer can dramatically promote stable cycling performances. Supported by in situ EIS and ex situ technologies followed by detailed analysis, the enhanced pseudocapacitance-dominated contributions and electron/ion transfer rate, benefiting from the combination with polyaniline, are further proved. This work confirms the significant effect of polyaniline on the ultrastable energy storage, further providing an in-depth sight on the impacts of polyaniline coating to the electrical conductivity as well as the resistances of electron/ion transport.
1. INTRODUCTION Triggered by the limited theoretical specific capacity (372 mAh g−1) of commercial graphite anode, the ever-growing demands have been made for alternative electrode materials for Lithiumion batteries (LIBs) with higher energy density, better safety features and enhanced rate performances.1−3 In terms of largescale fabrication and high theoretical specific capacity, a number of metal oxides have been paid close attention as potential anode materials for LIBs such as MoO3,4 Fe3O4,5 SnO2,6 and Co3O47 in recent years. Nevertheless, the commercial applications of most metal oxides were seriously hindered by their low conductivity and severe capacity fading caused by volume expansion and further structural pulverization during the repeated lithiation/delithiation processes.8,9 It is well-defined that multicomponent metal oxides normally show the enhanced electrochemical performances than that of single-component metal oxides due to their rich chemical component and synergistic reactions between multiple metal species.10 Particularly, Bi2MoO6, a layered structure consisted of [Bi 2 O 2 ] 2+ and slabs interleaved by double slabs of [MoO4]4+,11,12 has been widely studied as a photocatalyst for its excellent photoelectric properties13−17 and as an electrode materials for energy storage devices, such as LIBs, on account of its high theoretical specific capacity (791 mAh g−1) and low desertion voltage (
