Ya Mao
Chinese Academy of Sciences
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Publication
Featured researches published by Ya Mao.
Energy and Environmental Science | 2012
Ya Mao; Hui Duan; Bin Xu; Lin Zhang; Yong-Sheng Hu; Changchun Zhao; Zhaoxiang Wang; Liquan Chen; Yusheng Yang
Nitrogen-rich mesoporous carbon materials were obtained by pyrolyzing gelatin between 700 and 900 °C with a nano-CaCO3 template. The mesoporous structure and the high nitrogen content endowed these materials with reversible capacities up to ca. 1200 mA h g−1. The high specific surface area and the nitrogen doping are responsible for the capacity loss in the initial cycle. FTIR and XPS studies indicate that the nitrogen in the material exists in the form of pyridinic, pyrrolic/pyridonic and graphitic nitrogen. The Raman spectroscopic analysis indicates that the structure of the mesoporous carbon becomes more disordered during discharge and is restored during recharge, a behavior similar to that in nitrogen-free hard carbon materials. The reversible structural variation of these carbon materials ensures their high cyclic reversibility.
Chemistry-an Asian Journal | 2012
Xiangpeng Fang; Xianwei Guo; Ya Mao; Chunxiu Hua; Lanyao Shen; Yong-Sheng Hu; Zhaoxiang Wang; Feng Wu; Liquan Chen
The most-popular strategy to improve the cycling stability and rate performance of the sulfur electrode in lithium-sulfur (Li-S) batteries is to astrict the sulfur in a conducting medium by using complicated chemical/physical processing. Lithium sulfide (Li(2)S) has been proposed as an alternative electrode material to sulfur. However, for its application, it must meet challenges such as high instability in air together with all of the drawbacks of a sulfur-containing electrode. Herein, we report the feasibility of using Li(2)S, which was obtained by electrochemical conversion of commercial molybdenum disulfide (MoS(2)) into Li(2)S and metallic molybdenium (Mo) at low voltages, as a high-performance active material in Li-S batteries. Metallic Mo prevented the dissolution of lithium polysulfides into the electrolyte and enhanced the conductivity of the sulfide electrode. Therefore, the in situ electrochemically prepared Li(2)S/Mo composite exhibited both high cycling stability and high sulfur utilization.
Energy and Environmental Science | 2011
Ya Mao; Qingyu Kong; Bingkun Guo; Xiangpeng Fang; Xianwei Guo; Lian Shen; Michel Armand; Zhaoxiang Wang; Liquan Chen
Current lithium ion battery (LIB) technologies are all based on inorganic electrodes though organic materials have been hyped as electrodes for years. Disadvantages such as low specific capacity and poor rate performance hinder their applications. Here we report a novel high-performance organometallic lithium-storage material, a polypyrrole-iron-oxygen (PPy-Fe-O) coordination complex. Extended X-ray absorption fine structure (EXAFS) spectroscopy and density functional theory (DFT) calculations indicate that this complex has a multilayer structure. The strong and stable intralayer Fe–N coordination permits the material to possess high specific capacity, the high reversibility of its interlayer Fe–O–Fe interaction during cycling ensures its high cycling stability and the conducting PPy matrix endows it with outstanding rate performance. These findings pave the way to constructing a new type of high-performance organic anode materials for LIBs.
Chemistry: A European Journal | 2011
Bingkun Guo; Qingyu Kong; Ying Zhu; Ya Mao; Zhaoxiang Wang; Meixiang Wan; Liquan Chen
Current lithium-ion battery (LIB) technologies are all based on inorganic electrode materials, though organic materials have been used as electrodes for years. Disadvantages such as limited thermal stability and low specific capacity hinder their applications. On the other hand, the transition metal oxides that provide high lithium-storage capacity by way of electrochemical conversion reaction suffer from poor cycling stability. Here we report a novel high-performance, organic, lithium-storage material, a polypyrrole-cobalt-oxygen (PPy-Co-O) coordination complex, with high lithium-storage capacity and excellent cycling stability. Extended X-ray absorption fine structure and Raman spectroscopy and other physical and electrochemical characterizations demonstrate that this coordination complex can be electrochemically fabricated by cycling PPy-coated Co(3)O(4) between 0.0 V and 3.0 V versus Li(+)/Li. Density functional theory (DFT) calculations indicate that each cobalt atom coordinates with two nitrogen atoms within the PPy-Co coordination layer and the layers are connected with oxygen atoms between them. Coordination weakens the C-H bonds on PPy and makes the complex a novel lithium-storage material with high capacity and high cycling stability.
Electrochemistry Communications | 2010
Xiangpeng Fang; Xia Lu; Xianwei Guo; Ya Mao; Yong-Sheng Hu; Jiazhao Wang; Zhaoxiang Wang; Feng Wu; Hua-Kun Liu; Liquan Chen
Electrochemistry Communications | 2010
Xianwei Guo; Xia Lu; Xiangpeng Fang; Ya Mao; Zhaoxiang Wang; Liquan Chen; Xiaoxue Xu; Hong Yang; Yinong Liu
Journal of Power Sources | 2013
Xiangpeng Fang; Xianwei Guo; Ya Mao; Jun Ma; Changchun Zhao; Zhaoxiang Wang; Liquan Chen
Electrochimica Acta | 2013
Ya Mao; Qingyu Kong; Bingkun Guo; Lian Shen; Zhaoxiang Wang; Liquan Chen
Journal of Physical Chemistry C | 2011
Xianwei Guo; Xiangpeng Fang; Ya Mao; Zhaoxiang Wang; Feng Wu; Liquan Chen
Journal of Power Sources | 2014
Ya Mao; Qingyu Kong; Lian Shen; Zhaoxiang Wang; Liquan Chen