Spinel LiMn_(2-x)Si_xO_4(x< 1,through substituting Mn^(4+) with Si^(4+) in cubic spinel LiMn_2O_4) was synthesized successfully by a facile sol-gel method.The as-prepared LiMn_(2-x)Si_xO_4 consisted of pores with l...Spinel LiMn_(2-x)Si_xO_4(x< 1,through substituting Mn^(4+) with Si^(4+) in cubic spinel LiMn_2O_4) was synthesized successfully by a facile sol-gel method.The as-prepared LiMn_(2-x)Si_xO_4 consisted of pores with large size distribution range from a few nanometers to over 200 nm and possessed specific surface area of 8.76 m^2g^(-1).Results of X-ray powder diffraction and X-ray photoelectron spectroscopy confirmed that Si atoms entered the host lattice.As a cathode material for rechargeable lithium-ion batteries,spinel LiMn_(2-x)Si_xO_4exhibited excellent structural reversibility and integrity during the charging-discharging process.The result indicated that substitution of Mn^(4+) by Si^(4+) in spinel LiMn_2O_4material effectively alleviated the phase transition caused by Jahn-Teller effect.The initial discharge capacity of the as-prepared spinel LiMn_(2-x)Si_xO_4 was 147 mA h g^(-1) over the voltage range of 1.5-4.8 V.However,after 51 cycles,the specific capacity was 88 mA h g^(-1) with capacity retention of 60%.More work is needed to understand the effects of substituting Mn^(4+) by Si^(4+) and to improve the cyclic stability.展开更多
Layered Li[Li0.2Mn.56Ni0.6Co0.08]O2 cathode materials were synthesized via a solid-state reaction for Liion batteries, in which lithium hydroxide monohydrate, manganese dioxide, nickel monoxide, and cobalt monoxide w...Layered Li[Li0.2Mn.56Ni0.6Co0.08]O2 cathode materials were synthesized via a solid-state reaction for Liion batteries, in which lithium hydroxide monohydrate, manganese dioxide, nickel monoxide, and cobalt monoxide were employed as metal precursors. To uncover the relationship between the structure and electrochemical properties of the materials, synthesis conditions such as calcination temperature and time as well as quenching methods were investigated. For the synthesized Li[Li0.2Mn.56Ni0.6Co0.08]O2 materials, the metal components were found to be in the form of Mn4＋, Ni2＋, and Co3＋, and their molar ratio was in good agreement with stoichiometric ratio of 0.56：0.16：0.08. Among them, the one synthesized at 800 ℃ for 12 h and subsequently quenched in air showed the best electrochemical performances, which had an initial discharge specific capacity and coulombic efficiency of 265.6 mAh/g and 84.0%, respectively, and when cycled at 0.5, 1, and 2 C, the corresponding discharge specific capacities were 237.3, 212.6, and 178.6 mAh/g, respectively. After recovered to 0.1 C rate, the discharge specific capacity became 259.5 mAh/g and the capacity loss was only 2.3% of the initial value at 0.1 C. This work suggests that the solid-state synthesis route is easy for preparing high performance Li[Li0.2Mn0.56Ni0.16Co0.08]O2 cathode materials for Li-ion batteries.展开更多
基金supported by China Postdoctoral Science Foundation(2012M521064)the Natural Science Foundation of Jiangsu Province(BK20140936)+1 种基金Research and Innovation Project of Jiangsu Province(KLYX_0746)the Priority Academic Program Development of Jiangsu Higher Education Institution(PAPD)
文摘Spinel LiMn_(2-x)Si_xO_4(x< 1,through substituting Mn^(4+) with Si^(4+) in cubic spinel LiMn_2O_4) was synthesized successfully by a facile sol-gel method.The as-prepared LiMn_(2-x)Si_xO_4 consisted of pores with large size distribution range from a few nanometers to over 200 nm and possessed specific surface area of 8.76 m^2g^(-1).Results of X-ray powder diffraction and X-ray photoelectron spectroscopy confirmed that Si atoms entered the host lattice.As a cathode material for rechargeable lithium-ion batteries,spinel LiMn_(2-x)Si_xO_4exhibited excellent structural reversibility and integrity during the charging-discharging process.The result indicated that substitution of Mn^(4+) by Si^(4+) in spinel LiMn_2O_4material effectively alleviated the phase transition caused by Jahn-Teller effect.The initial discharge capacity of the as-prepared spinel LiMn_(2-x)Si_xO_4 was 147 mA h g^(-1) over the voltage range of 1.5-4.8 V.However,after 51 cycles,the specific capacity was 88 mA h g^(-1) with capacity retention of 60%.More work is needed to understand the effects of substituting Mn^(4+) by Si^(4+) and to improve the cyclic stability.
基金the supports from National Natural Science Foundation of China(No.51272252)the Hundred Talents Program of the Chinese Academy of Sciences+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)(No.SA1102)the Fundamental Research Funds for the Central Universities(No.2012LWB29)
文摘Layered Li[Li0.2Mn.56Ni0.6Co0.08]O2 cathode materials were synthesized via a solid-state reaction for Liion batteries, in which lithium hydroxide monohydrate, manganese dioxide, nickel monoxide, and cobalt monoxide were employed as metal precursors. To uncover the relationship between the structure and electrochemical properties of the materials, synthesis conditions such as calcination temperature and time as well as quenching methods were investigated. For the synthesized Li[Li0.2Mn.56Ni0.6Co0.08]O2 materials, the metal components were found to be in the form of Mn4＋, Ni2＋, and Co3＋, and their molar ratio was in good agreement with stoichiometric ratio of 0.56：0.16：0.08. Among them, the one synthesized at 800 ℃ for 12 h and subsequently quenched in air showed the best electrochemical performances, which had an initial discharge specific capacity and coulombic efficiency of 265.6 mAh/g and 84.0%, respectively, and when cycled at 0.5, 1, and 2 C, the corresponding discharge specific capacities were 237.3, 212.6, and 178.6 mAh/g, respectively. After recovered to 0.1 C rate, the discharge specific capacity became 259.5 mAh/g and the capacity loss was only 2.3% of the initial value at 0.1 C. This work suggests that the solid-state synthesis route is easy for preparing high performance Li[Li0.2Mn0.56Ni0.16Co0.08]O2 cathode materials for Li-ion batteries.
