Synthesis Of Nickel、Manganese Compounds Micro/Nanomaterials And Their Applications In Lithium-ion Battery

In this paper, we have synthesized several kinds of nickel、manganese compounds negative materials for Li-ion batteries. The lithium storage properties of these obtained samples have been investigated. Various morphologies of NiO mico/nanostructures have been synthesized by thermal decomposition process, their electrochemical properties in lithium-ion battery were studied; MnC03twinborn spheres were obtaine by a co-precipitation method at room temperature, the electrochemical performances of the as-obtained MnCO3electrode materials were preliminarily investigated; MnO ellipsoids and twinborn spheres can be obtained through thermal decomposition approach, the lithium storage properties of these MnO samples with distinct morphologies have been investigated. The details list as follows:1. β-Ni(OH)2flower-like microspheres and triangular nanosheets have been hydrothermally synthesized at180℃in the presence of L-proline with different precipitants. NiO flower-like microspheres and triangular nanosheets can be obtained by calcining the β-Ni(OH)2precursors at350℃in air, the flower-like microspheres with diameter of1-2μm are assembled from triangular nanosheets with thickness of15nm and edge length of110run. the Brunauer-Emmett-Teller (BET) surface area are80.1m2·g-1and33.4m2·g-1, respectively. The catalytic activities of the as-obtained NiO for CO oxidation were evaluated. It was found that the catalytic activation temperature is130℃for NiO flower-like microspheres and160℃for NiO triangular nanosheets. When used as anode materials in lithium-ion batteries, NiO flower-like microspheres and triangular nanosheets exhibit initial discharge capacities of1227mAh·g-1and1105mAh·g-1, respectively. The discharge capacities for NiO flower-like microspheres and triangular nanosheets are687mAh·g-1and651mAh·g-1after charged/discharged for50cycles. The better catalytic activity and capacity for NiO flower-like microspheres may be related to the higer BET surface area.2. α-Ni(OH)2peonylike structures constructed with curly nanosheets were successfully synthesized by a facile hydrothermal method at150℃. Moreover, NiO peonylike spheres with nanopores have also been synthesized by calcination of a-Ni(OH)2precursor at350℃. We tested the electrochemical properties in lithium-ion battery at500mA·g-1. The result showed that the initial capacity is higer than2000mAh·g-1. NiO peonylike structures exhibit a discharge capacity of639.1mAh·g-1after charged/discharged for20cycles. 3. MnCO3twinborn spheres with size of1μm have been synthesized by a co-precipitation method at room temperature. The surface of the twinborn spheres is rough and consists of many nanoscale primary particles with a mean size of20nm that were assembled to form the spheres. MnCO3twinborn spheres with different sizes were obtained by adjusting the reaction times and amount of PVP. When used as an anode material in lithium-ion batteries, MnCO3twinborn spheres exhibit a discharge capacity of193mAh·g-1after charged/discharged for200cycles at500mA·g-1, while the initial capacity is1650mAh·g-1.4. MnO ellipsoids and twinborn spheres have been synthesized by thermal decomposition process at600℃. SEM images show that both the MnCO3ellipsoids and twinborn spheres have a similar size of about1μm. BET surface areas of MnCO3ellipsoids and twinborn spheres are34.3m2·g-1and3.2m2·g-1, respectively. The lithium storage properties of these MnO samples with distinct morphologies have been investigated. When used as anode materials in lithium-ion batteries, MnO ellipsoids and twinborn spheres exhibit the initial discharge capacities of1619mAh·g-1and1001mAh·g-1, respectively. After charged/discharged for25cycles at a current density of500mA·g-1, the remaining discharge capacities for MnCO3ellipsoids and twinborn spheres are442mAh·g-1and258mAh·g-1, respectively. The result show that higer BET surface areas can lead to the better electrochemical properties.