1,721,408 research outputs found
Electrochemical and structural characterizations of InSb nanoparticles prepared using a sodium naphthalenide reduction method
No full textInSb nanoparticles with a mean particle size of 10 nm prepared by the reduction of metal salts using sodium naphthalenide at 350°C was discussed in terms of its electrochemical, ex situ X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterizations. Ex situ XRD and TEM results revealed the progressive formation of extruded In from InSb, followed by the formation of Li 3 In 2 and In 3 Li 13 with a lithium alloy process. In addition, it was observed that Li 2 Sb and Li 3 Sb were formed as a result of the decomposition of InSb. During lithium dealloying, Li 3Sb and In 3 Li 13 were returned to Sb and In, respectively. Nanosized InSb particles showed a charge capacity of 590 mAhg from the first-charge capacity of 670 mAhg after 30 cycles, leading to a cycle retention ratio of 86%. This value was far superior to its bulk counterpart, which showed only a 48% capacity retention ratio after the same cycles. The improved capacity retention of the nanosized InSb was due to significantly decreased particle pulverization, compared to the bulk counterpart.close2
Template synthesis of hollow Sb nanoparticles as a high-performance lithium battery anode material
No full textThe synthesis of hollow Sb nanoparticles as a high-performance Lithium battery anode material, using a SiO2 template functionalized with cetyltrimrthylammonium bromide (CTAB) groups, was reported. Scanning electron microscopy (SEM) images show that the SiO2 templates are spherical with diameters of 300 nm and that hollow Sn particles have shell thickness of 20 nm. The results also show that the improved specific lithium storage capacity of the hollow Sb is associated with the unique structure of the hollow nanostructure, which has porous shells formed during NaOH etching. Sb also shows increased charge capacity retention at higher rates to the nanoparticles while the hollow samples show the first charge capacity and its capacity after 10 cycles at a 7C rate is 587 and 570 mAh/g.close424
Superior Lithium Electroactive Mesoporous Si@Carbon Core-Shell Nanowires for Lithium Battery Anode Material
No full textMesoporous Si@carbon core-shell nanowires with a diameter of ???6.5 nm were prepared for a lithium battery anode material using a SBA-15 template. As-synthesized nanowires demonstrated excellent first charge capacity of 3163 mA h/g with a Coulombic efficiency of 86% at a rate of 0.2 C (600 mA/g) between 1.5 and 0 V in coin-type half-cells. Moreover, the capacity retention after 80 cycles was 87% and the rate capability at 2 C (6000 mA/g) was 78% the capacity at 0.2 C.close28430
PVP-Assisted ZrO2 coating on LiMn2O4 spinel cathode nanoparticles prepared by MnO2 nanowire templates
No full textLiMn2O4 spinel nanorods prepared from nanowire MnO2 templates were capped with polyvinyl pyrrolidone (PVP) and coated with ZrC2O4 precursors in aqueous solution. Upon annealing at 600 ??C in air, an amorphous ZrO2 nanoscale coating layer was obtained on the spinel nanoparticles with a particle size of <100 nm that formed from the splitting of the original spinel nanorods. The electrochemical cycling results clearly showed that nanoscale ZrO2 coating significantly improved the rate capability and cycle life at 65 ??C in spite of very high surface area of the spinel nanoparticles.close687
M-3(PO4)(2)-nanoparticle-coated LiCoO2 vs LiCo0.96M0.04O2 (M = Mg and Zn) on electrochemical and storage characteristics
No full textThe electrochemical cycling and storage characteristics of LiCo0.96 M0.04 O2 and M3 (PO4)2 nanoparticle-coated LiCoO2 cathode materials (M=Zn and Mg) were compared at room temperature and 90°C between 3 and 4.5 V. The doped cathodes showed degraded electrochemical performance at room temperature compared to the uncoated cathode. The first discharge capacities of the uncoated and the doped cathodes were 186 and 175 mAhg, respectively. The doped cathodes showed 30 mAhg after 30 cycles, while the uncoated cathode showed 100 mAhg after 50 cycles at a 1 C rate. Mg3 (PO4)2 and Zn3 (PO4)2 -coated LiCoO2 showed discharge capacities of 179 and 187 mAhg, respectively, and hadsignificantly improved capacity retention, showing 133 and 153 mAhg, respectively, after 50 cycles. After storage at 90°C, in the electrolytes using 4.5 V charged electrodes, the doped cathodes showed both greatly decreased side reactions with the electrolytes and formation of Co3 O4 and CoO phases from Li and Co dissolution. However, the coated cathodes did not show either structural transformation into the Co3 O4 and CoO phases or side reactions with the electrolytes.close7
Hard templating synthesis of mesoporous and nanowire SnO2 lithium battery anode materials
No full textMesoporous and nanowire SnO2 anode materials for lithium batteries were prepared using KIT-6 and SBA-15 SiO2 templates, and their electrochemical properties were compared at different current rates. The as-prepared SnO2 nanowires had a diameter of 6 nm and a length of >3 μm and Brunauer-Emmett-Teller (BET) surface area of 80 m2 g-1 while mesoporous SnO2 showed a pore size of 3.8 nm and a BET surface area of 160 m2 g-1. The charge capacities of these two anodes were similar to each other at 800 mAh g-1, but mesoporous SnO2 showed much improved cycle life performance and rate capabilities because of its higher surface area than nanowire SnO2. Especially, the capacity retention of the mesoporous SnO2 was 98%, compared with 31% for the SnO2 nanowires at a 10 C rate (= 4000 mA g-1). The improved electrochemical performance of the mesoporous SnO2 was related to the regular porosity which permitted thorough flooding of the electrolyte between the particles, and the mesopores which acted as a buffer zone during the volume contraction and expansion of Sn.close15415
PVP-functionalized nanometre scale metal oxide coatings for cathode materials: successful application to LiMn(2)O(4) spinel nanoparticles
No full textPVP functionalized metal oxide coatings on spinel nanoparticles demonstrated significantly improved rate characteristics under extensive cycling at 65??C and exhibited over 100% improved capacity retention compared to the bare counterpart.close212
High capacity carbon-coated Si70Sn30 nanoalloys for lithium battery anode material
No full textCarbon-coated Si70Sn30 nanoalloys with a particle size < 10 nm were prepared from butyl-capped analogues via firing at 900°C under a vacuum showed a reversible capacity of 2032 mAh g-1 and excellent capacity retention.close363
Air stable Al2O3-coated Li2NiO2 cathode additive as a surplus current consumer in a Li-ion cell
No full textHighly air stable Al2O3-coated Li2NiO 2 cathode additive is prepared by coating with Al iso-propoxide on Li2NiO2, obtained from firing of a physical mixture of pure Li2O and NiO at 600 °C for 10h under N2 atmosphere. An as-prepared coated cathode has first charge and discharge capacities of 420 mAh/g and 310 mAh/g, respectively, between 4.3V and 1.5V showing an irreversible capacity ratio of 26%. However, when the discharge cut-off voltage increases to 2.75V (2.85V vs. graphite), its discharge capacity decreases to 120 mAh/g, which corresponds to an irreversible capacity ratio of 71%. Owing to such a high irreversible capacity, it can effectively compensate for the irreversible capacity of the Li-ion cell using LiCoO2 and natural graphite as cathode and anode materials, respectively, in spite of only 4wt% addition to the LiCoO2 cathode. In addition, the additive prevents the 12V overcharge, thereby preventing the explosion of the cell. We believe that Li2NiO2 decomposition consumes the surplus current during the overcharging to 12V, and therefore the voltage is not increased until the complete decomposition of the Li2NiO2.close161
Layered Li-0.88[Li0.18Co0.33Mn0.49]O-2 nanowires for fast and high capacity Li-ion storage material
No full textLayered Li0.88[Li0.18Co0.33Mn 0.49]O2 nanowires are prepared using Co 0.4Mn0.6O2 nanowires and lithium nitrate as precursors at 200 ??C via a hydrothermal method for fast and high capacity Li-ion storage material. The obtained nanowires exhibit a reversible capacity of 230 mAh/g between 2 and 4.8 V, even at the high current rate of 3600 mA/g.close414
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