Hierarchical LiFePO4/C microspheres with high tap density assembled by nanosheets as cathode materials for high-performance Li-ion batteries

Engineering 3D bicontinuous hierarchically macro-mesoporous LiFePO4/C nanocomposite for lithium storage with high rate capability and long cycle stability

A highly crystalline three dimensional (3D) bicontinuous hierarchically macro-mesoporous LiFePO₄/C nanocomposite constructed by nanoparticles in the range of 50~100 nm via a rapid microwave assisted solvothermal process followed by carbon coating have been synthesized as cathode material for high performance lithium-ion batteries. The abundant 3D macropores allow better penetration of electrolyte to promote Li⁺ diffusion, the mesopores provide more electrochemical reaction sites and the carbon layers outside LiFePO₄ nanoparticles increase the electrical conductivity, thus ultimately facilitating reverse reaction of Fe³⁺ to Fe²⁺ and alleviating electrode polarization. In addition, the particle size in nanoscale can provide short diffusion lengths for the Li⁺ intercalation-deintercalation. As a result, the 3D macro-mesoporous nanosized LiFePO₄/C electrode exhibits excellent rate capability (129.1 mA h/g at 2 C; 110.9 mA h/g at 10 C) and cycling stability (87.2% capacity retention at 2 C after 1000 cycles, 76.3% at 5 C after 500 cycles and 87.8% at 10 C after 500 cycles, respectively), which are much better than many reported LiFePO₄/C structures. Our demonstration here offers the opportunity to develop nanoscaled hierarchically porous LiFePO₄/C structures for high performance lithium-ion batteries through microwave assisted solvothermal method.

Porous micro-spherical LiFePO4/CNT nanocomposite for high-performance Li-ion battery cathode material

Although many routes have been developed that can efficiently improve the electrochemical performance of LiFePO₄ cathodes, few of them meet the urgent industrial requirements of large-scale production, low cost and excellent performance.

Effect of the Sheet Thickness on the Electrochemical Performance of 2-D SnO2 Nanomaterial as Li Ion Battery Anode Material

2-D SnO2nanosheets with controllable thickness have been synthesized via a simple hydrothermal method. Characterization shows that the sheet thickness can be controlled from 3 to 30 nm. The correlation between the sheet thickness and the electrochemical performance of these samples as anode materials for Li ion batteries were investigated, it was found that when the sheet thickness less than 10 nm, electrodes with high charge/discharge capacities, coulombic efficiencies and stable cycling performance could be realized. The good electrochemical performance are ascribe to the ultra thin nanosheet, good flexility and porous structure of the SnO2anode material.

Solvothermal synthesis of monodisperse LiFePO4 micro hollow spheres as high performance cathode material for lithium ion batteries

A microspherical, hollow LiFePO4 (LFP) cathode material with polycrystal structure was simply synthesized by a solvothermal method using spherical Li3PO4 as the self-sacrificed template and FeCl2·4H2O as the Fe(2+) source. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that the LFP micro hollow spheres have a quite uniform size of ~1 μm consisting of aggregated nanoparticles. The influences of solvent and Fe(2+) source on the phase and morphology of the final product were chiefly investigated, and a direct ion exchange reaction between spherical Li3PO4 templates and Fe(2+) ions was firstly proposed on the basis of the X-ray powder diffraction (XRD) transformation of the products. The LFP nanoparticles in the micro hollow spheres could finely coat a uniform carbon layer ~3.5 nm by a glucose solution impregnating-drying-sintering process. The electrochemical measurements show that the carbon coated LFP materials could exhibit high charge-discharge capacities of 158, 144, 125, 101, and even 72 mAh g(-1) at 0.1, 1, 5, 20, and 50 C, respectively. It could also maintain 80% of the initial discharge capacity after cycling for 2000 times at 20 C.