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LiFePO4/C ultra-thin nanoflakes have been synthesized via evaporative self-assembly induced by squaric acid and successfully applied for cathode materials in full cell. The morphologies and structures were characterized by X-ray diffractometer, scanning electron microscopy and transmission electron microscopy. Some LiFePO4/C nanoparticles about 40–80 nm in diameter are connected by LiFePO4/C ultra-thin nano-flakes which are constructed by squaric acids, other LiFePO4 nanoparticles are embedded in the ultra-thin carbon nanoflakes. LiFePO4/C ultra-thin nano-flakes deliver a initial discharge capacity of 164 mAh g−1 at 0.2C rate and 92 mAh g−1 at 50 C rate. Its capacity retention is still 96% at 10 C rate after 1000 cycles. The unique LiFePO4/C ultra-thin nano-flakes can effectively increase the contact between electrode and electrolyte, improve the electronic and ionic conductivity and promote the transportations for lithium ions.

Research on the magnetotelluric (MT) forward modeling response in anisotropic media has been important since the discovery of anisotropic electric fields in the Earth's interior. In this study, we presented an edge-based and nodal finite-element method (FEM) for three-dimensional (3D) MT forward modeling problems in general anisotropic media. Partial differential equations are derived using the Coulomb-gauged approach from Maxwell's equation and discretized by the edge-based and nodal FEM. The magnetic vector A was discretized by an edge-based FEM and the electric scalar ψ was discretized by nodal FEM. The computational domain was refined using a hexahedral mesh. The Galerkin variant of the weighted residuals method was used to obtain a sparse linear system for magnetic vector A and electric scalar ψ. Three models were designed to validate and analyze our forward modeling code by comparing it with a one-dimensional analytical solution and with the results from codes developed by other scholars. A direct solver and iterative solvers with preprocessors were used to evaluate the performance of our code. Numerical experiments showed that our forward modeling code is accurate and robust and converges faster. In addition, the stiffness matrix assembled by our algorithm was smaller than that assembled by the nodal FEM, which further demonstrates the advantage of our algorithm in terms of computational memory.

LiFePO 4 /carbon nanowires with three-dimensional (3D) nano-network structure were successfully synthesized via evaporative self-assembly method induced by amylose. The morphologies and structures are investigated by X-ray diffractometer, scanning electron microscope and transmission electron microscope. The co-axis one-dimensional LiFePO 4 /C nanowires, which are 50 nm in diameter and between 400 nm and 1 μm in length, are tightly connected into 3D nano-network structure by the amorphous carbon from the short branched chains of amylase. They deliver high capacities of 167 and 138 mA h g −1 at 0.1 C and 50 C respectively. After 100 cycles at 50C rate, the capacity retention of the composite can still maintain 92.8% (128 mA h g −1 ).The unique 3D nano-network structure can effectively increase the contact between active materials and electrolyte, and improve the poor electronic and ionic conductivity.

Silicon/carbon microrods are co-deposited on copper substrate and graphite spheres surface using dimethyl dichlorosilance as carbon and silicon precursor. The obtained composites are characterized by X-ray diffraction and scanning electron microscopy. The experimental results show that silicon/carbon microrods deposited on the copper substrate, whose diameter is about 500 nm, are accumulated into sisallike morphology, those deposited on the graphite spheres surface form hedgehog-like feature, whose diameter is about 200 nm and whose top is like cauliflower. When current density of 50 mA/g is applied, charge capacity of silicon/carbon microrods is 1492 mA h/g (deposited on copper substrate) and 693 mA h/g (deposited on the graphite spheres surface). Moreover, silicon/carbon microrods deposited on the graphite spehres and copper substrate respectively deliver the capacity of 592, 985 mA h/g, and display no capacity decay at all after the 20 cycles, when cycled under current density of 500 mA/g.

LiFePO 4 and LiFePO 4 /C microspheres are successfully synthesized via facile co-precipitation in an elevated temperature oil bath. Their morphologies and structures are investigated by X-ray diffractometer, scanning electron microscope and transmission electron microscope. LiFePO 4 /C microspheres are uniform between 2 and 4 μm in diameter and composed of nanoparticles from 30 to 80 nm in size. Nanoparticles are coated by a thin nano-carbon layer and imbedded into three-dimensional nano-carbon networks. LiFePO 4 /C microspheres exhibit a high tap density (1.82 g cm −3 ), deliver large reversible discharge capacity of 165 mA h g −1 at 0.1C rate, excellent rate capability of 106 mA h g −1 at 50C rate, and capacity retention over 98% after 20 cycles even applied 50C rate. Therefore, the material is a potential candidate for high-power lithium ion batteries.

LiFePO4/C nanowires were successfully synthesized via evaporated self-assembly assisted by polyvinyl alcohol at room temperature. The structure, morphology, and composition of the as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TG). The experimental results show that LiFePO4/C nanowires are uniform about 50–100 nm in diameter and 1 μm in length. LiFePO4/C nanowires exhibit excellent electrochemical performance and attain the discharge-specific capacity of 155 mAhg−1 at 1C rate and 118 mAhg−1 at 20C rate. The capacity retention is 98 % after 100 cycles at 20C rate.

Urchin-shaped Nb 2 O 5 microspheres have been synthesized through the facile hydrothermal method. Nb 2 O 5 microspheres, wrapped tightly by filaments about 10 nm in diameter and 1.5 μm in length, are about 0.8 μm in diameter. The initial discharge and charge capacities for Nb 2 O 5 microspheres are 480.43 mA h g −1 and 406.80 mA h g −1 at 50 mA g −1 , meanwhile it exhibits the capacity retention of 390.0 mA h g −1 after 200 cycles. The urchin-shaped Nb 2 O 5 microspheres are a potential anode material for lithium ion batteries.

Three-dimensional foam structure LiFePO 4 /C composite has been successfully synthesized via evaporative self-assembly assisted by polyethylene glycol. The morphologies, structures and properties of bare LiFePO 4 and LiFePO 4 /C are investigated by X-ray diffractometer, scanning electron microscope, and transmission electron microscope. LiFePO 4 /C composite exhibits high capacity of 150 mA h g −1 at the 1 C rate, and excellent rate performance (120 mA h g −1 at the 20 C rate). The improved properties can be attributed to a unique three-dimensional foam structure constructed by facile evaporative self-assembly. Furthermore, the unique structure can increase the electrochemical reaction surface, enhance the electrochemical conductivity and promote lithium ion diffusion.