Hailong Fei

Hierarchical LiFePO4 with a controllable growth of the (010) facet for lithium-ion batteries

Hierarchically structured LiFePO4 was successfully synthesized by ionic liquid solvothermal method. These hierarchically structured LiFePO4 samples were constructed from nanostructured platelets with their (010) facets mainly exposed. To the best of our knowledge, facet control of a hierarchical LiFePO4 crystal has not been reported yet. Based on a series of experimental results, a tentative mechanism for the formation of these hierarchical structures was proposed. After these hierarchically structured LiFePO4 samples were coated with a thin carbon layer and used as cathode materials for lithium-ion batteries, they exhibited excellent high-rate discharge capability and cycling stability. For instance, a capacity of 95% can be maintained for the LiFePO4 sample at a rate as high as 20 C, even after 1000 cycles.

Facile synthesis of V6O13 micro-flowers for Li-ion and Na-ion battery cathodes with good cycling performance.

A simple and versatile method for the preparation of V6O13 microflowers is developed via a simple hydrothermal route with the aid of an alkali metal nitrate salt, which has important effects on the formation of V6O13. It is found that V6O13 microflowers display good cycling stability as cathode materials for lithium-ion battery. In addition, they show high capacities for sodium-ion battery. We have V6O13 microflowers discharge capacities up to 225.7 mA h g(-1) for sodium-ion battery. The reason may be the fewer phase transitions occurring upon lithium and sodium insertion for phase-unpure V6O13 microflowers.

Novel sodium intercalated (NH4)2V6O16 platelets: High performance cathode materials for lithium-ion battery.

A simple and versatile method for preparation of novel sodium intercalated (NH4)2V6O16 is developed via a simple hydrothermal route. It is found that ammonium sodium vanadium bronze displays higher discharge capacity and better rate cyclic stability than ammonium vanadium bronze as lithium-ion battery cathode material because of smaller charge transfer resistance, which would favor superior discharge capacity and rate performance.

Flaky CoS2 and graphene nanocomposite anode materials for sodium-ion batteries with improved performance

A flaky CoS2 based reduced graphene oxide (CoS2/rGO) composite was successfully synthesized via a solvothermal route. CoS2 nanoparticles with sizes of 20–30 nm are uniformly anchored on the reduced graphene oxide (rGO), resulting in the flaky structure. The as-fabricated CoS2 based rGO composite exhibits improved sodium storage capacity compared with bare CoS2 as anode materials for sodium-ion batteries. After cycling for 1000 cycles at 1 A g−1, the CoS2 based rGO electrode still delivered a reversible capacity of 192 mA h g−1. The enhanced electrochemical performances of the CoS2 based rGO composite can be ascribed to the formation of a robust, conductive and high surface area composite.

Facile synthesis of Li2MnO3 nanowires for lithium-ion battery cathodes

In the present work, Li2MnO3 nanowires with a good electrochemical performance were synthesized by a simple molten-salt method, at a low temperature, using Mn2O3 nanowires with MnF2 as the Mn source. The discharge capacity of the Li2MnO3 nanowires used as the cathode material in a lithium-ion battery was up to 159.8 mA h g−1 after 27 cycles in a voltage range of 2.0 to 4.8 V at a current density of 20 mA g−1 at room temperature. They also displayed a good cycling stability and rate performance at different current densities.

Enhanced electrochemical performance of ammonium vanadium bronze through sodium cation intercalation and optimization of electrolyte

A new type of platelet-like ammonium vanadium bronze (NH4)2V6O16 is first used as cathode material for Na-ion battery. The discharge capacity and cycling stability is improved by the intercalation of Na(+) and using NaPF6 as electrolyte. Raman spectrum shows that the crystalline structure of (NH4)2V6O16 is changed after the intercalation of Na(+) to (NH4)2V6O16. Furthermore, the obtained sodium ammonium vanadium bronze shows smaller charge transfer resistance than (NH4)2V6O16, which would favor superior discharge capacity and good cycling stability. Additionally, NaPF6 is prior to NaClO4 as electrolyte for ammonium vanadium bronze cathode materials.

Zinc pyridinedicarboxylate micro-nanostructures: Promising anode materials for lithium-ion batteries with excellent cycling performance.

It is important to discover new, cheap and environmental friendly coordination polymer electrode materials for lithium-ion batteries. Zinc 2,6-pyridilinedicarboxylate particles show better cycling stability and higher discharge capacity than 2,5-pyridilinedicarboxylate micro-platelets when they are firstly tested as anode materials for lithium-ion batteries. The former can steadily cycle at current densities of 750, 1000 and 2000mAg(-1). It is also stable in multiple insertion/extraction processes at current densities of 750, 1500, 2000, 2500, 3000, and 750mAg(-1), and the capacity retention is 77.9% after 60cycles. While the latter is apt to show good cycling performance at smaller discharge current density.