A polyoxovanadate as an advanced electrode material for supercapacitors.

Polyoxovanadate Na(6)V(10)O(28) is investigated for the first time as electrode material for supercapacitors (SCs). The electrochemical properties of Na(6)V(10)O(28) electrodes are studied in Li(+) -containing organic electrolyte (1 M LiClO(4) in propylene carbonate) by galvanostatic charge/discharge and cyclic voltammetry in a three-electrode configuration. Na(6)V(10)O(28) electrodes exhibit high specific capacitances of up to 354 F g(-1). An asymmetric SC with activated carbon as positive electrode and Na(6)V(10)O(28) as negative electrode is fabricated and exhibits a high energy density of 73 Wh kg(-1) with a power density of 312 W kg(-1), which successfully demonstrates that Na(6)V(10)O(28) is a promising electrode material for high-energy SC applications.

Electrospun hierarchical CaCo2O4 nanofibers with excellent lithium storage properties.

Hierarchical CaCo2O4 nanofibers (denoted as CCO-NFs) with a unique hierarchical structure have been prepared by a facile electrospinning method and subsequent calcination in air. The as-prepared CCO-NFs are composed of well-defined ultrathin nanoplates that arrange themselves in an oriented manner to form one-dimensional (1D) hierarchical structures. The controllable formation process and possible formation mechanism are also discussed. Moreover, as a demonstration of the functional properties of such hierarchical architecture, the 1D hierarchical CCO-NFs were investigated as materials for lithium-ion batteries (LIBs) anode; they not only delivers a high reversible capacity of 650 mAh g(-1) at a current of 100 mA g(-1) and with 99.6% capacity retention over 60 cycles, but they also show excellent rate capability with respect to counterpart nanoplates-in-nanofibers and nanoplates. The high specific surface areas as well as the unique feature of hierarchical structures are probably responsible for the enhanced electrochemical performance. Considering their facile preparation and good lithium storage properties, 1D hierarchical CCO-NFs will hold promise in practical LIBs.

Electrospun porous NiCo2O4 nanotubes as advanced electrodes for electrochemical capacitors.

Novel, porous NiCo2O4 nanotubes (NCO-NTs) are prepared by a single-spinneret electrospinning technique followed by calcination in air. The obtained NCO-NTs display a one-dimensional architecture with a porous structure and hollow interiors. The effect of precursor concentration on the morphologies of the products is investigated. Due to their unique structure, the prepared NCO-NT electrode exhibits a high specific capacitance (1647 F g(-1) at 1 A g(-1)), excellent rate capability (77.3 % capacity retention at 25 A g(-1)), and outstanding cycling stability (6.4 % loss after 3000 cycles), which indicates it has great potential for high-performance electrochemical capacitors. The desirable enhanced capacitive performance of NCO-NTs can be attributed to the relatively large specific surface area of these porous and hollow one-dimensional nanostructures.