No abstract

The surface pseudocapacitance contribution is dominant in Na+ storage processes in favour of the high rate performance of Fe3BO5.

In this work, a flake-structured Co 2 B 2 O 5 material was obtained by a simple sol-gel method and researched for use in sodium ion batteries firstly. When serving as anode material for sodium ion batteries, it exhibits the high initial reversible capacity of 466 mAhÁg -1 at a current density of 100 mAÁg -1 . Through the recombination of carbon nanotubes (CNTs), the composite Co 2 B 2 O 5 /CNTs delivers the initial reversible capacity of 464 mAhÁg -1 , and 324 mAhÁg -1 is obtained after 60 cycles under the current density of 100 mAÁg -1 . When under the current density of 1000 mAÁg -1 , a capacity of 236 mAhÁg -1 is obtained for Co 2 B 2 O 5 /CNTs while 160 mAhÁg -1 for Co 2 B 2 O 5 . Moreover, the sodium storage behavior of Co 2 B 2 O 5 is identified by kinetic analysis. The higher Na ? capacitive contribution of Co 2 B 2 O 5 /CNTs could account for the enhanced rate performance. The results indicate that Co 2 B 2 O 5 is a promising anode material for sodium ion batteries.

The hierarchical TiO2/C microspheres were obtained via a facile method of in-situ hydrolysis and spray drying. Antase TiO2 nanoparticles were coherent to microspheres TiO2/C due to the pyrolysis of carbon source (PVP). Besides, the favorable electron transfer from carbon to TiO2 improves the electronic conductivity of TiO2 via the presence of Ti–C bond within TiO2/C composite. Charge-discharge tests show that TiO2/C microspheres delivered a good rate capability of 106.1[Formula: see text]mAh[Formula: see text]g[Formula: see text] at the high current density of 5[Formula: see text]A[Formula: see text]g[Formula: see text] and an enhanced cyclic capacity. The superior electrochemical performance could be ascribed to the porous micro–nano structure, smaller crystal size and increased conductivity. The synthesis of TiO2/C microspheres is easy to scale up for satisfying high-performance sodium storage.