2 research outputs found
Polyaniline/Polyoxometalate Hybrid Nanofibers as Cathode for Lithium Ion Batteries with Improved Lithium Storage Capacity
Hybrid nanofibers of polyaniline/polyoxometalate
are synthesized
via a facile interfacial polymerization method for the first time,
and evaluated as a cathode material for lithium ion batteries. The
hybrid nanofibers with 100 nm diameter consisted of phosphomolybdic
acid polyanion, [PMo<sub>12</sub>O<sub>40</sub>]<sup>3–</sup>, and polyaniline matrix. Their 1D geometry improves the utilization
of electrode materials and accommodates the volume change during cycling,
which enables the significant improvement in lithium storage capacity
and capacity retentions. The phosphomolybdic acid polyanions not only
exhibit a large theoretical capacity of about 270 mAh g<sup>–1</sup>, but also reduce the charge transfer resistance of electrode leading
to the enhanced reversible capacity and rate capability. The polyaniline/polyoxometalate
nanofibers delivered a remarkably improved electrochemical performance
in terms of lithium storage capacity (183.4 mAh g<sup>–1</sup> at 0.1C rate), cycling stability (80.7% capacity retention after
50 cycles), and rate capability (94.2 mAh g<sup>–1</sup> at
2C rate) compared to polyaniline nanofibers and bulk polyaniline/polyoxometalate
hybrid
Dominant Factors Governing the Rate Capability of a TiO<sub>2</sub> Nanotube Anode for High Power Lithium Ion Batteries
Titanium dioxide (TiO<sub>2</sub>) is one of the most promising anode materials for lithium ion batteries due to low cost and structural stability during Li insertion/extraction. However, its poor rate capability limits its practical use. Although various approaches have been explored to overcome this problem, previous reports have mainly focused on the enhancement of both the electronic conductivity and the kinetic associated with lithium in the composite film of active material/conducting agent/binder. Here, we systematically explore the effect of the contact resistance between a current collector and a composite film of active material/conducting agent/binder on the rate capability of a TiO<sub>2</sub>-based electrode. The vertically aligned TiO<sub>2</sub> nanotubes arrays, directly grown on the current collector, with sealed cap and unsealed cap, and conventional randomly oriented TiO<sub>2</sub> nanotubes electrodes were prepared for this study. The vertically aligned TiO<sub>2</sub> nanotubes array electrode with unsealed cap showed superior performance with six times higher capacity at 10 C rate compared to conventional randomly oriented TiO<sub>2</sub> nanotubes electrode with 10 wt % conducting agent. On the basis of the detailed experimental results and associated theoretical analysis, we demonstrate that the reduction of the contact resistance between electrode and current collector plays an important role in improving the electronic conductivity of the overall electrode system