In situ polyaniline coating of Prussian blue as cathode material for sodium-ion battery

Prussian blue has great potential for using as a sodium cathode material
owing to its high working potential and cube frame structure. Herein, this
work reports a two-step method to synthesize Prussian blue with ascorbic
acid (AA) as the ball-milling additive, which improves electrochemical
rate performance of Prussian blue during the traditional co-precipitation
method. The obtained Prussian blue sample exhibited a superior specific
capability (113.3 mAh g-1 even at 20 C, 1 C=170 mA g-1) and a specific
capacity retention of 84.8% after 100 cycles at 1 C rate. In order to
enhance the cycling performance of the Prussian blue, an in situ
polyaniline (PANI) coating strategy was employed in which aniline was
added into the electrolyte and polymerized under electrochemical
conditions. The coated anode exhibited a high specific capacity retention
of 62.7% after 500 cycles, which is significantly higher than that of the
non-coated sample which only remains 40.1% after 500 cycles. This
development has shown a great potential as a low-cost, high-performance
and environmental-friendly technology for large-scale industrial
application of PB.