Fe(CN)6-4-doped polypyrrole: a high-capacity and high-rate cathode material for sodium-ion batteries

A redox-active Fe(CN)(6)(-4)-doped polypyrrole was synthesized and found to have a remarkable redox capacity of 135 mA h g(-1) in Na+ electrolyte, an excellent rate capability of 1600 mA g(-1) and a strong capacity retention of 85% over 100 cycles, showing great promise for enabling low-cost and environmentally benign Naion batteries for large-scale electric energy storage.