Low-Cost and Scalable Ni-Prussian Blue Analogue//Functionalized Carbon Based Na-Ion Systems for all Climate Operations

Herein, we have developed a sodium ion based aqueous energy storage device with nickel prussian-blue-analogue (Ni-PBA) positive and functionalized carbon-black negative electrodes in 1 M Na₂SO₄ electrolyte solution. The components required to develop the device, i. e., stainless steel (SS) current-collectors, absorbent-glass-mat separator, electrolyte, carbon-black, and precursors of Ni-PBA, are all environmentally benign and inexpensive. To minimize the corrosion of pristine-SS, polyaniline coating on the SS surface is applied by in situ electrodeposition method. The full cell exhibits a specific capacity of 28 mAh g⁻¹ with 90 % Coulomb efficiency (@0.2C), an energy density of 34 Wh kg⁻¹ (@20 W kg⁻¹), a power density of 100 W kg⁻¹ (@18 Wh kg⁻¹) and a good life cycle (70 % capacity-retention over 500 cycles @1.0C rate) within the 0–1.2 V window. The cell performance is further tested under variable temperatures, and 0–50 °C range is reported to be the working window for this cell.