Effect of Doping Ni on Microstructures and Properties of Coxni1-Xhcf Based Seawater Battery

Abstract

Prussian blue analogues (PBAs) have been proven to be a promising seawater battery cathode due to the accommodation of electrons upon the intercalation of Na+ in seawater. In the current work, Ni-doped cobalt hexacyanoferrate (CoxNi1-xHCF) was fabricated by the method of co-precipitation at room temperature. Results show that with the increase of the molar ratio of Co: Ni, the specific capacity of the cathode initially increases and then decreases. The best battery properties were achieved when the molar ratio of Co: Ni was 1:2. The specific capacity was up to 76.5 mAh·g-1 at 0.1A·g-1, the capacity retention was up to 63.5% at a current density of 10 A·g-1, and the capacity retention of 81% is obtained after 100 cycles. The introduction of Ni2+ increase the specific surface leading to the increase of the active site for the redox reaction. At the same time, the specific capacity was decreased due to the doping Ni. Enhanced electrochemical performance of CoxNi1-xHCF cathode for seawater battery was achieved by considering the synergistic effects of specific surface and element composition. Furthermore, seawater battery were successfully assembled using the Co0.86Ni0.14HCF cathode and Mg anode, which demonstrate promising application of prussian blue analogues in seawater batteries.

Keywords: Cobalt hexacyanoferrate, Ni-doped, seawater battery