An ultra-high special energy Mg-Ni seawater battery

Seawater batteries with natural seawater as the electrolyte have drawn significant attention due to their advantages of low cost, environmental friendliness, and high theoretical energy density. Herein, an Mg-Ni seawater battery consisting of a magnesium anode and a carbon-loaded nickel foam cathode is developed, which exhibits excellent discharge performance with an ultra-high specific capacity of 1500 mAh g⁻¹ and discharge voltage kept above 1.28 V at the current density of 1 mA cm⁻² after stable discharge of 100 h. Moreover, the specific energy of the Mg-Ni seawater battery reaches a competitive value of 1950 Wh kg⁻¹.