Continuous and self-charging electricity generator based on saltwater

In the field of energy harvesting and storage techniques, extensive efforts have been made to utilize abundant seawater on earth as an eco-friendly energy source. However, seawater-based energy harvesting methods are sensitive to environmental conditions, causing problems in sustainable energy production. Meanwhile, similar to common batteries, seawater-based batteries require external energy sources for charging and recharging. Therefore, developing seawater-based electricity devices that can produce energy continuously irrespective of environmental conditions and without external energy sources remains a great challenge. Herein, we developed a saltwater-based electricity generator (SWEG) using carbon nanotube and graphene oxide as electrodes, which can produce electricity sustainably and self-recharge without the need for any external energy sources after discharging the stored energy. The proposed SWEG generates a stable open-circuit voltage of ∼ 300 mV. After being fully discharged at a high current density (0.5 µA cm−2), the voltage can be recovered in 2 h. At moderate discharge current density (0.1 µA cm−2), considerable voltage is maintained for 24 h. This continuous energy generation was aroused from the ion-redistribution between the surface of electrodes and the electrolyte of salt water. Our results demonstrate the feasibility of self-charging and continuous electricity generation without the constraint of atmospheric conditions.