Insight into the Characterization of Sea-Salt Batteries

Abstract

Batteries are one of the main tools to provide the flexibility distribution and transmission systems need due to their increasing dependence on weather conditions. However, environmental and economic factors pose a significant problem. New types of batteries that do not rely on rare earth metals and organic solvents but instead use water and more common ions could be a cost-effective and environmentally safe way to provide energy storage in the future. We studied the performance of sea-salt cells designed as a low-cost, environmentally friendly method to store electricity. We used a constant current charge/discharge test with different currents, from 50 mA to 300 mA, to identify the maximum efficiencies of the cell. Then, we introduced a new strategy to determine the cut-off voltage to discharge the battery, inspired by the maximum power point found in photovoltaics. We used a constant voltage charge to determine the cell’s energy density. However, evidence of side reactions urged us to use constant current charge/discharge tests to identify the battery’s capacity based on the efficiencies drop. Results showed a maximum energy efficiency of 74.6% at 200 mA and a maximum Coulombic efficiency of 88.7% at 300 mA. The cut-off voltage of the cell during discharge should be between 1.4 V and 1.6 V. The energy densities range from 10.1 Wh/kg(6.53 WhL) with an efficiency of 57.5% and 4.18 Wh/kg(2.7 WhL) with an efficiency of 69.8%.