Electrochemical properties of environment-friendly lithium-tin liquid metal battery

A Li/LiF-LiCl-LiBr/Sn battery cell is prepared for the first time to investigate the feasibility of pure tin metal as an environmentally friendly cathode material in the liquid metal battery. The Li-Sn cell can achieve the mean voltages of 0.820 and 0.607 V during charge and discharge at 100 mA cm−2, respectively. Increasing the discharge current density from 100 to 700 mA cm−2 results in 1.3% capacity loss, and the capacity loss is 12.4% when the charge current density increased from 100 to 1000 mA cm−2. This high rate capability of the cell is due to ultrafast charge-transfer kinetics at the interface of liquid electrode and liquid electrolyte. The Li-Sn cell exhibits a capacity retention of 94.0% after 220 cycles. The capacity loss originates from the loss of active Sn by forming SnFe and CrSn2 intermetallics in side reaction between the Sn and stainless steel case, and these intermetallics are inert to lithium within the voltage window of 0.5–1.2 V.