Sn foil as the cathode for a reversible 2.8 V Sn-Li battery

Abstract

Tin (Sn) is a common metal in our daily life. Recently, Sn and its alloys have received much interest as anode materials for lithium-ion batteries. Herein, we are the first to demonstrate a Sn–Li battery using Sn metal as the cathode and Li metal as the anode in a carbonate–ether based electrolyte. The Sn–Li battery uses electrochemical redox reactions of the two metal/metal cation pairs to store and release energy. With an anion exchange membrane as the separator, the battery can cycle at a current density of 0.2 mA cm⁻² with an areal capacity limitation of 0.1 mA h cm⁻² and a discharge voltage of about 2.8 V for more than 1500 cycles with an average Coulombic efficiency of about 99.5%. The discharge voltage plateau of the Sn–Li battery drops by only 0.05 V even when the current density is increased 5 times to 1 mA cm⁻² (about a 10C rate), demonstrating its fast kinetics. Comparing batteries with Sn, Cu and Ni cathodes, the ones with Sn and Cu show lower activation energy for the redox reaction and smaller polarization than that with Ni. On the other hand, Sn and Ni show higher average Coulombic efficiency than that of Cu, suggesting smaller permeability of Sn²⁺ and Ni²⁺ than Cu⁺ through the PIL/PP membrane. Overall, Sn shows better performance over Cu and Ni as the cathode material for metal–metal batteries.