Wide-temperature electrolyte for advanced Mn metal batteries

The electrolyte enables reversible Mn plating/stripping from −20 to 120 °C. • A minimum overpotential of 50 mV is achieved for Mn plating/stripping. • Near-integral Coulombic efficiency (99.2–100.3%) is realized in asymmetric cells. • The Mn metal batteries deliver a long cycling life of over 7000 cycles. Mn metal batteries (MnMBs) have attracted widespread attention due to distinct merits of Mn anode on energy-to-price ratio, volumetric capacity and redox potential. However, most MnMBs can only be operated around room temperature, largely constraining their potential application scenarios. In this work, a wide-temperature non-aqueous electrolyte, comprising wide-liquid-range solvents [tetramethylene sulfone (26–285 °C); diglyme (−64–162 °C)] and hybrid solutes (MnCl 2 -AlCl 3 -Mn(TFSI) 2 ), is proposed as the first electrolyte enabling MnMBs to work at −20 to 120 °C. Benefitting from superior stability and high ionic conductivity, the resultant electrolyte allows reversible and dendrite-free Mn plating/stripping with overpotential controlled as low as 50 mV, representing a record in MnMBs. Near integral Coulombic efficiency of Mn plating/stripping is realized in asymmetric Mn cells under different areal capacities. As consequences, the assembled MnMBs show a high average output voltage, a long cycling life of >7000 cycles and wide operation temperature. The wide-temperature electrolyte offers a pathway for designing advanced MnMBs for diverse application scenarios. Download: Download high-res image (183KB) Download: Download full-size image