Magnesium-ion-conducting solid polymer electrolytes have been studied for rechargeable Mg metal batteries,one of the beyond-Li-ion systems.In this paper,magnesium polymer electrolytes with magnesium bis(trifluorometha...Magnesium-ion-conducting solid polymer electrolytes have been studied for rechargeable Mg metal batteries,one of the beyond-Li-ion systems.In this paper,magnesium polymer electrolytes with magnesium bis(trifluoromethane)sulfonimide(Mg(TFSI)2)salt in poly(ε-caprolactone-co-trimethylene carbonate)(PCL-PTMC)were investigated and compared with the poly(ethylene oxide)(PEO)analogs.Both thermal properties and vibrational spectroscopy indicated that the total ion conduction in the PEO electrolytes was dominated by the anion conduction due to strong polymer coordination with fully dissociated Mg2+.On the other hand,in PCL-PTMC electrolytes,there is relatively weaker polymer–cation coordination and increased anion–cation coordination.Sporadic Mg-and F-rich particles were observed on the Cu electrodes after polarization tests in Cu|Mg cells with PCL-PTMC electrolyte,suggesting that Mg was conducted in the ion complex form(MgxTFSIy)to the copper working electrode to be reduced which resulted in anion decomposition.However,the Mg metal deposition/stripping was not favorable with either Mg(TFSI)2 in PCL-PTMC or Mg(TFSI)2 in PEO,which inhibited quantitative analysis of magnesium conduction.A remaining challenge is thus to accurately assess transport numbers in these systems.展开更多
基金We thank Prof.Ruilan Guo for DSC instrumentation and Tatyana Orlova and the University of Notre Dame Integrated Imaging Facilities for SEM.JM,GH,and RA acknowledge the financial support from STandUP for Energy.JLS,BP,and JL acknowledge the partial financial support from NSF CBET-1706370.
文摘Magnesium-ion-conducting solid polymer electrolytes have been studied for rechargeable Mg metal batteries,one of the beyond-Li-ion systems.In this paper,magnesium polymer electrolytes with magnesium bis(trifluoromethane)sulfonimide(Mg(TFSI)2)salt in poly(ε-caprolactone-co-trimethylene carbonate)(PCL-PTMC)were investigated and compared with the poly(ethylene oxide)(PEO)analogs.Both thermal properties and vibrational spectroscopy indicated that the total ion conduction in the PEO electrolytes was dominated by the anion conduction due to strong polymer coordination with fully dissociated Mg2+.On the other hand,in PCL-PTMC electrolytes,there is relatively weaker polymer–cation coordination and increased anion–cation coordination.Sporadic Mg-and F-rich particles were observed on the Cu electrodes after polarization tests in Cu|Mg cells with PCL-PTMC electrolyte,suggesting that Mg was conducted in the ion complex form(MgxTFSIy)to the copper working electrode to be reduced which resulted in anion decomposition.However,the Mg metal deposition/stripping was not favorable with either Mg(TFSI)2 in PCL-PTMC or Mg(TFSI)2 in PEO,which inhibited quantitative analysis of magnesium conduction.A remaining challenge is thus to accurately assess transport numbers in these systems.
