Compatibility of polymer electrolyte based on N-methyl-N-propylpiperidinium bis(trifluoromethanesulphonyl)imide ionic liquid with LiMn₂O₄ cathode in Li-ion batteries

By Swiderska-Mocek, Agnieszka & Naparstek, Dominika
Published in Solid State Ionics NULL 2014

Abstract

LiMn₂O₄ (LMO) was examined as a cathode material for the lithium-ion battery, working together with a polymer electrolyte (PE) based on the PVdF polymer network, MePrPipNTf₂ + LiNTf₂ ionic liquid (MePrPip: N-methyl-N-propylpiperidinium cation, NTf₂ is bis(trifluoromethanesulphonyl)imide anion) and vinylene carbonate (VC) as the SEI forming additive. The polymer electrolyte was prepared by the casting technique. The LiMn₂O₄ cathode in LMO/PE/Li and LMO/PE/Li₄Ti₅O₁₂ (LTO) cells was characterized by scanning electron microscopy (SEM), cyclic sweep voltammetry (CV), electrochemical impedance spectroscopy (EIS), cyclic sweep voltammetry (CV) and galvanostatic charging/discharging. Room temperature ionic conductivity of the LiNTf₂ + MePrPipNTf₂ + PVdF and LiNTf₂ + MePrPipNTf₂ + PVdF + VC polymer electrolytes was 0.46 mS cm⁻¹ and 4.4 mS m⁻¹ , respectively. The LiMn₂O₄ cathode with quaternary PE exhibited a good specific capacity of 117 mAh g⁻¹ and 105 mAh g⁻¹ at low and medium rates. The full LMO/LTO cell using PE as a separator displayed good cycling performances (ca. 103 mAh g⁻¹ after 160 cycles). This result indicates that the non-flammable, quaternary LiNTf₂ + MePrPipNTf₂ + PVdF + VC polymer electrolyte can be safely used in combination with a manganese cathode in Li-ion batteries.

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