Li-doped N-methoxyethyl-N-methylpyrrolidinium fluorosulfonyl-(trifluoromethanesulfonyl)imide as electrolyte for reliable lithium ion batteries

The electrochemical performance of a new electrolyte based on N-methoxyethyl-N-methylpyrrolidinium fluorosulfonyl-(trifluoromethanesulfonyl)imide (PYR12O1FTFSI) doped with LiFTFSI salt has been investigated. The electrolyte showed no evidence of crystalline phases even at low temperatures and possesses high ionic conductivity (3.7 × 10−3 S cm−1 at 20 °C) that makes it suitable for lithium battery applications. The new electrolyte has been tested in combination with aqueous processed, electrode materials such as Li4Ti5O12 and LiFePO4, showing good electrochemical performance even at room temperature. Lab-scale, lithium-ion cells comprising Li4Ti5O12/PYR12O1FTFSI-LiFTFSI/LiFePO4 were also assembled and tested. The cells exhibit stable cycling behavior at room temperature with an energy density of 130 Wh kg−1. Moreover, the cell was cycled at 1C up to 80 °C displays a capacity loss of about 30% but retaining high coulombic efficiency. These results demonstrate the feasibility of PYR12O1FTFSI-based ionic liquids as electrolytes for safer and greener lithium ion batteries with extended operative temperature range.