The cycle behaviour and rate performance of solid-state Li/LiFePO4polymer electrolyte batteries incorporating the N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR13TFSI) room temperature ionic liquid (IL) into the P(EO)20LiTFSI electrolyte and the cathode have been investigated at 40 °C. The ionic conductivity of the P(EO)20LiTFSI + PYR13TFSI polymer electrolyte was about 6 × 10-4S cm-1at 40 °C for a PYR13+/Li+mole ratio of 1.73. Li/LiFePO4batteries retained about 86% of their initial discharge capacity (127 mAh g-1) after 240 continuous cycles and showed excellent reversible cyclability with a capacity fade lower than 0.06% per cycle over about 500 cycles at various current densities. In addition, the Li/LiFePO4batteries exhibited some discharge capability at high currents up to 1.52 mA cm-2(2 C) at 40 °C which is very significant for a lithium metal-polymer electrolyte (solvent-free) battery systems. The addition of the IL to lithium metal-polymer electrolyte batteries has resulted in a very promising improvement in performance at moderate temperatures. © 2005 Elsevier B.V. All rights reserved.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Energy Engineering and Power Technology
- Physical and Theoretical Chemistry
- Electrical and Electronic Engineering