Journal of Applied Electrochemistry, Vol.41, No.2, 241-247, 2011
Electrochemical investigation of Al-Li/Li (x) FePO4 cells in oligo(ethylene glycol) dimethyl ether/LiPF6
1 M LiPF6 dissolved in oligo(ethylene glycol) dimethyl ether with a molecular weight, 500 g mol(-1) (OEGDME500, 1 M LiPF6), was investigated as an electrolyte in experimental Al-Li/LiFePO4 cells. More than 60 cycles were achieved using this electrolyte in a Li-ion cell with an Al-Li alloy as an anode sandwiched between two Li (x) FePO4 electrodes (cathodes). Charging efficiencies of 96-100% and energy efficiencies of 86-89% were maintained during 60 cycles at low current densities. A theoretical investigation revealed that the specific energy can be increased up to 15% if conventional LiC6 anodes are replaced by Al-Li alloy electrodes. The specific energy and the energy density were calculated as a function of the active mass per electrode surface (charge density). The results reveal that for a charge density of 4 mAh cm(-2) about 160 mWh g(-1) can be reached with Al-Li/LiFePO4 batteries. Power limiting diffusion processes are discussed, and the power capability of Al-Li/LiFePO4 cells was experimentally evaluated using conventional electrolytes.
Keywords:Al-Li alloy anode;Oligo(ethylene glycol);Al-Li/FePO4 cells;Specific energy;Li diffusion in Al