In this paper we examine the influence of various mixed-solvent electr
olytes on the discharge capacity and charge-discharge cycle life of co
in-type lithium (Li) metal/amorphous (a-) V2O5-P2O5 (95:5 in molar rat
io) cells. The solvents used were ethylene carbonate (EC), propylene c
arbonate (PC), 2-methyl-tetrahydrofuran (2MeTHF), THF, 1,2-diethoxyeth
ane and 4-methyl-1,3-dioxolane, LiAsF6 and LiCF3SO3 were used as the s
olute. The electrolyte solutions examined here contain binary, ternary
and quaternary mixed solvent systems. The purpose of this work is to
obtain an electrolyte solution which provides lithium cells with a hig
her rate capability than the previously studied EC/PC/2MeTHF ternary m
ixed system while suppressing the reduction in the cycle life. The sta
ck pressure effect on the lithium cycling efficiency is minimized by t
he spacious internal electrode structure of the coin cell used in this
work in order to investigate the influence of the electrolyte materia
ls on the cell properties. Among the electrolyte systems examined here
, the EC/PC/2MeTHF/THF (15:70:7.5:7.5 in volume) four-solvent mixed sy
stem provided the best cell performance. Its rate capability at 5 mA c
m(-2) discharge was about twice that of EC/PC/2MeTHF ternary mixed sol
vent electrolyte with almost the same rechargeability. (C) 1997 Elsevi
er Science Ltd. All rights reserved.