1. Introduction
Li-ion batterieswere brought onto the consumermarket by Sony
Corp. in the early 1990s [1]. Desirable characteristics, such as high
energy density, low auto-discharge rate, and high potential dif-
ference, made these batteries preferable to the typical Ni–Cd and
Ni–MH batteries for many applications. Moreover, Li-ion batter-
ies are less harmful to the environment. For Li-ion batteries, the
main materials used are LiCoO2 in the cathode and carbon in the
anode [2]. High potentials obtained with these batteries (approxi-
mately 3.70V) hinder the utilization of aqueous electrolytes so that
a mixture of lithium organic solvents and inorganic salts is usually
required.
Li-ion battery production has been continually increasing since
the 1990s, accompanying the consumption growth of portable
devices (e.g., cellular phones, microcomputers, and toys). World
production of Li-ion batteries increased from 250 to 700 million
units between 1998 and 2004 [3]. Residues generated by Li-ion bat-
teries remained at 200–500 tons year−1 from 2002 to 2006. Cobalt
constitutes between 5 and 20% (m/m) of this residue,while lithium
constitutes 2–5% (m/m) of it [3]. The price of cobalt increased from
$15 to $54 per kilogram between 2003 and 2004 [4]. Li-ion bat-
tery recycling is of great importance for environmental protection;