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13
Rechargeable Lithium Anodes

Jun-ichi Yamaki and Shin-ichi Tobishima

13.1
Introduction

The need to increase the energy density of rechargeable cells has become more
urgent as a result of the recent rapid development of new applications, such as
electric vehicles, load leveling, and various types of portable equipment, including
personal computers, cellular phones, and camcorders. For these practical applica-
tions, lithium ion cells have been used since 1991. Many commercial lithium ion
cells are composed of a carbon anode and an LiCoO 2 cathode with nonaqueous elec-
trolyte solutions. However, the capacity of carbon anodes is now getting closer to
−1
the theoretical value (372 mAh g ). Moreover, new anode materials having higher
energy density than carbon have been studied. A lithium-metal anode is an attrac-
tive way of delivering the high energy density from such cells. The lithium-metal
−1
anode has a very large theoretical capacity of 3860 mAh g , in contrast to the
−1
value of 372 mAh g for an LiC 6 carbon anode. This high energy encourages an
attempt to realize a practical lithium-metal anode cell. As an example of these
applications requiring supremely high energy density cells, there is a project of
New Energy and the Industrial Technology Development Organization (NEDO)
in Japan. This project started in 2007. One of the targets of this project is to
realize battery packs (not cells) having an energy density exceeding 700 Wh kg −1
for future electric vehicles. This value is about 10 times greater than that of present
commercial lithium ion cells. In this project, many studies on new high-energy
systems have been carried out including lithium metal anode air-rechargeable
batteries.
Primary lithium metal cells, including cylindrical and coin-type cells, have been
manufactured as high-energy cells since 1973 (Panasonic, Li/polyfluorocarbon
cell). In addition, several small rechargeable coin-type cells have appeared on the
market (cell capacity < 100 mAh), which are generally categorized as lithium cells.
These small rechargeable cells do not employ pure lithium metal as their anode, but
have anodes of lithium-metal alloys (Table 13.1). Cells with lithium-ion-inserted
compounds have been commercialized more recently (Table 13.2). In spite of their
lower energy density, these alternative anodes are used because pure lithium tends

Handbook of Battery Materials, Second Edition. Edited by Claus Daniel and J¨ urgen O. Besenhard.
 2011 Wiley-VCH Verlag GmbH & Co. KGaA. Published 2011 by Wiley-VCH Verlag GmbH & Co. KGaA.