Page 406 - Handbook of Battery Materials

378 13 Rechargeable Lithium Anodes

Table 13.1 Commercially available rechargeable coin-type cells with lithium-metal alloys.

Anode Cathode Cell voltage Main Manufacturer
(V) application

Pb–Cd–Bi–Sn(−Li) Carbon 3 Memory backup Panasonic
Li–Al c-V 2 O 5 3 Memory backup Panasonic
Li–Al–Mn Li 2 MnO 3 + γ -β-MnO 2 3 Memory backup Sanyo
Li–Al Polyaniline 3 Memory backup Seiko/
Bridgestone

Abbreviation:c-V 2 O 5 , crystalline V 2 O 5 .

Table 13.2 Commercially available rechargeable coin-type
cells with lithium-ion inserted anodes.

Anode Cathode Cell voltage Main application Manufacturer
(V)

Li x Nb 2 O 5 c-V 2 O 5 1.5 Watches Panasonic
1.5 Watches Panasonic
Li x TiO 2 Li x MnO 2
Carbon (−Li) c-V 2 O 5 3 Memory backup Toshiba
Polyacenic Polyacenic semi- 2 Memory backup Kanebo
semiconductor (−Li) conductor (−Li)
Carbon (−Li) Li x Ti y O z 1.5 Memory backup Hitachi Maxell

Abbreviation:c-V 2 O 5 , crystalline V 2 O 5 .

to be deposited on the anode in dendritic form when the cell is charged. These
dendrites may cause an internal short as well as a decrease in lithium cycling
efficiency.
The alternative alloy anodes, which exhibit good cycle life in coin cells (Table 13.1),
are not applied to cylindrical cells. This is because they are brittle, and these alloy
anodes turn into fine particles after cycling when the anode is spirally wound in
the cylindrical cell. Cylindrical rechargeable lithium-metal cells, such as AA-size
cells, are not yet commercially available. Several prototype AA cells with pure
lithium anodes have been developed since late 1980 (Table 13.3). However, their
cycle life depends on the discharge and charge currents. This problem results from
the low cycling efficiency of lithium anodes. Another big problem is the safety
of lithium-metal cells. Reasons for their poor thermal stability include the high
◦
reactivity and low melting point (180 C) of lithium.
Nippon Telegraph and Telephone Corporation (NTT) has developed a prototype
AA-size lithium-metal anode cell [1] with an amorphous V 2 O 5 cathode. The energy
of this cell is 2 Wh, which is higher than the value of 1.8 Wh for a lithium-ion cell
with an LiCoO 2 cathode. (The estimated value for an AA-size lithium-metal cell