Page 112 - Handbook of Battery Materials

78 2 Practical Batteries

−1
energy density of this battery is 294 Wh L −1 or 122 Wh kg . The energy density
of this battery is higher than that of the LiCoO 2 -coke cell, and its decrease in cell
voltage was small during discharge, which is favorable from the viewpoint of total
energy density.
These features are caused by the graphite negative electrode. The LiCoO 2 -graphite
system is superior to LiCoO 2 -coke in energy density and charge–discharge charac-
teristics [83].
As the cost of LiCoO 2 is high, other positive electrode materials will eventually
take the place of LiCoO 2 . LiNiO 2 and LiMnO 2 are often mentioned as positive
electrode materials instead of LiCoO 2 [84]. LiNiO 2 is desirable because it offers a
larger capacity and lower cost than LiCoO 2 , and it is expected that a LiNiO 2 -graphite
cell will be commercialized in the near future.

2.8
Secondary Lithium Batteries with Metal Anodes

Secondary lithium-metal batteries which have a lithium-metal anode are attractive
because their energy density is theoretically higher than that of lithium-ion bat-
teries. Lithium–molybdenum disulfide batteries were the world’s first secondary
cylindrical lithium-metal batteries. However, the batteries were recalled in 1989
because of an overheating defect. Lithium–manganese dioxide batteries are the
only secondary cylindrical lithium–metal batteries which are manufactured at
present. Lithium–vanadium oxide batteries are being researched and developed.
Furthermore, electrolytes, electrolyte additives, and lithium surface treatments are
being studied to improve safety and rechargeability.
Li–MoS 2 batteries were developed by Moli Energy; lithium is intercalated into the
positive MoS 2 material. The value of x can vary from about 0.2 for a fully charged
battery to about 1.0 for a fully discharged battery in accordance with reaction:
(2.19)
xLi + MoS 2 → Li x MoS 2
Products include an AA-size battery, a C-size battery, and a developmental butylene
carbonate (BC)-size (diameter 66 mm, height 152 mm) battery with a nominal 65
Ah capacity. The features of these batteries are a long charge-retention time, a
direct state-of-charge indicator based on a variable open-circuit voltage, a high
energy density relative to that of other rechargeable batteries, and a high power
density [85].
A new rechargeable Li-Li x MnO 2 3 V battery system was developed by Tadiran
Ltd. The active material of the negative electrode is lithium metal, and that of the
positive electrode is lithiated manganese dioxide. These batteries have an organic
electrolyte and separator, and exhibit excellent performance and safe behavior. The
capacity of the AA–size battery is 800−750 mAh, and the energy density is 125–145
−1
Wh kg −1 or 280–315 Wh L . At charging regimes around C/10, more than 350
cycles at 100% DOD could be obtained. An accumulated capacity of about 200 Ah
can be achieved under cycling [86].