Page 110 - Handbook of Battery Materials

76 2 Practical Batteries

Safety vent
Positive cap
PTC device
Gasket
Separator

Casing
(negative terminal) Negative electrode

Positive electrode Negative current collector
Figure 2.63 Structure of a lithium-ion battery. PTC, positive thermal coefficient device.

5

4
Voltage (V) 3 2

1

0
0 100 200 300 400 500 600
Discharge capacity (mAh/g)
Figure 2.64 Discharge characteristic of an LiCoO 2 /coke cell.

As mentioned above, the typical positive electrode material is LiCoO 2 , and there
are typically two types of negative electrode materials, such as coke and graphite. The
characteristics of lithium-ion batteries constructed using these electrode materials
are discussed below.
Figure 2.64 shows the discharge characteristics of a cylindrical type LiCoO 2 –coke
cell. The discharge capacity is 350 mAh, the average discharge voltage is 3.6 V, and
−1
the energy density of this battery is 164 Wh L −1 or 66 Wh kg . The cell voltage
of this battery decreased greatly during discharge. This feature is not favorable
from the viewpoint of total energy density, but it is easy to determine the residual
capacity from the cell voltage [82].