ABSTRACT
Batteries can be defined as “devices to produce directly the chemical,
physical, and biological change of composed materials as the
electrical energy.” They fall into three kinds, that is, chemical,
physical, and biological batteries, as in Fig. 3.1. A chemical battery
can produce electrical energy by a chemical reaction in the cell.
A physical battery can convert light and thermal energies into
electrical energy without a chemical reaction. A biological battery
can produce electrical energy by a biochemical change using a
biocatalyst and a microorganism. Among them, we usually call
chemical batteries such as a dry cell battery and a storage
battery used in social life as batteries. Added to this, chemical
batteries are grouped into a dischargeable primary battery, a
charge/dischargeable second battery, and a fuel cell that can be a
future electronic source. Cobalt oxides are actively involved in a
second battery and a fuel cell, which are introduced in this chapter
and Chapter 10, respectively.
