Introduction to chemical power supply

As a chemical power source, batteries have become a necessity in people's daily life
.

Hand-held mobile phones (cell phones), remote controls, electronic watches, etc.

1.
Zinc Hammer Battery

Zinc-manganese battery is an earlier battery used by people
.

As shown in Figure 8-6, the center is a positive electrode graphite rod with MnO ₂ around it ; the outer negative electrode is zinc skin, and the paste-like NH ₄ CI, ZnCl ₂ and starch mixture are placed between the two electrodes

The electrode reaction of zinc-manganese battery is

Positive 2NH _.
4 ⁺ + 2E ^- = 2NH _.
3 + H ₂

= A Zn negative electrode a Zn ²⁺ + 2E ^-

Figure 8-6 Schematic diagram of zinc-manganese battery

1.

Zinc bark; 2.

The function of MnO ₂ is to remove the generated H ₂

H ₂ +2MnO ₂ =Mn ₂ O ₃ +H ₂ O

The product Mn ₂ O ₃ can be written as MnO(OH)
.

As the reaction progresses, the generated NH ₃ dissolves in the system, causing the pH of the acidic system to gradually increase

2.
Silver zinc battery

The silver-zinc battery is a single-liquid battery.
Because of its light weight and small size, it is often used as the power source for electronic watches and calculators, and is called a button battery
.

The positive electrode of the battery is Ag ₂ O, the negative electrode is metallic Zn, and the electrolyte is KOH

The positive electrode of Ag ₂ O + H ₂ O + 2E ^- = 2Ag + 2OH ^-

+ 2OH negative a Zn ^- = a Zn (OH) ₂ + 2E ^-

3.
Lead battery

Lead-acid batteries are rechargeable batteries that are bulky and are often used as power sources for automobiles
.

The lead plate is coated with PbO ₂ as the positive electrode, and the negative electrode is metal Pb, and both electrodes are in contact with H ₂ SO ₄ at the same time

The positive electrode of PbO ₂ + SO _.
4 ^2- + 4H ⁺ + 2E ^- = PbSO _.
4 + 2H ₂ O

+ SO negative Pb _.
4 ^2- = PbSO _.
4 + 2E ^-

Lead-acid batteries are single-liquid batteries, and their symbol is

(-)Pb|H ₂ SO ₄ (c)|PbO ₂ (+)

PbSO _{4 is} generated in the battery discharge reaction , so the symbol of lead storage battery can also be written as

(-)Pb|PbSO ₄ |H ₂ SO ₄ (c)|PbSO ₄ |PbO ₂ |Pb(+)

4.
Fuel Cell

The fuel cell is a new type of power source that carries out the combustion reaction in the form of a primary battery, which has a much higher energy utilization rate than the combustion of heat to generate electricity
.

For example, if the combustion reaction of H ₂ and O ₂ is designed into a battery in an alkaline medium, the electrode reaction

Cathode O ₂ + 2H ₂ O + 4E ^- = 4OH ^-

Negative H ₂ + 2OH ^- = 2H ₂ O + 2E ^-

5.
Ni-MH battery

Ni-MH batteries are single-liquid rechargeable batteries with a long life
.

The positive electrode is an oxygen-containing compound of nickel, the negative electrode is high-pressure H ₂ , and there is a KOH or NaOH solution between the two electrodes

The positive electrode of NiO (OH) + H ₂ O + E ^- = of Ni (OH) ₂ + OH ^-

Negative H ₂ + 2OH ^- = 2H ₂ O + 2E ^-

The battery symbol is

(-)Pt|H ₂ |KOH|Ni(OH) ₂ |NiO(OH)(+)