The alkaline battery is one of the most common primary battery types in consumer applications, in the sizes AA (IEC designation: LR6) and AAA (IEC designation: LR03), often labeled “ALKALINE”. This cell chemistry belongs to a relatively well-developed and proven chemistry where development is not of the larger kind. However, in 2015, the world’s first alkaline battery cells launched with 4% recycled material from batteries left for recycling.
Structure (Alkaline)
It is the alkaline electrolyte that has given the battery its name. The electrolyte consists of a solution of potassium hydroxide (KOH). The anode consists of powdered zinc which is soaked in an electrolyte which results in very efficient use of the anode material. This means that the anode will be completely oxidized when the battery is exhausted. The current conductor consists of a brass nail located in the center of the cell.
As the cathode material, manganese dioxide is used in powder form. The manganese dioxide is mixed with graphite powder to increase its conductivity and, like the anode, is soaked in electrolyte. The mass is then compressed into cylinders which are in direct galvanic contact with the cell jug (of stainless steel), which also constitutes current conductors for the cathode. The cathode is separated from the anode by a separator.
Since both the anode and the cathode are made of powdered material, a significantly larger electrode surface is obtained and the immediate contact with the electrolyte increases the efficiency of the battery while decreasing the polarization (which occurs in rechargeable batteries in high continuous current discharge).
Characteristics
Alkaline batteries have a nominal voltage of 1.5 V. The maximum voltage is between 1.5 V and 1.65 V depending on the purity of the manganese oxide in the cathode. A discharged alkaline battery has a voltage of between 0.8 V and 1.0 V. The available capacity of a AA-size battery depends on which power outlet the cell is exposed to and can vary between 3000 mAh at low power outlets to 700 mAh for currents upwards of 1 A. Alkaline batteries have a shelf life of 5-10 years from the date of manufacture. The operating temperature of alkaline batteries is usually set between -18 ° C and +55 ° C, but its properties are adversely affected at specified extreme temperatures.
Advantages and disadvantages
Benefits
Compared to the brownstone battery, an alkaline battery costs almost twice as much but, depending on the application and mode of use, provides about 4-6 times longer operating time. The internal design of the alkaline battery and the choice of electrolyte give it a much better performance than the brown battery and also much better low-temperature properties. It can also be stored longer before use than the rechargeable battery without losing performance.
The alkaline battery, unlike the brownstone battery, is fully encapsulated in a stainless steel cell jug, which means that it is not as leak-proof as its predecessor where the anode also functions as a cell jug.
Drawbacks
It is more expensive than the brownstone battery and places higher demands on the components being of a high degree of purity.
