How do alkaline batteries generate electricity?

1. Redox reaction:
In alkaline batteries, the main process of generating electricity is the redox reaction. This reaction involves the oxidation of zinc (Zn) to zinc ions (Zn²⁺) and the simultaneous reduction of manganese dioxide (MnO₂) to manganese oxide (MnO(OH)). This process occurs at the anode and cathode within the battery, with zinc being the anode and manganese dioxide being the cathode. When a battery is connected to a circuit, electrons flow from the anode (zinc) to the cathode (manganese dioxide), creating an electric current through the external circuit. This chemical reaction is the primary driver of electricity generation, and the resulting electrical current is the source of energy used to power electronic devices.

2. Ion conduction in electrolyte:
In alkaline batteries, the electrolyte plays a vital role as it allows ions to move freely within the battery, thereby maintaining electrical neutrality and facilitating the flow of electricity. The alkaline electrolyte is usually potassium hydroxide (KOH), which contains hydroxide ions (OH⁻) and zinc ions (Zn²⁺). These ions move freely in the electrolyte from one pole to the other as the chemical reaction proceeds, ensuring the balance of charges in the battery and promoting the generation of electric current.

3. Current generation:
When an alkaline battery is connected to an external circuit, a chemical reaction begins, creating an electrical current. At the anode (zinc), zinc is oxidized into zinc ions and electrons are released. At the same time, at the cathode (manganese dioxide), the manganese dioxide is reduced and electrons are absorbed. These electrons flow from the anode to the cathode through an external circuit, creating an electric current. This current is the result of a chemical reaction converted into electrical energy, which can be used to supply the energy needs of various electronic devices.

4. Battery consumption:
Over time and chemical reactions proceeding, the active material in an alkaline battery is gradually consumed, causing the battery's charge to gradually decrease. Specifically, zinc metal is gradually dissolved and converted into zinc ions on the anode, while manganese dioxide is gradually reduced on the cathode. This results in a decrease in battery life, and eventually the battery loses its effectiveness and needs to be replaced. Therefore, the service life of a battery depends on the rate and efficiency of its internal chemical reactions, as well as the impact of usage conditions.