What type of energy conversion takes place in a battery?

Chemical energy into electrical energy

The correct answer is option 2. Chemical energy into electrical energy.

In a battery, the conversion of energy involves chemical reactions that occur within the battery's cells. 

A battery stores energy in the form of chemical potential energy. This energy is contained within the chemical compounds present in the battery's electrodes (anode and cathode) and electrolyte. The chemical compounds undergo oxidation-reduction (redox) reactions during the battery's operation.

When a circuit is completed by connecting the battery terminals with a conductor (such as a wire), electrons flow from the negative terminal (anode) to the positive terminal (cathode) through the external circuit. Simultaneously, ions within the battery electrolyte flow through the internal circuit to maintain charge balance.

Within the battery's cells, oxidation and reduction reactions occur at the anode and cathode, respectively. At the anode, a chemical species undergoes oxidation, releasing electrons into the external circuit. At the cathode, another chemical species undergoes reduction, accepting electrons from the external circuit.

The flow of electrons through the external circuit constitutes an electric current. This flow of electrons represents electrical energy that can perform work, such as powering electronic devices or generating light, heat, or mechanical motion.

As the battery operates and electrons flow through the circuit, the chemical compounds within the battery undergo chemical changes. These changes result in a gradual depletion of the reactants and a decrease in the battery's capacity to deliver electrical energy over time.

In rechargeable batteries, such as lithium-ion batteries, the conversion process is reversible. When the battery is connected to an external power source (e.g., through charging), electrical energy is supplied to the battery, causing chemical changes that restore the original chemical compounds and store energy for later use.

In summary, the energy conversion in a battery involves the conversion of chemical energy stored within the battery's chemical compounds into electrical energy, which can then be utilized to power various devices. This process relies on electrochemical reactions that occur within the battery's cells during discharge and recharge cycles.