The battery consists of four basic parts: electrode, electrolyte, isolation layer and container. 

The electrode is the core part of the battery, which is composed of active substances and conductive materials that participate in electrochemical reactions. The electrode is divided into positive electrode (represented by "+") and negative electrode (represented by "-"). Electrolytes are aqueous solutions of acids, bases and salts or organic electrolyte solutions, which play the role of transferring charged ions between positive and negative electrodes in the battery. In some batteries, electrolytes also participate in electrochemical reactions. The isolation layer is located between the positive and negative poles of the battery and plays an isolation role to prevent the stored electric energy from being consumed due to internal short circuit. The container is the shell of the battery, which plays the role of protecting and containing the battery components. The shell of some batteries is also the electrode of the battery.

When the battery is discharged, electrons flow from the negative pole to the positive pole through the external circuit. In the electrolyte solution inside the battery, positive and negative ions move towards the two poles to form a current. Chemical reaction occurs on both electrodes at the same time, oxidation reaction occurs on the negative electrode, and reduction reaction occurs on the positive electrode. When the battery is charged, the reverse reaction of discharge reaction occurs on the electrode, the active substance is regenerated, and the electrical energy is stored again in the form of chemical energy.

Battery is a device that directly converts other forms of energy into DC power. According to the form of converted energy, it can be divided into physical battery and chemical battery. Chemical battery is a device that directly converts chemical energy into DC electric energy, commonly known as battery.

Batteries can be divided into primary cells, storage batteries, storage batteries, solar cells and fuel cells according to their different use properties.

Primary battery is also called primary cell. Once its active substance is exhausted, such battery cannot be recovered for reuse by charging. The galvanic cell whose electrolyte does not flow is called "dry cell". Primary battery is the most common civilian battery, such as ordinary zinc manganese battery, alkaline zinc manganese battery, zinc silver battery, lithium manganese battery, etc.

Storage Batteries are also called secondary batteries, which can be recharged and reused for many times, such as lead-acid batteries, nickel cadmium batteries, nickel metal hydrogen batteries, lithium ion batteries, etc. Due to the large proportion of lead-acid batteries, lead-acid batteries are usually classified separately, and the others are small secondary batteries, including cadmium nickel(NiCD) batteries, nickel metal hydrogen(NiMH) batteries, and lithium ion batteries.

The purpose of storage battery is to make the battery have a long storage period. During storage, other parts of the battery are stored separately from the electrolyte, and then the electrolyte solution is injected for activation. It is usually used in military and other special occasions.

Fuel cell is an electrochemical energy conversion device, which uses the direct reaction between hydrogen or hydrogen containing carrier and oxygen to generate electric energy. There is no direct combustion process, and the active substances are supplemented through the outside of the device.

Solar cells can be subdivided into solar photovoltaic cells and solar photochemical cells. Solar photovoltaic cells are usually classified as physical cells. The current practical solar photovoltaic cells are semiconductor devices, which can produce photovoltaic effect when exposed to sunlight and convert solar energy into direct current energy, including crystalline silicon solar cells, monocrystalline silicon solar cells, polycrystalline silicon solar cells, amorphous silicon solar cells, and compound semiconductor solar cells. Solar photochemical cells use the energy chemical conversion of photochemical reaction to convert solar energy into chemical energy. There are two main methods: photosynthesis and photochemical reaction.