Schematic showing the processing steps for converting battery materials into battery packs, starting from the initial slurry mixing, electrode coating, calendering, and drying (in red and blue for the anode and cathode, respectively), over the cell assembly and electrolyte filling until the eventual module and pack assembly (in green).
The most common dry cell battery is the Leclanche cell. The capacity of a battery depends directly on the quantity of electrode and electrolyte material inside the cell. Primary batteries can lose around 8% to 20% of their charge over the course of a year without any use. This is caused by side chemical reactions that do not produce current.
A battery requires three things – two electrodes and an electrolyte. The electrodes must be different materials with different chemical reactivity to allow electrons to move round the circuit. This movement requires an electrolyte to complete the circuit, provided by the acidic liquid in the lemon.
Inside a battery, are one or more simple chemical cells. A simple cell must contain an electrolyte and two different metals. It can be made from everyday items like a lemon, zinc nail, and copper penny. The lemon juice in the lemon acts as the electrolyte and the two metals are electrodes. Electricity flows between the two metal.
Interestingly, in present times, unless explicitly specified otherwise, the term "battery" universally refers to electrochemical cells used for generating electrical energy, and even a single cell is now referred to as a battery.
This electrolyte acts as a concentration gradient for both sides of the half reaction, facilitating the process of the electron transfer through the wire. This movement of electrons is what produces energy and is used to power the battery. The cell is separated into two compartments because the chemical reaction is spontaneous.