Primary & Secondary Batteries

Primary batteries (more commonly known as disposable batteries) are designed to be used once. The chemical reactions in their cells are not easily reversible, so energy cannot be restored to the battery after their initial supply of reactants have been used. Such batteries are commonly exploited in portable devices with low current requirements. Common types of primary batteries include alkaline batteries and zinc-carbon batteries. In comparison with secondary batteries, primary batteries have higher energy densities, but are not as well suited to high-drain applications.

Secondary batteries (more commonly known as rechargeable batteries) can be recharged through the supply an electric current, typically from the electricity mains. Their original composition can be restored due to the reversible nature of the chemical reactions within their cells. Secondary batteries cannot be recharged indefinitely however and become less effective at holding charge over time due to loss of active materials, electrolyte and internal corrosion. The lead-acid battery was one of the first types of rechargeable battery, of which the modern car battery is a good example. Secondary batteries used in portable devices such as laptops and mobile phones, include nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH) and lithium-ion (Li-ion) batteries.