battery

A battery is a device that stores chemical energy and converts it into electrical energy through electrochemical reactions. It comprises one or more cells, each with an anode, a cathode, an electrolyte, and a separator, encased in a protective housing. When connected to a circuit, chemical reactions shuttle ions between electrodes via the electrolyte, while electrons flow through the external circuit to supply power.

Batteries are categorized as primary (non-rechargeable) and secondary (rechargeable). Common chemistries include zinc–carbon and alkaline for primary cells; lead‑acid, nickel‑cadmium, nickel‑metal hydride, and lithium-based chemistries for secondary cells. They differ in voltage per cell, energy density, cycle life, temperature tolerance, and cost.

The concept dates to the voltaic pile described by Alessandro Volta in 1800. Lead‑acid batteries were developed in the 19th century, nickel‑cadmium in the 20th, and lithium‑ion in the 1990s, revolutionizing portable electronics and electric vehicles by providing higher energy density and lighter weight.

Performance is described by voltage per cell, capacity (ampere-hours), energy (watt-hours), and cycle life. Batteries power a wide range of devices, from small sensors to cars and stationary storage that supports electricity grids. Charging, discharging, and storage conditions influence lifespan.

Safety concerns include overheating and thermal runaway in some chemistries, mechanical damage, and leakage. Regulations and standards govern transport, handling, and recycling. End-of-life batteries should be recycled to recover materials such as lithium, cobalt, nickel, and lead, reducing environmental impact.

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