Akumulatorer

Akumulatorer, or rechargeable batteries, store chemical energy and convert it to electrical energy. Unlike disposable cells, they can be recharged and reused many times. They comprise one or more electrochemical cells with an anode, a cathode, an electrolyte, and separators. During discharge, redox reactions release electrons; charging reverses these reactions using electrical energy.

Historically, the first widely used accumulator was the lead–acid battery, developed by Gaston Planté in 1859. Nickel-based chemistries followed (NiCd in the 1950s, NiMH in the 1990s), and lithium-based systems (Li-ion, Li-polymer) emerged from the late 1990s onward.

Common chemistries vary in cost, weight, and energy density. Lead-acid is inexpensive and robust but heavy and prone to sulfation. NiCd offers tolerance to temperature and high discharge rates but contains cadmium. NiMH improves energy density and reduces toxic metals. Lithium-based chemistries provide high energy density and longer life; solid-state batteries are under development.

Performance characteristics include capacity in ampere-hours (Ah) or watt-hours (Wh) and cycle life ranging from hundreds to thousands of cycles. Efficiency is generally high, while self-discharge differs by chemistry (Li-ion around 2–5% per month). Charging typically uses constant-current and constant-voltage stages with safe current limits; improper charging can cause overheating.

Applications span portable electronics, electric and hybrid vehicles, and grid storage. End-of-life batteries are recycled to recover metals and materials, reducing environmental impact. Safety, transport, and recycling regulations govern their handling and disposal.