A lithium-ion (Li-ion) battery is an advanced battery that employs lithium ions as an important component of its electrochemistry. Lithium atoms in the anode are ionized and separated from their electrons during a discharge cycle. The lithium ions travel from the anode through the electrolyte to the cathode, where they recombine with their electrons and electrically neutralize. The lithium ions are small enough to pass through a micro-permeable separator that separates the anode and cathode. Because of the small size of lithium (third only to hydrogen and helium), Li-ion batteries can have very high voltage and charge storage per unit mass and unit volume.
Electrodes in Lithium-ion batteries can be made of a variety of materials. The most common combination is lithium cobalt oxide (cathode) and graphite (anode), which is found in portable electronic devices like cell phones and laptop computers. Lithium manganese oxide (used in hybrid and electric vehicles) and lithium iron phosphate are two other cathode materials. As an electrolyte, ether (a class of organic compounds) is commonly used in lithium-ion batteries.
Lithium-ion batteries have several advantages over other high-quality rechargeable battery technologies (nickel-cadmium or nickel-metal-hydride). They have the highest energy density of any battery technology available today (100–265 Wh/kg or 250–670 Wh/L). Furthermore, Li-ion battery cells can deliver up to 3.6 Volts, which is three times higher than Ni-Cd or Ni-MH technologies. This means they can provide large amounts of current for high-power applications. Li-ion batteries are also low-maintenance, as they do not require scheduled cycling to maintain battery life.
High energy density — potential for even greater capacity.
When new, no lengthy priming is required. One regular charge is all that is required.
Self-discharge is less than half that of nickel-based batteries.
Low Maintenance — no need for periodic discharge; no memory.
Specialty cells can deliver extremely high current to applications such as power tools.
Li-ion batteries have no memory effect, which is a negative process in which a battery can’t remember a lower capacity after repeated partial discharge/charge cycles. This is an advantage over Ni-Cd and Ni-MH, both of which exhibit this effect. In addition, lithium-ion batteries have a low self-discharge rate of 1.5–2% per month. Because they do not contain toxic cadmium, they are easier to dispose of than Ni-Cd batteries.
Because of these benefits, Li-ion batteries have surpassed Ni-Cd batteries to become the market leader in portable electronic devices (such as smartphones and laptops). Li-ion batteries are also used to power electrical systems in some aerospace applications, most notably the newer and more environmentally friendly Boeing 787, where weight is an important cost factor. Much of the promise of Li-ion technology in terms of clean energy stems from its potential applications in battery-powered automobiles. The most popular electric vehicles today, the Nissan Leaf and the Tesla Model S, both use Li-ion batteries as their primary fuel source.
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