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Lithium ion battery: Advantages and disadvantages
Lithium ion batteries (sometimes abbreviated Li-Ion) are a type of rechargeable battery commonly used in consumer electronics. They are currently one of the most popular types of battery, with one of the best energy-to-weight ratios, no memory effect and a slow loss of charge when not in use. They can be dangerous if mistreated, however, and unless care is taken may have a short lifespan compared to other battery types. A more advanced lithium-ion battery design is the lithium polymer cell.
The immediate advantage to Lithium battery chemistry is higher charge density. Li ions are small and mobile, but more readily stored than hydrogen. Thus a battery based on Li is smaller than one with hydrogen, such as a NiMH or NiCd, and with fewer volatile gases. Because the ions need fewer storage intermediaries, more battery weight is useable as charge, instead of overhead. Thus, Li batteries are lighter than equivalents in other chemistries- often much lighter.
The Li-ion battery required nearly 20 years of development before it was safe enough to be used on a mass market level. While Li-ion batteries do not suffer from the memory effect, they are not as durable as NiMH or NiCd designs and can be extremely dangerous if mistreated.
At a typical 100% charge level (notebook battery, full most of the time) at 25 degrees Celsius, Li-ion batteries irreversibly lose approximately 20% capacity per year from the time they are manufactured, even when unused. (6% at 0 °C, 20% at 25 °C, 35% at 40 °C). When stored at 40% charge level, these figures are reduced to 2%, 4%, 15% at 0, 25 and 40 degrees Celsius respectively.) Every (deep) discharge cycle decreases their capacity. The degradation is sloped such that 100 cycles leave the battery with about 75% to 85% of the original. When used in notebook computers or cellular phones, this rate of deterioration means that after three to five years the battery will have capacities too low to be still usable.
A unique drawback of the Li-ion battery is that its life cycle is dependent upon aging from time of manufacturing (shelf life) regardless if it was charged or not and not on the number of charge/discharge cycles. This drawback is not widely publicized. As a newer chemistry, with more-advanced applications, Li batteries command a higher price.
One great advantage of Li-ion batteries is their low self-discharge rate of only approximately 5% per month, compared with over 30% per month and 20% per month in nickel metal hydride batteries and nickel cadmium batteries respectively.
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