Lithium-ion Battery

The Lithium-ion Battery also known as Li-ion battery or lithium battery (LIB abbrv.) is a rechargeable battery in which lithium ions migrate from the negative electrode to the positive electrode when it is discharging and back when charging. These batteries make use of an intercalated lithium compound as an electrode material unlike the metallic lithium used for the non-rechargeable battery. The major components of this lithium battery cell are the electrolyte which allows ionic movement and two electrodes.

Most home electronics use the lithium-ion battery since they have a high energy density, low self-discharge, and tiny memory effect. Not only that but they are also used for other purposes like aerospace, battery electric vehicle, and military. This is fast phasing out the old heavy lead-plate and acid electrolyte battery since it is a lightweight battery which performs the same function.

Construction of the Lithium-ion Battery

The lithium battery has three major components: the positive electrode, negative electrode, and the electrolyte. In the conventional lithium battery, the positive electrode is known to be a metallic oxide while the electrolyte is lithium salt in an organic solvent. Depending on the current flow direction through the cell, the electrochemical roles between the cathode and anode reverse.

The most common commercial negative electrode known is graphite while the positive electrode can be any of the following materials: a spinel (like lithium manganese oxide), a polyanion (like lithium iron phosphate) or a layered oxide (like lithium cobalt oxide). Not too long ago, graphene-based electrodes were also used as electrodes in the lithium battery.

A mixture of organic carbonates as ethylene carbonate or diethyl carbonates which contain lithium ion complexes form the electrolyte. These are non-aqueous electrolytes which normally use non-coordinating anion salts like lithium triflate, lithium tetrafluoroborate, lithium perchlorate, etc.

Li-ion batteries are costlier than NiCd batteries but can work over a wider temperature range having higher densities. A protective circuit is needed so as to limit peak voltage. Also, the battery pack of laptops and notebooks contain lithium ion cells with other components such as voltage tap, temperature sensors, battery charge state monitor, voltage converter/regulator circuit and the main connector. The function of these components is to monitor the charging state and current going in and out of all the cells, their capacities individually because a drastic charge can cause reverse polarities, a very dangerous state and check each cell's temperature with the aim of reducing the risk of short circuits.

Temperature difference

The Li-ion battery can be classified as a high and low-temperaturebattery due to temperature difference. As a high-temperature battery, it can work under a temperature of 60 degrees Celsius for a long time while it is available at -20 degrees Celsius. However, it can reach up to 85 degrees Celsius of short term storage.

On the other hand, as a low-temperature battery, it can work under -40 degrees Celsius while its short term storage can reach up to 70 degrees Celsius.

Safe storage

Li-ion batteries come in various sizes and an example is the 18650 Li-ion battery which is used in notebooks. One thing to be noted is that temperature is a major factor that determines the resulting capacity after storage and how long that battery can be stored.

An 18650 Li-ion battery can be stored at low temperatures because they degrade quickly at high temperatures. During the time of breaking down and decomposition, lithium batteries are known to have a voltage above 2.5 Volts which implies that it is necessary to top-up the battery whenever the voltage drops very low.

Precautions that are very important when storing are:

1. If the battery is to be stored for less than a month, it can be kept in an environment with temperature of 50 degrees Celsius.

2. If the battery is to be stored for less than 3 months, it should be kept in an environment with temperature of 40 degrees Celsius.

3. If the battery is to be stored less than a year, then it should be kept in an environment with temperature of 20 degrees Celsius.

Contact:
Person: Tim.lee
Company: Dongguan Large Electronics Co., Ltd
Add: Block A, Gaosheng Technology Zone, Nancheng District, Dongguan City, Guangdong Province, CN
Tel: 86-769-23182621
Email: Tim.lee@largepower.cn
Site: www.lithiumion-batterypack.com