Thursday, June 16, 2011

History of Li-Ion Batteries

In the 1970s, at Exxon at the Binghamton University, M.S. Whittingham proposed the Lithium – ion battery which is the starting point of the history of these power alternatives. At the anode, Whittingham used lithium metal and at the cathode, titanium (II) sulphide. It was at TU Munich in the 1970s, that J.O. Besenhard, discovered the intercalation in graphite that was reversible, as well as, the intercalation into cathodic oxides. High energy density Lithium cells in power alternate application was then proposed. 

Issues related to safety were posed by the anode comprising from metallic lithium in the lithium batteries of the primary type. A material that contained ions of lithium, were used in these laptop batteries (of the lithium – ion type) in which both the cathode as well as the anode were present. The battery made from lithium metal was provided with the alternative of a graphite anode that was workable and developed by Dell Labs in the year 1981. 

As per the history of the Li-Ion batteries a lithium ion laptop battery was commercially released by Sony in the year 1991. John Goodenough led a team to perform the research on cathodes. Lithium cobalt oxide or the layered oxide chemistry was then used in lithium – ion laptop battery cells. For the cathode, a material called manganese spinel was identified by John Goodenough, Dr. Michael Thackeray and some of Goodenough’s co-workers in the year 1983. Spinel added stability in structure that was good, better conductivity in lithium ions, electronic conductivity as well as cost effectiveness thus showing great promise. 

With cycling, fading can take place in manganese spinel in its purest form. However when modifications are made in the material chemically, issues like fading can be overcome. In many of the cells that are commercially used in the current times, manganese spinel is used. At Austin at the University of Texas, Arumugam Manthiram as well as John Goodenough proved that sulphates or the cathodes that contained the polyanions were responsible for producing voltages that were higher as compared to oxides. Production of higher voltages took place due to the poly-anion effect that was inductive. 

Again by the year 1996 in the history of the Li-Ion batteries, lithium iron phosphate as well as other kinds of phospho-olivines were identified as materials for the cathode by Akshaya Padhi, John Goodenough and number of their co-workers. Conductivity of the material was boosted by getting it doped with zirconium, aluminum and niobium which in turn helped in showcasing an improvement that was substantial in the lithium battery’s performance in the year 2002 when Yet-Ming Chiang and his group worked on the formula at the MIT. This subject was debated upon for a while later. 

Again the performance of the batteries was increased in the year 2004 when particles of iron phosphate were utilized which had diameter of less than 100 nanometers. Density of the particles decreased, while surface area of the cathodes increased, improving performance as well as capacity. The market became even more competitive when commercialization of batteries took place with the infringement battle for patent between Goodenough and Chiang. In the lithium ion batteries there are reactions of the electrochemical types in which there are three participants - electrolyte, anode, and the cathode. 

Migration of lithium takes place into the materials within the cathode and the anode. At the time of intercalation or insertion, lithium particles move into the particles of the electrode.  When the reverse process called extraction or the de-intercalation takes place, the lithium travels back. It is from the anode that the lithium gets extracted when discharge takes place in the cell that is lithium based and insertion of lithium takes place within the cathode. Activity of the reverse kind takes place when charging of the cell takes place, as seen in the history of the Li-Ion batteries production. If through an internal circuit that is closed the flow of electrons takes place, then optimum output can be targeted. 

There is an overall limit to the reactions. Lithium cobalt oxide gets supersaturated due to over discharging which leads to lithium oxide production which also happens due to reactions that are irreversible. Cobalt (IV) oxide gets synthesized when overcharged at 5.2 volts as is evident by diffraction of x-rays. Cobalt is the metal used for transition and for transporting the ions of lithium from the anode or the cathode in a lithium ion battery. The Li-Ion battery also referred to as the LIB comes from a family of batteries that are rechargeable in nature. 

During discharge, the ions of lithium start moving from electrodes that are negative to electrodes that are positive and they travel back when charging takes place. There are different types of lithium ion batteries which vary depending on the safety enhancements, chemistry, cost as well as performance of batteries. Lithium batteries that are primary in nature are disposable, in which the electrochemical cells containing lithium ion use a compound called intercalated lithium as material for the electrode instead of lithium in metallic form. A large number of products used by consumers have batteries made with Lithium ion for use. Electronic items of the portable kind make the best use of lithium ion batteries that are rechargeable. 

Density of energy is the best in these batteries and when they are not used the loss of charge is slow, with no memory effect. These batteries are being effectively used in other applications in the aerospace industry, military and vehicle production (those that run on electricity). A lot of research continues to take place on the Li-Ion batteries to improve the LIB technology that is used traditionally where more focus is being laid of density of energy, intrinsic safety, cost as well as durability of the batteries. The lithium ion batteries safety plan keeps changing dramatically depending on the safety requirements, voltage, life, capacity etc as per the type of materials used in the batteries. They are being invested in, in recent times to add quality to gizmo and life to overall usage.

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