Lithium rechargeable batteries positive electrodes

There have been a number of attempts to produce commercial lithium rechargeable batteries. The V205 positive is currently used by the Matsushita Battery Industrial Co in Japan for the production of small capacity, coin-type cells. Fig. 7.24 shows a cross-section of one prototype. For the construction of the battery, V205 and carbon black are mixed together with a binder, moulded and vacuum-dried to form the positive electrode pellet. A solution of LiBF4 in a propylene carbonate-y-butyrolactone-1,2-dimethoxyethane mixture absorbed in a polypropylene separator is used as the electrolyte. 

While the development of primary cells with a lithium anode has been crowned by relatively fast success and such cells have filled their secure rank as power sources for portable devices for public and special purposes, the history of development of lithium rechargeable batteries was full of drama. Generally, the chemistry of secondary batteries in aprotic electrolytes is very close to the chemistry of primary ones. The same processes occur under discharge in both types of batteries anodic dissolution of lithium on the negative electrode and cathodic lithium insertion into the crystalline lattice of the positive electrode material. Electrode processes must occur in the reverse direction under charge of the secondary battery with a negative electrode of metallic lithium. Already at the end of the 1970s, positive electrode materials were found, on which cathodic insertion and anodic extraction of lithium occur practically reversibly. Examples of such compounds are titanium and molybdenum disulfides. 

Arbizzani, C., and M. Mastragostino. 1990. Polybithiophene as positive electrode in solid-state polyethylene oxide-LiC104 lithium rechargeable battery. Electrochim Acta 35 251. 

Carbon-Lithium Rechargeable Batteries. The carbon-lithium batteries use a lithium alloy for the negative active material, a nonaqueous organic electrolyte, such as propylene carbonate, and activated carbon for the positive electrode. The battery is built in a discharged state. The mode of operation and the reactions during charge and discharge are delineated as follows ... 

The most important rechargeable lithium batteries are those using a soHd positive electrode within which the lithium ion is capable of intercalating. These intercalation, or insertion, electrodes function by allowing the interstitial introduction of the LE ion into a host lattice (16,17). The general reaction can be represented by the equation ... 

Beginning in the early 1980s [20, 21] metallic lithium was replaced by lithium insertion materials having a lower standard redox potential than the positive insertion electrode this resulted in a "Li-ion" or "rocking-chair" cell with both negative and positive electrodes capable of reversible lithium insertion (see recommended papers and review papers [7, 10, 22-28]). Various insertion materials have been proposed for the anode of rechargeable lithium batteries,... 

At the end of the 1990s in Japan, large-scale production of rechargeable lithium ion batteries was initiated. These contained lithium compounds intercalated into oxide materials (positive electrodes) as well as into graphitic materials (negative electrode). The development of these batteries initiated a further increase in investigations of the properties of different intercalation compounds and of the mechanism of intercalation and deintercalation processes. 

Although conjugated polymers can be both n-doped and p-doped - and thus, in principle, be capable of behaving either as negative or as positive electrodes - the majority of applications have been confined to the p-doping, positive side. Conductive polymers have been proposed and tested in a variety of advanced electrochemical devices. Due to lack of space, we will confine our attention to the description of the most illustrative examples which are rechargeable lithium batteries and multi-chromic optical displays. 

Many industrial and academic laboratories have investigated doped polymers as improved positive electrodes in rechargeable lithium batteries. A common example is the battery formed by a lithium anode, a liquid organic electrolyte (e.g. LiC104-PC solution) and a polypyrrole film... 

Padhi AK, Nanjundaswamy KS, Goodenough JB. Phospho-olivines as positive-electrode material for rechargable lithium batteries. J Electrochem Soc. 1997 144(4) 1188—94. 

Edison cell — A nickel-iron (Ni-Fe) secondary (rechargeable) cell independently developed by Edison in USA and W. Jiinger in Sweden in 1900. The cell (-> battery) is based on the use of nickel oxyhydroxide (NiOOH) at the positive electrode and metallic iron for the negative electrode, and a potassium hydroxide (KOH) solution containing lithium hydroxide (LiOH) is the electrolyte. The Ni-Fe cell is represented as ( Fe/KOH/NiOOH. The charge-discharge reactions for the Edison (Ni-Fe) cell are as follows ... 

There are two main kinds of rechargeable battery based on lithium chemistry the lithium-metal and the lithium-ion battery. In both the positive electrode is a lithium insertion material the negative in the former is lithium metal and in the latter it is a lithium insertion host. The reason for the application in lithium batteries of insertion electrode materials, which are electronic and ionic conductive solid matrixes (inorganic and carbon-based), is that electrochemical insertion reactions are intrinsically simple and highly reversible. 

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