Lithium ion cell

Fig. 1. Schematic drawing of a lithium-ion cell, (a) during discharge, (b) during charge.

A possible solution to this problem is to use an electrolyte, such as a solid polymer electrolyte, which is less reactive with lithium metal [3]. Another simple solution is the lithium-ion cell. 

Most commercial lithium-ion cells maufactured today use graphitic carbons from region 1 of Fig. 2. These are of several forms, with mesocarbon microspheres and natural graphites being the most commonly used. The specific capacity of these carbons is near 350 mAh/g. 

Lithium-Ion Cells. Lithium-ion cells and the newer alternative, lithium-ion-polymer, can usually run much longer on a charge than comparable-size Nicad and nickel-metal hydride batteries. Usually is the keyword here since it depends on the battery s application. If the product using the battery requires low levels of sustained current, the lithium battery will perform very well however, for high-power technology, lithium cells do not perform as well as Nicad or nickel-metal hydride batteries. 

Lithium-ion cells operate during charge and discharge by a mechanism that involves the electrochemical insertion of lithium into, and extraction from, positive and negative electrode host structures. For example, in the well known Li tC6 / Li, tCo02 system, which is assembled in the discharged state, lithium ions are extracted from the metal oxide structure and... 

The best known layered structures that have been exploited in lithium-ion cells have the general formula LiM02 (M= Co,... 

The compound LiCo02 is an attractive positive electrode for lithium-ion cells because it has a stable structure which is easy to prepare with the ideal layered configuration (da ratio = 4.99). At present, LiCo02 is the preferred positive electrode... 

Lithium-titanium-oxide spinels provide a relatively low voltage of 1.5V vs. lithium. They are, therefore, of interest as possible negative electrode materials for lithium-ion cells [161-163] they can be coupled, for example, to Li[Mn2104 (4V vs. Li) to yield a 2.5V lithium-ion cell, or to LixMn02 (3V vs. Li) to yield a 1.5V lithium-ion cell. Although these cells have a voltage lower than that of commercial... 

These values are poor compared with lithium-ion cells, whose corresponding values are 500 cycles and above 130 °C. This poor performance is explained mainly by the characteristics of the lithium-metal anode, and specifically its low cycling efficiency. 

The use of non-graphitic (disordered) carbons as anode materials in lithium ion cell is highly attractive for two reasons ... 

Carbons exhibiting hysteresis show poor cycling performance, and can be discharged only in a broad potential region of about 1-2 V (Fig. 13) [41, 51, 52, 218-220, 234-236, 244, 277, 278, 287], As a result, the energy efficiency of a lithium-ion cell is reduced. 

Despite the fact that currently commercialized lithium-ion cells basically contain... 

Figure 19. The volumes of several anode materials tor lithium ion cells before (gray) and after (black) lithiation.

This section reviews the state-of-the-art in battery separator technology for lithium-ion cells, with a focus on separators for spirally wound batteries in particular, button cells are not considered. 

Note that a review of battery separators for lithium-ion cells was recently published [1] in Japanese. 

Currently, all commercially available, spirally wound lithium-ion cells use microporous polyolefin separators. In particular, separators are made from polyethylene, polypropylene, or some combination of the two. Polyolefins provide excellent mechanical properties and chemical stability at a reasonable cost. A number of manufacturers produce microporous polyolefin separators (Table 1.)... 

Practically every battery system uses carbon in one form or another. The purity, morphology and physical form are very important factors in its effective use in all these applications. Its use in lithium-ion batteries (Li-Ion), fuel cells and other battery systems has been reviewed previously [1 -8]. Two recent applications in alkaline cells and Li-Ion cells will be discussed in more detail. Table 1 contains a partial listing of the use of carbon materials in batteries that stretch across a wide spectrum of battery technologies and materials. Materials stretch from bituminous materials used to seal carbon-zinc and lead acid batteries to synthetic graphites used as active materials in lithium ion cells. 

SEI formation control is the key to good performance and the safety of the whole lithium ion battery, as not only anode operation but also cathode properties are strongly affected by the SEI formation process (the cathode is the lithium cation source of lithium ion cells). Apart from control of the graphite (surface) properties, an appropriate composition of the electrolyte is usually helpful for creation of an effective SEI. 

Winter M., Novak P. and. Monnier A. Graphites for Lithium-ion Cells The Correlation of the First-Cycle Loss with the Brunauer-Emmett-Teller Area. J. Electrochem. Soc., 145, 428-435 (1998). 

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