You're right Karma. Here's a couple of technology paragraphs from the Wikipedia. I suspected Herb was right and our protagonist couldn't see very well with his head up his... In case someone asks, solvents are considered to be liquids.
On Li Ion
Specifications and design
Specific energy density: 150 to 200 W·h/kg (540 to 720 kJ/kg)
Volumetric energy density: 250 to 530 W·h/L (900 to 1900 J/cm3)
Specific power density: 300 to 1500 W/kg (@ 20 seconds [1] and 285 W·h/L)
A typical chemical reaction of the Li-ion battery is as follows:
[citation needed]
Lithium-ion batteries have a nominal open-circuit voltage of 3.6 V and a typical charging voltage of 4.2 V. The charging procedure is one of constant voltage with current limiting. This means charging with constant current until a voltage of 4.2 V is reached by the cell and continuing with a constant voltage applied until the current drops close to zero. (Typically the charge is terminated at 7% of the initial charge current.) In the past Lithium-ion batteries could not be fast-charged and typically needed at least two hours to fully charge. Current generation cells can be fully charged in 45 minutes or less; some reach 90% in as little as 10 minutes. [citation needed]
Lithium ion internal design is as follows. The anode is made from carbon, the cathode is a metal oxide, and the electrolyte is a lithium salt in an organic solvent. Since the lithium metal which might be produced under irregular charging conditions is very reactive and might cause explosion, Li-ion cells usually have built-in protective electronics and/or fuses to prevent polarity reversal, over-voltage and over-heating. [citation needed]
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Solid electrolyte interphase
A particularly important element for activating Li-ion batteries is the solid electrolyte interphase (SEI). Liquid electrolytes in Li-ion batteries consist of solid lithium-salt electrolytes, such as LiPF6, LiBF4, or LiClO4, and organic solvents, such as ether. A liquid electrolyte conducts Li ions, which act as a carrier between the cathode and the anode when a battery passes an electric current through an external circuit. However, solid electrolytes and organic solvents are easily decomposed on anodes during charging, thus preventing battery activation. Nevertheless, when appropriate organic solvents are used for electrolytes, the electrolytes are decomposed and form a solid electrolyte interface at first charge that is electrically insulating and high Li-ion conducting. The interface prevents decomposition of electrolytes after the second charge. For example, ethylene carbonate is decomposed at relatively high voltage, 0.7 V vs. Li, and forms a tight and stable interface. This interface is called an SEI. [citation needed]
See uranium trioxide for some details of how the cathode works. While uranium oxides are not used in commercially made batteries, the way in which uranium oxides can reversibly insert cations is the same as the way in which the cathode in many lithium ion cells work. [citation needed]
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On Li Ion Polymer:
Technology
There are currently two commercialized technologies, both lithium-ion-polymer (where "polymer" stands for "polymer electrolyte/separator"). They are called "polymer electrolyte batteries".
The idea is to use an ion-conducting polymer instead of the traditional combination of a microporous separator and a liquid electrolyte. This promises not only better safety, as polymer electrolyte does not burn as easily, but also the possibility to make battery cells very thin, as they don't require pressure applied to "sandwich" cathode+anode together. Polymer electrolyte seals both electrodes together like a glue.
The design is: anode (Li or carbon-Li intercalation compound)/conducting polymer electrolyte-separator/cathode (LiCoO2 or LiMn2O4)
Typical reaction:
Anode: carbon-Li(x) - xLi+ - xe-
Separator: Li+ conduction
Cathode: Li(1-x)CoO2 + xLi+ + xe-
Polymer electrolyte/separator can be real solid polymer (polyethyleneoxide, PEO) +LiPF6 or other conducting salt +SiO2 or other filler for better mechanical properties (such systems are not available commercially yet). Some are planning to use metallic Li as the anode, whereas others want to go with the proven safe carbon intercalation anode.
Both currently commercialized technologies use PVdF (a polymer) gelled with conventional solvents and salts, like EC/DMC/DEC etc. The difference between the two technologies is that one (Bellcore/Telcordia technology) uses LiMn2O4 as the cathode, and the other, more conventional LiCoO2.
Other, more exotic (although not yet commercially available) Li-polymer batteries use a polymer cathode. For example, Moltech is developing a battery with a plastic conducting carbon-sulfur cathode. However, as of 2005 this technology seems to have problems with self-discharge and manufacturing cost.
Yet another proposal is to use organic sulfur containing compounds for the cathode in combination with an electrically conducting polymer such as polyaniline. This approach promises high power capability (i.e. low internal resistance) and high discharge capacity, but has problems with cycleability and cost. |
