Lithium polymer electrolyte batteries

Sec color insert.) Pouch cell design for solid electrolyte lithium polymer battery. Design is easily adaptable to ECs made with organic electrolyte. Source ElectropecUa Cell Construction (online). http //wwwjnpoweruk.com/ceU construction.htm [accessed AprU 5, 2012]. With permission.)... 

The majority of polymer electrodes cannot be doped to very high levels. For instance, polypyrrole may reach doping levels of the order of 33%. This inherent limitation combined with the fact that the operation of the lithium/polymer battery requires an excess of electrolyte (to ensure... 

More recently, solid state batteries with lithium conducting polymer electrolytes have been extensively studied. The development has focused on secondary batteries for an electric vehicle, because lithium polymer batteries have a theoretical energy density that approaches 800 W h kg ... 

Gel polymer lithium-ion batteries replace the conventional liquid electrolytes with an advanced polymer electrolyte membrane. These cells can be packed in lightweight plastic packages as they do not have any free electrolytes and they can be fabricated in any desired shape and size. They are now increasingly becoming an alternative to liquid-electrolyte lithium-ion batteries, and several battery manufacturers. such as Sanyo. Sony, and Panasonic have started commercial production.Song et al. have recently reviewed the present state of gel-type polymer electrolyte technology for lithium-ion batteries. They focused on four plasticized systems, which have received particular attention from a practical viewpoint, i.e.. poly(ethylene oxide) (PEO). poly (acrylonitrile) (PAN). ° poly (methyl methacrylate) (PMMA). - and poly(vinylidene fluoride) (PVdF) based electrolytes. ... 

Lithium polymer batteries are similar in principle to the lithium batteries described above but the electrolyte is a polymer. The advantage of these batteries is the absence of liquid in the cell and so the batteries do not leak. The polymer electrolyte is a polymer-alkali metal salt complex. The best known such electrolytes are complexes of poly (ethylene) oxide (PEO). 

In lithium polymer batteries, one electrode is lithium foil, or in some cases another electrically conducting material such as graphite, and the other is a reversible intercalation compound as in liquid electrolyte lithium batteries. Compounds used as intercalation electrodes include LiCo02 and VeOis. The cell developed in the Anglo-Danish project, which ran from 1979 to 1995, was... 

The lithium polymer battery (LPB), shown schematically in Fig. 7.21, is an all-solid-state system which in its most common form combines a lithium ion conducting polymer separator with two lithium-reversible electrodes. The key component of these LPBs is the polymer electrolyte and extensive work has been devoted to its development. A polymer electrolyte should have (1) a high ionic conductivity (2) a lithium ion transport number approaching unity (to avoid concentration polarization) (3) negligible electronic conductivity (4) high chemical and electrochemical stability with respect to the electrode materials (5) good mechanical stability (6) low cost and (7) a benign chemical composition. 

LPB (lithium polymer battery) A cell (generally rechargeable) having a lithium foil negative, a metal oxide positive and a polymer electrolyte. 

The substitution of the liquid electrolyte with the less reactive polymer electrolyte has led to lithium-polymer batteries, among the most likely to be commercialized for electric vehicles [89]. It must be stressed that the lithium-polymer battery is still a lithium-metal battery and not a lithium-ion one. Lithium-polymer batteries are solid-state, in that their electrolyte is a solid. A great safety advantage of this type of battery is that the electrolyte will not leak out if there is a rupture in the battery case. Furthermore, it can be assembled in any size and shape, allowing manufacturers considerable flexibility in cell design for electric vehicle or electronic equipment. 

This type of Li battery has already widely diffused in the electronic consumer market, however for automotive applications the presence of a liquid electrolyte is not considered the best solution in terms of safety, then for this type of utilization the so-called lithium polymer batteries appear more convenient. They are based on a polymeric electrolyte which permits the transfer of lithium ions between the electrodes [21]. The anode can be composed either of a lithium metal foil (in this case the device is known as lithium metal polymer battery) or of lithium supported on carbon (lithium ion polymer battery), while the cathode is constituted by an oxide of lithium and other metals, of the same type used in lithium-ion batteries, in which the lithium reversible intercalation can occur. For lithium metal polymer batteries the overall cycling process involves the lithium stripping-deposition at the anode, and the deintercalation-intercalation at the anode, according to the following electrochemical reaction, written for a Mn-based cathode ... 

Electrodes and cell components must be thin to minimise the internal resistance of the batteries the total cell can be less than 0.2 mm thick. Figure 12.11 shows the construction of a multi-layer film, rechargeable lithium polymer battery, using a solid polymer electrolyte. A thin lithium metal foil acts as an anode. The electrolyte is polyethylene oxide containing a lithium salt, and the cathode is a composite of the electrolyte and a... 

Sivakkumar, S., Kim, D.-W., 2007. Polyanfline/carbon nano tube composite cathode for rechargeable lithium polymer batteries assembled with gel polymer electrolyte. J. Electrochem. Soc. 154, A134-A139. 

With the use of sohd to gelatinous, polymeric electrolyte layers that ensure electrical separation of the electrodes and the unity of the cell components combined with good conductivity for lithium ions, it is not necessary to employ hquid electrolytes in lithium batteries. This simplifies the production of lithium polymer batteries, which are also safer in operation because the electrolyte is polymeric, not liquid. This battery cell structure facilitates production of thin foil batteries, a favorable form for use in portable devices. The expected performance data correspond to what is obtained with other lithium ion systems. 

Lithium-polymer batteries, that is, batteries with polymer electrolyte are generally manufactured in the form of thin flat elastic products with a simple plastic casing ( coffee bag ) instead of a metallic case. 

Figure 21.5 shows the gel-type polymer electrolyte especially developed for the lithium polymer battery by Dai-Ichi Kogyo Seiyaku Co. Ltd. (DKS). The structure of the acrylate after cross-linking enables it to hold the large quantity of the liquid electrolyte and never leak the liquid electrolyte. ... 

The purpose of this chapter is to describe how ionic conductivity has been achieved in ways that retain the advantages of flexibility, processability, ease of handling and relatively low impact on the environment that polymers inherently possess. Electronically conducting polymers are addressed in the next chapter. The reader will also find particular aspects of ion conducting polymers discussed in detail in subsequent parts of this volume these include multivalent polymer electrolytes, key application areas such as lithium polymer batteries and smart windows, and the development of polymer hosts which permit greatly enhanced conductivity at room temperature. 

The discovery and the characterization of ionically conducting polymeric membranes (see Chapters 1 and 2) have provided the interesting possibility of developing new types of lithium batteries having a thin-layer, laminated structure. Various academic and industrial laboratories [1-5] are presently engaged in the development of this revolutionary type of battery, i.e. the so-called Lithium Polymer Battery (LPB). The key component of the LPB is the polymeric ionic membrane which acts both as electrolyte and separator furthermore, the membrane can be easily fabricated in the form of a thin film (typically 50 jum thickness) by a number of convenient casting techniques. 

Arie et al. [116] investigated the electrochemical characteristics of phosphorus-and boron-doped silicon thin-film (n-type and p-type silicon) anodes integrated with a solid polymer electrolyte in lithium-polymer batteries. The doped silicon electrodes showed enhanced discharge capacity and coulombic efficiency over the un-doped silicon electrode, and the phosphorus-doped, n-type silicon electrode showed the most stable cyclic performance after 40 cycles with a reversible specific capacity of about 2,500 mAh/g. The improved electrochemical performance of the doped silicon electrode was mainly due to enhancement of its electrical and lithium-ion conductivities and stable SEI layer formation on the surface of the electrode. In the case of the un-doped silicon electrode, an unstable surface layer formed on the electrode surface, and the interfacial impedance was relatively high, resulting in high electrode polarization and poor cycling performance. 

Poly (ethylene oxide) (PEO) - LiX complexes appear to be the most suitable electrolytes for lithium polymer batteries, however, the local relaxation and segmental motion of the polymer chains remain a problem area (Armand et al., 1997). Therefore, the PEO-based electrolytes show an appreciable ionic conductivity only above 100°C (Gorecki et al., 1986). This is, of course, a drawback for applications in the consumer electronic market. On the other hand, the gel polymer electrolytes although offer high ionic conductivity and appreciable lithiiun transport properties it suffers from poor mechanical strength and interfacial properties (Croce et al., 1998 Gray et al., 1986 Kelly et al., 1985 Weston et al., 1982). Recent studies reveal that the nanocomposite polymer electrolytes alone can offer safe and reliable lithium batteries (Appetecchi... 

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