Lithium-doped conducting polymer

Lithium-Doped Conducting Polymer and Lithium-Polymer Batteries... 

FIGURE 5.8. Structures of some common doped conductive polymers, each projected on a plane normal to the direction of the polymer chains. Cross-hatched circles indicate dopant ions, (a) The square channel structure of potassium-doped polyacetylene (other alkali-doped PA lattices show similar structures),(b) lithium-doped polyparaphenylene, (c) potassium-doped ppp,(ii3) AsFs-doped PPR In (d) the dopant species, represented by x, are probably... 

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. 

The redox properties of the conducting polymer film are the primary interest of the present chapter, because most of the important applications are associated with switching the electroactive polymer films from the neutral (reduced) state of the doped (oxidized) state. The voltage range in which representative polymers show electroactivity is shown in Figure 2.2, compared with inorganic materials. Li metal is chosen as the reference because of the interest in using the intercalation materials in lithium battery systems. 

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. 

Fukami K, Sakka T, Ogata YH, Yamauchi T, TsubokawaN (2009) Multistep filling of porous silicon with conductive polymer by electropolymerization. Physica Status Solidi (a) 206 1259 Gao L, Mbonu N, Cao L, Gao D (2008) Label-lfee colorimetric detection of gelatinases on nanoporous silicon photonic films. Anal Chem 80 1468 Ge M, Rong J, Fang X, Zhou C (2012) Porous doped sdicon nanowires for lithium ion battery anode with long cycle life. Nano Lett 12 2318... 

Polymers. Electronically conductive polymers may also be used as cathode materials in rechargeable lithium batteries. The most popular polymers are polyacetylene, polypyrrole, polyaniline, and polythiophene, which are made conductive by doping with suitable anions. The discharge-charge process is a redox reaction in the polymer. The low specific energy, high cost, and their instability, however, make these polymers less attractive. They have been used in small coin-type batteries with a lithium-aluminum alloy as the anode. 

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