N-doping polymer

P" doped polyacetylene results in the formation of highly conjugated carbeni urn ions, whereas "n" doped polymer forms highly conjugated carbanions. These "holes" and "electrons", respectively, are thought to move along the polymer backbone. 

The conductivity of the doped polymer is quite sensitive to its environment,with both oxygen and water leading to decay. "N" doped polymers are extremely sensitive to ambient conditions. 

The terminology used to describe redox processes in n-doping polymers is often ambiguous. For clarity in this chapter, oxidation of polymers is defined as the removal of electrons from the polymer in its neutral (uncharged or undoped) state. This oxidized (p-doped) polymer is positively charged and most commonly referred to as the true conducting version of an EAR When this oxidized polymer is converted back to its neutral form by the addition of electrons (often referred to as reduction of the oxidized polymer), it will be referred to as neutralization of the oxidized polymer, rather than reduction. 

Ion transport in n-doping polymers needs further investigation, but it seems likely that cation transport dominates when the cation is small and highly mobile whereas anion transport dominates... 

In Type III and Type IV supercapadtors, ox(anode)- red(cathode) typically ranges from 0.8 to 3 V [ 147]. The overvoltage is approximately the same as that of a Type I supercapacitor (perhaps less due to the sensitivity of n-doped polymers), meaning that Type in and Type IV supercapacitors typically have... 

Loveday et al. [170] proposed the use of self-n-doping polymers in Type III supercapacitors. Self-n-doping was expected to alleviate cation transport problems and enhance the n-doping process, thus enhancing device performance. While the polymer, poly-3-(p-trimethylammoniumphenyl)hithiophene (Figure 9.4N) showed promising n-doping, no supercapacitor device properties were reported. 

Ebron, V.H., et al. 2002. Electrochemical characterization of 4,4 -bicyclopenta[2,l-k3,4-l/]dithiophenylidene dimer A new n-doping polymer of electrochemical capacitors. Polym Mater Sci Eng 86 4. 

In order to avoid the problems associated with the instability of the n-doping process of the polymer, it has been proposed to replace the n-doped polymer at the negative electrode with a carbon electrode to form the so-called hybrid capacitor [22, 33, 40]. Such hybrid capacitors with a p-doped polythiophene derivative as the positive electrode and activated carbon as the negative electrode were found to outperform double-layer carbon capacitors in terms of specific power while maintaining good performance cyclability over 10000 cycles [40]. Another asymmetric hybrid capacitor has been built using a lithium titanate (Li4Ti50i2) intercalation anode, instead of a carbon electrode and PFPT electrode [35]. 

---