Conjugated Molecules and Polymers in Secondary Batteries: A Perspective

Abstract

Intrinsically conducting polymers constituting a subclass of macromolecules, as well as a still growing family of large, conjugated molecules, oligomers, and polymers, have attracted research interest for the recent decades. Closely corresponding to the fascination of these materials, combining typical properties of organic polymers and metallic materials, numerous applications have been suggested, explored, and sometimes transferred into products. In electrochemistry, they have been used in various functions beyond the initially proposed and obvious application as active masses in devices for electrochemical energy conversion and storage. This perspective contribution wraps up basic facts that are necessary to understand the behavior and properties of the oligo and polymers and their behavior in electrochemical cells for energy conversion by electrode reactions and associated energy storage. Representative examples are presented and discussed, and an overview of the state of research and development is provided. Particular attention is paid to stability and related aspects of practical importance. Future trends and perspectives are indicated.

Intrinsically Conducting Polymer Composites as Active Masses in Supercapacitors

“…The most frequently studied materials showing suitable electrochemical behaviors are metal chalcogenides, especially those formed from mixed metal (for earlier reviews, see [ 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ]; for an update, see [ 51 ]) and ICPs. For overviews on ICPs and their applications in electrochemical energy technology, including supercapacitors, see [ 52 , 53 , 54 , 55 , 56 , 57 ]; for selected ICPs, see e.g.,; for PANI, see [ 1 , 58 , 59 ]; for PPy, see [ 60 ]. Electrodes prepared with only a single material have shown significant drawbacks, such as insufficient electronic conductivity, excessive shape change during cycling, and lack of stability.…”

“…ICPs have been proposed as active masses, first of primary and secondary batteries, and later of supercapacitors, since the discovery of their reversible redox behavior, suggesting employment of the proceeding transitions for charge storage [ 52 , 53 , 56 , 57 , 92 , 93 ]. Possible charge densities are large enough to suggest further investigations.…”

Weak Polyelectrolytes as Nanoarchitectonic Design Tools for Functional Materials: A Review of Recent Achievements

“…The resulting films can combine electron conductivity with weak polybase characteristics, conferring them with doping, complexation, and molecular imprinting abilities. A large number of recent studies have used these appealing properties to design sensors, energy devices, light-emitting devices, and electrochromic and “smart” electrodes, as described in recent reviews [ 72 , 73 , 74 , 75 , 76 ]. The presence of aromatic cycles in such polymers also confers them with a hydrophobic character and self-assembling properties that enable them not only to act as weak polyelectrolytes but also as structure directing nano-units ( Figure 2 B).…”

A Conjugately Configured Supercapacitor with Suppressed Self-Discharge by Coupling Pairs of Presodiated Manganese Oxides

“…Currently, the mechanisms proposed for self-discharge include ohmic leakage, charge redistribution, and Faradaic reactions. ,,− Ohmic leakage refers to the loss due to incomplete isolation between positive and negative electrodes. ,, Charge redistribution refers to the loss caused by the transfer of absorbed charged ions due to the concentration gradient. , The Faradaic reaction is caused by the irreversible reaction between the electrodes and the impurities in the electrolytes. ,− So far, the research on the inhibition of self-discharge has mainly focused on improving the electrochemical stability of one component of the device such as the modification of the electrode surface, ,, electrode coating, , the improvement of the electrolyte, − or designing functional separators. − Theoretically, the self-discharge process of one electrode is accompanied with the desorption of ions and the dissipation of electrons, which is coupled with the electrochemical behavior of the counter electrode. − This indicates that the configuration of the device might have a decisive effect on the self-discharge behavior. , However, as far as we know, the viability to suppress self-discharge based on designing the configuration of the device remains unknown.…”

“…50−52 This indicates that the configuration of the device might have a decisive effect on the self-discharge behavior. 53,54 However, as far as we know, the viability to suppress self-discharge based on designing the configuration of the device remains unknown.…”