Multistage redox reactions of conductive-polymer nanostructures with lithium ions: potential for high-performance organic anodes

Abstract

Conducive polymers have a wide range of applications originating from their π-conjugated systems. The redox reactions of conductive polymers with doping and dedoping of anions have been applied to cathodes for charge storage. In contrast, the redox reactions with cations have not been fully studied in anodes for charge storage. Here, we found that the nanostructures of conductive polymers, such as polypyrrole (PPy) . The introduction of a carboxy group to the pyrrole and thiophene rings enhanced the specific capacities up to 730 and 963 mAh g -1 , respectively. The enhanced electrochemical properties were not observed in the bulk-size conductive polymers. The results suggest that conductive-polymer nanostructures have potential for developing metal-free, high-performance charge storage devices.

Experiment‐Oriented Materials Informatics for Efficient Exploration of Design Strategy and New Compounds for High‐Performance Organic Anode

“…Morphologies in sub‐micrometer scales contribute to ensure the diffusion of electrolyte solution. As for organic anode, the nanoparticles of polypyrrole and polythiophene with carboxy groups showed the enhanced specific capacity . This previous work implied the importance of not only the morphology but also the energy level of lowest unoccupied molecular orbital (LUMO) for the capacity.…”

“…Control of reaction potential and enhancement of specific capacity are achieved by molecular design of organic cathodes. Exploration of organic anode as an alternate of graphite has been rapidly developed during the past decade (Tables S1, S2 and Figure S1, Supporting Information) . Carboxy group on π‐conjugated molecules shows reversible reaction with lithium ion (Li + ) around 1.5 V versus Li/Li + .…”

“…Further reduction induces incorporation of multiple Li + within 0–1.5 V versus Li/LI + . On the basis of these studies, the ladder, main‐chain, and side‐chain polymers were synthesized to achieve high specific capacity with cycle stability and rate performance . A couple of biological and biomimetic macromolecules exhibited high specific capacity and cycle stability .…”

Experimental and Theoretical Studies of Trisodium‐1,3,5‐Benzene Tricarboxylate as a Low‐Voltage Anode Material for Sodium‐Ion Batteries

“…Organic compounds also have the advantages of structural diversity, [22] biocompatibility, and environmental-friendliness. [8,23] Organic anodes have shown superior lithium storage capacity and excellent rate capabilities, e.g., maleic acid [24] can deliver a capacity of 900 mAh g À1 over 500 cycles, and polythiophenebased polymers [25] deliver capacities of 960 mAh g À1 at 20 mA g À1 . The stability of polypyrrole electrodes over 1000 cycles has also been demonstrated.…”

Redox-active polymers as promising electrodes for rechargeable lithium batteries

“…[114] Thus, state-of-the-art investigations have been mainly focused on conjugated polymers (conductive polymers can be also regarded as a type of conjugated polymers) as well as polymers with multiple redox-active carbonyl groups. [115][116][117][118][119][120][121][122][123][124][125] Therefore, this thesis will mainly focus on these two types of polymers. Surprisingly, recent progress showed that the electrochemical performances including energy density, power density and cycling stability of redox-active polymers are comparable to or even superior than the conventional inorganic materials.…”