Polypyrrole as a Novel Chloride‐Storage Electrode for Seawater Desalination

Abstract

The desalination battery is regarded as a promising high‐efficiency technology for seawater desalination on account of the reversible salt‐ion storage in the bulk of the battery electrodes. Herein, polypyrrole is used as a new electrode to store chloride ions in seawater desalination. The as‐prepared polypyrrole composite electrode shows good electrochemical reversibility in chloride‐ion storage and removal in the aqueous NaCl electrolyte. When this chloride electrode is incorporated with a sodium electrode of sodium manganese oxide, a desalination battery that can capture chloride and sodium ions from the electrolyte through the electrochemical redox reactions is obtained. A stable and reversible capacity of 40 mAh g−1 of the desalination battery is achieved after 200 cycles.

Faradaic Electrodes Open a New Era for Capacitive Deionization

“…[56,137] As typical redox-active moiety-embedded polymers, p-type conducting polymers such as polypyrrole and polyaniline can undergo p-doping/dedoping reactions to capture/release Cl − . [138,139] Moreover, polymers can also be endowed with electrochemical activity by integrating www.advancedsciencenews.com www.advancedscience.com redox-active moieties on polymer backbones, such as by grafting electron donor/withdrawing groups (such as -SO 3…”

“…Li et al [138] synthesized a redox-active polyimide, poly[N,N′-(ethane-1,2-diyl)-1,4,5,8-naphthalenetetracarboxiimide] www.advancedsciencenews.com www.advancedscience.com Figure 25. Schematic representation of a) the redox reaction of aromatic polyimide with Na + and b) the p-doping and n-doping reactions of polypyrrole.…”

“…The most typical ones involve conjugated conductive polymers, which undergo redox reactions through doping/dedoping ions on the -conjugated double bonds of polymer backbone. [138,278] They can either be pdoped with counter-anions, or n-doped with counter-cations to maintain electrical neutrality, [139,278] as shown in the representative equation (Figure 25b) using polypyrrole as an example.…”

“…In general, most of the typical conjugated conductive polymers are more inclined to be p-doped with counter-anions, termed as the p-type polymers, such as polyaniline (PANi) and polypyrrole (PPy). For example, Kong et al [138] reported a p-type polypyrrole doped with chloride ion (PPyCl) as the Cl − capture anode for desalination, coupled with a Na 0.44 MnO 2 as the Na + capture cathode. As shown in CV curves (Figure 26c), the redox couple of the PPyCl anode corresponded to the release/capture of Cl − from/into the PPyCl anode.…”

Frozen‐State Polymerization as a Tool in Conductivity Enhancement of Polypyrrole

“…Polypyrrole (PPy) has gathered compelling attention among conducting polymers due to its facile preparation and unique physico-chemical properties. [1,2] As a result of its relatively high conductivity, environmental stability, and biocompatibility, PPy has been used in many applications, for example, bio and gas sensors, [3,4] micro-actuators, [5] battery electrodes, [6,7] supercapacitors [8,9] and adsorption. [10] The insolubility and infusibility of PPy have restricted its practical applications; however, its processability and more importantly, conductivity can be improved by the formation of nanostructures.…”