An Aqueous Conducting Redox‐Polymer‐Based Proton Battery that Can Withstand Rapid Constant‐Voltage Charging and Sub‐Zero Temperatures

Abstract

Electrodes based on organic matter operating in aqueous electrolytes enable new approaches and technologies for assembling and utilizing batteries that are difficult to achieve with traditional electrode materials. Here, we report how thiophene‐based trimeric structures with naphthoquinone or hydroquinone redox‐active pendent groups can be processed in solution, deposited, dried and subsequently polymerized in solid state to form conductive (redox) polymer layers without any additives. Such post‐deposition polymerization offers efficient use of material, high mass loading (up to 10 mg cm−2) and good flexibility in the choice of substrate and coating method. By employing these materials as anode and cathode in an acidic aqueous electrolyte a rocking‐chair proton battery is built. The battery shows good cycling stability (85 % after 500 cycles), withstands rapid charging, with full capacity (60 mAh g−1) reached within 100 seconds, allows for direct integration with photovoltaics, and retains its favorable characteristics even at −24 °C.

Recent Advances in Aqueous Batteries with Nonmetal Cations as Charge Carriers

“…Reproduced with permission. [ 36 ] Copyright 2020, Wiley‐VCH GmbH. f) The structural variation mechanism of H 3+ x IrO 4 .…”

“…In Sjödin et al's study, an aqueous conducting redox‐polymer‐based proton battery was built, where 0.5 m H 2 SO 4 (aq) was used as electrolyte, benzoquinone/hydroquinone (Q/QH2) and naphthoquinone/naphthohydroquinone (NQ/NQH 2 ) as cathode and anode material (Figure 1d). [ 36 ] The cathode redox activity relied on the two‐electron two‐proton (2e2H) redox process of the pendants. During oxidation process, the cathode material was converted to QH2 with a discharge capacity of ≈80 mAh g −1 at 3C.…”

“…[42] Moreover, recent studies have demonstrated that the aqueous proton batteries could exhibit encouraging performance even at and below À90 C, showing promising applications in extremely cold area and deep space. [36,42,52] NH 4 þ ions as charge carriers have received much attention due to the abundant sources and low cost. It has a small hydrated ionic size and could promote faster kinetics.…”

“…d) The cathode material pEP(QH2)E. e) The cathode redox activity depends on the two-electron two-proton (2e2H) redox process of the pendants. Reproduced with permission [36]. Copyright 2020, Wiley-VCH GmbH.…”

Organic–Inorganic Hybridization Engineering of Polyperylenediimide Cathodes for Efficient Potassium Storage

“…[15,16] Up till now, the polyperylenediimide (PDI), as a typical covalent organic framework, stands out from others, and has been explored for potassium storage because of its abundant redox building blocks, well-ordered skeleton and enriched nanopores. [17,18] Nonetheless, the PDI compounds themselves are plagued by their poor conductivity, high activation energies of active sites (C = C and C = N), and inferior electrochemical stability due to easy loss of active sites over cycling. [19] Thus, the purposeful incorporation of inorganic phases into PDI towards highly conductive organic-inorganic hybrids with mutual chemical interactions and superior mechanical flexibility is an optimal choice to increase conductivities, achieve more redox sites by declining activation barriers, and approach the well-inherited active sites during cycling.…”