Redox‐active nitroxyl‐containing polymers are promising candidates as possible replacements for inorganic based energy‐storage materials, due to their high energy density and fast redox kinetics. One challenge towards the implementation of such a system is the insufficient electrical conductivity, impeding the charge collection even with highly conductive additives. Herein, the first implementation of a polymeric bis(salicylideniminato) nickel (NiSalen) conductive backbone as an active charge‐collecting wire is reported. NiSalen simultaneously serves as a charge collector for nitroxyl pendants and supports the redox capacity of the material. This novel polymer exhibits a specific capacity of up to 91.5 mAh g−1, retaining 87 % of its theoretical capacity at 800 C and more than 30 % at as high as 3000 C (66 % capacity retention after 2000 cycles). The properties of the new material upon operation was studied by means of operando electrochemical methods, UV‐Vis, and electron paramagnetic resonance spectroscopy.

The nickel salen‐type redox polymers represent an interesting class of organometallic polymers frequently used in hybrid supercapacitor electrodes as thin films and carbon material composites. However, the suitability of these compounds for application as electrode materials for rechargeable batteries has not yet been tested. In this study, redox processes in monocomponent electrodes based on a series of nickel salen‐type redox polymers are investigated in 1 m LiPF6 in 1:1 ethylene carbonate (EC)/diethyl carbonate (DEC) electrolyte in a Li‐ion battery. The oxidation potentials for polymer complexes of nickel exceed 3.5 V versus Li/Li+, which enhances specific energy. It is found that introduction of a proper substituent in the phenyl ring of the ligand allows to fabricate additive‐free electrodes which demonstrate high charge/discharge rate performance with the capacity on discharge at 10C being up to 73% of the capacity obtained at discharge at 1C, which corresponds to maximum power of 2.6 kW kg−1.

Reinvestigation of (o-benzoquinonedioximate)2Ni/I2 systems demonstrated that the reaction itself and also the crystallization conditions dramatically affect the identity of generated species. Crystallization (CHCl3, 20–25 °C) of the nickel­(II) dioximate complex [Ni­(bqoxH)2] (bqoxH2 = o-benzoquinonedioxime) with I2 in the 1:(1–10) molar ratios of the reactants led to several (o-benzoquinonedioximate)2Ni derivatives and/or iodine adducts [Ni­(I)­(bqoxH)­(bqoxH2)]·3/2I2, [Ni­(I3)­(bqoxH)­(bqoxH2)]·[Ni­(bqoxH)2], and [Ni­(I3)­(bqox•–)­(bqoxH2)]·I2; the latter one, featuring the anion-radical bqox•– ligand, is derived from the formal (−2H+/1e –)-oxidation of bqoxH2. In these three adducts, various types of noncovalent interactions were identified experimentally and their existence was supported theoretically. The [Ni­(I3)­(bqox•–)­(bqoxH2)]·I2 adduct exhibits simultaneous semicoordination and coordination patterns of the triiodide ligand; this is the first recognition of the semicoordination of any polyiodide ligand to a metal center. The semicoordination noncovalent contact Ni···I3 (3.7011(10) Å) is substantially longer that the Ni–I3 coordination bond (2.8476(9) Å), and the difference in energies between these two types of linkages is 8–12 kcal/mol.

Catechols are of great interest as cathode materials for energy storage due to the combination of high capacity and redox potential. However, pristine catechols possess poor electrical conductivity and dissolution stability. We propose a sulfonated polycatechol SPVQ with a high molecular mass, which can be used as an anionic redox-active dopant for the electrochemical deposition of poly(3,4-ethylenedioxythiophene) (PEDOT). Proposed polycatechol is designed to maximize the theoretical capacity as much as possible for the polymer bearing both catechol and sulfonate functionalities. The composite polymer shows an improved capacity due to the two-electron faradaic process of SPVQ compared to PEDOT:PSS (49 mA h g −1 vs 21 mA h g −1 ) and, being deposited on a carbon fiber, affords an areal capacitance of 264 mF cm −2 versus 87 mF cm −2 for PEDOT:PSS. Coulombic anchoring of SPVQ in the PEDOT matrix resulted in increased cycling stability of the material (70% capacity retention after 100 cycles and 35% after 1500 cycles). Scanning electron microscopy, operando spectroelectrochemical, and microgravimetric methods reveal a great impact of the polyanionic dopant structure on the morphology, ionic transport, and finally electrochemical performance of the composite material. The obtained results demonstrate the importance of fine tuning of the composition and morphology of the composite materials to ensure optimal interactions between the redox/anionic and conductive components.

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