Irina A. Chepurnaya

For the first time, polymeric forms of the complexes N,N'-bis(salicylidene)ethylenediaminonickel (II) and N,N'-bis(3-methoxysalicylidene)ethylenediaminonickel (II) have been investigated as functional materials for the conducting channels of organic electrochemical transistors. The dependence of the electrical conductivity of the polymers on the electrolyte anion-doping level has been established. The polymer film conductance versus gate voltage curve parameters have been shown to depend on the molecular structure of the complex and the nature of the electrolyte solvent.

The electrochemical oxidation and reduction of polymeric nickel(II) complex of N,N′-bis(3-methoxysalicylidene)ethylenediamine is investigated in acetonitrile- and 1,2-dichloroethane-based solutions by a combination of in situ conductivity measurements, quartz-crystal microbalance, and cyclic voltammetry. The type of electrolyte solution is shown to have a pronounced effect on the variations in the electrical conductivity and ion and solvent transfer at the polymer/solution interface when the polymer is electrochemically switched between different oxidation states.

The electrochemical oxidation-reduction of polymeric nickel(II) complex of N,N′-bis(3-methoxysalicylidene)ethylenediamine was investigated in acetonitrile and 1,2-dichloroethane-based solutions by a combination of in situ conductance measurements, quartz crystal microbalance, and cyclic voltammetry. The type of electrolyte solution is shown to have a pronounced effect on the variations in the electrical conductance and ion and solvent transfer at the polymer/solution interface when the polymer is electrochemically switched between various oxidation states.

Conductive electrochemically active metallopolymers are outstanding materials for energy storage and conversion, electrocatalysis, electroanalysis, and other applications. The hybrid inorganic–organic nature of these materials ensures their rich chemistry and offers wide opportunities for fine-tuning their functional properties. The electrochemical modulation of the nanomechanical properties of metallopolymers is rarely investigated, and the correlations between the structure, stiffness, and capacitive properties of these materials have not yet been reported. We use electrochemical atomic force microscopy (EC-AFM) to perform in-situ quantitative nanomechanical measurements of two Schiff base metallopolymers, poly[NiSalphen] and its derivative that contains two methoxy substituents in the bridging phenylene diimine unit poly[NiSalphen(CH₃O)₂], during their polarization in the electrolyte solution to the undoped and fully doped states. We also get insight into the electrochemical p-doping of these polymers using electrochemical quartz crystal microgravimetry (EQCM) coupled with cyclic voltammetry (CV). Combined findings for the structurally similar polymers with different interchain interactions led us to propose a correlation between Young’s modulus of the material, its maximum doping level, and ion and solvent fluxes in the polymer films upon electrochemical oxidation.

As a cathode material for lithium-ion batteries, lithium iron phosphate (LiFePO₄, LFP) successfully transitioned from laboratory bench to commercial product but was outshone by high capacity/high voltage lithium metal oxide chemistries. Recent changes in the global economy combined with advances in the battery pack design brought industry attention back to LFP. However, well-recognized intrinsic drawbacks of LiFePO₄ such as relatively low specific capacity and poor electronic and ionic conductivity have not yet been fully mitigated. Integration of electrochemically active electron-conducting polymers (EAECPs) into the cathode structure to replace conventional auxiliary electrode components has been proposed as an effective strategy for further performance improvement of LFP batteries. In this review, we show how various combinations of polymer properties/functions have been utilized in composite LiFePO₄ electrodes containing EAECP components. We present recent advances in the cathode design, materials, and methods and highlight the impact of synthetic strategies for the cathode preparation on its electrochemical performance in lithium-ion cells. We discuss advantages and limitations of the proposed approaches as well as challenges of their adoption by the battery manufactures. We conclude with perspectives on future development in this area.

For the first time, polymeric forms of the complexes N,N'-bis(salicylidene)ethylenediaminonickel(II) and N,N'-bis(3-methoxysalicylidene)ethylenediaminonickel(II) have been investigated as functional materials for the conducting channels of organic electrochemical transistors. The dependence of the electrical conductivity of the polymers on the electrolyte anion-doping level has been established. The polymer film conductance versus gate voltage curve parameters have been shown to depend on the molecular structure of the complex and the nature of the electrolyte solvent. Keywords: organic electronics, electrochemical transistor, nickel-salen polymer, conductivity, doping.

Зависимость электрической проводимости никель-саленовых полимеров от напряжения затвор-исток в электрохимическом транзисторе

Metal–ligand interactions in monomeric and polymeric transition metal complexes of Schiff base ligands largely define their functional properties and perspective applications. In this study, redox behavior of a nickel(II) N₄-anilinosalen complex, [NiAmben] (where H₂Amben = N,N′-bis(o-aminobenzylidene)ethylenediamine) was studied by cyclic voltammetry in solvents of different Lewis basicity. A poly-[NiAmben] film electrochemically synthesized from a 1,2-dichloroethane-based electrolyte was investigated by a combination of cyclic voltammetry, electrochemical quartz crystal microbalance, in situ UV-Vis spectroelectrochemistry, and in situ conductance measurements between −0.9 and 1.3 V vs. Ag/Ag⁺. The polymer displayed multistep redox processes involving reversible transfer of the total of ca. 1.6 electrons per repeat unit, electrical conductivity over a wide potential range, and multiple color changes in correlation with electrochemical processes. Performance advantages of poly-[NiAmben] over its nickel(II) N₂O₂ Schiff base analogue were identified and related to the increased number of accessible redox states in the polymer due to the higher extent of electronic communication between metal ions and ligand segments in the nickel(II) N₄-anilinosalen system. The obtained results suggest that electrosynthesized poly-[NiAmben] films may be viable candidates for energy storage and saving applications.