There exists an extensive literature on the electronic structure of transition-metal phthalocyanines (TMPcs), either as single molecules or adsorbed on surfaces, where explicit intra-atomic Coulomb interactions of the strongly correlated orbitals are included in the form of a Hubbard U term. The choice of U is, to a large extent, based solely on previous values reported in the literature for similar systems. Here, we provide a systematic analysis of the influence of electron correlation on the electronic structure and magnetism of several TMPcs (MnPc, FePc, CoPc, NiPc, and CuPc). By comparing calculated results to valence-band photoelectron spectroscopy measurements, and by determining the Hubbard term from linear response, we show that the choice of U is not as straightforward and can be different for each different TMPc. This, in turn, highlights the importance of individually estimating the value of U for each system before performing any further analysis and shows how this value can influence the final results.

Two conjugated covalent organic frameworks (COFs) are successfully synthesized and are introduced as the interface modifier in perovskite solar cells (PVSCs) to enhance the overall performance.

NIBs) are one of the most attractive alternative electrochemical energy storage systems because they use cheaper and more abundant sodium based materials. In addition, the potential of Na/Na + is only 0.3 V higher than that of Li/Li + , which suggests that similar energy density for both battery types is achievable. [3] We note that many materials which are efficient in LIB are not efficient in NIBs, [4] primarily due to the poor kinetics and thermodynamics of Na + insertion/desertion reaction caused by the relatively larger ionic radius of Na + versus Li + (102 pm versus 76 pm). [5] Furthermore, the commonly used electrode materials in batteries are made of inorganic compounds, which rely on limited nonrenewable mineral resources and require energy intensive synthetic processes. [6] Therefore, development of green, flexible, and sustainable materials for energy storage with minimal negative environmental impact is mandatory and has been gaining increasing attention.In contrast to inorganic materials, organic electrode materials display the advantages of low cost, structural diversity, and ease of processing in an ecofriendly way from potentially renewable sources. [7][8][9] Their highly flexible structures and tunability at the molecular level compared with inorganic compounds could provide high mobility of Na + ions, as the performance of organic battery materials is not quite sensitive to the cation's ionic radius. [10] A large number of organic materials have already been reported as electrodes in NIBs and can be classified as low molecular weight compounds (such as carbonyl, carboxylate, and anhydride) and organic polymers (such as stable radical, conductive, organometallic, and microporous polymers). [8,9,11] Among them, organic electrode materials based on carboxylates and their salts are attractive due to their high electrochemical activity for reversible storage of sodium or lithium ions. [12] Furthermore, organic salts formed from the carboxylate have higher polarity which helps preventing the dissolution of electrode materials in electrolytic solution and hence could achieve better cycling stability. [13] In sodium carboxylates, Na ions usually insert at a potential below 1 V (versus Na + /Na) and thus these carboxylates can be employed as potential anode materials. As an example, a disodium terephthalate salt (Na 2 TP) and a 4,4-biphenyldicarboxylate sodium A combined experimental and computational study of disodium pyridine-2,5-dicarboxylate (Na 2 PDC) is presented exploring the possibility of using it as a potential anode for organic sodium-ion batteries. This electrode material can reversibly insert/release two Na cations per formula unit, resulting in high reversible capacity of 270 mA h g −1 (236 mA h g −1 after accounting for the contribution from Super P carbon) with excellent cyclability 225 mA h g −1 , with retention of 83% capacity after 100 cycles, and good rate performance with reversible capacity of 138 mA h g −1 at a 5 C rate. The performance of disodium pyridine dicarboxylate is there...

Abstract

We present the first atomistic-scale simulation of the discharge process of polymeric cathode materials for electrochemical batteries in solid state. The oxidation of polyaniline (PANI) and of cyano groups (CN) functionalized PANI induced by coordination to the electrolyte anions is computed and voltage curves are estimated. To deal with the large required numbers of atoms and structures, a combination of molecular dynamics and density functional tight binding (DFTB) is used. The DFTB is benchmarked to density functional theory (DFT) calculations using different functionals to confirm its accuracy. The voltages computed with the solid state model are in good agreement with available experimental data and ab initio models based on oligomers. The solid state model also predicts substantially increased voltage with PANI functionalized with cyano groups.