Electronic structure of high-T c superconductors and related compounds

We study a 5-band Hubbard model for the CuO₂ planes in cuprate super-conductors using Hartree-Fock mean-field theory including spiral spin density waves. For the half-filled case we recover a ZSA-like phase diagrambut with an additional new region characterized by strong covalency effects, which we call a covalent insulator region. We also provide a nonperturbative calculation ofJ _eff, the effective in-plane antiferromagnetic interaction, as a function of parameters of the model. We suggest that the high-T _c cuprates are in or very close to the covalent insulator region and within this we show that a consistent explanation of apparently conflicting high energy spectroscopic and magnetic measurements of the high-T _c cuprates can be given.     

Polyimide Compounds For Post-Lithium Energy Storage Applications

The exploration of cathode and anode materials that enable reversible storage of mono and multivalent cations has driven extensive research on organic compounds. In this regard, polyimide (PI)-based electrodes have emerged as a promising avenue for the development of post-lithium energy storage systems. This review article provides a comprehensive summary of the syntheses, characterizations, and applications of PI compounds as electrode materials capable of hosting a wide range of cations. Furthermore, the review also delves into the advancements in PI based solid state batteries, PI-based separators, current collectors, and their effectiveness as polymeric binders. By highlighting the key findings in these areas, this review aims at contributing to the understanding and advancement of PI-based structures paving the way for the next generation of energy storage systems.