Pyromellitic Diimide-Based Copolymers and Their Application as Stable Cathode Active Materials in Lithium and Sodium-Ion Batteries

Abstract

Organic molecules are emerging candidates for the next generation of cost-effective active materials of Li-ion batteries. Small diimide building blocks such as pyromellitic diimide (PMDI) have attracted much attention because of their high theoretical capacity. Many strategies have been undertaken to limit the well-known phenomenon of dissolution of the active material in the electrolyte. Such strategies include the preparation of salts and the synthesis of polyimides or macrocycles. Since dibromopyromellitic dimiide exhibits almost no sp2 cross-coupling polymerization reaction by conventional synthetic routes (Suzuki–Miyaura or Migita–Stille), we used PMDI as an aromatic C–H bond-bearing unit for direct (hetero)­arylation polymerization (DHAP) with 1,4-dibromobenzene as comonomer as a new stabilization strategy. DHAP proved to be an effective tool in the preparation of this polymer, yielding a number-average molecular weight of up to 31 kDa. We studied the effect of side-chain engineering using variable chain lengths, cross-linked structures, and thermocleavable functional groups. Practical potential limits of 1.65 to 2.50 V vs Li/Li+, wherein two distinct redox phenomena appear, and a galvanostatic high rate limit of 2C were determined. Galvanostatic measurements at C/20 show a starting normalized capacity of 0.94 decreasing to 0.48 after more than 80 days (50 cycles). A maximum discharge capacity of 73 mAh/g as a first cycle was obtained for a polymer of this family at C/10. Density functional theory calculations were applied to understand the higher corrected redox potentials obtained by cyclic voltammetry for sodium ion over lithium ion batteries.

Identifying the Trade-off between Intramolecular Singlet Fission Requirements in Donor–Acceptor Copolymers

“…[46][47][48][49][50][51] Nsubstituted side-chains on the amide and imide moieties found on isoindigo (iI), diketopyrrolopyrrole (DPP), naphthalene diimide (NDI) and thienopyrroledione (TPD) acceptors are readily accessible through the condensation of anhydrides with amines and substitutions reactions. 52,53 These sites and similar ones on other cores are tagged for side-chain substitution, as shown by the 'R' in Figure 1.…”

Supramolecular complexation between chain-folding poly(ester-imide)s and polycyclic aromatics: a fractal-based pattern of NMR ring-current shielding

“…Starting materials, solvents, diacyl chlorides ClCO(CH 2 ) x COCl (x = 1-4 and 6-8), and heptanedioic acid were purchased from Sigma-Aldrich, ThermoFisher or Fluorochem and were used as received. The diimide-based diols N,N′-bis(2-hydroxyethyl)hexafluoro-isopropylidene-diphthalimide (1) 20 N,N′-bis(2-hydroxyethyl)-pyromellitimide (2), 21 and N,N′-bis(2-hydroxyethyl) naphthalene-1,4,5,8-tetracarboxylic diimide (3) 22 were synthesised as noted below. Proton and 13 C NMR spectra were recorded on a Bruker Nanobay 400 spectrometer (400 MHz for 1 H and 100 MHz for 13 C NMR) and on a Bruker AVANCE 500 spectrometer with TCI Cryoprobe system (500 MHz for 1 H NMR).…”

Identifying the Trade-off between Intramolecular Singlet Fission Requirements in Donor-Acceptor Copolymers

“…[46][47][48][49][50][51] Nsubstituted side-chains on the amide and imide moieties found on isoindigo (iI), diketopyrrolopyrrole (DPP), naphthalene diimide (NDI) and thienopyrroledione (TPD) acceptors are readily accessible through the condensation of anhydrides with amines and substitutions reactions. 52,53 These sites and similar ones on other cores are tagged for side-chain substitution, as shown by the 'R' in Figure 1.…”