Pyromellitic diimide-based copolymers and their application as stable cathode active materials in lithium and sodium-ion batteries

13^th International Conference on Electrochemistry

May 27-28, 2019 | Barcelona, Spain

Nicolas Zindy, J. Terence Blaskovits, Catherine Beaumont, Julien Michaud-Valcourt, Hamidreza Saneifar, Paul A. Johnson, Daniel Belanger and Mario Leclerc

Universite Laval, Quebec, Canada.
Universite du Quebec a Montreal (UQAM), Canada

Posters & Accepted Abstracts: J Biosens Bioelectron

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 due to their high theoretical capacity. Many strategies have been undertaken to limit the well-known phenomenon of dissolution of the active mate-rial 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 2.50V 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.

Biography :