Molecule and Microstructure Modulations of Cyano-Containing Electrodes for High-Performance Fully Organic Batteries.

ABSTRACT

Cyano-containing electrodes usually promise high theoretical potentials while suffering from uncontrollable self-dissolution and sluggish reaction kinetics. Herein, to remedy their limitations, an unprecedented core-shell heterostructured electrode of carbon nanotubes encapsulated in poly(1,4-dicyanoperfluorobenzene sulfide) (CNT@PFDCB) is rationally crafted via molecule and microstructure modulations. Specifically, the linkage of sulfide bridges of PFDCB prevents the active cyano groups from dissolving, resulting in a robust structure. The fluorinations modulate the electronic configurations in frontier orbitals, allowing higher electrical conductivity and elevated output voltage. Combined with the core-shell architecture to unlock the sluggish diffusion kinetics for both electrons and guest ions, the CNT@PFDCB exhibits an impressive capacity (203.5 mAh g-1), remarkable rate ability (127.6 mAh g-1 at 3.0 A g-1), and exceptional cycling stability (retaining 81.1 % capacity after 3000 cycles at 1.0 A g-1). Additionally, the Li-storage mechanisms regarding PFDCB are thoroughly revealed by in situ attenuated total reflection infrared spectroscopy, in situ Raman spectroscopy, and theoretical simulations, which involve the coordination interaction between Li ions and cyano groups and the electron delocalization along the conjugated skeleton. More importantly, a practical fully organic cell based on the CNT@PFDCB is well-validated that demonstrates a tremendous potential of cyanopolymer as the cathode to replace its inorganic counterparts.