PEDOT Encapsulated and Mechanochemically Engineered Silicate Nanocrystals for High Energy Density Cathodes

Abstract

Lithium iron silicate (LFS) attracts a lot of attention due to its 330 mAh g−1 theoretical capacity (2 Li+ per formula unit). However, inherently it exhibits poor Li‐ion intercalation kinetics, interfacial reactivity, and complex phase transitions resulting in lower than one Li+ capacity and poor retention. In this work, a core–shell architecture is devised largely overcoming these obstacles. At first, the nanostructure of Pmn21 LFS is annealed via mechanochemical processing enabling the activation of Li‐ion diffusion. Subsequently, the LFS nanocrystals are coated via in situ poly(3,4‐ethylenedioxythiophene) (PEDOT) polymerization involving partial chemical de‐lithiation/re‐lithiation, the latter catalyzed with FeCl3. As a result of the devised mechanochemical/interphasial engineering of the LFS@PEDOT nanocrystals, their Li‐ion storage capacity is augmented to > 1 Li, namely 200 mAh g−1 after 50 cycles or 1.2 Li+ units—the highest capacity reported for the Pmn21 LFS cathode. A key attribute of the new PEDOT coating technique is the generation of a Fe3+‐rich subsurface layer that contributes to structure stabilization via accelerated phase transition to inverse Pmn21 phase, in addition to rendering the nanocrystals electronically conductive and protected against reaction with electrolyte. Such core–shell engineered nanocrystals provide a powerful paradigm in developing viable high energy density cathodes for next‐generation Li‐ion batteries.

Intrinsically conducting polymers and their combinations with redox-active molecules for rechargeable battery electrodes: an update

“…Particles of lithium iron silicate, a material with an attractive theoretical charge density, have been encapsulated with PEDOT (Rasool et al 2020). Some of the numerous drawbacks limiting its application initially could be mitigated.…”

Multi-Layer TiO2−x-PEDOT-Decorated Industrial Fe2O3 Composites as Anode Materials for Cycle-Performance-Enhanced Lithium-Ion Batteries

“…The composites remained at a specific capacity of 770 mAh g −1 after 200 cycles under a current density of 200 mA g −1 [35]. Conductive polymers, such as polypyrrole (PPY) [36,37], polyaniline (PANI), and poly 3,4-ethylenedioxythiophene (PEDOT) [38,39] etc., were applied in energy storage devices for a long time for their long cycling performance. Jeong et al [40] designed a hierarchical hollow spheres structure with PANI as a coating layer, and the composites exhibited an excellent rate performance and cycling stability during 100 cycles, remaining at 732 mAh g −1 .…”