Development of high performance composite lithium ion battery cathode systems with carbon nanotubes functionalised with bimetallic inorganic nanocrystal alloys

Abstract

Lithium ion cathode systems based on composites of lithium iron phosphate (LiFePO₄), iron-cobalt-derivatised carbon nanotubes (FeCo-CNT) and polyaniline (PA) nanomaterials were developed. The FeCo-functionalised CNTs were obtained through in-situ reductive precipitation of iron (II) sulfate heptahydrate (FeSO₄.7H₂O) and cobalt (II) chloride hexahydrate (CoCl₂.6H₂O) within a CNT suspension via sodium borohydrate (NaBH₄) reduction protocol. Results from high Resolution Transmission Electron Microscopy (HRTEM) and Scanning Electron Microscopy (SEM) showed the successful attachment FeCo nanoclusters at the ends and walls of the CNTs. The nanoclusters provided viable routes for the facile transfer of electrons during lithium ion deinsertion/insertion in the 3-D nanonetwork formed between the CNTs and adjacent LiFePO₄ particles.