Cactus-like iron diphosphide@carbon nanotubes composites as advanced anode materials for lithium-ion batteries

The ball-cactus-like iron diphosphide@carbon nanotubes (FeP2@CNTs) composites are synthesized via a simple chemical vapor deposition (CVD) with two-step heating method. SEM, TEM, XRD and Raman spectrum confirm that FeP2 and CNTs exist as the core and the surrounding spines of the ball-cactus-like composite, respectively, for FeP2@CNTs synthesized under suitable conditions. With optimized FeP2@CNTs composite containing ball-catus-like structure as the anode of LIBs, the assembled batteries exhibit an initial coulombic efficiency of 91.6%. Furthermore, this kind of battery delivers a stable and high discharge specific capacity of 736.2 mAh g(-1) at 0.1 C (1 C = 1365 mA g(-1)) after 100 cycles. Even at a higher rate of 2.5 C, it still delivers a stable discharge specific capacity of 650.2 mAh g(-1) within 100 cycles with negligible capacity fading, much higher than the reported results to date. This excellent electrochemical performance of FeP2@CNTs composite is attributed to the cladding of FeP2 with CNTs, which prevent the large volume changes of FeP2 and improve the electrical conductivity of composites. (c) 2017 Elsevier Ltd. All rights reserved.