Electrochemical and spectroscopic studies on carbon‐coated and iodine‐doped LiFeBO₃ as a cathode material for lithium‐ion batteries

Abstract

In this study, monoclinic LiFeBO 3 was carbon-coated and iodine doped via a solid-state reaction to improve the electrochemical performance of pristine LiFeBO 3 as cathode material in lithium-ion batteries. In order to enhance the electrical conductivity of LiFeBO 3 , the highly electronegative iodide anion was doped in a limited amount (x = 0.005) at the oxygen site of the borate to produce LiFeBO 3Àx I 2x . A thin carbon layer was then deposited in situ on the LiFe-BO 2.995 I 0.01 particles (to produce "LFBI/C") to protect them from air and moisture. Field-emission scanning electron microscopy (FE-SEM) data indicated the aggregated morphology of the synthesized samples. Powder X-ray diffraction (XRD) and 7 Li magic angle spinning (MAS) nuclear magnetic resonance (NMR) measurements revealed that both the doped and undoped LiFeBO 3based samples had mainly monoclinic structures, although a small amount of a vonsenite-type phase was formed upon iodine doping. X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX) data confirmed the successful insertion of iodine in the cathode material. The specific discharge capacity of LFBI/C at 0.05 C rate (144.68 mAh g À1 ) was higher than that of carbon-coated LiFeBO 3 (122.46 mAh g À1 ). The increased capacity of LFBI/C was also evident in long charge-discharge cycles conducted at 1 C rate and in the overall rate performance. Interestingly, the iodine-doped sample exhibited significantly high specific discharge capacity even at 10 C rate.

Li‐ion hopping conduction enabled by associative Li‐salt in acetonitrile solutions

“…The demand for safe, high-energy Li-ion batteries (LIBs) is constantly increasing across various applications, including electric vehicles and large-scale electric storage. [1][2][3] To meet the expectations for advanced battery systems, it is essential to develop innovative functional electrolytes that ensure the stable, rapid operation of LIBs. [4][5][6][7][8] In particular, the rate capability of LIBs heavily depends on the mass transport rate in the electrolytes, which is largely influenced by ion-ion and ion-solvent interactions.…”