A study on the structural modification of vanadium oxide as a cathode material for a high-performance lithium-ion battery

Abstract

In recent years, the popularity of high-power equipments such as electric vehicles require a higher the energy density, higher the power density and lower cost of lithium-ion batteries (LIBs). Among the cathode materials, vanadium pentoxide (V2O5) is considered as an attractive cathode material for LIBs due to its high theoretical capacity (~294 mAhg-1). Nevertheless, its commercialization is challenging owing to the its poor cycling stability and rate-capability caused by severe structural changes and the sluggish electrons/lithium transportation during the repeated lithium intercalation/de-intercalation. Meanwhile, since the [010] is the fastest growth direction and [001] is the slowest due to the weak c-axis bonding in V2O5, many studies have used rod-like 1D V2O5 with the length along [010]. However, [010] corresponds to the energy preferred lithium ion (Li+) diffusion path, so the Li+ diffusion distance along [010] direction in rod shaped V2O5 is long. In this work, we report the simple lithium-treatment method for synthesis of nanoplates-stacked structured V2O5 (Li-treated VO) with highly exposed (010) facets and shorter [010] growth-length (0.7-1.4 um, compared with ~20 um of V2O5 nanobelt (VO)) which could facilitate the fast and efficient transportation of Li+ into the [010] channel. As a result, in the window voltage of 2.05-4.0 V (vs. Li/Li+), the Li-treated VO electrode exhibits a higher rate performance (140 mAh g-1 at 1 A g-1) and cycling capability (79% capacity retention after 100 cycles), compared to the untreated VO electrode. Furthermore, the reversible lithium intercalation reaction and structure stability of Li-treated VO is confirmed by cyclic voltammetry and ex-situ TEM images, respectively.