Spray-drying synthesis and vanadium-catalyzed graphitization of a nanocrystalline γ-Li_3.2V_0.8Si_0.2O₄/C anode material with a unique double capsule structure

Abstract

By means of a simple spray-drying method, a unique double capsule structure of nanocrystalline lithium superionic conductor (LISICON)-type γ-Li3.2V0.8Si0.2O4 (γ-LVSiO) has first been obtained for anodes of hybrid supercapacitors. The...

Enhancing the Phase Stability of γ-Phase Li3VO4 for High-Performance Hybrid Supercapacitors: Investigating Influential Factors and Mechanistic Insights

“…Due to its excellent properties, LVO has been anticipated as an alternative to commercial anode materials like lithium titanate or graphite. − The crystal structure of LVO features a wurtzite-type three-dimensional (3D) framework, where LiO 4 and VO 4 tetrahedra are interconnected through corner sharing, which is favorable for Li + diffusion but unfavorable for electron conduction . Various strategies have been employed to enhance its low electric conductivity, such as compositional adjustments involving carbon, − control of morphologies, − and particle downsizing, demonstrating the significant improvement in the high-rate performance. For instance, as we reported in 2016, nanocrystalline LVO/MWCNT (multiwalled carbon nanotubes) composites showcased ultrafast rate capabilities sufficient as an anode for a hybrid supercapacitor, maintaining 50% of their capacity at a rate of 20 A g –1 .…”

“…To address these challenges, researchers have explored the substitution of vanadium ions (V 5+ ) in LVO with various transition metal ions (M 4+ ), resulting in the formation of different polymorphs. ,− Among the various potential polymorphs and solid-solution systems, particular attention has been drawn to the γ-phase of LVO (γ-LVO). This interest arises from its exceptional ionic conductivity, stemming from the LISICON (Lithium Super Ionic CONductor) structure. − γ-LVO exhibits pseudocapacitive charge/discharge behavior along with high-power and high-cycle properties, comparable to the cation-disordered LVO . However, there is a warning: the γ-phase is stable only at temperatures exceeding 700 °C and readily reverts to the β-phase when cooled to room temperature, thus losing its superior properties.…”

“…26−28 γ-LVO exhibits pseudocapacitive charge/discharge behavior along with high-power and high-cycle properties, comparable to the cation-disordered LVO. 11 However, there is a warning: the γ-phase is stable only at temperatures exceeding 700 °C and readily reverts to the β-phase when cooled to room temperature, thus losing its superior properties.…”

One-step uniform rotation solvothermal synthesis of a Li3VO4@rGO anode material with superior cycling and rate performance

“…16 On the other hand, Li 3 VO 4 possesses a higher theoretical capacity (592 mA h g −1 , corresponding to xLi + + Li 3 VO 4 + xe − ↔ Li 3+x VO 4 ) and a lower working potential than Li 4 Ti 5 O 12 (175 mA h g −1 ). [17][18][19] Structural stability contributes to the small volume expansion (<20%) of Li 3 VO 4 during charging and discharging. 20 All these merits make Li 3 VO 4 a potential alternative to graphite.…”