Honeycomb-like amorphous VPO4/C spheres with improved sodium storage performance as anode materials for sodium-ion batteries

Amorphous and Crystalline Vanadium Orthophosphate and Oxidized Multiwalled Carbon Nanotube Composites as Anode Materials in Sodium‐Ion Batteries

“…NaPF 6 [35] α-VPO 4 /C (intercalation mechanism) 110 mAh g À 1 at 0.1 C (first cycle) NaPF 6 [32] VPO 4 /C (porous carbon framework) 728 mAh g À 1 at 0.1 A g À 1 (first cycle) 329 mAh g À 1 at 0.1 A g À 1 (after 100 cycles) [33] Honeycomb-like a-VPO 4 /C 421 mAh g À 1 at 0.1 A g À 1 (first cycle) NaClO 4 [31] Honeycomb-like c-VPO 4 /C 106 mAh g À 1 at 0.1 A g À 1 (first cycle) NaClO 4 [31] a-VPO 4 /ox-MWCNT 1680 mAh g À 1 at 0. Flower like VPO 4 /C 616 mAh g À 1 at 0.05 A g À 1 (first cycle) 350 mAh g À 1 at 0.2 A g À 1 (after 100 cycles) KFSI in DME [36] for [a] Theoretical capacity.…”

“…[33][34][35]37] Therefore, rapid capacity fading is achieved. The stabilization of capacity was obtained in the range of approximately 700-300 mAh g À 1 for lithium-ion batteries, [23][24][25][26][27][28][29][30][31][32][33][34] 300-250 mAh g À 1 for sodium-ion batteries [32][33][34][35] at a 0.1 C rate and 100 mAh g À 1 for potassium-ion batteries at a 0.5 C rate. [32,36] The capacity performance of anodic material is significantly affected by the SEI passivating films.…”

“…Therefore, rapid capacity fading is achieved. The stabilization of capacity was obtained in the range of approximately 700–300 mAh g −1 for lithium‐ion batteries, [23–34] 300–250 mAh g −1 for sodium‐ion batteries [32–35] at a 0.1 C rate and 100 mAh g −1 for potassium‐ion batteries at a 0.5 C rate [32,36] …”

“…Vanadium phosphonates were first used as anodes in lithium batteries by Zhang and coworkers [23] . Since then, many papers have been published on various issues related to the use of VPO 4 as an electroactive material in lithium, [24–34] sodium [31–35] and potassium ion batteries [32,36] . During the battery discharging process, alkali metal ions are incorporated into the anodic material by the electrochemical conversion reaction described by the following equation: …”

“…where M = Li, Na and K. VPO 4 has been synthesized through numerous methods, such as sol-gel, [23,24,35] freeze-drying assisted annealing [25] and hydrothermal methods. [26][27][28][29][30][31][32][33][34][35][36] Vanadium is highly chemically active, and its oxidation levels assume a value from 0 to + 5. VPO 4 has an orthorhombic structure composed of VO 6 octahedrons and PO 4 tetrahedrons.…”