Sandwich Structure of 3D Porous Carbon and Water‐Pillared V₂O₅ Nanosheets for Superior Zinc‐Ion Storage Properties

Abstract

Vanadium oxides are promising cathode materials for rechargeable aqueous zinc-ion batteries (RAZIBs). However, the selfagglomeration and poor ion/electron conductivity of vanadium oxides in the charge/discharge process usually lead to low capacity and capacity attenuation, which limits their commercial application. Herein, we report a facile and mass-production method for fabricating 3D porous carbon/water-pillared V 2 O 5 nanosheet composites with sandwich structure (PC/V 2 O 5 • nH 2 O), which can further reduce the preparation cost of vanadiumoxide-based cathodes. Moreover, the excellent structural characteristics of PC/V 2 O 5 • nH 2 O not only effectively inhibits the aggregation and stacking of V 2 O 5 • nH 2 O but also increases the contact area between the active substance and the electrolyte, which is conducive to the transport of zinc ions and improves the electrochemical performance of RAZIBs. The PC/V 2 O 5 • nH 2 O cathode displays an excellent rate performance (325.3 mAh g À 1 at high current density 20 A g À 1 ), a high specific discharge capacity of 415.4 mAh g À 1 at 0.5 A g À 1 , an outstanding cyclic stability, and capacity retention (after 1000 cycles the capacity retention rate about 97.1 %). Ex situ XRD patterns reveal that the charge/discharge process of the PC/V 2 O 5 • nH 2 O electrode undergoes a reversible intercalation and conversion process. The method used in this work provides an idea for large-scale synthesis of vanadium-based cathode materials for multivalent batteries.

Ultrastable hydrated vanadium dioxide cathodes for high-performance aqueous zinc ion batteries with H+/Zn2+ Co-insertion mechanism

“…† During the rst cycle of charge and discharge, VO 2 $xH 2 O (10 −10.8 -10 −10.3 cm 2 s −1 ) exhibits a higher Zn 2+ diffusion coefficient than (NH 4 ) 2 V 10 O 25 $8H 2 O (10 −11.7 -10 −10.8 cm 2 s −1 ), which further explains why VO 2 $xH 2 O has better zinc storage performance. [39][40][41] In addition, the high diffusion coef-cient suggests that the electrostatic interaction between Zn 2+ and the host material is weak. To gain a better understanding of the kinetic behavior, the in situ EIS tests of the VO 2 $xH 2 O electrode were performed during the rst discharge-charge cycle (Fig.…”

Recent Developments and Challenges of Vanadium Oxides (VxOy) Cathodes for Aqueous Zinc‐Ion Batteries

“…91.1 %/4000/5 A g À 1 16 [70] C@V 2 O 71 %/2000/0.5 A g À 1 17 [71] V 2 O 5 /GO 90.8 %/10000/20 A g À 1 18 [72] PC/V 97.1 %/1000/5 A g À 1 19 [73] Cu ), (50°C) 88 %/10000/10 A g À 1 20 [74] La 3…”

“…Additionally, the cell volume expansion problem also occurs, which strongly affects the cycling stability of the system. Recently, this problem was effectively solved by constructing cathodes with porous morphology [73] . More active sites for the reaction of Zn 2+ were supplied, and numerous by‐product precipitates can be accommodated, which will reduce the adverse effects of these substances on the electrochemical process to a certain extent [121] .…”

“…In addition, the progressive increase of capacitive contribution in the V 2 O 5 /GOÀ Zn battery led to a large amount of Zn 2 + stored on the surface of V 2 O 5 /GO and less lattice collapse, which promoted the rapid transfer of Zn 2 + and structural stability in line with the high performance and extremely fast capacity (Figure 5f). Very recently, a 3D porous carbon/water-pillared V 2 O 5 nanosheets sandwich structure composite (PC/V 2 O 5 • nH 2 O) was introduced by Li et al [73] The preparation method broke the limitations of the high preparation cost of conventional vanadium-oxygen cathodes. The PC/V 2 O 5 • nH 2 O cathode displayed outstanding electrochemical performance (high specific discharge capacity of 415.4 mAh g À 1 at 0.5 A g À 1 and still possessed a stable discharge capacity of 325.3 mAh g À 1 even at 20 A g À 1 ).…”

“…Recently, this problem was effectively solved by constructing cathodes with porous morphology. [73] More active sites for the reaction of Zn 2 + were supplied, and numerous by-product precipitates can be accommodated, which will reduce the adverse effects of these substances on the electrochemical process to a certain extent. [121] There are few studies related to the effect of byproducts on aqueous ZIBs systems, but the irreversible formation of by-products may influence the electrochemical behavior of the cell to a greater or lesser extent.…”