【Research Background】

    With the increasing demand for electric vehicles and large-scale energy storage, it is urgently needed to bring long-cycle reliability, low-cost and high-security energy storage systems. The rechargeable water-based zinc ion battery is due to its high theoretical capacity (820 mAh g ^-1 ), abundant reserves in nature, low oxidation potential of Zn / Zn ⁺ (-0.76 vs. standard hydrogen electrode), non-flammable and The environmentally friendly aqueous electrolyte and simple manufacturing process have become one of the most promising alternatives. However, despite its many advantages, the divalent zinc ion has a strong Coulomb interaction, making it difficult to embed and embed in the cathode material. Exploring suitable anode materials for zinc-ion batteries with long cycle life and high capacity is the key to achieving high energy density batteries, and actually has a long way to go. V-based oxides, especially anhydrous vanadium pentoxide, have abundant defects and oxidizing ability of different valence states from V ²⁺ to V ⁵⁺ , and have a wide range of applications in different rechargeable metal ion batteries Prospects, such as Li ⁺ , Na ⁺ , Zn ²⁺ , Ca ²⁺  and Al ³⁺ batteries. However, V 2 O . 5 has not been actually applied to the rechargeable battery, mainly due to. 1) V 2 O . 5 intrinsic low electron conductivity; 2) metal ions V 2 O . 5It is very difficult to embed and diffuse in 3) The structural phase change during charging and discharging leads to irreversible structural change due to its lattice strain, which ultimately causes capacity loss and short cycle life. 2D MXene material is considered to be the most potential substitute for catalytic and energy storage applications due to its unique structure, electronic properties and chemical composition. V 2 CT x  MXene is considered to be a potential pseudo-capacitor material, thanks to the multi-oxidation valence state of vanadium which can bring high charge storage capacity.

【Achievement Introduction】

 Recently, Professor Feng Jinkui of Shandong University published a research paper titled:  Micron-Sized Nanoporous Vanadium Pentoxide Arrays for High Performance Gel Zinc-Ion Batteries and Potassium Batteries in the internationally renowned academic journal Chemistry of Materials . The thesis introduces a one-step annealing process using V 2 CT x as a precursor to obtain a micro-scale nanoporous V 2 O 5 array with controllable morphology , and explores the annealing conditions on the degree of crystallinity, microstructure and electrochemical performance. influences.  

【Graphic introduction】

Figure 1.  Schematic diagram of the synthesis process  of V 2 O 5 derived from V 2 CT x MXene at different annealing temperatures and heating rates.

Figure 2.  Physical characterization of V 2 O 5 derived from V 2 CT x MXene under different conditions: XRD, Raman and XPS.

Figure 3.  Microscopic characterization  of V 2 O 5 derived from V 2 CT x MXene : SEM, TEM and mapping distribution.

Figure 4.   Application of V 2 O 5 derived from V 2 CT x MXene in quasi-solid zinc ion batteries: electrochemical performance test.

Figure 5.  Kinetic analysis of V 2 O 5 derived from V 2 CT x MXene .

FIG. 6. The  V 2 CT X MXene derived V 2 O . 5 Electrochemical Properties of potassium ion battery applications.

【Summary of this article】

This paper designs and synthesizes a micro-sized nanoporous V 2 O 5 array generated by V 2 CT x through one-step annealing treatment for quasi-solid zinc ion batteries and potassium ion batteries. The crystallinity, morphology and electrochemical properties of V 2 O 5 under the influence of different temperatures and heating rate were systematically studied. This reasonably designed V 2 O 5 has a unique 2D structure, porous design and pseudo-capacitance effect, which ensures the embeddability of ions, outstanding structural stability and fast electron transmission. As a positive electrode material for zinc ion batteries, with self-healing quasi-solid PVA-Zn (CF 3 SO 3 ) 2 hydrogel electrolyte, the micro-sized accordion-shaped V 2 O 5 has a current density of 358.7 at 200 mA g ^-1 The reversible capacity of mAh g ^-1 still has a reversible capacity of 279 mAh g ^-1 after 3500 cycles . In addition, this optimized micro-sized accordion-shaped V 2 O 5 cathode material also has high electrochemical performance when applied to potassium ion batteries. 

Literature link:

https://dx.doi.org/10.1021/acs.chemmater.0c00787

Source: MXene Frontier

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