Enze Hu's research while affiliated with Qingdao University of Science and Technology and other places

Aqueous zinc-ion batteries are considered one of the promising large-scale energy storage devices of the future because of their high energy density, simple preparation process, efficient and safe discharge process, abundant zinc reserves, and low cost. However, the development of cathode materials with high capacity and stable structure has become one of the key elements to further development of aqueous zinc-ion batteries. Vanadium-based compounds, as one of the cathode materials for aqueous zinc-ion batteries, have various structures and high reversible capacities. Among them, vanadium-based sulfides have higher academic ability, better electrochemical activity, lower ion diffusion potential barrier, and a faster ion diffusion rate. As a result, vanadium-based sulfides have received extensive attention and research. In this review, we summarize the recent progress of vanadium-based sulfides applied in aqueous zinc-ion batteries, highlighting their effective strategies for designing optimized electrochemical performance and the underlying electrochemical mechanisms. Finally, an overview is provided of current vanadium-based sulfides and their prospects, and other perspectives on vanadium-based sulfide cathode materials for aqueous zinc-ion batteries are also discussed.

Rechargeable aqueous zinc-ion batteries (ZIBs) are an attractive alternative for flexible energy storage devices due to their excellent safety and low cost. One of the main challenges that plagues their practical applications is the restricted variety of cathode materials with fast reaction kinetics and good mechanical properties. Herein, we prepared rose-like VS2 nanosheets which have decent specific capacities, metallic conductivity, and open-enough channels and further incorporated them into a single-walled carbon nanotube (SWCNT) network, achieving a C-V chemical-bonded freestanding VS2@SWCNT (C-VS2) composite. Such chemical bonding in the composites builds a bridge for rapid electron transfer and ion diffusion in the longitudinal direction from one layer to another layer. As a result, the reversible Zn/C-VS2 system in core cells exhibits a high specific capacity (205.3 mA h g-1 at 0.1 A g-1), an excellent cyclic stability (115.4 mA h g-1 was obtained after 1500 cycles at 5 A g-1), and a remarkable rate capability (135.4 mA h g-1 at 10 A g-1). Furthermore, the freestanding C-VS2 films with good flexibility and conductivity can serve as a flexible cathode to assemble soft-packaged ZIBs. Meanwhile, the soft-packaged ZIB has good electrochemical stability even under different bending conditions (the discharge capacity dropped by only 2.1 mA h g-1 after bending). This work offers insights into the rational design of zinc-ion hosts throughout chemical bond engineering.

As an emerging member of the two-dimensional (2D) material family, V2CTX MXene shows great potential in the application of lithium-ion capacitors (LICs) due to its unique structure and excellent electrical conductivity. However, severe nanosheets stacking and intra-layer transport barriers have limited the further development of V2CTX MXene-based materials. Herein, we prepared K⁺ ions and -O functional group co-modified V2CTX MXene (VCT-K) and further incorporated it with single-walled carbon nanotube (SWCNT), obtaining freestanding V2CTX composite films ([email protected]) with the 3D conductive network. Significantly, K⁺ ions were introduced into V2CTX MXene to stabilize the interlayer structure and prevent the aggregation of nanosheets, the terminal group of -O was controllably modified on the surface of MXene to improve the Li⁺ ions storage reversible capacities and the SWCNT acted as the bridge between MXene nanosheets to opens up the channels for ion/electron transportation in the longitudinal direction. Benefited from the synergistic effect of VCT-K and SWCNT, the [email protected] exhibits superior reversible specific capacities of 671.8 mAh g⁻¹ at 0.1 A g⁻¹ and 318 mAh g⁻¹ at 1.0 A g⁻¹. Furthermore, the assembled LICs with [email protected] anode coupling activated carbon (AC) cathode deliver an outstanding power density of 19.0 kW kg⁻¹ at 67.4 Wh kg⁻¹, a high energy density of 140.5 Wh kg⁻¹ at 94.8 W kg⁻¹ and a stable capacitance retention of 86% after 6000 cycles at 10 A g⁻¹. Such unique structures and excellent electrochemical properties are expected to pave the way for the large-scale application in LICs of MXene-based materials.