Dezhou Zheng

Aqueous Zn-ion hybrid supercapacitors (AZHSCs) combining the advantages of high-energy batteries and high-power supercapacitors see a bright future, but they still suffer from the poor capacity of carbonic cathodes. Herein, a functionalized porous carbon cloth (denoted as FPCC) electrode is demonstrated based on commercial carbon cloth (denoted as CC) tuning by structural and surface engineering. The constructed exfoliated porous carbon layer and the negatively charged functionalized interface not only increase the electrical double layer capacitance but also favor the chemical adsorption of Zn2+ to obtain additional pseudocapacitance. Consequently, the FPCC electrode delivers a high capacity of 0.16 mAh cm−2 at 4 mA cm−2, which is 923.8 times higher than CC, and a long cycle life (85.0% capacity retention after 30 000 cycles). More importantly, the Zn//FPCC AZHSC possesses an impressive energy density (3.3 mWh cm−3) and power density (240 mW cm−3), superior to many advanced batteries and supercapacitors. The quasi-solid-state device is also assembled as a demo. This modification strategy may provide new opportunities for high-performance AZHSCs.

The inferior capacity and cyclic durability of V₂O₅ caused by inadequate active sites and sluggish kinetics are the main problems to encumber the widespread industrial applications of vanadium‐zinc batteries (VZBs). Herein, a cooperative redox chemistry (CRC) as “electron carrier” is proposed to facilitate the electron‐transfer by capturing/providing electrons for the redox of V₂O₅. The increased oxygen vacancies in V₂O₅ provoked in situ by CRC offers numerous Zn²⁺ storage sites and ion‐diffusion paths and reduces the electrostatic interactions between vanadium‐based cathode and intercalated Zn²⁺, which enhance Zn²⁺ storage capability and structural stability. The feasibility of this strategy is fully verified by some CRCs. Noticeably, VZB with [Fe(CN)₆]³⁻/[Fe(CN)₆]⁴⁻ as CRC displays conspicuous specific capacity (433.3 mAh g⁻¹), ≈100% coulombic efficiency and superb cyclability (≈3500 cycles without capacity attenuation). Also, the mechanism and selection criteria of CRC are specifically unraveled in this work, which provides insightful perspectives for the development of high‐efficiency energy‐storage devices.

With the merits of low cost, environmental friendliness and rich resources, manganese dioxide is considered to be a promising cathode material for aqueous zinc-ion batteries (AZIBs). However, its low ion diffusion and structural instability greatly limit its practical application. Hence, we developed an ion pre-intercalation strategy based on a simple water bath method to grow in situ δ-MnO₂ nanosheets on flexible carbon cloth substrate (MnO₂), while pre-intercalated Na⁺ in the interlayer of δ-MnO₂ nanosheets (Na-MnO₂), which effectively enlarges the layer spacing and enhances the conductivity of Na-MnO₂. The prepared Na-MnO₂//Zn battery obtained a fairly high capacity of 251 mAh g⁻¹ at a current density of 2 A g⁻¹, a satisfactory cycle life (62.5% of its initial capacity after 500 cycles) and favorable rate capability (96 mAh g⁻¹ at 8 A g⁻¹). Furthermore, this study revealed that the pre-intercalation engineering of alkaline cations is an effective method to boost the properties of δ-MnO₂ zinc storage and provides new insights into the construction of high energy density flexible electrodes.

Transition metal organic framework materials and their selenides are considered to be one of the most promising cathode materials for nickel-zinc (denoted as Ni-Zn) batteries due to their low cost, environmental friendliness, and controllable microstructure. Yet, their low capacity and poor cycling performance severely restricts their further development. Herein, we developed a simple one-pot hydrothermal process to directly synthesize NiSe₂ (denotes as NiSe₂-X based on the molar amount of SeO₂ added) stacked layered sheets. Benefiting from the peculiar architectures, the fabricated NiSe₂−1//Zn battery based on NiSe₂ and the Zn plate exhibits a high specific capacity of 231.6 mAh g⁻¹ at 1 A g⁻¹, and excellent rate performance (162.8 mAh g⁻¹ at 10 A g⁻¹). In addition, the NiSe₂//Zn battery also presents a satisfactory cycle life at the high current density of 8 A g⁻¹ (almost no decay compared to the initial specific capacity after 1000 cycles). Additionally, the battery device also exhibits a satisfactory energy density of 343.2 Wh kg⁻¹ and a peak power density of 11.7 kW kg⁻¹. This work provides a simple attempt to design a high-performance layered cathode material for aqueous Ni-Zn batteries.