Aqueous zinc (Zn)-ion batteries (AZIBs) have gained significant interest in energy storage due to several unique advantages. Utilizing water-based electrolytes enhances environmental sustainability, while the abundance and affordability of Zn offer economic benefits. Manganese (Mn)-based materials, commonly used as cathodes in these batteries, provide high theoretical capacity, high electrical conductivity, and good structural stability. However, these materials suffer from capacity degradation over repeated cycles due to structural collapse and limited conductivity. To address this problem, we synthesized a magnesium (Mg)- and Mn-based composite, Mg²⁺-Mn₃O₄, using the hydrothermal method with an optimized amount of ammonium hydroxide (NH₄OH) solution. This approach effectively stabilizes the structure during cycling, enhancing both capacity retention and conductivity. The Zn²⁺/H⁺ intercalation/deintercalation process was confirmed by experimental results and ex-situ X-ray diffraction analysis, which demonstrates that Mg²⁺, along with optimized NH₄OH amount, prevents structural collapse and improves conductivity. Under optimal process conditions, the composite electrode (Mg²⁺-Mn₃O₄–8 ml) achieved a capacity of 173.58 mA h g^–1 at 0.5 A g^–1, with excellent rate performance of 71.39 mA h g^–1 at 10 A g^–1. Remarkably, even at 5 A g^–1, the electrode maintained a capacity of 86.87 mA h g^–1 over 2100 cycles, underscoring the role of Mg²⁺ and NH₄OH in enhancing the reversible insertion/extraction stability of Zn²⁺ in Mn-based layered materials. This study presents a novel strategy for metal-ion incorporation in Mn-based AZIBs, offering insights into the optimization of cathode materials and advancing research on associated storage mechanisms.

High-performance aqueous zinc (Zn)-ion batteries (AZIBs) have emerged as one of the greatest favorable candidates for next-generation energy storage systems because of their low cost, sustainability, high safety, and eco-friendliness. In this report, we prepared magnesium vanadate (MgVO)-based nanostructures by a facile single-step solvothermal method with varying experimental reaction times (1, 3, and 6 h) and investigated the effect of the reaction time on the morphology and layered structure for MgVO-based compounds. The newly prepared MgVO-1 h, MgVO-3 h and MgVO-6 h samples were used as cathode materials for AZIBs. Compared to the MgVO-1 h and MgVO-6 h cathodes, the MgVO-3 h cathode showed a higher specific capacity of 492.74 mA h g^-1 at 1 A g^-1 over 500 cycles and excellent rate behavior (291.58 mA h g^-1 at 3.75 A g^-1) with high cycling stability (116%) over 2000 cycles at 5 A g^-1. Moreover, the MgVO-3 h electrode exhibited good electrochemical performance owing to its fast Zn-ion diffusion kinetics. Additionally, various ex-situ analyses confirmed that the MgVO-3 h cathode displayed excellent insertion/extraction of Zn²⁺ ions during charge and discharge processes. This study offers an efficient method for the synthesis of nanostructured MgVO-based cathode materials for high-performance AZIBs.

Aqueous zinc (Zn)-ion batteries (AZIBs) have the potential to be used in massive energy storage owing to their low cost, eco-friendliness, safety, and good energy density. Significant research has been focused on enhancing the performance of AZIBs, but challenges persist. Vanadium-based oxides, known for their large interlayer spacing, are promising cathode materials. In this report, we synthesize Mg²⁺-intercalated potassium vanadate (KVO) (MgKVO) via a single-step hydrothermal method and achieve a 12.2 Å interlayer spacing. Mg²⁺ intercalation enhances the KVO performance, providing wide channels for Zn²⁺, which results in high capacity and ion diffusion. The combined action of K⁺ and Mg²⁺ intercalation enhances the electrical conductivity of MgKVO. This structural design endows MgKVO with excellent electrochemical performance. The AZIB with the MgKVO cathode delivers a high capacity of 457 mAh g^-1 at 0.5 A g^-1, excellent rate performance of 298 mAh g^-1 at 5 A g^-1, and outstanding cycling stability of 102% over 1300 cycles at 3 A g^-1. Additionally, pseudocapacitance analysis reveals the high capacitance contribution and Zn²⁺ diffusion coefficient of MgKVO. Notably, ex-situ X-ray diffraction, X-ray photoelectron spectroscopy, and Raman analyses further demonstrate the Zn²⁺ insertion/extraction and Zn-ion storage mechanisms that occurred during cycling in the battery system. This study provides new insights into the intercalation of dual cations in vanadium oxides and offers new solutions for designing cathodes for high-capacity AZIBs.

Together with the development of high-performance advanced electronics, flexible supercapacitors (SCs) with tailored nanostructures have great attraction. Electrochemically deposited nanosheet arrays of nickel magnesium selenide (Ni_xMg_3-xSe₄, NMgS) with high capacitance provide high potentials as a positive electrode in flexible SCs. To further enhance their electrochemical properties and long-term cycling stability, a promising strategy of surface engineering with conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) is proposed. The present work proposes the construction of PEDOT shielded NMgS (P@NMgS-2) on a flexible carbon cloth substrate via a hierarchical electrodeposition technique. Benefitting from the synergistic effect, the P@NMgS-2 exhibits an excellent areal capacitance value of 1440 mF cm⁻² at 4 mA cm⁻². A novel shape-adaptable polymer gel electrolyte-assisted flexible quasi-solid-state hybrid SC (FQHSC) device constructed with P@NMgS-2 as a positive electrode and activated carbon as a negative electrode demonstrates the maximum power and energy density values of 14.13 mW cm⁻² and 0.18 mWh cm⁻², respectively, followed by outstanding cycling stability (~100% capacitance retention over 50,000 cycles). Furthermore, the FQHSC device successfully powered electronic devices with no serious degradation upon bending and twisting for wearable electronic applications.

Novel rare-earth (RE; e.g., europium (Eu³⁺), samarium (Sm³⁺), and praseodymium (Pr³⁺)) and transition metal (TM⁴⁺; e.g., manganese (Mn⁴⁺)) ion single-/co-doped double-perovskite Ca₂InTaO₆ (CITO) phosphors were prepared and investigated with respect to their crystal structure and photoluminescence (PL) properties. Among them, the CITO:Eu³⁺ phosphors were found to exhibit an ultra-high internal PL quantum yield (89.1%) and good thermal stability (78.7% at 423 K relative to the initial value at 303 K). As such, the corresponding packaged white light-emitting diode (LED) was able to display a remarkable color rendering index (CRI; = 91.51@10 mA). Besides, the potential in applications of anti-counterfeiting fields and a novel LED structure based on flexible phosphor-converted films was also studied. Moreover, due to their different thermal quenching, trivalent lanthanide (Ln³⁺)/Mn⁴⁺ co-doped CITO phosphors were designed for optical thermometry based on the luminescence intensity ratio (LIR) between different 4f transitions of various Ln³⁺ ions and ²E_g → ⁴A_2g (Mn⁴⁺) transition. Particularly, the LIR between the ⁴G_5/2 → ⁶H_9/2 and ²E_g → ⁴A_2g peaks of the CITO activated with 5 mol% Sm³⁺ and 0.3 mol% Mn⁴⁺ exhibited the most excellent relative sensitivity (S_r; = 3.80 %·K⁻¹) with beneficial temperature uncertainty of 0.0648 K. Overall, these results are of significance to offer valuable databases for constructing multifunctional high-performance optical platforms using single-/co-doped double-perovskite tantalates.

Currently, bimetallic selenates have attracted much attention as a prominent electrode composite material for supercapacitors owing to their higher redox chemistry and superior electrical conductivity. Herein, we synthesized cobalt-magnesium selenates (CoSeO₃−MgSeO₄, CMS) via a facile hydrothermal process, followed by selenization. At first, cobalt-magnesium oxide (Co_2.32Mg_0.68O₄, CMO) was in situ prepared by a one-pot hydrothermal method. An investigation on the morphological change was performed by synthesizing the same CMO samples at different growth times by keeping the temperature constant. The CMO electrode designed for 8 h of growth time (CMO-8 h) with an attractive morphology showed a higher areal capacity of 101.7 µAh cm⁻² (at 3 mA cm⁻²) than the other CMO electrodes prepared for 6 and 10 h. Further exalted performance was achieved by the selenization of the CMO-8 h sample to form the CMS material. At 3 mA cm⁻², the resulted CMS exhibited nearly three times higher capacity, i.e., 385.4 µAh cm⁻², than the CMO-8 h electrode. Additionally, an asymmetric cell fabricated with CMS as a positive electrode also revealed good energy storage performance. Within the applied voltage between 0 and 1.5 V, the asymmetric cell demonstrated maximum energy density of 0.159 mWh cm⁻² (18.6 Wh kg⁻¹) and maximum power density of 18.47 mW cm⁻² (1938 W kg⁻¹), respectively. Thus, novel magnesium-based metal selenates can act as an efficient electrode for energy storage.

Transition metal oxide/hydroxide with multifunctional hierarchical nanostructures has attracted widespread attention in supercapacitors (SCs) because of their large accessible surface area, high electrochemical activity and superior redox chemistry. Herein, core-shell-like copper (Cu) hydroxide nanotube arrays grafted nickel aluminum layered double hydroxide nanosheets were facilely synthesized on porous Cu foam (CH NTAs@NiAl LDH NSs) for use as an efficient battery-type electrode in hybrid SCs. With the synergistic effects of NiAl LDH NSs on well-adhered CH NTAs/CF, the core-shell-like composite (prepared for 24 h) delivered a maximum areal capacity of 334.3 µAh/cm² at a current density of 3 mA/cm² in 2 M KOH electrolyte, which is comparatively higher than other samples synthesized at different growth times. Moreover, the core-shell-like CH NTAs@NiAl LDH NSs-24 demonstrated an outstanding cycling stability of 134.3% after 10, 000 cycles. Utilizing high capacity and stability of CH NTAs@NiAl LDH NSs-24, a pouch-type hybrid SC was further assembled with core-shell-like composite as a positive electrode and reduced graphene oxide as a negative electrode with a filter paper as a separator in aqueous alkaline electrolyte. The hybrid SC showed a high areal capacity of 250 µAh/cm² at 2 mA/cm² with maximum areal energy and power densities of 181.9 µWh/cm² and 24, 991.5 µW/cm², respectively. Successfully harvesting the solar energy via solar cell panel and subsequently delivering the stored energy to switching and proximity applications also demonstrated the real-time applicability of our hybrid SCs.

We report triboelectric nanogenerators (TENGs) composed of a flexible and cost-effective gold-coated conductive textile (CT) to convert wind energy into electricity. The Au-coated CT is employed because of its high surface roughness resulting from Au nanodots distributed on microsized fibers. Thus, the Au-coated CT with nano/microarchitecture plays an important role in enhancing the effective contact area as well as the output performance of the TENG. Moreover, the surface roughness of the Au-coated CT is controlled by adjusting the Au thermal deposition time or tailoring the diameter of the Au nanodots. At an applied wind speed of 10 m·s^–1, a wind-based TENG (W-TENG) with dimensions of 75 mm × 12 mm × 25 mm produces an open-circuit voltage (V_OC) of ~39 V and a short-circuit current (I_SC) of ~3 μA by using the airflow-induced vibrations of an optimized Au-coated CT between two flat polydimethylsiloxane (PDMS) layers. To further specify the device performance, the electric output of the W-TENG is analyzed by varying several parameters such as the distance between the PDMS layer and Au-coated CT, applied wind speed, external load resistance, and surface roughness of the PDMS layers. Introducing an inverse micropyramid architecture on the PDMS layers further improves the output performance of the W-TENG, which exhibits the highest V_OC (~49 V) and I_SC (~5 μA) values at an applied wind speed of 6.8 m·s^-1. Additionally, the reliability of the W-TENG is also tested by measuring its output current during long-term cyclic operation. Furthermore, the rectified output signals observed by the W-TENG device are used as a direct power source to light 45 green commercial light-emitting diodes connected in series and also to charge capacitors (100 and 4.7 μF). Finally, the output performance of the W-TENG device in an actual windy situation is also investigated.

Hierarchical core–shell-like MnO₂ nanostructures (NSs) were used to anchor MnO₂ hexagonal nanoplate arrays (HNPAs) on carbon cloth (CC) fibers. The NSs were prepared by a novel one-step electrochemical deposition method. Under an external cathodic voltage of -2.0 V for 30 min, hierarchical core–shell-like MnO₂-NS-decorated MnO₂ HNPAs (MnO₂ NSs@MnO₂ HNPAs) were uniformly grown on CC with reliable adhesion. The phase purity and morphological properties of the samples were characterized by various physicochemical techniques. At a constant external cathodic voltage, growth of MnO₂ NSs@MnO₂ HNPAs on CC was carried for different time periods. When utilized as a flexible, robust, and binder-free electrode for pseudocapacitors, the hierarchical core–shell-like MnO₂ NSs@MnO₂ HNPAs on CC showed clearly enhanced electrochemical properties in 1 M Na₂SO₄ electrolyte solution. The results indicate that the MnO₂ NSs@MnO₂ HNPAs on CC have a maximum specific capacitance of 244.54 F/g at a current density of 0.5 A/g with excellent cycling stability compared to that of bare MnO₂ HNPAs on CC (112.1 F/g at 0.5 A/g current density). We believe that the superior charge storage performance of the pseudocapacitive electrode can be mainly attributed to the hierarchical MnO₂ NSs@MnO₂ HNPAs building blocks that have a large specific surface area, offering additional electroactive sites for efficient electrochemical reactions. The facile and single-step approach to growth of hierarchical pseudocapacitive materials on textile based electrodes opens up the possibility for the fabrication of high-performance flexible energy storage devices.

Amorphous nickel tungsten tetraoxide (NiWO₄) nanostructures (NSs) were successfully synthesized on a flexible conductive fabric (CF) using a facile onestep electrochemical deposition (ED) method. With an applied external cathodic voltage (–1.8 V for 15 min), the amorphous NiWO₄ NSs with burl-like morphologies adhered well on the seed-coated CF substrate. The burl-like amorphous NiWO₄ NSs on CF (NiWO₄ NSs/CF) are employed as a flexible and binder-free electrode for pseudocapacitors, which exhibit remarkable electrochemical properties with high specific capacitance (1, 190.2 F/g at 2 A/g), excellent cyclic stability (92% at 10 A/g), and good rate capability (765.7 F/g at 20 A/g) in 1 M KOH electrolyte solution. The superior electrochemical properties can be ascribed to the hierarchical structure and large specific surface area of the burl-like amorphous NiWO₄ NSs/CF. This cost-effective facile method for the synthesis of metal tungsten tetraoxide nanomaterials on a flexible CF could be promising for advanced electronic and energy storage device applications.