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Supercapacitors (SCs) are attractive as promising energy storage devices because of their distinctive attributes, such as high power density, good current charge/discharge ability, excellent cyclic stability, reasonable safety, and low cost. Electrode materials play key roles in achieving excellent performance of these SCs. Among them, binary transition metal sulfides (BTMSs) have received significant attention, attributed to their high conductivity, abundant active sites, and excellent electrochemical properties. This topic review aims to summarize recent advances in principles, design, and evaluation of the electrochemical performance for nanostructured BTMSs (including nickel–cobalt sulfides, zinc–cobalt sulfides, and copper–cobalt sulfides.) and their nanocomposites (including those carbon nanomaterials, transition metal oxides, binary transition metal oxides, transition metal sulfides, and polymers). Nanostructuring of these BTMSs and nanocomposites as well as their effects on the performance were discussed, including nanoparticles, nanospheres, nanosheets, nanowires, nanorods, nanotubes, nanoarrays, and hierarchitectured nanostructures. Their electrochemical performance has further been reviewed including specific capacitance, conductivity, rate capability, and cycling stability. In addition, the performance of hybrid supercapacitors (HSCs) assembled using the nanostructured BTMSs as the cathodes also have been summarized and compared. Finally, challenges and further prospects in the HSCs-based BTMS electrodes are presented. [ABSTRACT FROM AUTHOR]

Due to their outstanding electrochemical properties, transition metal sulfides and hydroxides are often used as high-performance electrode materials for supercapacitors. The Mn-doped Co(OH) 2 /Ni 3 S 4 electrode material in this study, due to the synergistic reaction mechanism among Co(OH) 2 and Ni 3 S 4 and the increased active sites by the addition of Mn, the Mn-Co(OH) 2 /Ni 3 S 4 exhibits excellent electrochemical property. The electrochemical performance of the Mn-Co(OH) 2 /Ni 3 S 4 hybrid electrode was measured in an electrode cell made of 2 M KOH solution, showing a superior specific capacitance of 1107.0 C g−1 at 0.5 A g−1, in addition to the excellent capacity retention rate at 10 A g−1 is 72.7 % of that at 1 A g−1. The performance of the hybrid supercapacitor (HSC) assembled with Mn-Co(OH) 2 /Ni 3 S 4 compound and activated carbon (AC) was measured under the same electrolyte conditions, anwell-specificific capacity (157.2 F g−1 at 0.5 A g−1) was achieved, along with superior long-term stable charge/discharge capability (88.9 % of the original specific capacity after 35,000 cycles at 8 A g−1). Meanwhile, the most practical application is when the power density of 410.4 W kg−1, the assembled HSC device has an energy storage capacity of 58.8 W h kg−1, revealing that the developed Mn-Co(OH) 2 /Ni 3 S 4 has great application potential for supercapacitors in the future. [Display omitted] • Mn-Co(OH) 2 /Ni 3 S 4 was synthesized via co-precipitation, and hydrothermal processes. • Mn-Co(OH) 2 /Ni 3 S 4 electrode achieves a large specific capacity of 1107 C g−1 at 0.5 A g−1. • The specific capacity maintains 72.7 % when the current density is changed from 1 A g−1 to 10 A g−1. • Mn-Co(OH) 2 /Ni 3 S 4 //AC HSC obtains an energy density of 58.8 Wh kg−1 at a power density of 410.4 W kg−1. • The capacitance of the Mn-Co(OH) 2 /Ni 3 S 4 //AC maintains ∼89.0 % after 35,000 cycles. [ABSTRACT FROM AUTHOR]

• Flower-like Zn doped Ni(OH) 2 @CNTs (ZNC) was in-situ synthesized by a colloidal method at room temperature. • ZNC shows a high specific capacity of 726.5 C g-1 at 1 A g-1 and maintains 72.9% at 10 A g-1. • The energy density of ZNC//AC hybrid supercapacitor (HSC) is 51.3 Wh kg-1 at the power density of 409.6 W kg-1. • After 50,000 cycles, the energy density of ZNC//AC HSC maintains 29.33 Wh kg-1 at 16.5 kW kg-1. • After 50,000 cycles, the capacity of the HSC becomes 115.8% of its initial value. Transition metal oxides and hydroxides are typically applied as electrode materials for supercapacitors, but it is often difficult to achieve both their high power density and energy density simultaneously. Herein, electrodes of flower-like Zn doped Ni(OH) 2 combined with carbon nanotubes (i.e., Zn doped Ni(OH) 2 @CNTs) were in-situ synthesized using a colloidal synthesis method at room-temperature, assisted by cetyltrimethyl ammonium bromide (CTAB) and NaBH 4. This electrode exhibits an excellent electrochemical performance, achieving a high specific capacity of 750.5 C g-1 at 0.5 A g-1 and maintaining 72.9% of its initial value when the current density is increased from 1 A g-1 to 10 A g-1. A hybrid supercapacitor (HSC) assembled using the Zn doped Ni(OH) 2 @CNTs as the positive electrode and an active carbon as the negative electrode exhibits a capacity of 201.7 C g−1 at 1 A g-1 and an energy density of 51.3 Wh kg-1 at a power density of 409.6 W kg-1. After running for 50,000 cycles at a current density of 6 A g-1, the capacity of the HSC becomes 115.8% of its initial value. Moreover, this HSC maintains a high energy density of 29.33 Wh kg-1 at a high power density of 16.5 kW kg-1 after cycling for 50,000 times, which indicates its suitability for energy storage applications. [Display omitted] [ABSTRACT FROM AUTHOR]

The carbon nanoparticles layer coated zinc anode with (1 0 3) crystal plane preferential oriented crystal structure (denoted as C@RZn) is prepared by a facile one-step vapor deposition method, and showed great potentials in extending lifespan and inhibiting dendrite growth. [Display omitted] • The C@RZn was prepared by a facile one-step vapor deposition method. • The C@RZn is combining crystallographic orientation and coating layer. • The C@RZn can guide the deposition of Zn2+ ions and inhibit the dendrite growth. • The C@RZn anode achieves a stable cycle life for more than 3000 h. • The MVO//C@RZn cell keep stable for 5000 cycles. Aqueous zinc ion batteries (ZIBs) have been considered promising energy storage systems due to their excellent electrochemical performance, environmental toxicity, high safety and low cost. However, uncontrolled dendrite growth and side reactions at the zinc anode have seriously hindered the development of ZIBs. Herein, we prepared the carbon nanoparticles layer coated zinc anode with (1 0 3) crystal plane preferential oriented crystal structure (denoted as C@RZn) by a facile one-step vapor deposition method. The preferential crystallographic orientation of (1 0 3) crystal plane promotes zinc deposition at a slight angle, effectively preventing the formation of Zn dendrites on the surface. In addition, the hydrophobic layer of carbon layer used as an inert physical barrier to prevent corrosion reaction and a buffer during volume changes, thus improving the reversibility of the zinc anode. As a result. the C@RZn anode achieves a stable cycle performance of more than 3000 h at 1 mA cm−2 with CE of 99.77 % at 5 mA cm−2. The full battery with C@RZn anode and Mn-doped V 6 O 13 (MVO) cathode show stability for 5000 cycles at the current density of 5 A g−1. This work provides a new approach for the design of multifunctional interfaces for Zn anode. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hybrid materials integrated with Zn 0.76 Co 0.24 S nanoparticles and Co(OH) 2 nanosheets (ZCS@CH) can have a good synergistic effect. • Hierarchically nanostructured hybrid of ZCS@CH was prepared using a simple but effective two-step hydrothermal method. • ZCS@CH electrode achieves a large specific capacity of 1152 C g−1 at 0.5 A g−1. • Hybrid supercapacitor of ZCS@CH//AC obtains an excellent energy density of 62.5 Wh kg−1 at a power density of 425.0 W kg−1. • ZCS@CH//AC shows an excellent long-term stability. It is a great challenge to achieve both high specific capacity and high energy density of supercapacitors by designing and constructing hybrid electrode materials through a simple but effective process. In this paper, we proposed a hierarchically nanostructured hybrid material combining Zn 0.76 Co 0.24 S (ZCS) nanoparticles and Co(OH) 2 (CH) nanosheets using a two-step hydrothermal synthesis strategy. Synergistic effects between ZCS nanoparticles and CH nanosheets result in efficient ion transports during the charge-discharge process, thus achieving a good electrochemical performance of the supercapacitor. The synthesized ZCS@CH hybrid exhibits a high specific capacity of 1152.0 C g-1 at a current density of 0.5 A g-1 in 2 M KOH electrolyte. Its capacity retention rate is maintained at ∼ 70.0% when the current density is changed from 1 A g-1 to 10 A g-1. A hybrid supercapacitor (HSC) assembled from ZCS@CH as the cathode and active carbon (AC) as the anode displays a capacitance of 155.7 F g-1 at 0.5 A g-1, with a remarkable cycling stability of 91.3% after 12,000cycles. Meanwhile, this HSC shows a high energy density of 62.5 Wh kg-1 at a power density of 425.0 W kg-1, proving that the developed ZCS@CH is a promising electrode material for energy storage applications. [ABSTRACT FROM AUTHOR]

Zinc-ion capacitors (ZICs) have garnered significant attention due to their ability to balance energy density and power density. The properties of electrolytes greatly influence the electrochemical performance of ZICs, and the oxidation potential (OP) of electrolytes can be used to determine the most suitable electrolyte for ZICs. However, traditional methods for exploring OP are time-consuming and inefficient, making it difficult to effectively determine the most suitable electrolyte for ZICs. Herein, we propose a machine learning-assisted method that combines deep learning with the traditional machine learning algorithm Gradient Boosting Regression (GBR), which we refer to as DeepGBR. This method can accurately predict the OP of electrolytes even when dealing with complex features and small datasets. Furthermore, with the assistance of deep learning, the accuracy of the predictions improves as the dataset size increases. We further validated the model with four common electrolyte molecules, finding that the predicted results are highly consistent with the theoretical values. The results show that acetonitrile has a high OP, which can achieve high energy density and long-cycle stability when used as an electrolyte solvent for ZICs. This work provides a certain reference for the database modeling strategy of electrolytes for electrochemical energy storage devices. [Display omitted] • Pioneered the application of deep learning for predicting electrolyte OP values. • Model superiority over traditional machine learning became more pronounced. • Consistency observed among experimental, theoretical, and predicted values. • The resulting electrolyte achieves high cycling performance. [ABSTRACT FROM AUTHOR]