Three-dimensional hollow CoS2 nanoframes fabricated by anion replacement and their enhanced pseudocapacitive performances

Achieving High Performance Electrode for Energy Storage with Advanced Prussian Blue-Drived Nanocomposites-A Review

Recently, Prussian blue analogues (PBAs)-based anode materials (oxides, sulfides, selenides, phosphides, borides, and carbides) have been extensively investigated in the field of energy conversion and storage. This is due to PBAs' unique properties, including high theoretical specific capacity, environmental friendly, and low cost. We thoroughly discussed the formation of PBAs in conjunction with other materials. The performance of composite materials improves the electrochemical performance of its energy storage materials. Furthermore, new insights are provided for the manufacture of low-cost, high-capacity, and long-life battery materials in order to solve the difficulties in different electrode materials, combined with advanced manufacturing technology and principles. Finally, PBAs and their composites' future challenges and opportunities are discussed.

Sea urchin-like CoNi2S4materials derived from nickel hexamyanocobaltate for high-performance asymmetric hybrid supercapacitor

In this work, a mild chemical precipitation method and simple hydrothermal treatment of the nickel hexamyanocobaltate precursor strategy are developed to prepare a sea urchin-like CoNi₂S₄compound with remarkable specific capacity and excellent cycling stability. The prepared CoNi₂S₄has an outstanding specific capacity of 149.1 mA h g^-1at 1 A g^-1and an initial capacity of 83.1% after 3000 cycles at 10 A g^-1. Moreover, the porous carbon nanospheres (PCNs) with exhibit cycling stability (94.7% of initial specific capacity after 10 000 cycles at 10 A g^-1) are selected as negative electrode to match CoNi₂S₄positive electrode for assembly of CoNi₂S₄//PCNs asymmetric supercapacitor (ASC). Satisfactorily, the as-assembled CoNi₂S₄//PCNs ASC exhibits an impressive energy density of 41.6 Wh kg^-1at 797 W kg^-1, as well as the suitable capacity retention of 82.8% after 10 000 cycles. The superior properties of the device demonstrated that the as-prepared material is potential energy storage material.

Potential transition and post-transition metal sulfides as efficient electrodes for energy storage applications: review

Electrochemical energy storage has attracted much attention due to the common recognition of sustainable energy development. Transition metal sulfides and post-transition metal sulfides have been intensively been focused on due to their potential as electrode materials for energy storage applications in different types of capacitors such as supercapacitors and pseudocapacitors, which have high power density and long cycle life. Herein, the physicochemical properties of transition and post-transition metal sulfides, their typical synthesis, structural characterization, and electrochemical energy storage applications are reviewed. Various perspectives on the design and fabrication of transition and post-transition metal sulfides-based electrode materials having capacitive applications are discussed. This review further discusses various strategies to develop transition and/or post-transition metal sulfide heterostructured electrode-based self-powered photocapacitors with high energy storage efficiencies.

Electrochemical energy storage has attracted much attention due to the common recognition of sustainable energy development.

Free-Standing rGO-CNT Nanocomposites with Excellent Rate Capability and Cycling Stability for Na2SO4 Aqueous Electrolyte Supercapacitors

Facing the increasing demand for various renewable energy storage devices and wearable and portable energy storage systems, the research on electrode materials with low costs and high energy densities has attracted great attention. Herein, free-standing rGO-CNT nanocomposites have been successfully synthesized by a facile hydrothermal method, in which the hierarchical porous network nanostructure is synergistically assembled by rGO nanosheets and CNT with interlaced network distribution. The rGO-CNT composite electrodes with synergistic enhancement of rGO and CNT exhibit high specific capacitance, excellent rate capability, exceptional conductivity and outstanding long-term cycling stability, especially for the optimal rGO-CNT₃₀ electrode. Applied to a symmetric supercapacitor systems (SSS) assembled with an rGO-CNT₃₀ electrode and with 1 M Na₂SO₄ aqueous solution as the electrolyte, the SSS possesses a high energy density of 12.29 W h kg⁻¹ and an outstanding cycling stability, with 91.42% of initial specific capacitance after 18,000 cycles. Results from these electrochemical properties suggest that the rGO-CNT₃₀ nanocomposite electrode is a promising candidate for the development of flexible and lightweight high-performance supercapacitors.

Advanced materials and technologies for supercapacitors used in energy conversion and storage: a review

Supercapacitors are increasingly used for energy conversion and storage systems in sustainable nanotechnologies. Graphite is a conventional electrode utilized in Li-ion-based batteries, yet its specific capacitance of 372 mA h g−1 is not adequate for supercapacitor applications. Interest in supercapacitors is due to their high-energy capacity, storage for a shorter period and longer lifetime. This review compares the following materials used to fabricate supercapacitors: spinel ferrites, e.g., MFe2O4, MMoO4 and MCo2O4 where M denotes a transition metal ion; perovskite oxides; transition metals sulfides; carbon materials; and conducting polymers. The application window of perovskite can be controlled by cations in sublattice sites. Cations increase the specific capacitance because cations possess large orbital valence electrons which grow the oxygen vacancies. Electrodes made of transition metal sulfides, e.g., ZnCo2S4, display a high specific capacitance of 1269 F g−1, which is four times higher than those of transition metals oxides, e.g., Zn–Co ferrite, of 296 F g−1. This is explained by the low charge-transfer resistance and the high ion diffusion rate of transition metals sulfides. Composites made of magnetic oxides or transition metal sulfides with conducting polymers or carbon materials have the highest capacitance activity and cyclic stability. This is attributed to oxygen and sulfur active sites which foster electrolyte penetration during cycling, and, in turn, create new active sites.

Hollow Structures Based on Prussian Blue and Its Analogs for Electrochemical Energy Storage and Conversion

Due to their special structural characteristics, hollow structures grant fascinating physicochemical properties and widespread applications, especially in electrochemical energy storage and conversion. Recently, the research of Prussian blue (PB) and its analog (PBA) related nanomaterials has emerged and has drawn considerable attention because of their low cost, facile preparation, intrinsic open framework, and tunable composition. Here, the recent progress in the study of PB- and PBA-based hollow structures for electrochemical energy storage and conversion are summarized and discussed. First, some remarkable examples in the synthesis of hollow structures from PB- and PBA-based materials are illustrated in terms of the structural architectures, i.e., closed single-shelled hollow structures, open hollow structures, and complex hollow structures. Thereafter, their applications as potential electrode materials for lithium-/sodium-ion batteries, hybrid supercapacitors, and electrocatalysis are demonstrated. Finally, the current achievements in this field together with the limits and urgent challenges are summarized. Some perspectives on the potential solutions and possible future trends are also provided.

Multi-layer-stacked Co9S8 micro/nanostructure directly anchoring on carbon cloth as a flexible electrode in supercapacitors

Rational design and synthesis of electrode materials containing uniformly stacked lamella structures with high surface areas are attractive for efficient storage of electrochemical energy. In this work, Co9S8 clusters with a uniformly stacked lamella structure was directly anchored onto carbon cloth (CC) by an easy-to-implement chemical solution processing method, which involves the homogeneous growth of the CoCO3 precursor, promoting the formation of nanosheets during the subsequent sulfurization process. Due to the conductive substrate (CC) and special multi-layer micro/nanostructure (Co9S8), the flexible Co9S8/CC electrode, which can be tailored, bent and twisted arbitrarily without affecting its electrochemical properties, also exhibits excellent electrochemical properties with a high specific capacitance (1475.4 F g-1 at 1 A g-1), a good rate capacity (80.2% retention at 20 A g-1) and excellent cycling stability (92.9% retention over 5000 cycles). In addition, the assembled solid-state asymmetric supercapacitor device containing the fabricated Co9S8 as the positive electrode and activated carbon as the negative electrode, also exhibits a high energy density of 20.3 W h kg-1 at a power density of 22 796.1 W kg-1 and a high energy density of 33.2 W h kg-1 at a power density of 817.9 W kg-1. Because of its good electrochemical properties and flexibility, the flexible Co9S8/CC electrode material is very promising to be used in flexible supercapacitors and wearable electronic technology.

Mesoporous nickel cobalt manganese sulfide yolk–shell hollow spheres for high-performance electrochemical energy storage

Mesoporous Ni–Co–Mn sulfide yolk–shell hollow spheres have been prepared via a self-template route and show excellent electrochemical performance in supercapacitors.

Bifunctional iron disulfide nanoellipsoids for high energy density supercapacitor and electrocatalytic oxygen evolution applications

FeS₂, prepared using a rapid microwave assisted method, exhibits excellent electrochemical performance for supercapacitor and OER applications.

Recent Advances in Metal Chalcogenides (MX; X = S, Se) Nanostructures for Electrochemical Supercapacitor Applications: A Brief Review

Supercapacitors (SCs) have received a great deal of attention and play an important role for future self-powered devices, mainly owing to their higher power density. Among all types of electrical energy storage devices, electrochemical supercapacitors are considered to be the most promising because of their superior performance characteristics, including short charging time, high power density, safety, easy fabrication procedures, and long operational life. An SC consists of two foremost components, namely electrode materials, and electrolyte. The selection of appropriate electrode materials with rational nanostructured designs has resulted in improved electrochemical properties for high performance and has reduced the cost of SCs. In this review, we mainly spotlight the non-metallic oxide, especially metal chalcogenides (MX; X = S, Se) based nanostructured electrode materials for electrochemical SCs. Different non-metallic oxide materials are highlighted in various categories, such as transition metal sulfides and selenides materials. Finally, the designing strategy and future improvements on metal chalcogenide materials for the application of electrochemical SCs are also discussed.