Cobalt-doping SnS2 nanosheets towards high-performance anodes for sodium ion batteries

Constructing Three-Dimensional Porous SnS2/RGO as Superior-Rate and Long-Life Anodes for Lithium-Ion Batteries

Tin-based sulfides, possessing a unique layered structure and a high theoretical capacity, stand as highly prospective contenders for anode materials in lithium-ion batteries (LIBs). Nevertheless, the pronounced volume expansion that occurs during lithium storage and poor capacity retention have limited its progress toward commercialization. Herein, we designed and prepared a SnS2/RGO composite with a three-dimensional porous structure by sulfurizing the Sn6O4(OH)4/GO precursor. Through the integration of the structural architecture during the solvent reaction process and the nanomodification during the vulcanization process, the prepared SnS2/RGO composite has a porous structure, and the particle size is optimized at 2-5 nm. This structure is conducive to improving the conductivity of electrode materials, increasing reaction active sites, and enhancing the structural stability of electrode materials. Consequently, the synthesized SnS2/RGO composite is capable of retaining reversible capacities of 975 and 592 mA h g-1 after 250 cycles at 1.0 and 2.0 A g-1, respectively. Moreover, it exhibits a capacity of 349 mA h g-1 after 1100 cycles at 5.0 A g-1. This efficient and convenient preparation method provides guidance for enhancing the lithium storage properties of tin-based sulfides.

NiS2 nanoboxes wrapped in carbon with a core-shell structure for high-performance sodium storage

One-dimensional nitrogen-doped carbon nanotube wrapped NiS2 core-shell nanoboxes have been developed. The hollow interior and protective carbon layer significantly enhance sodium storage properties, showing high reversible capacities and superior cycling stability at high current densities. Density functional theory calculations indicated that the heterostructure remarkably enhances the charge transfer process.

Boosting the Zn2+ storage capacity of MoO3 nanoribbons by modulating the electrons spin states of Mo via Ni doping

Aqueous zinc-ion batteries (AZIBs) have received considerable potential for their affordability and high reliability. Among potential cathodes, α-MoO3 stands out due to its layered structure aligned with the (010) plane, offering extensive ionic insertion channels for enhanced charge storage. However, its limited electrochemical activity and poor Zn2+ transport kinetics present significant challenges for its deployment in energy storage devices. To overcome these limitations, we introduce a new strategy by doping α-MoO3 with Ni (Ni-MoO3), tuning the electron spin states of Mo. Thus modification can activate the reactivity of Ni-MoO3 towards Zn2+ storage and weaken the interaction between Ni-MoO3 and intercalated Zn2+, thereby accelerating the Zn2+ transport and storage. Consequently, the electrochemical properties of Ni-MoO3 significantly surpass those of pure MoO3, demonstrating a specific capacity of 258 mAh g-1 at 1 A g-1 and outstanding rate performance (120 mAh g-1 at 10 A g-1). After 1000 cycles at 8 A g-1, it retains 76 % of the initial capacity, with an energy density of 154.4 Wh kg-1 and a power density of 11.2 kW kg-1. This work proves that the modulation of electron spin states in cathode materials via metal ion doping can effectively boost their capacity and cycling durability.

Engineered Two-Dimensional Transition Metal Dichalcogenides for Energy Conversion and Storage

Designing efficient and cost-effective materials is pivotal to solving the key scientific and technological challenges at the interface of energy, environment, and sustainability for achieving NetZero. Two-dimensional transition metal dichalcogenides (2D TMDs) represent a unique class of materials that have catered to a myriad of energy conversion and storage (ECS) applications. Their uniqueness arises from their ultra-thin nature, high fractions of atoms residing on surfaces, rich chemical compositions featuring diverse metals and chalcogens, and remarkable tunability across multiple length scales. Specifically, the rich electronic/electrical, optical, and thermal properties of 2D TMDs have been widely exploited for electrochemical energy conversion (e.g., electrocatalytic water splitting), and storage (e.g., anodes in alkali ion batteries and supercapacitors), photocatalysis, photovoltaic devices, and thermoelectric applications. Furthermore, their properties and performances can be greatly boosted by judicious structural and chemical tuning through phase, size, composition, defect, dopant, topological, and heterostructure engineering. The challenge, however, is to design and control such engineering levers, optimally and specifically, to maximize performance outcomes for targeted applications. In this review we discuss, highlight, and provide insights on the significant advancements and ongoing research directions in the design and engineering approaches of 2D TMDs for improving their performance and potential in ECS applications.

Solvothermally Synthesized Nickel-Doped Marigold-Like SnS2 Microflowers for High-Performance Supercapacitor Electrode Materials

Two-dimensional transition-metal dichalcogenides (TMDs) have emerged as promising capacitive materials for supercapacitors owing to their layered structure, high specific capacity, and large surface area. Herein, Ni-doped SnS2 microflowers were successfully synthesized via a facile one-step solvothermal approach. The obtained Ni-doped SnS2 microflowers exhibited a high specific capacitances of 459.5 and 77.22 F g-1 at current densities of 2 and 10 A g-1, respectively, in NaClO4 electrolyte, which was found to be higher than that of SnS2-based electrodes in various electrolytes such as KOH, KCl, Na2SO4, NaOH, and NaNO3. Additionally, these microflowers demonstrate a good specific energy density of up to 51.69 Wh kg-1, at a power density of 3204 Wkg-1. Moreover, Ni-doped SnS2 microflowers exhibit a capacity retention of 78.4% even after 5000 cycles. Better electrochemical performance of the prepared electrode may be attributed to some important factors, including the utilization of a highly ionic conductive and less viscous NaClO4 electrolyte, incorporation of Ni as a dopant, and the marigold flower-like morphology of the Ni-doped SnS2. Thus, Ni-doped SnS2 is a promising electrode material in unconventional high-energy storage technologies.

Constructing Hollow Microcubes SnS2 as Negative Electrode for Sodium-ion and Potassium-ion Batteries

Sodium/potassium-ion batteries (NIBs and KIBs) are considered the most promising candidates for lithium-ion batteries in energy storage fields. Tin sulfide (SnS2) is regarded as an attractive negative candidate for NIBs and KIBs thanks to its superior power density, high-rate performance and natural richness. Nevertheless, the slow dynamics, the enormous volume change and the decomposition of polysulfide intermediates limit its practical application. Herein, microcubes SnS2 were prepared through sacrificial MnCO3 template-assisted and a facile solvothermal reaction strategy and their performance was investigated in Na and K-based cells. The unique hollow cubic structure and well-confined SnS2 nanosheets play an important role in Na+/K+ rapid kinetic and alleviating volume change. The effect of the carbon additives (Super P/C65) on the electrochemical properties were investigated thoroughly. The in operando and ex-situ characterization provide a piece of direct evidence to clarify the storage mechanism of such conversion-alloying type negative electrode materials.

Biotene: Earth-Abundant 2D Material as Sustainable Anode for Li/Na-Ion Battery

Natural ores are abundant, cost-effective, and environmentally friendly. Ultrathin (2D) layers of a naturally abundant van der Waals mineral, Biotite, have been prepared in bulk via exfoliation. We report here that this 2D Biotene material has shown extraordinary Li-Na-ion battery anode properties with ultralong cycling stability. Biotene shows 302 and 141 mAh g-1 first cycle-specific charge capacity for Li- and Na-ion battery applications with ∼90% initial Coulombic efficiency. The electrode exhibits significantly extended cycling stability with ∼75% capacity retention after 4000 cycles even at higher current densities (500-2000 mA g-1). Further, density functional theory studies show the possible Li intercalation mechanism between the 2D Biotene layers. Our work brings new directions toward designing the next generation of metal-ion battery anodes.

Cobalt-doped tin disulfide catalysts for high-capacity lithium-air batteries with high lifetime

Dual electrolyte lithium-air batteries have received widespread attention for their ultra-high energy density. However, the low internal redox efficiency of these batteries results in a relatively short operating life. SnS2 is widely used in Li-S batteries, Li-ion batteries, photocatalysis, and other fields due to the high discharge capacity in batteries. However, SnS2 suffers from low electrical conductivity and slow redox kinetics. In this study, Co-doped SnS2 is prepared by hydrothermal method for application in dual-electrolyte lithium-air batteries to study its electrochemical performance and its catalytic reaction process by DFT theory. Conductivity tests show that the Co doping enhances the electrical conductivity of the material and high transmission electron microscopy (HRTEM) results demonstrate that the Co doping of SnS2 increases the grain plane spacing and the material indicates that defects are created on the surface of the material, which is more beneficial to the electrochemical performance of the cell. Co-doped SnS2 exhibits excellent good cycling stability and high discharge capacity in a dual electrolyte lithium-air battery, maintaining a 0.7 V overpotential for 120 h at a current density of 0.1 mA cm-2, with a cell life of over 500 h and an initial discharge capacity showing excellent results up to 16 065 mA h g-1. In addition, this study explores the catalytic activity of Co-doped SnS2 based on density flooding theory (DFT). The results show that Co atoms have a synergistic effect with Sn atoms to perturb the lattice parameters. The calculations show that the catalytic activity is enhanced with the increasing of Co doping content and 3Co-Sn exhibits minimal overpotential.

Hybrid CuSn nanosphere-functionalized Cu/Sn co-doped hollow carbon nanofibers as anode materials for sodium-ion batteries

To strengthen the electrochemical performance of anode materials for sodium-ion batteries, Cu/Sn co-doped hollow carbon nanofibers functionalized by hybrid CuSn nanospheres (CuSn/C@MCNF) were prepared by a simple electrospinning method. The microstructural characteristics of CuSn/C@MCNF confirmed the same doped elements and strong interactions in hybrid CuSn nanospheres and the hollow carbon nanofiber substrate. CuSn/C@MCNF has superior specific capacity, excellent conductivity and high cycling stability. In particular, the doped hollow carbon nanofiber substrate can facilitate Na+ transport and alleviate volume expansion during the process of sodium storage. When applied as an anode material for sodium-ion batteries, CuSn/C@MCNF can deliver a reversible capacity of 340.1 mA h g-1 at a large current density of 1 A g-1 for 1000 cycles and a high-rate capacity of 202.5 mA h g-1 at 4.0 A g-1, all superior to the corresponding Sn-SnOx@MCNF- and MCNF-based electrodes. This work provides a basic idea for future anode materials in high-performance sodium-ion batteries.

Optimization of Sodium Storage Performance by Structure Engineering in Nickel-Cobalt-Sulfide

The development of high-performance electrode materials is crucial for the advancement of sodium ion batteries (SIBs), and NiCo2 S4 has been identified as a promising anode material due to its high theoretical capacity and abundant redox centers. However, its practical application in SIBs is hampered by issues such as severe volume variations and poor cycle stability. Herein, the Mn-doped NiCo2 S4 @graphene nanosheets (GNs) composite electrodes with hollow nanocages were designed using a structure engineering method to relieve the volume expansion and improve the transport kinetics and conductivity of the NiCo2 S4 electrode during cycling. Physical characterization and electrochemical tests, combined with density functional theory (DFT) calculations indicate that the resulting 3 % Mn-NCS@GNs electrode demonstrates excellent electrochemical performance (352.9 mAh g-1 at 200 mA g-1 after 200 cycles, and 315.3 mAh g-1 at 5000 mA g-1 ). This work provides a promising strategy for enhancing the sodium storage performance of metal sulfide electrodes.

Facile and High-Efficiency Chemical Presodiation Strategy on the SnS2/rGO Composite Anode for Stable Sodium-Ion Batteries

SnS₂/reduced graphite oxide (rGO) composite materials show great potential as high-performance anode candidates in sodium-ion batteries (SIBs) owing to their high specific capacities and power densities. However, the repeated formation/decomposition of the solid electrolyte interface (SEI) layer around composite anodes usually consumes additional sodium cations, resulting in poor Coulombic efficiency and decreasing specific capacity upon cycling. Therefore, in order to compensate for the large irreversible sodium loss of the SnS₂/rGO anode, this study has proposed a facile strategy by implementing organic solutions of sodium-biphenyl/tetrahydrofuran (Na-Bp/THF) and sodium-naphthylamine/dimethoxyethane (Na-Naph/DME) as chemical presodiation reagents. Particularly, the storage stability of Na-Bp/THF and Na-Naph/DME in ambient air accompanied by their presodiation behavior on the SnS₂/rGO anode has been investigated, and both reagents exhibited desirable ambient air-tolerant storage stability with favorable sodium supplement effects even after 20 days of storage. More importantly, the initial Coulombic efficiency (ICE) of SnS₂/rGO electrodes could be controllably increased by immersing in a presodiation reagent for different durations. Consequently, with a facile chemical presodiation strategy of immersion in Na-Bp/THF solution for only 3 min in ambient air, the presodiated SnS₂/rGO anode has exhibited an outstanding electrochemical performance with a high ICE of 95.6% as well as an ultrahigh specific capacity of 879.2 mAh g^-1 after 300 cycles (83.5% of its initial capacity), highly superior to the pristine SnS₂/rGO anode. This efficient and scalable presodiation strategy provides a new avenue for the prevailing application of other anode candidates in high-energy SIBs.

Multifunctional Nanocrystalline-Assembled Porous Hierarchical Material and Device for Integrating Microwave Absorption, Electromagnetic Interference Shielding, and Energy Storage

Multifunctional applications including efficient microwave absorption and electromagnetic interference (EMI) shielding as well as excellent Li-ion storage are rarely achieved in a single material. Herein, a multifunctional nanocrystalline-assembled porous hierarchical NiO@NiFe₂ O₄ /reduced graphene oxide (rGO) heterostructure integrating microwave absorption, EMI shielding, and Li-ion storage functions is fabricated and tailored to develop high-performance energy conversion and storage devices. Owing to its structural and compositional advantages, the optimized NiO@NiFe₂ O₄ /15rGO achieves a minimum reflection loss of -55 dB with a matching thickness of 2.3 mm, and the effective absorption bandwidth is up to 6.4 GHz. The EMI shielding effectiveness reaches 8.69 dB. NiO@NiFe₂ O₄ /15rGO exhibits a high initial discharge specific capacity of 1813.92 mAh g^-1 , which reaches 1218.6 mAh g^-1 after 289 cycles and remains at 784.32 mAh g^-1 after 500 cycles at 0.1 A g^-1 . In addition, NiO@NiFe₂ O₄ /15rGO demonstrates a long cycling stability at high current densities. This study provides an insight into the design of advanced multifunctional materials and devices and provides an innovative method of solving current environmental and energy problems.

Crab Shell-Derived SnS2/C and FeS2/C Carbon Composites as Anodes for High-Performance Sodium-Ion Batteries

The demand for energy storage devices has increased significantly, and the sustainable development of lithium-ion batteries is limited by scarce lithium resources. Therefore, alternative sodium-ion batteries which are rich in resource may become more competitive in the future market. In this work, we synthesized low-cost SnS₂/C and FeS₂/C anode materials of sodium-ion batteries which used waste crab shells as biomass carbon precursor. The SnS₂ nanosheet and FeS₂ nanosphere structures are deposited on the crab shell-derived carbon through simple hydrothermal reaction. Due to the coexistence of transition metal dichalcogenides (TMDs) and crab-derived biomass carbon, the anode material has excellent cycle stability and rate performance. SnS₂/C and FeS₂/C deliver capacities of 535.4 and 479 mA h g^-1 at the current density of 0.1 A g^-1, respectively. This study explored an effective and economical strategy to use biomass and TMDs to construct high-performance sodium-ion batteries.

Low volume expansion hierarchical porous sulfur-doped Fe2O3@C with high-rate capability for superior lithium storage

Ingenious morphology design and doping engineering have remarkable effects on enhancing conductivity and reducing volume expansion, which need to be improved by transition metal oxides serving as anode materials for lithium-ion batteries. Herein, S_0.15-Fe₂O₃@C nano-spindles with a hierarchical porous structure are obtained by carbonizing MIL-88B@PDA and subsequent high-temperature S-doping. Kinetic analysis showed that S-doping increases capacitive contribution, enhances charge transfer capability and accelerates Li⁺ diffusion rate. Therefore, the S_0.15-Fe₂O₃@C electrode exhibits superior lithium storage performance with a remarkable specific capacity of 1014.4 mA h g^-1 at 200 mA g^-1, ultrahigh rate capability of 513.1 mA h g^-1 at 5.0 A g^-1, and excellent cycling stability of 842.3 mA h g^-1 at 1.0 A g^-1 after 500 cycles. Moreover, the size of S_0.15-Fe₂O₃@C particles barely changed after 50 cycles, indicating an extremely low volume expansion, related to the carbon shell, fine Fe₂O₃ nanoparticles, abundant voids inside, and improved kinetics. This strategy can be applied to other metal oxides for synthesizing anodes with high-rate capability and low volume expansion.

Ammonium-Modified Synthesis of Vanadium Sulfide Nanosheet Assemblies toward High Sodium Storage

The weak van der Waals interactions of the one-dimensional (1D) chainlike VS₄ crystal structure can enable fast charge-transfer kinetics in metal ion batteries, but its potential has been rarely exploited in depth. Herein, a thermodynamics-driven morphology manipulation strategy is reported to tailor VS₄ nanosheets into 3D hierarchical self-assembled architectures including nanospheres, hollow nanospheres, and nanoflowers. The ultrathin VS₄ nanosheets are generated via 2D anisotropic growth by the strong driving force of coordination interaction from ammonium ions under microwave irradiation and then evolve into 3D sheet-assembled configurations by adjusting the thermodynamic factors of temperature and reaction time. The as-synthesized VS₄ nanomaterials present good electrochemical performances as the anode materials for sodium-ion batteries. In particular, the hollow VS₄ nanospheres show a specific capacity of 1226.7 mAh g^-1 at 200 mA g^-1 current density after 100 cycles. The hierarchical nanostructures with large specific surface area and structural stability can overcome the difficulty of sodium ions embedding into the bulk material interior and provide more reactive materials at the same material mass loading compared with other morphologies. Both experiment and DFT calculations suggest that VS₄ nanosheets reduce reaction kinetic impediment of sodium ion in battery operating. This work demonstrates a way of the morphological design of 2D VS₄ nanosheets and application in sodium ion storage.

Facile One-Step Microwave-Assisted Method to Synthesize Nickel Selenide Nanosheets for High-Performance Hybrid Supercapacitor

Nanosheets structures can be employed as the most promising electrode material to enhance electrochemical performance for supercapacitors. Nickel Selenide (Ni_0.85Se) nanosheets are synthesized using a rapid microwave synthesis method in a single step. The Ni_0.85Se nanosheets possess a high surface area (125 m²g^-1) with a hexagonal crystalline structure. It shows magnificent electrochemical properties, such as splendid specific capacitance (2530 Fg^-1 at 0.5 Ag^-1). An asymmetric hybrid supercapacitor is fabricated with nickel selenide nanosheets as a positive electrode and activated carbon as a negative electrode. The assembled hybrid supercapacitor displays a high energy density of 63.5 WhKg^-1 at a power density of 404 WKg^-1, and after 8000 cycles, only 5% capacitance is lost along with the better voltage window at 0-1.6 V.

Anionic Te-Substitution Boosting the Reversible Redox in CuS Nanosheet Cathodes for Magnesium Storage

The conversion-type copper chalcogenide cathode materials hold great promise for realizing the competitive advantages of rechargeable magnesium batteries among next-generation energy storage technologies; yet, they suffer from sluggish kinetics and low redox reversibility due to large Coulombic resistance and ionic polarization of Mg²⁺ ions. Here we present an anionic Te-substitution strategy to promote the reversible Cu⁰/Cu⁺ redox reaction in Te-substituted CuS_1-xTe_x nanosheet cathodes. X-ray absorption fine structure analysis demonstrates that Te dopants occupy the anionic sites of sulfur atoms and result in an improved oxidation state of the Cu species. The kinetically favored CuS_1-xTe_x (x = 0.04) nanosheets deliver a specific capacity of 446 mAh g^-1 under a 20 mA g^-1 current density and a good long-life cycling stability upon 1500 repeated cycles with a capacity decay rate of 0.0345% per cycle at 1 A g^-1. Furthermore, the CuS_1-xTe_x (x = 0.04) nanosheets can also exhibit an enhanced rate capability with a reversible specific capacity of 100 mAh g^-1 even under a high current density of 1 A g^-1. All the obtained electrochemical characteristics of CuS_1-xTe_x nanosheets significantly exceed those of pristine CuS nanosheets, which can contribute to the improved redox reversibility and favorable kinetics of CuS_1-xTe_x nanosheets. Therefore, anionic Te-substitution demonstrates a route for purposeful cathode chemistry regulation in rechargeable magnesium batteries.

Phosphorus Doping Induced the Co-Construction of Sulfur Vacancies and Heterojunctions in Tin Disulfide as a Durable Anode for Lithium/Sodium-Ion Batteries

The reasonable design of electrode materials with heterojunction and vacancy is a promising strategy to elevate its electrochemical performances. Herein, tin-based sulfide composites with heterojunction and sulfur vacancy encapsulated by...

Dual Enhancement of Sodium Storage Induced through Both S-Compositing and Co-Doping Strategies

As a promising alternative to lithium-ion batteries (LIBs), rechargeable sodium-ion batteries (SIBs) are attracting enormous attention due to the abundance of sodium. However, the lack of high-performance sodium anode materials limits the commercialization of SIBs. In this work, the dual enhancement of SnS₂/graphene anodes in sodium storage is achieved through S-compositing and Co doping via an innovative one-step hydrothermal reaction at a relatively low temperature of 120 °C. The as-prepared 7% Co-SnS₂/S@r-G composite consisting of 15.4 wt % S and 1.49 atom % Co shows both superior cycling stability (over 1000 cycles) and rate capability, giving high reversible specific capacities of 878, 608, and 470 mAh g^-1 at 0.2, 5, and 10 A g^-1, respectively. More encouragingly, the full-cell also exhibits an outstanding long-term cycling performance under 0.5 A g^-1, which delivers a reversible capacity of 500 mAh g^-1 over 200 cycles and still retains a high reversible capacity of 432 mAh g^-1 over 400 cycles. The enhancement mechanism is attributed to the favorable three-dimensional structure of the composite, Co doping, and S-composition, which can induce a synergistic effect.

Construction of series-wound architectures composed of metal-organic framework-derived hetero-(CoFe)Se2 hollow nanocubes confined into a flexible carbon skeleton as a durable sodium storage anode

Metal chalcogenides with structural pulverization/degradation and intrinsic low electrical conductivity trigger the challenging issues of serious capacity fading and inferior rate capability upon repeated de-/sodiation cycling. Multiple electroactive heterostructures can integrate the inherent advantages of a strong synergistic coupling effect to improve their electrochemical Na+-storage behavior and structural durability, showing robust mechanical features, fast Na+ immigration and abundant active insertion sites at intriguing heterointerfaces. Hence, a series-wound architecture of metal-organic framework (MOF)-derived heterogeneous (CoFe)Se2 hollow nanocubes confined into a one-dimension carbon nanofiber skeleton ((CoFe)Se2@CNS) was successfully developed via a template-assisted liquid phase anion exchange followed by electrospinning and conventional selenization treatment. When examined as an anode for sodium ion batteries, the (CoFe)Se2@CNS electrode exhibits remarkably enhanced electrochemical Na+-storage performance delivering a high sodiation capacity as high as 213.9 mA h g-1 after 3650 cycles at 5 A g-1 with a capacity degradation rate of only 0.0047% per cycle; specifically, it shows tremendous rate performance and ultrastable cycling durability of 194.7 mA h g-1 at a high rate of 8 A g-1 after 5630 cycles. This work can shed light on a fundamental approach for designing heterostructures of multiple electroactive components toward high-performance alkali metal ion batteries.

Cream roll-inspired advanced MnS/C composite for sodium-ion batteries: encapsulating MnS cream into hollow N,S-co-doped carbon rolls

With advantages of high theoretical capacity and low cost, manganese sulfide (MnS) has become a potential electrode material for sodium-ion batteries (SIBs). However, complicated preparations and limited cycle life still hinder its application. Inspired by cream rolls in our daily life, a MnS/N,S-co-doped carbon tube (MnS/NSCT) composite with a 3D cross-linked tubular structure is prepared via an ultra-simple and low-cost method in this work. As the anode for SIBs, the cream roll-like MnS/NSCT composite has delivered the best electrochemical performance to date (the highest capacity of 550.6 mA h g^-1 at 100 mA g^-1, the highest capacity of 447.0 mA h g^-1 after 1400 cycles at 1000 mA g^-1, and the best rate performance of 319.8 mA h g^-1 at 10 000 mA g^-1). Besides, according to several in situ and ex situ techniques, the sodium storage mechanism of MnS/NSCTs is mainly from a conversion reaction, and the superior electrochemical performance of MnS/NSCTs is mainly attributed to the unique cream roll-like structure. More importantly, this simple method may be feasible for other anode materials, which will greatly promote the development of SIBs.

Hierarchical Co-doped SnS2@Ni(OH)2 double-shell crystalline structure on carbon cloth with gradient pore distribution for superior capacitance

Hierarchical Co-doped SnS₂@Ni(OH)₂ double-shell nanosheet arrays are coated on carbon cloth, the vertically aligned arrays with gradient pore distribution can facilitate the charge/ion transfer rate, thus improve the energy storage performance.