Cycling Stability Research Articles

Electric Double Layer Oriented Eutectic Additive Design towards Stable Zn Anodes with A High Depth of Discharge.

ZnSO4-based electrolytes for aqueous zinc ion batteries (AZIBs) fail to meet practical application metrics due to hydrogen evolution reaction (HER) and dendrite growth. In this work, we rationally designed a highly polarized eutectic additive, glycerophosphorylcholine (GPC), to regulate the EDL structure for stable Zn anodes with a high depth of discharge (DOD). On one hand, GPC molecules with abundant hydroxyl groups can precisely regulate the hydrogen bond network in EDL to suppress HER. On the other hand, the enrichment of GPC at the interface is positively responsible for the negative charge density on the Zn surface, which leads to the formation of a robust ZnxPyOz-rich solid-electrolyte interphase (SEI) and terminates dendrite growth in the charge-rich sites. This EDL-oriented eutectic additive engineering enables highly reversible and selectively (002)-textured Zn anodes to operate for over 1450h at a high DOD of 45.3%. Meanwhile, a high-capacity (185.7 mAh g-1) aqueous Zn||VS2 full cell shows remarkable cycling stability over 220 cycles with an excellent capacity retention of 90.4% even at a low current density of 0.1 A g-1 (0.5 C). This work sheds light on electrolyte design and interface engineering for high-performance aqueous batteries. This article is protected by copyright. All rights reserved.

Scalable Precise Nanofilm Coating and Gradient Al Doping Enable Stable Battery Cycling of LiCoO2 at 4.7 V.

The quest for smart electronics with higher energy densities has intensified the development of high-voltage LiCoO2 (LCO). Despite their potential, LCO materials operating at 4.7 V faces critical challenges, including interface degradation and structural collapse. Herein, we propose a collective surface architecture through precise nanofilm coating and doping that combines an ultra-thin LiAlO2 coating layer and gradient doping of Al. This architecture not only mitigates side reactions, but also improves the Li+ migration kinetics on the LCO surface. Meanwhile, gradient doping of Al inhibited the severe lattice distortion caused by the irreversible phase transition of O3-H1-3-O1, thereby enhanced the electrochemical stability of LCO during 4.7 V cycling. DFT calculations further revealed that our approach significantly boosts the electronic conductivity. As a result, the modified LCO exhibited an outstanding reversible capacity of 230 mAh g-1 at 4.7 V, which is approximately 28% higher than the conventional capacity at 4.5 V. To demonstrate their practical application, our cathode structure shows improved stability in full pouch cell configuration under high operating voltage. LCO exhibited an excellent cycling stability, retaining 82.33% after 1000 cycles at 4.5 V. This multifunctional surface modification strategy offers a viable pathway for the practical application of LCO materials.

A Strong, Tough, and Stable Composite with Nacre-Inspired Sandwich Structure.

Improving the fracture resistance of nacre-inspired composites is crucial in addressing the strength-toughness trade-off. However, most previously proposed strategies for enhancing fracture resistance in these composites have been limited to interfacial modification by polymer, which restricts mechanical enhancement. Here, a composite material consisting of graphene oxide (GO) lamellae and nanocrystalline reinforced amorphous alumina nanowires (NAANs) has been developed. The structure of the composite is inspired by nacre and is composed of stacked GO nanosheets with NAANs in between, forming a sandwich-like structure. This design enhances the fracture resistance of the composite through the pull-out of GO nanosheets at the nanoscale and GO/NAANs sandwich-like coupling at the micro-scale, while also providing stiff ceramic support. This composite simultaneously possesses high strength (887.8MPa), toughness (31.6MJm-3), superior cyclic stability (1600 cycles), and long-term (2 years) immersion stability, which outperform previously reported GO-based lamellar composites. The hierarchical fracture design provides a new path to design next-generation strong, tough, and stable materials for advanced engineering applications.

Microwave synthesis of magnesium phosphate-rGO as an effective electrode for supercapacitor application

Abstract Transition metal phosphate based materials is being used for energy storage because of P–O covalent bond which facilitates more storage compared to other transition metals and this covalent bond enhanced the electrochemical performance for supercapacitor applications. Pure magnesium phosphate (Mg3(PO4)2) were synthesized via microwave synthesis as the composite varies with rGO (MgPO-XrGO) X=25,50,75,100mg. The prepared composite materials were examined employing XRD, Raman, FT-IR, SEM and XPS studies. Electrochemical studies (CV, EIS, GCD) of three electrode system for the prepared electrodes were performed using Biologic SP-150 with 2M (H2SO4) as electrolyte. From the XRD results, triclinic structured MgPO was confirmed (JCPDS card #35–0329) and rGO has enhanced the crystallinity of MgPO composite. From Raman analyses, the well graphitization nature of rGO in composite MgPO was identified and from XPS analysis chemical composition of the elements was analyzed. The FT-IR fundamental modes of vibrations of PO 4 3 − ${\text{PO}}_{4}^{3-}$ (γ 1,γ 3,γ 4) were obtained. The electrochemical analysis of the prepared material such as pure and composite materials showed better performance. The high specific capacitance was obtained for MgPO-50rGO because MgPO has high coordination with rGO. As Mg2+ oxidation state has high chemical reactivity compared to other earth metals and other advantage is P–O covalent bond that enhanced the performance of the electrode. By facilitating these advantages, rGO is included as composite to develop the electrode to favor the practical applications. By using the optimum level rGO composite with MgPO4-50rGO a better new candidate was successfully developed for supercapacitor applications. The fabricated MgPO-50rGO//Activate carbon full cell set up exhibited the specific capacitance 61 Fg−1 at 1 Ag−1, 21.7 Wh kg−1 energy density and 790.0 W kg−1 power densities and explored outstanding capacitive retention in 2 electrode full cell setup cyclic stability of 99.1 % over the 5000 cycles.

Precycling Strategy in Suitable Voltage to Improve the Stability of Interfacial Film and Suppress the Decline of LiNi0.6Mn0.2Co0.2O2 Cathode at Elevated Temperatures.

Layered ternary oxide LiNixMnyCo1-x-yO2 is a promising cathode candidate for high-energy lithium-ion batteries (LIBs). However, the capacity of LIBs is significantly restricted by several factors, including the repeated dissolution-regeneration of the interfacial film at high temperatures, the dissolution of transition metals, and the increase of impedance. Herein, a new precycling strategy in suitable voltage scope at room temperature is proposed to construct a uniform, thermally stable, and insoluble cathode-electrolyte interface (CEI), which helps to maintain stable cycling performances at high temperatures. Specifically, after 5 precycles in the range of 3.85-4.3 V at room temperature, a CEI layer containing numerous inorganic components and oligomers is formed on the surface of LiNi0.6Mn0.2Co0.2O2. Subsequently, the harmful side reactions are effectively suppressed, endowing the cell with an excellent capacity retention of 84.67% after 50 cycles at 0.5C and 55 °C, much higher than that of 65.61% under the conventional film-forming process conditions. This work emphasizes the crucial role of the precycling strategy in regulating the characteristics of CEI layer on the surface of cathode electrode, opening up a new avenue for the high-temperature application of positive electrodes of LIBs.

Asymmetric Wettability Janus Mesh via Electrostatic Printing for Selective Oil-Water and Emulsion Separation.

Janus mesh with two-sided asymmetric wettability shows high potential for selective oil-water and emulsion separation. However, it remains a challenge to construct Janus mesh structures with good stability and extremely asymmetric wettability. Herein, a novel Janus mesh with asymmetric wettability was structured by two different precursors, polydimethylsiloxane/zinc oxide (PDMS/ZnO) and zinc oxide-polyacrylonitrile/N,N-dimethylformamide (ZnO-PAN/DMF), by electrostatic printing, including electrostatic air spraying and electrostatic spinning. The prepared Janus mesh has special micro-nanostructures on two sides, including PDMS@ZnO and ZnO@PAN. On the basis of gravity, when the placement direction is changed, Janus mesh can effectively separate oil-water mixtures of different densities and surfactant-stabilized oil-water emulsions. Meanwhile, the obtained Janus mesh exhibited good separation efficiency (>96.3%) for various oil-water mixtures, and the flux was up to 2621 ± 30 L m-2 h-1. The Janus mesh was cycled 20 times with no weakening in separation efficiency, indicating satisfactory cycling stability. The Janus mesh displayed good stability under harsh conditions (acidic, alkaline, and high temperature). The Janus mesh can realize low energy input and long-lasting oil-water separation, which has widespread application prospects in intelligent oil-water separation. This top-down electrostatic printing strategy provides a way to construct Janus interface materials with practical applications.

In Situ Integration of a Flame Retardant Quasisolid Gel Polymer Electrolyte with a Si-Based Anode for High-Energy Li-Ion Batteries.

Silicon (Si) stands out as a promising high-capacity anode material for high-energy Li-ion batteries. However, a drastic volume change of Si during cycling leads to the electrode structure collapse and interfacial stability degradation. Herein, a multifunctional quasisolid gel polymer electrolyte (QSGPE) is designed, which is synthesized through the in situ polymerization of methylene bis(acrylamide) with silica-nanoresin composed of nanosilica and a trifunctional cross-linker in cells, leading to the creation of a "breathing" three-dimensional elastic Li-ion conducting framework that seamlessly integrates an electrode, a binder, and an electrolyte. The silicon particles within the anode are encapsulated by buffering the QSGPE after cross-linking polymerization, which synergistically interacts with the existing PAA binder to reinforce the electrode structure and stabilize the interface. In addition, the formation of the LiF- and Li3N-rich SEI layer further improves the interfacial property. The QSGPE demonstrates a wide electrochemical window until 5.5 V, good flame retardancy, high ionic conductivity (1.13 × 10-3 S cm-1), and a Li+ transference number of 0.649. The advanced QSGPE and cell design endow both nano- and submicrosized silicon (smSi) anodes with high initial Coulombic efficiencies over 88.0% and impressive cycling stability up to 600 cycles at 1 A g-1. Furthermore, the NCM811//Si cell achieves capacity retention of ca. 82% after 100 cycles at 0.5 A g-1. This work provides an effective strategy for extending the cycling life of the Si anode and constructing an integrated cell structure by in situ polymerization of the quasisolid gel polymer electrolyte.

Engineering strategies for high‐voltage LiCoO2 based high‐energy Li‐ion batteries

AbstractTo drive electronic devices for a long range, the energy density of Li‐ion batteries must be further enhanced, and high‐energy cathode materials are required. Among the cathode materials, LiCoO2 (LCO) is one of the most promising candidates when charged to higher voltages over 4.3 V. However, high‐voltage LCO materials are confronted with severe surface and bulk issues inducing poor cyclic stability. To completely unleash the potential of LCO cathodes, a more comprehensive theoretical understanding of the underlying issues is necessary, along with active exploration of previous modifications. This paper mainly presents the degradation mechanisms of LCO under high voltage, the formation and evolution mechanisms of the cathode electrolyte interface, and the surface engineering strategies employed to enhance the cell performance. By organizing and summarizing these modifications, this work aims to establish associations among common research issues and to suggest future research priorities, thus facilitating the rapid development of high‐voltage LCO.

Dealloyed nickel skeleton hosting in-situ formed multimetallic phosphides for enhanced electrochemical energy storage

Transition metal phosphides (TMPs) exhibit considerable potential in supercapacitors (SCs) electrodes fabrication due to their high power densities and conducive ion transport, positioning them as quintessential candidates for such application. Despite their promise, monometallic phosphides require further electrochemical performance enhancements. This work unveils an innovative strategy for synthesizing complex cobalt/nickel phosphides directly on a nickel skeleton (Ni@NCP), achieved by the selectively leaching copper from a Ni–Cu alloy via a dealloying process after electrodeposition, significantly improving electrochemical performance through increased electroactive sites and optimized ion diffusion channels. The Ni@NCP electrode exhibits an impressive specific capacitance of 612 F g−1 at a high current density of 20 A g−1. Furthermore, the unique hollow nanotube structure greatly enhances cyclic stability, maintaining 80.1 % capacity after 10,000 cycles at 10 A g−1. This research presents a methodical approach to electrode material synthesis, emphasizing the construction of supportive frameworks and active sites, thereby underscoring the substantial potential for advancements in SC electrode technology.

Metal-Organic Framework for Aluminum based Energy Storage Devices: Utilizing Redox Additives for Significant Performance Enhancement.

There are various methods being tried to address the sluggish kinetics observed in Al-ion batteries (AIBs). They mostly deal with morphology tuning, but have led to limited improvement. A new approach is proposed to overcome this limitation. It focuses on the use of a redox additive modified electrolyte in combination with framework like materials, which have wider channels. The ordered microporous and interconnected framework of ZIF 67, with large surface area, effectively facilitates the diffusion of aluminum ions. Therefore, AIBs are able to exhibit a superior discharge capacity of 288 mAh g-1 at 0.2 A g-1 current density with robust cycling stability. The addition of potassium ferricyanide as a redox-active species in an aqueous solution of aluminum chloride (supporting electrolyte) leads to significant enhancement in the specific capacity with much higher cycling stability. Al-ion based BatCap devices can be assembled by using ZIF 67 as the cathode, ZIF 67 derived porous carbon as the anode, and a redox additive modified electrolyte. The BatCap device exhibits excellent energy density of 86 Wh kg-1 at a power density of 2 KW kg-1, which is higher than reported aqueous AIBs. The ex situ characterization clearly explains the unexplored mechanism of redox additives in AIBs.

Superior Oxygen Evolution Electrocatalyst based on Ni‐Ellagic Acid Coordination Polymer

AbstractThe oxygen evolution reaction (OER) is central to energy conversion technologies, but the high cost and scarcity of commercial noble metal catalysts limit their widespread application. Natural products exhibit great potential in preparing high‐performance electrocatalysts due to their cost‐effectiveness and sustainability. Here, a kind of 1D polymers [M‐EA (M═Co, Cu, Ni)] for oxygen evolution reaction via the complexation of ellagic acid (EA) with metal ions are reported. It is found that Ni‐EA displays a low overpotential (190 mV at 10 mA cm−2) and an ultralow Tafel slope (28 mV dec−1), with a production cost of only 3.6 × 10−2% of IrO2. Density functional theory investigations reveal the electrocatalytic mechanism of the OER. A rechargeable Zn‐Air battery using Ni‐EA+Pt/C as the air electrode shows a lower charging potential and better cycling stability than the IrO2+Pt/C‐based battery. This work provides a train for the development of state‐of‐the‐art OER catalysts.

Tailoring porous structure in non-ionic polymer membranes using multiple templates for low-cost iron-lead single-flow batteries

Porous ion-selective membranes are promising alternatives for the expensive perfluorosulfonic acid membranes in redox flow batteries. In this work, novel non-ionic porous polyvinylidene fluoride-hexafluoro propylene membranes are designed for iron-lead single-flow batteries. The membranes are prepared using a multiple template approach, involving simultaneously using polyethylene glycol and dibutyl phthalate (DBP) as pore-forming templates. Their porous structure is finely tuned by adjusting the ratio of the two templates. As a result, dual-porous membranes bearing both macro and micropores are obtained. The H3520 membrane with modified porous structure attains a high proton conductivity of 43.5 mS·cm-1 and a relatively low ferric ion diffusion constant (8.61 × 10-8 cm2·min-1) and demonstrates the best balance between these performance-determining parameters (selectivity 5.04 × 105 S·min·cm-3, higher than that of the N115 membrane). Besides, performance tests of the iron-lead single-flow single cells equipped with the dual-porous membranes show a high energy efficiency, exceeding 87.2% at its rated current density, and outstanding cycling stability over 200 charge-discharge cycles. Altogether, the mixed template method presents a promising strategy to prepare high-performance and low-cost non-ionic membranes for redox flow batteries.

Scalable Customization of Crystallographic Plane Controllable Lithium Metal Anodes for Ultralong-Lasting Lithium Metal Batteries.

A formidable challenge to achieve the practical applications of rechargeable lithium (Li) metal batteries (RLMBs) is to suppress the uncontrollable growth of Li dendrites. One of the most effective solutions is to fabricate Li metal anodes with specific crystal plane, but still lack of a simple and high-efficient approach. Herein, a facile and controllable way for the scalable customization of polished Li metal anodes with highly preferred (110) and (200) crystallographic orientation (donating as polished Li(110) and polished Li(200), respectively) by regulating the times of accumulative roll bonding, is reported. According to the inherent characteristics of polished Li(110)/Li(200), the influence of Li atomic structure on the electrochemical performance of RLMBs is deeply elucidated by combining theoretical calculations with relative experimental proofs. In particular, a polished Li(110) crystal plane is demonstrated to induce Li+ uniform deposition, promoting the formation of flat and dense Li deposits. Impressively, the polished Li(110)||LiFePO4 full cells exhibit unprecedented cycling stability with 10000 cycles at 10 C almost without capacity degradation, indicating the great potential application prospect of such textured Li metal. More valuably, this work provides an important reference for low-cost, continued, and large-scale production of Li metal anodes with highly preferred crystal orientation through roll-to-roll manufacturability.

High Seebeck Coefficient Thermally Chargeable Supercapacitor with Synergistic Effect of Multichannel Ionogel Electrolyte and Ti3C2Tx MXene‐Based Composite Electrode

Thermally chargeable supercapacitors can collect low‐grade heat generated by the human body and convert it into electricity as a power supply unit for wearable electronics. However, the low Seebeck coefficient and heat‐to‐electricity conversion efficiency hinder further application. In this paper, we designed a high‐performance thermally chargeable supercapacitor device composed of ZnMn2O4@Ti3C2Tx MXene composites (ZMO@Ti3C2Tx MXene) electrode and UIO‐66 metal–organic framework doped multichannel polyvinylidene fluoridehexafluoro‐propylene ionogel electrolyte, which realized the thermoelectric conversion and electrical energy storage at the same time. This thermally chargeable supercapacitor device exhibited a high Seebeck coefficient of 55.4 mV K−1, thermal voltage of 243 mV, and outstanding heat‐to‐electricity conversion efficiency of up to 6.48% at the temperature difference of 4.4 K. In addition, this device showed excellent charge–discharge cycling stability at high‐temperature differences (3 K) and low‐temperature differences (1 K), respectively. Connecting two thermally chargeable supercapacitor units in series, the generated output voltage of 500 mV further confirmed the stability of devices. When a single device was worn on the arm, a thermal voltage of 208.3 mV was obtained indicating the possibility of application in wearable electronics.

Chemical vapor deposition-grown single-layer graphene-supported nanostructured Co3O4 composite as binder-free electrode for asymmetric supercapacitor and electrochemical detection of caffeic acid

In this study, we developed a monolayer graphene/nanostructured cobalt oxide (MLG/Co3O4) composite for asymmetric supercapacitor and electrochemical sensor applications. The MLG was grown by chemical vapor deposition process and the Co3O4 nanostructures were electrodeposited on the MLG surface. Scanning electron microscopy proved that there were flower-like nanostructured Co3O4 densely electrodeposited on the MLG surface. At a current density of 3 mA cm−2, the MLG/Co3O4 composite produced an areal capacitance of 3.73 F cm−2. After 10,000 cycles, the composite electrode still had 93.6 % of its initial capacitance at 5 mA cm−2. The asymmetric system displayed an areal capacitance of 929 mF cm−2 at 4 mA cm−2 with good cycle stability. The asymmetric electrode produced a specific energy of 51 μWh cm−2 and a specific power of 11.1 mW cm−2. Cyclic voltammetric measurements demonstrated that the composite showed redox peaks at 0.48 eV and 0.09 eV toward the determination of CA. With a sensitivity of 0.13 µA/µM/cm2 and a limit of detection of 0.009 µM, the composite showed CA concentrations, ranging from 0.5 to 480 M. The composite displayed excellent selectivity and the current produced for the interfering compounds was exceedingly low. Using the composite electrode, the spiked CA in red wine and green tea samples recovered remarkably effectively.

Construction of Z‐scheme 1T/2H‐MoS2/CdS for improving photocatalytic degradation of antibiotic residues

Abstract1T/2H‐MoS2/CdS composite was effectively prepared by a two‐step hydrothermal method, which greatly improved the photocatalytic degradation efficiency of tetracycline hydrochloride and photocatalytic cycle stability compared with pristine 1T/2H‐MoS2. The highest photodegradation efficiency of 70.8% is achieved when the molar ratio of 1T/2H‐MoS2 to cadmium sulfide is 1:4. The capture experiment indicates that hydroxyl radical (⋅OH) and superoxide radical (⋅O2−) play a role in the photocatalytic degradation process. A Z‐type heterojunction may be formed on the 1T/2H‐MoS2/CdS composite based on a series of analyses, which improves the photocatalytic performance effectively via expanding the range of light response and promoting the separation of photogenerated electrons and holes. This work provides an alternative to constructing novel Z‐scheme photocatalysts with high performance in the absence of noble metals.

Highly conductive titanium nitride core sterically reinforced nickel-vanadium layered double hydroxides for supercapacitors

Nickel vanadium layered double hydroxide (NiV-LDH) is a highly promising electrode material for supercapacitors, but its poor electrochemical durability and conductivity limit its capacitance performance as a high-performance supercapacitor electrode. In contrast, titanium nitride (TiN) stands out for its outstanding electrochemical durability and superior conductivity. In this work, a composite material (TiN@NiV-LDH) with outstanding electrochemical performance was prepared by a simple hydrothermal method, where nickel vanadium layered double hydroxide nanosheets were vertically grown in a staggered manner on the surface of amorphous titanium nitride nanoparticles. The results demonstrate that at a current density of 2 A g−1, the capacitance of TiN@NiV-LDH reaches 712.4 F g−1. In addition, the assembled TiN@NiV-LDH//AC asymmetric supercapacitor exhibits a high energy density of 136.5 Wh kg−1 at a high power density of 1549.9 W kg−1, and after 10,000 cycles at a high current density of 20 A g−1, it retains 80.2 % excellent cyclic stability. This work, based on nickel vanadium layered double hydroxide and utilizing titanium nitride modification, aims to enhance the long-term stability of nickel vanadium layered double hydroxide while preserving its advantageous properties, providing a promising strategy for designing efficient supercapacitor electrodes.

Synthesis of Stable and Efficient Electrocatalysts for Hydrogen Evolution: Hierarchical NiMo-Based Hollow Nanotubes

Large-scale development of low-cost, efficient, and stable powder electrocatalysts for the hydrogen evolution reaction (HER) in alkaline solutions is a key step toward commercial hydrogen production. Herein, a hierarchical NiMo-MoO3-x hollow nanotube (NiMo-MoO3-x-HNT) with bifunctional groups as an efficient HER electrocatalyst was strategically invented using an MoO3 nanorod (MoO3−NR) as the precursor. The synthesis mechanism of the NiMo-MoO3-x-HNT is established based on in-depth investigations using diffraction, spectral, and microscopy results. Experimental results suggest that the NiMo-MoO3-x-HNT exhibits excellent electrocatalytic HER performance in 1 M KOH, with a low overpotential of 26.5 mV@10.0 mA cm-2 and a small Tafel slope of 32.6 mV dec–1. These values are comparable to those of cutting-edge electrocatalysts based on platinum-group metals. Moreover, it exhibits an almost unaffected cyclic stability over 50,000 cycles and robust durability over 98 h. This remarkable performance is attributed to its bifunctional groups and the porous hierarchical hollow nanotubular morphology. In summary, this study proposes a novel, efficient, and cost-effective strategy for the development of noble metal-free, high-performance HER electrocatalysts.

Antioxidant Interfaces Enabled by Self‐Deoxidizing and Self‐Dehydrogenating Redox Couple for Reversible Zinc Metal Batteries

AbstractParasitic electrolyte reactions and dendrite growth make Zn metal anodes with high Zn utilization rates (ZURs) more inaccessible, holding back the advance of aqueous zinc metal batteries (AZMBs). Here, sodium isoascorbate (SIA) is introduced to aqueous electrolytes as a self‐deoxidizing and self‐dehydrogenating additive. Coexisting C6H7O6−/C6H5O6− couple spontaneously captures dissolved oxygen and eliminates generated hydrogen by acting as a redox buffer, which leads to the creation of antioxidant Interfaces due to an in situ formed ZnCO3‐dominated solid electrolyte interphase (SEI). This SEI enables the (100) faceted electrode with dendrite‐free and non‐corrosive Zn plating/stripping, thus yielding a Coulombic efficiency of 99.7% up to 1100 h at 5 mAh cm−2, as well as a stable cycle sustaining for over 335 h under a high ZUR of 85.5%. Full‐cell properties are demonstrated by matching a poly(3,4‐ethylenedioxythiophene) intercalated vanadium oxide (PEDOT‐V2O5) cathode, which harvests a high capacity of 302 mAh g−1 (at 0.01 A g−1) and holds 94.2% capacity retention over 600 cycles (at 1 A g−1) under practical conditions (N/P = 4.2 and E/C = 7.6 µL mg−1). These findings provide a new solution for electrolyte design for industrializing AZMBs.

Rational design of hollow C@SnS2/SnS@C cubes with N-doping to realize stepwise sodium storage induced structural stability for highly stable cycling performance

Current application of SnS2-based anodes in sodium-ion batteries fails to meet the demand for higher Na+ storage capacity due to the structural pulverization induced by significant volume changes during cycling. Herein, a novel composite of hollow C@SnS2/SnS@C cubes with excellent diffusion kinetics and structural stability from stepwise Na+ storage is designed. The SnS with gentle pseudocapacitive reaction acts as the self-supporter to prevent the collapse of SnS2/SnS heterostructure during the Na+ insertion/extraction. Together with the clamping of double carbon layers and hollow construction, the volume change caused structural instability in heterostructure is effectively alleviated. The rapid transport of electrons and ions within the built-in electric field of heterostructure endows the composite an excellent diffusion kinetics, which is generated from the narrow bandgap and outstanding Na+ absorption of heterostructure according to the first-principle calculation. Thus, the as-prepared composite maintains a remarkable capacity of 547.9 mAh g−1 after 200 cycles at current density of 0.5 A g−1. Even a capacity of 502.5 mAh g−1 with a low attenuation rate of 0.035 % per cycle is achieved at 2 A g−1 after 1000 cycles. The work proposes an effective approach to achieve effective Na + storage of SnS2-based anodes with long-lasting structural stability.