Ultra-long Cycling Performance Research Articles

Constructing Lysozyme Protective Layer via Conformational Transition for Aqueous Zn Batteries.

The practical applications for aqueous Zn ion batteries (ZIBs) are promising yet still impeded by the severe side reactions on Zn metal. Here, a lysozyme protective layer (LPL) is prepared on Zn metal surface by a simple and facile self-adsorption strategy. The LPL exhibits extremely strong adhesion on Zn metal to provide stable interface during long-term cycling. In addition, the self-adsorption strategy triggered by the hydrophobicity-induced aggregation effect endows the protective layer with a gap-free and compacted morphology which can reject free water for effective side reaction inhibition performance. More importantly, the lysozyme conformation is transformed from α-helix to β-sheet structure before layer formation, thus abundant functional groups are exposed to interact with Zn2+ for electrical double layer (EDL) modification, desolvation energy decrease, and ion diffusion kinetics acceleration. Consequently, the LPL renders the symmetrical Zn battery with ultra-long cycling performance for more than 1200 h under high Zn depth of discharge (DOD) for 77.7%, and the Zn/Zn0.25V2O5 pouch cell with low N/P ratio of 2.1 at high Zn utilization of 48% for over 300 cycles. This study proposes a facile and low-cost method for constructing a stable protective layer of Zn metal for high Zn utilization aqueous devices.

Improving the structural stability and reaction kinetic of Na3V2(PO4)3 through tungsten doping towards the ultralong cycle performance and excellent temperature tolerance of sodium ion batteries

A series of carbon-coated tungsten doping NVP (Na(3-x)V(2-x)Wx(PO4)3@C, x = 0, 0.05, 0.1, 0.2, 0.3) was synthesized by sol–gel method. Characterization reveals that partial substitution of V by the larger W has beneficial influences on the structure and diffusion kinetics of NVP. Consequently, the optimized NVP-W0.1@C electrode releases a reversible initial capacity of 116 mA h g−1 at 1C, that is quite near to the theoretical value of pure NVP (117 mA h g−1). Furthermore, it delivers a high reversible capacity of 83.6 mA h g−1 at 50C with marvelous 94.3 % retention over 18,000 cycles. Desirable performances are demonstrated at −20 °C and 45 °C respectively, suggesting its viability in harsh environment. This work shed a light on scalable and feasible routine to regulate SIBs-based cathodes with promising performances.

Synchronous Regulation of D-Band Centers in Zn Substrates and Weakening Pauli Repulsion of Zn Ions Using the Ascorbic Acid Additive for Reversible Zinc Anodes.

The advanced aqueous zinc-ion batteries (AZIBs) are still challenging due to the harmful reactions including hydrogen evolution and corrosion. Here, a natural small molecule acid vitamin C (Vc) as an aqueous electrolyte additive has been selectively identified. The small molecule Vc can adjust the d band center of Zn substrate which fixes the active H+ so that the hydrogen evolution reaction (HER) is restrained. Simultaneously, it could also fine-tune the solvation structure of Zn ions due to the enhanced electrostatics and reduced Pauli repulsion verified by energy decomposition analysis (EDA). Hence, the cell retains an ultra-long cycle performance of over 1300 cycles and a superior Coulombic efficiency (CE) of 99.5 %. The prepared full cells display increased rate capability, cycle lifetime, and self-discharge suppression. Our results shed light on the mechanistic principle of electrolyte additives on the performance improvement of ZIBs, which is anticipated to render a new round of studies.

Integrated Li3VO4 and boron doped carbon microspheres with high tap density for high-rate and durable lithium storage

As an essential representative of novel anode materials with high capacity and safe voltage, Li3VO4 (LVO) still suffers from the challenges of low electronic conductivity and low tap density of nanostructures. Herein, a strategy of nanoization and recombination is proposed to synthesize the integrated LVO and boron doped carbon microspheres (LVO/BC-MS-550) with high tap density via a chemical crosslink method to improve the Li-ion storage performance. LVO/BC-MS-550 is consisted of the well-dispersed LVO nano-crystals in tightly stacked carbon spheres derived from the cross-linked network of boric acid (BA) and polyvinyl alcohol (PVA). By introducing conductive and continuous carbon framework, the LVO crystals are controlled to grow in the confined region with mitigated volume changes, as well as the enhanced electronic conductivity. Benefiting from the constructive advantages, LVO/BC-MS-550 anode delivers a specific capacity of 512.1 mAh g−1 at the current density of 0.2 A g−1 (0.34 C) after 300 cycles, and ultra-long cycling performance of 231.8 mAh g−1 over 5000 cycles at the charging/discharging current density of 4/2 A g−1, exhibiting rapid pseudo-capacitance reaction kinetics. This work provides valuable insights into the fabrication of in situ three-dimensional crosslinked carbon and LVO composites for alternative grid-scale electrochemical applications.

A High-Voltage Cathode Material with Ultralong Cycle Performance for Sodium-Ion Batteries.

Vanadium-based polyanionic materials are promising electrode materials for sodium-ion batteries (SIBs) due to their outstanding advantages such as high voltage, acceptable specific capacity, excellent structural reversibility, good thermal stability, etc. Polyanionic compounds, moreover, can exhibit excellent multiplicity performance as well as good cycling stability after well-designed carbon covering and bulk-phase doping and thus have attracted the attention of multiple researchers in recent years. In this paper, after the modification of carbon capping and bulk-phase nitrogen doping, compared to pristine Na3 V2 (PO4 )3 , the well optimized Na3 V(PO3 )3 N/C possesses improved electromagnetic induction strength and structural stability, therefore exhibits exceptional cycling capability of 96.11% after 500 cycles at 2C (1C=80mAg-1 ) with an elevated voltage platform of 4V (vs Na+ /Na). Meanwhile, the designed Na3 V(PO3 )3 N/C possesses an exceptionally low volume change of ≈0.12% during cycling, demonstrating its quasi-zero strain property, ensuring an impressive capacity retention of 70.26% after 10,000 cycles at 2C. This work provides a facial and cost-effective synthesis method to obtain stable vanadium-based phosphate materials and highlights the enhanced electrochemical properties through the strategy of carbon rapping and bulk-phase nitrogen doping.

Three-dimensional Ordered Macroporous Flexible Electrode Design toward High-Performance Zinc-Ion Batteries.

Flexible zinc-ion batteries (ZIBs) have been considered to have huge potential in portable and wearable electronics due to their high safety, cost efficiency, and considerable energy density. Therein, the design and construction of flexible electrodes significantly determine the performance and lifespan of flexible battery devices. In this work, an ultrathin flexible three-dimensional ordered macroporous (3DOM) Sn@Zn anode (60 μm in thickness) is presented to relieve dendrite growth and expand the lifespan of flexible ZIBs. The 3DOM structure can ensure uniform electric field distribution, guide oriented zinc plating/stripping, and extend the lifespan of anodes. The rich zincophilic Sn sites on the electrode surface significantly facilitate Zn nucleation. Accordingly, a lowered nucleation overpotential of 8.9 mV and an ultralong cycling performance of 2400 h at 0.1 mA cm-2 and 0.1 mAh cm-2 are achieved in symmetric cells, and the 3DOM Sn@Zn anode can also operate in deep cycling for over 200 h at 10 mA cm-2 and 5 mAh cm-2. A flexible 3DOM MnO2/Ni cathode with a high structural stability and a high mass-specific capacity is fabricated to match with the anode to form a flexible ZIB with a total thickness of 200 μm. The flexible device delivers a high volumetric energy density of 11.76 mWh cm-3 at 100 mA gMnO2-1 and a high average open-circuit voltage of 1.5 V and exhibits high-performance power supply under deformation in practical application scenarios. This work may shed some light on the design and fabrication of flexible energy-storage devices.

Flexible Self-Supporting MOF-Based Bean Pod Cube Hollow Nanofibers for Ultralong Cycling and High Rate Na Storage.

Sodium-ion batteries (SIBs) have garnered significant attention due to their potential as an emerging energy storage solution. Tin sulfide (SnS) has emerged as a promising anode material for SIBs due to its impressive theoretical specific capacity of 1022 mA h g-1 and excellent electrical conductivity. However, its practical application has been hindered by issues such as large volume expansion, which adversely affects cycling stability and rate performance during the charge/discharge processes. In this study, a novel approach to address these issues by synthesizing the bean pod cube hollow metal-organic framework (MOF)-SnSx/NC@N-doped carbon nanofibers through a process involving electrospinning, PDA coating, and calcination. The Sn-MOF serves as a self-sacrificing template, facilitating the simultaneous dissociation of MOF and polymerization of dopamine, leading to the creation of hollow intermediates that retain tin components. Subsequent sulfidation results in the integration of the hollow MOF-SnSx/NC nanoparticles within 3D nitrogen-doped carbon nanofibers, forming the distinctive bean pod cube composite structure. This unique configuration effectively shortens the diffusion path and mitigates volume expansion for sodium ions, ultimately yielding an exceptional high rate performance of 130 mA h g-1 (10 A g-1) and an ultralong cycling performance of 328 mA h g-1 even after 3500 cycles (2 A g-1) as the anode for SIBs.

Controllable sulfur redox multi-pathway reactions regulated by metal-free electrocatalysts anchored with LiS3* radicals

Regulating sulfur redox kinetics is an effective strategy for addressing the critical issues in lithium-sulfur batteries and improving their comprehensive performance. However, the sluggish and complex sulfur reduction reaction (SRR) kinetics can seriously deteriorate the electrochemical performance of lithium-sulfur batteries, hindering a clear comprehension of the electrocatalytic mechanism and presenting challenges for targeted design. Hence, it is crucial to elucidate the SRR mechanism and further refine the catalytic principle. In this study, the SRR mechanism and the pivotal role of radicals are comprehensively explored using ultrathin nitrogen-oxygen co-doped carbon nanosheets (UN/O-CNS) as an electrocatalytic model, combining density functional theory calculations with experimental techniques, such as X-ray absorption near-edge structure spectroscopy. The abundant N-O active sites of UN/O-CNS can synergistically anchor LiS3* radicals, facilitating efficient multi-pathway sulfur conversion. Additionally, UN/O-CNS can capture and catalyze polysulfides while also bi-directionally catalyzing Li2S. The S@UN/O-CNS cells ultimately demonstrate ultra-long cycling performance and high load capacity. The successful operation in pouch cells validates the practical effectiveness of UN/O-CNS. Overall, this study offers novel insights into the complexity and potential pathways of sulfur redox reaction, providing new perspectives for exploring the catalytic mechanism of cost-effective metal-free electrocatalysts.

Triethanolamine-modified binder with synergistic effects on Zn anode in improving the cycling stability of aqueous rechargeable Zn[sbnd]Ni batteries

Aqueous rechargeable ZnNi batteries (ARZNBs) have been broadly considered as beyond-lithium energy-storage devices owing to their safety and potentially high energy density. However, the current practical ARZNBs suffer from short-circuit attack led by inherent problem of zinc anodes. Among the optimization methods of Zn anodes, proper binder engineering of anode is a facile and competitive solution, which is potentially needed to confront the problem of Zn dendrite, poor zinc reversibility, and the difficulties in enlargement for practical production. Herein, Zn anode is fabricated by simply mixing the triethanolamine (TEA) with traditional binder glue via aqueous processing. Specifically, it is composed of the commercial available chemical additive, triethanolamine (TEA), exploiting polyvinyl alcohol (PVA) substrate and potassium polyacrylate (PAAK) additive to retain water and help dissolve PVA. While the TEA helps to achieve the better dispersing and wetting properties of slurry, together with the stable interface structure and better electrolyte tolerance of anode. Notably, the leveling effect of TEA on anode is proved in this strategy, which is beyond the traditional approaches of adding additives to electrolyte. As a result, the scale-up large-area ZnNi pouch battery (∼3 Ah) prepared using this composite binder delivers ultra-long and stable galvanostatic cycling performance (∼1.3 V, >450 cycles and 1200 h) and superior energy efficiency compared to the benchmark of traditional anode, with considerable cyclic discharge loading (∼753 mA g−1Zn and ∼75 mA cm−2). The TEA-modified binder with synergistic effects on Zn anode offers a promising avenue to build low-cost and high-performance ARZNBs.

3D network-structured CoSb/P-CNFs@rGO as a highly conductive self-supporting anode material for lithium-ion batteries

CoSb particles have an extremely high specific capacity as anodes for Li-ion batteries, but the severe expansion during the reaction process makes their cycle stability very poor. In this study, a 3D CoSb/P-CNFs@rGO network structure has been successfully constructed by a simple electrospinning technique and hydrothermal treatment. 1D carbon nanofibers and 2D reduced graphene oxide network are intertwined and coated to create this 3D structure. In this ingenious strategy, CoSb particles are embedded in carbon nanofibers to restrain volume expansion. By encapsulating the nanoparticles in a graphene structural network, it is possible to stabilize the matrix structure and precipitate CoSb particles for secondary capture. In addition, the 3D network structure also builds a fast channel for 3D interaction electron/ion transfer. Benefiting from the above structural advantages, the CoSb/P-CNFs@rGO flexible self-supporting anode exhibits excellent electrochemical performance, including ultra-long cycling performance (870 mA h g−1 after 2000 cycles at a current density of 500 mA g−1). More importantly, the 3D structure design method may provide a simple and effective strategy to overcome the volume expansion of anode materials.

Electrochemistry-Driven Interphase Doubly Protects Graphite Cathodes for Ultralong Life and Fast Charge of Dual-Ion Batteries.

Dual-ion batteries (DIBs) with graphite as cathode material, show superiority in terms of sustainability, affordability, and environmental impact over Li-ion batteries that rely on transition-metal based cathodes. However, graphite cathodes severely suffer from poor structural stability during anion storage at high potentials because of the co-intercalation and oxidative decomposition of electrolytes. This work presents an in situ electrochemistry-driven route to create a bifunctional interphase through implantation of diethylenetriaminepenta(methylene-phosphonic acid) (DTPMP) on the surface of graphite particles. The reaction mechanisms and functions of DTPMP are investigated both experimentally and theoretically. The DTPMP-derived interphase not only improves the antioxidative stability of electrolytes but also benefits the desolvation of PF6 - anions, which doubly protect the graphitic structure and give rise to fast-charge and ultralong cycling performance of graphite cathodes in DIBs.

Anion Receptor Enhanced Li Ion Transportation for High-Performance Lithium Metal Batteries.

High-potential lithium metal batteries (LMBs) are still facing many challenges, such as the growth of lithium (Li) dendrites and resultant safety hazards, low-rate capabilities, etc. To this end, electrolyte engineering is believed to be a feasible strategy and interests many researchers. In this work, a novel gel polymer electrolyte membrane, which is composed of polyethyleneimine (PEI)/poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) cross-linked membrane and electrolyte (PPCM GPE), is prepared successfully. Due to the fact that the amine groups on PEI molecular chains can provide the rich anion receptors and strongly pin the anions of electrolytes and thus confine the movement of anions, our designed PPCM GPE owns a high Li+ transference number (0.70) and finally contributes to the uniform Li+ deposition and inhibits the growth of Li dendrites. In addition, the cells with PPCM GPE as a separator behave the impressive electrochemical performances, i.e., a low overpotential and an ultralong and stable cycling performance in Li∥Li cells, a low overvoltage of about 34 mV after a stable cycling for 400 h even at a high current density of 5 mA/cm2, and, in Li∥LFP full batteries, a specific capacity of 78 mAh/g after 250 cycles at a 5 C rate. These excellent results suggest a potential application of our PPCM GPE in developing high-energy-density LMBs.

Insights into the storage mechanism of freestanding MoTe2/C nanofibers as binder-free anodes for high-performance sodium-ion batteries

Developing flexible and binder-free electrodes with superior electrochemical performance is the critical key for flexible electronics and wearable devices. MoTe2, a typical two-dimensional (2D) layered material, has emerged as an attractive anode material for sodium ion batteries (SIBs) because its abundant active sites and rapid Na+ transfer and storage. In this work, a series of flexible MoTe2/C nanofibers (NFs) are successfully synthesized via a facile electrospinning process with tellurization treatment. As binder and current collector-free anodes, the optimized MoTe2/C-600 shows significantly enhanced Na+ storage performance, which delivers a high reversible capacity of 294 mAh g−1 after 100 cycles at 0.1 A g−1 and an ultra-long time cycling performance of 5000 cycles at 1.0 A g−1. The as-prepared MoTe2/C NFs possess double merits of well 1D conductive paths and 3D ion diffusion channels, which effectively boost the electron/Na+ transfer. Meanwhile, its excellent flexibility and mechanical strength greatly enhance the cycling stability. More importantly, in-situ X-ray diffraction and ex-situ transmission electron microscope were employed to demonstrate its structure evolution, revealing that the high capacity of MoTe2/C-600 results from the cooperation of Na+ intercalation and conversion reaction. The findings of this study provide a better understanding on the sodium storage mechanism of MoTe2-based flexible electrodes.

Conjugated microporous polyimide cathodes for sodium/lithium-ion batteries with ultra-long cycling performance

Conjugated microporous polyimides (CMPs) have been emerging as the promising electrode materials for sodium-ion batteries (SIBs) and lithium-ion batteries (LIBs) owing to their low cost, tunable structures, environmental benefit, and high porosity. However, the low intrinsic conductivity, poor structural stability and sluggish diffusion kinetics have hindered their further applications. Herein, a novel conjugated microporous polyimide trapped by multi-walled carbon nanotubes (TAPBA-NTCDA@MWCNTs) as cathodes for SIBs/LIBs have been prepared by in situ polycondensation. The addition of MWCNTs profits greatly in conductivity and structural stability of electrode materials. Consequently, when explored as cathode materials for SIBs, TAPBA-NTCDA@MWCNTs exhibits the good reversible specific capacity, predominant rate capability and ultra-long cycling stability. Moreover, the reaction mechanism and outstanding reversibility are investigated by the detailed ex-situ XPS/FT-IR/SEM analysis. Finally, the cathode also delivers an excellent lithium storage performance. In view of the outstanding cycle stability and such simple synthetic route, this work perhaps provides an effective strategy to fabricate high-performance conjugated microporous polyimide-based cathodes for energy storage and conversion devices.

Synergistic realization of Co/N co-doped hierarchical vanadium trioxide core–shell sphere for ultra-long cycle performance of Li–S batteries

Lithium–sulfur (Li–S) battery has been recognized as one of the most promising energy systems due to its high specific capacity and energy density. However, its instinct defects, such as shuttle effect of lithium polysulfide (LPS), low conductivity, and high volume expansion of cathode sulfur (S), seriously hinder its commercialization process. Herein, a hierarchical vanadium trioxide (V2O3) core–shell sphere, which is self-assembled from zero-dimensional (0D) nanoparticles and integrated with 2D nanosheets and co-doped cobalt (Co) and nitrogen (N), has been prepared. After the hierarchical V2O3 core–shell sphere being served as a separator modifier, a synergistic effect of physisorption, chemisorption, and catalytic conversion of LPS can be well realized, leading to an effective inhibition of the shuttle effect. Hence, exceptional initial discharging capacities of 1485.3 and 1322.2 mAh g−1 can be obtained at 0.1 and 1C, respectively, and after 1100 ultra-long cycles, the capacity loss rate can be restricted at 0.064% per cycle; furthermore, a discharging capacity of 973.9 mAh g−1 can also be obtained even at a high current of 3C, and the capacity loss rate is only 0.059% per cycle during 1000 ultra-long cycles, showing extraordinary ultra-long cycle performance and rate performance.

In situ three-dimensional cross-linked carbon nanotube-interspersed SnSb@CNF as freestanding anode for long-term cycling sodium-ion batteries

Alloying-based material has achieved tremendous appealing being anode used in sodium‑ion batteries (SIBs) by virtue of its relatively giant sodium storage specific capacity along with low discharge platforms. Nevertheless, the sluggish ion transmission dynamics and the huge volume change during cycling induced irreparable particle pulverization and agglomeration result in collapse of electrode structure and deterioration of cycling properties. In this work, three-dimensional cross-linked carbon nanotube-interspersed SnSb@CNF integrated structure (SnSb@CNF/CNT) is designed and synthesized. In this ingenious nanostructure, CNTs interspersed between CNF frames play the role of electron transport and diffusion “bridges” for enhancing the electrical conductivity of anode materials and relieve aggregation of SnSb alloy particles, the N doped-CNFs serve as external frame could efficiently mitigate dramatic volume effect to maintain system integrity. Based on these constructive advantages, the elastic conductive system can be directly available as anode for SIBs, showing ultralong cycling performance of 210 mAh g−1 over 700 sodiation/desodiation processes with a current density of 0.5 A g−1, even 161 mAh g−1 following 1000 cycling under a high current density of 1 A g−1 accompanied by an almost 100% superb capacity retention ratio, as well as distinguished high rate performance (470 mAh g−1 with a returned current density of 0.05 A g−1). This work shed distinctive insight to construct in situ three-dimensional cross-linked freestanding alloying-based anode materials used in alternative electrochemical grid-scale application.

Defective Bi2S3 Anchored on CuS/C as an Ultrafast and Long-Life Anode for Sodium-Ion Storage.

Due to the high electrical conductivity and abundant redox active sites, bimetal sulfides are highly competitive anode materials for sodium storage with long-life and high-rate. Herein, a heterostructured metal sulfide (Bi2S3-CuS) with a carbon-based support is prepared by calcination and ion exchange methods. The synergistic effects of the heterostructure and defective structure provide facile diffusion channels, fast Na+ migration, and plentiful active sites for Na+, which reflect in the impressive electrochemical performance with a high reversible capacity of 592.2 mA h g-1 after 1000 cycles at 8 A g-1. Furthermore, the Na-ion full batteries exhibit an ultra-long cycling performance with a value of 216 mA h g-1 after 4000 cycles at 10 A g-1. Interestingly, the defective structure of Bi2S3 remains after cycling. Kinetic analyses and density functional theoretical calculations clarified that the heterointerfacial structure, especially on the interface containing sulfur defects in Bi2S3 of Bi2S3-CuS, could induce feasible ion adsorption and promote ion transfer, which lays the foundation for achieving ultrafast sodiation kinetics.

Thiol-ene crosslinked cellulose-based gel polymer electrolyte with good structural integrity for high cycling performance lithium-metal battery

Gel polymer electrolytes (GPEs) are considered to be one most promising alternative to liquid electrolytes due to their suitability for creating safe and durable solid-state lithium-metal batteries. However, the mechanical properties of GPEs usually deteriorate dramatically when polymer matrices are plasticized by a liquid electrolyte, which leads to significant loss of battery performance. Therefore, the long-term structural integrity and good mechanical strength are critical characteristics of GPEs designed for high-performance batteries. Here, an ecologically compatible cellulose-based GPE with a crosslinked structure is synthesized via a facile and effective thiol-ene click chemistry method. The prepared thiol-ene crosslinked GPE possesses enhanced mechanical strength (10.95 MPa) and rigid structure, which enabled us to fabricate LiFePO4|Li batteries with ultra-long cycling performance. The capacity retention of the crosslinked cellulose-based GPE can be up to 84% at 0.5 C, even after 350 cycles, which is considerably higher than that of non-crosslinked GPE for which rapid decline in capacity occurs after 200 cycles. In addition, a GPE preparation method described in this work compares favorably well with existing commercial electrolytes for lithium metal batteries.

Self-assembled MoTe2 hierarchical nanoflowers with carbon coating as anode material for excellent sodium storage performance

Developing a suitable anode material for rapid sodium ion transfer and storage is a common challenge for application of sodium ion batteries (SIBs). As a typical two-dimensional (2D) layered material, some potential advantages can be discovered from MoTe2 such as unique structural feature, abundant active sites and rapid Na+ intercalation/de-intercalation. However, the stacking of layers, collapse of structure and large volume expansion still affect the Na+ storage performance of MoTe2 anode material. In this work, we report a nanoflower like MoTe2/C as an excellent anode material for SIBs, which is synthesized via a simple method containing chelation, preoxidation and tellurization from Mo-PDA, MoOx/C to MoTe2/C. Through controlling the reasonable tellurization temperatures and suitable mass proportion between Mo raw material and dopamine hydrochloride, the best performance of MoTe2/C-600 can be obtained, which shows a higher initial capacity of 580 mAh/g and 250 mAh/g after 100 cycles at 0.1A/g compared with other tested samples. Besides, MoTe2/C-600 delivers an ultra-long time cycling performance of 3000 cycles and the capacity still retains 190 mAh/g at 1.0 A/g. After assembled with Na3V2(PO4)3 (NVP), a full-cell retains 109 mAh/g after 50 cycles at 0.1A/g. The 3D connected network between petals of flower like MoTe2/C can effectively suppress the volume expansion or pulverization to the boost the Na+ storage performance. This work offers new clues to construct MoTe2-based composites with unique and robust nanostructures for electrochemical energy-storage application.

Ultrafast sodium-ion storage in an interconnected Ni/Ni3S2 nanocomposite with long-term cycling performance

Nickel sulfide (Ni3S2) is a potential anode candidate for sodium-ion batteries due to its abundance, stable structure, and low price. However, its rate and cycling performance require improvement for practical applications. This paper reports the facile synthesis of a unique composite consisting of an interconnected nickel/nickel sulfide nanocomposite (Ni/Ni3S2) by heating a mixture of nickel nanopowder and sulfur. The interconnected nanostructured backbone of the nickel nanoparticles facilitates continuous electron pathways in the composite, while the embedded nanosized nickel sulfide domain reduces the diffusion length and improves reaction kinetics. The Ni/Ni3S2 electrode exhibits excellent rate performance in dimethyl ether (DME) electrolyte, with a current density of 80 A g−1 and capacity of 151 mA h g−1; it also exhibits stable, ultralong cycling performance. Synergism between the unique nanostructure of the composite and the low-viscosity DME electrolyte may be responsible for the extraordinary cycling and rate performance. A full cell with a Na3V2(PO4)3 (NVP) electrode delivers a capacity of 111 mA h g−1 at 100 A g−1; moreover, the Ni/Ni3S2–NVP full cell retains 55% of its capacity after 5000 cycles at 20 A g−1. The developed strategy, which uses a conductive metal-nanoparticle/metal-sulfide nanocomposite, is applicable to other systems and is scalable for practical applications.