Amorphous MoS3-modified porous Co4S3-embedded N,S co-doped carbon polyhedron as new high-capacity and high-rate anode materials for sodium-ion half/full cells

Bimetallic sulfide Fe5Ni4S8 nanoparticles modified N/S co-doped carbon nanofibers as anode materials for high-performance sodium-ion batteries

Transition metal sulfides (TMSs) have garnered significant attention owing to high theoretical capacities, favorable environmental compatibility, abundant natural resources, and suitable discharge/charge voltage platform in the field of anode materials for sodium-ion batteries (SIBs). However, the sluggish reaction rates and significant volume alteration during the process of sodiation/desodiation restrict the practical application of TMSs for SIBs. Herein, a novel bimetallic sulfide Fe5Ni4S8 nanoparticles modified nitrogen/sulfur co-doped carbon nanofibers (NSCFs) composite is successfully synthesized using a straightforward electrostatic spinning and sulfurization treatment. As an anode material for SIBs, Fe5Ni4S8/NSCFs exhibits a high reversible specific capacity of 686.34 mAh g-1 at 0.1 A/g and a capacity of 607.26 mAh g-1 after 120 cycles at 1.0 A/g with a capacity retention rate of 96.9 %. Even at 10.0 A/g, it still maintains a capacity of 481.14 mAh g-1 after 800 cycles, indicating an excellent electrochemical energy storage performance. Density functional theory calculations demonstrate that the Fe5Ni4S8 exhibits enhanced binding with NSCFs, promoted electron transfers, improved Na+ adsorption ability, and decreased Na+ diffusion barrier energy compared to those of monometallic sulfide FeS. Additionally, the three-dimensional network skeleton of NSCFs can effectively enhance the electrical conductivity and relieve the volume change during the discharge and charge process. The innovative multicomponent design and nanostructural configuration provide a promising strategy to develop high-performance anode materials based on bimetallic sulfide for SIBs.

Heterointerface magic: How FeS2/NiS2@NC nanoparticles transform sodium-ion battery anode performance

Transition metal sulfides (TMS) are acknowledged as potential anode materials for sodium ion batteries (SIBs); however, their practical application is significantly hindered by suboptimal cycling durability and inadequate rate performance, primarily stemming from limited electronic conductivity and substantial volume swelling during the sodiation/desodiation process. Constructing heterojunction incorporating multiple active components has been emerged as an effective strategy to mitigate these limitations. In this study, high lattice matching FeS2/NiS2 heterojunction nanoparticles anchored on a carbon skeleton (FeS2/NiS2@NC) were synthesized by a facile high-temperature pyrolysis and sulfidation process. The combination of experimental characteristics and theoretical simulations confirms that this unique heterojunction, characterized by an electric field at the interface, offers an adjustable electronic structure and strong Na+ adsorption energy, thus expediting Na+ diffusion kinetics. Consequently, the FeS2/NiS2@NC electrode demonstrates superior rate capabilities (491.2 mAh/g at 10.0 A/g) and enhanced cycling stability (490.8 and 274.7 mAh/g at 10.0 and 20.0 A/g over 5000 cycles) when employed as anode in SIBs. This research underscores the pivotal role of the heterointerface engineering in enhancing rechargeable battery performance and presents a promising avenue for optimizing the electrochemical properties of TMS.

Optimizing sodium storage and durability in metal sulfide anodes with a 3D graphene architecture

Transition metal chalcogenides (TMCs) with a high theoretical capacity are regarded as promising anodes for sodium-ion batteries (SIBs) but encounter several challenges because of the complex conversion process, which leads to numerous side reactions and the inevitable disintegration of active materials, thereby impeding their practical application. In this work, inspired by a three-dimensional (3D) structure design, stable 3D reduced graphene oxide with heteroatom-site coordinated carbon centers (3DNSrGO) is fabricated, which features uniform and abundant nickel sulfide (NiS) particles within the empty spaces, along with sufficient access to the liquid electrolyte, thereby enabling more efficient transfer of sodium ions. Nevertheless, the NiS/3DNSrGO electrode still suffers from unexpected cycling instability and failure issues because of the short-circuiting, resulting from sodium (Na) metal corrosion and the deterioration of the glass fiber (GF) separator. The issue of short cycle life is significantly mitigated at the cell configuration level (inclusion of the polypropylene membrane) by lowering the risks of Na-metal corrosion and protecting the GF membrane. This study holds considerable potential for addressing (1) the growing requirement for efficient and sustainable Na+ host materials and (2) a newfangled approach that optimizes the long-term cycling stability of SIBs via a better cell configuration.

Amorphous/Crystalline Heterostructured Nanomaterials: An Emerging Platform for Electrochemical Energy Storage

With the expanding adoption of large-scale energy storage systems and electrical devices, batteries and supercapacitors are encountering growing demands and challenges related to their energy storage capability. Amorphous/crystalline heterostructured nanomaterials (AC-HNMs) have emerged as promising electrode materials to address these needs. AC-HNMs leverage synergistic interactions between their amorphous and crystalline phases, along with abundant interface effects, which enhance capacity output and accelerate mass and charge transfer dynamics in electrochemical energy storage (EES) devices. Motivated by these elements, this review provides a comprehensive overview of synthesis strategies and advanced EES applications explored in current research on AC-HNMs. It begins with a summary of various synthesis strategies of AC-HNMs. Diverse EES devices of AC-HNMs, such as metal-ion batteries, metal-air batteries, lithium-sulfur batteries, and supercapacitors, are thoroughly elucidated, with particular focus on the underlying structure-activity relationship among amorphous/crystalline heterostructure, electrochemical performance, and mechanism. Finally, challenges and perspectives for AC-HNMs are proposed to offer insights that may guide their continued development and optimization.

Multiple Heterointerfaces and Heterostructure Engineering in MXene@Co-P-S Hybrids Promote High-Performance Sodium-Ion Half/Full Batteries

In this paper, heterogeneous cobalt phosphosulfide (Co4S3/Co2P) nanocrystals anchoring on few-layered MXene nanosheets (MXene@Co4S3/Co2P) were prepared by in situ growth and the subsequent high-temperature phosphorization/sulfidation processes. Thanks to the synergistic effect and the abundant phase interfaces of Co4S3, Co2P, and MXene, the electron transfer and Na+ diffusion processes were greatly accelerated. Meanwhile, the high electrical conductivity of MXene nanosheets and the heterogeneous structure of Co4S3/Co2P effectively avoided the MXene restacking and the agglomeration of phosphosulfide particles, thus mitigating volumetric expansion during charging and discharging. The results show that the MXene@Co4S3/Co2P heterostructure presents good rate capability (251.08 mAh g-1 at 1 A g-1) and excellent cycling stability (198.69 mAh g-1 after 407 cycles at 5 A g-1). Finally, the storage mechanism of Na+ in the heterostructure and the multistep phase transition reaction were determined by ex situ X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS) analyses. This study provides a new perspective on the formation of metal phosphosulfide and MXene hybrids with multiple heterointerfaces as well as demonstrates MXene@Co4S3/Co2P composites as the promising anode material in sodium-ion batteries.

Achieving High-Rate and Stable Sodium-Ion Storage by Constructing Okra-Like NiS2/FeS2@Multichannel Carbon Nanofibers

Transition metal sulfides (TMSs) are considered as promising anode materials for sodium-ion batteries (SIBs) due to their high theoretical capacities. However, the relatively low electrical conductivity, large volume variation, and easy aggregation/pulverization of active materials seriously hinder their practical application. Herein, okra-like NiS2/FeS2 particles encapsulated in multichannel N-doped carbon nanofibers (NiS2/FeS2@MCNFs) are fabricated by a coprecipitation, electrospinning, and carbonization/sulfurization strategy. The combined advantages arising from the hollow multichannel structure in carbon skeleton and heterogeneous NiS2/FeS2 particles with rich interfaces can provide facile ion/electron transfer paths, ensure boosted reaction kinetics, and help maintain the structural integrity, thereby resulting in a high reversible capacity (457 mA h g-1 at 1 A g-1), excellent rate performance (350 mA h g-1 at 5 A g-1), and outstanding long-term cycling stability (93.5% retention after 1100 cycles). This work provides a facile and efficient synthetic strategy to develop TMS-based heterostructured anode materials with high-rate and stable sodium storage properties.