Leaf-inspired design of mesoporous Sb_2S_3/N-doped Ti_3C_2T_x composite towards fast sodium storage

Owing to excellent conductivity and abundant surface terminals,MXene-based heterostructures have been intensively investigated as energy storage materials.However,elaborate design of the structure and composition of MXene-based hybrids towards superior electrochemical performance is still challenging.Herein,we present an ingenious leaf-inspired design for preparing a unique Sb_2S_3/nitrogen-doped Ti_3C_2T_x MXene (L-Sb_2S_3/Ti_3C_2) hybrid.In-situ TEM observations reveal that the leaflike Sb_2S_3 nanoparticles with numerous mesopores can well relieve the large volume changes via an inward pore filling mechanism with only 20%outward expansion,whereas highly conductive N-doped Ti_3C_2T_x nanosheets can serve as the robust mechanical support to reinforce the structural integrity of the hybrid.Benefiting from the structural and constituent merits,the L-Sb_2S_3/Ti_3C_2anode fabricated exhibits a fast sodium storage behavior in terms of outstanding rate capability (339.5 mA h g~(-1)at 2,000 mA g~(-1)) and high reversible capacity at high current density (358.2 mA h g~(-1)at 1,000 mA g~(-1)after 100 cycles).Electrochemical kinetic tests and theoretical simulation further manifest that the boosted electrochemical performance mainly arises from such a unique leaf-like Sb_2S_3 mesoporous nanostructure with abundant active sites,and enhanced Na~+ adsorption energy on the heterojunction formed between Sb_2S_3 nanoparticles and Ti_3C_2 matrix.     

Green Ether Electrolytes for Sustainable High-voltage Potassium Ion Batteries

Ether-based electrolytes are promising for secondary batteries due to their good compatibility with alkali metal anodes and high ionic conductivity. However, they suffer from poor oxidative stability and high toxicity, leading to severe electrolyte decomposition at high voltage and biosafety/environmental concerns when electrolyte leakage occurs. Here, we report a green ether solvent through a rational design of carbon-chain regulation to elicit steric hindrance, such a structure significantly reducing the solvent‘s biotoxicity and tuning the solvation structure of electrolytes. Notably, our solvent design is versatile, and an anion-dominated solvation structure is favored, facilitating a stable interphase formation on both the anode and cathode in potassium-ion batteries. Remarkably, the green ether-based electrolyte demonstrates excellent compatibility with K metal and graphite anode and a 4.2 V high-voltage cathode (200 cycles with average Coulombic efficiency of 99.64 %). This work points to a promising path toward the molecular design of green ether-based electrolytes for practical high-voltage potassium-ion batteries and other rechargeable batteries.     

SnS2/graphene nanocomposite: A high rate anode material for lithium ion battery

In this work,via a facile solvothermal route,we synthesized an anode material for lithium ion batteries(LIBs)—SnS_2 nanoparticle/graphene(SnS_2 NP/GNs) nanocomposite.The nanocomposite consists of SnS_2nanoparticles with an average diameter of 4 nm and graphene nanosheets without restacking.The SnS_2 nanoparticles are firmly anchored on the graphene nanosheets.As an anode material for LIBs,the nanocomposite exhibits good Li storage performance especially high rate performance.At the high current rate of 5,10,and 20 A/g,the nanocomposite delivered high capacities of 525,443,and 378 mAh/g,respectively.The good conductivity of the graphene nanosheets and the small particle size of SnS_2contribute to the electrochemical performance of SnS_2 NP/GNs.     

Large-scale Ni-MOF derived Ni_3S_2 nanocrystals embedded in N-doped porous carbon nanoparticles for high-rate Na~+ storage

Metal organic framework(MOF) has been confirmed as the promising precursor to develop the conve rsion-typed anode mate rials of sodium-ion batteries(SIBs) because of the tunable structure design and simple functional modification.Here,we prepare the ultrasmall Ni_3S_2 nanocrystals embedded into N-doped porous carbon nanoparticles using the scalable Ni-MOF as precursor(denoted as Ni_3S_2@NPC).The ultrasmall size of Ni_3S_2 can work for accelerated electro n/ion transfer to facilitate the electrochemical reaction kinetics.Moreover,the robust conductivity network originated from N-doped porous carbon nanoparticles can not only improve the electron conductivity,but also enhance the electrode integrity and stability of the electrode/electrolyte interface.In addition,the N heteroatoms provide extra Na storage sites.Accordingly,the electrode delivers the obviously competitive capacities and high-power output with respect to the currently reported Ni_3S_2/C composites.This study provides a scalable and universal strategy to develop the advanced transition metal sulfides for practically feasible SIBs.     

Highly Rechargeable Lithium-CO2 Batteries with a Boron- and Nitrogen-Codoped Holey-Graphene Cathode

Metal-air batteries, especially Li-air batteries, have attracted significant research attention in the past decade. However, the electrochemical reactions between CO₂ (0.04 % in ambient air) with Li anode may lead to the irreversible formation of insulating Li₂CO₃, making the battery less rechargeable. To make the Li-CO₂ batteries usable under ambient conditions, it is critical to develop highly efficient catalysts for the CO₂ reduction and evolution reactions and investigate the electrochemical behavior of Li-CO₂ batteries. Here, we demonstrate a rechargeable Li-CO₂ battery with a high reversibility by using B,N-codoped holey graphene as a highly efficient catalyst for CO₂ reduction and evolution reactions. Benefiting from the unique porous holey nanostructure and high catalytic activity of the cathode, the as-prepared Li-CO₂ batteries exhibit high reversibility, low polarization, excellent rate performance, and superior long-term cycling stability over 200 cycles at a high current density of 1.0 A g⁻¹. Our results open up new possibilities for the development of long-term Li-air batteries reusable under ambient conditions, and the utilization and storage of CO₂.     

Porous surfur-doped hard carbon for excellent potassium storage

Hard carbon is promising anode for potassium-ion batteries(PIBs),however,the poor rate capability hinders its development as potential anode.To address this question,we design a sulfur-doped porous hard carbon(S-HC)for PIBs through the combination of structural design and composition adjustment.The as-designed S-HC exhibits a long cycling life with^191 mAh/g after 300 cycles at 1 A/g,and an excellent rate capability with^100 mAh/g at 5 A/g,which was attributed to its structural characteristics and compositions.The S-HC demonstrates to be promising anode in the future.     

An organometallic approach for ultrathin SnO(x)Fe(y)S(z) plates and their graphene composites as stable anode materials for high performance lithium ion batteries

Through an organometallic approach, ultrathin SnO(x)Fe(y)S(z) plates with ~2 nm single layer-thicknesses were obtained and their graphene composites showed very promising discharge capacities of up to 736 mA h g(-1) and excellent stabilities as anode materials in lithium ion batteries.     

Flower-like Spherical α-Ni(OH)2 Derived NiP2 as Superior Anode Material of Sodium-Ion Batteries

Transition metal phosphides (TMPs) are promising anode candidates for sodium-ion batteries, due to their high theoretical specific capacity and working potential. However, the low conductivity and excessive volume variation of TMPs during insertion/extraction of sodium ions result in a poor rate performance and long-term cycling stability, largely limiting their practical application. In this paper, NiP₂ nanoparticles encapsulated in three-dimensional graphene (NiP₂@rGO) were obtained from the flower-like spherical α-Ni(OH)₂ by phosphating and carbon encapsulation processes. When used as a sodium-ion batteries anode material, the NiP₂@rGO composite shows an excellent cycling performance (117 mA h g⁻¹ at 10 A g⁻¹ after 8000 cycles). The outstanding electrochemical performance of NiP₂@rGO is ascribed to the synergistic effect of the rGO and NiP₂. The rGO wrapped on the NiP₂ nanoparticles build a conductive way, improving ionic and electronic conductivity. The effective combination of NiP₂ nanoparticles with graphene greatly reduces the aggregation and pulverization of NiP₂ nanoparticles during the discharge/charge process. This study may shed light on the construction of high-performance anode materials for sodium-ion batteries and to other electrode materials.     

Understanding High-Rate K+-Solvent Co-Intercalation in Natural Graphite for Potassium-Ion Batteries

Graphite shows great potential as an anode material for rechargeable metal-ion batteries because of its high abundance and low cost. However, the electrochemical performance of graphite anode materials for rechargeable potassium-ion batteries needs to be further improved. Reported herein is a natural graphite with superior rate performance and cycling stability obtained through a unique K⁺-solvent co-intercalation mechanism in a 1 m KCF₃SO₃ diethylene glycol dimethyl ether electrolyte. The co-intercalation mechanism was demonstrated by ex situ Fourier transform infrared spectroscopy and in situ X-ray diffraction. Moreover, the structure of the [K-solvent]⁺ complexes intercalated with the graphite and the conditions for reversible K⁺-solvent co-intercalation into graphite are proposed based on the experimental results and first-principles calculations. This work provides important insights into the design of natural graphite for high-performance rechargeable potassium-ion batteries.     

Recent Progress on Modification Strategies of Alloy-based Anode Materials for Alkali-ion Batteries

Alkali-ion batteries,including lithium-ion batteries(LIBs),sodium-ion batteries(NIBs)and potassium-ion batteries(KIBs),with alloy-based anodes exhibit huge potential in high energy density due to the natural abundance,high theoretical capacity as well as suitable operating voltages.However,the practical application is severely hindered by the huge volume variation based on the alloying mechanism and inferior conductivity,especially for red phosphorus(P)and silicon(Si)anodes,which induces poor rate capability and fast capacity decay.Herein,we will briefly review fundamental advantages and challenges of alloy-based anode materials.Then,effective modification strategies of alloy-based anode materials for boosting the performance would be emphasized and discussed.Finally,we will share our perspectives and some opportunities to obtain high-performance alloy-based anode materials for further application.     

Fe2O3/rGO纳米复合物的制备及其储锂和储钠性能

金属氧化物可通过电化学转换反应与锂离子及钠离子发生多电子可逆结构转换,是一类极具应用前景的高容量锂离子和钠离子电池负极材料。实验以氧化石墨烯和铁盐为前驱体,采用简单的溶剂法,成功将Fe₂O₃纳米单晶粒子均匀负载于石墨烯的导电片层上,获得Fe₂O₃/rGO(还原氧化石墨烯)纳米复合材料。复合电极在锂离子和钠离子电池中都表现出优异的充放电性能和循环稳定性。实验结果表明石墨烯的包覆不仅能降低Fe₂O₃发生转换反应的电荷传递阻抗,而且能够稳定电极在循环过程中带来的结构转变,极大改善电极大电流充放能力和循环稳定性。本研究为发展高容量的锂离子和钠离子电池负极材料提供了可行的途径。     

Graphene-wrapped Ni2P materials: a 3D porous architecture with improved electrochemical performance

Ni₂P/graphene hybrid with a 3D architecture has been successfully accomplished through a series of controlled chemical processes. In contrast to random mixture of Ni₂P nanoparticles and graphene nanosheets, the architecture hybrid exhibits superior electrochemical stability because the Ni₂P nanoparticles are firmly riveted on the graphene sheets. The 3D graphene network enhances the electrical conductivity over the 2D nanostructure. As anode materials for lithium-ion batteries, the graphene-wrapped Ni₂P nanoparticles can deliver a reversible capacity of ~400 mAh g^?1 after 30 cycles with nearly no fading and also exhibit a good rate performance. The graphene network can serve as a conducting network for fast electron transfer from all directions between the active materials and charge collector, and better buffer spaces to accommodate the volume expansion/contraction during discharge/charge process, which can be considered to contribute to the remarkable cyclic stability, thereby pointing to a new synthetic route to hybridizing graphene with active materials for advanced lithium ion batteries.

Rapid Microwave-assisted Hydrothermal Synthesis of Bi_(0.76)Sb_(1.24)S_3 and Its Application in the Photocatalytic Degradation of Pollutants by Visible Light Irradiation

Bi_(0.76)Sb_(1.24)S_3 nanocrystals were synthesized by a rapid microwave-assisted hydrothermal method using bismuth nitrate, antimony pentoxide and thioacetamide as starting materials and characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM) and UV-vis diffuse reflectance spectroscopy(DRS). The effects of the synthetic condition on the product composition were investigated. The photocatalytic activities of Bi_(0.76)Sb_(1.24)S_3 nanocrystals for the degradation of methyl orange and p-hydroxyazobenzene under visible light irradiation were evaluated. Bi_(0.76)Sb_(1.24)S_3 exhibited good and stable visible light photocatalytic activity.     

Cotton-derived oxygen/sulfur co-doped hard carbon as advanced anode material for potassium-ion batteries

Hard carbon is regarded as promising anode materials for potassium-ion batteries(KIBs)owing to their low price and easy availability.However,the limited rate capability still needs to be improved.Herein,we demonstrate the fabrication of oxygen/sulfur co-doped hard carbon through a facile hydrolyzationsulfuration process of skimmed cotton.The simultaneous dopants significantly improve potassium ion diffusion rate.When served as the anode for KIBs,this hydrolyzed hard carbon delivered a high reversible capacity(409 mAh/g at 0.1 A/g),superior rate capability(135 mAh/g at 2 A/g)and excellent cyclability(about 120 mAh/g overt 500 cycles at 2 A/g).This work provides a facile strategy to prepare low-cost doped-hard carbon with superior potassium storage property.     

Free-standing ternary metallic sulphides/Ni/C-nanofiber anodes for high-performance lithium-ion capacitors

As a promising energy-storage device,the hybrid lithium-ion capacitor coupling with both a large energy density battery-type anode and a high power density capacitor-type cathode is attracting great attention.For the sake of improving the energy density of hybrid lithium-ion capacitor,the free-standing anodes with good electrochemical performance are essential.Herein,we design an effective electrospinning strategy to prepare free-standing MnS/Co_4S_3/Ni_3S_2/Ni/C-nanofibers(TMSs/Ni/C-NFs)film and firstly use it as a binder-free anode for hybrid lithium-ion capacitor.We find that the carbon nanofibers can availably prevent MnS/Co_4S_3/Ni_3S_2/Ni nanoparticles from aggregation as well as significantly improve the electrochemical performance.Therefore,the binder-free TMSs/Ni/C-NFs membrane displays an ultrahigh reversible capacity of 1246.9 m Ah g~(-1)at 100 m A g~(-1),excellent rate capability(398 mAh g~(-1) at2000 mA g~(-1)),and long-term cyclic endurance.Besides,we further assemble the hybrid lithium-ion capacitor,which exhibits a high energy density of 182.0 Wh kg~(-1)at 121.1 W kg~(-1)(19.0 Wh kg~(-1) at 3512.5 W kg~(-1))and remarkable cycle life.     

Graphene-encapsulated iron microspheres on the graphene nanosheets

Graphene nanosheets (GNSs) loading graphene-encapsulated iron microspheres (GEIMs) were fabricated by heat treatment of graphene oxide nanosheets (GONs) with ferric trichloride (FeCl(3)). The special pentagon-hexagonal graphene shells have been produced by precipitation of carbon from metal carbide solutions, thanks to the high reactivity of GONs and ferric nanoparticles dispersing homogeneously between graphene layers. The morphology, structure and elemental composition of GEIMs were investigated by scanning electron microscope, X-ray diffraction and electron energy disperse spectroscope, respectively. The formation mechanism of GEIMs was proposed. Hollow graphene microspheres (HGMs) on the GNSs were obtained with the removal of ferric species in GEIMs. When used as the anode materials for lithium-ion batteries, the almost graphitic HGMs exhibit stable voltage platform at ca. 0.2 V, excellent cycle capability and higher reversible capacity of about 440 mAh g(-1) after 50 cycles and possess great potential application in lithium-ion batteries.     

Enhanced anode performances of the Fe3O4-carbon-rGO three dimensional composite in lithium ion batteries

A three dimensional composite was constructed by anchoring Fe(3)O(4) nanoparticles encapsulated within carbon shells onto reduced graphene oxide sheets, which exhibited enhanced anode performances in lithium ion batteries with a specific capacity of 842.7 mAh g(-1) and superior recycle stability after 100 cycles.     

Construction of CoS_2 nanoparticles embedded in well-structured carbon nanocubes for high-performance potassium-ion half/full batteries

Metal sulfides have been widely investigated as promising electrode materials for potassium-ion batteries(PIBs) due to their high theoretical capacities.However,the practical application of metal sulfides in PIBs is still hindered by their intrinsic shortcomings of low conductivity and severe volume changes during the potassiation/depotassiation process.Herein,a simple template-based two-step annealing strategy is proposed to impregnate CoS_2 nanoparticles in the well-structured carbon nanocubes(denoted CoS_2/CNCs) as an advanced anode material for PIBs.The ex-situ XRD measurements reveal the K storage mechanism in CoS_2/CNCs.Benefiting from the unique structures,including abundant active interfacial sites,high electronic conductivity,and significantly alleviated volume variation,CoS_2/CNCs present a high specific capacity(537.3 mAh g~(-1) at0.1 A g~(-1)),good cycling stability(322.4 mAh g~(-1) at 0.5 A g~(-1) after 300 cycles),and excellent rate capability(153.1 mAh g~(-1) at5 A g~(-1)).Moreover,the obtained nanocomposite shows superior potassium storage properties in K-ion full cells when it is coupled with a KVP04 F cathode.     

High-volumetric-capacity WSe_2 Anode for Potassium-ion Batteries

Exploring high-capacity electrode materials is critical for the development of K-ion batteries. In this work, we report a layered-structured tungsten selenide(WSe2) anode, which not only delivers an ultrahigh volumetric capacity of 1772.8 Ah/L(or 188.4 mA h/g) at a current density of 5 mA/g but also exhibits good rate capability(72 mA h/g at 200 mA/g) and cycling stability(83.14% capacity retention over 100 cycles at 100 mA/g). We have also revealed the underlying reaction mechanism through ex situ X-ray powder diffraction. Furthermore, proof-of-concept full-cell batteries comprising of WSe_2 anodes and Prussian Blue cathodes are capable of delivering an energy density of 135.2 Wh/kgcathode+anode. This work highlights the potential of WSe_2 as a promising high-volumetric-capacity anode material for rechargeable potassium-ion batteries.     

Unveiling the Advances of Nanostructure Design for Alloy-Type Potassium-Ion Battery Anodes via In Situ TEM

Nanostructure design and in situ transmission electron microscopy (TEM) are combined to demonstrate Sb-based nanofibers composed of bunched yolk–shell building units as a significantly improved anode for potassium-ion batteries (PIBs). Particularly, a metal–organic frameworks (MOFs)-engaged electrospinning strategy coupled to a confined ion-exchange followed by a subsequent thermal reduction is proposed to fabricate yolk–shell Sb@C nanoboxes embedded in carbon nanofibers (Sb@CNFs). In situ TEM analysis reveals that the inner Sb nanoparticles undergo a significant volume expansion/contraction during the alloying/dealloying processes, while the void space can effectively relieve the overall volume change, and the plastic carbon shell maintains the structural integrity of electrode material. This work provides an important reference for the application of advanced characterization techniques to guide the optimization of electrode material design.