Microwave assisted hydrothermal synthesis of tin niobates nanosheets with high cycle stability as lithium-ion battery anodes

SnNb₂O₆ and Sn₂Nb₂O₇ nanosheets were synthetized via microwave assisted hydrothermal method, and innovatively employed as anode materials for lithium-ion battery. Compared with Sn₂Nb₂O₇ and the previously reported pure Sn-based anode materials, the SnNb₂O₆ electrode exhibited outstanding cycling performance.     

Lotus-stalk Bi4Ge3O12 as binder-free anode for lithium and sodium ion batteries

The synthesized lotus-stalk Bi₄Ge₃O₁₂ utilized as binder-free anode for LIBs demonstrates excellent cycling performance. The synthesized lotus-stalk Bi₄Ge₃O₁₂ is composed of nanosheets, which is contribute to outstanding lithium storage performance.     

Sucrose assisted hydrothermal synthesis of SnO2/graphene nanocomposites with improved lithium storage properties

SnO₂/graphene nanocomposites are synthesized by a new hydrothermal treatment strategy under the assistance of sucrose. From the images of the scanning electron microscope (SEM) and transmission electron microscope (TEM), it can be observed that SnO₂ nanoparticles with the size of 4~5 nm uniformly distribute on the graphene nanosheets. The result demonstrates that sucrose can effectively prevent graphene nanosheets from restacking during hydrothermal treatment and subsequently treatment. The charging/discharging test result indicates that the SnO₂/graphene nanocomposites exhibit high specific capacity and excellent cycleability. The first reversible specific capacity is 729 mAh.g^?1 at the current density of 50 mA.g^?1, and remains 646 mAh.g^?1 after 30 cycles at the current density of 100 mA.g^?1, 30 cycles at the current density of 200 mA.g^?1, 30 cycles at the current density of 400 mA.g^?1, 30 cycles at the current density of 800 mA.g^?1, and 30 cycles at the current density of 50 mA.g^?1.     

V-MOF@graphene derived two-dimensional hierarchical V2O5@graphene as high-performance cathode for aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries (ZIBs) are attracting growing attention in the field of grid-scale energy storage systems due to their reliable safety and low cost. However, it is still hindered by the limited choices of suitable cathode materials with high performance for aqueous ZIBs. Herein, we developed a V-MOF@graphene derived two-dimensional hierarchical V₂O₅@graphene for the first time, where the porous V₂O₅ nanosheets are homogeneously attached to the 2D graphene substrate. Benefiting from the unique 2D composite structure with excellent electronic and ionic conductivity, adequate active sites, as well as the synergistic effect between the ultrathin V₂O₅ nanosheets and graphene, the V₂O₅@graphene here exhibits outstanding electrochemical performance in aqueous ZIBs. Particularly, it delivered an ultrahigh reversible capacity of 378 mAh/g at a current density of 2 A/g. What is more, a high specific capacity of 305 mAh/g after 100 cycles at 0.1 A/g and 200 mAh/g after 1,000 cycles at 1 A/g can be achieved. These ideal results suggest that the V₂O₅@graphene cathode hold great promise for high-performance aqueous zinc-ion batteries.     

Two-Dimensional Germanium Sulfide Nanosheets as an Ultra-Stable and High Capacity Anode for Lithium Ion Batteries

Lithium ion batteries (LIBs) at present still suffer from low rate capability and poor cycle life during fast ion insertion/extraction processes. Searching for high-capacity and stable anode materials is still an ongoing challenge. Herein, a facile strategy for the synthesis of ultrathin GeS₂ nanosheets with the thickness of 1.1 nm is reported. When used as anodes for LIBs, the two-dimensional (2D) structure can effectively increase the electrode/electrolyte interface area, facilitate the ion transport, and buffer the volume expansion. Benefiting from these merits, the as-synthesized GeS₂ nanosheets deliver high specific capacity (1335 mAh g⁻¹ at 0.15 A g⁻¹), extraordinary rate performance (337 mAh g⁻¹ at 15 A g⁻¹) and stable cycling performance (974 mAh g⁻¹ after 200 cycles at 0.5 A g⁻¹). Importantly, our fabricated Li-ion full cells manifest an impressive specific capacity of 577 mAh g⁻¹ after 50 cycles at 0.1 A g⁻¹ and a high energy density of 361 Wh kg⁻¹ at a power density of 346 W kg⁻¹. Furthermore, the electrochemical reaction mechanism is investigated by the means of ex-situ high-resolution transmission electron microscopy. These results suggest that GeS₂ can use to be an alternative anode material and encourage more efforts to develop other high-performance LIBs anodes.     

Fabrication of Nb2O5/C nanocomposites as a high performance anode for lithium ion battery

Nb₂O₅/C nanosheets are successfully prepared through a mixing process and followed by heating treatment.Such Nb₂O₅/C based electrode exhibits high rate performance and remarkable cycling ability, showing a high and stable specific capacity of ~380 mAh g^-1 at the current density of 50 mA g^-1(much higher than the theoretical capacity of Nb₂O₅).Further more,at a current density of 500 mA g^-1,the nanocomposites electrode still exhibits a specific capacity of above 150 mAh g^-1 after 100 cycles.These results suggest the Nb₂O₅/C nanocomposite is a high performance anode material for lithium-ion batteries.     

Porous bowl-shaped VS_2 nanosheets/graphene composite for high-rate lithium-ion storage

Two-dimensional (2D) layered vanadium disulfide (VS_2) is a promising anode material for lithium ion batteries (LIBs) due to the high theoretical capacity.However,it remains a challenge to synthesize monodispersed ultrathin VS_2 nanosheets to realize the full potential.Herein,a novel solvothermal method has been developed to prepare the monodispersed bowl-shaped NH_3-inserted VS_2 nanosheets (VS_2).The formation of such a unique structure is caused by the blocked growth of (001) or (002) crystal planes in combination with a ripening process driven by the thermodynamics.The annealing treatment in Ar/H_2creates porous monodispersed VS_2(H-VS_2),which is subsequently integrated with graphene oxide to form porous monodispersed H-VS_2/rGO composite coupled with a reduction process.As an anode material for LIBs,H-VS_2/rGO delivers superior rate performance and longer cycle stability:a high average capacity of 868/525 mAh g~(-1) at a current density of 1/10 A g~(-1);a reversible capacity of 1177/889 mAh g~(-1) after 150/500 cycles at 0.2/1 A g~(-1).Such excellent electrochemical performance may be attributed to the increased active sites available for lithium storage,the alleviated volume variations and the shortened Li-ion diffusion induced from the porous structure with large specific surface area,as well as the protective effect from graphene nanosheets.     

Li-ion charge storage performance of wood-derived carbon fibers@MnO as a battery anode

Wood-derived carbons have been demonstrated to have large specific capacities as the anode materials of lithium-ion batteries(LIBs). However, these carbons generally show low tap density and minor volumetric capacity because of high specific surface area and pore volume. Combination with metal oxide is one of the expected methods to alleviate the obstacles of wood-derived carbons. In this work, the composites of Mn O loaded wood-derived carbon fibers(CF@Mn O) were prepared via a simple and envir...     

Three‐Dimensional MoS2 Hierarchical Nanoarchitectures Anchored into a Carbon Layer as Graphene Analogues with Improved Lithium Ion Storage Performance

Much attention has recently been focused on the synthesis and application of graphene analogues of layered nanomaterials owing to their better electrochemical performance than the bulk counterparts. We synthesized graphene analogue of 3D MoS₂ hierarchical nanoarchitectures through a facile hydrothermal route. The graphene‐like MoS₂ nanosheets are uniformly dispersed in an amorphous carbon matrix produced in situ by hydrothermal carbonization. The interlaminar distance between the MoS₂ nanosheets is about 1.38 nm, which is far larger than that of bulk MoS₂ (0.62 nm). Such a layered architecture is especially beneficial for the intercalation and deintercalation of Li⁺. When tested as a lithium‐storage anode material, the graphene‐like MoS₂ hierarchical nanoarchitectures exhibit high specific capacity, superior rate capability, and enhanced cycling performance. This material shows a high reversible capacity of 813.5 mAh g^?1 at a current density of 1000 mA g^?1 after 100 cycles and a specific capacity as high as 600 mAh g^?1 could be retained even at a current density of 4000 mA g^?1. The results further demonstrate that constructing 3D graphene‐like hierarchical nanoarchitectures can effectively improve the electrochemical performance of electrode materials.     

Design of hierarchical and mesoporous FeF3/rGO hybrids as cathodes for superior lithium-ion batteries

Iron fluoride (FeF₃) is considered as a promising cathode material for Li-ion batteries (LIBs) due to its high theoretical capacity (712 mAh/g) with a 3e^? transfer. Herein, we have designed a strategy of hierarchical and mesoporous FeF₃/rGO hybrids for LIBs, where the hollow FeF₃ nanospheres are the main contributor to the specific capacity and the 2D rGO nanosheets are the matrix elevating the electronic conductivity and buffering the volume expansion. The unique FeF₃/rGO hybrid can be rationally synthesized by a non-aqueous in-situ precipitation method, offering the merits of large specific surface area with rich active sites, fast transport channels for lithium ions, effective alleviation of volume expansion during cycles, and accelerating the electrochemical reaction kinetics. The FeF₃/rGO hybrid electrode possesses a high initial discharge capacity of 553.9 mAh/g at a rate of 0.5 C with 378 mAh/g after 100 cycles, acceptable rate capability with 168 mAh/g at 2 C, and feasible high-temperature operation (320 mAh/g at 70 °C). The superior electrochemical behaviors presented here demonstrates that the FeF₃/rGO hybrid is a potential electrode for LIBs, which may open up a new vision to design high-efficiency energy-storage devices such as LIBs based on transition metal fluorides.     

Highly elastic cobweb-like SiO/CNF composites with reconstructed heterostructure for high-efficient lithium storage

The silicon-based materials are promising candidates for lithium-ion batteries owing to their high energy density. However, achieving long lifespan under realistic conditions remains a challenge because of the volume expansion and low conductivity. In this work, the highly elastic cobweb-like composite materials consisted by SiO and nanofibers are designed and fabricated for high-efficient lithium storage by ball-milling & electrostatic spinning method. The reconstructed heterostructure and highly elastic nanofibers can simultaneously increase the conductivity and inhibit the “expansion effect” of silicon-based materials. The constructed electrode of n-SiO/CNF delivers an initial capacity of 1700 mAh/g, and maintains the capacities over 1000 mAh/g after 100 cycles at the current density of 500 mA/g. Meanwhile, this electrode can give an initial coulombic efficiency over 85% and maintains at 98% in the following charge/discharge processes. Furthermore, it exhibits efficient long-term electrochemical performance, maintaining the capacity at about 1000 mAh/g at a high current density of 1000 mA/g after 1000 cycles. This work could provide a promising strategy for enhancing the performance of silicon-based composite materials for practical application in lithium-ion batteries.     

Ultrahigh rate binder-free Na_3V_2(PO_4)_3/carbon cathode for sodium-ion battery

Sodium ion batteries(SIBs)are very promising for large-scale energy storage in virtue of its high energy density,abundant sodium resources and low environmental impact,etc.However,it is still a big challenge to develop high-performance and durable cathode materials for SIBs.Among different candidate materials,Na_3V_2(PO_4)_3has attracted great attentions due to its high theoretical capacity(117 mAh/g),stable framework structure and excellent ionic conductivity.However,Na_3V_2(PO_4)_3delivers inferior rate capability and cycling stability due to its poor electronic conductivity.In this work,free-standing Na_3V_2(PO_4)_3/carbon nanofiber membranes are synthesized by an electrospinning-sintering route.The sample could deliver excellent cycling capability with specific capacity of 112 mAh/g at 1 C after 250cycles and ultrahigh rate capability with 76.9 mAh/g even at 100 C,which is superior to many state-ofthe-art SIB cathode materials.This can be attributed to the hierarchically distributed Na_3V_2(PO_4)_3crystals in carbon nanofiber network,which possesses outstanding electronic/ionic conductivity and thus leads to an ultrahigh rate capability.     

锂离子电池正极材料xLi2MnO3·(1-x)Li[Ni1/3Mn1/3Co1/3]O2的制备及表征

以过渡金属乙酸盐和乙酸锂为原料,柠檬酸为螯合剂,通过溶胶-凝胶法结合高温煅烧法制备了锂离子电池富锂锰基正极材料xLi2MnO3·(1-x)Li[Ni1/3Mn1/3Co1/3]O2,采用X射线衍射(XRD),扫描电子显微镜(SEM)和电化学性能测试对所得样品的结构,形貌及电化学性能进行了表征.结果表明:x=0.5时,在900°C下煅烧12h得到颗粒均匀细小的层状xLi2MnO3·(1-x)Li[Ni1/3Mn1/3Co1/3]O2材料,并具有良好的电化学性能,在室温下以20mA·g-1的电流密度充放电,2.0-4.8V电位范围内首次放电比容量高达260.0mAh·g-1,循环40次后放电比容量为244.7mAh·g-1,容量保持率为94.12%.     

Bimetallic CoNiSe2/C nanosphere anodes derived from Ni-Co-metal-organic framework precursor towards higher lithium storage capacity

Through uncomplicated carbonation process, a carbon-embedded CoNiSe₂/C nanosphere was synthesized from Ni-Co-MOF (metal-organic framework) precursor whose controllable structure and synergistic effect of bimetallic Ni/Co brought CoNiSe₂/C anodes with high specific surface area (172.79 m²/g) and outstanding electrochemical performance. CoNiSe₂/C anodes obtained reversible discharge capacities of 850.9 mAh/g at 0.1 A/g after cycling for 100 cycles. In addition, CoNiSe₂/C exhibits excellent cycle stability and reversibility in the rate test at a current density of 0.1–2.0 A/g. When the current density returns to 0.5 A/g for 150 cycles, its discharge ratio the capacity is 330.8 mAh/g. Electrochemical impedance spectroscopy (EIS) tests suggested that CoNiSe₂/C anodes had a lower charge transfer impedance of 130.02 Ω after 30 cycles. In-situ X-ray diffraction (XRD) tests confirmed the alloying mechanism of CoNiSe₂/C which realized higher lithium storage capacity. This work affords substantial evidence for the extension of bimetallic selenides in secondary batteries, promoting the development of bimetallic selenides in anode materials for LIBs.     

Matryoshka-type carbon-stabilized hollow Si spheres as an advanced anode material for lithium-ion batteries

Silicon(Si) is regarded as the potential anode for lithium-ion batteries(LIBs), due to the remarkable theoretical specific capacity and low voltage plateau. However, the rapid capacity decay resulting from volume variation and slow electron/ion transportation of Si limit its practical application. Here, matryoshka-type carbon-stabilized hollow silicon spheres(Si/C/Si/C) are synthesized by an aluminothermic reduction and calcination process. The Si/C/Si/C anode materials prepared at 500 ℃(Si/C/Si...     

Ultrathin two-dimensional bimetal NiCo-based MOF nanosheets as ultralight interlayer in lithium-sulfur batteries

Lithium-sulfur batteries as one of the most promising next-generation high-energy storage system, the shuttle effect, the expansion of cathode and the slow electrode redox kinetics limit its further development. Herein, we report a two-dimensional, ultrathin and ultra-light bimetal-NiCo-organic framework as the interlayer for Li-S batteries. This kind of interlayer can effectively block polysulfides and accelerate the conversion with a thickness of only 1 μm and a load of 0.1 mg/cm². Because the MOF nanosheets with a thickness of a few nanometers have a large specific surface and a large number of exposed accessible active sites. At the same time, the intrinsic activity of each site is enhanced and the catalytic performance is improved due to the synergistic effect of mixed metals and the unique coordination environment around the active sites. So, 2D NiCo MOF/CNT totally meets the requirements for the lightweight and effective interlayer. The initial discharge capacity of cell with 2D NiCo MOF/CNT interlayer can reach 1132.7 mAh/g at 0.5 C. It remained 709.1 mAh/g after 300 cycles, showing good cycling stability and rate performance.     

Electrospun Sb2Se3@C nanofibers with excellent lithium storage properties

Antimony-based materials have become promising anodes within lithium-ion batteries(LIBs)due to their low cost and the high theoretical capacity.However,there is a potential to further enhance the electrochemical performance of such antimony-based materials.Herein,Sb2Se3@C nanofibers(Sb2Se3@CNFs)are designed and obtained via a novel electrospinning method.Upon electrochemically testing as an anode within LIBs,the Sb2Se3@CNFs(annealed at 600℃)delivers a remarkably good cycling performance of 625 mAh/g at 100 mA/g after 100 cycles.Moreover,it still remains at 490 mAh/g after 500 cycles with an applied current density of 1.0 A/g.The excellent performance of the Sb2 Se3@CNFs can be attributed to the fact that the N-doped C matrices not only remit the volume expansion of materials,but also enhance the electrical and ionic conductivity thusly increasing the lithium-ion diffusion.The obtained Sb2Se3@CNFs are promising anode for LIBs in the future.     

A novel synthesis of Nb_2O_5@rGO nanocomposite as anode material for superior sodium storage

The development of novel anode materials,with superior rate capability,is of utmost significance for the successful realization of sodium-ion batteries(SIBs).Herein,we present a nanocomposite of Nb_2 O_5 and reduced graphene oxide(rGO) by using hydrothermal-assisted microemulsion route.The water-in-oil microemulsion formed nanoreactors,which restrained the particle size of Nb_2 O_5 and shortened the diffusion length of ions.Moreover,the rGO network prevented agglomeration of Nb_2 O_5 nanoparticles and improved electronic conductivity.Consequently,Nb_2 O_5@rGO nanocomposite is employed as anode material in SIBs,delivering a capacity of 195 mAh/g after 200 charge/discharge cycles at 0.2 A/g.Moreover,owing to conductive rGO network,the Nb_2 O_5@rGO electrode rende red a specific capacity of 76 mAh/g at high current density of 10 A/g and maintained 98 mAh/g after 1000 charge/discharge cycles at 2 A/g.The Nb_2 O_5@rGO electrode material prepared by microemulsion method shows promising possibilities for application of SIBs.     

Amorphous nickel borate nanosheets as cathode material with high capacity and better cycling performance for zinc ion battery

Zinc-ion batteries are under current research focus because of their uniqueness in low cost and high safety. However, the pursuing of high-performance cathode materials of aqueous Zinc ion batteries (AZBs) with low cost, high energy density and long cycle life has become the key problem to be solved. Herein we synthesized a series of amorphous nickel borate (AM-NiBO) nanosheets by varying corrosion time with in-situ electrochemical corrosion method. The AM-NiBO-T13 as electrode material possesses a high areal capacity of 0.65 mAh/cm² with the capacity retention of 95.1% after 2000 cycles. In addition, the assembled AM-NiBO-T13//Zn provides high energy density (0.77 mWh/cm² at 1.76 mW/cm²). The high areal capacity and better cycling performance can be owing to the amorphous nanosheets structure and the stable coordination characteristics of boron and oxygen in borate materials. It shows that amorphous nickel borate nanosheets have great prospects in the field of energy storage.     

One-step construction of MoO_2 uniform nanoparticles on graphene with enhanced lithium storage

Transition-metal oxides are considered to be a promising anode material for lithium-ion batteries(LIBs)due to their high capacities,low cost,and ease of synthesis.Herein,a hybrid nanosheet composed of uniform MoO_2 nanoparticles(NPs) homogeneously immobilized on the reduced graphene oxide nanosheets(MoO_2 NP@rGO) is first synthesized by a self-templating and subsequent calcination treatment.The unique two-dimensional hybridnanosheets provides several merits.rGO can be used as a favorable support for the loading of electrochemically active MoO_2 NPs.Meanwhile,MoO_2 NPs can effectively prevent the stacking of the rGO.The effective combination of MoO_2 NPs and rGO nanosheets furnish additional electrochemically interfacial active sites for extra lithium ion sto rage.Noticeably,the as-fabricated hybrid nanosheets deliver a reversible capacity of 641 mAh/g after 350 cycles at a current density of 1000 mA/g with a good rate capability.The greatly enhanced lithium storage properties of MoO_2 NP@rGO indicate the importance of elaborate construction of novel hybrid hierarchical structures.