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Antimony sulfide (Sb2S3) has a high theoretical specific capacity due to its two reaction mechanisms of conversion and alloying during the Li+-(de)intercalation process, thus becoming a promising lithium-ion battery (LIB) anode material. However, its poor inherent conductivity and large volume expansion during repeated Li+-(de)intercalation processes greatly hinder the in-depth development of Sb2S3 based LIB anode materials. Herein, an Sb2S3/SnO2@rGO composite was prepared by using an interface engineering technique involving metal-containing ionic liquid precursors, in which Sb2S3/SnO2 quantum dots (QDs) as p–n heterojunctions are uniformly anchored on the surface of reduced graphene oxide (rGO). The p–n heterogeneous interface between Sb2S3 and SnO2 QDs induces an internal electric field, promoting the electronic/ion transport during electrochemical reactions, and the QD-sized Sb2S3/SnO2 heterostructure with a larger surface area provides more active sites for Li+-(de)intercalation reactions. In addition, the rGO matrix acts as a buffer to prevent the aggregation of active Sb2S3 and SnO2 QDs, alleviate the volume expansion, and enhance the conductivity of the composite during repeated cycles. These advantages endow the designed Sb2S3/SnO2@rGO electrode with excellent reaction kinetics and good long cycling stability. As an anode material of LIBs, it can still provide a reversible specific capacity of 474 mA h g−1 after 2000 cycles at a high current density of 3.0 A g−1, which is superior to those of most of the previously reported Sb2S3-based carbon materials. The p–n heterostructure construction strategy of nano-metal sulfide/metal oxides in this work can provide inspiration for the design and synthesis of other advanced energy storage materials. [ABSTRACT FROM AUTHOR]

Metal chalcogenides are attractive anode materials for lithium-ion batteries (LIBs) due to their high theoretical capacities. With the advantages of low cost and abundance reserves, ZnS is regarded as the prime candidate anode material for future generations, but its practical application is hindered by the large volume expansion during repeated cycling processes and inherent poor conductivity. Rational design of the microstructure with large pore volume and high specific surface area is of great significance to solve these problems. Here, a carbon-coated ZnS yolk-shell structure (YS-ZnS@C) has been prepared by selective partial oxidation of a core-shell structured ZnS@C precursor in air and subsequent acid etching. Studies show that the carbon wrapping and proper etching to bring cavities can not only improve the material's electrical conductivity, but can also effectively alleviate the volume expansion problem of ZnS during its cycles. As a LIB anode material, the YS-ZnS@C exhibits an obvious superiority in capacity and cycle life compared to ZnS@C. The YS-ZnS@C composite shows a discharge capacity of 910 mA h g−1 at the current density of 100 mA g−1 after 65 cycles, compared to only 604 mA h g−1 for ZnS@C after 65 cycles. Notably, at a large current density of 3000 mA g−1, a capacity of 206 mA h g−1 can still be maintained after 1000 cycles (over three times of the capacity for ZnS@C). It is expected that the synthetic strategy developed here is applicable to designing various high-performance metal chalcogenide-based anode materials for LIBs. [ABSTRACT FROM AUTHOR]

Iron-based sulfides are considered promising anode materials for lithium-ion batteries (LIBs) due to their low cost and high theoretical specific capacities. However, low conductivity and dissolution of lithium polysulfides during the reaction hamper their practical applications. Herein, we firstly synthesized N-doped carbon-coated Fe1−xS (Fe1−xS@NC) sheets through vacuum pyrolysis of the precursor Fe1−xS(en)0.5 (en = ethylenediamine). Then Fe1−xS@NC-rGO composites (rGO = reduced graphene oxide) were prepared in which the Fe1−xS@NC sheets were anchored on the rGO. The performance of the composites as an anode material for LIBs has been investigated. It is found that coating N-doped C on Fe1−xS surfaces can improve the surface conductivity and electrochemical kinetics of Fe1−xS, which is beneficial for the conversion between lithium polysulfides and Fe1−xS. In addition, the coated N-doped C on the Fe1−xS sheets can serve as a barrier to direct contact between the electrolyte and the material, reducing the dissolution of polysulfides and preventing the loss of active ingredients. More importantly, the double protection of the N-doped C layer and the flexible rGO substrate minimizes the structural damage caused by the cyclic expansion of Fe1−xS@NC-rGO. As expected, Fe1−xS@NC-rGO exhibits good rate performance with a reversible capacity of 939.5 mA h g−1 after 1690 cycles at a current density of 1.0 A g−1, along with outstanding charge and discharge performance and excellent long-term cycling stability. This work shows that the introduction of NC coating and the rGO matrix into Fe1−xS would synergistically enhance the performance of Fe1−xS for LIBs and highlights the effectiveness of the synthetic strategy for double carbon-based materials-protected sulfides in developing superior LIB electrodes. [ABSTRACT FROM AUTHOR]

Silicon (Si) has recently aroused great interest as a promising anode material for lithium-ion batteries with high energy density due to its high theoretical capacity. However, the application of Si remains a great challenge owing to its extremely large volume change during cycling, thus resulting in dramatic capacity fading. Herein, a novel structure design of the porous Si/C composite with Si nanoparticles embedded in the carbon nanosheets has been successfully achieved by using a recrystallized NaCl template with appropriate particle size. The outermost sheet-like carbon coating can improve the electronic conductivity and contribute to the formation of a more stable solid-electrolyte interphase layer, while the inner void space effectively buffers the volume expansion of Si during the lithiation process. In addition, only a structure with Si particles anchored on the surface of carbon nanosheets has been obtained by using a commercial NaCl template with large particle size, confirming the effective regulation of the NaCl template in the microstructure and thus the electrochemical properties of the Si/C composites. As expected, benefiting from the combination of the outermost carbon coating and recrystallized NaCl-derived porous structure, the as-obtained Si/C composite demonstrates attractive cycling stability and rate performance as an anode material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Novel N-doped carbon coated porous hierarchical MnO microspheres have been successfully synthesized via the simultaneous pyrolysis of MnCO 3 and polyacrylonitrile (PAN) at low calcination temperature. The micro/nano structure with uniform N-doped carbon coating, suitable interior pores and tiny primary MnO nanocrystals can significantly increase the electronic conductivity of the composite, reduce the amount of irreversible solid-electrolyte interphase (SEI) layer, accommodate the huge volume change of MnO during cycling and facilitate easier redox reaction of Mn2+/Mn x+ (x >2) to generate extra capacity. By using partially pyrolytic PAN as the conductive agent and binder, the obtained additive-free MnO-based electrode (MnO@NC-S) demonstrates a high reversible capacity of 998 mAh g−1 after 100 cycles at 0.1 A g−1 and remarkable long-term cycling stability with the capacity of 629 mAh g−1 after 500 cycles at 0.5 A g−1. [Display omitted] [ABSTRACT FROM AUTHOR]

The nanocomposites of SnS 2 and reduced graphene oxide (SnS 2 @rGO) are synthesized by a unique ionic liquid-assisted route, which involves SnS x precursors prepared by the reaction of elemental tin and sulfur in the ionic liquid of 1-butyl-2,3-dimethylimidazolium chloride. The SnS 2 contents in the composites can be adjusted by changing the ratios of SnS x precursor to graphene oxide (GO). Transmission electron microscopy (TEM) observations clearly show that SnS 2 nanoparticles with a diameter of about 5 ​nm are anchored on reduced graphene oxide (rGO). The synthesized composites are used as the anode materials for lithium-ion batteries (LIBs), which demonstrate highly reversible capacities and outstanding cycle stabilities. The discharge specific capacity can still reach 1045.8 ​mAh·g−1 after 700 cycles at a current density of 500 ​mA ​g−1. The prepared SnS 2 @rGO composites with highly reversible capacities and good cycle performance may be promising LIBs anode materials. Image 1 • The nanocomposites are synthesized by a unique ionic liquid-assisted route. • SnS 2 nanoparticles with a diameter of about 5 ​nm are anchored on rGO. • The synthesis method is simple and fast. • The composite reaches 1045.8 ​mA ​h ​g−1 after 700 cycles at 500 ​mA ​g−1. [ABSTRACT FROM AUTHOR]

SnO 2 is one of the promising anode materials for the next-generation lithium-ion batteries due to its high theoretical capacity. The main challenges of SnO 2 include large volume change during cycling, partially reversibility between SnO 2 and Sn, and unstable solid-electrolyte interphase. Herein, we demonstrate a novel structure design of SnO 2 -based anode, in which SnO 2 nanoparticles are embedded in a hierarchical porous carbon framework and further coated by the uniform Nitrogen-doped carbon layer. The hierarchical porous carbon framework can provide void space for the SnO 2 expansion, while the Nitrogen-doped carbon coating can act as a buffer layer to reduce the amount of irreversible solid-electrolyte interphase. This peculiar structure can also build highly conductive network, and promote the reversible conversion from Sn to SnO 2 by preventing the agglomeration of the intermediate Sn product. Therefore, the obtained SnO 2 @HPC@NC composite exhibits remarkable electrochemical performance with a high specific capacity of 1100 mAh g−1 after 100 cycles at 0.1 A g−1 and superior long-term stability over 500 cycles at 1 A g−1. Image 1 • SnO 2 @HPC@NC with novel structure was successfully designed. • The hierarchical porous carbon framework greatly buffers the volume change of SnO 2. • The N-doped carbon coating is helpful to reduce the amount of irreversible SEI. • The peculiar structure can promote the reversible conversion from Sn to SnO 2. • The composite exhibits remarkable long-term cycling stability. [ABSTRACT FROM AUTHOR]

Low yield is a common problem for the solvothermal synthesis of LiMnPO 4. Herein, a high-yield synthesis route is developed to obtain novel LiMnPO 4 /C nanoplates via a facile water-polyethylene glycol (PEG200)-assisted solvothermal approach followed by carbonization treatment. The reactant concentration plays an important role in the formation of LiMnPO 4 /C by effectively controlling the solution supersaturation of solvothermal reaction. When using optimal Mn concentration of 0.5 mol L−1, the as-prepared LiMnPO 4 /C exhibits outstanding rate capability with a high reversible value of 100.1 mAh g−1 at 10 C and excellent cycling stability with capacity and energy density retention of ∼89.7% and ∼91.7% after 300 cycles at 0.5 C, respectively, which can be attributed to its typical structure of high crystalline, uniform carbon coating and plate-like morphology with small size of 30∼80 nm along the [010] direction. This work provides a scalable route for the design of high-performance LiMnPO 4 materials for commercial lithium-ion batteries. [Display omitted] A high-yield synthesis route, which combines well-designed solvothermal reaction with normal carbonization treatment, is developed to obtain novel LiMnPO 4 /C nanoplates as cathode materials for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

The rational design and construction of hierarchical heterogeneous nanostructures is effective for improving the electrical and ionic conductivity of anode material for lithium-ion batteries (LIBs). Herein, a hierarchical ZnS/SnO 2 @rGO (rGO = reduced graphene oxide) composite has been designed and successfully synthesized via hydrothermal method by using metal-containing ionic liquid and ZIF-8 metal organic framework precursors. The synergistic effect of precursors hinders the agglomeration of nanoparticles, which makes SnO 2 quantum dots (QDs) be anchored on the surface of polyhedral ZnS and further be uniformly dispersed on the rGO. The outer rGO matrix can improve the electrical conductivity and fully alleviate the volume expansion of ZnS/SnO 2 during the cycling. Meanwhile, the ZnS/SnO 2 heterostructure can endow the material with excellent reaction kinetics, accelerating the charge transfer and providing more active sites for electrochemical reactions. Benefiting from the compositional and structural features, the as-prepared ZnS/SnO 2 @rGO as LIB anode provides the reversible specific capacity of 1030 and 630 mA h g−1 after 1150 cycles at the current density of 1.0 and 3.0 A g−1, respectively. This mixed-precursors strategy represents a novel and effective technique to in situ synthesize hierarchical metal sulfide/metal oxide/carbon anode materials for developing high-performance battery. [Display omitted] • Hierarchical ZnS/SnO 2 @rGO was developed by structure-directing effect of mixed-precursors. • Small-sized SnO 2 QDs are attached on ZnS polyhedron then uniformly dispersed on rGO. • As LIB anode, the composite exhibits the excellent lithium-ion storage performance. • 2D conductive rGO coat and ZnS/SnO 2 heterojunction contribute to the performance. • The novel mixed-precursors strategy can be used to obtain high-performance LIBs. [ABSTRACT FROM AUTHOR]