Search

Nb2O5has been viewed as a promising anode material for lithium-ion batteries by virtue of its appropriate redox potential and high theoretical capacity. However, it suffers from poor electric conductivity and low ion diffusivity. Herein, we demonstrate the controllable fabrication of Cu-doped Nb2O5with orthorhombic (T–Nb2O5) and monoclinic (H–Nb2O5) phases through annealing the solvothermally presynthesized Nb2O5precursor under different temperatures in air, and the Cu doping amount can be readily controlled by the concentration of the precursor solution, whose effect on the lithium storage behaviors of the Cu-doped Nb2O5is thoroughly investigated. H–Nb2O5shows obvious redox peaks (Nb5+/Nb4+and Nb4+/Nb3+) with much higher capacity and better cycling stability than those for the widely investigated T–Nb2O5. When introducing appropriate Cu doping, the optimized H–Cu0.1–Nb2O5electrode shows greatly enhanced conductivity and lower diffusion barrier as revealed by the theoretical calculations and electrochemical characterizations, delivering a high reversible capacity of 203.6 mAh g–1and a high capacity retention of 140.8 mAh g–1after 5000 cycles at 1 A g–1, with a high initial Coulombic efficiency of 91% and a high rate capacity of 144.2 mAh g–1at 4 A g–1. As a demonstration for full-cell application, the H–Cu0.1–Nb2O5||LiFePO4cell displays good cycling performance, exhibiting a reversible capacity of 135 mAh g–1after 200 cycles at 0.2 A g–1. More importantly, this work offers a new synthesis protocol of the monoclinic Nb2O5phase with high capacity retention and improved reaction kinetics.

Antimony (Sb)-based materials have shown great potential as anode materials for lithium-ion batteries (LIBs) owing to their high energy density as well as long lifespan. However, the huge volume variation upon cycling will result in severe capacity fading, thus hindering the practical application of Sb-based anode materials. Herein, an ultrafine Sb2O3nanoparticle-decorated reduced graphene oxide (rGO) composite (denoted as Sb2O3/rGO) was developed through a facile thermal decomposition of antimony 2-ethylhexanoate on rGO in the air at low temperatures, where the ultrafine Sb2O3nanoparticles are homogeneously anchored on the rGO substrate. Benefiting from the rich mesoporous structure, large specific surface area, moderate mass loading, and uniform dispersion of ultrafine Sb2O3nanoparticles, the optimized Sb2O3/rGO-100 electrode showed enhanced electrode–electrolyte contact area and ion/electron transferability. When applied as an anode material for LIBs, the Sb2O3/rGO-100 electrode exhibited excellent cycling stability and rate performance, delivering a high reversible capacity of 513 mAh g–1at 0.5 A g–1after 300 cycles. Ex situ transmission electron microscopy reveals that the nanoscale configuration of rGO and Sb2O3nanoparticles of Sb2O3/rGO-100 was well maintained, while the bulk Sb2O3crushed into pieces after cycling, further confirming the robust structure of the composite. More importantly, the synthetic method may also be commonly applied to other metal oxides, which is promising for the development of high-performance next-generation electrochemical energy storage devices.

Transition metal oxides with spinel AB2O4phases are deemed as potential anode materials for lithium-ion batteries (LIBs), attributing to high specific capacities, low cost, and environmental friendliness, but the pulverization problem induced by the volume changes upon lithiation/delithiation greatly restricts their practical applications. To overcome this problem by nanostructure engineering, we herein successfully design and fabricate one-dimensional (1D) nanotubes consisted of interconnected MnCo2O4nanoparticles via the convenient electrospinning process and the following heating method. As an anode for LIBs, the as-prepared 1D MnCo2O4nanotubes demonstrate superior lithium storage properties, showing a high specific capacity (701.4 mA h g–1at 500 mA g–1even after going through 320 cycles) and a high-rate performance (400.4 mA h g–1at 1 A g–1). The unique 1D hollow tubular nanoarchitecture assembled from interconnected nanoparticles can provide richer active sites and shorten the lithium diffusion length, as well as mitigate the pulverization issue caused by volume changes.

SnO2suffers from the severe pulverization problem when used as an anode material for lithium ion batteries (LIBs). To overcome its drawbacks, hybridizing nanosized SnO2with carbon-based materials is very impactful, and we herein successfully synthesize ultrasmall SnO2nanodots (average size of around 5 nm) within the channels of the commercial ordered mesoporous carbon (CMK-3), in which the tin precursor is prefilled under a vacuum and then is easily converted into SnO2by annealing at 350 °C in air. The as-prepared SnO2@CMK-3 composite demonstrates good lithium storage properties, displaying a discharge capacity of 898.8 mA h/g at the 150th cycle at 500 mA/g, apparently higher than that for the bare SnO2and CMK-3 electrodes. The superior electrochemical performance of SnO2@CMK-3 can be due to the high conductivity and vast pore volume of the CMK-3 carbon matrices, which efficiently alleviate the volume change induced pulverization and enhance the electrode conductivity. Besides, the uniform distribution of the ultrasmall SnO2nanodots within CMK-3 maximally enlarges the lithium storage sites and minimizes the effect of the volume variation.

Tin-based oxides are promising anode materials for lithium ion batteries (LIBs) in virtue of their many advantages including high capacity, abundant reserves and environmental friendliness. Yet, previous studies mainly focus on the SnO2-based anodes for lithium storage. Considering that the mixed valence and layered crystal structure of Sn3O4may lead to better lithium storage properties, Sn3O4-based anode material is designed and synthesized through a facile hydrothermal method in this work. The as-prepared Sn3O4nanosheets are coated with N-doped carbon layers (∼15 nm) on both sides through dopamine polymerization and subsequent polydopamine carbonization to solve the issues of poor intrinsic electronic conductivity and drastic volume change during LiSn alloying/dealloying, which have hindered their application in LIBs. With the structural and composition advantages brought by the thick N-doped carbon layers, the Sn3O4@NC nanosheets delivered a remarkable reversible capacity (1222 mAh g−1after 50 cycles at 200 mA g−1) and excellent rate performance when applied in LIB as anode material, owing to the improved electrical conductivity and strengthened structure stabilities. Importantly, we demonstrate a convenient strategy to realize carbon coating in the fabrication of Sn3O4-based anode materials, which could inspire the development of other Sn3O4-based anode materials with excellent lithium storage properties.

Tenable structure design is vital in the pursuit of advanced anode materials for enhanced lithium storage, but construction of the desired architectures often faces challenges. Herein, we demonstrate the facile fabrication of double yolk-shelled MnO/C microspheres by annealing the solvothermally synthesized Mn-gluconate microspheres under Ar atmosphere, and the double or single yolk-shell structure can be easily regulated by changing the glucose amount. Benefits brought by the unique structure include enlarged surface area, hierarchical pores, abundant reaction sites and increased ion diffusion rate. Besides, combination of MnO with glucose-derived carbon could not only restrict the volume variation of MnO but also increase the electrical conductivity, bringing improved rate capability and enhanced cycling stability. Thus, a high-rate and stable capacity of 611 mAh g−1after 500 cycles at 1 A g−1is observed in the lithium-ion batteries adopting the presented double yolk-shelled MnO/C microspheres as the anode materials, thanks to the synergistic structure and composition advantages. Importantly, this study provides a controllable method to construct delicate multi-shelled structures with simultaneous carbon hybridization, which could be promising in fabrication of advanced electrodes for energy-related applications.

Transition metal sulfides (TMSs) have been considered as up-and-coming anode materials for lithium-ion batteries (LIBs) owing to their large theoretical capacity and good reversibility. However, obvious volume variation and sluggish kinetics greatly limit their practical application. To address this issue, we successfully design and fabricate hollow CoS2/MoS2nanospheres and effectively enhance their lithium storage performance via N-doped carbon-coating (CoS2/MoS2@N-C). The unique hollow structure provides shortened ion-diffusion path, while the N-doped carbon shells buffer the severe volume changes during cycling and improve the electronic conductivity of the electrode. When used as an anode material for LIBs, the CoS2/MoS2@N-C displays high specific capacity (1056.9 mA h g−1at 100 mA g−1), excellent cycling stability (653.9 mA h g−1after 250 cycles at 1000 mA g−1), and rate capability (685 mA h g−1at 2000 mA g−1). The CoS2/MoS2@N-C||LiFePO4full-cell LIB is also assembled and exhibits remarkable performance. The remarkable electrochemical performance of CoS2/MoS2@N-C electrode could be assigned to the synergistic enhancement effect of the N-doped carbon coating and hollow structure, which efficiently shorten the ion diffusion path, boost the charge transfer rate, and alleviated the volume changes of the electrode upon cycling.

Lithium–sulfur (Li–S) batteries as among the most promising energy storage devices possess high theoretical capacity and energy density but suffer from the polysulfide dissolution, which hinders their practical application. Herein, we present a facile synthesis of hollow carbon nanoballs (HCNBs) anchored with ultrafine TiO2nanoparticles (TiO2@HCNBs) in which the HCNBs with hollow interiors and graphitic crystallization accommodate the volume expansion of sulfur upon lithiation and improve the cathode conductivity, while the TiO2nanoparticles effectively trap the polysulfides through strong chemical bonding. Notably, the S@TiO2@HCNBs with a high sulfur loading of ∼73 wt % demonstrate superior cycle performance at 0.5 C over 600 cycles with a slow capacity decay and deliver high specific capacities of 1217, 1013, 893, and 773 mA h/g at 0.1, 0.2, 0.5, and 1 C, respectively. The adsorption test clearly reveals the efficient suppression of the polysulfide shuttling owing to the spatial and chemical confinement of the TiO2@HCNBs host.

Titanium dioxide (TiO2) has been widely investigated as a candidate for anode materials of sodium-ion batteries (SIBs) due to its low cost and high abundance. However, the intrinsic sluggish ion/electron transfer rate hinders its practical applications for high energy density storage devices. In contrast, antimony (Sb) shows high specific theoretical capacity (660 mAh/g) as well as excellent electron conductivity, but the large volume variation upon cycling usually leads to severe capacity fading. Herein, with the objective of achieving high-performance sodium storage anode materials, TiO2@C-Sb nanotablets with a small amount of Sb content (6.4 wt%) are developed through calcination Ti-metal–organic framework (MIL-125) derived TiO2@C/SbCl3mixture under reductive atmosphere. Benefitting from the synergetic effect of well-dispersed Sb nanoparticles as well as robust porous TiO2@C substrate, the TiO2@C-Sb shows enhanced electron/ion transfer rate and predominantly pseudocapacitive sodium storage behavior, delivering a reversible capacity of 219 mAh/g at 0.5 A/g even after 1000 cycles. More significantly, this method may be commonly used to incorporate other alloy-based high-theoretical materials into MIL-125-derived TiO2@C, which is promising for developing high-energy-density TiO2-based energy storage devices.

We report a facile template-free fabrication of heterostructured Co3O4/CuO hollow nanospheres using pre-synthesized Co/Cu-glycerate as conformal precursor. The introduction of copper nitrate in the solvothermal reaction system of glycerol/isopropanol/cobalt nitrate readily induces the conversion from solid Co-glycerate to hollow Co/Cu-glycerate nanospheres, and the effect of the Co/Cu atomic ratio on the structure evolution of the metal glycerates as well as their corresponding oxides were investigated. When examined as anode materials for lithium-ion batteries, the well-defined Co3O4/CuO hollow nanospheres with Co/Cu molar ratio of 2.0 demonstrate excellent lithium storage performance, delivering a high reversible capacity of 930 mAh/g after 300 cycles at a current density of 0.5 A/g and a stable capacity of 650 mAh/g after 500 cycles even at a higher current density of 2.0 A/g, which are much better than their counterparts of bare CuO and Co3O4. The enhanced lithium storage performance can be attributed to the synergistic effect of the CuO and Co3O4heterostructure with hollow spherical morphology, which greatly enhances the charge/electrolyte transfer and effectively buffers the volume changes upon lithiation/delithiation cycling.

Transition metal phosphides are emerging as potential anode materials for lithium‐ion batteries (LIBs) due to their high theoretical capacity and good thermal stability, but the severe volume changes during the charge/discharge process and low electrical conductivity have hampered their practical application. Herein, the facile synthesis of carbon‐coated CoP nanoparticles (CoP@C) with uniform spherical morphology is demonstrated through the solvothermal method followed by annealing and phosphating treatments, in which an interesting precursor, the Co–gluconate complex, is prepared as the Co/C sources. When used as the LIB anode, the CoP@C electrode displays excellent cycling stability with a reversible capacity of 483.4 mA h g−1upon 1000 cycles at 0.5 A g−1. The superior lithium storage performance is attributed to the unique composite structure of CoP@C with the nanosized CoP particles wrapped into the carbon matrices, which can enhance the electrical conductivity, provide sufficient reaction sites, shorten the Li+transport path, and buffer the volume changes of the electrode upon lithiation/delithiation. More importantly, the strategy of generating gluconate–metal complex as the metal‐ and carbon‐containing precursor can be widely applied in the synthesis of various functional materials for energy‐related applications. Uniform cobalt gluconate nanospheres are prepared by a facile solvothermal method, which serve as precursors for the synthesis of carbon coated CoP (CoP@C) nanoparticles through phosphating treatment. When examined as an anode for lithium‐ion batteries, the CoP@C demonstrated superior lithium storage properties.

Dissolution of intermediate sodium polysulfides (Na2Sx; 4≤x≤8) is a crucial obstacle for the development of room-temperature sodium-sulfur (Na–S) batteries. One promising strategy to avoid this issue is to load short-chain sulfur (S2–4), which could prohibit the generation of soluble polysulfides during the sodiation process. Herein, unlike in the previous reported cases where short-chain sulfur was stored by confinement within a small-pore-size (≤0.5 nm) carbon host, we report a new strategy to generate short-chain sulfur in larger pores (>0.5 nm) by the synergistic catalytic effect of CoS2and appropriate pore size. Based on density functional theory calculations, we predict that CoS2can serve as a catalyst to weaken the S–S bond in the S8ring structure, facilitating the formation of short-chain sulfur molecules. By experimentally tuning the pore size of the CoS2-based hosts and comparing their performances as cathodes in Na–S and Li–S batteries, we conclude that such a catalytic effect depends on the proximity of sulfur to CoS2. This avoids the generation of soluble polysulfides and results in superior electrochemical properties of the composite materials introduced here for Na–S batteries. As a result, the optimized CoS2/N-doped carbon/S electrode showed excellent electrochemical performance with high reversible specific capacities of 488 mA h g–1(962 mA h g(s)–1) after 100 cycles (0.1 A g–1) and 403 mA h g–1after 1000 cycles (1 A g–1) with a superior rate performance (262 mA h g–1at 5.0 A g–1).