•Hierarchical V2O5 nanosheets are firmly grown on surface-decorated carbon cloth.•The polydopamine plays a pivotal role in the formation of robust flexible cathode.•The flexible cathode exhibits superior mechanical strength and LIBs performances.The search for an appropriate flexible cathode is pivotal to expediting the development of flexible and foldable lithium-ion batteries (LIBs). Herein, we demonstrate a simple and scalable synthesis of hierarchical V2O5 nanosheet arrays on polydopamine (PDA)-decorated carbon cloth with strong combination between them, which then directly applied as flexible cathode for LIBs. We found this flexible cathode with a loading mass of 2.1 mg cm−2 can deliver a high specific capacity of 120 mAh g−1 even at 15C (1C = 300 mA g−1) and maintain a long-term cycling stability, i.e. simply 0.30% capacity loss per cycle at 2C for 100 cycles without morphology change. More importantly, the corresponding areal capacity can reach as high as 560 μAh cm−2 at 210 μA cm−2, favorably comparing with the-state-of-art flexible cathode reported to date. Additionally, a flexible LIBs full cell has been assembled, exhibiting high mechanical strength and superior electrochemical performances.Download high-res image (202KB)Download full-size image

The exploitation of high-capacity and long-life MoS2-based materials is highly important for developing lithium ion batteries (LIBs) and sodium ion batteries (SIBs). Herein, we demonstrate the confined synthesis of 2D MoS2/polyaniline (MoS2/PANI) nanosheet heterostructures with well-defined interfaces, in which the interlayer distance of MoS2 is greatly enlarged from 0.62 nm to 1.08 nm. The introduction of such a big interlayer distance for efficient Li+/Na+ storage has never been demonstrated before. The unique MoS2/PANI nanosheets can address well the key challenges of traditional MoS2 anode materials related to low conductivity particularly in the vertical direction, easy restacking/aggregation, large volumetric change and sluggish Li+/Na+ diffusion kinetics in the interlamination. Consequently, they deliver a high reversible capacity, superior rate capability and long cycle life for both LIBs and SIBs. A state-of-the-art ab initio molecular dynamics (AIMD) simulation also reveals that MoS2/PANI nanosheets with enlarged interlayer spacing possess a remarkably improved Li+/Na+ diffusion mobility compared to pristine MoS2 nanosheets. The present material design concept opens new directions for finding efficient LIBs/SIBs anodes with high capacity, rate capability and stability.

Constructing 3D hierarchical architecture consisting of 2D hybrid nanosheets is very critical to achieve uppermost and stable electrochemical performance for both lithium-ion batteries (LIBs) and hydrogen evolution reaction (HER). Herein, a simple synthesis of uniform 3D microspheres assembled from carbon nanosheets with the incorporated MoO2 nanoclusters is demonstrated. The MoO2 nanoclusters can be readily converted into the molybdenum carbide (Mo2C) nanocrystals by using high temperature treatment. Such assembling architecture is highly particular for preventing Mo-based ultrasmall nanoparticles from coalescing or oxidizing and endowing them with rapid electron transfer. Consequently, the MoO2/C hybrids as LIB anode materials deliver a specific capacity of 625 mA h g−1 at 1600 mA g−1 even after 1000 cycles, which is among the best reported values for MoO2-based electrode materials. Moreover, the Mo2C/C hybrids also exhibit excellent electrocatalytic activity for HER with small overpotential and robust durability in both acid and alkaline media. The present work highlights the importance of designing 3D structure and controlling ultrasmall Mo-based nanoparticles for enhancing electrochemical energy conversion and storage applications.

Searching for efficient and robust non-noble electrocatalysts for hydrogen generation is extremely desirable for future green energy systems. Here, we present the synthesis of integrated Ni-P-S nanosheets array including Ni2P and NiS on nickel foam by a simple simultaneous phosphorization and sulfurization strategy. The resultant sample with optimal composition exhibits superior electrocatalytic performance for hydrogen evolution reaction (HER) in a wide pH range. In alkaline media, it can generate current densities of 10, 20 and 100 mA cm−2 at low overpotentials of only −101.9, −142.0 and −207.8 mV with robust durability. It still exhibits high electrocatalytic activities even in acid or neutral media. Such superior electrocatalytic performances can be mainly attributed to the synergistic enhancement of the hybrid Ni-P-S nanosheets array with integration microstructure. The kind of catalyst gives a new insight on achieving efficient and robust hydrogen generation.The integrated Ni-P-S nanosheets array has been demonstrated by a simple simultaneous phosphorization and sulfurization strategy, exhibiting superior electrocatalytic performances for hydrogen evolution reaction in a wide pH range.Download high-res image (229KB)Download full-size image

•The carbon cloths are modified by micro-area etching and functionalization.•The maximal 2D heterointerface greatly improves sodium storage capacity.•The enlarged interlayer space of 0.99 nm enhances the diffusion kinetics of Na+.•An ultrastable capacity retention is achieved for over 10000 cycles.Development of ultra-stable high capacity electrodes is imperative for the widespread commercialization of sodium-ion batteries. Herein, we employed a micro-area etching and surface functionalization strategy to synthesize two-dimensional (2D) MoS2/C nanosheets with a well-defined heterointerface vertically anchored on a carbon cloth. The large MoS2/C nanosheet heterointerface and a high interlayer distance (0.99 nm) not only facilitated Na+ intercalation but also improved the diffusion kinetics of Na+ in the 2D interlayer space. A modulation of the cut-off voltage yielded a high specific capacity of 433 mAh g−1 at 0.2 A g−1 and 232 mAh g−1 at 10 A g−1 within the potential range of 0.4–3.0 V. These values are much higher than that of pure MoS2 nanosheet arrays (162 mAh g−1 at 10 A g−1). More importantly, during the first 1500 cycles, the capacity was maintained at ∼320 mAh g−1 at 1 A g−1, while after 10000 cycles, it became approximately ∼271 mAh g−1 at 3 A g−1. These are the best values ever reported for MoS2-based anode materials for SIBs. Furthermore, after being assembled into a flexible battery, it withstand repeated bending for over 200 times without any obvious capacity loss. Hence, this material is a promising electrode for future flexible batteries.Download high-res image (99KB)Download full-size image

Rational construction of metal oxides-based electrode materials for Li-ion batteries (LIBs) is essential to simultaneously overcome their low conductivity and vulnerable nanostructure. Here, we demonstrate the design and synthesis of homologous V2O3/C box-in-box and V2O5 boxes as anodes and cathodes for all-nanobox based LIB full cells, which are subsequently obtained by thermal treatment in different atmospheres. While the V2O5 box cathodes can provide abundant active sites, short ionic diffusion distances and partial volume flexibility, the key design concept of the V2O3/C box-in-box is the carbon box-in-box, which further enhances the structural durability during lithiation/delithiation, hence giving rise to an extended lifespan. As proof-of-concept, the V2O3/C box-in-box anodes deliver a high reversible capacity of 641 mA h g−1 even after 1200 cycles at 1000 mA g−1, while the V2O5 box cathodes possess a specific capacity of 119 mA h g−1 at 10C with superior cycling stability. Importantly, a V2O3/C//V2O5 LIB full cell is assembled, which shows an impressive specific capacity of 97 mA h g−1 at 500 mA g−1 with a capacity retention of 81 mA h g−1 even after 100 cycles based on the cathode material weight.

•Silicon hollow nanosheets are synthesized by a magnesiothermic reduction strategy.•A flexible freestanding Si/rGO film has been realized by layer-by-layer assembly.•The durable Si/rGO film anode shows intriguing performances in a flexible full LIB.The fabrication of flexible freestanding electrodes with superior electrochemical performance is challenging now in consumer electronics miniaturization. Herein, we demonstrate a simple and scalable synthesis of hollow silicon nanosheets, which then hybridizes with rGO into flexible films by layer-by-layer assembly process. The resulting Si/rGO films, when applied as a free-standing LIBs anode, exhibit a high reversible specific capacity of 904 mAh g−1 at 200 mA g−1 (about 2 times higher than theoretical value of graphite anode), and meanwhile maintain a long cycle life (650 mAh g−1 after 150 cycles). In addition, a flexible full battery has also been assembled based on the flexible film as an anode and the commercial LiCoO2 as a cathode, which impressively delivers a high specific capacity of 700 and 613 mAh g−1 at 50 mA g−1 after 15 cycles in flat and bent state, respectively. Such intriguing electrochemical performances can be mainly attributed to the two-dimensional hollow nanostructure of silicon and their strong synergistic effect with rGO. It is reckoned that our Si/rGO films are a promising anode for advanced flexible LIBs.

To address the large volume change and polysulfide dissolution of FeS2-based materials for lithium-ion batteries (LIBs), we demonstrate the synthesis of FeS2 nanoparticles encapsulated in carbon nanotubes (CNTs) by a confined reaction. There is sufficient void space between adjacent FeS2 nanoparticles for guaranteeing the highly structural integrity. The resultant FeS2/CNT hybrids, when served as anode materials for LIBs, predictably exhibit a very stable capacity retention of 800 mAh g–1 over 200 cycles at 200 mA g–1. Even at 2000 mA g–1, they still deliver high-rate and long-life performance with a high specific capacity of 525 mAh g–1 after 1000 cycles. Such a kind of encapsulated structure is helpful for enhancing rate capability and cycling stability in LIBs applications. Importantly, the present confined reaction strategy can be extensively applied to synthesize other analogous hybrids for energy storage and conversion.Keywords: Confined synthesis; Encapsulated structure; FeS2; Lithium-ion batteries

The preparation of few-layered ultrasmall MoS2 nanosheets inlayed into carbon frameworks is challenging to date. Herein, we realize the synthesis of such meaningful nanohybrids (labeled as MoS2/CFs hybrids) by a simple salt-templating protocol, where NaCl particles are chosen as a sacrificial template to grow MoS2 crystals on the surface during the glucose carbonization, which meanwhile effectively inhibits their growth and stacking. In regard to electrochemical energy storage and conversion, the resulting MoS2/CFs hybrids are beneficial for providing substantial and accessible electroactive sites as well as rapid electrons/ions transfer. The present hybrids, when applied as lithium-ion batteries anode materials, exhibit a remarkably enhanced reversible specific capacity as high as 1083.5 mAh g–1 at 200 mA g–1 with fast charge/discharge capability (465.4 mAh g–1 at 6400 mA g–1), which is much higher than the exfoliated MoS2 nanosheets (only 97.6 mAh g–1 at 6400 mA g–1) and the commercial graphite. More impressively, our MoS2/CFs hybrids simultaneously possess a superior cycle life with negligible capacity loss after 400 cycles at 1600 mA g–1. In addition to the excellent lithium ion storage, our MoS2/CFs hybrids may concurrently exhibit some intriguing properties for applications in other energy-related fields.Keywords: Carbon frameworks; Few-layered MoS2; Lithium-ion battery; Nanohybrids; Salt-templating

We demonstrate the synthesis of ultrathin MnO2 nanoflakes grown on N-doped carbon nanoboxes, forming an impressive hierarchical MnO2/C nanobox hybrid with an average size of 500 nm, which exhibits an excellent electrochemical performance due to the unique structure, N-doping and strong synergistic effects between them. In addition, we also assembled a green asymmetric supercapacitor (ASC) using the as-synthesized MnO2/C nanoboxes as a positive electrode and the corresponding N-doped carbon nanoboxes as a negative electrode in a neutral aqueous electrolyte, aiming to further enhance its energy density by extending the operating potential. More significantly, our ASC device is able to reversibly cycle within a wide operating voltage of 2.0 V and delivers a maximum energy density of 39.5 W h kg−1 with superior cycling stability (∼90.2% capacitance retention after 5000 cycles). These intriguing results show that hollow nanostructures will be promising electrode materials for advanced supercapacitors.

The reciprocal hybridization of MoO2 nanoparticles and few-layer MoS2 has been realized via a facile hydrothermal reaction. The resulting MoO2/MoS2 hybrids exhibit a high reversible specific capacity of 1103 mA h g−1 at 0.2 A g−1 with a high rate performance (273 mA h g−1 at 6.4 A g−1) and an excellent cycling stability (∼92% capacity retention after 800 cycles) mainly due to the strong synergistic effect between them.

To overcome the poor cycling stability of LiMn2O4 cathode materials without sacrificing the specific capacity, we demonstrate a new strategy for synergistically enhancing their electrochemical performance by combining the advantages of Al doping and the exposure of highly active facets. Specifically, Al doping can suppress Mn dissolution in the electrolyte, leading to an outstanding cycling stability. In addition, the exposure of highly active facets can greatly enhance the specific capacity and rate capability, while also compensating for the capacity loss caused by Al doping. As a consequence, the as-prepared Al-doped LiMn2O4 truncated octahedrons exhibit a far superior performance in both rate capacity and cycling stability than the pure LiMn2O4 octahedrons and the LiMn2O4 truncated octahedrons. Our work is meaningful not only for the synthesis of high-performance LiAl0.1Mn1.9O4 truncated octahedrons, but also for providing new insight into the development of high-performance LiMn2O4 cathode materials.

In order to mitigate the drastic volumetric expansion (>300%) of silicon (Si) during the lithiation process, we demonstrate the synthesis of novel Si nanowire arrays (n-SNWAs) with a coral-like surface on Cu foam via a one-step CVD method, in which the Cu foam can simultaneously act as a catalyst and current collector. The unique coral-like surface endows n-SNWAs with a high structural integrity, which is beneficial for enhancing their electrochemical performance. In addition, the as-prepared n-SNWAs on Cu foam can be directly applied as the anode for lithium-ion batteries (LIBs), exhibiting a very high reversible discharge capacity (2745 mA h g−1 at 200 mA g−1) and a fast charge and discharge capability (884 mA h g−1 at 3200 mA g−1), which is much higher than the conventional SNWAs (c-SNWAs, only 127 mA h g−1 at 3200 mA g−1). Meanwhile, they deliver an improved cycling stability (2178 mA h g−1 at 400 mA g−1 after 50 cycles). More significantly, the as-synthesized n-SNWAs on Cu foam also possess a superior specific areal capacity of 4.1 mA h cm−2 at 0.6 mA cm−2. Such excellent electrochemical performance is superior, or at least comparable, to the best report for Si anode materials. Combining the cost-effective and facile preparation method, the present n-SNWAs on Cu foam can serve as a promising anode for LIBs.

Mesoporous single-crystalline V2O5 nanorods assembled into novel hollow microspheres have been synthesized as cathode materials for lithium-ion batteries by a simple solvothermal treatment of NH4VO3 and ethylene glycol with subsequent annealing in air at 400 °C, which delivered a very high reversible capacity of 145.8 mA h g−1 at 2.5–4.0 V (vs. theoretical value: 147 mA h g−1) with much improved capacity retention and long cycle life at various rates.

Mesoporous single crystals Li4Ti5O12 grown on reduced graphene oxide (MSCs-LTO–rGO) nanohybrids have been synthesized by a simple hydrothermal reaction of TiO2/rGO and LiOH with subsequent annealing in Ar at 600 °C, which exhibited high specific capacity (171 mA h g−1) with much improved rate capability (132 mA h g−1 at 40 C) and intriguing cycling stability (85% capacity retention after 2000 cycles).

•Hierarchical porous Li4Mn5O12 nano/micro structure has been synthesized.•The unique structure has the advantages of both nanostructure and microstructure.•The Li4Mn5O12 cathode exhibits excellent electrochemical performances for LIBs.To overcome the disproportionation reaction and Jahn-Teller distortion of Mn3+ in LiMn2O4 cathode materials, we demonstrate a facile route to synthesize hierarchical porous Li4Mn5O12 nano/micro structure, which consists of numerous well-crystallized nanoparticles with diameters of 20–30 nm. The unique structure combines the advantages of both nanostructure and microstructure. When applied as cathode materials for Li-ion batteries, it exhibited a very high specific capacity of 161 mAh g−1 (theoretical value: 163 mAh g−1) with intriguing rate performance and cycling stability.

Ultrathin, uniform and monodisperse hollow mesoporous carbon nanospheres (HMCNs) with a thickness of ∼3.8 nm have been synthesized. The obtained HMCNs have a high specific surface area (568 m2 g–1), large pore volume (1.63 cm3 g–1), and highly accessible mesopores (∼9.1 nm). Notably, we realized precise control of the shell thickness in the range of ultrathin size (<10 nm). When applied as supercapacitor electrodes, the HMCNs demonstrate impressive capacitive properties, such as high specific capacitance (253 F g–1), excellent rate capability (111 F g–1 at 60 A g–1) and outstanding cycling stability (only 3.8% loss after 5000 cycles). The results suggest that the unique structure of HMCNs can allow high rate electrolyte infiltration and rapid ion diffusion. The present findings push forward the development of carbon materials, exhibiting huge potential for applications in energy storage fields.

We demonstrate the self-assembly of few-layer MoS2 nanosheets on a CNT backbone via a facile hydrothermal reaction with a subsequent annealing process. In this structure, the few-layer MoS2 nanosheets with controllable contents are alternately and vertically grown on the surface of CNTs, forming a three-dimensional hierarchical nanostructure. The optimized MoS2/CNTs hybrids could be applied as a fascinating anode material for high-rate and long cycle life lithium ion batteries (LIBs). Compared with the commercial MoS2 (716 mA h g−1), the as-prepared MoS2/CNTs hybrids exhibit a much higher specific capacity of 1293 mA h g−1 at 200 mA g−1 with remarkably enhanced rate capability (888 mA h g−1 even at 3200 mA g−1). More significantly, we find that the MoS2/CNTs hybrids show no capacity fading after 200 cycles at 400 mA g−1. As for MoS2-based anode materials, such overwhelming electrochemical performance endows the present MoS2/CNTs hybrids with huge potential for developing LIBs.

Novel Mn2O3 hollow nanocones have been successfully prepared as a lithium ion batteries anode material by a hydrothermal then annealing process, which exhibited a high specific capacity of ∼900 mA h g−1 at 50 mA g−1 with intriguing rate performance and cycling stability.

The reciprocal hybridization of MoO2 nanoparticles and few-layer MoS2 has been realized via a facile hydrothermal reaction. The resulting MoO2/MoS2 hybrids exhibit a high reversible specific capacity of 1103 mA h g−1 at 0.2 A g−1 with a high rate performance (273 mA h g−1 at 6.4 A g−1) and an excellent cycling stability (∼92% capacity retention after 800 cycles) mainly due to the strong synergistic effect between them.

Mesoporous single crystals Li4Ti5O12 grown on reduced graphene oxide (MSCs-LTO–rGO) nanohybrids have been synthesized by a simple hydrothermal reaction of TiO2/rGO and LiOH with subsequent annealing in Ar at 600 °C, which exhibited high specific capacity (171 mA h g−1) with much improved rate capability (132 mA h g−1 at 40 C) and intriguing cycling stability (85% capacity retention after 2000 cycles).

Rational construction of metal oxides-based electrode materials for Li-ion batteries (LIBs) is essential to simultaneously overcome their low conductivity and vulnerable nanostructure. Here, we demonstrate the design and synthesis of homologous V2O3/C box-in-box and V2O5 boxes as anodes and cathodes for all-nanobox based LIB full cells, which are subsequently obtained by thermal treatment in different atmospheres. While the V2O5 box cathodes can provide abundant active sites, short ionic diffusion distances and partial volume flexibility, the key design concept of the V2O3/C box-in-box is the carbon box-in-box, which further enhances the structural durability during lithiation/delithiation, hence giving rise to an extended lifespan. As proof-of-concept, the V2O3/C box-in-box anodes deliver a high reversible capacity of 641 mA h g−1 even after 1200 cycles at 1000 mA g−1, while the V2O5 box cathodes possess a specific capacity of 119 mA h g−1 at 10C with superior cycling stability. Importantly, a V2O3/C//V2O5 LIB full cell is assembled, which shows an impressive specific capacity of 97 mA h g−1 at 500 mA g−1 with a capacity retention of 81 mA h g−1 even after 100 cycles based on the cathode material weight.

The exploitation of high-capacity and long-life MoS2-based materials is highly important for developing lithium ion batteries (LIBs) and sodium ion batteries (SIBs). Herein, we demonstrate the confined synthesis of 2D MoS2/polyaniline (MoS2/PANI) nanosheet heterostructures with well-defined interfaces, in which the interlayer distance of MoS2 is greatly enlarged from 0.62 nm to 1.08 nm. The introduction of such a big interlayer distance for efficient Li+/Na+ storage has never been demonstrated before. The unique MoS2/PANI nanosheets can address well the key challenges of traditional MoS2 anode materials related to low conductivity particularly in the vertical direction, easy restacking/aggregation, large volumetric change and sluggish Li+/Na+ diffusion kinetics in the interlamination. Consequently, they deliver a high reversible capacity, superior rate capability and long cycle life for both LIBs and SIBs. A state-of-the-art ab initio molecular dynamics (AIMD) simulation also reveals that MoS2/PANI nanosheets with enlarged interlayer spacing possess a remarkably improved Li+/Na+ diffusion mobility compared to pristine MoS2 nanosheets. The present material design concept opens new directions for finding efficient LIBs/SIBs anodes with high capacity, rate capability and stability.

We demonstrate the synthesis of ultrathin MnO2 nanoflakes grown on N-doped carbon nanoboxes, forming an impressive hierarchical MnO2/C nanobox hybrid with an average size of 500 nm, which exhibits an excellent electrochemical performance due to the unique structure, N-doping and strong synergistic effects between them. In addition, we also assembled a green asymmetric supercapacitor (ASC) using the as-synthesized MnO2/C nanoboxes as a positive electrode and the corresponding N-doped carbon nanoboxes as a negative electrode in a neutral aqueous electrolyte, aiming to further enhance its energy density by extending the operating potential. More significantly, our ASC device is able to reversibly cycle within a wide operating voltage of 2.0 V and delivers a maximum energy density of 39.5 W h kg−1 with superior cycling stability (∼90.2% capacitance retention after 5000 cycles). These intriguing results show that hollow nanostructures will be promising electrode materials for advanced supercapacitors.

Mesoporous single-crystalline V2O5 nanorods assembled into novel hollow microspheres have been synthesized as cathode materials for lithium-ion batteries by a simple solvothermal treatment of NH4VO3 and ethylene glycol with subsequent annealing in air at 400 °C, which delivered a very high reversible capacity of 145.8 mA h g−1 at 2.5–4.0 V (vs. theoretical value: 147 mA h g−1) with much improved capacity retention and long cycle life at various rates.