Silicon is considered an exceptionally promising alternative to the most commonly used material, graphite, as an anode for next-generation lithium-ion batteries, as it has high energy density owing to its high theoretical capacity and abundant storage. Here, microsized walnut-like porous silicon/reduced graphene oxide (P-Si/rGO) core–shell composites are successfully prepared via in situ reduction followed by a dealloying process. The composites show specific capacities of more than 2,100 mAh·g?1 at a current density of 1,000 mA·g?1, 1,600 mAh·g?1 at 2,000 mA·g?1, 1,500 mAh·g?1 at 3,000 mA·g?1, 1,200 mAh·g?1 at 4,000 mA·g?1, and 950 mAh·g?1 at 5,000 mA·g?1, and maintain a value of 1,258 mAh·g?1 after 300 cycles at a current density of 1,000 mA·g?1. Their excellent rate performance and cycling stability can be attributed to the unique structural design: 1) The graphene shell dramatically improves the conductivity and stabilizes the solid–electrolyte interface layers; 2) the inner porous structure supplies sufficient space for silicon expansion; 3) the nanostructure of silicon can prevent the pulverization resulting from volume expansion stress. Notably, this in situ reduction method can be applied as a universal formula to coat graphene on almost all types of metals and alloys of various sizes, shapes, and compositions without adding any reagents to afford energy storage materials, graphene-based catalytic materials, graphene-enhanced composites, etc.
Iron sulfide is an attractive anode material for lithium-ion batteries (LIBs) due to its high specific capacity, environmental benignity, and abundant resources. However, its application is hindered by poor cyclability and rate performance, caused by a large volume variation and low conductivity. Herein, iron sulfide porous nanowires confined in an N-doped carbon matrix (FeS@N-C nanowires) are fabricated through a simple amine-assisted solvothermal reaction and subsequent calcination strategy. The as-obtained FeS@N-C nanowires, as an LIB anode, exhibit ultrahigh reversible capacity, superior rate capability, and long-term cycling performance. In particular, a high specific capacity of 1,061 mAh·g?1 can be achieved at 1 A·g?1 after 500 cycles. Most impressively, it exhibits a high specific capacity of 433 mAh·g?1 even at 5 A·g?1. The superior electrochemical performance is ascribed to the synergistic effect of the porous nanowire structure and the conductive N-doped carbon matrix. These results demonstrate that the synergistic strategy of combining porous nanowires with an N-doped carbon matrix holds great potential for energy storage.
Germanium-based oxide has been found to be a promising high-capacity anode material for lithium-ion batteries (LIBs). However, it exhibits poor electrochemical performance because of the drastic volume change during cycling. Herein, we designed porous Ge-Fe bimetal oxide nanowires (Ge-Fe-Ox-700 NWs) by a large-scale and facile solvothermal reaction. When used as the anode material for LIBs, these Ge-Fe-Ox-700 NWs exhibited superior electrochemical performance (～ 1,120 mAh·g?1 at a current density of 100 mA·g?1) and good cycling performance (～ 750 mAh·g?1 after 50 cycles at a current density of 100 mA·g?1). The improved performance is due to the small NW diameter, which allows for better accommodation of the drastic volume changes and zero-dimensional nanoparticles, which shorten the diffusion length of ions and electrons.
Mixed transition metal oxides (MTMOs) have received intensive attention as promising anode materials for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). In this work, we demonstrate a facile one-step water-bath method for the preparation of graphene oxide (GO) decorated Fe2(MoO4)3 (FMO) microflower composite (FMO/GO), in which the FMO is constructed by numerous nanosheets. The resulting FMO/GO exhibits excellent electrochemical performances in both LIBs and SIBs. As the anode material for LIBs, the FMO/GO delivers a high capacity of 1,220 mAh·g–1 at 200 mA·g–1 after 50 cycles and a capacity of 685 mAh·g–1 at a high current density of 10 A·g–1. As the anode material for SIBs, the FMO/GO shows an initial discharge capacity of 571 mAh·g–1 at 100 mA·g–1, maintaining a discharge capacity of 307 mAh·g–1 after 100 cycles. The promising performance is attributed to the good electrical transport from the intimate contact between FMO and graphene oxide. This work indicates that the FMO/GO composite is a promising anode for high-performance lithium and sodium storage.
Si has been considered as a promising anode material but its practical application has been severely hindered due to poor cyclability caused by the large volume change during charge/discharge. A new and effective protocol has been developed to construct Si nanoparticle/graphene electrodes with a favorable structure to alleviate this problem. Starting from a stable suspension of Si nanoparticles and graphene oxide in ethanol, spin-coating can be used as a facile method to cast a spin-coated Si nanoparticle/graphene (SC-Si/G) film, in which graphene can act as both an efficient electronic conductor and effective binder with no need for other binders such as polyvinylidenefluoride (PVDF) or polytetrafluoroethylene (PTFE). The prepared SC-Si/G electrode can achieve a high-performance as an anode for lithium-ion batteries benefiting from the following advantages: i) the graphene enhances the electronic conductivity of Si nanoparticles and the void spaces between Si nanoparticles facilitate the lithium ion diffusion, ii) the flexible graphene and the void spaces can effectively cushion the volume expansion of Si nanoparticles. As a result, the binder-free electrode shows a high capacity of 1611 mA·h·g?1 at 1 A·g?1 after 200 cycles, a superior rate capability of 648 mA·h·g?1 at 10 A·g?1, and an excellent cycle life of 200 cycles with 74% capacity retention. 相似文献
Earth abundant and economical rock salt (NaCl) particles of different sizes (<3 μm and 5–20 μm) prepared by high energy mechanical milling were used as water-soluble templates for generation of Si with novel nanoscale architectures via low pressure chemical vapor deposition (LPCVD). Si nanoflakes (SiNF) comprising largely amorphous Si (a-Si) with a small volume fraction of nanocrystalline Si (nc-Si), and Si nanorods (SiNR) composed of a larger volume fraction of crystalline Si (c-Si) and a small volume fraction of a-Si resulted from modification of the NaCl crystals. SiNF yielded first-cycle discharge and charge capacities of ～2,830 and 2,175 mAh·g?1, respectively, at a current rate of 50 mA·g?1 with a first-cycle irreversible loss (FIR loss) of ～15%–20%. SiNR displayed first-cycle discharge and charge capacities of ～2,980 and ～2,500 mAh·g?1, respectively, at a current rate of 50 mA·g?1 with an FIR loss of ～12%–15%. However, at a current rate of 1 A·g?1, SiNF exhibited a stable discharge capacity of ～810 mAh·g?1 at the end of 250 cycles with a fade rate of ～0.11% loss per cycle, while SiNR showed a stable specific discharge capacity of ～740 mAh·g?1 with a fade rate of ～0.23% loss per cycle. The morphology of the nanostructures and compositions of the different phases/phase of Si influence the performance of SiNF and SiNR, making them attractive anodes for lithium-ion batteries.
Current research on vanadium oxides in lithium ion batteries (LIBs) considers them as cathode materials, whereas they are rarely studied for use as anodes in LIBs because of their low electrical conductivity and rapid capacity fading. In this work, hydrogenated vanadium oxide nanoneedles were prepared and incorporated into freeze-dried graphene foam. The hydrogenated vanadium oxides show greatly improved charge-transfer kinetics, which lead to excellent electrochemical properties. When tested as anode materials (0.005–3.0 V vs. Li/Li+) in LIBs, the sample activated at 600 °C exhibits high specific capacity (～941 mA·h·g?1 at 100 mA·g?1) and high-rate capability (～504 mA·h·g?1 at 5 A·g?1), as well as excellent cycling performance (～285 mA·h·g?1 in the 1,000th cycle at 5 A·g?1). These results demonstrate the promising application of vanadium oxides as anodes in LIBs.
Herein, hierarchically structured SnO2 microspheres are designed and synthesized as an efficient anode material for lithium-ion batteries using hollow SnO2 nanoplates. Three-dimensionally ordered macroporous (3-DOM) SnOx-C microspheres synthesized by spray pyrolysis are transformed into hierarchically structured SnO2 microspheres by a two-step post-treatment process. Sulfidation produces hierarchically structured SnS-SnS2-C microspheres comprising tin sulfide nanoplate and carbon building blocks. A subsequent oxidation process produces SnO2 microspheres from hollow SnO2 nanoplate building blocks, which are formed by Kirkendall diffusion. The discharge capacity of the hierarchically structured SnO2 microspheres at a current density of 5 A·g?1 for the 600th cycle is 404 mA·h·g?1. The hierarchically structured SnO2 microspheres have reversible discharge capacities of 609 and 158 mA·h·g?1 at current densities of 0.5 and 30 A·g?1, respectively. The ultrafine nanosheets contain empty voids that allow excellent lithium-ion storage performance, even at high current densities.
Scrupulous design and fabrication of advanced electrode materials are vital for developing high-performance sodium ion batteries. Herein, we report a facile one-step hydrothermal strategy for construction of a C-MoSe2/rGO composite with both high porosity and large surface area. Double modification of MoSe2 nanosheets is realized in this composite by introducing a reduced graphene oxide (rGO) skeleton and outer carbon protective layer. The MoSe2 nanosheets are well wrapped by a carbon layer and also strongly anchored on the interconnected rGO network. As an anode in sodium ion batteries, the designed C-MoSe2/rGO composite delivers noticeably enhanced sodium ion storage, with a high specific capacity of 445 mAh·g-1 at 200 mA·g-1 after 350 cycles, and 228 mAh·g-1 even at 4 A·g-1; these values are much better than those of C-MoSe2 nanosheets (258 mAh·g-1 at 200 mA·g-1 and 75 mAh·g-1 at 4 A·g-1). Additionally, the sodium ion storage mechanism is investigated well using ex situ X-ray diffraction and transmission electron microscopy methods. Our proposed electrode design protocol and sodium storage mechanism may pave the way for the fabrication of other high-performance metal diselenide anodes for electrochemical energy storage.
PX-phase PbTiO3 (PT) nanowires with open channels running along the length direction have been investigated as an anode material for lithium ion batteries. This material shows a stabilized reversible specific capacity of about 410 mAh·g–1 up to 200 cycles with a charge/discharge voltage plateau of around 0.3–0.65 V. In addition, it exhibits superior high-rate performance, with 90% and 77% capacity retention observed at 1 and 2 A·g–1, respectively. At a very high current rate of 10 A·g–1, a specific capacity of over 170 mAh·g–1 is retained up to 100 cycles, significantly outperforming the rate capability reported for Pb and Pb oxides. The results of X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) analyses along with the cyclic voltammogram results reveal that the PX-phase PT nanowires undergo irreversible structural amorphization and reduction reactions during the initial cycle, which allow them to transform into a composite structure composed of 2–5 nm Pb nanoparticles uniformly dispersed in the 1D amorphous Li2O·TiO2·LiTiO2 matrix. In this composite structure, the presence of abundant amounts of Ti3+ in both the charged and discharged states enhances the electrical conductance of the system, whereas the presence of ultrafine Pb nanoparticles imparts high reversible capacity. The structurally stable TiO2-based amorphous matrix can also considerably buffer the volume variation during the charge/discharge process, thereby facilitating extremely stable cycling performance. This compound combines the high specific capacity of Pb-based materials and the good rate capability of Ti3+-based wiring. Our results might furnish a possible route for achieving superior cycling and rate performance and contribute towards the search for next-generation anode materials.
Lithium-ion batteries (LIBs) are currently recognized as one of the most popular power sources available. To construct advanced LIBs exhibiting long-term endurance, great attention has been paid to enhancing their poor cycle stabilities. As the performance of LIBs is dependent on the electrode materials employed, the most promising approach to improve their life span is the design of novel electrode materials. We herein describe the rational design of a three-dimensional (3D) porous MnO/C-N nanoarchitecture as an anode material for long cycle life LIBs based on their preparation from inexpensive, renewable, and abundant rapeseed pollen (R-pollen) via a facile immersion-annealing route. Remarkably, the as-prepared MnO/C-N with its optimized 3D nanostructure exhibited a high specific capacity (756.5 mAh·g?1 at a rate of 100 mA·g?1), long life span (specific discharge capacity of 513.0 mAh·g?1, ~95.16% of the initial reversible capacity, after 400 cycles at 300 mA·g?1), and good rate capability. This material therefore represents a promising alternative candidate for the high-performance anode of next-generation LIBs.
Nanomaterials with electrochemical activity are always suffering from aggregations, particularly during the high-temperature synthesis processes, which will lead to decreased energy-storage performance. Here, hierarchically structured lithium titanate/nitrogen-doped porous graphene fiber nanocomposites were synthesized by using confined growth of Li4Ti5O12 (LTO) nanoparticles in nitrogen-doped mesoporous graphene fibers (NPGF). NPGFs with uniform pore structure are used as templates for hosting LTO precursors, followed by high-temperature treatment at 800 °C under argon (Ar). LTO nanoparticles with size of several nanometers are successfully synthesized in the mesopores of NPGFs, forming nanostructured LTO/NPGF composite fibers. As an anode material for lithium-ion batteries, such nanocomposite architecture offers effective electron and ion transport, and robust structure. Such nanocomposites in the electrodes delivered a high reversible capacity (164 mAh·g–1 at 0.3 C), excellent rate capability (102 mAh·g–1 at 10 C), and long cycling stability.
Mesoporous Mn-Sn bimetallic oxide (BO) nanocubes with sizes of 15–30 nm show outstanding stable and reversible capacities in lithium ion batteries (LIBs), reaching 856.8 mAh·g–1 after 400 cycles at 500 mA·g–1 and 506 mAh·g–1 after 850 cycles at 1,000 mA·g–1. The preliminary investigation of the reaction mechanism, based on X-ray diffraction measurements, indicates the occurrence of both conversion and alloying–dealloying reactions in the Mn-Sn bimetallic oxide electrode. Moreover, Mn-Sn BO//LiCoO2 Li-ion full cells were successfully assembled for the first time, and found to deliver a relatively high energy density of 176.25 Wh·kg–1 at 16.35 W·kg–1 (based on the total weight of anode and cathode materials). The superior long-term stability of these materials might be attributed to their nanoscale size and unique mesoporous nanocubic structure, which provide short Li+ diffusion pathways and a high contact area between electrolyte and active material. In addition, the Mn-Sn BOs could be used as advanced sulfur hosts for lithium-sulfur batteries, owing to their adequate mesoporous structure and relatively strong chemisorption of lithium polysulfide. The present results thus highlight the promising potential of mesoporous Mn-Sn bimetallic oxides for application in Li-ion and Li-S batteries.
Sodium-ion batteries (SIBs) have great promise for sustainable and economical energy-storage applications. Nevertheless, it is a major challenge to develop anode materials with high capacity, high rate capability, and excellent cycling stability for them. In this study, FeSe2 clusters consisting of nanorods were synthesized by a facile hydrothermal method, and their sodium-storage properties were investigated with different electrolytes. The FeSe2 clusters delivered high electrochemical performance with an ether-based electrolyte in a voltage range of 0.5–2.9 V. A high discharge capacity of 515 mAh·g–1 was obtained after 400 cycles at 1 A·g–1, with a high initial columbic efficiency of 97.4%. Even at an ultrahigh rate of 35 A·g–1, a specific capacity of 128 mAh·g–1 was achieved. Using calculations, we revealed that the pseudocapacitance significantly contributed to the sodium-ion storage, especially at high current rates, leading to a high rate capability. The high comprehensive performance of the FeSe2 clusters makes them a promising anode material for SIBs.
A hybrid structure consisting of boron-doped porous carbon spheres and graphene (BPCS-G) has been designed and synthesized toward solving the polysulfide-shuttle problem, which is the most critical issue of current Li-S batteries. The proposed hybrid structure showing high surface area (870 m2·g?1) and high B-dopant content (6.51 wt.%) simultaneously offers both physical confinement and chemical absorption of polysulfides. On one hand, the abundant-pore structure ensures high sulfur loading, facilitates fast charge transfer, and restrains polysulfide migration during cycling. On the other hand, our density functional theory calculations demonstrate that the B dopant is capable of chemically binding polysulfides. As a consequence of such dual polysulfide confinement, the BPCS-G/S cathode prepared with 70 wt.% sulfur loading presents a high reversible capacity of 1,174 mAh·g?1 at 0.02 C, a high rate capacity of 396 mAh·g?1 at 5 C, and good cyclability over 500 cycles with only 0.05% capacity decay per cycle. The present work provides an efficient and cost-effective platform for the scalable synthesis of high-performance carbon-based materials for advanced Li-S batteries.
Rechargeable metal-iodine batteries are an emerging attractive electrochemical energy storage technology that combines metallic anodes with halogen cathodes. Such batteries using aqueous electrolytes represent a viable solution for the safety and cost issues associated with organic electrolytes. A hybrid-electrolyte battery architecture has been adopted in a lithium-iodine battery using a solid ceramic membrane that protects the metallic anode from contacting the aqueous electrolyte. Here we demonstrate an eco-friendly, low-cost zinc-iodine battery with an aqueous electrolyte, wherein active I2 is confined in a nanoporous carbon cloth substrate. The electrochemical reaction is confined in the nanopores as a single conversion reaction, thus avoiding the production of I3? intermediates. The cathode architecture fully utilizes the active I2, showing a capacity of 255 mAh·g?1 and low capacity cycling fading. The battery provides an energy density of ～ 151 Wh·kg?1 and exhibits an ultrastable cycle life of more than 1,500 cycles.
We report the synthesis and electrochemical sodium storage of cobalt disulfide (CoS2) with various micro/nano-structures. CoS2 with microscale sizes are either assembled by nanoparticles (P-CoS2) via a facile solvothermal route or nanooctahedrons constructed solid (O-CoS2) and hollow microstructures (H-CoS2) fabricated by hydrothermal methods. Among three morphologies, H-CoS2 exhibits the largest discharge capacities and best rate performance as anode of sodium-ion batteries (SIBs). Furthermore, H-CoS2 delivers a capacity of 690 mA·h·g?1 at 1 A·g?1 after 100 cycles in a potential range of 0.1–3.0 V, and ～240 mA·h·g?1 over 800 cycles in the potential window of 1.0–3.0 V. This cycling difference mainly lies in the two discharge plateaus observed in 0.1–3.0 V and one discharge plateau in 1.0–3.0 V. To interpret the reactions, X-ray diffraction (XRD) and transmission electron microscopy (TEM) are applied. The results show that at the first plateau around 1.4 V, the insertion reaction (CoS2 + xNa+ + xe? → NaxCoS2) occurs; while at the second plateau around 0.6 V, the conversion reaction (NaxCoS2 + (4 ? x) Na+ + (4 ? x)e? → Co + 2Na2S) takes place. This provides insights for electrochemical sodium storage of CoS2 as the anode of SIBs.
Two-dimensional (2D) materials have attracted enormous attention due to their functional applications in energy storage. In this work, a low-temperature molten-salt chemical exfoliation methodology is developed for producing free-standing 2D mesoporous Si through deintercalation of CaSi2 in excess molten AlCl3 at 195 °C. The average dimension of these sheets is 1.5 μm, and the thickness of a single sheet is approximately 10 nm. The as-prepared 2D Si has a Brunauer–Emmett–Teller surface area of 154 m2·g?1 and an average pore size of 5.87 nm. With this unique structure, the 2D Si exhibits superior Li-storage performance, including a reversible capacity of 2,974 mA·h·g?1 at 0.2 C, reversible capacities of 2,162, 1,947, and 1,527 mA·h·g?1 at 0.8, 2, and 5 C after 200 cycles, and a capacity retention of 357 mA·h·g?1 even at 30 C (90 A·g?1).
We report the facile, one-pot synthesis of 3-D urchin-like W18O49 nanostructures (U-WO) via a simple solvothermal approach. An excellent supercapacitive performance was achieved by the U-WO because of its large Brunauer–Emmett–Teller (BET) specific surface area (ca. 123 m2·g–1) and unique morphological and structural features. The U-WO electrodes not only exhibit a high rate-capability with a specific capacitance (Csp) of ~235 F·g–1 at a current density of 20 A·g–1, but also superior long-life performance for 1,000 cycles, and even up to 7,000 cycles, showing ~176 F·g–1 at a high current density of 40 A·g–1.
The assembly of hybrid nanomaterials has opened up a new direction for the construction of high-performance anodes for lithium-ion batteries (LIBs). In this work, we present a straightforward, eco-friendly, one-step hydrothermal protocol for the synthesis of a new type of Fe2O3-SnO2/graphene hybrid, in which zero-dimensional (0D) SnO2 nanoparticles with an average diameter of 8 nm and one-dimensional (1D) Fe2O3 nanorods with a length of ~150 nm are homogeneously attached onto two-dimensional (2D) reduced graphene oxide nanosheets, generating a unique point-line-plane (0D-1D-2D) architecture. The achieved Fe2O3-SnO2/graphene exhibits a well-defined morphology, a uniform size, and good monodispersity. As anode materials for LIBs, the hybrids exhibit a remarkable reversible capacity of 1,530 mA·g?1 at a current density of 100 mA·g?1 after 200 cycles, as well as a high rate capability of 615 mAh·g?1 at 2,000 mA·g?1. Detailed characterizations reveal that the superior lithium-storage capacity and good cycle stability of the hybrids arise from their peculiar hybrid nanostructure and conductive graphene matrix, as well as the synergistic interaction among the components.
