Ion Storage Performance Research Articles

Honeycomb‐Inspired Heterogeneous Bimetallic Co–Mo Oxide Nanoarchitectures for High‐Rate Electrochemical Lithium Storage

AbstractNanostructure engineering has been proved to be an efficient approach for improving electrochemical properties for energy storage by accommodating volume changes, facilitating rapid mass transport paths, and enlarging ion storage sites and interfaces. The well‐designed fine nanostructures, unfortunately, are usually destroyed during long‐term cycles and ultimately lose their structural advantages. Herein, stimulated by the extraordinary structural stability, robust mechanical properties, and salient ventilation capacity of natural honeycomb species, bioinspired heterogeneous bimetallic Co–Mo oxide (CoMoOx) nanoarchitectures assembled from 2D nanounits are successfully fabricated via a molybdenum‐mediated self‐assembly strategy for improving the rate capability of electrochemical lithium storage devices. Owing to the robust structural stability and the ultrathin 2D wall structure, CoMoOx nanostructures present well‐maintained honeycomb‐like structure, rapid capacitive insertion–desertion behaviors, and thus significantly enhanced lithium ion storage performance at high rates (5.0 A g−1). It is also revealed that the reversible transition of cobalt and molybdenum phases closely associated with the ultrathin 2D wall structures greatly contribute to the outstanding electrochemical lithium storage performances. This attractive integration of structural and functional advantages achieved by learning from nature offers new insights into the design of cost‐effective electrode materials for high‐performance energy devices.

Facile construction of hollow carbon nanosphere-interconnected network for advanced sodium-ion battery anode

Sodium-ion batteries are promising next-generation electrical-energy-storage devices due to the relative low cost, and the natural abundance of sodium resources. Yet developmental anodes in sodium-ion batteries such as carbonaceous materials have adagio sodium ion diffusion kinetics, huge volume expansion, poor rate performance and cycle stability. Herein, we report a high-performance sodium ion storage anode material, i.e., a unique nanonetwork-structured carbon (NNSC) with a valuable hollow nanosphere as network unit by developing a facile, efficient and post-treatment-free strategy. The as-constructed NNSC exhibits a three-dimensional interconnected hierarchical porous network and a luxuriant accessible surface area, which greatly enhance sodium ion transport and storage. Thus, the obtained NNSC demonstrates excellent sodium ion storage performance, including a high capacity of 250 mA h g−1, good rate capability, and ultra-long-term cycle life up to 9000 cycles. Such attractive capabilities could accelerate the application of sodium-ion batteries in large-scale energy storage.

MoO2 and graphene heterostructure as promising flexible anodes for lithium-ion batteries

Two-dimensional van der Waals heterostructures hold great promise to create lithium-ion batteries with large energy density, large power density, and long cycle life. In this work, we investigate the MoO2/graphene heterostructure as anodes for lithium-ion batteries by first principles calculations. It is found that the MoO2/graphene heterostructure possesses enhanced electrical conductivity, high theoretical specific capacity (1411 mAh∙g−1), and small diffusion barriers (77 meV). Meanwhile, the flexibility of graphene eliminates the irreversible deformation of MoO2 during the charge-discharge process. These characteristics render the MoO2/graphene heterostructure a stable and efficient Li ion storage performance.

V2O5 nanosheets anchored on graphitized carbon nanofibers network for free-standing cathode on performance-improved lithium ion batteries

Using excellent kinetic transport graphitized carbon nanofibers network to construct free-standing V2O5-based electrode is an effective approach to develop high-performance lithium ion batteries. Herein, we successfully prepare graphitized carbon nanofibers by combining the electrospinning and the catalytic effect of iron oxide, and the conductance of graphitized carbon nanofibers is increased by 5×104 times compared to the amorphous carbon. Through hydrothermal method, the V2O5 nanosheets can be anchored on the surface of graphitized carbon nanofibers, forming a flexible and free-standing composite electrode, which can be directly used as cathode electrodes with a reversible capacity of 290 mAh g−1 at 0.1 C and a capacity higher than 105 mAh g−1 even at a large current density of 20 C, retaining a capacity of 160 mAh g−1 at 5.0 C even over 700 cycles. This is the first report to synthesize V2O5 nanosheets on graphitized carbon nanofibers prepared by electrospinning to construct a free-standing composite electrode with high rate capability and cycling stability lithium ion storage performances.

Covalent organic frameworks converted N, B co-doped carbon spheres with excellent lithium ion storage performance at high current density

Covalent organic frameworks (COFs) with devisable nanostructures have exhibited extensive application prospects in energy storage and conversion. In this work, spherical COFs were successfully utilized as an ideal precursor for N, B co-doped carbon spheres (NBCs) that display hierarchical spherical architectures with rich pores. When applied as lithium ion batteries (LIBs) anode, NBCs exhibit high reversible specific capacity and outstanding long-life cycling stability (205.5 mAh g−1 at 5.0 A g−1 and 171.4 mAh g−1 at 10.0 A g−1 after 5000 cycles) owing to their hierarchical porosity, unique structure and in-situ N, B co-doping. The excellent lithium storage ability, especially satisfactory long cycling stability, enables NBCs to be a promising candidate for LIBs.

Nanopore confined anthraquinone in MOF-derived N-doped microporous carbon as stable organic cathode for lithium-ion battery

Anthraquinone (AQ), as organic cathode material, has provided an excellent opportunity to update the preexisting energy storage technologies owing to its facile and desirable fabrication at molecular level, higher theoretical gravimetric capacities and remarkable sustainability. However, some of its pristine properties like insulation and dissolution into electrolyte of organic active materials during cycling, have been inevitable obstacles to boost its electrochemical performance. Herein, we report a rational strategy to improve lithium ion storage performance of AQ by confining nanosized amorphous AQ into zeolitic imidazolate framework-8 (ZIF-8)-derived nitrogen-doped microporous carbon scaffold (AQ@N-ZIF-8). The AQ@N-ZIF-8 cathode delivers a high reversible specific capacity of 240 mAh g−1 at current rate of 0.1 C and retains ~216 mAh g−1 after 300 cycles (remarkably low capacity fading rate of 0.08% per cycle) with coulombic efficiency up to 99%. The exceptional lithium ion storage capacity of AQ@N-ZIF-8 is mainly ascribed to the synergistic effect of high loading capacity of AQ encapsulation and nanopore confinement of AQ dissolution in carbon scaffolds, and the enhanced conductivity of the encapsulated AQ by higher contents of nitrogen dopant. Moreover, the N-ZIF-8 with micropores facilitates the fast diffusion of organic electrolyte ions.

Oxygen vacancy modulated Ti2Nb10O29-x embedded onto porous bacterial cellulose carbon for highly efficient lithium ion storage

Rational design & modulation of ion/electron transfer paths are critical for achieving high-performance anode materials for lithium ion batteries. In this work, we first time realize smart assembly of oxygen vacancy modulated titanium niobium oxide (Ti2Nb10O29-x, TNOx) onto highly conductive bacterial cellulose carbon (BCC) forming BCC/TNOx electrode through a facile solvothermal-annealing method. BCC consists of interlinked (N, S & P) co-doped carbon fibres uniformly decorated with TNOx nanoparticles. Impressively, the introduction of oxygen vacancy can effectively enhance the internal ion/electron transfer in TNOx and enhancement effect is elaborated by synchrotron radiation technology (XANES and XAFS) and DFT calculation. Meanwhile, with the aid of conductive BCC skeleton, the external ion/electron transfer path on TNOx is also greatly improved leading to better reaction kinetics. The synergistic dual internal plus external modulation on transfer path show positive advantages including smaller band gap with better electrical conductivity, and larger lattice parameters with faster ion/electron transfer. Accordingly, the BCC/TNOx electrode is endowed with outstanding lithium ion storage performance with high-rate capability (281 mA h g−1 at 5 C, and 160.5 mA h g−1 at 40 C). Our finding provides valuable insights into design of other advanced electrodes via dual transfer path modulation strategy.

Effects of vanadium pentoxide with different crystallinities on lithium ion storage performance

V2O5 anode materials with low crystallinity release better electrochemical performance than that of V2O5 with high crystallinity.

Preparation and electrochemical performance of VO2(A) hollow spheres as a cathode for aqueous zinc ion batteries.

Rechargeable aqueous zinc ion batteries (ZIBs), owing to their low-cost zinc metal, high safety and nontoxic aqueous electrolyte, have the potential to accelerate the development of large-scale energy storage applications. However, the desired development is significantly restricted by cathode materials, which are hampered by the intense charge repulsion of bivalent Zn2+. Herein, the as-prepared VO2(A) hollow spheres via a feasible hydrothermal reaction exhibit superior zinc ion storage performance, large reversible capacity of 357 mA h g−1 at 0.1 A g−1, high rate capability of 165 mA h g−1 at 10 A g−1 and good cycling stability with a capacity retention of 76% over 500 cycles at 5 A g−1. Our study not only provides the possibility of the practical application of ZIBs, but also brings a new prospect of designing high-performance cathode materials.

NiSe2 nanooctahedra as anodes for high-performance sodium-ion batteries

Octahedral NiSe2 was fabricated by a facile hydrothermal method. It showed excellent Na ion storage performance when used as an anode material for sodium-ion batteries.

Heterojunction engineering of MoSe2/MoS2 with electronic modulation towards synergetic hydrogen evolution reaction and supercapacitance performance

Two-dimensional (2D) heterojunction held together by van der Waals or covalent interactions give high flexibility in modifying their electrocatalytic activity and ion storage performance, since the surface work function and electronic states are dependent on the topmost layer, also the overall heterostructure. The MoSe2/MoS2 heterostructure based on 2D MoSe2 thin-flake and MoS2 nanosheet was designed through heterojunction engineering and prepared by epitaxial growth process. The abundant interfaces in the MoSe2/MoS2 heterostructure not only enable more exposed active sites for electrochemical reaction, but also facilitate the charge transport due to the open porous space within the interlaced nanosheet arrays, arising from with the synergistic effect by the combination of MoS2 and MoSe2. As expected, the MoSe2/MoS2 heterostructure exhibits excellent hydrogen evolution property with a small Tafel slope of 61 mV dec−1, lower overpotential of 162 mV at 10 mA cm−2, and long-term stability. It also delivers a much boosted supercapacitance performance with a high specific capacitance of 1229.6F g−1 at 1 A g−1 and 92.8% capacitance retention after 2000 cycles. The asymmetric supercapacitor made of the MoSe2/MoS2//nitrogen-doped carbon shows a stable potential window of 1.8 V.

Correlation between the microstructure of carbon materials and their potassium ion storage performance

Alkali-metal ions storage in carbon materials is of great interests for developing high-performance anodes for batteries. While Li, Na ions storage has been extensively investigated, systematic studies on the correlation between K ions storage and carbon microstructure have rarely been conducted. The large radius of K ions leaves a legitimate question whether the charge storage sites for Li and Na ions are also active for K ions. Herein, electrospun carbon nanofibers are employed as model materials to explore the K-ion storage behaviors in carbon with representative microstructures. By combining in-situ characterization and theoretical calculations, three active sites have been unveiled, including (i) uptake of K-ion by defect sites; (ii) K ions adsorption on isolated graphene sheets in partially disordered carbon; (iii) K ions intercalation between graphene layers for carbon with a high degree of graphitization. A similar reversible capacity around 280 mAh/g is obtained for various carbon structures while their voltage profiles are highly disparate. Remarkably, it is found that non-graphitic carbon presents better rate capability and less temperature-dependence due to the faster ion diffusion. These findings offer new insights into the design of advanced carbon anode materials with tunable properties for K-ion batteries.

Hierarchical Carbon@SnS2 Aerogel with "Skeleton/Skin" Architectures as a High-Capacity, High-Rate Capability and Long Cycle Life Anode for Sodium Ion Storage.

Developing high-performance electrode materials with high energy and long-term cycling stability is a hot topic and of great importance for sodium ion batteries (SIBs). In this work, a highly porous carbon/tin sulfide aerogel with a "skeleton/skin" morphology (SSC@SnS2) has been developed and further used as a binder-free anode for SIBs. This SSC@SnS2 electrode delivers a high specific capacity of 612 mA h g-1 at 0.1 A g-1, a good rate capability, and a long-term cycling stability up to 1000 times with an average Coulombic efficiency of ∼99.9%. Meanwhile, this SSC@SnS2 aerogel also achieves a stable cycling performance even at a high current density up to 5.0 A g-1. The fast-yet-stable sodium ion storage performance of the prepared SSC@SnS2 aerogel can be ascribed to the reasons that (i) the carbon nanofiber/graphene skeleton provides unimpeded pathways for the rapid transfer of electrons; (ii) thin SnS2 skin with nonaggregated morphology can provide a great number of active sites for sodium ion storage; (iii) the porous structure of the SSC@SnS2 aerogel ensures a rapid penetration of electrolyte and can further accommodate the volume expansion of active SnS2 nanoflakes; and (iv) the intermediate product of Na15Sn4 alloy contributes greatly to the sodium ion storage performance of the SSC@SnS2 aerogel. The excellent electrochemical performances coupling with the unique structural features of this SSC@SnS2 aerogel make it a promising anode candidate for SIBs.

In situ construction of interconnected SnO2/nitrogen-doped Carbon@TiO2 networks for lithium-ion half/full cells

A one-pot in situ pyrrole polymerization strategy, followed by controllable atomic layer deposition of TiO2 and pyrolysis process, is carried out to construct the core-shell SnO2/NC@TiO2 with sub-5 nm SnO2 nanoparticles uniformly dispersing in interconnected nitrogen-doped carbon nanospheres coated by TiO2 layer. Benefiting from the unique structural stability of SnO2/NC@TiO2, as anode materials for LIBs, they show much improved cycling stability and rate capability compared with the bare SnO2 and SnO2/NC electrodes. Specifically, the SnO2/NC@TiO2 electrode with a 10 nm TiO2 coating layer demonstrate the optimal lithium ion storage performance, delivering initial discharge capacity of 1224 mAh g−1 with a first-cycle Columbic efficiency of 72.3% and 871 mAh g−1 after 200 cycles at 100 mA g−1. Moreover, the assembled SnO2/NC@TiO2//LiFePO4 full cell demonstrates a good rate capability with a reversible capacity of 145 mAh g−1 (67% capacity retention of the initial value) when the electrode undergoes various current densities after 70 cycles. The improved electrochemical performance is mainly attributed to the surface interface engineering by the interconnected carbon matrix as well as the uniform TiO2 outer layer. These achieved results suggest that interconnected SnO2/NC@TiO2 electrodes have the potential to be used as anode for high-performance lithium ion battery.

Freeze-drying method to synthesize V2O5/graphene composites toward enhanced sodium ion storage

V2O5 nanowires/Graphene composite was successfully constructed through a delicate method. SEM, TEM, XRD and Raman spectra were utilized to investigate the morphology and phase structure of as-obtained samples. When being compared with bare V2O5 nanowires, the as-obtained composite presented an enhanced performance of sodium ion storage. The results illustrated that the composite electrode can render a discharge specific capacity of 154 mA h g−1 during the first cycle, whereas it was 100 mA h g−1 for bare V2O5 nanowires electrode. It was worth noting that the method here to decorate graphene sheets with V2O5 nanowires was crucial to achieve the optimal electrochemical property. EIS and CV cures (at different scanning rate) indicated that the introduction of graphene sheets can enhance the electrical conductivity of as-obtained composite and facilitate the surface-controlled electrochemical reaction process of electrode. Finally, the enhanced sodium ion storage performance can be expected.

Solution synthesis of VSe2 nanosheets and their alkali metal ion storage performance

Vanadium diselenide (VSe2) is a transition metal dichalcogenide with metallic conductivity, which makes it a potentially promising electrode material for electrochemical applications. However, the development of VSe2 electrodes for such applications has been severely hampered by the difficulty of preparing nanosized products. In this work, a new facile solvothermal synthesis process is developed and optimized to synthesize ultrathin VSe2 nanosheet assemblies. To obtain the ultrathin nanosheets, N-methyl pyrrolidone, which has similar surface energy to many transition metal dichalcogenides, was used as the solvent to limit the crystal growth along the c-axis direction. The resulting ultrathin VSe2 nanosheets exhibit good performance toward alkaline ion (Li+ and Na+) storage, which can be significantly enhanced by carbon coating. Specifically, the carbon-coated VSe2 nanosheets can deliver high capacities of 768 mA h g-1 (Li+ storage) and 571 mA h g-1 (Na+ storage) along with outstanding stability.

Ultrafine CoP Nanoparticles Anchored on Reduced Graphene Oxide Nanosheets as Anodes for Sodium Ion Batteries with Enhanced Electrochemical Performance

Cobalt phosphide/reduced graphene oxide (CoP/RGO) nanohybrid materials have been prepared by a simple chemical precipitation method and a low‐temperature phosphorization process. Ultrafine CoP nanoparticles are loaded uniformly onto RGO nanosheets. The diameter of the CoP particle decreases to about 6–8 nm. Sodium ion battery anodes based on the CoP/RGO nanohybrids display significantly improved sodium ion storage performance. These electrode materials demonstrate a large capacity of about 490 mA h g–1, at a current density of 100 mA g–1, after 100 cycles. They also deliver good rate performance, demonstrating about 381 mA h g–1 specific capacity when the current density reaches 2.0 A g–1. The ultrafine nanoparticles, interconnected porous structure, large surface area, and good electrical conductivity are the major reasons for the excellent electrochemical performance. The synthesis method presented here is general, easy, and efficient, and can be developed for other metal phosphide–graphene composites.

Hydrothermal Synthesis of Flower-like Fe-doped VO2(B) with Enhanced Lithium Ion Storage Performance

Hydrothermal Synthesis of Flower-like Fe-doped VO2(B) with Enhanced Lithium Ion Storage Performance

Rapid activation and enhanced cycling stability of Co3O4 microspheres decorated by N-doped amorphous carbon shell for advanced LIBs

Co3O4 has been always highlighted as an anode material for lithium ion batteries (LIBs) due to its high theoretical capacity and low cost. However, its practical application is severely limited by the inherent structural pulverization and activation hysteresis during cycling. To overcome such limitation, in this work, a facile route of air-injection assisted soaking in dopamine-tris (DA-tris) solution followed by annealing in Ar atmosphere is successfully approached to decorate N-doped amorphous carbon (a-C) shells on surface of Co3O4 microspheres. The N-doped a-C shells are co-constructed by films and nanoparticles of N-doped a-C. The concentration of DA-tris plays significant roles to the structural nature of the N-doped a-C shells and the phase configuration of the Co3O4 microspheres. As an anode material for LIBs, the Co3O4 microspheres decorated by the N-doped a-C shells exhibit superior reversible capabilities of 1074 mA h g−1 under 500 mA g−1 and 830 mA h g−1 under 1000 mA g−1 after 500 cycles, respectively. Moreover, the rate capacity is impressive and the activation hysteresis is remitted effectively. Such an excellent lithium ions storage performance is firstly ascribed to the rapid activation of Co3O4 promoted by metallic Co, which is reduced by the N-doped a-C shells in situ. Secondly, the N-doped a-C shells effectively protect the structure from cracking and promote the electrochemical reactions of the Co3O4 microspheres. The present work provides an effective way to buffer the activation hysteresis of the transition metal oxides used for advanced LIBs application.

Molybdenum disulfide nanosheets embedded in hollow nitrogen-doped carbon spheres for efficient lithium/sodium storage with enhanced electrochemical kinetics

Molybdenum disulfide nanosheets@hollow nitrogen-doped carbon (MoS2@NC) spheres were prepared via a facile synthesis and investigated as a host material for ion storages. When used in lithium ion batteries (LIBs) or sodium ion batteries (SIBs), the MoS2@NC spheres electrodes exhibited excellent electrochemical performances. A high capacity of 1386 mAh g−1 after 100 cycles was obtained at a current density of 200 mA g−1 for LIBs. As for SIBs, a capacity of 330 mAh g−1 was retained after 400 cycles at 1000 mA g−1. The remarkable ion storage performances can be attributed to the hierarchical architecture of the MoS2@NC spheres, which not only supply abundant active sites and efficient electron and ion pathways, but also alleviate the volume change of the active MoS2 material. Meanwhile, synergistic effect of the heterogeneous components, interfacial ion storages, nitrogen doping and induced defects are responsible for high capacities of the MoS2@NC electrodes. And the electrodes exhibited enhanced electrochemical kinetics due to the significantly improved electrical conductivity and the large specific area of the MoS2@NC spheres.