Enhanced Lithium Storage Performance Research Articles

Metal-organic framework derived CdSe wrapped with rGO for enhanced lithium storage performance.

Considering the advantages of MOF-based, CdSe-based, and rGO-based materials, CdSe nanoparticles encapsulated with rGO (CdSe@rGO) were synthesized by a metal-organic framework derived method. CdSe nanoparticles encapsulated with rGO can effectively tolerate volume expansion and improve electrical conductivity, leading to excellent cycling stability (396 mAh g-1 at 0.3 A g-1 after 200 cycles, 311 mAh g-1 at 0.5 A g-1 after 500 cycles), and rate performance (562 mAh g-1 at 0.1 A g-1 and 122.2 mAh g-1 at 4 A g-1) for lithium-ion storage. This strategy for preparing metal selenides protected by carbon layers can be extended to the design of other high-performance materials.

Hierarchical-Structured Fe2O3 Anode with Exposed (001) Facet for Enhanced Lithium Storage Performance.

The hierarchical structure is an ideal nanostructure for conversion-type anodes with drastic volume expansion. Here, we demonstrate a tin-doping strategy for constructing Fe2O3 brushes, in which nanowires with exposed (001) facets are stacked into the hierarchical structure. Thanks to the tin-doping, the conductivity of the Sn-doped Fe2O3 has been improved greatly. Moreover, the volume changes of the Sn-doped Fe2O3 anodes can be limited to ~4% vertical expansion and ~13% horizontal expansion, thus resulting in high-rate performance and long-life stability due to the exposed (001) facet and the unique hierarchical structure. As a result, it delivers a high reversible lithium storage capacity of 580 mAh/g at a current density of 0.2C (0.2 A/g), and excellent rate performance of above 400 mAh/g even at a high current density of 2C (2 A/g) over 500 cycles, which is much higher than most of the reported transition metal oxide anodes. This doping strategy and the unique hierarchical structures bring inspiration for nanostructure design of functional materials in energy storage.

Enhanced lithium storage performance of Si/C composite nanofiber membrane with carbon coating as binder-free and self-supporting anode for lithium-ion battery

Self-supporting Si/C composite membrane is an ideal anode for flexible lithium-ion battery. However, how to achieve a long lifespan for Si/C anode remains a challenge because of the large volume expansion and low conductivity of Si. In this work, hierarchical porous Si/C composite nanofibers with carbon coating and hollow Si/SiOx embedded (C-Si-CNF) were fabricated by hydrothermal deposition of polydopamine on electrospun Si/C nanofibers, followed by pyrolysis. A hydrothermal deposition/pyrolysis process achieved both carbon coating and conversing of the solid Si into hollow Si/SiOx, which improved the conductivity and alleviated the volume expansion of Si. The C-Si-CNF electrode exhibited a high capacity (694.7 mAh·g−1 at 0.2 A·g−1), good rate performance (capacity retention of 36.9% with the current density increased from 0.1 to 5 A·g−1), and excellent cycling stability (capacity retention of 92.6% after 300 cycles). Overall, the C-Si-CNF membrane shows great potential as a binder-free and self-supporting anode for lithium-ion battery.

MoS2 nanoflowers implanted in nitrogen-doped carbon fibers with Fe2O3 nanoparticles decorated for enhanced lithium storage performance

MoS2 has attracted extensive attention due to its unique two-dimensional layered structure and high theoretical capacity. Unfortunately, the large volume variation and sluggish lithiation kinetics during charging/discharging result in low-rate capability and poor cyclic stability. To solve those issues, MoS2/Fe2O3 @ carbon fiber (CNF) composite was designed delicately by implanting MoS2 nanoflowers in nitrogen-doped carbon fibers with Fe2O3 nanoparticles decorated. The carbon nano-fibers served as a holder to accommodate the volume expansion of MoS2 and provide a high-speed channel for electron transport, while Fe2O3 nanoparticles are apt to form heterojunction with MoS2, producing an internal electric field to enhance the ionic dynamic. As a result, the optimized sample, denoted as MoS2/Fe2O3 @CNF-3, exhibits high first discharge capacity of ∼1370 mAh g−1 at 50 mA g−1 and excellent cycle performance (559.74 mAh g−1 after 500 cycles at 1 A g−1, with capacity retention rate of 71.6%). In summary, the design techniques of heterojunction building and carbon encapsulation can be applied to different energy storage materials and have significant potential for enhancing lithium-ion battery performance electrochemically.

Uniform yolk-shell Fe2O3@N-doped carbon nanorings with rich oxygen vacancies as anode materials for high performance Li-ion battery

Owing to the rapidly increasing demand of energy storage devices, it is necessary to create an apposite anode of lithium ion batteries (LIBs). Fe2O3-based anode materials, which possess high theoretical capacity and low cost, are one of the popular candidate anodes. However, Fe2O3-based anode suffer from large volume change and low conductivity. Herein, yolk-shell (YS) Fe2O3/N-doped carbon nanorings with abundant oxygen vacancies (YS-Fe2O3@NC-OVs) were designed and synthesized for robust lithium storage. OVs in the Fe2O3 lattices were introduced by annealing process, inducing a local construction internal electric field to accelerate the fast migration of Li+ by Coulomb force during cycling process and leading to an excellent electrochemical property for Li-ion batteries. Benefit from the yolk-shell structure and the OVs, the YS-Fe2O3@NC-OVs electrode display an outstanding cycling stability with a reversibly specific capacity of 697.4 mA h g−1 at 5 A g−1 after 500 cycles for lithium storage. And a high specific capacity of 570.3 mA h g−1 at 10 A g−1 is attained. The high reversible specific capacities and superior cycle stability of YS-Fe2O3@NC-OVs might be ascribed to the elaborate YS nanoarchitecture. The well-designed YS nanoarchitecture might be to blame for the high reversible specific capacities and remarkable cycle stability of YS-Fe2O3@NC-OVs. Additionally, the work function (WF) indicated that the enhanced lithium storage performance of YS-Fe2O3@NC-OVs might be ascribed to better Li+ diffusion kinetics and high electronic conductivity.

Copper-induced formation of heterostructured Co3O4/CuO hollow nanospheres towards greatly enhanced lithium storage performance

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 Co3O4 heterostructure with hollow spherical morphology, which greatly enhances the charge/electrolyte transfer and effectively buffers the volume changes upon lithiation/delithiation cycling.

Flexible electrospun FeCo/carbon hybrid nanofiber films as binder-free anodes for enhanced lithium storage performance

The design of electrodes with excellent mechanical elasticity is the significant to developing flexible electronic devices with mechanical endurance and outstanding lithium storage properties. Herein, the flexible FeCo/carbon hybrid nanofiber membranes (named as FeCo@CNFM) were successfully prepared via electrospinning and subsequent carbonization process. From the macroscopic perspective, the FeCo@CNFM can bend at a large angle without any destruction, and be directly used as working electrode of lithium ions batteries (LIBs) without any expensive additives, demonstrating its extraordinary mechanical flexibility. From the microscopic perspective, the homogeneously dispersed fine FeCo nanoparticles and the three-dimensional (3D) interconnected transport network constructed of carbon nanofibers significantly shorten the lithium-ion transfer distance, eliminate the volume fluctuation during lithiation/delithiation process, enhance the utilization rate of active materials, and promote the electrical conductivity of the composite electrode, thus leading to remarkably improved electrochemical properties. As a consequence, the optimized FeCo@CNFM manifests a superior discharge capacity of 584.9 mA h g−1 at 100 mA g−1 after 100 cycles with long cycling stability and good rate capability of 227.1 mA h g−1 even at a large current rate of 2 A g−1, making it a promising flexible self-supporting anode for LIBs.

Graphene Oxide-Wrapped Porous Hollow Co3O4 Microspheres with Enhanced Lithium Storage Performance

Porous hollow Co3O4 microspheres wrapped with graphene oxide were synthesized by a step solvothermal method and subsequent heat treatment. Benefiting from the design of special porous hollow microspheres, the effective specific surface area was greatly increased, the sufficient contact between the porous hollow Co3O4 microspheres and electrolyte was achieved, and then a charge specific capacity of 888.59 mA h g-1 was gained. Meanwhile, partial stress from the charging/discharging process was greatly relieved due to the abundant pores and hollow structure, excellent cycling stability was realized, and the charge specific capacity of the 1000th cycle was 465.75 mA h g-1 at 5 C (1 C = 890 mA g-1). In addition, the conductivity of Co3O4 microspheres was effectively improved due to the tight package of graphene oxide to Co3O4 microspheres, and superior rate performance was attained (280.99 mA h g-1 at 10 C).

Manipulation of π-aromatic conjugation in two-dimensional Sn-organic materials for efficient lithium storage

Sn-based materials are promising candidates for lithium storage but suffer generally from huge volume change during the (de)lithiation processes. Sn-organic materials with monodispersed Sn centers surrounded by lithium active ligands can alleviate the volume change of anode materials based on reversible (de)lithiation processes. However, the structural factors governing the kinetics of lithium storage and utilization efficiency of active sites are not well understood to date. Herein, we report three two-dimensional Sn-organic materials with enhanced lithium storage performance by manipulation of π-aromatic conjugation of the ligands. The increasing π-aromatic conjugation plays a key role in promoting efficient lithium storage, and the volume expansion during the (de)lithiation reaction is suppressed in these Sn-organic materials. This work reveals that the π-aromatic conjugation of the ligand is crucial for improving the kinetics of lithium storage and the utilization of active sites in metal-organic materials with minimised volume expansion.

One-step construction of hexagonal WO3 nano-shuttles with enhanced lithium storage performance.

In this work, WO3 nanorod-based aggregates and WO3 nano-shuttles were constructed by a facile hydrothermal route. The structure, morphology, element composition and valence state of the formed WO3 samples were characterized using different testing instruments. As the active anode for lithium-ion batteries, the WO3 nano-shuttle electrode can deliver a reversible specific capacity of 614.7 mA h g-1 after 300 cycles at a current density of 500 mA g-1. The excellent electrochemical properties indicate that WO3 nano-shuttles are a prospective anode candidate for high performance lithium-ion batteries.

In-situ encapsulating ultrafine CoFe2O4 nanoparticle into porous N-doped carbon nanofiber membrane as self-standing anode for enhanced lithium storage performance

The ultrasmall CoFe2O4 nanoparticles in situ encapsulated in porous N-doped carbon nanofibers membranes (CFO@PNCFM) with different pore structures have been prepared by electrospinning and subsequent carbonization. When immediately used as self-standing anodes for lithium-ion batteries (LIBs), the optimized CFO@PNCFM exhibits superior lithium storage properties with high rate capability (476.5 mAh g−1 at 2 A g−1) and long stable cycle life (755.8 mAh g−1 at 100 mA g−1 after 200 cycles). The outstanding electrochemical performance may be mainly ascribed to the synergistic effect of special 3D conductive porous carbon nanofibers (PCNFs) network and ultrafine CoFe2O4 nanoparticles in energy storage, which can significantly enhance the utilization efficiency of electroactive materials and improve the charge-transport kinetics. Moreover, the CoFe2O4 nanoparticles bonded closely to PCNFs through strong metal-oxygen bridges, which promote the electron capture and transfer from PCNFs to CoFe2O4, and thus achieving fast electrochemical reaction kinetics. Meanwhile, the porous structure can not only alleviate the volume change during charge/discharge cycles, but also supply numerous active sites for lithium storage, resulting in a high reversible capacity as well as good cycle stability and rate performance.

Design and synthesis of NiCo-NiCoO2@C composites with improved lithium storage performance as the anode materials

The rapid capacity decay severely limits the commercial applications of metal oxide-based electrodes. Exploring innovative materials with enhanced lithium storage performance is urgent and challenging. Herein, we propose a strategy for the synthesis of NiCo-NiCoO2@C composites using layered double hydroxide (LDH) precursors. When used as the anode materials, the composites deliver enhanced capacity throughout the continuous charge–discharge process. In our design, the electrochemically active NiCoO2 nanoparticles pulverize the NiCo phases via a conversion reaction. The NiCo phases can increase capacity by reacting with the Li2O yielded from the conversion of NiCoO2 and participating in the reversible transformation of solid-electrolyte interface (SEI) films, thus ensuring fast charge transfer. Voids that appear with the consumption of NiCo phases can provide abundant channels for Li+ transportation. Carbon matrices can effectively alleviate the stress generated during repeated cycles of expansion and shrinkage. Benefiting from these features, NiCo-NiCoO2@C anode delivers a highly enhanced reversible capacity of 961.6 mAh g−1 after 300 cycles at 200 mA g−1. This LDH-based strategy may be extended to the design and synthesis of various enhanced anode materials for lithium-ion batteries (LIBs).

Amorphous carbon nanofibers incorporated with ultrafine GeO2 nanoparticles for enhanced lithium storage performance

As a potential anode material with high theoretical specific capacity, the practical application of GeO 2 is largely hindered by huge volume change and low reactivity, Herein, we proposed the engineering of dual amorphous GeO 2 @C nanofibers via facile electrospinning and thermal annealing process. In this design, numerous ultrafine GeO 2 particles are evenly anchored in carbon nanofibers, which could relief the stress in the carbon material during the lithium/delithiation process. Moreover, the low binding energy of Ge-O bond in the dual amorphous GeO 2 /C nanofibers render for convenient charge transfer. As a result, the electrode delivers highly reversible conversion (GeO 2 + 4Li ↔ Ge + 2Li 2 O) and alloying (Ge + 4.4Li ↔ GeLi 4.4 ) reaction. Furthermore, the GeO 2 @C nanofibers with large specific surface area also supply more active sites for pseudocapacitive lithium storage. Benefitting from the typical structure, the dual amorphous GeO 2 @C nanofibers electrode exhibits high reversible capacity of 1053 mAh g −1 at 0.3 A g −1 after 1000 cycle, and superior rate capacity of 476 mAh g −1 at 5 A g −1 . The excellent electrochemical performance endows dual amorphous GeO 2 @C nanofibers competitive electrode material for next-generation lithium-ion batteries. • Dual amorphous GeO 2 @C nanofibers were prepared by a facile and efficient approach. • Dual amorphous GeO 2 @C nanofibers display outstanding lithium storage properties. • Dual amorphous structure benefits for superior lithium storage.

Structural engineering of CoMoO3 nanosheets on cage-like carbon nanoflakes toward enhanced lithium storage performance

Bimetal oxides possess high electronic conductivity and multiple electrochemically active sites owing to their stepwise electrochemical reactions compared with the single metal oxides. However, bimetal oxides still suffer from the severe volume changes upon lithium insertion/delithiation processes, thus leading to poor cycle stability. Herein, we demonstrate the growth of novel CoMoO3 nanosheets on the cage-like carbon nanoflakes (c-CNFs) through a facile in-situ thermal decomposition strategy. The phase and morphology structures of CoMoO3 can be readily controlled by adjusting the sintering temperature under the argon atmosphere, changing from 0D CoMoO4 nanoparticles@c-CNFs (350 ℃, denoted as CoMoO4 @C) to 0D CoMoO4 nanoparticles and 2D CoMoO3 nanosheets co-existed nanohybrids@c-CNFs (450 ℃, denoted as CoMoOx @C) and 2D CoMoO3 nanosheets@c-CNFs (550 ℃, denoted as CoMoO3 @C). When examined as anode materials for LIBs, the CoMoO3 @C electrode exhibited excellent lithium storage performance. The superior performance of the CoMoO3 @C electrode could be attributed to the novel CoMoO3 nanosheet structure combined with the reduced volume change from well-fitted CoMoO3 @c-CNFs, which delivered a reversible capacity of ~706 mA h/g for 360 cycles at 500 mA/g, higher than that of the CoMoO4 @C and CoMoOx @C electrodes.

Self-assembly synthesis of petal-like MoS2/Co9S8/carbon nanohybrids for enhanced lithium storage performance

Transition metal sulfides are favored as anode materials for the next generation of lithium-ion batteries because of their high theoretical capacities and abundant natural resources. However, serious volume changes during charging and discharging pose great challenges to their stability. In this work, petal-like MoS2/Co9S8/C nanohybrids were synthesized via the immobilization of molybdyl acetoacetonate MoO2(acac)2 in ZIF-67 and subsequent combined vulcanization and thermolysis process. Benefiting from the homogeneous bimetallic sulfide and highly conductive carbon layer, the as-obtained MoS2/Co9S8/C nanohybrids exhibited a high initial discharge capacity of 988.3 mAh g−1 at 200 mA g−1 and a capacity retention > 99.9% after 50 cycles. Even at a high current density of 1000 mA g−1, the reversible capacity of MoS2/Co9S8/C is still as high as 754.6 mAh g−1, revealing extraordinary rate ability. This work can provide a general approach to design and synthesize other advanced bimetallic chalcogenides for boosting lithium-ion batteries storage performance.

Engineering Ag nanoparticles and amorphous MoOx on three dimensional N-doped carbon networks for enhanced lithium storage performance

Molybdenum-based oxides have been widely investigated as promising material for lithium ion batteries owing to their unique physical and chemical properties as well as the large specific capacities. However, the fast capacity fading and poor cyclability originated from the large volume expansion and the sluggish electrode kinetics still inhibit their practical application. Herein, Ag nanoparticles combined with amorphous MoOx-in-plane nanoconfined on three dimensional N-doped porous carbon networks (3DNC) are designed and synthesized through salt-template strategy accompanied by annealing treatment and hydrothermal method (3DNC-MoOx-Ag). The synergistic effect of Ag nanoparticles and amorphous MoOx can inhibit the “dead volume” and aggregation of the electrode, accommodate the volume change, accelerate the diffusion kinetics during the lithium ion intercalation and de-intercalation processes. As a result, the designed 3DNC-MoOx-Ag delivers prominent cycling stability (834 mAh g−1 after 100 cycles at 200 mA g−1) and excellent rate performance (419 mAh g−1 after 70 cycles at 5000 mA g−1). Even at 5000 mA g−1, a specific capacity as high as 369 mAh g−1 can be achieved after 500 cycles.

Facile Synthesis of Hybrid Anodes with Enhanced Lithium-Storage Performance Realized by a “Synergistic Effect”

Alloying-type anodes including Si- and Sn-based materials are considered the most exploitable anodes for high-performance lithium-ion batteries. However, problems of poor kinetics properties and structural failures such as grain pulverization and coarsening hinder their large-scale application. Herein, SnO2/Si@graphite hybrid anodes, with nano-SnO2 and nano-Si thoroughly mixed with each other and loaded onto graphite flakes, have been prepared by a facile ball milling method. Attributed to the "synergistic effect" between SnO2 and Si, the mechanical stability and kinetics properties can be remarkably enhanced. Furthermore, graphite substrate supplies a fast electrically conductive path and buffers the volume expansion of active particles. Accordingly, SnO2/Si@graphite delivers 798.9 mAh g-1 at 200 mA g-1 and maintains 550.8 mAh g-1 after 1000 cycles at 1 A g-1 in half cells. Impressively, a high energy density of 431.4 Wh kg-1 (based on the mass of anode and cathode) can be obtained in full cells when paired with the NCM622 cathode. This work presents an effective strategy to exploit high-performance alloying-type anodes for LIBs by designing hybrid materials with multiple active components.

Hollow nanospheres constructed by ultrafine few-layered MoS2 partially with amorphous fragments homogeneously incorporated in N-doped amorphous carbon for enhanced lithium storage performance

The rational design of ultrathin and few-layered structures for three-dimensional MoS2 nanospheres is crucial for achieving attractive lithium-ion batteries (LIBs). Herein, hollow nanospheres constructed by ultrafine and few-layered MoS2 homogeneously incorporated in N-doped amorphous carbon (HUF-MoS2/NC) have been successfully synthesized as high-performance anode for LIBs. Using Mo-glycerol spheres as templates and dopamine hydrochloride as coordination ligands, hollow Mo-glycerol-polydopamine precursors are formed with Mo-containing groups which are surrounded by organic carbon species. Consequently, the MoS2 is confined to the nanoscale and grows partially amorphous fragments while being uniformly embedded in NC. This unique architecture can not only hinder the substantial restacking between MoS2 interlayers, offering more active sites, but also vastly enhance the electrical conductivity and relieve the mechanical stress ascribed to volume changes. As a result, the HUF-MoS2/NC composite anode exhibits excellent cyclic stability (980mAhg−1 after 300 cycles at 0.2Ag−1) and superior rate performance (498mAhg−1 at 5.0Ag−1) for LIBs.

Hierarchical copper manganese oxide porous micro/nanospheres with high electrochemical performance

In this contribution, hierarchical copper manganese oxide porous micro/nanospheres have been synthesized through sacrificial manganese carbonate micro/nano spheres precursor. The morphology and structure are examined by scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electron microscopic (TEM), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmet-Teller adsorption (BET). As electrode of lithium-half cells, the as-synthesized sample demonstrates the remarkably enhanced lithium storage performance compared to those of bulk counterparts and the reported literature, in terms of high first discharge capacity (1191.8 mAh g−1), satisfactory cycle performance (462.7 mAh g−1 at 2 C after 500 cycles), fair rate capability (357.8 mAh g- even at 5 C), quick Li+ diffusion kinetics (1.1 ×10−12 cm2 s−1), as well as low activation energy (13.06 KJ mol−1). Interestingly, the hierarchical micro/nanospheres are well maintained after 500 cycles.

Sb-etching-doping engineering TiSe2@C core–shell with low polarization effect enabling enhanced lithium storage performance

The critical challenge of TiSe2 anode for lithium-ion battery (LIB) lies in the severe polarization due to the accumulation of excessive lithium ions and Li3TiSe2 phase during charge/discharge process, resulting in reduced active sites and sluggish interfacial transport kinetics. To solve the issues, Sb doped TiSe2@C core–shell is synthesized via a combined ion etching-doping route. During the process, the introduced Sb element in MIL-125 triggers a synergistic etching-ion exchanging reaction, leading to a structure change of TiSe2 from bulk to core–shell as well as homogeneous Sb-doping in TiSe2. The unique structure demonstrates nano-crystallization of bulk TiSe2 and the formation of local built-in electric field, providing enough achievable active sites and enhancing interfacial charge/ion transfer kinetics. Benefitting from the synergistic effect of structural engineering and electronic structural engineering, polarization effect is weakened and pseudocapacitance storage ability is improved, leading to the high specific capacity and cycle stability of 502 mAh g−1 after 100 cycles at 0.1 A g−1. Therefore, the synthetic route of Sb doped TiSe2@C core–shell anode can be extended to related nanostructured systems for high performance energy storage device application.