Excellent Lithium Storage Capability Research Articles

Defect-rich hierarchical porous spinel MFe2O4 (M = Ni, Co, Fe, Mn) as high-performance anode for lithium ion batteries

Exploring innovative anode materials with excellent lithium storage capability is an urgent and challenging task. Among various candidates, the spinel ferrites based anodes received huge attention owing to the high theoretical capacity. However, the rapid capacity decaying and sluggish reaction kinetics during cycling have severely hampered their commercialization process. Herein, the hierarchical porous spinel MFe2O4 (M = Ni, Co, Mn, Fe), comprised of Mn doped porous NiFe2O4/CoFe2O4 heterostructure ligament network and Ni/Co/Mn co-doped Fe3O4 nanosheets network, is synthesized through a facile chemical dealloying strategy. The as-prepared MFe2O4 anode shows impressive cycling stability, revealing a discharge capacity of 1161.6 mAh g−1 after cycling for 1500 cycles at 500 mA g−1. Furthermore, the assembled LiFePO4//MFe2O4 full cell can display a reversible capacity of 111.2 mAh g−1 at 0.5 C after 150 cycles, exhibiting the great potential of the practical application of the MFe2O4 in the next-generation LIBs. The remarkable Li storage properties can be attributed to the particular hierarchical porous structure, highly active NiFe2O4/CoFe2O4 heterointerface and abundant surficial oxygen defects, high stable spinel structure contributed from high conformational entropy of polymetallic ions, and a double role of Mn doping in the cycling process. The structure regulating strategy proposed here is greatly expected to boost the developing of high-performance spinel ferrites based anodes.

Se@MoSe2/Si composite boosts excellent lithium storage capability with enhanced electrochemical activity

The traditional MoSe2 anode material for lithium-ion batteries has poor cyclic stability and relatively low capacity, which hinders its practical application. Herein, high capacity of Si and Se are exploratively incorporated into two-dimensional MoSe2 nanopetals to configure Se@MoSe2/Si composite. The optimized Se@MoSe2/Si composites have both high capacity and good electrochemical stability with a high retention capacity of 1187.7 mAh/g after 200 cycles at 100 mA/g current density. The visible depression on volumetric expansion is observed on the configuration of Se@MoSe2/Si. The admirable function of silicon on the enhancement of the electrochemical activity and the conductivity of Se@MoSe2 is theoretically demonstrated by First-principles calculations. This mutually beneficial interaction between the components demonstrates a promising synergistic effect on Se@MoSe2/Si.

Hydrogen-bonded Complex-based Frameworks for Stable Lithium Storage.

Metal-complex-based materials for lithium storage have attracted great interest due to their highly designable structures with multiple active sites and well-defined lithium transport pathways. Their cycling and rate performances, however, are still constrained by structural stability and electrical conductivity. Herein, we present two hydrogen-bonded complex-based frameworks with excellent lithium storage capability. Multiple hydrogen bonds among the mononuclear molecules result in three-dimensional frameworks that are stable in electrolyte. The origin of the remarkable lithium storage performance of this family was revealed through kinetic analysis and DFT calculations.

N-doped carbon nanofibers encapsulated Cu2-xSe with the improved lithium storage performance and its structural evolution analysis

With the porous feature, high aspect ratio and high electronic conductivity, nitrogen-doped one-dimensional carbon nanofibers can effectively shorten ionic transport pathways and enhance the intrinsic electronic conductivity of metal selenides electrodes, showing a great potential as anode material for the next-generation lithium-ion batteries (LIBs). In this work, we have synthesized nitrogen-doped carbon nanofibers encapsulated Cu2-xSe (N-CNFs@Cu2-xSe) with an average particle size of 20 nm, via electrospinning and in-situ selenization process, giving an excellent lithium storage capability. Specifically, such electrodes delivered a specific capacity of 1079.1 mA h g−1 at 0.1 A g−1 after 100 cycles, while 639.4 mA h g−1 at 2 A g−1 after 1000 cycles, exhibiting an ultralong cycle life. The gradually increased capacity was attributed to phase transformation of Cu2-xSe from crystalline to amorphous state, which leads to the capacity improvement from increased capacitive behavior. The in-situ X-ray diffraction harvest at the real time state of battery demonstrated the phase transition of Cu2-xSe with lithium and phase regeneration among cycles, verifying copper selenide has the features of the high reversibility of conversion reaction and superior thermostability. The high capacity and long cycling life of NCNFs@Cu2-xSe make it possible for great application potentials for high-performance lithium-ion batteries.

Cl-/SO32--Codoped Poly(3,4-ethylenedioxythiophene) That Interpenetrates and Encapsulates Porous Fe2O3 To Form Composite Nanoframeworks for Stable Lithium-Ion Batteries.

Penetrating into the inner surface of porous metal-oxide nanostructures to encapsulate the conductive layer is an efficient but challenging route to exploit high-performance lithium-ion battery electrodes. Furthermore, if the bonding force on the interface between the core and shell was enhanced, the structure and cyclic performance of the electrodes will be greatly improved. Here, vertically aligned interpenetrating encapsulation composite nanoframeworks were assembled from Cl-/SO32--codoped poly(3,4-ethylenedioxythiophene) (PEDOT) that interpenetrated and coated on porous Fe2O3 nanoframeworks (PEDOT-IE-Fe2O3) via a one-step Fe3+-induced in situ growth strategy. Compared with conventional wrapped structures and methods, the special PEDOT-IE-Fe2O3 encapsulation structure has many advantages. First, the codoped PEDOT shell ensures a high conductive network in the composites (100.6 S cm-1) and provides interpenetrating fast ion/electron transport pathways on the inner and outer surface of a single composite unit. Additionally, the pores inside offer void space to buffer the volume expansion of the nanoscale frameworks in cycling processes. In particular, the formation of Fe-S bonds on the organic-inorganic interface (between PEDOT shell and Fe2O3 core) enhances the structural stability and further extends the cell cycle life. The PEDOT-IE-Fe2O3 was applied as lithium-ion battery anodes, which exhibit excellent lithium storage capability and cycling stability. The capacity was as high as 1096 mA h g-1 at 0.05 A g-1, excellent rate capability, and a long and stable cycle process with a capacity retention of 89% (791 mA h g-1) after 1000 cycles (2 A g-1). We demonstrate a novel interpenetrating encapsulation structure to highly enhance the electrochemical performance of metal-oxide nanostructures, especially the cycling stability, and provide new insights for designing electrochemical energy storage materials.

Facile preparation of N-doped MnO/rGO composite as an anode material for high-performance lithium-ion batteries

An N-doped MnO/rGO composite (N-MnO/rGO) was successfully fabricated by a one-step hydrothermal method in which histidine and potassium permanganate (KMnO4) reacted in water containing graphene oxide, and the product was then calcinated in a nitrogen (N2) atmosphere. The N-MnO/rGO presents an excellent lithium-storage capability. It shows a high reversible specific capacity of 1020 mA h g−1 at a current density of 200 mA g−1 after 150 cycles and 760 mA h g−1 at a current density of 500 mA g−1 after 200 cycles. Meanwhile, the N-MnO/rGO sample presents a stable rate capability from 100 to 2000 mA g−1. Even at 2000 mA g−1, the electrode delivers 335 mA h g−1, which is higher than the capability for the pure MnO particles and rGO sheets. The outstanding electrochemical performances of the N-MnO/rGO electrodes may be attributed to the combined effect of the rGO with N-doping that can effectively buffer the large volume expansion of the MnO particles and can enhance the transport rates of lithium ions and electrons during lithium cycling.

Preparation of ternary phase Li4Ti5O12/anatase/rutile nanocomposites with defects and their enhanced capability for lithium ion storage

Developing anode materials that have high safety and high performance is essential for their application in Li ion batteries. Ternary phase Li4Ti5O12/rutile/anatase (N-LTO/A/R) nanocomposites that have abundant phase boundaries and structure defects are prepared via solvothermal synthesis and following calcination under an Ar/NH3 atmosphere. With the introduction of multiple phases and defects, the as-prepared ternary phase nanocomposites display excellent lithium storage capability in a Li half-cell as well as in full-cell batteries. The nanocomposites deliver a reversible specific capacity of 149.0 mAh g−1 at a current density of 10 A g−1 and maintain about 85% of the specific capacity after 800 cycles at a higher rate of 5 A g−1 for the Li half-cell. Even in the Li ion full-cell, the as-prepared nanocomposites deliver specific capacities of 210 and 124 mAh g−1 at current densities of 0.05 and 1 A g−1, respectively. The extraordinary electrochemical performance of the N-LTO/A/R nanocomposites is attributed to the nanostructures, phase boundaries, presence of structure defects, and larger specific surface area, which favor facilitating lithium ion diffusion and electron transfer. This study shows that the ternary phase nanocomposites are very promising as a high-performance anode in lithium ion batteries.

High Areal Capacity Li-Ion Storage of Binder-Free Metal Vanadate/Carbon Hybrid Anode by Ion-Exchange Reaction.

Storing more energy in a limited device area is very challenging but crucial for the applications of flexible and wearable electronics. Metal vanadates have been regarded as a fascinating group of materials in many areas, especially in lithium-ion storage. However, there has not been a versatile strategy to synthesize flexible metal vanadate hybrid nanostructures as binder-free anodes for Li-ion batteries so far. A convenient and versatile synthesis of Mx Vy Ox+2.5y @carbon cloth (M = Mn, Co, Ni, Cu) composites is proposed here based on a two-step hydrothermal route. As-synthesized products demonstrate hierarchical proliferous structure, ranging from nanoparticles (0D), and nanobelts (1D) to a 3D interconnected network. The metal vanadate/carbon hybrid nanostructures exhibit excellent lithium storage capability, with a high areal specific capacity up to 5.9 mAh cm-2 (which equals to 1676.8 mAh g-1 ) at a current density of 200 mA g-1 . Moreover, the nature of good flexibility, mixed valence states, and ultrahigh mass loading density (over 3.5 mg cm-2 ) all guarantee their great potential in compact energy storage for future wearable devices and other related applications.

Hierarchical hybrid sandwiched structure of ultrathin graphene nanosheets enwrapped MnO nanooctahedra with excellent lithium storage capability

Graphene supported transition metal oxides (TMOs) nanocomposites have been recognized as an advisable strategy to develop the advanced electrodes for lithium-ion batteries (LIB) recently, yet the long-term cyclic stability could not be well maintained mainly due to the severe structural collapse and continuous exfoliation of active TMOs from graphene support. Herein, we successfully designed a novel sandwich-type hybrid nanostructure of reduced graphene oxide (rGO) enwrapped MnO nanooctahedra like a blanket (MnO@rGO NO) via a facile solution reflux and a post-annealing. The XRD patterns and FESEM images confirm that octahedral Mn3O4 precursor embedded among GO interlayers could be easily reduced into conformal MnO nanocrystal whilst the full reduction of GO into rGO during the subsequent calcination at 700 °C in N2. When used as a promising anode for LIBs, the sandwiched MnO@rGO NO manifests excellent lithium storage capability with high reversible discharge capacity, long-term cyclic stability and superb rate performance, mainly benefiting from the robust structure and good conductivity enhanced by rGO matrix. Even undergoing 600 cycles at the current densities of 400 and 800 mA g−1, the hybrid sandwiched MnO@rGO NO anodes could still deliver stable discharge capacities of 838 and 687 mAh g−1, respectively.

Nanowires of spinel cathode material for improved lithium-ion storage

Li-excess layered materials, such as Li[Li0.2Mn0.54Ni0.13Co0.13]O2 (LMNCO) et al. are promising cathode materials that can be used in batteries for hybrid electric vehicles (HEV)/electric vehicles (EV), due to their excellent lithium-storage capability and very high energy density. Dramatic capacity loss during electrochemical cycling seriously hinders their practical implementation. It is found that the LMNCO layered cathode material suffers from structural instability and irreversible layered-to-spinel phase transition during lithiation/delithiation, leading to dramatic loss of capacity and deteriorated electrochemical kinetics. To overcome this challenge, we synthesize spinel-structured LHMNCO TBA nanowires using an electrospinning method followed by facile ion-exchange promoted phase transition. After 100 electrochemical cycles at the specific current 0.5 C, spinel-structured LHMNCO TBA still retains a capacity of about 200 mAh/g, corresponding to a capacity retention ratio of 90.5%, much higher than that of layered LMNCO nanowires, which only maintains a specific capacity of 137 mAh/g with only 48.9% capacity retention.

Continuous Carbon Hollow Shell with Zinc Oxide Nanoparticles Embedded as an Anode Material with Excellent Lithium Storage Capability

AbstractContinuous carbon hollow shells with embedded ZnO nanoparticles were synthesized from colloidal polystyrene/ZnO as templates and glucose oligomer as the carbon source followed by calcination. The resulting uniform ZnO/C hollow spheres display a relatively high reversible capacity of 994 mAh g−1 after 100 cycles at 0.1 A g−1 and 812 mAh g−1 after 200 cycles at 1 A g−1, which is superior to most reported ZnO‐based anode materials. The excellent electrochemical performance of the ZnO/C hollow spheres may arise from the following aspects: the shortened pathway of Li ions and electrolyte attributed to the unique hollow shell structures, improved electronic conductivity, firm encapsulation of ZnO nanoparticles, and high specific surface area of the products, which together facilitate the ZnO nanoparticles to undergo the alloying reaction completely.

Construction of point-line-plane (0-1-2 dimensional) Fe2O3-SnO2/graphene hybrids as the anodes with excellent lithium storage capability

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.

Novel spinel Li5Cr9Ti4O24 anode: Its electrochemical property and lithium storage process

In this work, a novel lithium storage material Li5Cr9Ti4O24 is reported as anode material for rechargeable lithium-ion batteries. We prepare Li5Cr9Ti4O24 by two different routes, sol-gel method and solid state reaction. Li5Cr9Ti4O24 nanocrystalline can be achieved by sol-gel method, while solid state reaction delivers micro-sized product. Electrochemical results show that Li5Cr9Ti4O24 nanocrystalline exhibits reduced charge transfer resistance, decreased redox polarization and improved lithium-ion diffusion coefficient compared with micro-sized product. As a result, Li5Cr9Ti4O24 nanocrystalline shows excellent lithium storage capability with 100% capacity retention after 200 cycles. Cycled at 600mAg−1, it still can deliver a charge specific capacity of 110.3mAhg−1. In contrast, micro-sized Li5Cr9Ti4O24 only reveals the reversible capacity of 66.8mAhg−1 at the same current density. In addition, Li5Cr9Ti4O24 nanocrystalline also shows outstanding structural stability for repeated lithium storage. In-situ structural observation reveals that the entire volume expansion of Li5Cr9Ti4O24 is only 0.62% during the charge/discharge process, which is similar with the zero-strain Li4Ti5O12. Therefore, Li5Cr9Ti4O24 nanocrystalline can be used as high performance anode material for lithium-ion batteries.

Effect of Sodium-Site Doping on Enhancing the Lithium Storage Performance of Sodium Lithium Titanate.

Via Li(+), Cu(2+), Y(3+), Ce(4+), and Nb(5+) dopings, a series of Na-site-substituted Na1.9M0.1Li2Ti6O14 are prepared and evaluated as lithium storage host materials. Structural and electrochemical analyses suggest that Na-site substitution by high-valent metal ions can effectively enhance the ionic and electronic conductivities of Na2Li2Ti6O14. As a result, Cu(2+)-, Y(3+)-, Ce(4+)-, and Nb(5+)-doped samples reveal better electrochemical performance than bare Na2Li2Ti6O14, especially for Na1.9Nb0.1Li2Ti6O14, which can deliver the highest reversible charge capacity of 259.4 mAh g(-1) at 100 mA g(-1) among all samples. Even when cycled at higher rates, Na1.9Nb0.1Li2Ti6O14 still can maintain excellent lithium storage capability with the reversible charge capacities of 242.9 mAh g(-1) at 700 mA g(-1), 216.4 mAh g(-1) at 900 mA g(-1), and 190.5 mAh g(-1) at 1100 mA g(-1). In addition, ex situ and in situ observations demonstrate that the zero-strain characteristic should also be responsible for the outstanding lithium storage capability of Na1.9Nb0.1Li2Ti6O14. All of this evidence indicates that Na1.9Nb0.1Li2Ti6O14 is a high-performance anode material for rechargeable lithium ion batteries.

The Effect of CO2 on Alkyl Carbonate Trans-Esterification during Formation of Graphite Electrodes in Li-Ion Batteries

Graphite is the most widely used anode material in Li-ion batteries due to its excellent lithium storage capability as well as long-term and cycle stability. Carbonate-based electrolytes are reduced on the graphite surface and form a solid electrolyte interface (SEI) within the first few cycles. The passivating layer inhibits continuous electrolyte decomposition by blocking the electron transport while allowing Li-ions to pass through. Additives are often used to influence the SEI chemistry [1]. Most studies focus on the composition of the SEI and investigate the insoluble products deposited onto the graphite surface by FTIR and XPS [2]. In this work, we employ on-line electrochemical mass spectrometry (OEMS) to analyze in a complementary manner the gas evolution and change of volatile electrolyte components during the formation of graphite electrodes, using a sealed 2-compartment cell [3]. Figure 1 shows the electrochemical and mass spectrometric data for the first CV cycle of a SLP30 graphite electrode vs. metallic lithium in LP57 electrolyte (1M LiPF6 in EC:EMC, 3:7 by weight). It is apparent that C2H4 is the main gas evolved during SEI formation, according to the reduction of EC in Eq. (1) [4]. However, the gases H2, CO, and CO2can also be quantified and reveal the important processes at the electrode-electrolyte interface. The evolution of CO is accompanied by the release of lithium alkoxides LiOR which initiate the conversion of EMC into DMC and DEC, as illustrated in Eq. (2) [5,6]. The trans-esterification causes the change of many different mass signals such as m/z = 15, 31, 77 related to the fragmentation patterns of the linear carbonates (EMC, DMC, DEC). OEMS data suggest that the reaction starts in parallel to the reduction of EC and proceeds quantitatively in LP57 electrolyte. In contrast, the addition of VC decreases the released amount of C2H4 by more than half and prevents successfully the trans-esterification [7]. Its positive effect seems not only be based on the incorporation of reduction products such as poly(VC) into the SEI but also on the evolution of CO2 which may trap lithium alkoxides, as proposed in Ref. [1]. Based on this assumption, the influence of CO2 in the head space of the cell is investigated in pure LP57 electrolyte, focusing on the extent of trans-esterification. To gain a mechanistic insight into the reaction, the formation of graphite electrodes is repeated in the model electrolyte 1M LiPF6 in EMC which reflects solely the reactivity of EMC without the interaction of EC, accelerating its conversion. The results may contribute to elucidate in general the role of CO2 in CO2-forming additives such as VC and FEC.

Fe3O4–carbon nanocomposites via a simple synthesis as anode materials for rechargeable lithium ion batteries

Fe3O4–carbon nanocomposites have been synthesized simply with a hydrothermal method free of template that is followed by an annealing process. The morphological and compositional analysis reveals that the inter-separated Fe3O4 nanocrystals with a size of ~10 nm are homogeneously embedded within the mesoporous carbon matrix. The interesting configuration is evaluated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman, energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Benefiting from the advantages of good buffering and electric conductivity, the nanocomposite delivers an initial capacity of 1706 mAh g−1 at 0.2 C (1 C = 1 A g−1). Besides excellent lithium storage capability, it exhibits a superior cycling stability with more than 100% capacity retention after 100 cycles at 0.2 C and 1 C. When successively discharging at variable rates, the nanocomposite retains a reversible capacity of 1249 mAh g−1 at 0.1 C, 690 mAh g−1 at 1 C, and 311 mAh g−1 at 10 C. With excellent capability and rate performance, the Fe3O4–carbon nanocomposites may be a promising anode material of lithium ion batteries (LIBs) for the green large-scale production.