Transition Metal Oxide Anodes Research Articles

A Hierarchically Nanostructured Composite of MoO3-NiO/Graphene for High-Performance Lithium-Ion Batteries

Abstract Bicomponent transition metal oxide (TMO) anodes have attracted increased attention for the application in high-performance lithium-ion batteries (LIBs). In this work, MoO3-NiO/graphene (MNG) composite was fabricated by one-pot method. Results showed that ultrafine MoO3 nanosheets and NiO nanoparticles were homogeneously anchored on the graphene layers, which is benefit for short Li+ diffusion distance, fast reaction kinetics, and low volume expansion. The as-prepared MNG composite exhibited remarkable electrochemical properties as lithium-ion battery anodes with high specific capacities of 1164 mAh/g at 100 mA/g after 50 cycles and 946.9 mAh/g at 1000 mA/g after 180 cycles. This work indicates that the MNG composite would be a promising anode material for high-performance LIBs.

Extremely pseudocapacitive interface engineered CoO@3D-NRGO hybrid anodes for high energy/ power density and ultralong life lithium-ion batteries

Although secondary Li-ion batteries are widely used for electrochemical energy storage, low energy (100–300 Wh kg−1) and power density (250–400 W kg−1) are limiting their applications in several areas including long-range electric vehicles. Herein, we demonstrate high energy (400 Wh kg−1) and power density (1 kW kg−1) Li-ion batteries (considering the weight of both electrodes) based on extremely pseudocapacitive interface engineered CoO@3D-NRGO hybrid anodes. These values are 2.8 and 2.3-fold higher respectively compared to graphite‖LiNiMnCoO2 full-cells under similar experimental conditions. Three-dimensional anode architecture presented here composed of ultrafine CoO nanoparticles (∼10 nm) chemically bonded to nitrogen-doped reduced graphene-oxide. This hybrid anode demonstrated excellent pseudocapacitance (∼92%), specific capacity (1429 mAh g−1 @ 25 mA g−1), rate performance (906 mAh g−1 @ 5 A g−1), and cycling stability (990 mAh g−1 after 7500 cycles @ 5 A g−1). Outstanding electrochemical performance of CoO@3D-NRGO‖LiNiMnCoO2 full-cells is credited to the extreme pseudocapacitance of CoO@3D-NRGO anode resulting from Li2O/Co/NRGO nanointerfaces and Co–O–C bonds. The demonstrated strategy of interfacial engineering can also be extended for other environmental friendly/inexpensive transition metal oxide (Fe2O3, MnO2 etc.) anodes for high energy/power density and ultra-long-life Li-ion batteries.

Crystalline Planes templated engineering of defect chemistry in Cobalt(II, III) oxide anodes for lithium ion batteries

Transition metal oxide (TMO) anodes show promising applications in energy storage due to the unique physical and chemical properties and high theoretical capacity to storage ions. Their practical usages are restricted by low intrinsic electronic conductivity, sluggish ionic diffusion, and large volume change during continuous cycling. In this work, we propose a strategy of selective solution-phase reduction on specific crystalline planes to generate the defect chemistry and thus improve the intrinsic electronic conductivity. Taking Co3O4 electrode as a typical example, we prepared the structures with different exposed planes, which were then subjected to solution-phase reduction at room temperature. When used as the electrodes for lithium ion batteries, the optimized material possesses a high reversible capacity of 873.5 mAh g−1 at a current of 0.1 A g−1, even at a large current density of 5 A g−1, a remarkable discharge capacity of 569.1 mA h g−1 can still be achieved. The improved performance is attributed to the synergistic effects of the optimized amount of Co2+ species and oxygen vacancies. The current strategy can be extended to other TMO electrodes, paving an alternative way to optimize the electrochemical performance for different applications.

Oxygen-Vacancy-Abundant Ferrites on N-Doped Carbon Nanosheets as High-Performance Li-Ion Battery Anodes.

Transition metal oxides, as one of the most promising anode materials for lithium-ion batteries, often suffer from poor electronic conductivity and serious structural collapse. In this work, oxygen-vacancy-abundant CoFe2 O4 and NiFe2 O4 deposited on N-doped carbon nanosheets are designed and fabricated through a calcination procedure and a solvothermal strategy using Zn-hexamine coordination frameworks as precursors. The as-prepared NC@CoFe2 O4 and NC@NiFe2 O4 hybrids display improved cycle performances and rate capacities compared with CoFe2 O4 , NiFe2 O4 , and Fe2 O3 . The enhanced lithium storage performances of NC@CoFe2 O4 and NC@NiFe2 O4 are attributed to the oxygen vacancies and conductive N-doped carbon nanosheets, which increase the electronic conductivity and electrochemical reaction kinetics. The synthetic process in this work provides a new perspective for designing other high-performance transition metal oxide anodes.

Rhombic dodecahedron-like CoMoO4/C composite: A facile construction and excellent electrochemical performances for lithium-ion batteries

The design of an unique micro/nanoscale structure and the composite construction with conductive materials are the two effective means to improve the electrochemical energy storage for transition metal oxides anode. However, the rational design and controllable synthesis of complex ternary transition metal oxide (such as CoMoO4) composite with polyhedron morphology is still a challenge. Herein, we report a facile and effective strategy to synthesize rhombic dodecahedron-like (denoted as RD-like) CoMoO4/C composite, which involves the initial pre-reaction between the newly made ZIF-67 with H2MoO4 in ethanol and the subsequent calcination for the resultant precursor powders in air. It is found that the calcination temperature plays a key role in determining the microstructures and the content of the generated activated carbon. Below 400 °C, the CoMoO4/C composite cannot be derived, whereas the perfect and regular RD morphology for CoMoO4/C composite also cannot be acquired over 500 °C. Moreover, a plausible mechanism for the construction of RD-like CoMoO4/C composite has also been proposed and explained. Benefiting from its unique structural merits and the significant synergistic effect of the in-situ composite activated carbon, the obtained RD-like CoMoO4/C composite at 500 °C displays outstanding electrochemical performances with high reversible capacity (532.5 mAh g−1/500th cycle at 1C), excellent cycling stability and better rate capability when it tested as anode materials for lithium-ion batteries. It is conceivable that this three-in-one strategy can be extended to design and construct other cobalt-based oxyacid/C composites with unique polyhedron morphology, and markedly boost their electrocehmical performaces.

Spinel-structured high entropy oxide (FeCoNiCrMn)3O4 as anode towards superior lithium storage performance

High entropy oxide (HEO) is a new-type inorganic material composed of multiple principle metal elements with a single-phase structure and is proved to display many potential unexpected properties such as high structural stability and superionic conductivity. Herein, a novel spinel-structured high entropy oxide (FeCoNiCrMn)3O4 is prepared by high-temperature solid state reaction and evaluated as anode for lithium-ion batteries (LIBs). In-situ high-temperature X-ray diffraction (HT-XRD) is used to reveal structure evolution of mixed oxides with the calcination temperature increase and a single-phase spinel-structured (FeCoNiCrMn)3O4 is obtained at 900 °C. The effect of temperature on structure and electrochemical performance of HEO were investigated, and the HEO-900 anode with commercial mass loading exerts higher capacity (discharge/charge, 1034/680 mAh g−1) and better rate capability (182 mAh g−1 at 2 Ag-1) than HEO-950 and HEO-1000 for its moderate particle size, and all the three samples show excellent cycling stability. Ex-situ XRD and transmission electron microscope are applied to unravel the lithium-storage mechanism of (FeCoNiCrMn)3O4, an amorphization reaction process occurs during the initial discharging and the amorphous structure is maintained in subsequent cycles. The synergetic effect of multiple metal cations with different radius, valence states and reaction potentials and entropy stabilization effect make the HEO display a superior electrochemical performance in LIBs. This work provides a new concept to design multi-element transition metal oxide anode materials by high entropy strategy.

Binder-free 3D porous Fe3O4–Fe2P–Fe@C films as high-performance anode materials for lithium-ion batteries

Slow lithium storage reaction kinetics and huge volume changes are the main limiting factors for the large-scale application of transition metal oxide anode materials for lithium ion batteries. Developing multi-structure and carbon coating films is a promising solution. Herein, a facile strategy for synthesizing novel binder-free 3D porous Fe3O4–Fe2P–Fe@C films is proposed based on the electrodeposition of self-supporting porous FeOOH–FeP–Fe films, glucose coating to form FeOOH–FeP–Fe@Glucose films, and oxygen-free annealing treatment for the decomposition of FeOOH into Fe3O4, phase separation of FeP into Fe2P–Fe3P and pyrolysis of glucose into C. The binder-free Fe3O4–Fe2P–Fe@C film anode exhibits high reversible capacity (914 mA h g−1 after 200 cycles at 0.1 A g−1), superior rate capability (518 mA h g−1 at 5 A g−1), and stable long cycling performance (723 mA h g−1 after 500 cycles at 2 A g−1). The excellent lithium storage performance of the Fe3O4–Fe2P–Fe@C anode is attributed to the synergistic effects of the self-supporting 3D porous film structure, multi-phase structure, and carbon coating, which not only enhances the Li+ and electron transport to accelerate the reaction kinetics, but also buffers the volume changes to improve the structure stability during reversible charge-discharge process.

Fabrication of Ta2O5@C/F composite nanotubes as stable anode material for Lithium-ion batteries

In this paper, helical mesoporous Ta2O5 nanotubes and Ta2O5/fluorine-doped carbon composite nanotubes (Ta2O5@C/F) (~9 wt% of C and ~1 wt% of F) were prepared via a sol–gel method, using a chiral gelator as the template. Electrochemical studies showed that, the Ta2O5 nanotubes electrode and Ta2O5@C/F nanotubes electrode both possessed good Li-storage capability and cycling stability. The reversible capacity of Ta2O5@C/F was higher than that of Ta2O5, while the impedance of Ta2O5@C/F was lower than that of Ta2O5. These results indicated that the coating of fluorine-doped carbon layer could effectively improve the electrochemical performance of transition metal oxide anodes.

ZnMn2O4/milk-derived Carbon hybrids with enhanced Lithium storage capability

One of the effective ways to improve the conductivity and structural stability of binary metal oxide nanostructures is to tightly composite them with nano-carbon materials with excellent conductivity. However, the introduction of low density carbon materials also reduces the energy density of batteries. Therefore, we provides a new idea to enhance the lithium storage performance of carbon/binary transition metal oxide anode materials by multi-element co-doping carbon. ZnMn2O4 provides high lithium storage capacity; non-metallic heteroatoms in milk-derived carbon greatly improve the conductivity of carbon materials; metal heteroatoms in milk-derived carbon increase the density of carbon materials. Multicomponent co-doping carbon can build up the mass specific capacity, ratio performance, cyclic life and mechanical properties of binary metal oxides/porous carbon nanocomposites. As the anode materials of lithium-ion batteries, the ZnMn2O4/MC (milk-derived carbon) hybrids deliver a high reversible capacity of 1352 mAh g−1 after 400 cycles at 0.1 A g−1, and a remarkable long-term cyclability with 635 mAh g−1 after 300 cycles at 1.0 A g−1.

Transition Metal Oxide Anodes for Electrochemical Energy Storage in Lithium‐ and Sodium‐Ion Batteries

AbstractLithium‐ion batteries (LIBs) with outstanding energy and power density have been extensively investigated in recent years, rendering them the most suitable energy storage technology for application in emerging markets such as electric vehicles and stationary storage. More recently, sodium, one of the most abundant elements on earth, exhibiting similar physicochemical properties as lithium, has been gaining increasing attention for the development of sodium‐ion batteries (SIBs) in order to address the concern about Li availability and cost—especially with regard to stationary applications for which size and volume of the battery are of less importance. Compared with traditional intercalation reactions, conversion reaction‐based transition metal oxides (TMOs) are prospective anode materials for rechargeable batteries thanks to their low cost and high gravimetric specific capacities. In this review, the recent progress and remaining challenges of conversion reactions for LIBs and SIBs are discussed, covering an overview about the different synthesis methods, morphological characteristics, as well as their electrochemical performance. Potential future research directions and a perspective toward the practical application of TMOs for electrochemical energy storage are also provided.

Electrochemical Performance of Co3O4 Nanofibers As Anode Material for Lithium-Ion Batteries

Nanostructuring is a promising approach to the problems of low diffusion coefficient of transition metal oxides anodes. Co3O4 nanofibers electrode materials were successfully synthesized by electrospinning followed by controlled pyrolysis. Electrode materials based on Co3O4 nanofibers applied as anode for lithium-ion batteries (LIBs) show high discharge-charge specific capacity of 595 and 527 mA h g–1 at 0.5C, respectively. Further electrochemical investigation reveals that Co3O4 nanofibers exhibiting high specific capacity (300 mA h g−1 at 0.5C after 200 cycles), the capacity fading is only 11.8% after 200 cycles. Further electrochemical studies reveal that these excellent electrochemical properties should be attribute to the ordered ions diffusion pathway originated from the one-dimensional nanostructure and continuous fibrous network structure. These results revealed that the Co3O4 nanofibers are promising anode materials for LIBs.

Trimetallic MOF-Derived Cu0.39Zn0.14Co2.47O4–CuO Interwoven with Carbon Nanotubes on Copper Foam for Superior Lithium Storage with Boosted Kinetics

Transition metal oxides (TMOs), identified as a potential candidate for high-energy anode materials for state-of-the-art lithium-ion batteries (LIBs), suffer from the inherent defects of low electronic conductivity and dramatic volume variation, hindering their practical applications. It is still a great challenge to synthesize novel TMO anodes with satisfactory lithium storage performance. Herein, trimetallic Zn–Co–Cu-zeolitic imidazolate framework is designed with carbon nanotubes (CNTs) and copper foam (CF) serving as multifunctional bridges by postsynthetic metal-ion exchange and in situ solvothermal growth. After annealing, a novel trimetallic metal–organic framework (MOF)-derived polymetallic oxide, Cu0.39Zn0.14Co2.47O4–CuO@CNTs/CF hybrid, was successfully prepared. The introduction of conductive CNTs and a three-dimensional (3D) CF substrate effectively boosts the mechanical robustness and electronic conductivity of metal oxide composites, accelerates the lithium-ion diffusion, and reduces the impe...

Three-dimensional porous Co3O4–CoO@GO composite combined with N-doped carbon for superior lithium storage

Transition metal oxides (TMOs) as anode materials have potential for lithium-ion batteries (LIBs). However, the poor rate capacity and cycle stability restrict its application. Herein, we demonstrate a facile one-step hydrothermal method to construct a three-dimensional porous conductive network structure, which consists of thin-layered graphene, ultrafine Co3O4–CoO nanoparticles and nitrogen-doped carbon. This unique structure can effectively prevent particle agglomeration and cracking caused by volume expansion, provide fast passage for lithium ion/electron transport during cycling and improve the electrical conductivity of the electrode. Moreover, the electrochemical kinetic analysis proves that this is a process dominated by pseudocapacitive behavior. Consequently, the N-C@Co3O4–CoO@GO hybrid electrode delivers an ultrahigh capacity of 1 273.1 mA h g−1 at 0.1 A g−1 and superior rate performance (725.1 mA h g−1 at 5 A g−1). Additionally, it exhibits a high reversible cycling capacity of 787.4 mA h g−1 at 1 A g−1 over 600 cycles and even maintains excellent cycling stability for a ultra-long cycles at 5 A g−1. This work provides a feasible strategy for fabricating the N-C@Co3O4–CoO@GO composite as a promising high-performance TMOs anode for LIBs.

Three-dimensional mesoporous sandwich-like g-C3N4-interconnected CuCo2O4 nanowires arrays as ultrastable anode for fast lithium storage

Inspite of their impressive high theoretical capacity as Lithium-ion batteries (LIBs) anodes, spinel transition-metal oxides (TMOs) suffer serious volume expansion, aggregation and the pulverization of crystal structures during lithiation/delithiation, and this process severely restrict their industrial application. Multi-dimensional morphological engineering of spinel TMO nanostructures is an effective way to solve this issue. In this work, using facile hydrothermal synthetic methods, spinel CuCo2O4 nanowires arrays are synthesized and supported on g-C3N4 nanosheets, thus forming a unique sandwich-like interconnected three-dimensional mesoporous structure containing high amount of void spaces. Addition of g-C3N4 nanosheets to CuCo2O4 nanowire arrays may shorten the Li+ diffusion distance and electron transfer pathway, and may also provide more active sites for Li+ diffusion into electrolyte and buffer for the volume expansion and aggregation of CuCo2O4. As a LIB anode material, CuCo2O4@g-C3N4 shows initial lithiation capacity of 840.6 mAh g−1, and capacity retention of 641.2 mAh g−1 after 60 cycles at the current density of 0.1 A g−1 and 499.2 mAh g−1 after 40 cycles at high current of 1 A g−1, which is significantly better than value of pure CuCo2O4 nanowires. This work affords a new way to tackle the problem of volume expansion of high capacity spinel TMO anode materials using g-C3N4 nanosheets as buffering agent.

Understanding aggregation hindered Li-ion transport in transition metal oxide at mesoscale

Conversion based transition-metal oxides as a promising class of anode materials, require proper nanostructuring for enhanced Li-ion storage capabilities. However, aggregation is found to be a common issue in nanomaterial systems, and can have detrimental effects on transport properties in composite electrodes. By employing a model transition-metal oxide anode with unique two-dimensional holey nanostructures, we investigated underlying reasons for the limited electrochemical kinetics induced by mesoscale aggregation. Through combined electrochemical and in situ characterization techniques, we demonstrate that aggregation leads to hindered interfacial charge transfer and retarded phase transformation, with the influence on kinetics escalating with more aggregation. These results shed light on more dedicated structural design for effective battery electrodes across multiple length scales.

An Upgraded Lithium Ion Battery Based on a Polymeric Separator Incorporated with Anode Active Materials

AbstractStructural/compositional characteristics at the anode/electrolyte interface are of paramount importance for the practical performance of lithium ion batteries, including cyclic stability, rate capacity, and operational safety. The anode‐electrolyte interface with traditional separator technology is featured with inevitable phase discontinuity and fails to support the stable operation of lithium ion batteries based on large‐capacity anodes with structural change in charges/discharges, such as transition metal oxide anodes. In this work, an anode/electrolyte framework based on an oxide anode and an active‐oxide‐incorporated separator is proposed for the first time and investigated for lithium ion batteries. The architecture builds a robust anode‐separator interface in LIBs, shortens Li+ diffusion path, accelerates electron transport, and mitigates the volume change of the oxide anode in electrochemical reactions. Remarkably, 4 wt% CuO addition in the separator leads to a 17% enhancement in the overall capacity of a battery with a CuO anode. The battery delivers an unparalleled record reversible capacity of 637.2 mAh g−1 with a 99% capacity retention after 100 charge/discharge cycles at 0.5 C. The high performance are attributed to the robust anode‐separator interface, which gives rise to enhanced interaction between the oxide anode and the same‐oxide‐incorporated composite in the separator.

Enhanced electrochemical performance by size-dependent SEI layer reactivation of NiCo2O4 anodes for lithium ion batteries

Under over-increasing demand of advanced lithium-ion batteries (LIBs) for long-range electric vehicles (EVs), high-capacity transition metal oxide (TMO) negative electrodes for LIBs are thought as potential substitutes of traditional graphite anodes. A major barrier for TMO anodes is volumetric expansion during lithiation processes, leading to active material pulverization and falling off current collectors, which seriously deteriorates capacity retention. Herein, apart from conventional mechanical degradation, another capacity fading mechanism is revealed. Furthermore, the understanding is supported by an interesting cycling property. Firstly, NiCo2O4 with designed morphologies of nanoplates and microspheres are studied for the initial (de)lithiation and prolonged cycles. The morphology changes indicate solid electrolyte interphase (SEI) layer accumulating on the surface of electrodes and impeding the contact and reactions between lithium and active materials with a result of severe capacity loss. It can be understood as SEI layer insulating NiCo2O4, and if SEI film appropriately changes, high capacities can recovery. This conjecture is confirmed by following research of NiCo2O4 nanoparticles with amazing cycling performance prepared by a facile water-bath method. As LIB anodes, NiCo2O4 nanoparticles exhibit capacities of 1144 mAh g−1 at the initial discharging, 230 mAh g−1 at the 100th cycle and 661 mAh g−1 at the 500th cycle. The corresponding coulombic efficiency is of 73.1%, 98.4% and 99.5%, respectively. By TEM characterization in combination with electrochemical analysis, size-dependent SEI layer reactivation (from thick and unstable to thin and stable) is a key role on the dramatic capacity recovery.

Suppressing volume change and in situ electrochemical atom force microscopy observation during the lithiation/delithiation process for CuO nanorod array electrodes

A big challenge in the high-performance transition metal oxide anode for lithium-ion batteries (LIBs) is relieving the volume changes during the lithiation/delithiation. In this work, CuO nanorod array was produced via glancing angle deposition and directly used as anode materials for thin film electrodes of LIBs. The obtained CuO nanorod array anodes show good LIB performance with a capacity of 220 μAh/cm2/μm tested at 100 μA/cm2 after 80 cycles and excellent rate performance. The obtained properties for CuO nanorod array anodes were much better than thin film anodes without nanorod array structure. In addition, the in situ electrochemical atom force microscopy (EC-AFM) characterization has been used to reveal the enhanced mechanism of CuO nanorod array anodes. On the one hand, CuO nanorods within the electrodes may serve as the hosts for Li+, and ease intercalation by shortening Li+ ion diffusion pathways, resulting in the remarkable cycling stability and rate performance. On the other hand, the “breathing” of CuO nanorod array electrode clearly observed by in situ EC-AFM with the appearance and disappearance of cracks, demonstrated that the nanorod array may act as a buffering to alleviate the giant volume variations during the cycling. As a result, the remarkable stability of the CuO nanorod array electrode allowed its use in a full lithium-ion cell with a pervasive LiCoO2 thin film cathode. Additionally, we also observed the SEI formed on the surface of electrode during cycling, which may benefit the further studies on transition metal oxide as anodes for LIBs.

Large-scale synthesis of hierarchical SnO spheres assisted with poly (N-isopropylacrylamide) for high lithium storage capacity

Hierarchical tin monoxide (SnO) spheres were successfully prepared by using a new facile route, i.e., a one-pot method in an aqueous solution with the assistance of a thermosensitive polymer, poly (N-isopropylacrylamide) (PNIPAM), acting as a surfactant. The synthesized SnO spheres were assembled from irregular SnO nanosheets, which have a thickness of 20 nm and are several nanometers in length, with a rough surface homogeneously decorated by SnO nanoparticles. The formation of this hierarchical structure is achieved through the cooperation of the template-directing growth and self-assembly process. The electrochemical performance of hierarchical SnO was examined as an anode material for lithium-ion batteries. The as-synthesized SnO leads to an excellent electrochemical performance as characterized by the high specific capacity (275 mAh g−1 at 500 mA g−1), cycling stability (400 mAh g−1 after 70 charge-discharge cycles at 200 mA g−1 with 49% capacity retention), and high rate performance (119 mAh g−1 at 1 A g−1). This one-step facial method may provide an attractive alternative approach to the large-scale preparation of high-purity and low-valence transition metal oxides (TMOs) anode materials.

Revisiting Solid Electrolyte Interphase on the Carbonaceous Electrodes Using Soft X-ray Absorption Spectroscopy.

It is widely accepted that solid electrolyte interphase (SEI) layer of carbonaceous material is formed by irreversible decomposition reaction of an electrolyte, and acts as a passivation layer to prevent further decomposition of the electrolyte, ensuring reliable operation of a Li-ion battery. On the other hand, recent studies have reported that some transition metal oxide anode materials undergo reversible decomposition of an organic electrolyte during cycling, which is completely different from carbonaceous anode materials. In this work, we revisit the electrochemical reaction of an electrolyte that produces SEI layer on the surface of carbonaceous anode materials using soft X-ray absorption spectroscopy. We discover that the reversible formation and decomposition of SEI layer are also able to occur on the carbonaceous materials in both Li- and Na-ion battery systems. These new findings on the unexpected behavior of SEI in the carbonaceous anode materials revealed by soft X-ray absorption spectroscopy would be highly helpful in more comprehensive understanding of the interfacial chemistry of carbonaceous anode materials in Li- and Na-ion batteries.