High-rate Long-term Cycling Research Articles

Encapsulating Mn-Fe prussian blue analog nanocuboids into the graphene framework towards fast and durable sodium storage

The exploration of high-performance sodium-ion hosts is an important issue in the field of advanced energy storage and conversions. Herein, MnFe PBA/rGO composite was prepared by simple coprecipitation and in situ synthesis, and realized the fast kinetics and superior stability for sodium storage. The rGO nanosheets were introduced as the framework to encapsulate the MnFe PBA nanocuboids with uniform particle size and well-defined configuration to further enhance their electrical conductivity and electrochemical properties. The prepared MnFe PBA/rGO composite exhibits superior charge/discharge properties than the pristine MnFe PBA nanocuboids, which show a capacity enhancement of over 30%. In addition, the PBA/rGO composite exhibits excellent cycling stability, which retains 80% of the capacity after 1000 cycles at a high rate of 1 A/g. The electrochemical impedance spectroscopy (EIS) results further demonstrate the low resistance, high durability, and ultrahigh stability of the MnFe PBA/rGO composite during high-rate long-term cycling. Therefore, this work not only provides a high-performance sodium host but also gives a new clue to the design and construction of highly efficient electrode materials for advanced electrochemical systems.

Covalent sulfur/CoS2-decorated honeycomb-like carbon hierarchies for high-performance sodium storage with ultra-long high-rate cycling stability

Transition metal sulfides (TMSs) with high theoretical sodium storage capacity have been regarded as one of the most competitive and promising anode materials for sodium-ion batteries. Nevertheless, great challenges still exist for TMS to achieve long-cycle life owing to the poor conductivity and volume expansion during the sodiation/desodiation process. The conventionally used pure carbon coating method can effectively solve the above problems. However, the low sodium ion storage capability of carbon will decrease the capacity of the anode. Thus the functionalization of well-designed carbon nanostructures with exotic elements (e.g., sulfur) or high-specific-capacity materials has been regarded as an efficient route to enhance sodium storage performance. Herein, we developed a facile strategy to incorporate covalent sulfur and CoS2 nanoparticles into honeycomb-like carbon matrices (denoted as S/CoS2@C), where sulfur is vaporized under vacuum and reacted with the Co-decorated carbon hierarchies, leading to the formation of CoS2 nanoparticles as well as the covalent C–Sx–C bonds. Consequently, the as-prepared S/CoS2@C composite demonstrates excellent sodium storage performance, with high initial coulomb efficiency (ICE) of 83 % and capacity retention of 95 % (478.5 mAh g−1) after 700 cycles at 0.2 A g−1, and an outstanding high-rate long-term cycling stability with a high reversible capacity of 396.1 mAh g−1 after 5000 cycles at 2 A g−1 (an average decay rate of only 0.0014 %). Furthermore, electrochemical analyses reveal that both covalent sulfur and CoS2 contribute to the sodium storage capacity via a predominantly surface-induced capacitive process, and the well-designed S/CoS2@C composite with encapsulation of covalent sulfur and CoS2 into the highly interconnected porous carbon matrices efficiently buffer the volume changes and well maintain the electrode integrity/conductivity upon sodiation/desodiation cycling.

Yolk–shell tin phosphides composites as superior reversibility and stability anodes for lithium/sodium ion batteries

The rational design of nanostructure is crucial to achieving high-rate and long-term cycling performance for electrodes. Herein, the tin phosphide composites with yolk–shell nanostructure (SnxPy/NG) are designed and synthesized by one-step carbonization and phosphorization from the precursor of Sn6O4(OH)4/NG. The SnxPy/NG electrode with yolk–shell nanostructure shows energy storage properties superior to that of nanoclusters or nanoparticles. The void space in yolk–shell nanostructure relieves the huge volume expansion, and the unique phase hybridization of Sn4P3 and SnP0.94 promotes the reaction kinetics. Thus, SnxPy/NG delivers high-rate long-term cycling stability for Li-half cells (521.2 mA h g−1 maintained after 3000 cycles at 5.0 A g−1) and Na-half cells (203.1 mA h g−1 maintained after 300 cycles at 1.0 A g−1). The design strategy can promote the practical application of Sn-based phosphide and pave the way for designing and exploring other metal-based phosphide electrodes for energy storage.

Rational design of ZnMn2O4 nanoparticles on carbon nanotubes for high-rate and durable aqueous zinc-ion batteries

ZnMn2O4 (ZMO) is a promising cathode material for aqueous zinc-ion batteries (ZIBs) due toits high capacity, high output voltage and rich abundance. However, the commercial application of ZMO is severely restricted by the rapid capacity decay at high rate resulting from low electrical conductivity and structural degradation. Herein, a commonplace one-step hydrothermal method is applied to rationally synthesize ZMO nanoparticles (∼20 nm) on carbon nanotubes (ZMO/CNTs) heterostructure for stable high-rate Zn2+ storage. The high electrical conductive CNTs and such small ZMO benefit from electrons’ fast transport, endowing ZMO/CNTs composite with high electrical conductivity. Furthermore, the flexible CNTs network and the strong interface interaction (Mn-O-C bond) between ZMO and CNTs can effectively suppress irreversible structural degradation. As a result, the ZMO/CNTs composite delivers a promising initial capacity of 220.3 mAh g−1 at 100 mA g−1 and a high capacity retention of 97.01% after 2000 cycles at 3000 mA g−1, indicating excellent high-rate long-term cycling stability. Furthermore, the flexible ZIBs are assembled and show stable electrochemical properties at different bending states, demonstrating their potential practical applications.

Twin boundary CdxZn1−xS: a new anode for high reversibility and stability lithium/sodium-ion batteries

CdxZn1−xS-B with a twin boundary structure are investigated as anode materials for LIBs/SIBs, and high-rate long-term cycling stability is delivered.

Metal-organic framework derived vanadium-doped TiO2@carbon nanotablets for high-performance sodium storage

Titanium dioxide (TiO2) as a potential anode material for sodium-ion batteries (SIBs) suffers from the intrinsic poor electronic conductivity and sluggish ionic diffusivity, thus usually leading to the inferior electrochemical performance. Herein, we demonstrate a facile strategy to enhance the sodium storage performance of TiO2via vanadium (V) doping, using the pre-synthesized V-doped Ti-based metal–organic framework (MOF, MIL-125) as the precursor, which can be converted into the V-doped TiO2 with simultaneous carbon hybridization and controlled V-doping amount (denote as VxTiO2@C, where × represents the V/Ti molar ratio (RV/Ti)). V-doping not only affects the morphology of the MIL-125 changing from thick to thin nanotablets, but also greatly enhances the electrochemical performance of the VxTiO2@C. When used as an anode for SIBs, the V0.1TiO2@C exhibits a much higher reversible capacity of 211 mAh/g than that for the undoped TiO2@C (only 156 mAh/g) after 150 cycles at 100 mA/g. Even after high-rate long-term cycling, the V0.1TiO2@C can still display a capacity of 180 mAh/g with a high capacity retention of 137% at 1000 mA/g after 4500 cycles. Structural/electrochemical measurements reveal that V-doping induces the formation of oxygen vacancies as well as Ti3+ species, which efficiently improve the electric conductivity and the ion diffusivity of the electrode. Meanwhile, the thinner V0.1TiO2@C nanotablets with porous structure and carbon hybridization could facilitate the ion/electron transfer with shortened diffusion pathways.

Interface-strain-confined synthesis of amorphous TiO2 mesoporous nanosheets with stable pseudocapacitive lithium storage

• A largescale salt-template method is developed to prepare conformable amorphous TiO 2 mesoporous nanosheets. • Interfacial strain between salt and TiO 2 is revealed to assist to suppress the amorphous-to-crystalline transformation. • This amorphous TiO 2 possesses ultrathin structure and rich mesopores that are beneficial for fast lithium-storage. • Remarkable high-rate long-term cycling stability (103 mA h g −1 at 6 A g −1 after 1000 cycles) are demonstrated. Amorphous nanomaterials recently have been demonstrated as a new type of high-power electrodes for many electrochemical energy-storage devices owing to their structural advantages of large surface area, shortened ion-diffused pathway, rich surficial defects and loosely packed structure; However, it is still challenging to prepare amorphous nanomaterials on a large scale via low-cost sol–gel method due to the easy amorphous-to-crystalline transformation upon post calcination process. Herein, we develop a simple and scalable approach to prepare amorphous TiO 2 mesoporous nanosheets by using the potassium chloride (KCl) as the template. The experimental results combined with density functional theory (DFT) calculations have revealed that the interfacial strain between the KCl and TiO 2 suppresses the crystallization of TiO 2 , which maintains amorphous characteristics even at a relative high temperature of 400 °C. Benefiting from short Li + -diffused distance, accessible mesoporous structure, and surface pseudo-capability, the amorphous TiO 2 nanosheet electrode exhibits fast and durable lithium-storage/-release ability, such as delivering a high reversible capacity of 103 mA h g −1 at 6 A g −1 after 1000 cycles. This study may pave a new way for the design of amorphous nanoarchitectures, and highlight the function of the templates, not only leading to the formation of various morphologies, but also affecting the surface microstructure.

Building defect-rich oxide nanowires@graphene coaxial scrolls to boost high-rate capability, cycling durability and energy density for flexible Zn-ion batteries

Transition metal oxides with earth abundance and high theoretical capacity have received ever-growing interests as promising cathode materials for aqueous zinc-ion batteries (ZIBs). However, their semiconducting nature and poor conductivity lead to the kinetically sluggish rate and poor electrochemical reversibility. Herein, a novel defect-rich oxide nanowire filled graphene scrolls (denoted as DNGS) is introduced as a high-performance cathode for ZIBs. The 1D ultrathin oxide nanowires with defective nature are enwrapped in the center of the graphene scrolls, forming the core-shell coaxial scrolls. Benefitting from the highly conductive graphene network and 1D structured oxide with defect-rich structure, the DNGS hybrid scrolls achieve fast electron/ion transport, high electrochemical reversibility and superior energy storage capability. For the first time, the defect-rich vanadate oxide (V6O13-δ) is employed to construct the DNGS structure. The evolution of the DNGS structure is probed and the sequential mechanism based on the “oriented growth, self-assembly and self-rolling” process is disclosed. Both experimental and theoretical analyses demonstrate the significant increase in the electronic conductivity, ionic diffusion capability and electrochemical properties of the DNGS hybrid scrolls in comparison with the reference ones. The DNGS sample achieves ultrafast discharge capability and excellent deep cycling stability. Moreover, the flexible ZIBs based on the DNGS cathode display excellent high-rate long-term cycling stability (97% after 1000 cycles at alternative 13 and 4 A g−1) and admirable energy density (max. 231 mWh cm−3). Even under severe external deformation, the superior properties are well-retained which prove their high reliability. Therefore, this work not only provides a highly efficient structure to improve properties of oxides, but also propel the development of ZIBs for broadened applications.

Intrinsic performance regulation in hierarchically porous Co3O4 microrods towards high-rate lithium ion battery anode

The hierarchically porous Co3O4 microrods made up of orientated self-assembled nanorods are fabricated through a facile strategy, which possess bicontinuous mesopores and one dimensional macropores. Oxygen vacancies are successfully introduced into Co3O4 microrods by simply controlling the heating temperature. When applied into lithium ion batteries as anode materials, local in-plane electric fields induced by the introduced oxygen vacancies and hierarchically bicontinuous porous feature endow Co3O4 microrods with enhanced ionic and electronic conductivity, outstanding structural stability and good electrochemical (de)lithiation reversibility. As a result, a high reversible capacity of 1858 mA h g−1 after 300 cycles at 0.5 A g−1 and distinguished high-rate long-term cycling stability with a specific capacity of 502 mA h g−1 after total 1000 cycles at 5 A g−1 are delivered. The magnetic hysteresis loops, zero-field cooled and field-cooled temperature-dependent magnetization curves after different cycles are used to explore the electrochemical reaction reversibility and structural stability of electrode materials. The result highlights the importance of the intrinsic performance regulation of atomic defects, morphology, microstructures and pores structure of anode materials on the improvement of their ionic and electronic conductivity, structural stability and thus electrochemical properties.

Yolk-shelled Sb@C nanoconfined nitrogen/sulfur co-doped 3D porous carbon microspheres for sodium-ion battery anode with ultralong high-rate cycling

Sb materials have considered to be one of the most excellent anode materials for sodium ion batteries (SIBs). Developing a Sb-based materials with high-rate long-term cycling durability is highly requisite for boosting their practical application as SIB anodes. In this work, yolk-shell structured Sb@C nanoconfined nitrogen-sulfur co-doped 3D porous carbon microspheres (Sb@NS-3DPCMSs) were prepared via salt-templating directed spray-drying strategy combined with ingenious and continuous high efficiency one-pot multi-step approach. The formation mechanism of the yolk-shell structure was revealed by first-principles simulations for the first time. In the constructed 3D architecture, the robust yolk-shell structure for confining Sb nanocrystals can provide enough void space for effectively buffering the volume expansion of Sb and thus remarkably stabilize the structural integrity of the overall electrode during rapid long-term cycling, while the interconnected empty carbon box with abundant hierarchical pores and high conductivity can facilitate the fast transport of electrons, sodium ions and electrolyte in the whole electrode. Moreover, nitrogen-sulfur co-doping can enhance the intercalation kinetics of sodium ions, and further increase the capacity. As a consequence, the resulting electrode based on the optimized Sb@NS-3DPCMSs exhibits high specific capacity (~540 mA h g−1 at 100 mA g−1), superior rate capability (334 mA h g−1 at 20 A g−1), excellent high-rate cycling capacity retention even at low temperature of 5 °C, and ultralong high-rate cycling life (331 mA h g−1 after 10000 cycles at 20 A g−1) as SIB anode.

A NaV3(PO4)3@C hierarchical nanofiber in high alignment: exploring a novel high-performance anode for aqueous rechargeable sodium batteries.

The development of aqueous rechargeable sodium batteries (ARSBs) demands high-performance electrode materials, especially anode materials with low operating potential and competent electrochemical properties. The lithium/sodium vanadium phosphate family with good structural stability and abundant vanadium chemistry versatility is a promising series for energy storage applications. Herein, a new member in the sodium vanadium phosphate family, i.e. NaV3(PO4)3, is introduced as a novel anode candidate for ARSBs. For the first time, its sodium intercalation mechanism in an aqueous electrolyte is explored, and moreover, the well-aligned NaV3(PO4)3@porous carbon nanofiber is constructed to fulfil its full potential. Based on the reversible phase transformation and 3D open framework, the NaV3(PO4)3 is demonstrated to be reliable in the aqueous electrolyte. Favored by the well-aligned, highly porous and hierarchical 1D nanoarchitecture, the freestanding aligned NaV3(PO4)3@porous carbon hybrid film achieves fast electron/ion transport capability and good mechanical flexibility, resulting in its superior high-rate properties and excellent cycling durability. Moreover, a full cell is fabricated using the aligned NaV3(PO4)3@C nanofiber as the anode and Na0.44MnO2 as the cathode. The cell is capable of high-rate long-term cycling, which retains 84% of the capacity after five hundred cycles at alternate 20 and 5C. Therefore, this work not only demonstrates a novel high-performance anode material for ARSBs, but also introduces a general applicable and highly efficient architecture of aligned 1D nanofibers for energy storage applications.

One-Step Fabrication of Fe-Si-O/Carbon Nanotube Composite Anode Material with Excellent High-Rate Long-Term Cycling Stability

ABSTRACTThe composite Li-ion battery anode material of Fe2SiO4, Fe3O4, Fe3C (Fe-Si-O) and carbon nanotubes was prepared by a simple one-step reaction between ferrocene and tetraethyl orthosilicate. When cycled at 100 mA g-1, this material exhibited ever-increasing capacities and reached 588 mAh g-1 at the 280th cycle. At 500 mA g-1, a reversible capacity of 350 mAh g-1 was retained for 600 cycles. Compared with Fe3O4 materials, the Fe-Si-O/CNT exhibited superior long-term high-rate performance, which could mainly result from its enhanced stability and conductivities by introducing silicates and CNTs during the one-step synthesis.

Synthesis of strontium hexaferrite nanoplates and the enhancement of their electrochemical performance by Zn2+ doping for high-rate and long-life lithium-ion batteries

Hexagonal structured strontium hexaferrites and their perfect high-rate long-term cycling performances.

One-step fabrication of Fe-Si-O/carbon nanotube composite anode material with excellent high-rate long-term cycling stability

The composite of Fe2SiO4 with carbon nanotubes, Fe3O4 and Fe3C are fabricated by a simple one-step reaction between ferrocene and tetraethyl orthosilicate. The composite utilized as anode material for Li-ion storage exhibits ever-increasing capacities when cycled at a current density of 100 mA g−1, and after 280 cycles, a stable capacity of 588 mAh g−1 is achieved. When cycled at 200, 400, 800 and 1600 mA g−1, the reversible capacities are 364, 323, 281, 235, and 186 mAh g−1, respectively. Even cycled at 500 mA g−1, a reversible capacity of 350 mAh g−1 is retained after 600 cycles. The excellent performance is much superior to that of the carbon-coated Fe3O4 prepared under the similar conditions. The outstanding performance associates significantly with the electronic conductivity of in-situ formed carbon nanotubes with uniform dispersion and Fe3C coated on the Fe2SiO4 nanoparticles, as well as the formation of lithium silicates to act as solid electrolyte for enhancing the ionic conductivity.

From a 3D hollow hexahedron to 2D hierarchical nanosheets: controllable synthesis of biochemistry-enabled Na7V3(P2O7)4/C composites for high-potential and long-life sodium ion batteries.

Tailoring materials into different structures offers unprecedented opportunities in the realization of their functional properties. Particularly, controllable design of diverse structured electrode materials is regarded as a crucial step towards fabricating high-performance batteries. Herein, a general biochemistry-directed strategy has been developed to fabricate functional materials with controllable architectures and superior performance. The natural structure of fern (i.e. Cibotium) spores realizes the formation of a three-dimensional hexahedral bio-precursor. Either its core or shell is targeted to be destroyed, resulting in different architectures, from a 3D hollow hexahedron to a 2D hierarchical nanosheet, of the final product. As a case study, sodium vanadium pyrophosphate (i.e. Na7V3(P2O7)4) is employed as the electrochemically active material in this study. The crucial role of controllable damage in the construction of diverse architectures is discussed. Moreover, the relationship between different outside architectures, internal microstructures and the sodium intercalation capabilities of the bio-composites is clarified. Among all the samples, the 2D nanosheet with hierarchical structures has the smallest particle size and the highest surface area, which are favourable for its fast sodium intercalation. As a result, it is capable of high-rate long-term cycling, which achieves a high cycling efficiency of 93% after 500 cycles at 20C. However, a 3D hollow hexahedron has a thick shell and inferior surface characteristics, which greatly limits its sodium transport kinetics and leads to inferior performance. Therefore, the present work not only highlights a general, green and energy-efficient biochemistry-enabled strategy to prepare high-performance electrode materials, but also provides clues to controllably design diverse architectures for functional materials.