Ultra-long Cycling Performance Research Articles

Defective Bi2S3 Anchored on CuS/C as an Ultrafast and Long-Life Anode for Sodium-Ion Storage.

Due to the high electrical conductivity and abundant redox active sites, bimetal sulfides are highly competitive anode materials for sodium storage with long-life and high-rate. Herein, a heterostructured metal sulfide (Bi2S3-CuS) with a carbon-based support is prepared by calcination and ion exchange methods. The synergistic effects of the heterostructure and defective structure provide facile diffusion channels, fast Na+ migration, and plentiful active sites for Na+, which reflect in the impressive electrochemical performance with a high reversible capacity of 592.2 mA h g-1 after 1000 cycles at 8 A g-1. Furthermore, the Na-ion full batteries exhibit an ultra-long cycling performance with a value of 216 mA h g-1 after 4000 cycles at 10 A g-1. Interestingly, the defective structure of Bi2S3 remains after cycling. Kinetic analyses and density functional theoretical calculations clarified that the heterointerfacial structure, especially on the interface containing sulfur defects in Bi2S3 of Bi2S3-CuS, could induce feasible ion adsorption and promote ion transfer, which lays the foundation for achieving ultrafast sodiation kinetics.

Thiol-ene crosslinked cellulose-based gel polymer electrolyte with good structural integrity for high cycling performance lithium-metal battery

Gel polymer electrolytes (GPEs) are considered to be one most promising alternative to liquid electrolytes due to their suitability for creating safe and durable solid-state lithium-metal batteries. However, the mechanical properties of GPEs usually deteriorate dramatically when polymer matrices are plasticized by a liquid electrolyte, which leads to significant loss of battery performance. Therefore, the long-term structural integrity and good mechanical strength are critical characteristics of GPEs designed for high-performance batteries. Here, an ecologically compatible cellulose-based GPE with a crosslinked structure is synthesized via a facile and effective thiol-ene click chemistry method. The prepared thiol-ene crosslinked GPE possesses enhanced mechanical strength (10.95 MPa) and rigid structure, which enabled us to fabricate LiFePO4|Li batteries with ultra-long cycling performance. The capacity retention of the crosslinked cellulose-based GPE can be up to 84% at 0.5 C, even after 350 cycles, which is considerably higher than that of non-crosslinked GPE for which rapid decline in capacity occurs after 200 cycles. In addition, a GPE preparation method described in this work compares favorably well with existing commercial electrolytes for lithium metal batteries.

Self-assembled MoTe2 hierarchical nanoflowers with carbon coating as anode material for excellent sodium storage performance

Developing a suitable anode material for rapid sodium ion transfer and storage is a common challenge for application of sodium ion batteries (SIBs). As a typical two-dimensional (2D) layered material, some potential advantages can be discovered from MoTe2 such as unique structural feature, abundant active sites and rapid Na+ intercalation/de-intercalation. However, the stacking of layers, collapse of structure and large volume expansion still affect the Na+ storage performance of MoTe2 anode material. In this work, we report a nanoflower like MoTe2/C as an excellent anode material for SIBs, which is synthesized via a simple method containing chelation, preoxidation and tellurization from Mo-PDA, MoOx/C to MoTe2/C. Through controlling the reasonable tellurization temperatures and suitable mass proportion between Mo raw material and dopamine hydrochloride, the best performance of MoTe2/C-600 can be obtained, which shows a higher initial capacity of 580 mAh/g and 250 mAh/g after 100 cycles at 0.1A/g compared with other tested samples. Besides, MoTe2/C-600 delivers an ultra-long time cycling performance of 3000 cycles and the capacity still retains 190 mAh/g at 1.0 A/g. After assembled with Na3V2(PO4)3 (NVP), a full-cell retains 109 mAh/g after 50 cycles at 0.1A/g. The 3D connected network between petals of flower like MoTe2/C can effectively suppress the volume expansion or pulverization to the boost the Na+ storage performance. This work offers new clues to construct MoTe2-based composites with unique and robust nanostructures for electrochemical energy-storage application.

Ultrafast sodium-ion storage in an interconnected Ni/Ni3S2 nanocomposite with long-term cycling performance

Nickel sulfide (Ni3S2) is a potential anode candidate for sodium-ion batteries due to its abundance, stable structure, and low price. However, its rate and cycling performance require improvement for practical applications. This paper reports the facile synthesis of a unique composite consisting of an interconnected nickel/nickel sulfide nanocomposite (Ni/Ni3S2) by heating a mixture of nickel nanopowder and sulfur. The interconnected nanostructured backbone of the nickel nanoparticles facilitates continuous electron pathways in the composite, while the embedded nanosized nickel sulfide domain reduces the diffusion length and improves reaction kinetics. The Ni/Ni3S2 electrode exhibits excellent rate performance in dimethyl ether (DME) electrolyte, with a current density of 80 A g−1 and capacity of 151 mA h g−1; it also exhibits stable, ultralong cycling performance. Synergism between the unique nanostructure of the composite and the low-viscosity DME electrolyte may be responsible for the extraordinary cycling and rate performance. A full cell with a Na3V2(PO4)3 (NVP) electrode delivers a capacity of 111 mA h g−1 at 100 A g−1; moreover, the Ni/Ni3S2–NVP full cell retains 55% of its capacity after 5000 cycles at 20 A g−1. The developed strategy, which uses a conductive metal-nanoparticle/metal-sulfide nanocomposite, is applicable to other systems and is scalable for practical applications.

Bimetallic sulfides SnS/FeS particles anchored on tremella-like carbon as advanced anode material for sodium ion storage

Sodium-ion batteries (SIBs) are considered as the most promising alternatives to lithium-ion batteries (LIBs). The design of electrode materials is crucial to the improvement of the electrochemical performance of SIBs. In this work, the multicomponent sulfides SnS@FeS particles anchored on tremella-like carbon (SnS@FeS/C) are rationally engineered and constructed. The bimetallic sulfides SnS@FeS particles can provide abundant redox active sites and distinguished electronic structures. Simultaneously, the three-dimensional interconnected carbon with tremella-like structure mitigates the volume expansion and enhances the conductivity. Benefiting from the compositional and structural advantages, the SnS@FeS/C composite achieves high reversible capacity (410.1 mAh g−1 at 100 mA g−1) and excellent rate capability (300.7 mAh g−1 at 3000 mA g−1) in SIBs. Notably, it also exhibits ultralong cycling performance (360 mAh g−1 after 1000 cycles). Additionally, the kinetic analyses of redox reaction reveal that the pseudo-capacitance behavior dominates the charge/discharge process of SnS@FeS/C electrode. This work provides a strategy for preparation of multicomponent metal sulfides with three-dimensional carbon network for excellent electrochemical performance, paving the way for the potential applications in energy storage fields.

Facile construction of N-doped porous carbon nanosheets derived from melamine cyanurate/xylitol for advanced sodium-ion batteries

Herein, the attractive N-doped porous carbon nanosheets (NPCs-4, mass ratio = 4/1) were synthesized by a simple one-step carbonization approach using the mixtures of melamine cyanurate and xylitol (mass ratio = 4/1), which formed the interconnected carbon framework with abundant pore structure. The NPCs-4 electrode displayed a large specific surface area of 703.2 m2/g with hierarchical pore sizes (2–4 nm) and expanded interlayer spacing of ~0.39 nm. The abundant pore structure and N-doping of the NPCs-4 facilitated high Na-ion storage capacity, fast transfer kinetics and stable cycling. As a result of these improvements, the as-prepared NPCs-4 electrode delivered an advanced rate performance (191.1 mA h/g at 20 A/g), and an outstanding ultra-long cycling performance with a specific capacity of 171 mA h/g at 10 A/g after 10,000 cycles (0.0017% loss per cycle), which was the one of the optimal long-cycle properties at high current density reported for carbon-based anode for SIBs to date. Moreover, the kinetic analysis revealed a capacitance-dominated sodium storage mechanism in the NPCs-4 electrode, and possessed a superior Na+ ion diffusion coefficient (1.92 ∗ 10−12 cm2/s), on account of synergistic interaction of rational nanopore structure and appropriate N-doping in NPCs-4. This work provided a facial route to synthesize controlled N-doping porous carbon nanosheets with enlarged interplanar spacing and high specific area, meeting the various requirements unitized as anodes in rechargeable Na+ ions batteries.

Constructing 1D/2D interwoven carbonous matrix to enable high-efficiency sulfur immobilization in Li-S battery

The lithium-sulfur battery is currently considered to be a promising candidate for next-generation energy storage devices. However, its commercial application is severely restricted by rapid capacity decay mainly arising from unavoidable dissolution of intermediate lithium polysulfide of the S-based cathodes. Herein, multifunctional stripped grapheme-carbon nanotubes (SG-CNT) with 1D/2D interwoven and hierarchical pore structure as a promising host to stabilize S was constructed by cheaper raw materials and a facile strategy. Based on comprehensive analysis, the interwoven network and hierarchical pores along with abundant oxidative functional groups in matrix provided large contact area with S, short transport pathway for electrons/Li-ions, sufficient space to accommodate volumetric change, and superior confinement ability for S/polysulfides, thus resulting in effectively stabilizing the S cathode with high S loading and increasing its utilization. Therefore, the S@SG-CNT cathodes exhibited a high reversible capacity of 1227 mAh g-1 at 0.1 A g-1, excellent cyclability with a capacity of 773 mAh g-1 after 500 cycles at 0.2 A g-1, and ultra-long cycling performance with capacity decay less than 0.01% per cycle at 2 A g-1. This facile strategy and unique construction of superior performance cathode provide a new avenue for next commercial application.

Enhanced ionic conductivity of a Na3Zr2Si2PO12 solid electrolyte with Na2SiO3 obtained by liquid phase sintering for solid-state Na+ batteries.

NASICON-type Na3Zr2Si2PO12 (NZSP) is supposed to be one of the best potential solid electrolytes with the characteristics of high ionic conductivity and safety for use in solid-state sodium batteries. Many methods have been used to enhance the ionic conductivity of NZSP, among which liquid phase sintering is a simple and rapid method. However, the transport mechanism of sodium ions in a NZSP electrolyte obtained by liquid phase sintering is not clear, and its application in solid-state batteries has not been confirmed. In this study, we synthesized NZSP with Na2SiO3 additives by liquid phase sintering to reduce the sintering temperature and improve the ionic conductivity. NZSP with 5 wt% Na2SiO3 (NZSP-NSO-5) achieves the highest ionic conductivity of 1.28 mS cm-1 and the lowest activation energy of 0.21 eV. Furthermore, the DFT study proves the Na+ diffusion mechanism and the decline in activation energy after addition. Lastly, the Na/Na3V2(PO4)3 battery with a Na2SiO3-added NZSP solid electrolyte exhibits a remarkably extended cycling capacity of 96.6% capacity retention after being cycled at 0.1 C 100 times. The liquid phase sintering with addition of low melting point salt compounds to electrolyte powder represents a rapid and straightforward technique for improving other ceramic electrolytes.

Template-directed synthesis of Co2P/MoSe2 in a N-doped carbon hollow structure for efficient and stable sodium/potassium ion storage

Multi-component hollow structures with attractive physicochemical properties, often show superior electrochemical performance in alkali-ion batteries. Herein, a template-directed strategy is proposed for synthesis of multi-component hollow nanosphere with Co2P/MoSe2 confined in N-doped carbon (Co2P/MoSe2@NC). This structure markedly improves the kinetics, provides sufficient active sites and accommodates volume expansion, for the large-sized K+/Na+ storage, which is proved by the in-situ and ex-situ transmission electron microscopy measurements. As for sodium storage, a capacity of 230 mAh g−1 over 1500 cycles can be retained at current of 2.0 A g−1, with a capacity retention of 83%. In terms of K+ storage, Co2P/MoSe2@NC anodes display excellent rate capability and ultra-long cycling performance (177.6 mAh g−1 at 1.0 A g−1 for 5000 cycles with a capacity retention of 75%). Based on the analysis of electrode process by comparison of dQ/dV curves and theoretical calculations, the intercalation-conversion reaction for K+ storage is more reversible and the weaker adsorption of K+ on the Co2P/MoSe2 interface can guarantee the stable storage of the K+-ions. High energy density of 43.34 Wh kg−1 at power densities of 22263.7 W kg−1 is delivered in the Co2P/MoSe2@NC//AC potassium-ion hybrid supercapacitor. This indicates that a selenide/phosphide combination can exert useful synergistic effects on the large-sized K+/Na+ storage, and is a promising anode candidate.

Nitrogen and fluorine co-doped TiO2/carbon microspheres for advanced anodes in sodium-ion batteries: High volumetric capacity, superior power density and large areal capacity

Fast charging and high volumetric capacity are two of the critical demands for sodium-ion batteries (SIBs). Although nanostructured materials achieve outstanding rate performance, they suffer from low tap density and small volumetric capacity. Therefore, how to realize large volumetric capacity and high tap density simultaneously is very challenging. Here, N/F co-doped TiO2/carbon microspheres (NF-TiO2/C) are synthesized to achieve both of them. Theoretical calculations reveal that N and F co-doping increases the contents of oxygen vacancies and narrows the bandgaps of TiO2 and C, improving the electronic conductivity of NF-TiO2/C. Furthermore, NF-TiO2/C exhibits the high binding energy and low diffusion energy barrier of Na+, significantly facilitating Na+ storage and Na+ diffusion. Therefore, NF-TiO2/C offers a high tap density (1.51 g cm−3), an outstanding rate performance (∼125.9 mAh g−1 at 100 C), a large volumetric capacity (∼190 mAh cm−3 at 100 C), a high areal capacity (∼4.8 mAh cm−2) and an ultra-long cycling performance (∼80.2% after 10,000 cycles at 10 C) simultaneously. In addition, NF-TiO2/C||Na3V2(PO4)3 full cells achieve an ultrahigh power density of 25.2 kW kg−1. These results indicate the great promise of NF-TiO2/C as a high-volumetric-capacity and high-power-density anode material of SIBs.

Rational Design of β-NiOOH Nanosheet-Sheathed CNTs as a Highly Efficient Electrocatalyst for Practical Li-S Batteries.

The shuttle effects of polysulfide intermediates (LiPSs) and sluggish kinetics during sulfur reduction reaction (SRR) process severely exacerbate the electrochemical performances of Li-S batteries. Herein, a unique nanocatalyst comprising β-NiOOH nanosheets uniformly implanted on the surface of carbon nanotubes (CNT@NiOOH) was designed and synthesized for sulfur cathodes. The β-NiOOH nanosheets have great capability of adsorbing LiPSs as well as superior catalytic activity for accelerating LiPS conversion, providing a more efficient method to restrain shuttle effects and improve the kinetics of SRR. Moreover, the nanometer-scale epitaxial growth and uniform distribution of β-NiOOH on CNTs provide a multidimensional catalytic skeleton with sufficient accessible active surfaces, unimpeded LiPS diffusion pathways, and resultant high utilization of active sites. Simultaneously, stable electron transportation pathways are also obtained by being synthesized on CNTs to avoid the faultiness of poor electron conductivity of β-NiOOH. These conspicuous advantages contribute to fully exert the catalytic and LiPS anchoring potential of CNT@NiOOH, bringing about the ultralong cycle performance and excellent capacity reversibility at a high discharge rate. Reticular CNT@NiOOH frameworks are assembled with the sulfur composite materials (SCMs) by a self-assembly method, and a super-high capacity of 813.3 mA h g-1 after 400 cycles at 0.5 C with a small capacity degradation of 0.07% per cycle is achieved. Furthermore, the 3 A h pouch-type cell with the SCM/CNT@NiOOH cathode attains a super-high energy density of about 320 W h kg-1 and shows a superior capacity retention as high as 75.9% after 50 cycles at 0.2 C. This work provides a promising method to accelerate the SRR process and restrain the shuttle effects for practical long-life and high-capacity Li-sulfur batteries.

Ti3C2 MXene with pillared structure for hybrid magnesium-lithium batteries cathode material with long cycle life and high rate capability

Cationic surfactants (CS) pillared Ti3C2 composites (Ti3C2/CS) were prepared by a facile electrostatic assembly method, which have large interlayer spacing and slight N-doping. In hybrid magnesium-lithium batteries (HMLBs), the Ti3C2/CS composites exhibit excellent performance by utilizing both Li+ and Mg2+ as charge carriers. Among these composites, the Ti3C2/CTAB (CTC) electrode displays a reversible capacity of 115.9 and 60 mAh g−1 in APC/LiCl (APCL) and APC electrolytes at 0.1 A g−1, and it also exhibits excellent high rate performance and ultralong cycle performance. It is verified that CS is vital to significantly improve the diffusion kinetics of Mg2+ on the electrode surface. The CS can act as the conductive “bridge” which connects different Ti3C2 layers and the interlayer pillar which expands the interlayer distance. In addition, the N element in CS is effective in neutralizing electronegativity and enhancing electrical conductivity for the CTC electrode. The electrode design strategy can adapt to the synthesis of cathode materials with high rate capability in HMLBs.

Pre-potassiated hydrated vanadium oxide as cathode for quasi-solid-state zinc-ion battery

Zinc-ion batteries (ZIBs), in particular quasi-solid-state ZIBs, occupy a crucial position in the field of energy storage devices owing to the superiorities of abundant zinc reserve, low cost, high safety and high theoretical capacity of zinc anode. However, as divalent Zn2+ ions experience strong electrostatic interactions when intercalating into the cathode materials, which poses challenges to the structural stability and higher demand in Zn2+ ions diffusion kinetics of the cathode materials. Here, a microwave-assisted hydrothermal method is adopted to prepare pre-potassiated hydrated vanadium pentoxide (K0.52V2O5·0.29H2O, abbreviated as KHVO) cathode material, in which the potassium ions pre-inserted into the interlayers can act as “pillars” to stabilize the lamellar structure, and crystal water can act as “lubricant” to improve the diffusion efficiency of Zn2+ ions. Consequently, the KHVO displays high electrochemical properties with high capacity (∼ 300 mAh/g), superior rate capability (69 mAh/g at 5 A/g) and ultralong cycling performance (>1500 cycles at 2 A/g) in quasi-solid-state ZIBs. These superior Zn storage properties result from the large diffusion coefficient and highly stable and reversible Zn2+ (de)intercalation reaction of KHVO.

Harnessing the Volume Expansion of MoS3 Anode by Structure Engineering to Achieve High Performance Beyond Lithium-Based Rechargeable Batteries.

Beyond-lithium-ion storage devices are promising alternatives to lithium-ion storage devices for low-cost and large-scale applications. Nowadays, the most of high-capacity electrodes are crystal materials. However, these crystal materials with intrinsic anisotropy feature generally suffer from lattice strain and structure pulverization during the electrochemical process. Herein, a 2D heterostructure of amorphous molybdenum sulfide (MoS3 ) on reduced graphene surface (denoted as MoS3 -on-rGO), which exhibits low strain and fast reaction kinetics for beyond-lithium-ions (Na+ , K+ , Zn2+ ) storage is demonstrated. Benefiting from the low volume expansion and small sodiation strain of the MoS3 -on-rGO, it displays ultralong cycling performance of 40 000cycles at 10A g-1 for sodium-ion batteries. Furthermore, the as-constructed 2D heterostructure also delivers superior electrochemical performance when used in Na+ full batteries, solid-state sodium batteries, K+ batteries, Zn2+ batteries and hybrid supercapacitors, demonstrating its excellent application prospect.

Enhanced bifunctional catalytic activities of N-doped graphene by Ni in a 3D trimodal nanoporous nanotubular network and its ultralong cycling performance in Zn-air batteries

Free-standing and flexible air electrodes with long-lasting bifunctional activities for both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) are crucial to the development of wearable Zn-air rechargeable batteries. In this work, we synthesize a flexible air electrode consisting of 3D nanoporous N-doped graphene with trimodal shells and Ni particles through repeated chemical vapor deposition (CVD) and acidic etching processes. Our results indicate that such trimodal graphene morphology significantly enhances the active N-dopant sites and graphene-coated Ni surface, which consequentially boosts both the ORR and OER activities, as well as catalytic durability. First-principles density functional theory (DFT) calculations reveal the synergetic effects between the Ni and the N-doped graphene; namely, the Ni nanoparticles boost the bifunctional activities of the coated N-doped graphene, and in turn the graphene-covering layers enhance the stability of Ni. Thanks to the better protection from the triple graphene shells, our trimodal N-doped graphene/Ni-based Zn-air battery can be stably discharged/recharged beyond 2500 h with low overpotentials. It is reasonable to expect that such free-standing trimodal graphene/Ni would be promising in many flexible energy conversion/storage devices.

High performance of LiFePO4 with nitrogen and phosphorus dual-doped carbon layer for lithium-ion batteries

In recent years, LiFePO4 is considered to be a promising cathode material for lithium-ion batteries (LIBs) and has attracted increasing attention due to its good thermal stability, safety and environmental friendliness compared with layered cathode materials (such as Li[NixCoyMnz]O2). However, the low electrical conductivity and slow lithium-ion diffusion hampers the use of LFP in applications. Herein, we report a creative and facile method for fabricating nitrogen and phosphorus dual-doped carbon-coated LiFePO4 (LFP@NPC) via the pyrolysis of egg yolk. Egg yolk is a widely available and low-cost raw material and is used in this work as both the carbon precursors and the dopant source. LFP@NPC materials produced by one-step pyrolysis of egg yolk were systematically studied by various characterization techniques. The obtained results show that LFP@NPC has smaller uniform particle sizes, better grain-to-grain electrical contact, and faster diffusion of both electrons and lithium ions. As expected, the LFP coating with 1 mL egg yolk exhibits a high discharge capacity of 150.2mAhg−1 at 1 C and ultralong cycle performance with only 0.016% capacity fading rate per cycle in 300 cycles at 2 C. Therefore, we suggest that the LFP@NPC composite is a promising cathode material with high performance for LIBs.

Enabling the fast lithium storage of large-scalable γ-Fe2O3/Carbon nanoarchitecture anode material with an ultralong cycle life

Two-dimensional (2D) materials are generally expected to have superior lithium-ion (LIBs) performances compare with their bulk counterpart as they display superior specific surface area. In this context, the development of 2D maghemite would be of great interest owing to its high theoretical specific capacity, natural abundance, and relatively low cost and toxicity; however, maghemite do not have a layered crystalline structure. Herein, to overcome this hindrance, γ-Fe2O3 has been enclosed within a 2D carbon matrix via a simple and facile synthesis strategy based on the complexation of ethylene glycol with aqueous iron species by hydrolysis and condensation reactions followed by its carbonization. As obtained 2D carbon γ-Fe2O3 nanosheet composite (CEG-Fe) is composed of 41.3 wt.% carbon and 10.2 wt.% Fe. When used as anode materials in LIBs, CEG-Fe demonstrated the enhanced initial discharge capacity of 1589 mAh g−1 at 100 mA g−1, and outstanding ultralong cycling performance with the significant stable capacity of 700 mAh g−1 and 230 mAh g−1 at the higher current rate of 0.5 A g−1 and 10 A g−1 for more than 300 and 6000 cycles, respectively. These results enable a promising avenue to design the large-scale production of 2D CEG-Fe sheets-based nanostructured anode materials for next-generation LIBs for large‐scale energy storage applications.

V3Se4 embedded within N/P co-doped carbon fibers for sodium/potassium ion batteries

The development of electrode materials with high reversible capacity, superior rate capability, and long lifespan for sodium-ion and potassium-ion batteries (SIBs/PIBs) is gaining great attention. Herein, V3Se4 nanoparticles embedded in nitrogen/phosphorus co-doped carbon nanofibers (V3Se4/NPCNFs) were initially synthesized with the assistance of biomass algae (Chlorella pyrenoidosa) and employed as anodes in SIBs and PIBs for the first time. The experimental findings and DFT calculation results reveal that heteroatom N/P co-doping could increase the content of pyridinic N with more open edge sites and boost the Na+/K+ storage performance by optimizing the distribution of electron density and enhancing ion reaction kinetics. As a result, the V3Se4/NPCNFs electrode exhibits an admirable capacity (527 mAh g−1/0.1 A g−1/60 cycles) and ultralong cycle performance (340 mAh g−1/5 A g−1/8000 cycles and 240 mAh g−1/10 A g−1/13000 cycles) for SIBs as well as an excellent electrochemical performance for PIBs (450 mAh g−1/100 cycles at 50 mA g−1 and 207 mAh g−1/800 cycles at 2 A g−1). The SIB full cell obtained by pairing with a Na3V2(PO4)3 cathode also reveals outstanding cycling performance. Thus, this work helps explain how biomass algae is a sustainable and economical source of heteroatoms and reactor in constructing energy storage materials.

Agaric-like anodes of porous carbon decorated with MoO2 nanoparticles for stable ultralong cycling lifespan and high-rate lithium/sodium storage

The agaric-like anodes of porous carbon decorated with MoO2 nanoparticles (MoO2/C) for reversible Li/Na storage were synthesized via a green and facile bio-inspired route. The uniformly distributed MoO2 nanoparticles, the porous agaric-like carbon matrix and high degree graphitization of carbon materials, effectively mitigated the huge volume changes during cycling and improved the reversible capacity, resulting in the outstanding electrochemical behaviors with excellent rate capability, high capacity and excellent stable long cycling lifespan as anodes for lithium and sodium storage. Especially, the MoO2/C electrodes showed ultralong cycling performance under high current density of 5.0 A g−1, presenting a reversible capacity of 363.2 mAh g−1 after a prolonged 2000-cycles as anodes for Li storage. Meanwhile, the MoO2/C electrodes displayed a super-long cycling lifespan of 3000 cycles with the reversible discharge capacity of 193.5 mAh g−1 at the current density of 5.0 A g−1 for Na storage. Furthermore, the kinetic analysis of MoO2/C-4 electrodes as anodes for Li/Na storage was carried out to further investigate the electrochemical behavior. The ultralong cycling performance under high-density could satisfy the demands of next-generation anode electrodes for Li/Na ion batteries, promoting the commercialization process of MoO2-based materials.

The Mechanism of Aluminum Vanadate in Aqueous Zinc Ion Batteries with Ultra-Long Cycle Life

There are few cathode materials suitable for aqueous zinc ion batteries with high capacity and long cycle stability. Herein, H11Al2V6O23.2 (defined as HAVO) microspheres are synthesized by hydrothermal method as cathode material, which exhibits a maximum discharge capacity of 236 mA g−1 at 100 mA g−1. Significantly, ultra-long cycle performance of 100 mA g−1 with an extraordinary capacity retention of 90% is achieved after 5000 cycles at 8 A g−1. The research finds that the excellent performance is attributed to the extraordinary layer spacing of 13.37 Å and reveals the zinc storage mechanism of the HAVO electrode.