Membrane-less MoO_(3-x)@TiO_(2)-bromine battery with excellent rate capability and cyclic stability

Bromine has attracted significant attention as a cathode material for aqueous batteries due to its high reduction potential of 1.05 V(Br_(3)^(-)+2e~-■3Br~-),impressive theoretical specific capacity of 223 mA h g^(-1),and rapid reaction kinetics in the electrolyte.However,searching for compatible anode materials to match with bromine has posed a challenge due to its highly corrosive nature.In this study,we developed oxygen-deficient MoO_(3) with TiO_(2) coating(referred to as MoO_(3-x)@TiO_(2))as an anode material to pair with a bromine cathode in static full batteries.The oxygen deficiency contributes to enhanced electronic and protonic diffusion within the MoO_(3-x)lattice,while the TiO_(2) coating mitigates structural dissolution and proton trapping during cycling.The MoO_(3-x)@TiO_(2) demonstrates fast charge storage kinetics and excellent resistance to bromine corrosion.The impressive compatibility between MoO_(3-x)@TiO_(2) and bromine enables the construction of membrane-less full batteries with exceptional rate capability and cyclic stability.The MoO_(3-x)@TiO_(2)-bromine battery achieves an energy density of70.8 W h kg^(-1)at a power density of 328.1 W kg^(-1),showcasing an impressive long-term cyclic life of 20,000 cycles.Our study provides valuable insights for the development of high-performance aqueous secondary batteries.

Bi/Bi_(3)Se_(4) nanoparticles embedded in hollow porous carbon nanorod:High rate capability material for potassium-ion batteries

Considering their superior theoretical capacity and low voltage plateau,bismuth(Bi)-based materials are being widely explored for application in potassium-ion batteries(PIBs).Unfortunately,pure Bi and Bibased compounds suffer from severe electrochemical polarization,agglomeration,and dramatic volume fluctuations.To develop an advanced bismuth-based anode material with high reactivity and durability,in this work,the pyrolysis of Bi-based metal-organic frameworks and in-situ selenization techniques have been successfully used to produce a Bi-based composite with high capacity and unique structure,in which Bi/Bi_(3)Se_(4)nanoparticles are encapsulated in carbon nanorods(Bi/Bi_(3)Se_(4)@CNR).Applied as the anode material of PIBs,the Bi/Bi_(3)Se_(4)@CNR displays fast potassium storage capability with 307.5 m A h g^(-1)at 20 A g^(-1)and durable cycle performance of 2000 cycles at 5 A g^(-1).Notably,the Bi/Bi_(3)Se_(4)@CNR also showed long cycle stability over 1600 cycles when working in a full cell system with potassium vanadate as the cathode material,which further demonstrates its promising potential in the field of PIBs.Additionally,the dual potassium storage mechanism of the Bi/Bi_(3)Se_(4)@CNR based on conversion and alloying reaction has also been revealed by in-situ X-ray diffraction.

Fluorine-substituted O3-type NaNi_(0.4)Mn_(0.25)Ti_(0.3)Co_(0.05)O_(2-x)F_(x) cathode with improved rate capability and cyclic stability for sodium-ion storage at high voltage

O3-type Na NiO_(2)-based cathode materials undergo irreversible phase transition and serious capacity decay at high voltage above 4.0 V in sodium-ion batteries. To address these challenges, effects of Fsubstitution on the structure and electrochemical performance of Na Ni_(0.4)Mn_(0.25)Ti_(0.3)Co_(0.05)O_(2) are investigated in this article. The F-substitution leads to expanding of interlayer, which can enhance the mobility of Na+. NaNi_(0.4)Mn_(0.25)Ti_(0.3)Co_(0.05)O_(1.92)F_(0.08)(NMTC-F_(0.08)) with the optimal F-substitution degree exhibits much improved rate capability and cyclic stability. It delivers reversible capacities of 177 and 97 m Ah g^(-1) at 0.05 and 5 C within 2.0–4.4 V, respectively. Galvanostatic intermittent titration technique verifies faster kinetics of Na+diffusion in NMTC-F_(0.08). And in-situ XRD investigation reveals the phase evolution of NMTC-F_(0.08), indicating enhanced structural stability results from F-substitution. This study may shed light on the development of high performance cathode materials for sodium-ion storage at high voltage.

Dual-Carbon-Confined SnS Nanostructure with High Capacity and Long Cycle Life for Lithium-ion Batteries

SnS with high theoretical capacity is a promising anode material for lithiumion batteries.However,dramatic volume changes of SnS during repeated discharge/charge cycles result in fractures or even pulverization of electrode,leading to rapid capacity degradation.To solve this problem,we construct a dual-carbon-confined SnS nanostructure(denoted as SnS@C/rGO)by depositing semi-graphitized carbon layers on reduced graphene oxide(rGO)supported SnS nanoplates during high-temperature reduction.The dual carbon of rGO and in situ formed carbon coating confines growth of SnS during the high-temperature calcination.Moreover,during the reversible Li+storage the dual-carbon modification enables good electronic conductivity,relieves the volume effect,and provides double insurance for the electrical contact of SnS even after repeated cycles.Benefiting from the dual-carbon confinement,SnS@C/rGO exhibits significantly enhanced rate capability and cycling stability compared with the bare and single carbon modified SnS.SnS@C/rGO presents reversible capacity of 1029.8 mAh g^(-1)at 0.2 A g^(-1).Even at a high current density of 1 A g^(-1),it initially delivers reversible capacity of 934.0 mAh g^(-1)and retains 98.2%of the capacity(918.0 mAh g^(-1))after 330 cycles.This work demonstrates potential application of dual-carbon modification in the development of electrode materials for high-performance lithium-ion batteries.

Microsized SnS/Few-Layer Graphene Composite with Interconnected Nanosized Building Blocks for Superior Volumetric Lithium and Sodium Storage

To develop anode materials with superior volumetric storage is crucial for practical application of lithium/sodium-ion batteries.Here,we have developed a micro/nanostructured Sn S/few-layer graphene(Sn S/FLG)composite by facile scalable plasma milling.Inside the hybrid,SnS nanoparticles are tightly supported by FLG,forming nanosized primary particles as building blocks and assembling to microsized secondary granules.With this unique micro/nanostructure,the Sn S/FLG composite possesses a high tap density of 1.98 g cm^(-3)and thus ensures a high volumetric storage.The combination of Sn S nanoparticles and FLG nanosheets can not only enhance the overall electrical conductivity and facilitate the ion diffusion greatly,but alleviate the large volume expansion of Sn S effectively and maintain the electrode integrity during cycling.Thus,the densely compacted Sn S/FLG composite exhibits superior volumetric lithium and sodium storage,including high volumetric capacities of 1926.5/1051.4 m Ah cm^(-3)at 0.2 A g^(-1),and high retained capacities of 1754.3/760.3 m Ah cm^(-3)after 500cycles at 1.0 A g^(-1).With superior volumetric storage performance and facile scalable synthesis,the Sn S/FLG composite can be a promising anode for practical batteries application.

Recent advances of two-dimensional CoFe layered-double-hydroxides for electrocatalytic water oxidation

Oxygen evolution reaction(OER)is pivotal to drive green hydrogen generation from water electrolysis,but yet is strictly overshadowed by the sluggish reaction kinetics.Earth-abundant and cut-price transitionmetal compounds,particularly Co Fe layered-double-hydroxides(LDHs),show the distinct superiorities in contrast to noble metals and their derivatives.In this review,we firstly underline their fundamental issues in electrocatalytic water oxidation,including Co Fe LDHs crystal structure,the surface of(hydr)oxides confined to OER and the controversial roles of Fe species,aiming at understanding the structure-related activity and catalytic mechanism.Advanced approaches for optimizing OER activity of Co Fe LDHs are then comprehensively overviewed,which will shed light on the different working mechanisms and provide a concise analysis of their unique advantages.Finally,a perspective on the future development of Co Fe LDHs electrocatalysts is offered.We hope this review can give a concise and explicit guidance for the development of transition-metal-based electrocatalysts in the energy field.

Phase Engineering of CoMo0_(4)Anode Materials toward Improved Cycle Life for Li^(+)Storage

Anode materials based on conversion reactions usually possess high energy densities for lithium-ion batteries(LIBs).However,they suffer from poor rate performance and cycle life due to serious volume changes.Herein,α/β-CoMo04 heterogeneous nanorods are synthesized via a facile co-precipitation method,and further are phase-engineered through varying calcination temperature,accomplishing the obviously improved cycle life and rate performance as anodes for LIBs.When evaluated at a current density of 1.0 A·g^(-1)the optimal nanorods with anα/βphase ratio of 6.0 afford the reversible capacity of 1143.6 mAh·g^(-1)after 200 cycles,outperforming most of recently reported bimetal oxides.Li^(+)storage mechanism is further analyzed by using in-situ X-ray diffraction and ex-situ transition electronic microscopy.It's revealed thatβ-CoMoO_(4)follows a one-step conversion reaction;whileα-CoMo0_(4)proceeds an intercalation pathway before the conversion reaction.Grading storage of Li^(+)would alleviate the volume effect of heterostructuredα/β-CoMo0_(4),forming electronically conductive network evenly composed of Co and Mo nanograins to enable the reversible electrochemical conversion.This work is anticipated to give some hints for the rational design of high-performance energy materials.

Construction of SnS-Mo-graphene nanosheets composite for highly reversible and stable lithium/sodium storage

Sn-based chalcogenides are considered as one of the most promising anode materials for lithium-ion batteries(LIBs)because of their high capacities through both conversion and alloying reactions.However,the realization of full capacities of Sn-based chalcogenides is mainly hindered by the large volume variation and inferior reversibility of conversion reaction during cycling.In present work,a new ternary Sn SMo-graphene nanosheets(Sn S-Mo-GNs)composite is fabricated by a simple and scalable plasma milling method,in which Sn S nanoparticles are tightly bonded with Mo and GNs.The Mo and GNs additives can effectively alleviate the large volume change of Sn S upon cycling,which leads to a stable electrochemical framework.Moreover,they can significantly suppress the Sn agglomeration in lithiated Sn S,which enables highly reversible conversion reaction during cycling.As anode for LIBs,the Sn S-Mo-GNs composite exhibits a high initial coulombic efficiency of 86.9%(almost complete reversibility of Sn S,~97.3%),high cyclic coulombic efficiency after initial three cycles(>99.5%),and long lifespan(up to 600 cycles).Moreover,it also demonstrates superior electrochemical performance for sodium storage.Thus,this work demonstrates a potential anode for batteries application and provides a viable strategy to obtain highly reversible and stable anodes for lithium/sodium storage.