Precise construction of RuPt dual single-atomic sites to optimize oxygen electrocatalytic behaviors for high-performance Zn-air batteries

The development of redox bifunctional electrocatalysts with high performance,low cost,and long lifetimes is essential for achieving clean energy goals.This study proposed an atom capture strategy for anchoring dual single atoms(DSAs)in a zinc-zeolitic imidazolate framework(Zn-ZIF),followed by calcination under an N_(2) atmosphere to synthesize ruthenium-platinum DSAs supported on a nitrogendoped carbon substrate(RuPt DSAs-NC).Theoretical calculations showed that the degree of Ru 5dxz-~*O 2p_x orbital hybridization was high when^(*)O was adsorbed at the Ru site,indicating enhanced covalent hybridization of metal sites and oxygen ligands,which benefited the adsorption of intermediate species.The presence of the RuPtN_6 active center optimized the absorption-desorption behavior of intermediates,improving the electrocatalytic performance of the oxygen reduction reaction(ORR)and the oxygen evolution reaction(DER),RuPt DSAs-NC exhibited a 0.87 V high half-wave potential and a 268 mV low overpotential at 10 mA cm^(-2)in an alkaline environment.Furthermore,rechargeable zinc-air batteries(ZABs)achieved a peak power density of 171 MW cm^(-2).The RuPt DSAs-NC demonstrated long-term cycling for up to 500 h with superior round-trip efficiency.This study provided an effective structural design strategy to construct DSAs active sites for enhanced electrocata lytic performance.

Ultra‑Stable Sodium‑Ion Battery Enabled by All‑Solid‑State Ferroelectric‑Engineered Composite Electrolytes

Symmetric Na-ion cells using the NASICON-structured electrodes could simplify the manufacturing process,reduce the cost,facilitate the recycling post-process,and thus attractive in the field of large-scale stationary energy storage.However,the long-term cycling performance of such batteries is usually poor.This investigation reveals the unavoidable side reactions between the NASICON-type Na_(3)V_(2)(PO_(4))_(3)(NVP)anode and the commercial liquid electrolyte,leading to serious capacity fading in the symmetric NVP//NVP cells.To resolve this issue,an all-solid-state composite electrolyte is used to replace the liquid electrolyte so that to overcome the side reaction and achieve high anode/electrolyte interfacial stability.The ferroelectric engineering could further improve the interfacial ion conduction,effectively reducing the electrode/electrolyte interfacial resistances.The NVP//NVP cell using the ferroelectric-engineered composite electrolyte can achieve a capacity retention of 86.4%after 650 cycles.Furthermore,the electrolyte can also be used to match the Prussianblue cathode NaxFeyFe(CN)_(6−z)·nH_(2)O(NFFCN).Outstanding long-term cycling stability has been obtained in the all-solid-state NVP//NFFCN cell over 9000 cycles at a current density of 500 mA g^(-1),with a fading rate as low as 0.005%per cycle.

Covalency competition induced selective bond breakage and surface reconstruction in manganese cobaltite towards enhanced electrochemical charge storage

Manganese cobaltite(MnCo_(2)_(4))is a promising electrode material because of its attractive redox chemistry and excellent charge storage capability.Our previous work demonstrated that the octahedrally-coordinated Mn are prone to react with the hydroxyl ions in alkaline electrolyte upon electrochemical cycling and separates on the surface of spinel to reconstruct into d-MnO_(2) nanosheets irreversibly,thus results in a change of the reaction mechanism with Kþion intercalation.However,the low capacity has greatly limited its practical application.Herein,we found that the tetrahedrally-coordinated Co_(2) þions were leached when MnCo_(2)_(4) was equilibrated in 1 mol L^(-1) HCl solution,leading to the formation of layered CoOOH on MnCo_(2)_(4) surface which is originated from the covalency competition induced selective breakage of the CoT–O bond in CoT–O–CoO and subsequent rearrangement of free Co_(6) octahedra.The as-formed CoOOH is stable upon cycling in alkaline electrolyte,exhibits conversion reaction mechanism with facile proton diffusion and is free of massive structural evolution,thus enables utilization of the bulk electrode material and realizes enhanced specific capacity as well as facilitated charge transfer and ion diffusion.In general,our work not only offers a feasible approach to deliberate modification of MnCo_(2)_(4)'s surface structure,but also provides an in-depth understanding of its charge storage mechanism,which enables rational design of the spinel oxides with promising charge storage properties.

A perspective on the key factors of safety for rechargeable magnesium batteries

Rechargeable Mg batteries(RMBs)have become one of the best subsitutes for lithium-ion batteries due to the high volumetric capacity,abundant resources,and uniform plating behavior of Mg metal anode.However,the safety hazard induced by the formation of high-modulue Mg dendrites under a high current density(10 mA cm^(-1))was still revealed in recent years.It has forced researchers to re-examine the safety of RMBs.In this review,the intrinsic safety factors of key components in RMBs,such as uneven plating,pitting and flammability of Mg anode,heat release and crystalline water decomposition of cathode,strong corrosion,low oxidition stability and flammability of electrolytes,and soforth,are systematacially summarized.Their origins,formation mechanisms,and possible safety hazards are deeply discussed.To develop high-performance Mg anode,current strategies including designing artificial SEI,three-dimensional substrates,and Mg alloys are summarized.For practical electrolytes,the configurations of boron-centered anions and simple Mg salts and the functionalized solvent with high boiling point and low flammability are suggested to comprehensively design.In addition,the future study should more focus on the investigation on the thermal runaway and decomposition of cathode materials and separa-tors.This review aims to provide fundamental insights into the relationship between electrochemistry and safety,further promoting the sustainable development of RMBs.

Layered buserite Mg-Mn oxide cathode for aqueous rechargeable Mg-ion battery

Owing to the features(high safety,inexpensive and environmental friendliness)of aqueous rechargeable Mg-ion batteries(ARMIBs),they have drawn extensive attention in the future energy storage systems.However,the poor Mg^(2+)migration kinetics during the Mg^(2+)intercalation/extraction still hinders the progress of developing suitable cathode materials.Herein,a layered buserite Mg-Mn oxide(MMO)material with large interlayer space(~9.70A)and low-crystalline structure is studied as a high-performance cathode in ARMIBs.Compared with the counterpart,the Mg^(2+)migration kinetics of the MMO cathode can be enhanced by its unique structure(bigger interlayer spacing and low-crystalline structure).The layered buserite MMO as a high-performance ARMIBs cathode exhibits high Mg storage capacity(50 mAg^(-1):169.3 mAh g^(-1)),excellent rate capability(1000 mAg^(-1):98.3 mAh g^(-1)),and fast Mg^(2+)migration(an average diffusion coefficient:~4.21×10-^(10)cm^(2)s^(-1))in 0.5 M MgCl_(2)aqueous electrolyte.Moreover,the MMO-1//AC full battery achieved a high discharge capacity(100 mAg^(-1):111 mAh g^(-1)),and an ignored fading over 5000 cycles(1000 mAg^(-1)).Therefore,layered Mg-Mn oxide with large interlayer space may break a new path to develop the promising ARMIBs.

Electrocatalytic oxygen evolution activities of metal chalcogenides and phosphides:Fundamentals,origins,and future strategies

The development of inexpensive and efficient electrocatalysts is key to commercializing energy-related electrocatalytic techniques such as water electrolyzers and metal-air batteries.In particular,novel oxygen evolution reaction(OER)pre-catalysts,such as transition metal chalcogenides(TMCs)and phosphides(TMPs),have evolved in recent years from traditional stable OER electrocatalysts,which show superior OER electrocatalytic performance compared with transition metal oxides(TMOs)or(oxy)hydroxides(TMOHs).In this feature article,we summarize recent advances in the development of TMCand TMP-based OER electrocatalysts,as well as approaches to improve the OER performance in terms of morphology,structure,composition,surface engineering,lattice-strained and in-situ transformation in the electrolysis process.In particular,the electrochemical stability of TMCs and TMPs in alkaline electrolytes and the evolution of morphology,structure and composition under OER conditions are discussed.In the last section,we discuss the challenges that need to be addressed in this specific area of research and the implications for further research.

Vacancies and interfaces engineering of core-shell heterostuctured NiCoP/NiO as trifunctional electrocatalysts for overall water splitting and zinc-air batteries

The electronic structures and properties of electrocatalysts,which depend on the physicochemical structure and metallic element components,could significantly affect their electrocatalytic performance and their future applications in Zn-air battery(ZAB)and overall water splitting(OWS).Here,by combining vacancies and heterogeneous interfacial engineering,three-dimensional(3D)core-shell NiCoP/NiO heterostructures with dominated oxygen vacancies have been controllably in-situ grown on carbon cloth for using as highly efficient electrocatalysts toward hydrogen and oxygen electrochemical reactions.Theoretical calculation and electrochemical results manifest that the hybridization of NiCoP core with NiO shell produces a strong synergistic electronic coupling effect.The oxygen vacancy can enable the emergence of new electronic states within the band gap,crossing the Fermi levels of the two spin components and optimizing the local electronic structure.Besides,the hierarchical core-shell NiCoP/NiO nanoarrays also endow the catalysts with multiple exposed active sites,faster mass transfer behavior,optimized electronic strutures and improved electrochemical performance during ZAB and OWS applications.

Development of solid-state electrolytes for sodium-ion battery–A short review

All-solid-state sodium-ion battery is regarded as the next generation battery to replace the current commercial lithium-ion battery, with the advantages of abundant sodium resources, low price and high-level safety. As one critical component in sodium-ion battery, solid-state electrolyte should possess superior operational safety and design simplicity, yet reasonable high room-temperature ionic conductivity. This paper gives a comprehensive review on the recent progress in solid-state electrolyte materials for sodium-ion battery, including inorganic ceramic/glass-ceramic, organic polymer and ceramic-polymer composite electrolytes, and also provides a comparison of the ionic conductivity in various solid-state electrolyte materials. The development of solid-state electrolytes suggests a bright future direction: all solid-state sodium-ion battery could be fully used to power all electric road vehicles, portable electronic devices and large-scale grid support.

Progress in aqueous rechargeable batteries

Over the past decades, a series of aqueous rechargeable batteries(ARBs) were explored, investigated and demonstrated. Among them,aqueous rechargeable alkali-metal ion(Li^+Na^+, K^+) batteries, aqueous rechargeable-metal ion(Zn^(2+),Mg^(2+), Ca^(2+), Al^(3+)) batteries and aqueous rechargeable hybrid batteries are standing out due to peculiar properties. In this review, we focus on the fundamental basics of these batteries, and discuss the scientific and/or technological achievements and challenges. By critically reviewing state-of-the-art technologies and the most promising results so far, we aim to analyze the benefits of ARBs and the critical issues to be addressed, and to promote better development of ARBs.

Rational Design of Layered SnS2 on Ultralight Graphene Fiber Fabrics as Binder-Free Anodes for Enhanced Practical Capacity of Sodium-Ion Batteries

Generally,the practical capacity of an electrode should include the weight of non-active components such as current collector,polymer binder,and conductive additives,which were as high as 70 wt%in current reported works,seriously limiting the practical capacity.This work pioneered the usage of ultralight reduced graphene fiber(rGF)fabrics as conductive scaffolds,aiming to reduce the weight of nonactive components and enhance the practical capacity.Ultrathin SnS2 nanosheets/rGF hybrids were prepared and used as binder-free electrodes of sodium-ion batteries(SIBs).The interfused graphene fibers endow the electrode a porous,continuous,and conductive network.The in situ phase transformation from SnO2 to SnS2 could preserve the strong interfacial interactions between SnS2 and graphene.Benefitting from these,the designed binder-free electrode delivers a high specific capacity of 500 mAh g?1 after 500 cycles at a current rate of 0.5 A g?1 with almost 100%Coulombic efficiency.Furthermore,the weight percentage of SnS2 in the whole electrode could reach up to 67.2 wt%,much higher than that of common electrode configurations using Cu foil,Al foil,or carbon cloth,significantly highlighting the ultralight characters and advantages of the rGF fabrics for using as binder-free electrodes of SIBs.

Freestanding polypyrrole nanotube/reduced graphene oxide hybrid film as flexible scaffold for dendrite-free lithium metal anodes

Lithium metal anode is the most potential anode material for the next generation high-energy rechargeable batteries owing to its highest specific capacity and lowest redox potential.Unfortunately,the uneven deposition of Li during plating/stripping and the formation of uncontrolled Li dendrites,which might cause poor battery performance and serious safety problems,are demonstrating to be a huge challenge for its practical application.Here,we show that a flexible and free-standing film hybriding with polypyrrole(PPy) nanotubes and reduced graphene oxide(rGO) can significantly regulate the Li nucleation and deposition,and further prohibit the formation of Li dendrites,owing to the large specific surface area,rich of nitrogen functional groups and porous structures.Finally,the high Coulombic efficiency and stable Li plating/stripping cycling performance with 98% for 230 cycles at 0.5 mA cm^(-2) and more than 900 hours stable lifespan are achieved.No Li dendrites form even at a Li deposition capacity as high as4.0 mA h cm^(-2).Besides,the designed PPy/rGO hybrid anode scaffold can also drive a superior battery performance in the lithium-metal full cell applications.

Transition metal carbonate anodes for Li-ion battery: fundamentals,synthesis and modification

Even though transition metal carbonates(TMCs, TM = Fe, Mn, Co, Ni etc.), show high theoretical capacities, rich reserves and environmental friendliness as anodes for lithium-ion batteries(LIBs), they suffer from sluggish electronic/ionic conductivities and huge volume variation, which severely deteriorate the rate capacities and cycling performances. Understanding the intrinsic reaction mechanism and further developing ideal TMC-based anode with high specific capacity, excellent rate capabilities, and longterm cycling stability are critical for the practical application of TMCs. In this review, we firstly focus on the fundamental electrochemical energy-storage mechanisms of TMCs, in terms of conversionreaction process, pseudocapacitance-type charge storage, valence change for charge storage and catalytic conversion mechanisms. Based on the reaction mechanisms, various modification strategies to improve the electrochemical performance of TMCs are summarized, covering:(i) micro-nano structural engineering, in which the influence factors on the morphology are discussed, and multiple architectures are listed;(ii) elemental doping, in which the intrinsic mechanisms of metal/nonmetal elements doping on the electrochemical performance are deeply explored;(iii) multifunctional compositing strategies, in which the specific affections on structure, electronic conductivity and chemo-mechanical stability are summarized.Finally, the key challenges and opportunities to develop high-performance TMCs are discussed and some solutions are also proposed. This timely review sheds light on the path towards achieving cost-effective and safe LIBs with high energy density and long cycling life using TMCs-based anode materials.

The design of Co_(3)S_(4)@MXene heterostructure as sulfur host to promote the electrochemical kinetics for reversible magnesium-sulfur batteries

The rechargeable Mg-S batteries are attractive because of their resource abundances of Mg and S,high volumetric energy density,and less dendrite property of Mg anodes.However,the development is barred by the intrinsic low electronic conductivity of S and the discharge products as well as the lack of understanding the hidden electrochemical kinetics.Here,a Co_(3)S_(4)@MXene heterostructure is proposed as effective sulfur host for reversible Mg-S batteries.XPS results and density functional theory(DFT)calculation confirm that the chemical interaction between the decorated Co_(3)S_(4)nanocrystals host and polysulfide intermediates could well absorb and catalyze the polysulfides conversion,thus improve the electrochemical redox kinetics.Meanwhile,the MXene matrix could promote Mg ion diffusion dynamics greatly.As a result,the developed Mg-S batteries using the Co_(3)S_(4)@MXene-S as the cathode material could demonstrate high sulfur utilization with specific capacity of 1220 mAh g^(-1) and retain a capacity of 528 mAh g^(-1) after 100 cycles,together with a satisfactory rate performance even at 2 C.This work shed light on the advanced cathode design for reversible high energy Mg-S batteries.

Stabilizing SEI by cyclic ethers toward enhanced K^(+) storage in graphite

The poor cycling stability of graphite in traditional ester electrolyte limits its applications as anodes for potassium ion batteries(KIBs).Herein,we demonstrate that the introduction of cyclic ether co-solvents into ester electrolytes can remarkably enhance the cycling stability of graphite anodes.The graphite anode in ester electrolyte with cyclic ether could achieve a reversible capacity of 196.1 m Ah g^(-1) after 100 cycles at 0.3 C(1 C=280 m A g^(-1)),about three times higher than those in ester electrolytes with or without linear ether.Compared with the SEI formed in ester electrolytes,the addition of tetrahydrofuran promotes the generation of K_(2)CO_(3) and ethylene oxide oligomers(PEO),of which the K_(2)CO_(3) is expected to be more conductive and PEO is mechanically robust.The more uniform,conductive and stable solid electrolyte interphases(SEIs)on graphite in electrolytes with cyclic ethers contribute to the enhancement of the electrochemical performances of graphite.This work provides a novel design of commercialized electrolytes to achieve high-performance anodes for KIBs,which potentially accelerates the development of KIBs.

Origin of the electrocatalytic oxygen evolution activity of nickel phosphides: in-situ electrochemical oxidation and Cr doping to achieve high performance

Zinc-air batteries(ZnABs) with high theoretical capacity and environmental benignity are the most promising candidates for next-generation electronics. However, their large-scale applications are greatly hindered due to the lack of high-efficient and cost-effective electrocatalysts. Transition metal phosphides(TMPs) have been reported as promising electrocatalysts. Notably,(Ni_(1-x)Cr_(x))_(2) P(0≤x≤0.15) is an unstable electrocatalyst, which undergoes in-situ electrochemical oxidation during the initial oxygen evolution reaction(OER) and even in the activation cycles, and is eventually converted to Cr-NiOOH serving as the actual OER active sites with high efficiency. Density functional theory(DFT) simulations and experimental results elucidate that the OER performance could be significantly promoted by the synergistic effect of surface engineering and electronic modulations by Cr doping and in-situ phase transformation. The constructed rechargeable ZnABs could stably cycle for more than 208 h at 5 m A cm^(-2), while the voltage degradation is negligible. Furthermore, the developed catalytic materials could be assembled into flexible and all-solid-state Zn ABs to power wearable electronics with high performance.

Universal lithiophilic interfacial layers towards dendrite-free lithium anodes for solid-state lithium-metal batteries

Solid-state lithium-metal-batteries(SSLMBs)using garnet Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)as the solid electrolyte are expected to conquer the safety concerns of high energy Li batteries with organic liquid electrolytes owing to its nonflammable nature and good mechanical strength.However,the poor interfacial contact between the Li anode and LLZTO greatly restrains the practical applications of the electrolyte,because large polarization,dendritic Li formation and penetration can occur at the interfaces.Here,an effective method is proposed to improve the wettability of the LLZTO toward lithium and reduce the interfacial resistance by engineering universal lithiophilic interfacial layers.Thanks to the in-situ formed lithiophilic and ionic conductive Co/Li_(2)O interlayers,the symmetric Li/CoO-LLZTO/Li batteries present much smaller overpotential,ultra-low areal specific resistance(ASR,12.3 X cm^(2)),high critical current density(CCD,1.1 mA cm^(-2)),and outstanding cycling performance(1696 h at a current density of 0.3 mA cm^(-2))at 25℃.Besides,the solid-state Li/CoO-LLZTO/LFP cells deliver an excellent electrochemical performance with a high coulombic efficiency of~100%and a long cycling time over 185 times.Surprisingly,the high-voltage(4.6 V)solid state Li/CoO-LLZTO/Li_(1.4)Mn_(0.6)Ni_(0.2)Co_(0.2)O_(2.4)(LMNC622)batteries can also realize an ultra-high specific capacity(232.5 mAh g-1)under 0.1 C at 25℃.This work paves an effective way for practical applications of the dendrite-free SSLMBs.

Engineering of Co_(3O)_(4)@Ni_(2)P heterostructure as trifunctional electrocatalysts for rechargeable zinc-air battery and self-powered overall water splitting

Rational design of highly efficient,robust and nonprecious electrocatalysts for the oxygen reduction reaction(ORR),oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)is highly demanded and challenging.Here,heterostructural Co_(3O)_(4)@Ni_(2)P arrays with numerous reaction sites,unique interfacial electronic structure and fast charge transfer kinetics are developed as electrocatalysts for rechargeable Zn-air batteries and overall water splitting.Both density functional theory calculation and X-ray absorption fine structure analysis manifest that the synergistic structural and abundant electronic modulations interfaces are formed,thus simultaneously promoting the electrocatalytic kinetics,activities and stabilities.Specifically,it can achieve an ultralow overpotential of 270 m V and 28 m V at 10 m A cm^(-2) for OER and HER,respectively.The water electrolyzer delivers a current density of 10 m A cm^(-2) at 1.563 V;furthermore,rechargeable Zn-air batteries triggered by this heterostructure can achieve excellent cyclic stability of 177 h(2 h per cycle)at 10 m A cm^(-2);both devices are superior to the Pt/C+Ir/C.This work not only designs an efficient trifunctional electrocatalyst but also paves an avenue to understand the heterostructure engineering for catalysts development and disclose the underlying relationship of interfacial electronic structures and catalytic properties.