Ni–Co bimetallic coordination effect for long lifetime rechargeable Zn–air battery

The development of bifunctional oxygen electrocatalysts with high efficiency, high stability, and low cost is of great significance to the industrialization of rechargeable Zn–air batteries. A widely accepted view is that the oxygen reduction reaction(ORR) and the oxygen evolution reaction(OER) follow different catalytic mechanisms, and accordingly they need different active sites for catalysis. Transition metal elements have admirable electronic acceptance ability for coordinating with reactants, and this can weaken the bond energy between reactants, thus promoting the ORR or OER reactions. Herein, the ORR and OER activities of different transition metal supported nitrogen-doped carbon nanotubes were systematically studied and compared. The optimal catalyst for synchronous ORR and OER was obtained by pyrolyzing melamine, cobalt nitrate, and nickel nitrate on carbon nanotubes, called cobalt–nickel supported nitrogenmixed carbon nanotubes(CoNi–NCNT), which were equipped with two types of high-performance active sites—the Co/Ni–N–C structure for the ORR and Co Ni alloy particles for the OER—simultaneously. Remarkably, the optimized Co Ni–NCNT exhibited a satisfactory bifunctional catalytic activity for both the ORR and OER. The value of the oxygen electrode activity parameter,△E, of CoNi–NCNT was 0.81 V, which surpasses that of catalysts Pt/C and Ir/C, and most of the non-precious metal-based bifunctional electrocatalysts reported in previous literatures. Furthermore, a specially assembled rechargeable Zn–air cell with Co Ni–NCNT loaded carbon paper as an air cathode was used to evaluate the practicability. As a result, a superior specific capacity of 744.3 mAh/gZn, a peak power density of 88 mW/cm2, and an excellent rechargeable cycling stability were observed, and these endow the Co Ni–NCNT with promising prospects for practical application.

Flexible, Porous, and Metal–Heteroatom?Doped Carbon Nanofibers as Efficient ORR Electrocatalysts for Zn–Air Battery

Developing an e cient and durable oxygen reduction electrocatalyst is critical for clean-energy technology, such as fuel cells and metal–air batteries. In this study, we developed a facile strategy for the preparation of flexible, porous, and well-dispersed metal–heteroatom-doped carbon nanofibers by direct carbonization of electrospun Zn/Co-ZIFs/PAN nanofibers(Zn/Co-ZIFs/PAN). The obtained Zn/Co and N co-doped porous carbon nanofibers carbonized at 800 °C(Zn/Co–N@PCNFs-800) presented a good flexibility, a continuous porous structure, and a superior oxygen reduction reaction(ORR) catalytic activity to that of commercial 20 wt% Pt/C, in terms of its onset potential(0.98 V vs. RHE), half-wave potential(0.89 V vs. RHE), and limiting current density(-5.26 mA cm^(-2)). In addition, we tested the suitability and durability of Zn/Co–N@PCNFs-800 as the oxygen cathode for a rechargeable Zn–air battery. The prepared Zn–air batteries exhibited a higher power density(83.5 mW cm^(-2)), a higher specific capacity(640.3 mAh g^(-1)), an excellent reversibility, and a better cycling life than the commercial 20 wt% Pt/C + RuO_2 catalysts. This design strategy of flexible porous non-precious metal-doped ORR electrocatalysts obtained from electrospun ZIFs/polymer nanofibers could be extended to fabricate other novel, stable, and easy-to-use multi-functional electrocatalysts for clean-energy technology.

In Situ Coupling Strategy for Anchoring Monodisperse Co_9S_8 Nanoparticles on S and N Dual?Doped Graphene as a Bifunctional Electrocatalyst for Rechargeable Zn–Air Battery

An in situ coupling strategy to prepare Co_9S_8/S and N dual?doped graphene composite(Co_9S_8/NSG) has been proposed. The key point of this strategy is the function?oriented design of organic compounds. Herein, cobalt porphyrin derivatives with sulfo groups are employed as not only the coupling agents to form and anchor Co_9S_8 on the graphene in situ, but also the heteroatom?doped agent to generate S and N dual?doped graphene. The tight coupling of multiple active sites endows the composite materials with fast electrochemical kinetics and excellent stability for both oxygen reduction reaction(ORR) and oxygen evolution reaction(OER). The obtained electrocatalyst exhibits better activity parameter(ΔE = 0.82 V) and smaller Tafel slope(47.7 mV dec^(-1) for ORR and 69.2 mV dec^(-1) for OER) than commercially available Pt/C and RuO_2. Most importantly, as electrocatalyst for rechargeable Zn–air battery, Co_9S_8/NSG displays low charge–discharge voltage gap and outstanding long?term cycle stability over 138 h compared to Pt/C–RuO_2. To further broaden its application scope, a homemade all?solid?state Zn–air battery is also prepared, which displays good charge–discharge performance and cycle performance. The function?oriented design of N_4?metallomacrocycle derivatives might open new avenues to strategic construction of high?performance and long?life multifunctional electrocatalysts for wider electro?chemical energy applications.

Bimetallic Nickel Cobalt Sulfide as E cient Electrocatalyst for Zn–Air Battery and Water Splitting

The development of e cient earth-abundant electrocatalysts for oxygen reduction, oxygen evolution, and hydrogen evolution reactions(ORR, OER, and HER) is important for future energy conversion and energy storage devices, for which both rechargeable Zn–air batteries and water splitting have raised great expectations. Herein, we report a single-phase bimetallic nickel cobalt sulfide((Ni,Co)S_2) as an e cient electrocatalyst for both OER and ORR. Owing to the synergistic combination of Ni and Co, the(Ni,Co)S_2 exhibits superior electrocatalytic performance for ORR, OER, and HER in an alkaline electrolyte, and the first principle calculation results indicate that the reaction of an adsorbed O atom with a H_2O molecule to form a *OOH is the potential limiting step in the OER. Importantly, it could be utilized as an advanced air electrode material in Zn–air batteries, which shows an enhanced charge–discharge performance(charging voltage of 1.71 V and discharge voltage of 1.26 V at 2 mA cm^(-2)), large specific capacity(842 mAh g_(Zn)^(-1) at 5 mA cm^(-2)), and excellent cycling stability(480 h). Interestingly, the(Ni,Co)S_2-based Zn–air battery can e ciently power an electrochemical water-splitting unit with(Ni,Co)S_2 serving as both the electrodes. This reveals that the prepared(Ni,Co)S_2 has promising applications in future energy conversion and energy storage devices.

Hollow cobalt oxide nanoparticles embedded in nitrogen-doped carbon nanosheets as an efficient bifunctional catalyst for Zn–air battery

Rational design of low-cost, highly electrocatalytic activity, and stable bifunctional electrocatalysts for oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) has been a great significant for metal–air batteries. Herein, an efficient bifunctional electrocatalyst based on hollow cobalt oxide nanoparticles embedded in nitrogen-doped carbon nanosheets(Co/N-Pg) is fabricated for Zn–air batteries. A lowcost biomass peach gum, consisting of carbon, oxygen, and hydrogen without other heteroatoms, was used as carbon source to form carbon matrix hosting hollow cobalt oxide nanoparticles. Meanwhile, the melamine was applied as nitrogen source and template precursor, which can convert to carbon-based template graphitic carbon nitride by polycondensation process. Owing to the unique structure and synergistic effect between hollow cobalt oxide nanoparticles and Co-N-C species, the proposal Co/N-Pg catalyst displays not only prominent bifunctional electrocatalytic activities for ORR and OER, but also excellent durability. Remarkably, the assembled Zn–air battery with Co/N-Pg air electrode exhibited a low discharge-charge voltage gap(0.81 V at 50 mA cm^-2) and high peak power density(119 mW cm^-2) with long-term cycling stability. This work presents an effective approach for engineering transition metal oxides and nitrogen modified carbon nanosheets to boost the performance of bifunctional electrocatalysts for Zn–air battery.

Recent progress of self-supported air electrodes for flexible Zn-air batteries

Smart wearable devices are regarded to be the next prevailing technology product after smartphones and smart homes,and thus there has recently been rapid development in flexible electronic energy storage devices.Among them,flexible solid-state zinc-air batteries have received widespread attention because of their high energy density,good safety,and stability.Efficient bifunctional oxygen electrocatalysts are the primary consideration in the development of flexible solid-state zinc-air batteries,and self-supported air cathodes are strong candidates because of their advantages including simplified fabrication process,reduced interfacial resistance,accelerated electron transfer,and good flexibility.This review outlines the research progress in the design and construction of nanoarray bifunctional oxygen electrocatalysts.Starting from the configuration and basic principles of zinc-air batteries and the strategies for the design of bifunctional oxygen electrocatalysts,a detailed discussion of self-supported air cathodes on carbon and metal substrates and their uses in flexible zinc-air batteries will follow.Finally,the challenges and opportunities in the development of flexible zinc-air batteries will be discussed.

Microstructure design of advanced magnesium-air battery anodes

Metal-air battery is an environmental friendly energy storage system with unique open structure.Magnesium(Mg)and its alloys have been extensively attempted as anodes for air batteries due to high theoretical energy density,low cost,and recyclability.However,the study on Mg-air battery(MAB)is still at the laboratory level currently,mainly owing to the low anodic efficiency caused by the poor corrosion resistance.In order to reduce corrosion losses and achieve optimal utilization efficiency of Mg anode,the design strategies are reviewed from microstructure perspectives.Firstly,the corrosion behaviors have been discussed,especially the negative difference effect derived by hydrogen evolution.Special attention is given to the effect of anode micro-structures on the MAB,which includes grain size,grain orientation,second phases,crystal structure,twins,and dislocations.For further improvement,the discharge performance,long period stacking ordered phase and its enhancing effect are considered.Meanwhile,given the current debates over Mg dendrites,the potential risk,the impact on discharge,and the elimination strategies are discussed.Microstructure control and single crystal would be promising ways for MAB anode.

Regulating zinc ion transport behavior and solvated structure towards stable aqueous Zn metal batteries

Aqueous Zn metal batteries(AZMBs)with intrinsic safety,high energy density and low cost have been regarded as promising electrochemical energy storage devices.However,the parasitic reaction on metallic Zn anode and the incompatibility between electrode and electrolytes lead to the deterioration of electrochemical performance of AZMBs during the cycling.The critical point to achieve the stable cycling of AZMBs is to properly regulate the zinc ion solvated structure and transfer behavior between metallic Zn anode and electrolyte.In recent years,numerous achievements have been made to resolve the formation of Zn dendrite and interface incompatible issues faced by AZMBs via optimizing the sheath structure and transport capability of zinc ions at electrode-electrolyte interface.In this review,the challenges for metallic Zn anode and electrode-electrolyte interface in AZMBs including dendrite formation and interface characteristics are presented.Following the influences of different strategies involving designing advanced electrode structu re,artificial solid electrolyte interphase(SEI)on Zn anode and electrolyte engineering to regulate zinc ion solvated sheath structure and transport behavior are summarized and discussed.Finally,the perspectives for the future development of design strategies for dendrite-free Zn metal anode and long lifespan AZMBs are also given.

Recent Advances in Aqueous Zn||MnO_(2)Batteries

Recently,rechargeable aqueous zinc-based batteries using manganese oxide as the cathode(e.g.,MnO_(2))have gained attention due to their inherent safety,environmental friendliness,and low cost.Despite their potential,achieving high energy density in Zn||MnO_(2)batteries remains challenging,highlighting the need to understand the electrochemical reaction mechanisms underlying these batteries more deeply and optimize battery components,including electrodes and electrolytes.This review comprehensively summarizes the latest advancements for understanding the electrochemistry reaction mechanisms and designing electrodes and electrolytes for Zn||MnO_(2)batteries in mildly and strongly acidic environments.Furthermore,we highlight the key challenges hindering the extensive application of Zn||MnO_(2)batteries,including high-voltage requirements and areal capacity,and propose innovative solutions to overcome these challenges.We suggest that MnO_(2)/Mn^(2+)conversion in neutral electrolytes is a crucial aspect that needs to be addressed to achieve high-performance Zn||MnO_(2)batteries.These approaches could lead to breakthroughs in the future development of Zn||MnO_(2)batteries,off ering a more sustainable,costeff ective,and high-performance alternative to traditional batteries.

Plasma-assisted aerogel interface engineering enables uniform Zn^(2+)flux and fast desolvation kinetics toward zinc metal batteries

The poor reversibility of Zn anodes induced by dendrite growth,surface passivation,and corrosion,severely hinders the practical applicability of Zn metal batteries.To address these issues,a plasmaassisted aerogel(PAG)interface engineering was proposed as efficient ion transport modulator that can simultaneously regulate uniform Zn^(2+)flux and desolvation behavior during battery operation.The PAG with ordered mesopores acted as an ion sieve to homogenize Zn deposition and accelerate Zn^(2+)flux,which is favorable for corrosion resistance and dendrite suppression.Importantly,the plasma-assisted aerogel with abundant hydrophilic groups can facilitate the desolvation kinetics of Zn^(2+)due to the multiple hydrogen-bonding interaction with the activated water molecules,thus accelerating the Zn^(2+)migration kinetics.Consequently,the Zn/Zn cell assembled with PAG-modified separator demonstrates stable plating and stripping behavior(over 1400 h at 1 mA cm^(-2))and high Coulombic efficiency(99.8%at1 mA cm^(-2)after 1100 cycles),and the Zn‖MnO_(2)full cell shows excellent long-term cycling stability and maintains a high capacity of 154.9 mA h g^(-1)after 1000 cycles at 1 A g^(-1).This study provides a feasible approach for the large-scale fabrication of aerogel functionalized separators to realize ultra-stable Zn metal batteries.

Regulating the inner Helmholtz plane structure at the electrolyte-electrode interface for highly reversible aqueous Zn batteries

The development of aqueous Zn batteries is limited by parasitic water reactions,corrosion,and dendrite growth.To address these challenges,an inner Helmholtz plane(IHP)regulation method is proposed by employing low-cost,non-toxic maltitol as the electrolyte additive.The preferential adsorption behavior of maltitol can expel the water from the inner Helmholtz plane,and thus hinder the immediate contact between Zn metal and H_(2)O.Meanwhile,strong interaction between maltitol and H_(2)O molecules can restrain the activity of H_(2)O.Besides,the"IHP adsorption effect"along with the low LUMO energy level of maltitol-CF_(3)SO_(3)^(-)can promote the in-situ formation of an organic-inorganic complex solid electrolyte interface(SEI)layer.As a result,the hydrogen/oxygen evolution side reaction,corrosion,and dendrites issues are effectively suppressed,thereby leading to highly reversible and dendrite-free Zn plating/stripping.The Zn‖I_(2)battery with hybrid electrolytes also demonstrates high electrochemical performance and ultralong cycling stability,showing a capacity retention of 75%over 20000 charge-discharge cycles at a large current density of 5 A g^(-1).In addition,the capacity of the device has almost no obvious decay over20000 cycles even at-30℃.This work offers a successful electrolyte regulation strategy via the IHP adsorption effect to design electrolytes for high-performance rechargeable Zn-ion batteries.

Boosting electrocatalytic activity with the formation of abundant heterointerfaces and N, S dual-doped carbon nanotube for rechargeable Zn-air battery

Herein,a facile synthetic strategy is proposed to fabricate high-performance electrocatalysts for rechargeable Zn-air batteries(ZABs).Heterostructured NiCo/NiCo_(2)S_(4) nanoparticles encapsulated in N-,S-co-doped CNT(NiCo/NiCo_(2)S_(4)@NSCNT) are synthesized via co-precipitation,thermal carbonization,and partial sulfidation processes.The strongly coupled NiCo/NiCo_(2)S_(4) heterostructure can improve the redox property and charge transfer ability.Also,the CNTs with abundant foreign dopants provide high electrical conductivity and abundant defect sites for both the oxygen evolution reaction(OER) and oxygen reduction reaction(ORR).The prepared NiCo/NiCo_(2)S_(4)@NSCNT electrocatalyst exhibits a low overpotential of 349 mV at a current density of 10 mA cm-2 and a half-wave potential of 0.865 V for the OER and ORR,respectively.Moreover,the ZAB assembled using as-prepared NiCo/NiCo_(2)S_(4)@NSCNT can provide superior specific capacity(756.16 mA h g_(Zn)^(-1)],peak power density(155.82 mW cm^(-2)),and long-term cyclability compared to those of the precious metal-based electrocatalyst(Pt/C+RuO_(2)).

An Air‑Rechargeable Zn Battery Enabled by Organic–Inorganic Hybrid Cathode

Self-charging power systems collecting energy harvesting technology and batteries are attracting extensive attention.To solve the disadvantages of the traditional integrated system,such as highly dependent on energy supply and complex structure,an airrechargeable Zn battery based on MoS_(2)/PANI cathode is reported.Benefited from the excellent conductivity desolvation shield of PANI,the MoS_(2)/PANI cathode exhibits ultra-high capacity(304.98 mAh g^(−1) in N_(2) and 351.25 mAh g^(−1) in air).In particular,this battery has the ability to collect,convert and store energy simultaneously by an airrechargeable process of the spontaneous redox reaction between the discharged cathode and O2 from air.The air-rechargeable Zn batteries display a high open-circuit voltage(1.15 V),an unforgettable discharge capacity(316.09 mAh g^(−1) and the air-rechargeable depth is 89.99%)and good air-recharging stability(291.22 mAh g^(−1) after 50 air recharging/galvanostatic current discharge cycle).Most importantly,both our quasi-solid zinc ion batteries and batteries modules have excellent performance and practicability.This work will provide a promising research direction for the material design and device assembly of the next-generation self-powered system.

Hybrid battery integrated by Zn-air and Zn-Co3O4 batteries at cell level

The construction of Zn based hybrid battery through the combination of Zn-air and Zn-Co3O4 batteries at cell level is a feasible strategy to integrate high voltage,specific capacity and energy density in one power supply equipment.For Zn based hybrid battery,an efficient cathode material with high specific capacitance and excellent ORR,OER activities is a vital component,which determines its performance in great extent.In this work,with Co based coordination polymer as precursor,oxygen vacancy-rich Co3 O4 based cathode material is synthesized.In this material Co3O4 particles with the size about 20 to 35 nm reside evenly in mesoporous carbon matrix doped by nitrogen atoms.In OER,the overpotential of this cathode material is merely 330 m V.Its ORR proceeds with a typical four electron process with half wave achieving 0.76 V.If charge/discharge at 1 A·g^-1,specific capacitance of this cathode material is 254.4 mAh·g^-1.As current density increases to 20 A·g^-1,the specific capacitance still arrives at 122.5 mAh·g^-1 with nearly 50%retained.Based on attractive performance of this cathode material,Zn based hybrid battery is assembled.When discharge at 1 m A·cm-2,it presences two voltage platforms at 1.71 and 1.14 V.In this situation,specific capacitance reaches 790 m Ah·g^-1 with energy density 928 Wh·kg^-1.Hybrid battery shows promising stability after 300-cycle continuous test.

Core-shell-structured Co@Co4N nanoparticles encapsulated into MnO-modified porous N-doping carbon nanocubes as bifunctional catalysts for rechargeable Zn–air batteries

Designing the highly catalytic activity and durable bifunctional catalysts toward oxygen reduction/evolution reaction(ORR/OER) is paramount for metal–air batteries. Metal–organic frameworks(MOFs)-based materials have attracted a great deal of attention as the potential candidate for effectively catalyzing ORR/OER due to their adjustable composition and porous structure. Herein, we first introduce the Mn species into zeolitic-imidazole frameworks(ZIFs) and then further pyrolyze the Mn-containing bimetallic ZIFs to synthesize core-shell-structured Co@Co4N nanoparticles embedded into MnO-modified porous N-doped carbon nanocubes(Co@Co4N/MnO–NC). Co@Co4N/MnO–NC exhibits the outstanding catalytic activity toward ORR and OER which is attributed to its abundant pyridinic/graphitic N and Co4N,the optimized content of MnO species, highly dispersed catalytic sites and porous carbon matrix. As a result, the Co@Co4N/MnO–NC-based Zn–air battery exhibits enhanced performances, including the high discharge capacity(762 mA h gZn-1), large power density(200.5 mW cm-2), stable potential profile over 72 h, low overpotential(<1.0 V) and superior cycling life(2800 cycles). Moreover, the belt-shaped Co@Co4N/MnO–NC cathode-based Zn–air batteries are also designed which exhibit the superb electrochemical properties at different bending/twisting conditions.

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.

An in-depth understanding of improvement strategies and corresponding characterizations towards Zn anode in aqueous Zn-ions batteries

Combining the unique advantages of aqueous electrolytes and metallic Zn anode, rechargeable aqueous Zn-ion batteries(ZIBs) are of great promise for large-scale energy storage applications due to their inherent high safety, low cost, and environmental friendliness. As the essential component of ZIBs, Zn metal anode suffers from severe dendrite formation and inevitable side reactions(e.g. corrosion and hydrogen evolution)in aqueous electrolytes, which leads to low Coulombic efficiency and inferior cycling stability, impeding their large-scale applications. To be compatible with satisfactory aqueous ZIBs, Zn anode has been modified from various perspectives and focus areas. Herein, based on their intrinsic characteristics, we review the related improvement strategies for Zn anode, including interphase, substrate, and bulk design, so as to achieve an in-depth understanding of Zn anode optimization. Furthermore, the timely summary of characterization methods for Zn anodes are also performed for the first time, from both thermodynamic and kinetics perspectives, which is particularly helpful for beginners to understand the complicated characterizations and employ suitable methods. Finally, certain noteworthy points are put forward for subsequent investigation of aqueous ZIBs. It is expected that this review will enlighten researchers to explore more efficient optimization strategies for Zn anode in aqueous electrolytes.

In situ construction of a stable composite solid electrolyte interphase for dendrite-free Zn batteries

Building a stable solid electrolyte interphase(SEI)has been regarded to be highly effective for mitigating the dendrite growth and parasitic side reactions of Zn anodes.Herein,a robust inorganic composite SEI layer is in situ constructed by introducing an organic cysteine additive to achieve long lifetime Zn metal batteries.The chemisorbed cysteine derivatives are electrochemically reduced to trigger a local alkaline environment for generating a gradient layered zinc hydroxide based multicomponent interphase.Such a unique interphase is of significant advantage as a corrosion inhibitor and Zn^(2+)modulator to enable reversible plating/stripping chemistry with a reduced desolvation energy barrier.Accordingly,the cells with a thin glass fiber separator(260μm)deliver a prolonged lifespan beyond 2000 h and enhanced Coulombic efficiency of 99.5%over 450 cycles.This work will rationally elaborate in situ construction of a desirable SEI by implanting reductive additives for dendrite-free Zn anodes.

Ultrafast Synthesis of Metal-Layered Hydroxides in a Dozen Seconds for High-Performance Aqueous Zn(Micro-)Battery

Efficient synthesis of transition metal hydroxides on conductive substrate is essential for enhancing their merits in industrialization of energy storage field.However,most of the synthetic routes at present mainly rely on traditional bottom-up method,which involves tedious steps,time-consuming treatments,or additional alkaline media,and is unfavorable for high-efficiency production.Herein,we present a facile,ultrafast and general avenue to synthesize transition metal hydroxides on carbon substrate within 13 s by Joule-heating method.With high reaction kinetics caused by the instantaneous high temperature,seven kinds of transition metal-layered hydroxides(TM-LDHs)are formed on carbon cloth.Therein,the fastest synthesis rate reaches~0.46 cm^(2)s^(-1).Density functional theory calculations further demonstrate the nucleation energy barriers and potential mechanism for the formation of metal-based hydroxides on carbon substrates.This efficient approach avoids the use of extra agents,multiple steps,and long production time and endows the LDHs@carbon cloth with outstanding flexibility and machinability,showing practical advantages in both common and micro-zinc ion-based energy storage devices.To prove its utility,as a cathode in rechargeable aqueous alkaline Zn(micro-)battery,the NiCo LDH@carbon cloth exhibits a high energy density,superior to most transition metal LDH materials reported so far.

Towards storable and durable Zn-MnO_(2) batteries with hydrous tetraglyme electrolyte

Aqueous rechargeable zinc-based batteries have attracted increasing interest and been considered potential alternatives for state-of-the-art lithium-ion batteries because of the low cost and high safety.Many cathode materials have been gradually developed and demonstrated excellent electrochemical performances.However,the complex electrochemistry,inevitable hydrogen release,and zinc corrosion severely hinder the practical application.The most concerned Zn-MnO_(2)batteries still suffer from the Mn dissolution and formation of byproducts.By adding organic solvents to inhibit the activity of water molecules,the hydrous organic electrolytes provide a sound solution for eliminating the unfavorable factors.Here we report a tetraethylene glycol dimethyl ether-based hydrous organic electrolyte consisting of LiClO_(4)·3H_(2)O and Zn(ClO4)2·6H2O,and a birnessite-type MnO_(2)cathode material for Zn-MnO_(2)batteries.The Li+/Zn2+ions co-(de)insertion mechanism is ascertained by the structural and morphological analyses.The electrostatic interaction between inserted ions and crystal structure is reduced effectively by employment of monovalent Li+ions,which ensures structural stability of cathode materials.Hydrous tetraglyme electrolyte inhibits the activity of water molecules and thus avoids the formation of byproduct Zn_(4)ClO_(4)(OH)7·Meanwhile,highly stable Zn plating/stripping for over 1500 h,an average coulombic efficiency of>99%in long-term cycling,and ultralong storage life(the cells can work well after stored over 1 year)are simultaneously realized in the novel electrolyte.Benefitting from these aspects,the Zn-MnO_(2)batteries manifest high specific capacity of 132 mA h g^(-1),an operating voltage of 1.25 V,and a capacity retention of>98%after 1000 cycles at a current density of 200 mA g^(-1).