A green repair pathway for spent spinel cathode material:Coupled mechanochemistry and solid-phase reactions

A way of directly repairing spent lithium-ion battery cathode materials is needed in response to environmental pollution and resource depletion.In this work,we report a green repair method involving coupled mechano-chemistry and solid-state reactions for spent lithium-ion batteries.During the ball-milling repair process,an added manganese source enters into the degraded LiMn_(2)O_(4)(LMO)crystal structure in order to fill the Mn vacancies formed by Mn deficiency due to the Jahn–Teller effect,thereby repairing the LMO's chemical composition.An added carbon source acts not only as a lubricant but also as a conductor to improve the material's electrical conductivity.Meanwhile,mechanical force reduces the crystal size of the LMO particles,increasing the amount of active sites for electrochemical reactions.Jahn–Teller distortion is successfully suppressed by cation disorder in the LMO material.The cycling stability and rate performance of the repaired cathode material are thereby greatly improved,with the discharge specific capacity being more than twice that of commercial LMO.The proposed solid-state mechanochemical in situ repair process,which is safe for the environment and simple to use,may be extended to the repair of other waste materials without consuming highly acidic or alkaline chemical reagents.

Single-crystalline Mn-based oxide as a high-rate and long-life cathode material for potassium-ion battery

Mn-based oxides are promising cathode materials for potassium-ion batteries due to their high theoretical ca-pacity and abundant raw materials.However,the anisotropic properties of their conventional polycrystalline structures lead to insufficient rate capability and cycle life.Here,a single-crystal Mn-based layered oxide,P3′-type K_(0.35)Mn_(0.8)Fe_(0.1)Cu_(0.1)O_(2)(KMFCO),is designed and synthesized through a bimetallic co-induction effect and used as a cathode for potassium-ion battery.Benefiting from a unique single-crystal structure that is devoid of grain boundaries,it achieves a higher Kþtransport rate and a reduced volume change during the Kþintercalation/deintercalation process.Accordingly,the single-crystal P3′-type KMFCO delivers superior rate capability(52.9 mAh g^(-1) at 1000 mA g^(-1))and excellent cycling stability(91.1%capacity retention after 500 cycles at 500 mA g^(-1)).A full cell assembled with the P3′-type KMFCO cathode and a graphite anode also exhibits a high reversible capacity(81.2 mAh g^(-1) at 100 mA g^(-1))and excellent cycling performance(97%capacity retention after 300 cycles).The strategy of developing single-crystal materials may offer a new pathway for maintaining structural stability and improving the rate capability of layered manganese oxide cathodes and beyond.

Anode corrosion in aqueous Zn metal batteries

Given their low cost and intrinsic safety,aqueous Zn metal batteries(AZMBs)are drawing increasing attention in the field of smart grids and large-scale energy storage.However,the Zn metal anode in aqueous electrolyte suffers from a critical issue,corrosion,which must be fully addressed before the practical implementation of AZMBs.In this perspective,the mechanisms of aqueous Zn metal anode corrosion in both alkaline and neutral electrolytes are compared and discussed.The methods for studying the corrosion processes and the strategies for Zn corrosion protection in AZMBs are also summarized.Finally,some expectations about potential research directions for making corrosion-resistant AZMBs a commercial reality are provided.

Recent progress in transition-metal-oxide-based electrocatalysts for the oxygen evolution reaction in natural seawater splitting: A critical review

Direct electrolytic splitting of seawater for the production of H2 using ocean energy is a promising technology that can help achieve carbon neutrality.However,owing to the high concentrations of chlorine ions in seawater,the chlorine evolution reaction always competes with the oxygen evolution reaction(OER)at the anode,and chloride corrosion occurs on both the anode and cathode.Thus,effective electrocatalysts with high selectivity toward the OER and excellent resistance to chloride corrosion should be developed.In this critical review,we focus on the prospects of state-of-the-art metal-oxide electrocatalysts,including noble metal oxides,non-noble metal oxides and their compounds,and spinel-and perovskite-type oxides,for seawater splitting.We elucidate their chemical properties,excellent OER selectivity,outstanding anti-chlorine-corrosion performance,and reaction mechanisms.In particular,we review metal oxides that operate at high current densities,near industrial application levels,based on special catalyst design strategies.

Interface boosted highly efficient selective photooxidation in Bi_(3)O_(4)Br/ Bi_(2)O_(3) heterojunctions

Selective photooxidation of amines to biologically important imines is in great demand for industrial applications.The conversion efficiency and selectivity of the process are strongly dependent on the activation of photocatalytic molecular oxygen(O_(2))into reactive oxygen species.Here,we propose the construction of rich interfaces to boost photocatalytic O_(2) activation by facilitating the transfer of photocarriers.Taking Bi_(3)O_(4)Br/Bi_(2)O_(3) heterojunctions as an example,rich interfaces facilitate electron transfer to adsorbed O_(2) for superoxide(O_(2)⋅^(-))generation,thus achieving≥98%conversion efficiency and selectivity for benzylamine and benzylamine derivatives.This study offers a valid method to design advanced photocatalysts for selective oxidation reactions.

Hierarchical and lamellar porous carbon as interconnected sulfur host and polysulfide-proof interlayer for Li–S batteries

A robust three-dimensional(3D)interconnected sulfur host and a polysulfide-proof interlayer are key components in high-performance Li–S batteries.Herein,cellulose-based 3D hierarchical porous carbon(HPC)and two-dimensional(2D)lamellar porous carbon(LPC)are employed as the sulfur host and polysulfide-proof inter-layer,respectively,for a Li–S battery.The 3D HPC displays a cross-linked macroporous structure,which allows high sulfur loading and restriction capability and provides unobstructed electrolyte diffusion channels.With a stackable carbon sheet of 2D LPC that has a large plane view size and is ultrathin and porous,the LPC-coated separator effectively inhibits polysulfides.An optimized combination of the HPC and LPC yields an electrode structure that effectively protects the lithium anode against corrosion by polysulfides,giving the cell a high ca-pacity of 1339.4 mAh g^(-1) and high stability,with a capacity decay rate of 0.021% per cycle at 0.2C.This work provides a new understanding of biomaterials and offers a novel strategy to improve the performance of Li–S batteries for practical applications.

Hydrogen isotope effects: A new path to high-energy aqueous rechargeable Li/Na-ion batteries

Aqueous rechargeable Li/Na-ion batteries have shown promise for sustainable large-scale energy storage due to their safety,low cost,and environmental benignity.However,practical applications of aqueous batteries are plagued by water's intrinsically narrow electrochemical stability window,which results in low energy density.In this perspective article,we review several strategies to broaden the electrochemical window of aqueous electrolytes and realize high-energy aqueous batteries.Specifically,we highlight our recent findings on stabilizing aqueous Li storage electrochemistry using a deuterium dioxide-based aqueous electrolyte,which shows significant hydrogen isotope effects that trigger a wider electrochemical window and inhibit detrimental parasitic processes.

Near-unity quantum yield in zero-dimensional lead-free manganese-based halides for flexible X-ray imaging with high spatial resolution

Low-dimensional luminescent lead-free metal halides have received substantial attention due to their unique optoelectronic properties.Among them,zero-dimensional(0D)manganese(II)-based metal halides with negligible self-absorption have emerged as potential candidates in X-ray scintillators.Herein,we for the first time report a novel lead-free(TBA)_(2)MnBr_(4) single crystal synthesized via a facile solvent evaporation method.In this crystal,[MnBr_(4)]^(2-)units are isolated by large TBA^(+)organic cations,resulting in a unique 0D structure.The prepared manganese-based crystals exhibit a bright-green emission centered at 512 nm with a high photoluminescence quantum yield(PLQY)of 93.76%at room temperature,originating from the ^(4)T_(1)–^(6)A_(1) transition of Mn^(2+).Apart from their outstanding optical performance,the crystals also show excellent stability and can maintain 94.4%of the initial PLQY even after being stored in air for 90 days.Flexible(TBA)_(2)MnBr4 films prepared as X-ray imaging scintillators exhibit a low detection limit of 63.3 nGyair/s,a high light yield of 68000 ph/MeV,and a high spatial resolution of 15.4 lp/mm.Thus,this work not only enriches the family of lead-free metal halides but also expands the application of manganese(II)-based halides in flexible X-ray scintillators.

In situ surface engineering enables high interface stability and rapid reaction kinetics for Ni-rich cathodes

Layered oxide cathodes with high Ni content promise high energy density and competitive cost for Li-ion batteries(LIBs).However,Ni-rich cathodes suffer from irreversible interface reconstruction and undesirable cracking with severe performance degradation upon long-term operation,especially at elevated temperatures.Herein,we demonstrate in situ surface engineering of Ni-rich cathodes to construct a dual ion/electron-conductive NiTiO 3 coating layer and Ti gradient doping(NC90–Ti@NTO)in parallel.The dual-modification synergy helps to build a thin,robust cathode–electrolyte interface with rapid Li-ion transport and enhanced reaction kinetics,and effec-tively prevents unfavorable crystalline phase transformation during long-term cycling under harsh environments.The optimized NC90–Ti@NTO delivers a high reversible capacity of 221.0 mAh g^(-1) at 0.1C and 158.9 mAh g^(-1) at 10C.Impressively,it exhibits a capacity retention of 88.4%at 25?C after 500 cycles and 90.7%at 55?C after 300 cycles in a pouch-type full battery.This finding provides viable clues for stabilizing the lattice and interfacial chemistry of Ni-rich cathodes to achieve durable LIBs with high energy density.

Construction of amorphous/crystalline heterointerfaces for enhanced electrochemical processes

Amorphous nanomaterials have emerged as potential candidates for energy storage and conversion owing to their amazing physicochemical properties.Recent studies have proved that the manipulation of amorphous nanomaterials can further enhance electrochemical performance.To date,various feasible strategies have been proposed,of which amorphous/crystalline(a-c)heterointerface engineering is deemed an effective approach to break through the inherent activity limitations of electrode materials.The following review discusses recent research progress on a-c heterointerfaces for enhanced electrochemical processes.The general strategies for synthesizing ac heterojunctions are first summarized.Subsequently,we highlight various advanced applications of a-c heterointerfaces in the field of electrochemistry,including for supercapacitors,batteries,and electrocatalysts.We also elucidate the synergistic mechanism of the crystalline phase and amorphous phase for electrochemical processes.Lastly,we summarize the challenges,present our personal opinions,and offer a critical perspective on the further development of a-c nanomaterials.

Heterostructure engineering in electrode materials for sodium-ion batteries:Recent progress and perspectives

Sodium-ion batteries(SIBs)have stepped into the spotlight as a promising alternative to lithium-ion batteries for large-scale energy storage systems.However,SIB electrode materials,in general,have inferior performance than their lithium counterparts because Nat is larger and heavier than Lit.Heterostructure engineering is a promising strategy to overcome this intrinsic limitation and achieve practical SIBs.We provide a brief review of recent progress in heterostructure engineering of electrode materials and research on how the phase interface influences Nat storage and transport properties.Efficient strategies for the design and fabrication of heterostructures(in situ methods)are discussed,with a focus on the heterostructure formation mechanism.The heterostructure's influence on Nat storage and transport properties arises primarily from local distortions of the structure and chemomechanical coupling at the phase interface,which may accelerate ion/electron diffusion,create additional active sites,and bolster structural stability.Finally,we offer our perspectives on the existing challenges,knowledge gaps,and opportunities for the advancement of heterostructure engineering as a means to develop practical,highperformance sodium-ion batteries.

Electrolyte design principles for low-temperature lithium-ion batteries

Alongside the pursuit of high energy density and long service life,the urgent demand for low-temperature performance remains a long-standing challenge for a wide range of Li-ion battery applications,such as electric vehicles,portable electronics,large-scale grid systems,and special space/seabed/military purposes.Current Li-ion batteries suffer a major loss of capacity and power and fail to operate normally when the temperature decreases to-20℃.This deterioration is mainly attributed to poor Li-ion transport in a bulk carbonated ester electrolyte and its derived solid–electrolyte interphase(SEI).In this mini-review discussing the limiting factors in the Li-ion diffusion process,we propose three basic requirements when formulating electrolytes for low-temperature Liion batteries:low melting point,poor Liþaffinity,and a favorable SEI.Then,we briefly review emerging progress,including liquefied gas electrolytes,weakly solvating electrolytes,and localized high-concentration electrolytes.The proposed novel electrolytes effectively improve the reaction kinetics via accelerating Li-ion diffusion in the bulk electrolyte and interphase.The final part of the paper addresses future challenges and offers perspectives on electrolyte designs for low-temperature Li-ion batteries.

Micro/nano metal–organic frameworks meet energy chemistry: A review of materials synthesis and applications

Micro/nano metal–organic frameworks(MOFs)have attracted significant attention in recent years due to their numerous unique properties,with many synthetic methods and strategies being reported for constructing MOFs with specific micro/nano structures.In addition,the design of micro/nano MOFs for energy storage and conversion applications and the study of the structure–activity relationship have also become research hotspots.Herein,a comprehensive overview of the recent progress on micro/nano MOFs is presented.We begin with a brief introduction to the various synthesis methods for controlling the morphology of micro/nano MOFs.Subsequently,the structure-dependent properties of micro/nano MOFs as electrode materials or catalysts in terms of batteries,supercapacitors,and catalysis are discussed.Finally,the remaining challenges and future perspectives in this field are presented.Overall,this review is expected to inspire the design of advanced micro/nano MOFs for efficient energy storage and conversion technologies.

CO electroreduction:What can we learn from its parent reaction,CO_(2) electroreduction?

The CO electroreduction reaction(CORR)represents an important piece of the decarbonization puzzle and is heavily inspired by research on the CO_(2) electroreduction reaction(CO_(2)RR).Compared to its parent reaction,CORR circumvents the(bi)carbonate issue that plagues CO_(2)RR,potentially enabling greater stability and selectivity toward C2þproducts,particularly oxygenates.Despite its unique potential,CORR still suffers from unsatisfactory performance.In this perspective article,we aim to provide a concise and informative overview of CORR and its close connection with CO_(2)RR.We start by briefly presenting the two reactions’similarities and differences,then discussing several catalyst design strategies.This is followed by highlights of the latest results on device integration and engineering.Finally,we offer our thoughts about possible future research opportunities that could render this technology a practical reality.

The role of machine learning in carbon neutrality:Catalyst property prediction,design,and synthesis for carbon dioxide reduction

Achieving carbon neutrality is an essential part of responding to climate change caused by the deforestation and over-exploitation of natural resources that have accompanied the development of human society.The carbon dioxide reduction reaction(CO_(2)RR)is a promising strategy to capture and convert carbon dioxide(CO_(2))into value-added chemical products.However,the traditional trial-and-error method makes it expensive and time-consuming to understand the deeper mechanism behind the reaction,discover novel catalysts with superior performance and lower cost,and determine optimal support structures and electrolytes for the CO_(2)RR.Emerging machine learning(ML)techniques provide an opportunity to integrate material science and artificial intelligence,which would enable chemists to extract the implicit knowledge behind data,be guided by the insights thereby gained,and be freed from performing repetitive experiments.In this perspective article,we focus on recent ad-vancements in ML-participated CO_(2)RR applications.After a brief introduction to ML techniques and the CO_(2)RR,we first focus on ML-accelerated property prediction for potential CO_(2)RR catalysts.Then we explore ML-aided prediction of catalytic activity and selectivity.This is followed by a discussion about ML-guided catalyst and electrode design.Next,the potential application of ML-assisted experimental synthesis for the CO_(2)RR is discussed.

In situ construction of zinc-rich polymeric solid–electrolyte interface for high-performance zinc anode

With their excellent reliability and environmental friendliness,zinc-ion batteries(ZIBs)are regarded as potential energy storage technologies.Unfortunately,their poor cycling durability and low Coulombic effectiveness(CE),driven by dendritic growth and surface passivation on the Zn anode,severely restrict their commercialization.Herein,we describe the in situ construction of a Zn-rich polymeric solid–electrolyte interface(SEI)using poly-acrylic acid(PAA)as an electrolyte additive.On the one hand,the PAA SEI layer offers evenly distributed nucleation sites and promotes ion transport,hence suppressing dendrite growth.On the other hand,the SEI layer prevents direct contact between the Zn foil and the electrolyte,thus inhibiting side reactions.Additionally,the robust coordination of PAA with Zn^(2+)and the SEI layer's good adherence to the Zn foil provide long-term pro-tection to the Zn anode.As a result,symmetric cells and Zn/V_(2)O_(5)cells all deliver prolonged cycle life and superior electrochemical efficiency.

Solution sequential deposited organic photovoltaics:From morphology control to large-area modules

Organic optoelectronic materials enable cutting-edge,low-cost organic photodiodes,including organic solar cells(OSCs)for energy conversion and organic photodetectors(OPDs)for image sensors.The bulk heterojunction(BHJ)structure,derived by blending donor and acceptor materials in a single solution,has dominated in the construction of active layer,but its morphological evolution during film formation poses a great challenge for obtaining an ideal nanoscale morphology to maximize exciton dissociation and minimize nongeminate recom-bination.Solution sequential deposition(SSD)can deliver favorable p–i–n vertical component distribution with abundant donor/acceptor interfaces and relatively neat donor and acceptor phases near electrodes,making it highly promising for excellent device performance and long-term stability.Focusing on the p–i–n structure,this review provides a systematic retrospect on regulating this morphology in SSD by summarizing solvent selection and additive strategies.These methods have been successfully implemented to achieve well-defined morphology in ternary OSCs,all-polymer solar cells,and OPDs.To provide a practical perspective,comparative studies of device stability with BHJ and SSD film are also discussed,and we review influential progress in blade-coating techniques and large-area modules to shed light on industrial production.Finally,challenging issues are out-lined for further research toward eventual commercialization.

Electronic structure regulation of noble metal-free materials toward alkaline oxygen electrocatalysis

Developing highly efficient,inexpensive catalysts for oxygen electrocatalysis in alkaline electrolytes(i.e.,the oxygen reduction reaction(ORR)and the oxygen evolution reaction(OER))is essential for constructing advanced energy conversion techniques(such as electrolyzers,fuel cells,and metal–air batteries).Recent achievements in efficient noble metal-free ORR and OER catalysts make the replacement of conventional noble metal counterparts a realistic possibility.In particular,various electronic structure regulation strategies have been employed to endow these oxygen catalysts with attractive physicochemical properties and strong synergistic effects,providing significant fundamental understanding to advance in this direction.This review article summarizes recently developed electronic structure regulation strategies for three types of noble metal-free oxygen catalysts:transition metal compounds,single-atom catalysts,and metal-free catalysts.We begin by briefly presenting the basic ORR and OER reaction mechanisms,following this with an analysis of the fundamental relationship between electronic structure and intrinsic electrocatalytic activity for the three categories of catalysts.Subsequently,recent advances in electronic structure regulation strategies for noble metal-free ORR and OER catalysts are systematically dis-cussed.We conclude by summarizing the remaining challenges and presenting our outlook on the future for designing and synthesizing noble metal-free oxygen electrocatalysts.

Crystallographic engineering of Zn anodes for aqueous batteries

With their intrinsic safety and environmental benignity,aqueous Zn-ion batteries(ZIBs)have been considered the most appropriate candidates for replacing alkali metal systems.However,polycrystalline Zn anodes in aqueous environments still pose enormous issues,such as dendrite growth and side reactions.Although many efforts have been made to address these obstacles through interphase modification and electrolyte design,researchers have not been able to improve the inherent thermodynamic stability and ion deposition behavior of the Zn anode.It is imperative to understand and explore advanced anode construction methods from the perspective of crystallinity.This review delves into the feasibility of precisely regulating the crystallographic features of metallic zinc,examines the challenges and merits of reported strategies for fabricating textured zinc,and offers constructive suggestions for the large-scale production and commercial application of aqueous ZIBs.

Modulating single-molecule charge transport through external stimulus

Understanding and tuning charge transport over a single molecule is a fundamental topic in molecular electronics.Single-molecule junctions composed of individual molecules attached to two electrodes are the most common components built for single-molecule charge transport studies.During the past two decades,rapid technical and theoretical advances in single-molecule junctions have increased our understanding of the conductance properties and functions of molecular devices.In this perspective article,we introduce the basic principles of charge transport in single-molecule junctions,then give an overview of recent progress in modulating single-molecule transport through external stimuli such as electric field and potential,light,mechanical force,heat,and chemical environment.Lastly,we discuss challenges and offer views on future developments in molecular electronics.