Insights into the nitride-regulated processes at the electrolyte/electrode interface in quasi-solid-state lithium metal batteries

Gel polymer electrolytes(GPEs)are one of the promising candidates for high-energy-density quasi-solid-state lithium metal batteries(QSSLMBs),for their high ionic conductivity and excellent interfacial compatibility.The comprehension of dynamic evolution and structure-reactivity correlation at the GPE/Li interface becomes significant.Here,in situ electrochemical atomic force microscopy(EC-AFM)provides insights into the LiNO_(3)-regulated micromechanism of the Li plating/stripping processes upon cycles in GPE-based LMBs at nanoscale.The additive LiNO_(3)induces the formation of amorphous nitride SEI film and facilitates Li^(+) ion diffusion.It stabilizes a compatible interface and regulates the Li nucleation/growth at steady kinetics.The deposited Li is in the shape of chunks and tightly compact.The Li dissolution shows favorable reversibility,which guarantees the cycling performance of LMBs.In situ AFM monitoring provides a deep understanding into the dynamic evolution of Li deposition/dissolution and the interphasial properties of tunable SEI film,regulating the rational design of electrolyte and optimizing interfacial establishment for GPE-based QSSLMBs.

TiN nanocrystal anchored on N-doped graphene as effective sulfur hosts for high-performance lithium-sulfur batteries

Lithium-sulfur(Li-S)batteries have become prospective candidates for next-generation energy storage owing to the high energy density and low cost.However,the sluggish kinetics of the electrochemical reaction and shuttle effect result in a rapid capacity decay.Herein,a titanium nitride nanocrystal/Ndoped graphene(TiN@NG)composite is developed to host elemental sulfur.The TiN nanoparticles decorated on graphene sheets attract Li polysulfides(LiPSx)and catalyze the electrochemical reduction and oxidation of LiPSx in the discharge and charge processes,respectively.These two effects effectively restrain the dissolution of the LiPSx and accelerate the electrochemical reactions,thereby,alleviating the shuttle effect.As a result,the cathode composed of TiN@NG/S delivers a remarkable reversible capacity(1390 mA h g^(-1) at 0.1 C)and excellent cycling performance(730 mA h g^(-1) after 300 cycles).We believe that this work can bring some inspiration for designing high-performance Li-S batteries.

Solid-state lithium-ion batteries for grid energy storage:opportunities and challenges

The energy crisis and environmental pollution drive more attention to the development and utilization of renewable energy.Considering the capricious nature of renewable energy resource,it has difficulty supplying electricity directly to consumers stably and efficiently,which calls for energy storage systems to collect energy and release electricity at peak periods.Due to their flexible power and energy,quick response,and high energy conversion efficiency,lithium-ion batteries stand out among multiple energy storage technologies and are rapidly deployed in the grid.Pursuing superior performance and ensuring the safety of energy storage systems,intrinsically safe solid-state electrolytes are expected as an ideal alternative to liquid electrolytes.In this review,we systematically evaluate the priorities and issues of traditional lithium-ion batteries in grid energy storage.Beyond lithium-ion batteries containing liquid electrolytes,solid-state lithium-ion batteries have the potential to play a more significant role in grid energy storage.The challenges of developing solid-state lithium-ion batteries,such as low ionic conductivity of the electrolyte,unstable electrode/electrolyte interface,and complicated fabrication process,are discussed in detail.Additionally,the safety of solid-state lithium-ion batteries is re-examined.Following the obtained insights,inspiring prospects for solid-state lithium-ion batteries in grid energy storage are depicted.

Roadmap for rechargeable batteries:present and beyond

Rechargeable batteries currently hold the largest share of the electrochemical energy storage market,and they play a major role in the sustainable energy transition and industrial decarbonization to respond to global climate change.Due to the increased popularity of consumer electronics and electric vehicles,lithium-ion batteries have quickly become the most successful rechargeable batteries in the past three decades,yet growing demands in diversified application scenarios call for new types of rechargeable batteries.Tremendous efforts are made to developing the next-generation post-Li-ion rechargeable batteries,which include,but are not limited to solid-state batteries,lithium–sulfur batteries,sodium-/potassium-ion batteries,organic batteries,magnesium-/zinc-ion batteries,aqueous batteries and flow batteries.Despite the great achievements,challenges persist in precise understandings about the electrochemical reaction and charge transfer process,and optimal design of key materials and interfaces in a battery.This roadmap tends to provide an overview about the current research progress,key challenges and future prospects of various types of rechargeable batteries.New computational methods for materials development,and characterization techniques will also be discussed as they play an important role in battery research.

Preface:special topic on rechargeable battery technology

Rechargeable batteries play a major role in the transition from fossil energy to renewable energy and are considered the key-enabling decarbonization technology for several industries,including electronics,transportation,and future-oriented artificial intelligence and aerospace,in response to global climate change.

Template-free synthesis of hollow carbon-based nanostructures from MOFs for rechargeable battery applications

Hollow carbon-based nanostructures(HCNs)have found broad applications in various fields,particularly rechargeable batteries.However,the syntheses of HCNs usually rely on template methods,which are time-consuming,low-yield,and environmentally detrimental.Metal-organic frameworks(MOFs),constructed by organic ligands and inorganic metal nodes,have been identified as effective platforms for preparing HCNs without adding extra templates.This review summarized the recent progress in template-free synthesis of HCNs enabled by MOFs and their applications in rechargeable batteries.Different template-free strategies were introduced first with mechanistic insights into the hollowing mechanism.Then the electrochemical performances of the HCNs were discussed with highlight on the structure-function correlation.It is found that the built-in cavities and nonporous for HCNs is of critical importance to increase the storage sites for high capacity,to enhance charge and mass transport kinetics for high-rate capability,and to ensure the resilient electrode structure for stable cycling.Finally,the challenges and opportunities regarding MOFs-derived HCNs and their applications in rechargeable batteries were discussed.

Structural Restoration of Degraded LiFePO_(4)Cathode with Enhanced Kinetics Using Residual Lithium in Spent Graphite Anodes

Enormous LiFePO_(4)(LFP)/graphite batteries retired from the market need urgent rational disposal and reutilization based on the degradation analysis of the evolutional mechanism for electrodes.Typically,Li inventory loss is one of the main reasons for the degradation of LFP-based batteries.The reduced portion of lithium in a cathode is inevitably consumed to form solid electrolyte interphase or trapped in the anode.Herein,we propose a comprehensive strategy for battery recycling and conduct the work by simply regenerating the degraded LFP materials directly with the extracted lithium compounds from spent anodes.Moreover,inter-particle three-dimensional(3D)conductive networks are built via an in situ carbonization to reinforce the electronic conductivity of regenerated cathodes.An improved electrochemical performance was achieved in the regenerated LFP materials even compared with the pristine LFP.This integrated recycling strategy not only brings more added value to the recycled materials by leveraging the recycling process but also aims to apply the concept of“treating waste with waste”and spur innovations in battery recycling technologies in the future.

In situ analysis of dynamic evolution of the additive-regulated cathode processes in quasi-solid-state lithium-metal batteries

The implementation of high-energy-density storage devices can be facilitated by the built-in situ cathode electrolyte interphase(CEI)between Ni-rich cathodes and gel polymer electrolytes,as it improves interfacial compatibility and enhances security.Understanding the interphase processes of cathode materials,including the structural evolution and the formation of cathode electrolyte interphase upon charging/discharging,is crucial for the design of solid-state lithium batteries.Here,we employed in situ atomic force microscopy(AFM)to investigate the effects of lithium difluoro(oxalato)borate(Li DFOB)on the dynamic evolution of the cathode interphase.In the presence of Li DFOB,the adhesion of nanoparticles and a thin amorphous film on the cathode surface resulted in the formation of a homogeneous CEI,inducing the production of LixPFyas byproducts.Furthermore,the stable CEI formed between the cathode and electrolyte helps maintain the integrity of the composition and structure,reduces interfacial resistance,and improves the cycle stability of the batteries.The visualization of in situ AFM in quasi-solid-state lithium-metal batteries provides valuable insights into the distinct nanostructures and growth dynamics of Li DFOB-mediated CEI on the LiNi_(6)Co_(2)Mn_(2)O_(2) cathode,thus offering a universal and convenient technique for interfacial analysis and a mechanistic understanding of solid-state batteries.

Stable 4.5 V LiCoO_(2)cathode material enabled by surface manganese oxides nanoshell

Charging the LiCoO_(2)(LCO)cathode to a higher voltage,for example 4.5 V compared to the commonly used 4.2 V,is now intensively pursued so as to achieve a higher specific capacity.However,it suffers severe surface structural degradation and detrimental interfacial side reactions between cathode and electrolyte,which lead to the fast capacity fading during long-term cycling.Here,a surface coating strategy was developed for the protection of 4.5 V LCO by constructing a manganese oxides(MOs)nanoshell around LCO particles,which was achieved through a solution-based coating process with success in controlling the growth kinetics of the coating species.We found that the introduction of the MOs nanoshell is highly effective in alleviating the organic electrolyte decomposition at the cathode surface,thus ensuring a much more stable LiF-rich cathode-electrolyte interface and an obvious lower interfacial resistance during electrochemical cycling.Meanwhile,this protection layer can effectively improve the structural stability of the cathode by hindering the cracks formation and structural degradation of LCO particles.Therefore,the MOs modified LCO exhibited excellent rate performance and a high discharge capacity retention of 81.5%after 100 cycles at 1 C compared with the untreated LCO(55.2%),as well as the improved thermal stability and cyclability at the elevated temperature.It is expected that this discovery and fundamental understanding of the surface chemistry regulation strategy provide promising insights into improving the reversibility and stability of LCO cathode at the cut-off voltage of 4.5 V.

Preface:special issue in honor of Professor Lixin Dai on the occasion of his 100th birthday

Prof.Lixin Dai,a luminary in the field of chemistry,was born in Beijing on November 13,1924.His remarkable journey through the world of science began at Beijing Yuying Middle School in 1936 and continued as he pursued his secondary education in Shanghai.In 1942,he embarked on his academic path by enrolling in the Department of Chemistry at the University of Shanghai.In the next year,he transferred to Zhejiang University in Guizhou Province.

Unveiling the future of chemistry:the 2023 emerging investigator issue of Science China Chemistry

In the dynamic realm of scientific discovery,it is imperative to acknowledge and support the innovative perspectives and groundbreaking research emanating from the next generation of leaders in our field.To this end,Science China Chemistry(SCC)has organized three Emerging Investigator Issues since 2020[1–3].

Porous organic polymers: a progress report in China

Porous organic polymers(POPs) are porous materials composed of light elements such as C, H, N, and O. The benign characters,including large surface area, good physical and chemical stability, well-defined chemical composition, wide ranges of monomer selection, and strong designability, have made POPs one of the frontiers in materials research. In this review, we discussed the design and synthesis of various POP materials that mainly led by Chinese scientists, including conjugated microporous polymers(CMPs), porous aromatic frameworks(PAFs), and hypercrosslinked porous polymers(HCPs), as well as crystalline POPs comprised of covalent organic frameworks(COFs) and a special class of COFs with triazine rings, covalent triazine frameworks(CTFs), and supramolecular organic frameworks(SOFs), and sorted out their main applications in adsorption, separation,catalysis, and electrochemistry fields.

Designing solid-state interfaces on lithium-metal anodes: a review

Li-metal anodes are one of the most promising energy storage systems that can considerably exceed the current technology to meet the ever-increasing demand of power applications. The apparent cycling performances and dendrite challenges of Li-metal anodes are highly influenced by the interface layer on the Li-metal anode because the intrinsic high reactivity of metallic Li results in an inevitable solid-state interface layer between the Li-metal and electrolytes. In this review, we summarize the recent progress on the interfacial chemistry regarding the interactions between electrolytes and ion migration through dynamic interfaces. The critical factors that affect the interface formation for constructing a stable interface with a low resistance are reviewed. Moreover, we review emerging strategies for rationally designing multiple-structured solid-state electrolytes and their interfaces, including the interfacial properties within hybrid electrolytes and the solid electrolyte/electrode interface. Finally, we present scientific issues and perspectives associated with Li-metal anode interfaces toward a practical Li-metal battery.

Improving the stability of LiNi_(0.80)Co_(0.15)Al_(0.05)O_2 by AlPO_4 nanocoating for lithium-ion batteries

Nickel-rich layered materials,such as LiNi_(0.8)0Co_(0.15)Al_(0.05)O_2(NCA),have been considered as one alternative cathode materials for lithium-ion batteries(LIBs) due to their high capacity and low cost.However,their poor cycle life and low thermal stability,caused by the electrode/electrolyte side reaction,prohibit their prosperity in practical application.Herein,AlPO4 has been homogeneously coated on the surface of NCA via wet chemical method towards the target of protecting NCA from the attack of electrolyte.Compared with the bare NCA,NCA@AlPO_4 electrode delivers high capacity without sacrificing the discharge capacity and excellent cycling stability.After 150 cycles at 0.5 C between 3.0-4.3 V,the capacity retention of the coated material is 86.9%,much higher than that of bare NCA(66.8%).Furthermore,the thermal stability of cathode is much improved due to the protection of the uniform coating layer on the surface of NCA.These results suggest that AlPO4 coated NCA materials could act as one promising candidate for next-generation LIBs with high energy density in the near future.

In-situ nanoscale insights into the evolution of solid electrolyte interphase shells:revealing interfacial degradation in lithium metal batteries

The solid electrolyte interphase(SEI)has caught considerable attention as a pivotal factor affecting lithium(Li)metal battery performances.However,the understanding of the interfacial evolution and properties of the on-site formed SEI shells on Li deposits during cycling is still at a preliminary stage.Here,we provide a straightforward visualized evidence of SEI shells’evolution during Li deposition/stripping to reveal anode degradation via in-situ atomic force microscopy(AFM).Nucleation and growth of quasi-spherical Li particles are observed on a Cu substrate,followed by Li stripping and collapse of SEI shells.In the subsequent cycling,new Li deposits tend to nucleate at pristine sites with fresh SEI shells forming on Li.The previously collapsed SEI shells accumulate to increase interface impedance,eventually leading to capacity degradation.Revealing the electrochemical processes and interfacial degradation at the nanoscale will enrich fundamental comprehension and further guide improvement strategies of Li metal anodes.

Advanced transition metal/nitrogen/carbon-based electrocatalysts for fuel cell applications

The development of advanced transition metal/nitrogen/carbon-based(M/N/C)catalysts with high activity and extended durability for oxygen reduction reaction(ORR)is critical for platinum-group-metal(PGM)free fuel cells but still remains great challenging.In this review,we summarize the recent progress in two typical M/N/C catalysts(atomically dispersed metal-nitrogen-carbon(M-N-C)catalysts and carbon-supported metal nanoparticles with N-doped carbon shells(M@NC))with an emphasis on their potential applications in fuel cells.Starting with understanding the active sites in these two types of catalysts,the representative innovative strategies for enhancing their intrinsic activity and increasing the density of these sites are systematically introduced.The synergistic effects of M-N-C and M@NC are subsequently discussed for those M/N/C catalysts combining both of them.To translate the material-level catalyst performance into high-performance devices,we also include the recent progress in engineering the porous structure and durability of M/N/C catalysts towards efficient performance in fuel cell devices.From the viewpoint of industrial applications,the scale-up cost-effective synthesis of M/N/C catalysts has been lastly briefed.With this knowledge,the challenges and perspectives in designing advanced M/N/C catalysts for potential PGM-free fuel cells are proposed.

Facile synthesis of hollow Ti2Nb10O29 microspheres for high-rate anode of Li-ion batteries

Titanium niobium oxides emerge as promising anode materials with potential for applications in lithium ion batteries with high safety and high energy density.However,the innate low electronic conductivity of such a composite oxide seriously limits its practical capacity,which becomes a serious concern especially when a high rate charge/discharge capability is expected.Here,using a modified template-assisted synthesis protocol,which features an in-situ entrapment of both titanium and niobium species during the formation of polymeric microsphere followed by a pyrolysis process,we succeed in preparing hollow microspheres of titanium niobium oxide with high efficiency in structural control.When used as an anode material,the structurally-controlled hollow sample delivers high reversible capacity(103.7 m A h g^(-1)at 50 C)and extraordinary cycling capability especially at high charge/discharge currents(164.7 m A h g^(-1)after 500 cycles at 10 C).

Redistribution of Li-ions using covalent organic frameworks towards dendrite-free lithium anodes:a mechanism based on a Galton Board

Because of its high theoretical specific capacity and low reduction potential,Li metal is considered to be key to reaching high energy density in rechargeable batteries.In this context,most of the research has focused on suppressing dendrite formation during Li deposition to improve the cycling reversibility and safety of the batteries.Here,covalent organic framework(COF)film coating on a commercial polypropylene separator is applied as an ion redistributor to eliminate Li dendrites.The COF crystallites consist of ordered nanochannels that hinder the movement of anions while allowing Li-ions to transport across,leading to a high Li-ion transference number of 0.77±0.01.The transport of Li-ions across the COF film can be considered to be analogous to beads passing through a Galton Board,a model that demonstrates a statistical concept of a normal distribution.Thus,an even distribution of Li-ions is obtained at the COF/Li metal interface.The controlled Li-ion flux yields a smooth Li metal surface after 1,000 h(500 times)of cycling,leading to a significantly improved cycling stability and reversibility,as demonstrated by Cu||Li half cells,Li||Li symmetric cells,and Li Fe PO4||Li full cells.These results suggest that,following the principle of a Galton Board,nanopore insulators such as COF-based materials are effective ion distributors for the different energy storage or conversion systems.

Monitoring the mechanical properties of the solid electrolyte interphase(SEI)using electrochemical quartz crystal microbalance with dissipation

Stable solid electrolyte interphase(SEI)has been well established to be critical for the reversible operation of Li(ion)batteries,yet our understanding of its mechanical properties currently remains incomplete.Here,we used an electrochemical quartz crystal microbalance combined with dissipation monitoring(EQCM-D)to investigate SEI formation.By quantitatively estimating in-situ,the change in mass,shear modulus,and viscosity of the SEI,we show that the SEI formation in propylene carbonate(PC)-and ethylene carbonate/diethyl carbonate(EC/DEC)-based electrolytes involves the growth of a rigid laye r followed by a viscoelastic layer,whereas a distinct"one-layer"rigid model is applicable to the SEI formulated in tetraethylene glycol dimethyl ether(TEGDME)-based electrolyte.With the continuous formation of the SEI,its shear modulus decreases accompanied by an increase in viscosity.In TEGDME,the lightest/thinnest SEI(mass lower than in PC by a factor of nine)yet having the greatest stiffness(more than five times that in PC)is obtained.We attribute this behavior to differences in the chemical composition of the SEIs,which have been revealed by tracking the mass-change-per-mole-of-electrontransferred using EQCM-D and further confirmed by X-ray photoelectron spectroscopy.

Structurally modulated Li-rich cathode materials through cooperative cation doping and anion hybridization

High capacity Li-rich materials are mighty contenders for building rechargeable batteries that coincide with the demand in energy density. Fully realizing the extraordinary capacity involves oxygen evolution and related cation migration, resulting in phase transitions and deteriorations that would hinder their practical application. In an attempt to enhance the anodic redox participation and stabilize the structure at the same time, we proposed a structural modulation strategy with modification on anion hybridization intensifying and cation doping. Spectator ions with large ionic radius were introduced into the lattice during calcination with stannous chloride and the d-p hybridization between transition metal 3 d and oxygen 2 p orbitals was subsequently intensified along with expelling weakly bonded chloride species in the reheating process. Both of the reversible capacity and stability upon cycling were remarkably improved through the cooperation of bond alteration and dopant. This strategy might provide new insight into the modulation of the structure to truly fulfill the potential of Li-rich materials.