Metal organic frameworks-based cathode materials for advanced Li-S batteries: A comprehensive review

Li-S batteries(LSBs)have been considering as new and promising energy storage systems because of the high theoretical energy density and low price.Nevertheless,their practical application is inhibited by several factors,including poor electrical conductivity of electrode materials,greatly volumetric variation,as well as the polysulfide formation upon the cycling.To address these problems,it is imperative to develop and design effective and suitable sulfur host anode materials.Metal organic frameworks(MOFs)-based cathode materials,possessing their good conductivity and easy morphology design,have been extensively studied and exhibited enormously potential in LSBs.In this review,a comprehensive overview of MOFs-based sulfur host materials is provided,including their electrochemical reaction mechanisms,related evaluation parameters,and their performances used in LSBs in the past few years.In particular,the recent advances using in-situ characterization technologies for investigating the electrochemical reaction mechanism in LSBs are presented and highlighted.Additionally,the challenges and prospects associated with future research on MOF-related sulfur host materials are discussed.It is anticipated to offer the guidance for the identification of suitable MOFs-based sulfur cathode materials for high-performance LSBs,thereby contributing for the achievement of a sustainable and renewable society.

Tailored ZnF_(2)/ZnS-rich interphase for reversible aqueous Zn batteries

The urgent need for highly safe and sustainable large-scale energy storage systems for residential buildings has led to research into aqueous zinc ion batteries.However,when zinc is used in aqueous zinc ion batteries,it suffers from severe irreversibility due to its low Coulombic efficiency,dendrite growth,and side reactions.To address these challenges,we take advantage of organic cation to induce trifluoromethanesulfonate decomposition to build zinc fluoride/zinc sulfide-rich solid electrolyte interphase(SEI)that not only can adapt to a high areal capacity of deposition/stripping disturbance but also adjust zinc ion deposition path to eliminate dendrite.As a result,the unique interface can promote the Zn battery to achieve excellent electrochemical performance:high levels of plating/stripping Coulombic efficiency(99.8%),stability life(6,600 h),and cumulative capacity(66,000 mAh·cm^(−2))at 68%zinc utilization(20 mAh·cm^(−2)).More importantly,the SEI significantly enhances the cyclability of full battery under limited Zn,lean electrolyte,and high areal capacity cathode conditions.

Electrocatalytic seawater splitting for hydrogen production:Recent progress and future prospects

Earth-abundant seawater resource has become an attractive candidate to produce hydrogen from electrolysis,which is of great significance to realize hydrogen economy and carbon neutrality.Nonetheless,developing highly active and stable electrocatalysts to meet the needs of highly effective seawater splitting is still challenging for the sluggish oxygen evolution dynamics and the existed competitive reaction of chlorine evolution reaction(CER).To this end,some newly-developed electrocatalysts with superior performance,such as noble metals,alloy,transition metals,oxides,carbides,nitrides,phosphides,and so on,have been synthesized for the seawater splitting in recent years.This review starts from the historical background and fundamental mechanisms,and summarizes the most recent progress in the development of seawater electrolysis technologies.Some existing issues in the process of seawater electrolysis are enumerated and the corresponded solutions are presented.The future of hydrogen production from seawater electrolysis,especially the design and synthesis of novel catalysts for seawater electrolysis,is prospected.

Interface engineering of Fe-Co_(3)N/CoP composite with N-doped C by using soybean:Fabrication of efficient electrocatalysts for oxygen evolution reaction

Soybean can serve as an efficient carbon and nitrogen source for in-situ fabrication of efficient composite electrocatalysts with conductive nitrogen-doped carbon(N-C)material.In this study,the iron-doped cobalt nitride/phosphide(Fe-Co_(3)N/CoP)nanosheet was composited with a conductive N-C material by using soybean as C and N source,as well as NH3 as additional nitrogen source.During the nitridation process of Fe-Co_(3)N,N-C bond was formed as a newly generated Co(Fe)-N-C active sites.Therefore,it fabricates a good microscopic contact interface between the catalyst and carbon material for charge transfer.Besides,the introduction of Fe-CoP by partially phosphating Fe-Co_(3)N further improved the OER activity due to the high catalytic activity of Co sites with high valence state.As a result,the obtained electrocatalyst exhibited overpotentials as low as 285 and 390 mV for supporting 10 and 100 mA/cm􀀀2 current densities.This work indicates that the design of materials with good interfaces could be an effective approach for the preparation of electrocatalysts for water electrolysis.

An organosulfide-based energetic liquid as the catholyte in highenergy density lithium metal batteries for large-scale grid energy storage

Development of catholytes with long-cycle lifespan,high interfacial stability,and fast electrochemical kinetics is crucial for the comprehensive deployment of high-energy density lithium metal batteries(LMBs)with cost-efficiency.In this study,a lithiated 2-mercaptopyridine(2-MP-Li)organosulfide was synthesized and used as the soluble catholyte for the first time.Under the routine working mode,the LMB using this 2-MP-Li catholyte possessed high capacity retention of 55.4%with a Coulombic efficiency(CE)of near 100%after 2,000 cycles.When a cell system was fully filled with 2-MP-Li catholyte,it yielded a double capacity with 15%improvement in the capacity retention,corresponding to 0.0182%capacity decay per cycle,as well as excellent rate performance even at 6 mA·cm^(−2).These superior achievements resulted from the enhanced interfacial stability of Li anode induced by the salt-type 2-MP-Li molecule and the avoiding of using neutral catholyte as the initial active material,thereby mitigating the side reactions originating from the polysulfide shuttle effect.Furthermore,density functional theory(DFT)calculation and kinetics investigations proved the pseudocapacitive characteristic and faster ion diffusion coefficient with this design.Besides,the fabricated energy storage device showed excellent performance but with low economic cost and easy processing.Such a LMB with an alterable amount of capacity has a high potential to be applied in flow-cell type batteries for large-scale grid energy storage in the future.

Fluoropyridine family:Bifunction as electrolyte solvent and additive to achieve dendrites-free lithium metal batteries

Electrolyte formulation with high stability towards both Li metal anode and high-voltage cathode is considered as one of key points for the high-energy density lithium metal batteries(LMBs).In our previous study,by adding only 2%of 2-fluoropyridine(2-FP)as the additive in the carbonate and ether-based electrolyte formulations effectively suppressed Li dendrite growth.In this study,we further found that the main fluoropyridine(FP)family members can serve as not only the effective additive but also the excellent electrolyte solvent in the electrolyte formulations to enhance the performance of LMBs.For the 2-FP,when it was also used the electrolyte solvent and paired with single-salt lithium bis(trifluoromethylsulfonyl)imide(Li TFSI),the obtained electrolyte formulation of 1 M Li TFSI in pure2-FP solvent not only allowed faster ion transport though solvation effect,but also possessed impressive oxidation stability window over 4.3 V.As a result,the high-voltage LiNi_(1/3)Mn1_(/3)Co_(1/3)O_(2)(1.5 mA h cm^(-2))|Li metal battery with it exhibited a capacity retention of more than 80%over a long-term cycle even at 0.45 m A cm^(-2)with a lean electrolyte(30μL).Meanwhile,for another FP family member(i.e.,3-FP)as the electrolyte additive,the 4.3 V LMBs with the carbonate-based electrolyte containing only 1%of 3-FP maintained 83.9%of initial capacity after 200 cycles at 0.75 m A cm^(-2).Density functional theory(DFT)calculations and experiments confirmed that three typical FPs,i.e.,2-FP,3-FP and 4-FP can not only regulate the initial Li nucleation process,but more importantly also induce a protective layer,leading to a uniform and dendrites-free Li deposition.This bifunction of the FP family member as either electrolyte solvent or additive in the electrolyte formulations should be promising for the achieving of dendrites-free high-energy density LMBs.