由于钠资源丰富且成本低廉,钠离子电池(SIBs)有望成为解决可再生能源存储与分配难题的储能器件,开发高性能正极材料是SIBs实现产业化应用的关键。磷酸铁钠(NaFePO_(4))具有成本低廉和安全性好等优点,受到人们的广泛关注。然而,Na+半径...由于钠资源丰富且成本低廉,钠离子电池(SIBs)有望成为解决可再生能源存储与分配难题的储能器件,开发高性能正极材料是SIBs实现产业化应用的关键。磷酸铁钠(NaFePO_(4))具有成本低廉和安全性好等优点,受到人们的广泛关注。然而,Na+半径相对较大,导致其扩散动力学较慢,致使NaFePO_(4)倍率性能较差,限制了其进一步应用。本文通过调控LiFePO4脱锂电压进行电化学嵌钠,成功合成出NaFePO_(4)材料。结果表明,当脱锂电压为4.4 V,通过电化学嵌钠合成出的NaFePO_(4)材料在25℃、0.5 C(1 C=154 mAh g^(-1))下循环50次后仍然具有78.23 mAh g^(-1)的放电比容量,容量保持率高达96.97%。同时,其在2 C的倍率下仍然具有62.98 mAh g^(-1)的放电比容量。脱锂电压为4.4 V时有效提高了NaFePO_(4)材料的晶格间距,利于Na+的脱嵌,从而在一定程度上提高了NaFePO_(4)材料的倍率性能。钠离子电池正极材料的研究对于缓解锂资源稀缺问题以及提高电池性能都具有重要的意义。展开更多
Ceramic cells promise ideal energy conversion and storage devices,making the development of efficient and robust air electrodes crucial for their application.In this study,a Ba_(0.4)Sr_(0.5)Cs_(0.1)Co_(0.7)Fe_(0.2)Nb_...Ceramic cells promise ideal energy conversion and storage devices,making the development of efficient and robust air electrodes crucial for their application.In this study,a Ba_(0.4)Sr_(0.5)Cs_(0.1)Co_(0.7)Fe_(0.2)Nb_(0.1)O_(3−δ)(BSCCFN)air electrode,based on Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3−δ)(BSCF),is designed using a perovskite A-B-site ionic Lewis acid strength(ISA)polarization distribution strategy and is successfully applied in both oxygen-ion conducting solid oxide fuel cells(O-SOFCs)and proton-conducting reversible protonic ceramic cells(R-PCCs).When BSCCFN is used as the air electrode in O-SOFCs,a peak power density(PPD)of 1.45 W cm^(−2)is achieved at 650°C,whereas in R-PCCs,a PPD of 1.13 W cm^(−2)and a current density of−1.8 A cm^(−2)at 1.3 V are achieved at the same temperature and show stable reversibility over 100 h.Experimental measurements and theoretical calculations demonstrate that low-ISA Cs+doping accelerates the reaction kinetics of both oxygen ions and protons,while high-ISA Nb^(5+)doping enhances electrode stability.The synergistic effect of Cs^(+)and Nb^(5+)co-doping in the BSCCFN electrode lies in the ISA polarization distribution,which weakens the Co/Fe–O bond covalency,thereby promoting oxygen vacancy formation and facilitating the conduction of oxygen ions and protons.展开更多
The deployment of flexible zinc-ion batteries is impeded by dendrite growth from random anode defects.Conventional defect-elimination strategies often compromise flexibility and fail to achieve uniform interfaces.We p...The deployment of flexible zinc-ion batteries is impeded by dendrite growth from random anode defects.Conventional defect-elimination strategies often compromise flexibility and fail to achieve uniform interfaces.We propose a paradigm shift:reconfiguring random defects into engineered,monodisperse artificial micro-curves to homogenize electric fields and guide aligned zinc(Zn)deposition.Using moisture-assisted flash heating,we transform zincophilic silver(Ag)coatings on carbon fibers into uniformly dispersed micro-curved particles(Ag Particles@CC),creating identical nucleation sites with optimal zinc ion(Zn^(2+))adsorption energetics.Theoretical simulations confirm these structures eliminate localized field concentrations,enabling homogeneous plating/stripping.This design demonstrates remarkable performance,with ultrastable 1500 cycles at 10 mA cm^(-2)(98.6%avg.Coulombic efficiency)and symmetric cell operation>650 h(57.7 mV hysteresis).Crucially,interparticle discontinuities preserve intrinsic flexibility,enabling flexible pouch cells(Ag Particles@CC-Zn//NaV_(3)O_(8)·1,5H_(2)O)to successfully power wearable devices such as smartwatches and smartphones.This work establishes defect reconfiguration via artificial micro-curvature engineering as a universal strategy toward dendritesuppressed,flexible energy storage.展开更多
Layered oxides have attracted significant attention as cathodes for sodium-ion batteries(SIBs)due to their compositional versatility and tuneable electrochemical performance.However,these materials still face challeng...Layered oxides have attracted significant attention as cathodes for sodium-ion batteries(SIBs)due to their compositional versatility and tuneable electrochemical performance.However,these materials still face challenges such as structural phase transitions,Na^(+)/vacancy ordering,and Jahn–Teller distortion effect,resulting in severe capacity decay and sluggish ion kinetics.We develop a novel Cu/Y dual-doping strategy that leads to the formation of"Na–Y"interlayer aggregates,which act as structural pillars within alkali metal layers,enhancing structural stability and disrupting the ordered arrangement of Na^(+)/vacancies.This disruption leads to a unique coexistence of ordered and disordered Na^(+)/vacancy states with near-zero strain,which significantly improves Na^(+)diffusion kinetics.This structural innovation not only mitigates the unfavorable P2–O2 phase transition but also facilitates rapid ion transport.As a result,the doped material demonstrates exceptional electrochemical performance,including an ultra-long cycle life of 3000 cycles at 10 C and an outstanding high-rate capability of~70 mAh g^(−1)at 50 C.The discovery of this novel interlayer pillar,along with its role in modulating Na^(+)/vacancy arrangements,provides a fresh perspective on engineering layered oxides.It opens up promising new pathways for the structural design of advanced cathode materials toward efficient,stable,and high-rate SIBs.展开更多
To enhance the electrochemical performance of lithium-ion battery anodes with higher silicon content,it is essential to engineer their microstructure for better lithium-ion transport and mitigated volume change as wel...To enhance the electrochemical performance of lithium-ion battery anodes with higher silicon content,it is essential to engineer their microstructure for better lithium-ion transport and mitigated volume change as well.Herein,we suggest an effective approach to control the micropore structure of silicon oxide(SiO_(x))/artificial graphite(AG)composite electrodes using a perforated current collector.The electrode features a unique pore structure,where alternating high-porosity domains and low-porosity domains markedly reduce overall electrode resistance,leading to a 20%improvement in rate capability at a 5C-rate discharge condition.Using microstructure-resolved modeling and simulations,we demonstrate that the patterned micropore structure enhances lithium-ion transport,mitigating the electrolyte concentration gradient of lithium-ion.Additionally,perforating current collector with a chemical etching process increases the number of hydrogen bonding sites and enlarges the interface with the SiO_(x)/AG composite electrode,significantly improving adhesion strength.This,in turn,suppresses mechanical degradation and leads to a 50%higher capacity retention.Thus,regularly arranged micropore structure enabled by the perforated current collector successfully improves both rate capability and cycle life in SiO_(x)/AG composite electrodes,providing valuable insights into electrode engineering.展开更多
Controllable synthesis of ultrathin metallene nanosheets and rational design of their spatial arrangement in favor of electrochemical catalysis are critical for their renewable energy applications.Here,a biomimetic de...Controllable synthesis of ultrathin metallene nanosheets and rational design of their spatial arrangement in favor of electrochemical catalysis are critical for their renewable energy applications.Here,a biomimetic design of“Trunk-Branch-Leaf”strategy is proposed to prepare the ultrathin edge-riched Zn-ene“leaves”with a thickness of~2.5 nm,adjacent Zn-ene cross-linked with each other,which are supported by copper nanoneedle“branches”on copper mesh“trunks,”named as Zn-ene/Cu-CM.The resulting superstructure enables the formation of an interconnected network and multiple channels,which can be used as an electrocatalytic CO_(2) reduction reaction(CO_(2)RR)electrode to allow a fast charge and mass transfer as well as a large electrolyte reservoir.By virtue of the distinctive structure,the obtained Zn-ene/Cu-CM electrode exhibits excellent selectivity and activity toward CO production with a maximum Faradaic efficiency of 91.3%and incredible partial current density up to 40 mA cm^(−2),outperforming most of the state-of-the-art Zn-based electrodes for CO_(2) reduction.The phenolphthalein color probe combined with in situ attenuated total reflection-infrared spectroscopy uncovered the formation of the localized pseudo-alkaline microenvironment at the interface of the Zn-ene/Cu-CM electrode.Theoretical calculations confirmed that the localized pH as the origin is responsible for the adsorption of CO_(2) at the interface and the generation of *COOH and *CO intermediates.This study offers valuable insights into developing efficient electrodes through synergistic regulation of reaction microenvironments and active sites,thereby facilitating the electrolysis of practical CO_(2) conversion.展开更多
The rapid expansion of the photovoltaic industry has generated heavily oxidized waste silicon(wSi),which hinders efficient recycling owing to its small particle size and uncontrolled surface oxidation.This study intro...The rapid expansion of the photovoltaic industry has generated heavily oxidized waste silicon(wSi),which hinders efficient recycling owing to its small particle size and uncontrolled surface oxidation.This study introduces a molten salt electrochemical strategy for converting photovoltaic wSi into NiSi_(2)-silicon nanorods(NiSi_(2)-SiNRs)as high-performance anode materials for lithium-ion batteries.A stable oxidized passivation layer is formed on the wSi surface via controlled oxidation,and further in situ generated highly active NiSi_(2) droplets.The molten salt electric field modulates the surface energy of silicon,while particle integration drives localized directional growth,enabling the self-assembly of NiSi_(2)-SiNRs composites.These NiSi_(2)-SiNRs anodes exhibit rapid ion transport and effective strain buffering.The high aspect ratio of SiNRs and the presence of retained NiSi_(2) facilitate both longitudinal and transverse Li^(+) diffusion.Owing to their robust structural design,the NiSi_(2)-SiNRs anode achieves an excellent initial Coulombic efficiency of 91.61%and retains 72.99%of its capacity after 800 cycles at 2 A·g^(−1).This study establishes a model system for investigating silicide/silicon interfaces in molten salt electrochemical synthesis and provides an effective strategy for upcycling photovoltaic wSi into high-performance lithium-ion battery anodes.展开更多
Zinc-iodine(Zn-I_(2))batteries are deemed as potential candidate of energy storage system for the merits of high safety,cost-effectiveness,high capacity,and environmental compatibility.Unfortunately,the practical impl...Zinc-iodine(Zn-I_(2))batteries are deemed as potential candidate of energy storage system for the merits of high safety,cost-effectiveness,high capacity,and environmental compatibility.Unfortunately,the practical implementation of Zn-I_(2)batteries is still hindered by the sluggish iodine redox kinetics and the shuttle effect of soluble polyiodides,which induce rapid capacity decay and electrode interface passivation.This work proposes platinum/carbon(Pt/C)and iridium/carbon(Ir/C)composite as conductive catalytic iodine hosts,which realizes the physical confinement for active iodine through the intrinsic porous structure.The introduction of active Pt/Ir sites effectively anchors the polyiodides through chemical adsorption capability,and inhibits shuttle effect and Zn metal corrosion.In addition,the superior electrical conductivity and catalytic activity of Pt/C and Ir/C carriers also contribute to reduce the reaction energy barriers,significantly promoting the electrochemical performance and conversion reaction kinetics.As expected,the assembled Zn//Pt/C@I_(2)and Zn//Ir/C@I_(2)batteries achieve impressive reversible capacity of 132.2 and 108 mAh g^(-1)after 2000 cycles at 200 mA g^(-1),respectively,and their capacity retention rate after 25000 cycles at 1000 mA g^(-1)are as high as 88.1%and 85.9%.This study will guide the carrier design of iodine cathode to drive the application of high-performance Zn-I2batteries.展开更多
High-capacity O3-type layered NiFeMn-based oxides are promising cathodes for sodium-ion batteries,though their practical deployment is constrained by the inherent limitations of Fe redox chemistry.Traditional designs ...High-capacity O3-type layered NiFeMn-based oxides are promising cathodes for sodium-ion batteries,though their practical deployment is constrained by the inherent limitations of Fe redox chemistry.Traditional designs generally enforcing stoichiometric symmetry(Ni=Mn)yield low Fe redox activity.Herein,we propose a valence engineering strategy that breaks conventional Ni/Mn stoichiometry to reconfigure Fe's local chemical environment and unlock unprecedented redox depth.Density functional theory(DFT)calculations reveal that the designed NaNi_(0.35)Fe_(0.225)Mn_(0.425)O_(2)cathode exhibits a reduced Bader charge on Fe(1.598 vs.1.638 in NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2))and elevated Fe 3d orbital energy,signifying enhanced Fe redox activity.This configuration enables an exceptional Fe^(2.60+)/Fe^(3.88+)redox(1.28 e~-per Fe),delivering a reversible capacity of184.3 mAh g^(-1)within 2-4.2 V at 0.2 C,markedly exceeding the benchmark NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2)(161.3 mAh g^(-1))with low reaction depth of Fe^(3.01+)/Fe^(3.61+).The intensified cationic redox reaction enables an ultrahigh energy density of 596 Whkg-1.The NaNi_(0.35)Fe_(0.225)Mn_(0.425)O_(2)cathode demonstrates robust performance over a broad temperature range from-15℃to 60℃.In situ and ex situ characterizations unveil a reversible O3■P3■OP2 phase transition with minimal volume change(1.88%)that circumvents detrimental deleterious O'3 intermediates and intragranular cracking.This work establishes valence engineering as a paradigm to consolidate cationic redox reaction in high-energy layered sodium oxide cathodes.展开更多
文摘由于钠资源丰富且成本低廉,钠离子电池(SIBs)有望成为解决可再生能源存储与分配难题的储能器件,开发高性能正极材料是SIBs实现产业化应用的关键。磷酸铁钠(NaFePO_(4))具有成本低廉和安全性好等优点,受到人们的广泛关注。然而,Na+半径相对较大,导致其扩散动力学较慢,致使NaFePO_(4)倍率性能较差,限制了其进一步应用。本文通过调控LiFePO4脱锂电压进行电化学嵌钠,成功合成出NaFePO_(4)材料。结果表明,当脱锂电压为4.4 V,通过电化学嵌钠合成出的NaFePO_(4)材料在25℃、0.5 C(1 C=154 mAh g^(-1))下循环50次后仍然具有78.23 mAh g^(-1)的放电比容量,容量保持率高达96.97%。同时,其在2 C的倍率下仍然具有62.98 mAh g^(-1)的放电比容量。脱锂电压为4.4 V时有效提高了NaFePO_(4)材料的晶格间距,利于Na+的脱嵌,从而在一定程度上提高了NaFePO_(4)材料的倍率性能。钠离子电池正极材料的研究对于缓解锂资源稀缺问题以及提高电池性能都具有重要的意义。
基金funding from the National Natural Science Foundation of China (Award 91745203) supplemented by Central Universities’ Basic Research Funds.
文摘Ceramic cells promise ideal energy conversion and storage devices,making the development of efficient and robust air electrodes crucial for their application.In this study,a Ba_(0.4)Sr_(0.5)Cs_(0.1)Co_(0.7)Fe_(0.2)Nb_(0.1)O_(3−δ)(BSCCFN)air electrode,based on Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3−δ)(BSCF),is designed using a perovskite A-B-site ionic Lewis acid strength(ISA)polarization distribution strategy and is successfully applied in both oxygen-ion conducting solid oxide fuel cells(O-SOFCs)and proton-conducting reversible protonic ceramic cells(R-PCCs).When BSCCFN is used as the air electrode in O-SOFCs,a peak power density(PPD)of 1.45 W cm^(−2)is achieved at 650°C,whereas in R-PCCs,a PPD of 1.13 W cm^(−2)and a current density of−1.8 A cm^(−2)at 1.3 V are achieved at the same temperature and show stable reversibility over 100 h.Experimental measurements and theoretical calculations demonstrate that low-ISA Cs+doping accelerates the reaction kinetics of both oxygen ions and protons,while high-ISA Nb^(5+)doping enhances electrode stability.The synergistic effect of Cs^(+)and Nb^(5+)co-doping in the BSCCFN electrode lies in the ISA polarization distribution,which weakens the Co/Fe–O bond covalency,thereby promoting oxygen vacancy formation and facilitating the conduction of oxygen ions and protons.
基金supported by the National Natural Science Foundation of China(52202218)the Fundamental Research Funds for the Central Universities(CUSF-DH-T-2023044)。
文摘The deployment of flexible zinc-ion batteries is impeded by dendrite growth from random anode defects.Conventional defect-elimination strategies often compromise flexibility and fail to achieve uniform interfaces.We propose a paradigm shift:reconfiguring random defects into engineered,monodisperse artificial micro-curves to homogenize electric fields and guide aligned zinc(Zn)deposition.Using moisture-assisted flash heating,we transform zincophilic silver(Ag)coatings on carbon fibers into uniformly dispersed micro-curved particles(Ag Particles@CC),creating identical nucleation sites with optimal zinc ion(Zn^(2+))adsorption energetics.Theoretical simulations confirm these structures eliminate localized field concentrations,enabling homogeneous plating/stripping.This design demonstrates remarkable performance,with ultrastable 1500 cycles at 10 mA cm^(-2)(98.6%avg.Coulombic efficiency)and symmetric cell operation>650 h(57.7 mV hysteresis).Crucially,interparticle discontinuities preserve intrinsic flexibility,enabling flexible pouch cells(Ag Particles@CC-Zn//NaV_(3)O_(8)·1,5H_(2)O)to successfully power wearable devices such as smartwatches and smartphones.This work establishes defect reconfiguration via artificial micro-curvature engineering as a universal strategy toward dendritesuppressed,flexible energy storage.
基金supported by the “Pioneer” and “Leading Goose” R&D Program of Zhejiang Province of China (No. 2024C01056)the support from London South Bank University
文摘Layered oxides have attracted significant attention as cathodes for sodium-ion batteries(SIBs)due to their compositional versatility and tuneable electrochemical performance.However,these materials still face challenges such as structural phase transitions,Na^(+)/vacancy ordering,and Jahn–Teller distortion effect,resulting in severe capacity decay and sluggish ion kinetics.We develop a novel Cu/Y dual-doping strategy that leads to the formation of"Na–Y"interlayer aggregates,which act as structural pillars within alkali metal layers,enhancing structural stability and disrupting the ordered arrangement of Na^(+)/vacancies.This disruption leads to a unique coexistence of ordered and disordered Na^(+)/vacancy states with near-zero strain,which significantly improves Na^(+)diffusion kinetics.This structural innovation not only mitigates the unfavorable P2–O2 phase transition but also facilitates rapid ion transport.As a result,the doped material demonstrates exceptional electrochemical performance,including an ultra-long cycle life of 3000 cycles at 10 C and an outstanding high-rate capability of~70 mAh g^(−1)at 50 C.The discovery of this novel interlayer pillar,along with its role in modulating Na^(+)/vacancy arrangements,provides a fresh perspective on engineering layered oxides.It opens up promising new pathways for the structural design of advanced cathode materials toward efficient,stable,and high-rate SIBs.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(No.NRF-2021M3H4A1A02048529)the Ministry of Trade,Industry and Energy(MOTIE)of the Korean government under grant No.RS-2022-00155854support from the DGIST Supercomputing and Big Data Center.
文摘To enhance the electrochemical performance of lithium-ion battery anodes with higher silicon content,it is essential to engineer their microstructure for better lithium-ion transport and mitigated volume change as well.Herein,we suggest an effective approach to control the micropore structure of silicon oxide(SiO_(x))/artificial graphite(AG)composite electrodes using a perforated current collector.The electrode features a unique pore structure,where alternating high-porosity domains and low-porosity domains markedly reduce overall electrode resistance,leading to a 20%improvement in rate capability at a 5C-rate discharge condition.Using microstructure-resolved modeling and simulations,we demonstrate that the patterned micropore structure enhances lithium-ion transport,mitigating the electrolyte concentration gradient of lithium-ion.Additionally,perforating current collector with a chemical etching process increases the number of hydrogen bonding sites and enlarges the interface with the SiO_(x)/AG composite electrode,significantly improving adhesion strength.This,in turn,suppresses mechanical degradation and leads to a 50%higher capacity retention.Thus,regularly arranged micropore structure enabled by the perforated current collector successfully improves both rate capability and cycle life in SiO_(x)/AG composite electrodes,providing valuable insights into electrode engineering.
基金supports of the National Natural Science Foundation of China(NSFC)(52021004,52394202)key project of the Joint Fund for Innovation and Development of Chongqing Natural Science Foundation(CSTB2022NSCQ-LZX0013)+1 种基金the National Natural Science Foundation of China(NSFC)(52301232,and 52476056)the Natural Science Foundation of Chongqing Province(2024NSCQ-MSX1109).
文摘Controllable synthesis of ultrathin metallene nanosheets and rational design of their spatial arrangement in favor of electrochemical catalysis are critical for their renewable energy applications.Here,a biomimetic design of“Trunk-Branch-Leaf”strategy is proposed to prepare the ultrathin edge-riched Zn-ene“leaves”with a thickness of~2.5 nm,adjacent Zn-ene cross-linked with each other,which are supported by copper nanoneedle“branches”on copper mesh“trunks,”named as Zn-ene/Cu-CM.The resulting superstructure enables the formation of an interconnected network and multiple channels,which can be used as an electrocatalytic CO_(2) reduction reaction(CO_(2)RR)electrode to allow a fast charge and mass transfer as well as a large electrolyte reservoir.By virtue of the distinctive structure,the obtained Zn-ene/Cu-CM electrode exhibits excellent selectivity and activity toward CO production with a maximum Faradaic efficiency of 91.3%and incredible partial current density up to 40 mA cm^(−2),outperforming most of the state-of-the-art Zn-based electrodes for CO_(2) reduction.The phenolphthalein color probe combined with in situ attenuated total reflection-infrared spectroscopy uncovered the formation of the localized pseudo-alkaline microenvironment at the interface of the Zn-ene/Cu-CM electrode.Theoretical calculations confirmed that the localized pH as the origin is responsible for the adsorption of CO_(2) at the interface and the generation of *COOH and *CO intermediates.This study offers valuable insights into developing efficient electrodes through synergistic regulation of reaction microenvironments and active sites,thereby facilitating the electrolysis of practical CO_(2) conversion.
基金supported by the Yunnan Province Basic Research General Program,China(No.202201BE070001-002)the Major Science and Technology Projects in Yunnan Province,China(No.202402AF 080005).
文摘The rapid expansion of the photovoltaic industry has generated heavily oxidized waste silicon(wSi),which hinders efficient recycling owing to its small particle size and uncontrolled surface oxidation.This study introduces a molten salt electrochemical strategy for converting photovoltaic wSi into NiSi_(2)-silicon nanorods(NiSi_(2)-SiNRs)as high-performance anode materials for lithium-ion batteries.A stable oxidized passivation layer is formed on the wSi surface via controlled oxidation,and further in situ generated highly active NiSi_(2) droplets.The molten salt electric field modulates the surface energy of silicon,while particle integration drives localized directional growth,enabling the self-assembly of NiSi_(2)-SiNRs composites.These NiSi_(2)-SiNRs anodes exhibit rapid ion transport and effective strain buffering.The high aspect ratio of SiNRs and the presence of retained NiSi_(2) facilitate both longitudinal and transverse Li^(+) diffusion.Owing to their robust structural design,the NiSi_(2)-SiNRs anode achieves an excellent initial Coulombic efficiency of 91.61%and retains 72.99%of its capacity after 800 cycles at 2 A·g^(−1).This study establishes a model system for investigating silicide/silicon interfaces in molten salt electrochemical synthesis and provides an effective strategy for upcycling photovoltaic wSi into high-performance lithium-ion battery anodes.
基金the National Natural Science Foundation of China(Nos.52404316,52461040,52274297,52474325,and 22202053)Hainan Provincial Natural Science Foundation(No.524RC475)+3 种基金Collaborative Innovation Center of Marine Science and Technology of Hainan University(No.XTCX2022HYC14)Start-up Research Foundation of Hainan University(Nos.XJ2400012968,KYQD(ZR)23069,23169 and 21124the support for comprehensive characterizations by Pico Election Microscopy Center of Hainan Universitythe funding supports from China Scholarship Council。
文摘Zinc-iodine(Zn-I_(2))batteries are deemed as potential candidate of energy storage system for the merits of high safety,cost-effectiveness,high capacity,and environmental compatibility.Unfortunately,the practical implementation of Zn-I_(2)batteries is still hindered by the sluggish iodine redox kinetics and the shuttle effect of soluble polyiodides,which induce rapid capacity decay and electrode interface passivation.This work proposes platinum/carbon(Pt/C)and iridium/carbon(Ir/C)composite as conductive catalytic iodine hosts,which realizes the physical confinement for active iodine through the intrinsic porous structure.The introduction of active Pt/Ir sites effectively anchors the polyiodides through chemical adsorption capability,and inhibits shuttle effect and Zn metal corrosion.In addition,the superior electrical conductivity and catalytic activity of Pt/C and Ir/C carriers also contribute to reduce the reaction energy barriers,significantly promoting the electrochemical performance and conversion reaction kinetics.As expected,the assembled Zn//Pt/C@I_(2)and Zn//Ir/C@I_(2)batteries achieve impressive reversible capacity of 132.2 and 108 mAh g^(-1)after 2000 cycles at 200 mA g^(-1),respectively,and their capacity retention rate after 25000 cycles at 1000 mA g^(-1)are as high as 88.1%and 85.9%.This study will guide the carrier design of iodine cathode to drive the application of high-performance Zn-I2batteries.
基金supported by the National Natural Science Foundation of China(Grant Nos.52202282,52402054,22471283,and 52202327)Natural Science Foundation of Tianjin City(Grant Nos.22JCYBJC00040,24JCQNJC00970)。
文摘High-capacity O3-type layered NiFeMn-based oxides are promising cathodes for sodium-ion batteries,though their practical deployment is constrained by the inherent limitations of Fe redox chemistry.Traditional designs generally enforcing stoichiometric symmetry(Ni=Mn)yield low Fe redox activity.Herein,we propose a valence engineering strategy that breaks conventional Ni/Mn stoichiometry to reconfigure Fe's local chemical environment and unlock unprecedented redox depth.Density functional theory(DFT)calculations reveal that the designed NaNi_(0.35)Fe_(0.225)Mn_(0.425)O_(2)cathode exhibits a reduced Bader charge on Fe(1.598 vs.1.638 in NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2))and elevated Fe 3d orbital energy,signifying enhanced Fe redox activity.This configuration enables an exceptional Fe^(2.60+)/Fe^(3.88+)redox(1.28 e~-per Fe),delivering a reversible capacity of184.3 mAh g^(-1)within 2-4.2 V at 0.2 C,markedly exceeding the benchmark NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2)(161.3 mAh g^(-1))with low reaction depth of Fe^(3.01+)/Fe^(3.61+).The intensified cationic redox reaction enables an ultrahigh energy density of 596 Whkg-1.The NaNi_(0.35)Fe_(0.225)Mn_(0.425)O_(2)cathode demonstrates robust performance over a broad temperature range from-15℃to 60℃.In situ and ex situ characterizations unveil a reversible O3■P3■OP2 phase transition with minimal volume change(1.88%)that circumvents detrimental deleterious O'3 intermediates and intragranular cracking.This work establishes valence engineering as a paradigm to consolidate cationic redox reaction in high-energy layered sodium oxide cathodes.
