Four low-alloy hull steels with different alloy elements were selected. Theirsusceptibility to pitting corrosion was compared by means of electrochemical polarization test. Theinclusions in the steels and their pittin...Four low-alloy hull steels with different alloy elements were selected. Theirsusceptibility to pitting corrosion was compared by means of electrochemical polarization test. Theinclusions in the steels and their pitting corrosion characteristics were studied by an electronprobe micro-analyzer (EPMA). The results indicate that some inclusions are the main sources ofpitting corrosion. The susceptibility of nickel-chromium steel to pit initiation is less than thatof manganese steel. Under the same conditions, nickel-chromium steel is easier to passivate thanmanganese steel, and the passive films on nickel-chromium steel surface are more stable than that onmanganese steel. In low-alloy steels, the higher the contents of nickel and chromium, the lower thecritical passive pH value. In the same kind of steel, multi-phase inclusions containing sulfide areeasier to initiate pitting corrosion than other inclusions.展开更多
LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)with a spinel crystal structure presents a compelling avenue towards the development of economic cobalt-free and high voltage(~5 V)lithium-ion batteries.Nevertheless,the elevated operation...LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)with a spinel crystal structure presents a compelling avenue towards the development of economic cobalt-free and high voltage(~5 V)lithium-ion batteries.Nevertheless,the elevated operational voltage of LNMO gives rise to pronounced interfacial interactions between the distorted surface lattices characterized by Jahn-Teller(J-T)distortions and the electrolyte constituents.Herein,a localized crystallized coherent LaNiO_(3) and surface passivated Li_(3)PO_(4) layer is deposited on LNMO via a one-step calcination process.As evidenced by transmission electron microscopy(TEM),time-of-flight secondary ion mass spectrometry(ToF-SIMS)and density functional theory(DFT)calculation,the epitaxial growth of LaNiO_(3) along the LNMO lattice can effectively stabilize the structure and inhibit irreversible phase transitions,and the Li_(3)PO_(4) surface coating can prevent the chemical reaction between HF and transition metals without sacrificing the electrochemical activity.In addition,the ionic conductive Li_(3)PO_(4) and atomic wetting inter-layer enables fast charge transfer transport property.Consequently,the LNMO material enabled by the lattice bonding and surface passivating features,demonstrates high performance at high current densities and good capacity retention during long-term test.The rational design of interface coherent engineering and surface coating layers of the LNMO cathode material offers a new perspective for the practical application of high-voltage lithium-ion batteries.展开更多
A high-performance quasi-solid polymer electrolyte for sodium metal batteries(SMBs)based on in-situ polymerized poly(1,3-dioxolane)(DOL)with 20%volume ratio of fluoroethylene carbonate(FEC),termed"PDFE-20",i...A high-performance quasi-solid polymer electrolyte for sodium metal batteries(SMBs)based on in-situ polymerized poly(1,3-dioxolane)(DOL)with 20%volume ratio of fluoroethylene carbonate(FEC),termed"PDFE-20",is proposed in this work.It is demonstrated PDFE-20 possesses a room-temperature ionic conductivity of 3.31×10^(-3) S cm^(-1),an ionic diffusion activation energy of 0.10 eV,and an oxidation potential of 4.4 V.SMBs based on PDFE-20 and Na_(3)V_(2)(PO_(4))_(3)(NVP)cathodes were evaluated with an active material mass loading of 6.8 mg cm^(-2).The cell displayed an initial discharge specific capacity of 104 mA h g^(-1),and97.1%capacity retention after 100 cycles at 0.5 C.In-situ polymerization conformally coats the anode/-cathode interfaces,avoiding geometrical gaps and high charge transfer resistance with ex-situ polymerization of the same chemistry.FEC acts as a plasticizer during polymerization to suppress crystallization and significantly improves ionic transport.During battery cycling FEC promotes mechanical congruence of electrolyte-electrode interfaces while forming a stable NaF-rich solid electrolyte interphase(SEI)at the anode.Density functional theory(DFT)calculations were also performed to further understand the role FEC in the poly(DOL)-FEC electrolytes.This work broadens the application of in-situ prepared poly(DOL)electrolytes to sodium storage and demonstrates the crucial role of FEC in improving the electrochemical performance.展开更多
Extensive usage of highly conductive carbon materials with large specific surface area(e.g.,carbon nanotubes,CNTs)in lithium ion batteries(LIBs),especially as current collector of anodes,suffers from low initial coulo...Extensive usage of highly conductive carbon materials with large specific surface area(e.g.,carbon nanotubes,CNTs)in lithium ion batteries(LIBs),especially as current collector of anodes,suffers from low initial coulombic efficiency(ICE),large interfacial resistance,and severe embrittlement,as the large specific surface area often results in severe interfacial decomposition of the electrolyte and the formation of thick and fluffy solid electrolyte interphase(SEI)during cycling of LIBs.Herein,we demonstrate that when the CNT-based current collector and Na foil(which are being stacked intimately upon each other)are being placed in Na+-based organic electrolyte,local redox reaction between the Na foil and the electrolyte would occur spontaneously,generating a thin and homogeneous NaF-based passivating layer on the CNTs.More importantly,we found that owing to the weak solvation behaviors of Na+in the organic electrolyte,the resulting passivation layer,which is rich in NaF,is thin and dense;when used as the anode current collector in LIBs,the pre-existing passivating layer can function effectively in isolating the anode from the solvated Li+,thus suppressing the formation of bulky SEI and the destructive intercalation of solvated Li+.The relevant half-cell(graphite as anode)exhibits a high ICE of 92.1%;the relevant pouch cell with thus passivated CNT film as current collectors for both electrodes(LiCoO_(2)as cathode,graphite as anode)displays a high energy density of 255 Wh kg^(-1),spelling an increase of 50%compared with that using the conventional metal current collectors.展开更多
Graphene coatings have been shown to protect the underlying material from oxidation when exposed to different media. However, the passivating properties of graphene in air at room temperature, which corresponds to the...Graphene coatings have been shown to protect the underlying material from oxidation when exposed to different media. However, the passivating properties of graphene in air at room temperature, which corresponds to the operating conditions of many electronic devices, still remain undear. In this work, we analyze the oxidation kinetics of graphene/Cu samples in air at room temperature for long periods of time （from I day to 113 days） using scanning electron microscopy, conductive atomic force microscopy and Auger electron microscop3~ and we compare the results with those obtained for similar samples treated in H202. We observe that unlike the graphene sheets exposed to H202, in which the accumulation of oxygen at the graphene domain boundaries evolves in a very controlled and progressive way, the local oxidation of graphene in air happens in a disordered manner. In both cases the oxide hillocks formed at the graphene domain boundaries can propagate to the domains until reaching a limiting width and height. Our results demonstrate that the local oxidation of the underlying material along the domain boundaries can dramatically decrease the roughness, conductivity, mechanical resistance and frictional characteristics of the graphene sheet, which reduces the performance of the whole device.展开更多
Polycrystalline Si(poly-Si)-based passivating contacts are promising candidates for high-efficiency crystalline Si solar cells.We show that nanosecond-scale pulsed laser melting(PLM)is an industrially viable technique...Polycrystalline Si(poly-Si)-based passivating contacts are promising candidates for high-efficiency crystalline Si solar cells.We show that nanosecond-scale pulsed laser melting(PLM)is an industrially viable technique to fabricate such contacts with precisely controlled dopant concentration profiles that exceed the solid solubility limit.We demonstrate that conventionally doped,hole-selective poly-Si/SiO_(x)contacts that provide poor surface passivation of c-Si can be replaced with Ga-or B-doped contacts based on non-equilibrium doping.We overcome the solid solubility limit for both dopants in poly-Si by rapid cooling and recrystallization over a timescale of∼25 ns.We show an active Ga dopant concentration of∼3×10^(20)cm^(−3)in poly-Si which is six times higher than its solubility limit in c-Si,and a B dopant concentration as high as∼10^(21) cm^(−3).We measure an implied open-circuit voltage of 735 mV for Ga-doped poly-Si/SiO_(x)contacts on Czochralski Si with a low contact resistivity of 35.5±2.4 mΩcm^(2).Scanning spreading resistance microscopy and Kelvin probe force microscopy show large diffusion and drift current in the p-n junction that contributes to the low contact resistivity.Our results suggest that PLM can be extended for hyperdoping of other semiconductors with low solubility atoms to enable high-efficiency devices.展开更多
Tandem solar cells are a key technology for exceeding the theoretical efficiency limit of single-junction cells.One of the most promising combinations is the silicon–perovskite tandem cells,considering their potentia...Tandem solar cells are a key technology for exceeding the theoretical efficiency limit of single-junction cells.One of the most promising combinations is the silicon–perovskite tandem cells,considering their potential for high efficiency,fabrication on a large scale,and low cost.While most research focuses on improving each subcell,another key challenge lies in the tunnel junction that connects these subcells,significantly impacting the overall cell characteristics.Here,we demonstrate the first use of tunnel junctions using a stack of p+/n+polysilicon passivating contacts deposited directly on the tunnel oxide to overcome the drawbacks of conventional metal oxide-based tunnel junctions,including low tunneling efficiency and sputter damage.Using Random Forest analysis,we achieved high implied open circuit voltages over 700 mV and low contact resistivities of 500 mΩcm 2,suggesting fill factor losses of less than 1%abs for the operating conditions of a tandem cell.展开更多
1,3-dioxolane (DOL) is originally used to pretreat the lithium metal electrode in order to passivate lithium metal and improve its interface stability. Through electrochemical impedance spectra (EIS) and cathodic pola...1,3-dioxolane (DOL) is originally used to pretreat the lithium metal electrode in order to passivate lithium metal and improve its interface stability. Through electrochemical impedance spectra (EIS) and cathodic polarization measurements of pretreated and untreated electrodes, it was found that 1,3-dioxolane could form a stable passivating film on the surface of lithium electrode. And such film could enhance effectively the interfacial stability of lithium electrode, without depressing its kinetics characteristic. Consequentially, further tests of the cell-performance during repeated charge/discharge cycles showed that the cell with DOL pretreated anode had better discharging performance and longer cycle life because of the passivating and protective effects of 1,3-dioxolane pretreatment on lithium electrode.展开更多
Clay minerals,phosphates,alkaline materials,organic materials are common improvers in the management of Cd polluted soil. This paper systematically summarized types of common soil improvers and their passivation mecha...Clay minerals,phosphates,alkaline materials,organic materials are common improvers in the management of Cd polluted soil. This paper systematically summarized types of common soil improvers and their passivation mechanism of Cd in soil. It reviewed advances in researches of soil improvers. Besides,it introduced major problems in four common passivating agents for management of Cd polluted soil. Finally,according to different mechanism characteristics of passivating agents,it came up with some recommendations.展开更多
文摘Four low-alloy hull steels with different alloy elements were selected. Theirsusceptibility to pitting corrosion was compared by means of electrochemical polarization test. Theinclusions in the steels and their pitting corrosion characteristics were studied by an electronprobe micro-analyzer (EPMA). The results indicate that some inclusions are the main sources ofpitting corrosion. The susceptibility of nickel-chromium steel to pit initiation is less than thatof manganese steel. Under the same conditions, nickel-chromium steel is easier to passivate thanmanganese steel, and the passive films on nickel-chromium steel surface are more stable than that onmanganese steel. In low-alloy steels, the higher the contents of nickel and chromium, the lower thecritical passive pH value. In the same kind of steel, multi-phase inclusions containing sulfide areeasier to initiate pitting corrosion than other inclusions.
基金supported by the National Natural Science Foundation of China(Nos.22209075,12004145)the Key Science and Technology Plan Project of Ji’an City(No.20211-015311)the Natural Science Foundation of Jiangsu Province(No.BK20200800).
文摘LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)with a spinel crystal structure presents a compelling avenue towards the development of economic cobalt-free and high voltage(~5 V)lithium-ion batteries.Nevertheless,the elevated operational voltage of LNMO gives rise to pronounced interfacial interactions between the distorted surface lattices characterized by Jahn-Teller(J-T)distortions and the electrolyte constituents.Herein,a localized crystallized coherent LaNiO_(3) and surface passivated Li_(3)PO_(4) layer is deposited on LNMO via a one-step calcination process.As evidenced by transmission electron microscopy(TEM),time-of-flight secondary ion mass spectrometry(ToF-SIMS)and density functional theory(DFT)calculation,the epitaxial growth of LaNiO_(3) along the LNMO lattice can effectively stabilize the structure and inhibit irreversible phase transitions,and the Li_(3)PO_(4) surface coating can prevent the chemical reaction between HF and transition metals without sacrificing the electrochemical activity.In addition,the ionic conductive Li_(3)PO_(4) and atomic wetting inter-layer enables fast charge transfer transport property.Consequently,the LNMO material enabled by the lattice bonding and surface passivating features,demonstrates high performance at high current densities and good capacity retention during long-term test.The rational design of interface coherent engineering and surface coating layers of the LNMO cathode material offers a new perspective for the practical application of high-voltage lithium-ion batteries.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52072105 and 21676067)the Key R&D Program of Anhui Province(202104a05020044)+3 种基金the Anhui Provincial Natural Science Foundation(2108085J23)the Major Science and Technology Projects in Anhui Province(202003a05020014,2021e03020001)the Fundamental Research Funds for the Central Universities(PA2021KCPY0028,JZ2022HGTB0251)supported by the National Science Foundation,Division of Materials Research,Award Number 1938833。
文摘A high-performance quasi-solid polymer electrolyte for sodium metal batteries(SMBs)based on in-situ polymerized poly(1,3-dioxolane)(DOL)with 20%volume ratio of fluoroethylene carbonate(FEC),termed"PDFE-20",is proposed in this work.It is demonstrated PDFE-20 possesses a room-temperature ionic conductivity of 3.31×10^(-3) S cm^(-1),an ionic diffusion activation energy of 0.10 eV,and an oxidation potential of 4.4 V.SMBs based on PDFE-20 and Na_(3)V_(2)(PO_(4))_(3)(NVP)cathodes were evaluated with an active material mass loading of 6.8 mg cm^(-2).The cell displayed an initial discharge specific capacity of 104 mA h g^(-1),and97.1%capacity retention after 100 cycles at 0.5 C.In-situ polymerization conformally coats the anode/-cathode interfaces,avoiding geometrical gaps and high charge transfer resistance with ex-situ polymerization of the same chemistry.FEC acts as a plasticizer during polymerization to suppress crystallization and significantly improves ionic transport.During battery cycling FEC promotes mechanical congruence of electrolyte-electrode interfaces while forming a stable NaF-rich solid electrolyte interphase(SEI)at the anode.Density functional theory(DFT)calculations were also performed to further understand the role FEC in the poly(DOL)-FEC electrolytes.This work broadens the application of in-situ prepared poly(DOL)electrolytes to sodium storage and demonstrates the crucial role of FEC in improving the electrochemical performance.
基金financially supported by the National Key Research and Development Program of China(2022YFB4002103)the National Natural Science Foundation of China(22279107)。
文摘Extensive usage of highly conductive carbon materials with large specific surface area(e.g.,carbon nanotubes,CNTs)in lithium ion batteries(LIBs),especially as current collector of anodes,suffers from low initial coulombic efficiency(ICE),large interfacial resistance,and severe embrittlement,as the large specific surface area often results in severe interfacial decomposition of the electrolyte and the formation of thick and fluffy solid electrolyte interphase(SEI)during cycling of LIBs.Herein,we demonstrate that when the CNT-based current collector and Na foil(which are being stacked intimately upon each other)are being placed in Na+-based organic electrolyte,local redox reaction between the Na foil and the electrolyte would occur spontaneously,generating a thin and homogeneous NaF-based passivating layer on the CNTs.More importantly,we found that owing to the weak solvation behaviors of Na+in the organic electrolyte,the resulting passivation layer,which is rich in NaF,is thin and dense;when used as the anode current collector in LIBs,the pre-existing passivating layer can function effectively in isolating the anode from the solvated Li+,thus suppressing the formation of bulky SEI and the destructive intercalation of solvated Li+.The relevant half-cell(graphite as anode)exhibits a high ICE of 92.1%;the relevant pouch cell with thus passivated CNT film as current collectors for both electrodes(LiCoO_(2)as cathode,graphite as anode)displays a high energy density of 255 Wh kg^(-1),spelling an increase of 50%compared with that using the conventional metal current collectors.
文摘Graphene coatings have been shown to protect the underlying material from oxidation when exposed to different media. However, the passivating properties of graphene in air at room temperature, which corresponds to the operating conditions of many electronic devices, still remain undear. In this work, we analyze the oxidation kinetics of graphene/Cu samples in air at room temperature for long periods of time （from I day to 113 days） using scanning electron microscopy, conductive atomic force microscopy and Auger electron microscop3~ and we compare the results with those obtained for similar samples treated in H202. We observe that unlike the graphene sheets exposed to H202, in which the accumulation of oxygen at the graphene domain boundaries evolves in a very controlled and progressive way, the local oxidation of graphene in air happens in a disordered manner. In both cases the oxide hillocks formed at the graphene domain boundaries can propagate to the domains until reaching a limiting width and height. Our results demonstrate that the local oxidation of the underlying material along the domain boundaries can dramatically decrease the roughness, conductivity, mechanical resistance and frictional characteristics of the graphene sheet, which reduces the performance of the whole device.
基金the National Renewable Energy Laboratory,operated by Alliance for Sustainable Energy,LLC,for the U.S.Department of Energy(DOE)under Contract No.DE-AC36-08GO28308.
文摘Polycrystalline Si(poly-Si)-based passivating contacts are promising candidates for high-efficiency crystalline Si solar cells.We show that nanosecond-scale pulsed laser melting(PLM)is an industrially viable technique to fabricate such contacts with precisely controlled dopant concentration profiles that exceed the solid solubility limit.We demonstrate that conventionally doped,hole-selective poly-Si/SiO_(x)contacts that provide poor surface passivation of c-Si can be replaced with Ga-or B-doped contacts based on non-equilibrium doping.We overcome the solid solubility limit for both dopants in poly-Si by rapid cooling and recrystallization over a timescale of∼25 ns.We show an active Ga dopant concentration of∼3×10^(20)cm^(−3)in poly-Si which is six times higher than its solubility limit in c-Si,and a B dopant concentration as high as∼10^(21) cm^(−3).We measure an implied open-circuit voltage of 735 mV for Ga-doped poly-Si/SiO_(x)contacts on Czochralski Si with a low contact resistivity of 35.5±2.4 mΩcm^(2).Scanning spreading resistance microscopy and Kelvin probe force microscopy show large diffusion and drift current in the p-n junction that contributes to the low contact resistivity.Our results suggest that PLM can be extended for hyperdoping of other semiconductors with low solubility atoms to enable high-efficiency devices.
基金This research was funded by the New&Renewable Energy Core Technology Program of the Korea Institute of Energy Technology Eval-uation and Planning(KETEP),and supported by the ministry of Trade,Industry,Energy,of the Republic of Korea(No.20204010600470)Munho Kim acknowledges the support of Ministry of Education,Sin-gapore,under AcRF Tier 2(T2EP50120-0001)。
文摘Tandem solar cells are a key technology for exceeding the theoretical efficiency limit of single-junction cells.One of the most promising combinations is the silicon–perovskite tandem cells,considering their potential for high efficiency,fabrication on a large scale,and low cost.While most research focuses on improving each subcell,another key challenge lies in the tunnel junction that connects these subcells,significantly impacting the overall cell characteristics.Here,we demonstrate the first use of tunnel junctions using a stack of p+/n+polysilicon passivating contacts deposited directly on the tunnel oxide to overcome the drawbacks of conventional metal oxide-based tunnel junctions,including low tunneling efficiency and sputter damage.Using Random Forest analysis,we achieved high implied open circuit voltages over 700 mV and low contact resistivities of 500 mΩcm 2,suggesting fill factor losses of less than 1%abs for the operating conditions of a tandem cell.
文摘1,3-dioxolane (DOL) is originally used to pretreat the lithium metal electrode in order to passivate lithium metal and improve its interface stability. Through electrochemical impedance spectra (EIS) and cathodic polarization measurements of pretreated and untreated electrodes, it was found that 1,3-dioxolane could form a stable passivating film on the surface of lithium electrode. And such film could enhance effectively the interfacial stability of lithium electrode, without depressing its kinetics characteristic. Consequentially, further tests of the cell-performance during repeated charge/discharge cycles showed that the cell with DOL pretreated anode had better discharging performance and longer cycle life because of the passivating and protective effects of 1,3-dioxolane pretreatment on lithium electrode.
基金Supported by National Key Research and Development Program(2016YED0800705-01)Key Research and Development Program of Guangxi(Gui Ke AB16380084)+2 种基金Key Agricultural Science and Technology Program of Guangxi(201528,201604)Scientific Research and Technological Development Program Project of Nanning City(20162105)Scientific Development Fund Project of Guangxi Academy of Agricultural Sciences(Gui Nong Ke2017JM06,2017JM07)
文摘Clay minerals,phosphates,alkaline materials,organic materials are common improvers in the management of Cd polluted soil. This paper systematically summarized types of common soil improvers and their passivation mechanism of Cd in soil. It reviewed advances in researches of soil improvers. Besides,it introduced major problems in four common passivating agents for management of Cd polluted soil. Finally,according to different mechanism characteristics of passivating agents,it came up with some recommendations.
