Nickel-rich transition-metal oxides are widely regarded as promising cathode materials for high-energydensity lithium-ion batteries for emerging electric vehicles. However, achieving high energy density in Ni-rich cat...Nickel-rich transition-metal oxides are widely regarded as promising cathode materials for high-energydensity lithium-ion batteries for emerging electric vehicles. However, achieving high energy density in Ni-rich cathodes is accompanied by substantial safety and cycle-life obstacles. The major issues of Ni-rich cathodes at high working potentials are originated from the unstable cathode-electrolyte interface, while the underlying mechanism of parasitic reactions towards surface reconstructions of cathode materials is not well understood. In this work, we controlled the Li_(2)CO_(3) impurity content on LiNi_(0.83)Mn_(0.1)Co_(0.07)O_(2) cathodes using air, tank-air, and O_(2) synthesis environments. Home-built high-precision leakage current and on-line electrochemical mass spectroscopy experiments verify that Li_(2)CO_(3) impurity is a significant promoter of parasitic reactions on Ni-rich cathodes. The rate of parasitic reactions is strongly correlated to Li_(2)CO_(3) content and severe performance deterioration of Ni83 cathodes.The post-mortem characterizations via high-resolution transition electron microscope and X-ray photoelectron spectroscopy depth profiles reveal that parasitic reactions promote more Ni reduction and O deficiency and even rock-salt phase transformation at the surface of cathode materials. Our observation suggests that surface reconstructions have a strong affiliation to parasitic reactions that create chemically acidic environment to etch away the lattice oxygen and offer the electrical charge to reduce the valence state of transition metal. Thus, this study advances our understanding on surface reconstructions of Nirich cathodes and prepares us for searching for rational strategies.展开更多
Solid-state batteries(SSBs)have been considered the most promising technology because of their superior energy density and safety.Among all the solid-state electrolytes(SEs),Li_(7) La_(3) Zr_(2) O_(12)(LLZO)with high ...Solid-state batteries(SSBs)have been considered the most promising technology because of their superior energy density and safety.Among all the solid-state electrolytes(SEs),Li_(7) La_(3) Zr_(2) O_(12)(LLZO)with high ionic conductivity(3×10^(−4) S/cm)has been widely investigated.However,its large-scale production in ambient air faces a challenge.After air exposure,the generated Li_(2)CO_(3) layer deteriorates the ionic conductivity and interfacial wettability,thus greatly compromising the electrochemical performance of SSBs.Many works aim to eliminate this layer to recover the pristine LLZO surface.Unfor-tunately,few articles have emphasized the merits of Li_(2)CO_(3).In this review,we focus on the two-sidedness of Li_(2)CO_(3).We discuss the various characteristics of Li_(2)CO_(3) that can be used and recapitulate the strategies that utilize Li_(2)CO_(3).Insulating Li_(2)CO_(3) is no longer an obstacle but an opportunity for realizing intimate interfacial contact,high air stability,and outstand-ing electrochemical performance.This review aims to off er insightful guidelines for treating air-induced Li_(2)CO_(3) and lead to developing the enhanced air stability and electrochemical performance of LLZO.展开更多
Lithium(Li)-rich manganese(Mn)-based cathode Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)(LRNCM)has attracted considerable attention owing to its high specific discharge capacity and low cost.However,unsatisfactory cycle ...Lithium(Li)-rich manganese(Mn)-based cathode Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)(LRNCM)has attracted considerable attention owing to its high specific discharge capacity and low cost.However,unsatisfactory cycle performance and poor rate property hinder its large-scale application.The fast ionic conductor has been widely used as the cathode coating material because of its superior stability and excellent lithium-ion conductivity rate.In this study,Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2) is modified by using Li_(1.4)Al_(0.4)Ti_(1.6)(PO_(4))_(3)(LATP)ionic conductor.The electrochemical test results show that the discharge capacity of the resulting LRNCM@LATP1 sample is 198 mA·h/g after 100 cycles at 0.2C,with a capacity retention of 81%.Compared with the uncoated pristine LRNCM(188.4 m A·h/g and 76%),LRNCM after the LATP modification shows superior cycle performance.Moreover,the lithium-ion diffusion coefficient D_(Li+)is a crucial factor affecting the rate performance,and the D_(Li+)of the LRNCM material is improved from 4.94×10^(-13) to 5.68×10^(-12)cm^(2)/s after modification.The specific capacity of LRNCM@LATP1 reaches 102.5 mA·h/g at 5C,with an improved rate performance.Thus,the modification layer can considerably enhance the electrochemical performance of LRNCM.展开更多
Rechargeable lithium-ion batteries(LIBs)represent the highest energy density in the contemporary energy storage community,typically delivering a practical energy density of 150-350 Wh kg-1in the current technique,whic...Rechargeable lithium-ion batteries(LIBs)represent the highest energy density in the contemporary energy storage community,typically delivering a practical energy density of 150-350 Wh kg-1in the current technique,which can hardly satisfy the evergrowing demand for the portable electronic devices and power tools requiring long service time[1-3].展开更多
基金supported by the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Officesupported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office, under Contract No. DE-SC0012704+1 种基金supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract DE-AC02-06CH11357supported by the Vehicle Technologies Office of the U.S. Department of Energy。
文摘Nickel-rich transition-metal oxides are widely regarded as promising cathode materials for high-energydensity lithium-ion batteries for emerging electric vehicles. However, achieving high energy density in Ni-rich cathodes is accompanied by substantial safety and cycle-life obstacles. The major issues of Ni-rich cathodes at high working potentials are originated from the unstable cathode-electrolyte interface, while the underlying mechanism of parasitic reactions towards surface reconstructions of cathode materials is not well understood. In this work, we controlled the Li_(2)CO_(3) impurity content on LiNi_(0.83)Mn_(0.1)Co_(0.07)O_(2) cathodes using air, tank-air, and O_(2) synthesis environments. Home-built high-precision leakage current and on-line electrochemical mass spectroscopy experiments verify that Li_(2)CO_(3) impurity is a significant promoter of parasitic reactions on Ni-rich cathodes. The rate of parasitic reactions is strongly correlated to Li_(2)CO_(3) content and severe performance deterioration of Ni83 cathodes.The post-mortem characterizations via high-resolution transition electron microscope and X-ray photoelectron spectroscopy depth profiles reveal that parasitic reactions promote more Ni reduction and O deficiency and even rock-salt phase transformation at the surface of cathode materials. Our observation suggests that surface reconstructions have a strong affiliation to parasitic reactions that create chemically acidic environment to etch away the lattice oxygen and offer the electrical charge to reduce the valence state of transition metal. Thus, this study advances our understanding on surface reconstructions of Nirich cathodes and prepares us for searching for rational strategies.
基金the support from the National Natural Science Foundation of China (Nos.U2001220 and 51902223)the Haihe Laboratory of Sustainable Chemical Transformations+2 种基金the Fundamental Research Funds for the Central Universitiesthe National Key Research and Development Program of China (Nos.2021YFF0500600 and 2019YFE0118800)the Natural Science Foundation of Tianjin (No.20JCYBJC00850)
文摘Solid-state batteries(SSBs)have been considered the most promising technology because of their superior energy density and safety.Among all the solid-state electrolytes(SEs),Li_(7) La_(3) Zr_(2) O_(12)(LLZO)with high ionic conductivity(3×10^(−4) S/cm)has been widely investigated.However,its large-scale production in ambient air faces a challenge.After air exposure,the generated Li_(2)CO_(3) layer deteriorates the ionic conductivity and interfacial wettability,thus greatly compromising the electrochemical performance of SSBs.Many works aim to eliminate this layer to recover the pristine LLZO surface.Unfor-tunately,few articles have emphasized the merits of Li_(2)CO_(3).In this review,we focus on the two-sidedness of Li_(2)CO_(3).We discuss the various characteristics of Li_(2)CO_(3) that can be used and recapitulate the strategies that utilize Li_(2)CO_(3).Insulating Li_(2)CO_(3) is no longer an obstacle but an opportunity for realizing intimate interfacial contact,high air stability,and outstand-ing electrochemical performance.This review aims to off er insightful guidelines for treating air-induced Li_(2)CO_(3) and lead to developing the enhanced air stability and electrochemical performance of LLZO.
基金Project(51772333) supported by the National Natural Science Foundation of China。
文摘Lithium(Li)-rich manganese(Mn)-based cathode Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)(LRNCM)has attracted considerable attention owing to its high specific discharge capacity and low cost.However,unsatisfactory cycle performance and poor rate property hinder its large-scale application.The fast ionic conductor has been widely used as the cathode coating material because of its superior stability and excellent lithium-ion conductivity rate.In this study,Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2) is modified by using Li_(1.4)Al_(0.4)Ti_(1.6)(PO_(4))_(3)(LATP)ionic conductor.The electrochemical test results show that the discharge capacity of the resulting LRNCM@LATP1 sample is 198 mA·h/g after 100 cycles at 0.2C,with a capacity retention of 81%.Compared with the uncoated pristine LRNCM(188.4 m A·h/g and 76%),LRNCM after the LATP modification shows superior cycle performance.Moreover,the lithium-ion diffusion coefficient D_(Li+)is a crucial factor affecting the rate performance,and the D_(Li+)of the LRNCM material is improved from 4.94×10^(-13) to 5.68×10^(-12)cm^(2)/s after modification.The specific capacity of LRNCM@LATP1 reaches 102.5 mA·h/g at 5C,with an improved rate performance.Thus,the modification layer can considerably enhance the electrochemical performance of LRNCM.
基金support from the National Natural Science Foundation of China(21972133,21805070,21605136,21733012,and 21633008)the Newton Advanced Fellowships(NAF/R2/180603)+1 种基金the Guangxi Department of Education(2019KY0394)the"Scientist Studio Funding"from Tianmu Lake Institute of Advanced Energy Storage Technologies Co.,Ltd.
文摘Rechargeable lithium-ion batteries(LIBs)represent the highest energy density in the contemporary energy storage community,typically delivering a practical energy density of 150-350 Wh kg-1in the current technique,which can hardly satisfy the evergrowing demand for the portable electronic devices and power tools requiring long service time[1-3].
