Lithium and manganese-rich layered oxides(LMROs)have attracted extensive attention and are promising cathode materials for next-generation lithium ion batteries due to their high capacities and high energy densities.H...Lithium and manganese-rich layered oxides(LMROs)have attracted extensive attention and are promising cathode materials for next-generation lithium ion batteries due to their high capacities and high energy densities.However,LMRO cathode suffers from severe capacity and voltage fading originating from irreversible surface oxygen evolution.Herein,we propose a facile redox couple strategy by introducing nitroxyl radicals species to regulate the surface anionic redox reaction of LMRO cathode.Differential electrochemical mass spectroscopy,X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analyses demonstrate that during charge process,the peroxide ion O_(2)^(2−)on the surface generated from the oxidation of lattice O^(2-)could be reduced back to stable O^(2-)by redox couple in time,thus avoiding oxygen evolution and structure degradation,as well as enhancing bulk oxygen redox activity.The enhanced LMRO electrode delivers a high capacity of 220.3 mAh g^(−1)at 1 C.An excellent cycling stability with a capacity retention of 94.4%is achieved after 500 cycles,as well as a suppressed voltage decay with only 1.12 mV per cycle.展开更多
Li-and Mn-rich(LMR)cathode materials have received tremendous attention due to the highly reversible specific capacity(>250 m Ah·g^(-1)).In the analysis of its crystal structure,the two-phase composite model g...Li-and Mn-rich(LMR)cathode materials have received tremendous attention due to the highly reversible specific capacity(>250 m Ah·g^(-1)).In the analysis of its crystal structure,the two-phase composite model gains increasing acceptance,and the phase transition behaviors in LMR cathode materials have been extensively studied.Herein,the structure controversy of LMR cathode materials,and the mechanisms of phase transition are summarized.Particularly,the causes of initiating or accelerating the phase transition of LMR cathode materials have been summarized into three main driving forces,i.e.,the electrochemical driving force,the component driving force and the thermodynamic driving force.Additionally,the applications of phase transition behavior in improving the electrochemical performance of LMR cathode materials,including the construction of spinel surface coating and spinel/layered hetero-structure are discussed.展开更多
There are plenty of issues need to be solved before the practi-cal application of Li-and Mn-rich cathodes,including the detrimental voltage decay and mediocre rate capability,etc.Element doping can e ectively solve th...There are plenty of issues need to be solved before the practi-cal application of Li-and Mn-rich cathodes,including the detrimental voltage decay and mediocre rate capability,etc.Element doping can e ectively solve the above problems,but cause the loss of capacity.The introduction of appropriate defects can compensate the capacity loss;however,it will lead to structural mismatch and stress accumulation.Herein,a three-in-one method that combines cation–polyanion co-doping,defect construction,and stress engineering is pro-posed.The co-doped Na^(+)/SO_(4)^(2-)can stabilize the layer framework and enhance the capacity and voltage stability.The induced defects would activate more reac-tion sites and promote the electrochemical performance.Meanwhile,the unique alternately distributed defect bands and crystal bands structure can alleviate the stress accumulation caused by changes of cell parameters upon cycling.Consequently,the modified sample retains a capacity of 273 mAh g^(-1)with a high-capacity retention of 94.1%after 100 cycles at 0.2 C,and 152 mAh g^(-1)after 1000 cycles at 2 C,the corresponding voltage attenuation is less than 0.907 mV per cycle.展开更多
Effects of ultrasonic vibration(UV)and mechanical vibration(MV)on the Mn-rich phase modification and mechanical properties of Al−12Si−4Cu−1Ni−1Mg−2Mn piston alloys were investigated.The results show that the UV and UV...Effects of ultrasonic vibration(UV)and mechanical vibration(MV)on the Mn-rich phase modification and mechanical properties of Al−12Si−4Cu−1Ni−1Mg−2Mn piston alloys were investigated.The results show that the UV and UV+MV treatments can significantly refine and fragmentize the microstructures.In addition,UV treatment can significantly passivate the primary Mn-rich Al15Mn3Si2 intermetallics.The formation mechanisms of refinement and passivation of the grains and non-dendrite particles were discussed.Compared with the gravity die-cast alloys,the UV and UV+MV treated alloys exhibit improved tensile and creep resistance at room and elevated temperatures.These results can be attributed to the refinement of theα(Al)grains and the secondary intermetallics,the increased proportion of refined heat-resistant precipitates,and the formation of nano-sized Si particles.The ultimate tensile strength of the UV treated alloys at 350℃ exceeds that of commercial piston alloys.This indicates the high application potential of the developed piston alloys in density diesel engines.展开更多
We investigate the influence of Sb-doping on the martensitic transformation and magnetocaloric effect in Mn（50）Ni（40）Sn（10-x）Sbx（x = 1, 2, 3, and 4） alloys. All the prepared samples exhibit a B2-type structure...We investigate the influence of Sb-doping on the martensitic transformation and magnetocaloric effect in Mn（50）Ni（40）Sn（10-x）Sbx（x = 1, 2, 3, and 4） alloys. All the prepared samples exhibit a B2-type structure with the space group F m3 m at room temperature. The substitution of Sb increases the valence electron concentration and decreases the unit cell volume. As a result, the magnetostructural transformation shifts rapidly towards higher temperatures as x increases.The changes in magnetic entropy under different magnetic field variations are explored around this transformation. The isothermal magnetization curves exhibit typical metamagnetic behavior, indicating that the magnetostructural transformation can be induced by a magnetic field. The tunable martensitic transformation and magnetic entropy changes suggest that Mn（50）Ni（40）Sn（10-x）Sbx alloys are attractive candidates for applications in solid-state refrigeration.展开更多
The Li-and Mn-rich layered oxides(R-LNCM)are considered as promising cathode materials for high-energy density lithium-ion batteries(LIBs).However,the interface side reaction aggravates the voltage and capacity fading...The Li-and Mn-rich layered oxides(R-LNCM)are considered as promising cathode materials for high-energy density lithium-ion batteries(LIBs).However,the interface side reaction aggravates the voltage and capacity fading between cathode material and electrolyte at high voltage,which severely hinders the practical application of LIB s.Herein,lithium polyacrylate(LiPAA)as the binder and coating agent is applied to suppress the voltage and capacity fading of R-LNCM electrode.The flexible LiPAA layers with high elasticity are capable of impeding cathode cracks on the particle surface via mechanical stress relief.Thus,superior voltage and capacity fading suppression on R-LNCM electrode is finally achieved.As a result,LiPAA-R-LNCM cathode exhibits a remarkable specific capacity of 186 mA·h·g^(-1)with~73%retention at 1℃after 200cycles.Further,the corresponding average discharge potential is maintained to~3.1 V with only~0.4 V falling.展开更多
According to the news release from the Department of Land and Resources of Xinjiang Uygur Autonomous Region,the West Kunlun Maerkansu Mn ore prospecting project financed by the Autonomous Region scored a major breakth...According to the news release from the Department of Land and Resources of Xinjiang Uygur Autonomous Region,the West Kunlun Maerkansu Mn ore prospecting project financed by the Autonomous Region scored a major breakthrough.Located in the Akto County。展开更多
基金support from the National Key Research and Development Program of China(No.2022YFB2502000)the National Natural Science Foundation of China(Grant Nos.52201277)+1 种基金the key program of the National Natural Science Foundation of China(Grant Nos.51831009)the National Outstanding Youth Foundation of China(No.52125104).
文摘Lithium and manganese-rich layered oxides(LMROs)have attracted extensive attention and are promising cathode materials for next-generation lithium ion batteries due to their high capacities and high energy densities.However,LMRO cathode suffers from severe capacity and voltage fading originating from irreversible surface oxygen evolution.Herein,we propose a facile redox couple strategy by introducing nitroxyl radicals species to regulate the surface anionic redox reaction of LMRO cathode.Differential electrochemical mass spectroscopy,X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analyses demonstrate that during charge process,the peroxide ion O_(2)^(2−)on the surface generated from the oxidation of lattice O^(2-)could be reduced back to stable O^(2-)by redox couple in time,thus avoiding oxygen evolution and structure degradation,as well as enhancing bulk oxygen redox activity.The enhanced LMRO electrode delivers a high capacity of 220.3 mAh g^(−1)at 1 C.An excellent cycling stability with a capacity retention of 94.4%is achieved after 500 cycles,as well as a suppressed voltage decay with only 1.12 mV per cycle.
基金the Natural Science Foundation of Fujian Province of China(Nos.2019J06003 and 2020J05014)the National Natural Science Foundation of China(Nos.51931006 and 51871188)+4 种基金the National Key R&D Program of China(No.2016YFA0202602)Guangdong Basic and Applied Basic Research Foundation(Nos.2021A1515010139 and 2019A1515011070)the Science and Technology Planning Projects of Fujian Province,China(No.2020H0005)the Fundamental Research Funds for the Central Universities of China(Nos.20720200068 and 20720190013)the“Double-First Class”Foundation of Materials Intelligent Manufacturing Discipline of Xiamen University。
文摘Li-and Mn-rich(LMR)cathode materials have received tremendous attention due to the highly reversible specific capacity(>250 m Ah·g^(-1)).In the analysis of its crystal structure,the two-phase composite model gains increasing acceptance,and the phase transition behaviors in LMR cathode materials have been extensively studied.Herein,the structure controversy of LMR cathode materials,and the mechanisms of phase transition are summarized.Particularly,the causes of initiating or accelerating the phase transition of LMR cathode materials have been summarized into three main driving forces,i.e.,the electrochemical driving force,the component driving force and the thermodynamic driving force.Additionally,the applications of phase transition behavior in improving the electrochemical performance of LMR cathode materials,including the construction of spinel surface coating and spinel/layered hetero-structure are discussed.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51931006 and 51871188)the National Key R&D Program of China(No.2016YFA0202602)+4 种基金the Science and Technology Plan-ning Projects of Fujian Province of China(Grant No.2020H0005)the Natural Science Foundation of Fujian Province of China(No.2020J05014)Guangdong Basic and Applied Basic Research Foundation(Nos.2021A1515010139 and 2019A1515011070)the Fundamental Research Funds for the Central Universities of China(Xiamen University:Nos.20720200068,20720190013,and 20720200080)the“Double-First Class”Foundation of Mate-rials Intelligent Manufacturing Discipline of Xiamen University。
文摘There are plenty of issues need to be solved before the practi-cal application of Li-and Mn-rich cathodes,including the detrimental voltage decay and mediocre rate capability,etc.Element doping can e ectively solve the above problems,but cause the loss of capacity.The introduction of appropriate defects can compensate the capacity loss;however,it will lead to structural mismatch and stress accumulation.Herein,a three-in-one method that combines cation–polyanion co-doping,defect construction,and stress engineering is pro-posed.The co-doped Na^(+)/SO_(4)^(2-)can stabilize the layer framework and enhance the capacity and voltage stability.The induced defects would activate more reac-tion sites and promote the electrochemical performance.Meanwhile,the unique alternately distributed defect bands and crystal bands structure can alleviate the stress accumulation caused by changes of cell parameters upon cycling.Consequently,the modified sample retains a capacity of 273 mAh g^(-1)with a high-capacity retention of 94.1%after 100 cycles at 0.2 C,and 152 mAh g^(-1)after 1000 cycles at 2 C,the corresponding voltage attenuation is less than 0.907 mV per cycle.
基金the National Natural Science Foundation of China(No.52265043)Science and Technology Plan,Guizhou Province,China(No.ZK2021(267))+2 种基金Technology Achievements Application and Industrialization Project,Guizhou Province,China(No.2021(067))Cultivation Project of Guizhou University,China(No.2019(23))Lastly,we thank the Shanghai Synchrotron Radiation Facility(SSRF)for providing the synchrotron radiation beamtime.
文摘Effects of ultrasonic vibration(UV)and mechanical vibration(MV)on the Mn-rich phase modification and mechanical properties of Al−12Si−4Cu−1Ni−1Mg−2Mn piston alloys were investigated.The results show that the UV and UV+MV treatments can significantly refine and fragmentize the microstructures.In addition,UV treatment can significantly passivate the primary Mn-rich Al15Mn3Si2 intermetallics.The formation mechanisms of refinement and passivation of the grains and non-dendrite particles were discussed.Compared with the gravity die-cast alloys,the UV and UV+MV treated alloys exhibit improved tensile and creep resistance at room and elevated temperatures.These results can be attributed to the refinement of theα(Al)grains and the secondary intermetallics,the increased proportion of refined heat-resistant precipitates,and the formation of nano-sized Si particles.The ultimate tensile strength of the UV treated alloys at 350℃ exceeds that of commercial piston alloys.This indicates the high application potential of the developed piston alloys in density diesel engines.
基金supported by the National Natural Science Foundation of China(Grant Nos.51271093,51571121,11604148,and 51601092)the Fundamental Research Funds for the Central Universities,China(Grant Nos.30920140111010,30916011344,and 30916011345)+4 种基金Jiangsu Natural Science Foundation for Distinguished Young Scholars,China(Grant No.BK20140035)China Postdoctoral Science Foundation(Grant No.2016M591851)the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK20160833 and BK20160829)Qing Lan Project,Six Talent Peaks Project in Jiangsu Province,Chinathe Priority Academic Program Development of Jiangsu Higher Education Institutions,China
文摘We investigate the influence of Sb-doping on the martensitic transformation and magnetocaloric effect in Mn（50）Ni（40）Sn（10-x）Sbx（x = 1, 2, 3, and 4） alloys. All the prepared samples exhibit a B2-type structure with the space group F m3 m at room temperature. The substitution of Sb increases the valence electron concentration and decreases the unit cell volume. As a result, the magnetostructural transformation shifts rapidly towards higher temperatures as x increases.The changes in magnetic entropy under different magnetic field variations are explored around this transformation. The isothermal magnetization curves exhibit typical metamagnetic behavior, indicating that the magnetostructural transformation can be induced by a magnetic field. The tunable martensitic transformation and magnetic entropy changes suggest that Mn（50）Ni（40）Sn（10-x）Sbx alloys are attractive candidates for applications in solid-state refrigeration.
基金financial support from the National Key Research and Development Program of China (Grant No.2021YFB2400401)Project of Development Fund of Key Laboratory of Green Plateau and Ecological Community of Qinghai Province (Grant No.SL-2020-019)。
文摘The Li-and Mn-rich layered oxides(R-LNCM)are considered as promising cathode materials for high-energy density lithium-ion batteries(LIBs).However,the interface side reaction aggravates the voltage and capacity fading between cathode material and electrolyte at high voltage,which severely hinders the practical application of LIB s.Herein,lithium polyacrylate(LiPAA)as the binder and coating agent is applied to suppress the voltage and capacity fading of R-LNCM electrode.The flexible LiPAA layers with high elasticity are capable of impeding cathode cracks on the particle surface via mechanical stress relief.Thus,superior voltage and capacity fading suppression on R-LNCM electrode is finally achieved.As a result,LiPAA-R-LNCM cathode exhibits a remarkable specific capacity of 186 mA·h·g^(-1)with~73%retention at 1℃after 200cycles.Further,the corresponding average discharge potential is maintained to~3.1 V with only~0.4 V falling.
文摘According to the news release from the Department of Land and Resources of Xinjiang Uygur Autonomous Region,the West Kunlun Maerkansu Mn ore prospecting project financed by the Autonomous Region scored a major breakthrough.Located in the Akto County。
基金Project(U1034001)supported by the Natural Science Foundation of Guangdong Province,ChinaProject(2011BAE21B00)supported by the National Key Technology R & D Program during the12th Five-year Plan of ChinaProjects(2009A090100026,2008A010300003)supported by Key Projects of Science and Technology of Guangdong Province,China
