With the increasing spotlight in electric vehicles,there is a growing demand for high-energy-density batteries to enhance driving range.Consequently,several studies have been conducted on high-energy-density LiNi_(x)C...With the increasing spotlight in electric vehicles,there is a growing demand for high-energy-density batteries to enhance driving range.Consequently,several studies have been conducted on high-energy-density LiNi_(x)Co_(y)Mn_(z)O_(2)cathodes.However,there is a limit to permanent performance deterioration because of side reactions caused by moisture in the atmosphere and continuous microcracks during cycling as the Ni content to express high energy increases and the content of Mn and Co that maintain structural and electrochemical stabilization decreases.The direct modification of the surface and bulk regions aims to enhance the capacity and long-term performance of high-Ni cathode materials.Therefore,an efficient modification requires a study based on a thorough understanding of the degradation mechanisms in the surface and bulk region.In this review,a comprehensive analysis of various modifications,including doping,coating,concentration gradient,and single crystals,is conducted to solve degradation issues along with an analysis of the overall degradation mechanism occurring in high-Ni cathode materials.It also summarizes recent research developments related to the following modifications,aims to provide notable points and directions for post-studies,and provides valuable references for the commercialization of stable high-energy-density cathode materials.展开更多
High-Ni layered oxide cathodes hold a great promise for fabricating highenergy lithium-ion batteries.However,the oxygen evolution during cycling is a crucial factor in the structure deterioration,potential change,and ...High-Ni layered oxide cathodes hold a great promise for fabricating highenergy lithium-ion batteries.However,the oxygen evolution during cycling is a crucial factor in the structure deterioration,potential change,and capacity decay of cathodes,limiting the commercial application of high-Ni(Ni>0.9)layered oxides in batteries.Herein,we demonstrate a feasible approach to enhance the stability of oxygen framework,through the surface oxygen immobilization with yttrium and bulk oxygen stabilization with aluminum in high-Ni layered oxides.As expected,benefiting from the oxygen-stabilized framework,the bulk structure deterioration,and interfacial parasitic reaction are mitigated obviously during battery operation,along with the improved thermal stability of cathode.Correspondingly,the as-prepared high-Ni oxide delivers high reversible capacity,impressive cycle ability,and low potential polarization upon cycling.Such significant improvement on the electrochemical performance is primarily attributed to the strong oxygen affinities of both yttrium at the surface layer and aluminum in the bulk,which synergistically stabilizes the oxygen framework of high-Ni oxide via raising the energy barrier for oxygen evolution.Therefore,building the stable oxygen framework is critical for enhancing the energy density output,cycle operation,and thermal stability of high-Ni oxide cathodes.展开更多
Advanced cathode materials have been considered as the key to significantly improve the energy density of lithium-ion batteries(LIBs).High-Ni layer-structured cathodes,especially with Ni atomic content above 0.9(LiN1_...Advanced cathode materials have been considered as the key to significantly improve the energy density of lithium-ion batteries(LIBs).High-Ni layer-structured cathodes,especially with Ni atomic content above 0.9(LiN1_(x)M_(1-x)O_(2),x≥0.9),exhibit high capacity to be commercially available in electric vehicles(EVs).However,the intrinsic structure instability of high-Ni materials and the negative impacts severely restrict their further applic ation.In addition,Co has various effective efforts to stabilize the layered structure.Nevertheless,due to the high cost of Co,it is required to be replaced.Therefore,modification methods on increasing the stability of high-Ni cathode with the reduction of Co content have been widely investigated.In this review,we summarized various effective research progresses and several potential modification strategies of Cofree/Co-poor layered c athodes with Ni content over 0.9.The challenges and development opportunities of high-Ni,Cofree/Co-poor cathodes are further overviewed to meet the future commercial energy demands.展开更多
文摘With the increasing spotlight in electric vehicles,there is a growing demand for high-energy-density batteries to enhance driving range.Consequently,several studies have been conducted on high-energy-density LiNi_(x)Co_(y)Mn_(z)O_(2)cathodes.However,there is a limit to permanent performance deterioration because of side reactions caused by moisture in the atmosphere and continuous microcracks during cycling as the Ni content to express high energy increases and the content of Mn and Co that maintain structural and electrochemical stabilization decreases.The direct modification of the surface and bulk regions aims to enhance the capacity and long-term performance of high-Ni cathode materials.Therefore,an efficient modification requires a study based on a thorough understanding of the degradation mechanisms in the surface and bulk region.In this review,a comprehensive analysis of various modifications,including doping,coating,concentration gradient,and single crystals,is conducted to solve degradation issues along with an analysis of the overall degradation mechanism occurring in high-Ni cathode materials.It also summarizes recent research developments related to the following modifications,aims to provide notable points and directions for post-studies,and provides valuable references for the commercialization of stable high-energy-density cathode materials.
基金supported by the National Key Research and Development Program(2016YFB0100500)the Fundamental Research Funds for the Central Universities of China.
文摘High-Ni layered oxide cathodes hold a great promise for fabricating highenergy lithium-ion batteries.However,the oxygen evolution during cycling is a crucial factor in the structure deterioration,potential change,and capacity decay of cathodes,limiting the commercial application of high-Ni(Ni>0.9)layered oxides in batteries.Herein,we demonstrate a feasible approach to enhance the stability of oxygen framework,through the surface oxygen immobilization with yttrium and bulk oxygen stabilization with aluminum in high-Ni layered oxides.As expected,benefiting from the oxygen-stabilized framework,the bulk structure deterioration,and interfacial parasitic reaction are mitigated obviously during battery operation,along with the improved thermal stability of cathode.Correspondingly,the as-prepared high-Ni oxide delivers high reversible capacity,impressive cycle ability,and low potential polarization upon cycling.Such significant improvement on the electrochemical performance is primarily attributed to the strong oxygen affinities of both yttrium at the surface layer and aluminum in the bulk,which synergistically stabilizes the oxygen framework of high-Ni oxide via raising the energy barrier for oxygen evolution.Therefore,building the stable oxygen framework is critical for enhancing the energy density output,cycle operation,and thermal stability of high-Ni oxide cathodes.
基金financially supported by the National Natural Science Foundation of China(Nos.22109091 and 91963113)。
文摘Advanced cathode materials have been considered as the key to significantly improve the energy density of lithium-ion batteries(LIBs).High-Ni layer-structured cathodes,especially with Ni atomic content above 0.9(LiN1_(x)M_(1-x)O_(2),x≥0.9),exhibit high capacity to be commercially available in electric vehicles(EVs).However,the intrinsic structure instability of high-Ni materials and the negative impacts severely restrict their further applic ation.In addition,Co has various effective efforts to stabilize the layered structure.Nevertheless,due to the high cost of Co,it is required to be replaced.Therefore,modification methods on increasing the stability of high-Ni cathode with the reduction of Co content have been widely investigated.In this review,we summarized various effective research progresses and several potential modification strategies of Cofree/Co-poor layered c athodes with Ni content over 0.9.The challenges and development opportunities of high-Ni,Cofree/Co-poor cathodes are further overviewed to meet the future commercial energy demands.
文摘2024年春季(3—5月)我国平均降水量为163 mm,为1961年以来历史同期第六多,4—5月东部地区旱涝灾害并重,华南和江南大部降水较常年同期偏多,尤其是华南大部降水偏多5成以上,多次暴雨过程造成部分地区发生洪涝;而黄淮、江淮北部降水显著偏少,春季后期干旱迅速发展。春季“华南涝、黄淮旱”的形成与东亚大气环流关键系统异常及其季节内阶段性变化密切相关。4月异常偏强、偏南的西北太平洋副热带高压和低层850 hPa偏强的西北太平洋反气旋为华南和江南提供了有利的水汽输送条件,导致南方地区发生多次强降水过程;而黄淮干旱主要受4—5月持续偏强的朝鲜半岛-日本海高压(小笠原高压)和偏南的西北太平洋副热带高压共同影响。此外,春季El Ni o衰减和热带印度洋海温异常偏暖有助于激发异常偏强的西北太平洋反气旋,是我国南方强降水发生的重要海洋外强迫背景。
