Lithium-rich manganese-based cathodes(LR)are valuable cathode materials for the next generation of lithium-ion batteries(LIBs)with high-energy density.However,the fast voltage/capacity decay on cycling is the major ob...Lithium-rich manganese-based cathodes(LR)are valuable cathode materials for the next generation of lithium-ion batteries(LIBs)with high-energy density.However,the fast voltage/capacity decay on cycling is the major obstacle for the practical application induced by the less-than-ideal anionic redox reactions and structure distortion.Herein,in order to tackle these challenges,a perovskite-like La_(2)Li_(0.5)Co_(0.5)O_(4)(LLCO)material is selected as protective surface to stabilize the Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)(LR)substrate through wet chemical coating method.Versatile structure/phase characterizations and electrochemical tests exhibit that the LLCO can not only minish the oxygen evolution and enhance the structure stability,but also restrain the electrolyte corrosion and increase the mechanical strength of cathode materials.Moreover,the coated LLCO with high electronic/ionic conductivity dramatically accelerates the energy storage kinetic,thereby displaying the improved rate performance.Specifically,the optimized LR@LLCO sample(1LLCO)exhibits a high capacity of 250.6 mAh·g^(-1)after 100 cycles at 0.1 C and excellent capacity retention of 82.6%after 200 cycles at 2 C.This work provides a new idea for the modification of LR cathodes toward commercial high-performance LIBs.展开更多
光生电荷的分离和转移被认为是影响BiVO_(4)基光阳极光电性能的核心因素之一.本文设计了在BiVO_(4)光阳极与析氧助催化剂之间插入空穴提取层的方法.Cu_(2)O作为空穴提取层引入到助催化剂层(FeOOH/NiOOH)和BiVO_(4)之间,可以有效优化空...光生电荷的分离和转移被认为是影响BiVO_(4)基光阳极光电性能的核心因素之一.本文设计了在BiVO_(4)光阳极与析氧助催化剂之间插入空穴提取层的方法.Cu_(2)O作为空穴提取层引入到助催化剂层(FeOOH/NiOOH)和BiVO_(4)之间,可以有效优化空穴的迁移路径,延长光生空穴的寿命,从而提高电极的光电化学性能.与BiVO_(4)相比,调整后的BiVO_(4)/Cu_(2)O/FeOOH/NiOOH光阳极的电荷分离效率从70.6%提高到了92.0%.此外,该光阳极在1.23 VRHE(AM 1.5G照明下)下,还显示出了3.85 mA cm^(-2)的高光电流密度,是BiVO_(4)的2.77倍.我们的研究结果表明,电沉积Cu_(2)O空穴提取层是一种简单且可扩展的方法,能够有效提高BiVO_(4)的光电活性,可用于太阳能驱动水分解领域.展开更多
Proton exchange membrane fuel cells(PEMFCs),which have the advantages of high-power density,zero emission,and low noise,are considered ideal electrochemical conversion systems for converting hydrogen(H2)and oxy-gen(O_...Proton exchange membrane fuel cells(PEMFCs),which have the advantages of high-power density,zero emission,and low noise,are considered ideal electrochemical conversion systems for converting hydrogen(H2)and oxy-gen(O_(2))/air into electricity.However,the oxygen reduction reaction(ORR),which is accompanied by multiple electrons,results in voltage loss and low conversion efficiency of PEMFCs.Currently,PEMFCs mainly use high-load precious platinum(Pt)to promote the ORR process;however,the high cost of Pt hinders the widespread commercialization of PEMFCs.Over the past few years,metal-nitrogen-carbon single-atom catalysts(M-N-C SACs)have attracted considerable attention and have been recognized as potential Pt-based catalysts owing to their outstanding ORR activity.This review briefly introduces the components of PEMFCs.Second,we discuss the catalytic mechanisms of the M-N-C SACs for the ORR.Third,the latest advances in noble,non-noble,and heteroatom-doped M-N-C SACs used as ORR and PEMFCs cathode catalysts are systematically reviewed.In sum-mary,we have outlined the current challenges and proposed a future perspective of M-N-C SACs for PEMFCs cathodes.展开更多
基金This work was supported by the National Natural Science Foundation of China(Nos.21878201 and 22008165)the Natural Science Foundation of Shanxi Province(No.20210302124211)+2 种基金the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(No.2021L042)the Foundation of Taiyuan University of Technology(No.2022QN022)the 7th Youth Talent Support Program of Shanxi Province.
文摘Lithium-rich manganese-based cathodes(LR)are valuable cathode materials for the next generation of lithium-ion batteries(LIBs)with high-energy density.However,the fast voltage/capacity decay on cycling is the major obstacle for the practical application induced by the less-than-ideal anionic redox reactions and structure distortion.Herein,in order to tackle these challenges,a perovskite-like La_(2)Li_(0.5)Co_(0.5)O_(4)(LLCO)material is selected as protective surface to stabilize the Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)(LR)substrate through wet chemical coating method.Versatile structure/phase characterizations and electrochemical tests exhibit that the LLCO can not only minish the oxygen evolution and enhance the structure stability,but also restrain the electrolyte corrosion and increase the mechanical strength of cathode materials.Moreover,the coated LLCO with high electronic/ionic conductivity dramatically accelerates the energy storage kinetic,thereby displaying the improved rate performance.Specifically,the optimized LR@LLCO sample(1LLCO)exhibits a high capacity of 250.6 mAh·g^(-1)after 100 cycles at 0.1 C and excellent capacity retention of 82.6%after 200 cycles at 2 C.This work provides a new idea for the modification of LR cathodes toward commercial high-performance LIBs.
基金supported by the National Natural Science Foundation of China(22008165 and 21878201)the Natural Science Foundation of Shanxi Province(202303021211035)+1 种基金the 7th Youth Talent Support Program of Shanxi Provincethe Opening Project of Sichuan University of Science and Engineering,Material Corrosion and Protection Key Laboratory of Sichuan Province(2021CL22)。
文摘光生电荷的分离和转移被认为是影响BiVO_(4)基光阳极光电性能的核心因素之一.本文设计了在BiVO_(4)光阳极与析氧助催化剂之间插入空穴提取层的方法.Cu_(2)O作为空穴提取层引入到助催化剂层(FeOOH/NiOOH)和BiVO_(4)之间,可以有效优化空穴的迁移路径,延长光生空穴的寿命,从而提高电极的光电化学性能.与BiVO_(4)相比,调整后的BiVO_(4)/Cu_(2)O/FeOOH/NiOOH光阳极的电荷分离效率从70.6%提高到了92.0%.此外,该光阳极在1.23 VRHE(AM 1.5G照明下)下,还显示出了3.85 mA cm^(-2)的高光电流密度,是BiVO_(4)的2.77倍.我们的研究结果表明,电沉积Cu_(2)O空穴提取层是一种简单且可扩展的方法,能够有效提高BiVO_(4)的光电活性,可用于太阳能驱动水分解领域.
基金the National Natural Science Foundation of China(22008165,21878201)Natural Science Foundation of Shanxi Province(202303021211035,202203021212240)the 7th Youth Talent Support Program of Shanxi Province.
文摘Proton exchange membrane fuel cells(PEMFCs),which have the advantages of high-power density,zero emission,and low noise,are considered ideal electrochemical conversion systems for converting hydrogen(H2)and oxy-gen(O_(2))/air into electricity.However,the oxygen reduction reaction(ORR),which is accompanied by multiple electrons,results in voltage loss and low conversion efficiency of PEMFCs.Currently,PEMFCs mainly use high-load precious platinum(Pt)to promote the ORR process;however,the high cost of Pt hinders the widespread commercialization of PEMFCs.Over the past few years,metal-nitrogen-carbon single-atom catalysts(M-N-C SACs)have attracted considerable attention and have been recognized as potential Pt-based catalysts owing to their outstanding ORR activity.This review briefly introduces the components of PEMFCs.Second,we discuss the catalytic mechanisms of the M-N-C SACs for the ORR.Third,the latest advances in noble,non-noble,and heteroatom-doped M-N-C SACs used as ORR and PEMFCs cathode catalysts are systematically reviewed.In sum-mary,we have outlined the current challenges and proposed a future perspective of M-N-C SACs for PEMFCs cathodes.
