As a novel class of high-voltage cathode materials,spinel lithium transition metal oxides have been faced with demerits including pronounced structural instability caused by Jahn-Teller distortion(especially at the lo...As a novel class of high-voltage cathode materials,spinel lithium transition metal oxides have been faced with demerits including pronounced structural instability caused by Jahn-Teller distortion(especially at the lower voltage region)and severe capacity degradation despite their intriguing electrochemical properties.To extend their functionalities as broad-voltage cathodes,the sacrificial template method has been regarded as a promising way to realize structural and compositional control for desirable electrochemical behaviors.Herein,we report a synthetic protocol to directionally prepare Li Co Mn O_(4)(LCMO)using carboxyl-based metal-organic frameworks(MOFs)as self-sacrificing templates.Impressively,LCMO derived from Co Mn-BDC(H_(2)BDC=1,4-benzenedicarboxylate)displays superior electrochemical performances with a specific capacity of 151.6 m Ah g^(-1)at 1 C(150 m A g^(-1))after 120 cycles and excellent rate capacity of 91.9 m Ah g^(-1)at 10 C due to the morphology control,microstructural modulation,and atomic manipulation of the MOF precursor.Bestowed by the optimized atomic and electronic structure,abundant oxygen vacancies,and the nanostructure retained from MOF precursors,LCMO materials display extraordinary electrochemical properties,which have been extensively verified by both experimental and theoretical studies.This work not only provides guidelines for the directional design of spinel materials at molecular and atomic levels but also sheds light on the practical use of LIBs with broad range voltage.展开更多
In order to overcome the drawbacks of 3RRR non-redundant parallel manipulators,a redundantly actuated planar parallel manipulator,the 4RRR manipulator,was examined.In the current study,three types of workspace were an...In order to overcome the drawbacks of 3RRR non-redundant parallel manipulators,a redundantly actuated planar parallel manipulator,the 4RRR manipulator,was examined.In the current study,three types of workspace were analyzed.In the analysis of the reachable workspace,the shape of the workspace of 4RRR PMs was illustrated,and the relationship between the parameters of parallel mechanisms（PMs） and this kind of workspace was discussed.In the analysis of the m-orientation workspace,a procedure for calculating this type of workspace was presented,and the relationship between this type of workspace and the requirement of rotational displacement was revealed.In the analysis of the nonsingular workspace,the singularity of 4RRR PMs was discussed,the boundary of the singularity was illustrated,and a scheme to maximize the nonsingular workspace was presented.Depicting the properties of 4RRR PMs from different perspectives,the analyses of these three kinds of workspace can serve as helpful references for the structure design and mechanism control of 4RRR PMs.展开更多
基金the financial support from the Special Funds for the Cultivation of Guangdong College Students’Scientific and Technological Innovation(“Climbing Program”Special Funds,pdjh2022b0135)the Open Fund of Energy and Materials Chemistry Joint Laboratory of SCNU and TINCI(SCNU-TINCI202207)。
文摘As a novel class of high-voltage cathode materials,spinel lithium transition metal oxides have been faced with demerits including pronounced structural instability caused by Jahn-Teller distortion(especially at the lower voltage region)and severe capacity degradation despite their intriguing electrochemical properties.To extend their functionalities as broad-voltage cathodes,the sacrificial template method has been regarded as a promising way to realize structural and compositional control for desirable electrochemical behaviors.Herein,we report a synthetic protocol to directionally prepare Li Co Mn O_(4)(LCMO)using carboxyl-based metal-organic frameworks(MOFs)as self-sacrificing templates.Impressively,LCMO derived from Co Mn-BDC(H_(2)BDC=1,4-benzenedicarboxylate)displays superior electrochemical performances with a specific capacity of 151.6 m Ah g^(-1)at 1 C(150 m A g^(-1))after 120 cycles and excellent rate capacity of 91.9 m Ah g^(-1)at 10 C due to the morphology control,microstructural modulation,and atomic manipulation of the MOF precursor.Bestowed by the optimized atomic and electronic structure,abundant oxygen vacancies,and the nanostructure retained from MOF precursors,LCMO materials display extraordinary electrochemical properties,which have been extensively verified by both experimental and theoretical studies.This work not only provides guidelines for the directional design of spinel materials at molecular and atomic levels but also sheds light on the practical use of LIBs with broad range voltage.
基金Supported by the National Natural Science Foundation of China(No 50775117)the National Key Basic Research and Development (973) Program of China (No 2004CB318000)
文摘In order to overcome the drawbacks of 3RRR non-redundant parallel manipulators,a redundantly actuated planar parallel manipulator,the 4RRR manipulator,was examined.In the current study,three types of workspace were analyzed.In the analysis of the reachable workspace,the shape of the workspace of 4RRR PMs was illustrated,and the relationship between the parameters of parallel mechanisms（PMs） and this kind of workspace was discussed.In the analysis of the m-orientation workspace,a procedure for calculating this type of workspace was presented,and the relationship between this type of workspace and the requirement of rotational displacement was revealed.In the analysis of the nonsingular workspace,the singularity of 4RRR PMs was discussed,the boundary of the singularity was illustrated,and a scheme to maximize the nonsingular workspace was presented.Depicting the properties of 4RRR PMs from different perspectives,the analyses of these three kinds of workspace can serve as helpful references for the structure design and mechanism control of 4RRR PMs.
