P2-type sodium layered oxide cathode (Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)P2-NNMO) has attracted great attention as a promising cathode material for sodium ion batteries because of its high specific capacity. However, this m...P2-type sodium layered oxide cathode (Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)P2-NNMO) has attracted great attention as a promising cathode material for sodium ion batteries because of its high specific capacity. However, this material suffers from a rapid capacity fade during high-voltage cycling. Several mechanisms have been proposed to explain the capacity fade, including intragranular fracture caused by the P2-O2 phase transion, surface structural change, and irreversible lattice oxygen release. Here we systematically investigated the morphological, structural, and chemical changes of P2-NNMO during high-voltage cycling using a variety of characterization techniques. It was found that the lattice distortion and crystal-plane buckling induced by the P2-O2 phase transition slowed down the Na-ion transport in the bulk and hindered the extraction of the Na ions. The sluggish kinetics was the main reason in reducing the accessible capacity while other interfacial degradation mechanisms played minor roles. Our results not only enabled a more complete understanding of the capacity-fading mechanism of P2-NNMO but also revealed the underlying correlations between lattice doping and the moderately improved cycle performance.展开更多
The self-assembly of DNA provides an attractive approach to understanding structural formation mechanism in living organisms and to assisting applications in materials chemistry.Herein,we investigated the effect of me...The self-assembly of DNA provides an attractive approach to understanding structural formation mechanism in living organisms and to assisting applications in materials chemistry.Herein,we investigated the effect of metal ions on chiral self-assembly of DNA through the synthesis of chiral mesostructured silica via self-assembly of metal ions,DNA,and silica source.31 types of multivalent cationic metal ions were found to induce formation of chiral impeller-like DNA-silica complexes due to the chiral stacking of DNA.The strength of the interaction between the metal ion and phosphate group of DNA was speculated for the chiral stacking of DNA due to close distance of adjacent DNA to assure mutual recognition.Theoretical calculations indicated that chiral packing of DNA depends on the stability of the bridging phosphate-metal ion-phosphate bonds of DNA based on electron delocalization in d-orbital conjugation of metal ions.展开更多
基金financial support from the National Natural Science Foundation of China (21938005, 21573147, 22005190, 22008154, 21872163)the Science & Technology Commission of Shanghai Municipality, the Natural Science Foundation of Shanghai (19DZ1205500, 19ZR1424600, 19ZR1475100)the Sichuan Science and Technology Program (2021JDRC0015 to L.S.L)。
文摘P2-type sodium layered oxide cathode (Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)P2-NNMO) has attracted great attention as a promising cathode material for sodium ion batteries because of its high specific capacity. However, this material suffers from a rapid capacity fade during high-voltage cycling. Several mechanisms have been proposed to explain the capacity fade, including intragranular fracture caused by the P2-O2 phase transion, surface structural change, and irreversible lattice oxygen release. Here we systematically investigated the morphological, structural, and chemical changes of P2-NNMO during high-voltage cycling using a variety of characterization techniques. It was found that the lattice distortion and crystal-plane buckling induced by the P2-O2 phase transition slowed down the Na-ion transport in the bulk and hindered the extraction of the Na ions. The sluggish kinetics was the main reason in reducing the accessible capacity while other interfacial degradation mechanisms played minor roles. Our results not only enabled a more complete understanding of the capacity-fading mechanism of P2-NNMO but also revealed the underlying correlations between lattice doping and the moderately improved cycle performance.
基金supported by the National Key Research and Development Program of China(No.2021YFA1200300,S.C.,2021YFA1500300,X.L.)the National Natural Science Foundation of China(No.21931008,S.C.,22072090 X.L,21991153 L.C.)the science foundation of the Shanghai Municipal science and Technology Commission(No.19JC1410300,S.C.).
文摘The self-assembly of DNA provides an attractive approach to understanding structural formation mechanism in living organisms and to assisting applications in materials chemistry.Herein,we investigated the effect of metal ions on chiral self-assembly of DNA through the synthesis of chiral mesostructured silica via self-assembly of metal ions,DNA,and silica source.31 types of multivalent cationic metal ions were found to induce formation of chiral impeller-like DNA-silica complexes due to the chiral stacking of DNA.The strength of the interaction between the metal ion and phosphate group of DNA was speculated for the chiral stacking of DNA due to close distance of adjacent DNA to assure mutual recognition.Theoretical calculations indicated that chiral packing of DNA depends on the stability of the bridging phosphate-metal ion-phosphate bonds of DNA based on electron delocalization in d-orbital conjugation of metal ions.
