Rational architecture design has turned out to be an effective strategy in improving the electrochemical performance of electrode materials for batteries.However,an elaborate structure that could simultaneously endow ...Rational architecture design has turned out to be an effective strategy in improving the electrochemical performance of electrode materials for batteries.However,an elaborate structure that could simultaneously endow active materials with promoted reaction reversibility,accelerated kinetic and restricted volume change still remains a huge challenge.Herein,a novel chemical interaction motivated structure design strategy has been proposed,and a chemically bonded Co(CO_(3))_(0.5)OH·0.11 H_(2)O@MXene(CoCH@MXene)layered-composite was fabricated for the first time.In such a composite,the chemical interaction between Co^(2+)and MXene drives the growth of smaller-sized CoCH crystals and the subsequent formation of interwoven CoCH wires sandwiched in-between MXene nanosheets.This unique layered structure not only encourages charge transfer for faster reaction dynamics,but buffers the volume change of CoCH during lithiation-delithiation process,owing to the confined crystal growth between conductive MXene layers with the help of chemical bonding.Besides,the sandwiched interwoven CoCH wires also prevent the stacking of MXene layers,further conducive to the electrochemical performance of the composite.As a result,the as-prepared CoCH@MXene anode demonstrates a high reversible capacity(903.1 mAh g^(-1)at 100 mA g^(-1))and excellent cycling stability(maintains 733.6 mAh g^(-1)at1000 mA g^(-1)after 500 cycles)for lithium ion batteries.This work highlights a novel concept of layerby-layer chemical interaction motivated architecture design for futuristic high performance electrode materials in energy storage systems.展开更多
This paper describes the work completed in a two-year research project designed to study the critical question about how CALL can be used to help learners develop their language and communication skills. The project i...This paper describes the work completed in a two-year research project designed to study the critical question about how CALL can be used to help learners develop their language and communication skills. The project involved students of two classes of English as a foreign language （EFL） taught by the author. One of the classes was integrated with CALL, and the other was a traditional instructor-led class. The data collected from the two classes have been analyzed by a combination of both the quantitative and qualitative procedures. The study shows that the CALL program is effective and if applied correctly, can be far more efficient than traditional language learning programs. Furthermore, the reasons for the positive change have been investigated.展开更多
基金financially supported by the National Natural Science Foundation of China(No.51933007,No.51673123 and No.22005346)the National Key R&D Program of China(No.2017YFE0111500)+1 种基金the State Key Laboratory of Polymer Materials Engineering(Grant No.:sklpme2020-1-02)Financial support provided by the Fundamental Research Funds for the Central Universities(No.YJ202118)。
文摘Rational architecture design has turned out to be an effective strategy in improving the electrochemical performance of electrode materials for batteries.However,an elaborate structure that could simultaneously endow active materials with promoted reaction reversibility,accelerated kinetic and restricted volume change still remains a huge challenge.Herein,a novel chemical interaction motivated structure design strategy has been proposed,and a chemically bonded Co(CO_(3))_(0.5)OH·0.11 H_(2)O@MXene(CoCH@MXene)layered-composite was fabricated for the first time.In such a composite,the chemical interaction between Co^(2+)and MXene drives the growth of smaller-sized CoCH crystals and the subsequent formation of interwoven CoCH wires sandwiched in-between MXene nanosheets.This unique layered structure not only encourages charge transfer for faster reaction dynamics,but buffers the volume change of CoCH during lithiation-delithiation process,owing to the confined crystal growth between conductive MXene layers with the help of chemical bonding.Besides,the sandwiched interwoven CoCH wires also prevent the stacking of MXene layers,further conducive to the electrochemical performance of the composite.As a result,the as-prepared CoCH@MXene anode demonstrates a high reversible capacity(903.1 mAh g^(-1)at 100 mA g^(-1))and excellent cycling stability(maintains 733.6 mAh g^(-1)at1000 mA g^(-1)after 500 cycles)for lithium ion batteries.This work highlights a novel concept of layerby-layer chemical interaction motivated architecture design for futuristic high performance electrode materials in energy storage systems.
文摘This paper describes the work completed in a two-year research project designed to study the critical question about how CALL can be used to help learners develop their language and communication skills. The project involved students of two classes of English as a foreign language （EFL） taught by the author. One of the classes was integrated with CALL, and the other was a traditional instructor-led class. The data collected from the two classes have been analyzed by a combination of both the quantitative and qualitative procedures. The study shows that the CALL program is effective and if applied correctly, can be far more efficient than traditional language learning programs. Furthermore, the reasons for the positive change have been investigated.
