Defective layered Mn-based materials were synthesized by Li/Na ion exchange to improve their electrochemical activity and Coulombic efficiency.The annealing temperature of the Na precursors was important to control th...Defective layered Mn-based materials were synthesized by Li/Na ion exchange to improve their electrochemical activity and Coulombic efficiency.The annealing temperature of the Na precursors was important to control the P3-P2 phase transition,which directly affected the structure and electrochemical characteristics of the final products obtained by ion exchange.The O3-Li_(0.78)[Li_(0.25)Fe_(0.075)Mn_(0.675)]O_(δ) cathode made from a P3-type precursor calcined at 700℃ was analyzed using X-ray photoelectron spectrometry and electron paramagnetic resonance.The results showed that the presence of abundant trivalent manganese and defects resulted in a discharge capacity of 230 mAh/g with an initial Coulombic efficiency of about 109%.Afterward,galvanostatic intermittent titration was performed to examine the Li^(+) ion diffusion coefficients,which affected the reversible capacity.First principles calculations suggested that the charge redistribution induced by oxygen vacancies(OV_(s))greatly affected the local Mn coordination environment and enhanced the structural activity.Moreover,the Li-deficient cathode was a perfect match for the pre-lithiation anode,providing a novel approach to improve the initial Coulombic efficiency and activity of Mn-based materials in the commercial application.展开更多
Under the key competence,high school English teachers shall strengthen the use of mind mappings when developing reading and teaching activities,thus making English reading,and teaching more intuitive and logical.In th...Under the key competence,high school English teachers shall strengthen the use of mind mappings when developing reading and teaching activities,thus making English reading,and teaching more intuitive and logical.In this way,high school students can be more interested in English,and more active and autonomous in improving their English reading ability.This article explores and analyzes the problems existing in high school English reading teaching at current stage,and puts forward an effective strategy for using mind mappings to develop high school English reading and teaching under the key competence,with the hope of facilitating the development of English reading and teaching in high school.展开更多
Functional mesoporous materials,based on IUPAC,are a type of porous materials with a uniform pore size ranging from 2 to 50 nm.In the 1980s,the existing zeolites or microporous materials with small pore sizes(less tha...Functional mesoporous materials,based on IUPAC,are a type of porous materials with a uniform pore size ranging from 2 to 50 nm.In the 1980s,the existing zeolites or microporous materials with small pore sizes(less than 1.2 nm)have some limitations in practical applications,especially for large molecule conversion and transfer.Inspired by these motivations,the exploration of mesoporous materials has been widely sparked.From the early 1990s,the mesoporous materials including or-dered M41S[1]mesoporous silicate molecular sieves and large-pore mesoporous silica SBA-15[2]were prepared when templated by the quaternary ammonium cationic surfactant or the amphiphilic triblock copolymer micelles.The high thermal stability of such porous materials and good repeatability of methods have aroused widespread interest in both academic and industrial domains.展开更多
Hollow TiO2-x porous microspheres consisted of numerous well-crystalline nanocrystals with superior structural integrity and robust hollow interior were synthesized by a facile sol-gel template-assisted approach and t...Hollow TiO2-x porous microspheres consisted of numerous well-crystalline nanocrystals with superior structural integrity and robust hollow interior were synthesized by a facile sol-gel template-assisted approach and two-step carbonprotected calcination method, together with hydrogenation treatment. They exhibit a uniform diameter of -470 nm with a thin porous wall shell of -50 nm in thickness. The Brunauer-Emmett-Teller （BET） surface area and pore volume are -19 m2/g and 0.07 crnB/g, respectively. These hollow TiOR_x porous microspheres demonstrated excellent lithium storage performance with stable capacity retention for over 300 cycles （a high capacity of 151 mAh/g can be obtained up to 300 cycles at I C, retaining 81.6% of the initial capacity of 185 mAh/g） and enhanced rate capability even up to 10 C （222, 192, 121, and 92.1 mAh/g at current rates of 0.5, 1, 5, and 10 C, respectively）. The intrinsic increased conductivity of the hydrogenated TiO2 microspheres and their robust hollow structure benefidal for lithium ion-electron diffusion and mitigating the structural strain synergistically contribute to the remarkable improvements in their cycling stability and rate performance.展开更多
基金The Beijing Municipal Education Commission(KZ201910005003)supported this work。
文摘Defective layered Mn-based materials were synthesized by Li/Na ion exchange to improve their electrochemical activity and Coulombic efficiency.The annealing temperature of the Na precursors was important to control the P3-P2 phase transition,which directly affected the structure and electrochemical characteristics of the final products obtained by ion exchange.The O3-Li_(0.78)[Li_(0.25)Fe_(0.075)Mn_(0.675)]O_(δ) cathode made from a P3-type precursor calcined at 700℃ was analyzed using X-ray photoelectron spectrometry and electron paramagnetic resonance.The results showed that the presence of abundant trivalent manganese and defects resulted in a discharge capacity of 230 mAh/g with an initial Coulombic efficiency of about 109%.Afterward,galvanostatic intermittent titration was performed to examine the Li^(+) ion diffusion coefficients,which affected the reversible capacity.First principles calculations suggested that the charge redistribution induced by oxygen vacancies(OV_(s))greatly affected the local Mn coordination environment and enhanced the structural activity.Moreover,the Li-deficient cathode was a perfect match for the pre-lithiation anode,providing a novel approach to improve the initial Coulombic efficiency and activity of Mn-based materials in the commercial application.
文摘Under the key competence,high school English teachers shall strengthen the use of mind mappings when developing reading and teaching activities,thus making English reading,and teaching more intuitive and logical.In this way,high school students can be more interested in English,and more active and autonomous in improving their English reading ability.This article explores and analyzes the problems existing in high school English reading teaching at current stage,and puts forward an effective strategy for using mind mappings to develop high school English reading and teaching under the key competence,with the hope of facilitating the development of English reading and teaching in high school.
基金supported by the National Natural Science Foundation of China(22305132)the“Junma”Program of Inner Mongolia University(10000-23112101/045)the Inner Mongolia Natural Science Foundation Youth Fund(2023QN02014).
文摘Functional mesoporous materials,based on IUPAC,are a type of porous materials with a uniform pore size ranging from 2 to 50 nm.In the 1980s,the existing zeolites or microporous materials with small pore sizes(less than 1.2 nm)have some limitations in practical applications,especially for large molecule conversion and transfer.Inspired by these motivations,the exploration of mesoporous materials has been widely sparked.From the early 1990s,the mesoporous materials including or-dered M41S[1]mesoporous silicate molecular sieves and large-pore mesoporous silica SBA-15[2]were prepared when templated by the quaternary ammonium cationic surfactant or the amphiphilic triblock copolymer micelles.The high thermal stability of such porous materials and good repeatability of methods have aroused widespread interest in both academic and industrial domains.
基金This work was supported by the National Basic Research Program of China （Nos. 2012CB224805 and 2013CB934104）, Shanghai Sci. ＆ Tech. Committee （No. 14JC1400700）, the National Natural Science Foundation of China （Nos. 21210004, 51372041, 51422202 and U1463206）, the innovation program （No. 13ZZ004）, the ＂Shu Guang＂ Project （No. 13SG02） supported by Shanghai Municipal Education Commission, Qatar University startup grant # QUSG-CAS-MST-14／15-1, and National Youth Top Talent Support Program of National High-level Personnel of Special Support Program. We extend our appreciation to the Deanship of Scientific Research at King Saud University for funding the work through the research group project No RGP-227.
文摘Hollow TiO2-x porous microspheres consisted of numerous well-crystalline nanocrystals with superior structural integrity and robust hollow interior were synthesized by a facile sol-gel template-assisted approach and two-step carbonprotected calcination method, together with hydrogenation treatment. They exhibit a uniform diameter of -470 nm with a thin porous wall shell of -50 nm in thickness. The Brunauer-Emmett-Teller （BET） surface area and pore volume are -19 m2/g and 0.07 crnB/g, respectively. These hollow TiOR_x porous microspheres demonstrated excellent lithium storage performance with stable capacity retention for over 300 cycles （a high capacity of 151 mAh/g can be obtained up to 300 cycles at I C, retaining 81.6% of the initial capacity of 185 mAh/g） and enhanced rate capability even up to 10 C （222, 192, 121, and 92.1 mAh/g at current rates of 0.5, 1, 5, and 10 C, respectively）. The intrinsic increased conductivity of the hydrogenated TiO2 microspheres and their robust hollow structure benefidal for lithium ion-electron diffusion and mitigating the structural strain synergistically contribute to the remarkable improvements in their cycling stability and rate performance.
