Manganese-based oxide electrode materials suffer from severe Jahn-Teller(J-T)distortion,leading to severe cycle instability in sodium ion storage.However,it is difficult to adjust the electron at d orbitals exactly to...Manganese-based oxide electrode materials suffer from severe Jahn-Teller(J-T)distortion,leading to severe cycle instability in sodium ion storage.However,it is difficult to adjust the electron at d orbitals exactly to a low spin state to eliminate orbital degeneracy and suppress J-T distortion fundamentally.This article constructed concentration-controllable Mn/O coupled vacancy and amorphous network in Mn_(3)O_(4) and coated it with nitrogen-doped carbon aerogel(Mn_(3-x)O_(4-y)@NCA).The existence of Mn/O vacancies has been confirmed by scanning transmission electron microscopy(STEM)and positron annihilation lifetime spectroscopy(PALS).Atomic absorption spectroscopy(AAS)and X-ray photoelectron spectroscopy(XPS)determine the most optimal ratio of Mn/O vacancies for sodium ion storage is 1:2.Density functional theory(DFT)calculations prove that Mn/O coupled vacancies with the ratio of 1:2could exactly induce a low spin states and a d~4 electron configuration of Mn,suppressing the J-T distortion successfully.The abundant amorphous regions can shorten the transport distance of sodium ions,increase the electrochemically active sites and improve the pseudocapacitance response.From the synergetic effect of Mn/O coupled vacancies and amorphous regions,Mn_(3-x)O_(4-y)@NCA exhibits an energy density of 37.5 W h kg^(-1)and an ultra-high power density of 563 W kg^(-1)in an asymmetric supercapacitor.In sodium-ion batteries,it demonstrates high reversible capacity and exceptional cycling stability.This research presents a new method to improve the Na^(+)storage performance in manganese-based oxide,which is expected to be generalized to other structural distortion.展开更多
Aqueous rechargeable magnesium ion batteries(ARMBs) have obtained more attention due to the twoelectrons transfer nature, low cost and safety. However, the scarcity of cathode materials seriously hinders the developme...Aqueous rechargeable magnesium ion batteries(ARMBs) have obtained more attention due to the twoelectrons transfer nature, low cost and safety. However, the scarcity of cathode materials seriously hinders the development of ARMBs because of the unfavorable strong interaction between Mg^(2+) and cathode material. Herein, we choose a pre-treated spinel Mn_(3)O_(4) cathode for aqueous Mg^(2+) storage. The pretreatment in Na_(2)SO_(4) solution induces the grain refinement decorated with tortuous amorphous ion diffusion channels, facilitating the production of electrochemical reaction active sites and the diffusion of Mg^(2+), respectively, which achieve a(sub-)surface pseudocapacitance reaction between Mn(Ⅱ) and Mn(Ⅲ). As a result, the pre-treated Mn_(3)O_(4) cathode exhibits a package of optimal performances, i.e., a capacity of 98.9 m Ah g^(-1) and a high capacity retention rate of 99.4% after 2000 cycles. To the best of our knowledge, our work not only provides a new reaction mechanism of spinelMn_(3)O_(4) in aqueous batteries system,but also affords a high cycle stability electrode material for rechargeable Mg^(2+) energy storage.展开更多
Solid-solid surface adsorption of Eu2O3 on amorphous Al2O3 have been investigated by Mossbauer spectroscopy, X- ray diffraction analysis and laser Raman spectra (LRS). No X-ray diffraction peak of crystalline Eu2O3 ca...Solid-solid surface adsorption of Eu2O3 on amorphous Al2O3 have been investigated by Mossbauer spectroscopy, X- ray diffraction analysis and laser Raman spectra (LRS). No X-ray diffraction peak of crystalline Eu2O3 can be found for all samples studied. The LRS show that two peaks at 998 and 1051 cm-1 assigned to two-dimensional surface europium-oxygen species appear at Eu2O3 content of 18.7 wt%. The peak at 1068 cm-1 due to the surface species and another peak at 342cm-1 due to crystalline Eu2O3 content start to appear for the sample with an Eu2O3 content of 36.5 wt%. The dispersity of Eu2O3 on the surface of amorphous Al2O3 were compared with that of α-Al2O3,η-Al2O3 and SiO2 gel. The results of these studies indicate that the structure of Eu2O3 dispersed onto the support surface depend on the structure of support and that there is an inductive effect of support on the structure of the Eu2O3.展开更多
Amorphous Er2O3 films are deposited on Si （001） substrates by using reactive evaporation. This paper reports the evolution of the structure, morphology and electrical characteristics with annealing temperatures in a...Amorphous Er2O3 films are deposited on Si （001） substrates by using reactive evaporation. This paper reports the evolution of the structure, morphology and electrical characteristics with annealing temperatures in an oxygen ambience. X-ray diffraction and high resolution transimission electron microscopy measurement show that the films remain amorphous even after annealing at 700 ℃. The capacitance in the accumulation region of Er2O3 films annealed at 450 ℃ is higher than that of as-deposited films and films annealed at other temperatures. An Er2O3/ErOx/SiOx/Si structure model is proposed to explain the results. The annealed films also exhibit a low leakage current density （around 1.38 × 10^-4 A/cm^2 at a bias of -1 V） due to the evolution of morphology and composition of the films after they are annealed.展开更多
基金supported by the National Natural Science Foundation of China (22278231,22005165 and 22376110)the Natural Science Foundation Project of Shandong Province (ZR2022MB092 and ZR2023ME098)the Taishan Scholar Program (ts201712030)。
文摘Manganese-based oxide electrode materials suffer from severe Jahn-Teller(J-T)distortion,leading to severe cycle instability in sodium ion storage.However,it is difficult to adjust the electron at d orbitals exactly to a low spin state to eliminate orbital degeneracy and suppress J-T distortion fundamentally.This article constructed concentration-controllable Mn/O coupled vacancy and amorphous network in Mn_(3)O_(4) and coated it with nitrogen-doped carbon aerogel(Mn_(3-x)O_(4-y)@NCA).The existence of Mn/O vacancies has been confirmed by scanning transmission electron microscopy(STEM)and positron annihilation lifetime spectroscopy(PALS).Atomic absorption spectroscopy(AAS)and X-ray photoelectron spectroscopy(XPS)determine the most optimal ratio of Mn/O vacancies for sodium ion storage is 1:2.Density functional theory(DFT)calculations prove that Mn/O coupled vacancies with the ratio of 1:2could exactly induce a low spin states and a d~4 electron configuration of Mn,suppressing the J-T distortion successfully.The abundant amorphous regions can shorten the transport distance of sodium ions,increase the electrochemically active sites and improve the pseudocapacitance response.From the synergetic effect of Mn/O coupled vacancies and amorphous regions,Mn_(3-x)O_(4-y)@NCA exhibits an energy density of 37.5 W h kg^(-1)and an ultra-high power density of 563 W kg^(-1)in an asymmetric supercapacitor.In sodium-ion batteries,it demonstrates high reversible capacity and exceptional cycling stability.This research presents a new method to improve the Na^(+)storage performance in manganese-based oxide,which is expected to be generalized to other structural distortion.
基金supported by the National Natural Science Foundation of China (51932003, 51872115)the 2020 International Cooperation Project of the Department of Science and Technology of Jilin Province (20200801001GH)+4 种基金the Program for the Development of Science and Technology of Jilin Province(20190201309JC)the Jilin Province/Jilin University coConstruction Project-Funds for New Materials (SXGJSF2017-3,Branch-2/440050316A36)the Project for Self-innovation Capability Construction of Jilin Province Development and Reform Commission (2021C026)the Program for JLU Science and Technology Innovative Research Team (JLUSTIRT, 2017TD-09)the Fundamental Research Funds for the Central Universities JLU, and “DoubleFirst Class” Discipline for Materials Science&Engineering。
文摘Aqueous rechargeable magnesium ion batteries(ARMBs) have obtained more attention due to the twoelectrons transfer nature, low cost and safety. However, the scarcity of cathode materials seriously hinders the development of ARMBs because of the unfavorable strong interaction between Mg^(2+) and cathode material. Herein, we choose a pre-treated spinel Mn_(3)O_(4) cathode for aqueous Mg^(2+) storage. The pretreatment in Na_(2)SO_(4) solution induces the grain refinement decorated with tortuous amorphous ion diffusion channels, facilitating the production of electrochemical reaction active sites and the diffusion of Mg^(2+), respectively, which achieve a(sub-)surface pseudocapacitance reaction between Mn(Ⅱ) and Mn(Ⅲ). As a result, the pre-treated Mn_(3)O_(4) cathode exhibits a package of optimal performances, i.e., a capacity of 98.9 m Ah g^(-1) and a high capacity retention rate of 99.4% after 2000 cycles. To the best of our knowledge, our work not only provides a new reaction mechanism of spinelMn_(3)O_(4) in aqueous batteries system,but also affords a high cycle stability electrode material for rechargeable Mg^(2+) energy storage.
文摘Solid-solid surface adsorption of Eu2O3 on amorphous Al2O3 have been investigated by Mossbauer spectroscopy, X- ray diffraction analysis and laser Raman spectra (LRS). No X-ray diffraction peak of crystalline Eu2O3 can be found for all samples studied. The LRS show that two peaks at 998 and 1051 cm-1 assigned to two-dimensional surface europium-oxygen species appear at Eu2O3 content of 18.7 wt%. The peak at 1068 cm-1 due to the surface species and another peak at 342cm-1 due to crystalline Eu2O3 content start to appear for the sample with an Eu2O3 content of 36.5 wt%. The dispersity of Eu2O3 on the surface of amorphous Al2O3 were compared with that of α-Al2O3,η-Al2O3 and SiO2 gel. The results of these studies indicate that the structure of Eu2O3 dispersed onto the support surface depend on the structure of support and that there is an inductive effect of support on the structure of the Eu2O3.
基金supported by the China Postdoctoral Science Foundation and Shaoxing Science and Technology Commission (Grant No2007A21015)supported by the Project of Shanghai Nanotechnology (Grant No 0852NM02400)the National Natural Science Foundation of China (Grant No 60806031)
文摘Amorphous Er2O3 films are deposited on Si （001） substrates by using reactive evaporation. This paper reports the evolution of the structure, morphology and electrical characteristics with annealing temperatures in an oxygen ambience. X-ray diffraction and high resolution transimission electron microscopy measurement show that the films remain amorphous even after annealing at 700 ℃. The capacitance in the accumulation region of Er2O3 films annealed at 450 ℃ is higher than that of as-deposited films and films annealed at other temperatures. An Er2O3/ErOx/SiOx/Si structure model is proposed to explain the results. The annealed films also exhibit a low leakage current density （around 1.38 × 10^-4 A/cm^2 at a bias of -1 V） due to the evolution of morphology and composition of the films after they are annealed.
