The application of conventional manganese dioxide(MnO_(2))materials in sodium-ion supercapacitors(Na-SCs)is considerably limited by their low conductivity and structural instability.Biomimetic morphology engineering c...The application of conventional manganese dioxide(MnO_(2))materials in sodium-ion supercapacitors(Na-SCs)is considerably limited by their low conductivity and structural instability.Biomimetic morphology engineering can optimize the electrochemical performance of MnO_(2).Here,based on the metal-organic frameworks(MOFs)-derived method and electrochemical reconstruction,a coral-like MnO_(2)structure integrated with a functional nitrogen-doped carbon(NC)coating is designed for Na-SC application.The bioinspired coral-like structure captures numerous electrolyte ions and increases the Na+concentration on the electrode surface,which is beneficial for optimizing the Na+transport pathway and accelerating the electrode reaction kinetics.Moreover,the coral-like crosslinked structure effectively enhances the mechanical properties,enabling the maintenance of the structure of MnO_(2)-based electrodes during long-term operation.Furthermore,in/ex-situ characterizations are performed to elucidate the mechanism of lattice transformation during electrochemical phase reconstruction.Additionally,the theoretical calculation and simulation results reveal the ion/electron dynamics in the fabricated electrode.The prepared electrode demonstrates excellent capacitance storage ability(340.7 F g^(−1)at 0.5 A g^(−1))and cycling stability(85.1%capacitance retention after 10,000 cycles).The assembled hybrid device exhibits exceptional life-span(82.0%capacitance retention after 10,000 cycles)and exceptional energy density(36.5 Wh kg^(−1)).This study provides a reliable biomimetic morphology design strategy for MnO_(2)cathodes,paving the way for the fabrication of high-performance Na-SCs.展开更多
Layered manganese dioxide(δ-MnO_(2))is considered a promising ammonium ion capture electrode material for capacitive deionization(CDI)attributed to its high theoretical capacity and cost-effectiveness.Nevertheless,it...Layered manganese dioxide(δ-MnO_(2))is considered a promising ammonium ion capture electrode material for capacitive deionization(CDI)attributed to its high theoretical capacity and cost-effectiveness.Nevertheless,it continues to encounter challenges including rapid capacity degradation,structural instability,and Jahn-Teller effect.Herein,a crystal and electron synergistically regulation engineering strategy is proposed for the suppression of the Jahn-Teller effect and the improvement of ammonium ion storage dynamics in F doped MnO_(2)(MnOF).The induced action of F ions transforms the MnO_(2)structure from the original cubic[MnO_(6)]octahedron into an asymmetric[Mn(OF)_(6)]octahedron with electron redistribution,and generates a localized charge imbalance along the O-Mn-F pathway,which promotes electron transfer from Mn to F direction,accelerates electron transfer,and reduces the energy barrier of ammonium ion diffusion.As a result,the prepared MnOF exhibited a maximum salt adsorption capacity of 144.3 mg g^(−1)and an exceptionally high salt adsorption rate of 18.25 mg g^(−1)min^(-1),along with outstanding cycling stability.Besides,ex/in situ characterizations reveal that in MnOF,the formation/breaking of hydrogen bond is accompanied by the insertion/deinsertion of NH_(4)^(+).Therefore,the rational introduction of highly electronegative anions provides a new direction for the development of advanced CDI electrode materials.展开更多
基金supported by the National Natural Science Foundation of China(22409065)the Guangdong Basic and Applied Basic Research Foundation(2022A1515011906)+2 种基金the China Postdoctoral Science Foundation(2023M731153)the Research Fund Program of Guangdong Provincial Key Laboratory of Fuel Cell Technologythe Postdoctoral Fellowship Program of CPSF(GZC20230868).
文摘The application of conventional manganese dioxide(MnO_(2))materials in sodium-ion supercapacitors(Na-SCs)is considerably limited by their low conductivity and structural instability.Biomimetic morphology engineering can optimize the electrochemical performance of MnO_(2).Here,based on the metal-organic frameworks(MOFs)-derived method and electrochemical reconstruction,a coral-like MnO_(2)structure integrated with a functional nitrogen-doped carbon(NC)coating is designed for Na-SC application.The bioinspired coral-like structure captures numerous electrolyte ions and increases the Na+concentration on the electrode surface,which is beneficial for optimizing the Na+transport pathway and accelerating the electrode reaction kinetics.Moreover,the coral-like crosslinked structure effectively enhances the mechanical properties,enabling the maintenance of the structure of MnO_(2)-based electrodes during long-term operation.Furthermore,in/ex-situ characterizations are performed to elucidate the mechanism of lattice transformation during electrochemical phase reconstruction.Additionally,the theoretical calculation and simulation results reveal the ion/electron dynamics in the fabricated electrode.The prepared electrode demonstrates excellent capacitance storage ability(340.7 F g^(−1)at 0.5 A g^(−1))and cycling stability(85.1%capacitance retention after 10,000 cycles).The assembled hybrid device exhibits exceptional life-span(82.0%capacitance retention after 10,000 cycles)and exceptional energy density(36.5 Wh kg^(−1)).This study provides a reliable biomimetic morphology design strategy for MnO_(2)cathodes,paving the way for the fabrication of high-performance Na-SCs.
基金financial support from the National Natural Science Foundation of China(22108032 and 22178055)the Dongguan Introduction Program of Leading Innovative and Entrepreneurial Talents+1 种基金the support of characterization from the Dongguan University of Technology Analytical and Testing Centerthe Guangdong Provincial Key Laboratory of Intelligent Disaster Prevention and Emergency Technologies for Urban Lifeline Engineering(2022)(Grant No.2022B1212010016).
文摘Layered manganese dioxide(δ-MnO_(2))is considered a promising ammonium ion capture electrode material for capacitive deionization(CDI)attributed to its high theoretical capacity and cost-effectiveness.Nevertheless,it continues to encounter challenges including rapid capacity degradation,structural instability,and Jahn-Teller effect.Herein,a crystal and electron synergistically regulation engineering strategy is proposed for the suppression of the Jahn-Teller effect and the improvement of ammonium ion storage dynamics in F doped MnO_(2)(MnOF).The induced action of F ions transforms the MnO_(2)structure from the original cubic[MnO_(6)]octahedron into an asymmetric[Mn(OF)_(6)]octahedron with electron redistribution,and generates a localized charge imbalance along the O-Mn-F pathway,which promotes electron transfer from Mn to F direction,accelerates electron transfer,and reduces the energy barrier of ammonium ion diffusion.As a result,the prepared MnOF exhibited a maximum salt adsorption capacity of 144.3 mg g^(−1)and an exceptionally high salt adsorption rate of 18.25 mg g^(−1)min^(-1),along with outstanding cycling stability.Besides,ex/in situ characterizations reveal that in MnOF,the formation/breaking of hydrogen bond is accompanied by the insertion/deinsertion of NH_(4)^(+).Therefore,the rational introduction of highly electronegative anions provides a new direction for the development of advanced CDI electrode materials.
