Hollow structuring has been identified as an effective strategy to enhance the cycling stability of electrodes for rechargeable batteries due to the outstanding volume expansion buffering efficiency,which motivates ar...Hollow structuring has been identified as an effective strategy to enhance the cycling stability of electrodes for rechargeable batteries due to the outstanding volume expansion buffering efficiency,which motivates ardent pursuing on the synthetic approaches of hollow materials.Herein,an intriguing route,combining solid precursor transition and Ostwald ripening(SPTOR),is developed to craft nano single-crystal(SC)-constructed MnCO_(3) submicron hollow spindles homogeneously encapsulated in a reduced graphene oxide matrix(MnCO_(3) SMHSs/rGO).It is noteworthy that the H-bonding interaction between Mn_(3)O_(4) nanoparticles(NPs)and oxygen-containing groups on GO promotes uniform anchoring of Mn_(3)O_(4) NPs on GO,mild reductant ascorbic acid triggers the progressive solid-to-solid transition from Mn_(3)O_(4) NPs to MnCO_(3) submicron solid spindles(SMSSs)in situ on GO,and the Ostwald ripening process induces the gradual dissolution of interior polycrystals of MnCO_(3) SMSSs and subsequent recrystallization on surface SCs of MnCO_(3) SMHSs.Remarkably,MnCO_(3) SMHSs/rGO delivers a 500th lithium storage capacity of 2023 mAh g^(-1) at 1000 mAg^(-1),which is 10 times higher than that of MnCO_(3) microspheres/rGO fabricated from a conventional Mn^(2+)salt precursor(202 mAh g^(-1)).The ultrahigh capacity and ultralong lifespan of MnCO_(3) SMHSs/rGO can be primarily attributed to the superior reaction kinetics and reversibility combined with exceptional interfacial and capacitive lithium storage capability,enabled by the fast ion/electron transfer,large specific surface area,and robust electrode pulverization inhibition efficacy.Moreover,fascinating in-depth lithium storage reactions of MnCO_(3) are observed such as the oxidation of Mn^(2+)in MnCO_(3) to Mn^(3+)in charge process after long-term cycles and the further lithiation of Li_(2)CO_(3) in discharge process.As such,the Carbon Energy.SPTOR approach may represent a viable strategy for crafting various hollow functional materials with metastable nanomaterials as precurso展开更多
Spinel LiMn2O4 microspheres with durable high rate capability were synthesized by a facile route using spherical MnCO3 precursors as the self-supported templates, combined with the calcinations of LiNO3 at 700 °C...Spinel LiMn2O4 microspheres with durable high rate capability were synthesized by a facile route using spherical MnCO3 precursors as the self-supported templates, combined with the calcinations of LiNO3 at 700 °C for 8 h. The spherical MnCO3 precursors were obtained from the control of the crystallizing process of Mn2＋ ions and NH4HCO3 in aqueous solution. The effects of the mole ratio of the raw materials, reaction time, and reaction temperature on the morphology and yield of the MnCO3 were investigated. The as-synthesized MnCO3 and LiMn2O4 microspheres were characterized by powder X-ray diffractometry （XRD） and scanning electron microscopy （SEM）. Galvanostatic charge/discharge tests indicate that the spinel LiMn2O4 microspheres deliver a discharge capacity of 90 mA-h/g at 10C rate show good capacity retention capability （75% of their initial capacity after 800 cycles at 10C rate）. The durable high rate capability suggests that the as-synthesized LiMn2O4 microspheres are promising cathode materials for high power lithium ion batteries.展开更多
Developing new electrode materials with a high specific capacity for excellent lithium-ion storage properties is very desirable.The MnCO_(3)/Mn_(3)O_(4)nanoparticles with uniform size(about 50 nm)and shape which are w...Developing new electrode materials with a high specific capacity for excellent lithium-ion storage properties is very desirable.The MnCO_(3)/Mn_(3)O_(4)nanoparticles with uniform size(about 50 nm)and shape which are wrapped with graphene have been successfully synthesized via the one-step method for anode material of lithium-ion batteries.The as-prepared graphene-wrapped MnCO_(3)/Mn_(3)O_(4)nanocomposite exhibits remarkable electrochemical performance,including high reversible specific capacity,outstanding cycling stability,and excellent rate capability in comparison with the bare MnCO_(3)and MnCO_(3)/Mn_(3)O_(4)nanocomposite.This is because the synergistic effect of MnCO_(3)and Mn_(3)O_(4)nanoparticles and graphene nanosheets act as both electron conductors and volume buffer layers.From the scanning electron microscopy(SEM)analysis,we confirmed that the morphology and structure of the composite are preserved after 200 cycles.This further confirms that graphene-wrapped MnCO_(3)/Mn_(3)O_(4)nanocomposite acts as a stable template for reversible lithium-ion intercalation/deintercalation.展开更多
Transition metal molybdates/carbonates and hybrid nanomaterials have attracted great attention in energy storage applications because of their enriched redox activity,good electronic conductivity,and stable crystallin...Transition metal molybdates/carbonates and hybrid nanomaterials have attracted great attention in energy storage applications because of their enriched redox activity,good electronic conductivity,and stable crystallinity.We synthesize a multicomponent MnMoO_(4)/MnCO_(3)hybrid by a one-step hydrothermal method with urea as the reaction fuel.By controlling only the urea concentration in the initial precursor solution,the MnMoO_(4)/MnCO_(3)molecular ratio is controlled effectively,which is found to have a profound effect on the electrochemical properties of the hybrid electrodes.The electrochemical measurements show that the specific capacitance of MnMoO_(4)/MnCO_(3)hybrid is 1311 F/g,the energy density of 116.8 Wh/kg,and power density of 383 W/kg at a current density of 1 A/g with 79%capacitance retention over 5000 cycles.The fabricated asymmetric supercapacitor device exhibits good energy storage performance,including the specific capacitance of 97 F/g along with the energy density of 26.5 Wh/kg and the power density of 657 W/kg at a current density of 1 A/g and good reversibility with capacitance retention of 85%after 2000 cycles and 70%over 5000 cycles.The increase in the energy density of 900%with a mere 60%decrement in the energy density indicates its potential superior applications in high-power devices.展开更多
基金General Research Project of Zhejiang Provincial Department of Education,Grant/Award Number:Y202250766National Natural Science Foundation of China,Grant/Award Numbers:21905208,22250410263Natural Science Foundation of Zhejiang Province,Grant/Award Numbers:LY23B030001,LZ18E030001。
文摘Hollow structuring has been identified as an effective strategy to enhance the cycling stability of electrodes for rechargeable batteries due to the outstanding volume expansion buffering efficiency,which motivates ardent pursuing on the synthetic approaches of hollow materials.Herein,an intriguing route,combining solid precursor transition and Ostwald ripening(SPTOR),is developed to craft nano single-crystal(SC)-constructed MnCO_(3) submicron hollow spindles homogeneously encapsulated in a reduced graphene oxide matrix(MnCO_(3) SMHSs/rGO).It is noteworthy that the H-bonding interaction between Mn_(3)O_(4) nanoparticles(NPs)and oxygen-containing groups on GO promotes uniform anchoring of Mn_(3)O_(4) NPs on GO,mild reductant ascorbic acid triggers the progressive solid-to-solid transition from Mn_(3)O_(4) NPs to MnCO_(3) submicron solid spindles(SMSSs)in situ on GO,and the Ostwald ripening process induces the gradual dissolution of interior polycrystals of MnCO_(3) SMSSs and subsequent recrystallization on surface SCs of MnCO_(3) SMHSs.Remarkably,MnCO_(3) SMHSs/rGO delivers a 500th lithium storage capacity of 2023 mAh g^(-1) at 1000 mAg^(-1),which is 10 times higher than that of MnCO_(3) microspheres/rGO fabricated from a conventional Mn^(2+)salt precursor(202 mAh g^(-1)).The ultrahigh capacity and ultralong lifespan of MnCO_(3) SMHSs/rGO can be primarily attributed to the superior reaction kinetics and reversibility combined with exceptional interfacial and capacitive lithium storage capability,enabled by the fast ion/electron transfer,large specific surface area,and robust electrode pulverization inhibition efficacy.Moreover,fascinating in-depth lithium storage reactions of MnCO_(3) are observed such as the oxidation of Mn^(2+)in MnCO_(3) to Mn^(3+)in charge process after long-term cycles and the further lithiation of Li_(2)CO_(3) in discharge process.As such,the Carbon Energy.SPTOR approach may represent a viable strategy for crafting various hollow functional materials with metastable nanomaterials as precurso
基金Project(2011M501090) upported by the China Postdoctoral Science FoundationProject(SCUT2012ZZ0042) upported by the Fundamental Research Funds for the Central Universities+1 种基金Project supported by the"SPR-2011"of South China University of TechnologyProject(NRC07/08.EG01)supprted by the Fok Ying Tung Foundation
文摘Spinel LiMn2O4 microspheres with durable high rate capability were synthesized by a facile route using spherical MnCO3 precursors as the self-supported templates, combined with the calcinations of LiNO3 at 700 °C for 8 h. The spherical MnCO3 precursors were obtained from the control of the crystallizing process of Mn2＋ ions and NH4HCO3 in aqueous solution. The effects of the mole ratio of the raw materials, reaction time, and reaction temperature on the morphology and yield of the MnCO3 were investigated. The as-synthesized MnCO3 and LiMn2O4 microspheres were characterized by powder X-ray diffractometry （XRD） and scanning electron microscopy （SEM）. Galvanostatic charge/discharge tests indicate that the spinel LiMn2O4 microspheres deliver a discharge capacity of 90 mA-h/g at 10C rate show good capacity retention capability （75% of their initial capacity after 800 cycles at 10C rate）. The durable high rate capability suggests that the as-synthesized LiMn2O4 microspheres are promising cathode materials for high power lithium ion batteries.
基金financially supported by the 111 Project(B16009)the National Natural Science Foundation of China(Nos.51704065 and 51804219)+1 种基金the Fundamental Research Funds for the Central Universities of China(No.N2002022)the Natural Science Foundation of Anhui Province,China(No.1808085QE161)
文摘Developing new electrode materials with a high specific capacity for excellent lithium-ion storage properties is very desirable.The MnCO_(3)/Mn_(3)O_(4)nanoparticles with uniform size(about 50 nm)and shape which are wrapped with graphene have been successfully synthesized via the one-step method for anode material of lithium-ion batteries.The as-prepared graphene-wrapped MnCO_(3)/Mn_(3)O_(4)nanocomposite exhibits remarkable electrochemical performance,including high reversible specific capacity,outstanding cycling stability,and excellent rate capability in comparison with the bare MnCO_(3)and MnCO_(3)/Mn_(3)O_(4)nanocomposite.This is because the synergistic effect of MnCO_(3)and Mn_(3)O_(4)nanoparticles and graphene nanosheets act as both electron conductors and volume buffer layers.From the scanning electron microscopy(SEM)analysis,we confirmed that the morphology and structure of the composite are preserved after 200 cycles.This further confirms that graphene-wrapped MnCO_(3)/Mn_(3)O_(4)nanocomposite acts as a stable template for reversible lithium-ion intercalation/deintercalation.
基金supported by the grant NRF-2019R1A5A8080290 of the National Research Foundation of KoreaSupport Center for Natural Products and Medical Materials(CRCNM)for technical support。
文摘Transition metal molybdates/carbonates and hybrid nanomaterials have attracted great attention in energy storage applications because of their enriched redox activity,good electronic conductivity,and stable crystallinity.We synthesize a multicomponent MnMoO_(4)/MnCO_(3)hybrid by a one-step hydrothermal method with urea as the reaction fuel.By controlling only the urea concentration in the initial precursor solution,the MnMoO_(4)/MnCO_(3)molecular ratio is controlled effectively,which is found to have a profound effect on the electrochemical properties of the hybrid electrodes.The electrochemical measurements show that the specific capacitance of MnMoO_(4)/MnCO_(3)hybrid is 1311 F/g,the energy density of 116.8 Wh/kg,and power density of 383 W/kg at a current density of 1 A/g with 79%capacitance retention over 5000 cycles.The fabricated asymmetric supercapacitor device exhibits good energy storage performance,including the specific capacitance of 97 F/g along with the energy density of 26.5 Wh/kg and the power density of 657 W/kg at a current density of 1 A/g and good reversibility with capacitance retention of 85%after 2000 cycles and 70%over 5000 cycles.The increase in the energy density of 900%with a mere 60%decrement in the energy density indicates its potential superior applications in high-power devices.
