For high performance supercapacitors, novel hierarchical yolk-shell α-Ni(OH)_(2)/Mn_(2)O_(3) microspheres were controllably synthesized using a facile two-step method based on the solvothermal treatment. The unique ...For high performance supercapacitors, novel hierarchical yolk-shell α-Ni(OH)_(2)/Mn_(2)O_(3) microspheres were controllably synthesized using a facile two-step method based on the solvothermal treatment. The unique α-Ni(OH)_(2) based yolk-shell microstructures decorated with numerous interconnected nanosheets and the heterocomposition features can synergistically enhance reactive site exposure and electron conduction within the microspheres, facilitate charge transfer between electrolyte and electrode materials, and release structural stress during OH− chemisorption/desorption. Moreover, the Mn2O3 sediments distributed over the α-Ni(OH)_(2) microspheres can serve as an effective protective layer for electrochemical reactions. Consequently, when tested in 1 mol·L^(−1) KOH aqueous electrolyte for supercapacitors, the yolk-shell α-Ni (OH)_(2)/Mn_(2)O_(3) microspheres exhibited a considerably high specific capacitance of 2228.6 F·g^(−1) at 1 A·g^(−1) and an impressive capacitance retention of 77.7% after 3000 cycles at 10 A·g^(−1). The proposed α-Ni(OH)_(2)/Mn_(2)O_(3) microspheres with hetero-composition and unique hierarchical yolk-shell microstructures are highly promising to be used as electrode materials in supercapacitors and other energy storage devices.展开更多
In this work,a facile"carbonization-activation"strategy is developed to synthesize N,P-codoped hierarchical porous carbon.Phosphoric acid is innovatively introduced during the hydrothermal process to achieve...In this work,a facile"carbonization-activation"strategy is developed to synthesize N,P-codoped hierarchical porous carbon.Phosphoric acid is innovatively introduced during the hydrothermal process to achieve in-situ P doping as well as create abundant pores,and the employment of sodamide is of vital importance to simultaneously serve as activating agent and N-source to succeed a high-level N doping.Thus,the obtained samples exhibit a unique three-dimensional hierarchical structure with an ultra-high specific surface area(3646 m^(2)g^(-1))and ultra-high N-doping level(9.81 at.%).Computational analyses confirm that N,P co-doping and higher N content can enhance active sites and widen potential differences of carbon materials to improve their capacitance.The as-prepared carbon materials demonstrate superior electrochemical performances,such as an ultra-high capacitance of 586 Fg^(-1)at 1 Ag^(-1),a superior rate capability of 409 Fg^(-1)at 20 Ag^(-1),and excellent long-term stability of 97%capacitance retention after10,000 cycles in 6 M KOH.Moreover,an assembled symmetric supercapacitor delivers a high energy density of 28.1 Wh kg^(-1)at the power density of 450 W kg^(-1)in 1 M Na_(2)SO_(4),demonstrating a great potential for applications in supercapacitors.展开更多
Superhydrophilic surfaces have been applied for supercapacitor;however,during energy storage reaction,how the wettability affects the process of electrochemical reaction specifically is still unclear.Herein,we demonst...Superhydrophilic surfaces have been applied for supercapacitor;however,during energy storage reaction,how the wettability affects the process of electrochemical reaction specifically is still unclear.Herein,we demonstrate superhydrophilic surface for promotion of electrochemical reactions by liquid affinity and further explain the mechanism,where the transition of the wettability state caused by the change in surface free energy is the main reason for the obvious increase in specific capacitance.Through citric acid assistance strategy,an intrinsically hydrophobic Ni(OH)_(2)thick nanosheets(HNHTNs,16 nm)can be transitioned into superhydrophilic Ni(OH)_(2)ultrathin nanosheets(SNHUNs,6.8 nm),where the water contact angle was 0°and the surface free energy increased from 8.6to 65.8 mN·m^(-1),implying superhydrophilicity.Compared with HNHTNs,the specific capacitance of SNHUNs is doubled:from 1230 F·g^(-1)(HNHTNs)to 2350 F·g^(-1)(2A·g^(-1))and,even at 20 A·g^(-1),from 833 F·g^(-1)(HNHTNs)to 1670 F·g^(-1).The asymmetric capacitors assembled by SNHUNs and activated carbon show 52.44 Wh·kg^(-1)at 160W·kg^(-1)and excellent stability with~90%retention after5000 cycles(~80%retention after 9500 cycles).The promotion of electrochemical performances is ascribed to the change of surface wettability caused by surface free energy,which greatly increase affinity of electrode to the surrounding liquid environment to reduce the interface resistance and optimize the electron transport path.展开更多
The conversion of biomass waste into eco-nomical and high-performance energy storage devices receives significant attention.Herein,a facile and green method to prepare porous active carbon from walnut sep-tum is appli...The conversion of biomass waste into eco-nomical and high-performance energy storage devices receives significant attention.Herein,a facile and green method to prepare porous active carbon from walnut sep-tum is applied to the electrode materials of supercapacitors.The effect of chemical etching reagent(KOH)on the microstructure and specific capacitance of the porous car-bon are explored.The modified BC-2.0,with a KOH/walnut septum mass ratio of 2∶1,exhibits large specific surface area of 1003.9 m^(2)·g^(-1)with hierarchical micro-mesoporous structures.BC-2.0 reveals a superior specific capacitance of 457 F·g^(-1)at 1 A·g^(-1).The flexible sym-metric supercapacitor in gel electrolyte(KOH/PVA)exhi-bits considerable synergetic energy-power output performance.The results indicate that walnut septum is a better precursor to obtain activated carbons relative to other biomass carbon sources.The large mesoporosity after activation effectively boosts the electrochemical properties of supercapacitor.Consequently,the walnut septum has potential to be a superior electrode material for supercapacitors.展开更多
We report here the activated carbon and cobalt hexacyanoferrate composite,which is applied as the electrode materials in symmetric supercapacitors containing a 1.0 M Na_(2)SO_(4) aqueous electrolyte.This novel materia...We report here the activated carbon and cobalt hexacyanoferrate composite,which is applied as the electrode materials in symmetric supercapacitors containing a 1.0 M Na_(2)SO_(4) aqueous electrolyte.This novel material combines high specific surface area and electrochemical stability of activated carbon with the redox properties of cobalt hexacyanoferrate,resulting in maximum specific capacitance of 329 F g^(-1) with large voltage working window of 2.0 V.Electrochemical studies indicated that cobalt hexacyanoferrate introduces important pseudocapacitive properties accounting for the overall charge-storage process,especially when I<0.5 A g^(-1).At lower gravimetric currents(e.g.,0.05 A g^(-1))and up to 1.0 V,the presence of cobalt hexacyanoferrate improves the specific energy for more than 300%.In addition,to better understanding the energy storage process we also provided a careful investigation of the electrode materials under dynamic polarization conditions using the in situ Raman spectroscopy and synchrotron light Xray diffraction techniques.Interesting complementary findings were obtained in these studies.We believe that this novel electrode material is promising for applications regarding the energy-storage process in pseudocapacitors with long lifespan properties.展开更多
Low-cost,high safety and environment-friendly aqueous energy storage systems(ESSs)are huge potential for grid-level energy storage,but the(de)intercalation of metal ions in the electrode materials(e.g.vanadium oxides)...Low-cost,high safety and environment-friendly aqueous energy storage systems(ESSs)are huge potential for grid-level energy storage,but the(de)intercalation of metal ions in the electrode materials(e.g.vanadium oxides)to obtain superior long-term cycling stability is a significant challenge.Herein,we demonstrate that polyvinyl alcohol(PVA)-assisted hydrated vanadium pentoxide/reduced graphene oxide(V_(2)O_(5)·n H_(2)O/r GO/PVA,denoted as the VGP)films enable long cycle stability and high capacity for the Li^(+)and Zn^(2+)storages in both the VGP//Li Cl(aq)//VGP and the VGP//Zn SO4(aq)//Zn cells.The binderfree VGP films are synthesized by a one-step hydrothermal method combination with the filtration.The extensive hydrogen bonds are formed among PVA,GO and H_(2)O,and they act as structural pillars and connect the adjacent layers as glue,which contributes to the ultrahigh specific capacitance and ultralong cyclic performance of Li^(+)and Zn^(2+)storage properties.As for Li^(+)storage,the binder-free VGP4 film(4mg PVA)electrode achieves the highest specific capacitance up to 1381 F g^(-1)at 1.0 A g^(-1)in the three-electrode system and 962 F g^(-1)at 1.0 A g^(-1)in the symmetric two-electrode system.It also behaves the outstanding cyclic performance with the capacitance retention of 96.5%after 15000 cycles in the three-electrode system and 99.7%after 25000 cycles in the symmetric two-electrode system.As for Zn^(2+)storage,the binder-free VGP4 film electrode exhibits the high specific capacity of 184 m A h g^(-1)at 0.5A g^(-1)in the VGP4//Zn SO4(aq)//Zn cell and the superb cycle performance of 98.5%after 25000 cycles.This work not only provides a new strategy for the construction of vanadium oxides composites and demonstrates the potential application of PVA-assisted binder-free film with excellent electrochemical properties,but also extends to construct other potential electrode materials for metal ion storage cells.展开更多
Exfoliated graphite oxide was prepared by an improved Hummers method and was then reduced to graphene with hydrazine in the presence of ammonium hydroxide.N2adsorption–desorption measurement showed that graphene so o...Exfoliated graphite oxide was prepared by an improved Hummers method and was then reduced to graphene with hydrazine in the presence of ammonium hydroxide.N2adsorption–desorption measurement showed that graphene so obtained had a specific surface area as high as 818 m2/g.Galvanostatic charge/discharge curves demonstrated that the as-prepared graphene exhibited a specific capacitance of 186.9 F/g at a current density of 0.1 A/g and that about 96%of the specific capacitance was retained after 2000 cycles at a current density of 5 A/g.展开更多
In this work,we report a high-performance self-standing supercapacitor electrode of mixed nickel manganese sulfides (NMSs)with a cracked-bark shape grown by one-step electrochemical deposition on activated carbon clot...In this work,we report a high-performance self-standing supercapacitor electrode of mixed nickel manganese sulfides (NMSs)with a cracked-bark shape grown by one-step electrochemical deposition on activated carbon cloth (ACC).The electrode possesses outstanding electrochemical properties,including a high specific capacitance of up to 3142.8 F g^(-1)at 1.0 A g^(-1),the high-rate performance (~1206.8 F g^(-1)at 60.0 A g^(-1)),and cycle stability (~92.3%capacitance retention after 8000 cycles at8 A g^(-1)).An asymmetric supercapacitor assembled using NMSs on ACC as the cathode,activated carbon on carbon cloth as the anode and 1.0 mol L;KOH as the electrolyte delivers a high energy density of 111.2 W h kg^(-1)at 800.0 W kg^(-1)and the prominent cycling performance of~93.2%capacitance retention after 10000 cycles at 5 A g^(-1)with the Columbic efficiency of around 100%during these 10000 cycles.The high performance and facile preparation indicate that the NMSs on ACC hold a huge potential as the electrode for supercapacitors.展开更多
基金the National Natural Science Foundation of China(Grant Nos.21908037,91834301)the Fundamental Research Funds for the Central Universities of China(Grant No.JZ2019HGBZ0147).
文摘For high performance supercapacitors, novel hierarchical yolk-shell α-Ni(OH)_(2)/Mn_(2)O_(3) microspheres were controllably synthesized using a facile two-step method based on the solvothermal treatment. The unique α-Ni(OH)_(2) based yolk-shell microstructures decorated with numerous interconnected nanosheets and the heterocomposition features can synergistically enhance reactive site exposure and electron conduction within the microspheres, facilitate charge transfer between electrolyte and electrode materials, and release structural stress during OH− chemisorption/desorption. Moreover, the Mn2O3 sediments distributed over the α-Ni(OH)_(2) microspheres can serve as an effective protective layer for electrochemical reactions. Consequently, when tested in 1 mol·L^(−1) KOH aqueous electrolyte for supercapacitors, the yolk-shell α-Ni (OH)_(2)/Mn_(2)O_(3) microspheres exhibited a considerably high specific capacitance of 2228.6 F·g^(−1) at 1 A·g^(−1) and an impressive capacitance retention of 77.7% after 3000 cycles at 10 A·g^(−1). The proposed α-Ni(OH)_(2)/Mn_(2)O_(3) microspheres with hetero-composition and unique hierarchical yolk-shell microstructures are highly promising to be used as electrode materials in supercapacitors and other energy storage devices.
基金financially supported by the National Natural Science Foundation of China(Nos.21776147,21606140,61604086,and 21905153)the Qingdao Municipal Science and Technology Bureau,China(19-6-1-91-nsh)+2 种基金the International Science&Technology Cooperation Program of China(No.2014DFA60150)the Department of Science and Technology of Shandong Province(Nos.ZR2018BB066 and 2016GGX104010)the Chemcloudcomputing of National Supercomputing Center in Shenzhen(Shenzhen CloudComputing Center)。
文摘In this work,a facile"carbonization-activation"strategy is developed to synthesize N,P-codoped hierarchical porous carbon.Phosphoric acid is innovatively introduced during the hydrothermal process to achieve in-situ P doping as well as create abundant pores,and the employment of sodamide is of vital importance to simultaneously serve as activating agent and N-source to succeed a high-level N doping.Thus,the obtained samples exhibit a unique three-dimensional hierarchical structure with an ultra-high specific surface area(3646 m^(2)g^(-1))and ultra-high N-doping level(9.81 at.%).Computational analyses confirm that N,P co-doping and higher N content can enhance active sites and widen potential differences of carbon materials to improve their capacitance.The as-prepared carbon materials demonstrate superior electrochemical performances,such as an ultra-high capacitance of 586 Fg^(-1)at 1 Ag^(-1),a superior rate capability of 409 Fg^(-1)at 20 Ag^(-1),and excellent long-term stability of 97%capacitance retention after10,000 cycles in 6 M KOH.Moreover,an assembled symmetric supercapacitor delivers a high energy density of 28.1 Wh kg^(-1)at the power density of 450 W kg^(-1)in 1 M Na_(2)SO_(4),demonstrating a great potential for applications in supercapacitors.
基金financially supported by the National Natural Science Foundation of China(Nos.22278349 and 62071413)Hebei Natural Science Foundation(Nos.B2020203013 and F2020203056)+4 种基金the Science and Technology Project of Hebei Education Department(No.QN2020137)Subsidy for Hebei Key Laboratory of Applied Chemistry after Operation Performance(No.22567616H)the Cultivation Project for Basic Research Innovation of Yanshan University(No.2021LGZD015)the Natural Science Foundation of Heilongjiang Province of China(No.LH2022B025)the Fundamental Research Funds for the Provincial Universities of Heilongjiang Province(No.KYYWF10236190104)。
文摘Superhydrophilic surfaces have been applied for supercapacitor;however,during energy storage reaction,how the wettability affects the process of electrochemical reaction specifically is still unclear.Herein,we demonstrate superhydrophilic surface for promotion of electrochemical reactions by liquid affinity and further explain the mechanism,where the transition of the wettability state caused by the change in surface free energy is the main reason for the obvious increase in specific capacitance.Through citric acid assistance strategy,an intrinsically hydrophobic Ni(OH)_(2)thick nanosheets(HNHTNs,16 nm)can be transitioned into superhydrophilic Ni(OH)_(2)ultrathin nanosheets(SNHUNs,6.8 nm),where the water contact angle was 0°and the surface free energy increased from 8.6to 65.8 mN·m^(-1),implying superhydrophilicity.Compared with HNHTNs,the specific capacitance of SNHUNs is doubled:from 1230 F·g^(-1)(HNHTNs)to 2350 F·g^(-1)(2A·g^(-1))and,even at 20 A·g^(-1),from 833 F·g^(-1)(HNHTNs)to 1670 F·g^(-1).The asymmetric capacitors assembled by SNHUNs and activated carbon show 52.44 Wh·kg^(-1)at 160W·kg^(-1)and excellent stability with~90%retention after5000 cycles(~80%retention after 9500 cycles).The promotion of electrochemical performances is ascribed to the change of surface wettability caused by surface free energy,which greatly increase affinity of electrode to the surrounding liquid environment to reduce the interface resistance and optimize the electron transport path.
基金financially supported by the National Natural Science Foundation of China (Nos. 51874079 and 11775226)the Natural Science Foundation of Hebei Province (Nos. E2018501091, E2020501001 and E2021501029)+2 种基金Hebei Province Key Research and Development Plan Project (No.19211302D)the Natural Science Foundation of Liaoning Province (No. 2019-MS-110)the Fundamental Research Funds for the Central Universities (No. N2023040 and N2123035)
文摘The conversion of biomass waste into eco-nomical and high-performance energy storage devices receives significant attention.Herein,a facile and green method to prepare porous active carbon from walnut sep-tum is applied to the electrode materials of supercapacitors.The effect of chemical etching reagent(KOH)on the microstructure and specific capacitance of the porous car-bon are explored.The modified BC-2.0,with a KOH/walnut septum mass ratio of 2∶1,exhibits large specific surface area of 1003.9 m^(2)·g^(-1)with hierarchical micro-mesoporous structures.BC-2.0 reveals a superior specific capacitance of 457 F·g^(-1)at 1 A·g^(-1).The flexible sym-metric supercapacitor in gel electrolyte(KOH/PVA)exhi-bits considerable synergetic energy-power output performance.The results indicate that walnut septum is a better precursor to obtain activated carbons relative to other biomass carbon sources.The large mesoporosity after activation effectively boosts the electrochemical properties of supercapacitor.Consequently,the walnut septum has potential to be a superior electrode material for supercapacitors.
基金the financial support from the Brazilian funding agencies CNPq(301486/2016-6)FAPESP(2014/02163-7,2017/11958-1,2018/20756-6)+2 种基金FAPEMIG(Financial support for the LMMA/UFVJM Laboratory)CNPq(PQ-2 grant:Process 301095/2018-3)the support from Shell and the strategic importance of the support given by ANP(Brazil’s National Oil,Natural Gas and Biofuels Agency)through the R&D levy regulation。
文摘We report here the activated carbon and cobalt hexacyanoferrate composite,which is applied as the electrode materials in symmetric supercapacitors containing a 1.0 M Na_(2)SO_(4) aqueous electrolyte.This novel material combines high specific surface area and electrochemical stability of activated carbon with the redox properties of cobalt hexacyanoferrate,resulting in maximum specific capacitance of 329 F g^(-1) with large voltage working window of 2.0 V.Electrochemical studies indicated that cobalt hexacyanoferrate introduces important pseudocapacitive properties accounting for the overall charge-storage process,especially when I<0.5 A g^(-1).At lower gravimetric currents(e.g.,0.05 A g^(-1))and up to 1.0 V,the presence of cobalt hexacyanoferrate improves the specific energy for more than 300%.In addition,to better understanding the energy storage process we also provided a careful investigation of the electrode materials under dynamic polarization conditions using the in situ Raman spectroscopy and synchrotron light Xray diffraction techniques.Interesting complementary findings were obtained in these studies.We believe that this novel electrode material is promising for applications regarding the energy-storage process in pseudocapacitors with long lifespan properties.
基金partially supported by the National Natural Science Foundation of China(Nos.21771030 and 51572201)the Natural Science Foundation of Liaoning Province(No.2020-MS113)the Fundamental Research Funds for the Central Universities(No.DUT18RC(6)008)。
文摘Low-cost,high safety and environment-friendly aqueous energy storage systems(ESSs)are huge potential for grid-level energy storage,but the(de)intercalation of metal ions in the electrode materials(e.g.vanadium oxides)to obtain superior long-term cycling stability is a significant challenge.Herein,we demonstrate that polyvinyl alcohol(PVA)-assisted hydrated vanadium pentoxide/reduced graphene oxide(V_(2)O_(5)·n H_(2)O/r GO/PVA,denoted as the VGP)films enable long cycle stability and high capacity for the Li^(+)and Zn^(2+)storages in both the VGP//Li Cl(aq)//VGP and the VGP//Zn SO4(aq)//Zn cells.The binderfree VGP films are synthesized by a one-step hydrothermal method combination with the filtration.The extensive hydrogen bonds are formed among PVA,GO and H_(2)O,and they act as structural pillars and connect the adjacent layers as glue,which contributes to the ultrahigh specific capacitance and ultralong cyclic performance of Li^(+)and Zn^(2+)storage properties.As for Li^(+)storage,the binder-free VGP4 film(4mg PVA)electrode achieves the highest specific capacitance up to 1381 F g^(-1)at 1.0 A g^(-1)in the three-electrode system and 962 F g^(-1)at 1.0 A g^(-1)in the symmetric two-electrode system.It also behaves the outstanding cyclic performance with the capacitance retention of 96.5%after 15000 cycles in the three-electrode system and 99.7%after 25000 cycles in the symmetric two-electrode system.As for Zn^(2+)storage,the binder-free VGP4 film electrode exhibits the high specific capacity of 184 m A h g^(-1)at 0.5A g^(-1)in the VGP4//Zn SO4(aq)//Zn cell and the superb cycle performance of 98.5%after 25000 cycles.This work not only provides a new strategy for the construction of vanadium oxides composites and demonstrates the potential application of PVA-assisted binder-free film with excellent electrochemical properties,but also extends to construct other potential electrode materials for metal ion storage cells.
基金supported by the National Natural Science Foundation of China(Grant Nos.51072047,21271067)the Program for Innovative Research Team in University(Grant No.IRT-1237)
文摘Exfoliated graphite oxide was prepared by an improved Hummers method and was then reduced to graphene with hydrazine in the presence of ammonium hydroxide.N2adsorption–desorption measurement showed that graphene so obtained had a specific surface area as high as 818 m2/g.Galvanostatic charge/discharge curves demonstrated that the as-prepared graphene exhibited a specific capacitance of 186.9 F/g at a current density of 0.1 A/g and that about 96%of the specific capacitance was retained after 2000 cycles at a current density of 5 A/g.
基金supported by the Natural Science Foundation of Gansu,China(Grant No.20JR10RA611)。
文摘In this work,we report a high-performance self-standing supercapacitor electrode of mixed nickel manganese sulfides (NMSs)with a cracked-bark shape grown by one-step electrochemical deposition on activated carbon cloth (ACC).The electrode possesses outstanding electrochemical properties,including a high specific capacitance of up to 3142.8 F g^(-1)at 1.0 A g^(-1),the high-rate performance (~1206.8 F g^(-1)at 60.0 A g^(-1)),and cycle stability (~92.3%capacitance retention after 8000 cycles at8 A g^(-1)).An asymmetric supercapacitor assembled using NMSs on ACC as the cathode,activated carbon on carbon cloth as the anode and 1.0 mol L;KOH as the electrolyte delivers a high energy density of 111.2 W h kg^(-1)at 800.0 W kg^(-1)and the prominent cycling performance of~93.2%capacitance retention after 10000 cycles at 5 A g^(-1)with the Columbic efficiency of around 100%during these 10000 cycles.The high performance and facile preparation indicate that the NMSs on ACC hold a huge potential as the electrode for supercapacitors.
