Nano-silicon(nano-Si)and its composites have been regarded as the most promising negative electrode materials for producing the next-generation Li-ion batteries(LIBs),due to their ultrahigh theoretical capacity.Howeve...Nano-silicon(nano-Si)and its composites have been regarded as the most promising negative electrode materials for producing the next-generation Li-ion batteries(LIBs),due to their ultrahigh theoretical capacity.However,the commercial applications of nano Si-based negative electrode materials are constrained by the low cycling stability and high costs.The molten salt electrolysis of SiO_(2)is proven to be suitable to produce nano-Si with the advantages of in-situ microstructure control possibilities,cheap affordability and scale-up process capability.Therefore,an economical approach for electrolysis,with a SiO_(2)/graphite porous electrode as cathode,is adopted to produce nano-Si/graphite composite negative electrode materials(SGNM)in this study.The electrolytic product of the optimized porous electrode is taken as the negative electrode materials for LIBs,and it offers a capacity of 733.2 mAh·g^(-1)and an initial coulombic efficiency of 86.8%in a coin-type cell.Moreover,the capacity of the SGNM retained 74.1%of the initial discharging capacity after 50 cycles at 0.2C,which is significantly higher than that of the simple mixture of silicon and graphite obtained from the formation of silicon carbide(SiC)between nano-Si and graphite particles.Notably,this new approach can be applied to a large-scale production.展开更多
Vanadium nitride(VN)-based materials have been investigated as negative electrode materials for supercapacitors(SCs)owing to their high theoretical capacitances and suitable negative potential windows.However,viable V...Vanadium nitride(VN)-based materials have been investigated as negative electrode materials for supercapacitors(SCs)owing to their high theoretical capacitances and suitable negative potential windows.However,viable VNbased negative electrode materials suffer from irreversible electrochemical oxidation of the soluble vanadium species,leading to rapid capacitance fading when operated in aqueous electrolytes.Developing a versatile approach to enhance the stability of VN in aqueous electrolytes is still a challenge.Here,an interface engineering strategy is developed to intentionally introduce surface nanolayers of vanadium oxides(VO_(x))as a reactive template on the VN surface to formulate welldesigned polypyrrole@VNO(Ppy@VNO)core-shell nanowires(NWs)incorporated into a 3D porous N-doped graphene(NG)hybrid aerogel as a durable negative electrode for SCs.Experimental and theoretical investigations reveal that the in-situ constructed Ppy@VNO core-shell host can offer more efficient pathways for rapid electron/ion transport and accessible electroactive sites.Most importantly,a reversible surface redox reaction is realized through the transformation of the valence state of V,and a long cyclic stability is achieved.The Ppy@VNO/NG hybrid aerogel can deliver a high specific capacitance of 650 F g^(-1) at 1 A g^(-1) with approximately 70.7%capacitance retention(up to the twenty-fold current density),and an excellent cycling stability without any capacitance decay after 10,000 cycles at both low and high current densities(1 and 10 A g^(-1),respectively).This work paves the way for the development of advanced electrode materials for SCs.展开更多
Developing advanced negative electrode materials with high capacity for supercapacitors currently remains a challenge.To address this issue,an effective strategy through a simple electric field-induced anion exchange ...Developing advanced negative electrode materials with high capacity for supercapacitors currently remains a challenge.To address this issue,an effective strategy through a simple electric field-induced anion exchange process was raised to prepare a novel nanostructured CuCo_(2)S_(x)(OH)_(y) heterostructure based on CuCo_(2)S_(4) nanosheets as the substrate.Notably,the unique nano-heterostructure featured an extremely high area specific capacitance of 2.94 F cm^(−2) at 5 mA cm^(−2) and exhibited excellent cycle life and rate capacity.Moreover,the corresponding assembled supercapacitors using the obtained CuCo_(2)S_(x)(OH)_(y) heterostructure as the negative electrode exhibited superior capacitive performance.More specifically,the assembled hybrid supercapacitor possessed a high energy density of 0.54 mW h cm^(−2) at a power density of 4.01 mW cm^(−2) and the capacitance retention rate was 94.7%even after 10000 cycles,which confirmed the practicality of the synthesized negative electrode material.Density functional theory calculations further showed that an enhanced conductivity and increased OH^(−) adsorption capability could be achieved in the CuCo_(2)S_(x)(OH)_(y) nano-heterostructure.This work presents a feasible and effective in situ anion exchange strategy to construct the CuCo_(2)S_(x)(OH)_(y) nano-heterostructure as a negative electrode material toward high-performance supercapacitors,improving the current deficiency of negative electrode materials.展开更多
Aqueous magnesium ion supercapacitors(MISs)have attracted attention due to their safety,low cost and environmental friendliness.However,the cycling stability of MISs is usually not ideal due to magnesium ion plating i...Aqueous magnesium ion supercapacitors(MISs)have attracted attention due to their safety,low cost and environmental friendliness.However,the cycling stability of MISs is usually not ideal due to magnesium ion plating in/stripping from the negative electrode materials.Here,we demonstrate that MoS_(2)with expanded interlayer spacing(E-MoS_(2)),obtained via a facile method,is a prospective negative electrode material for rechargeable MISs,because the expanded layer spacing reduces ion diffusion resistance and provides more active sites for ion interaction.展开更多
To overcome the limitations of graphite as a negative electrode material for lithium-ion batteries(LIBs),transition metal oxyfluorides are under active development.In this study,chromium oxyfluorides CrO_(2-x)F_(x)wit...To overcome the limitations of graphite as a negative electrode material for lithium-ion batteries(LIBs),transition metal oxyfluorides are under active development.In this study,chromium oxyfluorides CrO_(2-x)F_(x)with 0≤x≤0.3 were synthesized under a high-pressure/high-temperature(HP/HT)environment,and their electrochemical properties were examined in a nonaqueous lithium cell.展开更多
Aluminum metal is a promising negative electrode material for next generation rechargable batteries while the developed positive electrode materials of current aluminum batteries still have diffculty in meeting the de...Aluminum metal is a promising negative electrode material for next generation rechargable batteries while the developed positive electrode materials of current aluminum batteries still have diffculty in meeting the demands for high energy density.With a higher electrical conductivity than that of sulfur and selenium in chalcogen-based positive electrode materials,tellurium with high theoretical specific capacity(1260 mA h g^(−1))still suffers from severe capacity loss induced by the chemical and electrochemical process in the Lewis acid electrolyte.For massively promoting the utilization of active materials and rechargeability at both positive and negative electrodes,a simple strategy is demonstrated to construct tellurium–aluminum batteries(ATBs)using acetylene black/polyvinylidenefluoride modified separators,and the assembled ATB delivers a discharge capacity of∼1120 mA h g^(−1)(at 0.5 A g^(−1))and a considerably promoted capacity retention of 400 mA h g^(−1)after 300 cycles(at 1.0 A g^(−1)).Such a simple approach offers a low-cost and high-effciency strategy to develop advanced aluminium batteries with high capacity and energy density.展开更多
基金This work was financially supported by the National Key Research and Development Program of China(No.2016YFB0301305)the Talent Plan Project of Beijing(No.2018000097607G378)the National Natural Science Foundation of China(U166420031).
文摘Nano-silicon(nano-Si)and its composites have been regarded as the most promising negative electrode materials for producing the next-generation Li-ion batteries(LIBs),due to their ultrahigh theoretical capacity.However,the commercial applications of nano Si-based negative electrode materials are constrained by the low cycling stability and high costs.The molten salt electrolysis of SiO_(2)is proven to be suitable to produce nano-Si with the advantages of in-situ microstructure control possibilities,cheap affordability and scale-up process capability.Therefore,an economical approach for electrolysis,with a SiO_(2)/graphite porous electrode as cathode,is adopted to produce nano-Si/graphite composite negative electrode materials(SGNM)in this study.The electrolytic product of the optimized porous electrode is taken as the negative electrode materials for LIBs,and it offers a capacity of 733.2 mAh·g^(-1)and an initial coulombic efficiency of 86.8%in a coin-type cell.Moreover,the capacity of the SGNM retained 74.1%of the initial discharging capacity after 50 cycles at 0.2C,which is significantly higher than that of the simple mixture of silicon and graphite obtained from the formation of silicon carbide(SiC)between nano-Si and graphite particles.Notably,this new approach can be applied to a large-scale production.
基金financially supported by the National Natural Science Foundation of China (52002059 and 51872204)the Belt&Road Young Scientist Exchanges Project of Science and Technology Commission Foundation of Shanghai (20520741000)+3 种基金Shanghai Belt and Road Joint Laboratory of Advanced Fiber and Lowdimension Materials (Donghua University)(18520750400)the Fundamental Research Funds for the Central Universities (20D110631)DHU Distinguished Young Professor Program (LZA2019001)the Open Research Fund of Shanghai Center for High Performance Fibers and Composites and Center for Civil Aviation Composites of Donghua University
文摘Vanadium nitride(VN)-based materials have been investigated as negative electrode materials for supercapacitors(SCs)owing to their high theoretical capacitances and suitable negative potential windows.However,viable VNbased negative electrode materials suffer from irreversible electrochemical oxidation of the soluble vanadium species,leading to rapid capacitance fading when operated in aqueous electrolytes.Developing a versatile approach to enhance the stability of VN in aqueous electrolytes is still a challenge.Here,an interface engineering strategy is developed to intentionally introduce surface nanolayers of vanadium oxides(VO_(x))as a reactive template on the VN surface to formulate welldesigned polypyrrole@VNO(Ppy@VNO)core-shell nanowires(NWs)incorporated into a 3D porous N-doped graphene(NG)hybrid aerogel as a durable negative electrode for SCs.Experimental and theoretical investigations reveal that the in-situ constructed Ppy@VNO core-shell host can offer more efficient pathways for rapid electron/ion transport and accessible electroactive sites.Most importantly,a reversible surface redox reaction is realized through the transformation of the valence state of V,and a long cyclic stability is achieved.The Ppy@VNO/NG hybrid aerogel can deliver a high specific capacitance of 650 F g^(-1) at 1 A g^(-1) with approximately 70.7%capacitance retention(up to the twenty-fold current density),and an excellent cycling stability without any capacitance decay after 10,000 cycles at both low and high current densities(1 and 10 A g^(-1),respectively).This work paves the way for the development of advanced electrode materials for SCs.
基金financially supported by the National Natural Science Foundation of China(21405105)the Shanghai Natural Science Foundation(14ZR1429300)the State Key Laboratory of Green Catalysis of Sichuan Institutes of Higher Education(LZJ1703).
文摘Developing advanced negative electrode materials with high capacity for supercapacitors currently remains a challenge.To address this issue,an effective strategy through a simple electric field-induced anion exchange process was raised to prepare a novel nanostructured CuCo_(2)S_(x)(OH)_(y) heterostructure based on CuCo_(2)S_(4) nanosheets as the substrate.Notably,the unique nano-heterostructure featured an extremely high area specific capacitance of 2.94 F cm^(−2) at 5 mA cm^(−2) and exhibited excellent cycle life and rate capacity.Moreover,the corresponding assembled supercapacitors using the obtained CuCo_(2)S_(x)(OH)_(y) heterostructure as the negative electrode exhibited superior capacitive performance.More specifically,the assembled hybrid supercapacitor possessed a high energy density of 0.54 mW h cm^(−2) at a power density of 4.01 mW cm^(−2) and the capacitance retention rate was 94.7%even after 10000 cycles,which confirmed the practicality of the synthesized negative electrode material.Density functional theory calculations further showed that an enhanced conductivity and increased OH^(−) adsorption capability could be achieved in the CuCo_(2)S_(x)(OH)_(y) nano-heterostructure.This work presents a feasible and effective in situ anion exchange strategy to construct the CuCo_(2)S_(x)(OH)_(y) nano-heterostructure as a negative electrode material toward high-performance supercapacitors,improving the current deficiency of negative electrode materials.
基金Financial support from theNationalNatural Science Foundation of China(21771064)the JST-ERATO Yamauchi Materials Space-Tectonics Project(JPMJER2003)is gratefully acknowledged.This work was performed in part at the Queensland node of the Australian National Fabrication Facility,a companyestablished under the National Collaborative Research Infrastructure Strategy to provide nano and microfabrication facilities for Australia's researchersThe authors are also grateful to the Taif University Researchers Supporting Project number(TURSP-2020/03),Taif University,Taif,KSA.
文摘Aqueous magnesium ion supercapacitors(MISs)have attracted attention due to their safety,low cost and environmental friendliness.However,the cycling stability of MISs is usually not ideal due to magnesium ion plating in/stripping from the negative electrode materials.Here,we demonstrate that MoS_(2)with expanded interlayer spacing(E-MoS_(2)),obtained via a facile method,is a prospective negative electrode material for rechargeable MISs,because the expanded layer spacing reduces ion diffusion resistance and provides more active sites for ion interaction.
基金The synchrotron XRD patterns were measured at the BL5S2 beamline of the Aichi Synchrotron Radiation Center,Aichi Science&Technology Foundation,Japan(Proposal No.201803038 and 201901008).
文摘To overcome the limitations of graphite as a negative electrode material for lithium-ion batteries(LIBs),transition metal oxyfluorides are under active development.In this study,chromium oxyfluorides CrO_(2-x)F_(x)with 0≤x≤0.3 were synthesized under a high-pressure/high-temperature(HP/HT)environment,and their electrochemical properties were examined in a nonaqueous lithium cell.
基金supported by the National Natural Science Foundation of China(No.51725401 and 51874019)the Fundamental Research Funds for the Central Universities(FRF-TP-17-002C2).
文摘Aluminum metal is a promising negative electrode material for next generation rechargable batteries while the developed positive electrode materials of current aluminum batteries still have diffculty in meeting the demands for high energy density.With a higher electrical conductivity than that of sulfur and selenium in chalcogen-based positive electrode materials,tellurium with high theoretical specific capacity(1260 mA h g^(−1))still suffers from severe capacity loss induced by the chemical and electrochemical process in the Lewis acid electrolyte.For massively promoting the utilization of active materials and rechargeability at both positive and negative electrodes,a simple strategy is demonstrated to construct tellurium–aluminum batteries(ATBs)using acetylene black/polyvinylidenefluoride modified separators,and the assembled ATB delivers a discharge capacity of∼1120 mA h g^(−1)(at 0.5 A g^(−1))and a considerably promoted capacity retention of 400 mA h g^(−1)after 300 cycles(at 1.0 A g^(−1)).Such a simple approach offers a low-cost and high-effciency strategy to develop advanced aluminium batteries with high capacity and energy density.
