New chemistry and new materials for high-energy-density batteries are in great demands as advanced portable electronics and long-range electric vehicles require ever increasing energy and power;current lithium(Li)-ion...New chemistry and new materials for high-energy-density batteries are in great demands as advanced portable electronics and long-range electric vehicles require ever increasing energy and power;current lithium(Li)-ion batteries based on graphite anode(a theoretical specific capacity of 372 mA h g^(-1))reach the limited theoretical energy density of 350 W h kg^(-1)[1].展开更多
V^(4+)-rich V_(2)O_(5)/carbon aerogel(V^(4+)-V_(2)O_(5)/CA)composites were synthesized as electrode materials for supercapacitors via in-situ hydrolysis-condensation processing.Carbon aerogel(CA)promotes the depositio...V^(4+)-rich V_(2)O_(5)/carbon aerogel(V^(4+)-V_(2)O_(5)/CA)composites were synthesized as electrode materials for supercapacitors via in-situ hydrolysis-condensation processing.Carbon aerogel(CA)promotes the deposition of amorphous vanadium oxide and catalyzes the crystallization of V^(4+)-rich V_(2)O_(5)nanosheets at much reduced temperature.With a uniform distribution of V_(2)O_(5)nanosheets in CA,the special structure provides a large specific area and reactive sites.CA also synergistically improves the electrical conductivity and structural integrity.In addition,rich V^(4+) would enhance the intrinsic electrical conductivity of V_(2)O_(5),promote ion diffusion and catalyze the electrochemical reactions.Consequently,V^(4+)-V_(2)O_(5)/CA exhibits much enhanced specific capacitance(405 F g^(-1) at 0.5 A g^(-1)),high energy density(56 W h kg^(-1) with a power density of 250 W kg^(-1))and long cycle life(96%capacitance retention after 40,000 cycles).展开更多
Co_(2)VO_(4) with Co tetrahedrons and octahedrons of transition metal oxides has achieved progress in electrocatalysts and batteries.However,high metal-metal interactions make it challenging to maintain high reactivit...Co_(2)VO_(4) with Co tetrahedrons and octahedrons of transition metal oxides has achieved progress in electrocatalysts and batteries.However,high metal-metal interactions make it challenging to maintain high reactivity as well as increase the conductivity and stability of supercapacitors.In this work,spinel-structured CoZn_(0.5)V_(1.5)O_(4) with a high specific surface area was synthesized through an ion-exchange process from the metal-organic frameworks of zinc-cobalt.Density functional theory calculations indicate that the replacement of transition metal by Zn can decrease the interaction between the transition metals,leading to a downshift in the π^(∗)-orbitals(V-O)and half-filled a_(1g) orbitals near the Fermi level,thus increasing the conductivity and stability of CoZn_(0.5)V_(1.5)O_(4).As a supercapacitor electrode,CoZn_(0.5)V_(1.5)O_(4) exhibits high cycling durability(99.4% capacitance retention after 18,000 cycles)and specific capacitance(1100mFcm^(-2) at 1mAcm^(-2)).This work provides the possibility of designing octahedral and tetrahedral sites in transition metal oxides to improve their electrochemical performance.展开更多
Oxygen vacancies are one of the most common defects.Defects are imperfections in the regular geometrical arrangement of the atoms in crystalline solid.There are point defects,linear defects,plane defects and volume de...Oxygen vacancies are one of the most common defects.Defects are imperfections in the regular geometrical arrangement of the atoms in crystalline solid.There are point defects,linear defects,plane defects and volume defects in crystals.In an elemental crystal,point defects are formed when atoms are removed from the position that should be filled in the crystal,creating vacancies,or when atoms occupy interstitial sites where no atom would ordinarily appear,causing interstitialcy[1].展开更多
文摘New chemistry and new materials for high-energy-density batteries are in great demands as advanced portable electronics and long-range electric vehicles require ever increasing energy and power;current lithium(Li)-ion batteries based on graphite anode(a theoretical specific capacity of 372 mA h g^(-1))reach the limited theoretical energy density of 350 W h kg^(-1)[1].
基金support from the National Natural Science Foundation of China(51872204,52072261,and 22011540379)Shanghai Sailing Program(21YF1430900)+2 种基金the National Key Research and Development Program of China(2017YFA0204600)Shanghai Social Development Science and Technology Project(20dz1201800)supported by the National Natural Science Foundation(1803256)。
文摘V^(4+)-rich V_(2)O_(5)/carbon aerogel(V^(4+)-V_(2)O_(5)/CA)composites were synthesized as electrode materials for supercapacitors via in-situ hydrolysis-condensation processing.Carbon aerogel(CA)promotes the deposition of amorphous vanadium oxide and catalyzes the crystallization of V^(4+)-rich V_(2)O_(5)nanosheets at much reduced temperature.With a uniform distribution of V_(2)O_(5)nanosheets in CA,the special structure provides a large specific area and reactive sites.CA also synergistically improves the electrical conductivity and structural integrity.In addition,rich V^(4+) would enhance the intrinsic electrical conductivity of V_(2)O_(5),promote ion diffusion and catalyze the electrochemical reactions.Consequently,V^(4+)-V_(2)O_(5)/CA exhibits much enhanced specific capacitance(405 F g^(-1) at 0.5 A g^(-1)),high energy density(56 W h kg^(-1) with a power density of 250 W kg^(-1))and long cycle life(96%capacitance retention after 40,000 cycles).
基金supported by the National Natural Science Foundation of China(51872204,52072261 and 22011540379)the National Key Research and Development Program of China(2017YFA0204600)+1 种基金Shanghai Social Development Science and Technology Project(20dz1201800)Shanghai Sailing Program(21YF1430900).
文摘Co_(2)VO_(4) with Co tetrahedrons and octahedrons of transition metal oxides has achieved progress in electrocatalysts and batteries.However,high metal-metal interactions make it challenging to maintain high reactivity as well as increase the conductivity and stability of supercapacitors.In this work,spinel-structured CoZn_(0.5)V_(1.5)O_(4) with a high specific surface area was synthesized through an ion-exchange process from the metal-organic frameworks of zinc-cobalt.Density functional theory calculations indicate that the replacement of transition metal by Zn can decrease the interaction between the transition metals,leading to a downshift in the π^(∗)-orbitals(V-O)and half-filled a_(1g) orbitals near the Fermi level,thus increasing the conductivity and stability of CoZn_(0.5)V_(1.5)O_(4).As a supercapacitor electrode,CoZn_(0.5)V_(1.5)O_(4) exhibits high cycling durability(99.4% capacitance retention after 18,000 cycles)and specific capacitance(1100mFcm^(-2) at 1mAcm^(-2)).This work provides the possibility of designing octahedral and tetrahedral sites in transition metal oxides to improve their electrochemical performance.
文摘Oxygen vacancies are one of the most common defects.Defects are imperfections in the regular geometrical arrangement of the atoms in crystalline solid.There are point defects,linear defects,plane defects and volume defects in crystals.In an elemental crystal,point defects are formed when atoms are removed from the position that should be filled in the crystal,creating vacancies,or when atoms occupy interstitial sites where no atom would ordinarily appear,causing interstitialcy[1].
