Doped two-dimensional(2D)materials hold significant promise for advancing many technologies,such as microelectronics,optoelectronics,and energy storage.Herein,n-type 2D oxidized Si nanosheets,namely n-type siloxene(n-...Doped two-dimensional(2D)materials hold significant promise for advancing many technologies,such as microelectronics,optoelectronics,and energy storage.Herein,n-type 2D oxidized Si nanosheets,namely n-type siloxene(n-SX),are employed as Li-ion battery anodes.Via thermal evaporation of sodium hypophosphite at 275℃,P atoms are effectively incorporated into siloxene(SX)without compromising its 2D layered morphology and unique Kautsky-type crystal structure.Further,selective nucleophilic substitution occurs,with only Si atoms being replaced by P atoms in the O_(3)≡Si-H tetrahedra.The resulting n-SX possesses two delocalized electrons arising from the presence of two electron donor types:(i)P atoms residing in Si sites and(ii)H vacancies.The doping concentrations are varied by controlling the amount of precursors or their mean free paths.Even at 2000 mA g^(-1),the n-SX electrode with the optimized doping concentration(6.7×10^(19) atoms cm^(-3))delivers a capacity of 594 mAh g^(-1) with a 73%capacity retention after 500 cycles.These improvements originate from the enhanced kinetics of charge transport processes,including electronic conduction,charge transfer,and solid-state diffusion.The approach proposed herein offers an unprecedented route for engineering SX anodes to boost Li-ion storage.展开更多
Lithium-sulfur batteries(LSBs)have emerged as promising power sources for high-performance devices such as electric vehicles.However,the poor energy density of LSBs owing to polysulfide shuttling and passivation has l...Lithium-sulfur batteries(LSBs)have emerged as promising power sources for high-performance devices such as electric vehicles.However,the poor energy density of LSBs owing to polysulfide shuttling and passivation has limited their further market penetration.To mitigate this challenge,two-dimensional(2D)siloxene(2DSi),a Si-based analog of graphene,is utilized as an additive for sulfur cathodes.The 2DSi is fabricated on a large scale by simple solvent extraction of calcium disilicide to form a thin-layered structure of Si planes functionalized with vertically aligned hydroxyl groups in the 2DSi.The stoichiometric reaction of 2DSi with polysulfides generates a thiosulfate redox mediator,secures the intercalation pathway,and reveals Lewis acidic sites within the siloxene galleries.The 2DSi utilizes the corresponding in-situ-formed electrocatalyst,the 2D confinement effect of the layered structure,and the surface affinity based on Lewis acid-base interaction to improve the energy density of 2DSi-based LSB cells.Combined with the commercial carbon-based current collector,2DSi-based LSB cells achieve a volumetric energy density of 612 Wh Lcell^(−1) at 1 mA cm^(−2) with minor degradation of 0.17%per cycle,which rivals those of state-of-the-art LSBs.This study presents a method for the industrial production of high-energy-dense LSBs.展开更多
Graphene,an emerging fabric of carbon atoms,has manifested its versatility in all kinds of fields encompassing electronics,optoelectronics,thermoelectrics,taking advantage of its excellent mechanical strength,exceptio...Graphene,an emerging fabric of carbon atoms,has manifested its versatility in all kinds of fields encompassing electronics,optoelectronics,thermoelectrics,taking advantage of its excellent mechanical strength,exceptional electronic and thermal conductivities,high surface specific area,and so forth.The prosperity of graphene never seen before has led the attention to silicene,siloxene,germanene,stanene,and plumbene due to their promising applications in the quantum spin Hall effect,topological insulator,batteries,capacitors,catalysis,and topological superconductivity.Herein,we review the existing production methods,numerous applications of two-dimensional group-IVA materials,and critically discuss the challenges of these materials,providing potential implications to the exploration of uncharted material systems.展开更多
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(2020R1A6A1A03045059)+1 种基金by Ministry of Science and ICT(2022R1A2C3003319)by the Institutional Program(2E33221)of the Korea Institute of Science and Technology(KIST).
文摘Doped two-dimensional(2D)materials hold significant promise for advancing many technologies,such as microelectronics,optoelectronics,and energy storage.Herein,n-type 2D oxidized Si nanosheets,namely n-type siloxene(n-SX),are employed as Li-ion battery anodes.Via thermal evaporation of sodium hypophosphite at 275℃,P atoms are effectively incorporated into siloxene(SX)without compromising its 2D layered morphology and unique Kautsky-type crystal structure.Further,selective nucleophilic substitution occurs,with only Si atoms being replaced by P atoms in the O_(3)≡Si-H tetrahedra.The resulting n-SX possesses two delocalized electrons arising from the presence of two electron donor types:(i)P atoms residing in Si sites and(ii)H vacancies.The doping concentrations are varied by controlling the amount of precursors or their mean free paths.Even at 2000 mA g^(-1),the n-SX electrode with the optimized doping concentration(6.7×10^(19) atoms cm^(-3))delivers a capacity of 594 mAh g^(-1) with a 73%capacity retention after 500 cycles.These improvements originate from the enhanced kinetics of charge transport processes,including electronic conduction,charge transfer,and solid-state diffusion.The approach proposed herein offers an unprecedented route for engineering SX anodes to boost Li-ion storage.
基金supported by the R&D Convergence Program of NST(National Research Council of Science&Technology)of the Republic of Korea(CAP-15-02-KBSI)a National Research Foundation of Korea(NRF)grant funded by the Korean Government(MSIT)(no.2019R1C1C1007745)a National Research Foundation of Korea(NRF)grant funded by the Korean Government(Ministry of Science,ICT&Future Planning)(no.2019R1A4A2001527).
文摘Lithium-sulfur batteries(LSBs)have emerged as promising power sources for high-performance devices such as electric vehicles.However,the poor energy density of LSBs owing to polysulfide shuttling and passivation has limited their further market penetration.To mitigate this challenge,two-dimensional(2D)siloxene(2DSi),a Si-based analog of graphene,is utilized as an additive for sulfur cathodes.The 2DSi is fabricated on a large scale by simple solvent extraction of calcium disilicide to form a thin-layered structure of Si planes functionalized with vertically aligned hydroxyl groups in the 2DSi.The stoichiometric reaction of 2DSi with polysulfides generates a thiosulfate redox mediator,secures the intercalation pathway,and reveals Lewis acidic sites within the siloxene galleries.The 2DSi utilizes the corresponding in-situ-formed electrocatalyst,the 2D confinement effect of the layered structure,and the surface affinity based on Lewis acid-base interaction to improve the energy density of 2DSi-based LSB cells.Combined with the commercial carbon-based current collector,2DSi-based LSB cells achieve a volumetric energy density of 612 Wh Lcell^(−1) at 1 mA cm^(−2) with minor degradation of 0.17%per cycle,which rivals those of state-of-the-art LSBs.This study presents a method for the industrial production of high-energy-dense LSBs.
基金This study was supported by the National Key R&D Program of China(2017YFB1104300 and 2016YFA0200200)Natural Science Foundation of China(NSFC)(No.21671020,51433005 and 51673026)+1 种基金NSFC-MAECI(51861135202),Beijing Natural Science Foundation(2172049)Analysis&Testing Center,Beijing Institute of Technology.
文摘Graphene,an emerging fabric of carbon atoms,has manifested its versatility in all kinds of fields encompassing electronics,optoelectronics,thermoelectrics,taking advantage of its excellent mechanical strength,exceptional electronic and thermal conductivities,high surface specific area,and so forth.The prosperity of graphene never seen before has led the attention to silicene,siloxene,germanene,stanene,and plumbene due to their promising applications in the quantum spin Hall effect,topological insulator,batteries,capacitors,catalysis,and topological superconductivity.Herein,we review the existing production methods,numerous applications of two-dimensional group-IVA materials,and critically discuss the challenges of these materials,providing potential implications to the exploration of uncharted material systems.
