Germanium-based material has attracted numerous attentions and been regarded as a promising anode material for lithium-ion batteries due to its high theoretical capacity.However,drastic pulverization and rapid capacit...Germanium-based material has attracted numerous attentions and been regarded as a promising anode material for lithium-ion batteries due to its high theoretical capacity.However,drastic pulverization and rapid capacity fading caused by large volume variation during cycling limit its practical application.In this work,three-dimensional N-doped carbon framework-wrapped Na_(4)Ge_(9)O_(20)nanoparticles(3D Na_(4)Ge_(9)O_(20)@N-C)have been synthesized via freeze-drying approach with NaCl as both template and sodium source for ion-exchanging.The employment of NaCl has two special roles:on the one hand,the NaCl crystals act as template and facilitate the formation of 3D porous structure,while on the other hand,the NaCl crystals serving as sodium source and support the ion exchange between NaCl and GeO_(2)promote the formation of Na_(4)Ge_(9)O_(20).Benefiting from the unique method,the prepared 3D Na_(4)Ge_(9)O_(20)@N-C not only suppresses the volume change by using carbon as buffer layers but also demonstrates an improved electronic conductivity and a shortened ionic diffusion.When utilized as an anode material for LIBs,the 3D Na_(4)Ge_(9)O_(20)@N-C composites deliver high reversible capacity(896.2 mAh·g^(-1)at0.1 A·g^(-1)after 100 cycles),good cycling stability(520.8 mAh·g^(-1)at 2.0 A·g^(-1)after 400 cycles)and excellent rate performance(636.0 mAh·g^(-1)at 2.0 A·g^(-1)).This work provides a strategy to improve the electrochemical performance of germanium-based anode materials for lithium-ion batteries.展开更多
In this work,azobenzene mesogen-containing tin thiolates have been synthesized,which possess ordered lamellar structures persistent to higher temperature and serve as liquid crystalline precursors.Based on the preorga...In this work,azobenzene mesogen-containing tin thiolates have been synthesized,which possess ordered lamellar structures persistent to higher temperature and serve as liquid crystalline precursors.Based on the preorganized tin thiolate precursors,Sn S nanocrystals encapsulated with in-situ N-doped carbon layer have been achieved through a simple solventless pyrolysis process with the azobenzene mesogenic thiolate precursor served as Sn,S,N,and C sources simultaneously.Thus prepared nanocomposite materials as anode of lithium ion batteries present a large specific capacity of 604.6 m Ah·g^（-1）at a current density of 100 m A·g^（-1）,keeping a high capacity retention up to 96% after 80 cycles,and display high rate capability due to the synergistic effect of well-dispersed Sn S nanocrystals and N-doped carbon layer.Such encouraging results shed a light on the controlled preparation of advanced nanocomposites based on liquid crystalline metallomesogen precursors and may boost their novel intriguing applications.展开更多
In this paper, we report a one-step electrodeposited synthesis strategy for directly growing NiCoSe2/Ni3Se2 lamella arrays(LAs) on N-doped graphene nanotubes(N-GNTs) as advanced free-standing positive electrode for as...In this paper, we report a one-step electrodeposited synthesis strategy for directly growing NiCoSe2/Ni3Se2 lamella arrays(LAs) on N-doped graphene nanotubes(N-GNTs) as advanced free-standing positive electrode for asymmetric supercapacitors. Benefiting from the synergetic contribution between the distinctive electroactive materials and the skeletons, the as-constructed N-GNTs@NiCoSe2/Ni3-Se2LAs present a specific capacitance of ~1308 F g^-1 at a current density of 1 A g^-1. More importantly, the hybrid electrode also reveals excellent rate capability(~1000 F g^-1 even at 100 A g^-1) and appealing cycling performance(~103.2% of capacitance retention over 10,000 cycles). Furthermore, an asymmetric supercapacitor is fabricated by using the obtained N-GNTs@NiCoSe2/Ni3Se2LAs and active carbon(AC) as the positive and negative electrodes respectively,which holds a high energy density of 42.8 W h kg^-1 at 2.6 k W kg^-1, and superior cycling stability of ~94.4% retention over 10,000 cycles. Accordingly, our fabrication technique and new insight herein can both widen design strategy of multicomponent composite electrode materials and promote the practical applications of the latest emerging transition metal selenides in next-generation high-performance supercapacitors.展开更多
基金financially supported by the National Natural Science Foundation of China(No.51874362)the Scientific Research Project of Hunan Provincial Department of Education(No.21B0815)。
文摘Germanium-based material has attracted numerous attentions and been regarded as a promising anode material for lithium-ion batteries due to its high theoretical capacity.However,drastic pulverization and rapid capacity fading caused by large volume variation during cycling limit its practical application.In this work,three-dimensional N-doped carbon framework-wrapped Na_(4)Ge_(9)O_(20)nanoparticles(3D Na_(4)Ge_(9)O_(20)@N-C)have been synthesized via freeze-drying approach with NaCl as both template and sodium source for ion-exchanging.The employment of NaCl has two special roles:on the one hand,the NaCl crystals act as template and facilitate the formation of 3D porous structure,while on the other hand,the NaCl crystals serving as sodium source and support the ion exchange between NaCl and GeO_(2)promote the formation of Na_(4)Ge_(9)O_(20).Benefiting from the unique method,the prepared 3D Na_(4)Ge_(9)O_(20)@N-C not only suppresses the volume change by using carbon as buffer layers but also demonstrates an improved electronic conductivity and a shortened ionic diffusion.When utilized as an anode material for LIBs,the 3D Na_(4)Ge_(9)O_(20)@N-C composites deliver high reversible capacity(896.2 mAh·g^(-1)at0.1 A·g^(-1)after 100 cycles),good cycling stability(520.8 mAh·g^(-1)at 2.0 A·g^(-1)after 400 cycles)and excellent rate performance(636.0 mAh·g^(-1)at 2.0 A·g^(-1)).This work provides a strategy to improve the electrochemical performance of germanium-based anode materials for lithium-ion batteries.
基金Project supported by the National Natural Science Foundation of China(Grant No.21574062)the Huaian High-Technology Research Institute of Nanjing University,China(Grant No.2011Q1)
文摘In this work,azobenzene mesogen-containing tin thiolates have been synthesized,which possess ordered lamellar structures persistent to higher temperature and serve as liquid crystalline precursors.Based on the preorganized tin thiolate precursors,Sn S nanocrystals encapsulated with in-situ N-doped carbon layer have been achieved through a simple solventless pyrolysis process with the azobenzene mesogenic thiolate precursor served as Sn,S,N,and C sources simultaneously.Thus prepared nanocomposite materials as anode of lithium ion batteries present a large specific capacity of 604.6 m Ah·g^（-1）at a current density of 100 m A·g^（-1）,keeping a high capacity retention up to 96% after 80 cycles,and display high rate capability due to the synergistic effect of well-dispersed Sn S nanocrystals and N-doped carbon layer.Such encouraging results shed a light on the controlled preparation of advanced nanocomposites based on liquid crystalline metallomesogen precursors and may boost their novel intriguing applications.
基金supported by the National Natural Science Foundation of China (51672144, 51572137 and 51702181)the Natural Science Foundation of Shandong Province (ZR2017BB013 and ZR2019BEM042)+2 种基金Higher Educational Science and Technology Program of Shandong Province (J17KA014, J18KA001 and J18KA033)Taishan Scholars Program of Shandong Province (ts201511034)Overseas Taishan Scholars Program
文摘In this paper, we report a one-step electrodeposited synthesis strategy for directly growing NiCoSe2/Ni3Se2 lamella arrays(LAs) on N-doped graphene nanotubes(N-GNTs) as advanced free-standing positive electrode for asymmetric supercapacitors. Benefiting from the synergetic contribution between the distinctive electroactive materials and the skeletons, the as-constructed N-GNTs@NiCoSe2/Ni3-Se2LAs present a specific capacitance of ~1308 F g^-1 at a current density of 1 A g^-1. More importantly, the hybrid electrode also reveals excellent rate capability(~1000 F g^-1 even at 100 A g^-1) and appealing cycling performance(~103.2% of capacitance retention over 10,000 cycles). Furthermore, an asymmetric supercapacitor is fabricated by using the obtained N-GNTs@NiCoSe2/Ni3Se2LAs and active carbon(AC) as the positive and negative electrodes respectively,which holds a high energy density of 42.8 W h kg^-1 at 2.6 k W kg^-1, and superior cycling stability of ~94.4% retention over 10,000 cycles. Accordingly, our fabrication technique and new insight herein can both widen design strategy of multicomponent composite electrode materials and promote the practical applications of the latest emerging transition metal selenides in next-generation high-performance supercapacitors.
