Silicon (Si) is a promising anode material for next-generation high-energy lithium-ion batteries (LIBs) due to its high capacity.However,the large volumetric expansion,poor ion conductivity and unstable solid electrol...Silicon (Si) is a promising anode material for next-generation high-energy lithium-ion batteries (LIBs) due to its high capacity.However,the large volumetric expansion,poor ion conductivity and unstable solid electrolyte interface (SEI) lead to rapid capacity fading and low rate performance.Herein,we report Si nitride (SiN) comprising stoichiometric Si_(3)N_(4) and Li-active anazotic SiN_(x) coated porous Si (p-Si@SiN)for high-performance anodes in LIBs.The ant-nest-like porous Si consisting of 3D interconnected Si nanoligaments and bicontinuous nanopores prevents pulverization and accommodates volume expansion during cycling.The Si_(3)N_(4) offers mechanically protective coating to endow highly structural integrity and inhibit superfluous formation of SEI.The fast ion conducting Li_(3)N generated in situ from lithiation of active SiN_(x) facilitates Li ion transport.Consequently,the p-Si@SiN anode has appealing electrochemical properties such as a high capacity of 2180 mAh g^(-1)at 0.5 A g^(-1) with 84%capacity retention after 200cycles and excellent rate capacity with discharge capacity of 721 mAh g^(-1) after 500 cycles at 5.0 A g^(-1).This work provides insights into the rational design of active/inactive nanocoating on Si-based anode materials for fast-charging and highly stable LIBs.展开更多
A method to identify complex Young＇s modulus of viscoelastic materials using forced longitudinal vibration of slender rods is proposed. The method differs from the beam one. Experimental tests were carried out at roo...A method to identify complex Young＇s modulus of viscoelastic materials using forced longitudinal vibration of slender rods is proposed. The method differs from the beam one. Experimental tests were carried out at room temperature with different lengths in 108 mm, 100 mm, 90 ram, 83.5 mm, 80 ram, 74.5 mm, 70 mm for the polycarbonate bars, and the curves of ratios A2/A1 between two ends of a viscoelastic bar versus frequencies are obtained, furthermore, the corresponding 3 dB bandwidth and the storage and loss modulus can be calculated. Sufficient number of obtained complex Young＇s modulus at different frequency allows us to calculate other ones using the least square method. If the step of the tested frequency is 5 Hz, the maximum error of results can be less than 6%. By comparison with the measurement methods which the previous literature mentioned, this new method simplifies the calculation, and the physical meaning appears apparently and clearly.展开更多
Heteroanionic oxysulfide perovskite compounds represent an emerging class of new materials allowing for a wide range of tunability in the electronic structure that could lead to a diverse spectrum of novel and improve...Heteroanionic oxysulfide perovskite compounds represent an emerging class of new materials allowing for a wide range of tunability in the electronic structure that could lead to a diverse spectrum of novel and improved functionalities.Unlike cation ordered double perovskites—where the origins and design rules of various experimentally observed cation orderings are well known and understood—anion ordering in heteroanionic perovskites remains a largely uncharted territory.展开更多
基金financially supported by the National Natural Science Foundation of China (U2004210, 51974208, U2003130, 21875080, 52002297)the Outstanding Youth Foundation of Natural Science Foundation of Hubei Province (2020CFA099)+2 种基金the Special Project of Central Government for Local Science and Technology Development of Hubei Province (2019ZYYD024)the Innovation group of Natural Science Foundation of Hubei Province (2019CFA020)the City University of Hong Kong Strategic Research Grants (7005505)。
文摘Silicon (Si) is a promising anode material for next-generation high-energy lithium-ion batteries (LIBs) due to its high capacity.However,the large volumetric expansion,poor ion conductivity and unstable solid electrolyte interface (SEI) lead to rapid capacity fading and low rate performance.Herein,we report Si nitride (SiN) comprising stoichiometric Si_(3)N_(4) and Li-active anazotic SiN_(x) coated porous Si (p-Si@SiN)for high-performance anodes in LIBs.The ant-nest-like porous Si consisting of 3D interconnected Si nanoligaments and bicontinuous nanopores prevents pulverization and accommodates volume expansion during cycling.The Si_(3)N_(4) offers mechanically protective coating to endow highly structural integrity and inhibit superfluous formation of SEI.The fast ion conducting Li_(3)N generated in situ from lithiation of active SiN_(x) facilitates Li ion transport.Consequently,the p-Si@SiN anode has appealing electrochemical properties such as a high capacity of 2180 mAh g^(-1)at 0.5 A g^(-1) with 84%capacity retention after 200cycles and excellent rate capacity with discharge capacity of 721 mAh g^(-1) after 500 cycles at 5.0 A g^(-1).This work provides insights into the rational design of active/inactive nanocoating on Si-based anode materials for fast-charging and highly stable LIBs.
基金supported by the Fundamental Research Funds of China for the Central Universities(GK201001008)
文摘A method to identify complex Young＇s modulus of viscoelastic materials using forced longitudinal vibration of slender rods is proposed. The method differs from the beam one. Experimental tests were carried out at room temperature with different lengths in 108 mm, 100 mm, 90 ram, 83.5 mm, 80 ram, 74.5 mm, 70 mm for the polycarbonate bars, and the curves of ratios A2/A1 between two ends of a viscoelastic bar versus frequencies are obtained, furthermore, the corresponding 3 dB bandwidth and the storage and loss modulus can be calculated. Sufficient number of obtained complex Young＇s modulus at different frequency allows us to calculate other ones using the least square method. If the step of the tested frequency is 5 Hz, the maximum error of results can be less than 6%. By comparison with the measurement methods which the previous literature mentioned, this new method simplifies the calculation, and the physical meaning appears apparently and clearly.
基金G.P.,C.R.S.,and B.P.U.gratefully acknowledge support from the Laboratory Directed Research and Development program of Los Alamos National Laboratory under project#20190043DRLos Alamos National Laboratory is operated by Triad National Security,LLC,for the National Nuclear Security Administration of US Department of Energy(Contract No.89233218CNA000001)+1 种基金S.T.H.and R.M.acknowledge support from the National Science Foundation through DMR-1806147Computational support for this work was provided by LANL’s high-performance computing clusters.
文摘Heteroanionic oxysulfide perovskite compounds represent an emerging class of new materials allowing for a wide range of tunability in the electronic structure that could lead to a diverse spectrum of novel and improved functionalities.Unlike cation ordered double perovskites—where the origins and design rules of various experimentally observed cation orderings are well known and understood—anion ordering in heteroanionic perovskites remains a largely uncharted territory.
