Cobalt sulphides attract much attention as anode materials for Li-ion batteries(LIBs).However,its poor conductivity,low initial column efficiency and large volume changes during cycling have hindered its further devel...Cobalt sulphides attract much attention as anode materials for Li-ion batteries(LIBs).However,its poor conductivity,low initial column efficiency and large volume changes during cycling have hindered its further development.Herein,novel interlaced CoS nanosheets were firstly prepared on Carbon Fiber Cloth(CFC)by two hydrothermal reactions followed with carbon coating via carbonizing dopamine(CoS NS@C/CFC).As a freestanding anode,the nanosheet structure of CoS not only accommodates the volume variation,but also provides a large interface area to proceed the charge transfer reaction.In addition,CFC works as both a three-dimensional skeleton and an active substance which can further improve the areal capacity of the resulting electrode.Furthermore,the coated carbon combined with the CFC work as a 3D conductive network to facilitate the electron conduction.The obtained CoS NS@C/CFC,and the contrast sample prepared with the same procedure but without carbon coating(CoS NS/CFC),are characterized with XRD,SEM,TEM,XPS and electrochemical measurements.The results show that the CoS NS@C/CFC possesses much improved electrochemical performance due to the synergistic effect of nanosheet CoS,the coated carbon and the CFC substrate,exhibiting high initial columbic efficiency(~87%),high areal capacity(2.5 at 0.15 mA cm−2),excellent rate performance(1.6 at 2.73 mA cm−2)and improved cycle stability(87.5%capacity retention after 300 cycles).This work may provide a new route to explore freestanding anodes with high areal specific capacity for LIBs.展开更多
The charge transport and accumulation in oil-paper can cause the insulation degradation.So far,the most widely used model to simulate space charge transport and accumulation is the bipolar charge transport(BCT)model,w...The charge transport and accumulation in oil-paper can cause the insulation degradation.So far,the most widely used model to simulate space charge transport and accumulation is the bipolar charge transport(BCT)model,which can well simulate the space charge dynamics.However,there are two shortcomings in the algorithms for solving the BCT model.One is that there is almost no use of vectorisation technology,which may increase the complexity of the algorithm,the other is the usage of fixed step size which might bring extra computation cost.In view of this,an adaptive time‐stepping transient up-stream finite element method(FEM)is developed to solve the BCT model considering trapping/detrapping,as well as the recombination phenomenon under DC condition in this article.Then,a vectorisation technology is used in the method to optimise the al-gorithm.Moreover,the adaptive time‐stepping method is introduced in simulation to reduce computation time and calculation amount.Simulation results are obtained by programing and later presented,which are basically consistent with the corresponding experimental results.Therefore,the proposed method is expected to promote the opti-mization design of the oil-paper insulation system.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.21573109,21206069)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).
文摘Cobalt sulphides attract much attention as anode materials for Li-ion batteries(LIBs).However,its poor conductivity,low initial column efficiency and large volume changes during cycling have hindered its further development.Herein,novel interlaced CoS nanosheets were firstly prepared on Carbon Fiber Cloth(CFC)by two hydrothermal reactions followed with carbon coating via carbonizing dopamine(CoS NS@C/CFC).As a freestanding anode,the nanosheet structure of CoS not only accommodates the volume variation,but also provides a large interface area to proceed the charge transfer reaction.In addition,CFC works as both a three-dimensional skeleton and an active substance which can further improve the areal capacity of the resulting electrode.Furthermore,the coated carbon combined with the CFC work as a 3D conductive network to facilitate the electron conduction.The obtained CoS NS@C/CFC,and the contrast sample prepared with the same procedure but without carbon coating(CoS NS/CFC),are characterized with XRD,SEM,TEM,XPS and electrochemical measurements.The results show that the CoS NS@C/CFC possesses much improved electrochemical performance due to the synergistic effect of nanosheet CoS,the coated carbon and the CFC substrate,exhibiting high initial columbic efficiency(~87%),high areal capacity(2.5 at 0.15 mA cm−2),excellent rate performance(1.6 at 2.73 mA cm−2)and improved cycle stability(87.5%capacity retention after 300 cycles).This work may provide a new route to explore freestanding anodes with high areal specific capacity for LIBs.
基金supported in part by the National Natural Science Foundation of China(61473272,51867003)in part by the Natural Science Foundation of Guangxi(2018JJB160064,2018JJA160176)in part by the Guangxi Bagui Young Scholars Special Funding,and in part by the Boshike Award Scheme for Young Innovative Talents.
文摘The charge transport and accumulation in oil-paper can cause the insulation degradation.So far,the most widely used model to simulate space charge transport and accumulation is the bipolar charge transport(BCT)model,which can well simulate the space charge dynamics.However,there are two shortcomings in the algorithms for solving the BCT model.One is that there is almost no use of vectorisation technology,which may increase the complexity of the algorithm,the other is the usage of fixed step size which might bring extra computation cost.In view of this,an adaptive time‐stepping transient up-stream finite element method(FEM)is developed to solve the BCT model considering trapping/detrapping,as well as the recombination phenomenon under DC condition in this article.Then,a vectorisation technology is used in the method to optimise the al-gorithm.Moreover,the adaptive time‐stepping method is introduced in simulation to reduce computation time and calculation amount.Simulation results are obtained by programing and later presented,which are basically consistent with the corresponding experimental results.Therefore,the proposed method is expected to promote the opti-mization design of the oil-paper insulation system.
