The surface structure and material composition of current collectors have significant effects on the electrochemical performances of lithium-ion batteries(LIBs). In this work, a three-dimensional(3D) porous composite ...The surface structure and material composition of current collectors have significant effects on the electrochemical performances of lithium-ion batteries(LIBs). In this work, a three-dimensional(3D) porous composite framework is applied as the anode current collector in LIBs. This unique 3D skeleton is composed of conductive carbon fiber/Cu core/shell fibrous structure. With an oxidation treatment upon the copper shell, the porous framework is assembled with CuO microspheres. Using mesocarbon microbead(MCMB) graphite powders as the active material, the cell with this 3D porous composite current collector shows an improved reversible discharge-charge capacity of 415 mAh g^(–1) at a current rate of 0.1 C after 50 cycles, which is much higher than that of the cell with a flat Cu foil(127 mAh g^(–1)). It is demonstrated that this unique fibrous network of the 3D current collector coupled with the morphological effects of the CuO microspheres greatly improve the cell performance in terms of electrical conductivity, reversible capacity and cycling stability.展开更多
Porous structure and surface chemistry of activated carbon fibers obtained by differ-ent precursors and activation methods were investigated. Adsorption isotherms werecharacterized by nitrogen adsorption at 77K over a...Porous structure and surface chemistry of activated carbon fibers obtained by differ-ent precursors and activation methods were investigated. Adsorption isotherms werecharacterized by nitrogen adsorption at 77K over a relative pressure range from 10 6to 1. The regularization method according to Density Functional Theory (DFT) wasemployed to calculate the pore size distribution in the samples. Their specific surfaceareas were calculated by BET method, micropore volume and microporous specificsurface area calculated by t-plot method and MPD by Horvath-Kawazoe equation. Mi-cropore volume of rayon-based ACF was higher than that of other samples. The staticand dynamic adsorption capacity for formaldehyde on different ACFs was determined.The results show that steam activated Rayon-based A CFs had higher adsorption capac-ity than that of steam and KOH activated PAN-A CFs. Breakthrough curves illustratedthat Rayon-ACFs had longer breakthrough time, thus they possessed higher adsorp-tion capacity for formaldehyde than that of PAN-ACFs. The entire sample had smalladsorption capacity and short breakthrough time for water. Rayon-A CFs had exccl-lent adsorption selectivity for formaldehyde than PAN-ACFs. And the samples withhigh surface areas had relatively high adsorption capacity for formaldehyde. Elementaicontent of different A CFs were performed. Rayon-based A CFs contained more oxygenthan PAN-ACFs, which may be attributed to their excellent adsorption capacity forformaldehyde.展开更多
通过静电纺丝制备出碳纤维,然后高温退火处理获得氮掺杂多孔碳纤维,并将其作为硫的宿主材料,最终得到NCNFs/S正极材料。利用XRD、TG、TEM等对N-CNFs/S复合电极材料的结构和形貌进行表征。N-CNFs/S作为正极材料组装的锂硫电池的电化学性...通过静电纺丝制备出碳纤维,然后高温退火处理获得氮掺杂多孔碳纤维,并将其作为硫的宿主材料,最终得到NCNFs/S正极材料。利用XRD、TG、TEM等对N-CNFs/S复合电极材料的结构和形貌进行表征。N-CNFs/S作为正极材料组装的锂硫电池的电化学性能测试结果表明,在167 m A/g和836 m A/g的电流密度下,N-CNFs/S复合电极材料循环250圈和500圈后容量分别高达836 m A·h/g和631 m A·h/g;同时,N-CNFs/S复合电极材料还表现出良好的倍率性能。展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.51722504,51475172)the Natural Science Foundation of Guangdong Province(Grant No.2015A030306013)+1 种基金the Guangdong Science and Technology Plan Program(Grant Nos.2017A010104006,2017KZ010105)China Scholarship Fund(Grant No.201706155048)
文摘The surface structure and material composition of current collectors have significant effects on the electrochemical performances of lithium-ion batteries(LIBs). In this work, a three-dimensional(3D) porous composite framework is applied as the anode current collector in LIBs. This unique 3D skeleton is composed of conductive carbon fiber/Cu core/shell fibrous structure. With an oxidation treatment upon the copper shell, the porous framework is assembled with CuO microspheres. Using mesocarbon microbead(MCMB) graphite powders as the active material, the cell with this 3D porous composite current collector shows an improved reversible discharge-charge capacity of 415 mAh g^(–1) at a current rate of 0.1 C after 50 cycles, which is much higher than that of the cell with a flat Cu foil(127 mAh g^(–1)). It is demonstrated that this unique fibrous network of the 3D current collector coupled with the morphological effects of the CuO microspheres greatly improve the cell performance in terms of electrical conductivity, reversible capacity and cycling stability.
文摘Porous structure and surface chemistry of activated carbon fibers obtained by differ-ent precursors and activation methods were investigated. Adsorption isotherms werecharacterized by nitrogen adsorption at 77K over a relative pressure range from 10 6to 1. The regularization method according to Density Functional Theory (DFT) wasemployed to calculate the pore size distribution in the samples. Their specific surfaceareas were calculated by BET method, micropore volume and microporous specificsurface area calculated by t-plot method and MPD by Horvath-Kawazoe equation. Mi-cropore volume of rayon-based ACF was higher than that of other samples. The staticand dynamic adsorption capacity for formaldehyde on different ACFs was determined.The results show that steam activated Rayon-based A CFs had higher adsorption capac-ity than that of steam and KOH activated PAN-A CFs. Breakthrough curves illustratedthat Rayon-ACFs had longer breakthrough time, thus they possessed higher adsorp-tion capacity for formaldehyde than that of PAN-ACFs. The entire sample had smalladsorption capacity and short breakthrough time for water. Rayon-A CFs had exccl-lent adsorption selectivity for formaldehyde than PAN-ACFs. And the samples withhigh surface areas had relatively high adsorption capacity for formaldehyde. Elementaicontent of different A CFs were performed. Rayon-based A CFs contained more oxygenthan PAN-ACFs, which may be attributed to their excellent adsorption capacity forformaldehyde.
文摘通过静电纺丝制备出碳纤维,然后高温退火处理获得氮掺杂多孔碳纤维,并将其作为硫的宿主材料,最终得到NCNFs/S正极材料。利用XRD、TG、TEM等对N-CNFs/S复合电极材料的结构和形貌进行表征。N-CNFs/S作为正极材料组装的锂硫电池的电化学性能测试结果表明,在167 m A/g和836 m A/g的电流密度下,N-CNFs/S复合电极材料循环250圈和500圈后容量分别高达836 m A·h/g和631 m A·h/g;同时,N-CNFs/S复合电极材料还表现出良好的倍率性能。
