| With the depletion of traditional fossil fuels,there is an urgent need to develop sustainable clean energy and energy storage devices.Among them,lithium-ion batteries,supercapacitors and other new electrochemical energy storage devices have been applied in many fields.Supercapacitors have the characteristics of fast charging and discharging speed,long cycle life,wide operating temperature range and high power density,while lithium-ion batteries have the characteristics of high working voltage and high energy density,but the charging and discharging time is longer.Therefore,supercapacitors and lithium-ion batteries can form complementary modes to some extent.Among many materials,porous carbon materials have good application prospects in supercapacitors and lithium-ion batteries due to their good conductivity,controllable specific surface area and complex pore structure.The purpose of this paper is to design porous carbon materials for supercapacitors and lithium-ion battery anodes by simple and efficient methods.The main contents of this paper are as follows:1.Mesoporous carbon nanotube microspheres supported microporous pyrolyticcarbon for high-performance supercapacitors.Carbon nanotube?CNT?microspheres,carbon nanotube-acetylene black?CNT-AB?microspheres and carbon nanotube-ketjen black?CNT-KB?microspheres?named as CTMS,CAMS and CKMS,respectively?were prepared by spray drying method.These materials have large specific surface area and pore volume,especially for the CKMS.Owing to the absorbing capacity of CTMS,CAMS and CKMS,the phenolic resin are readilyabsorbed into the sphere and can be transformed into activated carbon?AC?by KOH activation,and thus the CNT/AC,CNT-AB/AC and CNT-KB/AC porous carbon composites are obtained.The CNT/AC,CNT-AB/AC and CNT-KB/AC electrodes with an areal density of 3 mg cm-3 can achieve areal capacitance of 232.6,179.5 and 506.9mF cm-2,respectively,at the current density of 0.2 A g-1 in 6M KOH solution.The CNT-KB/AC exhibits higher areal capacitance than the other two materialsbecause that the CNT-KB/AC consists of 3D uniform microspheres with CNT-KB as the framework and activated carbon as the core.The micropores in activated carbon can shortenthe diffusion pathway of lithium ions,and while the CKMS can compensate for the low electronic conductivity of microporous activated carbon.However,in the other two materials,besides the active carbon exists in the spheres,it also exists outside the spheres,which will reduce the capacity and rate performance.When the areal density of electrode active material is increased up to 9mg cm-2,the areal capacitance of CNT-KB/AC is increased up to 998.9 mF cm-2 at0.2 A g-1 and 724.9 mF cm-2 at 20 A g-1,respectively.Furthermore,it exhibits excellent long-term cycling stability.These results indicate that the CNT-KB/AC composite is a promising electrode material for high-areal-density supercapacitors.2.Preparation of Co3O4-CKMS composite as an anode material for lithium ion batteries.Firstly,CKMS porous carbon skeleton was prepared by spray drying method,and then Co3O4-CKMS composite microspheres were prepared by solvothermal method using Co?NO3?2·6H2O as raw material.Co3O4as anode material for Li-ion batteries has attracted much attention due to its high theoretical specific capacity(890 mAh g-1).However,Co3O4 has the disadvantages of volume expansion during cycling and low conductivity,leading to poor cycling performance and rate performance.In this paper,the Co3O4-CKMS composite is synthesized by solvothermal method.CKMS can not only provide three-dimensional conductive network,but also alleviate the volume expansion of Co3O4 in the process of cycling,thus improving the cycling performance and rate performance.The specific capacity of 583 mAh g-1of the Co3O4-CKMS composite at the high current density of 2A g-1is significantly higher than that of Co3O4(62 mAh g-1).These results demonstrated thatthe Co3O4-CKMS composite would be a promising anode material for lithium ion batteries. |
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