Preparation Of Carbon-based Multi-composites For Energy Storage And Conversion

With the rapid growth of population and economic development,the global energy shortage is becoming more and more serious,and the environment is getting worse.All of which required people pay more attention to develop new energy.Lithium-ion battery and Supercapacitors,as a new type of chemical energy,has many advantages such as high voltage and capacity,excellent cycling stability,relatively high energy density,small self-discharge,no memory effect and wide operating range.Based on these preponderances,lithium-ion batteries have been widely used in communications equipment,audio-visual equipment,electronic equipment,industrial equipment,medical equipment and other fields.And in recent years,lithium-ion battery has been widely used in electric bicycles,electric vehicles,aerospace and other large-capacity energy storage equipment.However,commercial lithium-ion battery anode material is mainly used as graphite,and its theoretical specific capacity limits its capacity to further improve.At the same time,it is not suitable for rapid charge and discharge because of it is generally embedded in the lithium intercalation mode,which thus limiting its application in the field of high power.So we have been pay attention to improve the electrochemical properties of lithium-ion battery anode material.This work aimed to improve the electrochemical performance of lithium-ion batteries,synthesis composite materials based on metal materials and carbon nano materials through hydrothermal method.Besides,we discussed the effect of morphological characterization and structural properties to the electrochemical properties.The specific research contents and conclusions are as follows:(1)Carbon nanofibers(CNFs)were used as templates.Firstly,CNFs were acidified by nitric acid,then centrifugally washed and dispersed in water.The dispersed CNFs were mixed with aniline and sodium dodecylsulfate(SDS)to form a stable homogeneous mixture via ultrasound.Then,the aqueous solution(APS)acidified with hydrochloric acid was added to slowly under Ice water stirring overnight,and the resulting dispersion was centrifuged and washed three times to obtain polyaniline-coated carbon nano fibers(denoted as CNFs@PANl).Secondly,the Sodium molybdate(Na2MoO4)was added to resulting mixture and stirred at 80 ? for 30 minutes,followed by the sodium sulfide(Na2S)was added and the mixture was stirred at room temperature,and obtained the composite material of polyaniline-coated carbon nanofibers/molybdenum trisulfide(denoted as CNFs@PANI/MoS3).At last,the target composite material of N-doped carbon disulfide composites were(CNFs@NC/MoS2)was prepared by calcining at 800? for 2h.The hybrid two-dimensional nanostructured composite material can improve the electrochemical performance of Li-ion battery anode effectively,and the product performance is best at 600 ?.The specific capacity can reach 900.9 mA h g-1 after 80 cycles with the charge rate of 200 mA g-1.Furthermore,the specific capacity can still reach 998 mA h g-1 even at high current of 100 mA g-1.(2)We firstly prepared molybdenum disulfide through a one-step hydrothermal process,and then the diazonium salt of p-nitrobenzene tetrafluoroborate was grafted directly onto the flaky metal molybdenum sulfide by C-S covalent bond.Secondly,added metal zinc slowly to reduce nitrobenzene and get molybdenum disulfide/amino benzene composite materials under acetic acid environment.And then using ammonium persulfate catalysis,and react with aniline monomer in acidic environment to get polyaniline/molybdenum disulfide composite materials under the condition of ice bath.According to the electrochemical measure,we found the composite exhibits outstanding electrochemical performance in superncapacitors.This is probably due to the synergistic effect of molybdenum disulfide and polyaniline.On the one hand,the metal sulfide molybdenum disulfide can provide good electric double layer capacitance,and polyaniline can improve the conductivity of the material.On the other hand,after the composite of molybdenum disulfide and polyaniline,the material can make the electron recombination in a better channel and space for shuttle movement,which result to an excellent electrochemical performance.In summary,molybdenum disulfide/polyaniline composite electrode material has a broad application prospects in the supercapacitor electrode material.