Synthesis Of Carbon-based Nanocomposites And Their Electrochemical Properties As Anodes For Lithium-ion Batteries

Worldwide energy crisis provides an opportunity for the development of new energy storage devices,among which lithium ion batteries?LIBs?has been widely used in business applications due to its advantages of high energy density,long cycling life and so on.While because of the hypergrowth of the portable electronic devices,electric automobile and charging stations,LIBs with better electrochemical performance are urgently required.However,unfortunately,the traditional anode material of the current commercial LIBs cannot satisfy the need,thus exploring new anode materials with higher capacity,more excellent rate capability and long-term cycling performance is getting increasingly important and becoming the research focus for the scientists.The work here aims at developing new alternative anode materials,mainly concentrating on the carbon-based nanocomposites material as following:?1?3D porous graphene-like?3D-PGL?was directly synthesized with agarics as the carbon source,Fe as the catalyst and KOH as the activator via a facile,economical and eco-friendly two-step solid-state transformation process.When tested as anode material for LIBs,it delivers a high capacity and excelle nt cycling performance,as high as 572 mAh g^-1after 1200 cycles'running at 0.2 A g^-1,much higher than that of the commercial graphite material.Meanwhile,a good rate performance is observed.Besides,when tuning the amount of the catalyst Fe,2D graphene sheet?2D-GS?and 3D porous carbon?3D-PC?is obtained.?2?Carbon well-coated Co₉S₈ nanocomposite?Co₉S₈/C-T?was synthesized with citric acid as the carbon source and NaCl as the soft template.When serving as anode material for LIBs,Co₉S₈/C-T exhibits a much higher capacity and better cycling performance(709 mAh g^-1 after 150 cycles at 0.2 A g^-1)compared to the Co₉S₈/C synthesized without any template(only 380 mAh g^-1 at the same test condition).What's more,even at 5 A g^-1,Co₉S₈/C-T still remain a capacity of 362 mAh g^-1,revealing an extraordinary rate capability.?3?ZnO/C nanocomposite was fabricated by the chemical vapor deposition?CVD?method of heating the camphor powder to deposit onto ZnO.Compared to the pure ZnO,ZnO/C nanocoposite displays a much higher capacity a nd better cycling performance(671mAh g^-1 for the sample ZnO/C after 350 cycles at 0.2 A g^-1 while only 57.7 mAh g^-1 for ZnO).However,because the ZnO was not well covered by the low content carbon,the structural stability during the charge-discharge process still need to be improved.