The Research On The Lithium Ion Storage Properties Of Carbon Matrix Composites With Structural Design

Renewable and clean energy is considered to be the important material basis for human survival and development.However,considering the generation of renewable energy is inherently intermittent and has strong regional characteristics,it's necessary to develop high-efficiency energy conversion technology.In addition,in order to release the strong dependence on fossil energy in future transportation systems and reduce carbon dioxide emissions,it is urgent to design a new kind of power source for electric vehicles,with environmental friendliness and high efficiency,to replace the traditional fuel engines.The lithium-ion batteries?LIBs?,with some advantages as high energy efficiency,no memory effect,long cycle life,high theoretical energy density an d high theoretical power density,has been the main energy storage equipment used in consumer electronics products,and also has powered several types of electric vehicles available on the market.Thus,LIBs have enormous potential for energy sustainabilit y and significant reductions in carbon emissions.However,the negative electrode materials of commercial LIBs are mostly graphite,whose low specific capacity limits the development of lithium ion batteries to higher capacity,longer life,a nd faster charge and discharge.Here,following the electrochemical therories,we prepared carbon-based materials based on micro-nano structural design with other modifications,and the electrochemical performance testing verified the improvement of material properties.?1?The polypyrrole?PPy?nanotube precursors were successfully transformed to one-dimensional hollow nitrogen-doped non-graphite carbon nanotubes by carbonization process,which have an average diameter of about 200 to 400 nm and a length of several tens of micrometers.The results show that the nitrogen-doped non-graphite carbon nanotubes could remain a capacity of 172 mAh g^-1 even under a current density of up to 4000 mA g^-1 after 2000 cycles.The improved electrochemical performance of carbon nanotubes can be attributed to their non-graphitic carbon,hollow tubular structures,heteroatom-modified and cross-linked conductive networks.?2?The transition metal oxides can compensate for the limited energy storage of carbon-based materials.Therefore,we synthesized in-situ carbon-coated bimetallic oxides with a 3D porous network structure by a simple solution combustion method.Benefiting from the synergistic effect between the ultrafine metal oxides and the conductive carbon layers,the ZnO-CoO@C anodes exhibited an improved specific capacity and extended cycle life(503 mAh g^-1 after 700 cycles at 2000 mA g^-1).A full battery module consisting of ZnO-CoO@C as a negative electrode and a commercially available material NCM523 as a positive electrode showed a high charge capacity of94 mAh g^-1 after 100 cycles at 100 mA g^-1.