Modification Of Nanoporous Silicon-based Anode Materials And Study On Their Lithium Storage Performance

With the development of society and the progress of science and technology,the demand for high specific energy lithium ion batteries is becoming more and more urgent.However,commercial graphite-based anode materials cannot meet the needs of the current market due to their relatively low theoretical capacity(372 mAh g^-1).Therefore,the development of a newly generation of high specific capacitance anode material has become the focus of research.Among the many alternative materials,silicon?Si?,an alloy type anode material,has attracted much attention because of its high theoretical capacity,abundant reserves and low price.However,Si as a semiconductor material,its intrinsic conductivity is relatively poor.And its bulk expansion is very large?>300%?during the charge/discharge cycle,which can easily lead to structural collapse,unstable electrode-electrolyte interface,and eventually active material shedding electrode damage.Based on the above problems,in this paper,the Si anode electrode material was nanostructure treated by dealloying method,and the suitable metal/carbon material was selected for conductive modification,and then the Si anode material with excellent electrochemical performance was obtained.The main research contents of this paper are as follows:?1?Through combination with alloy phase diagram analysis,we have carefully designed and refined different proportions of SiAl,SiNiAl and SiZnAl alloys.By optimizing the corrosion conditions,the suitable corrosion conditions are selected to etch the more active aluminum atoms.Thus obtaining 3D interconnected nanopore structures such as nano macropores?MP?Si/Ni,nanoporous?NP?SiAl and SiZn composites.Followed by conductive modification treatment to improve the electrical conductivity of Si.?2?Structural and morphological characterization of the as-prepared MP-Si/Ni/C,NP-SiAl/GQDs and NP-Si Zn composites.Through SEM and TEM characterization,it can be seen that the corroded composite is composed of 3D interconnected pore structure.The structure is composed of Si-based skeleton ligaments of the main body and doped modified metal.Through EDS,XRD,XPS and Raman analysis,the material composition after corrosion is uniform and the content is controllable.?3?Further electrochemical performance tests have been carried out and the electrical conductivity of Si has been greatly improved due to the introduction of modified metal/carbon materials.The Si-based materials exhibit high reversible capacity,excellent cycling performance,and outstanding rate capability.In this paper,the Si-based anode materials prepared by dealloying method with simple preparation method and excellent electrochemical performance,which show a broad application prospect in the development and utilization of next-generation lithium ion batteries.