Lithium Storage Performances Of Controllably Dealloyed Fe-Si-Al Alloys

The high-specific capacity silicon-based anodes will experience serious volume expansion during the cycle,resulting in cracking,pulverization,shedding and rapid capacity attenuation of the electrodes,which seriously restricts its commercial application.In order to solve the above problems,starting with the composition modification and structure design of silicon-based lithium-ion anodes,this paper synthesized silicon-based anodes with different structures and components.The dual network porous Si/Al₉Fe Si₃/Fe₂O₃composites was fabricated by dealloying Fe_1.9Si_10.1Al₈₈alloy,and the influences of the structure of the dealloyed product during different dealloying time was studied.Meanwhile,the microstructure changes of the dealloyed product Si/Fe₂O₃were discussed by ball milling and dealloying processes,nano-Si/Fe₂O₃/r GO anodes were prepared under different methods,and their morphology was analyzed.In addition,the electrochemical performance of these anodes for lithium-ion batteries were investigated.The relationship among dealloying/preparation process parameters,microstructure and electrochemical properties was established.Finally,these anodes with unique three-dimensional porous network structure and excellent electrochemical properties were developed.This work can provide a unique design idea for the design and synthesis of nano-silicon based dual-network porous composite and three-dimensional multi-connected conductive network composite to improve the electrochemical performance of lithium ion battery anodes.In addition,the relatively inexpensive raw materials and without precious metals or heavy metal elements present a good prospect of the anode material for LIB applications.In this paper,low-capacity Al₉Fe Si₃and Fe₂O₃were mixed into a high-capacity Si anode,and a dual network(the porous Si/Al₉Fe Si₃ligamental network together with Fe₂O₃nanosheet network)structure was formed.The dual network structure has high porosity and large specific surface area,which can ensure the structural stability of the Si/Al₉Fe Si₃/Fe₂O₃electrode.The electrode shows an excellent stability in the long-term cycling test,and achieves a reversible capacity of 378 m Ah g^-1after 500 cycles at a high current density of4000 m A g^-1.To attain the excellent electrochemical performance,the Si/Fe₂O₃nanomaterial was obtained by ball milling and dealloying processes.A stable cycling performance was achieved when using it as anode material,while the rate performance was still not satisfying.r GO is used as a carbon source additive owing to its high conductivity and abundant voids.The composite,consists of nano-silicon particles,Fe₂O₃nanosheets and r GO,was prepared by a ball milling method.When serving as an anode,remarkable cycle stability and rate performance were achieved.A high discharge specific capacity of1744.5 m Ah g^-1was obtained at current density of 200 m A g^-1after 200 cycles,and the reversible capacity of 889.4 m Ah g^-1was still maintained after 500 cycles at a high current density of 5000 mA g^-1.