A Nanosilver Embedded Graphite-C Shell Coating on Large Size Micro Silicon Formed by Low Temperature Carbonizing with Ag+ Increased the Cross-Linking of Alginate as an Anode for LIBs

Abstract

Silicon (Si) is an aussichtsreich anode candidate for a new generation lithium-ion batteries on account of its enormous theoretical capacity. However, its progress is tremendously hindered due to the tremendous volumetric change causes structure instability and poor cycling stability during the charge/discharge cycle. To overcome these issues associated with Si anodes, fabricated Si/C composites have been extensively studied. Here, this paper exploits a method for preparing a Si/C composite at low temperature and under atmospheric conditions, which has a graphite-C layer embedded with nanosilver particles. Carboxyl-rich alginate as a carbon source which silicon-carbon was tightly bound due to forms strong bonds (hydrogen bond) on the silicon surface. Tiny silver ions (0.01 M) were added to improve carbon stability by enhancing the cross-linking of alginate coated on the surface of large size micro silicon powder. The Si/Ag@C ternary composites were obtained, which combined simultaneous synthesis of nanosilver and crack-free graphite-C by subsequent low-temperature carbonization at 480 °C. Si/Ag@C exhibits high conductivity and long period recycle stability due to inducing high conductivity of nanosilver and crack-free graphite-C as anodes for LIBs. Si/Ag@C shows a well reversible capacity (724 mAh/g) over 100 cycles at 200 mA/g, which is more than thirty times that of Si (21 mAh/g). Si/Ag@C shows low electrochemical impedance and satisfactory rate capability due to its special structure.