Polypyrrole in-situ coated SiO as anode material for lithium-ion batteries with excellent cyclic performance

SiO has been used as a lithium-ion batteries anode material because of its low discharge voltage, low cost, low volume change (<200 %), high Li+ storage capacity and other advantages, becoming an increasing number of popular in recent years. However, due to the formation of by-products (solid electrolyte interphase and Li4SiO4) during the initial lithiation, SiO materials generally have poor initial coulombic efficiency (ICE) and cycling properties. To improve the electrochemical reaction kinetics and electron transport of SiO, polypyrrole (PPy) was synthesized at a molar ratio of 1:1:1 with H2SO4 as the acid medium at low temperature, and then SiO raw materials pretreated by 3-aminopropyltriethoxysilane were polymerized in-situ. After high temperature carbonization, the core-shell structure anode material of amorphous carbon coated SiO was prepared by using PPy as the carbonization precursor. The effects of different PPy bonding methods on the rate performance and cycle stability of the electrode were analyzed. The experimental result expresses that SiO/M@cPPy bonded by chemical bond has the best electrochemical performance, providing an ICE of 63.1 % and a discharge specific capacity of 1657.9 mAh g(-1), even achieving a reversible specific capacity of 780.8 mAh g(-1) with a capacity retention rate of 92.6 % at 0.5 A g(-1) after 280 cycles. The amorphous core-shell anode material significantly reduces the volume change of SiO during the process of lithiation/delithiation, and also provides a stable solid electrolyte interface and excellent electrical conductivity. The research provides new insights into organic coated inorganic SiO-based anode materials.