As a promising anode material for next-generation high-energy density lithium-ion batteries (LIBs), one of the main technical issues for silicon (Si) electrodes is the low initial Coulombic efficiency (ICE). By a pre-lithiation process, preparation of lithium–silicon (Li–Si) alloy electrodes can efficiently improve the ICE, thus leading to excellent electrochemical performance. Herein, with solid wastes as precursors, we report a cost-efficient approach for the fabrication of Li3.25Si anode materials via simple magnesiothermic reduction and then mechanical alloy reaction methods, combining the advantages of low-cost and high ICE. The prepared Li3.25Si@acetylene black (Li3.25Si@A) electrode exhibits excellent electrochemical performance with a high reversible capacity of 1138.9 mA h g−1 over 90 cycles at a current density of 100 mA g−1 and its ICE is as high as 107.7%, which is superior to that of the commercial Li3.25Si@A electrode. With a simple and low-cost manufacturing process and high ICE, the fabrication process will be definitely meaningful in achieving low-cost and high-capacity anode materials with a prolonged cycle life.
Xiangyang Zhuang,Yao Zhang,Lingxiao He,Yunfeng Zhu,Quan Shi,Quan Wang,Guanzhou Song,Xiaoxiao Yan,Liquan Li
Overheating caused by exothermic effect of magnesiothermic reduction reaction is usually considered as a drawback in preparing porous silicon anode materials for Li-ion batteries. However, in the present work, thermal effect is available in facile preparation of macroporous Si by tabletting pretreatment . The released heat in magnesiothermic reaction is easily accumulated on the tablet with high density, leading to the collapse of the mesoporous structure of the precursor and formation of uniform macroporous silicon . Such macroporous silicon shows a higher initial Coulomb efficiency (86.5%) and enhanced cycling stability in comparison with mesoporous silicon prepared without tabletting treatment. XRD analysis indicates that the reaction temperature decreases to 430–435 °C (based on set temperature), much lower than that of the reaction without pretreatment. Since the structure of product has less dependency on precursor, a wide variety of precursors can be used to synthesize macroporous silicon, e.g. low cost biosilica. Being ascribed to low reaction temperature, heating rate insensitivity, less dependency on precursor, enhanced cycling performance and high initial Coulomb efficiency of the Si products, the modified magnesiothermic reduction method is promising for application in fabricating Si anode.
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