Low temperature growth of graphitic carbon on porous silicon for high-capacity lithium energy storage

With highly yield and low-cost micrometer-sized polycrystalline silicon powders, a hierarchical porous silicon (PS) structure is fabricated. As a novel passivated layer, graphitic carbon (GC) is in-situ growth on the three-dimensional surfaces of PS. The GC is synthesized with 1 nm Al2O3 catalyst, and the thickness can be controlled to 2 nm at a relatively low temperature 700 degrees C. With this unique GC layer coated PS, the structure integrity and solid electrolyte interphase stability substantially improved. As a result, the PS/GC shows a high capacity retention of 91% after 100 cycles at 0.2 A g(-1). During a long-life test at 1 A g(-1), the PS/GC electrode delivers 1024 mAh g(-1) after 600 cycles. In addition, an accumulated areal capacity of 492 mAh cm(-2) is achieved, further demonstrates the high mass loading of micrometer-sized PS as well as the electrochemical stability of highly-stacking GC coating layer. Our work invents a new approach of the GC growth and its application on large volume change electrode materials, which is enabled by a low temperature Al2O3 catalyzed method.