Pomegranate structured C@pSi/rGO composite as high performance anode materials of lithium-ion batteries

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A novel anode materials composed of pomegranate structured carbon @ porous silicon/reduced graphene oxide composite (C@pSi/rGO) was prepared by a facile high temperature pyrolysis and freeze drying technology. In this pomegranate-like composite, porous silicon is equivalent to pomegranate seeds providing sufficient specific capacity, the coated carbon layer is equivalent to pulp which can inhibit the volume expansion and improve electrical conductivity of silicon, and the outermost graphene is equivalent to the inner diaphragm and the outer fruit shell, which can accelerate the ion and electron transport and buffer the volume change of the inner silicon again, so that the cycling stability and rate performance of the material can be effectively improved. As a result, the initial discharge capacity of the C@pSi/rGO composite electrode is 825.7 mAh g−1, after 100 cycles, the reversible capacity of the C@pSi/rGO composite electrode can be maintained at 746 mAh g−1 at a current density of 0.4 A/g with a capacity retention up to 90.4%. However, for the pure porous silicon pSi electrode without carbon coating and graphene recombination, the initial discharge capacity is 769.4 mAh g−1 with almost 0% capacity retention after 30 cycles. Under the dual action of carbon coating and graphene composite, the performance of porous silicon electrode has been significantly improved, which will provide a new idea for the development of high performance silicon carbon anode materials.