A core@double-shell structured silicon/flower-like manganese selenide/carbon composite as superior dual anode materials of Li/Na-ion batteries

One of the feasible solutions for enhancing new energy density of secondary batteries is to develop high-performance dual anode materials for lithium and sodium-ion batteries (LIBs&SIBs). To address this key challenge, we introduce a novel silicon/flower-like manganese selenide/carbon composite (Si@MnSe@PPyC/rGO) with core@double-shell structure as potential dual anode materials. The morphology, structure and composition of the composite are determined by means of SEM, TEM, EDS, XRD, Raman, TGA and XPS. The key to the successful synthesis process is that in situ polymerization of polypyrrole on the nanosheet of flower-like Si@MnO2 preserves the intermediate layer with flower-like morphology during selenization. Si@MnSe@PPyC/rGO exhibits the high performance owing to exceptional advantages such as the high capacity silicon core, the stable flower-shaped MnSe and PPyC double shells as protective layer, as well as the excellent conductive network of rGO. This material delivers a greatly enhanced reversible capacity (803 mAh/g at 0.1 A/g), remarkable stability and excellent rate performance (437 mAh/g even at 3.2 A/g) in LIBs. For Na-ion storage, it pleasantly reaches 323 mAh/g at 0.2 A/g and remains constant at 226.4 mAh/g after 500 cycles at 2.0 A/g. This study provides versatile strategy so as to maintain the unique morphology of nano-metal oxide during selenization treatment, and supplies a cost-effective strategy for preparing high-performance dual-anode materials for Li/Na-ion storage. Novelty Statement Novel silicon/flower-like manganese selenide/carbon composites (Si@MnSe@PPyC/rGO) with core@double-shell structure are successfully fabricated as superior dual anode materials for Li/Na-ion storage for the first time. The critical step is the in-situ coating of PPy on the surface of nanosheets of Si@flower-like MnO2 which could remain the original flower-like morphology unchanged during selenization treatment. Si@MnSe@PPyC/rGO exhibits excellent potential as a dual anode material candidate for high performance Li/Na-ion storage including high capacity, stable cycling performance and high rate capability.