Sandwiched graphene inserted with graphene-encapsulated yolk–shell γ-Fe2O3 nanoparticles for efficient lithium ion storage
A convenient and scalable in situ chemical vapor deposition (CVD) method is developed for one-step fabrication of sandwiched graphene sheets which were filled with yolk–shell γ-Fe2O3 nanoparticles encapsulated with graphene shells (YS-γ-Fe2O3@G-GS). Such a unique architecture can be applied to produce an excellent lithium ion battery (LIB) anode. As a result, long-term cycling stability at high rates (a high capacity of 663.7 mA h g−1 is achieved at 2 A g−1 and maintained at approximately 96.6% even after 1500 cycles) and superior rate capability (1173 mA h g−1 at 0.1C, 989 mA h g−1 at 0.2C, 827 mA h g−1 at 0.5C, 737 mA h g−1 at 1C, 574 mA h g−1 at 2C, 443 mA h g−1 at 5C, and 350 mA h g−1 at 10C; 1C = 1 A g−1) can be obtained when YS-γ-Fe2O3@G-GS is used as an LIB anode. As far as we know, this is the best rate capacity and longest cycle life ever reported for an Fe2O3-based LIB anode.