Expanded graphite confined SnO2 as anode for lithium ion batteries with low average working potential and enhanced rate capability

To significantly improve the electrochemical performance of tin-based materials as anodes for lithium ion batteries, hybridizing tin-based nanomaterials with carbon is an effective way. This is due to carbon materials serving not only as conductive networks to increase the electrical conductivity, but also as construct void to buffer volume expansion. However, the use of excess carbon in hybrids and the low lithium storage ability of the carbon could lead to the reduced total capacity of the electrode. Herein, we develop a simple and effective approach to the synthesis of EG/SnO2-x in which SnO2 nanoparticles are tightly anchored on the surface of expanded graphite (EG) with well-defined expanded structures and highly conductive frameworks. Benefiting from the rational mass loading of SnO2, as well as the high conductivity and strong lithium storage characteristic of EG, the EG/SnO2-3 hybrid displays outstanding electrochemical performance with excellent rate capability (e.g., 406.3 mAh g–1 at 1 A g−1) and long cycling stability (e.g., 262.7 mAh g−1 over 500 cycles). In particular, the large proportion of capacity secured from a narrow voltage range of 0.01–0.3 V, corresponding to a low average working potential, is vital for the hybrids applied in high voltage full-cell LIBs.