Sn- and SnO2-Graphene Flexible Foams Suitable as Binder- Free Anodes for Lithium Ion Batteries

With the objective of developing new advanced composite materials that can be used as anodes for lithium ion batteries (LIBs), herein we describe the synthesis of a novel three dimensional (3D) macroporous foams formed by reduced graphene oxide (rGO) and submicron tin-based particles. The aerogels were obtained by freeze/freeze-drying a suspension of graphene oxide (GO) in the presence of a tin precursor and its subsequent thermal reduction under argon atmosphere. The materials exhibited a 3D-macroporous structure formed by walls of rGO decorated with Sn or SnO2 particles depending on the temperature of calcination. Self-standing compressed foams were directly assembled into coin cells without using any metallic support to be evaluated as binder-free anodes for LIBs. The homogeneous dispersion and intimate contact between the Sn-based particles and graphene walls were confirmed by scanning electron microscopy (SEM). The performance of SnO2-rGO composites materials as anode for LIBs showed larger specific capacity compared with the rGO and metallic Sn-containing samples, reaching in the former case a reversible capacity of 1010 mAh g of electrode at 0.05 A g and good capacity retention (470 mAh g) even at 2 A g (~ 2C), among the highest reported for similar systems. SEM images of selected electrodes after 50 charge-discharge cycles Page 1 of 21 Journal of Materials Chemistry A Jo ur na lo fM at er ia ls C he m is tr y A A cc ep te d M an us cr ip t