CoSn(OH)6 hybridized with anionic and cationic graphenes as a new high-capacity anode for lithium ion batteries

Abstract Herein is the first use of a CoSn(OH) 6 /graphene composites as a high-performance anode in lithium ion batteries (LIBs). CoSn(OH) 6 alone is found to be electrochemically active and to possess electrochemical properties that are superior to those displayed in its dehydrated form (CoSnO 3 ). In contrast to the formation of 3Li 2 O in CoSnO 3 during the first discharge (CoSnO 3  + 6Li +  + 6e −  → Co + Sn + 3Li 2 O), the production of 6 mol of LiOH in CoSn(OH) 6 (CoSn(OH) 6  + 6Li +  + 6e −  → Co + Sn + 6LiOH) seems to provide nanometric Co/Sn particles with more efficient reversibility for the subsequent Li + -insertion/de-insertion via conversion/alloy reactions. The electrochemical performance of CoSn(OH) 6 is further improved when composited with graphenes. This is accomplished by electrostatically combining negatively charged Co 2 + /Sn 2 + -anchored graphene oxide (GO) with positively charged amine-functionalized graphene (GN) in a solution. The subsequent hydrothermal reaction produces CoSn(OH) 6 nanocubes that are tightly held by graphene sheets (GO/CS/GN). The GO/CS/GN delivers unprecedentedly high capacity and excellent cyclability (discharge capacities of 1475 mAh·g − 1 for the 100th charge/discharge (C/D) cycles at a 0.1 A·g − 1 ). In contrast to the comparison materials (CoSnO 3 /graphene composites) the rate performance is also remarkable, delivering a capacity of 650 mAh·g − 1 at 2.0 A·g − 1 .