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

Publication date: 15 March 2017
Source:Materials & Design, Volume 118
Author(s): S.J. Richard Prabakar, Su Cheol Han, Jaehyang Jeong, Kee-Sun Sohn, Myoungho Pyo
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 (CoSnO3). In contrast to the formation of 3Li2O in CoSnO3 during the first discharge (CoSnO3+6Li⁺+6e⁻→Co+Sn+3Li2O), the production of 6mol 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 Co²⁺/Sn²⁺-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 1475mAh·g⁻¹ for the 100th charge/discharge (C/D) cycles at a 0.1A·g⁻¹). In contrast to the comparison materials (CoSnO3/graphene composites) the rate performance is also remarkable, delivering a capacity of 650mAh·g⁻¹ at 2.0A·g⁻¹.

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