Mechanical simulation informed rational design of a soft-and-hard double-jacketed SnO2 flexible electrode for high performance lithium-ion battery

Graphene-based tin dioxide (SnO2) composite electrode is emerging as an attractive anode candidate for high-performance flexible lithium-ion batteries due to its excellent electronic conductivity, high theoretical capacity, and mechanical durability. However, the understanding of the underlying mechanism that how graphene contributes to the mechanical integrity and good electrochemical performances of flexible SnO2 composite electrodes remains superficial. To this end, mechanical simulations aiming at directing the electrode structural design are highly desired. In this work, we reported a first-of-its-kind mechanical simulation on lithium intercalation induced stress in pristine SnO2 anode and surface-modified SnO2 composite anodes “wearing” soft (graphene)/hard (amorphous carbon) jacket. The simulation results quantitatively revealed that the double coatings are far more effective in reducing the charging-induced stresses and avoiding mechanical failure than pristine SnO2 and amorphous carbon single protection. Based on this, a unique soft-and-hard double-jacketed flexible SnO2 composite electrode with core-shelled [email protected]2 embedded in graphene nanosheets was fabricated. In line with the mechanical simulations, the confinement of graphene encapsulation suppresses the crack formation, enhancing the mechanical integrity and the cyclic stability of the composite SnO2 anodes. As expected, the obtained flexible anode shows high specific capacity (836 mAh•g−1 at 100 mAg−1), excellent rate capability (506 mAh•g−1 at 2 Ag−1) and ultra-stable cycling stability.