Simultaneous Encapsulation of Nano-Si in Redox Assembled rGO Film as Binder-Free Anode for Flexible/Bendable Lithium-Ion Batteries.

Abstract

The emerging ubiquitous flexible/wearable electronics are in high demand for compatible flexible/high-energy rechargeable batteries, which set a collaborative goal to promote the electrochemical performance and the mechanical strength of the fundamental flexible electrodes involved. Herein, freestanding flexible electrode of Si/graphene films is proposed, which is fabricated through a scalable, zinc-driven redox layer-by-layer assembly process. In the hybrid films, silicon nanoparticles are intimately encapsulated and confined in multilayered reduced graphene oxide (rGO) nanosheet films. The designed monolithic rGO/Si film possesses several structural benefits such as high mechanical integrity and three-dimensional conductive framework for accessible charge transport and Li+ diffusion upon cycling. When adopted as binder-free electrode in half-cells, the optimized hybrid rGO/Si film delivers high gravimetric capacity (981 mA h g-1 at 200 mA g-1 with respect to the total weight of the electrode) and exceptional cycling stability (0.057% decay per cycle over 1000 cycles at 1000 mA g-1). Besides, the binder-free rGO/Si film anode is further combined with a commercial LiCoO2 foil cathode for completely flexible full cell/battery, which exhibits excellent cycling performance and a high capacity retention of over 95% after 30 cycles under continuous bending. This solution-processable, elaborately engineered, and robust Si/graphene films will further harness the potential of silicon-carbon composites for advanced flexible/wearable energy storage.