Rationally Designed 3D Graphene Hollow Spheres Towards Building High Energy - High Power Energy Storage System with Long Durability

摘要

Functional materials with high energy density - high rate capabilities have continued to gain importance, and are extensively studied for next-generation energy storage applications. The ongoing challenge is to elevate the power density of batteries on par with capacitors, while holding the energy density and cycle life. The sluggish intercalation kinetics, and continuous transition metal dissolution in conventional electrodes hampers the realization of high power, and highly stable devices. To overcome the kinetic issues, we rationally designed graphene hollow nanospheres (GHNS) with dual heteroatoms (nitrogen and sulfur) as both anode and cathode for Na-ion based energy storage system. The self-assembly of 2D graphene into a highly connected 3D architecture facilitates facile Na-ion storage, while the nitrogen and sulfur hetero atoms infiltrated in the carbonaceous matrix elevates the kinetics of the GHNS. The full-cell based on GHNS electrodes displays a high operating voltage, high energy density (121 Wh kg~(-1) at 100 W kg~(-1)), and high power density (51 kW kg~(-1)). Further, the sodium-ion storage system can render remarkable cycling stability of ～85% retention after 10,000 cycles (～0.0015% decay per cycle). Development of such nanostructured functional materials could establish a trade-off relationship between high energy and high power devices.