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

Abstract

Functional materials with high energy density – high rate capabilities have continued to gain importance, and are extensively studied for next-generation energy storage applications.[1] The ongoing challenge is to elevate the power density of batteries on par with capacitors, while holding the energy density and cycle life.[2] The sluggish intercalation kinetics, and continuous transition metal dissolution in conventional electrodes hampers the realization of high power, and highly stable devices.[3] 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.