Rational Construction of a Binder-Free and Universal Electrode for Stable and Fast Alkali-ion Storage

Na-ion batteries (SIBs) and K-ion batteries (PIBs) are considered as promising alternatives to Li -ion batteries (LIBs) for large-scale electrical -energy-storage applications. Thus, developing an advanced anodic material with appropriate structure for both SIBs and PIBs is urgently desirable but remains an eager challenge because of the relatively large ionic radius of Na+ or K. Herein, we rationally design a sulfur-mediated threedimensional graphene aerogel (SMGA) with plant cell wall structure as a binder-free anodic material for SIBs and PIBs as well as LIBs, exhibiting high capacity and excellent rate capability along with long cycling stability. For instance, at 0.1 A the SMGA anodes can deliver a high capacity of 320 mAh g' in PIBs after 500 cycles and 304 mAh CI in SIBs and 690 mAh g-1 in LIBs after 200 cycles. Furthermore, a detailed electrochemical kinetic calculation manifests that the Li/Na/K-ion storage capability is mainly ascribed to the introduction of sulfur in graphene aerogel (GA) to enlarge the interlayer distance, the three-dimensional interconnected network with porous structure providing sufficient space to accommodate volumetric expansion, and a short transport pathway for electrons/alkali-ions. Our results demonstrate the advanced performance of alkali -ion batteries, thus making it possible to develop a universal electrode for applications of cost-effective next-generation rechargeable batteries.