Alloying-triggered heterogeneous nucleation for the flexible sodium metallic batteries

The uncontrolled dendritic growth, infinite volume propagation and unstable interfacial electrochemistry remain the major bottlenecks to deploy the high-capacity metallic anodes. Further reconciling of the mechanical instable metal electrodeposits upon the geometric deformation in the light-weight, flexible and compactly packed battery model is even more challenging. Here, the Sn₄P₃ nanocrystallines were anchored within the interconnected reduced graphene oxide film (Sn₄P₃@rGO) to induce the heterogeneous Na-Sn and Na-P intermediates as the highly sodiophilic “magnets”. Both the galvanostatic cycling and first-principles calculations reveal the apparently reduced nucleation barriers of the Na plating process in the Sn₄P₃@rGO symmetric cells. Moreover, the device integration of the NaVPO₄F cathode and the Sn₄P₃@rGO substrate with the tailored pre-stored Na (1* excess) realizes 95.6% capacity retention for 150 cycles in a 1.1 mA h full cell. The empirical parameters beyond the prism of the electrode capacity that determine the overall cycle behavior are elucidated, presenting a horizon for architecture designs from both the component level and device level.