Integration of homogeneous and heterogeneous nucleation growth via 3D alloy framework for stable Na/K metal anode

Sodium/Potassium (Na/K) metal anodes have been considered as the promising anodes for next-generation Na/K secondary batteries owing to their ultrahigh specific capacity, low redox potential and low cost. However, their practical application is still hampered due to unstable solid electrolyte interphase, infinite volume change, and dendrite growth. Herein, we design a 3D-Na3Bi/3D-K3Bi alloy host which enables the homogeneous and heterogeneous nucleation growth of Na/K metal. The unique structure with periodic alternating of electron and ion conductivity improves the mass transfer kinetics and prevents the volume expansion during cycling. Meanwhile, the sodiophilicity of Na3Bi/potassiophilicity of K3Bi framework can avoid dendritic growth. Cycling lifespans over 700 h with 1 mAh cm-2 for 3D-Na3Bi@Na electrode and about 450 h with 1 mAh cm-2 for 3D-K3Bi@K electrode are achieved, respectively. 3D-Na3Bi@Na||Na3V2(PO4)3 full battery shows sustainable cycle performance over 400 cycles. This design provides a simple but effective approach for achieving safety of sodium/potassium metal anodes.

Automated summary

In this study, a 3D-Na3Bi/3D-K3Bi alloy host is designed to promote the homogeneous and heterogeneous nucleation growth of sodium/potassium metal anodes. This design effectively prevents dendrite growth and improves cycle performance by addressing volume expansion issues during cycling. The experimental results demonstrate promising cycling lifespans and sustainable cycle performance for sodium/potassium metal anodes.