Constructing sodiophilic interconnected ion-transport channels towards a stable Na-metal anode

Abstract

Electrochemical cells utilizing metals (e.g., Li, Na, K) as anodes have sparked significant interest in both academia and industry. However, the rapid growth of sodium dendrites and irregular deformation are limiting the usage of sodium metal anodes. Fast ion transport is crucial for metal deposition and stripping. Herein, we fabricated a hybrid metal anode by physically mixing superionic conductor Na₃V₂(PO₄)₃ particles with sodium metal using a facile and scalable rolling and folding method. The superionic conductor particles with high affinity for Na⁺ are beneficial for charged Na-ion channels formation. These channels serve as reservoirs to continuously release and deliver sodium ions, compensating for the ionic flux of the electrolyte. Moreover, the interconnected Na⁺-conducting channels also reduce the diffusion barrier and accelerate Na⁺ migration, thereby homogenizing the local Na-ion flux and steering uniform Na deposition. These characteristics collectively contribute to dendrite-free Na electrodeposition and long cycle life (over 1000 h for 2 mA h cm⁻² at 0.5 mA cm⁻²) in symmetric cells. Remarkably, when paired with Na₃V₂(PO₄)₃ cathodes, the full cell achieves high capacity retention (87.8% after 1000 cycles at a current density of 5C) and excellent rate performance (57.3 mA h g⁻¹ at 50C).