Anode-Free Sodium Metal Pouch Cell Using Cu 3 p Nanowires In-Situ Grown on Current Collector.

Anode-free sodium metal battery (AFSMB) promises a high energy density, but suffers from the difficulty of maintaining high cycling stability. Nonuniform sodium (Na) deposition on current collector is largely responsible for capacity decay in the cycling process of AFSMB. Here, a unique Cu 3 P nanowires was constructed on copper (Cu 3 P@Cu) as sodium deposition substrate by an in-situ growth method. Superior electrochemical performance of Cu 3 P@Cu anode was delivered in asymmetric cells with an average Coulombic efficiency of 99.8% for over 800 cycles at 1 mA cm -2 with 1 Am h cm -2 . Symmetric cell of Cu 3 P@Cu displayed a cycling lifespan of over 2000 h at 2 mA cm -2 with 1 Am h cm -2 . Cryo-TEM characterization and first principles calculation revealed that the low Na + absorption energy and low Na + diffusion energy barrier on Na 3 P promoted the uniform Na nucleation and deposition, thus enhancing the Na surface stability. Moreover, anode-free Na 3 V 2 (PO 4 ) 3 //Cu 3 P@Cu full pouch cell delivered a considerable cycling capacity of ∼15 mA h in 170 cycles, demonstrating its practical feasibility. This article is protected by copyright. All rights reserved.