Enhancing the electrochemical performance of Na metal anodes via local eutectic melting in porous Al-Cu alloy hosts

Sodium (Na) metal batteries (SMBs) have emerged as promising alternatives to lithium metal batteries for large-scale energy storage applications, owing to their cost-effectiveness, abundance, and favorable redox potential. However, the practical implementation of SMBs faces several challenges associated with the Na metal anode, including the formation of dendrites, low Coulombic efficiency, and capacity fading. Here, we propose a novel approach to enhance the electrochemical performance of Na metal anodes through a porous Al-Cu alloy host (PAC) fabricated by a local eutectic melting engineering. The local eutectic melting facilitates the development of a conductive network, offering mechanical support, and the porous structure provides abundant channels for the diffusion of Na ions and accommodates volume fluctuations in the Na metal during charge–discharge cycling. Moreover, the PAC exhibits a high average Coulombic efficiency of 99.8% at 1 mA·cm⁻² for 1 mAh·cm⁻² and a low voltage polarization of 19 mV during 500 cycles. This study provides valuable insight into the design and fabrication of high-performance Na metal anodes, which hold significant promise for the advancements of next-generation energy storage systems.