Rapid and reversible Na deposition onto Al nanosheet arrays

Sodium metal battery (SMB) is regarded as a promising candidate for next-generation high-energy battery due to high theoretical capacity and abundant natural resources. However, the growth of sodium dendrites and large volume expansion during the processes of sodium plating and stripping seriously restrict the practical application of SMBs. Here, a three-dimensional skeleton of aluminum nanosheet arrays (Al NSARs) is constructed by a facile etching approach to achieve rapid and reversible Na plating/stripping. The Al NSARs with large geometric specific surface and plentiful cavities can provide rich active nucleation sites, reduce local current density and accommodate Na volume change, which lead to uniform deposition of sodium with dendrite-free morphology. As a result, Na plating/stripping on Al NSARs can stably operate over 650 cycles at 2 mA cm −2 /2 mAh cm −2 with average Coulombic efficiency (CE) of 100.0% and low potential polarization of 27 mV. Moreover, the full cell of Na 3 V 2 (PO 4 ) 3 ‖Al NSARs@Na can run for over 1800 cycles at a high rate of 20C. These superior properties, combined with relatively low cost and weight of Al, enable our Al NSARs to be great prospect for practical applications.