Construction of an Anode Material for Sodium-Ion Batteries with an Ultrastable Structure

The reserves of sodium resources are much larger than those of lithium resources, and they are widely distributed and easy to produce and can be widely used in photovoltaic energy storage and other industries on the premise of this advantage. However, how to produce hard carbon anodes at a low cost for the preparation of energy storage materials requires continuous exploration and experimentation to find the optimal solution. Here, we used waste sour date shell biomass as a precursor for a hard carbon anode obtained by simple acid treatment and two pyrolyses. It is shown that acid washing after prepyrolysis has a significant effect on the electrochemical performance of the sour date shell-derived hard carbon (ZJ), constructing a stable structure that makes it easier for sodium ions to be embedded and dislodged, and the carbon particles are homogeneous and free of bonding and electrode cracking. The ZJ-1500-HCl pyrolyzed at 1500 °C has a high reversible capacity of 329.1 mAh g^–1, 94.1% initial Coulombic efficiency (ICE), 90.54% capacity retention efficiency cycling 300 cycles at a current density of 300 mA g^–1, and a resistivity below 10 Ω. It has good cycle stability and a good multiplier performance. It is expected to be used in practical production and photovoltaic energy storage in the future.