Gentle self-assembled freeze–thaw synthesis of graphene/SnO2 composite aerogel for sodium-ion battery anodes

We report a novel mild self-assembly freeze–thaw strategy for fabricating 3D graphene aerogel (GA) composite anchored with SnO 2 nanoparticles. Compared with conventional hydrothermal and freeze-drying methods, The method achieves energy-efficient synthesis (90 °C, 3 h) and eliminates complex equipment. Efficient dispersion of SnO 2 nanoparticles and precise modulation of the 3D porous structure were achieved through the synergistic effects of self-assembly, foaming, and in-situ reduction at low temperature and atmospheric pressure. The unique structure of GA/SnO 2 composites significantly buffers the volume expansion of SnO 2 and enhances the ion/electron transport kinetics. As a sodium-ion battery anode, it provides a high reversible capacity of 302.5 mAh g −1 after 300 cycles at 0.1 A g −1 and a remarkable rate capability (146 mAh g −1 at 2 A g −1 ), outperforming aggregated SnO 2 synthesized via hydrothermal routes. DFT simulations reveal enhanced sodium-ion adsorption energy and interfacial C Sn O covalent bonding, which synergistically stabilize the electrode structure. This work provides a low-cost and environmentally friendly route for designing high-performance metal oxide/carbon composites.