Solvothermal-Induced 3D Macroscopic SnO₂/Nitrogen-Doped Graphene Aerogels for High Capacity and Long-Life Lithium Storage

3D macroscopic tin oxide/nitrogen-doped graphene frameworks (SnO₂/GN) were constructed by a novel solvothermal-induced self-assembly process, using SnO₂ colloid as precursor (crystal size of 3–7 nm). Solvothermal treatment played a key role as N,N-dimethylmethanamide (DMF) acted both as reducing reagent and nitrogen source, requiring no additional nitrogen-containing precursors or post-treatment. The SnO₂/GN exhibited a 3D hierarchical porous architecture with a large surface area (336 m²g^‑1), which not only effectively prevented the agglomeration of SnO₂ but also facilitated fast ion and electron transport through 3D pathways. As a result, the optimized electrode with GN content of 44.23% exhibited superior rate capability (1126, 855, and 614 mAh g^‑1 at 1000, 3000, and 6000 mA g^‑1, respectively) and extraordinary prolonged cycling stability at high current densities (905 mAh g^‑1 after 1000 cycles at 2000 mA g^‑1). Electrochemical impedance spectroscopy (EIS) and morphological study demonstrated the enhanced electrochemical reactivity and good structural stability of the electrode.