Scalable Preparation and Precise Control of Carbon Materials via Molten Salt Liquid Seal Strategy in Air

Revealing the relations between the physical and chemical properties of carbon materials with defined composition and structure is an important topic. However, traditional organic carbon precursor-derived carbon materials lack effective fine-tuning methods due to the uncontrollable temperature changes. Herein, a novel strategy termed a "molten salt liquid seal" is introduced to address this issue. Impressively, the uppermost KBr layer in the provided configuration effectively contains the release of carbon organic precursor at low temperatures and forms a protective barrier at high temperatures, thereby inhibiting the oxidation of carbon materials in air. Furthermore, we propose a corresponding "liquid seal" mechanism by monitoring the temperature-dependent morphological evolution of molten salts and carbon materials. Remarkably, the heteroatoms, defects, etc., in the carbon material can be precisely controlled within the range of 100 °C and 0.5 h per interval. Moreover, the carbonization yield is close to or even higher than that of the conventional process under an Ar atmosphere. We also validate the advantages of the resultant carbon materials as anodes in sodium-ion batteries. This innovative approach not only minimizes the reliance of inert atmospheres but also enables the high-yield fabrication of carbon materials in air, significantly advancing the field toward more sustainable practices.