Mesoporous carbon hollow spheres with controllable pore structure for efficient lithium and aluminum ion storage

Abstract

Mesoporous carbon hollow nanospheres (MCHS), synthesized via a block copolymer-mediated supramolecular self-assembly process, serve as both anode materials for lithium-ion batteries (LIBs) and cathode materials for aluminum-ion batteries (AIBs). By adjusting the carbonization temperature and the dosage of the pore extender, 1,3,5-trimethylbenzene (TMB), insights into the relationships among pore structure, crystal structure, and electrochemical properties of MCHS in Li/Al-ion batteries are gained. Their exceptional properties, including hierarchically porous structure, large surface area, tailored inner voids, mesoporous shells, and high electronic conductivity, contribute to high specific capacity, improved rate performances, and remarkable electrochemical stability. Crystallographic insights reveal that highly porous MCHS facilitate the intercalation of ionic lithium and aluminum species into the carbon crystal lattices while maintaining structural integrity. The appropriate mesopore size significantly impacts the storage of lithium or aluminum ions, with relatively larger mesopore sizes being more beneficial for aluminum ion storage compared to lithium ions. The optimal MCHS exhibit a stable discharge specific capacity of 330.8 mAh·g−1 after 800 cycles at a current density of 372 mA·g−1 (1C) in LIBs and 41.6 mAh·g−1 after 500 cycles at 74.4 mA·g−1 in AIBs.