Synthesis, characterization and application for lithium-ion rechargeable batteries of hollow silica nanospheres

Hollow silica nanospheres with uniform size of about 30 nm have been successfully synthesized using a template of ABC triblock copolymer micelles of poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) (PS-PVP-PEO) with a core-shell-corona architecture. In this type of triblock copolymers, the PS block (core) works as a template of the void space of hollow silica, the PVP block (shell) acts as a reaction field for the sol-gel reaction of tetramethoxysilane (TMOS), and the PEO block (corona) stabilizes the polymer/silica composite particles. Use of polymers with different chain lengths of PS, PVP, and PEO led to hollow silica with tunable cavity size and wall thickness. The obtained hollow particles were thoroughly characterized by X-ray diffraction (XRD), thermal (TG/DTA) and nitrogen sorption analyses, infra-red (FT IR) and nuclear magnetic resonance (Si-29 MAS NMR) spectroscopies, and transmission electron microscopy (TEM). The efficiency of hollow silica nanospheres for lithium-ion rechargeable batteries is demonstrated for the first time. The hollow silica nanoparticles exhibited high cycle performance of up to 500 cycles in the lithium rechargeable batteries through the alloying/dealloying process. The tiny grain size of hollow nanospheres results in less volume expansion and/or contraction during charge/discharge cycles.