A broad pore size distribution mesoporous SnO₂ as anode for lithium-ion batteries

Abstract

We demonstrate here that mesoporous tin dioxide (abbreviated M-SnO₂) with a broad pore size distribution can be a prospective anode in lithium-ion batteries. M-SnO₂ with pore size ranging between 2 and 7.5 nm was synthesized using a hydrothermal procedure involving two different surfactants of slightly different sizes, and characterized. The irreversible capacity loss that occurs during the first discharge and charge cycle is 890 mAh g⁻¹, which is smaller than the 1,010-mAh g⁻¹ loss recorded for mesoporous SnO₂ (abbreviated S-SnO₂) synthesized using a single surfactant. After 50 cycles, the discharge capacity of M-SnO₂ (504 mAh g⁻¹) is higher than that of S-SnO2 (401 mAh g⁻¹) and solid nanoparticles of SnO₂ (abbreviated nano-SnO₂ < 4 mAh g⁻¹) and nano-SnO₂. Transmission electron microscopy revealed higher disorder in the pore arrangement in M-SnO₂. This, in turn imparts lower stiffness to M-SnO₂ (elastic modulus, ER ≈ 14.5 GPa) vis-a-vis S-SnO₂ (ER ≈ 20.5 GPa), as obtained using the nanoindentation technique. Thus, the superior battery performance of M-SnO₂ is attributed to its intrinsic material mechanical property. The fluidity of the internal microstructure of M-SnO₂ resulted in a lower degree of aggregation of Sn particles compared to S-SnO₂ and nano-SnO₂ structural stabilization and long-term cyclability.