Significantly improved high-rate Li-ion batteries anode by encapsulating tin dioxide nanocrystals into mesotunnels

Abstract

Novel nanostructures, e.g. core–shell or yolk–shell, sword–sheath, coaxial nanotubes, etc., are extensively explored for their potential application in modifying electrode durability in lithium-ion batteries (LIBs). Herein, hybrid nanostructures of monodisperse tin dioxide nanocrystals inclusion in highly ordered mesotunnels of mesoporous carbon (CMK-3) are hydrothermally synthesized. Benefiting from ultrafine nanocrystals of mainly 2 nm or so and their good distribution throughout the highly ordered tunnels and the outer surface of the CMK-3, the hybrid shows a strongly coupled synergistic effect. When used as anode materials for LIBs, the hybrid composite exhibits excellent cycling and rate performance superior to both components involved with high reversible capacity retention above 95% for 200 cycles and recoverable initial reversible capacity at large rates of 10 A g⁻¹. Insights into the electrochemical process reveal the total capacity is contributed by two different factors: redox capacitance and interfacial capacitance. Once solid electrolyte interfaces (SEIs) are formed, the hybrid composite exhibits stable interfaces and robust structures indicated by the enhanced interfacial capacitance.