Precisely Tunable T-Nb2O5 Nanotubes via Atomic Layer Deposition for Fast-Charging Lithium-Ion Batteries

The demand for fast-charging of lithium-ion batteries (LIBs) in modern electric transportation and wearable electronics is rapidly growing. However, commercially available graphite anodes still suffer from slow kinetics of lithium-ion diffusion and severe safety concerns of lithium plating when achieving the fast-charging goal. Here, it is demonstrated that the Li-ion diffusion kinetics of orthorhombic Nb 2 O 5 nanotubes (T-Nb 2 O 5 NTs) is enhanced by atomically precise manufacturing of nanoarchitectures. The controlled fabrication of T-Nb 2 O 5 NTs with wall thicknesses from 24 to 43 nm is realized via atomic layer deposition (ALD) using electrospun polyacrylonitrile nanofibers as a sacrificing template. The wall thickness of T-Nb 2 O 5 NTs can be precisely tuned by adjusting the number of ALD cycles. The relationship between the wall thicknesses and electrochemical performances is investigated in detail. The electrochemical kinetic analysis suggests that the lithium storage in T-Nb 2 O 5 NTs is dominated by surface and intercalation pseudocapacitance. The morphology of T-Nb 2 O 5 crystallites is found to have significant effects on the Li-ion insertion/extraction kinetics and the performance of the electrodes in LIBs. The resulting T-Nb 2 O 5 NTs exhibit fast charge-storage kinetics and enable highly reversible insertion/extraction of Li ions without a phase change. This work may open up a new avenue for further development of intercalation-pseudocapacitive nanostructured materials for high-rate and ultrastable energy-storage devices.