Formation of a Surficial Bifunctional Nanolayer on Nb₂O₅ for Ultrastable Electrodes for Lithium‐Ion Battery

Abstract

Safe and long cycle life electrode materials for lithium-ion batteries are significantly important to meet the increasing demands of rechargeable batteries. Niobium pentoxide (Nb O ) is one of the highly promising candidates for stable electrodes due to its safety and minimal volume expansion. Nevertheless, pulverization and low conductivity of Nb O have remained as inherent challenges for its practical use as viable electrodes. A highly facile method is proposed to improve the overall cycle retention of Nb O microparticles by ammonia (NH ) gas-driven nitridation. After nitridation, an ultrathin surficial layer (2 nm) is formed on the Nb O , acting as a bifunctional nanolayer that allows facile lithium (Li)-ion transport (10-100 times higher Li diffusivity compared with pristine Nb O microparticles) and further prevents the pulverization of Nb O . With the subsequent decoration of silver (Ag) nanoparticles (NPs), the low electric conductivity of nitridated Nb O is also significantly improved. Cycle retention is greatly improved for nitridated Nb O (96.7%) compared with Nb O (64.7%) for 500 cycles. Ag-decorated, nitridated Nb O microparticles and nitridated Nb O microparticles exhibit ultrastable cycling for 3000 cycles at high current density (3000 mA g ), which highlights the importance of the surficial nanolayer in improving overall electrochemical performances, in addition to conductive NPs.

T‐Nb2O5/C Nanofibers Prepared through Electrospinning with Prolonged Cycle Durability for High‐Rate Sodium–Ion Batteries Induced by Pseudocapacitance

“…X‐ray photoelectron spectroscopy (XPS) was performed to analyze the components and valence states of the samples. As shown in Figure c, two peaks around 206.9 and 209.7 eV are ascribed to Nb3d 3/2 and Nb3d 5/2 , respectively, which are in accordance with Nb 5+ in T‐Nb 2 O 5 …”

Niobium‐Based Oxides Toward Advanced Electrochemical Energy Storage: Recent Advances and Challenges

“…It exhibits high reversible capacities of 179.7 and 103.6 mA h g −1 at the current densities of 0.5 and 5 A g −1 , respectively. Ag nanoparticle coated nitridated Nb 2 O 5 electrode also shows high rate performances …”

“…Thus, exploring the practical energy storage applications of micrometer dimensional Nb 2 O 5 electrodes would be an interesting and significant topic. Typically, Kim et al have prepared some micrometer‐sized Nb 2 O 5 ‐based electrodes including pure Nb 2 O 5 , nitridated Nb 2 O 5 (N‐Nb 2 O 5 ), and Ag nanoparticles coated nitridated Nb 2 O 5 microparticles (Ag‐N‐Nb 2 O 5 ), then investigated their electrochemical performances ( Figure ) . It was found that Ag‐N‐Nb 2 O 5 exhibited high rate capacity (155, 108, 87 mA h g −1 at the current densities of 1, 3, 5 A g −1 , respectively) and excellent long‐cycle character (69 mA h g −1 after 3000 cycles at 3 A g −1 ) (Figure c,d).…”

“…d) Cycling performances of Ag–N–Nb 2 O 5 and N–Nb 2 O 5 at a high current density of 3 A g −1 . All panels reproduced with permission . Copyright 2017, Wiley‐VCH.…”

“…The large volume expansion would lead to the structural pulverization, fast capacity fading and serious safety hazards to the batteries. For intercalation‐type anodes, although most of them have the lower theoretical capacities, they show the smaller volume expansion (e.g., graphite ≈ 10%, TiO 2 ≈ 4%, Li 4 Ti 5 O 12 ≈ 0.3%, Nb 2 O 5 ≈ 5%) . As most of Nb‐based oxides anodes are intercalation‐type materials, thus, choosing the similar intercalation‐type anodes as the references for comparison can more objectively evaluate the electrochemical performances of niobium‐based oxides.…”