Carbide-Derived Niobium Pentoxide with Enhanced Charge Storage Capacity for Use as a Lithium-Ion Battery Electrode

Abstract

Nb 2 O 5 has been explored as a promising anode material for use as lithium-ion batteries (LIBs), but depending on the crystal structure, the specific capacity was always reported to be usually around or below 200 mAh/g. For the first time, we present coarse-grained Nb 2 O 5 materials that significantly overcome this capacity limitation with the promise of enabling high power applications. Our work introduces coarse-grained carbidederived Nb 2 O 5 phases obtained either by a one-step or a two-step bulk conversion process. By in situ production of chlorine gas from metal chloride salt at ambient pressure, we obtain in just one step directly orthorhombic Nb 2 O 5 alongside carbide-derived carbon (o-Nb 2 O 5 /CDC). In situ formation of chlorine gas from metal chloride salt under vacuum conditions yields CDC covering the remaining carbide core, which can be transformed into metal oxides covered by a carbon shell upon thermal treatment in CO 2 gas. The two-step process yielded a mixed-phase tetragonal and monoclinic Nb 2 O 5 with CDC (m-Nb 2 O 5 /CDC). Our combined diffraction and spectroscopic data confirm that carbide-derived Nb 2 O 5 materials show disordering of the crystallographic planes caused by oxygen deficiency in the structural units and, in the case of m-Nb 2 O 5 /CDC, severe stacking faults. This defect engineering allows access to a very high specific capacity exceeding the two-electron transfer process of conventional Nb 2 O 5 . The charge storage capacities of the resulting m-Nb 2 O 5 /CDC and o-Nb 2 O 5 /CDC are, in both cases, around 300 mAh/g at a specific current of 10 mA/g, thereby, the values are significantly higher than that of the state-of-the-art for Nb 2 O 5 as a LIB anode. Carbide-derived Nb 2 O 5 materials also show robust cycling stability over 500 cycles with capacity fading only 24% for the sample m-Nb 2 O 5 /CDC and 28% for o-Nb 2 O 5 /CDC, suggesting low degree of expansion/compaction during lithiation and delithiation.

Titanium Niobium Oxide Ti2Nb10O29/Carbon Hybrid Electrodes Derived by Mechanochemically Synthesized Carbide for High‐Performance Lithium‐Ion Batteries

“…The incomplete oxidation of carbides allows for the controlled design of metal oxide/carbon hybrids [7c,13] and the adjustment of crystal structure defects (oxygen vacancies). [14] To the best of our knowledge, our present work is the first to demonstrate a mixed metal oxide derived from a mixed metal carbide for battery applications. As a feature of the carbide-derived oxide synthesis, it is possible to adjust the titanium-to-niobium molar ratio of the carbide to a value of 1 : 5 so that the resulting mixed metal oxide phase would be Ti 2 Nb 10 O 29 .…”

“…The process involves first a mechanically induced self‐sustaining reaction (MSR) to obtain titanium niobium carbide (TNC) and a thermal annealing step to convert the material to TNO. The incomplete oxidation of carbides allows for the controlled design of metal oxide/carbon hybrids [7c,13] and the adjustment of crystal structure defects (oxygen vacancies) [14] . To the best of our knowledge, our present work is the first to demonstrate a mixed metal oxide derived from a mixed metal carbide for battery applications.…”

Nanoscale Phase Engineering in Two-Dimensional Niobium Pentoxide Anodes toward Excellent Electrochemical Lithium Storage

“…The Nb 2 O 5 -550 electrode exhibits a wide redox peak in the second and third cycles. For the other electrodes obtained at a higher calcinated temperature, the redox peaks gradually split, indicating that the surface-confined redox reactions are decreased, while the diffusion control processes dominate . In addition, there is an inconspicuous lithium extraction shoulder peak at about 1.86 V in the Nb 2 O 5 -750 electrode.…”

“…For the other electrodes obtained at a higher calcinated temperature, the redox peaks gradually split, indicating that the surface-confined redox reactions are decreased, while the diffusion control processes dominate. 58 In addition, there is an inconspicuous lithium extraction shoulder peak at about 1.86 V in the Nb 2 O 5 -750 electrode. It can be related to the reduction of the T-phase and the formation of a small amount of Hphase.…”

Inducing Conductive Surface Layer on Nb2O5 via Ar-ion Bombardment: Enhanced Electrochemical Performance for Li-ion Batteries

“…[12][13][14] To overcome the drawback, considerable efforts have been devoted to investigating fabrication techniques such as building special morphology, introducing conductive carbon networks, doping foreign elements for adequate utilization, and nanoarchitecture current collector (see Table S1 † for representative modification of the reported Nb2O5-based materials). [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] Although materials with utilization of these methods show certain enhancement, the compatibility with the ongoing manufacturing line remains challenging to meet the requirement of practical utilization of as mentioned methods. Simple experimental design is still highly desirable to circumvent the multistep or complicated synthesis routes.…”