Cation‐Vacancy Ordered Superstructure Enhanced Cycling Stability in Tungsten Bronze Anode

Abstract

Niobium‐based tungsten bronze oxides have recently emerged as attractive fast‐charging anodes for lithium‐ion batteries (LIBs), owing to their structural openings and adjustability. However, electrodes with tungsten bronze structures usually suffer from structural variability induced by Li+ intercalation/de‐intercalation, leading to unsatisfactory cycling performance. To circumvent this limitation, a novel tetragonal tungsten bronze (TTB) structure, Ba3.4Nb10O28.4 (BNO), is developed as an anode material for LIBs with prominent cycling performance. An unprecedented cation‐vacancy ordered superstructure with a periodic distribution of active and inactive sites is revealed inside the BNO. Through multiple characterizations and theoretical studies, it is demonstrated that this superstructure can improve the lithium‐ion diffusion and disperse the structural strain induced by Li+‐intercalation to enable stable Li+‐storage. Benefiting from the superstructure‐induced local structural stability, both the BNO bulk and Ba3.4Nb10O28.4@C (BNO@C) microspheres can deliver >90% capacity retention after 250 cycles at 2 C and close to 90% capacity retention after 2000 cycles at 10 C. These results are of significant importance for establishing the structure–property relationship between the cation‐vacancy ordered superstructure and Li+‐storage performance, facilitating the rational design of stable tungsten bronze anodes.

Novel Nonstoichiometric Niobium Oxide Anode Material with Rich Oxygen Vacancies for Advanced Lithium-Ion Capacitors

“…In terms of data analysis, k 1 and k 2 were calculated from a linear plot of i/ν 1/2 versus ν 1/2 . 39 As illustrated in Figure S9c,f (Supporting Information), P-Nb 12 O 29 and Nb 12 O 29−x @C electrodes exhibited predominantly capacitive contribution of up to 69.2 and 70.2% at 1.0 mV s −1 , respectively, indicating that Li + storage behavior in P-Nb 12 O 29 and Nb 12 O 29−x @C is dominantly controlled by the capacitive process and implying the excellent rate properties. Moreover, as demonstrated in Figure S10 (Supporting Information), the capacitive contribu-tion at 0.1, 0.2, 0.4, and 0.8 mV s −1 for Nb 12 O 29 and Nb 12 O 29−x @C further indicate the intercalation pseudocapacitance mechanism.…”

“…In terms of data analysis, k 1 and k 2 were calculated from a linear plot of i/ν 1/2 versus ν 1/2 . 39 As illustrated in Figure S9c,f (Supporting Information), P-Nb To evaluate the electrochemical performance of the prepared materials, CR2016 coin-type half-cells were fabricated. Lithium foil and 1.0 M LiPF 6 in ethylene carbonate/ dimethyl carbonate/ethyl methyl carbonate (EC/DMC/EMC, 1:1:1 by volume) with 5% fluoroethylene carbonate (FEC) were used as the counter/reference electrode and electrolyte, respectively.…”

“…The capacitive storage contribution could be further quantitatively calculated according to the following equation: i (V) = k 1 ν + k 2 ν 1/2 , where k 1 and k 2 are parameters at a given potential. In terms of data analysis, k 1 and k 2 were calculated from a linear plot of i /ν 1/2 versus ν 1/2 . As illustrated in Figure S9c,f (Supporting Information), P-Nb 12 O 29 and Nb 12 O 29– x @C electrodes exhibited predominantly capacitive contribution of up to 69.2 and 70.2% at 1.0 mV s –1 , respectively, indicating that Li + storage behavior in P-Nb 12 O 29 and Nb 12 O 29– x @C is dominantly controlled by the capacitive process and implying the excellent rate properties.…”

Gradient Graphdiyne Induced Copper and Oxygen Vacancies in Cu0.95V2O5 Anodes for Fast‐Charging Lithium‐Ion Batteries

“…Besides the oxygen vacancies, cation vacancies also remove kinetic limitations and provide thermodynamically favorable driving forces for additional cation insertion. [6] Recently, targeted generation of cation vacancies in electrode materials has been investigated. For example, CoSe 2 rich in Co vacancies was obtained via solvent intercalation for sodium-ion (Na-ion) batteries, and the enhanced storage of Na ions was mainly attributed to the pseudocapacitance induced by Co vacancies.…”

“…Based on these strategies, the oxygen vacancies are successfully introduced into the MOs such as niobium‐titanium oxide, [3] perovskite oxides [4] and MoO 3 [5] to significantly improve the lithium‐ion (Li‐ion) diffusion coefficient and electrochemical conversion reaction kinetics of the electrode. Besides the oxygen vacancies, cation vacancies also remove kinetic limitations and provide thermodynamically favorable driving forces for additional cation insertion [6] . Recently, targeted generation of cation vacancies in electrode materials has been investigated.…”