Oxygen vacancy-expedited ion diffusivity in transition-metal oxides for high-performance lithium-ion batteries

Abstract

Rapid capacity decay and inferior kinetics are the vital issues of anodes in the conversion reaction for lithium-ion batteries. Vacancy engineering can efficiently modulate the intrinsic properties of transition-metal oxide (TMO)-based electrode materials, but the effect of oxygen vacancies on electrode performance remains unclear. Herein, abundant oxygen vacancies are in situ introduced into the lattice of different TMOs (e.g., Co 3 O 4 , Fe 2 O 3 , and NiO) via a facile hydrothermal treatment combined with calcination. Taking Co 3 O 4 as a typical example, results prove that the oxygen vacancies in Co 3 O 4−x effectively accelerate charge transfer at the interface and significantly increase electrical conductivity and pseudocapacitance contribution. The Li-ion diffusion coefficient of Co 3 O 4−x is remarkably improved by two orders of magnitude compared with that of Co 3 O 4 . Theoretical calculations reveal that Co 3 O 4−x has a lower Li-insertion energy barrier and more density of states around the Fermi level than Co 3 O 4 , which is favorable for ion and electron transport. Therefore, TMOs with rich vacancies exhibit superior cycling performance and enhanced rate capability over their counterparts. This strategy regulating the reaction kinetics would provide inspiration for designing other TMObased electrodes for energy applications.

Utilizing MOF precursors toward one-step, calcination-free synthesis of MnO2 superstructures for superior lithium storage

“…It can be seen that both the charge-transfer resistance ( R ct ) (reflected by the diameter of the middle-frequency arc) and Li + ion diffusion in solid ( Z w ) (reflected by the pitched line of the Z ′– Z ′′ curves at low frequency) are small during the cycling process, suggesting easy ion and electron transfer to the surface and interior of nanoscale active particles. Based on the EIS results, the lithium ion diffusion coefficient (D Li ) was further calculated to be 7.54 × 10 −10 cm 2 s −1 which was superior to that of many reported TMOs-based materials, 47–49 further illustrating the good Li + diffusion ability of the hierarchical superstructure (Fig. S10†).…”

Cluster-derived TiO2 nanocrystals with multiple carbon coupling for interfacial pseudo-capacitive lithium storage

“…71 It is notable that oxygen vacancies were absent in the samples, which is consistent with the results of Ti 2p XPS. 72 This is reasonable since the generation of Ti 3+ is usually accompanied by the formation of oxygen vacancies. Therefore, the capacity contribution from the Ti 3+ and oxygen vacancies can be precluded.…”

Cation-exchange and oxygen vacancies triggered capacity in hierarchical α-Ni1−xCuxMoO4@CC flexible electrodes for energy-storage applications

“…Thus, the noticed peak shift behavior in the Raman spectra could be a good indicator of the shifted diffraction planes at 2 θ degree positions in the XRD results, which further corroborates the described OVs and is in very good agreement with previous reports. 41,42 The electron paramagnetic resonance (EPR) technique is one of the better methods to shed light on the OV concept at different doping concentrations of Cu in α-NiMoO 4 @CC. As shown in Fig.…”