Oxygen vacancies can promote Li-ion diffusion, reduce the charge transfer resistance, and improve the capacity and rate performance of Li-ion batteries. However, oxygen vacancies can also lead to accelerated degradation of the cathode material structure, and lead to phase transition etc.
High capacity Li2MnSiO4/C nanocomposite with good rate performance was prepared via a facile sol-gel method using ascorbic acid as carbon source. It had a uniform distribution on particle size of approximately 20 nm and a thin outlayer of carbon. The galvanostatic charge-discharge measurement showed that the Li2MnSiO4/C electrode could deliver an initial discharge capacity of 257.1 mA h g−1(corresponding to 1.56 Li+) at a current density of 10 mA g−1at 30°C, while the Li2MnSiO4electrode possessed a low capacity of 25.6 mA h g−1. Structural amorphization resulting from excessive extraction of Li+during the first charge was the main reason for the drastic capacity fading. Controlling extraction of Li+could inhibit the amorphization of Li2MnSiO4/C during the delithiation, contributing to a reversible structural change and good cycling performance.
Urchin-like Co3O4microspheres were prepared by a hydrothermal and sintering method; oxygen vacancies induce a local built-in electric field to boost battery performance.
Kinetic aspects, specifically Li-ion mobility, are found to determine the magnitude of the memory effect in TiO2 by studying samples with different levels of oxygen vacancies.
Li-Ion Batteries: Oxygen Vacancies and Ordering of d-levels Control Voltage Suppression in Oxide Cathodes: the Case of Spinel LiNi0.5
Mn1.5
O4-δ
(Adv. Funct. Mater. 44/2013)