Voltage Mediated Enhances Lithium‐Ion Storage in LiTiOPO4‐y with Oxygen Vacancy

Abstract The oxygen vacancy modulated LiTiOPO 4‐y was synthesized by simple hydrothermal and high‐temperature solid‐phase methods. X‐ray diffraction (XRD) test data analyses reveal that the density of oxygen defects in LiTiOPO 4‐y can be affected by the hydrothermal reaction time. The electron paramagnetic resonance (EPR) showed signal peaks at g=2.003, which proved that oxygen defects were generated. X‐ray photoelectron spectroscopy (XPS) further demonstrated that oxygen defects exist in LiTiOPO 4‐y , which led to the partial conversion of Ti 4+ to Ti 3+ . The capacity of LiTiOPO 4 was limited (less than 161 mAh g −1 ) by cycling potential range (0.5–3.0 V). The oxygen‐deficient LiTiOPO 4‐y was used to enhance lithium‐ion storage performance by mediating voltage from 0.01 to 3.0 V. The initial capacity of oxygen‐deficient LiTiOPO 4‐y , which was synthesized after hydrothermal treatment for 18 h, with an exposed (121) face, reached 563.5 mAh g −1 at the current density of 500 mA g −1 . After 1500 cycles, the specific discharge capacity kept at 397.2 mAh g −1 . In the oxygen‐defective LiTiOPO 4‐y , multiple coordination unsaturated sites are exposed, which can not only significantly enhance ion diffusion and charge transfer, but also promote Li + to more storage sites.