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The oxygen vacancy modulated LiTiOPO4‐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 LiTiOPO4‐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 LiTiOPO4‐y, which led to the partial conversion of Ti4+ to Ti3+. The capacity of LiTiOPO4 was limited (less than 161 mAh g−1) by cycling potential range (0.5–3.0 V). The oxygen‐deficient LiTiOPO4‐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 LiTiOPO4‐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 LiTiOPO4‐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. [ABSTRACT FROM AUTHOR]

Oxygen‐deficient TiP2O7‐y is synthesized by solvothermal and high‐temperature solid‐phase methods. X‐ray powder diffraction (XRD) test data analyses reveal that the solvothermal reaction time can affect the density of oxygen defects in the TiP2O7‐y. Fourier transform infrared spectra (FT‐IR) shows that there is a blue shift in the P−O bond because of the presence of oxygen vacancies. It is strongly demonstrated that oxygen vacancies exist in TiP2O7‐y because electron paramagnetic resonance (EPR) shows sharp peaks at g=2.003. Oxygen vacancy modulated TiP2O7‐y with exposed (541) face shows long cycling stability and super high‐rate capabilities. The initial discharge capacity of TiP2O7‐y, which was prepared after solvothermal reaction for 18 h, reached 828.4 mAh g−1. It can still maintain 246.9 mAh g−1, at 0.5 A g−1, after 500 cycles. Even cycled at 5 A g−1, the reversible rate capacity was maintained at 209.7 mAh g−1. Oxygen vacancies can not only improve the electronic conductivity of TiP2O7‐y but also increase the lithium‐ion diffusion rate. [ABSTRACT FROM AUTHOR]

Oxygen-deficient Li 1.3 Al 0.3 Ti 1.7 (PO 4) 3 (LATP) was prepared using a hydrothermal method followed by high-temperature calcination. Comprehensive analyses using X-ray powder diffraction (XRD), electron paramagnetic resonance (EPR), and X-ray photoelectron spectroscopy (XPS) conclusively demonstrated the successful preparation of oxygen-deficient LATPs under different calcination temperatures in an argon-hydrogen mixed atmosphere. These varying temperatures affected the concentration of oxygen defects in LATP. The hydrothermal precursor was calcined at 700 °C for 6 h to prepare an oxygen-deficient LATP, which was subsequently combined with polyacrylonitrile (PAN) to form a solid composite electrolyte. The composite exhibited a total ionic conductivity of 7.55 × 10−4 S cm−1 at 20 °C. Furthermore, when tested at 25 °C with a current density of 0.025 mA cm−2, the composite displayed good compatibility with a lithium metal anode. At a current density of 0.1 C, the initial discharge capacity was found to be 256.2 mA h g−1, which was maintained at 231.8 mA h g−1 after 100 cycles within the voltage range of 2.0–4.5 V. By judiciously modulating the oxygen defects concentration, it is possible to not only improve the ionic conductivity of the solid composite electrolyte but also to further enhance its discharge capacity. [ABSTRACT FROM AUTHOR]