Ceria Heterostructure Suppresses Oxygen Release of Na-Ion Battery Cathode Materials

Abstract

Oxygen anionic redox in transition metal (TM) layered oxide cathodes can offer large extra capacity at high operating voltage. However, this oxygen-involved chemical evolution is usually accompanied by lattice oxygen release, resulting in metal dissolution, voltage fading, and capacity decay. Herein, ultrathin ceria heterostructures were constructed at the surface of the Na2/3Ni1/3Mn2/3O2 (NNM) cathode, which shared similar hexagonal atomic arrangements with the Ni/Mn layer. This phase-compatible combination could form Ce–O–TM bonding at the NNM/ceria interphase for the stabilization of lattice oxygen anions, which effectively suppresses the oxygen release in the deep desodiated state and alleviates the Ni/Mn metal dissolution. By being composited with 5% ultrathin CeO2–x , the oxygen release behavior of the NNM cathode has been successfully suppressed and the modified NNM/CE-5 cathode displays highly competitive cycling stability (75.3% capacity retention after 100 cycles at 0.5 C), excellent voltage stability and high-rate capability. This work provides a successful strategy to construct strong interphase bonding for cathode materials to stabilize anionic redox at a high operating voltage.

Ceria Quantum Dot Filler-Modified Polymer Electrolytes for Three-Dimensional-Printed Sodium Solid-State Batteries

“…The Ce 3d core spectra are displayed in Figure 1 f, and the peaks at 903 and 884 eV could be assigned to Ce 3+ 3d states. The presence of Ce 3+ valence states was attributed to the existence of oxygen vacancies in CeO 2− x , and the concentration of Ce 3+ in CeO 2− x was 19%, which could be obtained by calculating the ratio of the Ce 3+ integrated area to the total area of the Ce 3d core spectra [ 32 ].…”

“…Moreover, inorganic fillers with oxygen vacancies can accelerate the dissociation of the ion pairs in electrolyte salts (such as LiTFSI or LiClO 4 ) and release more free Li + because the oxygen vacancies are capable of serving as the Lewis acid sites to construct strong interaction with the electrolyte salt anion (such as ClO 4 − or TFSI − ), further enhancing the ionic conductivity of SPEs [ 22 , 23 , 24 , 25 ]. Taking the oxygen vacancies into consideration, ceria come into sight as a promising option for the modification of SPEs due to the existence of numerous oxygen vacancies on the surface of CeO 2− x [ 26 , 27 , 28 , 29 , 30 , 31 , 32 ].…”

“…− or TFSI − ), further enhancing the ionic conductivity of SPEs [22][23][24][25]. Taking the oxygen vacancies into consideration, ceria come into sight as a promising option for the modification of SPEs due to the existence of numerous oxygen vacancies on the surface of CeO 2−x [26][27][28][29][30][31][32].…”