As potential cathodes for sodium ion batteries, layered NaxTMO2 (0.44 ≤ x ≤ 1, TM = transition metal) materials show high specific capacities but poor cycling and rate performance. In layered NaxTMO2, the distribution of TM at crystal sites determines the electrostatic interaction between TM and the coordinated atoms and affects the electrochemical behavior. Herein, the cycling performance of P3-type Na0.67Mn0.67Ni0.33O2 materials with ordered and disordered arrangement of TMs is investigated at different rates. Unlike the TM-ordered material, the disordered one can be cycled at 2000 mA g−1 for 1500 cycles with 89% capacity retention. X-ray absorption spectroscopy is performed to elucidate the reason for long cycle life of the TM-disordered P3-type Na0.67Mn0.67Ni0.33O2 from the sight of local structural changes around Mn and Ni. The experimental results show that the structural stability of NiO6 units in the TM-disordered material is responsible for its better cycling performance in comparison with that of the TM-ordered material.
Stabilizing P3-Type Oxides as Cathodes for High-Rate and Long-Life Sodium Ion Batteries by Disordered Distribution of Transition Metals
Li J.
2020-01-01
Abstract
As potential cathodes for sodium ion batteries, layered NaxTMO2 (0.44 ≤ x ≤ 1, TM = transition metal) materials show high specific capacities but poor cycling and rate performance. In layered NaxTMO2, the distribution of TM at crystal sites determines the electrostatic interaction between TM and the coordinated atoms and affects the electrochemical behavior. Herein, the cycling performance of P3-type Na0.67Mn0.67Ni0.33O2 materials with ordered and disordered arrangement of TMs is investigated at different rates. Unlike the TM-ordered material, the disordered one can be cycled at 2000 mA g−1 for 1500 cycles with 89% capacity retention. X-ray absorption spectroscopy is performed to elucidate the reason for long cycle life of the TM-disordered P3-type Na0.67Mn0.67Ni0.33O2 from the sight of local structural changes around Mn and Ni. The experimental results show that the structural stability of NiO6 units in the TM-disordered material is responsible for its better cycling performance in comparison with that of the TM-ordered material.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
