祝贺申明远等同学的文章
“Quasi-zero Volume Strain Cathode Materials for Sodium Ion Battery through Synergetic Substitution Effect of Li and Mg”
被 Advanced Functional Materials 接受发表！
Abstract
P2-type layered oxide material Na2/3Ni1/3Mn2/3O2 is a competitive candidate for sodium-ion batteries (SIBs). Nevertheless, it suffers from the strong P2-O2 phase transition during charging to the high voltage regime, rendering drastic volume variations and poor cycling performance. Here, a Quasi-zero strain P2-Na0.75Li0.15Mg0.05Ni0.1Mn0.7O2 cathode is synthesized, which reflects the vanishing P2-O2 transition with a volume change as low as 0.49%, thus resulting in the material an excellent cycling performance (83.9% capacity retention after 500 cycles at 5 C). The low-volume strain could be attributed to two aspects:1) the Mg2+ riveted in the Na layer can act as a "pillar" to stabilize the crystal structure under the condition of sodium removal, thus restricting the structural changes under high voltage. 2) the entry of Li+ into the TM layer can mitigate the electron localization in the highly desodiation state and could effectively immobilize the coordination oxygen atoms, thus suppressing the slip of P2-O2 transition. This study not only provides a new insight of Li and Mg synergetic substitution effect on the structural stability of P2-type cathode, but also an efficient avenue for developing cathode materials of SIBs with ultra-low bulk strain.
