Manipulating Stable Layered P2-Type Cathode via a Co-Substitution Strategy for High Performance Sodium Ion Batteries.

Mn-based layered transition metal oxides (TMOs) are promising cathodes for sodium ion batteries (SIBs) due to their eco-friendly character and abundant natural reserves. However, the complex phase changes and structural instability of the Mn-based layered TMO cathodes during electrochemical process are major hindrances to meet the commercial application. Cation substitution is an effective way to stabilize the structure and accelerate the Na + kinetics of cathode materials. Herein, an intriguing layered P2-type Mn-based Na 0.7 Li 0.06 Zn 0.06 Ni 0.21 Mn 0.67 O 2 material is reported by substitution of Li and Zn for partial Ni. The occupation of inert elements on Ni sites could well maintain the crystal structure, giving rise to a prominent cycle life and improved electrochemical kinetics. The as-prepared electrode presents an initial discharge capacity of 131.8 mA h g -1 at 20 mA g -1 and preserves 91.9% capacity after 100 cycles, accompanied with enexcellent rate performance (108 mA h g -1 at 500 mA g -1 ). Furthermore, the single-phase reaction mechanism during the sodiation/desodiation process is verified by in situ X-ray diffraction. Additionally, theory computations prove the decreased migration energy barriers and enhanced Na + kinetics ulteriorly. This dual-doping strategy inspires an effective way to produce high performance cathode materials for SIBs.