Details

Autor(en) / Beteiligte

• Hou, Peiyu
• Dong, Mohan
• Sun, Zhenbo
• Li, Feng

Titel

Compositionally graded high-voltage P2-type cathode with superior structural stability and redox kinetics for advanced Na-ion batteries

Ist Teil von

• Nano research, 2024-04, Vol.17 (4), p.2755-2762

Ort / Verlag

Beijing: Tsinghua University Press

Erscheinungsjahr

2024

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Layered P2-type cathodes with high voltage, large capacity, and easy synthesis show great potential for developing sodium (Na)-ion batteries (NIBs). However, the P2–O2 phase transition makes their structural degradation and the Na + /vacancy ordering lowers their redox kinetics. Here, we rationally propose a compositionally graded P2-type cathode, where nickel (Ni) and manganese (Mn) fractions decrease gradually, and cobalt (Co) content increases contiguously from the inside to the outside of a secondary particle. Inside these particles, the Ni/Mn-based compound delivers high capacity and high voltage. On the surface of particles, the Co/Mn-based solid solution offers a stable buffer matrix. Benefiting from these synergistic effects, this graded P2-type cathode shows the elimination of P2–O2 transformation even when charged to 4.4 V, which enables good structural stability, maintaining capacity retention reaching ∼ 80% within 300 cycles. Moreover, the Na + /vacancy ordering superstructure is further suppressed, and the Na + diffusion kinetics is significantly improved. The proposed graded structure with optimized chemical composition offers a new perspective for eliminating the unwanted phase transition and thus enhancing the electrochemistry of high-voltage layered cathodes for advanced NIBs.