K doping stabilizes three-dimensional K0.2Na1.3Mn0.5O2-δ as high-performance cathode for sodium-ion batteries

• Published in: Rare metals Vol. 43; no. 10; pp. 5030 - 5038
• Main Authors: Xu, Jia-Hao, Zhu, You-Huan, Yang, Wei-Min, Cheng, Hua, Lu, Zhou-Guang
• Format: Journal Article
• Language: English
• Published: Beijing Nonferrous Metals Society of China 01-10-2024
• Subjects: Biomaterials; Chemistry and Materials Science; Energy; Materials Engineering; Materials Science; Metallic Materials; Nanoscale Science and Technology; Original Article; Physical Chemistry; Metal ion dopings; Three-dimensional structure; Sodium-ion batteries; High-performance cathode
• ISSN: 1001-0521; 1867-7185
• DOI: 10.1007/s12598-024-02814-6

It is a difficult challenge to simultaneously employ the cationic and anionic redox chemistry in cathode materials for sodium-ion batteries with high energy. Even though layered oxides (classified as two-dimensional oxides) demonstrate excellent promise in the high discharge capacity, their poor oxygen transformation via redox reactions is limited by crystal instability. Therefore, a doping strategy was conceived to tackle this issue and increase redox efficiency. K doping was applied to transform the two-dimensional Na
1.3
Mn
0.7
O
2
(NMO) to three-dimensional K
0.2
Na
1.3
Mn
0.5
O
2
(KNMO), preventing the irreversible phase shift and preserving the crystal structure’s stability while cycling. With this modification treatment, KNMO features manganese and oxygen reactive sites, delivering a promising energy density of 190 mAh·g
−1
at 5 mA·g
−1
in the 2.0–4.5 V voltage range (vs. 71.4 mAh·g
−1
for the pristine NMO). Moreover, it displays improved capacity retention of more than 83.5% after 50 cycles at 50 mA·g
−1
. The results demonstrated that doped intercalation oxides were promising for redox oxygen transformation in sodium-ion batteries.
Graphical abstract