posted on 2024-10-03, 10:04authored byXiaoqing Li, Peilin Ran, Kang Wu, Na Li, Enyue Zhao, Yanhao Huang, Feng Wang
Lithium-ion batteries (LIBs) are limited by high costs
and sustainability
issues due to their cobalt content, despite their advantages in energy
storage. Sodium-ion batteries (SIBs) emerge as a viable alternative
because of their cost-effectiveness and abundant sodium, which is
especially suitable for large-scale applications. The O3-type sodium-layered
transition-metal oxide (NaxTMO2) cathode is pivotal for enhancing energy density, cost-effectiveness,
and stability of SIBs. However, these cathodes are affected by poor
air stability and irreversible phase transitions that degrade their
electrochemical performance. To address these issues, we propose a
near-surface structural modulation strategy to convert surface alkali
residues into the fast ionic conductor Na2CaMg(PO4)2 (NCMP). This method relieved air sensitivity by forming
a protective shield around the cathode and enhanced discharge capacity
and cycling stability, demonstrating a significant increase in specific
capacity, reaching 159.7 mAh/g at 0.1 C and 106.2 mAh/g at 5 C. This
study demonstrates the effectiveness of NCMP coatings in improving
the lifetime and performance of SIBs and proposes their general applicability
in enhancing sodium-ion-layered oxide cathodes.