Air/water/temperature-stable cathode for all-climate sodium-ion batteries

Abstract

The development of high-performance cathodes for sodium-ion batteries (SIBs) is one key issue required for the success of large-scale energy storage systems. In addition to performance degradation during cycling, electrode materials are usually hampered by instability when stored in various environments severely restricting their practical application. Here, we report a stable cathode material that shows no obvious capacity attenuation in various storage conditions. The cathode is composed of regular and homogeneous Na 3 V 2 (PO 4 ) 2 O 2 F 0.99 Cl 0.01 (NVPFCl) microcubes, with electrochemical properties, including high specific capacity (128.2 mA h g -1 at 0.1 C), excellent rate capability (79.8 mA h g -1 at 20 C), long-term cycle life, and all-climate performance. Studies using in/ex situ characterization and electrode kinetics are implemented to reveal the possible reasons for the stability and electrochemical activity of NVPFCl. This work may provide a pathway for the development of all-climate and storage-stable SIB cathode materials. • Regular microcube-shaped NVPFCl as cathode material for SIBs • NVPFCl can be stored in air and water and at various temperatures • Structure evolution of NVPFCl before and after storage is studied via in situ XRD • NVPFCl exhibits notable rate capability, long cycle life, and all-climate stability Gu et al. report a stable Na 3 V 2 (PO 4 ) 2 O 2 F 0.99 Cl 0.01 cathode, which exhibits negligible capacity attenuation under various storage conditions, including 26 months of exposure to air, immersion in water, and storage at high/low temperatures. It also displays competitive electrochemical properties and all-climate performance in both half and full SIBs.