Constructing micro-nano Na3V2(PO4)3/C architecture for practical high-loading electrode fabrication as superior-rate and ultralong-life sodium ion battery cathode

Abstract NASICON-structure Na3V2(PO4)3 (NVP) is a potential cathode for sodium ion battery, which however needs nano-crystallization to improve its rate performance. On the other hand, most practical electrodes are fabricated through slurry printing process, which needs to control the particle size to avoid the falling of the composite. Herein, for practical high-loading electrode fabrication, the micro-nano architecture, i.e. the micro particle plus nano channels inside, is suggested in this paper. The micro-nano information about NVP is obtained through Ga+ focused ion beam-scanning electron microscopy to reconstruct the 3D model of a single NVP particle, fully exhibiting the continuous nano channels inside the micro sphere. The as-obtained NVP/C sample in the micro size exhibits remarkable enhanced rate performance of 106, 104, 101, 96, 89, 70 and 44 mAh g−1 at rates of 2, 5, 10, 20, 50, 100 and 200 C respectively, compared to the control sample in the nano size with the capacity of 106, 103, 85, 77 and 60 mAh g−1 at 2, 5, 10, 20 and 50 C respectively, meanwhile maintaining good adhesion towards Al foil and electrochemical performance at the areal loading of 10 mg cm−2.