Optimized Heterostructures by Preferred Crystal Orientation for Ultrafast Sodium Storage

Abstract Accelerating the Na + diffusion kinetics and enhancing the structural stability in sulfide‐based anodes by structural engineering is an extremely effective strategy for improving sodium storage performance. Herein, an optimized Co 9 S 8 /MoS 2 heterojunction with preferred crystal orientation is delicately designed and successfully fabricated. Distinguish from the conventional heterostructure with anisotropic distribution, the preferred crystal orientation with isotropic structure can provide a rapid Na + ‐diffusion pathway and regulate Na + ‐concentration to promote its uniform distribution. Furthermore, it simultaneously realizes the even dispersion of inner stress and acquire the structural stability during the discharge/charge processes. Additionally, the abundant heterointerfaces with one direction effectively improve the charge transfer and reduce the Na + ‐diffusion distance, ensuring the boosted reaction kinetic. As expected, ascribing to the synergetic effect, the Co 9 S 8 /MoS 2 presents excellent ultra‐high rate performance and long‐term cycling stability for sodium ion batteries. Specifically, a high capacity of 492.1 mAh g −1 is maintained over 2000 cycles at 2.0 A g −1 , and an ultrahigh capacity of 504 mAh g −1 is achieved even at ultrahigh rate of 15.0 A g −1 . Moreover, the assembled NVP@C//Co 9 S 8 /MoS 2 full‐cell can achieve excellent cycling performance, delivering a high capacity of 318 mAh g −1 over 500 cycles at 1.0 A g −1 .