A Volume Self-Regulation MoS2 Superstructure Cathode for Stable and High Mass-Loaded Zn-Ion Storage.

Abstract

Engineering multifunctional superstructure cathodes to conquer the critical issue of sluggish kinetics and large volume changes associated with divalent Zn-ion intercalation reactions is highly desirable for boosting practical Zn-ion battery applications. Herein, it is demonstrated that a MoS2/C19H42N+ (CTAB) superstructure can be rationally designed as a stable and high-rate cathode. Incorporation of soft organic CTAB into a rigid MoS2 host forming the superlattice structure not only effectively initiates and smooths Zn2+ transport paths by significantly expanding the MoS2 interlayer spacing (1.0 nm) but also endows structural stability to accommodate Zn2+ storage with expansion along the MoS2 in-plane, while synchronous shrinkage along the superlattice interlayer achieves volume self-regulation of the whole cathode, as evidenced by in situ synchrotron X-ray diffraction and substantial ex situ characterizations. Consequently, the optimized superlattice cathode delivers high-rate performance, long-term cycling stability (∼92.8% capacity retention at 10 A g-1 after 2100 cycles), and favorable flexibility in a pouch cell. Moreover, a decent areal capacity (0.87 mAh cm-2) is achieved even after a 10-fold increase of loading mass (∼11.5 mg cm-2), which is of great significance for practical applications. This work highlights the design of multifunctional superlattice electrodes for high-performance aqueous batteries.